TW201726391A - High rigidity interlayers and light weight laminated multiple layer panels - Google Patents

Abstract

This disclosure is related to the field of polymer interlayers for multiple layer panels and multiple layer panels having at least one polymer interlayer sheet. Specifically, this disclosure is related to the field of high rigidity interlayers and light weight laminated multiple layer panels incorporating high rigidity interlayers.

Description

Highly rigid inner layer and lightweight layered multilayer board

This invention relates to the field of polymeric inner layers for multilayer boards and multilayer boards having at least one inner layer of polymer. In particular, the present invention relates to the field of lightweight laminate layers of highly rigid inner layers and highly rigid inner layers.

One aspect of the invention relates to a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; and adjacent to the first polymer layer a second polymer layer in contact therewith. The second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticizer. The inner layer comprises a third polymer layer comprising a third poly(vinyl butyral) resin and at least one plasticizer. The second polymer layer is adjacent to and in contact with the first and third polymer layers. The second poly(vinyl butyral) resin has a residual hydroxyl content difference of at least 7 wt% from the first poly(vinyl butyral) resin and/or the third poly(vinyl butyral) resin The residual hydroxyl content. The second polymer layer has a glass transition temperature of less than 9 ° C and a maximum thickness of no more than 9 mils. At least one of the first polymer layer and the third polymer layer has a glass transition temperature of at least 33 ° C and a thickness greater than 13 mils. Another aspect of the invention relates to a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; and a second poly(vinyl butyl) An acetal) resin and a second polymer layer of at least one plasticizer. The second polymer layer has a glass transition temperature of less than 9 °C. The inner layer comprises a third polymer layer comprising a third poly(vinyl butyral) resin and at least one plasticizer. The second polymer layer is disposed between and in contact with each of the first polymer layer and the second polymer layer. The glass transition temperature of at least one of the first polymer layer and the third polymer layer is at least 33 °C. The inner layer has an equivalent glass transition temperature (T _eq ) in the range of 27 ° C to less than 29 ° C. Another aspect of the invention relates to a multiple glazing panel comprising a pair of rigid substrates and an inner layer disposed between the substrates. The inner layer comprises a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer. The inner layer comprises a second polymer layer comprising a second poly(vinyl butyral) resin and at least one plasticizer, and a third polymer comprising a third poly(vinyl butyral) resin and at least one plasticizer Three polymer layers. The glass transition temperature of at least one of the first polymer layer and the third polymer layer is at least 33 ° C, and the combined thickness of the first polymer layer and the third polymer layer is at least 28 mils. The combined thickness of the rigid substrates is less than or equal to 4.0 mm.

In general, a multilayer board is constructed of two glass sheets or other applicable substrates that sandwich one or more polymeric inner sheets. Multilayer boards are typically prepared by placing at least one polymeric inner layer sheet between two substrates to create an assembly. It is not uncommon for multi-polymer inner sheets to be placed in two substrates, thereby creating a multi-layer sheet having a multi-polymer inner layer. After the air is removed from the self-assembly, the components of the assembly are initially pressure bonded together using methods generally known to those skilled in the art. The final overall structure is formed by a laminating process such as, but not limited to, high pressure processing to make the initial pressure bond more durable. Poly(vinyl butyral) (hereinafter referred to as "PVB") is a polymer commonly used in the production of polymer inner layers and multilayer boards. One of the primary functions of a multilayer board formed from one or more PVB inner layers is to absorb energy such as that caused by the force of the target impacting plate without dispersing it through the plate or glass fragments. Thus, when such panels are used in windows of motor vehicles, aircraft, structures, or other targets (often common applications), they have the effect of minimizing damage or damage to personnel or targets within the target enclosure area. In addition to safety benefits, the polymer inner layer of the multilayer board can also be used to impart other beneficial effects to the board, including but not limited to noise attenuation, reduced UV and/or IR light transmission, and enhanced overall appearance and aesthetic appeal of the window opening. . Recently, due to the growing social attention to the fuel efficiency of automotive and air transportation, multi-layer boards that are lighter than conventional models have been required. This need arises from the fact that weight is directly related to the fuel efficiency of the car or aircraft; the heavier the vehicle, the more fuel needs to move from point A to point B. In general, multi-layer boards account for the majority (about 45 to 68 kg) of weight of modern motor vehicles. Due to aesthetic add-ons such as sunroofs or panoramic sunroofs and larger windshields, the weight percentage of cars attributed to multi-layer boards is even increasing in some modern car models. The weight reduction of the multi-layer panels used in such applications will generally result in a significant reduction in the overall weight of the vehicle and associated fuel efficiency increases. Most of the weight in these panels is not in the inner layer weight but in the substrate weight. Traditionally, multi-layer panels for automotive applications, such as windshields, sun or moon skylights, and side and rear windows, are typically constructed of two glass sheets of the same thickness with an inner layer of PVB disposed therebetween. In general, each substrate sheet thickness in such applications is from about 2.0 mm to 2.3 mm. Lighter weight multilayer boards are achieved by using thinner glass with a symmetrical or asymmetric substrate configuration. The current form for achieving a lighter weight multilayer board for windshields is generally related to asymmetric substrate configuration. In these configurations, the thickness of the outer substrate (ie, the substrate facing the exterior of the vehicle cabin) is maintained at a conventional thickness of about 2.0 mm to 2.3 mm, while the thickness of the inner substrate (ie, the substrate facing the interior of the chamber) is reduced. . The outer substrate thickness is maintained at about 2.0 mm to 2.3 mm to maintain the strength of the plate to withstand the forces of sand, gravel, and other road debris and dangerous objects that can impact the motor vehicle during transportation. The inner substrate thickness is reduced to reduce the overall overall weight of the board. The overall glass thickness of the asymmetric window panels for windshields can be configured to as low as 3.7 mm. Asymmetric substrate configurations are typically used for windshields to achieve lighter weight, while symmetric substrate configurations are commonly used in multi-layer boards in side windows and skylights in automobiles. In general, the panels used for such windows are thermally strengthened to provide structural and mechanically strong inlaid glass to resist debris and can be closed by the door, board movement as the window descends and rises, sunroof movement and smaller targets Cracking caused by the impact of the board. The overall glass thickness of the symmetrical window panels for side and skylight windows can be configured to as low as 3.6 mm. Due to the reduced overall thickness, multi-layer boards prepared by asymmetric substrate configurations offer the opportunity to save weight and thus improve fuel economy in automotive and aerospace applications. For example, the surface area of a windshield is usually about 1.4 m.² . For a conventional 2.1 mm/2.1 mm glass configuration with a conventional PVB inner layer, the total weight of the windshield is approximately 15.8 kg. For asymmetric glass configurations, such as 2.1 mm/1.6 mm, which is one of the lowest merging glass thicknesses currently available for commercial use, the weight of the asymmetric windshield is approximately 14.1 kg, saving 1.7 over conventional multilayer boards. Kg, 10.8% by weight. Although asymmetric multilayer boards do result in increased weight savings, they are not without cost. A major problem is that lightweight laminates prepared via asymmetric morphology, while lighter, are not as strong as multilayer boards prepared by conventional methods. The mechanical strength of the windshield, such as the deflection stiffness, decreases as the thickness of the glass decreases. For example, the deflection stiffness of a 3.7 mm monolithic glass sheet is reduced by 33% compared to a 4.2 mm monolithic glass sheet. Therefore, the glass bending strength, the glass edge strength, the glass impact strength, the skylight strength, and the torsional rigidity are all reduced in these sheets. The strength of the panels used in automotive windows is critical, in part because in today's vehicles, the panels are part of the vehicle structure and contribute to the overall mechanical strength and rigidity of the vehicle body, particularly the sunroof of the vehicle. For example, on the Ford P2000 body, the torsional stiffness of the body is 24.29 kNm at the angle of the windshield and the rear glass in situ, and 16.44 kNm when the glass is not in place. See M. A. Khaleel et al., Effect of Glazing System Parameters on Glazing System Contribution to a Lightweight Vehicle's Torsional Stiffness and Weight.International Body And Engineering Conference , Detroit (2000) SAE Paper No. 2000-01-2719 (the entire disclosure of which is incorporated herein by reference). The glass contributes about 30% of the overall stiffness of the car. This contribution to the structure of the car is critical in normal vehicle operations and in the event of a collision or other accident. If the strength of the multi-layer board in the window of the car is damaged for lower weight and greater fuel efficiency, the structural rigidity and overall safety of the vehicle will be reduced. Since all problems are associated with asymmetrically configured multi-layer boards, there is a need in the art for lightweight multi-layer boards that have improved mechanical strength and therefore improved structural rigidity and overall safety of the vehicle. It is therefore an object of the present invention to design a lightweight multilayer board comprising an inner layer wherein the reduction in mechanical strength of the sheet due to the reduced glass thickness is at least partially compensated by the inner layer. Due to these and other problems in the art, the invention herein relates in particular to a lightweight multilayer glass panel comprising: a first glass substrate; a second glass substrate; and a first glass substrate and a second glass substrate At least one inner polymer layer, the inner layer of the polymer has a glass transition temperature greater than or equal to about 33 degrees Celsius. The combined thickness of the first glass substrate and the second glass substrate is less than or equal to about 4.0 mm. In addition, the deflection hardness of the multilayer glass sheet is higher than the deflection hardness of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) inner layer, and in some embodiments, the deflection hardness ratio of the multilayer glass sheet is the same Multilayer boards of thickness and glass configuration but having a conventional (non-rigid) inner layer have a deflection hardness of at least 10% or at least 20% higher. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than or equal to about 300. Newtons/cm, greater than about 320 Newtons/cm or greater than about 360 Newtons/cm. In some embodiments, the inner polymer layer comprises plasticized poly(vinyl butyral). The combined thickness of the first glass substrate and the second glass substrate may also be less than or equal to about 3.9 mm, or less than or equal to about 3.7 mm. In other embodiments, the inner layer of the polymer has a glass transition temperature greater than or equal to about 35 degrees Celsius. Also disclosed herein are multiple layers of glass sheets comprising: a first glass substrate; a second glass substrate; and a plurality of inner layers disposed between the first glass substrate and the second glass substrate. The multilayer inner layer comprises: a first plasticized polymer layer having a glass transition temperature greater than or equal to about 33 degrees Celsius; and a second plasticized polymer in contact with the first plasticized polymer layer, and a glass of the second plasticized polymer layer The transfer temperature is less than 30 degrees Celsius. The combined thickness of the first glass substrate and the second glass substrate is less than or equal to about 4.0 mm. The deflection hardness of the multilayer glass sheet is higher than the deflection hardness of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) multilayer inner layer, and in some embodiments, the deflection hardness ratio of the multilayer glass sheet has the same thickness The multilayer board of the glass configuration but having a conventional (non-rigid) multilayer inner layer has a deflection hardness of at least 10% or at least 20% higher. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than or equal to about 240. Newton/cm. In addition, the multilayer glass plate has a sound transmission loss (TL of greater than or equal to about 36 dB) at a reference frequency of 3150 Hz._Ref ). In some embodiments, the first plasticized polymer layer comprises plasticized poly(vinyl butyral) and the second plasticized polymer layer comprises plasticized poly(vinyl butyral). Additionally, the plate may comprise a third plasticized polymer layer composed of plasticized poly(vinyl butyral), wherein the second plasticized polymer layer is disposed on the first plasticized polymer layer and the third plasticized polymer Between the layers. In other embodiments, the multi-layer glass sheet has a higher deflection stiffness than a multi-layer sheet having the same thickness and glass configuration but having a conventional (non-rigid) inner layer, and in some embodiments, the deflection of the multi-layer glass sheet The flexural hardness of the multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) inner layer is at least 10% higher or at least 20% higher. In some embodiments, the multilayer board has a deflection hardness greater than about 250 Newtons per centimeter. In still other embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multi-layer glass plate is greater than about 280. Newton/cm. The combined thickness of the first glass substrate and the second glass substrate may also be less than or equal to about 3.9 mm, or less than or equal to about 3.7 mm. Additionally, the glass transition temperature of the first plasticized polymer layer can be greater than or equal to about 36 degrees Celsius, or the glass transition temperature of the second plasticized polymer layer can be less than or equal to about 20 degrees Celsius. Also disclosed herein are multiple layers of glass sheets comprising: a first glass substrate; a second glass substrate; and a plurality of inner layers disposed between the first glass substrate and the second glass substrate. The multilayer inner layer comprises: a first plasticized polymer layer having a residual hydroxyl group content of greater than or equal to about 19% by weight and a plasticizer content of less than or equal to about 35 phr; and a first contact with the first plasticized polymer layer The second plasticized polymer layer, the second plasticized polymer layer having a residual hydroxyl content of less than or equal to about 16% by weight and a plasticizer content of greater than or equal to about 48 phr. The combined thickness of the first glass substrate and the second glass substrate is less than or equal to about 4.0 mm, and the deflection hardness of the multilayer glass plate is higher than that of the multilayer plate having the same thickness and glass configuration but having a conventional (non-hard) inner layer Hardness, and in some embodiments, the multilayer glass sheet has a deflection hardness that is at least 10% or at least 20% higher than the deflection hardness of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) inner layer. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than or equal to about 240. Newton. In addition, the multi-layer glass sheet has a sound transmission loss of greater than or equal to about 36 decibels (TL_Ref ). In some embodiments, the first plasticized polymer layer comprises plasticized poly(vinyl butyral) and the second plasticized polymer layer comprises plasticized poly(vinyl butyral). Additionally, the plate may comprise a third plasticized polymer layer composed of plasticized poly(vinyl butyral), wherein the second plasticized polymer layer is disposed on the first plasticized polymer layer and the third plasticized polymer Between the layers. In some embodiments, the first plasticized polymer layer has a residual hydroxyl content of greater than or equal to about 20% by weight. In other embodiments, the second plasticized polymer layer has a residual hydroxyl content of less than or equal to about 15% by weight and a plasticizer content of greater than or equal to about 70 phr. In certain alternative embodiments, the multilayer glass sheet has a higher deflection stiffness than a multilayer sheet having the same thickness and glass configuration but having a conventional (non-rigid) inner layer, and in some embodiments, a multiple layer glass sheet The deflection hardness is at least 10% higher or at least 20% higher than the deflection hardness of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) inner layer. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than about 250 Newtons/ The centimeters, or greater than about 280 Newtons per centimeter. The combined thickness of the first glass substrate and the second glass substrate may also be less than or equal to about 3.9 mm, or less than or equal to about 3.7 mm. Also disclosed herein are multiple layers of glass sheets comprising: a first glass substrate; a second glass substrate; and a plurality of inner layers disposed between the first glass substrate and the second glass substrate. The multilayer inner layer comprises: a first plasticized polymer layer; and a second plasticized polymer layer in contact with the first plasticized polymer layer. The multilayer inner layer has an equivalent glass transition temperature (T) as defined below, greater than or equal to about 29 degrees Celsius_Eq ). In this embodiment, the combined thickness of the first glass substrate and the second glass substrate is less than or equal to about 4.0 mm, and the deflection hardness of the multilayer glass plate is higher than that of the conventional (non-hard) multilayer having the same thickness and glass configuration. The deflection hardness of the inner layer of the multilayer board, and in some embodiments, the multilayer glass sheet has a deflection hardness that is at least 10 greater than that of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) multilayer inner layer. % or higher at least 20%. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than or equal to about 240. Newton/cm. In addition, the multi-layer glass sheet has a sound transmission loss of greater than or equal to about 36 decibels (TL_Ref ). In some embodiments, the first plasticized polymer layer comprises plasticized poly(vinyl butyral) and the second plasticized polymer layer comprises plasticized poly(vinyl butyral). Additionally, the plate may comprise a third plasticized polymer layer composed of plasticized poly(vinyl butyral), wherein the second plasticized polymer layer is disposed on the first plasticized polymer layer and the third plasticized polymer Between the layers. In certain alternative embodiments, the multilayer glass sheet has a higher deflection stiffness than a multilayer sheet having the same thickness and glass configuration but having a conventional (non-rigid) inner layer, and in some embodiments, a multiple layer glass sheet The deflection hardness is at least 10% higher or at least 20% higher than the deflection hardness of a multilayer board having the same thickness and glass configuration but having a conventional (non-rigid) inner layer. In some embodiments, when the combined thickness of the first glass substrate and the second glass substrate is less than or equal to 4.0 mm, or less than or equal to 3.9 mm, or less than or equal to 3.7 mm, the deflection hardness of the multilayer board is greater than about 250 Newtons/ The centimeters, or greater than about 280 Newtons per centimeter. The combined thickness of the first glass substrate and the second glass substrate may also be less than or equal to about 3.9 mm, or less than or equal to about 3.7 mm. In other embodiments, the equivalent glass transition temperature of the multilayer inner layer (T_Eq ) is greater than or equal to about 31 degrees Celsius, or greater than or equal to about 34 degrees Celsius. According to some embodiments, a multilayer inner layer comprising: a first plasticized polymer layer, wherein a first glass transition temperature of the first plasticized polymer layer is at least 33 ° C; and a second plasticized polymer layer, wherein the second The plasticized polymer layer has a glass transition temperature of less than 10 ° C and a thickness of 5 mils or less, and wherein the inner layer has a sound transmission loss of at least 35 dB at the coincidence frequency (TL)_c And an equivalent glass transition temperature of at least 27 ° C (T_Eq ). In some embodiments, a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; and an adjacent polymer in the inner layer a second polymer layer of the layer, wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticizer, wherein the second poly(vinyl butyral) resin has a first poly The hydroxyl content of the (vinyl butyral) resin differs by at least 6% by weight of the residual hydroxyl content, wherein the second polymer layer has a glass transition temperature of less than 9 ° C and a maximum thickness of less than 9 mils, wherein the inner layer is at the coincidence frequency At least 35 dB of sound transmission loss (TL_c And/or a weighted average sound transmission loss of at least 38 dB between 2,000 and 8,000 Hz (TL)_w ). In some embodiments, a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer, wherein a glass transition temperature of the first polymer layer is provided Is at least 33 ° C; and a second polymer layer adjacent to the first polymer layer in the inner layer, wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticization The agent, wherein at least one of the first polymer layer and the second polymer layer has an average shear storage modulus (G' of at least 150 MPa in a 1/3 octave band frequency of 2,000 to 8,000 Hz ), wherein the inner layer has a sound transmission loss of at least 35 dB at the coincidence frequency (TL_c And/or a weighted average sound transmission loss of at least 38 dB between 2,000 and 8,000 Hz (TL)_w ). The shear storage modulus (G') can be determined using dynamic mechanical analysis (DMA) as described in further detail below. In some embodiments, a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; and a second poly(vinyl butyral) is provided a second polymer layer of a resin and at least one plasticizer, wherein the second polymer layer has a glass transition temperature of less than 9 ° C; and a third polymer comprising a third poly(vinyl butyral) resin and at least one plasticizer a polymer layer, wherein a second polymer layer is disposed between and in contact with each of the first polymer layer and the second polymer layer, wherein the first poly(vinyl butyral) resin and the second Poly(vinyl butyral) resin, second poly(vinyl butyral) resin and third poly(vinyl butyral) resin and first poly(vinyl butyral) resin and third poly( The maximum difference in residual hydroxyl content between the vinyl butyral resins is at least 6% by weight, wherein the ratio of the combined thickness of the first and third polymeric layers to the thickness of the second polymeric layer is at least 2.25: 1, and the overall inner layer thickness is less than or equal to 90 mils, wherein the equivalent glass transition temperature of the inner layer (T_Eq ) is at least 27 ° C. In some embodiments, a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer, wherein the first poly(vinyl butyral) is provided The resin has a residual hydroxyl content of at least 19% by weight; and a second polymer layer adjacent to the first polymer layer in the inner layer, wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least A plasticizer wherein a second polymer layer has a glass transition temperature of not more than 20 ° C, wherein at least one of the first polymer layer and the second polymer layer is at a 1/3 octave band of 2,000 to 8,000 Hz An average shear storage modulus (G') of at least 150 MPa in frequency, wherein the inner layer has a sound transmission loss of at least 35 dB at the coincidence frequency (TL)_c And/or a weighted average sound transmission loss of at least 38 dB between 2,000 and 8,000 Hz (TL)_w ). According to some embodiments, a multiple layer glass sheet comprising a pair of rigid substrates and a plurality of inner layers disposed between the rigid substrates is provided, the inner layer comprising a first polymer layer comprising a residue having greater than 19% by weight a hydroxyl group-containing first poly(vinyl butyral) resin and at least one plasticizer, wherein the first polymer layer has a glass transition temperature of at least 33 ° C; and a second polymer layer, the second polymer layer comprising a second poly(vinyl butyral) resin having a residual hydroxyl group content of less than 16% by weight and at least one plasticizer, wherein the glass transition temperature of the second polymer layer is at least lower than the glass transition temperature of the first polymer layer 20 ° C. In addition, when the combined thickness of the rigid substrate is less than 4.0 mm, less than 3.9 mm, or less than 3.7 mm, the deflection hardness of the panel is at least 240 N/cm. In other embodiments, a multilayer board comprising a pair of rigid substrates and an inner layer disposed between the substrates is provided, wherein the inner layer comprises at least a first poly(vinyl butyral) resin and at least one plasticizer At least one polymer layer, wherein the polymer layer has an average shear storage modulus (G') of at least 150 MPa in a 1/3 octave band frequency of 2,000 to 8,000 Hz, and wherein the inner layer has a coincidence frequency At least 35 dB of sound transmission loss (TL_c And/or a weighted average sound transmission loss of at least 38 dB between 2,000 and 8,000 Hz (TL)_w ). In addition, when the combined thickness of the rigid substrate is less than 4.0 mm, the deflection hardness of the panel is at least 240 N/cm. In some embodiments, a multiple layer glass sheet comprising a pair of rigid substrates and an inner layer disposed between the substrates is provided, wherein the inner layer comprises at least a first polymer layer comprising poly(vinyl condensate) An aldehyde resin and at least one plasticizer and having a glass transition temperature of at least 33 ° C, wherein the inner layer has a sound transmission loss of at least 35 dB at the coincidence frequency (TL_c And/or measure a weighted average sound transmission loss of at least 38 dB between 2,000 and 8,000 Hz (TL)_w ). In addition, when the combined thickness of the rigid substrate is less than 4.0 mm, the deflection hardness of the sheet is at least 225 N/cm. Also described herein are particularly high-rigidity inner layers and lightweight multi-layer boards (and high-rigidity inner layers) that have significantly reduced weight compared to conventional multi-layer boards and are associated with thin glass combinations with symmetric or asymmetric configurations. The intensity will not be significantly reduced. In one embodiment, for example, the lightweight multi-layer sheet is composed of two glass sheets or other applicable substrates having a thickness of 4.0 mm or less and at least one inner layer having a glass transition temperature of at least greater than 33 ° C, wherein The inner layer is sandwiched between two substrates. When used in floating or annealed glass, the resulting multilayer board can have a deflection hardness that is at least 20% higher than conventional multilayer sheets. When used to combine floating or annealed glass having a substrate thickness of 3.7 mm, the lightweight multilayer board may also have a deflection hardness of at least 285 N/cm. To promote a more complete understanding of the inner layers and multilayer boards disclosed herein, the meaning of certain terms as used in this application will be first defined. When the terms are understood by those skilled in the art, such definitions should not limit such terms, but merely improve the understanding of the terms used herein. As used herein, the terms "polymer inner sheet", "inner layer", "polymer layer" and "polymer melt sheet" may refer to a single layer sheet or multiple layers of inner layer. As the name implies, "single layer sheet" is a single polymer layer extruded in the form of a layer. Alternatively, the multilayer inner layer can comprise a plurality of layers, including separately extruded layers, coextruded layers, or any combination of separately extruded layers and coextruded layers. Thus, the multilayer inner layer may comprise, for example, two or more single layer sheets ("multiple layer sheets") that are combined together; two or more layers that are coextruded together ("coextruded sheets" And two or more coextruded sheets; a combination of at least one single layer sheet and at least one coextruded sheet; and a combination of at least one plurality of layer sheets and at least one coextruded sheet. In various embodiments of the invention, the multilayer inner layer comprises at least two polymer layers (eg, a single layer or a plurality of coextruded layers) disposed in direct contact with one another, wherein each layer comprises a polymeric resin. The term "resin" as used herein refers to a polymer component (eg, PVB) that is removed by acid catalysis of a free polymer precursor and subsequent neutralization resulting from a mixture. In general, plasticizers, such as those plasticizers more fully discussed below, are added to the resin to give a plasticized polymer. In addition, the resin may have other components than the polymer and the plasticizer, including, for example, acetates, salts, and alcohols. It should also be noted that although the inner layer of poly(vinyl butyral) ("PVB") is often specifically discussed herein as a polymer resin for the inner layer of the polymer, it should be understood that it is also possible to use an inner layer other than the PVB. Other thermoplastic inner layers. Polymers contemplated include, but are not limited to, polyurethanes, polyvinyl chloride, poly(ethylene vinyl acetate), and combinations thereof. These polymers can be utilized alone or in combination with other polymers. Accordingly, it should be understood that when ranges, values, and/or methods are provided to the PVB inner layers (eg, plasticizer component percentage, thickness, and property enhancing additives) in the present application, their ranges, values, and/or methods are Other polymers and polymer blends disclosed herein are also suitable, as applicable, or may be modified to apply to different materials as is known to those skilled in the art. The PVB resin is prepared by a known aqueous or solvent acetalization method by reacting polyvinyl alcohol ("PVOH") with butyraldehyde in the presence of an acid catalyst to separate the resin, and to prepare it stably and dry. Such acetalization processes are disclosed in, for example, U.S. Patent Nos. 2,282,057 and 2,282,026, and to Vinyl Acetal Polymers, issued by BE Wade (2003), Encyclopedia of Polymer Science & Technology, 3rd Edition, Volume 8, page 381. To page 399, the entire disclosures of which are incorporated herein by reference. The resins are commercially available in various forms, for example, in the form of Butvar® resin available from Solutia Inc.. As previously discussed, although generally referred to herein as "poly(vinyl acetal)" or "poly(vinyl butyral)", the resins described herein may include any suitable aldehyde group, including (but not limited to) isobutyraldehyde. In some embodiments, one or more poly(vinyl acetal) resins can include at least one C₁ To C₁₀ Aldehyde or at least one C₄ To C₈ A group of aldehydes. Suitable for C₄ To C₈ Examples of aldehydes can include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylpentanal, n-hexyl aldehyde, 2-ethylhexyl aldehyde, n-octyl aldehyde, and combinations thereof. In various embodiments, a plasticizer is added to the polymer resin to form a polymer layer or inner layer. A plasticizer is usually added to the polymer resin to increase the flexibility and durability of the inner layer of the resulting polymer. The plasticizer acts by embedding itself between the polymer chains, spacing the polymer chains apart (thus increasing the "free volume") and thus significantly reducing the glass transition temperature of the polymer resin (T_g ), thereby making the material softer. In this aspect, the amount of plasticizer in the inner layer can be adjusted to affect the glass transition temperature (T_g ). Glass transfer temperature (T_g ) is the temperature at which the inner layer of the mark is transferred from the glass state to the rubber state. In general, the higher the loading of plasticizer, the lower the T can be obtained._g . In various embodiments, and as described more fully in the examples, the highly rigid inner layer comprises a layer having a glass transition temperature greater than about 33 °C. Plasticizers covered include, but are not limited to, polybasic acids, esters of polyhydric alcohols; triethylene glycol bis(2-ethylbutyrate); triethylene glycol bis(2-ethylhexanoate) (already Known as "3-GEH"); triethylene glycol diheptanoate; tetraethylene glycol diheptanoate; dihexyl adipate; dioctyl adipate; cyclohexyl adipate hexyl ester; a mixture of heptyl dicarboxylate and decyl adipate; diisononyl adipate; heptyl adipate; dibutyl sebacate; and polymeric plasticizer, such as oil-modified azelaic acid Alkyd resins and mixtures of phosphates and adipates, as well as mixtures and combinations thereof. 3-GEH is especially preferred. Other examples of suitable plasticizers may include, but are not limited to, tetraethylene glycol di(2-ethylhexanoate) ("4-GEH"), di(butoxyethyl) adipate, and Bis(2-(2-butoxyethoxy)ethyl) dicarboxylate, dioctyl sebacate, nonylphenyltetraethyl glycol and mixtures thereof. In some embodiments, the plasticizer covered is 3-GEH having a refractive index of 1.442 at 25 °C. In some embodiments, other plasticizers, such as high refractive index plasticizers, can be used. As used herein, the term "high refractive index plasticizer" refers to a plasticizer having a refractive index of at least 1.460. As used herein, the refractive index (also known as index of refraction) values of the plasticizers or resins described herein are measured according to ASTM D542 at wavelengths of 589 nm and 25 ° C or according to ASTM. D542 is reported in the literature. In various embodiments, the plasticizer has a refractive index of at least 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. These plasticizers can be used in one or more layers of the inner layer. If the inner layer is a three-layer inner layer, the plasticizers can be used for each of the three layers. In some embodiments, one or more high refractive index plasticizers can be used in combination with a plasticizer having a refractive index of less than 1.460, such as 3-GEH. According to these embodiments, the plasticizer mixture can have a refractive index of at least 1.460. High refractive index plasticizers suitable for use in one or more embodiments of the invention may include, for example, polyadipates (RI from about 1.460 to about 1.485); epoxides (RI from about 1.460 to about 1.480); Phthalate and terephthalate (RI from about 1.480 to about 1.540); benzoate (RI from about 1.480 to about 1.550); and other special plasticizers (RI from about 1.490 to about 1.520) ). Examples of high refractive index plasticizers may include, but are not limited to, especially polybasic or polyhydric alcohol esters, polyadipates, epoxides, phthalates, terephthalates, benzates Acid esters, toluates, mellitic acid esters and other special plasticizers. Other examples of suitable plasticizers include, but are not limited to, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate Ester, 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-toluic acid Ester, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tris-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, diphenol A (2-ethylhexanoate), ethoxylated nonylphenol, and mixtures thereof. In general, the plasticizer content of the inner layer of the polymer of the present application is measured in parts by weight per hundred resin parts ("phr"). For example, if 30 grams of plasticizer is added to 100 grams of polymer resin, the resulting plasticized polymer will have a plasticizer content of 30 phr. When the plasticizer content of the polymer layer is given in this application, the plasticizer content of the particular layer is determined by reference to the phr of the plasticizer used to prepare the melt of the particular layer. In some embodiments, the highly rigid inner layer comprises a layer having a plasticizer content of less than about 35 phr and less than about 30 phr. According to some embodiments of the invention, the one or more polymer layers described herein may have a total plasticizer content of at least about 20 phr, at least about 25 phr, at least about 30 phr, at least about 35 phr, at least about 38. a phr, at least about 40 phr, at least about 45 phr, at least about 50 phr, at least about 55 phr, at least about 60 phr, at least about 65 phr, at least about 67 phr, at least about 70 phr, at least about 75 phr, or more Plasticizer. In some embodiments, the polymeric layer can also include no more than about 100 phr, no more than about 85 phr, no more than 80 phr, no more than about 75 phr, no more than about 70 phr, no more than about 65 phr, no more than about 60 phr, no more than about 55 phr, no more than about 50 phr, no more than about 45 phr, no more than about 40 phr, no more than about 38 phr, no more than about 35 phr or no more than about 30 phr or more plasticized Agent. In some embodiments, the total plasticizer content of the at least one polymer layer can range from about 20 to about 40 phr, from about 20 to about 38 phr, or from about 25 to about 35 phr. In other embodiments, the total plasticizer content of the at least one polymer layer can range from about 38 to about 90 phr, from about 40 to about 85 phr, or from about 50 to 70 phr. When the inner layer comprises a plurality of inner layers, the two or more polymer layers in the inner layer may have substantially the same plasticizer content and/or at least one of the polymer layers may have a different polymerization than the other The plasticizer content of one or more of the layers. When the inner layer comprises two or more polymer layers having different plasticizer contents, the two layers may abut each other. In some embodiments, the difference in plasticizer content between adjacent polymer layers can be at least about 1 phr, at least about 2 phr, at least about 5 phr, at least about 7 phr, at least about 10 phr, at least about 20 Ph, at least about 30 phr, at least about 35 phr and/or no more than about 80 phr, no more than about 55 phr, no more than about 50 phr or no more than about 45 phr, or from about 1 to about 60 phr, about 10 to Approximately 50 phr or approximately 30 to 45 phr. When three or more layers are present in the inner layer, at least two of the polymer layers of the inner layer may have similar plasticization to each other, for example within 10 phr, within 5 phr, within 2 phr, or within 1 phr. The agent content, while at least two of the polymer layers may have a plasticizer content that differs from each other according to the above range. In some embodiments, one or more of the polymer layers or inner layers described herein can include two or more plasticizers (including, for example, two or more of the plasticizers listed above). a blend of many). When the polymer layer includes two or more plasticizers, the difference between the total plasticizer content of the polymer layer and the total plasticizer content between adjacent polymer layers may belong to one of the above ranges or More. When the inner layer is a multilayer inner layer, one or more of the polymer layers may include two or more plasticizers. In some embodiments, when the inner layer is a multilayer inner layer, at least one of the polymer layers including the blend of plasticizers may have a glass transition higher than the glass transition temperature of the conventional plasticized polymer layer. temperature. In some cases, this may provide additional stiffness for layers that may be used, for example, as an outer "sheet" layer in a multilayer inner layer. For example, in some embodiments, at least one of the layers of the multilayer inner layer may comprise at least one poly(vinyl butyral) resin and a blend of two or more plasticizers to plasticize the polymer layer The agent content is one or more of the above ranges. In some embodiments, the total plasticizer content can be less than about 45 phr, less than about 40 phr, less than about 38 phr, less than about 35 phr, or less than about 30 phr, and the glass transition temperature of the polymer layer can be at least about 32. ° C, at least about 33 ° C, at least about 34 ° C, at least about 35 ° C, at least about 36 ° C, at least about 37 ° C, at least about 38 ° C, at least about 39 ° C, at least about 40 ° C, at least 45 ° C. The poly(vinyl butyral) resin used in the layer may optionally have a higher residual hydroxyl content, such as greater than 19% by weight, greater than 19.5% by weight, greater than 20% by weight, or greater than 20.5% by weight of residual hydroxyl content, or The layer can have a residual hydroxyl content, a glass transition temperature, or a total plasticizer content as described in one or more of the ranges herein. In addition to the plasticizer, it is also contemplated that an adhesion control agent ("ACA") may be added to the polymer resin to form the inner polymer layer. ACA is often used to change the adhesion to the inner layer. The ACAs covered include, but are not limited to, ACA, residual sodium acetate, potassium acetate, and/or bis(2-ethyl butyrate) magnesium salts disclosed in U.S. Patent No. 5,728,472. Other additives may be incorporated into the inner layer to promote its effectiveness in the final product, and certain other properties are imparted to the inner layer. Such additives include, but are not limited to, dyes, pigments, stabilizers (eg, UV stabilizers), antioxidants, antiblockers, flame retardants, IR absorbers or blockers (eg, indium tin oxide, antimony tin oxide) , lanthanum hexaboride (LaB₆ And cerium oxide), processing aids, flow enhancing additives, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents , coupling agents, adhesives, primers, reinforcing additives and fillers, as well as other additives known to those skilled in the art. One parameter used to describe the polymeric resin component of the inner polymer layer of the present application is the residual hydroxyl content (in the form of a vinyl hydroxyl content or a poly(vinyl alcohol) ("PVOH") content). The residual hydroxyl content refers to the amount of hydroxyl groups remaining in the form of pendant groups on the polymer chain after completion of the treatment. For example, PVB can be made by hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol) and then reacting poly(vinyl alcohol) with butyraldehyde to form PVB. In the process of hydrolyzing poly(vinyl acetate), typically not all acetate pendant groups are converted to hydroxyl groups. Additionally, the reaction with butyraldehyde will generally not convert all of the hydroxyl groups to acetal groups. Thus, in any final PVB, there will typically be residual acetate groups (such as vinyl acetate groups) and residual hydroxyl groups (such as vinyl hydroxyl groups) in the form of pendant groups on the polymer chain. In general, the residual hydroxyl content of the polymer can be adjusted by controlling the reaction time and reactant concentration as well as other variables in the polymer manufacturing process. When used herein as a parameter, the residual hydroxyl content is measured in % by weight according to ASTM D-1396. In various embodiments, the poly(vinyl butyral) resin comprises from about 8 to about 35 weight percent (wt. %) residual hydroxyl groups calculated as PVOH, from about 13 to about 30 weight percent residual hydroxyl groups calculated as PVOH, calculated as PVOH From about 8 to about 22 weight percent residual hydroxyl groups or from about 15 to about 22 weight percent residual hydroxyl groups as calculated from PVOH; and for some of the highly rigid inner layers disclosed herein, for one or more of the layers, poly(vinyl butyl) The acetal resin comprises greater than about 19 weight percent residual hydroxyl groups calculated as PVOH, greater than about 20 weight percent residual hydroxyl groups calculated as PVOH, greater than about 20.4 weight percent residual hydroxyl groups calculated as PVOH, and greater than about 21 weight percent residual hydroxyl groups calculated as PVOH. In some embodiments, the poly(vinyl butyral) resin used for at least one polymer layer of the inner layer may comprise a poly(vinyl butyral) resin having a residual hydroxyl content as measured as described above. : at least about 18% by weight, at least about 18.5% by weight, at least about 18.7% by weight, at least about 19% by weight, at least about 19.5% by weight, at least about 20% by weight, at least about 20.5% by weight, at least about 21% by weight, at least About 21.5 wt%, at least about 22 wt%, at least about 22.5 wt%, and/or no more than about 30 wt%, no more than about 29 wt%, no more than about 28 wt%, no more than about 27 wt%, no more than about 26% by weight, no more than about 25% by weight, no more than about 24% by weight, no more than about 23% by weight or no more than about 22% by weight. Additionally, one or more other polymer layers in the inner layer described herein may include another poly(vinyl butyral) resin having a lower residual hydroxyl content. For example, in some embodiments, at least one polymer layer of the inner layer can comprise a poly(vinyl butyral) resin having a residual hydroxyl content as measured as described above: at least about 8% by weight, at least About 8.5% by weight, at least about 9% by weight, at least about 9.5% by weight, at least about 10% by weight, at least about 10.5% by weight, at least about 11% by weight, at least about 11.5% by weight, at least about 12% by weight, at least about 13 % by weight and/or no more than about 16% by weight, no more than about 15% by weight, no more than about 14% by weight, no more than about 13.5% by weight, no more than about 13% by weight, no more than about 12% by weight or no more than about 11.5% by weight. When the inner layer comprises two or more polymer layers, the layers may comprise poly(vinyl butyral) resins having substantially the same residual hydroxyl content, or poly(vinyl butyral) resins in each layer The residual hydroxyl content can vary from one another. When two or more layers comprise a poly(vinyl butyral) resin having substantially the same residual hydroxyl content, the difference between the residual hydroxyl content of the poly(vinyl butyral) resin in each layer may be less than About 2% by weight, less than about 1% by weight, or less than about 0.5% by weight. As used herein, the terms "weight percent different" and "the difference between ... is at least ... weight percent" are meant to be subtracted from a number. Go to the difference between the other two calculated weights. For example, a poly(vinyl acetal) resin having a residual hydroxyl group content of 12% by weight has a residual hydroxyl content of 2% by weight different from a poly(vinyl acetal) resin having a residual hydroxyl group content of 14% by weight (14) Weight%-12% by weight = 2% by weight). As used herein, the term "different" may refer to a value above or below another value. Unless otherwise stated, all &quot;difference&quot; herein refers to the value of the difference and does not refer to the particular sign of the value resulting from the order in which the number is subtracted. Therefore, unless otherwise mentioned, all "differences" herein mean the absolute value of the difference between two numbers. When two or more layers include a poly(vinyl butyral) resin having a different residual hydroxyl group content, the difference between the residual hydroxyl content of the poly(vinyl butyral) resin may be as described above. At least about 2% by weight, at least about 3% by weight, at least about 4% by weight, at least about 5% by weight, at least about 6% by weight, at least about 7% by weight, at least about 8% by weight, at least about 9% by weight, At least about 10% by weight, at least about 12% by weight, at least about 15% by weight. The resin may also comprise less than 35% by weight of residual ester groups, less than 30% by weight, less than 25% by weight, less than 15% by weight, less than 13% by weight, less than 11% by weight, less than, calculated as polyvinyl ester (eg, acetate) 9% by weight, less than 7% by weight, less than 5% by weight or less than 1% by weight of residual ester groups, the remainder being acetals, preferably butyraldehyde acetals, but optionally including minor amounts of other acetal groups, For example, a 2-ethylhexanal group (see, for example, U.S. Patent No. 5,137,954, the disclosure of which is incorporated herein by reference in its entirety). The residual acetate content of the resin can also be determined in accordance with ASTM D-1396. In some embodiments, the residual acetate content of the at least one poly(vinyl acetal) resin can be measured as described above to be at least about 1% by weight, at least about 3% by weight, at least about 5% by weight, at least About 7% by weight and/or no more than about 15% by weight, no more than about 12% by weight, no more than about 10% by weight, and no more than about 8% by weight. When the inner layer comprises a plurality of inner layers, the two or more polymer layers may comprise a resin having substantially the same residual acetate content, or one or more of the various layers may have substantially different acetic acid Ester content. When the residual acetate content of the two or more resins is substantially the same, the difference in residual acetate content can be, for example, less than about 3% by weight, less than about 2% by weight, less than about 1% by weight, or less than about 0.5% by weight. In some embodiments, the difference in residual acetate content between two or more poly(vinyl butyral) resins in the multilayer inner layer can be at least about 3% by weight, at least about 5% by weight, At least about 8% by weight, at least about 15% by weight, at least about 20% by weight, or at least about 30% by weight. When the resins are used in a multilayer inner layer, resins having different residual acetate contents may be located in adjacent polymer layers. When the multilayer inner layer is a three-layer inner layer comprising a pair of outer "sheet" layers surrounding or sandwiching the inner "core" layer, for example, the core layer may comprise a resin having a higher or lower residual acetate content. At the same time, the resin in the inner core layer may have a residual hydroxyl content above or below the residual hydroxyl content of the outer skin layer and is within one or more of the ranges previously provided. When combined with at least one plasticizer, the poly(vinyl acetal) resin having a higher or lower residual hydroxyl content and/or residual acetate content may also ultimately include different amounts of plasticizer. Thus, layers or regions formed from first and second poly(vinyl acetal) resins having different compositions may also have different properties within a single polymer layer or inner layer. It is worth noting that for the type of plasticizer to be applied, the compatibility of the plasticizer in the polymer is primarily determined by the hydroxyl content of the polymer. Polymers having a relatively large residual hydroxyl content are generally associated with reduced plasticizer compatibility or capacity. Conversely, polymers with lower residual hydroxyl content will generally result in increased plasticizer compatibility or capacity. Therefore, poly(vinyl acetal) resins having a higher residual hydroxyl content tend to be less plasticized and exhibit a higher hardness than similar resins having a lower residual hydroxyl content. Conversely, when plasticized with a plasticizer is applied, a poly(vinyl acetal) resin having a lower residual hydroxyl content may tend to incorporate a higher amount of plasticizer, thereby obtaining A soft polymer layer that exhibits a lower glass transition temperature than a similar resin having a higher residual hydroxyl content. Depending on the particular resin and plasticizer, these tendencies can be reversed. When two poly(vinyl acetal) resins having different levels of residual hydroxyl groups are blended with the plasticizer, the plasticizer can be distributed between the polymer layers or regions, so that more plasticizer can exist. In layers or regions having a lower residual hydroxyl content, and less plasticizer may be present in the layer or region having a higher residual hydroxyl content. Finally, an equilibrium is achieved between the two resins. In general, this correlation between the residual hydroxyl content of the polymer and the plasticizer compatibility/capacity is steerable and allows for the addition of a suitable amount of plasticizer to the polymer resin and stable maintenance within the multilayer. The difference in the amount of plasticizer in the layer. This correlation also helps to stably maintain the difference in plasticizer content between two or more resins as the plasticizer will otherwise migrate between the resins. Due to the migration of the plasticizer in the inner layer, the glass transition temperatures of the one or more polymer layers can be different when measured separately or as part of a multilayer inner layer. In some embodiments, the inner layer can comprise at least one polymer layer having an outer glass transition temperature of at least about 33 ° C, at least about 34 ° C, at least about 35 ° C, at least about 36, at least about 37 ° C, At least about 38 ° C, at least about 39 ° C, at least about 40 ° C, at least about 41 ° C, at least about 42 ° C, at least about 43 ° C, at least about 44 ° C, at least about 45 ° C, or at least about 46 ° C. In some embodiments, the glass transition temperature of the same layer can be at least about 34 ° C, at least about 35 ° C, at least about 36 ° C, at least about 37 ° C, at least about 38 ° C, at least about 39 ° C, at least within the polymer layer. About 40 ° C, at least about 41 ° C, at least about 42 ° C, at least about 43 ° C, at least about 44 ° C, at least about 45 ° C, at least about 46 ° C, at least about 47 ° C. In the same or other embodiments, when the inner layer is not part of the inner layer, the glass transition temperature of at least one other polymer layer of the multilayer inner layer may be less than 30 ° C, and the glass transition temperature may be, for example, no more than about 25 ° C, no more than about 20 ° C, no more than about 15 ° C, no more than about 10 ° C, no more than about 9 ° C, no more than about 8 ° C, no more than about 7 ° C, no more than about 6 ° C, no more than about 5 ° C No more than about 4 ° C, no more than about 3 ° C, no more than about 2 ° C, no more than about 1 ° C, no more than about 0 ° C, no more than about -1 ° C, no more than about -2 ° C or no more than about -5 °C. When measured outside the inner layer, the glass transition temperature of the same polymer layer may be no more than about 25 ° C, no more than about 20 ° C, no more than about 15 ° C, no more than about 10 ° C, no more than about 9 ° C, no More than about 8 ° C, no more than about 7 ° C, no more than about 6 ° C, no more than about 5 ° C, no more than about 4 ° C, no more than about 3 ° C, no more than about 2 ° C, no more than about 1 ° C or no more than about 0 ° C. According to some embodiments, the difference between the glass transition temperatures of the two polymer layers, typically the adjacent polymer layers within the inner layer, can be at least about 5 ° C, at least about 10 ° C, at least about 15 ° C, at least about 20 °C, at least about 25 ° C, at least about 30 ° C, at least about 35 ° C, at least about 35 ° C, at least about 35 ° C, while in other embodiments, the glass transition temperatures of the two or more polymer layers are different from each other. The value can be at about 5 ° C, about 3 ° C, about 2 ° C or about 1 ° C. In general, the lower glass transition temperature layer has a lower hardness than the higher or higher glass transition temperature layer in the inner layer and may be between the higher glass transition temperature polymer layers in the final inner layer configuration. For example, in some embodiments of the present application, the increased acoustic attenuation properties of the soft layer are combined with the mechanical strength of the rigid/rigid layer to create a multilayer inner layer. In these embodiments, the central soft layer is sandwiched between two rigid/rigid outer layers. This (hard) / / (soft) / / (hard) configuration results in a multi-layered inner layer that is easy to handle, can be used in conventional lamination methods, and can be constructed with relatively thin and light layers. The soft layer is typically characterized by a lower residual hydroxyl content (eg, less than or equal to 16% by weight, less than or equal to 15% by weight, or less than or equal to 12% by weight or more of the disclosed ranges), higher plasticization An agent content (eg, greater than or equal to about 48 phr, or greater than or equal to about 70 phr, or any of the ranges disclosed above) and/or a lower glass transition temperature (eg, less than 30 ° C or less than 10 ° C or more) Reveal any of the scopes). It is contemplated that the polymeric inner layer sheets as described herein can be prepared by any suitable method known in the art for preparing polymeric inner layer sheets that can be used in multilayer sheets, such as glass laminates. For example, it is contemplated that the polymer inner layer sheet may be via solution casting, compression molding, injection molding, melt extrusion, meltblowing, or conventional techniques for preparing and manufacturing polymeric inner sheets. Any other program known to form. In addition, in embodiments utilizing a multi-polymer inner layer, it is contemplated that such multi-polymer inner layers may be co-extruded, blown film, dip coated, solution coated, knife coated, paddle coated, air knife Coating, printing, powder coating, spraying or other methods known to those skilled in the art are formed. While the methods for preparing the polymeric inner sheet described herein cover as much as possible all methods known to those skilled in the art for preparing polymeric inner sheets, the present application will focus on extrusion and A polymer inner sheet prepared by a co-extrusion process. The final multilayer glass ply articles of the present invention are formed using methods known in the art. In general, in most of its basic meaning, extrusion is the method used to establish the target of a fixed cross-sectional profile. This is accomplished by pushing or extracting the material through a mold for the desired cross section of the final product. In the extrusion process, the thermoplastic resin and plasticizer, including any of the above resins and plasticizers, are typically premixed and fed into the extruder apparatus. Additives such as coloring agents and UV inhibitors (in the form of liquids, powders or pellets) are often used and can be incorporated into the thermoplastic resin or plasticizer before reaching the extruder apparatus. These additives are incorporated into the thermoplastic polymer resin and related polymeric inner layer sheets to enhance certain properties of the polymer inner layer sheets and their effectiveness in the final multilayer glass sheet product. In the extruder apparatus, particles of a thermoplastic raw material and a plasticizer (including any of the above-mentioned resins, plasticizers, and other additives) are further mixed and melted, thereby obtaining a temperature and composition as a whole. The melt. When the melt reaches the end of the extruder unit, the melt is pushed into the extruder die. The extruder die is a component of a thermoplastic extrusion process that provides its profile to the final polymer inner laminate product. In general, the mold is designed such that the melt flows uniformly out of the cylindrical profile exiting the mold and becomes the final contour shape of the product. As long as a continuous profile is present, a plurality of shapes can be imparted to the final polymer inner layer sheet by the mold. It is to be noted that, for the purpose of the present application, the inner layer of the polymer in a state after the extrusion of the mold to form a continuous contour of the melt will be referred to as "polymer melt sheet". At this stage in the process, the extrusion die has imparted a specific profile shape to the thermoplastic resin, thus forming a polymer melt sheet. The polymer melt flakes are highly viscous throughout the overall molten state and in the overall molten molten state. In the polymer melt flakes, the melt has not cooled to a temperature at which the flakes are completely "set" overall. Thus, after the polymer melt flakes exit the extrusion die, the next step in the currently used thermoplastic extrusion process is to cool the polymer melt flakes with a cooling device. Cooling elements used in previously employed methods include, but are not limited to, sprayers, fans, cooling slots, and chill rolls. The cooling step is used to transform the polymer melt flakes into polymer inner layer flakes having a generally uniform non-melting cooling temperature. This polymer inner sheet is not in a molten state and is not highly viscous compared to a polymer melt sheet. Specifically, it is a shaped final form of cooled polymer inner sheet product. For purposes of this application, the shaped and cooled inner polymer layer will be referred to as a "polymer inner layer sheet." In some embodiments of the extrusion process, a co-extrusion process can be utilized. Co-extrusion is a method of simultaneously extruding multiple layers of a polymeric material. In general, this type of extrusion utilizes two or more extruders to melt and deliver a stable volumetric delivery of different thermoplastic melts having different viscosities or other properties to pass through a co-extrusion die. The final form of the need. The thickness of the multi-polymer layer exiting the extrusion die in the coextrusion process can generally be controlled by adjusting the relative speed of the melt through the extrusion die and by adjusting the individual extruder dimensions of each molten thermoplastic resin material. . According to some embodiments, the multilayer inner layer may have a total thickness of at least about 13 mils, at least about 20 mils, at least about 25 mils, at least about 27 mils, at least about 30 mils, at least about 31 mils, and/or Or no more than about 75 mils, no more than about 70 mils, no more than about 65 mils, no more than about 60 mils, or it may be from about 13 to about 75 mils, from about 25 to about 70 mils or about 30 to 60 mils. When the inner layer comprises two or more polymer layers, each of the layers may have a thickness of at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, At least about 6 mils, at least about 7 mils, at least about 8 mils, at least about 9 mils, at least about 10 mils, and/or no more than about 50 mils, no more than about 40 mils, no more than about 30 The mil, no more than about 20 mils, no more than about 17 mils, no more than about 15 mils, no more than about 13 mils, no more than about 12 mils, no more than about 10 mils, no more than about 9 mils. ear. In some embodiments, each of the layers can have about the same thickness, while in other embodiments, one or more of the layers can have a different thickness than one or more of the other layers within the inner layer. In some embodiments, wherein the inner layer comprises at least three polymer layers, one or more of the inner layers may be relatively thin compared to other outer layers. For example, in some embodiments, wherein the plurality of inner layers are three inner layers, the innermost layer may have a thickness of no more than about 12 mils, no more than about 10 mils, no more than about 9 mils, no more than about 8 The mil, no more than about 7 mils, no more than about 6 mils, no more than about 5 mils, or it can have from about 2 to about 12 mils, from about 3 to about 10 mils, or from about 4 to about 9 Thickness in the mil range. In the same or other embodiments, each of the outer layers can have a thickness of at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 7 mils, and/or no more than about 15 mils. No more than about 13 mils, no more than about 12 mils, no more than about 10 mils, no more than about 9 mils, no more than about 8 mils, or from about 2 to about 15 mils, about 3 to Approximately 13 mils or from about 4 to about 10 mils. When the inner layer comprises two outer layers, the combined thickness of the layers can be at least about 9 mils, at least about 13 mils, at least about 15 mils, at least about 16 mils, at least about 18 mils, at least about 20 mils, at least about 23 mils, at least about 25 mils, at least about 26 mils, at least about 28 mils or at least about 30 mils and/or no more than about 73 mils, no more than about 60 mils, Not more than about 50 mils, no more than about 45 mils, no more than about 40 mils, no more than about 35 mils, or from about 9 to about 70 mils, from about 13 to about 40 mils, or from about 25 to about Within 35 mils. According to some embodiments, the thickness ratio of one of the outer layers and one of the inner layers in the multilayer inner layer may be at least about 1.4:1, at least about 1.5:1, at least about 1.8:1, at least about 2: 1. At least about 2.5:1, at least about 2.75:1, at least about 3:1, at least about 3.25:1, at least about 3.5:1, at least about 3.75:1, or at least about 4:1. When the inner layer is a three-layer inner layer having an inner core layer disposed between a pair of outer skin layers, the ratio of the thickness of one of the skin layers to the thickness of the core layer may fall within one or more of the above ranges. In some embodiments, the ratio of the combined thickness of the outer layer to the thickness of the inner layer can be at least about 2.25:1, at least about 2.4:1, at least about 2.5:1, at least about 2.8:1, at least about 3:1, at least About 3.5:1, at least about 4:1, at least about 4.5:1, at least about 5:1, at least about 5.5:1, at least about 6:1, at least about 6.5:1, or at least about 7:1 and/or not More than about 30:1, no more than about 20:1, no more than about 15:1, no more than about 10:1, no more than about 9:1, no more than about 8:1. The multilayer inner layer as described herein can comprise a generally planar inner layer having substantially the same thickness along the length or the longest dimension and/or width or the second longest dimension of the sheet. In some embodiments, however, the multilayer inner layer of the present invention can be a wedge or wedge shaped inner layer comprising at least one wedge shaped region having a wedge shaped profile. The wedge inner layer has an altered thickness profile along at least a portion of the length and/or width of the sheet such that, for example, at least one edge of the inner layer has a thickness greater than the other edge. When the inner layer is a wedge inner layer, at least one, at least two, at least three, at least four or more individual resin layers may include at least one wedge-shaped region. The wedge inner layer can be particularly useful in head-up display (HUD) panels such as in automotive and aircraft applications. Turning now to Figures 1-8, several embodiments of a wedge-shaped inner layer in accordance with the present invention are provided. 1 is a cross-sectional view of an exemplary wedge-shaped inner layer including wedge-shaped regions of different thicknesses. As shown in Figure 1, the wedge-shaped region has a minimum thickness T measured at the first boundary of the wedge-shaped region._Min And the maximum thickness T measured at the second boundary of the wedge region_Max . In some embodiments, T_Min It can be at least about 0.25 mm, at least about 0.40 mm, at least about 0.60 mm, or at least about 0.76 mm (mm) and/or no more than 1.2 mm, no more than about 1.1 mm, or no more than about 1.0 mm. In addition, T_Min It can be in the range of 0.25 to 1.2 mm, 0.40 to 1.1 mm or 0.60 to 1.0 mm. In some embodiments, T_Max It can be at least about 0.38 mm, at least about 0.53 mm, or at least about 0.76 mm and/or no more than 2.2 mm, no more than about 2.1 mm, or no more than about 2.0 mm. In addition, T_Max It can be in the range of 0.38 to 2.2 mm, 0.53 to 2.1 mm or 0.76 to 2.0 mm. In some embodiments, T_Max With T_Min The difference between the two may be at least about 0.13 mm, at least about 0.15 mm, at least about 0.20 mm, at least about 0.25 mm, at least about 0.30 mm, at least about 0.35 mm, at least about 0.40 mm, and/or no more than 1.2 mm, More than about 0.90 mm, no more than about 0.85 mm, no more than about 0.80 mm, no more than about 0.75 mm, no more than about 0.70 mm, no more than about 0.65 mm, or no more than about 0.60 mm. In addition, T_Max With T_Min The difference between the two can be in the range of 0.13 to 1.2 mm, 0.25 to 0.75 mm or 0.40 to 0.60 mm. In some embodiments, the distance between the first boundary and the second boundary of the wedge-shaped region (ie, the "wedge region width") can be at least about 5 centimeters, at least about 10 centimeters, at least about 15 centimeters, at least about 20 The centimeters are at least about 30 centimeters (cm) and/or no more than about 200 cm, no more than about 150 cm, no more than about 125 cm, no more than about 100 cm, or no more than about 75 cm. In addition, the wedge-shaped region may have a width in the range of 5 to 200 cm, 15 to 125 cm, or 30 to 75 cm. As shown in Figure 1, the wedge inner layer includes opposing first and second outer end edges. In some embodiments, the distance between the first and second outer end edges (ie, the "inner layer width") can be at least about 20 cm, at least about 40 cm, or at least about 60 cm, and/or no more than about 400 cm, no more than about 200 cm or no more than about 100 cm. In addition, the inner layer width may be in the range of 20 to 400 cm, 40 to 200 cm, or 60 to 100 cm. In the embodiment depicted in Figure 1, the first and second boundaries of the wedge region are spaced inwardly from the first and second outer end edges of the inner layer. In these embodiments, only a portion of the inner layer is wedge shaped. When the wedge region forms only a portion of the inner layer, the ratio of the inner layer width to the wedge region width may be at least about 0.05:1, at least about 0.10:1, at least about 0.20:1, at least about 0.30:1, at least about 0.40:1. At least about 0.50:1, at least about 0.60:1 or at least about 0.70:1 and/or no more than about 1:1, no more than about 0.95:1, no more than about 0.90:1, no more than about 0.80:1 or no. More than about 0.70:1. Additionally, the ratio of the width of the inner layer to the width of the wedge region may range from 0.05:1 to 1:1 or 0.30:1 to 0.90:1. In an alternative embodiment, discussed below, the entire inner layer is wedge shaped. When the entire inner layer is wedge-shaped, the width of the wedge-shaped region is equal to the width of the inner layer, and the first and second boundaries of the wedge-shaped region are respectively located at the first and second end edges. As shown in Figure 1, the wedge-shaped region of the inner layer has a wedge angle (Ѳ) defined as the inner layer that intersects the first (upper) surface of the inner layer extending across the boundaries of the first and second wedge-shaped regions. The first reference line of the two points forms an angle with a second reference line extending through the two points at which the first and second wedge-shaped area boundaries intersect the second (lower) surface of the inner layer. In some embodiments, the wedge region may have a wedge angle of at least about 0.10 milliradians (mrad), at least about 0.13 milliradians, at least about 0.15 milliradians, at least about 0.20 milliradians, at least about 0.25 milliradians, at least about 0.30. Milli-radians, at least about 0.35 milliradians or at least about 0.40 milliradians (mrad) and/or no more than about 1.2 mrad, no more than about 1.0 mrad, no more than about 0.90 mrad, no more than about 0.85 mrad, no more than about 0.80 mrad, No more than about 0.75 mrad, no more than about 0.70 mrad, no more than about 0.65 mrad or no more than about 0.60 mrad. In addition, the wedge angle of the wedge-shaped region may be in the range of 0.10 to 1.2 mrad, 0.13 to 1.0 mrad, 0.25 to 0.75 mrad, or 0.40 to 0.60 mrad. When the first and second surfaces of the wedge-shaped region are each flat, the wedge angle of the wedge-shaped region is only the angle between the first (upper) and second (lower) surfaces. However, as discussed in further detail below, in certain embodiments, the wedge shaped region can include at least one variable angular region having a curved thickness profile and a continuous different wedge angle. Additionally, in certain embodiments, the wedge shaped region can include two or more constant angle regions, wherein the constant angular regions each have a linear thickness profile, but at least two of the constant angular regions have different wedge angles. 2 through 7 illustrate various wedge inner layers configured in accordance with an embodiment of the present invention. 2 depicts an inner layer 20 that includes a wedge-shaped region 22 that extends completely from a first end edge 24a of the inner layer 20 to a second end edge 24b of the inner layer 20. In this configuration, the first and second boundaries of the wedge region are located at the first and second end edges 24a, 24b of the inner layer. The entire wedge-shaped region 22 of the inner layer 20 depicted in FIG. 2 has a constant wedge angle 仅为 that is only the angle formed between the flat first (upper) and second (lower) flat surfaces of the inner layer 20. FIG. 3 illustrates an inner layer 30 that includes a wedge shaped region 32 and a flat edge region 33. The first boundary 35a of the wedge-shaped region 32 is located at the first end edge 34a of the inner layer 30, while the second boundary 35b of the wedge-shaped region 32 is located where the wedge-shaped region 32 meets the flat edge region 33. The wedge region 32 includes a constant angle region 36 and a variable angle region 37. The constant angle region 36 has a linear thickness profile and a constant wedge angle Ѳ_c At the same time, the variable angle region 37 has a curved thickness profile and a continuously varying wedge angle. The starting wedge angle of the variable angle region 37 is equal to the constant wedge angle Ѳ_c And the end wedge angle of the variable angle region 37 is zero. The inner layer 30 depicted in FIG. 3 has a constant wedge angle greater than the total wedge angle of the entire wedge region 32._c . Figure 4 illustrates an inner layer 40 comprising a wedge shaped region 42 between the first and second flat edge regions 43a, 43b. The first boundary 45a of the wedge-shaped region 42 is located at a position where the wedge-shaped region 42 meets the first flat edge region 43a, while the second boundary 45b of the wedge-shaped region 42 is located at a position where the wedge-shaped region 42 is in contact with the second flat edge region 43b. The wedge region 42 includes a constant angle region 46 between the first and second variable angle regions 47a, 47b. The first variable angle region 47a forms a transition region between the first flat edge region 43a and the constant angle region 46. The second variable angle region 47b forms a transition region between the second flat edge region 43b and the constant angle region 46. The constant angle region 46 has a linear thickness profile and a constant wedge angle Ѳ_c At the same time, the first and second variable angle regions 47a, 47b have a curved thickness profile and a continuously varying wedge angle. The starting wedge angle of the first variable angle region 47a is equal to zero and the ending wedge angle of the first variable angle region 47b is equal to the constant wedge angle Ѳ_c . The starting wedge angle of the second variable angle region 47b is equal to the constant wedge angle Ѳ_c And the end wedge angle of the second variable angle region 47b is zero. The inner layer 40 depicted in FIG. 4 has a constant wedge angle greater than the total wedge angle of the entire wedge region 42._c . Figure 5 illustrates an inner layer 50 comprising a wedge shaped region 52 between the first and second flat edge regions 53a, 53b. The wedge-shaped region 52 of the inner layer 50 does not include a constant angle region. Specifically, the entire wedge-shaped region 52 of the inner layer 50 is a variable angle region having a curved thickness profile and a continuously varying wedge angle. As described above, the total wedge angle of the wedge region 52 is measured as two of the first (second) surfaces of the inner layer 50 that are joined to the first and second boundaries 55a, 55b extending through the wedge region 52. A second reference line "A" of the point and a second reference line "B" extending through the first and second boundaries 55a, 55b of the wedge-shaped region 52 and the second (lower) surface of the inner layer 50 Between the angles. However, within the wedge region 52, the curved thickness profile provides an infinite number of wedge angles that may be greater than, less than, or equal to the total wedge angle 整个 of the entire wedge region 52. Figure 6 illustrates the inner layer 60 that does not include any flat end portions. Specifically, the wedge-shaped region 62 of the inner layer 60 forms the entire inner layer 60. Thus, the first and second boundaries 65a, 65b of the wedge region 60 are located at the first and second end edges 64a, 64b of the inner layer 60. The wedge shaped region 62 of the inner layer 60 includes first, second and third constant angle regions 46a-c separated by first and second variable angle regions 47a, 47b. The first, second, and third constant angle regions 46a-c each have a linear thickness profile and each have a unique first, second, and third constant wedge angle, respectively_C1 Ѳ_C2 Ѳ_C3 . The first variable angle region 47a serves as a transition region between the first and second constant angle regions 46a, 46b. The second variable angle region 47b serves as a transition region between the second and third constant angle regions 46b, 46c. As discussed above, the total wedge angle of the wedge region 62 is measured as the angle between the first reference line "A" and the second reference line "B". First constant wedge angle_C1 Less than the total wedge angle 楔 of the wedge region 62. Second constant wedge angle_C2 Greater than the total wedge angle 楔 of the wedge region 62. Third constant wedge angle_C3 Less than the total wedge angle 楔 of the wedge region 62. The wedge angle of the first variable angle region 47a is from the first constant wedge angle Ѳ_C1 To the second constant wedge angleѲ_C2 Continuous increase. The wedge angle of the second variable angle region 47b is from the second constant wedge angle Ѳ_C2 To the third wedge angle_C3 Continuous reduction. Figure 7 illustrates an inner layer 70 that includes a wedge shaped region 72 between the first and second flat edge regions 73a, 73b. The first and second boundaries 75a, 75b of the wedge region 72 are spaced inwardly from the first and second outer edges 74a, 74b of the inner layer 70. The wedge-shaped region 72 of the inner layer 70 includes first, second, third, and fourth variable angle regions 77a-d and first, second, and third constant angle regions 76a-c. The first variable angle region 77a serves as a transition region between the first flat edge region 73a and the first constant angle region 76a. The second variable angle region 77b serves as a transition region between the first constant angle region 76a and the second constant angle region 76b. The third variable angle region 77c serves as a transition region between the second constant angle region 76b and the third constant angle region 76c. The fourth variable angle region 77d serves as a transition region between the third constant angle region 76c and the second flat edge region 73b. The first, second, and third constant angle regions 76a-c each have a linear thickness profile and each have a unique first, second, and third constant wedge angle, respectively_C1 Ѳ_C2 Ѳ_C3 . As discussed above, the first, second, third, and fourth variable angle regions 77a-d have wedge angles that continuously transition from a wedge angle of a constant angle region on one side of the variable angle region 77 to a variable The wedge angle of the constant angle region on the other side of the angular region 77. As discussed above, the wedge inner layer can include one or more constant angle wedge shaped regions each having a width that is less than the total width of the entire wedge shaped region. Each wedge region may have a wedge angle that is the same or different than the total wedge angle of the entire wedge region. For example, the wedge shaped region can include one, two, three, four, five or more constant angle wedge shaped regions. When multiple constant angle wedge regions are employed, the constant angle wedge regions may be separated from one another by variable angle wedge regions for transitioning between adjacent constant angle wedge regions. In certain embodiments, each constant angle wedge region can have a width of at least about 2 cm, at least about 5 cm, at least about 10 cm, at least about 15 cm, or at least about 20 cm, and/or no more than about 150 cm, not More than about 100 cm or no more than about 50 cm. In some embodiments, the ratio of the width of each constant angle wedge region to the total width of the entire wedge region can be at least about 0.1:1, at least about 0.2:1, at least about 0.3:1, or at least about 0.4:1 and / Or no more than about 0.9:1, no more than about 0.8:1, no more than about 0.7:1, no more than about 0.6:1 or no more than about 0.5:1. In certain embodiments, each constant angle wedge region may have a wedge angle of at least about 0.13 mrad, at least about 0.15 mrad, at least about 0.20 mrad, at least about 0.25 mrad, at least about 0.30 mrad, at least about 0.35 mrad, at least about 0.40. Mrad and/or no more than about 1.2 mrad, no more than about 1.0 mrad, no more than about 0.90 mrad, no more than about 0.85 mrad, no more than about 0.80 mrad, no more than about 0.75 mrad, no more than about 0.70 mrad, no more than about 0.65 Mrad or no more than about 0.60 mrad. Additionally, the wedge angle of each constant angle wedge region may range from 0.13 to 1.2 mrad, 0.25 to 0.75 mrad, or 0.40 to 0.60 mrad. In certain embodiments, the wedge angle of the at least one constant angle wedge region is at least about 0.01 mrad greater than the total wedge angle of the entire wedge region, at least about 0.05 mrad, at least about 0.10 mrad, at least about 0.20 mrad, at least about 0.30 mrad, or At least about 0.40 mrad. In certain embodiments, the wedge angle of the at least one constant angle wedge region is at least about 0.01 mrad, at least about 0.05 mrad, at least about 0.10 mrad, at least about 0.20 mrad, at least about 0.30 mrad, or less than the total wedge angle of the entire wedge region. At least about 0.40 mrad. In certain embodiments, the wedge angle of the at least one constant angle wedge region is no more than about 0.40 mrad, no more than about 0.30 mrad, no more than about 0.20 mrad, no more than about 0.10 mrad, no more than the total wedge angle of the entire wedge region. More than about 0.05 mrad or no more than about 0.01 mrad. In certain embodiments, the wedge angle of the at least one constant angle wedge region is less than about 0.40 mrad, no more than about 0.30 mrad, no more than about 0.20 mrad, no more than about 0.10 mrad, no more than the total wedge angle of the entire wedge region. More than about 0.05 mrad or no more than about 0.01 mrad. Figures 8a and 8b illustrate an inner layer 80 having a thickness profile similar to inner layer 30 of Figure 3. The inner layer 80 of Figures 8a and 8b is configured for use by a vehicle windshield that secures the inner layer between two glass sheets. As depicted in Figure 8a, the first end edge 84a of the inner layer 80 can be located at the bottom of the windshield while the second end edge 84b of the inner layer 80 can be located at the top of the windshield. The wedge-shaped region 82 of the inner layer 80 is positioned in the windshield region at the location where the heads-up display is located. The wedge shaped region 82 of the inner layer 80 includes a constant angle region 86 and a variable angle region 87. As depicted in Figure 8a, in some embodiments, the wedge-shaped region 82 extends completely across the inner layer 80 between the first side edge 88a and the second side edge 88b of the inner layer 80. Figure 8b, which is similar to Figure 3, shows the thickness profile of the inner layer 80 between the bottom of the windshield and the top of the windshield. As described above, the inner layer of the present invention can be used as a single layer sheet or a multilayer sheet. In various embodiments, the inner layer of the invention (as a single layer sheet or as a multilayer sheet) can be incorporated into a multilayer board and most often disposed between two substrates. The two substrates of the disclosed multilayer board may be constructed of glass, plastic or any other applicable substrate known for use in making multilayer boards, but are most often constructed of glass. Examples of such structures will be: (glass) / / (inner layer) / / (glass). In one embodiment where the substrate is comprised of glass, the glass is expected to be annealed, thermally strengthened, or tempered. Additionally, the two substrates may have the same thickness (eg, 2 mm and 2 mm) or may have asymmetric thicknesses (eg, 1.5 mm and 2.5 mm). The combined thickness of the plates is defined as 4.0 mm or less. In one embodiment, the combined thickness of the substrate for the multi-layer glass sheet will be 3.7 mm or less for use in panels for windshield applications, 3.7 mm or less for use in side and back windows The board used is 4.0 mm or less for use in panels for skylight applications. In some embodiments, the combined thickness of the glass sheets or other rigid substrates used to form the multilayer board can be less than 3.95 mm, less than 3.85 mm, less than 3.75 mm, less than 3.65 mm, less than 3.5 mm, less than 3 mm, or less than 2.5 mm. The thickness of at least one or two substrates may be less than 2.1 mm, less than 2.0 mm, less than 1.9 mm, less than 1.8 mm, less than 1.7 mm, less than 1.6 mm, or less than 1.5 mm. Without intending to be limited to any theory of operation or mechanism, even in embodiments where the panel has a reduced glass thickness via an asymmetric or symmetrical configuration, the multilayer glass sheet has improved strength for this purpose within the multilayer board. The layer contributes to the overall strength of the board. This is due to the fact that the inner layer of high hardness in the multilayer board provides significant film stress to the maximum flexural rigidity under bending. The inclusion of an inner layer having a high hardness in the disclosed multilayer board produces a multilayer board having a strength greater than that of a conventional inner layer having a substrate of the same type and thickness. This is due to the fact that the inner layer of the disclosed multilayer sheet contributes more to the overall strength and stiffness of the panel than the conventional inner layer. Therefore, contrary to the conventional knowledge, the thickness of the multilayer board can be reduced without reducing the strength of the board. For the purposes of the present invention, conventional inner layers such as the conventional PVB (designated "known inner layer" or "practical PVB") are inner layers containing a single layer or a monolithic inner layer, such as a monolithic PVB. The inner layer exhibits a glass transition temperature of about 30 °C. Conventional PVB can be as followstable 1 The indicated PVB resin and plasticizer content were prepared. Conventional PVB can also be made with PVB resins having different hydroxyl contents and different levels of plasticizer to meet the glass transition temperature of about 30 °C. A conventional acoustic multilayer inner layer such as a conventional acoustic multilayer PVB inner layer (designated "President Acoustic PVB") is comprised of at least one conventional PVB layer (ie, conventional PVB) and at least one soft or acoustic PVB layer (presentation) Inner layer of glass transition temperature less than 30 °C. Glass layer articles using the inner layer of the present invention can be prepared by known procedures. The inner polymer layer and the glass are assembled and heated to a glass temperature of about 25 ° C to 60 ° C, and then the captured air is discharged through a pair of nip rolls to form an assembly. The press assembly is then heated to a temperature of between about 70 ° C and 120 ° C, for example by infrared radiation or in a convection oven. The assembly is then passed through a second pair of nip rolls, followed by high pressure processing of the assembly at about 130 ° C to 150 ° C and about 1,000 to 2,000 kPa (kPa) for about 30 minutes. The methods disclosed in the non-high pressure methods, such as those disclosed in U.S. Patent No. 5,536,347, the disclosure of which is incorporated herein in Additionally, in addition to nip rolls, other means known in the art and commercially implemented for degassing the inner-glass interface include vacuum bags and vacuum ring methods in which air is removed using a vacuum. To aid in understanding the inner layer of the present invention, it is also useful to understand the properties and characteristics associated with the inner layer of the polymer and the formulas used to measure such properties and characteristics of the inner layer of the polymer. A quantitative way to determine the contribution of a PVB inner layer having a high hardness to the overall strength and stiffness of a multilayer board is "deflection hardness." The deflection stiffness is determined by a three point bending method of edge strength, hardness, flexural modulus, and mechanical stiffness of the test panel. In this method, a polymeric inner layer test sheet is laminated between two substrates to form a sheet. In one embodiment, a polymeric inner layer test sheet having a thickness of about 0.76 millimeters is laminated between two sheets of glass each having a thickness of 2.3 millimeters, a width of 2.54 centimeters, and a length of 30.5 centimeters. The thicknesses, widths, and lengths of the inner layer and the glass are merely illustrative and not limiting. For example, different glass thicknesses and configurations (eg, asymmetry) are also typically tested using a three point bending method. After the lamination cycle, the plates were then conditioned for one to two hours in a constant humidity (50%) and temperature (23 °C) environment prior to being subjected to the bending test. In this test, two fixed supports spaced 19.0 cm apart were applied to the underside of the panel. A third point, a cylindrical rod having a diameter of 0.953 cm and a length of 5.08 cm was applied to the plate substantially at the center of the plate. Next, a force was applied to the third point to produce a constant speed of about 1.27 mm/min on the test panel. A diagram of an embodiment of the three point bend test is provided in FIG. Record the load value on the test board (measured in Newtons N) and the deflection value of the test panel (measured in centimeters). As seen in Figure 10, this equivalent is then plotted against each other to determine the hardness of the laminate (deflection hardness, measured in N/cm), which is equal to the load relative to the surface before the glass breaks or the load drops significantly. The deflection of the plate, that is, the average load divided by the average slope of the line produced by the corresponding deflection before the rupture or load is significantly reduced. In some embodiments, the multilayer panels constructed in accordance with the present invention may have a deflection hardness of at least about 225 N/cm, at least about 240 N/cm, at least about 250 N/cm, at least about 265 N, as measured as described above. /cm, at least about 275 N/cm, at least about 280 N/cm, at least about 300 N/cm, at least about 310 N/cm, at least about 325 N/cm, at least about 350 N/cm. Another key performance indicator for multi-layer glass laminates is penetration resistance. Penetration resistance is typically determined by a 2.27 kg (5 lb.) drop ball test where the average rupture height (MBH) can be measured. Penetration resistance can be measured by a step method. Automotive windshields used in vehicles in the United States must pass the minimum penetration resistance specifications found in ANSI Z26.1 (80% pass at 12°). In other countries of the world, similar rules need to be met. There are also specific rule requirements for laminated glass in architectural applications in the United States and Europe, where minimum penetration resistance must be met. The step method utilizes an impact tower, which can be dropped from a shock tower to a 30.5 cm x 30.5 cm sample at various heights. MBH is defined as 50% of the sample will hold the ball and 50% will allow the ball to penetrate the height of the ball. The test laminate is supported horizontally in a support frame similar to that described in the ANSI Z26.1 rule. The environmental chamber is used to adjust the laminate to the desired test temperature if necessary. The test was carried out by supporting the sample in a support frame and dropping the ball from the height of the expected MBH onto the laminate sample. If the ball penetrates the laminate, the result is recorded as a failure, and if the ball is supported (ie, does not penetrate the sample), the result is recorded as a hold. If the result is held, the method is repeated from a drop height of 0.5 m above the previous test. If the result is a failure, repeat the method at a drop height of 0.5 m below the previous test. Repeat this procedure until all test samples have been used. The results are then tabulated and the % retention at each drop height is calculated. These results are then graphically represented as % retention versus height, and a line representing the best fit of the data is plotted on the graph. The MBH can then be read from the graph at a point where the % retention is 50%. In general, ten to twelve samples are used for testing to generate individual MBH data points. Samples were laminated using 2.3 mm thick clear glass (available from Pittsburgh Glass Works, Pennsylvania) and subjected to high pressure processing using the conditions described herein. As used herein, the disclosed MBH data was obtained using the above method at a temperature of 23 °C. In some embodiments, a multi-layer sheet as described herein can have an MBH of at least about 4.5 m, at least about 5.0 m, at least about 5.5 m, as measured by a stepwise method. In other embodiments, the panels may have an MBH of less than 5.5 m, although this value may not be applicable to windshields and other applications requiring high impact strength. For windshield applications, MBH of 5.5 m or higher at 23 °C is considered acceptable for minimum penetration to meet the temperature range specified in the ANSI Z26.1 rule and in the laws or standards of the rest of the world. Permeability. The multilayer board of the present invention can exhibit enhanced acoustic performance as evidenced by, for example, higher sound transmission losses. Overall, the sound transmission losses exhibited by the plates configured in accordance with embodiments of the present invention are all unexpected at the coincident frequencies of the rigid substrates and as a weighted average across the coincident frequency regions, especially for having 4.0 mm or more. Small or in combination with a substrate thickness in any of the ranges provided above. In general, boards made from thinner substrates and harder polymer layers tend to exhibit poorer sound performance. However, multi-layer boards configured in accordance with embodiments of the present invention, even those comprising thinner substrates and/or harder polymer layers, have similarities to those formed from softer inner layers and/or thicker substrates. Multilayer boards or better sound transmission losses. The acoustic attenuation as used to characterize a glass laminate comprised of the multilayer inner layer of the present invention is determined by the sound transmission loss at a frequency corresponding to the coincidence frequency of the reference monolithic glass sheet of 4.8 mm (3/16 inch) thickness. For the purposes of the present invention, "coincidence frequency" means that the board exhibits a frequency at which the sound transmission loss decreases due to the "coincidence effect". The coincidence frequency can be expressed by the following equation:f _c =c ² /2π ́ [ρ _s /B]^1/2 , among themc For the speed of sound in the air,ρ _s It is the surface density of the glass plate, and B is the bending hardness of the glass plate. In general, the coincidence frequency increases as the thickness of the glass sheet decreases. Reference plate coincidence frequency (f_c ) is usually in the range of 2,000 to 6,000 Hz and can be evaluated by the following algorithm:Where "d" is the total glass thickness in millimeters and "f"_c In Hertz. For a reference plate having a fixed size and a laminate/multilayer plate of the present invention, sound transmission reduction (i.e., loss of sound transmission) is measured according to ASTM E90 (05) at a fixed temperature of 20 °C. The test board has a length of 80 cm and a width of 50 cm, and the thickness of the reference plate and the combined thickness of the glass for the multilayer inner layer aretable 2 Indicated in the middle. The reference plate (4.8 mm monolithic glass) has a measured coincidence frequency of 3,150 Hz. Sound transmission loss (TL) at the reference frequency of the conventional board and the board of the present invention_Ref ) shown in Table 2. In addition to reduced sound transmission at the reference frequency (TL_Ref In addition, in some embodiments, the board's sound transmission is reduced at the coincidence frequency of the board (TL)_c ) is also used to characterize the sound performance of the board. In addition to sound transmission loss at coincidence frequency (TL_c In addition, the sound performance of the multi-layer board can also be determined by measuring the weighted average sound transmission loss (TL) measured in the coincidence frequency region._w ) characterization. Weighted average sound transmission loss across a multi-layer board with a frequency range (TL_w ) is available from the following equation:Where TL _i Transmission loss measured for each 1/3 octave band in the desired frequency region at a fixed temperature of 20 ° C according to ASTM E-90 (05)i Range from 1 tok And wherek Corresponds to the number of 1/3 octave bands. In one embodiment, when weighted average sound transmission loss (TL_w When measuring across 2,000 and 8,000 Hz in the frequency region,k Is 7. In general, an inner layer or board with a higher sound transmission loss at a coincident frequency and/or a higher weighted average sound transmission loss will have a lower sound transmission loss than a coincident frequency (TL)_c And/or lower weighted average sound transmission loss (TL)_w The board has better acoustic performance. Sound transmission loss at the coincidence frequency provided by this paper (TL_c Value and weighted average sound transmission loss (TL_w The values were obtained using a test glass plate of 50 cm x 80 cm with two 2.3 mm clear glass sheets and an inner layer of interest. In various embodiments of the invention, when laminated between two glass sheets, the multilayer inner layer exhibits the same reduction in sound transmission as the conventional acoustic inner layer, wherein sound transmission loss (TL)_Ref ) Overall greater than 35 decibels (dB) and greater than 36 dB. In other embodiments of the invention, the multilayer inner layer exhibits the same reduction in sound transmission as the conventional acoustic inner layer when laminated between two glass sheets, wherein the sound transmission loss (TL)_Ref ) Overall greater than approximately 39 dB. In some embodiments, the sound transmission loss (TL) at the coincidence frequency of the inner layer described herein_c The measurement as described above may be at least about 35 dB, at least about 36 dB, at least about 36.5 dB, at least about 37 dB, at least about 37.5 dB, at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least About 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, or at least about 42 dB. In the same or other embodiments, the weighted average sound transmission loss (TL) of the inner layer across the 2,000 to 8,000 Hz frequency range is described herein._w The measurement as described above may be at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, at least Approximately 42 dB, at least approximately 42.5 dB. In some embodiments, the inner layer of the present invention can have, for example, an inner "core" layer having a glass transition temperature of less than 9 ° C and a thickness of less than 9 mils, but when combined in a thickness of no more than about 4.0 mm, no more than about 3.9 mm, When laminated between two glass sheets of no more than about 3.8 mm, no more than about 3.7 mm, or no more than about 3.6 mm, the inner layer can exhibit sound transmission loss (TL) at each of the measurement coincidence frequencies as described above._c ) is at least about 35 dB, at least about 36 dB, at least about 36.5 dB, at least about 37 dB, at least about 37.5 dB, at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, at least about 42 dB, and/or weighted average sound transmission loss (TL)_w ) is at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, at least about 42 dB, at least about 42.5 dB. The inner layers may have a core layer glass transition temperature, equivalent glass transition temperature (T, for example, within one or more ranges provided herein)_Eq ), internal layer thickness and / or deflection hardness. In some embodiments, the enhanced acoustic performance of the inner layers and/or sheets described herein can unexpectedly be combined with an inner layer having a polymer layer that is harder than many conventional acoustic inner layers or sheets. For example, in some embodiments, the TL exhibiting within the above range_c And/or TL_w The inner layer may have an average shear storage modulus (G') measured at 1/3 octave band frequency across 2,000 and 8,000 Hz as described above, and may also be at least about 150 MPa, at least about 155 MPa, at least About 160 MPa, at least about 165 MPa, at least about 170 MPa, at least about 175 MPa, at least about 180 MPa, at least 190 MPa. In some embodiments, the inner layer of the present invention may have a deflection hardness or an average fracture height within the above range, but may still exhibit a measurement of sound transmission loss at a coincidence frequency as described above._c ) is at least about 35 dB, at least about 36 dB, at least about 36.5 dB, at least about 37 dB, at least about 37.5 dB, at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, at least about 42 dB, and/or weighted average sound transmission loss (TL)_w ) is at least about 38 dB, at least about 38.5 dB, at least about 39 dB, at least about 39.5 dB, at least about 40 dB, at least about 40.5 dB, at least about 41 dB, at least about 41.5 dB, at least about 42 dB, or at least about 42.5 dB. This combination of properties is also possible even with, for example, a thinner, lower glass transition temperature core layer having a thickness of less than 9 mils. In some embodiments, the harder skin layer can have a combined thickness of at least about 15 mils, at least about 20 mils, at least about 23 mils, or at least about 25 mils. The glass transition temperature is also used to describe the inner layer of the polymer of the present invention. Glass transfer temperature (T_g ) Determined by dynamic mechanical analysis (DMA). DMA measurement varies with temperature at a given frequency and temperature sweep rate. Pascal storage (elastic) modulus (G') in Pascals, loss (viscosity) modulus in Pascals (G) ''), loss (damping) factor (LF) [tan(δ)]. However, when the sample temperature was raised from -20 ° C to 70 ° C at a rate of 2 ° C/min, the polymer sheet samples were tested in shear mode at an oscillation frequency of 1 Hz. Then T_g Determined by the position of the loss factor peak on the temperature scale in °C. In order to further define a multilayer inner layer comprising at least one high hardness layer and one acoustic attenuation layer, the equivalent glass transition temperature of the inner layer is used (T_Eq ). Equivalent glass transition temperature of the above two layers (T_Eq )defined as:Where T_G1 Glass transition temperature for high rigidity layers, w₁ For the thickness of the high rigidity layer, T_G2 Transfer temperature to the glass of the acoustic attenuation layer, and w₂ The thickness of the acoustic attenuation layer. For a multilayer inner layer comprising an additional layer and a high hardness layer and an acoustic attenuating layer, the equivalent glass transition temperature is defined as the sum of the glass transition temperatures of the layers multiplied by the thickness of the corresponding layer, and the total thickness of the inner layer is divided by this sum. In one embodiment, the equivalent glass transition temperature of the inner layer of the invention (T_Eq ) may be at least about 26 ° C, at least about 26.5 ° C, at least about 27 ° C, at least about 27.5 ° C, at least about 28 ° C, at least about 28.5 ° C, at least about 29 ° C, at least about 29.5 ° C, at least about 30 ° C, at least about 30.5 ° C, at least about 31 ° C, at least about 31.5 ° C, at least about 32 ° C, at least about 32.5 ° C, at least about 33 ° C or at least about 33.5 ° C. Equivalent glass transition temperature of the inner layer (T_Eq The measurement as described above may also be no more than about 75 ° C, no more than about 60 ° C, no more than about 45 ° C, no more than about 42 ° C, no more than about 40 ° C or no more than about 38 ° C. In some embodiments, the equivalent glass transition temperature of the inner layer (T_Eq ) may range from about 26 ° C to about 75 ° C, from about 27 ° C to about 60 ° C, from about 28 ° C to about 45 ° C, or from about 29 ° C to about 42 ° C. According to an embodiment of the invention, having an equivalent glass transition temperature (T as described herein)_Eq The inner layer can have a total thickness and individual layers having a thickness within the ranges provided above. It is possible to have an equivalent glass transition temperature (T) in one or more of the above ranges compared to conventional plates._Eq The inner layer can be used for multilayer boards having a reduced thickness. For example, in some embodiments, having at least about 26 ° C, at least about 26.5 ° C, at least about 27 ° C, at least about 27.5 ° C, at least about 28 ° C, at least about 28.5 ° C, at least about 29 ° C, at least about 29.5 ° C An equivalent glass transition temperature of at least about 30 ° C, at least about 30.5 ° C, at least about 31 ° C, at least about 31.5 ° C, at least about 32 ° C, at least about 32.5 ° C, at least about 33 ° C, or at least about 33.5 ° C (T_Eq The inner layer can be used for a multilayer board comprising a pair of rigid substrates having a combined thickness of no more than about 4.0 mm, no more than about 3.9 mm, no more than about 3.8 mm, no more than about 3.7 mm, no more than about 3.6 mm. No more than about 3.5 mm. In some embodiments, each of the substrates can have the same thickness, while in other embodiments, one of the substrates can have a different thickness than the other. The inner layer, as configured above, may exhibit enhanced acoustic performance despite enhanced impact strength and thinner substrate thickness, as described by TL above._c And/or TL_w Shown. In addition, the enhanced acoustic performance is also likely to be associated with a thinner soft core layer such as a core layer having a maximum thickness of no more than 9 mils.Instance Instance 1 Multilayer boards with different glass configuration thicknesses are disclosed with a highly rigid inner layer monolithic (ie single layer) inner layer having an inner layer thickness of about 0.76 mm (designated as "hard PVB-1" and "hard PVB-2" And astable 1 Shown in the structure). Similarly, acoustic monolithic layers for multi-layer boards with different glass configuration thicknesses (designated as "soft PVB" and astable 1 (presented) and a conventional inner layer having an inner layer thickness of about 0.76 mm (designated as "known PVB" and astable 1 Shown in the structure). All multilayer glass sheets were subjected to a three point bending test method to determine the deflection hardness.table 1 As can be seen from the results in Table 1, the "hard PVB" inner layer of the present invention has a high contribution to the hardness of the multilayer board when compared with the conventional or soft inner layer. In fact, a multilayer board with the disclosed hard or highly rigid inner layer (ie, "hard PVB") will result in a multilayered board having a deflection hardness ratio that has the same thickness and glass configuration but a conventional (non-rigid) inner layer. Multilayer boards are at least 20% taller. Table 1 further shows that the plasticizer content contributes to the hardness of the inner layer of the polymer. As seen in Table 1, polymer inner layer sheets having a plasticizer content of 30 phr or less are associated with a higher level of deflection hardness, and the lower the percentage of plasticizer in the inner layer of the polymer, the harder the inner layer. Thus, the plasticizer content can be used as a parameter to generate and identify the inner layer of the harder polymer. Table 1 also shows that, in addition to the plasticizer content, the deflection hardness of the multilayer board is directly related to the glass transition temperature of the PVB inner layer in the multilayer board. The larger the glass transition temperature of the PVB inner layer, the greater the bending hardness of the multilayer board. . This correlation is further illustrated in Figure 11, which depicts the deflection hardness of the inner layer from Table 1 versus glass transition temperature and glass configuration. Figure 11 also shows that the deflection stiffness is greatly affected by the nature of the inner layer sandwiched between the substrates. In addition, Figure 11 shows that the deflection hardness of the inner layer for each of the glass configurations has a significant deflection point relative to the glass transition temperature and occurs at about 33 °C. Above this temperature, the deflection hardness of the multilayer board is increased more rapidly at a temperature of 33 ° C or higher than 33 ° C than at a temperature lower than 33 ° C. Therefore, the PVB inner layer having a glass transition temperature of about 33 ° C or higher results in an inner layer having high rigidity/hardness. In contrast, the conventional PVB inner layer generally has a glass transition temperature of 30 °C. The effect of the disclosed inner layer on deflection stiffness can be further illustrated in FIG. In particular, Figure 11 shows that by using the disclosed highly rigid inner layer, the glass thickness can be effectively reduced while maintaining the same deflection stiffness. This can be demonstrated using the following method as shown in FIG. The horizontal line (long dashed line) is drawn from the point indicating that the 2.1/2.1 glass thickness configuration and the conventional PVB inner layer (ie, the glass transition temperature is 30 ° C) are drawn until the horizontal line is configured for the 2.1/1.6 glass. The deflection hardness intersects the glass transition temperature curve. Corresponding temperature (T_G2 ) was obtained from the intersection. This temperature of about 33.8 ° C corresponds to the rigid PVB inner layer in a plate with a 2.1/1.6 glass configuration, the deflection hardness of the plate has a 2.1/2.1 glass configuration and has a conventional PVB (ie 30 ° C) The boards are equal. In other words, with a 2.1/1.6 glass configuration and a glass transition temperature of T_G2 The plate of the PVB inner layer (33.8 °C) will have a deflection hardness equal to that of a plate having a 2.1/2.1 glass configuration and a conventional PVB inner layer. The long dashed line is then drawn vertically upward from the intersection of the 2.1/1.6 deflection hardness curve until the perpendicular intersects the deflection hardness curve of the 2.1/2.1 glass configuration. The deflection hardness corresponding to the intersection at the 2.1/2.1 glass deflection hardness curve was determined to be about 390 N/cm. Therefore, when in the same glass configuration (ie 2.1/2.1), the plate with the PVB inner layer with a glass transition temperature of 33.8 °C will be compared to the plate with the conventional PVB inner layer (deflection hardness 318 N/cm). Hard about 22.6%. The above procedure can be applied to a 2.3/2.3 glass plate having a conventional inner layer. As shown in Figure 11, a 2.3/2.3 glass sheet having a conventional inner layer has a deflection hardness of about 373 N/cm. The horizontal line (short dashed line in Figure 11) is then drawn to the point where the line intersects the 2.1/2.1 glass plate to determine the glass transition temperature of the revealed inner layer (i.e., T_G1 = 33.4 ° C). As can be seen, the deflection hardness corresponding to the disclosed inner layer (i.e., the glass transition temperature of 33.4 ° C) in the 2.3/2.3 plate was about 470 N/cm (as shown by the short dashed line in Figure 3). Thus, the disclosed inner layer will contribute an additional 26% to the total deflection stiffness of the panel (i.e., 470 N/cm compared to 373 N/cm). Figure 12 depicts the tempered glass from Table 1 versus the combined glass thickness of the inner layer. This figure further demonstrates the effect of the disclosed inner layer on the deflection stiffness of the multilayer board. As clearly shown in Figure 12, the rigid PVB-1 contributes to the deflection hardness of the multilayer sheet in such a way that the deflection hardness of the lightweight glass sheet (i.e., the total combined glass thickness is 3.7 mm) is substantially equal to 4.6 mm. Combine glass thickness and heavier multilayer boards with conventional PVB inner layers. Thus, a multi-layered board with a rigid PVB-1 can reduce the thickness of the glass by up to 0.9 mm or the glass by 19.6% by weight, while maintaining the same, compared to a multi-layered board with a conventional PVB inner layer and a 4.6 mm combined glass thickness. Hardness and mechanical stiffness.Instance 2 In another embodiment of the present application, a plurality of inner layers having a highly rigid layer are also incorporated into the multilayer board. For example, in addition to two substrates having a combined thickness of 4.0 mm or less and a rigid PVB layer (ie, a PVB layer having a glass transition temperature of at least 33 ° C), the lightweight multilayer board may further comprise a presentation ratio than conventional PVB. The glass transition temperature of the PVB layer (ie, the second PVB layer) is significantly lower at the glass transition temperature. In an embodiment, this second PVB layer will have a glass transition temperature of 15 ° C or less. This additional PVB layer with a lower glass transition temperature is included to improve the acoustic attenuation (i.e., reduced sound) of the multilayer board. Table 2 provides a number of examples of the disclosed multilayer inner layer construction (designated "inner layer 1-8") for various glass configurations (to form multilayer glass sheets of various thicknesses). The "informative acoustic PVB" inner layer refers to the conventional acoustic inner layer previously utilized. All multilayer inner layers were subjected to a three point bending method to determine the deflection hardness. Table 3 provides the compositions and characteristics shown in Table 2. Figure 5 provides the deflection hardness and equivalent glass transition temperature (T based on the information provided in Table 2)._Eq A graphical illustration of the relationship.table 2 table 3 As shown in Table 2, the high-rigidity layers (layers 1 and 3) of the multilayer inner layers 2-8 contribute to the deflection hardness of the multilayer board, which in this way enables a lightweight glass configuration (ie, a combined glass thickness of 3.7 mm). The deflection hardness is substantially equal to the heavier multilayer board having the conventional multilayer inner layer (designated as "conventional acoustic PVB") (ie, the combined glass thickness is 4.2 mm). Therefore, when compared with the conventional multilayer inner layer When compared to the previously used multilayer board, the multilayer board comprising the disclosed multilayer inner layer (ie, the inner layer 2-8, wherein the high rigidity PVB layer (layer 1 and layer 3) and the acoustically attenuating inner layer (layer 2)) It can reduce the thickness of the glass by up to 0.5 mm or the glass by 11.9%. In addition, lightweight laminates comprising multiple layers of inner layers having a high degree of rigidity maintain the same hardness, mechanical stiffness and acoustic properties as the heavy, previously utilized multilayer panels having conventional acoustic inner layers. Table 2 also shows the deflection hardness of the multilayer inner layer to the equivalent glass transition temperature (T_Eq Dependence). Increase the equivalent glass transition temperature of the inner layer (T_Eq Increase the deflection hardness. Obviously there is an equivalent glass transition temperature (T_Eq A panel having an inner layer of at least 28.5 ° C and higher has a modified deflection hardness that is better than a panel having a conventional acoustic PVB inner layer. It should be noted that although the inner layer-1 provides improved deflection stiffness over conventional acoustic PVB, its acoustic attenuation is significantly lower and is not desirable for applications requiring acoustic attenuation. Thus, a multilayer inner layer with significantly reduced acoustic attenuation, such as inner layer-1, is generally poor.Instance 3 Several additional polymer layers (PVB-12 to PVB-25) are mixed and melt blended with different residual hydroxyl content (which has varying amounts of plasticizer triethylene glycol bis(2-ethylhexanoate) Or a variety of poly(vinyl butyral) resins of 3-GEH). The residual hydroxyl content of the resin and the plasticizer content of each polymer layer are summarized in Table 4 below. The glass transition temperatures of the various polymer layers were determined as described above and the results are provided in Table 4. The several polymer layers listed in Table 4 above were used to form the comparative inner layers (CI-1 and CI-2) and the disclosed inner layers (DI-1 to DI-14) as shown in Table 5 below. Several properties of these inner layers, including equivalent glass transition temperatures (T_Eq ), transmission loss at coincidence frequency (TL_c And the average rupture height (MBH) was determined according to the methods described previously, and the results are summarized in Table 5. Although not desirable, it is desirable to have a laminate having an average fracture height of at least 5.5 m, especially for windshield applications. A comparison of the inner layer CI-1 and the disclosed inner layers CI-1 to DI-3 is then used to construct a plurality of multilayer sheets having different glass thicknesses. The configuration of each board is summarized in Table 6 below. The deflection stiffness of each panel was then determined according to the three point bending tests previously described, and the results are provided in Table 6. As shown in Tables 5 and 6 above, comparing the inner layer CI-1 and the comparison inner layer CI-2 each exhibits a sound transmission loss of 39 dB at the coincidence frequency (TL)._c And an average fracture height greater than 5.5 m, which would be considered acceptable for most windshield applications. However, the low equivalent glass transition temperature of these inner layers combined with the low deflection hardness of the plate (T_Eq ) indicates that if used with thinner glass sheets, these inner layers will run poorly. However, when combined with thinner glass sheets to form a multilayer board, the several disclosed inner layers shown in Tables 5 and 6 do exhibit the same as the equivalent glass transition temperature (T)._Eq And the average rupture height (MBH) shows sufficient strength and stiffness, as well as loss of sound transmission by coincidence frequency (TL)_c ) is suitable for acoustic performance. For example, the disclosed inner layers DI-1, DI-4 to DI-6, DI-8, DI-11 and DI-12, and DI-14 to DI-16 will each have an equivalent glass transition greater than 26 °C. Temperature (T_Eq And an average rupture height (MBH) greater than 5.5 m, and also a loss of sound transmission at a coincident frequency greater than 35 dB (TL)_c ). In addition, also shown in Tables 5 and 6 above, the thickness of the individual polymer layers used to construct the multilayer inner layer may also affect the effectiveness of the multilayer board. For example, the thickness of the inner "core" layer and/or the combined thickness of the outer "sheet" layer have an effect on the sound performance and overall strength and stiffness of the inner layer and the final multilayer board. For example, as shown by comparison of inner layers DI-1 to DI-3 and DI-8 to DI-10 as disclosed in Tables 5 and 6 above, the core layer thickness is from 5 mils (DI-1 and The addition of DI-8) to 20 mils (DI-3 and DI-10) resulted in an overall improvement in acoustic performance, as demonstrated by an increase in sound transmission loss from 34 dB to 38 dB. However, as the thickness of the core layer increases as the combined thickness of the skin layer decreases overall, the resulting sheet can exhibit reduced impact performance, such as by reducing MBH, for example, by revealing inner layers DI-3 and DI-10 (< 5.5 m). Shown, or exhibited reduced deflection stiffness given to the glass configuration, as shown by comparison of inner layers DI-1 to DI-3 as disclosed in Table 6. In addition, several multilayer boards each having a different glass configuration were constructed using the inner layer samples of the inner layers DI-14 and DI-15 disclosed in Table 5. The deflection stiffness of each of these panels was then determined according to the three point bend tests previously described, and the results are provided in Table 7. As shown in Tables 5 and 7 above, the disclosed inner layers DI-14 and DI-15 have the same core layer thickness (5 mils), the same core layer glass transition temperature (-3 ° C) and the same surface glass transition temperature ( 40 ° C). However, as shown in Table 7, the total thickness of the inner layer DI-14 disclosed is less than 4 mils less than the total thickness of the disclosed inner layer DI-15, as shown by Table 5, which has a ratio of the inner layer DI disclosed. The combined surface thickness of the combined surface layer thickness of -15 is obtained by revealing the inner layer DI-14. Therefore, the equivalent glass transition temperature of DI-15 (T_Eq ) 0.8 ° C high. However, when comparing the deflection tensities of the two panels, it was found that for the specified glass configuration, the deflection hardness of the panel formed using the disclosed inner layer DI-15 was higher than the deflection hardness of the panel formed by the disclosed inner layer DI-14. More than 15%. Thus, the combined thickness of the outer skin layer can have an effect on the deflection stiffness of the panel with the inner layer.Instance 4 Several poly(vinyl butyral) resins are combined with varying amounts of plasticizer to form a polymer layer which is then used to form additional comparative inner layers (CI-3 to CI-5) as shown in Table 8a and The inner layer (DI-17 to DI-22) is disclosed. Each of the disclosed inner layers CI-3 to CI-5 was formulated with a poly(vinyl butyral) resin and a plasticizer 3-GEH, while the inner layer disclosed was only 3-GEH (plasticizer A). It is formulated or formulated with 3-GEH blended with another plasticizer, nonylphenyltetraethylene glycol (plasticizer B). Residues for each of the poly(vinyl butyral) resins used to compare the surface layers and core layers of each of the inner layers CI-3 to CI-5 and the disclosed inner layers DI-17 to DI-22 The hydroxyl content and the type and amount of plasticizer used for each layer are summarized in Table 8a. The glass transition temperatures of the individual polymer layers were measured separately and in the inner layer according to the procedures previously described and the results are also provided in Table 8b. The inner layers CI-3 to CI-5 each have a surface layer and a core layer which are formed of the same poly(vinyl butyral) resin and have the same plasticizer content but different core layer thicknesses. As shown in Tables 8a and 8b, the thicker core layer of CI-5 (7 mils) resulted in a higher inner plasticizer than the inner layer CI-3 and CI-4 with a thinner core layer. Content (44 phr) and lower inner glass transition temperature (1 ° C) of the core layer. This is due to the composite effect, which increases the glass transition temperature of the various layers within the inner layer. As shown in Table 8a, the disclosed inner layers DI-17 to DI-21 also include the same poly(vinyl butyral) resin and include the same amount as each other and the comparative inner layers CI-3 to CI-5. The core layer of plasticizer. However, as shown in Table 8b, the disclosed inner layers DI-17 and DI-21 include a skin layer having a higher glass transition temperature than the skin layer used to compare the inner layers CI-3 to CI-5, and includes, for example, the following Polymer layer: a poly(vinyl butyral) resin with a higher residual hydroxyl content (DI-18 and DI-21), a blend of plasticizers (DI-17); or a higher residual hydroxyl content A blend of poly(vinyl butyral) and a plasticizer (DI-19 and DI-20). Therefore, the surface layer used in the disclosed inner layers DI-17 to DI-22 has a glass transition temperature of between 2 ° C and 8 ° C higher than the glass transition temperature of the surface layers of the comparative inner layers CI-3 to CI-5. In addition, a 1/3 octave band in the 2000-8000 Hz frequency range for forming each of the inner layers CI-3 to CI-5 and the revealed inner layers DI-17 to DI-22 is determined. The shear storage modulus (G') under each of them is provided and the results are provided in Table 9 below. As shown in Table 9, the surface layers of the disclosed inner layers DI-17 to DI-22 have a comparison of each of the inner layers CI-3 to CI-5 in each of the one-third octave bands. Higher shear storage modulus (G'). Additionally, the average shear storage modulus (G') of each of the disclosed inner layers DI-17 through DI-22 is at least 10 MPa higher than the comparative inner layer. Subsequently, several glass plates with a 2.3 mm glass//inner layer//2.3 mm glass configuration were used as described in Example 2 above to compare the inner layers CI-3 to CI-5 and the disclosed inner layers DI-17 to DI. Sample preparation of -22. The sound transmission loss of each of the obtained comparison plates CG-1 to CG-3 and the obtained disclosed plates DG-1 to DG-6 was measured at 20 ° C according to ASTM E90 (09). The results are provided in Table 10 below, including sound transmission loss for each of the 1/3 octave bands in the frequency range of 2000-8000 Hz, and sound transmission loss at the coincidence frequency (TL)_c And weighted average sound transmission loss (TL_w ). As shown by the comparison plates CG-1 to CG-3 in Table 10 above, comparing the thickness variations of the core layers in the multilayer inner layer has little effect to no effect on the sound transmission loss through the plates. For example, as shown in Table 10, the comparative plate CG-1 having a core thickness of 2 mils has substantially the same dimensions as the comparison plates CG-2 and CG-3 having a core layer thickness of 4.5 mils and 7 mils, respectively. Sound transmission loss at coincidence frequency (TL_c And weighted average sound transmission loss (TL_w ). However, as shown by panels DG-1 through DG-5 as disclosed in Table 10, for example, with an inner layer having a thickness similar to that of the disclosed panels DG-1 through DG-5 but utilizing a softer skin layer Compared to the comparison plate CG-2, the plate formed by the inner layer having the generally harder skin layer results in enhanced sound transmission loss. Although the present invention has been described in connection with the embodiments of the present invention, the present invention is intended to be illustrative, and is not intended to limit the scope of the invention. As will be understood by those skilled in the art, the present invention encompasses embodiments other than the embodiments described in detail herein. Modifications and variations of the described embodiments can be made without departing from the spirit and scope of the invention. It will be further understood that any one of the ranges, values or characteristics imparted by any single component of the invention, as it is compatible, as given throughout, may be combined with another component of the invention. Any range, value or characteristic given by either of them is used interchangeably, thereby forming an embodiment in which each of the components has a defined value. For example, a polymer layer containing a plasticizer content in any of the given ranges and a range of residual hydroxyl content can be formed, as appropriate, thereby forming Within the scope of the invention, there are many arrangements that will be very cumbersome.

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A‧‧‧ first reference line
B‧‧‧Second reference lineѲ‧‧‧Wedge angle _c ‧‧‧ Constant wedge angle _c1 ‧‧‧First constant wedge angle _c2 ‧‧‧Second constant wedge angle _c3 ‧‧‧ Third constant Wedge angle

1 is a cross-sectional view of a wedge-shaped inner layer configured in accordance with one embodiment of the present invention, with various features for marking the inner layer of the wedge for ease of reference. 2 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over the entire width of the inner layer, wherein the entire wedge-shaped region has a constant wedge angle and a linear thickness profile. 3 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over a portion of the inner layer and a flat edge region extending over a portion of the inner layer, wherein the wedge-shaped region includes a constant angle region and a variable angular region. 4 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over a portion of the inner layer and two flat edge regions extending over a portion of the inner layer, wherein the wedge-shaped region includes a constant angle region and two variable regions Angle area. Figure 5 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over a portion of the inner layer and two flat edge regions extending over a portion of the inner layer, wherein the wedge-shaped region is completely variable by having a curved thickness profile The angle area is formed. Figure 6 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over the entire width of the inner layer, wherein the wedge-shaped region includes three constant angular regions that are spaced apart from one another by two variable angular regions. Figure 7 is a cross-sectional view of a wedge-shaped inner layer having a wedge-shaped region extending over a portion of the inner layer and two flat edge regions extending over a portion of the inner layer, wherein the wedge-shaped region includes three constant-angle regions and four Variable angle area. Figure 8a is a plan view of a wedge-shaped inner layer for a vehicle windshield configuration, wherein the thickness profile of the inner layer is similar to the thickness profile of the inner layer depicted in Figure 2. Figure 8b is a cross-sectional view of the inner layer of Figure 8a showing the thickness profile of the inner layer. Figure 9 is a diagram showing three point bending test and test equipment of the embodiment. Figure 10 provides a graph of load versus test deflection for a test sheet in a three point bend test. Figure 11 provides a graph showing the dependence of the glass transition temperature of the inner layer on the hardness of the multilayer board. Figure 12 provides a graph showing the correlation of various plate thicknesses to improve the hardness of the disclosed multilayer sheets. Figure 13 is a graph showing the relationship between the equivalent glass transition temperature (T _eq ) and the deflection hardness of various comparison plates and disclosed panels.

Claims (30)

A multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; a second polymer layer adjacent to and in contact with the first polymer layer Wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticizer; and a third polymerization comprising a third poly(vinyl butyral) resin and at least one plasticizer a layer of the second polymer layer adjacent to and in contact with the first and third polymer layers, wherein the second poly(vinyl butyral) resin has a first poly(vinyl condensate) The residual hydroxyl content of the aldehyde) resin and/or the third poly(vinyl butyral) resin differs by at least 7% by weight of the residual hydroxyl group, wherein the second polymer layer has a glass transition temperature of less than 9 ° C and does not exceed A maximum thickness of 9 mils, wherein at least one of the first polymer layer and the third polymer layer has a glass transition temperature of at least 33 ° C and a thickness greater than 13 mils. The inner layer of claim 1, wherein the residual hydroxyl content of the first poly(vinyl butyral) resin is greater than 19% by weight and/or the plasticizer content of the first polymer layer is less than 35 phr. The inner layer of claim 1, wherein the total combined thickness of the first and third polymeric layers is at least 20 mils. The inner layer of claim 1, wherein the inner layer comprises at least one wedge-shaped region having a minimum wedge angle of at least 0.10 mrad. A multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; comprising a second poly(vinyl butyral) resin and at least one plasticization a second polymer layer, wherein the second polymer layer has a glass transition temperature of less than 9 ° C; and a third polymer layer comprising a third poly(vinyl butyral) resin and at least one plasticizer, Wherein the second polymer layer is disposed between and in contact with each of the first and second polymer layers, wherein at least one of the first and third polymer layers has at least 33 ° C The glass transition temperature, and wherein the inner layer has an equivalent glass transition temperature (T _eq ) in the range of 27 ° C to less than 29 ° C. The inner layer of claim 5, wherein the second poly(vinyl butyral) resin has a residual hydroxyl group content of at least 7% lower than the first and/or third poly(vinyl butyral) resin. Residual hydroxyl content, and wherein the second polymer layer has a thickness of less than 9 mils. The inner layer of claim 5, wherein at least one of the first and the third poly(vinyl butyral) resins has a residual hydroxyl content of greater than 19% by weight and/or wherein the first and third At least one of the polymer layers has a plasticizer content of less than 35 phr. A multilayer glass sheet comprising: a pair of rigid substrates; and an inner layer disposed between the substrates, wherein the inner layer comprises a first poly(vinyl butyral) resin and at least one plasticizer a polymer layer; a second polymer layer comprising a second poly(vinyl butyral) resin and at least one plasticizer; and a third poly(vinyl butyral) resin and at least one plasticizer a third polymer layer, wherein at least one of the first and third polymer layers has a glass transition temperature of at least 33 ° C and wherein the first and third polymer layers have a combined thickness of at least 28 mils And wherein the rigid substrates have a combined thickness of less than or equal to 4.0 mm. The panel of claim 8, wherein at least one of the first polymer layer and the third polymer layer has a plasticizer content of less than 35 phr and/or wherein the first poly(vinyl butyral) At least one of the resin and the third poly(vinyl butyral) resin has a residual hydroxyl content of greater than 19% by weight. The panel of claim 8, wherein the second polymer layer has a glass transition temperature of less than 9 ° C and a thickness of no more than 9 mils. A multilayer inner layer comprising: a first plasticized polymer layer, wherein the first plasticized polymer layer has a glass transition temperature of at least 33 ° C; and a second plasticized polymer layer, wherein the second plasticized polymerization layer The layer has a glass transition temperature of less than 10 ° C and a thickness of 5 mils or less, wherein the inner layer has an equivalent glass transition temperature of at least 28.3 °C. The inner layer of claim 11, further comprising a third plasticized polymer layer, wherein the second plasticized polymer layer is disposed between and in contact with each of the first and third polymer layers Wherein the third plasticized polymer layer has a glass transition temperature of at least 33 °C. The inner layer of claim 12, wherein the ratio of the combined thickness of the first plasticized polymer layer and the third plasticized polymer layer to the thickness of the second plasticized polymer layer is at least 3:1. a multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least a first plasticizer; and a second poly(vinyl butyral) resin and at least a second polymer layer of a second plasticizer, wherein the second polymer layer is disposed adjacent to and in contact with the first polymer layer, and wherein the second polymer layer has a glass transition temperature of less than or equal to 20 ° C, And wherein the first polymer layer has a glass transition temperature that is at least 15 ° C higher than the glass transition temperature of the second polymer layer, wherein the first and second poly(vinyl butyral) resins have respective First and second residual hydroxyl groups, wherein a difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 3% by weight, and wherein the first polymer layer has a 13 mil or greater The thickness and/or wherein the second polymer layer has a thickness of 5 mils or less. A multilayer glass sheet comprising: a pair of rigid substrates; and a plurality of inner layers disposed between the rigid substrates, the inner layer comprising a first poly(vinyl condensate) comprising a residual hydroxyl content greater than 19% by weight An aldehyde) resin and a first polymer layer of at least a first plasticizer, wherein the first polymer layer has a glass transition temperature of at least 33 ° C; and comprises a second poly(vinyl butyral) resin and at least a second a second polymer layer of a plasticizer, wherein the second polymer layer has a glass transition temperature of less than or equal to 20 ° C, and comprises a third poly(vinyl butyral) resin and at least a third third plasticizer a polymer layer, wherein the second polymer layer is disposed between and in contact with each of the first and third polymer layers, wherein each of the first and third polymer layers Contacting one of the rigid substrates, wherein the rigid substrates have a combined thickness of less than or equal to 4.0 mm. The panel of claim 15 wherein the residual hydroxyl content of the first poly(vinyl butyral) resin differs from the residual hydroxyl content of the second poly(vinyl butyral) resin by at least 6% by weight. The panel of claim 15 wherein the second polymer layer has a glass transition temperature of less than 9 ° C and/or a minimum thickness of no more than 9 mils. The board of claim 17, wherein the inner layer has a sound transmission loss of at least 35 dB, which is at a coincidence frequency according to ASTM E-90 (05) at a temperature of 20 ° C and when the inner layer is 80 cm × 50 in size Measured when laminating between two glass flakes of cm and thickness of 2.3 mm. The panel of claim 15 wherein the third poly(vinyl butyral) resin has a residual hydroxyl content of greater than 19% by weight, and wherein the third polymeric layer has a glass transition temperature of at least 33 °C. The panel of claim 15 wherein the panel has an asymmetric configuration such that one of the rigid substrates has a thickness that is at least 0.1 mm greater than the thickness of the other of the rigid substrates. A multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least two plasticizers, wherein each plasticizer is at least 4 parts per hundred parts of resin (phr) An amount present in the first polymer layer, and wherein the first polymer layer has a glass transition temperature of at least 35 ° C in the inner layer; and a second polymerization adjacent to and in contact with the first polymer layer a layer, wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticizer, wherein the second polymer layer has a glass transition temperature of less than 20 ° C in the inner layer, Wherein the inner layer has an equivalent glass transition temperature of at least 27 °C. The inner layer of claim 21, wherein the first poly(vinyl butyral) resin has a residual hydroxyl content of at least 19% by weight and a total plasticizer content of less than 35 phr. The inner layer of claim 21, further comprising a third polymer layer, wherein the second polymer layer is disposed between the first and third polymer layers in the inner layer and each of the layers Contact, wherein the third polymer layer comprises a third poly(vinyl butyral) resin and at least one plasticizer and has a glass transition temperature of at least 33 ° C, wherein the first and the third polymer layer are combined The thickness is at least 20 mils. A multilayer inner layer comprising: a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer, wherein the first polymer layer has a glass transition temperature of at least 35 ° C and comprises At least 30 parts per hundred parts of resin (phr) of the plasticizer, wherein the first poly(vinyl butyral) resin has a residual hydroxyl content of greater than 19% by weight; and adjacent to the first in the inner layer a second polymer layer of the polymer layer, wherein the second polymer layer comprises a second poly(vinyl butyral) resin and at least one plasticizer, wherein the second poly(vinyl butyral) resin has a residual hydroxyl group content differing from the residual hydroxyl content of the first poly(vinyl butyral) resin by at least 9.5% by weight, wherein at least one of the first and second polymer layers is at 2,000 to 8,000 Hz An average shear storage modulus of at least 150 MPa in the /3 octave band frequency and/or wherein the inner layer has a weighted average sound transmission loss (TL _w ) of at least 38 dB, when the inner layer is at a size of 80 2,000 and 8,000 when laminated between two glass sheets of cm × 50 cm and thickness of 2.3 mm Between Hz is measured at a temperature of 20 ° C according to ASTM E-90 (05). The inner layer of claim 24, further comprising a third polymer layer, wherein the second polymer layer is disposed between the first and third polymer layers in the inner layer and each of the layers Contact, wherein the third polymer layer comprises a third poly(vinyl butyral) resin and at least one plasticizer, and wherein the third poly(vinyl butyral) resin has a second poly(ethylene) The residual hydroxyl content of the butyl acetal resin differs by at least 7 wt% of the residual hydroxyl content. The inner layer of claim 24, wherein the first polymer layer has a plasticizer content of no more than about 35 phr, wherein the second polymer layer has a glass transition temperature of no more than 5 ° C and a plasticization of at least 55 phr The agent content, wherein the thickness ratio of the first polymer layer to the second polymer layer is at least 1.4:1, and wherein the inner layer has an equivalent glass transition temperature of at least 26 °C. A multilayer board comprising: a pair of rigid substrates; and an inner layer disposed between the substrates, wherein the inner layer comprises a first layer comprising a first poly(vinyl butyral) resin and at least one plasticizer a polymer layer, wherein the first polymer layer has a glass transition temperature of at least 35 ° C and wherein the plasticizer is present in the first polymer layer in an amount of less than 30 parts per hundred parts of resin (phr); a dimeric (vinyl butyral) resin and a second polymer layer of at least one plasticizer, wherein the plasticizer is present in the second polymer layer in an amount of at least 55 phr; and comprises a third poly( a vinyl butyral) resin and a third polymer layer of at least one plasticizer, wherein the second polymer layer is disposed between the first and second poly(vinyl butyral) polymer layers and Contacting each of them, wherein the inner layer has an equivalent glass transition temperature of at least 27 ° C, wherein the inner layer has a sound transmission loss of at least 35 dB, and when the inner layer has a size of 80 cm × 50 cm and When laminated between two glass sheets with a thickness of 2.3 mm, at the coincidence frequency according to ASTM E-90 ( 05) Measured at a temperature of 20 ° C, and / or a weighted average sound transmission loss (TL _w ) of at least 38 dB, when the inner layer is two glass flakes having a size of 80 cm × 50 cm and a thickness of 2.3 mm The lamination between 2,000 and 8,000 Hz is measured according to ASTM E-90 (05) at a temperature of 20 ° C, wherein the combined thickness of the rigid substrates is less than or equal to 4.0 mm. The panel of claim 27, wherein the first polymer layer has a plasticizer content of less than 35 phr and wherein the first poly(vinyl butyral) resin has a residual hydroxyl content of greater than 19% by weight. The panel of claim 27, wherein the inner layer has an equivalent glass transition temperature of at least 26 ° C, wherein the combined thickness of the rigid substrates is less than 3.8 mm, and wherein the sheet has a deflection hardness of at least 280 N/cm. The plate of claim 27, wherein the residual hydroxyl content of the first poly(vinyl butyral) resin differs from the residual hydroxyl content of the second poly(vinyl butyral) resin by at least 7% by weight, and wherein The difference between the glass transition temperature of the first and second polymer layers is at least 20 °C.