Interlayers with improved laminate processability

Abstract

Interlayers having improved laminate processability while also having excellent acoustic or acoustic characteristics are disclosed. The interlayer has a thermal shrinkage of less than about 4%, a coefficient of static friction (COF) of less than 1.50 when measured in an interlayer-to-interlayer configuration according to ASTM D1894, and wherein the laminated glazing has a damping loss factor (eta) of at least 0.20 when measured at 20 DEG C according to ISO 16940.

Description

Technical Field

[0001] The present disclosure relates to the field of polymer interlayers for multilayer glass panels and multilayer glass panels having at least one polymer interlayer sheet. In particular, the present disclosure relates to the field of multilayer panels comprising polymer interlayers comprising a plurality of thermoplastic layers having improved acoustic properties, such as improved damping and improved processability and handling. The present disclosure also relates to an improved method for assembling laminated glazing using the reinforced interlayer of the present invention. Background Art

[0002] Multilayer panels are usually panels composed of two substrates (such as but not limited to glass, polyester, polyacrylate or polycarbonate) and one or more polymer interlayers sandwiched therebetween. Laminated multilayer glass panels are commonly used in architectural window applications and windows of motor vehicles and aircraft and photovoltaic solar panels. The first two applications are generally referred to as laminated safety glass. The main function of the interlayer in laminated safety glass is to absorb the energy generated by the impact or force applied to the glass, so as to keep the glass layers bonded together even when force is applied and the glass is broken, and to prevent the glass from breaking into sharp fragments. In addition, the interlayer can also give the glass a much higher sound insulation level, reduce UV and / or IR light transmission, and improve the aesthetic appeal of the relevant windows. Regarding photovoltaic applications, the main function of the interlayer is to encapsulate photovoltaic solar panels for generating and supplying electricity in commercial and residential applications.

[0003] In order to achieve certain properties and performance characteristics of glass panels, it has become common practice to utilize multilayer or multilayer interlayers. As used herein, the terms "multilayer" and "multiple layers" mean an interlayer having more than one layer, and multilayer and multiple layers are used interchangeably. Multilayer interlayers typically contain at least one soft layer and at least one hard layer. Interlayers having a soft "core" layer sandwiched between two more rigid or harder "surface" layers have been designed to have sound insulation properties for glass panels. Interlayers with the opposite construction (i.e., a hard layer sandwiched between two soft layers) have been found to improve the impact performance of glass panels and can also be designed for sound insulation. Examples of multilayer interlayers also include interlayers having at least one "transparent" or non-colored layer and at least one colored layer or at least one conventional layer (e.g., non-acoustic layer) and at least one acoustic layer (i.e., a layer having acoustic properties or having the ability to provide sound insulation or reduce sound transmission, as further defined below). Other examples of multi-layer interlayers include interlayers having at least two layers having different colors for aesthetic appeal. The colored layer typically contains a pigment or a dye or some combination of a pigment and a dye.

[0004] The layers of the interlayer are typically produced by mixing a polymer resin such as poly(vinyl butyral) with one or more plasticizers and melt processing the mixture into a sheet by any suitable process or method known to those skilled in the art, including but not limited to extrusion. The multilayer interlayer can be produced by processes such as coextrusion or lamination, where the layers are combined together to form a unitary structure. Other additional ingredients may optionally be added for various other purposes. After the interlayer sheet is formed, it is typically collected and rolled for transportation and storage and subsequently used in a multilayer glass panel, as discussed below.

[0005] A simplified description of the manner in which multilayer glass panels are typically produced in combination with interlayers is provided below. First, at least one polymer interlayer sheet (single or multilayer) is placed between two substrates and any excess interlayer is trimmed from the edges to produce an assembly. It is not uncommon to place multiple polymer interlayer sheets or polymer interlayer sheets having multiple layers (or a combination of both) within two substrates to produce a multilayer glass panel having multiple polymer interlayers. The air is then removed from the assembly by an applicable process or method known to those skilled in the art; for example, by nip rollers, vacuum bags, or another degassing mechanism. In addition, the interlayer portion is crimped to the substrate by any method known to those of ordinary skill in the art. In the final step, to form the final integral structure, the preliminary bond is made more durable by a high temperature and high pressure lamination process, or any other method known to those of ordinary skill in the art, such as, but not limited to, autoclaving.

[0006] Multilayer interlayers such as three-layer interlayers having a soft core layer and two harder skin layers are commercially available. The hard skin layers provide handling, processing and mechanical strength for the interlayer; the soft core layer provides acoustic damping properties.

[0007] The vibration damping properties of laminated glass used in vehicle glazing applications (such as windshields, side laminates and sunroofs) are essential for vehicle cabin noise levels because vehicle glazing occupies a large portion of the vehicle cabin area and is the main path for external noise (such as wind noise, road noise, tire noise, engine noise) to enter the vehicle cabin. Laminated glazing with high vibration damping will allow more external noise or sound to be absorbed, thereby keeping the cabin quieter. When used in automotive glazing, these high damping laminates can absorb more external noise.

[0008] There is a need to maximize the damping of laminates while meeting the industrial safety requirements for vehicle glazing applications. The present invention discloses interlayers that provide high damping loss factors while improving the production efficiency of glass laminates and meeting the industrial requirements for vehicle glazing. The present invention also provides a method for more efficiently processing interlayers to meet the increasingly demanding lamination processability requirements, particularly in robotic lamination assembly processes.

[0009] In summary, multilayer interlayers are currently commonly used to provide high performance laminates. There is a need in the art to develop multilayer interlayers that have the good optical, mechanical and acoustic characteristics expected in a multilayer interlayer. More specifically, there is a need in the art to develop multilayer interlayers that have good acoustic properties such as damping loss factor, which can also be used and processed more efficiently. Summary of the invention

[0010] In view of these and other problems in the art, a polymer interlayer is described herein, wherein the polymer interlayer has a thermal shrinkage of less than about 4.0% (3.9%, 3.8%, 3.7%, 3.6%, 3.5%, 3.4%, 3.3%, 3.2%, 3.1%, 3.0%, 2.9%, 2.8%, 2.7%, 2.6%, 2.5%, 2.4%, 2.3%, 2.2%, 2.1%, 2.0% or less), when measured according to ASTM D1894 has a coefficient of static friction (COF) of less than 1.50 (1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30 or less) when measured in an interlayer to interlayer configuration, and the multiple layer glass panel including the interlayer has a damping loss factor (η) of at least 0.20 (0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 or more) when measured at 20°C according to ISO 16940. In embodiments, the interlayer has a coefficient of static friction (COF) of less than 2.00 (1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45 or less) when measured in an interlayer to metal slide configuration according to ASTM D1894. In an embodiment, the interlayer has a dynamic coefficient of friction (COF) of less than 0.50 (0.45, 0.40, 0.35, 0.30 or less) when measured in an interlayer-to-interlayer configuration according to ASTM D1894. In an embodiment, the interlayer has a dynamic coefficient of friction (COF) of less than 1.00 (0.95, 0.90, 0.85, 0.80, 0.75, 0.70) when measured in an interlayer-to-metal slide configuration according to ASTM D1894.

[0011] In an embodiment, the interlayer is a multilayer interlayer comprising: a first layer comprising a first poly(vinyl acetal) resin having a first residual hydroxyl content and a first residual acetate content, and a first plasticizer, wherein the first layer has a glass transition temperature (T g ); a second layer comprising a second poly(vinyl acetal) resin having a second residual hydroxyl content, and a second plasticizer, wherein the second layer has a glass transition temperature (T g ); and a third layer comprising a third poly(vinyl acetal) resin having a third residual hydroxyl content, and a third plasticizer, wherein the third layer has a glass transition temperature (T g ), wherein the second layer is between the first layer and the third layer.

[0012] In one embodiment, the laminate comprises: a first glass substrate: a polymer interlayer; and a second rigid substrate; wherein the polymer interlayer has a thermal shrinkage of less than about 4.0% (3.9%, 3.8%, 3.7%, 3.6%, 3.5%, 3.4%, 3.3%, 3.2%, 3.1%, 3.0%, 2.9%, 2.8%, 2.7%, 2.6%, 2.5%, 2.4%, 2.3%, 2.2%, 2.1%, 2.0% or less), when measured according to ASTM D1894 has a coefficient of static friction (COF) of less than 1.50 (, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30 or less) when measured in an interlayer-to-interlayer configuration, and the multiple layer glass panel including the interlayer has a damping loss factor (η) of at least 0.20 (0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 or more) when measured at 20°C according to ISO 16940. In an embodiment, the interlayer has a static coefficient of friction (COF) of less than 2.00 (1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45 or less) when measured in an interlayer to metal slide configuration according to ASTM D1894. In an embodiment, the interlayer has a dynamic coefficient of friction (COF) of less than 0.50 (0.45, 0.40, 0.35, 0.30 or less) when measured in an interlayer-to-interlayer configuration according to ASTM D1894. In an embodiment, the interlayer has a dynamic coefficient of friction (COF) of less than 1.00 (0.95, 0.90, 0.85, 0.80, 0.75, 0.70) when measured in an interlayer-to-metal slide configuration according to ASTM D1894.

[0013] In an embodiment, the first poly(vinyl acetal) resin and the third poly(vinyl acetal) resin are the same. In an embodiment, the first plasticizer and the third plasticizer are the same. In other embodiments, the second plasticizer is the same as at least one of the first plasticizer or the third plasticizer.

[0014] In embodiments, the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 2.0 (2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0 or more) weight percent. In embodiments, the difference between the first residual acetate content and the second residual acetate content is at least 2.0 (2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0 or more) weight percent.

[0015] In an embodiment, the interlayer is a colored interlayer. In an embodiment, the colored interlayer has a percent transmittance (%T) of less than about 75% (70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 4%, 3%, 2% or less). %T is also known as luminous transmittance %T and is measured according to ASTM D1003-13 procedure B using illuminant C at an observation angle of 2 degrees. In an embodiment, the colored interlayer is gray, such as a light gray or dark gray interlayer sheet.

[0016] In embodiments, the interlayer comprises an IR absorber.In embodiments, the interlayer is a multilayer interlayer having an IR absorber in at least one layer.

[0017] In an embodiment, the interlayer further comprises a non-poly(vinyl acetal) layer. In an embodiment, the interlayer comprises a non-poly(vinyl acetal) layer, which is a functional film, layer or sheet, such as a polyethylene terephthalate (PET) film, a coated PET film or other layer, such as an IR absorbing film or an IR reflecting film.

[0018] Also disclosed is a method of preparing a polymer interlayer, wherein the polymer interlayer is as disclosed herein.

[0019] In an embodiment, a method for manufacturing a laminate is disclosed, the method comprising the steps of providing a first rigid substrate to an assembly fixture, providing a sandwich blank, placing the sandwich blank on the first rigid substrate using a conveying device, providing a second rigid substrate and placing the second rigid substrate on the sandwich blank to form a pre-assembled part.

[0020] In an embodiment, the laminated glazing is a windshield, side lite, sunroof or other window in a vehicle. In an embodiment, the laminated glazing is used in a head-up display application.

[0021] In certain embodiments, the rigid substrate (or substrates) is glass. DETAILED DESCRIPTION

[0022] Described herein, inter alia, are laminated glazings comprised of a first rigid substrate and a second rigid substrate and a multilayer polymer interlayer. The interlayers of the present disclosure, and therefore the laminated glazings, have improved acoustic or soundproofing properties as measured by the damping loss factor. The laminated glazings comprising the interlayer of the present invention have a damping loss factor (η) of at least 0.20 (0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 or more) when measured according to ISO 16940. The interlayer of the present invention also has a static friction coefficient of less than 1.50 (measured as interlayer to interlayer according to ASTM D1894).

[0023] Also described is an automated method for manufacturing a multilayer glass panel, such as a side window, a sunroof, or a windshield. The method comprises the following steps: providing a first rigid substrate to an assembly fixture, providing an interlayer blank, placing the interlayer blank on the first rigid substrate using a conveying device, providing a second rigid substrate and placing the second rigid substrate on the interlayer blank, thereby forming a pre-assembled part. The pre-assembled part may be located on a conveyor or other device for moving the pre-assembled part for further processing. In an embodiment, a conveying device identical or similar to the conveying device for providing the interlayer blank may be used to provide the first and / or second rigid substrate. In an embodiment, the pre-assembled part is further processed by moving the pre-assembled part to a degassing process, such as a pinch roller, a vacuum bag, a vacuum ring, or other process. After degassing, the pre-assembled part may be further processed, such as in an autoclave.

[0024] As used herein, "conveying equipment" is any equipment or device for automatically (or partially automatically or semi-automatically) moving or conveying articles (such as sandwich blanks or rigid substrates). The conveying equipment automatically moves articles (such as by using a control device or programming) and does not use human hands to physically pick up and carry or move articles and place them in another position. Conveying equipment is known in the art. In an embodiment, the conveying equipment is a robot or a robot arm. In an embodiment, the conveying equipment can have a suction cup or other device for picking up rigid substrates and / or sandwich blanks.

[0025] Multiple layer glass panels including the interlayer are also described. The interlayers of the present invention can be used in multiple layer glass panel applications such as windshields, side windows, skylights and roofs, and safety glass in architectural windows, among other applications.

[0026] In the robotic lamination assembly process, the bottom glass sheet (or glass sheet) is usually picked up by a conveying device (such as a robotic arm) with a suction cup and placed on an assembly fixture for making a laminated window glass (such as a side laminate), the interlayer is cut to a certain size to form an interlayer blank from a roll, and the interlayer blank is picked up by another conveying device and placed directly on the bottom glass sheet, and then the top glass sheet is picked up by the conveying device and placed on top of the interlayer blank to form a pre-assembly. The pre-assembly is moved to a degassing section such as on a conveyor to complete the degassing process, thereby forming a finished assembly, and then the finished assembly is autoclaved to produce the final laminated glass. The interlayer blank can be cut from the roll and used immediately (such as picked up and conveyed), or the roll can be cut into interlayer blanks of appropriate size and stacked on each other (to form an interlayer blank stack) for subsequent use in the process. This type of automated assembly process provides the following benefits: reduced labor costs, increased production capacity, reduced yield loss due to fewer out-of-spec or rejected parts due to human process errors, less potential for contamination (due to handling, etc.), and less need to schedule workers in advance to manually assemble the glass. Other benefits will be recognized by those skilled in the art.

[0027] However, there are at least two problems when using conventional interlayers that may jeopardize the automated process and reduce productivity: the interlayer cannot be picked up by the conveying equipment (i.e., robot arm) due to the softness of the interlayer and / or its stickiness to other adjacent layers or surfaces (to another interlayer blank or to the surface on which the blank is located); when exposed to heat, the interlayer shrinks excessively during the degassing process, which leads to the formation of edge defects such as short interlayers along the edges and bubbles in the final laminated glass.

[0028] This shrinkage can be caused or exacerbated by processing conditions and can be minimized, for example, by avoiding excessive stretching during manufacturing, conveying and rolling or pre-relaxing the sheet before winding. In addition, the sheet can be relaxed again just before use.

[0029] At present, in order to solve the shrinkage problem, the laminate must undergo additional processing steps. One such additional step includes pre-cutting the interlayer blanks larger than the glass size and relaxing the interlayer blanks for 24 to 48 hours before the assembly process. By pre-cutting the interlayer blanks, this increases the amount of sheet handling steps, turnaround time, waste (yield loss) of the interlayer, and limits production capacity. For the stickiness of the interlayer (that is, the tendency of the interlayer to adhere to itself or other surfaces such as workbenches), the laminate must adjust process conditions such as room temperature, apply manual intervention or other process improvements to avoid operational failures of the conveying equipment.

[0030] These and other benefits are achieved by the multi-layer interlayers of the present invention having reduced shrinkage, lower COF, and high acoustic damping properties.

[0031] Each layer of the multilayer polymer interlayer can be manufactured by mixing one or more polymer resins such as poly(vinyl acetal) resins (such as PVB) and one or more plasticizers. The multilayer interlayer generally contains two or more layers and two or more resins of different compositions. For example, poly(vinyl acetal) resins (such as PVB resins) with different residual hydroxyl contents and / or residual acetate contents are suitable for use in the layers of the multilayer interlayer composition. In a multilayer comprising two layers, at least one of the two layers is a soft layer and the other layer is a hard layer. As used herein, a "soft layer" or "softer layer" is a layer having a glass transition temperature of less than about 20°C. As used herein, a "hard layer" or "harder layer" generally refers to a layer that is harder or more rigid than another layer and has a glass transition temperature that is generally at least 2 degrees Celsius (2°C) higher than another layer (such as a softer layer).

[0032] The multilayer interlayer formed from these compositions may contain two or more glass transitions, and the lowest glass transition occurs at less than 20°C, or less than 15°C, or less than 10°C, or less than 5°C, or less than 0°C, or less than -5°C, or less than -10°C.

[0033] Conventional multilayer interlayers, such as three-layer acoustic interlayers, contain a soft core layer composed of a single poly(vinyl butyral) ("PVB") resin with a low residual hydroxyl content and a high level of conventional plasticizers, and two hard skin layers with significantly higher residual hydroxyl contents (see, e.g., U.S. Pat. Nos. 5,340,654, 5,190,826, and 7,510,771). The residual hydroxyl content in the PVB core resin and the amount of plasticizer are optimized so that the interlayer provides optimal sound insulation properties under ambient conditions for multilayer glass panels, such as windshields and windows installed in vehicles and buildings.

[0034] A multilayer acoustic interlayer, such as a trilayer, can be designed and produced by (1) selecting a plasticizer or a mixture of plasticizers, (2) selecting one or more resins for one or more skin layers and one or more core layers, (3) maintaining a plasticizer balance between one or more core layers and one or more skin layers (such as by selecting resins with specific properties), and (4) combining one or more core layers with one or more skin layers to form the multilayer interlayer by a suitable process such as coextrusion or lamination. When the resins and plasticizers are appropriately selected for the desired properties and characteristics, the resulting multilayer acoustic interlayer provides excellent transparency and soundproofing properties without sacrificing other advantageous and desirable features of conventional multilayer interlayers, such as optical properties, and the mechanical strength of glass panels made with the multilayer acoustic interlayer.

[0035] Some terms and common components present in interlayers (generally and in the interlayers of the present disclosure) and their formation will be discussed. As used herein, the terms "polymer interlayer sheet", "interlayer" and "polymer melt sheet" can generally refer to a single layer sheet or a multilayer interlayer. As the name implies, a "single layer sheet" is a single polymer layer extruded as a layer. On the other hand, a multilayer interlayer can include multiple layers, including individually extruded layers, coextruded layers, or any combination of individual and coextruded layers. Thus, a multilayer interlayer can include, for example: two or more single layer sheets combined together ("multilayer sheets"); two or more layers coextruded together ("coextruded sheets"); two or more coextruded sheets combined together; a combination of at least one single layer sheet and at least one coextruded sheet; a combination of a single layer sheet and a multilayer 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 comprises at least two polymer layers (e.g., a single layer or multiple layers coextruded and / or laminated together) arranged in direct contact with each other, wherein each layer comprises a polymer resin, as described in more detail below. As used herein for a multilayer interlayer having at least three layers, a "skin layer" generally refers to the outer layer of the interlayer and a "core layer" generally refers to one or more inner layers. Thus, an exemplary embodiment would be: skin layer / / core layer / / skin layer. In a multilayer interlayer having a skin layer / / core layer / / skin layer construction, in some embodiments, the skin layer can be harder and the core layer can be softer, while in other embodiments, the skin layer can be softer and the core layer can be harder.

[0036] Poly(vinyl acetal) resins are produced by a known acetalization process by reacting polyvinyl alcohol ("PVOH") with one or more aldehydes such as butyraldehyde in the presence of an acid catalyst, isolating, stabilizing, and drying 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. The resins are commercially available in various forms, for example, as PVOH from Solutia Inc., a wholly owned subsidiary of Eastman Chemical Company. Resin.

[0037] As used herein, the residual hydroxyl content (calculated as % vinyl alcohol or % PVOH by weight) in poly (vinyl acetal) resin refers to the amount of hydroxyl groups remaining on the polymer chain after processing is completed. For example, PVB can be made by hydrolyzing poly (vinyl acetate) into poly (vinyl alcohol) (PVOH), and then reacting PVOH with butyraldehyde. In the process of hydrolyzing poly (vinyl acetate), usually not all acetate side groups are converted into hydroxyl groups. In addition, the reaction with butyraldehyde will not usually cause all hydroxyl groups to be converted into acetal groups. Therefore, in any finished PVB resin, there will usually be 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, the residual acetate content (calculated as % vinyl acetate content or poly (vinyl acetate) (PVAc) by weight) in poly (vinyl acetal) refers to the amount of residual groups remaining on the polymer chain. As used herein, residual hydroxyl content and residual acetate content are measured on a weight percent (wt %) basis according to ASTM D1396.

[0038] In an embodiment, when the multilayer interlayer of the present invention is three layers, the core layer is a soft layer and the skin layer is a hard layer. In other embodiments, the core layer is hard and the skin layer is softer. Other combinations and number of layers are also possible.

[0039] In various embodiments where the interlayer is a multi-layer interlayer such as a trilayer, the soft (or core) layer comprises a poly(vinyl acetal) resin (or first resin) comprising from about 7 weight percent (wt %) to about 16 wt % hydroxyl groups (calculated as % PVOH), from about 7 wt % to about 14 wt %, from about 9 wt % to about 14 wt %, from about 8.5 wt % to about 12 wt %, and for certain embodiments, from about 11 wt % to about 13 wt % hydroxyl groups (calculated as % PVOH), although other amounts are possible.

[0040] In various embodiments where the interlayer is a multi-layer interlayer such as a trilayer, one or more hard (or skin) layers comprise a poly(vinyl acetal) resin having a residual hydroxyl content greater than that of the resin in the soft (or core) layer by at least 2 wt%, or at least 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt% or more, and the resin in the skin layer may comprise from about 15 wt% to about 35 wt%, from about 15 wt% to about 30 wt%, or from about 17 wt% to about 22 wt%; and, for certain embodiments, from about 22 wt% to about 25 wt% residual hydroxyl groups (calculated as % PVOH), although other amounts are possible depending on the desired properties.

[0041] In either the soft (core) layer or the harder (skin) layer or both, any resin may also contain less than 30 wt% residual acetate groups, less than 25 wt% residual acetate groups, less than 20 wt%, less than 15 wt%, less than 13 wt%, less than 10 wt%, less than 7 wt%, less than 5 wt%, or less than 1 wt%, or less than 0.5 wt% residual acetate groups calculated as poly(vinyl acetate), or residual acetate groups in the range of 0 to 30 wt%, 1 wt% to 30 wt%, 2 wt% to 25 wt%, 5 wt% to 20 wt%, or 7 wt% to 15 wt%, the remainder being acetal, such as butyraldehyde (which includes isobutyraldehyde acetal groups), but optionally another acetal group, such as 2-ethylhexanal acetal groups, or a mixture of butyraldehyde acetal and 2-ethylhexanal acetal groups. In an embodiment, any resin may comprise a poly(vinyl acetal) resin having a residual acetate content that is at least 2% by weight greater, or at least 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20% by weight or more greater than the residual acetate content of another resin in the same or a different layer.

[0042] The difference in residual hydroxyl and / or residual acetate levels between poly(vinyl acetal) resins is calculated by subtracting the residual hydroxyl content of the resin having the lower residual hydroxyl content from the residual hydroxyl content of the resin having the greater residual hydroxyl content. As used herein, the term "weight percentage is different" or "the difference ... is at least ... weight percentage" refers to the 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 weight percent has a residual hydroxyl content that is 2 weight percentages lower than a poly(vinyl acetal) resin having a residual hydroxyl content of 14 weight percent (14 weight percent - 12 weight percent = 2 weight percent). As used herein, the term "different" may refer to one value being higher or lower than another value. One or more other poly(vinyl acetal) layers may also be present in the interlayer and may have residual hydroxyl groups within the ranges provided above. In addition, the residual hydroxyl content of one or more other poly(vinyl acetal) resins may be the same as or different from the residual hydroxyl content of the first and / or second poly(vinyl acetal) resins. The additional poly(vinyl acetal) layers present in the interlayer may have a residual acetate content that is the same as or different from the residual acetate content of the first and / or second poly(vinyl acetal) resins.

[0043] Poly(vinyl acetal) resins of the present disclosure, such as poly(vinyl butyral) (PVB) resins (or a plurality of such resins), typically have a molecular weight greater than 50,000 Daltons, or less than 500,000 Daltons, or from about 50,000 to about 500,000 Daltons, or from about 70,000 to about 500,000 Daltons, or from about 100,000 to about 425,000 Daltons, as measured by size exclusion chromatography using a low angle laser light scattering detector, a differential refractometer, or a UV detector. As used herein, the term "molecular weight" refers to the weight average molecular weight.

[0044] Various adhesion control agents ("ACAs") may be used in the interlayers of the present disclosure to control the adhesion of the interlayer sheets to the glass. In various embodiments of the interlayers of the present disclosure, the interlayer may include about 0.003 to about 0.15 parts of ACA per 100 parts of resin; about 0.01 to about 0.10 parts of ACA per 100 parts of resin; and about 0.01 to about 0.04 parts of ACA per 100 parts of resin. Such ACAs include, but are not limited to, ACAs disclosed in U.S. Pat. No. 5,728,472 (the entire disclosure of which is incorporated herein by reference), sodium acetate, potassium acetate, magnesium bis(2-ethylbutyrate), and / or magnesium bis(2-ethylhexanoate).

[0045] Other additives may be incorporated into the interlayer to enhance its performance in the final product and to impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., UV stabilizers), antioxidants, antiblocking agents, flame retardants, IR absorbers or blockers (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB6), and cesium tungsten oxide), processing aids, flow enhancing additives, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives and fillers, and other additives known to those of ordinary skill in the art.

[0046] In various embodiments, the plasticizer may be selected from a high refractive index plasticizer, a mixture of two or more high refractive index plasticizers, or a mixture of a conventional plasticizer and one or more high refractive index plasticizers.

[0047] As used herein, a plasticizer having a refractive index of about 1.450 or less is referred to as a "conventional plasticizer". Conventional plasticizers include, but are not limited to, triethylene glycol di-(2-ethylhexanoate) ("3GEH"), triethylene glycol di-(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, tetraethylene glycol di-(2-ethylhexanoate), dihexyl adipate, dioctyl adipate, cyclohexyl adipate, diisononyl adipate, heptyl nonyl adipate, di(butoxyethyl) adipate and bis(2-(2-butoxyethoxy)ethyl) adipate, dibutyl sebacate, dioctyl sebacate, and mixtures thereof. These plasticizers have a refractive index of about 1.442 to about 1.449. In contrast, PVB resin has a refractive index of about 1.485 to 1.495. 3GEH (refractive index = 1.442) is one of the most common plasticizers present in interlayers manufactured for various properties and applications.

[0048] In various embodiments, one or more high refractive index plasticizers may be used. In an embodiment, one or more high refractive index plasticizers are selected so that for both the core layer and / or the skin layer, the refractive index of the plasticizer is at least about 1.460, or greater than about 1.460, or greater than about 1.470, or greater than about 1.480, or greater than about 1.490, or greater than about 1.500, or greater than 1.510, or greater than 1.520. As used herein, a "high refractive index plasticizer" is a plasticizer with a refractive index of at least about 1.460. In some embodiments, one or more high refractive index plasticizers are used in combination with conventional plasticizers, and in some embodiments, if included, the conventional plasticizer is triethylene glycol di-(2-ethylhexanoate) ("3GEH"), and the refractive index of the plasticizer mixture is at least 1.460. As used herein, the refractive index of a plasticizer or resin used throughout this disclosure is measured according to ASTM D542 at a wavelength of 589 nm and 25° C., or as reported in the literature according to ASTM D542.

[0049] Examples of plasticizers with a high refractive index that can be used include, but are not limited to, polyadipates (RI from about 1.460 to about 1.485); epoxides (RI from about 1.460 to about 1.480); phthalates and terephthalates (RI from about 1.480 to about 1.540); benzoates (RI from about 1.480 to about 1.550); and other specialty plasticizers (RI from about 1.490 to about 1.520). Specific examples of suitable high refractive index 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-butylene glycol di ... Diol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, bisphenol A bis(2-ethylhexanoate), ethoxylated nonylphenol, nonylphenyl tetraethylene glycol, dioctyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, mixtures of benzoic acid esters of dipropylene glycol and diethylene glycol, and mixtures thereof.

[0050] The total plasticizer content in the interlayer may be from 0 to 120 phr, or greater than 0 phr, or greater than 5 phr, or greater than 10 phr, or greater than 15 phr, or greater than 20 phr, or greater than 25 phr, or greater than 30 phr and / or 120 phr or less, or 115 phr or less, or 110 phr or less, or 105 phr or less, or 100 phr or less, or 95 phr or less, or 90 phr or less, or 85 phr or less, or 80 phr or less, or 75 phr or less, or 70 phr or less, or in the range of 10 to 100 phr, or 20 to 80 phr, or 30 to 70 phr. In various embodiments of the interlayer of the present disclosure, the interlayer comprises greater than 5phr, about 5 to about 120phr, about 10 to about 90phr, about 20 to about 70phr, about 30 to about 60phr, or less than 120phr, or less than 90phr, or less than 60phr, or less than 40phr, or less than 30phr of total plasticizer. Although total plasticizer content is indicated above, the plasticizer content in one or more skins or core layers may be different from total plasticizer content. In addition, one or more skins and core layers may have different plasticizer types and plasticizer contents within the scope of previous discussion, because the plasticizer content of each corresponding layer is determined by the corresponding residual hydroxyl content of the layer under equilibrium, as disclosed in U.S. Patent number 7,510,771 (its entire disclosure is incorporated herein by reference). For example, at equilibrium, a sandwich may include two skin layers each having 30 phr plasticizer and a core layer having 65 phr plasticizer, with a total plasticizer amount of about 45.4 phr for a sandwich when the combined skin layer thickness is equal to the core layer thickness. For thicker or thinner skin layers, the total plasticizer amount for the sandwich will vary accordingly. As used herein, when the plasticizer content of a given sandwich is determined with reference to the phr of the plasticizer in the mixture or melt used to produce the sandwich.

[0051] The amount of plasticizer in the interlayer can be adjusted to affect the glass transition temperature (T g ) and the final acoustic performance. Glass transition temperature (T g ) is the temperature that marks the transition from the glassy state to the rubbery state of the interlayer. Generally, higher plasticizer loading will result in lower T g Conventionally, the interlayers previously used generally have a T in the range of about -10°C to 25°C. g For acoustic (noise reduction) interlayers, and up to a Tg of about 45°C for hurricane and aircraft (harder or structural) interlayer applications. g) can be determined by dynamic mechanical thermal analysis (DMTA) in shear mode. DMTA measures the storage (elastic) modulus (G') in Pascals, the loss (viscous) modulus (G") in Pascals, the loss tangent of the specimen as a function of temperature at a given frequency (=G" / G') and the temperature scan rate. A frequency of 1 Hz and a temperature scan rate of 3C / min are used herein. T is then determined by the position of the loss tangent peak on the temperature scale in °C. g , and the peak value of the loss tangent value is called the loss tangent value or the peak loss tangent value. As used herein, "loss tangent value", "peak loss tangent value", "tan δ" and "peak tan δ" are used interchangeably.

[0052] The glass transition temperature (T g ) is also related to the hardness of the interlayer, and generally speaking, the higher the glass transition temperature, the harder the interlayer. Typically, an interlayer with a glass transition temperature of 30°C or more increases the mechanical strength and torsional stiffness of the laminated glass. On the other hand, a soft layer or interlayer (typically characterized by a layer or interlayer having a glass transition temperature below 20°C) contributes to the sound damping effect (i.e., acoustic characteristics). One or more harder layers of the interlayer of the present disclosure may have a glass transition temperature of about 26°C or more, or about 37°C or more, and one or more soft layers may have a glass transition temperature of about 20°C or less, or 15°C or less, or 10°C or less, or about 5°C or less, or 0°C or less, or about -5°C or less, or about -10°C or less, but other glass transition temperatures are possible depending on the desired performance and characteristics.

[0053] In some embodiments, the multilayer interlayers of the present disclosure combine these two advantageous properties (i.e., strength and acoustics) by utilizing a stiffer or harder skin layer (e.g., hard / / soft / / hard) laminated with a softer core layer. In various embodiments, the multilayer interlayers typically include one or more stiffer layers comprising a poly(vinyl acetal) resin having a glass transition temperature of about 26°C to about 60°C, about 38°C to 48°C, about 26°C or more, about 30°C or more, or about 37°C or more, and one or more softer layers having a glass transition temperature of about 20°C or less, about 10°C or less, or about 5°C or less, or about 0°C or less, or about -5°C or less, or about -10°C or less.

[0054] Whether formed by extrusion or coextrusion or by lamination of multiple layers, the final interlayer generally has a random, rough surface morphology because it is formed by melt fracture of the polymer melt as it leaves the extrusion die, and may additionally be embossed with a random, rough surface on one or both sides (e.g., the skin layer) by any embossing method known to those of ordinary skill in the art.

[0055] Although all methods known to those of ordinary skill in the art for producing polymer interlayer sheets are contemplated as possible methods for producing the polymer interlayer sheets described herein, this application will focus on polymer interlayer sheets produced by extrusion and coextrusion processes. The final multilayer glass panel laminate of the present invention is formed using a lamination process known in the art.

[0056] Typically, the thickness or gauge of the polymer interlayer sheet will be in the range of about 10 mils to 100 mils (about 0.25 mm to about 2.54 mm), about 15 mils to 60 mils (about 0.38 mm to about 1.52 mm), about 20 mils to about 50 mils (about 0.51 to 1.27 mm), and about 15 mils to about 35 mils (about 0.38 to about 0.89 mm). In various embodiments, each layer of the multilayer interlayer (such as the skin layer and the core layer) can have a thickness of about 1 mil to 99 mils (about 0.025 to 2.51 mm), about 1 mil to 59 mils (about 0.025 to 1.50 mm), 1 mil to about 29 mils (about 0.025 to 0.74 mm), or about 2 mils to about 28 mils (about 0.05 to 0.71 mm), but other thicknesses can be selected depending on the desired properties and characteristics.

[0057] Although many of the embodiments described below refer to the polymer resin as PVB, it will be understood by those of ordinary skill in the art that the polymer may be any polymer suitable for use in multilayer panels. Typical polymers include, but are not limited to, polyvinyl acetal (PVA) (such as poly(vinyl butyral) (PVB) or poly(vinyl isobutyral), isomers of poly(vinyl butyral) (also known as PVisoB), aliphatic polyurethanes (PU), poly(ethylene-co-vinyl acetate) (EVA), polyvinyl chloride (PVC), poly(vinyl chloride-co-methacrylate), polyethylene, polyolefins, ethylene acrylate copolymers, poly(ethylene-co-butyl acrylate), silicone elastomers, epoxy resins, and acid copolymers derived from any of the foregoing possible thermoplastic resins such as ethylene / carboxylic acid copolymers and ionomers thereof, combinations of the foregoing, and the like. PVB and its isomers polyvinyl isobutyral, polyvinyl chloride, ionomers, and polyurethanes are suitable polymers generally used for interlayers; PVB (including its isomer PVisoB) is particularly suitable.

[0058] Examples of exemplary multilayer sandwich structures include, but are not limited to, PVB / / PVisoB / / PV B, wherein the PVisoB layer comprises two or more resins having different residual hydroxyl and / or residual acetate contents or different polymer compositions; PVC / / PVB / / PVC, PU / / PVB / / PU, ionomer / / PVB / / ionomer, ionomer / / PU / / ionomer, ionomer / / EVA / / ionomer, wherein the core layer PVB (including PVisoB), PU or EVA may comprise a single resin having one glass transition or two or more resins having different glass transitions. Alternatively, the skin layer and the core layer may both be PVB using the same or different starting resins, having the same or different residual hydroxyl and / or residual acetate contents and the same or different plasticizers. Other combinations of resins and polymers will be apparent to those skilled in the art.

[0059] Although often referred to as poly(vinyl acetal) or poly(vinyl butyral), any poly(vinyl acetal) resin may include the residue of any suitable aldehyde, such as isobutyraldehyde, as previously discussed. In some embodiments, one or more poly(vinyl acetal) resins may include at least one C1 to C 10 The first and second poly (vinyl acetal) resins may include at least about 20, at least about 30, at least about 40, at least about 50, at least about 60, or at least about 70 weight percent of the residues of at least one C4 to C8 aldehyde based on the total weight of the aldehyde residues of the resin, and / or may include no more than about 90, no more than about 85, no more than about 80, no more than about 75, no more than about 70, or no more than about 65 weight percent of at least one C4 to C8 aldehyde, or at least one C4 to C8 aldehyde within the range of about 20 to about 90, about 30 to about 80, or about 40 to about 70 weight percent. The C4 to C8 aldehyde may be selected from the group listed above, or may be selected from the group consisting of n-butyraldehyde, isobutyraldehyde, 2-ethylhexanal, and combinations thereof.

[0060] In various embodiments, the one or more poly(vinyl acetal) resins may be poly(vinyl butyral) (PVB) resins. In other embodiments, the one or more poly(vinyl acetal) resins may be poly(vinyl butyral) resins that contain primarily residues of n-butyraldehyde and may, for example, include no more than about 50, no more than about 40, no more than about 30, no more than about 20, no more than about 10, no more than about 5, or no more than about 2 weight percent of residues of aldehydes other than butyraldehyde, based on the total weight of all aldehyde residues of the resin.

[0061] As used herein, a multilayer panel may include a single substrate, such as glass, acrylic or polycarbonate (or other rigid substrate), on which a polymer interlayer sheet is disposed, and most commonly, a polymer film is also disposed on the polymer interlayer. The combination of a polymer interlayer sheet and a polymer film is generally referred to as a double layer in the art. A typical multilayer panel with a double-layer structure is: (glass) / / (polymer interlayer sheet) / / (polymer film), wherein the polymer interlayer sheet may include multiple interlayers, as described above. The polymer film provides a smooth, thin rigid substrate, thereby providing better optical characteristics than those typically obtained using only polymer interlayer sheets, and acts as a performance enhancement layer. As used herein, the difference between a polymer film and a polymer interlayer sheet is that the polymer film itself does not provide the necessary penetration resistance and glass retention characteristics, but rather provides performance improvements or functional attributes, such as infrared absorption characteristics. Poly (ethylene terephthalate) ("PET") is the most commonly used polymer film. Typically, as used herein, polymer films are thinner than polymer sheets, such as about 0.001 to 0.2 mm thick, but other thicknesses may be used. The polymer film may be referred to as a functional film or layer, especially when it provides a specific property improvement or functionality to the interlayer.

[0062] The interlayers of the present disclosure will most often be used in multilayer panels comprising two substrates, such as a pair of glass sheets (or other rigid materials known in the art, such as polycarbonate or acrylic), with the interlayer disposed between the two substrates. An example of such a construction would be: (glass) / / (polymer interlayer sheet) / / (glass), where the polymer interlayer sheet may include a multilayer interlayer as described above. These examples of multilayer panels are in no way intended to be limiting, as one of ordinary skill in the art will readily recognize that many constructions other than those described above may be made with the interlayers of the present disclosure.

[0063] A typical glass lamination process includes the following steps: (1) assembling two substrates (e.g., glass) and an interlayer (as further described herein); (2) heating the assembly for a short time via IR radiation or convection means; (3) passing the assembly into a pressure nip roller for a first degassing; (4) heating the assembly a second time to about 60° C. to about 120° C. to provide the assembly with sufficient temporary adhesion to seal the edges of the interlayer; (5) passing the assembly into a second pressure nip roller to further seal the edges of the interlayer and allow for further processing; and (6) autoclaving the assembly at a temperature between about 125° C. and 150° C. and a pressure between about 180 psig and 200 psig for about 30 to 90 minutes. The actual steps, as well as the times and temperatures, can be varied as desired, as known to those skilled in the art.

[0064] Other means known in the art and commercially practiced for degassing the interlayer-glass interface (steps 2 to 5) include vacuum bag and vacuum ring processes, where a vacuum is used to remove the air.

[0065] The coefficient of friction measures the friction between the interlayer and the substrate. Friction is a complex phenomenon affected by many factors such as roughness, embossing pattern, hardness, surface energy, surface treatment or coating, chemical compatibility, pressure and ambient temperature. Materials with lower surface energy generally exhibit less friction, while materials with higher surface energy will have a higher COF.

[0066] Coefficient of friction (COF) is measured according to ASTM D1894. Samples are measured in two ways. COF is measured by testing material to material (interlayer to interlayer) and interlayer to metal slide as described in D1894. Samples are conditioned for 40 hours before testing at 23°C and 50% relative humidity. The test speed used is 150mm / min. Samples are cut into 5 inches wide x 10 inches long for interlayer to slide COF testing, and are cut into 5 inches wide x 10 inches long and tested for 2.5 inches x 2.5 inches interlayer on slide for interlayer to interlayer COF testing.

[0067] Heat shrinkage was measured as follows: interlayer sheet samples were cut from rolls immediately after extrusion. Individual samples (10 cm long in the machine direction) were marked using a template and each individual sample was then placed on a piece of cardboard. The samples on the cardboard were placed on a rack in an oven (temperature preset to 54°C). The samples were then removed from the oven after 10 minutes and placed on a bench to cool to room temperature for at least 5 minutes. The sample length in the machine direction was measured using a calibrated ruler before and after the 54°C oven treatment. Shrinkage was calculated as the percentage of the change in length in the machine direction relative to the initial length before the oven treatment.

[0068] Surface roughness (Rz and Rsm) was measured on interlayer samples using a Mahr M1 500 Perthometer. Each sample was measured at three locations, and three surface traces were run in the machine and cross-machine directions at each measurement location. The reported surface Rz and Rsm values ​​are the averages from both directions on the top and bottom sides of the sheet from three locations.

[0069] The damping loss factor (η) is measured by mechanical impedance measurement (MIM) as described in ISO 16940. For the multilayer interlayers used in the following examples, the damping loss factor (MIM) is measured in the laboratory on small laminate samples or strips. The sample is 25 mm wide x 300 mm long (approximately 1" x 12") and has a pair of 2.3 mm transparent glass substrates, which are prepared by a standard lamination method. The sample is excited at the center point of the strip by a vibration table (Brüel and Kjaer). The force used to excite the strip to vibrate is measured using an impedance head (Brüel and Kjaer), and the vibration velocity and the resulting transfer function are recorded on a National Instruments data acquisition and analysis system. The loss factor in the first vibration mode is calculated using the half-power method. The laminate is conditioned at room temperature for 3 months after lamination and conditioned at the test temperature (e.g., 20°C) for at least 4 hours before performing the MIM test.

[0070] In an embodiment, the laminated glazing may be a window of a vehicle, such as a side window.

[0071] In an embodiment, an interlayer in a laminated glazing may include an interlayer wherein the first poly(vinyl acetal) resin and the third poly(vinyl acetal) resin are the same. In an embodiment, the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 2.0 (2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0 or more) weight percent. In an embodiment, the difference between the first residual acetate content and the second residual acetate content is at least 2.0 (2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0 or more) weight percent.

[0072] In embodiments, the first plasticizer and the third plasticizer are identical. In other embodiments, the second plasticizer is identical to at least one of the first plasticizer or the third plasticizer. In embodiments, at least one plasticizer can be a mixture of two or more plasticizers. In embodiments, at least one plasticizer can be a high refractive index plasticizer as defined herein.

[0073] In an embodiment, the interlayer is colored (i.e., opaque and has a low visual transmittance, such as less than 75%), such as gray (light gray, dark gray, or any gray). In other embodiments, the interlayer contains an IR absorber in at least one layer. In an embodiment, the interlayer may be colored and may contain an IR absorber in at least one layer.

[0074] In an embodiment, the interlayer further comprises at least one non-poly(vinyl acetal) layer. In an embodiment, the interlayer comprises a bonding layer between layers. In an embodiment, the interlayer comprises a functional film, layer or sheet. In an embodiment, the interlayer comprises at least one non-poly(vinyl acetal) layer and a functional film, layer or sheet.

[0075] In an embodiment, the multilayer glass panel including the interlayer has a damping loss factor (η) at 20° C. measured according to ISO 16940 of at least 0.20 (0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 or more).

[0076] Any feature described herein may be combined with any other feature. For example, a laminated glazing or windshield may include an interlayer having a non-poly(vinyl acetal) layer and / or a functional film, layer or sheet, and the interlayer may be tinted, or the interlayer may contain an IR absorber in at least one layer and may also be tinted, or the interlayer may be such that the first poly(vinyl acetal) resin and the third poly(vinyl acetal) resin are identical and also have at least a first and a second residual hydroxyl content, wherein the difference between the first residual hydroxyl and / or acetate content and the second residual hydroxyl and / or acetate content is at least 2.0 (2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0 or more) weight percent. Other combinations of features are also included and contemplated.

[0077] Example

[0078] Exemplary multilayer interlayers (DE-1 to DE-6) and comparative interlayers (CE-1) were produced by mixing and melt extruding 100 parts of poly(vinyl butyral) resin and various amounts of plasticizers and other common additives (as described above), as shown in Table 1. For the disclosed embodiments, a mixture of 3GEH and DPG-dibenzoate plasticizers was used, and the amount (%) of 3GEH in the mixture is shown in Table 1. The comparative (control) embodiments used only 3GEH plasticizer. The core layer thickness of all samples (DE-1 to DE-6 and CE-1) was about 4.5 mils. The total thickness of each interlayer is shown in Table 1.

[0079] The four PVB resins used to make these layers include:

[0080] PVB1: PVB resin having a residual PVOH content of about 23.8 wt%.

[0081] PVB2: PVB resin having a residual PVOH content of about 18.5 wt%.

[0082] PVB3: PVB resin having a residual PVOH content of about 9 wt%.

[0083] PVB4: PVB resin having a residual PVOH content of about 10.5 wt%.

[0084] The resulting multilayer interlayers were then tested and used to construct various laminates as shown in the table and described more fully below. The improvements in acoustic properties such as the damping loss factor (η), as well as the COF and thermal shrinkage, can be most easily appreciated by comparing the interlayers and laminates containing the multilayer (tri-layer) interlayers. As shown and discussed below, these examples demonstrate that the disclosed interlayers have improved (lower) coefficients of friction and thermal shrinkage, while also having excellent acoustic damping properties when certain changes are made to the multilayer interlayer.

[0085] Table 1 shows the composition and MIM damping loss factor of the disclosed multilayer interlayer sheets and comparative multilayer interlayer sheets.

[0086] Table 1

[0087]

[0088] The COF of the disclosed multilayer interlayers (DE-1 to DE-6) and the comparative multilayer interlayer (CE-1) as shown in Table 1 was tested by testing both interlayer to interlayer and interlayer to metal slide according to ASTM D1984 (described previously). Both channel patterns (non-random or regular embossed patterns) and random rough surface patterns were tested for the disclosed interlayers. Comparative interlayers with channel patterns or regular surface patterns were also tested. The results are shown in Table 2 below.

[0089] Table 2

[0090]

[0091]

[0092] As shown in Table 2, the disclosed interlayers DE-1 to DE-6 had significantly lower COFs (static and dynamic) compared to the comparative interlayer when tested against both the interlayer and the metal slide.

[0093] Two samples (DE-1 and CE-1) were also tested for heat shrinkage according to the previously described heat shrinkage test method. The lamination processability of the samples was also examined to determine how they were handled during processing. Processing involved handling the samples (interlayer blanks) cut from the roll using a suction cup to place the interlayer blank on a sheet of glass, followed by a second sheet of glass to form a pre-assembly. The interlayer blanks were not allowed to relax; instead, they were used immediately after being cut from the roll. The pre-assembly was then degassed and autoclaved, and the final assembly was evaluated to determine if there was any interlayer shorting due to shrinkage. The results and observations on processability and handling are shown in Table 3 below.

[0094] Table 3

[0095]

[0096]

[0097] As shown in Table 3, the disclosed sample DE-1 has significantly improved processability and lower shrinkage compared to the comparative example CE-1, which has significantly higher COF and heat shrinkage than DE-1. Although the disclosed example has no sticking between the interlayer blanks when placed in a blank stack (as previously described) and then picked up by the suction cup, about 20% of the comparative interlayer blanks have problems during handling and moving and stick to each other (when moved or lifted from the stack). For the comparative interlayer, there is also a problem of the interlayer not being long enough (interlayer short) when the interlayer blank is used immediately after being cut from the roll, while the disclosed interlayer with much lower heat shrinkage value does not show the problem of interlayer short.

[0098] It has been discovered that high damping acoustic interlayers having specific combinations of additional features, such as a higher glass transition temperature in the outer or skin layer combined with lower thermal shrinkage and lower static friction coefficient, have improved handling and processability and allow for the manufacture of multilayer panels using automated assembly processes.

[0099] In summary, interlayers and laminated glazings, such as side windows and windshields for automobiles, comprising the multilayer interlayer according to the present invention have better (smaller) thermal shrinkage values, reduced COF and enhanced damping compared to other multilayer interlayers and laminated glazings comprising the interlayer. Other advantages will be apparent to those skilled in the art.

[0100] Although the present invention has been disclosed in conjunction with the description of certain embodiments (including those currently believed to be preferred embodiments), the detailed description is intended to be illustrative and should not be construed as limiting the scope of the present disclosure. As will be appreciated by those of ordinary skill in the art, embodiments other than those described in detail herein are also encompassed in the present invention. Modifications and variations may be made to the described embodiments without departing from the spirit and scope of the present invention.

[0101] It is also understood that any range, value, or feature given for any individual component of the present disclosure may be used interchangeably with any range, value, or feature given for any other component of the present disclosure, where compatible, to form embodiments having defined values ​​for each component as given throughout this document. For example, an interlayer comprising poly(vinyl butyral) having a residual hydroxyl content within any given range, in addition to a plasticizer within any given range, may be formed to form numerous permutations that are within the scope of the present disclosure, but that would be cumbersome to list. Furthermore, unless otherwise indicated, ranges provided for a genus or class, such as phthalates or benzoates, may also apply to species within the members of that genus or class, such as dioctyl terephthalate.

Claims

1. A polymer interlayer comprising at least one layer, wherein the interlayer has a thermal shrinkage of less than about 4.0%, a static coefficient of friction (COF) of less than 1.50 when measured in an interlayer-on-interlayer configuration according to ASTM D1894, and a laminated glazing including the interlayer has a damping loss factor (η) of at least 0.20 when measured at 20°C according to ISO 16940.

2. The interlayer of claim 1, wherein the interlayer has a static coefficient of friction (COF) of less than 2.00 when measured in an interlayer-to-metal slide configuration according to ASTM D1894.

3. The interlayer of claim 1, wherein the interlayer has a coefficient of kinetic friction (COF) less than 0.50 when measured in the interlayer-to-interlayer configuration according to ASTM D1894.

4. The interlayer of claim 1, wherein the interlayer has a kinetic coefficient of friction (COF) of less than 1.00 when measured in accordance with ASTM D1894 with the interlayer against a metal slide plate configuration.

5. The interlayer of any one of claims 1 to 4, wherein the interlayer is a multilayer interlayer.

6. The interlayer according to any one of claims 1 to 5, wherein the interlayer is a multi-layer interlayer, and the multi-layer interlayer comprises: A first layer comprising a first poly(vinyl acetal) resin having a first residual hydroxyl content and a first residual acetate content, and a first plasticizer, wherein the first layer has a glass transition temperature (T g ); a second layer comprising a second poly(vinyl acetal) resin having a second residual hydroxyl content, a second residual acetate content, and a second plasticizer, wherein the second layer has a glass transition temperature (T g );as well as a third layer comprising a third poly(vinyl acetal) resin having a third residual hydroxyl content, a third residual acetate content, and a third plasticizer, wherein the third layer has a glass transition temperature (T g ), The second layer is located between the first layer and the third layer.

7. The interlayer of any one of claims 1 to 6, wherein the interlayer is pigmented and has a %T of less than about 75%.

8. The interlayer of claim 7, wherein the interlayer is grey in color.

9. The interlayer of any one of claims 1 to 8, wherein the interlayer comprises an IR absorber.

10. The interlayer of any one of claims 1 to 9, wherein the interlayer further comprises a non-poly(vinyl acetal) layer.

11. The interlayer of any one of claims 1 to 10, wherein the interlayer further comprises a functional film, layer or sheet.

12. The interlayer of claim 6, wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 2.0 weight percent.

13. The interlayer of claim 6, wherein the difference between the first residual acetate content and the second residual acetate content is at least 2.0 weight percent.

14. A laminated glazing comprising a first rigid substrate, an interlayer as claimed in any one of claims 1 to 13, and a second rigid substrate, wherein the interlayer is between the first rigid substrate and the second rigid substrate, and wherein the laminated glazing is a side window, sunroof or other window in a vehicle.

15. A method for manufacturing a multi-layer glass panel, the method comprising the steps of: providing a first rigid substrate to an assembly fixture, Providing a polymer interlayer as claimed in claim 1, Using a conveying device to place the sandwich blank on the first rigid substrate, providing a second rigid substrate, and The second rigid substrate is placed on the sandwich blank to form a pre-assembly.

16. The method of claim 15 further comprising the step of moving the pre-assembly to a degassing process.

17. The method of claim 16, wherein the degassing process comprises nip rolls, a vacuum bag or a vacuum ring.

18. The method of claim 16, further comprising moving the pre-assembly into an autoclave to form a final multi-layer panel.

19. The method of claim 18, wherein the multi-layer panel is a side window, sunroof or other window in a vehicle.

20. A multi-layer panel comprising: a first glass substrate; polymer interlayer; as well as a second rigid substrate; wherein the interlayer has a thermal shrinkage of less than about 4.0%, a static coefficient of friction (COF) of less than 1.50 when measured in an interlayer-to-interlayer configuration according to ASTM D1894, and wherein the multilayer panel has a damping loss factor (η) of at least 0.20 when measured at 20°C according to ISO 16940.

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