Multilayer interlayer with improved acoustic properties

Abstract

A multilayer interlayer film with improved acoustic properties is disclosed, which includes a hard skin layer(s) and a soft core layer comprising EVA. The multilayer interlayer film includes a first polymer layer (skin layer), a second polymer layer (skin layer), and a third polymer layer (core layer) between the first and second polymer layers, the third polymer layer comprising ethylene vinyl acetate resin.

Description

[Technical Field]

[0001]

[0001] This disclosure relates to the field of polymer interlayers for multilayer glass panels and multilayer glass panels having at least one polymer interlayer sheet. More specifically, this disclosure relates to the field of polymer interlayers comprising multiple thermoplastic layers having improved acoustic properties. [Background technology]

[0002]

[0002] A multi-layer panel is generally a panel consisting of two sheets of a substrate (for example, but not limited to, glass, polyester, polyacrylate, or polycarbonate) and one or more polymer interlayers sandwiched between them. Multi-layer glass panels are commonly used in architectural window applications, in automotive and aircraft windows, and in 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 energy from impacts or forces applied to the glass, to maintain the bonded layers of glass even when force is applied and the glass breaks, and to prevent the glass from breaking into sharp fragments. In addition, the interlayer can provide the glass with a higher sound insulation rating, reduce the transmission of UV and / or IR light, and enhance the aesthetic appeal of the associated window. With respect to solar cell applications, the main function of the interlayer is to enclose the photovoltaic panel used to generate and supply electricity in commercial and residential applications.

[0003]

[0003] To achieve certain properties and performance characteristics of glass panels, it has become common practice to utilize multilayer or multilayer interlayers. In this specification, the terms “multilayer” and “multilayer” mean interlayers having two or more layers, and multilayer and multilayer may be used interchangeably. Multilayer interlayers typically contain at least one soft layer and at least one hard layer. Interlayers having one soft “core” layer sandwiched between two more rigid or harder “skin” layers have been designed with sound insulation properties of glass panels in mind. Interlayers having the opposite configuration, i.e., one hard layer sandwiched between two softer layers, have been shown to improve the impact performance of glass panels and can also be designed with sound insulation in mind. Other examples of multilayer interlayers include those having at least one "transparent" or uncolored layer, 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., a layer having acoustic properties, or the ability to provide sound insulation or reduce sound transmission, as further defined below). Another example of a multilayer interlayer is one having at least two layers having various colors for aesthetic appeal. The colored layer typically contains a pigment or dye or some combination of pigments and dyes.

[0004]

[0004] Interlayers are generally produced by mixing a polymer resin, such as poly(vinyl butyral) or ethylene vinyl acetate copolymer, with one or more plasticizers of choice, and melting the mixture into a sheet by any applicable process or method known to those skilled in the art, for example, by extrusion molding, but not limited to these. Multilayer interlayers can be produced by processes such as co-extrusion molding or lamination, and the layers are combined together to form a single structure. Optionally, other additional components may be added for a variety of other purposes. After being formed, the interlayer sheets are typically assembled and rolled up for transport and storage and for later use in multilayer glass panels, as described below.

[0005]

[0005] A brief description follows of how a multilayer glass panel is generally manufactured in combination with an interlayer. 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 create an assembly. It is not uncommon to place multiple polymer interlayer sheets or polymer interlayer sheets with multiple layers (or a combination of both) within two substrates to create a multilayer glass panel with multiple polymer interlayers. Next, air is removed from the assembly by applicable processes or methods known to those skilled in the art, for example, via a nip roller, vacuum bag or other degassing mechanism. In addition, the interlayer is partially pressed onto the substrate by any method known to those skilled in the art. In the final step, to form a final integral structure, this pre-bonding is made more permanent by high-temperature, high-pressure lamination or any other method known to those skilled in the art, for example, by autoclave, but not limited to.

[0006]

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

[0007]

[0007] Acoustic quality or sound dampening quality is an important characteristic of laminated glass. At most frequencies, laminated glass exhibits better sound transmission loss than monolithic glass of the same surface density. At important frequencies (2000-20000 kHz) where the coincidence effect has the greatest impact on sound transmission, the presence of an embedded polymer interlayer leads to acoustic attenuation of the glass panel, significantly improving sound transmission loss. Acoustic interlayer products have been devised and improved, and currently, their acoustic performance is close to optimal for currently devised products. As vehicles become more sophisticated and more electronic devices are used, there is a need for improved acoustic attenuation, or reduction of sound, such as traffic noise entering vehicles. For buildings and structures, there is also a demand to reduce the amount of sound transmitted through windows and doors. Naturally, it is desirable to have even better acoustic performance.

[0008]

[0008] Therefore, in this field, there is a need to develop multilayer interlayers having desirable good optical, mechanical, and acoustic properties. More specifically, in this field, there is a need to develop multilayer interlayers having at least one soft core layer that have improved acoustic properties while maintaining other desirable physical and optical properties. [Overview of the project] [Means for solving the problem]

[0009]

[0009] Because of these and other problems in the art, multilayer interlayers comprising, in particular, multiple rigid skin layers and multiple flexible core layers are described herein. In one embodiment, these multilayer interlayers comprise a first polymer layer; a second polymer layer; and a third polymer layer comprising an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 70 weight percent, wherein the third polymer layer is located between the first polymer layer and the second polymer layer.

[0010]

[0010] In the embodiment, the multilayer interlayer comprises a first polymer layer comprising a poly(vinyl acetal) resin and a plasticizer; a second polymer layer comprising a poly(vinyl acetal) resin and a plasticizer; and a third polymer layer comprising an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 70 weight percent, wherein the third polymer layer is located between the first polymer layer and the second polymer layer.

[0011]

[0011] In one embodiment, the multilayer interlayer contains an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight.

[0012]

[0012] A multilayer panel is also disclosed. The multilayer panel comprises at least one rigid substrate and a polymer interlayer as disclosed herein. The panel has improved acoustic properties.

[0013]

[0013] A method for preparing a polymer interlayer is also disclosed, wherein the polymer interlayer is as disclosed herein.

[0014]

[0014] In a particular embodiment, the rigid substrate (or substrate) is glass. [Brief explanation of the drawing]

[0015] [Figure 1]

[0015] This graph shows the acoustic transmission loss of the interlayers disclosed in Example A and Example B compared to a standard reference acoustic PVB interlayer. [Figure 2]

[0016] This graph shows the acoustic transmission loss of the interlayer disclosed in Example 5 compared to two control acoustic PVB interlayers. [Figure 3]

[0017] This graph shows the acoustic transmission loss of the disclosed interlayers of Examples 7, 8, and 9 compared to two control acoustic PVB interlayers. [Figure 4]

[0018] Graph showing the acoustic transmission loss of the disclosed intermediate films of Example 10, Example 11, and Example 12 as compared to two control acoustic PVB intermediate films. [Figure 5]

[0019] Graph showing the acoustic transmission loss of the disclosed intermediate films of Example 13, Example 14, and Example 15 as compared to two control acoustic PVB intermediate films. [Figure 6]

[0020] Graph showing the loss tangent of two EVA core layers as compared to two different acoustic PVB intermediate films and HNBR. [Figure 7A]

[0021] Graph showing the shear modulus as a function of temperature for PVB formulations and EVA formulations for acoustic applications. [Figure 7B]

[0022] Graph showing the loss tangent as a function of temperature for PVB formulations and EVA formulations for acoustic applications.

Mode for Carrying Out the Invention

[0016]

[0023] In the present specification, there is described a multilayer intermediate film composed of, among other things, at least one soft core layer containing an ethylene vinyl acetate copolymer resin and optionally a plasticizer and at least one hard skin layer containing a resin and a plasticizer, and having improved acoustic properties. The intermediate film of the present disclosure has improved acoustic properties or sound insulation properties measured by acoustic transmission loss ("STL"). The intermediate film of the present invention has an improved acoustic transmission loss (STL) of at least about 40 decibels (dB) at 4000 Hertz (Hz) (measured by ASTM E90 (2009) at 20°C) and an attenuation loss coefficient of at least 0.2 (measured by ISO16940 at 20°C).

[0017]

[0024] The present invention discloses multilayer interlayers in which at least one layer comprises an ethylene vinyl acetate copolymer resin. These interlayers have good optical and physical properties while improving acoustic or sound insulation performance.

[0018]

[0025] In the embodiment, the interlayer has an STL of at least about 39 dB at 2000 Hz, or at least about 41 dB at 4000 Hz, or at least about 47.5 dB at 6350 Hz, or at least about 54 dB at 10000 Hz, measured at 20°C in a 2.3 mm / 2.3 mm glass configuration.

[0019]

[0026] In embodiments, the interlayer has an acoustic transmission loss (STL) of at least about 40 decibels, at least about 40.5 decibels, at least about 41 decibels, at least about 41.5 decibels, or at least about 42 decibels (dB) at 4000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)), and an attenuation loss coefficient of at least 0.2, at least 0.25, at least 0.3, at least 0.35, at least 0.4, at least 0.45, or at least about 0.5 (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ISO 16940).

[0020]

[0027] In embodiments, the multilayer interlayer has an acoustic transmission loss (STL) of at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, or at least about 41 dB at 2000 Hz (measured by ASTM E90 (2009) at 20°C with a 2.3 mm / 2.3 mm glass configuration).

[0021]

[0028] In the embodiment, the multilayer interlayer has an acoustic transmission loss (STL) of at least about 47.5 dB, at least about 48 dB, at least about 48.5 dB, at least about 49 dB, at least about 49.5 dB, or at least about 50 dB at 6350 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration according to ASTM E90 (2009)).

[0022]

[0029] In embodiments, the multilayer interlayer has an acoustic transmission loss (STL) of at least about 54 dB, at least about 54.5 dB, at least about 55 dB, at least about 55.5 dB, or at least about 56 dB at 10,000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration according to ASTM E90 (2009)).

[0023]

[0030] In one embodiment, the third polymer layer contains an adhesion modifier in an amount of at least 0.1 weight percent, at least 0.2 weight percent, at least 0.3 weight percent, at least 0.4 weight percent, at least 0.5 weight percent, at least 0.6 weight percent, at least 0.7 weight percent, at least 0.8 weight percent, at least 0.9 weight percent, at least 1.0 weight percent, at least 2.0 weight percent, at least 3.0 weight percent, at least 4.0 weight percent, at least 5.0 weight percent, at least 6.0 weight percent, at least 7.0 weight percent, at least 8.0 weight percent, at least 9.0 weight percent, or at least 10.0 weight percent.

[0024]

[0031]

[0032] Multilayer glass panels including interlayers are also described. The multilayer interlayers of the present invention can be used in double-glazed applications, such as windshields, side windows, sunroofs, and safety glass in roofs and building windows.

[0025]

[0033] In addition to the ethylene vinyl acetate ("EVA") copolymer resin layer, one (or more) layers of the multilayer polymer interlayer can be prepared by mixing one or more polymer resins, such as poly(vinyl acetal) resins (e.g., poly(vinyl butyral) ("PVB")), and one or more plasticizers. Multilayer interlayers generally contain two or more layers and two or more resins of various compositions. For example, poly(vinyl acetal) resins with various residual hydroxyl content and / or various residual acetate content, such as PVB resins, are suitable for at least one layer of the multilayer interlayer composition, while ethylene vinyl acetate copolymer resins are used for at least one other layer, for example, a softer layer, i.e., a core layer. In a multilayer containing two layers, at least one of the two layers is a soft layer and the other layer is a hard layer. In this specification, a "soft layer" or "softer layer" is a layer having a glass transition temperature of less than about 20°C. In this specification, “hard layer” or “harder layer” generally refers to a layer that is harder or more rigid than another layer and generally has a glass transition temperature at least 2 degrees (2°C) higher than another layer (e.g., a softer layer).

[0026]

[0034] In embodiments, the individual glass transition temperature (Tg) values ​​and the differences between the Tg values ​​of the layers vary depending on the thickness of the layer(s). For example, for a core layer containing the ethylene vinyl acetate copolymer described herein and having a thickness of about 5 mils, the layer can reach the desired or optimal STL level with a Tg of about 0°C. For a thicker core layer containing the ethylene vinyl acetate copolymer described herein and having a thickness of about 30 mils, the layer may have a Tg of about 17°C. Other layers and thicknesses may be selected according to desired properties and desired applications.

[0027]

[0035] A multilayer interlayer containing a layer of ethylene vinyl acetate copolymer resin is particularly useful for laminated glass panels and imparts certain properties and performance attributes not found in conventional sound-reducing poly(vinyl acetal) interlayers. The layer and multilayer interlayer of the present invention provide an interlayer with improved acoustic properties, such as sound insulation properties, compared to the acoustic properties of conventional multilayer interlayers containing poly(vinyl acetal) resin.

[0028]

[0036] Conventional multilayer interlayers, such as three-layer acoustic interlayers, consist of a flexible core layer composed of a single poly(vinyl butyral) ("PVB") resin with a low residual hydroxyl content and a high amount of conventional plasticizer, and two rigid skin layers with significantly higher residual hydroxyl content (see, for example, U.S. Patents 5,340,654, 5,190,826, and 7,510,771). The residual hydroxyl content and amount of plasticizer in the PVB core resin are optimized so that the interlayer provides optimal sound insulation properties under ambient conditions for double-glazed panels such as windshields and windows installed in vehicles and buildings.

[0029]

[0037] Here, multilayer acoustic interlayers, such as three-layer interlayers, can be designed and manufactured by selecting an ethylene vinyl acetate copolymer resin for use in the core layer. In these interlayers, a plasticizer equilibrium is maintained between the core layer(s) and the skin layer(s), and the core layer(s) and skin layer(s) can be combined by applicable methods such as co-extrusion or lamination to form the multilayer interlayer. The resulting multilayer acoustic interlayer provides excellent sound insulation without sacrificing other desirable and preferred characteristics of conventional multilayer interlayers, such as the optical properties and mechanical strength of glass panels made from the multilayer acoustic interlayer.

[0030]

[0038] This section explains some technical terms and common components found in both general interlayers and the interlayers of this disclosure, as well as in their formation. The terms “polymer interlayer sheet,” “interlayer,” and “polymer melt sheet” as used herein may generally specify a monolayer sheet or a multilayer interlayer. A “monolayer sheet,” as its name implies, is a single polymer layer extruded as a single layer. A multilayer interlayer, on the other hand, may include multiple layers, such as separately extruded layers, co-extruded layers, or any combination of separately extruded and co-extruded layers. Thus, a multilayer interlayer may include, for example: two or more monolayer sheets combined together ("multilayer sheet"); two or more layers co-extruded together ("co-extruded sheet"); two or more co-extruded sheets combined together; a combination of at least one monolayer sheet and at least one co-extruded sheet; a combination of a monolayer sheet and a multilayer sheet; and a combination of at least one multilayer sheet and at least one co-extruded sheet. In various embodiments of this disclosure, a multilayer interlayer comprises at least two polymer layers (e.g., single-layer or co-extruded multilayers and / or jointly laminated multilayers) arranged in direct contact with each other, each layer comprising a polymer resin as further detailed below. In this specification, for a multilayer interlayer having at least three layers, “skin layer” generally refers to the outer layer of the interlayer, and “core layer” generally refers to the inner layer(s). Thus, one exemplary embodiment is skin layer / / core layer / / skin layer. In a multilayer interlayer having a skin layer / / core layer / / skin layer configuration, in some embodiments the skin layer may be more rigid and the core layer may be more flexible, and in other embodiments the skin layer may be more flexible and the core layer may be more rigid.

[0031]

[0039] In this specification, "acoustic transmission loss" is determined according to the ASTM E90 (2009) method at a fixed temperature of 20°C for a laminate containing the interlayer of the present invention or the comparative interlayer. The multilayer interlayer of the present invention is laminated with 2.3 mm transparent glass. The panel has dimensions of 50 cm × 80 cm.

[0032]

[0040] In this specification, “sound transmission loss (STL) of the interlayer (measured by ASTM E90 (2009) at 20°C)” or “sound transmission loss (STL) of the interlayer” refers to the STL at a reference frequency for a particular glass configuration. In various embodiments, the interlayers of the present invention have improved sound transmission loss (STL).

[0033]

[0041] Glass transition temperature (T g ) can be determined by dynamic mechanical thermal analysis (DMTA) of the shear mode. DMTA measures the storage modulus (elastic) (G') (Pascals), loss modulus (viscous) (G'') (Pascals), and tan delta (=G'' / G') of the specimen 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 The value is determined by the position of the tan delta peak on a temperature scale (°C), and the tan delta peak value is referred to as tan delta or peak tan delta. In this specification, "tan delta," "peak tan delta," "tanδ," and "peak tanδ" can be used interchangeably.

[0034]

[0042] At least one layer, for example, a core layer, comprises, or may comprise, an ethylene vinyl acetate ("EVA") copolymer resin (sometimes referred to as poly(ethylene-co-vinyl acetate) resin). In such embodiments, this layer may also be referred to as the "EVA layer." EVA copolymer resins are commercially available from many suppliers, for example, from ARLANXEO Performance Elastomers as Levamelt® and Levapren®, and are available in various grades and vinyl acetate content.

[0035]

[0043] The EVA layer may contain a plasticizer. For example, the EVA layer may contain less than 30 phr, less than 25 phr, less than 20 phr, less than 15 phr, less than 10 phr, less than 5 phr, less than 2 phr, or less than 1 phr of added plasticizer. The plasticizer may be any plasticizer that is compatible with the EVA copolymer. Examples of suitable plasticizers are described below. In embodiments, the plasticizer used with EVA is the same plasticizer used in other layers, such as the PVB layer. In certain embodiments, the EVA layer does not contain any added plasticizer.

[0036]

[0044] Depending on the desired properties, EVA having various levels of vinyl acetate comonomer can be used. In a particular embodiment, depending on the desired application and desired properties, various amounts may be used, but the EVA contains a vinyl acetate content of at least 70 weight percent, at least 80 weight percent, or at least 90 weight percent, and / or 99 weight percent or less, 98 weight percent or less, or 95 weight percent or less.

[0037]

[0045] In various embodiments, EVA includes formulated EVA, which in some embodiments contains silane additives, peroxide additives, coactivators, UV blockers, and antioxidants. Alternatively, EVA may include "unformulated" EVA, which lacks one of the components listed above that are present in formulated EVA, such as peroxide additives (in which case the EVA is no longer thermally reactive). In various embodiments, EVA may be maleated. In some embodiments, the core layer may include a blend of one or more EVA resins.

[0038]

[0046] The EVA layer can be used in conjunction with other layers described herein to produce various types of multilayer interlayers, including other types of layers such as poly(vinyl acetal) layers, e.g., polyvinyl butyral ("PVB") layers. An example of a multilayer interlayer configuration is PVB / EVA / PVB (e.g., skin / core / skin).

[0039]

[0047] Multilayer interfilms containing an EVA layer and one or more additional layers can be manufactured using any method known in the art. For example, each layer may be formed separately using techniques known in the art and then laminated together. Alternatively, multilayer interfilms containing an EVA layer and one or more additional layers, such as PVB, can be manufactured by co-extrusion.

[0040]

[0048] Due to the crosslinking properties of EVA, it is generally desirable to avoid completely crosslinking the EVA when forming an EVA layer. Typically, partially crosslinked EVA can still be co-extruded with other polymers to form multilayer interlayers. Therefore, in some embodiments, it may be desirable to use an extrusion temperature that does not completely crosslink the EVA during extrusion. When amorphous EVA is completely crosslinked, its loss tangent in the glass transition region decreases, which leads to an adverse effect on or reduction of the STL value.

[0041]

[0049] In other embodiments, lightly crosslinked EVA without insoluble gel is desirable because it helps improve creep and iceflower resistance of the core layer. In embodiments, the EVA core layer may contain peroxides and co-activators to create a lightly crosslinked network structure. In embodiments, the EVA may be modified with peroxides and co-activators, which allows the chemical reaction to be completed in the extruder, thus eliminating the need to limit the extrusion temperature.

[0042]

[0050] In embodiments, an adhesion modifier can be used to increase the level of adhesion between the EVA layer and other polymer layers, such as a PVB layer. The adhesion modifier may be incorporated into the EVA or applied to the EVA layer. Examples of suitable adhesion modifiers include crotonic acid and peroxides, but other materials known to those skilled in the art may be used.

[0043]

[0051] In embodiments having layers (or more) of at least one poly(vinyl acetal) resin, the poly(vinyl acetal) resin is produced by known acetalization methods, which involve 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 methods are disclosed, for example, in U.S. Patent Nos. 2,282057 and 2,282026, and in Wade, B. 2016, Vinyl Acetal Polymers, Encyclopedia of Polymer Science and Technology, pp. 1-22 (online, copyright 2016 John Wiley & Sons, Inc.), the entirety of which is incorporated herein by reference. The resin is commercially available in various forms, for example, as Butvar® resin by Solutia Inc., a wholly owned subsidiary of Eastman Chemical.

[0044]

[0052] In this specification, the residual hydroxyl content of poly(vinyl acetal) resin (calculated as % by weight of vinyl alcohol or % by weight of PVOH) refers to the amount of hydroxyl groups remaining in the polymer chain after processing is complete. For example, PVB can be produced by hydrolyzing poly(vinyl acetate) to polyvinyl alcohol (PVOH), and then reacting the PVOH with butyraldehyde. In the hydrolysis of polyvinyl acetate, typically not all acetate side groups are converted to hydroxyl groups. Furthermore, the reaction with butyraldehyde typically does not convert all 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) are present as side groups in the polymer chain. In this specification, the residual acetate content (calculated as % vinyl acetate content in poly(vinyl acetal) or % by weight of poly(vinyl acetate) (PVAc)) refers to the amount of residual groups remaining in the polymer chain. In this specification, the residual hydroxyl content and residual acetate content are measured in weight percent (wt.%) according to ASTM D1396.

[0045]

[0053] According to the present invention, the multilayer interlayer comprises at least a first layer containing an ethylene vinyl acetate copolymer resin and a second layer containing a poly(vinyl acetal) resin. In various embodiments, the first layer may be a soft layer and the second layer may be a hard layer. In embodiments, when the multilayer interlayer of the present invention consists of three layers, the core layer is a soft layer and the skin layer is a hard layer.

[0046]

[0054] In various embodiments, when the interlayer is a multilayer interlayer such as a three-layer interlayer, the soft (or core) layer comprises the above-mentioned EVA copolymer resin, and the harder (or skin) outer layer comprises a poly(vinyl acetal) resin. In embodiments, the poly(vinyl acetal) resin has a residual hydroxyl content calculated as PVOH%, which is at least about 10 to about 35 wt.%, about 15 to about 30 wt.%, or about 17 to about 22 wt.% of residual hydroxyl groups. In embodiments, the poly(vinyl acetal) resin has a residual hydroxyl content calculated as PVOH%, of at least about 10 wt.%, at least about 12 wt.%, at least about 14 wt.%, at least about 15 wt.%, at least about 16 wt.%, at least about 17 wt.%, at least about 18 wt.%, at least about 19 wt.%, at least about 20 wt.%, at least about 21 wt.%, or at least about 22 wt.%, and residual hydroxyl groups of less than about 35 wt.%, less than about 30 wt.%, less than about 25 wt.%, less than about 23 wt.%, less than about 232 wt.%, less than about 21 wt.%, less than about 20 wt.%, or less than 19 wt.%.

[0047]

[0055] In embodiments, the skin layer may include a blend of two or more poly(vinyl acetal) resins having varying residual hydroxyl content. This difference between poly(vinyl acetal) resins is calculated by subtracting the residual hydroxyl content of the resin having the higher residual hydroxyl content from the residual hydroxyl content of the resin having the lower residual hydroxyl content. In this specification, the terms “weight percentage difference” or “the difference is at least ……… weight percent” refer to the difference between two given weight percent, 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 less than 2 weight percent 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). In this specification, the term “various” can refer to a value higher or lower than another value. One or more other poly(vinyl acetal) layers may be present in the interlayer and may have residual hydroxyls within the range indicated above.

[0048]

[0056] In various embodiments, the poly(vinyl acetal) resin may contain less than 30 wt.% of residual acetate groups, less than 25 wt.% of 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.%, of residual acetate groups calculated as poly(vinyl acetate), with the remainder being acetal, such as butyraldehyde (which includes isobutyraldehyde acetal groups), but optionally, as described above, another acetal group, such as 2-ethylhexanal acetal groups, or a mixture of butyraldehyde acetal groups and 2-ethylhexanal acetal groups.

[0049]

[0057] In some embodiments, when two or more poly(vinyl acetal) resins are present in a layer, the poly(vinyl acetal) resins can have various residual acetate content. For example, in some embodiments, the difference between the residual acetate content of the first poly(vinyl acetal) resin and the residual acetate content of the second poly(vinyl acetal) resin can be at least about 2 weight percent, at least about 3 weight percent, at least about 4 weight percent, at least about 5 weight percent, at least about 6 weight percent, at least about 7 weight percent, at least about 8 weight percent, at least about 9 weight percent, at least about 10 weight percent, at least about 12 weight percent, at least about 14 weight percent, at least about 16 weight percent, at least about 18 weight percent, at least about 20 weight percent, at least about 24 weight percent, or at least 29 weight percent. The poly(vinyl acetal) resins can have a residual acetate content of about 4 weight percent or less, about 3 weight percent or less, about 2 weight percent or less, or about 1 weight percent or less, as measured as described above. In some embodiments, the poly(vinyl acetal) resin may have a residual acetate content of at least 4 weight percent, at least about 5 weight percent, at least about 6 weight percent, at least about 7 weight percent, about 8 weight percent, at least about 10 weight percent, at least about 12 weight percent, at least about 14 weight percent, at least about 16 weight percent, at least about 18 weight percent, at least about 20 weight percent, at least about 25 weight percent, or at least about 30 weight percent.

[0050]

[0058] The poly(vinyl acetal) resins of this disclosure, for example, one or more poly(vinyl butyral) (PVB) resins typically have a molecular weight greater than 50,000 daltons, less than 500,000 daltons, or about 50,000 to about 500,000 daltons, or about 70,000 to about 500,000 daltons, or about 100,000 to about 425,000 daltons, as measured by size exclusion chromatography using a low-angle laser light scattering detector, differential refractometer, or UV detector. In this specification, the term "molecular weight" means weight-average molecular weight.

[0051]

[0059] To control the adhesion of the interlayer sheet to the glass, various adhesion control agents ("ACAs") can be used in the interlayers of this disclosure. In various embodiments of the interlayers of this disclosure, the interlayer may contain about 0.003 to about 0.15 parts by weight of ACA per 100 parts by weight of resin; about 0.01 to about 0.10 parts by weight of ACA per 100 parts by weight of resin; and about 0.01 to about 0.04 parts by weight of ACA per 100 parts by weight of resin. Such ACAs include, but are not limited to, ACA 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-ethyl butyrate), and / or magnesium bis(2-ethylhexanoate).

[0052]

[0060] Other additives can be incorporated into the interlayer to enhance its performance in the final product and impart certain additional properties to the interlayer. Such additives include, but are not limited to, a number of additives known to those skilled in the art, such as dyes, pigments, stabilizers (e.g., UV stabilizers), antioxidants, antiblocking agents, flame retardants, IR absorbers or IR 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, thermal stabilizers, UV absorbers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, enhancing additives, and fillers.

[0053]

[0061] One or more layers may also contain at least one type of plasticizer. Depending on the specific composition of the layer(s), the amount of plasticizer per 100 parts by weight of resin may be at least about 0.5 parts by weight, at least about 1 part by weight, at least about 2 parts by weight, at least about 3 parts by weight, at least about 4 parts by weight, at least about 5 parts by weight, at least about 10 parts by weight, at least about 15 parts by weight, at least about 20 parts by weight, at least about 25 parts by weight, at least about 30 parts by weight, at least about 35 parts by weight, at least about 40 parts by weight, at least about 45 parts by weight, at least about 50 parts by weight, at least about 55 parts by weight, and at least about 6 parts by weight. It may be present in amounts of 0 parts by weight (phr), and / or about 120 phr or less, about 110 phr or less, about 105 phr or less, about 100 phr or less, about 95 phr or less, about 90 phr or less, about 85 phr or less, about 75 phr or less, about 70 phr or less, about 65 phr or less, about 60 phr or less, about 55 phr or less, about 50 phr or less, about 45 phr or less, or about 40 phr or less, or in the range of about 5 to about 120 phr, about 10 to about 110 phr, about 20 to about 90 phr, or about 25 to about 75 phr.

[0054]

[0062] In this specification, the terms “parts by weight per 100 parts by weight of resin” or “phr” refer to the amount of plasticizer present in comparison to 100 parts by weight of resin, on a weight basis. For example, if 30 grams of plasticizer are added to 100 grams of resin, the amount of plasticizer present will be 30 phr. If the layer contains two or more types of resin, the weight of the plasticizer is determined in terms of parts by weight per 100 parts by weight of resin by comparing it to the total amount of all resins present. Furthermore, where the plasticizer content of a layer is provided in this specification, it is provided by reference to the amount of plasticizer in the mixture or melt used to manufacture the layer.

[0055]

[0063] Examples of suitable plasticizers include, but are not limited to, conventional plasticizers such as triethylene glycol di-(2-ethylhexanoate) ("3GEH"), triethylene glycol di-(2-ethyl butyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, tetraethylene glycol di-(2-ethylhexanoate) ("4GEH"), dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, di(butoxyethyl) adipate, and bis(2-(2-butoxyethoxy)ethyl) adipate, dibutyl sebacate, dioctyl sebacate, and mixtures thereof. The plasticizer can be selected from the group consisting of triethylene glycol di-(2-ethylhexanoate) and tetraethylene glycol di-(2-ethylhexanoate), or the plasticizer may contain triethylene glycol di-(2-ethylhexanoate). In this specification, plasticizers having a refractive index of approximately 1.450 or less are referred to as “conventional plasticizers.” These plasticizers have a refractive index of approximately 1.442 to 1.449. In comparison, PVB resins have a refractive index of approximately 1.485 to 1.495. In interlayers produced for diverse properties and applications, 3GEH (refractive index = 1.442) is one of the most common plasticizers available. Other plasticizers, including those not listed herein, may also be used.

[0056]

[0064] In some embodiments, the plasticizer contained in one or more layers may be a high-RI plasticizer. In this specification, the term “high-RI plasticizer” means a plasticizer having a refractive index of at least 1.460 as measured by ASTM D542 at a wavelength of 589 nm and a temperature of 25°C. When used, high-RI plasticizers may have refractive indices of at least about 1.470, at least about 1.480, at least about 1.490, at least about 1.500, at least about 1.510, at least about 1.520, and / or about 1.600 or less, about 1.575 or less, or about 1.550 or less as measured as described above.

[0057]

[0065] Examples of types or classifications of high-RI plasticizers include, but are not limited to, polyadipates (RI approximately 1.460 to 1.485); epoxides, such as epoxidized soybean oil (RI approximately 1.460 to 1.480); phthalates and terephthalates (RI approximately 1.480 to 1.540); benzoates and toluates (RI approximately 1.480 to 1.550); and other special plasticizers (RI approximately 1.490 to 1.520). Detailed examples of suitable RI plasticizers include, but are not limited to, dipropylene glycol dibenzoate, tripylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, butoxyethyl benzoate, butoxyethoxyethyl benzoate, butoxyethoxyethoxyethyl benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, and 2,2,4-trimethyl Examples include 1,3-pentanediol benzoate isobutyrate, 1,3-butanediol dibenzoate, diethylene glycol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bis-phenol A bis(2-ethylhexanate), di-(butoxyethyl) terephthalate, di-(butoxyethyl) terephthalate, and mixtures thereof. High RI plasticizers may be selected from dipropylene glycol dibenzoate and tripropylene glycol dibenzoate, and / or 2,2,4-trimethyl-1,3-pentanediol dibenzoate.

[0058]

[0066] When the resin layer or interlayer contains a high RI plasticizer, the plasticizer may exist alone in the layer or may be blended with one or more additional plasticizers. The other one or more plasticizers may also contain a high RI plasticizer, or one or more may be lower RI plasticizers having a refractive index of less than 1.460. In some embodiments, the lower RI plasticizers may have refractive indices of less than about 1.450, less than about 1.445, or less than about 1.442, and may be selected from the group enumerated above. When a mixture of two or more plasticizers is used, the mixture may have a refractive index of one or more of the above ranges.

[0059]

[0067] In some embodiments, the interlayer may include at least a first resin layer comprising a first resin and a first plasticizer, and a second resin layer comprising a second resin and a second plasticizer. The first and second plasticizers may be the same type of plasticizer, or they may be different. In some embodiments, at least one of the first and second plasticizers may also be a blend of two or more plasticizers, which may be the same as or different from one or more other plasticizers.

[0060]

[0068] In various embodiments, the high refractive index plasticizer(s) are selected such that, for both the core layer and / or skin layer, the refractive index of the plasticizer is at least about 1.460, or higher than about 1.460, or higher than about 1.470, or higher than about 1.480, or higher than about 1.490, or higher than about 1.500, or higher than 1.510, or higher than 1.520. In this specification, “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) are used in conjunction with a conventional plasticizer, 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. In this specification, the refractive index of plasticizers or resins used throughout this disclosure is measured according to ASTM D542 at a wavelength of 589 nm and 25°C, or as reported in literature in accordance with ASTM D542.

[0061]

[0069] Examples of plasticizers with high refractive indices that may be used include, but are not limited to, polyadipates (RI approximately 1.460 to 1.485); epoxides (RI approximately 1.460 to 1.480); phthalates and terephthalates (RI approximately 1.480 to 1.540); benzoates (RI approximately 1.480 to 1.550); and other special plasticizers (RI approximately 1.490 to 1.520). Detailed 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-butanediol dibenzoate, and diethylene glycol dibenzoate. Examples include chol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, bis-phenol A bis(2-ethylhexanate), ethoxylated nonylphenol, nonylphenyltetraethylene glycol, dioctyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, mixtures of benzoic acid esters of dipropylene glycol and diethylene glycol, and mixtures thereof.

[0062]

[0070] The total plasticizer content in the interlayer may be in the range of 0 to 120 phr, or higher than 0 phr, or higher than 5 phr, or higher than 10 phr, or higher than 15 phr, or higher than 20 phr, or higher than 25 phr, or higher 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, the interlayer or any layer of the interlayer contains total plasticizer in amounts greater than 1 phr, greater than 2 phr, greater than 3 phr, greater than 4 phr, greater 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. While the total plasticizer content is shown above, the plasticizer content of the skin layer(s) or core layer(s) may differ from the total plasticizer content. In addition, as disclosed in U.S. Patent No. 7,510,771 (the whole disclosure of which is incorporated herein by reference), the plasticizer content of each layer in equilibrium is determined by the residual hydroxyl content of each layer, so that the skin layer(s) and core layer(s) can have various types of plasticizers and various plasticizer content within the aforementioned range. For example, if the combined thickness of the skin layer is equal to the thickness of the core layer, and the total plasticizer content of the interlayer is approximately 45.4 phr, then in equilibrium, the interlayer may include two skin layers each containing 30 phr of plasticizer and a core layer each containing 65 phr of plasticizer. For thicker or thinner skin layers, the total plasticizer content of the interlayer will vary accordingly. Where a plasticizer content of an interlayer is given herein, the plasticizer content is determined by reference to the phr of the plasticizer in the mixture or melt used to produce the interlayer.

[0063]

[0071] The amount of plasticizer in the interlayer can be adjusted to affect the glass transition temperature (T g ) of the interlayer and the final acoustic performance. The glass transition temperature (T g ) is the temperature that indicates the transition of the interlayer from a glassy state to a rubbery state. Generally, a higher amount of plasticizer filling will result in a lower T g . Layers or interlayers containing conventional poly(vinyl acetal) resins that have been used previously generally have a T g in the range of about -10 to 25 °C for acoustic (noise reduction) interlayers, and a T g of up to about 45 °C for (more rigid or structural) interlayer applications for hurricanes and aircraft. For layers containing EVA, the T g may desirably be in other ranges depending on the application, but may also be in a similar range, for example, in the range of about -10 to 20 °C for acoustic (noise reduction) interlayers.

[0064]

[0072] The glass transition temperature (T g ) of the interlayer is also related to the rigidity of the interlayer. Generally, the higher the glass transition temperature, the harder the interlayer. Generally, interlayers having a glass transition temperature of 30 °C or higher increase the windshield mechanical strength and torsional rigidity. On the other hand, soft interlayers (generally characterized by interlayers having a glass transition temperature of less than 20 °C) contribute to the sound attenuation effect (i.e., acoustic properties). The interlayers of the present disclosure can have a glass transition temperature of about 26 °C or higher, or about 35 °C or higher, for the harder layer(s), and a glass transition temperature of 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 the soft layer(s).

[0065]

[0073] In some embodiments, the multilayer interlayers of the present disclosure combine these advantageous strength and acoustic properties by utilizing a harder or more rigid skin layer (e.g., rigid / / flexible / / rigid) laminated with a softer core layer, including EVA. In various embodiments, the multilayer interlayers generally include a rigid layer(s) containing poly(vinyl acetal) resin(s)

[0066]

[0074] The final interlayer, formed by extrusion or co-extrusion or by lamination of multiple layers, generally has a random rough surface topography because it is formed by melt fractures of the polymer melt as it exits the extrusion die, and furthermore, the random rough surface on one or both sides (e.g., the skin layer) can be embossed by any embossing method known to those skilled in the art.

[0067]

[0075] All methods for producing polymer interlayer sheets known to those skilled in the art are considered as possible methods for producing the polymer interlayer sheets described herein, but this application focuses on polymer interlayer sheets produced by extrusion and co-extrusion methods. The final multilayer glass panel laminate of the present invention is formed using lamination methods known in the art.

[0068]

[0076] Generally, the thickness or gauge of polymer interlayer sheets ranges from about 15 mil to 100 mil (about 0.38 mm to about 2.54 mm), about 15 mil to 60 mil (about 0.38 mm to about 1.52 mm), about 20 mil to about 50 mil (about 0.51 mm to 1.27 mm), and about 15 mil to about 35 mil (about 0.38 mm 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 mil (about 0.025 mm to 2.51 mm), about 1 mil to 59 mil (about 0.025 mm to 1.50 mm), 1 mil to about 29 mil (about 0.025 mm to 0.74 mm), or about 2 mil to about 28 mil (about 0.05 mm to 0.71 mm).

[0069]

[0077] Many of the embodiments described below refer to polymer resins for the outer layer (or more) which is PVB and the core layer which is EVA, but it will be understood by those skilled 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) (e.g., poly(vinyl butyral) (PVB) or poly(vinyl isobutyral), isomers of poly(vinyl butyral) (also known as PVisoB), aliphatic polyurethane (PU), polyvinyl chloride (PVC), poly(vinyl chloride-co-methacrylate), polyethylene, polyolefin, ethylene acrylate ester copolymer, poly(ethylene-co-butyl acrylate), silicone elastomers, epoxy resins, and acid copolymers, such as ethylene / carboxylic acid copolymers, and ionomers derived from any of the aforementioned possible thermoplastic resins, as well as combinations thereof. PVB and its isomers polyvinyl isobutyral, polyvinyl chloride, ionomers, and polyurethanes are generally suitable polymers for the outer layer(s) of multilayer interlayers, with PVB (including its isomer PVisoB) being particularly preferred.

[0070]

[0078] Although commonly referred to as poly(vinyl acetal) or poly(vinyl butyral), any poly(vinyl acetal) resin may contain any suitable aldehyde residue, such as isobutyraldehyde, as described above. In some embodiments, one or more poly(vinyl acetal) resins may contain at least one C1-C 10 It may contain an aldehyde or at least one C4-C8 aldehyde residue. Suitable examples of C4-C8 aldehydes include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylbarrelaldehyde, n-hexylaldehyde, 2-ethylhexylaldehyde, n-octylaldehyde, and combinations thereof. At least one of the first poly(vinyl acetal) resin and the second poly(vinyl acetal) resin may contain at least one C4-C8 aldehyde residue in an amount of at least about 20 weight percent, at least about 30 weight percent, at least about 40 weight percent, at least about 50 weight percent, at least about 60 weight percent, or at least about 70 weight percent, and / or may contain at least one C4-C8 aldehyde in an amount of about 90 weight percent or less, about 85 weight percent or less, about 80 weight percent or less, about 75 weight percent or less, about 70 weight percent or less, or about 65 weight percent or less, or may contain at least one C4-C8 aldehyde in an amount of about 20 to about 90 weight percent, about 30 to about 80 weight percent, or about 40 to about 70 weight percent. C4-C8 aldehydes may be selected from the group listed above, or from the group consisting of n-butyraldehyde, isobutyraldehyde, 2-ethylhexylaldehyde, and combinations thereof.

[0071]

[0079] In various embodiments, one or more poly(vinyl acetal) resins may be poly(vinyl butyral) (PVB) resins. In other embodiments, one or more poly(vinyl acetal) resins may be poly(vinyl butyral) resins mainly containing n-butyraldehyde residues, for example, the resin may contain aldehyde residues other than butyraldehyde in amounts of about 50% by weight or less, about 40% by weight or less, about 30% by weight or less, about 20% by weight or less, about 10% by weight or less, about 5% by weight or less, or about 2% by weight or less, relative to the total weight of all aldehyde residues in the resin.

[0072]

[0080] In this specification, a multilayer panel may include a single substrate, such as glass, acrylic, or polycarbonate, along with a polymer interlayer sheet placed thereon, and most commonly, a polymer film further placed across the polymer interlayer. The combination of the polymer interlayer sheet and the polymer film is generally referred to in the art as a two-layer. A typical multilayer panel having a two-layer structure is (glass) / / (polymer interlayer sheet) / / (polymer film), where the polymer interlayer sheet can contain a number of interlayers as described above. The polymer film provides a smooth, thin, rigid substrate that gives better optical properties than the polymer interlayer sheet alone would normally obtain, and functions as an improved layer. The polymer film differs from the polymer interlayer sheets used herein in that it does not itself provide the necessary penetration resistance and glass retention properties, but rather provides improved performance, such as infrared absorption properties. Poly(ethylene terephthalate) ("PET") is the most commonly used polymer film. Generally, in this specification, polymer films are thinner than polymer sheets, for example, with a thickness of about 0.001 to 0.2 mm.

[0073]

[0081] The interlayers of this disclosure are most commonly used in multilayer panels comprising two substrates, for example, a pair of glass sheets (or other rigid materials known in the art, such as polycarbonate or acrylic), and an interlayer disposed between the two substrates. An example of such a structure is (glass) / / (polymer interlayer sheet) / / (glass), where, as described above, the polymer interlayer sheet may comprise the multilayer interlayer, and the core layer of the multilayer interlayer may comprise a single resin, or a resin with excellent transparency or high T vis The first resin and the second resin having a higher residual hydroxyl content, as well as at least one high refractive index plasticizer, may be included to produce a transparent multilayer panel having % or minimal haze. These examples of multilayer panels are by no means limiting and are intended to make it readily apparent to those skilled in the art that numerous structures other than those described above can be fabricated with the interlayers of this disclosure.

[0074]

[0082] A typical glass lamination process includes the following steps: (1) assembling two substrates (e.g., glass) and an interlayer; (2) briefly heating the assembly by IR radiation or convection; (3) passing the assembly through a pressurized nip roll for a first degassing; (4) heating the assembly a second time (e.g., about 60°C to about 120°C) to give the assembly sufficient temporary adhesion to seal the edges of the interlayer; (5) passing the assembly through a second pressurized nip roll to further seal the edges of the interlayer and allow for further handling; and (6) autoclaving the assembly for a suitable time, e.g., about 30 to 90 minutes, at a suitable temperature and pressure, e.g., 135°C to 150°C and a pressure of 180 psig to 200 psig. Actual steps, times, and temperatures can be varied as needed, as is known to those skilled in the art.

[0075]

[0083] Other methods (steps 2-5) used in the degassing of interlayer-glass interfaces that are known and commercially practiced in this field include the vacuum bag method and the vacuum ring method, which utilize vacuum to remove air.

[0076]

[0084] Glass transition temperature (T g The values ​​were determined by dynamic mechanical thermal analysis (DMTA). DMTA measures the storage modulus (elastic) (G') (Pascals), loss modulus (viscosity) (G'') (Pascals), and tan delta (=G'' / G') of the specimen as a function of temperature at a given oscillation frequency and temperature sweep rate. In this specification, DMTA with an oscillation frequency of 1 Hz was used with shear mode and temperature sweep rate of 3°C / min. g We measured T. g This is determined by the position of the tan delta peak on the temperature scale (°C).

[0077]

[0085] The sound transmission loss (STL) is determined for a laminate of the present invention of fixed dimensions according to ASTM E90 (2009) at a fixed temperature of 20°C. The multilayer interlayer of the present invention is laminated with 2.3 mm transparent glass according to the above method for producing a laminated glass panel (having a configuration of 2.3 mm glass / / interlayer / / 2.3 mm glass). The panel has dimensions of 50 cm × 80 cm. In various embodiments, the STL of a glass panel containing the multilayer interlayer of the present invention is at least about 39 dB at 2000 Hz, or at least about 41 dB at 4000 Hz, or at least about 47.5 dB at 6350 Hz, or at least about 54 dB at 10000 Hz.

[0078]

[0086] Haze can be measured at an observation angle of 2 degrees using a haze meter or spectrophotometer, e.g., a HunterLab UltraScan XE instrument, or other haze meters known to those skilled in the art, according to ASTM D1003-Procedure B with light source C. The transmission percentage (T%) or transparency is the percentage of total incident light transmitted through the specimen and is also determined according to ASTM D1003. In various embodiments of this disclosure, the haze is less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, and less than 0.5%.

[0079]

[0087] HLD haze is measured by an HLD haze measuring device consisting of a tungsten halogen light source, a sample holder, and a goniometer with an attached photodetector. The HLD haze measuring device is calibrated using a set of HLD standard laminates with a total thickness of 8.3 mm (5 layers of 0.76 mm interlayers) between two 2.3 mm transparent glass sheets, representing HLD haze grades 0, 1, 2, etc., where a higher value indicates increased HLD haze. In this measurement, the laminate was made of transparent glass with a thickness of approximately 2.3 mm by a standard autoclave lamination method. After autoclaving, the laminate was left at room temperature overnight. Scattered light intensity at a scattering angle of 45° was collected from the test laminate sample at room temperature using the HLD haze measuring device, and the HLD haze was calculated using computer software and reported at the nominal total laminate thickness.

[0080]

[0088] In some embodiments, the resin blends, layers, and interlayers described herein may have HLD values ​​of less than 1, less than about 0.9, less than about 0.8, less than about 0.7, less than about 0.6, or less than about 0.5.

[0081]

[0089] Pammel adhesion is another parameter that may be used to describe the interlayers disclosed herein. The Pammel adhesion test measures the level of adhesion of glass to the interlayer in a laminated structure. The adhesion of the interlayer to the glass has a significant impact on the impact resistance and long-term stability of the glass-interlayer structure. In this test, the laminate is cooled to 0°F (-18°C) or conditioned at room temperature 70°F (21°C) and manually struck against a steel plate at a 45° angle using a 1 lb. (0.45 kg) hammer. The sample is then returned to room temperature and all broken glass that has detached (unadhere) from the interlayer is removed. The amount of glass remaining adhered to the interlayer is visually compared to a set of standards. The standards correspond to various scales of the amount of glass remaining adhered to the interlayer. For example, a Pammel standard of zero means that essentially no glass remains adhered to the interlayer. On the other hand, a Pammel standard of 10 means that essentially 100 percent of the glass remains adhered to the interlayer. The Pammel values ​​are classified and averaged for similar test specimens. The reported values ​​represent the average Pammel values ​​for the group and maximum range of Pammel adhesion evaluated for individual surfaces. The interlayers described herein may have Pammel adhesion ratings of 2 or more, 9 or less, or about 2 to about 9.

[0082]

[0090] The mean break height values ​​expressed herein are obtained using interlayers of known thickness (as indicated), e.g., 30 mil, 45 mil, or other thicknesses, laminated between two 2.3 mm thick glass sheets. The specification of these parameter values ​​is by no means limiting to the interlayer thicknesses described herein or the configuration of multilayer panels according to embodiments of the present invention. Rather, the specification of these parameter values ​​is intended to provide a reliable test for determining the impact resistance, measured as mean break height, indicated by the interlayer, and the test is measured at known thicknesses and, if necessary, normalized to a constant thickness (e.g., 30 mil or 45 mil) so that various interlayers can be compared at the same interlayer thickness.

[0083]

[0091] Using the interlayer of the present invention, it is possible to form a panel that exhibits an average fracture height similar to that of a comparative interlayer. [Examples]

[0084]

[0092] The improvement in acoustic properties can be most easily recognized by comparing multilayer (three-layer) interlayers with a core layer containing EVA with multilayer interlayers with a core layer containing PVB, as shown in Figures 1-4. As shown in the figures and described below, these examples demonstrate that when EVA is used in the core layer, acoustic properties can be improved compared to conventional interlayers. For example, when EVA is used in the core layer, in some cases, there is an improvement of up to 3 dB above 4000 Hz without adversely affecting the STL at lower frequencies. In some cases, this improvement is at least a 4 dB increase at high frequencies (>4000 Hz), with only a slight trade-off or slight decrease in the 2000-3000 Hz range. Other properties, such as haze and shock, can be maintained.

[0085] Example 1

[0093] Exemplary multilayer interlayers were fabricated. As shown in Table 1, for the PVB layer (outer skin layer), 100 parts by weight of PVB resin having a residual hydroxyl content of approximately 18.7 wt.% was mixed with a plasticizer (and general additives), and for the EVA layer, 100 parts by weight of EVA resin having a vinyl acetate content of 80 wt.% was mixed with a plasticizer (and general additives). The PVB layer and the EVA layer were co-extruded to form a multilayer interlayer.

[0086]

[0094] Figure 1 is a graph showing the acoustic transmission loss of the interlayers disclosed in Table 1 compared to a standard control acoustic PVB interlayer (Saflex® Q series PVB). As shown in Figure 1, the interlayer with an EVA core has a higher acoustic transmission loss value at frequencies above approximately 4000 Hz, i.e., an increase of at least 2 dB above the 4000 Hz range and only a small decrease of about 1 dB in the 2000 Hz to 3000 Hz range.

[0087] [Table 1]

[0088]

[0095] Further skin and core layers were fabricated. The skin layer was fabricated using 100 parts by weight of PVB resin with a residual hydroxyl content of approximately 18.7 wt.% and the amount of plasticizer shown in Table 2. The core layer was fabricated using EVA resin with a vinyl acetate content of 80 wt.% at various skin thicknesses, as shown in Table 2. No plasticizer was used in the EVA layer. The skin and core layers were combined (compressed) to create a three-layer interlayer with a PVB skin layer as the outer layer and an EVA layer as the interlayer or core layer. The fabricated interlayers are shown in Table 2. Table 3 shows the expected levels of plasticizer in the skin and core layers, as well as the expected Tg of the core layer, based on the plasticizer distribution ratio established by measuring the plasticizer levels of each of the compressed multilayer interlayers until no further changes were observed. The measured core layer plasticizer levels and measured Tg values ​​were measured in several samples and are shown in Table 3 below.

[0089] [Table 2]

[0090] [Table 3]

[0091]

[0096] Tables 2 and 3 show that the interlayers can be fabricated using an EVA-containing core layer having a desired low glass transition temperature. Some of these interlayers were then tested for their physical and optical properties.

[0092]

[0097] Figure 2 is a graph showing the acoustic transmission loss of the disclosed interlayer in Example 5 compared to two control acoustic PVB interlayers (Saflex® Q-series PVB interlayers). Figure 2 shows that the STL at the mid-frequency can be improved by using a specific amount of plasticizer and targeting a specific core Tg level. In other words, the STL trade-off between the mid-frequency and high-frequency can be manipulated and controlled depending on the desired level and requirements at a particular frequency and application.

[0093]

[0098] Figure 3 is a graph showing the acoustic transmission loss of the disclosed interlayers of Examples 7, 8, and 9 compared to the same two control acoustic PVB interlayers (Saflex® Q-series PVB interlayers). Figure 3 demonstrates that it is possible to adjust the STL improvement over various frequency ranges.

[0094]

[0099] Figure 4 is a graph showing the acoustic transmission loss of the disclosed interlayers of Examples 10, 11, and 12 compared to the same two control acoustic PVB interlayers (Saflex® Q-series PVB interlayers). Figure 4 shows that improvements of up to 3 dB in the high-frequency range can be achieved with only the minimum STL loss in the 2000-3000 Hz range.

[0095]

[0100] Several samples were tested for other physical and optical properties. Table 4 shows the impact results and average fracture height of the three disclosed interlayers (Examples 8, 11, and 14) compared to a commercially available structural interlayer (Saflex® Structural DG-41 interlayer) and a control acoustic interlayer (Saflex® Acoustic QF-51 interlayer). Table 5 shows the clear haze (%) and HLD haze (%) values ​​of the same disclosed interlayers compared to a commercially available monolithic interlayer (Saflex® R-Series RB-41 interlayer).

[0096] [Table 4]

[0097] [Table 5]

[0098]

[0101] Table 4 shows that the disclosed interlayer has similar adhesion (panmel) values ​​to commercially available acoustic triple interlayers having a similar skin layer but a PVB core layer. Table 4 also shows that similar average fracture heights to commercially available acoustic triple interlayers can be achieved.

[0099]

[0102] Table 5 shows that the disclosed interlayers have excellent clear haze and HLD haze values. The haze of the disclosed examples is thought to be higher than that of the control (RB-41) sample due to the presence of an anti-blocking agent (approximately 0.2 wt.% silica and approximately 0.05 wt.% talc) in the ethylene vinyl acetate resin, which is added to ensure the free-flow properties of the EVA pellet, but is still less than 1%. Reducing the amount of anti-blocking agent can lower the haze.

[0100]

[0103] Examples 10-15 show a significant improvement in STL performance compared to commercially available acoustic interlayers (e.g., Saflex® Q series acoustic interlayers used as control samples 1 and 2) in the frequency range of 4000-10000 Hz. The Tg of the core layers in Examples 10-15 is in the range of approximately -8°C to 0°C.

[0101]

[0104] Figure 5 is a graph showing the acoustic transmission loss of the disclosed interlayers of Examples 13, 14, and 15 compared to two control acoustic PVB interlayers (Saflex® Q-series PVB interlayers). Figure 5 shows that it is possible to achieve a 4 dB increase in the 4000–10000 Hz frequency range with only small losses (up to about 1 dB) in the 2000–3000 Hz range. Figure 5 shows a significant increase in the maximum loss tangent in the sample with an EVA-containing core layer compared to a sample with a PVB core layer, e.g., a commercially available three-layer sample. The large maximum loss tangent value of EVA is due to the high weight fraction of vinyl acetate in the copolymer and its amorphous structure (EVA with a vinyl acetate content of less than 55 wt.% is considered a quasicrystalline polymer with an even lower maximum loss tangent).

[0102] Example 2

[0105] To test the adhesion from EVA to PVB, a two-layer peel test sample was prepared. Conventional PVB (Saflex® R series RB-41PVB, 30 mils thick, with a residual hydroxyl content of approximately 18.7 wt.% and a plasticizer of 30 phr) was used as the skin layer together with the EVA core layer. For the EVA layer, 100 parts of EVA resin with a vinyl acetate content of 90 wt.% were mixed with and without an adhesion modifier, and extruded to form a sheet with a thickness of 30 mils. The adhesion modifier used was PVAc-co-crotonic acid copolymer, used in an amount of 10 wt.%.

[0103]

[0106] After fabricating 30-mil sheets measuring 17.78 cm × 17.78 cm (7 inches × 7 inches) with various EVA cores, a two-layer peel-bonded sample was prepared by laminating a 15.24 cm × 15.24 cm (6 inches × 6 inches) 2.3 mm thick glass (air side up), one PVB skin layer, a Mylar insert, an EVA core layer, and a release foil as a support layer. The laminate was degassed using a vacuum bag at ambient temperature for 20 minutes. The vacuum bag was placed in a 130°C oven until the lamination temperature reached 100°C (approximately 20 minutes). After an autoclave cycle at 140°C, the laminate was ready for peel testing. The upper layer bonded to the release foil was cut into 4 cm strips for testing. Peel adhesion was measured in N / cm using an Instron 5943 peel tester.

[0104]

[0107] For EVA samples without an adhesion modifier, the peel adhesion was extremely low, less than 2 N / cm, while for EVA samples containing an adhesion modifier, the peel adhesion was 32 N / cm.

[0105]

[0108] Figure 6 is a set of master curves showing the loss tangents of two EVA core layers compared to two different acoustic PVB interlayers and hydrogenated nitrile butadiene rubber (HNBR). As shown in Figure 6, when using a core layer containing EVA, there is a significant increase in the maximum loss tangent value compared to a core layer containing PVB. The EVA core also has a higher maximum loss tangent than the rubber (HNBR).

[0106]

[0109] Figure 7A is a graph showing the shear modulus as a function of temperature for PVB and EVA composites intended for acoustic applications, and Figure 7B is a graph showing the loss tangent as a function of temperature for PVB and EVA composites intended for acoustic applications. The mechanical properties of EVA, which are most relevant to acoustic performance, are shown in Figures 7A and 7B. During the physical process of acoustic transmission, the modulus of the interlayer determines where the coincidence frequency band begins in the STL spectrum, while the loss tangent determines how much the resulting STL drops when the coincidence effect begins. From Figures 7A and 7B, it is clear that the magnitude of both properties of EVA significantly exceeds that of PVB. In other words, compared to a pure PVB interlayer, EVA can result in a narrower band of STL degradation due to the coincidence effect, in which case the STL reduction is smaller. Therefore, better acoustic performance can be achieved when using a core layer containing EVA.

[0107]

[0110] In conclusion, multilayer interlayers having a layer containing ethylene vinyl acetate resin offer advantages over conventional multilayer interlayers previously used in the art. Overall, compared to multilayer interlayers previously used in the art, the multilayer interlayers containing ethylene vinyl acetate resin described herein have improved acoustic properties. Other advantages will be readily apparent to those skilled in the art.

[0108]

[0111] The present invention has been disclosed in conjunction with descriptions of certain embodiments, including those currently considered to be preferred embodiments. These detailed descriptions are intended to be illustrative and should not be understood as limiting the scope of this disclosure. Embodiments other than those described herein are encompassed by the present invention, as will be understood by those skilled in the art. Modifications and alterations of the described embodiments may be made without departing from the spirit and scope of the present invention.

[0109]

[0112] It is further understood that any range, value, or characteristic given to any one component of this disclosure may be used interchangeably with any range, value, or characteristic given to any other component of this disclosure, if they are compatible, in order to form embodiments having the respective values ​​of each component given herein. For example, to form many substitutions within the scope of this disclosure, although it would be cumbersome to enumerate them all, an interlayer can be formed containing a poly(vinyl butyral) having a residual hydroxyl content of any of the given ranges, in addition to containing a plasticizer of any of the given ranges. Furthermore, unless otherwise indicated, the ranges given for classes or categories, such as phthalates or benzoates, may also be applied to chemical species within a class or category, such as dioctyl terephthalate. The present invention includes the following embodiments. [1] First polymer layer; The second polymer layer; A third polymer layer located between the first polymer layer and the second polymer layer comprises an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 70 weight percent. A multilayer interlayer film containing a multilayer film. [2] The multilayer interfilm according to [1], wherein the third polymer layer does not contain added plasticizers. [3] The multilayer interfilm according to [1], wherein the third polymer layer contains a plasticizer. [4] The multilayer interfilm according to [1], wherein the third polymer layer has a glass transition temperature (Tg) of less than 0°C. [5] The multilayer interfilm according to [1], wherein the third polymer layer comprises an adhesion modifier in an amount of at least 0.1 weight percent. [6] The multilayer interfilm according to [1], wherein the first polymer layer comprises a poly(vinyl acetal) resin and at least one plasticizer. [7] The multilayer interfilm according to [1], wherein the second polymer layer comprises a poly(vinyl acetal) resin and at least one plasticizer. [8] The multilayer interfilm according to [1], wherein the first polymer layer comprises a poly(vinyl butyral) resin and at least one plasticizer. [9] The multilayer interfilm according to [1], wherein the second polymer layer comprises a poly(vinyl butyral) resin and at least one plasticizer.

[10] The multilayer interfilm according to [1], wherein the first polymer layer and the second polymer layer each comprise a poly(vinyl acetal) resin and at least one plasticizer.

[11] The multilayer interfilm according to [1], wherein the first polymer layer and the second polymer layer each comprise a poly(vinyl butyral) resin and at least one plasticizer.

[12] A multilayer interlayer according to [1], having an acoustic transmission loss (STL) of at least about 40 decibels (dB) at 4000 hertz (Hz) (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration according to ASTM E90 (2009)) and an attenuation loss coefficient of at least 0.2 (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration according to ISO 16940).

[13] A multilayer interlayer according to [1] having an acoustic transmission loss (STL) of at least about 39 dB at 2000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)).

[14] A multilayer interlayer as described in [1], having an acoustic transmission loss (STL) of at least about 47.5 dB at 6350 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)).

[15] A multilayer interlayer as described in [1], having an acoustic transmission loss (STL) of at least about 54 dB at 10,000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration according to ASTM E90 (2009)).

[16] A first polymer layer comprising poly(vinyl acetal) resin and a plasticizer; A second polymer layer comprising poly(vinyl acetal) resin and a plasticizer; A third polymer layer located between the first polymer layer and the second polymer layer comprises an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 70 weight percent. A multilayer interlayer film containing a multilayer film.

[17] First rigid base material, An interlayer according to any one of [1] to

[16] , and Second rigid base material Multi-layer glazing including.

Claims

1. A first polymer layer comprising a poly(vinyl butyral) resin and at least one plasticizer, wherein the plasticizer content of the first polymer layer is greater than 0 phr and 120 phr or less; A second polymer layer comprising poly(vinyl butyral) resin and at least one plasticizer, wherein the plasticizer content of the second polymer layer is greater than 0 phr and 120 phr or less; The polymer comprises an ethylene vinyl acetate copolymer having a vinyl acetate content of at least 70 weight percent, and a third polymer layer located between the first polymer layer and the second polymer layer, wherein the third polymer layer is in contact with the first polymer layer and the second polymer layer, and the plasticizer content of the third polymer layer is 0 to 120 phr; A multilayer interlayer film for double-glazed glass panels, including the above.

2. The multilayer interfilm according to claim 1, wherein the third polymer layer does not contain added plasticizers.

3. The multilayer interfilm according to claim 1, wherein the third polymer layer contains a plasticizer.

4. The multilayer interfilm according to claim 1, wherein the third polymer layer has a glass transition temperature (Tg) of less than 0°C.

5. The multilayer interfilm according to claim 1, wherein the third polymer layer contains an adhesion modifier in an amount of at least 0.1 weight percent.

6. The multilayer interlayer according to claim 1, having an acoustic transmission loss (STL) of at least about 40 decibels (dB) at 4000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)) and an attenuation loss coefficient of at least 0.2 (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ISO 16940).

7. The multilayer interlayer according to claim 1, having an acoustic transmission loss (STL) of at least about 39 dB at 2000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)).

8. The multilayer interlayer according to claim 1, having an acoustic transmission loss (STL) of at least about 47.5 dB at 6350 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)).

9. The multilayer interlayer according to claim 1, having an acoustic transmission loss (STL) of at least about 54 dB at 10,000 Hz (measured at 20°C with a 2.3 mm / 2.3 mm glass configuration by ASTM E90 (2009)).

10. First rigid base material, An interlayer according to any one of claims 1 to 9, and Second rigid base material Multi-layer glazing including.

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