Intermediate layer having improved bonding processability

Abstract

An intermediate layer is disclosed that has improved bonding processability and at the same time has excellent sound characteristics or acoustic properties. The intermediate layer has a heat shrinkage rate of less than about 4%, and a coefficient of static friction (COF) measured in accordance with ASTM D1894 in an arrangement where the intermediate layer is in contact with the intermediate layer is less than 1.50. The laminated window glass has a damping loss factor (η) of at least 0.20 when measured at 20 °C in accordance with 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. Specifically, the present disclosure relates to the field of multilayer panels including a polymer interlayer comprising a multiple thermoplastic layer having improved acoustic properties, such as improved damping properties, as well as improved processability and ease of handling. The present disclosure also relates to an improved process for assembling laminated window glass using the improved interlayer of the present invention.

Background Art

[0002] Multilayer panels generally are panels composed of two substrates (e.g., but not limited to, glass, polyester, polyacrylate or polycarbonate) with one or more polymer interlayers sandwiched therebetween. Laminated multilayer glass panels generally are utilized in applications for architectural windows, as well as automotive and aircraft windows, and solar panels for solar power generation. The first two applications generally are referred to as laminated safety glass. The primary functions of the interlayer in laminated safety glass are to absorb energy resulting from an impact or force applied to the glass, to keep the glass layers bonded together even when the glass is cracked by an applied force, and to prevent the glass from breaking into sharp fragments. In addition, the interlayer also can impart a much higher sound insulation rating to the glass, can reduce UV and / or IR light transmittance, and can enhance the aesthetic appeal of the associated window. With respect to solar power generation applications, the primary function of the interlayer is to encapsulate solar panels for solar power generation used to generate and supply electricity for commercial and residential use.

[0003] To achieve certain characteristics and performance properties of a glass panel, it is conventional to utilize a multilayer, or multi-layered, interlayer. As used herein, the terms "multilayer" and "multi-layered" mean an interlayer having more than one layer, and multilayer and multi-layered may be used interchangeably. A multi-layered interlayer typically contains at least one soft layer and at least one hard layer. An interlayer having one soft "core" layer sandwiched between two other rigid or hard "skin" layers is designed to have sound insulation properties for a glass panel. An interlayer having the reverse configuration, i.e., one hard layer sandwiched between two other soft layers, has been found to improve the impact performance of a glass panel and may likewise be designed for sound insulation. Examples of multi-layered interlayers also include an interlayer having at least one "transparent" or uncolored layer, and at least one colored layer or at least one conventional layer, such as a non-acoustic layer, and at least one acoustic layer (i.e., the layer has acoustic properties or the ability to provide sound insulation or reduce sound transmission as further defined below). Another example of a multi-layered interlayer is an interlayer having at least two layers of different colors for aesthetic appeal. The colored layer typically contains a pigment or dye, or a combination of a pigment and a dye.

[0004] The layers of the interlayer are generally manufactured 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, such as, but not limited to, extrusion. A multi-layered interlayer can be manufactured by processes such as co-extrusion or lamination that combine the layers to form a single structure. Other additional ingredients may optionally be added for various other purposes. After the interlayer sheet is formed, it is typically recovered and wound up for transportation and storage, as well as for later use in a multi-layered glass panel as described below.

[0005] The following presents a simplified explanation of a general method for manufacturing a multilayer glass panel in combination with an intermediate layer. First, at least one polymer intermediate layer sheet (single-layer or multi-layer) is placed between two substrates, and the excess intermediate layer is cut off from the edges to create an assembly. It is not uncommon to place a multi-polymer intermediate layer sheet, or a polymer intermediate layer sheet having multiple layers (or a combination of both) inside the two substrates to create a multilayer glass panel having a multi-polymer intermediate layer. Next, air is 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 other degassing mechanisms. In addition, the intermediate layer is partially press-bonded to the substrate by any method known to those skilled in the art. In the final step, this preliminary bonding is made more permanent by a high-temperature and high-pressure lamination process or any other method known to those skilled in the art, for example, but not limited to, autoclave treatment, to form the final integral structure.

[0006] Multilayer intermediate layers, such as a three-layer intermediate layer having one soft core layer and two harder skin layers, are commercially available. The hard skin layers provide ease of handling, processing and mechanical strength of the intermediate layer, and the soft core layer provides acoustic attenuation properties.

[0007] The vibration attenuation properties of laminated glass for vehicle window glass applications, for example, laminated glass for windshields, side laminates and sunroofs, are essential for the vehicle cabin noise level. This is because vehicle window glass occupies a large portion of the vehicle cabin area and is the main route for external noise (e.g., wind noise, road noise, tire noise, engine noise) to enter the vehicle cabin. By providing laminated glass with high vibration attenuation properties for window glass, it will be possible to absorb more external noise or sound and make the cabin quieter. These high damping laminates can absorb more external noise when used for automotive window glass.

[0008] It is required to maximize the vibration damping property of the laminate while simultaneously satisfying the industrial safety requirements for vehicle window glass applications. The present invention discloses an intermediate layer that improves the manufacturing efficiency of the glass laminate and provides a high vibration damping loss factor while satisfying the industrial requirements of vehicle window glass. The present invention also provides a process for more efficiently handling the intermediate layer that always satisfies the stringent lamination processability requirements, particularly those in the robot-based lamination integration process.

[0009] In summary, it is now common to use multi-layer intermediate layers to provide high-performance laminates. In the art, it is necessary to develop multi-layer intermediate layers having good optical, mechanical, and acoustic properties, which are desirable in multi-layer intermediate layers. More specifically, there is a need in the art to develop multi-layer intermediate layers having good acoustic properties, such as a vibration damping loss factor, and that can be used and processed more efficiently.

Summary of the Invention

Means for Solving the Problems

[0010] For these and other problems in the art, described herein is, among others, a polymer interlayer having a heat shrinkage rate 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), 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 according to ASTM D1894 in an arrangement where the interlayer is in contact with the interlayer, and a multilayer glass panel including the interlayer having 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 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 according to ASTM D1894 in an arrangement where the interlayer is in contact with the metal trough. In an embodiment, the interlayer has a coefficient of kinetic friction (COF) of less than 0.50 (0.45, 0.40, 0.35, 0.30, or less) when measured according to ASTM D1894 in an arrangement where the interlayer is in contact with the interlayer. In an embodiment, the interlayer has a coefficient of kinetic friction (COF) of less than 1.00 (0.95, 0.90, 0.85, 0.80, 0.75, 0.70) when measured according to ASTM D1894 in an arrangement where the interlayer is in contact with the metal trough.

[0011] In an embodiment, the intermediate layer is a first layer containing a first poly(vinyl acetal) resin having a first residual hydroxyl content and a first residual acetate content, and a first plasticizer, and having a glass transition temperature (T g ) above 37°C, the first layer; a second layer containing a second poly(vinyl acetal) resin having a second residual hydroxyl content and a second plasticizer, and having a glass transition temperature (T g ) below 20°C, the second layer; and a third layer containing a third poly(vinyl acetal) resin having a third residual hydroxyl content and a third plasticizer, and having a glass transition temperature (T g ) above 37°C, the third layer, the multilayer intermediate layer including the second layer being between the first layer and the third layer, the multilayer intermediate layer.

[0012] In an embodiment, the laminate includes a first glass substrate, a polymer intermediate layer, and a second rigid substrate. The polymer intermediate layer has a heat shrinkage rate 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). The coefficient of static friction (COF) measured in accordance with ASTM D1894 when the intermediate layer is in contact with the intermediate layer in the intermediate layer is 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). The damping loss factor (η) of the multilayer glass panel including the intermediate layer measured at 20 °C in accordance with ISO16940 is 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). In an embodiment, the coefficient of static friction (COF) of the intermediate layer measured in accordance with ASTM D1894 when the intermediate layer is in contact with the metal trough is 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). In an embodiment, the coefficient of kinetic friction (COF) of the intermediate layer measured in accordance with ASTM D1894 when the intermediate layer is in contact with the intermediate layer is less than 0.50 (0.45, 0.40, 0.35, 0.30, or less). In an embodiment, the coefficient of kinetic friction (COF) of the intermediate layer measured in accordance with ASTM D1894 when the intermediate layer is in contact with the metal trough is less than 1.00 (0.95, 0.90, 0.85, 0.80, 0.75, 0.70).

[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 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.

[0015] In an embodiment, the intermediate layer is a colored intermediate layer. In an embodiment, the colored intermediate layer 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 referred to as visual transmittance %T and is measured in accordance with Procedure B of ASTM D1003-13 at an observer angle of 2 degrees using a light source C. In an embodiment, the colored intermediate layer is a gray, for example, a light gray or dark gray intermediate layer sheet.

[0016] In an embodiment, the intermediate layer includes an IR absorber. In an embodiment, the intermediate layer is a multilayer intermediate layer having an IR absorber in at least one layer.

[0017] In an embodiment, the intermediate layer further includes a non-poly(vinyl acetal) layer. In an embodiment, the intermediate layer is a non-poly(vinyl acetal) layer that is a functional film, layer or sheet(s), for example, a polyethylene terephthalate (PET) film, a coated PET film, or other layer, for example, an IR absorption or IR reflection film.

[0018] Also disclosed is a method of making a polymer intermediate layer, wherein the polymer intermediate layer is as disclosed herein.

[0019] In an embodiment, disclosed is a process for making a laminate, the process including the steps of supplying a first rigid substrate to an assembly fixture, supplying an intermediate layer blank, disposing the intermediate layer blank on the first rigid substrate using a transport device, supplying a second rigid substrate, and disposing the second rigid substrate on the intermediate layer blank thereby forming a preliminary laminate.

[0020] In an embodiment, the laminated window glass is a vehicle windshield, side glass, sunroof, or other window. In an embodiment, the laminated window glass is used for head-up display applications.

[0021] In certain embodiments, the rigid substrate(s) is glass.

Best Mode for Carrying Out the Invention

[0022] Described herein is, among other things, a laminated window glass composed of a first rigid substrate and a second rigid substrate, and a multilayer polymer intermediate layer. The intermediate layer of the present disclosure, and thus the laminated window glass, has improved acoustic or sound insulation properties as measured by the damping loss factor. The laminated window glass including the intermediate layer of the present invention 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) as measured in accordance with ISO 16940. The intermediate layer of the present invention also has a coefficient of static friction (measured in accordance with ASTM D1894 with the intermediate layer in contact with another intermediate layer) of less than 1.50.

[0023] Further described is an automated process for making a multilayer glass panel, such as a side glass, sunroof or windshield. The process includes supplying a first rigid substrate to an assembly fixture, supplying an intermediate layer blank, using a transport device to dispose the intermediate layer blank on the first rigid substrate, supplying a second rigid substrate, and disposing the second rigid substrate on the intermediate layer blank thereby forming a preliminary assembly. The preliminary assembly can be placed on a conveyor or other means for moving the preliminary assembly for further processing. In an embodiment, the first rigid substrate and / or the second rigid substrate can be supplied using the same or a similar transport device as the transport device used to supply the intermediate layer blank. In an embodiment, the preliminary assembly is further processed by advancing the preliminary assembly into a degassing process, such as a nip roll machine, vacuum bag, vacuum ring or other process. After degassing, the preliminary assembly can be further processed in an autoclave or the like.

[0024] As used herein, a "transport device" is any device or means for automatically (or partially automatically or semi-automatically) moving or conveying an article, such as an intermediate layer blank or a rigid substrate. A transport device moves an article automatically (e.g., using controls or programming) and without physically picking up, carrying or moving the article by hand and placing it in another location. Transport devices are known in the art. In an embodiment, the transport device is a robot or robotic arm. In an embodiment, the transport device can have a suction cup or other means for picking up the rigid substrate and / or the intermediate layer blank.

[0025] Further described is a multilayer glass panel including an intermediate layer. The intermediate layer of the present invention can be used in multilayer glass panel applications, such as, among other applications, windshield, side window, sunroof and roof safety glass, and architectural windows.

[0026] In a lamination integration process by a robot, typically, a bottom glass sheet (or a piece of glass material) is picked up by a suction cup by a conveying device (e.g., a robot arm), placed on an integration fixture for making a laminated window glass (e.g., side laminate), the intermediate layer is cut to size to form an intermediate layer blank from a roll, the intermediate layer blank is picked up by another conveying device and directly stacked on the bottom glass sheet, and then, the upper glass sheet is picked up by a conveying device and placed on the intermediate layer blank to form a preliminary laminate. The preliminary laminate is, for example, placed on a conveyor and moved to a degassing area, the degassing process is completed to form a completed laminate, and then, the completed laminate is autoclaved to produce the final laminated glass. The intermediate layer blank may be cut out from the roll and used immediately (e.g., picked up and conveyed), or the roll may be cut into intermediate layer blanks of appropriate sizes and stacked on top of each other (thereby forming a stack of intermediate layer blanks) for use in a later step in the process. This type of automatic integration process provides the following advantages: reduction in labor costs, improvement in capacity, reduction in yield loss due to fewer out-of-grade or non-conforming parts caused by human process errors, reduction in the tendency of foreign matter contamination (such as handling), and reduction in the need to pre-arrange the schedules of workers who manually assemble the window glass. Other advantages may be recognized by those skilled in the art.

[0027] However, when using a conventional intermediate layer, there are at least two problems that can endanger the automatic process and reduce productivity: namely, the conveying device (i.e., the robot arm) cannot pick up the intermediate layer due to the flexibility of the intermediate layer and / or the adhesiveness with other adjacent layers or surfaces (either another intermediate layer blank or the surface on which the blank is placed); the intermediate layer shrinks too much when exposed to heat in the degassing process, which causes edge defects in the final laminated glass, such as a shortage of the intermediate layer along the edge and the formation of air bubbles.

[0028] This shrinkage can be caused or exacerbated by processing conditions and can be minimized, for example, by avoiding excessive stretching during manufacturing, transportation, and winding, or by pre-relaxing the sheet prior to winding. Additionally, the sheet may further relax immediately prior to use.

[0029] Currently, to address the issue of shrinkage, the laminator must undergo additional processing steps. One such extra step involves pre-cutting the intermediate layer blank larger than the glass size and allowing the intermediate layer blank to relax over 24 - 48 hours prior to the lamination process. By pre-cutting the intermediate layer blank, this increases the amount of sheet handling steps, turnaround time, waste (yield loss) of the intermediate layer, and limits production capacity. With respect to the tackiness of the intermediate layer (i.e., the tendency of the intermediate layer to adhere to itself or other surfaces, such as the workbench), the laminator must either adjust process conditions such as room temperature, apply manual intervention, or apply other process modifications to avoid malfunction of the conveying device.

[0030] These and other advantages can be achieved by the multi-layer intermediate layer of the present invention having a reduced shrinkage rate, lower COF, and high acoustic attenuation properties.

[0031] Each layer of the multi-layer polymer intermediate layer can be made by mixing one or more polymer resins, such as poly(vinyl acetal) resins (e.g., PVB), and one or more plasticizers. The multi-layer intermediate layer generally contains two or more layers and two or more resins with different compositions. For example, poly(vinyl acetal) resins with different residual hydroxyl contents and / or residual acetate contents, such as PVB resins, are suitable for the layers of the multi-layer intermediate layer composition. In a multi-layer including 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 "more flexible 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 compared to another layer and generally has a glass transition temperature at least 2 degrees (2°C) higher than that of another layer (e.g., a more flexible layer).

[0032] The multi-layer intermediate layer formed from the composition 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 multi-layer intermediate layers, such as three-layer acoustic intermediate layers, consist of a soft core layer made of a single poly(vinyl butyral) ("PVB") resin having a low residual hydroxyl content and a large amount of conventional plasticizer, and two hard skin layers having a significantly higher residual hydroxyl content (see, e.g., U.S. Patent 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 such that the intermediate layer provides optimal sound insulation properties for multi-layer glass panels, such as windshield and windows installed in vehicles and buildings, under ambient conditions.

[0034] A multi-layer acoustic intermediate layer such as a three-layer one can be designed and manufactured by: (1) selecting a plasticizer or a mixture of plasticizers; (2) selecting resins for the skin layer(s) and the core layer(s); (3) maintaining the plasticizer balance between the core layer(s) and the skin layer(s) (e.g., by selecting a resin having specific properties); and (4) combining the core layer(s) and the skin layer(s) by an applicable process, such as coextrusion or lamination, to form a multi-layer intermediate layer. When the resin and the plasticizer are appropriately selected with respect to the desired properties and characteristics, the resulting multi-layer acoustic intermediate layer provides excellent transparency and sound insulation properties without sacrificing other beneficial desired properties that conventional multi-layer intermediate layers have, such as optical properties, and the mechanical strength of a glass panel made of the multi-layer acoustic intermediate layer.

[0035] We will describe some of the terms and common components found in the intermediate layer, as well as its formation, with respect to both a general intermediate layer and the intermediate layer of the present disclosure. As used herein, the terms "polymer intermediate layer sheet", "intermediate layer", and "polymer melt sheet" generally can refer to a single-layer sheet or a multi-layered intermediate layer. A "single-layer sheet" is a single polymer layer extruded as one layer, as the name implies. On the other hand, a multi-layered intermediate layer can include multiple layers, including separately extruded layers, co-extruded layers, or any combination of separately extruded layers and co-extruded layers. Thus, a multi-layered intermediate layer can include, for example, two or more combined single-layer sheets ("multi-layer sheet"); two or more layers co-extruded together ("co-extruded sheet"); two or more combined co-extruded sheets; a combination of at least one single-layer sheet and at least one co-extruded sheet; a combination of a single-layer sheet and a multi-layer sheet; and a combination of at least one multi-layer sheet and at least one co-extruded sheet. In various embodiments of the present disclosure, the multi-layered intermediate layer includes at least two polymer layers (e.g., single-layer or multi-layer co-extruded and / or laminated together) arranged to be in direct contact with each other, and each layer includes a polymer resin that is further detailed below. When used herein with respect to a multi-layer intermediate layer having at least three layers, a "skin layer" generally refers to the outer layer of the intermediate layer, and a "core layer" generally refers to the inner layer(s). Thus, one exemplary embodiment is a skin layer / / core layer / / skin layer. In a multi-layer intermediate layer having a skin layer / / core layer / / skin layer configuration, 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 known acetalization processes involving reacting polyvinyl alcohol (“PVOH”) with one or more aldehydes, such as butyraldehyde, in the presence of an acid catalyst, followed by separation, stabilization, and drying of the resin. Such acetalization processes are disclosed, for example, in U.S. Patent Nos. 2,282,057 and 2,282,026, as well as Wade, B. 2016, Vinyl Acetal Polymers, Encyclopedia of Polymer Science and Technology. 1-22 (onlyne, copyright 2016 John Wiley & Sons, Inc.), the entire disclosures of which are hereby incorporated by reference. The resins are commercially available in various forms, for example, as the Butvar® resin of Solutia Inc., a wholly-owned subsidiary of Eastman Chemical Company.

[0037] As used herein, the residual hydroxyl content in the poly(vinyl acetal) resin (calculated as % by weight of vinyl alcohol or % by weight of 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 poly(vinyl alcohol) (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. Further, the reaction with butyraldehyde typically does not convert all of the hydroxyl groups to acetal groups. As a result, in any finished PVB resin, typically residual acetate groups (as vinyl acetate groups) and residual hydroxyl groups (as vinyl hydroxyl groups) will be present as side groups on the polymer chain. As used herein, the residual acetate content (calculated as the vinyl acetate content in the poly(vinyl acetal) or % by weight of poly(vinyl acetate) (PVAc)) refers to the amount of residual groups remaining on the polymer chain. As used herein, the residual hydroxyl content and the residual acetate content are measured on a weight percent (wt%) basis in accordance with ASTM D1396.

[0038] In embodiments where the multilayer intermediate layer 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 more flexible. Other combinations and numbers of layers are also possible.

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

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

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

[0042] The difference in the residual hydroxyl and / or residual acetate levels between poly(vinyl acetal) resins is calculated by subtracting the residual hydroxyl content of the resin with the lower residual hydroxyl content from the residual hydroxyl content of the resin with the higher residual hydroxyl content. As used herein, the terms "differ only by weight percent" or "the difference is at least... weight percent" refer to the difference between two given weight percents 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 2 weight percent lower (14 weight percent - 12 weight percent = 2 weight percent) compared to a poly(vinyl acetal) resin having a residual hydroxyl content of 14 weight percent. As used herein, the term "different" can refer to a value that is higher or lower compared to another value. The intermediate layer may also have one or more other poly(vinyl acetal) layers, and the residual hydroxyl thereof may be 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 poly(vinyl acetal) resin and / or the second poly(vinyl acetal) resin. The additional poly(vinyl acetal) layer present in the intermediate layer may have a residual acetate content that is the same as or different from the residual acetate content of the first poly(vinyl acetal) resin and / or the second poly(vinyl acetal) resin.

[0043] The poly(vinyl acetal) resins of the present disclosure, such as poly(vinyl butyral) (PVB) resin(s), typically have a molecular weight measured by size exclusion chromatography using a low angle laser light scattering detector, a differential refractometer, or a UV detector that is 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 used herein, the term "molecular weight" means the weight average molecular weight.

[0044] To control the adhesion of the interlayer sheet to glass, various adhesion control agents ("ACA") can be used in the interlayer of the present disclosure. In various embodiments of the interlayer of the present disclosure, the interlayer can include from about 0.003 to about 0.15 parts of ACA per 100 parts of resin; from about 0.01 to about 0.10 parts of ACA per 100 parts of resin; and from about 0.01 to about 0.04 parts of ACA per 100 parts of resin. Such ACAs include, but are not limited to, the ACAs disclosed in U.S. Patent 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 can be incorporated into the interlayer to improve its performance in the final product and impart certain additional properties to the interlayer. Such additives include, but are not limited to, among several additives known to those skilled in the art, dyes, pigments, stabilizers (e.g., ultraviolet 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 improvers, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives, and fillers.

[0046] In various embodiments, the plasticizer can 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". Examples of conventional plasticizers include 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, hexyl cyclohexyl adipate, diisononyl adipate, heptyl nonyl adipate, di(butoxyethyl) adipate, and bis(2-(2-butoxyethoxy)ethyl) adipate, dibutyl sebacate, dioctyl sebacate, and mixtures thereof, but are not limited thereto. These plasticizers have a refractive index of about 1.442 to about 1.449. In contrast, PVB resin has a refractive index of approximately 1.485 to 1.495. In the intermediate layer manufactured for various properties and uses, 3GEH (refractive index = 1.442) is one of the most common plasticizers present.

[0048] In various embodiments, one or more high refractive index plasticizers may be used. In an embodiment, the high refractive index plasticizer(s) is selected such that the refractive index of the plasticizer in both the core layer and / or the skin layer is at least about 1.460, i.e., 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 having a refractive index of at least about 1.460. In some embodiments, the high refractive index plasticizer(s) is used in combination with a conventional plasticizer, and in some embodiments, when a conventional plasticizer is included, it 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 the plasticizer or resin used throughout the present 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 polyadipates (RI of about 1.460 to about 1.485); epoxides (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 special plasticizers (RI of about 1.490 to about 1.520), but are not limited thereto. Specific examples of suitable high refractive index plasticizers include 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, bisphenol A bis(2-ethylhexanoate), ethoxylated nonylphenol, nonylphenyl tetraethylene glycol, dioctyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, a mixture of benzoic acid esters of dipropylene glycol and diethylene glycol, and mixtures thereof, but are not limited thereto.

[0050] The total plasticizer content in the intermediate layer can be in the range of 0 to 120 phr, or more than 0 phr, or more than 5 phr, or more than 10 phr, or more than 15 phr, or more than 20 phr, or more than 25 phr, or more 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 10 to 100 phr, or 20 to 80 phr, or 30 to 70 phr. In various embodiments of the intermediate layer of the present disclosure, the intermediate layer contains more than 5 phr, about 5 to about 120 phr, about 10 to about 90 phr, about 20 to about 70 phr, about 30 to about 60 phr, or less than 120 phr, or less than 90 phr, or less than 60 phr, or less than 40 phr, or less than 30 phr of total plasticizer. Although the total plasticizer content is shown above, the plasticizer content of the skin layer(s) or core layer(s) can be different from the total plasticizer content. In addition, the skin layer(s) and core layer(s) can have different plasticizer species and plasticizer contents within the above ranges. This is because, as disclosed in U.S. Patent No. 7,510,771 (the entire disclosure of which is incorporated herein by reference), the plasticizer content of each layer in the equilibrium state is determined by the respective residual hydroxyl content of the layer. For example, in the equilibrium state, the intermediate layer can include two skin layers each containing 30 phr of plasticizer and a core layer containing 65 phr of plasticizer, and the total plasticizer amount of the intermediate layer can be about 45.4 phr when the total thickness of the skin layers is equal to the core layer. In the case of thicker or thinner skin layers, the total plasticizer amount of the intermediate layer will change accordingly. When the plasticizer content of the intermediate layer is given, the plasticizer content, as used herein, is determined with reference to the phr of plasticizer in the kneaded product or melt used to produce the intermediate layer.

[0051] The amount of plasticizer in the intermediate layer is the glass transition temperature (T of the intermediate layer g) and can be adjusted to affect the final acoustic performance. The glass transition temperature (T g ) is the temperature at which the transition from the glassy state to the rubbery state of the intermediate layer occurs. Generally, when the compounding amount of the plasticizer is larger, T g becomes lower. Conventional, previously used intermediate layers generally had a T g in the range of about -10 to 25 °C for acoustic (noise reduction) intermediate layers and up to about 45 °C for applications of hurricane and aircraft (harder or structural) intermediate layers. The glass transition temperature (T g ) can be determined by dynamic mechanical thermal analysis (DMTA) in shear mode. DMTA measures the storage modulus (elastic modulus) (G’) in Pascal units of the test specimen, the loss modulus (viscosity coefficient (G”) in Pascal units, and tan delta (= G” / G’) as a function of temperature at a given frequency and temperature sweep rate. In this specification, a frequency of 1 Hz and a temperature sweep rate of 3 °C / min were used. Then, T g is determined by the position of the tan delta peak at the temperature scale in °C, and the peak value of tan delta is referred to as tan delta or peak tan delta. As used in this specification, “tan delta”, “peak tan delta”, “tan δ” and “peak tan δ” can be used interchangeably.

[0052] The glass transition temperature (T g ) of the intermediate layer also correlates with the hardness of the intermediate layer, and generally, the higher the glass transition temperature, the harder the intermediate layer. Generally, an intermediate layer having a glass transition temperature of 30 °C or higher increases the mechanical strength and torsional rigidity of the laminated glass. On the other hand, a flexible layer or intermediate layer (characterized generally by a layer or intermediate layer having a glass transition temperature of less than 20 °C) contributes to the sound attenuation effect (i.e., acoustic properties). The intermediate layer of the present disclosure can have a glass transition temperature of about 26 °C or higher or about 37 °C or higher for harder layer(s), and about 20 °C or lower or 15 °C or lower or 10 °C or lower or about 5 °C or lower or 0 °C or lower or about -5 °C or lower or about -10 °C or lower for soft layer(s), provided that other glass transition temperatures are possible depending on the desired performance and characteristics.

[0053] In some embodiments, the multi-layer intermediate layer of the present disclosure utilizes a harder or stiffer skin layer (e.g., hard / soft / hard) bonded to a more flexible core layer to possess these two beneficial properties, namely strength and acoustics. In various embodiments, the multi-layer intermediate layer generally includes a harder layer(s) comprising poly(vinyl acetal) resin(s) having a glass transition temperature of about 26°C to about 60°C, about 38°C to 48°C, about 26°C or higher, about 30°C or higher, or about 37°C or higher, and a more flexible layer(s) having a glass transition temperature of about 20°C or lower, about 10°C or lower, or about 5°C or lower, or about 0°C or lower, or about -5°C or lower, or about -10°C or lower.

[0054] The final intermediate layer, whether formed by extrusion or co-extrusion or by multi-layer lamination, generally has a disordered rough topography such as that formed by melt fracture of the polymer melt when exiting the extrusion die. In addition, embossing by any embossing method known to those skilled in the art may be applied to one or both sides (e.g., the skin layer) across the disordered rough surface.

[0055] Any method known to those skilled in the art for manufacturing a polymer intermediate layer sheet is contemplated as a possible method for manufacturing the polymer intermediate layer sheet described herein, but the present application focuses on polymer intermediate layer sheets manufactured by extrusion and co-extrusion processes. The final multi-layer glass panel laminate of the present invention is formed using a lamination process known in the art.

[0056] Generally, the thickness or gauge of the polymer interlayer sheet is 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 of the layers 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), although other thicknesses may be selected depending on the desired performance and characteristics.

[0057] Many of the embodiments described below refer to the polymer resin as being PVB, but it will be understood by those skilled in the art that the polymer can be any polymer suitable for use in a multilayer panel. Typical polymers include polyvinyl acetal (PVA) (e.g., poly(vinyl butyral) (PVB) or poly(vinyl isobutyrate), isomers of poly(vinyl butyral), also known as PVisoB, aliphatic polyurethane (PU), poly(ethylene-co-vinyl acetate) (EVA), polyvinyl chloride (PVC), poly(vinyl chloride-co-methacrylate), polyethylene, polyolefin, ethylene acrylate copolymer, poly(ethylene-co-butyl acrylate), silicone elastomer, epoxy resin, and acid copolymers derived from any of the above possible thermoplastic resins, such as ethylene / carboxylic acid copolymers and their ionomers, combinations of the above, etc., but are not limited thereto. PVB, and its isomer polyvinyl isobutyrate, polyvinyl chloride, ionomers, and polyurethanes are generally suitable polymers for the interlayer, and PVB (including its isomer PVisoB) is particularly preferred.

[0058] Examples of exemplary multi-layer intermediate layer compositions include PVisoB layers comprising two or more resins having different residual hydroxyl and / or residual acetate contents or different polymer compositions, such as PVB / / PVisoB / / PVB; the PVB (including PVisoB), PU, or EVA of the core layer can include a single resin having one glass transition or two or more resins having different glass transitions, such as PVC / / PVB / / PVC, PU / / PVB / / PU, ionomer / / PVB / / ionomer, ionomer / / PU / / ionomer, ionomer / / EVA / / ionomer, but are not limited thereto. Alternatively, all of the skin layer and the core layer may 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] Poly(vinyl acetal) resins are generally referred to as poly(vinyl acetal) or poly(vinyl butyral), and any of them may contain residues of any suitable aldehyde as described above, such as isobutyl aldehyde. In some embodiments, one or more poly(vinyl acetal) resins are at least one C1-C 10It may contain residues of an aldehyde or at least one C4-C8 aldehyde. Examples of suitable C4-C8 aldehydes can include, but are not limited to, n-butyl aldehyde, isobutyl aldehyde, 2-methylvaleraldehyde, n-hexyl aldehyde, 2-ethylhexyl aldehyde, n-octyl aldehyde, and combinations thereof. At least one of the first poly(vinyl acetal) resin and the second poly(vinyl acetal) resin may contain 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 residues of at least one C4-C8 aldehyde, based on the total weight of the aldehyde residues of the resin, and / or may contain up to about 90 weight percent, up to about 85 weight percent, up to about 80 weight percent, up to about 75 weight percent, up to about 70 weight percent or up to about 65 weight percent of at least one C4-C8 aldehyde, or may contain at least one C4-C8 aldehyde in the range of about 20 to about 90, about 30 to about 80, or about 40 to about 70 weight percent. The C4-C8 aldehyde may be selected from the group listed above, or it may be selected from the group consisting of n-butyl aldehyde, isobutyl aldehyde, 2-ethylhexyl aldehyde, and combinations thereof.

[0060] In various embodiments, one or more poly(vinyl acetal) resins can be poly(vinyl butyral) (PVB) resins. In other embodiments, one or more poly(vinyl acetal) resins can be poly(vinyl butyral) resins that mainly contain residues of n-butyl aldehyde and contain, for example, residues of aldehydes other than butyl aldehyde at up to about 50 weight percent, up to about 40 weight percent, up to about 30 weight percent, up to about 20 weight percent, up to about 10 weight percent, up to about 5 weight percent or up to about 2 weight percent, based on the total weight of all aldehyde residues of the resin.

[0061] As used herein, a multilayer panel can include a single substrate, such as glass, acrylic, or polycarbonate (or other rigid substrate), with a polymeric intermediate layer sheet disposed thereon, and most commonly, a polymeric film further disposed on the polymeric intermediate layer. The combination of the polymeric intermediate layer sheet and the polymeric film is generally referred to as two layers in the art. A typical multilayer panel having a two-layer structure is (glass) / / (polymeric intermediate layer sheet) / / (polymeric film), where the polymeric intermediate layer sheet can include multiple intermediate layers as described above. The polymeric film provides a smooth and thin rigid substrate that gives better optical characteristics than can typically be obtained with only the polymeric intermediate layer sheet and functions as a performance improvement layer. The polymeric film is different from the polymeric intermediate layer sheet used herein in that the polymeric film provides performance improvement or functional attributes, such as infrared absorbing properties, rather than providing the necessary through resistance and glass holding properties by itself. Poly(ethylene terephthalate) (“PET”) is the most commonly used polymeric film. Generally, as used herein, the polymeric film is thinner than a polymeric sheet, for example, having a thickness of about 0.001 to 0.2 mm, although other thicknesses may be used. The polymeric film may be referred to as a functional film or layer, particularly when the polymeric film provides specific performance improvements or functions to the intermediate layer.

[0062] The intermediate layer of the present disclosure will most commonly be utilized in a multilayer panel that includes two substrates, such as a pair of glass sheets (or other rigid materials known in the art, such as polycarbonate or acrylic), with an intermediate layer disposed therebetween. An example of such a configuration would be (glass) / / (polymeric intermediate layer sheet) / / (glass), where the polymeric intermediate layer sheet can include a multi-laminated intermediate layer 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 numerous configurations other than those described above can be made using the intermediate layer of the present disclosure.

[0063] A typical glass lamination process includes the following steps: (1) integrating two substrates (e.g., glass) with an intermediate layer (further described herein); (2) heating the integrated body briefly by IR radiation or convection means; (3) passing the integrated body through a pressure nip roll machine for the first degassing; (4) reheating the integrated body to about 60°C to about 120°C to impart sufficient temporary adhesion to seal the edges of the intermediate layer to the integrated body; (5) passing the integrated body through a second pressure nip roll machine to further seal the edges of the intermediate layer and enable further handling; (6) autoclaving the integrated body at a temperature of about 125°C to 150°C and a pressure of about 180 psig to 200 psig for about 30 to 90 minutes. The actual process, as well as the time and temperature, can be varied as needed, as is known to those skilled in the art.

[0064] Other means known in the art and commercially implemented for degassing the intermediate layer - glass interface (steps 2 - 5) include vacuum bag and vacuum ring processes that utilize a vacuum to remove air.

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

[0066] The coefficient of friction (COF) was measured in accordance with ASTM D1894. The samples were measured in two directions. The COF was measured by testing the material against the material (the intermediate layer against the intermediate layer) and the intermediate layer against the metal sled as described in D1894. The samples were conditioned at 23 °C and 50% relative humidity for 40 hours prior to testing. The test speed used was 150 mm / min. For the COF test of the intermediate layer against the sled, the samples were cut to a width of 5 inches × a length of 10 inches, and for the COF test of the intermediate layer against the intermediate layer, the samples were cut to a width of 5 inches × a length of 10 inches, and the test was performed on a 2.5 inches × 2.5 inches intermediate layer on the sled.

[0067] The heat shrinkage rate was measured as follows: The intermediate layer sheet samples were cut from the roll immediately after extrusion. A template (10 cm in length in the machine direction) was used to mark individual samples, and then each individual sample was placed on a piece of cardboard. The samples on the cardboard were placed on a shelf in an oven (the temperature of which was preset to 54 °C). The samples were then removed from the oven after 10 minutes and placed on a workbench and allowed to cool to room temperature over a minimum of 5 minutes. The sample length in the machine direction was measured using a calibrated gauge before and after treatment in the 54 °C oven. The shrinkage rate was calculated as the percentage change in length in the machine direction relative to the original length before treatment in the oven.

[0068] The surface roughness (Rz and Rsm) was measured for the intermediate layer samples using a Mahr M1 500 Perthometer. Each sample was measured at three positions, and at each measurement position, the surface was traced three times in the machine direction and in the direction perpendicular to the machine direction. The reported surface Rz and Rsm values are the average values obtained from both directions on the top and bottom surfaces of the sheet from three positions.

[0069] The damping loss factor (η) was measured by mechanical impedance measurement (MIM) as described in ISO16940. In the case of the multilayer intermediate layer used in the following examples, the measurement of the damping loss factor (MIM) was performed on a small laminate sample or bar in the laboratory. The sample was 25 mm wide × 300 mm long (approx. 1 inch × 12 inches) and had a pair of 2.3 mm transparent glass substrates prepared by a standard lamination process. The sample was excited at the center point of the bar by a vibration shaker (Bruel and Kjaer). An impedance head (Bruel and Kjaer) was used to measure the force exciting the bar to vibrate and the velocity of the vibration, and the resulting transfer function was recorded in a National Instrument data acquisition and analysis system. The loss factor in the first vibration mode was calculated using the half-width method. The laminate was acclimated at room temperature for 3 months after lamination and acclimated at the test temperature (e.g., 20 °C) for at least 4 hours before the MIM test.

[0070] In an embodiment, the laminated window glass can be a window for a vehicle, such as side glass.

[0071] In an embodiment, the intermediate layer in the laminated window glass can include an intermediate layer in which 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 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. In an embodiment, at least one plasticizer can be a mixture of two or more plasticizers. In an embodiment, at least one plasticizer can be a high refractive index plasticizer as defined herein.

[0073] In an embodiment, the intermediate layer is colored (i.e., not transparent and has a lower visual transmittance, e.g., less than 75%), and is, for example, gray (light gray, dark gray, or any gray-based color). In other embodiments, the intermediate layer includes an IR absorber in at least one layer. In an embodiment, the intermediate layer can be colored and can include an IR absorber in at least one layer.

[0074] In an embodiment, the intermediate layer further includes at least one non-poly(vinyl acetal) layer. In an embodiment, the intermediate layer includes a bonding layer between the layers. In an embodiment, the intermediate layer includes a functional film, layer, or sheet. In an embodiment, the intermediate layer includes 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 intermediate layer has a damping loss factor (η) at 20 °C measured in accordance with 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 in this specification may be combined with any other feature. For example, a laminated glazing or a front glass may include an interlayer having a non-poly(vinyl acetal) layer and / or a functional film, layer or sheet, the interlayer may be colored, or the interlayer may include an IR absorber in at least one layer and may also be colored, or the interlayer may be such that the first poly(vinyl acetal) resin and the third poly(vinyl acetal) resin are the same and, at least, 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, having a first residual hydroxyl content and a second residual hydroxyl content. Other combinations of features are also included and contemplated.

Examples

[0077] Exemplary multilayer interlayers (DE-1 to DE-6) and a comparative interlayer (CE-1) were produced, as shown in Table 1, by mixing 100 parts of a poly(vinyl butyral) resin, various amounts of a plasticizer, and other common additives (as described above) and melt-extruding. In the examples of the present disclosure, a mixture of 3GEH and a DPG-dibenzoate plasticizer was used, and the amount (%) of 3GEH in the mixture is shown in Table 1. The comparative (control) example used only the 3GEH plasticizer. The core layer thickness of all samples (DE-1 to DE-6, and CE-1) is about 4.5 mils. The total thickness of each interlayer is shown in Table 1.

[0078] The four PVB resins used to make the layers included the following:

[0079] PVB1: A PVB resin having a residual PVOH content of about 23.8 weight percent.

[0080] PVB2: A PVB resin having a residual PVOH content of about 18.5 weight percent.

[0081] PVB3: A PVB resin having a residual PVOH content of about 9% by weight.

[0082] PVB4: A PVB resin having a residual PVOH content of about 10.5% by weight.

[0083] Next, the manufactured multilayer intermediate layer was tested and used to construct various laminates shown in the table and described in more detail below. Improvements in acoustic properties such as the damping loss factor (η), as well as improvements in COF and the heating shrinkage rate, can be most easily understood by comparing the intermediate layer with a laminate containing a multilayer (3-layer) intermediate layer. As shown and described below, these examples demonstrate that when specific changes are made to the multilayer intermediate layer, the intermediate layer of the present disclosure has an improved (lower) coefficient of friction and heating shrinkage properties, while also having excellent acoustic attenuation properties.

[0084] Table 1 shows the composition and MIM damping loss factor of the multilayer intermediate layer sheets of the present disclosure and the comparative ones.

Table 1

[0085] Tests on the COF of the multilayer intermediate layers (DE-1 to DE-6) of the present disclosure and the comparative multilayer intermediate layer (CE-1) shown in Table 1 were conducted in accordance with ASTM D1984 (described above) by testing both the intermediate layer against the intermediate layer and the intermediate layer against a metal trough. Both a groove pattern (non-random or regular embossed pattern) and a random rough pattern were tested for the intermediate layer of the present disclosure. Comparative intermediate layers having a groove pattern or a regular surface pattern were also tested. The results are shown in Table 2 below.

Table 2

[0086] As shown in Table 2, for the intermediate layers DE-1 to DE-6 of the present disclosure, the COF (both static and dynamic COF) is significantly lower than that of the comparative intermediate layer when tested against either the intermediate layer or the metal trough.

[0087] According to the above-mentioned heating shrinkage rate test method, two samples (DE-1 and CE-1) were also tested for the heating shrinkage rate. In addition, the samples were inspected for lamination processability to determine their ease of handling during processing. The processing involved handling the samples (intermediate layer blanks) cut from the roll using a suction cup, placing the intermediate layer blanks on a glass piece, and subsequently placing a second glass piece to form a preliminary laminate. The intermediate layer blanks were not relaxed and were used immediately after being cut from the roll. Then, the preliminary laminate was degassed and autoclaved, and the final laminate was evaluated to determine whether there was any shortage of the intermediate layer due to shrinkage. The results and discussions regarding processability and ease of handling are shown in Table 3 below.

Table 3

[0088] As shown in Table 3, the sample DE-1 of the present disclosure has significantly improved processability and less shrinkage compared to the comparative example CE-1, which had significantly higher COF and heating shrinkage rate. The examples of the present disclosure had no adhesiveness between the intermediate layer blanks when picked up with a suction cup after being placed as a stack of blanks (as described above), while approximately 20% of the comparative intermediate layer blanks had problems during handling and movement and adhered to each other (when being moved or lifted from the stack). For the comparative intermediate layer, there was also a problem that the length of the intermediate layer was insufficient (shortage of the intermediate layer) when the intermediate layer blanks were used immediately after being cut from the roll. On the other hand, the intermediate layer of the present disclosure had a much lower heating shrinkage rate value and did not exhibit the problem of intermediate layer shortage.

[0089] It has been found that a highly damping acoustic intermediate layer having a specific combination of additional features, for example, a higher glass transition temperature of the outer layer or skin layer combined with a lower heating shrinkage rate and a lower coefficient of static friction, has improved ease of handling and processability, enabling the use of an automated lamination process for making multi-layer panels.

[0090] In conclusion, the intermediate layer according to the present invention, as well as the laminated window glass including the multi-layer intermediate layer, such as side glass and front glass for automobiles, have better (lower) heating shrinkage rate values, reduced COF, and improved vibration damping properties compared to other multi-layer intermediate layers and laminated window glass including intermediate layers. Other advantages will be readily apparent to those skilled in the art.

[0091] Although the present invention has been disclosed in conjunction with descriptions of specific embodiments, including those currently considered to be the preferred embodiments, the detailed description is intended to be exemplary and should not be understood as limiting the scope of the present disclosure. As will be understood by those skilled in the art, embodiments other than those specifically described herein are encompassed by the present invention. The described embodiments can be variously modified and changed without departing from the spirit and scope of the present invention.

[0092] Furthermore, when compatible, any of the ranges, values or characteristics shown for any single component of the present disclosure can be used interchangeably with any of the ranges, values or characteristics shown for any other component of the present disclosure to form embodiments having the defined values for each of the components shown throughout this specification. For example, in addition to including a plasticizer in any given range, an intermediate layer including poly(vinyl butyral) having a residual hydroxyl content in any given range can be formed to form many permutations within the scope of the present disclosure, although it would be cumbersome to enumerate them. Furthermore, ranges provided for a genus or species, such as phthalate or benzoate, can also be applied to species within the genus, or members within the species, such as dioctyl terephthalate, unless otherwise noted.

Claims

1. A polymer intermediate layer comprising at least one layer, The aforementioned intermediate layer is The heat shrinkage rate is less than approximately 4.0%. The coefficient of static friction (COF) measured in accordance with ASTM D1894 in an arrangement where the intermediate layer is in contact with the intermediate layer is less than 1.

50. The laminated window glass including the aforementioned intermediate layer has a vibration damping loss coefficient (η) of at least 0.20 when measured at 20°C in accordance with ISO 16940. The aforementioned intermediate layer.

2. The intermediate layer according to claim 1, wherein the intermediate layer has a static friction coefficient (COF) of less than 2.00 when measured in accordance with ASTM D1894 in an arrangement in which the intermediate layer is in contact with a metal warp.

3. The intermediate layer according to claim 1, wherein the intermediate layer has a coefficient of dynamic friction (COF) of less than 0.50 when measured in accordance with ASTM D1894 in an arrangement where the intermediate layer is in contact with the intermediate layer.

4. The intermediate layer according to claim 1, wherein the intermediate layer has a coefficient of dynamic friction (COF) of less than 1.00 when measured in accordance with ASTM D1894 in an arrangement in which the intermediate layer is in contact with a metal warp.

5. The intermediate layer according to claim 1, wherein the intermediate layer is a multilayer intermediate layer.

6. The aforementioned intermediate layer is a multilayer intermediate layer, and the multilayer intermediate layer is 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 (Tg) above 37°C; A second layer comprising a second poly(vinyl acetal) resin having a second residual hydroxyl content and a second residual acetate content, and a second plasticizer, wherein the second layer has a glass transition temperature (Tg) of less than 20°C; and A third layer comprising a third poly(vinyl acetal) resin having a third residual hydroxyl content and a third residual acetate content, and a third plasticizer, wherein the third layer has a glass transition temperature (Tg) above 37°C. The intermediate layer according to claim 1, comprising the second layer and located between the first and third layers.

7. The intermediate layer according to claim 1, wherein the intermediate layer is colored and has a %T of less than about 75%.

8. The intermediate layer according to claim 7, wherein the intermediate layer is gray.

9. The intermediate layer according to claim 1, wherein the intermediate layer contains an IR absorbent.

10. The intermediate layer according to claim 1, further comprising a non-poly(vinyl acetal) layer.

11. The intermediate layer according to claim 1, wherein the intermediate layer further comprises a functional film, layer, or sheet.

12. The intermediate layer according to 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 intermediate layer according to 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 window glass comprising a first rigid substrate, an intermediate layer according to any one of claims 1 to 13, and a second rigid substrate, wherein the intermediate layer is located between the first rigid substrate and the second rigid substrate, and the laminated window glass is a side window, sunroof, or other window of a vehicle.

15. This is a process for making multilayer glass panels. A process of supplying a first rigid substrate to an integrated assembly fixing device, A step of supplying the polymer intermediate layer according to claim 1, A step of placing the intermediate layer blank on the first rigid substrate using a transport device, A process of supplying a second rigid substrate, and The process of placing the second rigid substrate on the intermediate layer blank to form a pre-assembly. The process including the process described above.

16. The process according to claim 15, further comprising the step of advancing the pre-assembly to a degassing process.

17. The process according to claim 16, wherein the degassing process includes a nip roll machine, a vacuum bag, or a vacuum ring.

18. The process according to claim 16, further comprising moving the pre-assembly to an autoclave to form a final multilayer panel.

19. The process according to claim 18, wherein the multilayer panel is a side window, sunroof or other window of a vehicle.

20. It is a multi-layer panel, First glass substrate; Polymer intermediate layer; and Second rigid circuit board The multilayer panel comprises the following: the intermediate layer has a heating shrinkage rate of less than approximately 4.0%, the coefficient of static friction (COF) measured in accordance with ASTM D1894 in an arrangement where the intermediate layer is in contact with the intermediate layer is less than 1.50, and the multilayer panel has a vibration damping loss coefficient (η) of at least 0.20 measured at 20°C in accordance with ISO 16940.