Polymer interlayer with low speckle and reduced ice flower defects

Abstract

A polymer interlayer that is resistant to optical defects. The polymer interlayer comprises a first polymer layer and a second polymer layer. The first polymer layer is disposed on a first side of the second polymer layer. The non-embossed surface of the first side of the second polymer layer has an R of greater than 40 microns. Z The polymer interlayer has a mottle value of less than 1.0.

Description

[Technical field]

[0001]

[0001] The present invention relates to the field of polymeric interlayers and multi-layer panels comprising polymeric interlayers, more particularly to the field of polymeric interlayers comprising multiple thermoplastic 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 softer 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 may optionally be added for various other purposes. After the interlayer sheet is formed, it 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 with multiple layers (or a combination of both) to be placed between two glass substrates to form a multi-layer glass panel with 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 nip rollers, vacuum bags, or another degassing mechanism. The interlayer is then 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, glass panels containing these multi-layer acoustic interlayers, under extreme conditions, can develop defects commonly known as ice flowers (also known as snowflakes), which initiate in the presence of excess residual trapped air in the panel and stresses in the glass. Specifically, during the manufacturing process of laminated multi-ply glass panel constructions, air and other gases are often trapped in the interstitial spaces between the substrates and the interlayer, or between the individual layers of the multi-layer interlayer, as these layers are stacked together to form the multi-layer interlayer. This trapped air is generally removed by vacuum or nip rolls that degas the construction in the glazing or panel manufacturing process. However, these techniques are not always effective in removing all of the air trapped in the interstitial spaces between the substrates. These air pockets are particularly evident in mismatched glass (e.g., tempered glass, heat-strengthened glass, and thick annealed glass) as well as windshields, where the curvature of the glass generally results in air gaps. These air gaps in windshields are commonly referred to as “flex gaps.” Furthermore, if flex gaps are present during autoclaving, the heat and pressure compress the glass and accommodate the interlayer, narrowing the gap and creating high stresses in the glass in the original gap area.

[0009] As noted above, degassing techniques are not always effective in removing all of the air from a glass panel assembly. As a result, residual air exists between the glass and the interlayer. During autoclaving, the residual air dissolves under heat and pressure into the interlayer, most often into the skin layer. Residual air located in the skin layer can migrate into the core layer or into the skin-core interface, eventually partitioning between the skin and core layers to reach equilibrium. If a large amount of residual air (e.g., excess residual air) is present in the interlayer, bubbles can nucleate, especially at high temperatures, when the interlayer becomes soft and less resistant to nucleation.

[0010] In a multi-layer acoustic interlayer having a soft core layer sandwiched between two harder skin layers, for example when the soft layer is constrained between two harder layers, bubbles will generally form first in the soft core layer because nucleation is favored in a less viscous medium. In warm to hot climates, for example during the summer months, the temperature of the glass can rise to 50°C to 100°C for laminated glass installed in buildings and vehicles. At these high temperatures, the forces due to stresses within the glass panel or windshield exert pressure on the glass perpendicular to its face and in the opposite direction, pulling the glass panels away from each other in an attempt to return to their original state. The stresses reduce the resistance of the nucleation and expanding air, causing bubbles to grow in the core layer.

[0011] At elevated temperatures (e.g., 50°C to 100°C), stresses due to bend gaps or glass mismatches cause the bubbles to expand in random radial directions within the core layer along the path of least resistance. As the defects continue to expand radially, branching and dendritic features form, resulting in the undesirable optical appearance of ice flowers. Furthermore, the formation of ice flowers within the core layer typically results in separation between the layers, reducing the structural integrity of the panel.

[0012]

[0012] A further problem in the manufacture of multi-layer laminated glass panels is the presence of mottle in the final integral structure. The term "mottle" refers to an unpleasant visual defect, i.e., the appearance of uneven spots, in the final integral structure. In other words, mottle is a measure of the graininess or texture of the surface area of ​​the inner polymer interlayer(s). It is a form of optical distortion. It is believed that mottle is caused by small-scale surface variations in the interface between layers of the laminate that have different refractive indices. The refractive index of a layer is a measure of the speed of light passing through that material. Mottle is theoretically possible in any multi-layer interlayer as long as there is a sufficiently large refractive index difference between the layers and there is some interfacial variation. The presence of mottle in the final integral structure of a multi-layer laminated glass panel can be problematic because many (if not most) of the end uses of commercial applications of multi-layer laminated glass panels (e.g., applications in vehicles, aircraft, and architecture) require a certain degree of optical quality.

[0013] In view of the above, there is a need in the art to develop a multi-layer interlayer that resists the formation of these optical defects (i.e., ice flowers and mottle) without reducing the 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 nucleation and expansion of air that forms ice flowers while also having acceptable mottle values. [Brief description of the drawings]

[0014] [Figure 1]

[0014] FIG. 1 is a schematic diagram of a glass laminate panel comprising a pair of glass plates facing a polymer interlayer, the polymer interlayer comprising three layers, a pair of skin layers facing a core layer. [Diagram 2]

[0015] 1 is another schematic diagram of a glass laminate panel comprising a pair of glass plates facing a polymer interlayer, the polymer interlayer having a wedge shape. [Diagram 3]

[0016] 1 is a schematic cross-sectional view of a coextrusion die having an opening defined by a die and / or a pair of die lips, the die being configured to coextrude multiple polymer interlayers. [Figure 4]

[0017] FIG. 2 is a close-up view of a polymer interlayer having a regular surface roughness pattern in the form of a tire track pattern formed on the surface of the polymer interlayer by melt fracture. [Diagram 5]

[0018] FIG. 2 is a close-up view of a polymer interlayer having a random surface pattern formed on the surface of the polymer interlayer. [Figure 6]

[0019] 1 is a photograph of a plurality of stacked inventive three-layer interlayers formed in accordance with an embodiment of the present invention, the inventive three-layer interlayers demonstrating a lack of ice flower formation; [Figure 7]

[0020] 1 is a photograph of a plurality of stacked control tri-ply interlayers formed according to a prior art process, the control tri-ply interlayers showing the presence of ice flower formation; Summary of the Invention [Means for solving the problem]

[0015]

[0021] One aspect of the invention relates to a polymer interlayer that is resistant to the formation of optical defects. The polymer interlayer comprises a first polymer layer and a second polymer layer. The first polymer layer is disposed on a first side of the second polymer layer. The non-embossed surface of the first side of the second polymer layer has an R of greater than 40 microns. Z The polymer interlayer has a mottle value of less than 1.0.

[0016]

[0022] Another aspect of the invention relates to a polymer interlayer that is resistant to the formation of optical defects. The polymer interlayer comprises a first polymer layer and a second polymer layer. The first polymer layer is disposed on a first side of the second polymer layer. The surface of the first side of the second polymer layer has an R of greater than 500 microns. SM The polymer interlayer has a mottle value of less than 1.0.

[0017]

[0023] A further aspect of the invention relates to a further method of making a polymer interlayer that resists the formation of optical defects. One step of the method includes extruding a first polymer layer through a coextrusion die. A further step includes extruding a second polymer layer through the coextrusion die. A further step includes extruding a third polymer layer through the coextrusion die. During the extrusion step, the first polymer layer is positioned between the second polymer layer and the third polymer layer. During the extrusion of the first polymer layer, the first polymer layer has a first storage modulus value. During the extrusion of the second polymer layer, the second polymer layer has a second storage modulus value. The difference between the first storage modulus value and the second storage modulus value is less than about 45,000 Pa. After the first, second, and third polymer layers are extruded, the polymer interlayer has a speckle value of less than 1.0.

[0018]

[0024] A further aspect of the invention relates to a polymeric interlayer resistant to the formation of optical defects formed using a method comprising the following steps: one step comprises extruding a first polymeric layer through a coextrusion die; a further step comprises extruding a second polymeric layer through the coextrusion die; a further step comprises extruding a third polymeric layer through the coextrusion die; during the extrusion step, the first polymeric layer is positioned between the second polymeric layer and the third polymeric layer; during the extrusion of the first polymeric layer, the first polymeric layer has a first storage modulus value; during the extrusion of the second polymeric layer, the second polymeric layer has a second storage modulus value; the difference between the first storage modulus value and the second storage modulus value is less than about 45,000 Pa; after the first, second, and third polymeric layers are extruded, the polymeric interlayer has a speckle value of less than 1.0. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019]

[0025] 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.

[0020]

[0026] 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.

[0021]

[0027] 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.

[0022]

[0028] 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 a polymer resin. The term "resin" as utilized herein refers to the polymeric component (e.g., PVB) that is 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. Additionally, the resin may have other components in addition to the polymer and plasticizer, as discussed further below.

[0023]

[0029] 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.

[0024]

[0030] 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. Furthermore, in some embodiments, it may be preferred that one or more of the polymer layers of the interlayer have a unimodal Mw distribution. For example, it may be preferred that the skin layer be formed from a PVB resin that includes a unimodal Mw distribution, because such a resin may aid in the production of a regular melt fraction pattern, as discussed below.

[0025]

[0031] 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.

[0026]

[0032] The resins described herein are generally referred to herein as "poly(vinyl acetal)" or "poly(vinyl butyral)", but may contain the residues of any suitable aldehyde, including, but not limited to, isobutyraldehyde, as previously discussed. In some embodiments, the one or more poly(vinyl acetal) resins comprise 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.

[0027]

[0033] 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 gThe glass transition temperature (T g ) is the temperature that marks the transition from the glassy to the rubbery state of the interlayer. Generally, a higher plasticizer loading results in a lower T g This may result in:

[0028]

[0034] 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.

[0029]

[0035] 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.

[0030]

[0036] Generally, the plasticizer content of the polymeric interlayers of the present 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 polymeric 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. In some embodiments, high stiffness interlayers comprise layers having a plasticizer content of less than about 35 phr and less than about 30 phr.

[0031]

[0037] 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.

[0032]

[0038] 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.

[0033]

[0039] 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.

[0034]

[0040] In addition to plasticizers, it is also contemplated that adhesion control agents ("ACAs") may be added to the polymer resins to form the polymer interlayer. The ACA generally functions to modify adhesion to the interlayer. Contemplated ACAs include, but are not limited to, the ACAs disclosed in U.S. Pat. No. 5,728,472, residual sodium acetate, potassium acetate, and / or magnesium bis(2-ethylbutyrate).

[0035]

[0041] Other additives may be incorporated into the interlayer to improve its performance in the final product and to impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., 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]

[0042] 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 complete. 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 of the acetate side groups are converted to hydroxyl groups. Furthermore, typically not all of the 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 utilized herein as a parameter, residual hydroxyl content is measured on a weight percent basis according to ASTM D-1396.

[0037]

[0043] In various embodiments, the poly(vinyl butyral) resin comprises from about 8 to about 35 weight percent (wt.%) residual hydroxyl groups calculated as PVOH, from about 13 to about 30 wt.% residual hydroxyl groups calculated as PVOH, from about 8 to about 22 wt.% residual hydroxyl groups calculated as PVOH, or from about 15 to about 22 wt.% residual hydroxyl groups calculated as PVOH, 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 calculated as PVOH, and greater than about 21 wt.% residual hydroxyl groups calculated as PVOH.

[0038]

[0044] 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]

[0045] 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]

[0046] 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]

[0047] 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]

[0048] 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.%, 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]

[0049] 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.

[0044]

[0050] 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).

[0045]

[0051] 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, paddle, 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 laminate of the present disclosure may be formed using processes known in the art.

[0046]

[0052] In the extrusion process, the thermoplastic resin and plasticizer, including any of the resins and plasticizers mentioned above, are generally premixed and fed into the extruder device. Additives such as colorants and UV inhibitors (liquid, powder or pellet form) may be used and may be mixed into the thermoplastic resin or plasticizer 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.

[0047]

[0053] 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. 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.

[0048]

[0054] 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 and deliver a steady processing volume of different thermoplastic melts of different viscosities or other properties as a desired final form through a coextrusion die. For example, the multi-layer interlayer of the present invention (e.g., in the form of a three-layer interlayer) may be preferably coextruded 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 polymer melts from each manifold, which converges the three extruded melt streams into a single opening 20 of the die 22 of the coextrusion device, as shown by FIG. 3. The opening 20 may be defined, at least in part, as a space or gap that exists between a first portion 24 (e.g., an upper portion) and a second portion 26 (e.g., a lower portion) of the die 22. In some embodiments, the opening 20 may be further defined by a pair of spaced apart die lips (i.e., a first die lip 28 and a second die lip 30) positioned at the exit of the opening 20. The coextrusion device may thus be configured to extrude a tri-layer interlayer comprising a composite of three individual polymer layers (e.g., a core layer 14 sandwiched between a pair of skin layers 16). In particular, a composite tri-layer interlayer may be coextruded through the opening 20, with a first skin layer 16 positioned adjacent a first portion 24 (e.g., an upper portion) and / or a first die lip 28 (e.g., an upper die lip) of the die 22, a second skin layer 16 positioned adjacent a second portion 26 (e.g., a lower portion) and / or a second die lip 30 (e.g., a lower die lip) of the die 22, and a core layer 14 sandwiched between the two skin layers 16 and coextruded through the die 22. Thus, during coextrusion, the core layer 14 generally does not contact either the first or second portions 24, 26 of the die 22 and / or the first or second die lips 28, 30.

[0049]

[0055] The thickness of the multiple polymer layers exiting the extrusion die 22 in a coextrusion process may generally be controlled by adjusting the relative velocity of the melts through the extrusion die 22 and / or adjusting the size of the die opening 20. In certain embodiments, the position of one or both of the die lips 28, 30 may be shifted relative to one another to increase or decrease the size of the opening 20. According to some embodiments, the total thickness of the multiple layer interlayer may be at least about 13 mils, at least about 20 mils, at least about 25 mils, at least about 27 mils, at least about 30 mils, at least about 31 mils, and / or about 75 mils or less, about 70 mils or less, about 65 mils or less, about 60 mils or less, or may 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 not more than about 50 mils, not more than about 40 mils, not more than about 30 mils, not more than about 20 mils, not more than about 17 mils, not more than about 15 mils, not more than about 13 mils, not more than about 12 mils, not more than about 10 mils, not more than about 9 mils. In some embodiments, each of the layers may have about the same thickness, while in other embodiments, one or more layers may have a different thickness than one or more other layers in the intermediate layer.

[0050]

[0056] 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.

[0051]

[0057] 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 may be at least about 2.25:1, at least about 2.4:1, at least about 2.5:1, at least about 2.8:1, at least about 3:1, at least about 3.5:1, at least about 4:1, at least about 4.5:1, at least about 5:1, at least about 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, or no more than about 8:1.

[0052]

[0058] The multi-layer interlayer 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 interlayer of the present invention may be a tapered or wedge-shaped interlayer 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 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.

[0053]

[0059] In certain embodiments, surface roughness may be formed in one or more layers of the interlayer. Generally, such surface roughness may be imparted by melt fracture or embossing. Melt fracture is a process of forming roughness on the surface of a layer of a polymer interlayer by controlling the composition of the melt, the temperature of the die lip, and / or the rate and manner of cooling of the extruded interlayer (e.g., the interlayer may be immersed in a cooling bath immediately after extrusion). (See, e.g., U.S. Pat. Nos. 5,595,818 and 4,654,179, the entire disclosures of which are incorporated herein by reference.) In some embodiments, it may be preferred that one or more layers of the interlayer are formed to have a "regular melt fracture pattern." As used herein, the term "regular melt fracture pattern" or "regular pattern" is used to mean a pattern that is generally repeated or repeatable. Examples of regular patterns include, but are not limited to, parallel channels, sawtooth patterns, geometric shapes such as rectangles, pyramids, etc., or combinations of patterns. Figure 4 shows a regular melt fracture pattern formed on a polymer layer, referred to as a "tire track" pattern. In contrast, a random pattern refers to a pattern that does not have a regular or repeating pattern across the surface. Figure 5 shows a random pattern formed on a polymer layer.

[0054]

[0060] In the case of three individual layers that are laminated together to form a three-layer interlayer, any of the surfaces of the three layers may be formed to have a regular pattern surface roughness by melt fracture prior to or during assembly of the layers. In various embodiments, one or both of the two surfaces of the individual polymer layers that form the outer skin layer 16 of the three-layer interlayer may be formed to have a regular pattern surface roughness by melt fracture.

[0055]

[0061] According to an embodiment of the present invention, one or both surfaces of the outer skin polymer layer are z " or "R smThe polymer layer is modified using controlled melt fracture to produce a polymer layer having a desired regular pattern surface roughness, which can be measured by the R z R is a measure of the surface topography of the polymer layer and is a measure of the deviation of the surface from a plane (e.g., an imaginary plane indicated by the planarized surface of the polymer layer). sm R is a measure of the distance between peaks in the topography of the surface of a polymer layer. Both measurements are explained in detail below. As used herein, R z and R sm Regarding "imparted by melt fracture" means R z and R sm This means that the surface texture, as measured by, is generated by the melt fracture phenomenon at the time of extrusion.

[0056]

[0062] For a typical surface pattern, the surface roughness, or the height of a particular peak on the roughened surface from an imaginary plane on the surface of the planarized polymer layer, is the R z As described in this application, the surface roughness or R z is expressed in microns (μm) as measured by the 10-point average roughness scale according to DIN ES ISO-4287 of the International Organization for Standardization, and ASME B46.1 of the American Society of Mechanical Engineers. Generally, on these scales, R z is the single roughness depth R of the continuous sampling length zi (i.e., the perpendicular distance between the highest peak and the deepest groove within the sampling length).

[0057]

[0063]

[0058]

number

[0059]

[0064] Another surface parameter that is described and measured is the average spacing R sm The average interval R smR describes the average width, expressed in microns (μm), between peaks on the surface of the polymer interlayer sheet. sm and R z The values ​​can be used to measure the surface topography of both embossed and non-embossed polymer interlayer sheets. Generally, however, the surface roughness described herein as being imparted on the surface of a polymer layer is imparted by a non-embossing process, for example, by melt fracture.

[0060]

[0065] Each polymer layer has a specified R z and / or R sm The resulting interlayer having the above indicated R formed by melt fracture and present on at least one, and preferably both, of the outer layers of the three-layer interlayer can be easily laminated between two glazing layers, such as glass. z and R sm The value results in an outer surface that, after being placed in contact with a glass layer and laminated, can be easily degassed using, for example, a nip roll or vacuum ring degassing process.

[0061]

[0066] However, as noted above, glass panels containing multiple interlayers may contain objectionable visual defects and / or optical distortions in the final integral structure. Such defects / distortions can be referred to as mottle, which is a measure of the graininess or texture of the surface region of the polymer interlayer. Mottle is believed to be caused by small-scale surface variations at the interface between layers of laminates having different refractive indices.

[0062]

[0067] Traditionally, the assessment of the degree or amount of mottle in multi-layer glass panels was determined using a technique based on shadowgraphs. Shadowgraphs are optical methods that reveal inhomogeneities in transparent media such as air, water, or glass. In principle, the human eye without aid cannot directly discern differences or disturbances in transparent air, water or glass. However, all these disturbances / differences refract light rays and therefore they can cast shadows. Shadowgraphs exploit this property of the ability of laminate disturbances or differences to be able to cast shadows and use it to project an image of the laminate inhomogeneity onto a screen.

[0063]

[0068] In a conventional process for identifying mottle, the degree of mottle is assessed and classified by a side-by-side qualitative comparison of the shadowgraph projection of the multi-layer test laminate with a set of standard laminate shadowgraphs (e.g., CMS2.5 standard laminate with a scale of 0 to 4) that represent a series of mottle values ​​or scales ranging from 0 to 4, with 0 representing no mottle (e.g., a piece of glass with no interlayer), 1 representing a low mottle criterion (i.e., few disturbances), and 4 representing a high mottle criterion (i.e., many disturbances), which is optically unpleasant. In some embodiments, the qualitative comparison may be performed by human eye or by a computer-implemented test. For example, a mottle analyzer device may be used, in which a camera is positioned approximately perpendicular to a reflective screen on which a shadowgraph is depicted. The camera may take an image of the shadowgraph(s) and a computer device may perform the necessary comparisons to obtain a mottle value for the sample being tested.

[0064]

[0069] For example, the mottle values ​​described herein were determined using a Clear Mottle Analyzer (CMA), which includes a xenon arc lamp, a sample holder, a projection screen, and a digital camera. The xenon arc lamp is used to project a shadowgraph of the laminate sample onto the screen, and the camera is configured to take an image of the resulting shadowgraph. The image is then digitally analyzed using computer imaging software and compared to previously taken images of standard samples to determine the mottle of the sample. The method of measuring mottle using the CMA is described in detail in U.S. Pat. No. 9,311,699, the entirety of which is incorporated herein by reference.

[0065]

[0070] As also disclosed above, optical defects known as ice flowers are commonly found in glass panel laminates that include multiple interlayers. The formation of ice flowers in three-ply acoustic PVB laminates can be tested by simulating real-world conditions in windshields and other glazing, where a combination of large bending gaps and insufficient degassing is known to be one of the root causes of ice flower development in the field. The following steps describe an ice flower test that can be used to measure the formation of ice flowers in interlayers. First, a 30 cm x 30 cm three-ply interlayer with a centrally located polyethylene terephthalate (PET) film ring (having an inner diameter of 7.5 cm, an outer diameter of 14 cm, and a thickness of 0.10 mm to 0.18 mm) is sandwiched between two 30 cm x 30 cm pieces of glass. The construction is then prelaminated and autoclaved. The resulting laminate is conditioned at room temperature for 48 hours, baked in a conventional oven (80°C) for 48 hours, and then cooled. The laminate can then be visually inspected to determine the percentage of ice flower formation within the laminate (e.g., the percentage of the laminate that has developed ice flower defects) and the percentage of the area within the PET ring that has ice flower defects. Additionally, the laminate can be visually inspected to determine the percentage of ice flower formation within the entire laminate (including both inside and outside the PET film area).

[0066]

[0071] In view of the above, an embodiment of the present invention includes a polymeric interlayer having reduced mottle and resistance to the formation of ice flower defects. The polymeric interlayer may comprise a first polymeric layer (e.g., a core layer) and a second polymeric layer (e.g., a skin layer), the first polymeric layer being disposed on a first side of the second polymeric layer. The non-embossed surface of the first side of the second polymeric layer has an R of greater than 40 microns. Z In some embodiments, the second side of the second polymer layer (opposite the first side) also has a surface roughness defined by an R value of greater than 40 microns.Z Such second side of the second polymer layer may form the outer surface of the polymer interlayer. In some embodiments, the polymer interlayer may be an interlayer having a third polymer layer (e.g., a skin layer) disposed on the second side of the first polymer layer such that the second and third polymer layers sandwich the first polymer layer. In some embodiments, the first and / or second sides of the third polymer layer also have a surface roughness defined by an R value of greater than 40 microns. Z The third polymer layer may include a surface roughness defined by a value. A first side of the third polymer layer may be in contact with the first polymer layer, while a second side of the third polymer layer (opposite the first side) may form an outer surface of the intermediate layer. Such a surface roughness of the second and third polymer layers may have a regular pattern formed by melt fracture.

[0067]

[0072] In some embodiments, the surface roughness of the first and / or second surface of the second polymer layer (i.e., one of the skin layers) is formed by melt fracture. z The surface roughness, as defined by the value, is greater than 40 microns, greater than 50 microns, greater than 60 microns, or greater than 70 microns, and / or R z The value is 40-70 microns, 40-60 microns, 40-50 microns, 50-70 microns, 50-60 microns, or 60-70 microns. In some embodiments, each of the first and second side surfaces of the second and third polymer layers (i.e., skin layers) can be formed to have a surface roughness as discussed above. In addition to such surface roughness, the interlayer may, in some embodiments, have a mottle value of less than 0.9, less than 0.8, less than 0.7, less than 0.6, or less than 0.5, and / or the mottle value may be 0.0-1.0, 0.25-1.0, 0.5-1.0, 0.5-0.9, 0.5-0.8. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer panel, the multilayer panel can be essentially free of ice flower formation.

[0068]

[0073] Additionally or in conjunction therewith, the polymeric interlayer may comprise a first polymeric layer (e.g., a core layer) and a second polymeric layer (e.g., a skin layer), the first polymeric layer being disposed on a first side of the second polymeric layer. The non-embossed surface of the first side of the second polymeric layer has an R of greater than 500 microns. sm In some embodiments, the polymer interlayer has a surface roughness defined by a R value of greater than 500 microns. Additionally, the polymer interlayer has a mottle value of less than 1.0. In some embodiments, the first side of the second polymer layer may be in contact with the first polymer layer. Additionally, the second side of the second polymer layer (opposite the first side) also has a surface roughness defined by a R value of greater than 500 microns. sm Such second side of the second polymer layer may form the outer surface of the intermediate layer. In some embodiments, the polymer intermediate layer may be an intermediate layer having a third polymer layer (e.g., a skin layer) disposed on the second side of the first polymer layer such that the second and third polymer layers sandwich the second polymer layer. In some embodiments, the first and / or second sides of the third polymer layer also have a surface roughness defined by an R value of greater than 500 microns. sm The third polymer layer may include a surface roughness defined by a value. A first side of the third polymer layer may be in contact with the first polymer layer, while a second side of the third polymer layer (opposite the first side) may form an outer surface of the intermediate layer. Such a surface roughness of the second and third polymer layers may have a regular pattern formed by melt fracture.

[0069]

[0074] In some embodiments, the surface roughness of the surface of the first side of the second polymer layer (i.e., the skin layer) is formed by a non-embossing process, for example, by melt fracture. sm The surface roughness, as defined by the value, is greater than 400 microns, greater than 500 microns, greater than 600 microns, greater than 700 microns, or greater than 800 microns, and / or R smThe values ​​are 400-800 microns, 500-800 microns, 400-700 microns, 500-700 microns, 400-600 microns, 500-600 microns, 600-700 microns, 600-700 microns, or 700-800 microns. In some embodiments, each of the first and second side surfaces of the second and third polymer layers (i.e., skin layers) can be formed to have a surface roughness as discussed above. In addition to such surface roughness, the intermediate layer may, in some embodiments, have a mottle value of less than 0.9, less than 0.8, less than 0.7, less than 0.6, or less than 0.5, and / or the mottle value is 0.0-1.0, 0.25-1.0, 0.5-1.0, 0.5-0.9, or 0.5-0.8. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer panel, the multilayer panel can be essentially free of ice flower formation.

[0070]

[0075] The above-mentioned polymer interlayers can be formed by controlling temperature attributes of the coextrusion process. For example, an embodiment of the present invention includes a method of forming a polymer interlayer that is resistant to the formation of optical defects. The method includes extruding a first polymer layer (e.g., a core layer) through a coextrusion die. A further step includes extruding a second polymer layer (e.g., a skin layer) through the coextrusion die. During the extrusion of the second polymer layer, the second polymer layer contacts the die lip of the coextrusion die. A further step includes extruding a third polymer layer (e.g., another skin layer) through the coextrusion die. During the extrusion step, the first polymer layer is positioned between the second polymer layer and the third polymer layer and disposed on a first side of the second polymer layer. During the extrusion of the second polymer layer, the surface of the first side of the second polymer layer is formed to have a surface roughness due to melt fracture. During the extrusion step, the temperature of the die lip is at least 10° C. higher than the temperature of the first polymer. Additionally, during the extrusion step, the polymer interlayer has a speckle value of less than 1.0.

[0071]

[0076] The process may also be described as one in which the melt stream forming the first polymer layer (e.g., core layer) is extruded through a coextruder at a different temperature than the melt streams forming the second and / or third polymer layers (e.g., skin layers). Thus, during extrusion of the polymer layers, the surface of the first side of the second polymer layer is formed to have surface roughness due to melt fracture (e.g., R 1 as discussed above). z and / or R sm In particular, such melt fracture can be controlled by controlling the temperature of the die lip in contact with the melt stream forming the second polymer layer. Thus, the temperature difference between the first polymer layer (i.e., the core layer not in contact with the die lip) and the second polymer layer (i.e., the skin layer not in contact with the die lip) can be controlled during extrusion. For example, in some embodiments, the requisite surface roughness (e.g., R of greater than 40 microns) of the first side surface of the second polymer layer (i.e., the skin layer) required for beneficial reduction of ice flower formation can be achieved while maintaining low mottle of the intermediate layer by ensuring that the temperature of the die lip is at least 10° C. higher than the temperature of the melt stream used to form the first polymer layer (i.e., the core layer) as the polymer layers exit the die. z and / or R greater than 500 microns sm ) can be achieved. The second surface of the second polymer layer can also be formed to have surface roughness by melt fracture in a similar manner as discussed above (i.e., by controlling the temperature of the die lip of the co-extruder). In any event, upon extrusion of the first and second polymer layers, embodiments of the present invention provide a polymer interlayer having a mottle value of less than 1.0. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer panel, the multilayer panel can be essentially free of ice flower formation.

[0072]

[0077] In some embodiments, the first and / or second sides of the third polymer layer (i.e., the remaining skin layer of the intermediate layer) may also be formed to have a regular pattern surface roughness formed by melt fracture. Such melt fracture on the surface(s) of the third polymer layer may be controlled by controlling the temperature of the die lip in contact with the melt stream forming the third polymer layer in a manner similar to that discussed above.

[0073]

[0078] For example, the temperature of one or both of the die lips may be at least 10° C., at least 20° C., at least 30° C., at least 40° C., or at least 50° C. higher than the temperature of the first melt stream and / or first polymer layer (i.e., the core layer) during the extrusion process. Additionally or in conjunction with this, the temperature of one or both of the die lips may be greater than 160° C. during extrusion of the second and / or third polymer layers (i.e., the skin layers). In some embodiments, the temperature of one or both of the die lips is greater than 170° C., greater than 180° C., greater than 190° C., greater than 200° C., or greater than 210° C. during extrusion of the second and / or third polymer layers, and / or the temperature of one or both of the die lips is 160° C.-210° C., 160° C.-200° C., 170° C.-200° C., 180° C.-200° C., 190° C.-210° C., or 200° C.-210° C. during extrusion of the second and / or third polymer layers. The temperature of the first melt stream used to form the first polymer layer (i.e., core layer) may be 140° C.-170° C. during extrusion of the first polymer layer (e.g., core layer).

[0074]

[0079] During extrusion of the intermediate layer of the present invention, the regular pattern surface roughness formed on the surface of the second and third polymer layers (i.e., on the skin layer) can be controlled by controlling the temperature of the die lip, while the mottle of the resulting intermediate layer can be controlled by controlling the temperature difference between the die lip and the temperature of the first melt stream used to form the first polymer layer (i.e., the core layer). Such control of the temperature difference can improve the rheological similarity between the skin layer and the core layer so as to improve the mottle characteristics of the intermediate layer. For example, during extrusion of the intermediate layer, the temperature difference between one or both of the die lips and the temperature of the first melt stream can be at least 10°C, at least 20°C, at least 30°C, at least 40°C, or at least 50°C, and / or 50°C or less, 40°C or less, 30°C or less, 20°C or less, 10°C or less, or 5°C or less. Similarly, in some embodiments, during extrusion of the intermediate layer, the temperature difference between one or both of the die lips and the temperature of the first melt stream may be 5°C to 50°C, 10°C to 50°C, 10°C to 40°C, 10°C to 30°C, 10°C to 20°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 50°C, 30°C to 40°C, or 40°C to 50°C.

[0075]

[0080] The preferred speckle value (e.g., less than 1.0) of the interlayer discussed above may be associated with a particular delta G' value and / or delta G' range for one of the skin layers (e.g., the second or third polymer layer) and the core layer (e.g., the first polymer layer). Delta G' is the difference between the storage modulus values ​​of the two layers. Storage modulus is a measure of a material's resistance to deformation and is generally given in Pascals (Pa). The storage modulus of each layer of the interlayer described herein may be measured according to ASTM D-4065. For example, the storage modulus value may be obtained using dynamic mechanical thermal analysis (DMTA), for example, by using a TA DHR-2 rheology instrument. A sample of the polymer layer may be clamped and placed under tension in a test cell. The temperature of the test cell may be initially set to 75°C. A sinusoidal tensile strain may be applied to the sample at a given frequency over a temperature range, and the resulting stress response is measured. For example, a sinusoidal tensile strain at 1 Hz may be applied to the sample while the temperature of the sample may be shifted from 20°C to 200°C. The rate of temperature increase may be about 3°C ​​per minute, and data (i.e., the stress of the sample) may be collected every 10 seconds. The storage modulus may be obtained from the ratio of stress to strain, with the understanding that the storage modulus value of a given sample will generally vary with the temperature applied to the sample. For oscillatory tensile deformation, the storage modulus is the real part of the complex modulus. Once the storage modulus values ​​of one of the skin layers and the core layer are obtained, the difference between such storage values ​​may be calculated to obtain the delta G' value.

[0076]

[0081] The present invention includes a polymer interlayer that is resistant to the formation of optical defects, and / or a method of making a polymer interlayer, such a polymer interlayer having a polymer layer with a preferred delta G' value. For example, the present invention may include a polymer interlayer formed according to the following method: One step includes extruding a first polymer layer (e.g., a core layer) through a coextrusion die. A further step includes extruding a second polymer layer (e.g., a skin layer) through a coextrusion die. A further step includes extruding a third polymer layer (e.g., a skin layer) through a coextrusion die. During the extrusion step, the first polymer layer is positioned between the second polymer layer and the third polymer layer. During the extrusion of the first polymer layer, the first polymer layer has a first storage modulus value. During the extrusion of the second polymer layer, the second polymer layer has a second storage modulus value. The difference between the first storage modulus value and the second storage modulus value (ie, the delta G' value) may be less than about 45,000 Pa. During the extrusion step, the polymer interlayer has a speckle value of less than 1.0.

[0077]

[0082] Embodiments of the present invention may provide an intermediate layer having a delta G' value between one of the skin layers (e.g., the second or third polymer layer) and the core layer (e.g., the first polymer layer) of less than 60,000 Pa, less than 55,000 Pa, less than 50,000 Pa, less than 45,000 Pa, less than 40,000 Pa, less than 35,000 Pa, less than 30,000 Pa, less than 25,000 Pa, less than 20,000 Pa, less than 15,000 Pa, less than 10,000 Pa, or less than 5,000 Pa, measured during coextrusion of the intermediate layer through a coextrusion device. In some embodiments, the delta G' value between one of the skin layers and the core layer may be 5,000-60,000 Pa, 5,000-50,000 Pa, 5,000-40,000 Pa, 5,000-30,000 Pa, 10,000-50,000 Pa, 10,000-40,000 Pa, 10,000-30,000 Pa, 15,000-50,000 Pa, 15,000-40,000 Pa, 15,000-30,000 Pa, 20,000-50,000 Pa, 20,000-40,000 Pa, or 20,000-30,000 Pa.

[0078] Example 1

[0083] Two three-layer interlayers were formed, each comprising a core layer sandwiched between a pair of skin layers. Skin layers with regular melt fracture patterns were formed by controlling the lip temperature of the die lips used to form the skin layers. The skin layers were formed from a PVB resin having a monomodal molecular weight distribution and a polydispersity index of less than 3.0. The skin layer resin included 38 phr of plasticizer, and optionally an adhesion modifier and a UV stabilizer. The core layer resin included PVB and included 75 phr of plasticizer, and optionally an adhesion modifier and a UV stabilizer. The interlayers were formed by a coextrusion process. The hot die lip gap during extrusion with the die lip bolts operating at 30% power was set at 41 mils (1.04 mm). The extrusion rate was set at 550 lb / hr (250 kg / hr). The melt pipe, EAMF filter, die lip for the skin layers, and body temperatures were set at 204°C. The core melt temperature of the core layer was set between 170°C and 180°C.

[0079]

[0084] The first three-layer interlayer EX1-IIL1 was formed to have a lower surface roughness than the second three-layer interlayer EX2-IIL2. The surface roughness measurements of both exterior sides (i.e., both exterior surfaces of the associated skin layers) of each of EX1-IIL1 and EX1-IIL2 are set forth below in Table 1. MD refers to the surface roughness in the machine direction and CMD refers to the surface roughness in the cross direction. The mottle of each three-layer interlayer was also measured.

[0080] [Table 1]

[0081]

[0085] As shown by the data from Example 1, favorable mottle values ​​(e.g., mottle values ​​less than 1.0) were obtained by controlling the regular pattern surface roughness of the skin layer imparted by melt fracture. In particular, surface roughness values ​​R of 40 to 60 microns were obtained. z and / or R of 400 to 700 microns sm A three-ply interlayer having a skin layer having a surface roughness value R of greater than 60 microns, such as EX1-IIL1, provides a three-ply interlayer having a preferred mottle value of less than 1.0. z and / or R greater than 800 microns sm A three-layer interlayer having a skin layer having a thickness of 0.01 to 0.01 exhibited such an interlayer having an objectionable mottle value of greater than 1.0.

[0082] Example 2

[0086] Two inventive three-layer interlayers (inventive interlayers of Example 2: EX2-IIL1 and EX2-IIL2) were formed following the same process described above for EX1-IIL1 and EX1-IIL2 in Example 1. Thus, each inventive interlayer EX2-IIL1 and EX2-IIL2 includes a core layer sandwiched between a pair of skin layers, and the skin layers were formed with a regular melt fracture pattern by controlling the lip temperature of the die lip used to form the skin layers. The resulting inventive three-layer interlayers EX2-IIL1 and EX2-IIL2 had a surface roughness value R of 40 to 60 microns. z and R of 400 to 700 microns sm , as well as speckle values ​​less than 1.0.

[0083]

[0087] Two control three-layer interlayers (Control Interlayers of Example 2: EX2-CIL1 and EX2-CIL2) were formed using a standard prior art process that uses embossing to create surface roughness in the skin layer. In contrast to the inventive interlayers, the surface of the skin layer of the control interlayers was not formed by melt fracture. Instead, the control interlayers included a surface pattern on the skin layer that was formed by embossing.

[0084]

[0088] Table 2, shown below, shows the measured mottle values ​​for each of EX2-IIL1, EX2-IIL2, EX2-CIL1 and EX2-CIL2. Such mottle values ​​were measured immediately after the formation of the intermediate layer (e.g., time zero) and 35 days after the intermediate layer was formed. Table 2 also shows the average mottle values ​​for the intermediate layer of the present invention and the control intermediate layer.

[0085] [Table 2]

[0086]

[0089] As shown by the data from Example 2, by controlling the regular pattern surface roughness of the skin layer imparted by melt fracture, excellent and highly desirable mottle values ​​(e.g., mottle values ​​less than 1.0) can be obtained. Such mottle values ​​were optimally maintained below 1.0 immediately after formation and 35 days after formation in each of the inventive interlayers EX2-IIL1 and EX2-IIL2. In contrast, the control interlayers EX2-CIL1 and EX2-CIL2 (which included a surface roughness created by embossing) included mottle values ​​less than 1.0 immediately after formation, but after 35 days the control interlayers had undesirable mottle values ​​greater than 1.0.

[0087] Example 3

[0090] Ten inventive three-layer interlayers (inventive interlayers of Example 3: EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) were formed following the same process as described above for EX1-IIL1 and EX1-IIL2 in Example 1. Thus, each inventive interlayer EX3-IIL1 to EX3-IIL10 includes a core layer sandwiched between a pair of skin layers, and the skin layers were formed with a regular melt fracture pattern by controlling the lip temperature of the die lip used to form the skin layers. The resulting inventive three-layer interlayers EX3-IIL1 to EX3-IIL10 had surface roughness values ​​R of 40 to 60 microns. z and R of 400 to 700 microns sm values, as well as speckle values ​​less than 1.0.

[0088]

[0091] Additionally, ten control three-layer interlayers (Control Interlayers of Example 3: EX3-CIL1, EX3-CIL2, ..., EX3-CIL10) were formed using a standard prior art process of forming surface roughness in the skin layer using embossing. In contrast to the inventive interlayers, the surface of the skin layer of the control interlayers was not formed by melt fracture. Instead, the control interlayers included a surface pattern on the skin layer formed by embossing.

[0089]

[0092] Each of the three-layer interlayers of the present invention and the control interlayers was tested according to the ice flower test described above. Notably, none of the laminates formed with the three-layer interlayers of the present invention (EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) showed any ice flower formation. Specifically, FIG. 6 is a photograph of a stack of laminates each comprising one of the three-layer interlayers of the present invention (EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) laminated between a pair of glass sheets. As shown, none of such laminates show any ice flower formation. In contrast, each of the laminates formed with the control three-layer interlayers (EX3-CIL1, EX3-CIL2, ..., EX3-CIL10) was found to contain various degrees of ice flower formation, as shown in FIG. 7, which is a photograph of a stack of laminates formed with the control three-layer interlayers. Specifically, as shown in FIG. 7, the lower portions of the laminate formed with the control three-ply interlayer were found to contain ice flower formations.

[0090] Example 4

[0093] Two inventive three-layer interlayers (inventive interlayers of Example 4: EX4-IIL1 and EX4-IIL2) were formed following the same process described above for EX1-IIL1 and EX1-IIL2 in Example 1. Thus, each inventive interlayer EX4-IIL1 and EX4-IIL2 includes a core layer sandwiched between a pair of skin layers, with the skin layers formed having a regular melt fracture pattern by controlling the lip temperature of the die lip used to form the skin layers. The resulting inventive three-layer interlayers EX4-IIL1 and EX4-IIL2 had surface roughness values ​​R of 40 to 60 microns. z and / or R of 400 to 700 microns sm , as well as speckle values ​​less than 1.0.

[0091]

[0094] Two embossed control three-layer interlayers (Control Interlayers of Example 4: EX4-CIL1 and EX4-CIL2) were formed using a standard prior art process of forming surface roughness in the skin layer using embossing. In contrast to the inventive interlayers, the surface of the skin layer of the control interlayer was not formed by melt fracture. Instead, the control interlayer included a surface pattern on the skin layer formed by embossing.

[0092]

[0095] Additionally, two random melt fracture control three-layer interlayers (Control Interlayers of Example 4: EX4-RIL1 and EX4-RIL2) were formed using prior art processes. In contrast to the inventive interlayers, the surfaces of the skin layers of the control interlayers were not formed to have a regular pattern surface roughness by melt fracture. Instead, the random control interlayers included a random surface pattern on the skin layers formed by melt fracture.

[0093]

[0096] Each of the interlayer samples was tested for light transmission after vacuum bag degassing. Vacuum bag degassing is a technique used to evacuate air from samples prior to the final step of autoclaving. It may often be used to improve autoclave yields in commercial operations. Each of the interlayer samples was placed between two glass plates and laminated to form a laminate panel. Note that one of each of the samples was laminated with a flat unformed glass panel (referred to as "unformed" in Table 3) and the other of each of the samples was laminated with a shaped (e.g., curved) glass panel (referred to as "formed" in Table 3). The laminate panel was then placed in a resilient rubber bag, which was then evacuated by a vacuum hose connected to the bag. The bag was brought to a temperature of approximately 50° C. under vacuum and held for 60 minutes, then held at 120° C. for 20 minutes. The bag was then cooled and the resulting panel was removed and placed in an autoclave for final finishing.

[0094]

[0097] Light transmission measurements were taken as a percentage after vacuum bag degassing and before autoclaving. A low light transmission percentage value indicates insufficient degassing, while a high light transmission percentage value indicates acceptable degassing. Light transmission was tested using a spectrophotometer. Each laminate was tested eight times at locations distributed throughout the laminate, and the eight results were averaged to obtain the light transmission values ​​shown in Figure 3, where LT is the light transmission percentage.

[0095] [Table 3]

[0096]

[0098] As can be seen from Table 3 above, the two embossed control three-layer interlayers EX4-CIL1 and EX4-CIL2 exhibited the best light transmission properties (highest light transmission percentage, which indicated better or acceptable degassing), while the two random control three-layer interlayers EX4-RIL1 and EX4-RIL2 exhibited the worst or worst light transmission properties (lowest light transmission percentage, which indicated unacceptable degassing). The two inventive three-layer interlayers EX4-IIL1 and EX2-IIL4 exhibited improved light transmission properties (i.e., improved or higher light transmission percentage, which indicated acceptable degassing) over the two random control three-layer interlayers EX4-RIL1 and EX4-RIL2. Thus, this example shows that the inventive three-layer interlayers can be adequately degassed by a standard vacuum bag degassing process, while the random three-layer interlayers formed with a random melt fracture pattern cannot be adequately degassed by such a standard vacuum bag degassing process. Specifically, the random tri-layer interlayer must also be embossed (as in the case of the control tri-layer interlayer) in order to be adequately degassed, whereas the tri-layer interlayer of the present invention does not need to be further embossed in order to be adequately degassed.

[0097] Example 5

[0099] Four polymer layers (polymer layers of Example 5: EX5-PL1, EX5-PL2, EX5-PL3, and EX5-PL4) were formed. The polymer layers of Example 5 were then tested according to ASTM D-4065 as discussed below to determine storage modulus values ​​for the polymer layers at various temperatures. Once such storage modulus values ​​were determined, delta G' values ​​were calculated to compare EX5-PL4 to each of EX5-PL1, EX5-PL2, and EX5-PL3.

[0098] [000100] For the EX5-PL1, EX5-PL2, and EX5-PL3 polymer layers, such polymer layers were formed by mixing PVB resin and 38 phr of plasticizer. The resin of the EX5-PL1 polymer layer had a molecular weight of 150K Daltons, while the resin of the EX5-PL2 and EX5-PL3 polymer layers had a molecular weight of 160K Daltons.

[0099] [000101] For the EX5-PL4 polymer layer, the polymer layer included PVB and 75 phr of plasticizer. The resin of the EX5-PL4 polymer layer had a molecular weight of 250-300K Daltons. Considering the composition of the polymer layers in Example 5 above, EX5-PL4 generally corresponds to the core layer of an acoustical tri-ply interlayer, while EX5-PL1, EX5-PL2, and EX5-PL3 generally correspond to the skin layers of an acoustical tri-ply interlayer.

[0100] [000102] As previously described, dynamic mechanical thermal analysis (DMTA) was used to obtain storage modulus values ​​for each of the polymer layers of Example 5. Storage modulus values ​​were then obtained for the polymer layers at various temperatures, as shown in Table 4 below. For the EX5-PL1 and EX5-PL2 polymer layers, storage modulus values ​​were obtained at 10°C intervals for temperatures between 140°C and 200°C. For the EX5-PL3 polymer layer, storage modulus values ​​were obtained for a temperature of 200°C. For the EX5-PL4 polymer layer, storage modulus values ​​were obtained for temperatures between 170°C and 180°C.

[0101] [000103] Having obtained the storage modulus of the polymer layers of Example 5, the difference in such storage modulus value of EX5-PL4 compared to each of EX5-PL1, EX5-PL2, and EX5-PL3 was calculated to obtain the delta G' value (at the indicated temperature) of such sample. The resulting delta G' values ​​are shown in Table 4 below. Note that the delta G' values ​​were obtained by subtracting the storage modulus values ​​of EX5-PL1, EX5-PL2, and / or EX5-PL3, respectively, from the storage modulus value of EX5-PL4. Thus, a positive delta G' value indicated that the EX5-PL4 polymer layer (i.e., the core layer) was relatively softer than the EX5-PL1, EX5-PL2, and / or EX5-PL3 polymer layers (i.e., the skin layers). In contrast, a negative delta G' value indicates that the EX5-PL4 polymer layer is relatively harder than the EX5-PL1, EX5-PL2, and / or EX5-PL3 polymer layers.

[0102] [Table 4]

[0103] [000104] As shown by Table 4, the delta G' values ​​obtained comparing the EX5-PL1 and EX5-PL4 polymer layers were about 30,000 Pa or less when the DMTA test temperature of the EX5-PL1 polymer layer was about 160°C or more (and the temperature of the EX5-PL4 polymer layer was about 170°C or 180°C). The mottle values ​​of the intermediate layers formed with the EX5-PL1 and EX5-PL4 polymer layers were estimated to be 1.0 or less when the DMTA test temperature of the EX5-PL1 polymer layer was about 160°C or more. In contrast, the mottle values ​​of the intermediate layers formed with the EX5-PL1 and EX5-PL4 polymer layers were estimated to be greater than 1.0 when the DMTA test temperature of the EX5-PL1 polymer layer was less than 160°C. Thus, the delta G' values ​​and corresponding estimated mottle values ​​in Table 4 indicate that interlayers formed with EX5-PL1 and EX5-PL4 polymer layers had favorable mottle values ​​(i.e., 1.0 or less) when the delta G' value was about 30,000 Pa or less. In contrast, Table 4 indicates that interlayers formed with EX5-PL1 and EX5-PL4 polymer layers had unfavorable mottle values ​​(i.e., greater than 1.0) when the delta G' value was about 50,000 Pa or more.

[0104] [000105] As further shown by Table 4, the delta G' values ​​obtained comparing the EX5-PL2 and EX5-PL4 polymer layers were about 42,000 Pa or less when the DMTA test temperature of the EX5-PL2 polymer layer was about 160°C or more (and the temperature of the EX5-PL4 polymer layer was about 170°C or 180°C). The mottle value of the intermediate layer formed with the EX5-PL2 and EX5-PL4 polymer layers was estimated to be 1.0 or less when the DMTA test temperature of the EX5-PL2 polymer layer was about 160°C or more. In contrast, the mottle value of the intermediate layer formed with the EX5-PL2 and EX5-PL4 polymer layers was estimated to be greater than 1.0 when the DMTA test temperature of the EX5-PL2 polymer layer was less than 160°C. Thus, the delta G' values ​​and corresponding estimated mottle values ​​in Table 4 indicate that interlayers formed with EX5-PL2 and EX5-PL4 polymer layers had favorable mottle values ​​when the delta G' value was about 42,000 Pa or less. In contrast, Table 4 indicates that interlayers formed with EX5-PL2 and EX5-PL4 polymer layers had unfavorable mottle values ​​when the delta G' value was about 60,000 Pa or more.

[0105] [000106] As further shown by Table 4, the delta G' values ​​obtained comparing the EX5-PL3 and EX5-PL4 polymer layers were about -3,300 Pa or less when the DMTA test temperature of the EX5-PL3 polymer layer was equal to about 200°C (and the temperature of the EX5-PL4 polymer layer was about 170°C or 180°C). The mottle value of the intermediate layer formed with the EX5-PL3 and EX5-PL4 polymer layers was estimated to be 1.0 or less when the DMTA test temperature of the EX5-PL3 polymer layer was about 200°C or more. Thus, the delta G' values ​​and corresponding estimated mottle values ​​in Table 4 indicate that the intermediate layer formed with the EX5-PL3 and EX5-PL4 polymer layers has a favorable mottle value when the delta G' value was about -3,300 Pa or less. As discussed above, a negative delta G' value indicates that the EX5-PL4 polymer layer (i.e., the core layer) is harder than the EX5-PL3 polymer layer (i.e., the skin layer). It is believed that the above-mentioned preferred mottle values ​​for the polymer interlayer comprising EX5-PL3 and EX5-PL4 polymer layers are due in part to the negative delta G' values ​​indicating that the EX5-PL3 polymer layer (skin layer) is softer than the EX5-PL4 polymer layer (i.e., core layer), thus reducing the ability of the EX5-PL3 polymer layer to impress its melt fracture into the EX5-PL4 polymer layer.

[0106] [000107] Although the present invention has been disclosed in conjunction with a description of certain embodiments, including what are currently believed to be preferred embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the 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.

[0107] [000108] Furthermore, it is understood that any range, value, or characteristic set forth for any single component of this disclosure may be used interchangeably with any range, value, or characteristic set forth 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.

[0108]

[0109] For example, polymer layers containing any of the ranges recited for residual hydroxyl content, as well as any of the ranges recited for plasticizer content, may be formed, where appropriate, forming many permutations that are within the scope of the present invention but too complex to list.

Claims

1. A polymer interlayer that is resistant to the formation of optical defects, comprising: a first polymer layer; and Second Polymer Layer Equipped with the first polymer layer is disposed on a first side of the second polymer layer; The non-embossed surface of the first side of the second polymer layer has an R of greater than 40 microns. Ｚ a surface roughness defined by a value the polymer interlayer has a mottle value of less than 1.0; Polymer interlayer.

2. A polymer interlayer that is resistant to the formation of optical defects, comprising: a first polymer layer; and Second Polymer Layer Equipped with the first polymer layer is disposed on a first side of the second polymer layer; The surface of the first side of the second polymer layer has an R of greater than 500 microns. ＳＭ a surface roughness defined by a value the polymer interlayer has a mottle value of less than 1.0; Polymer interlayer.

3. 3. The polymer interlayer of claim 1 or 2, wherein the surface roughness is a regular pattern surface roughness formed by melt fracture.

4. R Ｚ values ​​greater than 50 microns, greater than 60 microns, or greater than 70 microns, and / or R Ｚ 3. The polymeric interlayer of claim 1 or 2, wherein the value is 40 to 70 microns, 40 to 60 microns, 40 to 50 microns, 50 to 70 microns, 50 to 60 microns, or 60 to 70 microns.

5. The surface of the first side of the second polymer layer has an R of greater than 500 microns. ＳＭ The polymeric interlayer of claim 1 , comprising a surface roughness defined by a value.

6. R ＳＭ values ​​greater than 600 microns, greater than 700 microns, or greater than 800 microns, and / or R ＳＭ 3. The polymeric interlayer of claim 1 or 2, wherein the value is 500 to 800 microns, 500 to 700 microns, 500 to 600 microns, 600 to 800 microns, 600 to 700 microns, or 700 to 800 microns.

7. 3. The polymeric interlayer of claim 1 or 2, wherein the mottle value is less than 0.9, less than 0.8, less than 0.7, less than 0.6, or less than 0.5, and / or the mottle value is between 0.5 and 1.0, between 0.5 and 0.9, or between 0.5 and 0.

8.

8. 3. The polymer interlayer of claim 1 or 2, wherein the first polymer layer has a first storage modulus and the second polymer layer has a second storage modulus, and the difference between the first and second storage moduli is less than about 45,000 Pa, less than 40,000 Pa, less than 35,000 Pa, less than 30,000 Pa, less than 25,000 Pa, less than 20,000 Pa, less than 15,000 Pa, less than 10,000 Pa, or less than 5,000 Pa.

9. The polymer interlayer of claim 1 or 2, further comprising a third polymer layer, the first polymer layer being positioned between the second polymer layer and the third polymer layer.

10. The polymer interlayer of claim 1 or 2, wherein the thickness of the first polymer layer is substantially constant along the length of the polymer interlayer.

11. 3. The polymer interlayer of claim 1, wherein the thickness of the first polymer layer varies along the length of the polymer interlayer such that the first polymer layer has a wedge shape.

12. 1. A method for forming a polymer interlayer that is resistant to the formation of optical defects, comprising: (a) extruding a first polymer layer through a coextrusion die; (b) extruding a second polymer layer through a coextrusion die; (c) extruding a third polymer layer through a coextrusion die; Including, During the extrusion of steps (a), (b), and (c), the first polymer layer is positioned between the second polymer layer and the third polymer layer; during extrusion in step (a), the first polymer layer has a first storage modulus value, and during extrusion in step (b), the second polymer layer has a second storage modulus value, the difference between the first storage modulus value and the second storage modulus value being less than about 45,000 Pa; Upon extrusion of steps (a), (b), and (c), the polymer interlayer has a speckle value of less than 1.

0. method.

13. 13. The method of claim 12, wherein the difference between the first storage modulus value and the second storage modulus value is less than 40,000 Pa, less than 35,000 Pa, less than 30,000 Pa, less than 25,000 Pa, less than 20,000 Pa, less than 15,000 Pa, less than 10,000 Pa, or less than 5,000 Pa.

14. The surface roughness of the surface of the second polymer layer is R Ｚ is defined by the value of R Ｚ values ​​greater than 40 microns, greater than 50 microns, greater than 60 microns, or greater than 70 microns, and / or R Ｚ 13. The method of claim 12, wherein the value is 40-70 microns, 40-60 microns, 40-50 microns, 50-70 microns, 50-60 microns, or 60-70 microns.

15. The surface roughness of the surface of the second polymer layer is R ＳＭ is defined by the value of R ＳＭ values ​​greater than 500 microns, greater than 600 microns, greater than 700 microns, or greater than 800 microns, and / or R ＳＭ 13. The method of claim 12, wherein the value is 500-800 microns, 500-700 microns, 500-600 microns, 600-800 microns, 600-700 microns, or 700-800 microns.

16. 13. The method of claim 12, wherein the speckle value is less than 0.9, less than 0.8, less than 0.7, less than 0.6 or less than 0.5, and / or the speckle value is between 0.5 and 1.0, between 0.5 and 0.9, between 0.5 and 0.

8.

17. 13. The method of claim 12, wherein the extrusion of steps (a), (b), and (c) is performed simultaneously.

18. 20. The method of claim 17, wherein the extrusion of steps (a), (b), and (c) is carried out by coextrusion.

19. 19. A polymer interlayer that is resistant to the formation of optical defects, formed according to the method of any one of claims 12 to 18.

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