Polymer interlayer film with reduced yellowing

Abstract

A polymer interlayer having low tint for a multilayer panel is disclosed. The use of a polymer interlayer having low tint provides the multilayer panel with visual neutrality (low yellowness) and high visible light transmission.

Description

[Technical Field]

[0001] This disclosure relates to the field of polymer interlayers for multilayer panels and multilayer panels having at least one polymer interlayer sheet. Specifically, this disclosure relates to the field of polymer interlayers having low color and multilayer panels including polymer interlayers having low color, particularly low yellowness. [Background technology]

[0002]

[0002] Multilayer panels are generally panels composed of two substrates (e.g., but not limited to, glass, polyester, polyacrylate, or polycarbonate) sandwiched between them and one or more polymer interlayers. Multilayer laminated glass panels are commonly used in architectural window applications, as well as in automotive and aircraft windows. These applications are commonly referred to as laminated safety glass. The primary function of the interlayer in laminated safety glass is to absorb energy resulting from impact or force applied to the glass, and to keep the glass layers bonded together when force is applied and the glass breaks, preventing the glass from breaking into sharp pieces. Additionally, interlayers can, among other things, impart higher sound insulation ratings to glass, reduce ultraviolet and / or infrared light transmission, or increase the aesthetic appeal of the associated window. Interlayers can be a single layer, a combination of two or more single layers, a coextruded multilayer, a combination of at least one single layer and at least one multilayer, or a combination of multiple multilayer sheets.

[0003]

[0003] Laminated safety glass, or multiple layer glass panels, are used in many different applications in the transportation industry, including automotive, rail, and aviation. The polymer interlayers used in laminated safety glass are also used in architectural or building applications, such as window panels in buildings or stadiums, balustrades, decorative panels (in offices, etc.), etc. Such applications allow for greater creativity by incorporating color and other decorative features into the design.

[0004]

[0004] Interlayers for window, windshield, and other multiple layer glass panel applications are generally produced by mixing a polymer resin (or resins), such as poly(vinyl butyral), with one or more plasticizers and other additives and melt processing the mixture into a sheet by any applicable process or method known to those skilled in the art, including, but not limited to, extrusion. For multilayer interlayers containing two or more layers, the layers can be combined by processes such as coextrusion and lamination. Other additional components may optionally be added for various other purposes. Once formed, the interlayer sheets are typically collected and rolled for transportation and storage, and for subsequent use in multiple layer glass panels, as discussed below.

[0005]

[0005] In the process of making PVB interlayers, organic compounds may be added to the formulation along with the resin and plasticizer (and any other additives), and these organic compounds often have a specific color or a certain degree of color. During the extrusion of the interlayer, the color of the interlayer may deepen (such as yellow) or additional color may be added (for example, the process temperature may induce some additional color), which sometimes results in an interlayer with a slight yellow tint.

[0006] In the past, additives such as stabilizers and optical brighteners have been added to formulations in an attempt to reduce or eliminate yellowness or yellow tint. Additionally, attempts have been made to limit the contribution of individual components to yellowness by modifying the manufacturing process, but it is neither practical nor possible to completely eliminate the yellowness or yellow tint in this manner.

[0007]

[0007] Currently commercially available laminated safety glass with clear PVB interlayers typically have a Yellowness Index (YI) of at least about 2 (up to about 10) (where YI is measured and calculated in accordance with ASTM E1348 and E313, as further described below, using a C illuminant and a 2° observation angle (formerly D1925) on a 6.3 mm nominal thickness PVB sheet pressed between two sheets of standard clear float glass), and the interlayers with the lowest yellowness (i.e., the color closest to achromatic) measured in the CIELab color space have a yellowness index (YI) of about -1.0 or less. * values ​​and b greater than 2.0, greater than 2.5, or greater than 3.0 * These commercially available glass sheets generally have an L value greater than about 96 (measured and calculated by ASTM methods E1348 and E308 for color on PVB sheets of nominal thickness 6.3 mm). * values ​​(measured by ASTM methods E1348 and E308 for color on PVB sheet of nominal thickness 6.3 mm).

[0008]

[0008] Contemplated polymer interlayers include, but are not limited to, poly(vinyl) acetal resins, such as poly(vinyl butyral) (PVB). Multilayer laminates can include multilayer glass panels and multilayer polymer films. In certain embodiments, multiple polymer films in a multilayer laminate may be laminated together to provide a multilayer film or interlayer. In certain embodiments, these polymer films may have a coating, such as a metal, silicone, or other applicable coating known to those skilled in the art. The individual polymer films comprising the multilayer polymer film may be laminated together using adhesives known to those skilled in the art.

[0009]

[0009] The following provides a simplified, generalized description of how multiple layer glass panels, typically combined with an interlayer, are produced. First, at least one polymer interlayer sheet (single or multi-layer) is placed between two substrates, such as glass panels, and excess interlayer is trimmed from the edges to form an assembly. Particularly in architectural and / or building applications, such as windows, interior or exterior panels, balustrades, and the like, it is not uncommon to place multiple polymer interlayer sheets, or polymer interlayer sheets with multiple layers (or a combination of both) between two substrates to form a multiple layer glass panel with multiple polymer interlayers. Next, air is removed from the assembly by any applicable process or method known to those skilled in the art, for example, using nip rollers, vacuum bags, or other degassing mechanisms. Furthermore, the interlayer is partially press-bonded to the substrates by any method known to those skilled in the art. In a final step, this pre-bonding is made more permanent by a high-temperature, high-pressure lamination process, such as, but not limited to, autoclaving, or other processes known to those skilled in the art, to form the final, integrated structure.

[0010]

[0010] One of the problems in the manufacture of multilayer laminate glass panels is the presence of various optical defects and / or undesirable colors in the final unitary structure or laminate, such as a window or panel. Multilayer glass panels must be free of optical defects and have a consistent color or hue. Furthermore, multilayer glass panels must be aesthetically pleasing, i.e., the glass panels cannot have undesirable manufacturing defects. It is important to maintain high optical standards when adding new features and functionality to glass panels.

[0011]

[0011] Good optical quality and color are particularly important when multiple layer glass panels or glazings are to be used in applications requiring higher levels of optical or visual quality, such as windows. New colors and features are constantly being developed in attempts to improve multiple layer glass panels used in window and other glazing applications, particularly in attempts to make them more aesthetically pleasing to consumers. There is a need for improved interlayers for use in windows and other panels where a low yellow or neutral appearance is desirable. There is also a need for improved interlayers having very low color, particularly low yellow, tint. There is also a need for interlayers having a low yellow or neutral appearance that can be used in combination with other interlayers and different glass types in laminated glass panels. Therefore, there is a need in the art for an interlayer having a lower color or less yellowness while maintaining high visible light transmittance for use in extra-clear glazing applications without degrading the optical, mechanical, and performance properties of the interlayer. Summary of the Invention

[0012]

[0012] Due to these and other problems in the art, among others, L * , a * , and b * Disclosed herein are polymer interlayers having improved color, such as an improved combination of low color value and improved luminous transmittance (%T). In one embodiment, the interlayer comprises a poly(vinyl butyral) resin, a plasticizer, and at least one colorant, and the interlayer has improved properties, such as low color and high visible light transmittance, while also maintaining a low Yellowness Index (YI). In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has an L value of 0.01, as measured on a PVB sample having a thickness of 6.3 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab). * >94, -2.5 * <0, and 0 * Color coordinate L < 2.5​​* , a * , and b * , and has a luminous transmittance (%T, measured in accordance with ASTM D1003) of at least 85%.

[0013] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.0 and 0 * Color coordinate a <2.5 * and b * , and has a luminous transmittance (%T) of at least 85%.

[0014] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.1, and 0 * Color coordinate a <2.5 * and b * , and has a luminous transmittance (%T) of at least 85%.

[0015] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.2, and 0 * Color coordinate a <2.5 * and b * ​​​​​​and a luminous transmittance (%T) of at least 85%. * <-1.1 and 0 * <2.5, or -2.4 * <-1.2 and 0 * <2.5, or -2.3 * <-1.2 and 0 * <2.4, or -2.2 * <-1.3 and 0.5 * <2.4, or -2.1 * <-1.3 and 0.5 * <2.3, or -2.0 * <-1.5 and 1.0 * <2.0.

[0016] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.0 and 0 * Color coordinate a <2.5 * and b * , and has a luminous transmittance (%T) of at least 86%.

[0017] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.1, and 0 * Color coordinate a <2.5 * and b * , and has a luminous transmittance (%T) of at least 86%.

[0018] ​​​​​​​​​​​​​​​​In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <-1.2, and 0.5 * Color coordinate a <2.5 * and b * , and has a luminous transmittance (%T, measured in accordance with ASTM D1003) of at least 86%.

[0019] In embodiments, the poly(vinyl butyral) interlayer has a thermal conductivity of -2.3 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab) when measured on a sample having a thickness of 6.3 mm. * <-1.2 and 0 * <2.4, or -2.2 * <-1.3 and 0.4 * <2.3, or -1.9 * <-1.4 and 1.5 * Color coordinate a <2.0 * and b * It has.

[0020] In some embodiments, the poly(vinyl butyral) interlayer has a thermal conductivity of -1.5 when measured on a sample having a thickness of 3.8 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab). * <-0.95 and 0 * <1.5, or -1.5 * <-1.0 and 0.2 * <1.5, or -1.3 * <-1.0 and 0.8 * Color coordinate a <1.5 * and b * ​​​​​​​​​​​​​​and L when measured on PVB having a thickness of 3.8 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab) * ≥ 95.

[0021] In embodiments, the poly(vinyl butyral) interlayer has a luminous transmittance (% T) of at least 89% when measured for a PVB thickness of 3.8 mm (measured according to ASTM D1003).

[0022] In some embodiments, the interlayer has a thermal conductivity of -0.65 when measured on a poly(vinyl butyral) having a thickness of 1.52 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab). * <-0.45 and 0.1 * <0.8, or -0.6 * <-0.4 and 0.4 * Color coordinate a <0.8 * and b * , and L * ≥ 95.

[0023] In embodiments, the interlayer has a luminous transmittance (% T) of at least 91% when measured on a sample having a PVB thickness of 1.52 mm (measured according to ASTM D1003).

[0024] In some embodiments, the interlayer has a thickness of 0.76 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab), L * >96, -0.35 * <-0.25 and 0.05 * Color coordinate L <0.55 * , a * , and b * It has.

[0025] ​​​​​​

[0025] In several embodiments, the laminate including the interlayer has a luminous transmittance (%T) of at least 90% when measured on a laminate having a PVB interlayer having a thickness of 0.76 mm and two layers of low-iron glass each having a thickness of 4 mm, and the poly(vinyl butyral) layer has a luminous transmittance (%T) of at least 91.5% when measured on a PVB thickness of 0.76 mm (measured according to ASTM D1003).

[0026]

[0026] In several embodiments, the interlayer is a multilayer interlayer having at least two layers, or the interlayer is a multilayer interlayer having at least three layers, or the interlayer is a multilayer interlayer having more than three layers.

[0027]

[0027] In another embodiment, a transparent multilayer panel includes a first glass substrate and a second glass substrate made of extra clear float glass, and the aforementioned poly(vinyl butyral) interlayer between the first substrate and the second substrate.

[0028] In embodiments, the multilayer panel has a luminous transmittance (%T) (as measured in accordance with ASTM D1003) of at least 86%, or at least 87%, or at least 88%, or at least 89%, or at least 90%. %T is affected by the color, type, and thickness of the glass, as well as the thickness of the interlayer.

[0029] In some embodiments, the interlayer is a multi-layer interlayer having at least one layer having a thickness of 0.76 mm, or the interlayer is a multi-layer interlayer having at least two layers having a thickness of 0.76 mm.

[0030] In an additional embodiment, a method of making an improved colored poly(vinyl butyral) sheet comprises the steps of providing a poly(vinyl butyral) resin; providing a plasticizer; and providing at least one colorant in an amount sufficient to reduce the yellowness in appearance of the poly(vinyl butyral) sheet; melt blending the poly(vinyl butyral) resin, plasticizer, and colorant to produce a poly(vinyl butyral) melt blend; and extruding the poly(vinyl butyral) melt blend into a poly(vinyl butyral) sheet, wherein the poly(vinyl butyral) sheet has a color of less than 100% when measured for a sheet having a thickness of 6.3 mm (measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab). * >94, -2.5 * <0, and 0 * Color coordinate a <2.5 * and b * In other embodiments, the poly(vinyl butyral) sheet has color coordinates and %T within any of the foregoing ranges.

[0031] In some embodiments, the interlayer comprises a single layer, while in other embodiments, the interlayer comprises multiple layers, such as two layers, three layers, or four or more layers.

[0032] In certain embodiments, the rigid substrate(s) is / are glass. In other embodiments, the panel may further include a photovoltaic cell, with an interlayer encapsulating the photovoltaic cell. In other embodiments, the panel may further include a film with or without a coating, such as a reflective coating or a coating that absorbs ultraviolet light. [Brief explanation of the drawings]

[0033] [Figure 1]

[0033] Figure 1 illustrates the a* and b* coordinates of commercial PVB interlayers (measured at a nominal thickness of 6.3 mm) in laminated glazing with standard clear float glass and low iron clear float glass. ​​ [Figure 2]

[0034] FIG. 1 illustrates the a* and b* coordinates of a commercially available comparative low YI PVB interlayer (measured at a nominal thickness of 6.3 mm) in laminated glazing with standard clear float glass. [Figure 3]

[0035] FIG. 1 illustrates the a* and b* coordinates of a commercially available disclosed PVB interlayer (measured at a nominal thickness of 6.3 mm) in laminated glass with low iron clear float glass and the a* and b* coordinates of a no-glass sample for the disclosed PVB interlayer. [Figure 4]

[0036] FIG. 1 illustrates the a* and b* coordinates of four different disclosed PVB interlayers in laminated glazing with low iron glass measured at nominal thicknesses of 0.76 mm, 1.52 mm, 3.8 mm, and 6.3 mm. [Figure 5]

[0037] FIG. 1 illustrates the a* and b* coordinates of four different disclosed PVB interlayers measured at nominal thicknesses of 0.76 mm, 1.52 mm, 3.8 mm, and 6.3 mm. [Figure 6]

[0038] FIG. 1 illustrates the a* coordinates of four different disclosed PVB formulations compared to several reference PVB interlayers at different nominal thicknesses. [Figure 7]

[0039] FIG. 1 illustrates the b* coordinates of four different disclosed PVB formulations compared to several reference PVB interlayers at different nominal thicknesses. [Figure 8]

[0040] FIG. 1 illustrates the %T of four different disclosed PVB formulations compared to several reference PVB interlayers at different nominal PVB thicknesses. [Figure 9]

[0041] FIG. 1 illustrates color tuning by adding different colorants or different concentrations of colorants, and one target area of ​​a* and b* coordinates to provide a visually neutral (low yellowness) interlayer film. DETAILED DESCRIPTION OF THE INVENTION

[0034]

[0042] Described herein is an interlayer film comprised of, among other things, a thermoplastic resin, a plasticizer, and at least one additive, wherein the interlayer film has low yellowness and a neutral appearance, good optical properties, and minimal change or decrease in other properties such that the other properties are acceptable.

[0035]

[0043] The presence of a certain amount of yellowness or yellow tint in a polymer interlayer (such as PVB) can be objectionable to customers, particularly when extra clear glazing is used in applications such as architectural applications. Many commercially available PVB interlayers have a higher yellow tint than is desired for use in extra clear glazing. The inventors have discovered that it is possible to reduce the yellowness (or reduce the level of yellowness) and produce a more neutral polymer material by adding a colorant in a ratio and concentration selected so that the resulting color of the polymer (PVB) has little or no noticeable yellow tint. The addition of certain colorants to a polymer interlayer can produce a polymer material that also has high visible light transmission (or where the visible light transmission is not adversely affected by the addition of the colorant), as displayed in Figure 9 and further described below, and that has an acceptable L * a of the polymer sheet while producing an interlayer that maintains the value * and b * The value can be changed.

[0036]

[0044] In one embodiment, the poly(vinyl butyral) interlayer comprises a poly(vinyl butyral) resin and at least one plasticizer, and the interlayer has a L * >94, -2.5 * <0, and 0 * Color coordinate L < 2.5 * , a * , and b * ​​In embodiments, the interlayer has a thickness of about 0.76 mm, or about 1.52 mm, or about 3.8 mm, or about 6.3 mm or more. In embodiments, the interlayer has a viscosity of -2.5 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab) when measured for an interlayer having a thickness of 6.3 mm. * <-1.0 and 0.5 * <2.5, or -2.5 * <-1.1 and 0.5 * <2.5, or -2.5 * <-1.2 and 0.5 * <2.5, or -2.5 * <-1.3 and 0.5 * <2.5, or -2.5 * <-1.4 and 0.5 * <2.5, or -2.5 * <-1.5 and 0.5 * Color coordinate a <2.5 * and b * In some embodiments, the formula has a value of -2.4 * <-1.2 and 0 * <2.5, or -2.3 * <-1.2 and 0 * <2.4, or -2.2 * <-1.3 and 0.5 * <2.4, or -2.1 * <-1.3 and 0.5 * <2.3, or -2.0 * <-1.5 and 1.0 * <2.0. * , a * , and b * Other ranges may be applicable as desired and required for a particular use or application.

[0037]

[0045] ​​​​​​​​​​​​​​​​​​​​​​In some embodiments, the multilayer panel has a L (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab) when measured on a laminate with a PVB interlayer having a thickness of 6.3 mm. * In some embodiments, the multilayer panel has an L ≥ 94 when measured on a laminate with a PVB interlayer having a thickness of 0.76 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab). * ≥ 96.

[0038]

[0046] In embodiments, the interlayer is a multilayer interlayer having at least two layers, or the interlayer is a multilayer interlayer having at least three layers, or the interlayer is a multilayer interlayer having more than three layers.

[0039]

[0047] In embodiments, the multilayer panel has a luminous transmittance (% T) of at least 86 (as measured according to ASTM D1003).

[0040]

[0048] The use of a poly(vinyl acetal) resin, such as a poly(vinyl butyral) resin, a plasticizer, and at least one colorant (in appropriate amounts) produces an interlayer film that, when melt extruded, has a neutral or low yellow appearance without sacrificing other optical and physical properties. As used herein, "lower tint," "lower yellowness," "colorless," and "neutral" refer to a less yellow appearance and a particular a color, such that the sheet also has low yellowness and good luminous transmittance. * , b * , and L * having colors centered around the value, preferably b * >0 and a * <0. The terms lower tint, lower yellowness, colorless, and achromatic all refer to visual yellowness or yellowness (or lack thereof) and may be used interchangeably throughout this description.

[0041]

[0049] As previously mentioned, attempts to impart a less yellow appearance to interlayers have been made by adding additives such as stabilizers and optical brighteners to formulations with the intention of reducing yellowness or yellow tint. Examples of previous attempts to reduce yellowness can be found, for example, in Liu, R., He, B. & Chen, X. 2008. Degradation of poly(vinyl butyral) and its stabilization by bases. Polymer Degradation and Stability 93(4):846-853; U.S. Patent Application Publication No. 20140371356; and U.S. Patent No. 5,573,842. Adding optical brighteners, often considered "blue" compounds, to compensate for or reduce yellowness often results in the resulting polymer appearing green. Furthermore, attempts have been made to limit the contribution of individual components to yellowness by modifying the manufacturing process, but it is impractical to completely eliminate yellowness or yellow tint in this manner. Adding some pigment, dye, or colorant, or excessive amounts of pigment, dye, and / or colorant, while sometimes reducing the yellowness or yellowness, can also reduce the luminous transmittance (%T) beyond levels desirable or acceptable in a particular application.

[0042]

[0050] The inventors also maintained a %T of at least 85% and achieved high L * It also has a value and a color (L * , a * , and b * value) and changes the yellow appearance (b *It has been discovered that it is possible to reduce the visual color (determined by the YI value) and produce a more neutral PVB material. Improved interlayers are produced by adding certain colorants to other ingredients (such as PVB and plasticizers) in ratios and concentrations selected so that the resulting color of the PVB has a low visual color (yellow) appearance and a %T > 86% (measured at a nominal PVB thickness of 6.3 mm as described herein). Polymer interlayers with good optical quality and improved color (lower color or more neutral) may be produced. The use of the addition of certain colorants can improve the L of the PVB sheet, as further described below. * , a * , and b * It is possible to control the value and %T.

[0043]

[0051] Figure 9 shows how the color of PVB can be adjusted or changed by adding certain additives such as colorants. As shown in Figure 9, the color coordinates can be controlled, and a colorless polymer sheet can be produced when the appropriate amount of additives is added, where a * is less than 0, and b * is greater than 0. By adding a certain amount of colorant, a * and b * The value can be adjusted (increased or decreased) to reach an optimum level as desired or required for the application.

[0044]

[0052] The PVB samples were laminated onto 2mm thick standard float glass and * and b * The values ​​were measured as described herein. As shown in Figures 4 and 5, it is possible to produce interlayers with lower or neutral color for various nominal PVB thicknesses ranging from 0.76 mm to 6.3 mm. Interlayers were measured for various thicknesses as shown in the table. The color difference, and therefore the improvement, is more easily discernible at higher PVB thickness levels. As shown in Figures 4-8, having a thicker PVB results in higher a * and b *, thus leading to more obvious color distinctions. If there are slight or small color differences between samples, they may only be distinguishable at large PVB thicknesses.

[0045]

[0053] The presence of glass, even low-iron glass, adds color to the multi-layer panel. This is evident in the a of the laminated glazing with PVB sample shown in Figure 4. * The values ​​were compared with a for the same PVB sample in Figure 5 but without glass. * This is demonstrated by comparing the a of the PVB samples in glass. * The values ​​are for the PVB samples without glass. * By carefully controlling the type and amount of colorant, the color of the final PVB can be adjusted or controlled to be less yellow and more neutral. Adding a higher concentration of colorant results in a lower L * and %T values, which may be undesirable in applications where high luminous transmission (%T of at least 80%, or at least 85%) is required.

[0046]

[0054] As shown in Figures 4 to 8, a * and b * The data are for different formulations at each thickness. * and b * Plotting the coordinates shows that the color measurement response is more pronounced at larger PVB thicknesses. At a nominal thickness of 6.3 mm, the color response is visually imperceptible or barely distinguishable (or nearly identical) to the sample with a nominal thickness of 0.76 mm. * and b * (Samples with values) The color difference between some interlayers is perceived visually.

[0047]

[0055] Several terms used throughout this application will be explained to provide a better understanding of the present invention. As used herein, the terms "polymer interlayer sheet," "interlayer," and "polymer melt sheet" may generally refer to a monolayer sheet or a multilayer interlayer. A "monolayer sheet," as the name suggests, is a single polymer layer extruded as a single layer. On the other hand, a multilayer interlayer may include multiple layers, including separately extruded layers, coextruded layers, or any combination of separately extruded and coextruded layers. Thus, a multilayer interlayer can include, for example, two or more combined monolayer sheets (multilayer sheets), two or more coextruded layers (coextruded sheets), two or more combined coextruded sheets, a combination of at least one monolayer sheet and at least one coextruded sheet, and a combination of at least one multilayer sheet and at least one coextruded sheet. In various embodiments of the present disclosure, a multilayer interlayer includes at least two polymer layers (e.g., a monolayer or coextruded multiple layers) disposed in direct contact with each other, wherein each layer includes a polymer resin, as described more fully below. As used herein, "skin layer" generally refers to the outer layer of a multilayer interlayer, and "core layer" generally refers to the inner layer. Thus, one exemplary embodiment is skin layer / / core layer / / skin layer. However, it should be noted that further embodiments include interlayers having more than three layers (e.g., 4, 5, 6, or even 10 individual layers). Furthermore, any utilized multilayer interlayer can be varied by manipulating the layer composition, thickness, or arrangement, etc. For example, in a three-layer polymer interlayer sheet, the two outer or skin layers may comprise poly(vinyl butyral) ("PVB") resin with a plasticizer or a mixture of plasticizers, while the inner or core layer may comprise the same or different PVB resin or a different thermoplastic material with a plasticizer and / or a mixture of plasticizers. Thus, it is contemplated that the skin and core layers of a multilayer interlayer sheet may be composed of the same or different thermoplastic materials.Either or both layers may optionally contain additional additives known in the art.

[0048]

[0056] Although the embodiments described below refer to a polymer resin that is PVB, it will be understood by those skilled in the art that the polymer may be any poly(vinyl acetal) polymer suitable for use in multilayer panels. PVB is particularly desirable when used with interlayers of the present disclosure for use in window and other glazing applications.

[0049]

[0057] Some common components found in both interlayers generally and those disclosed herein, and their formation, are discussed below. PVB resins are produced by known aqueous or solvent acetalization processes, involving the reaction of polyvinyl alcohol ("PVOH") with butyraldehyde in the presence of an acid catalyst, followed by isolation, 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. 1-22 (online, copyright 2016 John Wiley & Sons, Inc.), the entire disclosures of which are incorporated herein by reference. This resin is commercially available in various forms, such as Butvar® resin from Eastman Chemical Company.

[0050]

[0058] As used herein, residual hydroxyl content (calculated as PVOH) refers to the amount of hydroxyl groups remaining on the polymer chain after processing is complete. For example, PVB can be produced by hydrolyzing poly(vinyl acetate) to PVOH and then reacting the PVOH with butyraldehyde. In the process of hydrolyzing poly(vinyl acetate), typically not all of the acetate side groups are converted to hydroxyl groups. Furthermore, the reaction with butyraldehyde typically does not result in all of the hydroxyl groups being converted to acetal groups. As a result, in any finished poly(vinyl butyral) resin, there are typically residual acetate groups (as vinyl acetate groups) and residual hydroxyl groups (as vinyl hydroxyl groups) as side groups on the polymer chain. As used herein, residual hydroxyl content is measured on a weight percent basis according to ASTM 1396.

[0051]

[0059] In various embodiments, the poly(vinyl butyral) resin contains from about 8 to about 35 weight percent (wt%) hydroxyl groups, calculated as PVOH, depending on the desired properties of the interlayer. In embodiments, the resin (or at least one resin) may contain from about 10 to 30 wt%, or from about 15 to 25 wt%, hydroxyl groups, calculated as PVOH, although other amounts are possible depending on the desired properties. The resin may also contain polyvinyl esters, e.g., less than 15% by weight residual ester groups, calculated as acetate, less than 13% by weight, less than 11% by weight, less than 9% by weight, less than 7% by weight, less than 5% by weight, or less than 1% by weight residual ester groups, the remainder being acetals such as butyraldehyde acetal, but optionally other acetal groups such as 2-ethylhexanal acetal groups, or mixtures of butyraldehyde acetal, isobutyraldehyde acetal, and 2-ethylhexanal acetal groups (see, e.g., U.S. Pat. No. 5,137,954, the entire disclosure of which is incorporated herein by reference).

[0052]

[0060] For a given type of plasticizer, the compatibility of the plasticizer in the polymer is primarily determined by the polymer's hydroxyl content. Polymers with greater residual hydroxyl content are typically associated with decreased plasticizer compatibility or capacity. Conversely, polymers with lower residual hydroxyl content typically provide increased plasticizer compatibility or capacity. In general, this correlation between the polymer's residual hydroxyl content and the plasticizer's compatibility / capacity can be manipulated and utilized to allow for the addition of appropriate amounts of plasticizer to the polymer resin and to maintain consistent plasticizer content differences between multiple interlayers.

[0053]

[0061] The PVB resin(s) of the present disclosure typically have a molecular weight greater than 50,000, from about 50,000 to about 500,000 daltons, from about 70,000 to about 500,000 daltons, from about 80,000 to about 250,000 daltons, less than about 500,000 daltons, or less than about 250,000 daltons, as measured by size exclusion chromatography using low angle laser light scattering. As used herein, the term "molecular weight" refers to weight average molecular weight.

[0054]

[0062] Other additives may be added to the interlayer to improve its performance in the final product or to impart specific additional properties to the interlayer, so long as the additives do not adversely affect the desired color and other properties. Such additives include, but are not limited to, adhesion control agents ("ACA"), dyes, other pigments (such as colored pigments or titanium dioxide), stabilizers (e.g., UV stabilizers), antioxidants, antiblocking agents, flame retardants, infrared absorbers or shielding agents (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB6), and cesium tungsten oxide), processing aids, flow promoters, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, toughening additives, and fillers, among other additives known to those skilled in the art.

[0055]

[0063] In various embodiments of the interlayer film of the present disclosure, the interlayer film contains from about 5 to about 100 phr (parts per hundred parts of resin) of total plasticizer. In embodiments, the interlayer film may contain at least 10, at least 15, at least 20, at least 25, or at least 30 phr or more of plasticizer. In embodiments, the interlayer film may contain less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, or less than 50 phr of plasticizer. As used herein, the amount of plasticizer or any other component in an interlayer film can be measured on a weight / weight basis as parts per hundred parts of resin (phr). For example, if 30 grams of plasticizer is added to 100 grams of polymer resin, the plasticizer content of the resulting plasticized polymer will be 30 phr. When the plasticizer content of an interlayer film is given herein, the plasticizer content is determined with reference to the phr of plasticizer in the melt used to produce the interlayer film.

[0056]

[0064] Examples of plasticizers suitable for use in these interlayers include esters of polybasic acids or polyhydric alcohols, among others. Suitable plasticizers include, for example, triethylene glycol di(2-ethylhexanoate) ("3GEH"), tetraethylene glycol di(2-ethylhexanoate), triethylene glycol di(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and mixtures thereof. In some embodiments, the plasticizer is 3GEH.

[0057]

[0065] In other embodiments, high refractive index plasticizers may be used alone or in combination with other plasticizers, such as 3GEH. As used herein, a "high refractive index plasticizer" is a plasticizer with a refractive index of at least about 1.460. Commonly used plasticizers, such as 3GEH, have a refractive index of about 1.442, while many other conventional plasticizers have a refractive index of about 1.442 to about 1.449. Examples of high refractive index plasticizers that may be used in polymer interlayers include, but are not limited to, polyadipates (RI of about 1.460 to about 1.485), epoxides, such as epoxidized soybean oil (RI of about 1.460 to about 1.480), phthalates and terephthalates (RI of about 1.480 to about 1.540), benzoates (RI of about 1.480 to about 1.550), and other specialty plasticizers (RI of about 1.490 to about 1.520). The refractive index of poly(vinyl butyral) resin is approximately 1.485 to 1.495. Examples of high refractive index plasticizers include, but are not limited to, esters of polybasic acids or polyhydric alcohols, polyadipates, epoxides, phthalates, terephthalates, benzoates, toluates, mellitates, and other specialty plasticizers, among others. Examples of suitable plasticizers 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-ethylhexanoate), ethoxylated nonylphenol, and mixtures thereof.In some embodiments, examples of high refractive index plasticizers are dipropylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, and tripropylene glycol dibenzoate.

[0058]

[0066] It is contemplated that the polymer interlayer sheets described herein may be produced by any suitable process known to those skilled in the art of producing polymer interlayer sheets that can be used in multilayer panels (such as glass laminates or glass panels). For example, it is contemplated that the polymer interlayer sheets may be formed by solution casting, compression molding, injection molding, melt extrusion, meltblowing, or any other procedure for producing and manufacturing polymer interlayer sheets known to those skilled in the art. Furthermore, in embodiments utilizing multiple polymer interlayers, it is contemplated that these multiple polymer interlayers may be formed by coextrusion, blown film, dip coating, solution coating, blade, puddle, air knife, printing, powder coating, spray coating, or other processes known to those skilled in the art. While all methods for producing polymer interlayer sheets known to those skilled in the art are contemplated as possible methods for producing the polymer interlayer sheets described herein, this application focuses on polymer interlayer sheets produced by extrusion and coextrusion processes. The final multilayer glass panel laminate of the present invention is formed using processes known in the art.

[0059]

[0067] Generally, in its most basic sense, extrusion is a process used to produce objects of a defined cross-sectional shape. This is accomplished by forcing or drawing material through a die having the desired cross-section of the final product. Typically, in an extrusion process, a thermoplastic resin and plasticizer, including any resins, plasticizers, and other additives described above, are premixed and fed into an extruder. Optional additives, such as colorants and UV inhibitors (in liquid, powder, or pellet form), are often used and can be mixed into the thermoplastic resin or plasticizer before reaching the extruder. These additives are incorporated into the thermoplastic polymer resin and stretched to enhance certain properties of the resulting polymer interlayer sheet and its performance in the final multilayer glass panel product.

[0060]

[0068] In the extruder, the thermoplastic raw material particles, plasticizer, pigment, and any other additives mentioned above are further mixed and melted to obtain a melt that is generally uniform in temperature and composition. When the melt reaches the end of the extruder, it is forced into an extrusion die. The extrusion die is the component of the thermoplastic extrusion process that gives the final polymer interlayer sheet product its outer shape. Generally, the die is designed to allow the melt to flow uniformly from the cylindrical outer shape emerging from the die to the final outer shape of the product. As long as a continuous outer shape exists, the die can impart multiple shapes to the final polymer interlayer sheet.

[0061]

[0069] The polymer interlayer film in its state after the extrusion die forms the melt into a continuous shape is called a "polymer melt sheet." At this stage of the process, the extrusion die imparts a specific shape to the thermoplastic resin, forming a polymer melt sheet. The polymer melt sheet has a high viscosity throughout and is generally in a molten state. In the polymer melt sheet, the melt has not yet cooled to a temperature at which the sheet generally "solidifies." Therefore, after the polymer melt sheet leaves the extrusion die, the next step in currently employed thermoplastic extrusion processes is generally to cool the polymer melt sheet using a cooling device. Cooling devices used in conventional processes include, but are not limited to, spray jets, fans, cooling baths, and cooling rollers. The cooling step serves to solidify the polymer melt sheet into a polymer interlayer film sheet with a generally uniform, non-melt cooling temperature. In some embodiments, the polymer melt sheet may be embossed as previously described after leaving the die and before the cooling step. In contrast to the polymer melt sheet, this polymer interlayer film sheet is not in a molten state and is not highly viscous. Rather, it is the solidified, final-form cooled polymer interlayer sheet product. For purposes of this application, this solidified and cooled polymer interlayer will be referred to as the "polymer interlayer sheet."

[0062]

[0070] In some embodiments of the extrusion process, a coextrusion process may be utilized. Coextrusion is a process in which multiple layers of polymeric materials are extruded simultaneously. This type of extrusion typically uses two or more extruders to melt and feed different thermoplastic melts having different viscosities or other properties at a constant volumetric throughput through a coextrusion die to a desired final form. The thickness of the multiple polymer layers leaving the extrusion die in a coextrusion process can generally be controlled by adjusting the relative speed of the melts through the extrusion die and the size of the individual extruders processing each molten thermoplastic resin material.

[0063]

[0071] Generally, the thickness or gauge of either the polymer interlayer sheet or layer or interlayer can be at least about 2, at least about 5, at least about 10, at least about 15, or at least about 20 mils and / or not more than about 120, not more than about 100, not more than about 90, not more than about 60, not more than about 50, or not more than about 35 mils, or can range from about 2 to about 120, about 10 to about 100, about 15 to about 60, or about 20 to about 35 mils, although other thicknesses may be suitable depending on the desired properties and / or application. In millimeters, the thickness of the polymer layer or interlayer can be at least about 0.05, at least about 0.13, at least about 0.25, at least about 0.38, at least about 0.51 mm, and / or not more than about 2.74, not more than about 2.54, not more than about 2.29, not more than about 1.52, or not more than about 0.89 mm, or in the range of about 0.05 to 2.74, about 0.25 to about 2.54 mm, about 0.38 to about 1.52 mm, or about 0.51 to about 0.89 mm, although other thicknesses may be suitable depending on the desired properties and / or application.

[0064]

[0072] As described above, the interlayers of the present disclosure may be used as single or multi-layer sheets. Interlayers with improved or reduced yellowness may be used in conjunction with one or more clear or tinted interlayers to achieve the desired laminate color and appearance. In various embodiments, the interlayers of the present disclosure (either as single or multi-layer sheets, or as one or more layers of the same or different materials) can be incorporated into multi-layer panels, such as clear multi-layer panels, with various types of glass, such as low-iron glass or standard float glass.

[0065]

[0073] As used herein, a multilayer panel can include a single substrate, such as glass, acrylic, or polycarbonate, upon which a polymer interlayer sheet is disposed, most commonly a polymer film disposed on top of the polymer interlayer. The combination of a polymer interlayer sheet and a polymer film is commonly referred to in the art as a bilayer. A typical multilayer panel having a bilayer configuration is (glass) / / (polymer interlayer sheet) / / (polymer film), where the polymer interlayer sheet can include multiple interlayers as described above. The polymer film provides a smooth, thin, and rigid substrate, which can impart better optical properties than those typically achieved with a polymer interlayer sheet alone, functioning as a performance-enhancing layer. Polymer films, as used herein, differ from polymer interlayer sheets in that the polymer film itself does not provide the necessary puncture resistance and glass retention properties, but does improve performance, such as infrared absorption properties. Poly(ethylene terephthalate) (“PET”) is the most commonly used polymer film.

[0066]

[0074] The interlayers of the present disclosure are most commonly utilized in multilayer panels that include two substrates, preferably a pair of glass sheets (or other rigid materials known in the art, such as polycarbonate or acrylic), with an interlayer disposed between the two substrates. An example of such a structure is (glass) / / (polymer interlayer sheet) / / (glass), where the polymer interlayer sheet can include a multilayer interlayer or multiple different single-layer or multilayer interlayers as described above, and at least one of the polymer interlayers (or layers therein) includes an improved interlayer. These examples of multilayer panels are in no way intended to be limiting, and one skilled in the art will readily recognize that numerous structures other than those described above can be formed using the interlayers of the present disclosure.

[0067]

[0075] A typical glass lamination process includes the steps of (1) assembling two substrates (e.g., glass) and an interlayer; (2) briefly heating the assembly with an infrared source or convection means; (3) passing the assembly through pressure nip rolls for a first degassing; (4) subjecting the assembly to a second heating step, such as at a temperature of about 70°C to about 120°C, to provide the assembly with a temporary bond sufficient to seal the edges of the interlayer; (5) passing the assembly through a second pressure nip roll to further seal the edges of the interlayer for further handling; and (6) autoclaving the assembly for about 30 to 90 minutes, for example, at a temperature between 135°C and 150°C and a pressure between 150 psig and 200 psig.

[0068]

[0076] One parameter often used to describe polymer interlayers is transparency, which is determined by measuring the haze value or percent haze (% Haze). Light scattered as it passes through a film or sheet of material can produce a cloudy or cloudy area when an object is viewed through the material. Thus, the haze value is a quantification of the light scattered by a sample compared to the incident light. Testing for percent haze is performed using a spectrophotometer such as the Ultrascan XE or Ultrascan PRO, available from Hunter Associates (Reston, VA), according to ASTM D1003-13, Procedure B, using a C illuminant at a 2° observation angle.

[0069]

[0077] The interlayers of the present disclosure also have a luminous transmittance (%T) of at least 85%, or at least 86%, or at least 85-95% or more (as measured by a HunterLab Ultrascan XE), depending on the thickness of the PVB and the type of glass used. In embodiments, the %T may be at least 86%, at least 87%, at least 88%, at least 89%, or at least 90% or more. In embodiments, the interlayers of the present disclosure have an a of about -0.2 when the interlayer is a single layer or monolayer (target or nominal thickness 0.76 mm). *and b of about 0.4 * Other values ​​may be used depending on the desired color level, thickness, end use, and other factors. [Example]

[0070]

[0078] Samples of interlayer sheets with reduced yellowness were produced by blending and melt-extruding PVB resin, plasticizer, and colorant, along with other common additives (including adhesion control agents and UV stabilizers). The blend was extruded to form an interlayer sheet with a target or nominal thickness of approximately 0.76 mm (30 gauge (30 mil)).

[0071]

[0079] To test the resulting interlayers, multiple layers of the disclosed visually neutral, commercially available, clear, comparative low YI PVB interlayers were stacked and pressed together to measure YI, %T, and L. * a * b * A target thickness was formed for the measurement of values. Ten layers were stacked to create an interlayer having a target or nominal thickness of approximately 6.3 mm. Five layers were stacked for a target thickness of 3.8 mm, and two layers were stacked for a target thickness of 1.52 mm. The stacked interlayers were then pressed together to the target thickness, as further described below. A single layer of PVB (target or nominal thickness of 0.76 mm) was also measured, as shown below. The actual PVB thickness of each measured interlayer is shown in the table. In some cases, where indicated in the table, the values ​​have been corrected for the PVB thickness, as further described below.

[0072]

[0080] In some tables, properties of PVB interlayers (without glass) are displayed. These values ​​were obtained by collecting data on PVB samples (having the thickness shown in the table) where no glass was present during the sample measurements. In other tables, measurements were made on glass laminates (PVB samples laminated between two pieces of glass (standard float glass or low iron glass, as described below)).

[0073]

[0081] The following procedure (Procedure 1) was used to obtain PVB samples at the desired thickness for measurement. To obtain a PVB sample of the desired thickness (other than a single layer or single-layer sheet), multiple layers of PVB were pressed (or autoclaved) between two pieces of glass (as is conventional and known to those skilled in the art). The PVB layers were first stacked (2, 5, or 10 layers) and placed between two pieces of glass, with a polyester (PET or other similar material) sheet (not attached to the PVB or glass) placed at each glass / PVB interface so that the glass could be peeled from the PVB sheet for measurement after the PVB was pressed to the desired thickness (6.3, 3.8, or 1.52 mm nominal thickness). The stack had a glass / PET / PVB / PET / glass configuration. Once the stack was pressed or autoclaved, the glass and PET sheets were removed by peeling them from the PVB, leaving a pressed PVB sample without glass. The PVB sample was then measured as follows:

[0074]

[0082] For measurements in glass laminates (or glass panes), a standard lamination procedure known to those skilled in the art was used (Procedure 2): The interlayer (or a stack of 2 or 5 layers) was placed between two pieces of glass of the desired type (low iron float or standard float) and size, pre-pressed to remove air, and laminated. For 10-layer samples, the interlayer was placed between two pieces of glass of the desired size and type, placed between a mechanical press, and fused to the target PVB thickness. The stacked laminate had a glass / PVB / glass configuration. The laminate was then measured as follows:

[0075]

[0083] Glass color and PVB color were measured and calculated by the same method according to ASTM Methods E1348, Ill. D65 / 10° Obs. CIELab., and ASTM E308. YI was measured and calculated according to the methods of ASTM E1348 and E313 (formerly D1925) using illuminant C at a 2° observation angle. Haze (% Haze) and luminous transmittance (% T) were measured according to Procedure B of ASTM D1003-13 using illuminant C at a 2° observation angle. Glass and PVB thicknesses were measured with a calibrated slider used for thickness measurement (but may be measured by any method or device known in the art).

[0076]

[0084] Table 1 shows the color properties of standard commercial PVB using 10 layers in combination with two different types of glass (4 mm low-iron float glass or 2 mm standard clear float glass), and the color properties of single-ply or single-ply PVB samples in combination with low-iron clear float glass. The laminates were made using Procedure 2 described above. The measured YI was corrected for the thickness of the PVB as follows: [YI corrected =(YI measured x nominal thickness) / PVB thickness]. Corrections for thickness can be made by adding L * , a * , b * , and %T. As shown in Figures 6, 7, and 8, a * , b * The %T values ​​are linearly proportional to the thickness of the PVB. As the PVB interlayer becomes thicker, the b * The value is high, a * , L * , and %T will be lower. For each type of laminate, samples with the same name (i.e., Standard Clear 1, Standard Clear 2) are of the same material.

[0077]

[0085] In Tables 1 to 6, L * , a * , b *, and %T values ​​are not corrected for the nominal thickness of the PVB. In Tables 1 and 3, YI is corrected for a nominal thickness of 6.3 mm. In Tables 2 and 4-6, no correction for thickness is applied.

[0078] [Table 1]

[0086] As shown by the data in Table 1, glass laminates with PVB having a target thickness of 6.3 mm exhibited a porosity of -1.4 to -2.7 when laminated in low iron glass. * value and b of 3.6~7.0 * Using standard clear float glass (target PVB thickness 6.3 mm), a * The values ​​are lower, ranging from -2.5 to -3.8, but b * The values ​​remain roughly the same. The lower a * The values ​​show that the color of the laminate in standard clear float glass is slightly greener compared to the laminate made with low iron glass, which is also expected based on the color of the glass itself.

[0079]

[0087] Table 2 shows the glass color (L * a * b * ) is shown.

[0080] [Table 2]

[0088] a in Table 1 * and b * Color data are typical values ​​for laminate samples with standard commercial PVB interlayers. * and b * PVB has a yellow tint (or high yellowness index), as indicated by YI values ​​ranging from about 4.0 to 10.0. There may be interlayers used in laminates with lower YI values ​​than those measured in Table 1, but they are not readily available and have not been tested.

[0081]

[0089] Furthermore, in Table 1, the color of laminates made using standard commercially available clear PVB and using one layer of PVB in combination with 4 mm of low-iron glass tend to be the same as the 10-layer samples. The distinction between samples with only one layer of PVB is less clear because the signal-to-noise ratio becomes very small at smaller PVB thicknesses. Stated differently, using thicker layers or samples of PVB provides better distinction between samples when measuring color.

[0082]

[0090] Decreased color (lower Yellowness Index or YI) and a value close to 0, except that additional colorant was added in an amount sufficient to reduce the yellowness as described above. * and b * Comparative low YI interlayer samples, as well as those having lower %T, were produced as described above. Table 3 shows the properties of comparative interlayers prepared according to Procedure 2 using 2 mm thick clear float glass as described above.

[0083] [Table 3]

[0091] As shown in Table 3, the a of the sample with comparative low YI PVB * and b * The values ​​are lower than those shown in Table 1 for samples with the same glass type and thickness of commercial PVB, indicating that the comparative PVB is less yellow than the commercial PVB. Also, the comparative PVB has a lower L than the commercial PVB. * and low %T values ​​(less than 80% for PVB of 6.3 mm nominal thickness), which reduces the yellowness and improves the %T and L * The values ​​also show a decrease to levels that are undesirable in some applications where high levels of transmission (%T) are required.

[0084]

[0092] Table 4 shows data collected directly without the presence of glass (following Procedure 1 above) for commercially available comparative low YI PVB samples (single and 10 ply). * a * b *) differs from the number measured when the sample is laminated between two pieces of glass. When measuring a PVB sample directly, there is no glass color contribution, and the PVB and glass have different reflectance properties. * , a * , and b * The main trends in values ​​are similar for both laminated and unlaminated samples. For both sample types, color is much more apparent at larger PVB thicknesses for the standard commercial clear PVB and the comparative low YI PVB. For both sample types measured, L * and %T decrease with increasing thickness, while YI and b * The impact on

[0085] [Table 4]

[0093] Tables 5 and 6 show the properties of the disclosed visually neutral (less yellowish) PVB (CN PVB) samples, both laminated with 4 mm low-iron glass (Table 5) and without glass present (Table 6), using 10, 5, 2, or 1 layer prepared according to Procedures 1 and 2 above. Samples labeled CN1-4 exhibited a color similar to that described above and shown in FIG. 9. * and b * Different formulations with different amounts or levels of colorant to adjust or change the value.

[0086] [Table 5]

[0094] Table 5 shows that all laminates with a nominal PVB thickness of 6.3 mm (in 4 mm low iron glass) had luminous transmittance (%T) values ​​of at least 86% and L values ​​of greater than 94. * At a nominal thickness of 3.8 mm (in 4 mm low iron glass), all laminates containing the disclosed samples have a %T of at least about 87.5% and an L of greater than about 95.0. * All laminates with a nominal PVB thickness of 1.52 mm (in 4 mm low iron glass) had %T values ​​of approximately 90% and L values ​​of approximately 96%.* All laminates with PVB samples of nominal thickness of 0.76 mm (in 4 mm low iron glass) had %T greater than 90% and L greater than 96. * All disclosed PVB samples at all thicknesses have a value of less than 0. * value and b greater than 0 * Specifically, laminates with PVB samples having a target thickness of 6.3 mm had a range of a from -1.79 to -2.48. * value and PVB b in the range of 0.75 to 2.57 * At a target thickness of 3.8 mm, the laminate a * The values ​​range from -1.32 to -1.94, and b * The values ​​range from 0.41 to 1.70. For the 1.52 mm PVB sample, a * The values ​​range from -0.80 to -1.01, PVB b * The values ​​range from 0.37 to 0.89, but for the PVB sample with a nominal thickness of 0.76 mm, a * The values ​​range from -0.59 to -0.69, PVB b * The values ​​range from 0.30 to 0.55. Additionally, Table 5 shows that all disclosed samples have excellent low haze values ​​(haze <0.4% for the four disclosed CN formulations), which is similar to laminates containing standard commercially available clear PVB interlayers.

[0087] [Table 6]

[0095] Table 6 shows that all of the disclosed visually neutral samples with a nominal PVB thickness of 6.3 mm had %T values ​​of at least 86% and L values ​​of greater than 94.5. * At a nominal thickness of 3.8 mm, all disclosed PVB samples have a minimum %T of about 89% and an L of greater than about 95.5. * All samples with a nominal PVB thickness of 1.52 mm had a %T of at least 91% and an L of greater than 96.4. * All samples with a nominal thickness of 0.76 mm had a %T greater than 91.1% and an L greater than 96. *All PVB samples at all thicknesses had a value less than 0. * value and b greater than 0 * Specifically, in a sample having a target thickness of 6.3 mm, PVB a * The values ​​range from -1.64 to -2.50, PVB b * The values ​​ranged from 0.49 to 2.66, and at a target thickness of 3.8 mm, PVB a * The values ​​range from -0.95 to -1.44, and the PVB b ranges from 0.45 to 1.60. * At a nominal thickness of 1.52 mm, PVB a * The values ​​range from -0.43 to -0.64, PVB b * The values ​​range from 0.36 to 0.83, and finally, for the PVB sample with a nominal thickness of 0.76 mm, the PVB a * The values ​​range from -0.24 to -0.33, PVB b * The values ​​range from 0.26 to 0.54.

[0088]

[0096] As shown in Tables 5 and 6, at all thicknesses, the disclosed visually neutral PVB samples exhibited higher L than the commercial clear and comparative low YI PVB samples in Tables 1 and 3. * and %T values. The %T of the disclosed visually neutral PVBs is relatively low compared to the PVB a * and b * The YI value is higher (86.3% compared to only 80.6% at 6.3 mm PVB thickness for the comparative low YI PVB) while also achieving low yellowness.

[0089]

[0097] The %T and color data in Tables 5 and 6 (and as shown in Figures 6-8) demonstrate that it is possible to control visual color with limited impact on luminous transmittance (%T) by adding colorants to provide polymer interlayers with improved color and a visually neutral appearance. As shown in Figures 6-8, the PVB a of the disclosed interlayers * and b *The values ​​are in a distinct range compared to standard commercial clear and comparative low YI PVBs. The improved colorless interlayer has less yellowness and improved appearance compared to standard commercial interlayers and other comparative low yellowness interlayers.

[0090]

[0098] In conclusion, polymer interlayers with a lower yellow tint as described herein have advantages over polymer interlayers with higher levels of color because they can be more aesthetically pleasing. Other advantages will be readily apparent to those skilled in the art.

[0091]

[0099] While the invention has been disclosed with reference to particular embodiments, including what are currently considered to be preferred embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the disclosure. As will be understood by those skilled in the art, embodiments other than those specifically described herein are encompassed by the present invention. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention.

[0092]

[0100] Furthermore, it is understood that any range, value, or characteristic provided for any single component of this disclosure can be used interchangeably, where applicable, with any range, value, or characteristic provided for any other component of this disclosure to form an embodiment having the defined values ​​for each component provided throughout this specification. For example, an interlayer film can be formed that includes any given range of plasticizer, as well as any given range of residual hydroxyl content, to form many variations that are within the scope of this disclosure but would be too complex to list. Furthermore, a range provided for a class or category can also apply to species within that class or category, unless otherwise specified. The present invention includes the following embodiments. [1] A poly(vinyl butyral) interlayer film comprising a poly(vinyl butyral) resin and at least one plasticizer, When the interlayer is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L* >94、-2.5<a * <-1.0、0<b * <2.5, and %T≧85% * 、a * , and b * and luminous transmittance (%T), * 、a * , and b * is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab, and %T is measured according to ASTM D1003. Poly(vinyl butyral) interlayer. [2] The interlayer has a thickness of L when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1. * >94、-2.5<a * <-1.1、0<b * <2.5, and %T≧85% * 、a * , and b * L * 、a * , and b * However, ASTM The poly(vinyl butyral) interlayer film according to [1], wherein the viscosity is measured in accordance with E1348 Ill. D65 / 10° Obs. CIELab, and %T is measured in accordance with ASTM D1003. [3] The interlayer has a thickness of L when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1. * >94、-2.3<a * <-1.2、0.5<b * Color coordinate L < 2.4 * 、a * , and b * L * 、a * , and b * [1] The poly(vinyl butyral) interlayer film according to [1], wherein the viscosity is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab. [4] The interlayer has a thickness of L when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1. * >94、-2.2<a * <-1.3、0.5<b * Color coordinate L < 2.2 * 、a * , and b * L * 、a* , and b * [1] The poly(vinyl butyral) interlayer film according to [1], wherein the viscosity is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab. [5] The interlayer has a thickness of L when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1. * >94、-2.0<a * <-1.5、1.0<b * <2.0 color coordinate L * 、a * , and b * L * 、a * , and b * [1] The poly(vinyl butyral) interlayer film according to [1], wherein the viscosity is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab. [6] The interlayer has a thickness of L when measured on a sample having a target thickness of 3.8 mm prepared according to Procedure 1. * >95.5、-1.50<a * < -0.95, and 0 < 1.5 color coordinate L * , and b * 、a * L * , and b * 、a * ​ * [1] to [5], wherein the poly(vinyl butyral) interlayer film has a viscosity of 1000 sq ft (2000 sq m), and the viscosity of the interlayer is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab. [7] The poly(vinyl butyral) interlayer film of [6], wherein the interlayer film has a luminous transmittance (%T) of at least 89% when measured on a sample having a target thickness of 3.8 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003. [8] The interlayer has a thickness of L when measured on a sample having a target thickness of 1.52 mm prepared according to Procedure 1. * >95.0、-0.65<a * < -0.45, and 0.1 < 0.8 color coordinate L * , and b * 、a * L * , and b * 、a * The poly(vinyl butyral) interlayer film according to any one of [1] to [7], wherein the viscosity is measured according to ASTM E1348 Ill.D65 / 10° Obs. CIELab. * [9] The poly(vinyl butyral) interlayer film of [8], wherein the interlayer film has a luminous transmittance (%T) of at least 91% when measured on a sample having a target thickness of 1.52 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

[10] The interlayer has a thickness of L when measured on a sample having a target thickness of 0.76 mm prepared according to Procedure 1. <-0.25, and 0.05 < 0.55 color coordinate L * >96.0、-0.35<a * , and b * L *、a * , and b * [1] to [9], wherein the poly(vinyl butyral) interlayer film has a viscosity of 1000 sq ft (2000 sq m), and the viscosity of the interlayer is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab. * 、a *

[11] The poly(vinyl butyral) interlayer film of

[10] , wherein the interlayer film has a luminous transmittance (%T) of at least 90% when measured on a sample having a target thickness of 0.76 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003. *

[12] The poly(vinyl butyral) interlayer film according to any one of [1] to

[11] , which is a multilayer interlayer film having at least two layers.

[13] The poly(vinyl butyral) interlayer film according to any one of [1] to

[12] , which is a multilayer interlayer film having at least three layers.

[14] A first glass substrate; [1] to

[13] , and a second glass substrate; Including, multi-layer panels. ​ ​

[15] The multiple layer glass panel of

[14] , wherein the first glass substrate and the second glass substrate each comprise low-iron glass.

[16] The multiple layer glass panel of

[14] , wherein the first glass substrate and the second glass substrate each comprise standard float glass.

[17] The multilayer glass panel according to any one of

[14] to

[16] , wherein the first glass substrate has a thickness of at least 2 mm and the second glass substrate has a thickness of at least 2 mm.

[18] A method for making a poly(vinyl butyral) sheet with improved color, comprising: providing a poly(vinyl butyral) resin; providing a plasticizer; providing at least one colorant in an amount sufficient to reduce the yellowness in appearance of the poly(vinyl butyral) sheet; melt blending the poly(vinyl butyral) resin, the plasticizer, and the colorant to form a poly(vinyl butyral) melt blend; and extruding the poly(vinyl butyral) melt blend into a poly(vinyl butyral) sheet; The poly(vinyl butyral) sheet has a L when measured on a sheet having a thickness of 6.3 mm (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab). * >94、-2.5<a * Color coordinates a < -1.0 and 0 < 2.5 * and b * A method comprising: *

[19] The method of

[18] , wherein the interlayer film has a luminous transmittance (%T) of %T≧85% when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

[20] When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L <2.0 color coordinate L * >94、-2.0<a * <-1.5、1.0<b * , and b * 、a * and a * and b * The method according to

[18] or

[19] , wherein is measured according to ASTM E1348 Ill.D65 / 10°Obs.CIELab. * ​

Claims

1. A poly(vinyl butyral) interlayer film comprising a poly(vinyl butyral) resin, at least one plasticizer, and at least one colorant, When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L ＊ >94, -2.5<a ＊ <-1.0, 0<b ＊ <2.5, and %T≧85% ＊ , a ＊ , and b ＊ and luminous transmittance (%T), ＊ , a ＊ , and b ＊ is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab, and %T is measured according to ASTM D1003; Poly(vinyl butyral) interlayer.

2. When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L ＊ >94, -2.5<a ＊ <-1.1, 0<b ＊ <2.5, and %T≧85% ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 10. The poly(vinyl butyral) interlayer film of claim 1, wherein %T is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab and %T is measured according to ASTM D1003.

3. When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L ＊ >94, -2.3<a ＊ <-1.2, 0.5<b ＊ color coordinate L<2.4 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 2. The poly(vinyl butyral) interlayer film of claim 1, wherein the tensile strength is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab.

4. When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L ＊ >94, -2.2<a ＊ <-1.3, 0.5<b ＊ color coordinate L<2.2 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 2. The poly(vinyl butyral) interlayer film of claim 1, wherein the tensile strength is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab.

5. When the interlayer film is measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, L ＊ >94, -2.0<a ＊ <-1.5, 1.0<b ＊ color coordinate L<2.0 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 2. The poly(vinyl butyral) interlayer film of claim 1, wherein the tensile strength is measured in accordance with ASTM E1348 Ill. D65 / 10° Obs. CIELab.

6. When the interlayer film is measured on a sample having a target thickness of 3.8 mm prepared according to Procedure 1, L ＊ >95.5, -1.50<a ＊ < -0.95, and 0 < b ＊ color coordinate L<1.5 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 6. The poly(vinyl butyral) interlayer film of claim 1, wherein the viscosity is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab.

7. 7. The poly(vinyl butyral) interlayer film of claim 6, wherein the interlayer film has a luminous transmittance (%T) of at least 89% when measured on a sample having a target thickness of 3.8 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

8. When the interlayer film is measured on a sample having a target thickness of 1.52 mm prepared according to Procedure 1, L ＊ >95.0, -0.65<a ＊ < −0.45, and 0.1<b ＊ color coordinate L<0.8 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 8. The poly(vinyl butyral) interlayer film of claim 1, wherein the viscosity is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab.

9. 9. The poly(vinyl butyral) interlayer film of claim 8, wherein the interlayer film has a luminous transmittance (%T) of at least 91% when measured on a sample having a target thickness of 1.52 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

10. When the interlayer film is measured on a sample having a target thickness of 0.76 mm prepared according to Procedure 1, L ＊ >96.0, -0.35<a ＊ < −0.25, and 0.05<b ＊ color coordinate L<0.55 ＊ , a ＊ , and b ＊ and L ＊ , a ＊ , and b ＊ 10. The poly(vinyl butyral) interlayer film of claim 1, wherein the viscosity is measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab.

11. 11. The poly(vinyl butyral) interlayer film of claim 10, wherein the interlayer film has a luminous transmittance (%T) of at least 90% when measured on a sample having a target thickness of 0.76 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

12. a first glass substrate; The interlayer film according to any one of claims 1 to 11, a second glass substrate; Including, multi-layer panels.

13. 13. The multiple layer glass panel of claim 12, wherein the first glass substrate and the second glass substrate each comprise low iron glass.

14. 1. A method for making a poly(vinyl butyral) sheet with improved color, comprising: providing a poly(vinyl butyral) resin; providing a plasticizer; providing at least one colorant in an amount sufficient to reduce the yellowness in appearance of the poly(vinyl butyral) sheet; melt blending the poly(vinyl butyral) resin, the plasticizer, and the colorant to form a poly(vinyl butyral) melt blend; and extruding the poly(vinyl butyral) melt blend into a poly(vinyl butyral) sheet; The poly(vinyl butyral) sheet has a L 100% tensile strength (measured according to ASTM E1348 Ill. D65 / 10° Obs. CIELab) when measured on a sheet having a thickness of 6.3 mm. ＊ >94, -2.5<a ＊ <-1.0, and 0<b ＊ Color coordinate a<2.5 ＊ and b ＊ and the poly(vinyl butyral) sheet has a luminous transmittance (%T) of %T≧85%, when measured on a sample having a target thickness of 6.3 mm prepared according to Procedure 1, wherein %T is measured according to ASTM D1003.

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