Salt-reduced polymer interlayer

Abstract

A polymeric interlayer that resists the formation of optical defects. The polymeric interlayer comprises a first polymeric layer (14), a second polymeric layer (16), and a third polymeric layer (16). The first polymeric layer (14) is positioned between the second polymeric layer (16) and the third polymeric layer (16). The first polymeric layer (14) comprises a resin that includes (i) a monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

Description

[Technical field]

[0001]

[0001] The present invention relates to the field of polymeric interlayers and multilayer panels comprising polymeric interlayers, more particularly to the field of polymeric interlayers comprising multiple polymer layers. [Background technology]

[0002]

[0002] A multi-ply panel is comprised of two sheets of substrate (such as, but not limited to, glass, polyester, polyacrylate, or polycarbonate) sandwiched between them with one or more polymer interlayers. Laminated multi-ply glass panels are commonly utilized for architectural window applications and automotive and aircraft windows, as well as photovoltaic solar panels. The first two applications are commonly referred to as laminated safety glass. The primary functions of the interlayer in laminated safety glass are to absorb energy resulting from an impact or force applied to the glass, to keep the layers of glass bonded together even if a force is applied to the glass and the glass breaks, and to prevent the glass from shattering into sharp shards. In addition, the interlayer can impart a preferential sound insulation 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 that result in quieter interior spaces.

[0003]

[0003] Additionally, laminated glass panels are used in vehicles equipped with head-up display ("HUD") systems (also called head-up systems) that project an image of the instrument cluster or other important information onto a location on the windshield at eye level of the vehicle operator. Such displays allow the driver to visually access dashboard information while still remaining focused on the road ahead. Typically, HUD systems in automobiles or aircraft use the inner surface of the vehicle windscreen to partially reflect the projected image. However, a secondary reflection occurs at the outer surface of the vehicle windscreen, which forms a weak secondary or "ghost" image. Because these two reflected images are offset in position, double images are often observed, which results in an undesirable viewing experience for the driver. When an image is projected onto a windshield having a uniform, constant thickness, a coherent double or reflected ghost image is formed due to the difference in the position of the projected image as it is reflected from the inner and outer surfaces of the glass.

[0004] One way to address these double or ghost images is to orient the inner and outer glass sheets at an angle to one another. This aligns the location of the reflected images to a single point, thereby forming a single image. Typically, this is done by offsetting the outer sheet relative to the inner sheet through the use of a wedge-shaped or "tapered" interlayer that contains at least one region of non-uniform thickness. Many conventional tapered interlayers contain a constant wedge angle across the entire HUD area, but more recently, some interlayers have been developed that contain multiple wedge angles across the HUD area.

[0005]

[0005] It has become common practice to utilize multiple plies or multi-layer interlayers to achieve the required properties and performance characteristics of glass panels. As used herein, the terms "multi-layer" and "multi-layer" refer to interlayers having two or more layers, and multi-layer and multi-layer may be used interchangeably. Multi-layer interlayers typically contain at least one soft layer and at least one hard layer. As mentioned above, interlayers have been designed with one soft "core" layer sandwiched between two stiffer or harder "skin" layers that have the acoustic properties of the glass panel. The reverse configuration, i.e., interlayers with one hard layer sandwiched between two or more soft layers, have been found to improve the impact performance of glass panels and may also be designed for acoustic insulation. In either case, the soft "core" layer is generally referred to as the acoustic layer (because the soft layer beneficially reduces sound transmission), while the hard "skin" layer is referred to as the conventional layer, or non-acoustic layer.

[0006]

[0006] The layers of the interlayer are generally produced by mixing a polymeric resin, such as poly(vinyl butyral), with one or more plasticizers and melt processing the mixture into a sheet by any applicable process or method known to those skilled in the art, including but not limited to extrusion, and the layers are combined by processes such as coextrusion and lamination. In a three-ply interlayer, the core layer may contain more plasticizer than the skin layers, such that the core layer is softer than the relatively harder skin layers. Other additional ingredients, described in more detail below, may optionally be added for various other purposes. After the interlayer sheet is formed, the interlayer sheet is typically collected and rolled for shipping and storage, as well as for later use in multi-ply glass panels, as discussed below.

[0007]

[0007] The following provides a simplified description of the manner in which a multi-layer glass panel is typically manufactured in combination with an interlayer. First, a multi-layer interlayer may be coextruded using a multi-manifold coextrusion device. The device operates by simultaneously extruding a polymer melt from each manifold toward an extrusion orifice. The properties of the layers may be varied by adjusting the attributes of the die lip at the extrusion orifice (e.g., temperature and / or orifice size). Once formed, the interlayer sheet may be placed between two glass substrates, and any excess interlayer is trimmed from the edges to form an assembly. It is not uncommon for multiple polymer interlayer sheets or a polymer interlayer sheet having multiple layers (or a combination of both) to be placed between two glass substrates to form a multi-layer glass panel having multiple polymer interlayers. Air is then removed from the assembly by an applicable process or method known to one skilled in the art, for example, via a nip roller, vacuum bag, or another degassing mechanism. Furthermore, the interlayer is partially pressed to the substrate by any method known to one skilled in the art. In a final step, this preliminary bond is made more permanent by a high temperature and pressure lamination process or any other method known to those skilled in the art, such as, but not limited to, autoclaving, to form the final integral structure.

[0008]

[0008] Multi-layer interlayers, such as tri-ply interlayers having a soft core layer and two harder skin layers, are known to provide beneficial acoustic attenuation properties. However, such interlayers, and glass panels containing these interlayers, may develop optical defects commonly known as "bubbles." Specifically, during the manufacturing process of the interlayer and / or laminated multi-ply glass panel construction, bubbles typically appear within the soft core of the interlayer. Often, such bubbles are in the form of trim or edge bubbles, which appear near the edge of the interlayer in the laminated panel. Specifically, edge bubbles are bubbles that form within about 5 mm of the edge of the interlayer in the laminated glass panel, particularly the edge of the glass sheet of the glass panel. Trim bubbles are bubbles that form in the excess trim portion of the interlayer that extends beyond the edge of the glass sheet of the glass panel. Most of these bubbles become visible once the autoclave pressure is released. For example, bubble nucleation may occur inside the core layer after the pressure of the polymer drops below the melt pressure. Other variables known to contribute to bubble problems include the composition of the interlayer, the presence of environmental contamination, and / or the rheological properties of the interlayer.

[0009] In addition to the above, polymer interlayers, and / or laminated glass panels comprising polymer interlayers, can often exhibit other optical defects. For example, conventional polymer interlayer materials can yellow significantly after manufacture of the interlayer or after lamination of the interlayer as part of a glass panel.

[0010] In view of the above, there is a need in the art to develop a multi-layer interlayer that resists the formation of optical defects (i.e., yellowing or bubble formation) without reducing other optical, mechanical and acoustic properties of conventional multi-layer 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 resists the occurrence of yellowing and / or bubbles (e.g., trim or edge bubbles). [Brief description of the drawings]

[0011] [Figure 1]

[0011] FIG. 1 is a schematic diagram of a laminated glass panel comprising a pair of glass sheets facing a polymer interlayer, the polymer interlayer comprising three layers, a pair of skin layers facing a core layer. [Diagram 2]

[0012] 1 is another schematic diagram of a laminated glass panel comprising a pair of glass plates facing a polymer interlayer, the polymer interlayer having a wedge shape. [Diagram 3]

[0013] FIG. 2 is a structural formula of an organic acid scavenger in the form of MCS1562. [Figure 4]

[0014] FIG. 2 is a structural formula of an organic acid scavenger in the form of DER732. Summary of the Invention [Means for solving the problem]

[0012]

[0015] One aspect of the present invention relates to a polymeric interlayer that is resistant to the formation of optical defects. The polymeric interlayer comprises a first polymeric layer, a second polymeric layer, and a third polymeric layer. The first polymeric layer is positioned between the second polymeric layer and the third polymeric layer. The first polymeric layer comprises a resin that includes (i) at least one monovalent alkali metal salt having a titer of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0013]

[0016] Another aspect of the invention relates to a polymeric interlayer that is resistant to the formation of optical defects. The polymeric interlayer comprises a core layer, a first skin layer, and a second skin layer. The core layer is positioned between the first skin layer and the second skin layer. The core layer comprises a resin that includes (i) at least one monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0014]

[0017] Another aspect of the invention relates to a method of forming a polymeric interlayer that is resistant to the formation of optical defects. The method includes extruding a first polymer melt to form a first polymer layer, and extruding a second polymer melt to form a second polymer layer and a third polymer layer. During the extrusion step, the first polymer layer is positioned between the second polymer layer and the third polymer layer. The first polymer layer includes a resin that includes (i) at least one monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0015]

[0018] An additional aspect of the invention relates to a laminated glass panel that resists the formation of optical defects. The laminated glass panel comprises a first glass sheet, a second glass sheet, and a polymer interlayer laminated between the first and second glass sheets. The polymer interlayer comprises a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being positioned between the second and third polymer layers. The first polymer layer comprises a resin that includes an alkali metal salt having a strength of about 35 or less, and the alkali metal salt having a strength of at least 5 is potassium acetate.

[0016]

[0019] A further aspect of the invention relates to another laminated glass panel that resists the formation of optical defects. The laminated glass panel comprises a first glass sheet, a second glass sheet, and a polymer interlayer positioned between the first and second glass sheets. The polymer interlayer comprises a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being positioned between the second and third polymer layers. The first polymer layer comprises a resin that includes an alkali metal salt having a strength of about 35 or less, and the alkali metal salt having a strength of at least 5 is potassium acetate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017]

[0020] The present invention relates to a multi-layer panel and a method for making a multi-layer panel. Generally, a multi-layer panel is composed of two sheets of glass or other applicable substrate with one or more polymer interlayer sheets sandwiched between them. A multi-layer panel is generally manufactured by placing at least one polymer interlayer sheet between the two substrates to form an assembly. Figure 1 shows a multi-layer panel 10 comprising a pair of glass sheets 12 and a multi-layer interlayer sandwiched therebetween. The multi-layer interlayer is configured as a three-layer interlayer having three separate polymer interlayer sheets, including a soft core layer 14 and two relatively hard skin layers 16 positioned on either side of the core layer 14.

[0018]

[0021] In some embodiments, the intermediate layer (e.g., the core layer 14 and the skin layer 16) have a substantially constant or uniform thickness over the length of the intermediate layer. However, in alternative embodiments, as shown in FIG. 2, the intermediate layer may have at least one region of non-uniform thickness. For example, the intermediate layer, comprised of the core layer 14 and the skin layer 16, may be wedge-shaped such that the thickness of the intermediate layer varies (e.g., linearly or non-linearly) over the length of the intermediate layer. In some such embodiments, the thickness of the intermediate layer may vary due to a change in the thickness of the core layer 14 (i.e., the skin layer 16 has a substantially constant thickness). Alternatively, the thickness of the intermediate layer may vary due to a change in the thickness of the skin layer 16 (i.e., the core layer 14 has a substantially constant thickness). In a further alternative, the thickness of the intermediate layer may vary due to a change in the thickness of both the core layer 14 and the skin layer 16.

[0019]

[0022] In order to facilitate a more comprehensive understanding of the interlayers and multilayer panels disclosed herein, the meanings of certain terms used in this application are defined. These definitions should not be construed as limiting these terms to those as understood by those skilled in the art, but merely as providing an improved understanding of how certain terms are used herein.

[0020]

[0023] The terms "polymer interlayer sheet", "interlayer", "polymer layer" and "polymer melt sheet" as used herein may refer to a monolayer sheet or a multilayer interlayer. A "monolayer sheet", as the name suggests, is a single polymer layer extruded as one layer. A multilayer interlayer, on the other hand, may comprise multiple layers, including separately extruded layers, coextruded layers, or any combination of separately extruded and coextruded layers. Thus, a multilayer interlayer may comprise, for example, two or more monolayer sheets combined with each other ("multilayer sheet"), two or more layers coextruded with each other ("coextruded sheet"), two or more coextruded sheets combined with each other, a combination of at least one monolayer 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, a multilayer interlayer comprises at least two polymer layers (e.g., monolayer or coextruded multilayer) arranged in direct contact with each other, each layer comprising at least one polymer resin. The term "resin" as utilized herein refers to the polymeric component (e.g., PVB) removed from the process, such as those discussed more fully below. Generally, a plasticizer, such as those discussed more fully below, is added to the resin to obtain a plasticized polymer. Furthermore, as discussed further herein, the resin may have other components in addition to the polymer and plasticizer, including, for example, acetates, salts, and alcohols. However, as discussed in more detail below, the polymeric interlayer formed in accordance with an embodiment of the present invention may have one or more layers formed with a resin having a reduced amount of alkali salt, more specifically, in some embodiments, a reduced amount of monovalent alkali metal salt (compared to a typical interlayer).

[0021]

[0024] It should also be noted that although poly(vinyl butyral) ("PVB") interlayers are often specifically discussed in this application as the polymer resin of the polymer interlayer, it should be understood that other thermoplastic interlayers other than PVB interlayers may be used. Contemplated polymers include, but are not limited to, polyurethane, polyvinyl chloride, poly(ethylene vinyl acetate), and combinations thereof. These polymers may be utilized alone or in combination with other polymers. Thus, when ranges, values, and / or methods are given in this application with respect to PVB interlayers (e.g., percentages of plasticizer components, thickness and feature-enhancing additives), those ranges, values, and / or methods also apply, where applicable, to other polymers and polymer blends disclosed herein, or may be modified to apply to different materials, as known to those skilled in the art.

[0022]

[0025] As used herein, the term "molecular weight" refers to weight average molecular weight (Mw). The molecular weight of the PVB resin may be in the range of about 50,000 to about 600,000, about 70,000 to about 450,000, or about 100,000 to about 425,000 Daltons.

[0023]

[0026] PVB resins can be produced by known aqueous or solvent acetalization processes by reacting polyvinyl alcohol ("PVOH") with butyraldehyde in the presence of an acid catalyst, isolating, stabilizing, and drying the resin. Such acetalization processes are disclosed, for example, in U.S. Pat. Nos. 2,282,057 and 2,282,026, and Wade, B. (2016), "Vinyl Acetal Polymers," Encyclopedia of Polymer Science and Technology, pp. 1-22 (John Wiley & Sons, Inc.), the disclosures of which are incorporated herein by reference in their entireties.

[0024]

[0027] Although generally referred to herein as "poly(vinyl acetal)" or "poly(vinyl butyral)," the resins described herein may contain residues of any suitable aldehyde, including, but not limited to, isobutyraldehyde. In some embodiments, the one or more poly(vinyl acetal) resins are selected from the group consisting of at least one C1-C 10 The aldehyde may include a residue of an aldehyde or at least one C4-C8 aldehyde. Examples of suitable C4-C8 aldehydes may include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylvaleraldehyde, n-hexylaldehyde, 2-ethylhexylaldehyde, n-octylaldehyde, and combinations thereof.

[0025]

[0028] In many embodiments, plasticizers are added to the polymer resin to form the polymer layer or interlayer. Plasticizers are generally added to the polymer resin to increase the flexibility and durability of the resulting polymer interlayer. The plasticizer embeds itself between the polymer chains, spacing them apart (increasing the "free volume") and thus increasing the glass transition temperature (T g ), making the material softer. In this regard, the amount of plasticizer in the interlayer is important in determining the glass transition temperature (T g The glass transition temperature (T g ) is the temperature which marks the transition from the glassy state to the rubbery state of the interlayer. Generally, a higher plasticizer loading results in a lower (T g In some embodiments, for example when the intermediate layer is an acoustic trilayer, the inner core layer (i.e., the soft layer) has a glass transition temperature less than about 20°C, while the outer skin layers (e.g., the hard layers) have a glass transition temperature greater than about 25°C.

[0026]

[0029] Contemplated plasticizers include, but are not limited to, esters of polybasic acids, polyhydric alcohols, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexonate) (known as "3-GEH"), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, mixtures of heptyl adipate and nonyl adipate, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and polymeric plasticizers such as oil-modified sebacic acid alkyds, and mixtures of phosphates and adipates, and mixtures and combinations thereof. 3-GEH is particularly preferred. Other examples of suitable plasticizers may include, but are not limited to, tetraethylene glycol di-(2-ethylhexanoate) ("4-GEH"), di(butoxyethyl)adipate, and bis(2-(2-butoxyethoxy)ethyl)adipate, dioctyl sebacate, nonylphenyl tetraethylene glycol, and mixtures thereof.

[0027]

[0030] Other suitable plasticizers may include blends of two or more different plasticizers, including but not limited to those mentioned above. Still other suitable plasticizers or blends of plasticizers may be formed from the aromatic family, such as polyadipates, epoxides, phthalates, terephthalates, benzoates, toluates, mellitates, and other specialty plasticizers. Further examples include, but are not limited to, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol benzoate isobutyrate, 1,3-butanediol dibenzoate, diethylene glycol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bis-phenol A bis(2-ethylhexanoate), ethoxylated nonylphenol, and mixtures thereof. In some embodiments, the plasticizer may be selected from the group consisting of dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, and combinations thereof.

[0028]

[0031] Generally, the plasticizer content of polymeric interlayers in this application is measured in parts per hundred parts of resin ("phr") on a weight / weight basis. For example, if 30 grams of plasticizer is added to 100 grams of polymer resin, the plasticizer content of the final plasticized polymer will be 30 phr. When the plasticizer content of polymeric layers is given in this application, the plasticizer content of a particular layer is determined with reference to the phr of plasticizer in the melt used to make that particular layer.

[0029]

[0032] According to some embodiments of the invention, one or more polymer layers described herein may have a total plasticizer content of at least about 20 phr, at least about 25 phr, at least about 30 phr, at least about 35 phr, at least about 38 phr, at least about 40 phr, at least about 45 phr, at least about 50 phr, at least about 55 phr, at least about 60 phr, at least about 65 phr, at least about 67 phr, at least about 70 phr, at least about 75 phr. In some embodiments, the polymer layer may also include no more than about 100 phr, no more than about 85 phr, no more than about 80 phr, no more than about 75 phr, no more than about 70 phr, no more than about 65 phr, no more than about 60 phr, no more than about 55 phr, no more than about 50 phr, no more than about 45 phr, no more than about 40 phr, no more than about 38 phr, no more than about 35 phr, or no more than about 30 phr of one or more plasticizers. In some embodiments, the total plasticizer content of at least one polymer layer may be in the range of about 20 to about 40 phr, about 20 to about 38 phr, or about 25 to about 35 phr. In other embodiments, the total plasticizer content of at least one polymer layer may be in the range of about 38 to about 90 phr, about 40 to about 85 phr, or about 50 to 70 phr.

[0030]

[0033] When the intermediate layer comprises a multi-layer intermediate layer, two or more polymer layers within the intermediate layer may have substantially the same plasticizer content, and / or at least one of the polymer layers may have a plasticizer content different from one or more of the other polymer layers. When the intermediate layer comprises two or more polymer layers with 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 phr, at least about 2 phr, at least about 5 phr, at least about 7 phr, at least about 10 phr, at least about 20 phr, at least about 30 phr, at least about 35 phr, and / or about 80 phr or less, about 55 phr or less, about 50 phr or less, or about 45 phr or less, or in the range of about 1 to about 60 phr, about 10 to about 50 phr, or about 30 to 45 phr. If there are three or more layers in the intermediate layer, at least two of the polymer layers in the intermediate layer may have similar plasticizer contents, for example, within 10 phr, within 5 phr, within 2 phr, or within 1 phr of each other, while at least two of the polymer layers may have different plasticizer contents from each other according to the above ranges.

[0031]

[0034] In some embodiments, one or more of the polymer layers or interlayers described herein may comprise a blend of two or more plasticizers, for example, including two or more of the plasticizers listed above. When a polymer layer comprises two or more plasticizers, the total plasticizer content of the polymer layer and the difference in the total plasticizer content between adjacent polymer layers may fall within one or more of the ranges above. When the interlayer is a multi-layer interlayer, one or more of the polymer layers may comprise two or more plasticizers. In some embodiments when the interlayer is a multi-layer interlayer, at least one of the polymer layers comprising a blend of plasticizers may have a glass transition temperature higher than that of a conventional plasticized polymer layer. This may provide additional hardness in some cases to a layer that may be used, for example, as an outer "skin" layer in a multi-layer interlayer.

[0032]

[0035] In addition to plasticizers, it is also contemplated that adhesion control agents ("ACAs") may be added to polymer resins to form polymer interlayers. When used in the outer layers of a monolithic or multilayer interlayer, ACAs generally function to modify and / or improve the adhesion of the interlayer to the glass panel in forming a laminate panel. Such ACAs may also be used to improve the overall stability of the resin, particularly when used in the inner or core layers. It is believed that metal salts function as acid scavengers when used in the inner or core layers. Contemplated ACAs or metal salts include salts such as, but not limited to, monovalent and polyvalent metal salts. Contemplated salts include, for example, magnesium / magnesium carboxylate salts, such as magnesium di-2-ethylhexanoate, magnesium bis-2-ethylbutyrate, or other organic magnesium salts. Contemplated ACAs may also include salts in the form of magnesium acetate (i.e., Mg(OAc)2). Still other contemplated ACAs include monovalent alkali metal salts in the form of potassium acetate (i.e., potassium salt of acetic acid acetate or "KOAc"). The following is an exemplary list of monovalent metal salts that may be used as ACAs according to embodiments of the present invention: potassium formate, potassium 2-ethylbutyrate, potassium 2-ethylhexanoate, sodium formate, sodium acetate, sodium 2-ethylbutyrate, sodium 2-ethylhexanoate, etc. The following is an exemplary list of polyvalent metal salts that may be used as ACAs according to embodiments of the present invention: magnesium formate, magnesium di-2-ethylhexanoate, magnesium salicylate, calcium formate, calcium acetate, calcium 2-ethylbutyrate, calcium 2-ethylhexanoate, etc. In addition, contemplated ACAs may further include ACAs disclosed in U.S. Patent No. 5,728,472, the entirety of which is incorporated herein by reference. It is understood that the ACAs included in the polymer resins and / or polymer interlayers discussed herein may include various combinations of the exemplary ACAs listed above.

[0033]

[0036] It is further contemplated that in addition to the plasticizer and metal salt, an organic acid scavenger may be added to the polymer resin used to form the polymer interlayer. The organic acid scavenger generally functions to neutralize the acid without forming a salt. However, the use of an organic acid scavenger in the polymer resin has also been found to stabilize the resin and the resulting polymer layer. More specifically, it has been understood that the presence of salt in the resin can, in some circumstances, result in the formation of optical defects such as yellowing and / or bubble formation. Such optical defects are believed to result from the formation of nucleation sites in the resin where the salt is located. The presence of salt in the resin can be the result of decomposition of the ACA (which is generally composed of salt), the plasticizer, decomposition of the resin, and / or oxidation of organic volatiles. However, simply removing the ACA or metal salt from the polymer resin can be problematic. As explained in more detail below, reducing the amount of ACA or metal salt used in the polymer resin can destabilize the resin and result in optical defects such as increased yellowing of the resulting polymer layer, polymer interlayer, and / or laminated glass panel. To address such optical defects, embodiments of the present invention incorporate the use of organic acid scavengers in the polymer resin in place of, or in addition to, metal salts. As described in more detail below, the use of such organic acid scavengers has been found to stabilize the polymer resin (and the resulting polymer layer and / or interlayer).

[0034]

[0037] In general, the organic acid scavenger may include epoxide derivatives, such as mono-epoxides, di-epoxides, and / or epoxidized vegetable oils. An example of a suitable mono-epoxide is 2-ethylhexyl epoxy cyclohexyl carboxylate, which is commercialized as MCS1562. FIG. 3 shows the structural formula of MCS1562. An example of a suitable di-epoxide is a liquid epoxy resin produced from the reaction of epichlorohydrin and polypropylene glycol, which is commercialized as DER732 by Dow Chemical Company. FIG. 4 shows the structural formula of DER732. Suitable epoxidized vegetable oils include soybean oil, linseed oil, and the like. Additionally, contemplated organic acid scavengers may also include epoxidized octyl stearate or epoxidized polybutadiene.

[0035]

[0038] Other additives may be incorporated into the polymer resins forming the polymer interlayer to improve performance in the final product and impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., UV stabilizers), antioxidants, antiblocking agents, flame retardants, IR absorbers or blockers (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB6), and cesium tungsten oxide), processing aids, flow promoters, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives, and fillers, among other additives known to those skilled in the art.

[0036]

[0039] One parameter used to describe the polymer resin components of the polymer interlayers of this application is the residual hydroxyl content (as vinyl hydroxyl content or poly(vinyl alcohol) ("PVOH") content). Residual hydroxyl content refers to the amount of hydroxyl groups remaining as side groups on the polymer chain after processing is completed. For example, PVB may be produced by hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol) and then reacting the poly(vinyl alcohol) with butyraldehyde to form PVB. In the hydrolysis process of poly(vinyl acetate), typically not all acetate side groups are converted to hydroxyl groups. Furthermore, typically not all hydroxyl groups are converted to acetal groups by reaction with butyraldehyde. As a result, in any final PVB, typically there are residual acetate groups (e.g., vinyl acetate groups) and residual hydroxyl groups (e.g., vinyl hydroxyl groups) as side groups on the polymer chain. In general, the residual hydroxyl content of a polymer may be adjusted by controlling reaction times and reactant concentrations, among other variables in the polymer manufacturing process. As used herein as a parameter, residual hydroxyl content is measured on a weight percent (wt.%) basis according to ASTM D-1396.

[0037]

[0040] In various embodiments, the poly(vinyl butyral) resin comprises from about 8 to about 35 wt.% residual hydroxyl groups, calculated as PVOH, from about 13 to about 30 wt.% residual hydroxyl groups, calculated as PVOH, from about 8 to about 22 wt.% residual hydroxyl groups, or from about 15 to about 22 wt.% residual hydroxyl groups, and in some cases of the high stiffness intermediate layers disclosed herein, in one or more of the layers, the poly(vinyl butyral) resin comprises greater than about 19 wt.% residual hydroxyl groups, calculated as PVOH, greater than about 20 wt.% residual hydroxyl groups, calculated as PVOH, greater than about 20.4 wt.% residual hydroxyl groups, and greater than about 21 wt.% residual hydroxyl groups, calculated as PVOH.

[0038]

[0041] In some embodiments, the poly(vinyl butyral) resin used in at least one polymer layer of the intermediate layer may comprise a poly(vinyl butyral) resin having a residual hydroxyl content, measured as described above, of at least about 18 wt.%, at least about 18.5 wt.%, at least about 18.7 wt.%, at least about 19 wt.%, at least about 19.5 wt.%, at least about 20 wt.%, at least about 20.5 wt.%, at least about 21 wt.%, at least about 21.5 wt.%, at least about 22 wt.%, at least about 22.5 wt.%, and / or no more than about 30 wt.%, no more than about 29 wt.%, no more than about 28 wt.%, no more than about 27 wt.%, no more than about 26 wt.%, no more than about 25 wt.%, no more than about 24 wt.%, no more than about 23 wt.%, or no more than about 22 wt.%.

[0039]

[0042] Furthermore, one or more other polymer layers in the intermediate layer described herein may comprise another poly(vinyl butyral) resin having a lower residual hydroxyl content. For example, in some embodiments, at least one polymer layer of the intermediate layer may comprise a poly(vinyl butyral) resin having a residual hydroxyl content of at least about 8 wt.%, at least about 8.5 wt.%, at least about 9 wt.%, at least about 9.5 wt.%, at least about 10 wt.%, at least about 10.5 wt.%, at least about 11 wt.%, at least about 11.5 wt.%, at least about 12 wt.%, at least about 13 wt.%, and / or about 16 wt.% or less, about 15 wt.% or less, about 14 wt.% or less, about 13.5 wt.% or less, about 13 wt.% or less, about 12 wt.% or less, or about 11.5 wt.% or less.

[0040]

[0043] When the intermediate layer includes two or more polymer layers, the layers may include poly(vinyl butyral) resins having substantially the same residual hydroxyl content, or the residual hydroxyl content of the poly(vinyl butyral) resins in each layer may differ from each other. When two or more layers include poly(vinyl butyral) resins having substantially the same residual hydroxyl content, the difference between the residual hydroxyl content of the poly(vinyl butyral) resins in each layer may be less than about 2 wt.%, less than about 1 wt.%, or less than about 0.5 wt.%. As used herein, the terms "weight percent different" and "the difference between is at least weight percent" refer to the difference between two given weight percentages calculated by subtracting one number from the other. For example, a poly(vinyl acetal) resin with a residual hydroxyl content of 12 wt.% has a residual hydroxyl content that differs by 2 wt.% from a poly(vinyl acetal) resin with a residual hydroxyl content of 14 wt.% (14 wt.%-12 wt.%=2 wt.%). As used herein, the term "different" can refer to a value that is higher or lower than another value. Unless otherwise specified, all "differences" herein refer to the numerical value of the difference and do not refer to the particular sign of the value resulting from the order in which the numbers are subtracted. Thus, unless otherwise noted, all "differences" herein refer to the absolute value of the difference between two numbers.

[0041]

[0044] When two or more layers comprise poly(vinyl butyral) resins having different residual hydroxyl contents, the difference between the residual hydroxyl contents of the poly(vinyl butyral) resins may be at least about 2 wt.%, at least about 3 wt.%, at least about 4 wt.%, at least about 5 wt.%, at least about 6 wt.%, at least about 7 wt.%, at least about 8 wt.%, at least about 9 wt.%, at least about 10 wt.%, at least about 12 wt.%, or at least about 15 wt.%, measured as described above.

[0042]

[0045] The resin may also contain less than 35 wt.% residual ester groups, calculated as polyvinyl ester, e.g., acetate, less than 30 wt.%, less than 25 wt.%, less than 15 wt.%, less than 13 wt.%, less than 11 wt.%, less than 9 wt.%, less than 7 wt.%, less than 5 wt.%, less than 3 wt.%, or less than 1 wt.%, with the remainder being acetal, preferably butyraldehyde acetal, but optionally containing trace amounts of other acetal groups, e.g., 2-ethylhexanal groups (see, e.g., U.S. Pat. No. 5,137,954, the disclosure of which is incorporated herein by reference in its entirety). The residual acetate content of the resin may also be determined according to ASTM D-1396.

[0043]

[0046] In some embodiments, as described above, one or more of the polymer layers of the intermediate layer may be formed from a poly(vinyl acetal) resin. Such poly(vinyl acetal) resin may have a residual acetate content of at least about 1 wt.%, at least about 3 wt.%, at least about 5 wt.%, at least about 7 wt.%, and / or about 15 wt.% or less, about 12 wt.% or less, about 10 wt.% or less, about 8 wt.% or less, measured as described above. When the intermediate layer comprises a multi-layer intermediate layer, two or more polymer layers may include a resin having substantially the same residual acetate content, or one or more resins in the various layers may have substantially different acetate contents. When the residual acetate content of two or more resins is substantially the same, the difference in the residual acetate content may be, for example, less than about 3 wt.%, less than about 2 wt.%, less than about 1 wt.%, or less than about 0.5 wt.%. In some embodiments, the difference in residual acetate content between two or more poly(vinyl butyral) resins in a multi-layer intermediate layer may be at least about 3 wt.%, at least about 5 wt.%, at least about 8 wt.%, at least about 15 wt.%, at least about 20 wt.%, or at least about 30 wt.%. When such resins are utilized in a multi-layer intermediate layer, resins having different residual acetate contents may be present in adjacent polymer layers. When the multi-layer intermediate layer is a three-layer intermediate layer including a pair of outer "skin" layers surrounding or sandwiching an inner "core" layer, for example, the core layer may include a resin having a higher or lower residual acetate content. At the same time, the resin in the inner core layer may have a residual hydroxyl content that is higher or lower than the residual hydroxyl content of the outer skin layers and falls within one or more of the ranges set forth above.

[0044]

[0047] Poly(vinyl acetal) resins with higher or lower residual hydroxyl content and / or residual acetate content may also ultimately contain different amounts of plasticizer when combined with at least one plasticizer. As a result, layers or domains formed with first and second poly(vinyl acetal) resins with different compositions may also have different properties within a single polymer layer or interlayer. Notably, for a given type of plasticizer, the compatibility of the plasticizer with the polymer is largely determined by the hydroxyl content of the polymer. A polymer with a higher residual hydroxyl content typically correlates with a reduced plasticizer compatibility or capacity. Conversely, a polymer with a lower residual hydroxyl content typically results in an increased plasticizer compatibility or capacity. As a result, poly(vinyl acetal) resins with a higher residual hydroxyl content tend to be less plasticized and exhibit higher hardness than similar resins with lower residual hydroxyl content. Conversely, poly(vinyl acetal) resins with lower residual hydroxyl content, when plasticized with a given plasticizer, may tend to incorporate a greater amount of the plasticizer, which may result in a softer polymer layer exhibiting a lower glass transition temperature than a similar resin with a higher residual hydroxyl content. Depending on the particular resin and plasticizer, these trends may be reversed.

[0045]

[0048] When two poly(vinyl acetal) resins with different levels of residual hydroxyl content are blended with a plasticizer, the plasticizer can be distributed between the polymer layers or domains such that there can be more plasticizer in the layer or domain with the lower residual hydroxyl content and less in the layer or domain with the higher residual hydroxyl content. Eventually, an equilibrium state is achieved between the two resins. In general, this correlation between the polymer's residual hydroxyl content 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 within a multilayer interlayer. Such a correlation also stably maintains the difference in plasticizer content between two or more resins when the plasticizer would otherwise migrate between the resins.

[0046]

[0049] As a result of migration of plasticizer within the interlayer, the glass transition temperature of one or more polymer layers may differ when measured alone or as part of a multi-layer interlayer. In some embodiments, the interlayer may include at least one polymer layer outside the interlayer that has a glass transition temperature of at least about 33°C, at least about 34°C, at least about 35°C, at least about 36°C, at least about 37°C, at least about 38°C, at least about 39°C, at least about 40°C, at least about 41°C, at least about 42°C, at least about 43°C, at least about 44°C, at least about 45°C, or at least about 46°C. In some embodiments, the same layer may have a glass transition temperature of at least about 34°C, at least about 35°C, at least about 36°C, at least about 37°C, at least about 38°C, at least about 39°C, at least about 40°C, at least about 41°C, at least about 42°C, at least about 43°C, at least about 44°C, at least about 45°C, at least about 46°C, at least about 47°C within the polymer layer.

[0047]

[0050] In the same or other embodiments, at least one other polymer layer of a multi-layer interlayer may have a glass transition temperature of less than 30° C. measured when the interlayer is not part of the interlayer, and may have a glass transition temperature of, for example, about 25° C. or less, about 20° C. or less, about 15° C. or less, about 10° C. or less, about 9° C. or less, about 8° C. or less, about 7° C. or less, about 6° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, about 1° C. or less, about 0° C. or less, about −1° C. or less, about −2° C. or less, or about −5° C. The same polymer layer may have a glass transition temperature of about 25° C. or less, about 20° C. or less, about 15° C. or less, about 10° C. or less, about 9° C. or less, about 8° C. or less, about 7° C. or less, about 6° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, about 1° C. or less, or about 0° C. or less measured outside the interlayer.

[0048]

[0051] According to some embodiments, the difference between the glass transition temperatures of two polymer layers, typically adjacent polymer layers in an interlayer, may be at least about 5° C., at least about 10° C., at least about 15° C., at least about 20° C., at least about 25° C., at least about 30° C., at least about 35° C., at least about 40° C., or at least about 45° C.; in other embodiments, two or more polymer layers may have glass transition temperatures within about 5° C., within about 3° C., within about 2° C., or within about 1° C. of each other. Generally, a lower glass transition temperature layer will have a lower hardness than a higher glass transition temperature layer in an interlayer, and may be located between higher glass transition temperature polymer layers in the final interlayer structure.

[0049]

[0052] For example, in some embodiments of the present application, the increased acoustic damping properties of the soft layer are combined with the mechanical strength of the hard / rigid layer to form a multi-layer interlayer. In these embodiments, a central soft layer is sandwiched between two hard / rigid outer layers. This (hard) / / (soft) / / (hard) configuration forms a multi-layer interlayer that is easy to handle, can be used in conventional lamination methods, and can be constructed with relatively thin and lightweight layers. The soft layer is generally characterized by a lower residual hydroxyl content (e.g., 16 wt.% or less, 15 wt.% or less, or 12 wt.% or less, or any of the ranges disclosed above), a higher plasticizer content (e.g., about 48 phr or more, or about 70 phr or more, or any of the ranges disclosed above), and / or a lower glass transition temperature (e.g., less than 30° C., or less than 10° C., or any of the ranges disclosed above).

[0050]

[0053] It is contemplated that the polymer interlayer sheets described herein may be manufactured by any suitable process known to those skilled in the art for manufacturing polymer interlayer sheets that may be used in multi-layer panels (e.g., glass laminates). For example, it is contemplated that the polymer interlayer sheets may be formed by solution casting, compression molding, injection molding, melt extrusion, melt blowing, or any other procedure for the production and manufacture of polymer interlayer sheets known to those skilled in the art. Furthermore, in embodiments in which multiple polymer interlayers are utilized, it is contemplated that these multiple polymer interlayers may be formed by coextrusion, blown film, dip coating, solution coating, blade, puddle, air knife, printing, powder coating, spray coating, or other processes known to those skilled in the art. While all methods for the manufacture of polymer interlayer sheets known to those skilled in the art are contemplated as possible methods for manufacturing the polymer interlayer sheets described herein, the present application focuses on polymer interlayer sheets manufactured by extrusion and / or coextrusion processes. The final multi-layer glass panel laminates of the present disclosure are formed using processes known in the art.

[0051]

[0054] In the extrusion process, the thermoplastic resin and the plasticizer, ACA, metal salt, and / or organic acid scavenger, including any of the above-mentioned resins and plasticizers, ACA, metal salts, and / or organic acid scavenger, are generally premixed and fed into the extruder device. Other additives such as colorants and UV inhibitors (liquid, powder or pellet form) may be used and may be mixed into the resin before reaching the extruder device. These additives are incorporated into the thermoplastic polymer resin and into the final polymer interlayer sheet by extrusion to enhance certain properties of the polymer interlayer sheet and its performance in the final multi-ply glass panel product.

[0052]

[0055] In the extruder device, the particles of thermoplastic raw materials and plasticizers, including any of the resins, plasticizers and other additives mentioned above, are further mixed and melted to produce a melt that is generally uniform in temperature and composition. An embodiment of the present invention may provide a melt temperature of about 200°C. Once the melt reaches the end of the extruder device, it is forced into an extruder die. The extruder die is the part of the extruder device that gives the final polymer interlayer sheet product its shape. The die generally has an opening defined by a lip, one dimension of which is significantly larger than the vertical dimension. Generally, the die is designed so that the melt flows uniformly from a cylindrical shape to the final product shape as it exits the die. The die may impart multiple shapes to the final polymer interlayer sheet, as long as there is a continuous profile. Generally, in its most basic sense, extrusion is a process used to form an object of a fixed cross-sectional profile. This is accomplished by pushing or drawing the material through a die of the desired cross-section of the final product.

[0053]

[0056] In some embodiments, a coextrusion process may be utilized. Coextrusion is a process in which multiple layers of polymeric materials are extruded simultaneously. Generally, this type of extrusion utilizes two or more extruders to melt a steady processing volume of different thermoplastic melts of different viscosities or other properties and deliver them as a desired final form through a coextrusion die. For example, the multilayer interlayer of the present invention (e.g., in the form of a three-layer interlayer) may be coextruded preferably using a multiple manifold coextrusion device including a first die manifold, a second die manifold, and a third die manifold. The coextrusion device may operate by simultaneously extruding the polymer melt from each manifold through the die and out of the opening, and the multilayer interlayer is extruded as a composite of three individual polymer layers. The polymer melt may flow through the die such that the core layer is positioned between the skin layers to result in the production of a three-layer interlayer in which the core layer is sandwiched between the skin layers. The die opening may include a pair of lips positioned on either side of the opening. Given the positional orientation of the polymer melt, the skin layers may contact the lips. In either case, the interlayer thickness can be varied by adjusting the distance between the die lips located at the die opening.

[0054]

[0057] The thickness of the multiple polymer layers exiting the extrusion die in a coextrusion process can generally be controlled by adjusting the relative speed of the melt through the extrusion die and the size of the individual die lips. According to some embodiments, the total thickness of the multiple layer interlayer can 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 about 75 mils or less, about 70 mils or less, about 65 mils or less, about 60 mils or less, or can be within the range of about 13 to about 75 mils, about 25 to about 70 mils, or about 30 to 60 mils. When the intermediate layer comprises two or more polymer layers, each of the layers may have a thickness of at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 7 mils, at least about 8 mils, at least about 9 mils, at least about 10 mils, and / or about 50 mils or less, about 40 mils or less, about 30 mils or less, about 20 mils or less, about 17 mils or less, about 15 mils or less, about 13 mils or less, about 12 mils or less, about 10 mils or less, about 9 mils or less. In some embodiments, each of the layers may have about the same thickness, and in other embodiments, one or more layers may have a different thickness than one or more other layers in the intermediate layer. Other thicknesses may be selected depending on the desired application and properties.

[0055]

[0058] In some embodiments where the intermediate layer comprises at least three polymer layers, one or more of the inner layers may be relatively thin compared to the other outer layers. For example, in some embodiments where the multi-layer intermediate layer is a three-layer intermediate layer, the innermost layer may have a thickness of about 12 mils or less, about 10 mils or less, about 9 mils or less, about 8 mils or less, about 7 mils or less, about 6 mils or less, about 5 mils or less, or may have a thickness in the range 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 mils, at least about 5 mils, at least about 6 mils, at least about 7 mils, and / or about 15 mils or less, about 13 mils or less, about 12 mils or less, about 10 mils or less, about 9 mils or less, about 8 mils or less, or may be in the range of about 2 to about 15 mils, about 3 to about 13 mils, or about 4 mils to about 10 mils. When the intermediate layer includes two outer layers, the layers may have a combined thickness of at least about 9 mils, at least about 13 mils, at least about 15 mils, at least about 16 mils, at least about 18 mils, at least about 20 mils, at least about 23 mils, at least about 25 mils, at least about 26 mils, at least about 28 mils, or at least about 30 mils, and / or no more than about 73 mils, no more than about 60 mils, no more than about 50 mils, no more than about 45 mils, no more than about 40 mils, 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.

[0056]

[0059] According to some embodiments, the ratio of the thickness of one of the outer layers to one of the inner layers in a multi-layer intermediate layer may be at least about 1.4:1, at least about 1.5:1, at least about 1.8:1, at least about 2:1, at least about 2.5:1, at least about 2.75:1, at least about 3:1, at least about 3.25:1, at least about 3.5:1, at least about 3.75:1, or at least about 4:1. When the intermediate layer is a three-layer intermediate layer having an inner core layer disposed between a pair of outer skin layers, the ratio of the thickness of one of the skin layers to the thickness of the core layer may fall within one or more of the above ranges. In some embodiments, the ratio of the total thickness of the outer layer to the inner layer can be at least about 2.25:1, at least about 2.4:1, at least about 2.5:1, at least about 2.8:1, at least about 3:1, at least about 3.5:1, at least about 4:1, at least about 4.5:1, at least about 5:1, at least about 5.5:1, at least about 6:1, at least about 6.5:1, or at least about 7:1, and / or no more than about 30:1, no more than about 20:1, no more than about 15:1, no more than about 10:1, no more than about 9:1, no more than about 8:1.

[0057]

[0060] The multi-layer interlayers described herein may comprise a generally flat interlayer having substantially the same thickness along the length or longest dimension and / or width or second longest dimension of the sheet. However, in some embodiments, the multi-layer interlayers of the present invention may be tapered or wedge-shaped interlayers comprising at least one tapered zone having a wedge-shaped profile. A tapered interlayer has a thickness profile that varies along at least a portion of the length and / or width of the sheet, for example, such that at least one end of the interlayer has a greater thickness than the other end. When the interlayer is a tapered interlayer, at least one, at least two, at least three or more of the individual resin or polymer layers may include at least one tapered zone. Tapered interlayers may be particularly useful, for example, in head-up display (HUD) panels in automotive and aviation applications.

[0058]

[0061] In view of the above, embodiments of the present invention include a polymeric interlayer that resists the formation of optical defects. The polymeric interlayer may comprise a core layer, a first skin layer, and a second skin layer. The core layer is generally positioned between the first skin layer and the second skin layer such that the skin layers sandwich the core layer. Notably, the core layer includes a resin that includes (i) a monovalent alkali salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0059]

[0062] Beneficially, in such embodiments, the polymer interlayer (or resulting laminated glass panel) has improved yellowness index values ​​over other polymer interlayers (or resulting laminated glass panels) formed without the organic acid scavenger. For example, the polymer interlayer of the present invention, when laminated between a pair of glass sheets to form a laminated glass panel, may have a yellowness index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0. The "yellowness index" of the polymer interlayer (or resulting laminated glass panel) may be measured from spectroscopic light transmittance in the visible spectrum according to ASTM D-1925, "Standard Test Method for Yellowness Index of Plastics." Additionally, the polymer interlayer (or resulting laminated glass panel) may have reduced bubble formation (e.g., edge or trim bubbles) compared to other polymer interlayers (or resulting laminated glass panels) formed without the organic acid scavenger.

[0060]

[0063] To facilitate such improved Yellowness Index values ​​(or reduced bubble formation) in the interlayers and / or laminate panels of embodiments of the present invention, the resin forming the core layer of the interlayer may contain a monovalent alkali salt amount of less than about 10 strength, less than about 9 strength, less than about 8 strength, less than about 7 strength, less than about 6 strength, less than about 5 strength, less than about 4 strength, less than about 3 strength, less than about 2 strength, less than about 1 strength, less than about 0.5 strength, and / or about 0 strength (i.e., the core layer does not contain any monovalent alkali salt). Alternatively, the resin forming the core layer of the intermediate layer may be of about 0-10 strength, 0-9 strength, 0-8 strength, 0-7 strength, 0-6 strength, 0-5 strength, 0-4 strength, 0-3 strength, 0-2 strength, 0-1 strength, 1-10 strength, 1-9 strength, 1-8 strength, 1-7 strength, 1-6 strength, 1-5 strength, 1-4 strength, 1-3 strength, 1-2 strength, 2-10 strength, 2-9 strength, 2-8 strength, 2-7 strength, 2-6 strength, 2-5 strength, 2-4 strength, 2-3 strength, 3-10 strength In some embodiments, the monovalent alkali salt amount may be in the range of 1 to 8 potency, 3 to 9 potency, 3 to 8 potency, 3 to 7 potency, 3 to 6 potency, 3 to 5 potency, 3 to 4 potency, 4 to 10 potency, 4 to 9 potency, 4 to 8 potency, 4 to 7 potency, 4 to 6 potency, 4 to 5 potency, 5 to 10 potency, 5 to 9 potency, 5 to 8 potency, 5 to 7 potency, 5 to 6 potency, 6 to 10 potency, 6 to 9 potency, 6 to 8 potency, 6 to 7 potency, 7 to 10 potency, 7 to 9 potency, 7 to 8 potency, 8 to 10 potency, 8 to 9 potency, and / or 8 to 10 potency.

[0061]

[0064] The ACA or monovalent alkali salt concentration in the resin forming the relevant interlayer discussed herein is provided in titer units. The "titer" may be determined for the sodium acetate, potassium acetate, and magnesium salts in the sheet sample (as used herein, "total alkali titer") using the following procedure. To determine the amount of resin in each interlayer sheet sample that is weighed, the following equation may be used, where PHR is defined as pounds of plasticizer per 100 pounds of resin in the original sheet sample preparation:

[0062]

number

[0063]

[0065] Approximately 5 grams of resin in the sheet sample is the target mass used to estimate the amount of sheet sample to begin the procedure, and the calculated mass of resin in the sheet sample is used for each titer determination. All titrations should be completed on the same day. The sheet sample may be dissolved in 250 milliliters of methanol in a beaker. It may take up to 8 hours for the sheet sample to completely dissolve. A methanol-only blank should also be prepared in a beaker. The samples and blanks should each be titrated with 0.00500 normal hydrogen chloride (HCl) using an automated pH titrator programmed to stop at a pH of 2.5. The amount of HCl added to each of the samples and blanks to obtain a pH of 4.2 is recorded. The HCl titer (total alkaline titer) should be determined according to the following:

[0064]

number

[0065]

[0066] To determine the magnesium salt titer, the following procedure can be performed. 12-15 milliliters of a pH 10.00 buffer solution prepared from 54 grams of ammonium chloride and 350 milliliters of ammonium hydroxide diluted to 1 liter with methanol, and 12-15 milliliters of eriochrome black T indicator should be added to the blank and each sheet sample, all of which have already been titrated with HCl as described above. The titrant can then be replaced with a 0.000298 g / ml ethylenediaminetetraacetic acid (EDTA) solution prepared from 0.3263 g of tetrasodium ethylenediaminetetraacetate dihydrate, 5 milliliters of water diluted to 1 liter with methanol. The EDTA titration can be measured by light transmittance at 596 nm. The percent transmittance should first be adjusted to 100% in the sample or blank before the titration begins while the solution is a bright magenta-pink color. When the transmittance at 596 nm becomes constant, the EDTA titration is complete and the solution is a deep blue color. For the blank and each sheet sample, the volume of EDTA titrated to reach the deep blue end point should be recorded. The magnesium salt titer is determined as follows:

[0066]

number

[0067]

[0067] 1×10 per gram of resin -7 The portion of the total alkaline titer that can be attributed to sodium acetate and / or potassium acetate, as molar acetate, can be calculated according to the following:

[0068]

number

[0069]

[0068] After determining the portion of the total alkaline titer attributable to monovalent alkali metal salts, such as acetates (e.g., sodium acetate and / or potassium acetate), destructive analysis of the polymer sheet by inductively coupled plasma emission spectroscopy (ICP) can be performed to obtain the ppm potassium and ppm sodium concentrations. The alkaline titer attributable to sodium acetate is defined herein as the total alkaline titer attributable to sodium acetate and / or potassium acetate multiplied by the ratio of [ppm sodium / (ppm sodium+ppm potassium)]. The alkaline titer attributable to potassium acetate is defined herein as the total alkaline titer attributable to sodium acetate and / or potassium acetate multiplied by the ratio of [ppm potassium / (ppm sodium+ppm potassium)]. Another exemplary procedure for determining ACA titer is described in U.S. Pat. No. 5,728,472, previously incorporated herein by reference.

[0070]

[0069] The above values ​​and / or ranges of ACA and / or metal salt may include various combinations of types of ACA and / or metal salt. For example, as described above, the metal salt included in the interlayer and / or core layer of the laminate panel of the present embodiment may include magnesium salt and / or potassium salt. Thus, the core layer of the interlayer may include both magnesium salt and potassium salt, but the total amount of metal salt is monovalent alkali metal salt of about 15 titer or less, or less than about 10 titer. In an alternative embodiment, the core layer of the interlayer may include potassium salt as the monovalent alkali metal salt and no magnesium salt, but the total amount of monovalent alkali metal salt is still less than about 10 titer. In a further alternative, the core layer of the interlayer may include magnesium salt and no potassium salt, but the total amount of magnesium salt is less than about 10 titer. Magnesium salt works well as an acid scavenger in the core or inner layer, but too much magnesium salt leads to undesirable bubbles in the sheet, especially when used in laminated glass. Therefore, the amount of magnesium salt must be balanced or controlled, or may be used in combination with another metal salt.

[0071]

[0070] Additionally, to promote improvement in Yellowness Index values ​​and / or reduction in bubble formation within the interlayers and / or laminate panels of embodiments of the present invention, the core layer of the interlayer may also contain at least 0.5 phr, at least 1 phr, at least 2 phr, at least 3 phr, at least 4 phr, at least 5 phr, or at least 6 phr of an organic acid scavenger. Alternatively, the core layer of the intermediate layer may include an organic acid scavenger in the range of about 0.5-6 phr, 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 0.5-2 phr, 0.5-1 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 1-2 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

[0072] The above-mentioned polymeric intermediate layer that resists the formation of optical defects (e.g., yellowing and / or bubble formation) may be formed by extruding a first polymer melt to form a core layer and a second polymer melt to form a first and second skin layer. In some embodiments, the first polymer melt is fed by a first extruder (e.g., a core extruder), while the second polymer melt is fed by a second extruder (e.g., a skin extruder), and then split into two streams to form the skin layer. The core layer and the skin layer are generally coextruded such that the core layer is located between the first skin layer and the second skin layer. Notably, the first polymer melt from which the core layer is formed comprises a resin comprising (i) a monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0073]

[0072] Thus, the polymer interlayers of the present invention (and / or the resulting laminated glass panels) have reduced yellowing and / or lower bubble formation than other polymer interlayers (or other laminated glass panels). For example, in some particular embodiments, the polymer interlayers, and / or the resulting laminated glass panels formed via the polymer interlayers of the present invention laminated between a pair of glass panels, may have a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0. Furthermore, the polymer interlayers, and / or the resulting laminated glass panels formed via the polymer interlayers of the present invention laminated between a pair of glass panels may have low levels of bubbles.

[0074]

[0073] Embodiments may further include methods of forming laminated glass panels having reduced optical defects. Such methods may include laminating the above-described polymer interlayer between a pair of glass sheets to form a laminated glass panel. Such glass panels may, in certain embodiments, have a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0. Additionally, in some embodiments, the glass panels may have reduced bubble formation (e.g., edge or trim bubbles), or, in other words, the level of bubbles in the glass panel is lower than the level in a comparative panel.

[0075] In addition to the laminated glass panels of the invention described above that include an organic acid scavenger and reduced levels of metal salts in the core layer of the polymer interlayer of the panel, embodiments of the invention may include laminated glass panels (or polymer interlayers for use in laminated glass panels) formed with a polymer interlayer that resists the formation of optical defects and has a core layer that does not include an organic acid scavenger but does include a particular type and / or amount of metal salt. For example, certain embodiments of the invention may include a laminated glass panel comprising a first glass sheet, a second glass sheet, and a polymer layer positioned between the first and second glass sheets. The polymer layer may include a resin that includes a metal salt of about 35 strength or less, and the monovalent alkali metal salt of at least 5 strength is potassium acetate.

[0076] In certain embodiments, the polymer layer may be a core layer forming part of the polymer interlayer. The polymer interlayer may further include a pair of skin layers positioned on either side of the core layer. Thus, the polymer interlayer comprises a three-layer interlayer having a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being a core layer positioned between the second polymer layer (i.e., skin layer) and the third polymer layer (i.e., skin layer). In certain embodiments, the core layer may be formed from a PVB resin, as described in connection with previous embodiments of the invention. The resin of the core layer may be formed with a metal salt including potassium acetate, magnesium di-2-ethylhexanoate, or a combination thereof. For example, in some embodiments, the resin may include potassium acetate of at least 10 strength, at least 15 strength, at least 20 strength, and / or at least 25 strength. Alternatively or additionally, the resin may comprise a potassium acetate strength of 25 or less, 20 or less, 15 or less, 10 or less, and / or 6 or less. Alternatively or additionally, the resin may comprise a magnesium di-2-ethylhexanoate strength of at least 5, at least 10, and / or at least 15. Alternatively or additionally, the resin may comprise a magnesium di-2-ethylhexanoate strength of 15 or less, 10 or less, and / or 5 or less.

[0077] Certain specific embodiments of the glass panels of the present invention may provide that the resin of the core layer has a combination of metal salts of about 25 strength or less. In some such embodiments, the metal salt may consist essentially of potassium acetate in an amount of less than 10 strength. In further embodiments, the glass panels of the present invention may provide that the resin of the core layer has a metal salt of about 15 strength or less. In certain such embodiments, the ACA may consist of a combination of potassium acetate and magnesium di-2-ethylhexanoate. For example, the resin of the core layer may include potassium acetate of about 6 strength and magnesium di-2-ethylhexanoate of about 9 strength.

[0078] In view of the above, embodiments may provide that by forming a polymer layer of a glass panel with a particular type and amount of metal salt, such as an alkali metal salt, with reduced organic acid scavenging agent (or no organic acid scavenging agent), a laminated glass panel may be produced with reduced optical defects. Such reduced optical defects may be exhibited by a glass panel having an acceptable Yellowness Index value. In some embodiments, the Yellowness Index value may be less than about 1.00, less than about 0.75, less than about 0.50, less than about 0.25, less than about 0.00, less than about -0.25, and / or less than about -0.50. Furthermore, in some embodiments, such glass panels may also have reduced bubble formation (e.g., edge bubbles or trim bubbles).

[0079] Example 1

[0078] Eleven laminated glass panels (i.e., EX1-GP1 to EX1-GP11) were formed as described in more detail below. Each of the glass panels included a polymer layer formed with a specific amount of plasticizer, adhesion modifier (ACA), and / or organic acid scavenger. The yellowness index ("YI") value of each of the glass panels was then measured, as shown in Table 1 below. Specifically, the YI of the glass panels was measured using spectroscopic light transmittance in the visible spectrum according to ASTM D-1925 using a spectrophotometer, such as a Hunterlab UltraScan XE instrument (commercially available from Hunter Associates, Reston, VA). For some of the glass panels, a qualitative evaluation of the panels was performed to determine whether there was a high (unacceptable) level of bubbles formed within the panel or a low (acceptable) level of bubbles formed within the panel.

[0080]

[0079] More specifically, each of the glass panels EX1-GP1 to EX1-GP11 was formed by laminating a polymer sheet between two 2.3 mm clear annealed glass sheets under industry standard lamination degassing and autoclaving processes to form a laminated glass sample. For each of the glass panels EX1-GP1 to EX1-GP10, each polymer sheet was formed by mixing 50 grams of PVB resin in a plastic jar with the amounts of plasticizer, metal salt, and / or organic acid scavenger listed in Table 1. The PVB resin included PVB having a residual PVOH content of 10.5 wt.% and a residual PVAc content of less than 1 wt.%. The plasticizer included 3-GEH. The type 1 metal salt included magnesium di-2-ethylhexanoate. The type 2 metal salt included magnesium acetate. The type 3 metal salt included potassium acetate. The type 1 organic acid scavenger included MCS1562. The Type 2 organic acid scavenger included DER 732. The resulting mixture was fed into a Brabender laboratory melt mixer and melt mixed for 7 minutes at a temperature of 170° C. The resulting melt was removed from the mixer and compressed into a sheet having a thickness of about 0.76 mm to form a polymer sheet.

[0081] [Table 1]

[0082]

[0080] As illustrated by the data from Table 1, and as discussed in more detail below, it was found that glass panels formed using polymer sheets having a monovalent alkali metal salt and an organic acid scavenger beneficially had reduced YI values ​​and less bubble formation. It is generally understood that a lower YI value corresponds to reduced yellowing of the polymer layer and / or the laminated glass panel having the polymer layer, as well as an overall improved stability of the polymer layer.

[0083]

[0081] First, for EX1-GP9 and EX1-GP10 glass panels formed using a combination of type 2 metal salt (i.e., magnesium acetate) and type 3 metal salt (i.e., potassium acetate) in the polymer sheet, experimental results showed that such glass panels had unacceptably high YI values ​​of 6.41 and 4.49, respectively. In contrast, EX1-GP7 and EX1-GP8 glass panels formed using a combination of type 1 metal salt (i.e., magnesium di-2-ethylhexanoate) and type 3 metal salt (i.e., potassium acetate) in the polymer sheet were found to have acceptable YI values ​​of -0.54 and -0.65, respectively. However, as exemplified by EX1-GP5 and EX1-GP6, when the type 1 metal salt was removed from the polymer sheet and only low levels of monovalent alkali metal salt (type 3 metal salt) were present, the unacceptably high YI values ​​returned (i.e., 6.61 and 4.43, respectively).

[0084] However, it was found that the addition of a certain amount of organic acid scavenger to the polymer sheet improved the YI value of the glass panel while maintaining a low level of bubble formation. More specifically, EX1-GP1 to EX1-GP4 show glass panels formed using polymer sheets having reduced amounts of monovalent alkali metal salt (i.e., 6 strength 3 type metal salt, potassium acetate) and 5 phr of organic acid scavenger. Experimental results showed that such glass panels EX1-GP1 to EX1-GP4 have improved reduced YI values ​​(i.e., -0.54, -0.56, -0.47 and -0.51, respectively) and acceptable (low) bubble formation. In view of the above, Example 1 shows that glass panels formed using polymer layers having low levels of organic acid scavenger in combination with reduced levels of metal salt can have reduced optical defects such as yellowness and bubble formation. Specifically, polymer layers / interlayers formed with organic acid scavengers and reduced levels of metal salts (or glass panels formed with such polymer layers / interlayers) may have reduced Yellowness Index values, which are associated with reduced discoloration and improved overall stability of the polymer layer, as well as lower levels of bubbles.

[0085]

[0083] Referring briefly to the EX1-GP7 and EX1-GP8 glass panels, such glass panels were found to have acceptable YI values ​​(i.e., values ​​less than 1.00, -0.54 and -0.65, respectively) even when they contained large amounts of metal salts and no organic acid scavenger in their respective polymer sheets. More specifically, the EX1-GP7 and EX1-GP8 glass panels were formed using a combination of a Type 1 metal salt (i.e., magnesium di-2-ethylhexanoate with a strength of 9) and a Type 3 metal salt (i.e., potassium acetate with a strength of 6) in the polymer sheet. Thus, the data from Example 1 indicates that laminated glass panels having polymer sheets with higher amounts of metal salts but no organic acid scavenger may nevertheless have acceptable YI values ​​depending on the particular type and amount of metal salt used in the polymer sheets of the laminated glass panels.

[0086]

[0084] The EX1-GP11 glass panel further showed that while glass panels with polymer sheets having large amounts of metal salts and no organic acid scavenger could still provide acceptable YI values, such high levels of metal salts contribute to layer instability as indicated by the high levels of bubbles formed. In particular, the EX1-GP11 glass panel was formed using only type 3 metal salts (i.e., 25 strength potassium acetate) in the polymer sheet. As shown in Table 1, the EX1-GP11 glass panel had an acceptable YI value of about 0.76, but had a high level of bubbles.

[0087] Comparative Example 1

[0085] Six comparative laminated glass panels (i.e., CX1-GP1 to CX1-GP6) were formed in a manner similar to that described above for laminated glass panels EX1-GP1 to EX11 in Example 1. However, in contrast to the panels from Example 1, the polymer sheets from this Comparative Example 1 glass panel were formed using various types of surfactants without the use of an organic acid scavenger. Specifically, each polymer sheet was formed by mixing 5 phr of either a Type 1 surfactant, a Type 2 surfactant, or a Type 3 surfactant in the PVB resin. The Type 1 surfactant includes a polyethylene glycol nonyl phenol ether, has a degree of polymerization of about 10, and is known under the trade name Surfonic N-102. The Type 2 surfactant includes a polyethylene glycol nonyl phenol ether, has a degree of polymerization of about 4, and is known under the trade name Surfonic N-40. The Type 3 surfactant includes an alcohol, is C12-14-secondary, ethoxylated, has about 12 moles of ethylene oxide, and is known under the trade name Tergitol 15-S-12. After the glass panels CX1-GP1 to CX1-GP6 were formed, the YI value of each of the glass panels was measured, as shown in Table 2.

[0088] [Table 2]

[0089]

[0086] As shown by the data from Table 2, glass panels CX1-GP1 to CX1-GP6 formed using polymer sheets having a large amount of metal salts (i.e., a total of 43 strengths of metal salts, including 18 strengths of type 1 metal salts and 25 strengths of type 3 metal salts) and no organic acid scavenger were found to have unacceptably high YI values ​​(i.e., YI values ​​greater than 1.00). Thus, comparing the glass panels of Comparative Example 1 (i.e., CX1-GP1 to CX1-GP6) with the inventive glass panels of Example 1 (i.e., EX1-GP1 to EX1-GP4) shows that the use of an organic acid scavenger in combination with significantly reduced levels of metal salts in the polymer layer of a laminated glass panel can provide a reduction in optical defects (yellowness and / or bubbling) of the glass panels.

[0090]

[0087] Although the present invention has been disclosed in conjunction with a description of certain specific embodiments, including what are presently believed to be preferred embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the present disclosure. As will be appreciated by those skilled in the art, embodiments other than those specifically described herein are encompassed by the present invention. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the present invention.

[0091]

[0088] Furthermore, it is understood that any range, value, or characteristic recited for any single component of this disclosure may be used interchangeably with any range, value, or characteristic recited for any of the other components of this disclosure to form embodiments having the defined values ​​for each of the components as set forth throughout this specification, where compatible. For example, a polymer layer may be formed that includes any of the recited ranges for plasticizer content, in addition to any of the recited ranges for residual hydroxyl content, to form, where appropriate, many permutations that are within the scope of the present invention but too cumbersome to enumerate.

[0092]

[0089] The present invention and its preferred embodiments will now be further described with reference to numbered items 1-95.

[0093]

[0090] Item 1. A polymeric interlayer resistant to the formation of optical defects, comprising: a first polymeric layer; a second polymeric layer; and a third polymeric layer, the first polymeric layer being positioned between the second polymeric layer and the third polymeric layer, the first polymeric layer comprising a resin having (i) a monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0094] Item 2. The polymeric interlayer of item 1, wherein the resin of the first polymer layer comprises poly(vinyl butyral).

[0095] Item 3. The polymeric interlayer of item 1, wherein the monovalent alkali metal salt in the first polymer layer comprises a potassium salt.

[0096]

[0093] Item 4. A polymer intermediate layer described in Item 1, wherein the monovalent alkali metal salt in the first polymer layer has a potency of less than about 9, less than about 8, less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than about 0.5, and / or about 0.

[0097] Item 5. The polymeric interlayer of item 1, wherein the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

[0098] Item 6. The polymeric interlayer of item 5, wherein the epoxide derivative comprises a mono-epoxide.

[0099] Item 7. The polymeric interlayer of item 5, wherein the epoxide derivative comprises a di-epoxide.

[0100] Item 8. The polymeric interlayer of item 5, wherein the epoxide derivative comprises an epoxidized vegetable oil.

[0101]

[0098] Item 9. A polymer intermediate layer described in Item 1, wherein the organic acid scavenger in the first polymer layer is in the range of about 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

[0102]

[0099] Item 10. A polymer interlayer as described in Item 1, wherein when the polymer interlayer is laminated between a pair of glass sheets to form a laminated glass panel, such glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

[0103]

[0100] Item 11. The polymer interlayer of item 1, wherein the thickness of the polymer interlayer is approximately constant along the length of the polymer interlayer.

[0104]

[0101] Item 12. The polymer interlayer of item 1, wherein the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

[0105]

[0102] Item 13. The polymeric interlayer of item 1, wherein the first polymeric layer is softer than the second and third polymeric layers.

[0106]

[0103] Item 14. A laminated glass panel that resists the formation of optical defects, comprising: a first glass sheet; a second glass sheet; and a polymer interlayer laminated between the first glass sheet and the second glass sheet, the polymer interlayer comprising a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being positioned between the second polymer layer and the third polymer layer, the first polymer layer comprising a resin having (i) a monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0107]

[0104] Item 15. The laminated glass according to item 14, wherein the resin of the first polymer layer comprises poly(vinyl butyral).

[0108]

[0105] Item 16. The laminated glass of item 14, wherein the monovalent alkali metal salt in the first polymer layer comprises a potassium salt.

[0109]

[0106] Item 17. Laminated glass described in Item 14, wherein the monovalent alkali metal salt in the first polymer layer has a potency of less than about 9, less than about 8, less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than about 0.5, and / or about 0.

[0110]

[0107] Item 18. The laminated glass described in Item 14, wherein the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

[0111]

[0108] Item 19. The laminated glass according to item 18, wherein the epoxide derivative comprises a mono-epoxide.

[0112]

[0109] Item 20. The laminated glass according to item 18, wherein the epoxide derivative comprises a di-epoxide.

[0113]

[0110] Item 21. Laminated glass according to item 18, wherein the epoxide derivative comprises an epoxidized vegetable oil.

[0114]

[0111] Item 22. The laminated glass described in Item 14, wherein the organic acid scavenger in the first polymer layer is within the range of about 0.5 to 5 phr, 0.5 to 4 phr, 0.5 to 3 phr, 1 to 6 phr, 1 to 5 phr, 1 to 4 phr, 1 to 3 phr, 2 to 6 phr, 2 to 5 phr, 2 to 4 phr, 2 to 3 phr, 3 to 6 phr, 3 to 5 phr, 3 to 4 phr, 4 to 6 phr, 4 to 5 phr, and / or 5 to 6 phr.

[0115]

[0112] Item 23. The laminated glass described in Item 14, wherein when the polymer interlayer is laminated between a pair of glass sheets to form a laminated glass panel, such glass panel has a yellowness index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

[0116]

[0113] Item 24. A polymeric interlayer resistant to the formation of optical defects, comprising: a first polymer layer; a second polymer layer; and a third polymer layer, the first polymer layer being positioned between the second polymer layer and the third polymer layer, the first polymer layer comprising (i) a resin comprising a first alkali metal salt and a second alkali metal salt having a titer of about 15 or less.

[0117] Item 25. The polymeric interlayer of item 24, wherein the resin of the first polymer layer comprises poly(vinyl butyral).

[0118] Item 26. The polymeric intermediate layer of item 24, wherein the first alkali metal salt in the first polymer layer comprises a magnesium salt.

[0119] Item 27. The polymeric intermediate layer of item 24, wherein the second alkali metal salt in the first polymer layer comprises a potassium salt.

[0120] Item 28. The polymeric intermediate layer of item 24, wherein the first alkali metal salt and the second alkali metal salt in the first polymer layer comprise a combination of a magnesium salt and a potassium salt.

[0121] Item 29. The polymeric interlayer of item 24, wherein the first polymeric layer comprises an organic acid scavenger.

[0122]

[0119] Item 30. A polymer intermediate layer described in Item 24, wherein each of the first and second alkali metal salts in the first polymer layer is present in an amount of less than about 9 potency, less than about 8 potency, less than about 7 potency, less than about 6 potency, less than about 5 potency, less than about 4 potency, less than about 3 potency, less than about 2 potency, less than about 1 potency, less than about 0.5 potency, and / or about 0 potency.

[0123] Item 31. The polymeric interlayer of item 24, wherein the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

[0124] Item 32. The polymeric intermediate layer of item 31, wherein the epoxide derivative comprises a mono-epoxide.

[0125] Item 33. The polymeric intermediate layer of item 31, wherein the epoxide derivative comprises a di-epoxide.

[0126] Item 34. The polymeric intermediate layer of item 31, wherein the epoxide derivative comprises an epoxidized vegetable oil.

[0127]

[0124] Item 35. A polymer intermediate layer described in Item 29, wherein the organic acid scavenger in the first polymer layer is within the range of about 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

[0128]

[0125] Item 36. A polymer interlayer as described in Item 24, wherein when the polymer interlayer is laminated between a pair of glass sheets to form a laminated glass panel, such glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

[0129]

[0126] Item 37. The polymer interlayer of item 24, wherein the thickness of the polymer interlayer is approximately constant along the length of the polymer interlayer.

[0130] Item 38. The polymer interlayer of item 24, wherein the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

[0131] Item 39. The polymeric interlayer of item 24, wherein the first polymeric layer is softer than the second and third polymeric layers.

[0132]

[0129] Item 40. A method for forming a polymeric interlayer that is resistant to the formation of optical defects, comprising the steps of: (a) extruding a first polymer melt to form a first polymer layer; and (b) extruding a second polymer melt to form a second polymer layer and a third polymer layer, wherein during the extrusion of steps (a) and (b), the first polymer layer is positioned between the second polymer layer and the third polymer layer, and the first polymer layer comprises a resin comprising (i) a monovalent alkali metal salt having a strength of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

[0133]

[0130] Item 41. The method according to Item 40, wherein the extrusion of steps (a) and (b) is carried out by coextrusion, the resin of the first polymer layer comprises PVB, and the monovalent alkali metal salt in the first polymer layer comprises a potassium salt.

[0134]

[0131] Item 42. The method of item 40, wherein the resin of the first polymer layer does not contain a magnesium salt.

[0135]

[0132] Item 43. The method of item 40, wherein the monovalent alkali metal salt in the first polymer layer has a potency of less than about 9, less than about 8, less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than about 0.5, and / or about 0.

[0136] Item 44. The method of item 40, wherein the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

[0137]

[0134] Item 45. The method of item 40, wherein the organic acid scavenger in the first polymer layer is within the range of about 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

[0138]

[0135] Item 46. The method of Item 40, further comprising the step of (c) laminating a polymer interlayer between a pair of glass sheets to form a laminated glass panel, wherein upon lamination in step (c), the laminated glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

[0139]

[0136] Item 47. The method of Item 40, wherein the thickness of the polymer interlayer is approximately constant along the length of the polymer interlayer.

[0140] Item 48. The method of item 40, wherein the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

[0141]

[0138] Item 49. The method of item 40, wherein the first polymer layer is softer than the second and third polymer layers.

[0142]

[0139] Item 50. A method for forming a polymeric interlayer resistant to the formation of optical defects, comprising: (a) extruding a first polymer melt to form a first polymer layer; and (b) extruding a second polymer melt to form a second polymer layer and a third polymer layer, wherein during the extrusion of steps (a) and (b), the first polymer layer is positioned between the second polymer layer and the third polymer layer, and the first polymer layer comprises (i) a resin comprising a first alkali metal salt and a second alkali metal salt having a titer of about 15 or less.

[0143]

[0140] Item 51. The method of Item 50, wherein the extrusion of steps (a) and (b) is carried out by coextrusion, the resin of the first polymer layer comprises poly(vinyl butyral), and the first alkali metal salt in the first polymer layer comprises a magnesium salt.

[0144] Item 52. The method of item 50, wherein the second alkali metal salt in the first polymer layer comprises a potassium salt.

[0145] Item 53. The method of item 50, wherein the first alkali metal salt and the second alkali metal salt in the first polymer layer comprise a combination of a magnesium salt and a potassium salt.

[0146]

[0143] Item 54. The method of item 50, wherein the first polymer layer further comprises an organic acid scavenger.

[0147]

[0144] Item 55. The method of Item 50, wherein each of the first and second alkali metal salts in the first polymer layer is present in an amount of less than about 9 potency, less than about 8 potency, less than about 7 potency, less than about 6 potency, less than about 5 potency, less than about 4 potency, less than about 3 potency, less than about 2 potency, less than about 1 potency, less than about 0.5 potency, and / or about 0 potency.

[0148]

[0145] Item 56. The method of Item 50, further comprising the step of (c) laminating a polymer interlayer between a pair of glass sheets to form a laminated glass panel, wherein upon lamination in step (c), the laminated glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

[0149]

[0146] Item 57. The method of Item 50, wherein the thickness of the polymer interlayer is approximately constant along the length of the polymer interlayer.

[0150]

[0147] Item 58. The method of item 50, wherein the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

[0151]

[0148] Item 59. The method of item 50, wherein the first polymer layer is softer than the second and third polymer layers.

[0152]

[0149] Item 60. A polymeric interlayer resistant to the formation of optical defects, comprising a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being positioned between the second polymer layer and the third polymer layer, the first polymer layer comprising a resin comprising an alkali metal salt having a strength of about 35 or less, the alkali metal salt having a strength of at least 5 being potassium acetate.

[0153]

[0150] Item 61. The polymeric intermediate layer described in Item 60, wherein the resin of the first polymeric layer of the polymeric intermediate layer contains an alkali metal salt having a titer of about 25 or less.

[0154] Item 62. The polymeric intermediate layer of item 60, wherein the alkali metal salt consists essentially of potassium acetate.

[0155]

[0152] Item 63. The polymeric intermediate layer described in Item 60, wherein the resin of the first polymeric layer of the polymeric intermediate layer contains an alkali metal salt having a titer of about 15 or less.

[0156] Item 64. The polymeric intermediate layer of item 60, wherein the alkali metal salt comprises a combination of potassium acetate and magnesium di-2-ethylhexanoate.

[0157]

[0154] Item 65. The polymeric intermediate layer according to Item 60, wherein the alkali metal salt comprises potassium acetate having a strength of about 6.

[0158]

[0155] Item 66. The polymeric intermediate layer according to item 60, wherein the alkali metal salt comprises magnesium di-2-ethylhexanoate having a strength of about 9.

[0159]

[0156] Item 67. The polymer intermediate layer described in Item 60, wherein the resin of the first polymer layer of the polymer intermediate layer comprises at least 10 strength, at least 15 strength, at least 20 strength, and / or at least 25 strength of potassium acetate.

[0160]

[0157] Item 68. The polymer intermediate layer described in Item 60, wherein the resin of the first polymer layer of the polymer intermediate layer comprises potassium acetate having a strength of 25 or less, 20 or less, 15 or less, 10 or less, and / or 6 or less.

[0161]

[0158] Item 69. The polymer intermediate layer described in Item 60, wherein the resin of the first polymer layer of the polymer intermediate layer comprises magnesium di-2-ethylhexanoate having a strength of at least 5, at least 10, and / or at least 15.

[0162]

[0159] Item 70. The polymer intermediate layer described in Item 60, wherein the resin of the first polymer layer of the polymer intermediate layer comprises magnesium di-2-ethylhexanoate having a strength of 15 or less, 10 or less, and / or 5 or less.

[0163]

[0160] Item 71. A laminated glass panel that is resistant to the formation of optical defects, comprising: a first glass sheet; a second glass sheet; and a polymer interlayer laminated between the first glass sheet and the second glass sheet, the polymer interlayer comprising a first polymer layer, a second polymer layer, and a third polymer layer, the first polymer layer being positioned between the second polymer layer and the third polymer layer, the first polymer layer comprising a resin comprising an alkali metal salt having a strength of about 35 or less, the alkali metal salt having a strength of at least 5 being potassium acetate.

[0164]

[0161] Item 72. A laminated glass panel as described in Item 71, wherein the resin of the first polymer layer of the polymer interlayer contains an alkali metal salt having a strength of about 25 or less.

[0165]

[0162] Item 73. The laminated glass panel according to item 71, wherein the alkali metal salt consists essentially of potassium acetate.

[0166]

[0163] Item 74. A laminated glass panel as described in Item 71, wherein the resin of the first polymer layer of the polymer interlayer contains an alkali metal salt having a strength of about 15 or less.

[0167]

[0164] Item 75. The laminated glass panel according to item 71, wherein the alkali metal salt comprises a combination of potassium acetate and magnesium di-2-ethylhexanoate.

[0168]

[0165] Item 76. A laminated glass panel according to item 71, wherein the alkali metal salt comprises potassium acetate having a strength of about 6.

[0169]

[0166] Item 77. The laminated glass panel according to item 71, wherein the alkali metal salt comprises magnesium di-2-ethylhexanoate having a strength of about 9.

[0170]

[0167] Item 78. A laminated glass panel as described in Item 71, wherein the resin of the first polymer layer of the polymer interlayer comprises at least 10 strength, at least 15 strength, at least 20 strength, and / or at least 25 strength potassium acetate.

[0171]

[0168] Item 79. A laminated glass panel as described in Item 71, wherein the resin of the first polymer layer of the polymer interlayer contains potassium acetate having a strength of 25 or less, 20 or less, 15 or less, 10 or less, and / or 6 or less.

[0172]

[0169] Item 80. The laminated glass panel described in Item 71, wherein the resin of the first polymer layer of the polymer interlayer comprises magnesium di-2-ethylhexanoate having a strength of at least 5, at least 10, and / or at least 15.

[0173]

[0170] Item 81. The laminated glass panel of item 71, wherein the resin of the first polymer layer of the polymer interlayer comprises magnesium di-2-ethylhexanoate having a strength of 15 or less, 10 or less, and / or 5 or less.

[0174]

[0171] Item 82. A laminated glass panel according to item 71, having a Yellowness Index value of less than about 1.00.

[0175]

[0172] Item 83. A laminated glass panel described in Item 71, wherein the yellowness index value of the laminated glass panel is less than about 0.75, less than about 0.50, less than about 0.25, less than about 0.00, less than about -0.25, and / or less than about -0.50.

[0176]

[0173] Item 84. A method for forming a polymeric interlayer that is resistant to the formation of optical defects, comprising the steps of: (a) extruding a first polymer melt to form a first polymer layer; and (b) extruding a second polymer melt to form a second polymer layer and a third polymer layer, wherein during the extrusion of steps (a) and (b), the first polymer layer is positioned between the second polymer layer and the third polymer layer, and the first polymer layer comprises a resin comprising an alkali metal salt having a strength of about 35 or less, and the alkali metal salt having a strength of at least 5 is potassium acetate.

[0177]

[0174] Item 85. The method described in Item 84, wherein the extrusion of steps (a) and (b) is carried out by coextrusion, the resin of the first polymer layer comprises poly(vinyl butyral), and the resin of the first polymer layer of the polymer intermediate layer comprises an alkali metal salt having a titer of about 25 or less.

[0178]

[0175] Item 86. The method according to Item 84, wherein the alkali metal salt consists essentially of potassium acetate.

[0179]

[0176] Item 87. The method of item 84, wherein the resin of the first polymer layer of the polymer intermediate layer comprises an alkali metal salt having a titer of about 15 or less.

[0180]

[0177] Item 88. The method according to Item 84, wherein the alkali metal salt comprises a combination of potassium acetate and magnesium di-2-ethylhexanoate.

[0181]

[0178] Item 89. The method according to Item 84, wherein the alkali metal salt comprises potassium acetate having a strength of about 6.

[0182]

[0179] Item 90. The method of Item 84, wherein the alkali metal salt comprises magnesium di-2-ethylhexanoate having a strength of about 9.

[0183]

[0180] Item 91. The method of Item 84, further comprising the step of (c) laminating a polymer interlayer between a pair of glass sheets to form a laminated glass panel, wherein upon lamination in step (c), the laminated glass panel has a Yellowness Index value of less than about 1.00.

[0184]

[0181] Item 92. The method of Item 84, further comprising the step of (c) laminating a polymer interlayer between a pair of glass sheets to form a laminated glass panel, wherein upon lamination in step (c), the laminated glass panel has a Yellowness Index value of less than about 0.75, less than about 0.50, less than about 0.25, less than about 0.00, less than about -0.25, and / or less than about -0.50.

[0185]

[0182] Item 93. The method of Item 84, wherein the thickness of the polymer interlayer is approximately constant along the length of the polymer interlayer.

[0186]

[0183] Item 94. The method of item 84, wherein the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape.

[0187]

[0184] Item 95. The method of item 84, wherein the first polymer layer is softer than the second and third polymer layers.

Claims

1. A polymer interlayer that is resistant to the formation of optical defects, comprising: a first polymer layer; a second polymer layer; and Third Polymer Layer Equipped with the first polymer layer is positioned between the second polymer layer and the third polymer layer; A polymeric interlayer, wherein the first polymeric layer comprises a resin comprising (i) a monovalent alkali metal salt having a titer of less than about 10, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

2. 10. The polymeric intermediate layer of claim 1, wherein the resin of the first polymer layer comprises poly(vinyl butyral), or the monovalent alkali metal salt in the first polymer layer comprises a potassium salt, or the monovalent alkali metal salt in the first polymer layer has a potency of less than about 9, less than about 8, less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than about 0.5, and / or about 0, or the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

3. The polymeric interlayer of claim 2, wherein the epoxide derivative comprises a mono-epoxide, or a di-epoxide, or an epoxidized vegetable oil.

4. 10. The polymeric interlayer of claim 1, wherein the organic acid scavenger in the first polymer layer is in the range of about 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

5. 10. The polymer interlayer of claim 1, wherein when the polymer interlayer is laminated between a pair of glass sheets to form a laminated glass panel, such glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

6. A polymer interlayer that is resistant to the formation of optical defects, comprising: a first polymer layer; a second polymer layer; and Third Polymer Layer Equipped with the first polymer layer is positioned between the second polymer layer and the third polymer layer; A polymeric interlayer, wherein the first polymeric layer comprises: (i) a resin comprising a first alkali metal salt and a second alkali metal salt having a titer of about 15 or less.

7. 7. The polymeric interlayer of claim 6, wherein the resin of the first polymer layer comprises poly(vinyl butyral), or the first alkali metal salt in the first polymer layer comprises a magnesium salt, or the second alkali metal salt in the first polymer layer comprises a potassium salt, or the first alkali metal salt and the second alkali metal salt in the first polymer layer comprise a combination of a magnesium salt and a potassium salt, or the first polymer layer further comprises an organic acid scavenger, or each of the first and second alkali metal salts in the first polymer layer is present in an amount of less than about 9 potency, less than about 8 potency, less than about 7 potency, less than about 6 potency, less than about 5 potency, less than about 4 potency, less than about 3 potency, less than about 2 potency, less than about 1 potency, less than about 0.5 potency, and / or less than about 0 potency, or the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

8. 8. The polymeric interlayer of claim 7, wherein the epoxide derivative comprises a mono-epoxide, or the epoxide derivative comprises a di-epoxide, or the epoxide derivative comprises an epoxidized vegetable oil.

9. 8. The polymeric interlayer of claim 7, wherein the organic acid scavenger in the first polymer layer is in the range of about 0.5-5 phr, 0.5-4 phr, 0.5-3 phr, 1-6 phr, 1-5 phr, 1-4 phr, 1-3 phr, 2-6 phr, 2-5 phr, 2-4 phr, 2-3 phr, 3-6 phr, 3-5 phr, 3-4 phr, 4-6 phr, 4-5 phr, and / or 5-6 phr.

10. 7. The polymer interlayer of claim 6, wherein when the polymer interlayer is laminated between a pair of glass sheets to form a laminated glass panel, such glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

11. A polymer interlayer that is resistant to the formation of optical defects, comprising: a first polymer layer; a second polymer layer, and Third Polymer Layer Equipped with the first polymer layer is positioned between the second polymer layer and the third polymer layer; A polymeric interlayer wherein the first polymeric layer comprises a resin containing an alkali metal salt of about 35 strength or less, and the alkali metal salt of at least 5 strength is potassium acetate.

12. or the alkali metal salt comprises a combination of potassium acetate and magnesium di-2-ethylhexanoate; or the alkali metal salt comprises potassium acetate having a potency of about 6; or the alkali metal salt comprises magnesium di-2-ethylhexanoate having a potency of about 9; or the resin of the first polymer layer of the polymer intermediate layer comprises an alkali metal salt having a potency of at least 10, at least 15, or at least 20. and / or at least 25 titers of potassium acetate, or a resin of the first polymer layer of the polymer interlayer comprises no more than 25 titers, no more than 20 titers, no more than 15 titers, no more than 10 titers, and / or no more than 6 titers of potassium acetate, or a resin of the first polymer layer of the polymer interlayer comprises at least 5 titers, at least 10 titers, and / or at least 15 titers of magnesium di-2-ethylhexanoate, or a resin of the first polymer layer of the polymer interlayer comprises no more than 15 titers, no more than 10 titers, and / or no more than 5 titers of magnesium di-2-ethylhexanoate.

13. 10. The polymer interlayer of claim 1, wherein the thickness of the polymer interlayer is substantially constant along the length of the polymer interlayer, or the thickness of the polymer interlayer varies along the length of the polymer interlayer such that the polymer interlayer has a wedge shape, or the first polymer layer is softer than the second and third polymer layers.

14. 1. A laminated glass panel that is resistant to the formation of optical defects, comprising: a first glass sheet; a second glass sheet; and The polymer interlayer of any one of claims 1 to 13. A laminated glass panel comprising:

15. 15. The laminated glass panel of claim 14 having a Yellowness Index value of less than about 1.00, or less than about 0.75, less than about 0.50, less than about 0.25, less than about 0.00, less than about −0.25, and / or less than about −0.

50.

16. 1. A method for forming a polymer interlayer that is resistant to the formation of optical defects, comprising: (a) extruding a first polymer melt to form a first polymer layer; (b) extruding the second polymer melt to form a second polymer layer and a third polymer layer; Including, During the extrusion of steps (a) and (b), a first polymer layer is positioned between the second polymer layer and the third polymer layer; A method wherein the first polymer layer comprises a resin comprising (i) a monovalent alkali metal salt less than about 10 titer, and (ii) an organic acid scavenger in the range of 0.5 to 6 phr.

17. 17. The method of claim 16, wherein the extrusion of steps (a) and (b) is performed by coextrusion, the resin of the first polymer layer comprises PVB, the monovalent alkali metal salt in the first polymer layer comprises a potassium salt, or the resin of the first polymer layer does not comprise a magnesium salt, or the monovalent alkali metal salt in the first polymer layer has a potency of less than about 9, less than about 8, less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than about 0.5, and / or about 0, or the organic acid scavenger in the first polymer layer comprises an epoxide derivative.

18. 17. The method of claim 16, wherein the organic acid scavenger in the first polymer layer is in the range of about 0.5 to 5 phr, 0.5 to 4 phr, 0.5 to 3 phr, 1 to 6 phr, 1 to 5 phr, 1 to 4 phr, 1 to 3 phr, 2 to 6 phr, 2 to 5 phr, 2 to 4 phr, 2 to 3 phr, 3 to 6 phr, 3 to 5 phr, 3 to 4 phr, 4 to 6 phr, 4 to 5 phr, and / or 5 to 6 phr.

19. (c) laminating the polymer interlayer between a pair of glass sheets to form a laminated glass panel. further comprising 17. The method of claim 16, wherein upon lamination in step (c), the laminated glass panel has a Yellowness Index value of less than 4, less than 3, less than 2, less than 1, and / or less than 0.

20. 1. A method for forming a polymer interlayer that is resistant to the formation of optical defects, comprising: (a) extruding a first polymer melt to form a first polymer layer; (b) extruding the second polymer melt to form a second polymer layer and a third polymer layer; Including, During the extrusion of steps (a) and (b), a first polymer layer is positioned between the second polymer layer and the third polymer layer; A method wherein the first polymer layer comprises a resin containing an alkali metal salt of about 35 strength or less, and the alkali metal salt of at least 5 strength is potassium acetate.

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