CN118055855A

CN118055855A - Polymer interlayers having improved acoustic properties

Info

Publication number: CN118055855A
Application number: CN202280066994.XA
Authority: CN
Inventors: 马亦农; 唐广鑫; 陈文杰
Original assignee: Solutia Inc
Current assignee: Solutia Inc
Priority date: 2021-10-08
Filing date: 2022-10-05
Publication date: 2024-05-17

Abstract

A polymer interlayer having improved acoustic properties. The polymer interlayer includes a first polymer layer, a second polymer layer, and a third polymer layer. The first polymer layer is located between the second polymer layer and the third polymer layer. The first polymer layer is formed of a resin including polyvinyl acetate (PVAc). The first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

Description

Polymer interlayers having improved acoustic properties

Technical Field

The present invention relates to the field of polymer interlayers and multiple layer panels comprising polymer interlayers. More particularly, the present invention relates to the field of polymer interlayers comprising multiple polymer layers, and the manufacture and use thereof.

Background

A multi-layer panel is typically a panel composed of two sheets of substrate (e.g., without limitation, glass, polyester, polyacrylate, or polycarbonate) and one or more layers of polymer interlayers sandwiched therebetween. Laminated multiple layer glass panels are commonly used in architectural window applications and for motor vehicle windows and aircraft windows, as well as for photovoltaic solar panels. The first two applications are commonly referred to as laminated safety glass. The primary function of the interlayer in laminated safety glass is to absorb energy generated by an impact or force applied to the glass so that the glass layers bond together even under pressure and glass breakage and thereby prevent the glass from breaking into sharp fragments. In addition, the interlayer can also impart a significantly higher sound-insulating rating to the glass, reduce UV and/or IR light transmission, and enhance the aesthetic appeal of the associated window. For example, laminated glass panels have been produced with desirable acoustic properties, resulting in a quieter interior space.

In addition, laminated glass panels have been used in vehicles equipped with head-up display ("HUD") systems (also known as head-up systems) that project images of instrument clusters or other important information to a location on the windshield at the eye level of the vehicle driver. Such a display allows the driver to visually access dashboard information while maintaining focus on the upcoming travel path. Typically, HUD systems in automobiles or aircraft use the interior surface of the vehicle windshield to partially reflect the projected image. However, secondary reflections occur at the outer surface of the vehicle windshield, forming a weak secondary image or "ghost image". Since the two reflected images are shifted in position, ghosts are often observed, which creates an undesirable viewing experience for the driver. When an image is projected onto a windshield having a uniform thickness, interference ghost images or reflection ghost images are generated due to positional differences of the projected image when reflected at the inner and outer surfaces of the glass.

One way to solve these ghosts or ghosts is to orient the inner and outer glass panels at an angle to each other. This aligns the positions of the reflected images to a single point, creating a single image. Typically, this is accomplished by displacing the outer sheet relative to the inner sheet using a wedge-shaped or "tapered" interlayer that includes at least one region of non-uniform thickness. Most conventional tapered interlayers include a constant wedge angle across the HUD area, although some interlayers have recently been developed that include multiple wedge angles across the HUD area.

To achieve the desired characteristics and performance characteristics of glass panels (e.g., acoustical insulation, light transmission, HUD displays, and/or enhanced aesthetic appeal), it has become common practice to use multiple layers or interlayers. As used herein, the terms "multilayer" and "layers" refer to interlayers having more than one layer, and multilayer and layers are used interchangeably. The multi-layer interlayer typically comprises at least one soft layer and at least one hard layer. As mentioned above, interlayers having a soft "core" layer sandwiched between two more rigid or stiffer "skin" layers have been designed to have sound damping properties for glass panels. Such a construction is generally referred to herein as a "three layer" interlayer. The soft "core" layer is considered an acoustic layer (because the soft layer advantageously reduces the sound transmission), while the hard "skin" layer is referred to as a conventional layer or a non-acoustic layer.

Typically, the layers of the interlayer are produced by mixing a polymeric resin such as poly (vinyl butyral) with one or more plasticizers and melt processing the mixture into sheets by any suitable process or method known to those skilled in the art, including but not limited to extrusion, in which the layers are combined by methods such as coextrusion and lamination. In a three layer interlayer, the core layer may include more plasticizer than the skin layer, such that the core layer is softer than the relatively stiff skin layer. As described in more detail below, other additional ingredients may optionally be added for various other purposes. After the interlayer sheet is formed, it is typically collected and rolled for transport and storage, and later used in a multiple layer glass panel as described below.

Multiple layer glass panels are typically manufactured in combination with interlayers, a simplified description of which is provided below. First, a multi-layer interlayer can be coextruded using a multi-manifold coextrusion apparatus. The apparatus operates by simultaneously extruding the polymer melt from each manifold to an extrusion opening. The properties of the layer can be varied by adjusting the properties (e.g., temperature and/or opening size) of the die lip at the extrusion opening. Once formed, the interlayer sheet is placed between two glass substrates and any excess interlayer is trimmed from the edges to form an assembly. It is not uncommon to place multiple polymer interlayer sheets or one polymer interlayer sheet with multiple layers (or a combination of both) between two glass substrates to form a multiple layer glass panel with multiple polymer interlayers. Air is then removed from the assembly by suitable processes or methods known to those skilled in the art; for example by means of rolls, vacuum bags or another deaeration device. In addition, the interlayer is partially laminated to the substrate by any method known to those of ordinary skill in the art. In the final step, this pre-bonding is made more durable by a high temperature and high pressure lamination process or any other method known to one of ordinary skill in the art, such as, but not limited to, high pressure steam, in order to form the final unitary structure. The following provides a simplified description of the manner in which multiple layer glass panels are typically produced in combination with interlayers.

In view of the above, there remains a need in the art to develop a multilayer interlayer that can provide enhanced acoustic characteristics without degrading other optical or mechanical properties of conventional multilayer interlayers. More specifically, there is a need in the art to develop a multi-layer interlayer having at least one soft core layer and one hard skin layer that provides enhanced acoustic properties. In addition, the polymeric layers of such multi-layer interlayers are required to exhibit suitable compatibility with each other in order to provide sufficient adhesion to facilitate bonding of the polymeric layers during manufacture and use of the interlayer.

Drawings

FIG. 1 is a schematic view of a laminated glass panel comprising a pair of glass sheets opposite a polymer interlayer, wherein the polymer interlayer comprises three layers having a pair of skin layers opposite a core layer;

FIG. 2 is another schematic view of a laminated glass panel comprising a pair of glass sheets opposite a polymer interlayer, wherein the polymer interlayer has a wedge shape; and

FIG. 3 is a graph of tan delta values for two different polymer interlayer sheets, one of which comprises polyvinyl acetate (PVAc) with a glyceryl plasticizer and the other of which comprises poly (vinyl butyral) (PVB);

Fig. 4 is a graph of tan delta values for three different polymer interlayer sheets, two of which comprise polyvinyl acetate (PVAc) and a ethylene glycol diester plasticizer and the other of which comprises poly (vinyl butyral) (PVB);

FIG. 5 is a schematic illustration of a two-dimensional model of acoustic loss for simulating acoustic loss of a laminated glass panel;

FIG. 6 is a graph of simulated acoustic loss for two glass panels comprising the polymer interlayer of FIG. 4, wherein the acoustic loss is obtained using the acoustic loss model of FIG. 5;

FIG. 7 is a graph of tan delta values for four different polymer interlayer sheets, three of which contain polyvinyl acetate (PVAc) with different amounts of ethylene glycol diester plasticizers and another polymer interlayer sheet containing poly (vinyl butyral) (PVB);

FIG. 8 is a graph of simulated sound transmission loss for three glass panels comprising the polymer interlayer of FIG. 7, wherein the sound transmission loss is obtained using the sound transmission loss model of FIG. 5;

FIG. 9 is a graph of tan delta values for three different polymer interlayer sheets, two of which comprise hybrid polyvinyl acetate (PVAc) and the other of which comprises poly (vinyl butyral) (PVB);

fig. 10 is a graph of tan delta values for two different three layer polymer interlayers, one having a core layer comprising hybrid polyvinyl acetate (PVAc) and the other having a core layer comprising poly (vinyl butyral) (PVB);

FIG. 11 is a graph of tan delta values for two different three layer polymer interlayers, each of which has a core layer comprising hybrid polyvinyl acetate (PVAc);

fig. 12 is a graph of simulated acoustic loss for three laminated glass panels, each laminated glass panel having three polymer interlayers, two of which have a core layer comprising hybrid polyvinyl acetate (PVAc), and the other polymer interlayer having a core layer comprising poly (vinyl butyral) (PVB), and acoustic loss obtained using the acoustic loss model of fig. 5;

FIG. 13 is a graph of the difference between the simulated sound transmission losses of FIG. 12;

Fig. 14 is another graph of simulated acoustic losses for three laminated glass panels, each laminated glass panel having a three layer polymer interlayer, wherein two polymer interlayers have a core layer comprising hybrid polyvinyl acetate (PVAc), the other polymer interlayer has a core layer comprising poly (vinyl butyral) (PVB), and the acoustic losses were obtained using the acoustic loss model of fig. 5;

Fig. 15 is a graph of the difference between the transmission losses of fig. 14; and

Fig. 16 is a graph of tan delta values for two different polymer interlayers, one of which is a three layer having a core layer comprising poly (vinyl butyral) (PVB), and the other of which is a five layer interlayer having a core layer comprising polyvinyl acetate (PVAc), a tie layer comprising hybrid polyvinyl acetate (PVAc), and a skin layer comprising poly (vinyl butyral) (PVB).

Disclosure of Invention

One aspect of the present invention relates to a polymer interlayer having improved acoustic properties. The polymer interlayer includes a first polymer layer, a second polymer layer, and a third polymer layer. The first polymer layer is located between the second polymer layer and the third polymer layer. The first polymer layer is formed of a resin including polyvinyl acetate (PVAc). The first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

An additional aspect of the invention relates to a method of forming a polymer interlayer having improved acoustic properties. The method includes the step of extruding a first polymer melt to form a first polymer layer. An additional step includes extruding the second polymer melt to form a second polymer layer and a third polymer layer. During the extrusion step, the first polymer layer is located between the second polymer layer and the third polymer layer. The first polymer layer is formed of a resin including polyvinyl acetate (PVAc). The first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

An additional aspect of the invention relates to a polymer interlayer comprising a first polymer layer, a second polymer layer, and a third polymer layer. The first polymer layer is located between the second polymer layer and the third polymer layer. The first polymer layer is formed of a resin including hybrid polyvinyl acetate (PVAc). The first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.5.

Another aspect of the invention relates to a polymer interlayer comprising a first polymer layer, a second polymer layer, and a third polymer layer. The first polymer layer is located between the second polymer layer and the third polymer layer. The first polymer layer is formed of a resin including polyvinyl acetate (PVAc). The polymer interlayer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.3.

Detailed Description

Embodiments of the present invention relate to a multi-layer panel and a method of manufacturing a multi-layer panel. Typically, a multi-layer panel is composed of two sheets of glass or other suitable substrate with one or more polymeric interlayer sheets sandwiched therebetween. Multilayer panels are typically produced by placing at least one polymeric interlayer sheet between two substrates to create an assembly. Fig. 1 shows a multi-layer panel 10 comprising a pair of glass sheets 12 with a multi-layer interlayer sandwiched therebetween. The multi-layer sandwich is configured as a three-layer sandwich having three separate polymeric sandwich sheets including a soft core layer 14 and two relatively stiff skin layers 16 positioned on either side of the core layer 14. However, in some additional embodiments of the present invention, the multi-layer interlayer may include more than three separate layers. For example, in certain embodiments, the multi-layer interlayer may include a five-layer interlayer in which an adhesive layer is located between the core layer 14 and each skin layer 16.

In some embodiments, the interlayers (e.g., core layer 14 and skin layer 16) will have a substantially constant or uniform thickness with respect to the length of the interlayer. However, in an alternative embodiment, as shown in FIG. 2, the interlayer may have at least one region of non-uniform thickness. For example, the sandwich comprised of core layer 14 and skin layer 16 may be wedge-shaped such that the thickness of the sandwich varies (e.g., linearly) with respect to the length of the sandwich. In some such embodiments, the thickness of the interlayer may vary due to variations in the thickness of the core layer 14 (i.e., the skin layer 16 has a generally constant thickness). Alternatively, the thickness of the interlayer may vary due to variations in the thickness of the skin layer 16 (i.e., the core layer 14 has a generally constant thickness). In a further alternative, the thickness of the interlayer may vary due to variations in the thickness of both the core layer 14 and the skin layer 16.

To facilitate a more complete understanding of the interlayers and multiple layer panels disclosed herein, the meaning of certain terms as used in the present application will be defined. These definitions should not be construed to limit these terms as they are understood by those skilled in the art but merely to provide a better understanding of how certain terms are used herein.

As used herein, the terms "polymeric interlayer sheet", "interlayer", "polymeric layer" and "polymeric melt sheet" may refer to a single layer sheet or a multi-layer interlayer. As the name implies, a "monolayer sheet" is a single polymer layer extruded as a layer. In another aspect, the multilayer interlayer may comprise multiple layers including a single extruded layer, a co-extruded layer, or any combination of single and co-extruded layers. Thus, the multilayer interlayer may include, for example: two or more single layer sheets ("multi-layer sheets") combined together; two or more layers coextruded together ("coextruded sheet"); two or more coextruded sheets bonded together; a combination of at least one single layer sheet and at least one coextruded sheet; and a combination of at least one multilayer sheet and at least one coextruded sheet. In various embodiments of the present invention, the multilayer interlayer comprises at least two polymeric layers (e.g., a monolayer or a coextruded multilayer) disposed in direct contact with each other, wherein each layer comprises a polymeric resin. As used herein, the term "resin" refers to the polymeric component (e.g., PVAc or PVB) removed from the mixture, which results from acid catalysis and subsequent neutralization of the polymer precursor. Typically, plasticizers, such as those discussed more fully below, are added to the resin to produce plasticized polymers. Additionally, the resin may have other components in addition to the polymer and plasticizer, including, for example, acetates, salts, and alcohols.

It should be understood that various thermoplastic interlayers can be used as the polymer resin of the polymer interlayer. Contemplated polymers include, but are not limited to, polyurethane, polyvinyl chloride, polyvinyl acetate ("PVAc"), poly (vinyl butyral) ("PVB"), and combinations thereof. These polymers may be used alone or in combination with other polymers. It will thus be appreciated that where ranges, values and/or methods are given for a given polymer interlayer (e.g., plasticizer component percentages, thicknesses and characterization enhancing additives) in this disclosure, these ranges, values and/or methods may also apply to other polymers and polymer blends disclosed herein, where applicable, or may be modified as known to those of skill in the art to apply to different materials. As used herein, the term "molecular weight" refers to weight average molecular weight (Mw). The molecular weight of the PVAc or PVB resins disclosed herein can range from, for example, about 50,000 to about 600,000, about 70,000 to about 450,000, or about 100,000 to about 425,000 daltons. In certain preferred embodiments, the molecular weight of the PVAc resin may range from about 100,000 to about 1,500,000 or from about 200,000 to about 700,000 daltons or about 500,000 daltons.

When the resin compositions, layers, and interlayers described herein comprise PVAc resin, the PVAc can be formed according to any suitable method, and can include residual hydroxyl content and optionally aldehyde content (e.g., butyraldehyde) in addition to the desired percentage of acetate functionality. For example, the PVAc resin of the present invention can be formed by free radical polymerization of vinyl acetate monomers to form PVAc homopolymers of acetate having an acetate content of substantially 100 wt%. Subsequent hydrolysis may result in a lower desired percentage of acetate having residual hydroxyl content. If the free radical polymerization is carried out in the presence of ethylene or another copolymer, the polyvinyl acetate residues are present in the polymer in an amount of at least 80wt%, or at least 90wt%, or at least 95wt%, or at least 98wt%. Thus, the PVAc described herein can comprise at least 80wt%, or at least 90wt%, or at least 95wt%, or at least 98wt% acetate.

Alternatively, a hybrid form of PVAc may be formed by acetalization of PVAc with an acid catalyst in the presence of one or more aldehydes, optionally partially hydrolyzed (with residual hydroxyl content). When acetalization is carried out in the presence of an aldehyde (e.g., butyraldehyde), residual aldehyde groups are present in addition to acetate and hydroxyl content. For example, the aldehyde content of the PVAc may comprise one or more of acetaldehyde, propionaldehyde, isobutyraldehyde, or n-butyraldehyde. Thus, the aldehyde content of PVAc may be 4wt％-45wt％、4wt％-40wt％、4wt％-35wt％、4wt％-30wt％、4wt％-25wt％、4wt％-20wt％、4wt％-15wt％、4wt％-10wt％、5wt％-45wt％、5wt％-40wt％、5wt％-35wt％、5wt％-30wt％、5wt％-25wt％、5wt％-20wt％、5wt％-15wt％、5wt％-10wt％、10wt％-45wt％、10wt％-40wt％、10wt％-35wt％、10wt％-30wt％、10wt％-25wt％、10wt％-20wt％、10wt％-15wt％、15wt％-45wt％、15wt％-40wt％、15wt％-35wt％、15wt％-30wt％、15wt％-25wt％、15wt％-20wt％、20wt％-45wt％、20wt％-40wt％、20wt％-35wt％、20wt％-30wt％、20wt％-25wt％、30wt％-45wt％、30wt％-40wt％、30wt％-35wt％、40wt％-45wt％、 and/or up to about 45wt%, or up to 40wt%, or up to 35wt%, or up to 30wt%, or up to 25wt%, or up to 20wt%, or up to 15wt%, or up to 10wt%. Furthermore, the PVAc of the present invention can have a residual hydroxyl content of, for example, from about 4wt% to about 30wt%, or from 4wt% to about 25wt%, or from 4wt% to 20wt%, or from 4wt% to 15wt%, or from 4wt% to 10wt%, or from about 5wt% to about 30wt%, or from 5wt% to about 25wt%, or from 5wt% to 20wt%, or from 5wt% to 15wt%, or from 5wt% to 10wt%, or from 10wt% to 25wt%, or from 10wt% to 20wt%, or from 10wt% to 15wt%, or from 15wt% to 25wt%, or from 15wt% to 20wt%, and/or up to about 30wt%, or up to 25wt%, or up to 20wt%, or up to 15wt%, or up to 10wt%, or up to 5wt%.

The total percent acetate content of the resulting PVAc according to the present invention can be at least about 40wt%, at least 45wt%, or at least about 50wt%. Alternatively, unless otherwise indicated, the percent acetate measured according to ASTM D-1396 may be at least about 55wt%, or at least about 60wt%, or at least about 65wt%, or at least about 70wt%, or at least about 75wt%, at least 80wt%, at least 85wt%, at least 90wt%, at least 95wt%, up to 100wt%, and/or 40wt％-100wt％、40wt％-90wt％、40wt％-80wt％、40wt％-70wt％、40wt％-60wt％、40wt％-50wt％、50wt％-100wt％、50wt％-90wt％、50wt％-80wt％、50wt％-70wt％、50wt％-60wt％、60wt％-100wt％、60wt％-90wt％、60wt％-80wt％、60wt％-70wt％、70wt％-100wt％、70wt％-90wt％、70wt％-80wt％、80wt％-100wt％、80wt％-90wt％、 or 90wt% -100wt%. The total amount of any aldehyde residues in the PVAc resin may be collectively referred to as the acetal component, with the remainder of the PVAc resin being residual hydroxyl groups and residual acetate groups, as will be discussed in further detail below.

It should be understood that the PVAc resin of embodiments of the present invention can include any combination of the above-described composition values (or ranges of values). For example, in some embodiments, the PVAc may comprise 40wt% to 80wt% acetate content, 5wt% to 20wt% hydroxyl content, and 10wt% to 45wt% aldehyde content. In certain specific embodiments, the PVAc may comprise an acetate content of 50wt% to 70wt%, a hydroxyl content of 10wt% to 15wt%, and an aldehyde content of 25wt% to 35 wt%. In some further embodiments, the PVAc can comprise an acetate content of about 60wt%, a hydroxyl content of about 10wt%, and an aldehyde content of about 30 wt%. In still further embodiments, the PVAc may comprise an acetate content of about 50wt%, a hydroxyl content of about 15wt%, and an aldehyde content of about 35 wt%. The term "hybrid" may be used herein with respect to the PVAc resin (or resulting polymer layer) when the resin has an acetate content of at least 40wt% (e.g., a hydroxyl content and/or an aldehyde content of greater than about 4 wt%) in addition to the non-nominal hydroxyl content and aldehyde content. However, the generic term "PVAc" as used herein may refer to a hybrid PVAc resin or a resin consisting essentially of polyvinyl acetate.

Resins forming the compositions, layers and interlayers described herein can be prepared by known methods, such as those described below: poly (vinyl acetal) is formed directly from poly (vinyl acetate) without solvent, polymer engineering and science, volume 39, phase 5, pages 862-871, ,O'Neill,Mark L(2004)(Solvent-Free Generation of Poly(Viny Acetals)Directly Poly(Vinyl Acetate),in Polymer Engineering and Science,Volume 39,Issue 5,pages 862-871,by O'Neill,Mark L.(2004)),, the entire disclosure of which is incorporated herein by reference.

Although generally referred to herein as "poly (vinyl acetal)" or "poly (vinyl butyral)", the resins described herein may include residues of any suitable aldehyde, including, but not limited to, isobutyraldehyde, as previously discussed. In some embodiments, the one or more poly (vinyl acetal) resins can include residues of at least one C ₁-C₁₀ aldehyde or at least one C ₄-C₈ aldehyde. Examples of suitable C ₄-C₈ aldehydes may include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylpentanal, n-hexanal, 2-ethylhexanal, n-octanal, and combinations thereof.

In many embodiments, a plasticizer is added to the polymer resin to form a polymer layer or interlayer. Plasticizers are typically added to the polymer resins to increase the flexibility and durability of the resulting polymer interlayers. Plasticizers function by: embedding itself between the polymer chains, spacing them apart (increasing "free volume") and thus significantly lowering the glass transition temperature (T _g) of the polymer resin, makes the material softer. In this regard, the amount of plasticizer in the interlayer may be adjusted to affect the glass transition temperature T _g. The glass transition temperature T _g is the temperature at which the indicia transitions from the glassy state of the interlayer to the rubbery state. In general, higher plasticizer loadings may result in lower T _g. In some embodiments, for example when the interlayer is an acoustic trilayer, the inner core layer (i.e., soft layer) will have a glass transition temperature of less than about 20 ℃, while the outer skin layer (e.g., hard layer) will have a glass transition temperature of greater than about 25 ℃. More broadly, the inner core layer (i.e., soft layer) may be softer than the outer skin layer (e.g., hard layer).

Contemplated plasticizers include, but are not limited to, glyceryl plasticizers, ethylene glycol diester plasticizers, and/or combinations thereof. For example, the glyceryl plasticizer may comprise tributyrin. Ethylene glycol diester plasticizers may include, for example, diesters having four or more ethylene glycol repeat units. For example, the ethylene glycol diester plasticizer may include tetraethylene glycol di- (2-ethylhexanoate) ("4-GEH") which includes ethylene glycol diester molecules having four ethylene glycol repeat units. In addition, the ethylene glycol diester plasticizer may include polyethylene glycol bis- (2-ethylhexanoate), which includes ethylene glycol diester molecules having ten ethylene glycol repeat units.

In some embodiments, the glyceryl plasticizer and/or ethylene glycol diester plasticizer may comprise molecules having a particular oxygen to carbon ratio. Such a configuration may facilitate the preferred solubility characteristics of the plasticizer. For example, in some embodiments, the oxygen to carbon ratio of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be at least 0.32, at least 0.34, at least 0.36, at least 0.38, at least 0.40, at least 0.42, at least 0.44, at least 0.46, at least 0.48, or at least 0.50. In some embodiments, the oxygen to carbon ratio of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be 0.32 to 0.50, 0.32 to 0.44, 0.32 to 0.40, 0.34 to 0.50, 0.34 to 0.44, 0.34 to 0.40, 0.36 to 0.50, 0.36 to 0.44, and/or 0.36 to 0.40.

Furthermore, in some embodiments, the glyceryl plasticizer and/or ethylene glycol diester plasticizer may include preferred solubility attributes. In more detail, the total solubility parameter δ _tot of a material may be defined based on the Hansen solubility parameter of the material. The total solubility parameter δ _tot may consist of the solubility contribution from δ _d、δ_p、δ_h, which is a parameter that represents the solubility contribution from dispersion, polarity and hydrogen bonding interactions, respectively. Delta _tot of the material can be calculated by the following equation (1):

δ_tot ²＝δ_d ²+δ_p ²+δ_h ²(1)

In some embodiments, the polar solubility contribution δ _p of the total solubility parameter δ _tot of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be at least 3.7, at least 3.8, at least 3.9, at least 4.0, at least 4.4, at least 4.8, at least 5.0, at least 5.4, at least 5.8, at least 6.0, at least 6.4, at least 6.8, and/or at least 7.0. The units of solubility parameter are provided in MPa ^1/2. In some embodiments, the polar solubility contribution δ _p of the total solubility parameter δ _tot of the glyceryl plasticizer and/or ethylene glycol diester plasticizer may be 3.7 to 7.0, 3.8 to 6.0, and/or 3.8 to 6.0. In some embodiments, the total solubility parameter δ _tot of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer, the hydrogen bond solubility contribution δ _h, may be at least 4.6, at least 4.7, at least 4.8, at least 5.0, at least 5.2, at least 5.4, at least 5.6, at least 5.8, at least 6.0, at least 6.2, at least 6.4, at least 6.6, at least 6.8, at least 7.0, at least 7.2, at least 7.4, at least 7.6, at least 7.8, at least 8.0. In some embodiments, the polar solubility contribution δ _h of the total solubility parameter δ _tot of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be 4.6 to 8.0, 4.6 to 7.0, 4.8 to 8.0, 4.8 to 7.0, 5.4 to 8.0, and/or 5.4 to 7.0.

Furthermore, the polarity/hydrogen solubility parameter δ _(p,h) of a material may consist of solubility contributions from δ _p and δ _h, δ _p and δ _h being parameters representing solubility contributions from polarity and hydrogen bonding interactions, respectively. Delta _(p,h) of the material can be calculated by the following equation (2):

δ_(p,h) ²＝δ_p ²+δ_h ²(2)

In some embodiments, the polar/hydrogen solubility parameter δ _(p,h) of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be at least 5.8, at least 6.0, at least 6.2, at least 6.5, at least 7.0, at least 7.5, at least 8.0, at least 8.5, and/or at least 9.0. In some embodiments, the polar/hydrogen solubility parameter δ _(p,h) of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be 5.8 to 9.0, 6.0 to 9.0, and/or 7.0 to 9.0. In some embodiments, the ratio of the polar/hydrogen solubility parameter δ _(p,h) to the total solubility parameter δ _tot (i.e., δ _(p,h)/δ_tot) of the glyceryl plasticizer and/or ethylene glycol diester plasticizer may be at least 0.365, at least 0.375, at least 0.400, at least 0.420, at least 0.450, at least 0.500, at least 0.550, at least 0.600, at least 0.625, and/or at least 0.650. In some embodiments, the ratio of the polar/hydrogen solubility parameter δ _(p,h) to the total solubility parameter δ _tot (i.e., δ _(p,h)/δ_tot) of the glyceryl plasticizer and/or the ethylene glycol diester plasticizer may be 0.365 to 0.650, 0.375 to 0.650, 0.400 to 0.650, and/or 0.425 to 0.650.

Further, in some embodiments, the molecular weight Mw of the ethylene glycol diester plasticizer can be at least 420 daltons, at least 440 daltons, at least 460 daltons, at least 480 daltons, at least 500 daltons, at least 550 daltons, at least 600 daltons, at least 650 daltons, at least 700 daltons, at least 750 daltons, and/or at least 800 daltons. Further, the molecular weight Mw of the ethylene glycol diester plasticizer may be 420-800 daltons, 420-750 daltons, 440-800 daltons, and/or 440-750 daltons.

Typically, the plasticizer content of the polymer interlayers of the present application will be measured in parts per hundred parts of resin ("phr") as weight/weight. For example, if 30 grams of plasticizer were added to 100 grams of polymer resin, the plasticizer content of the resulting plasticized polymer would be 30phr. When the plasticizer content of the polymer layer is given in the present application, the plasticizer content of the specific layer is determined with reference to phr of plasticizer in the melt used to prepare the specific layer. In some embodiments, the high stiffness interlayer comprises a layer having a plasticizer content of less than about 35phr and less than about 30phr.

According to some embodiments of the present invention, the total plasticizer content of one or more polymeric layers described herein may be at least about 20phr, at least about 25phr, at least about 30phr, at least about 35phr, at least about 38phr, at least about 40phr, at least about 45phr, at least about 50phr, at least about 55phr, at least about 60phr, at least about 65phr, at least about 67phr, at least about 70phr, at least about 75phr of one or more plasticizers. In some embodiments, the polymeric layer may further comprise no more than about 100phr, no more than about 85phr, no more than 80phr, no more than about 75phr, no more than about 70phr, no more than about 65phr, no more than about 60phr, no more than about 55phr, no more than about 50phr, no more than about 45phr, no more than about 40phr, no more than about 38phr, no more than about 35phr, or no more than about 30phr of one or more plasticizers. In some embodiments, the total plasticizer content of at least one polymer layer may range from about 20phr to about 40phr, from about 20phr to about 38phr, or from about 25phr to about 35 phr. In other embodiments, the total plasticizer content of at least one polymer layer may range from about 38phr to about 90phr, from about 40phr to about 85phr, from about 50phr to about 70phr, from about 55phr to about 65phr, and/or from about 60phr or 62.5 phr.

When the interlayer comprises a multi-layer interlayer, two or more polymer layers within the interlayer may have substantially the same plasticizer content and/or at least one polymer layer may have a different plasticizer content than one or more other polymer layers. When the interlayer comprises two or more polymer layers having different plasticizer contents, the two layers may be adjacent to each other. In some embodiments, the difference in plasticizer content between adjacent polymer layers may be at least about 1, at least about 2, at least about 5, at least about 7, at least about 10, at least about 20, at least about 30, at least about 35phr and/or no more than about 80, no more than about 55, no more than about 50, or no more than about 45phr, or in the range of about 1 to about 60phr, about 10 to about 50phr, or about 30 to 45 phr. When three or more layers are present in the interlayer, at least two polymer layers of the interlayer may have similar plasticizer contents falling within, for example, 10phr, 5phr, 2phr, or 1phr of each other, while at least two polymer layers may have plasticizer contents different from each other according to the above ranges.

In addition to the specific plasticizers discussed above, the various polymer layers (e.g., hardcoat layers) of the interlayers discussed herein can include other types of plasticizers. For example, contemplated plasticizers include, but are not limited to, esters of polyacids, polyols, triethylene glycol di- (2-ethylbutyrate), triethylene glycol di- (2-ethylhexanoate) (known as "3-GEH"), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyl adipate, mixtures of heptyl and nonyl adipates, diisononyl adipates, heptyl and dibutyl sebacates, and polymeric plasticizers such as oil-modified sebacic alkyd resins and mixtures of phosphate esters and adipates, and mixtures and combinations thereof. 3-GEH is particularly preferred. Other examples of suitable plasticizers may include, but are not limited to, di (butoxyethyl) adipate and bis (2- (2-butoxyethoxy) ethyl) adipate, dioctyl sebacate, nonylphenyl tetraethylene glycol, and mixtures thereof.

In some embodiments, one or more of the polymeric layers or interlayers described herein can comprise a blend of two or more plasticizers comprising, for example, two or more of the plasticizers listed above. When the polymer layer contains 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 fall within one or more of the above ranges. When the interlayer is a multi-layer interlayer, one or more of the polymer layers may include two or more plasticizers. In some embodiments, when the interlayer is a multi-layer interlayer, at least one of the polymer layers comprising the plasticizer blend may have a glass transition temperature that is higher than the glass transition temperature of a conventional plasticized polymer layer. In some cases, this may provide additional stiffness to the layer, which may be used as an outer "skin" layer in a multi-layer sandwich, for example.

In addition to plasticizers, adhesion control agents ("ACA") are also contemplated as being added to the polymer resin to form the polymer interlayer. When forming laminated panels, the ACA generally acts to alter and/or improve the adhesion of the interlayer to the glass panel. Contemplated ACAs include, but are not limited to, magnesium carboxylate/magnesium salts. In addition, contemplated ACAs may also include those disclosed in U.S. Pat. No. 5,728,472, which is incorporated herein by reference in its entirety, such as residual sodium acetate, potassium acetate, and/or magnesium bis (2-ethylbutyrate).

Other additives may be incorporated into the interlayer to enhance its performance in the final product and to impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., ultraviolet stabilizers), antioxidants, antiblocking agents, flame retardants, IR absorbers or blockers (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB ₆) and cesium tungsten oxide), processing aids, flow enhancing additives, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents, coupling agents, binders, primers, reinforcing additives and fillers, and other additives known to those of ordinary skill in the art.

One parameter used to describe the polymer resin component of the polymer interlayers of the present application is the residual hydroxyl content (as the vinyl hydroxyl content or poly (vinyl alcohol) ("PVOH") content). Residual hydroxyl content refers to the amount of hydroxyl groups remaining as pendant groups on the polymer chain after processing is complete. For example, PVB can be manufactured by hydrolyzing poly (vinyl acetate) to poly (vinyl alcohol) and then reacting the poly (vinyl alcohol) with butyraldehyde to form PVB. Similarly, PVAc can be formed by hydrolyzing PVAc to the desired acetate and hydroxyl content. In the hydrolysis of poly (vinyl acetate) to form PVB, not all pendant acetate groups are typically converted to hydroxyl groups. Furthermore, the reaction with butyraldehyde does not generally result in all of the hydroxyl groups being converted to acetal groups. Thus, in any finished PVAc or PVB, there will typically be residual acetate groups (as vinyl acetate groups) and residual hydroxyl groups (as vinyl hydroxyl groups) on the polymer chain as pendant groups. 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 as a parameter herein, the residual hydroxyl content is measured in weight percent according to ASTM D-1396.

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. As a result, layers or domains formed from first and second poly (vinyl acetal) resins having different compositions may also have different characteristics within a single polymer layer or interlayer. Notably, for a given type of plasticizer, the compatibility of the plasticizer in the polymer is primarily determined by the hydroxyl content of the polymer. Polymers with a greater 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. As a result, poly (vinyl acetal) resins with higher residual hydroxyl content tend to plasticize less and exhibit higher stiffness than similar resins with lower residual hydroxyl content. Conversely, when plasticized with a given plasticizer, a poly (vinyl acetal) resin having a lower residual hydroxyl content may tend to incorporate a higher amount of plasticizer, which may result in a softer polymer layer that exhibits a lower glass transition temperature than a similar resin having a higher residual hydroxyl content. These trends may be reversed depending on the specific resin and plasticizer.

When two poly (vinyl acetal) resins having different residual hydroxyl content levels are blended with a plasticizer, the plasticizer may be partitioned between the polymer layers or domains such that more plasticizer may be present in the layer or domain having the lower residual hydroxyl content and less plasticizer may be present in the layer or domain having the higher residual hydroxyl content. Eventually, an equilibrium state is reached between the two resins. In general, this correlation between the residual hydroxyl content of the polymer and plasticizer compatibility/capacity can be manipulated and utilized to allow the addition of an appropriate amount of plasticizer to the polymer resin and to stably maintain the difference in plasticizer content in the multilayer interlayer. This correlation also helps to stably maintain the difference in plasticizer content between two or more resins as the plasticizer migrates between the resins.

The glass transition temperature of one or more of the polymer layers may be different when measured alone or as part of a multi-layer interlayer due to plasticizer migration within the interlayer. In some embodiments, the interlayer may include at least one polymer layer having a glass transition temperature outside the interlayer of at least about 33 ℃, at least about 34 ℃, at least about 35 ℃, at least about 36 ℃, at least about 37 ℃, at least about 38 ℃, at least about 39 ℃, at least about 40 ℃, at least about 41 ℃, at least about 42 ℃, at least about 43 ℃, at least about 44 ℃, at least about 45 ℃, or at least about 46 ℃. In some embodiments, the glass transition temperature of the same layer within the polymer layer can be at least about 34 ℃, at least about 35 ℃, at least about 36 ℃, at least about 37 ℃, at least about 38 ℃, at least about 39 ℃, at least about 40 ℃, at least about 41 ℃, at least about 42 ℃, at least about 43 ℃, at least about 44 ℃, at least about 45 ℃, at least about 46 ℃, at least about 47 ℃.

In the same or other embodiments, the glass transition temperature of at least one other polymer layer of the multi-layer interlayer may be less than 30 ℃, and for example, the glass transition temperature measured when the interlayer is not part of the interlayer may be no more than about 25 ℃, no more than about 20 ℃, no more than about 15 ℃, no more than about 10 ℃, no more than about 9 ℃, no more than about 8 ℃, no more than about 7 ℃, no more than about 6 ℃, no more than about 5 ℃, no more than about 4 ℃, no more than about 3 ℃, no more than about 2 ℃, no more than about 1 ℃, no more than about 0 ℃, no more than about-1 ℃, no more than about-2 ℃, or no more than about-5 ℃. The glass transition temperature of the same polymer layer may be no more than about 25 ℃, no more than about 20 ℃, no more than about 15 ℃, no more than about 10 ℃, no more than about 9 ℃, no more than about 8 ℃, no more than about 7 ℃, no more than about 6 ℃, no more than about 5 ℃, no more than about 4 ℃, no more than about 3 ℃, no more than about 2 ℃, no more than about 1 ℃, or no more than about 0 ℃ when measured outside the interlayer.

According to some embodiments, the difference between the glass transition temperatures of two polymer layers (typically adjacent polymer layers within an interlayer) may be at least about 5 ℃, at least about 10 ℃, at least about 15 ℃, at least about 20 ℃, at least about 25 ℃, at least about 30 ℃, at least about 35 ℃, or at least about 35 ℃, while in other embodiments, the glass transition temperatures of two or more polymer layers may be within about 5 ℃, about 3 ℃, about 2 ℃, or about 1 ℃ of each other. Typically, the lower glass transition temperature layers have lower stiffness than one or more of the higher glass transition temperature layers in the interlayer, and may be located between the higher glass transition temperature polymer layers in the final interlayer construction.

For example, in some embodiments of the present application, the increased acoustic attenuation characteristics of the soft layer combine with the mechanical strength of the hard/rigid layer to create a multi-layer sandwich. In these embodiments, the middle soft layer is sandwiched between two hard/rigid outer layers. This construction of (hard)/(soft)/(hard) results in an easy to handle multilayer interlayer which can be used in conventional lamination processes and which can be constructed with relatively thin and light layers. Soft layers composed of PVAc are generally characterized by a lower residual hydroxyl content (e.g., less than or equal to 16wt%, less than or equal to 15wt%, or less than or equal to 12wt%, or any of the ranges disclosed elsewhere), a higher plasticizer content (e.g., greater than or equal to about 48phr or greater than or equal to about 70phr, or any of the ranges described above), and/or a lower glass transition temperature (e.g., less than 30 ℃ or less than 10 ℃, or any of the ranges described above).

It is contemplated that the polymeric interlayer sheets as described herein may be produced by any suitable method known to one of ordinary skill in the art of producing polymeric interlayer sheets capable of being used in multi-layer panels (e.g., glass laminates). For example, it is contemplated that the polymeric interlayer sheet may be formed by solution casting, compression molding, injection molding, melt extrusion, melt blowing, or any other procedure known to one of ordinary skill in the art for producing and manufacturing polymeric interlayer sheets. Furthermore, in embodiments using multiple polymer interlayers, it is contemplated that these multiple polymer interlayers can be formed by coextrusion, blown film, dip coating, solution coating, knife coating, paddle coating, air knife coating, printing, powder coating, spray coating, or other methods known to those of ordinary skill in the art. While all methods of producing polymeric interlayer sheets known to those of ordinary skill in the art are considered possible methods of producing polymeric interlayer sheets described herein, the present application will focus on polymeric interlayer sheets produced by extrusion and/or coextrusion processes. The final multiple layer glass panel laminate of the present disclosure is formed using methods known in the art.

During extrusion, thermoplastic resins and plasticizers, including any of those described above, are typically pre-mixed and fed into an extruder apparatus. Additives such as colorants and UV inhibitors (in liquid, powder or pellet form) may be used and may be mixed into the thermoplastic resin or plasticizer before it reaches the extruder apparatus. These additives are incorporated into the thermoplastic polymer resin and thus into the resulting polymeric interlayer sheet to enhance certain properties of the polymeric interlayer sheet and its performance in the final multiple layer glass panel product.

In the extruder apparatus, the pellets of thermoplastic raw material and the plasticizer, including any of those resins, plasticizers, and other additives described above, are further mixed and melted to produce a resin melt of generally uniform temperature and composition. Embodiments of the present invention may provide a melt temperature of about 200 ℃. Once the melt reaches the end of the extruder device, the melt is advanced into the extruder die. An extruder die is a component of an extruder apparatus that imparts its profile to the final polymeric interlayer sheet product. The die typically has an opening defined by a lip that is substantially larger in one dimension than in a vertical dimension. Typically, the mold is designed such that the melt flows uniformly from the cylindrical profile exiting the mold and into the end profile shape of the product. Various shapes can be imparted to the final polymeric interlayer sheet by the mold, provided that a continuous profile is present. In its most basic sense, extrusion is generally a process used to create objects of a fixed cross-sectional profile. This is accomplished by pushing or pulling the material through a die having the desired cross-section of the final product.

In some embodiments, a coextrusion process may be used. Coextrusion is a method of simultaneously extruding multiple layers of polymeric material. Typically, this type of extrusion utilizes two or more extruders to melt and deliver different thermoplastic melts of different viscosities or other characteristics into a desired final form through a coextrusion die at a stable volumetric throughput. For example, the multi-layer interlayers of the present invention (e.g., in the form of a three-layer interlayer) can be preferably coextruded using a multi-manifold coextrusion apparatus comprising a first die manifold, a second die manifold, and a third die manifold. The coextrusion device can be operated by simultaneously extruding the polymer melt from each manifold through a die and out of an opening, wherein the multilayer interlayer is extruded as a composite of three separate polymer layers. The polymer melt may flow through the mold such that the core layer is located between the skin layers, resulting in the fabrication of a three-layer sandwich with the core layer sandwiched between the skin layers. The die opening may include a pair of lips on either side of the opening. The skin layer may be in contact with the lips, taking into account the positional orientation of the polymer melt. In any event, by adjusting the distance between the lips at the die opening, the interlayer thickness can be varied.

The thickness of the multiple polymer layers exiting the extrusion die during coextrusion can generally be controlled by adjusting the relative speed of the melt through the extrusion die and by the size of the individual die lips. According to some embodiments, the total thickness of the multilayer interlayer may be 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 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 in the range of about 13 to about 75 mils, about 25 to about 70 mils, or about 30 to 60 mils. When the interlayer comprises two or more polymeric layers, each layer can have a thickness of at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10 mils, and/or no more than about 50, no more than about 40, no more than about 30, no more than about 20, no more than about 17, no more than about 15, no more than about 13, no more than about 12, no more than about 10, no more than about 9 mils. In some embodiments, each layer may have approximately the same thickness, while in other embodiments, one or more layers may have a different thickness than one or more other layers within the interlayer.

In some embodiments, wherein the interlayer comprises at least three polymer layers, one or more inner layers may be relatively thin compared to the other outer layers. For example, in some embodiments in which the multilayer interlayer is a three-layer interlayer, the innermost layer may have a thickness of no more than about 12, no more than about 10, no more than about 9, no more than about 8, no more than about 7, no more than about 6, no more than about 5 mils, or it may have a thickness of about 2 to about 12 mils, about 3 to about 10 mils, or about 4 to about 9 mils. In the same or other embodiments, the thickness of each of the outer layers may be at least about 4, at least about 5, at least about 6, at least about 7 mils, and/or no more than about 15, no more than about 13, no more than about 12, no more than about 10, no more than about 9, no more than about 8 mils, or may be in the range of about 2 to about 15, about 3 to about 13, or about 4 to about 10 mils. When the interlayer comprises two outer layers, the layers may have a combined thickness of at least about 9, at least about 13, at least about 15, at least about 16, at least about 18, at least about 20, at least about 23, at least about 25, at least about 26, at least about 28, or at least about 30 mils, and/or no more than about 73, no more than about 60, no more than about 50, no more than about 45, no more than about 40, no more than about 35 mils, or in the range of about 9 to about 70 mils, about 13 to about 40 mils, or about 25 to about 35 mils.

According to some embodiments, the thickness ratio of one of the outer layers to one of the inner layers in the multilayer interlayer 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 interlayer is a three-layer interlayer having an inner core layer disposed between a pair of outer skin layers, the thickness ratio of one skin layer to the core layer may fall within one or more of the above ranges. In some embodiments, the combined thickness ratio of the outer layer to the inner layer may 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 6:1, at least about 6.5:1, or at least about 7:1, and/or not more than about 30:1, not more than about 20:1, not more than about 15:1, not more than about 10:1, not more than about 9:1, not more than about 8:1.

The multilayer interlayers described herein can comprise substantially planar interlayers having substantially the same thickness along the length or longest dimension and/or width or next longest dimension of the sheet. However, in some embodiments, the multi-layer interlayers of the present invention can be tapered or wedge-shaped interlayers that include at least one tapered region having a wedge-shaped profile. The tapered interlayer has a varying 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 interlayer has a greater thickness than the other edge. When the interlayer is a tapered interlayer, at least 1, at least 2, at least 3 or more individual resin layers may include at least one tapered region. Tapered interlayers can be particularly useful in head-up display (HUD) panels, for example, in automotive and aircraft applications.

In view of the above, embodiments of the present invention include a polymer interlayer having improved acoustic properties. The polymer interlayer may be three layers including a soft core polymer layer, a first hard skin polymer layer, and a second hard skin polymer layer. The core layer is located between the skin layers. The core layer may be formed of a resin including polyvinyl acetate (PVAc). For example, the core layer may comprise a hybrid PVAc resin. The first and second skin layers may be formed of PVB or, alternatively, PVAc. For example, the skin layer can be formed from a resin consisting essentially of PVB. However, the core layer may have a T _g of less than about 20 ℃ and a tan delta of greater than about 2.0.

Tan delta (tan delta) of a material (e.g., a polymer layer) is indicative of certain acoustic properties of the material and may be obtained from the glass transition of the material. Specifically, the tan delta (or loss factor) of a material indicates the effectiveness of the sound damping capacity of the material (where a higher tan delta value indicates a higher damping capacity). The glass transition of a polymer layer is the transition of a material from a hard "glass" state to a viscous rubbery state, which is reversible; the glass transition temperature is the temperature at which the sign changes from glassy to rubbery. The polymer layer provides the highest acoustic damping at the glass transition state, and the glass transition temperature is used to characterize the sound-insulating properties of the polymer. The glass transition temperature (T _g) can be determined by Dynamic Mechanical Analysis (DMA) in shear mode. DMA can be used to measure the storage (elastic) modulus in pascals (G ') and the loss (viscous) modulus in pascals (G') of a sample at a given frequency at a temperature sweep rate as a function of temperature. Tan delta of the sample can be calculated based on the ratio of the loss modulus to the storage modulus; in other words, tan δ=g "/G'. The T _g of the sample can be determined based on the position of the tan delta peak on a temperature scale in degrees celsius.

Because the polymer layer provides the highest acoustic damping at the glass transition temperature T _g of the polymer layer, the tan delta peak can also be used to characterize the acoustic properties of the polymer layer. As described above, in general, the higher the tan δ value (including tan δ peak value) of the polymer layer, the higher the sound insulation property of the polymer layer. Accordingly, such glass panels may have beneficial acoustical properties when the polymer layer is part of a multilayer interlayer of the present invention (e.g., a three-layer interlayer comprising a soft polymer core layer of a new composition having improved tan delta sandwiched between two hardcoat polymer layers) and further used to laminate a glass panel (e.g., having a 2.3mm glass// interlayer// 2.3mm glass construction). Such sound-insulating properties may be referred to as sound transmission loss, which is measured in decibels ("dB") for a given frequency or range of frequencies.

In various embodiments, the polymer interlayers of the present invention (e.g., comprising three layers of a soft polymer core layer sandwiched between two hard skin polymer layers) can comprise a soft core PVAc layer that exhibits a glass transition temperature T _g of less than about 20 ℃, less than 19 ℃, less than 18 ℃, less than 17 ℃, less than 16 ℃, less than 15 ℃, less than 10 ℃, less than 5 ℃, less than 3 ℃, less than 0 ℃, less than-3 ℃, less than-5 ℃ and/or less than-10 ℃. In some embodiments, the glass transition temperature T _g of the core layer may be-10 ℃ to 20 ℃, from-10 ℃ to 10 ℃, from-10 ℃ to 0 ℃, from-5 ℃ to 5 ℃, from-3 ℃ to 3 ℃, or about-2 ℃, about-1 ℃, about 0 ℃, about 1 ℃ and/or about 2 ℃. Accordingly, in some embodiments, the peak tan delta of the soft core layer of the polymer interlayers of the present invention can be greater than 1.50, greater than 1.60, greater than 1.70, greater than 1.80, greater than 1.90, greater than 2.00, greater than 2.10, greater than 2.20, greater than 2.30, greater than 2.40, greater than 2.50, greater than 2.60, greater than 2.70, greater than 2.80, greater than 2.90, greater than 3.00, greater than 3.10, greater than 3.20, greater than 3.30, greater than 3.40, greater than 3.50, greater than 3.60, greater than 3.70, greater than 3.80, greater than 3.90, and/or greater than 4.00. Furthermore, in some embodiments, the soft core layer of the polymer interlayers of the present invention can have a peak tan delta of 1.50 to 4.00, 1.50 to 2.00, 1.80 to 3.8, 2.0 to 3.5, and/or 2.1 to 3.0.

In various embodiments, the polymer interlayers of the present invention (e.g., three layers comprising a soft polymer core layer sandwiched between two hard skin polymer layers) can themselves exhibit a glass transition temperature T _g of less than about 20 ℃, less than 15 ℃, less than 10 ℃, less than 5 ℃, less than 3 ℃, less than 0 ℃, less than-3 ℃, less than-5 ℃ and/or less than-10 ℃. In some embodiments, the glass transition temperature T _g of the core layer may be-10 ℃ to 20 ℃, 10 ℃ to 10 ℃,0 ℃ to 10 ℃,5 ℃ to 5 ℃,3 ℃ to 3 ℃, or about-5 ℃, or about-3 ℃, or about-2 ℃, about-1 ℃, about 0 ℃, about 1 ℃, about 2 ℃, about 3 ℃, about 4 ℃, and/or about 5 ℃. Accordingly, in some embodiments, the peak tan delta of the polymer interlayers of the present invention can be greater than 1.20, greater than 1.30, greater than 1.40, greater than 1.50, greater than 1.60, greater than 1.70, greater than 1.80, greater than 1.90, and/or greater than 2.00. Further, in some embodiments, the peak tan delta of the polymer interlayers of the present invention can be from 1.20 to 2.00, from 1.30 to 1.90, from 1.30 to 1.80, from 1.30 to 1.70, from 1.30 to 1.60, and/or from 1.40 to 1.60.

When the polymeric interlayers of the present invention are laminated between a pair of glass sheets to form a glass panel, as discussed above (i.e., having a 2.3-mm glass// interlayer// 2.3-mm glass construction), the STL of the resulting glass panel can be greater than 30dB, greater than 31dB, greater than 32dB, greater than 33dB, greater than 34dB, or greater than 35dB, as measured by a weighted average loss of sound transmission at 1000-10000 Hz. In various embodiments, the interlayers of the present invention have a sound insulation (when in a glass panel having a 2.3mm glass// interlayer// 2.3mm glass construction and at 20 ℃) of greater than 35dB, greater than 36dB, greater than 37dB decibels, greater than 38dB, greater than 39dB, greater than 40dB, greater than 41dB, or greater than 42dB at the coincident frequencies of the glass panel (see definition below). In some embodiments, the coincidence frequency of a glass panel comprising a polymer interlayer according to embodiments of the present invention may be 4000-5000Hz or about 4400Hz. In various embodiments, the interlayers of the present invention have a sound insulation of greater than 35dB, greater than 36dB, greater than 37dB, greater than 38dB, greater than 39dB, greater than 40dB, greater than 41dB, or greater than 42dB at a coincident frequency from 1000Hz to the glass panel (when in a glass panel having a 2.3mm glass// interlayer// 2.3mm glass construction and at 20 ℃). In various embodiments, interlayers of the present invention have a sound insulation from the coincidence frequency of the glass panel to greater than 38dB, greater than 39dB, greater than 40dB, greater than 41dB, greater than 42dB, greater than 43dB, greater than 44dB, greater than 45dB, greater than 46dB, greater than 47dB, greater than 48dB, greater than 49dB, or greater than 50dB (when in a glass panel having a 2.3mm glass// interlayer// 2.3mm glass construction and at 20 ℃).

It will be appreciated that glass has a particular critical or coincidence frequency at which the velocity of the incident acoustic wave in air matches the velocity of the glass bending wave. At the coincidence frequency, the sound wave is particularly effective in vibrating the glass, and the vibrating glass is an effective sound radiator at or near the coincidence frequency and at frequencies above or below the coincidence frequency. As a result, the glass exhibits a decrease or drop in the loss of sound transmission, referred to as a drop in coincidence or coincidence effect, and the glass becomes transparent to sound.

The coincidence frequency of the glass panels can be expressed by the following equation (3):

f_c＝c²/2π×[ρ_s/B]^1/2 (3)

Where c is the speed of sound in air, ρ _s is the surface density of the glass panel and B is the bending stiffness of the glass panel. In general, the coincidence frequency increases as the thickness of the glass panel decreases. For automotive glazings, the coincidence frequency is typically in the range 3150 to 6000Hz, which is well within the wind noise frequency region of 2000 to 8000 Hz. For laminated building glass (e.g., windows), the coincidence frequency is typically less than about 3150Hz.

The polymer interlayers having improved acoustic properties described above can be formed by extruding a first polymer melt to form a soft core layer and extruding a second polymer melt to form first and second hard skin layers. In some embodiments, the first polymer melt will be fed from a first extruder (e.g., a core extruder) and the second polymer melt will be fed from a second extruder (e.g., a sheath extruder) and then split into two streams to form a sheath. Regardless of the core and skin layers, the core layer is typically co-extruded such that the core layer is located between the first and second skin layers. Notably, the first polymer melt forming the core layer comprises PVAc resin and a plasticizer, which, as discussed above, allows the core layer to have a T _g of less than about 20 ℃ and a tan delta of greater than about 2.0.

Thus, as discussed above and as will be described in more detail in the examples below, the polymer interlayers of the present invention will include improved sound damping characteristics. Further, embodiments may additionally include methods of forming laminated glass panels with improved acoustic properties. Such a method may include laminating the above-described polymer interlayer between a pair of glass sheets to form a laminated glass panel. Such glass panels may have improved acoustical properties due to the inclusion of the polymer interlayers of the present invention, as discussed above. Advantageously, the compositions of the core layer and the skin layer exhibit suitable compatibility with each other in order to provide sufficient adhesion to promote bonding of the polymer layers during manufacture and use of the polymer interlayer. Specifically, in the various embodiments described above, the core layer will be formed from a hybrid PVAc resin (i.e., a PVAc resin having an acetate content of at least 40wt% and hydroxyl and aldehyde contents greater than nominal), while the skin layer will consist essentially of PVB. However, a non-nominal amount of PVB in the PVAc resin of the core layer facilitates proper adhesion between the core layer and the skin layer.

Although the above examples discuss primarily the three layer form of the polymer interlayers of the present invention, the polymer interlayers of the present invention can also be in the form of five layer interlayers. Such a five-layer interlayer may include a soft core polymer layer, a first hard skin polymer layer, a first buffer layer between the core and the first skin layer, a second hard skin polymer layer, and a second buffer layer between the core and the second skin layer. The core layer may be formed of a resin containing PVAc. For example, the core layer may comprise a hybrid PVAc resin. Alternatively, the core layer may be formed of a resin consisting essentially of PVAc. The first and second skin layers may be formed of PVB or, alternatively, PVAc. For example, the skin layer can be formed from a resin consisting essentially of PVB. In addition, the buffer layer may include a hybrid PVAc resin. Alternatively, the buffer layer may be formed of a resin consisting essentially of PVAc. However, five-layer interlayers can provide improved sound damping characteristics. For example, a five-layer interlayer may be formed having the same or similar tan delta peak and glass transition temperature T _g values as the three-layer polymer interlayer discussed above. These beneficial properties are discussed in more detail in the examples below.

In certain aspects, a polymer interlayer having improved acoustic properties comprises: a first polymer layer; a second polymer layer; and a third polymer layer, wherein the first polymer layer is located between the second polymer layer and the third polymer layer, wherein the first polymer layer is formed from a resin comprising polyvinyl acetate (PVAc), wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

In other aspects, a method of forming a polymer interlayer having improved acoustic properties includes the steps of: (a) Extruding a first polymer melt to form a first polymer layer; and (b) extruding the second polymer melt to form a second polymer layer and a third polymer layer; wherein upon said extruding of steps (a) and (b), a first polymer layer is located between a second polymer layer and a third polymer layer, wherein the first polymer melt comprises a resin comprising polyvinyl acetate (PVAc), and wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

In certain aspects, the extruding of steps (a) and (b) is performed via coextrusion, wherein the peak tan delta of the first polymer layer is from 2.0 to 3.5, and wherein T _g of the first polymer layer is from-5 ℃ to 5 ℃.

In certain aspects, the first polymer layer has a peak tan delta of 2.0 to 3.5. In certain aspects, the T _g of the first polymeric layer is from-5 to 5 ℃.

In certain aspects, the polymer interlayer comprises: a first polymer layer; a second polymer layer; and a third polymer layer, wherein the first polymer layer is located between the second polymer layer and the third polymer layer, wherein the first polymer layer is formed from a hybrid resin comprising polyvinyl acetate (PVAc), wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.5.

In certain aspects, the peak tan delta of the first polymer layer of any polymer interlayer is from 1.5 to 2.0. In certain aspects, the T _g of the first polymer layer of any polymer interlayer is from-10 ℃ to 10 ℃, or the T _g of the first polymer layer is from 0 ℃ to 10 ℃. In certain aspects, the peak tan delta of any polymer interlayer is greater than 1.3, or the peak tan delta of the polymer interlayer is from 1.3 to 1.8. In certain aspects, the T _g of any of the polymer interlayers is from 0 ℃ to 10 ℃.

In certain aspects, the first and second polymer layers consist essentially of polyvinyl butyral (PVB).

In another aspect, a polymer interlayer comprises: a first polymer layer; a second polymer layer; and a third polymer layer, wherein the first polymer layer is located between the second polymer layer and the third polymer layer, wherein the first polymer layer is formed from a resin comprising polyvinyl acetate (PVAc), wherein the polymer interlayer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.3.

In certain aspects, the polymer interlayer has a peak tan delta greater than 1.5. In certain aspects, the T _g of the polymer interlayer is less than 0 ℃.

In certain aspects, the first polymer layer consists essentially of polyvinyl acetate (PVAc). In certain aspects, the second and third polymer layers are tie layers comprising hybrid polyvinyl acetate (PVAc).

In certain aspects, the polymeric interlayer further comprises a fourth polymeric layer and a fifth polymeric layer, wherein the second polymeric layer is located between the first polymeric layer and the fourth polymeric layer, and wherein the third polymeric layer is located between the first polymeric layer and the fifth polymeric layer. In certain aspects, the fourth and fifth polymer layers are skin layers consisting essentially of polyvinyl butyral (PVB).

In certain aspects, the resin of the first polymer layer of any polymer interlayer comprises a glyceryl plasticizer and/or an ethylene glycol diester plasticizer. In certain aspects, the resin comprises from 50phr to 70phr of plasticizer. In certain aspects, the plasticizer of the first polymer layer of any polymer interlayer comprises tributyrin, or the plasticizer of the first polymer layer comprises a diester having four or more ethylene glycol repeating units, or the plasticizer of the first polymer layer comprises polyethylene glycol bis- (2-ethylhexanoate), or the plasticizer of the first polymer layer comprises a molecule having an oxygen to carbon ratio of at least 0.32, or the plasticizer of the first polymer layer comprises ethylene glycol diester, and wherein the plasticizer has a molecular weight of at least 420 daltons, or the plasticizer of the first polymer layer has a total solubility parameter δ _tot consisting of contributions from a dispersion solubility parameter δ _d, a polar solubility parameter δ _p, and a hydrogen bond solubility parameter δ _h, wherein the ratio of contributions from polar solubility parameter δ _p and hydrogen bond solubility parameter δ _h relative to the total solubility parameter δ _tot is at least 0.365.

In certain aspects, T _g of the first polymer layer of any polymer interlayer is less than T _g of both the second polymer layer and the third polymer layer.

In certain aspects, the resin of any polymer interlayer comprises 40wt% to 80wt% acetate content, 5wt% to 20wt% hydroxyl content, and 20wt% to 40wt% aldehyde content, or the resin comprises at least 50wt% acetate content, or the resin comprises 10wt% to 15wt% hydroxyl content, or the resin comprises 10wt% to 45wt% aldehyde content.

In certain aspects, the thickness of any of the polymer interlayers is generally constant along the length of the polymer interlayer. In certain aspects, the thickness of any of the polymer interlayers varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

Example 1

Two polymer sheets were formed and Dynamic Mechanical Analysis (DMA) tests were used to determine the tan delta values of the sheets over a range of temperatures. The first sheet "EX1-S1" was formed using 200K to 700K daltons PVAc single polymer resin with 48phr tributyrin plasticizer. The second sheet "EX1-S2" was formed using 50,000-600,000 daltons PVB resin (comprising 10.5wt% PVOH, 2.0wt% PVAc, and 87.5wt% PVB) with 75phr triethylene glycol bis- (2-ethylhexanoate) plasticizer. Each of EX1-S1 and EX1-S2 is produced from a resin via a compression molding technique that includes forming the sheet using a steam heated press. Tan delta measurements were performed on sheet samples dried overnight in a desiccator. The test uses torsional and tensile mode Dynamic Mechanical Analysis (DMA). The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-40 to 20 ℃. The frequency dependent parameters were obtained using a "time-temperature superposition" in which the DMA was performed from 0.3rad/s to 300rad/s at-40 ℃, -20 ℃, -10 ℃,0 ℃,10 ℃ and 20 ℃ for each sample.

The resulting tan delta plot for each of the two polymer layers, sheets EX1-S1 and EX1-S2 is shown in FIG. 3. As shown, sheets EX1-S1 comprising PVAc resin and tributyrin plasticizer produced a peak tan delta of 2.9 at T _g at-3 ℃. This loss factor (shown as tan delta and T _g) is an improvement over the polymer layer of sheets EX1-S2 comprising standard PVB and triethylene glycol di- (2-ethylhexanoate) plasticizer. Specifically, as shown, sheets EX1-S2 produced a peak tan delta of only 1.3 at T _g of-1 ℃. Thus, the polymer layer comprising PVAc and tributyrin plasticizer (i.e., sheets EX 1-S1) exhibits an increase in peak tan delta and/or loss factor of greater than 100% at or near T _g relative to a similar PVB formulation (i.e., sheets EX 1-S2).

Example 2

Three polymer sheets were formed and Dynamic Mechanical Analysis (DMA) tests were used to determine tan delta values for the sheets over a range of temperatures. The first sheet "EX2-S1" was formed from 500K Dalton PVAc single polymer resin with 60phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. The second sheet "EX2-S2" is also formed from a 500K Dalton PVAc single polymer resin with 60phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. Finally, a third sheet "EX2-S3" is formed from 50,000-600,000 daltons PVB resin (comprising 10.5 wt.% PVOH, 2.0 wt.% PVAc, and 87.5 wt.% PVB) with 75phr triethylene glycol bis- (2-ethylhexanoate) plasticizer. Each of the EX2-S1, EX2-S2, and EX2-S3 sheets is produced from a resin via a compression molding technique that includes forming the sheet using a steam heated press. Tan delta measurements were performed on sheet samples dried overnight in a desiccator. The test uses torsional and tensile mode Dynamic Mechanical Analysis (DMA). The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-20 to 60 ℃. The frequency dependent parameters were obtained using a "time-temperature superposition" in which DMA was performed from 0.3rad/s to 300rad/s at-20 ℃, -10 ℃,0 ℃,10 ℃,20 ℃, 30 ℃, 40 ℃ and 60 ℃ for each sample.

The resulting tan delta curves for each of the three polymer layers, sheets EX2-S1, EX2-S2 and EX2-S3 are shown in FIG. 4. As shown, sheets EX2-S1 and EX2-S2, each comprising PVAc resin and poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer, produced a peak tan delta of about 2.2 at T _g of about-1 ℃, this loss factor (as shown by tan delta value and T _g) being an improvement over the polymer layer of sheets EX2-S3 comprising standard PVB and triethylene glycol bis- (2-ethylhexanoate) plasticizer. Specifically, as shown, sheets EX2-S3 produced a peak tan delta of only about 1.1 at T _g of-1 ℃. Thus, the polymer layers (i.e., sheets EX2-S1 and EX 2-S2) comprising PVAc and poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer exhibit an increase in peak tan delta and/or loss factor of greater than 100% at or near T _g relative to a similar PVB formulation (i.e., sheets EX 2-S3).

After obtaining the tan δ curve, two polymer layers, EX2-S1 and EX2-S3, were simulated to obtain sound loss transmission (STL) data in the case where the polymer layers were included in a laminated glass panel. Specifically, the polymer layer was modeled as a core layer in three layers (i.e., skin// core// skin) sandwiched between a pair of glass sheets. An STL model is built and simulated by means of a finite element software tool COMSOL. The STL model is a two-dimensional model as shown in fig. 5. In this model, the glass panels included a "2.3mm glass sheet-0.355 mm skin (PVB) -0.11mm core-0.355 mm skin (PVB) -2.3mm glass sheet" laminate that was embedded in an infinite air space (an infinite space was built by applying a perfect matching layer). Frequency dependent parameters of both EX2-S1 (PVAc) and EX2-S3 (PVB) measured by DMA were applied to the model. The STL of the diffuse sound STL _d field is calculated by the following equation (4):

wherein, Is the sound intensity transmission coefficient, θ is the angle of the incident plane wave, p _t is the transmitted sound pressure, and p _i is the incident sound pressure. The incident angle is assumed to be uniformly distributed between 0 deg. and 78 deg. (radian 1-1.361). The integral is calculated by Simpson's law using MATLAB software.

The resulting simulated STL data is graphically shown in fig. 6. From the STL data, it can be seen that the coincidence frequency of the laminated glass panel with PVAc core (i.e., EX 2-S1) is shifted to a lower frequency relative to the laminated glass panel with PVB core (i.e., EX 2-S3). This is probably because PVAc is generally harder than our current PVB above 100 Hz. Regardless, the STL performance of laminated glass panels with PVAc core is lower at low frequencies (i.e., frequencies below 4400 Hz). However, at frequencies higher than the coincidence frequency of the laminated glass panels with PVB core (i.e., EX 2-S3), the STL of the laminated glass panel with PVAc core (i.e., EX 2-S1) has a 2+db improvement over the laminated glass panel with PVB core. This result may be due to the fact that both the damping and stiffness of PVAc are greater than those of PVB.

Example 3

Four polymer sheets were formed and Dynamic Mechanical Analysis (DMA) tests were used to determine tan delta values for the sheets over a range of temperatures. The first sheet "EX3-S1" was formed from 500K Dalton PVAc single polymer resin with 60phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. The second sheet, "EX3-S2", is formed from a 500K Dalton PVAc single polymer resin with 60phr poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. The third sheet, "EX3-S3", is formed from a 500K Dalton PVAc single polymer resin with 62.5phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. Finally, a fourth sheet "EX3-S4" is formed from a PVB resin of 50,000 to 600,000 daltons (comprising 10.5wt% PVOH, 2.0wt% PVAc, and 87.5wt% PVB) with 75phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each of the EX3-S1, EX3-S2, EX3-S3, EX3-S4 sheets is produced from a resin via a compression molding technique that includes forming the sheet using a steam heated press. Tan delta measurements were performed on sheet samples dried overnight in a desiccator. The test uses torsional and tensile mode Dynamic Mechanical Analysis (DMA). The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-20 to 60 ℃. The frequency dependent parameters were obtained using a "time-temperature superposition" in which DMA was performed from 0.3rad/s to 300rad/s at-20 ℃, -10 ℃,0 ℃,10 ℃,20 ℃, 30 ℃, 40 ℃ and 60 ℃ for each sample.

The resulting tan delta curves for each of the four polymer layers, sheets EX3-S1, EX3-S2, EX3-S3, and EX3-S4 are shown in FIG. 7. As shown, sheets EX3-S1 and EX3-S2, each comprising PVAc resin and 60phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer, produced a peak tan delta of about 2.2 at T _g of about-1 ℃. Sheets EX3-S3 comprising PVAc resin and 62.5phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer produced a slightly greater peak tan delta of about 2.3 at a slightly lower T _g of about-2 ℃. Each of the loss factors measured (as indicated by tan delta values and T _g) is an improvement to the polymer layer of sheets EX3-S4 comprising standard PVB and triethylene glycol di- (2-ethylhexanoate) plasticizer. Specifically, as shown, sheets EX3-S4 produced a peak tan delta of only about 1.1 at T _g at-1 ℃. Thus, the polymer layers (i.e., sheets EX3-S1, EX3-S2, and EX 3-S3) comprising PVAc and poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer exhibit an increase in peak tan delta and/or loss factor of greater than 100% at or near T _g relative to a similar PVB formulation (i.e., sheets EX 3-S4).

After obtaining the tan δ graph, three polymer sheets, that is, EX3-S1, EX3-S3, and EX3-S4, were simulated to obtain sound loss transmission (STL) data in the case where the polymer sheets were included in laminated glass panels. Specifically, using the STL model described in example 2 above, the polymer sheet was simulated as part of a laminated glass panel, and the resulting simulated STL data is shown in fig. 8.

From the STL data, it can be seen that the STL loss of the laminated glass panel with PVAc with 60phr plasticizer core (i.e., EX 3-S1) was lower than 4400Hz relative to the laminated glass panel with PVB core (i.e., EX 3-S4), whereas the laminated glass panel with PVAc with 62.5phr plasticizer (i.e., EX 3-S3) was absent. The result may be that the overlapping frequencies of laminated glass panels (i.e., EX 3-S3) with PVAc and 62.5phr plasticizer are shifted to higher frequencies due to 62.5phr PVAc being softer than 60phr PVAc. This offset was such that the STL performance of the laminated glass panels with PVAc and 62.5phr plasticizer (i.e., EX 3-S3) at low frequencies (below the coincidence frequency) was similar to the performance level of the laminated glass panels with PVB core (i.e., EX 3-S4).

At 4400Hz and above, laminated glass panels with PVAc and 62.5phr plasticizer (i.e., EX 3-S3) provided a 2dB improvement over laminated glass panels with PVB core (i.e., EX 3-S4). This result may be due to the much higher damping characteristics of PVAc than PVB. For frequencies greater than 4400Hz, the STL curve of 60phr of plasticizer core (i.e., EX 3-S1) overlaps a laminated glass panel with PVAc and 62.5phr of plasticizer (i.e., EX 3-S3). This result may be due to the higher damping of PVAc with 62.5phr plasticizer than PVAc with 60phr plasticizer, and the higher damping of laminated glass panels (i.e., EX 3-S3) with PVAc with 62.5phr plasticizer in this frequency range compensates for STL losses caused by the modulus decrease.

Example 4

As provided in table 1 below, eight exemplary hybrid PVAc resin samples were formed, hybrid resin samples ("HRS") 1-8, each having different amounts of acetate content, hydroxyl content, and aldehyde content. The percent hydrolysis used to form the samples is also provided for each sample.

TABLE 1

Sample of	Hydrolysis%	wt％PVAc	wt％PVB	wt％PVOH
					HRS-1	17.4	88.7	4.4	6.9
HRS-2	21.5	84.7	9	6.3
					HRS-3	31.4	76	16.5	7.5
HRS-4	62.1	44.6	47.5	7.9
					HRS-5	61.0	45.4	47.5	7
HRS-6	33.4	72.8	22.5	4.7
					HRS-7	37.2	70	23.2	6.8
HRS-8	47.0	59.9	33.9	6.2

Sub-example 4A

Three polymer sheets were formed and Dynamic Mechanical Analysis (DMA) tests were used to determine tan delta values for the sheets over a range of temperatures. The first sheet, "EX4A-S1", was formed from the HRS-2 sample resin with 63.4phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. The second layer, "EX4A-S2", was formed from the HRS-4 sample resin with 59.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Finally, a third sheet "EX4A-S3" is formed from a PVB resin of 50,000 to 600,000 daltons (comprising 10.5wt% PVOH, 2.0wt% PVAc, and 87.5wt% PVB) with 75phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each of the EX4A-S1, EX4A-S2, and EX4A-S3 sheets is produced from a resin via a compression molding technique that includes forming the sheets using a steam heated press. Tan delta measurements were performed on sheet samples dried overnight in a desiccator. The test uses torsional and tensile mode Dynamic Mechanical Analysis (DMA). The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-20 to 60 ℃. Frequency dependent parameters were obtained using "time-temperature superposition" in which DMA was performed from 0.3rad/s to 300rad/s at-20 ℃, -10 ℃,0 ℃,10 ℃,20 ℃, 30 ℃, 40 ℃ and 60 ℃ for each sample.

Three polymer layers, the tan delta curves for each of sheets EX4A-S1, EX4A-S2 and EX4A-S3, are shown in FIG. 9. As shown, sheets EX4A-S1 (formed from the hybrid PVAc resin) produced a peak tan delta of about 1.88 at T _g about-6℃and sheets EX4A-S2 (also formed from the hybrid PVAc resin) produced a slightly smaller peak tan delta of about 1.66 at slightly higher T _g of about-0.4 ℃. Each measured loss factor (as shown by tan delta value and T _g) is an improvement over the polymer layer of sheets EX4A-S3 comprising a standard PVB resin with triethylene glycol di- (2-ethylhexanoate) plasticizer. Specifically, as shown, the peak tan delta generated by sheets EX4A-S3 at T _g at-1℃is only about 1.1. Thus, the polymer layers (i.e., sheets EX4A-S1 and EX 4A-S2) comprising the hybrid PVAc and poly (ethylene glycol) bis (2-ethylhexanoate) or triethylene glycol bis- (2-ethylhexanoate) plasticizer exhibit an increase in peak tan delta and/or loss factor relative to a similar PVB formulation (i.e., sheets EX 4A-S3) that is the same or near T _g.

Although not shown in fig. 9, two additional polymer sheets were produced with HRS-2 and HRS-4 resin samples and tested in the same manner as described above. In particular, the fourth sheet "EX4A-S4" was formed from the HRS-2 sample resin with 68.7phr of poly (ethylene glycol) bis (2-ethylhexanoate) plasticizer. The fifth sheet, "EX4A-S5", was formed from the HRS-4 sample resin with 55.6phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each sheet was tested using the DMA method described above. EX4A-S4 sheet produced a tan delta peak of about 1.8 at T _g of about-7 ℃. EX4A-S5 sheet produced a tan delta peak of about 1.64 at T _g of about 1 ℃. Thus, the EX4A-S4 and EX4A-S5 sheets demonstrate that the hybrid PVAc polymer layer exhibits improved tan delta peak and/or loss factor values compared to standard PVB formulations.

Sub-example 4B

Three-layer polymer interlayers were formed and tested using the DMA method described in more detail below to determine the tan delta value of the interlayers. The two polymer interlayers included a core layer formed from the hybrid PVAc samples described above in example 4B. In particular, a first polymer interlayer "EX4B-S1" was laminated using a core layer composed of the HRS-4 sample resin with 59.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. The core layer is formed to a thickness of about 18mm. Each skin layer of EX4B-S1 contained PVB resin (containing 21.1wt% pvoh, 2.0wt% pvac, and 87.5wt% PVB) and 36.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each skin layer has a thickness of about 0.32mm. Similarly, a core layer composed of HRS-4 sample resin with 55.6phr of triethylene glycol di- (2-ethylhexanoate) plasticizer was used to laminate a second polymer interlayer "EX4B-S2". The core layer is formed to a thickness of about 18mm. Each skin layer of EX4B-S2 contained PVB resin (containing 18.7wt% pvoh, 2.0wt% pvac, and 87.5wt% PVB) with 36.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each skin layer has a thickness of about 0.32mm. In addition, a third polymer interlayer "EX4B-S3" was laminated using a core layer composed of PVB resin (comprising 10.5wt% PVOH, 2.0wt% PVAc, and 87.5wt% PVB). The core layer is formed to a thickness of about 11mm. Each skin layer of EX4B-S3 contained PVB resin (comprising 18.7wt% pvoh, 2.0wt% pvac, and 87.5wt% PVB) and 38phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. Each skin layer has a thickness of about 0.35mm.

Each of the polymer interlayers EX4B-S1-EX4B-S3 was tested using DMA to determine the tan delta value of the interlayer over a range of temperatures. Tan delta measurements were performed on sandwich samples dried overnight in a desiccator. The test uses torsion and tension mode DMA. The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-20 to 60 ℃. Frequency dependent parameters were obtained using "time-temperature superposition" in which DMA was performed from 0.3rad/s to 300rad/s at-20 ℃, -10 ℃,0 ℃,10 ℃, 20 ℃, 30 ℃, 40 ℃ and 60 ℃ for each sample.

The tan delta curves of each of the three resulting three-layer polymer interlayers EX4B-S1-EX4B-S3 are shown in FIGS. 10 and 11. In particular, the tan delta curves of EX4B-S1 and EX4B-S3 are shown in FIG. 10, while the tan delta curves of EX4B-S1 and EX4B-S2 are shown in FIG. 11. As shown in fig. 10, interlayers EX4B-S1 (formed from a core layer comprising a hybrid PVAc resin) produced a peak tan delta of about 1.59 at T _g at about 3 ℃, while interlayers EX4B-S3 (formed from a core layer comprising a standard PVB resin) produced a peak tan delta of about 1.17 at T _g at about 4 ℃. Thus, the measured loss factor (as shown by tan delta value and T _g) of the interlayer formed from the core layer comprising hybrid PVAc is improved compared to the interlayer formed from the core layer comprising standard PVB. In particular, a three-layer interlayer having a core layer comprising hybrid PVAc (i.e., interlayer EX 4B-S1) exhibits an increase in peak tan delta and/or loss factor at or near T _g relative to a three-layer interlayer having a standard PVB core layer (i.e., interlayer EX 4B-S3).

Turning to FIG. 11, as discussed above, this plot reproduces the tan delta curve of the EX4B-S1 interlayer (formed from a core layer comprising the hybrid PVAc resin HRS-4 with 59.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer) and shows the tan delta curve of the EX4B-S2 interlayer (formed from a core layer comprising the hybrid PVAc resin HRS-4 with 55.6phr of triethylene glycol di- (2-ethylhexanoate) plasticizer). Thus, the EX4B-S1 interlayer has slightly more plasticizer in its core than the EX4B-S2 interlayer. As shown, the interlayer EX4B-S1 produced a peak tan delta of about 1.59 at T _g of about 3 ℃, while the interlayer EX4B-S2 produced a peak tan delta of about 1.37 at T _g of about 9 ℃. Thus, the measured loss factor (as shown by tan delta value and T _g) of an interlayer formed from a core layer comprising hybrid PVAc having a greater amount of plasticizer is improved compared to an interlayer formed from a core layer comprising hybrid PVAc having a lesser amount of plasticizer. Specifically, a three-layer interlayer (i.e., interlayer EX 4B-S1) having a core layer comprising hybrid PVAc and 59.5phr plasticizer exhibited an increase in peak tan δ and/or loss factor at the same or near T _g relative to a three-layer interlayer (i.e., interlayer EX 4B-S2) having a core layer comprising hybrid PVAc and 55.6phr plasticizer.

Sub-example 4C

After obtaining the tan δ curves of the EX4A-S2 and EX4A-S3 sheets described in sub-example 4A, the sheets were simulated to obtain sound loss transmission (STL) data in the case where the polymer from the polymer sheet was contained in a laminated glass panel. Specifically, the polymer from the polymer sheet was generally modeled as part of a laminated glass panel using the STL model described in example 2 above. Frequency dependent parameters of EX4A-S2 and EX4A-S3 sheets measured by DMA in sub-example 4A were applied to each model. Fig. 12-15 show the resulting simulated STL data.

In more detail, a first simulation, "EX4C-S1", was performed with the polymer from the EX4A-S2 sheet to form a core layer simulating the three-layer polymer interlayer included in the laminated glass panel. The core layer was modeled as having a thickness of 0.22 mm. The skin layer of the three layer polymeric interlayer was modeled as comprising a standard PVB resin (comprising 21.1wt% pvoh, 2.0wt% pvac, and 87.5wt% PVB) with 36.5phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. The skin layers were each modeled as having a thickness of 0.3 mm. The second simulation, "EX4C-S2", was performed with the same parameters as EX4C-S1 described above, except that the core layer was modeled as 0.18mm and each skin layer was modeled as having a thickness of 0.32 mm. The third simulation, "EX4C-S3", was performed with the polymer from the EX4A-S3 sheet, forming a core layer simulating the three-layer polymer interlayer included in the laminated glass panel. The core layer was modeled as having a thickness of 0.11 mm. The skin layer of the three layer polymeric interlayer was modeled as comprising a standard PVB resin (including 18.7wt% pvoh, 2.0wt% pvac, and 87.5wt% PVB) with 38phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. The skin layers were each modeled as having a thickness of 0.355 mm. The simulation models of EX4C-S1, EX4C-S2, and EX4C-S3 are identical to the STL model described above in example 2, except as provided in this paragraph. Simulated curves of STL data for EX4C-S1, EX4C-S2 and EX4C-S3 are shown in FIGS. 12 and 13.

Finally, a fourth simulation, "EX4C-S4", was performed with the same parameters as EX4C-S2 described above, except that the skin layer of the three-layer polymer interlayer was modeled to contain standard PVB resin (containing 22.3wt% PVOH, 2.0wt% PVAc, and 87.5wt% PVB) with 34.7phr of triethylene glycol di- (2-ethylhexanoate) plasticizer. The simulation model of EX4C-S4 is identical to the STL model described above in example 2, except as provided in this paragraph. Simulated curves of STL data for EX4C-S2, EX4C-S3 and EX4C-S4 are shown in FIGS. 14 and 15.

From the STL data, it can be seen that forming the hybrid PVAc (i.e., EX4C-S1, EX4C-S2, and EX 4C-S4) laminated glass panels in the core layer provides an improvement in sound damping over laminated glass panels with a standard PVB core layer (i.e., EXC 4-S3). In more detail, referring to fig. 12, each laminated glass panel has substantially equivalent sound damping characteristics at frequencies below 4400 Hz. However, the glass panels with hybridized PVAc in the core layer (i.e., EX4C-S1 and EX 4C-S2) provided improvements over laminated glass panels with standard PVB core layers (i.e., EXC 4-S3). Fig. 13 shows the STL difference between laminated glass panels. As shown, for frequencies above 4400Hz, the EX4C-S1 glass panel provides an improvement of approximately 0.6 to 1.1dB when compared to the EX4C-S3 glass panel. For frequencies above 4400Hz, the EX4C-S2 glass panel provides an improvement of about 1.1 to 2.6dB when compared to the EX4C-S3 glass panel.

Similarly, referring to fig. 14, each laminated glass panel has substantially equivalent sound damping characteristics at frequencies below 4400 Hz. However, the glass panels with hybridized PVAc in the core layer (i.e., EX4C-S2 and EX 4C-S4) provided improvements over laminated glass panels with standard PVB core layers (i.e., EXC 4-S3). Fig. 15 shows the STL difference between laminated glass panels. As shown, for frequencies above 4400Hz, the EX4C-S2 glass panel provides an improvement of about 1.1 to 2.6dB over the EX4C-S3 glass panel for frequencies above 4400 Hz. For frequencies above 4400Hz, the EX4C-S4 glass panel provides an improvement of about 1.6 to 2.2dB when compared to the EX4C-S3 glass panel.

Sub-example 4D

Five-layer polymer interlayers "EX4D-S1" were formed and tested using the DMA method described in more detail below to determine the tan delta value of the interlayer. The EX4D-S1 interlayer is formed with a core layer consisting essentially of PVAc. The thickness of the core layer is about 0.05mm. The EX4D-S1 sandwich includes a pair of skins on either side of a core. The skin layers consisted essentially of PVB, each having a thickness of about 0.10mm. The EX4D-S1 sandwich also includes a pair of tie layers, each tie layer being located between the core layer and one of the skin layers. The tie layers consisted of HRS-2 sample resins (provided in table 1), each tie layer having a thickness of about 0.05mm. Each polymer layer of the EX4D-S1 interlayer was plasticized with poly (ethylene glycol) bis (2-ethylhexanoate).

Five-layer polymer interlayers EX4D-S1 were tested using DMA to determine tan delta values for the interlayers over a range of temperatures. Tan delta measurements were performed on sandwich samples dried overnight in a desiccator. The test uses torsion and tension mode DMA. The samples were tested using a rheosolids analyzer at an oscillation frequency of 1Hz in the temperature range of-20 to 60 ℃. Frequency dependent parameters were obtained using "time-temperature superposition" in which DMA was performed from 0.3rad/s to 300rad/s at-20 ℃, -10 ℃,0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃ and 60 ℃ for each sample.

The resulting tan delta curves for each of the five-layer polymer interlayers EX4D-S1 and EX4B-S3 described above (a standard three-layer interlayer formed substantially from PVB) are shown in fig. 16. As shown, the five-layer interlayer EX4D-S1 produced a peak tan delta of about 1.53 at T _g at about-3℃, while the standard interlayer EX4B-S3 (formed with a core layer comprising standard PVB resin) produced a peak tan delta of about 1.17 at T _g at about 4℃. Thus, the measured loss factor (as shown by tan delta values and T _g) for interlayers formed with five layers of interlayer (having a PVAc core, a hybrid PVAc tie layer, and a PVB skin layer) was improved over the loss factor for a standard three layer interlayer (having a PVB-containing core and skin layer). In particular, five-layer interlayers exhibit an increase in peak tan delta and/or loss factor relative to three-layer interlayers at or near T _g.

While the invention has been disclosed in connection with certain embodiments, including what is presently considered to be the preferred embodiments, the detailed description is intended to be illustrative, and should not be construed as limiting the scope of the disclosure. As will be appreciated by those of ordinary skill in the art, embodiments other than those described in detail herein are also encompassed by the present invention. Modifications and variations may be made to the described embodiments without departing from the spirit and scope of the invention.

It should also be understood that any range, value, or characteristic given for any single component of the disclosure may be used interchangeably with any range, value, or characteristic given for any other component of the disclosure, where compatible, to form embodiments having defined values for the components, as given throughout this document. For example, a polymer layer may be formed that includes any given range of plasticizer content in addition to any given range of residual hydroxyl content, where appropriate, to form many permutations within the scope of the present invention, but this will be difficult to list.

Claims

1. A polymer interlayer having improved acoustic properties, the polymer interlayer comprising:

A first polymer layer;

A second polymer layer; and

The third layer of polymer is formed from a blend of a first polymer and a second polymer,

Wherein the first polymer layer is located between the second polymer layer and the third polymer layer,

Wherein the first polymer layer is formed from a resin comprising polyvinyl acetate (PVAc), wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

2. A polymer interlayer, comprising:

A first polymer layer;

A second polymer layer; and

Wherein the first polymer layer is formed from a hybrid resin comprising polyvinyl acetate (PVAc), wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.5.

3. The polymer interlayer of claim 1 or claim 2, wherein the polymer interlayer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 1.3.

4. The polymer interlayer of claim 1, wherein the peak tan delta of the first polymer layer is from 2.0 to 3.5.

5. The polymer interlayer of claim 2, wherein the peak tan δ of the first polymer layer is from 1.5 to 2.0.

6. The polymer interlayer of any of claims 1-5, wherein the first polymer layer has a T _g of-5 ℃ to 5 ℃, or wherein the first polymer layer has a T _g of-10 ℃ to 10 ℃, or wherein the first polymer layer has a T _g of 0 ℃ to 10 ℃, or wherein the polymer interlayer has a T _g of less than 0 ℃, or wherein the polymer interlayer has a T _g of 0 ℃ to 10 ℃.

7. The polymer interlayer of any of claims 1-6, wherein the resin of the first polymer layer comprises a glyceryl plasticizer and/or a ethylene glycol diester plasticizer.

8. The polymer interlayer of claim 7, wherein the resin comprises 50phr to 70phr of the plasticizer, or wherein the plasticizer of the first polymer layer comprises tributyrin, or wherein the plasticizer of the first polymer layer comprises a diester having four or more ethylene glycol repeat units, or wherein the plasticizer of the first polymer layer comprises a molecule having an oxygen to carbon ratio of at least 0.32, or wherein the plasticizer of the first polymer layer comprises an ethylene glycol diester, and wherein the plasticizer has a molecular weight of at least 420 daltons, or wherein the plasticizer of the first polymer layer has a total solubility parameter δ _tot consisting of contributions from a self-dispersing solubility parameter δ _d, a polar solubility parameter δ _p, and a hydrogen bond solubility parameter δ _h, wherein the ratio of contributions from the polar solubility parameter δ _p and the hydrogen bond solubility parameter δ _h relative to the total solubility parameter δ _tot is at least 0.365.

9. The polymer interlayer of any of claims 1 to 8, wherein T _g of the first polymer layer is less than T _g of both the second polymer layer and the third polymer layer.

10. The polymer interlayer of any of claims 1 to 9, wherein the resin comprises 40wt% to 80wt% acetate content, 5wt% to 20wt% hydroxyl content, and 20wt% to 40wt% aldehyde content.

11. The polymer interlayer of any of claims 1 to 10, wherein said first polymer layer consists essentially of polyvinyl acetate (PVAc).

12. The polymer interlayer of any of claims 1 to 11, wherein said second polymer layer and said third polymer layer are tie layers comprising hybrid polyvinyl acetate (PVAc).

13. The polymer interlayer of any of claims 1 to 12, further comprising a fourth polymer layer and a fifth polymer layer, wherein the second polymer layer is located between the first polymer layer and the fourth polymer layer, and wherein the third polymer layer is located between the first polymer layer and the fifth polymer layer.

14. The polymer interlayer of claim 13, wherein the fourth polymer layer and the fifth polymer layer are skin layers consisting essentially of poly (vinyl butyral) (PVB).

15. A method of forming a polymer interlayer having improved acoustic properties, the method comprising the steps of:

(a) Extruding a first polymer melt to form a first polymer layer; and

(B) Extruding the second polymer melt to form a second polymer layer and a third polymer layer;

Wherein upon said extrusion of steps (a) and (b), said first polymer layer is located between said second polymer layer and said third polymer layer,

Wherein the first polymer melt comprises a resin comprising polyvinyl acetate (PVAc), and wherein the first polymer layer has a T _g of less than about 20 ℃ and a peak tan delta of greater than about 2.0.

16. The method of claim 15, wherein the extruding of steps (a) and (b) is via coextrusion, wherein the peak tan delta of the first polymer layer is from 2.0 to 3.5, and wherein the T _g of the first polymer layer is from-5 ℃ to 5 ℃.

17. The method of claim 15 or claim 16, wherein the resin comprises a glyceryl plasticizer and/or a glycol diester plasticizer.

18. The method of any of claims 15-17, wherein the resin comprises 50phr to 70phr of the plasticizer, or wherein the plasticizer of the first polymer layer comprises tributyrin, or wherein the plasticizer of the first polymer layer comprises a diester having four or more ethylene glycol repeat units, or wherein the plasticizer of the first polymer layer comprises a molecule having an oxygen to carbon ratio of at least 0.32, or wherein the plasticizer of the first polymer layer comprises an ethylene glycol diester, and wherein the plasticizer has a molecular weight of at least 420 daltons, or wherein the plasticizer of the first polymer layer has a total solubility parameter delta _tot consisting of contributions from a self-dispersion solubility parameter delta _d, a polar solubility parameter delta _p, and a hydrogen bond solubility parameter delta _h, wherein the ratio of contributions from the polar solubility parameter delta _p and the hydrogen bond solubility parameter delta _h relative to the total solubility parameter delta _tot is at least 0.365.

19. The method of any one of claims 15-18, wherein T _g of the first polymer layer is less than T _g of both the second polymer layer and the third polymer layer.

20. The method of any one of claims 15-19, wherein the resin comprises an acetate content of 50wt% to 80wt%, a hydroxyl content of 5wt% to 20wt%, and an aldehyde content of 10wt% to 45 wt%.