Polymer interlayer with low mottle and reduced frosting defects

Abstract

An optical defect-resistant polymer sandwich layer. The polymer sandwich layer includes 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 unembossed surface of the first side of the second polymer layer includes a texture greater than 40 micrometers made of R... Z The surface roughness is defined by a value. The polymer interlayer has a mottle value of less than 1.0.

Description

Technical Field

[0001] This invention relates to the field of polymer sandwich panels and multilayer panels comprising polymer sandwich panels. More specifically, this invention relates to the field of polymer sandwich panels comprising multiple thermoplastic polymer layers. Background Technology

[0002] Multilayer panels are typically composed of two substrates (e.g., but not limited to glass, polyester, polyacrylate, or polycarbonate) and one or more polymer interlayers sandwiched between them. Laminated multilayer glass panels are commonly used in architectural windows and in motor vehicle and aircraft windows, as well as in photovoltaic solar panels. The first two applications are often referred to as laminated safety glass. The primary function of the interlayer in laminated safety glass is to absorb the energy generated by impacts or forces applied to the glass, allowing the glass layers to remain bonded together even under pressure and in the event of breakage, thus preventing the glass from shattering into sharp fragments. Furthermore, the interlayer can impart significantly higher sound insulation levels, reduce UV and / or IR light transmission, and enhance the aesthetic appeal of the window. For example, laminated glass panels with desired acoustic properties have been produced, resulting in quieter interior spaces.

[0003] Furthermore, laminated glass panels are already used in vehicles equipped with head-up display (“HUD”) systems (also known as head-up systems), which project images from the instrument cluster or other important information onto the windshield at eye level for the driver. This display allows the driver to visually access dashboard information while maintaining focus on the upcoming driving path. Typically, HUD systems in cars or airplanes use the inner surface of the windshield to partially reflect the projected image. However, secondary reflections occur on the outer surface of the windshield, forming a weak secondary image or “ghosting.” Because these two reflected images are offset in position, ghosting is frequently observed, creating an undesirable viewing experience for the driver. When an image is projected onto a windshield with a uniform thickness, interference ghosting or reflection ghosting occurs due to the difference in position of the projected image as it reflects off the inner and outer surfaces of the glass.

[0004] One way to resolve these ghosting or reflections is to orient the inner and outer glass panels at an angle to each other. This aligns the reflected image to a single point, creating a single image. Typically, this is achieved by employing a wedge-shaped or “conical” interlayer that displaces the outer sheet relative to the inner sheet, including at least one region of uneven thickness. Most conventional conical interlayers include a constant wedge angle across the entire HUD area, although some interlayers incorporating multiple wedge angles across the HUD area have recently been developed.

[0005] To achieve the desired properties and performance characteristics of glass panels, the use of multilayer or multi-layer sandwich structures has become common practice. As used herein, the terms "multilayer" and "multiple layers" refer to sandwich structures with more than one layer, and the terms multilayer and multiple layers are used interchangeably. Multilayer sandwich structures typically contain at least one soft layer and at least one hard layer. As mentioned above, sandwich structures with a soft "core" layer sandwiched between two more rigid or harder "skin" layers have been designed to have sound insulation properties for glass panels. Sandwich structures with the opposite construction, i.e., a hard layer sandwiched between two softer layers, have been found to improve the impact resistance of glass panels and can also be designed for sound insulation. In any case, the soft "core" layer is generally referred to as the acoustic layer (because soft layers advantageously reduce sound transmission), while the hard "skin" layer is referred to as the conventional layer or non-acoustic layer.

[0006] The layers of a sandwich structure are typically produced by mixing a polymeric resin, such as poly(vinyl butyral), with one or more plasticizers and then melting the mixture into a sheet using any suitable process or method known to those skilled in the art, including but not limited to extrusion, wherein the layers are bonded by methods such as co-extrusion and lamination. In a three-layer sandwich structure, the core layer may include more plasticizer than the skin layer, making the core layer softer than the relatively rigid skin layer. Other additional components may optionally be added for various other purposes. After the sandwich sheet is formed, it is typically collected and rolled for transport and storage, and subsequently used in multilayer glass panels as described below.

[0007] Multilayer glass panels are typically manufactured by combining with interlayers, and a simplified description of this process is provided below. First, a multilayer interlayer can be co-extruded using a multi-manifold co-extrusion apparatus. This apparatus operates by simultaneously extruding polymer melt from each manifold into the extrusion opening. The properties of the layer can be varied by adjusting the properties of the die lip at the extrusion opening (e.g., temperature and / or opening size). Once formed, an interlayer sheet is placed between two glass substrates, and any excess interlayer is trimmed from the edges to form the assembly. It is not uncommon to place multiple polymer interlayer sheets or a single polymer interlayer sheet with multiple layers (or a combination of both) between two glass substrates to form a multilayer glass panel with multiple polymer interlayers. Air is then removed from the assembly using suitable processes or methods known to those skilled in the art; for example, by rollers, vacuum bags, or another degassing device. Additionally, the interlayer is partially pressed onto the substrates using any method known to those skilled in the art. In this final step, to form the final single structure, this pre-bonding is made more durable by a high-temperature and high-pressure lamination process or any other method known to those skilled in the art, such as, but not limited to, high-pressure steam.

[0008] Multilayer laminates, such as three-layer laminates with a soft core and two harder skin layers, are known to provide beneficial acoustic damping properties. However, glass panels containing these multilayer acoustic laminates can develop defects commonly known as ice flowers (also called snowflakes) under extreme conditions, which begin to appear when there is excessive residual trapped air in the panel and stress within the glass. Specifically, during the manufacturing process of laminated multilayer glass panel structures, air and other gases are often trapped in the gaps between the substrate and the laminate, or in the gaps between the individual layers of the multilayer laminate, as these layers are stacked together to form the multilayer laminate. During the manufacturing process of glass windows or panels, this trapped air is typically removed by degassing the structure using vacuum or rollers. However, these techniques are not always effective in removing all trapped air from the gaps between the substrates. These cavitations are particularly noticeable in mismatched glass (e.g., tempered glass, heat-strengthened glass, and thick annealed glass) and windshields, where the curvature of the glass often results in air gaps. These air gaps in windshields are commonly referred to as "bending gaps." Additionally, when bending gaps exist during high-pressure steam processes, the heating and pressurization of the glass to fit the interlayer and narrow the gaps results in high stress in the glass within the initial gap region.

[0009] As mentioned above, degassing techniques are not always effective at removing all air from glass panel assemblies. As a result, residual air remains between the glass and the interlayer. During high-pressure steam processing, under heat and pressure, the residual air dissolves into the interlayer, primarily in the skin layer. The residual air located in the skin layer can move to the core layer or the skin-core interface, and it eventually distributes between the skin and core layers to reach an equilibrium. When a large amount of residual air (e.g., excessive residual air) is present in the interlayer, bubbles can nucleate, especially at high temperatures, because the interlayer softens and becomes less resistant to nucleation.

[0010] In multilayer acoustic laminates with a soft core sandwiched between two harder layers, where the soft layer is confined between the two harder layers, bubbles typically form first within the soft core because nucleation favors less viscous media. In warm to hot climates, such as during the summer, the temperature of the glass in laminated glass installed in buildings and vehicles can rise to 50°C to 100°C. At these elevated temperatures, forces generated by stress in the glass panels or windshield, perpendicular to the plane of the glass panel or windshield and in opposite directions, exert pressure on the glass, pulling the glass panels away from each other in an attempt to restore them to their initial state. This stress reduces the resistance to air nucleation and expansion, allowing bubbles to grow within the core layer.

[0011] At high temperatures (e.g., 50°C to 100°C), stress from bending gaps or glass mismatch causes bubbles to expand within the core layer in random radial directions along paths of least resistance. As the defects continue to expand radially, branching and dendritic features form, producing the undesirable optical appearance of frosting. Additionally, frosting formation within the core layer often leads to layer separation, reducing the structural integrity of the plate.

[0012] An additional problem in the manufacture of multilayer laminated glass panels is the presence of mottle in the final monolithic structure. The term "mottle" refers to an unsightly visual defect in the final monolithic structure, namely the appearance of uneven spots. In other words, mottle is a measure of the graininess or texture of the surface area of ​​the inner polymer interlayers or multiple polymer interlayers. It is a form of optical distortion. Mottle is believed to be caused by small-scale surface variations at the interfaces between the layers of a laminate with different refractive indices. The refractive index of a layer is a measure of the speed at which light passes through that material. For any multilayer interlayer, mottle is theoretically possible, provided there is a sufficiently large difference in refractive index between the layers and a certain degree of interfacial variation exists. The presence of mottle in the final monolithic structure of multilayer laminated glass panels can be problematic because a certain level of optical quality is required in many (if not most) end-use commercial applications of multilayer laminated glass panels, such as automotive, aerospace, and architectural applications.

[0013] In view of the above, there is a need in the art to develop a multilayer sandwich that can resist the formation of these optical defects (i.e., ice flowers and mottles) without reducing other optical, mechanical, and acoustic properties of conventional multilayer sandwiches. More specifically, there is a need in the art to develop a multilayer sandwich having at least one soft core layer and one hard skin layer, which resists air nucleation and expansion to form ice flowers, while also having an acceptable mottle value. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a glass laminated panel, which includes a pair of glass plates opposite a polymer interlayer, wherein the polymer interlayer comprises three layers having a pair of skin layers opposite a core layer;

[0015] Figure 2 This is another schematic diagram of a glass laminated panel, which includes a pair of glass plates opposite a polymer interlayer, wherein the polymer interlayer has a wedge shape;

[0016] Figure 3 It is a schematic cross-section of a co-extrusion die having an opening defined by the die and / or a pair of die lips, wherein the die is configured to co-extrude a multilayer polymer sandwich.

[0017] Figure 4It is an enlarged view of a polymer interlayer with a regular surface rough pattern, which takes the form of a tire track pattern and is formed on the surface of the polymer interlayer by melt fracture;

[0018] Figure 5 It is an enlarged view of a polymer interlayer with a random surface pattern formed on the surface of the polymer interlayer;

[0019] Figure 6 These are photographs of multiple stacked three-layer sandwich structures of the present invention formed according to embodiments of the present invention, wherein the three-layer sandwich structures of the present invention show no ice crystal formation; and

[0020] Figure 7 The photograph shows multiple stacked contrasting three-layer sandwiches formed according to existing technology, in which the contrasting three-layer sandwiches show the presence of ice flower formation. Summary of the Invention

[0021] One aspect of the present invention relates to a polymer sandwich layer resistant to the formation of optical defects. The polymer sandwich layer includes a first polymer layer and a second polymer layer. The first polymer layer is disposed on a first side surface of the second polymer layer. The unembossed surface of the first side surface of the second polymer layer comprises a texture greater than 40 micrometers formed by R... Z The surface roughness is defined by a value. The polymer interlayer has a mottle value of less than 1.0.

[0022] Another aspect of the invention relates to a polymer sandwich layer that resists the formation of optical defects. The polymer sandwich layer includes a first polymer layer and a second polymer layer. The first polymer layer is disposed on a first side surface of the second polymer layer. The surface of the first side surface of the second polymer layer includes a surface texture greater than 500 micrometers made of R... SM The surface roughness is defined by a value. The polymer interlayer has a mottle value of less than 1.0.

[0023] Another aspect of the invention relates to an additional method for preparing a polymer interlayer resistant to the formation of optical defects. One step of the method includes extruding a first polymer layer through a co-extrusion die. An additional step includes extruding a second polymer layer through a co-extrusion die. A further step includes extruding a third polymer layer through a co-extrusion die. During the extrusion step, the first polymer layer is located between the second and third polymer layers. 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 and second storage modulus values ​​is less than about 45,000 Pa. After extruding the first, second, and third polymer layers, the polymer interlayer has a mottle value of less than 1.0.

[0024] Another aspect of the invention relates to a polymer sandwich that resists the formation of optical defects using a method comprising the following steps: One step includes extruding a first polymer layer through a co-extrusion die. An additional step includes extruding a second polymer layer through a co-extrusion die. A further step includes extruding a third polymer layer through a co-extrusion die. During the extrusion step, the first polymer layer is located between the second and third polymer layers. 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 and second storage modulus values ​​is less than about 45,000 Pa. After extruding the first, second, and third polymer layers, the polymer sandwich has a mottle value of less than 1.0. Detailed Implementation

[0025] Embodiments of the present invention relate to multilayer panels and methods of manufacturing multilayer panels. Typically, a multilayer panel consists of two glass or other suitable substrates, with one or more polymer interlayer sheets sandwiched between them. Multilayer panels are generally manufactured by placing at least one polymer interlayer sheet between two substrates to create an assembly. Figure 1 A multilayer panel 10 is shown, comprising a pair of glass sheets 12 sandwiched therebetween. The multilayer sandwich is configured as a three-layer sandwich having three separate polymer sandwich sheets, including a soft core layer 14 and two relatively rigid skin layers 16 positioned on either side of the core layer 14.

[0026] In some embodiments, the interlayer (e.g., core layer 14 and skin layer 16) will have a generally constant or uniform thickness with respect to the interlayer length. However, in alternative embodiments, such as Figure 2 As shown, the interlayer may have at least one region of non-uniform thickness. For example, the interlayer consisting of core layer 14 and skin layer 16 may be wedge-shaped, such that the thickness of the interlayer varies with the length of the interlayer (e.g., linearly or non-linearly). In some such embodiments, the thickness of the interlayer may vary due to variations in the thickness of core layer 14 (i.e., skin layer 16 has a generally constant thickness). Alternatively, the thickness of the interlayer may vary due to variations in the thickness of skin layer 16 (i.e., core layer 14 has a generally constant thickness). In another alternative, the thickness of the interlayer may vary due to variations in the thickness of both core layer 14 and skin layer 16.

[0027] To facilitate a more comprehensive understanding of the mezzanine and multilayer panels disclosed herein, the meanings of certain terms as used herein will be defined. These definitions should not be construed as limiting the terms, as they are understood by those skilled in the art, but are merely intended to provide a better understanding of how certain terms are used herein.

[0028] As used herein, the terms “polymer sandwich sheet,” “sandwich,” “polymer layer,” and “polymer melt sheet” can refer to a single-layer sheet or a multilayer sandwich. As the name suggests, a “single-layer sheet” is a single polymer layer extruded as a single layer. On the other hand, a multilayer sandwich can include multiple layers, including individually extruded layers, co-extruded layers, or any combination of individually and co-extruded layers. Thus, a multilayer sandwich can include, for example: two or more single-layer sheets combined together (“multilayer sheets”); two or more layers co-extruded together (“co-extruded sheets”); two or more co-extruded sheets combined together; a combination of at least one single-layer sheet and at least one co-extruded sheet; and a combination of at least one multilayer sheet and at least one co-extruded sheet. In various embodiments of the invention, a multilayer sandwich includes at least two polymer layers (e.g., single-layer or co-extruded multilayers) arranged in direct contact with each other, wherein each layer comprises a polymer resin. As used herein, the term “resin” refers to polymer components (e.g., PVB) removed from the process, such as those discussed more fully below. Typically, plasticizers, such as those discussed more fully below, are added to the resin to produce a plasticized polymer. Additionally, the resin may have other components besides the polymer and plasticizer, as discussed further below.

[0029] It should also be noted that while polyvinyl butyral (“PVB”) interlayers are frequently discussed in detail in this application as polymeric resins for polymeric interlayers, it should be understood that other thermoplastic interlayers besides PVB interlayers may be used. Contemplated polymers include, but are not limited to, polyurethanes, polyvinyl chloride, poly(vinyl acetate), and combinations thereof. These polymers may be used alone or in combination with other polymers. Therefore, it should be understood that when the scope, values, and / or methods for PVB interlayers are given in this application (e.g., plasticizer component percentage, thickness, and characterization of reinforcing additives), these scopes, values, and / or methods are applicable to other polymers and polymer blends disclosed herein, or may be modified as known to those skilled in the art to suit different materials.

[0030] As used herein, the term "molecular weight" refers to weight-average molecular weight (Mw). The molecular weight of PVB resins can range from 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, one or more polymer layers of the interlayer preferably have a unimodal Mw distribution. For example, the skin layer may preferably be formed of a PVB resin comprising a unimodal Mw distribution, as such resins may contribute to the formation of regular melt portion patterns, as will be discussed below.

[0031] PVB resins can be prepared by known aqueous or solvent acetalization methods, which involve reacting polyvinyl alcohol (“PVOH”) with butyraldehyde in the presence of an acid catalyst, followed by separation, stabilization, and drying of the resin. Such acetalization methods are disclosed, for example, in U.S. Patent Nos. 2,282,057 and 2,282,026 and Wade, B. 2016, “Vinyl Alcohol Acetal Polymers”. Polymer Science With the encyclopedia of technology , 1-22 (John Wiley & Sons, Inc.) (Wade, B. (2016), "Vinyl Acetal Polymers", Encyclopedia of Polymer Science and Technology ,pp.1-22 (John Wiley & Sons, Inc.), all of which are publicly available and incorporated herein by reference.

[0032] Although generally referred to herein as "poly(vinyl acetal)" or "poly(vinyl butyral)," the resins described herein may include any suitable aldehyde residues, including but not limited to isobutyral, as previously discussed. In some embodiments, one or more poly(vinyl acetal) resins may include at least one C1-C14 resin. 10 An aldehyde or a residue of at least one C4-C8 aldehyde. Suitable examples of C4-C8 aldehydes may include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylpentanaldehyde, n-hexanaldehyde, 2-ethylhexanaldehyde, n-octanaldehyde, and combinations thereof.

[0033] In many embodiments, a plasticizer is added to a polymer resin to form a polymer layer or interlayer. Plasticizers are typically added to the polymer resin to increase the flexibility and durability of the resulting polymer interlayer. The plasticizer works by embedding itself between polymer chains, spacing them apart (increasing "free volume"), and thus significantly lowering the glass transition temperature (Tg) of the polymer resin. g This makes the material softer. In this respect, the amount of plasticizer in the interlayer can be adjusted to affect the glass transition temperature T. g Glass transition temperature T g This is the temperature at which the interlayer transitions from a glassy state to a rubbery state. Generally, a higher plasticizer loading results in a lower Tg. g .

[0034] The anticipated plasticizers include, but are not limited to, esters of polybasic acids, polyols, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate) (referred to as "3-GEH"), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, cyclohexyl adipate, heptyl adipate and nonyl adipate mixtures, diisononyl adipate, heptyl nonyl adipate, dibutyl sebacate, and polymeric plasticizers such as oil-modified sebacate alkyd resins and mixtures of phosphate esters and adipates, 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"), bis(butoxyethyl) adipate and bis(2-(2-butoxyethoxy)ethyl) adipate, dioctyl sebacate, nonylphenyl tetraethylene glycol and mixtures thereof.

[0035] Other suitable plasticizers may include blends of two or more different plasticizers, including but not limited to those described above. Other suitable plasticizers or blends of plasticizers may be formed from aromatic groups, such as polyadipate, epoxides, phthalates, terephthalates, benzoates, toluene, hexabenzoate, and other specialty plasticizers. Other examples include, but are not limited to, dipropylene glycol benzoate, tripropylene glycol benzoate, polypropylene glycol benzoate, isodecanyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, propylene glycol benzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol isobutyrate benzoate, 1,3-butanediol dibenzoate, diethylene glycol di-o-methylbenzoate, triethylene glycol di-o-methylbenzoate, dipropylene glycol di-o-methylbenzoate, 1,2-octyl benzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bisphenol A bis(2-ethylhexanoate), ethoxylated nonylphenol, and mixtures thereof. In some embodiments, the plasticizer may be selected from dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, and combinations thereof.

[0036] Typically, the plasticizer content of the polymer interlayer in this application is measured in parts per hundred parts of resin (“phr”), expressed as a weight-to-weight ratio. For example, if 30 grams of plasticizer are added to 100 grams of polymer resin, the resulting plasticized polymer will have a plasticizer content of 30 phr. When the plasticizer content of a polymer layer is given in this application, the plasticizer content of a particular layer is determined with reference to the phr of the plasticizer in the melt used to prepare that particular layer. In some embodiments, the high-rigidity interlayer comprises layers with plasticizer contents of less than about 35 phr and less than about 30 phr.

[0037] According to some embodiments of the present invention, the total plasticizer content of one or more polymer layers described herein may be 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, or at least about 75 phr. In some embodiments, the polymer layer may further include one or more plasticizers not exceeding about 100 phr, not exceeding about 85 phr, not exceeding 80 phr, not exceeding about 75 phr, not exceeding about 70 phr, not exceeding about 65 phr, not exceeding about 60 phr, not exceeding about 55 phr, not exceeding about 50 phr, not exceeding about 45 phr, not exceeding about 40 phr, not exceeding about 38 phr, not exceeding about 35 phr, or not exceeding about 30 phr. 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 about 70 phr.

[0038] When the interlayer comprises multiple layers, two or more polymer layers within the interlayer may have substantially the same plasticizer content and / or at least one polymer layer may have a different plasticizer content than one or more other polymer layers. When the interlayer comprises two or more polymer layers with different plasticizer contents, these two layers may be adjacent to each other. In some embodiments, the difference in plasticizer content between adjacent polymer layers may be at least about 1, at least about 2, at least about 5, at least about 7, at least about 10, at least about 20, at least about 30, at least about 35 phr and / or no more than about 80, no more than about 55, no more than about 50, or no more than about 45 phr, or in the range of about 1 to about 60 phr, about 10 to about 50 phr, or about 30 to 45 phr. When three or more layers are present in the interlayer, at least two polymer layers of the interlayer may have similar plasticizer contents falling within, for example, 10 phr, 5 phr, 2 phr, or 1 phr, while at least two polymer layers may have plasticizer contents that differ from each other according to the above ranges.

[0039] In some embodiments, one or more polymer layers or interlayers described herein may comprise blends of two or more plasticizers, including, for example, two or more plasticizers listed above. When a polymer layer contains two or more plasticizers, the difference between the total plasticizer content of the polymer layer and the total plasticizer content between adjacent polymer layers may fall within one or more of the ranges described above. When the interlayer is a multilayer interlayer, one or more polymer layers may comprise two or more plasticizers. In some embodiments, when the interlayer is a multilayer interlayer, at least one of the polymer layers comprising the plasticizer blend may have a glass transition temperature higher than that of a conventional plasticized polymer layer. In some cases, this can provide additional stiffness to the layer, which can be used as, for example, an outer “skin” layer in a multilayer interlayer.

[0040] In addition to plasticizers, it is also considered that adhesive control agents (“ACA”) can be added to polymer resins to form polymer interlayers. ACA typically acts to modify the adhesiveness of the interlayer. The intended ACAs include, but are not limited to, those disclosed in U.S. Patent 5,728,472, residual sodium acetate, potassium acetate, and / or magnesium bis(2-ethylbutyrate).

[0041] Other additives may be introduced into the interlayer to enhance its performance in the final product and impart certain additional properties to the interlayer. These additives include, but are not limited to, dyes, pigments, stabilizers (e.g., UV stabilizers), antioxidants, anti-caking 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-enhancing additives, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, UV stabilizers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives, and fillers, as well as other additives known to those skilled in the art.

[0042] One parameter used to describe the polymer resin composition of the polymer interlayer 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. For example, PVB can be manufactured by hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol), and then reacting the poly(vinyl alcohol) with butyraldehyde to form PVB. During the hydrolysis of poly(vinyl acetate), not all acetate side groups are typically converted to hydroxyl groups. Furthermore, the reaction with butyraldehyde typically does not result in all hydroxyl groups being converted to acetal groups. Therefore, in any finished PVB, there will typically be residual acetate groups (as vinyl acetate groups) and residual hydroxyl groups (as vinyl hydroxyl groups) as side groups on the polymer chain. Generally, the residual hydroxyl content of the polymer can be adjusted by controlling the reaction time, reactant concentration, and other variables in the polymer manufacturing process. When used as a parameter herein, the residual hydroxyl content is measured as a weight percentage according to ASTM D-1396.

[0043] In various embodiments, the poly(vinyl butyral) resin comprises about 8 wt% to about 35 wt% (wt%) of residual hydroxyl groups calculated in PVOH, about 13 wt% to about 30 wt% of residual hydroxyl groups calculated in PVOH, about 8 wt% to about 22 wt% of residual hydroxyl groups calculated in PVOH, or about 15 wt% to about 22 wt% of residual hydroxyl groups calculated in PVOH; for some of the high-rigidity interlayers disclosed herein, for one or more layers, the poly(vinyl butyral) resin comprises more than about 19 wt% of residual hydroxyl groups calculated in PVOH, more than about 20 wt% of residual hydroxyl groups calculated in PVOH, more than about 20.4 wt% of residual hydroxyl groups calculated in PVOH, and more than about 21 wt% of residual hydroxyl groups calculated in PVOH.

[0044] In some embodiments, the poly(vinyl butyral) resin used in at least one polymer layer of the interlayer may comprise poly(vinyl butyral) resin having the following residual hydroxyl content: 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 not more than about 30 wt%, not more than about 29 wt%, not more than about 28 wt%, not more than about 27 wt%, not more than about 26 wt%, not more than about 25 wt%, not more than about 24 wt%, not more than about 23 wt%, or not more than about 22 wt%, as measured above.

[0045] Additionally, one or more other polymer layers in the interlayer described herein may comprise another poly(vinyl butyral) resin with a lower residual hydroxyl content. For example, in some embodiments, at least one polymer layer of the interlayer 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 not exceeding about 16 wt%, not exceeding about 15 wt%, not exceeding about 14 wt%, not exceeding about 13.5 wt%, not exceeding about 13 wt%, not exceeding about 12 wt%, or not exceeding about 11.5 wt%, as measured above.

[0046] When the interlayer comprises two or more polymer layers, these layers may comprise poly(vinyl butyral) resins with 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 comprise poly(vinyl butyral) resins with 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 percentage difference” and “…the difference between them is at least… wt%” refer to the difference between two given weight percentages, calculated by subtracting one value from the other. For example, a poly(vinyl butyral) resin with a residual hydroxyl content of 12 wt% has a residual hydroxyl content that differs from that of a poly(vinyl butyral) resin with a residual hydroxyl content of 14 wt% by 2 wt% (14 wt% - 12 wt% = 2 wt%). As used herein, the term “different” may refer to a value higher or lower than the other value. Unless otherwise stated, all terms "difference" in this document refer to the numerical value of the difference, not the specific sign of the value resulting from the order of the subtraction. Therefore, unless otherwise stated, all terms "difference" in this document refer to the absolute value of the difference between two numerical values.

[0047] When two or more layers contain poly(vinyl butyral) resins with 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%, as measured as described above.

[0048] The resin may also contain less than 35 wt%, 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% of residual ester groups calculated as polyethylene ester (e.g., acetate), with the balance being acetal, preferably butyraldehyde acetal, but optionally including small amounts of other acetal groups, such as 2-ethylhexanal (see, for example, U.S. Patent No. 5,137,954, the entire disclosure of which is incorporated herein by reference). The residual acetate content of the resin may also be determined according to ASTM D-1396.

[0049] According to some embodiments, the difference between the glass transition temperatures of two polymer layers (typically adjacent polymer layers within a sandwich structure) can be at least about 5°C, at least about 10°C, at least about 15°C, at least about 20°C, at least about 25°C, at least about 30°C, at least about 35°C, at least about 40°C, or at least about 45°C. In other embodiments, the glass transition temperatures of two or more polymer layers can be within about 5°C, about 3°C, about 2°C, or about 1°C of each other. Typically, the lower glass transition temperature layer has a lower stiffness than one or more higher glass transition temperature layers in the sandwich structure and can be located between the higher glass transition temperature polymer layers in the final sandwich structure.

[0050] For example, in some embodiments of this application, the increased acoustic attenuation properties of the soft layer are combined with the mechanical strength of the hard / rigid layers to create a multilayer sandwich. In these embodiments, the intermediate soft layer is sandwiched between two hard / rigid outer layers. This (hard) / / (soft) / / (hard) configuration produces a multilayer sandwich that is easy to handle and can be used in conventional lamination methods and can be constructed with relatively thin and light layers. The soft layer is typically characterized by a lower residual hydroxyl content (e.g., less than or equal to 16 wt%, less than or equal to 15 wt%, or less than or equal to 12 wt%, or any of the above ranges), a higher plasticizer content (e.g., greater than or equal to about 48 phr, or greater than or equal to about 70 phr, or any of the above ranges), and / or a lower glass transition temperature (e.g., less than 30°C, or less than 10°C, or any of the above ranges).

[0051] The polymer sandwich sheets described herein are contemplated to be produced by any suitable method known to those skilled in the art for producing polymer sandwich sheets suitable for use in multilayer panels (e.g., glass laminates). For example, the polymer sandwich sheets are contemplated to be formed by solution casting, compression molding, injection molding, melt extrusion, meltblowing, or any other process known to those skilled in the art for producing and manufacturing polymer sandwich sheets. Furthermore, in embodiments using multiple polymer sandwiches, these multiple polymer sandwiches are contemplated to be formed by co-extrusion, blown film, dip coating, solution coating, knife coating, paddle coating, air knife coating, printing, powder coating, spraying, or other methods known to those skilled in the art. While all methods of producing polymer sandwich sheets known to those skilled in the art are considered possible methods for producing the polymer sandwich sheets described herein, this application focuses on polymer sandwich sheets produced by extrusion and / or co-extrusion processes. The final multilayer glass panel laminates of this disclosure can be formed using methods known in the art.

[0052] During the extrusion process, thermoplastic resins and plasticizers, including any of the resins and plasticizers described above, are typically premixed and fed into the extruder unit. Additives such as colorants and UV inhibitors (in liquid, powder, or granular form) may be used and may be incorporated into the thermoplastic resin or plasticizer before it reaches the extruder unit. These additives are introduced into the thermoplastic polymer resin and, consequently, into the resulting polymer sandwich sheet to enhance certain properties of the polymer sandwich sheet and its performance in the final multilayer glass panel product.

[0053] In an extruder unit, the granules of thermoplastic raw material and plasticizers, including any of the resins, plasticizers, and other additives described above, are further mixed and melted to produce a melt with generally uniform temperature and composition. Once the melt reaches the end of the extruder unit, it is forced into the extruder die. The extruder die is a component of the extruder unit that gives the final polymer sandwich sheet product its profile. The die typically has an opening defined by a lip, which is substantially larger in one dimension than in the vertical dimension. Generally, the die is designed so that the melt flows uniformly from the cylindrical profile exiting the die and into the end profile shape of the product. A variety of shapes can be given to the final polymer sandwich sheet by the die, as long as a continuous profile exists. Generally, in its most basic sense, extrusion is a process used to produce an object with a fixed cross-sectional profile. This is achieved by pushing or pulling material through a die having the desired cross-section of the final product.

[0054] In some embodiments, a co-extrusion process can be used. Co-extrusion is a method of simultaneously extruding multiple layers of polymer materials. Typically, this type of extrusion utilizes two or more extruders to melt and deliver different thermoplastic melts of varying viscosities or other properties through co-extrusion dies in a stable volumetric throughput to the desired final form. For example, the multilayer sandwich structure of the present invention (e.g., in the form of a three-layer sandwich structure) can preferably be co-extruded using a multi-manifold co-extrusion apparatus comprising a first die manifold, a second die manifold, and a third die manifold. Figure 3 As shown, the co-extrusion apparatus can be operated by simultaneously extruding polymer melt from each manifold, converging three extruded melt flows into a single opening 20 of the die 22 of the co-extrusion apparatus. The opening 20 can be at least partially defined as a space or gap between a first portion 24 (e.g., upper portion) and a second portion 26 (e.g., lower portion) of the die 22. In some embodiments, the opening 20 can also be defined by a pair of spaced-apart die lips (i.e., a first die lip 28 and a second die lip 30) located at the outlet of the opening 20. Thus, the co-extrusion apparatus can be configured to extrude a three-layer sandwich comprising a composite material of three separate polymer layers (e.g., a core layer 14 sandwiched between a pair of skin layers 16). Specifically, the composite three-layer sandwich can be co-extruded through opening 20, wherein a first skin layer 16 is positioned adjacent to a first portion 24 (e.g., upper) and / or a first die lip 28 (e.g., upper die lip) of die 22, a second skin layer 16 is positioned adjacent to a second portion 26 (e.g., lower) and / or a second die lip 30 (e.g., lower die lip) of die 22, and a core layer 14 is co-extruded through die 22 sandwiched between the two skin layers 16. Therefore, during the co-extrusion process, the core layer 14 typically does not contact the first portion 24 or the second portion 26 and / or the first die lip 28 or the second die lip 30 of die 22.

[0055] The thickness of the multiple polymer layers exiting the extrusion die 22 during co-extrusion can typically be controlled by adjusting the relative speed of the melt through the extrusion die 22 and / or by adjusting the size of the die opening 20. In some embodiments, the position of one or both of the die lips 28, 30 can be moved relative to each other to increase or decrease the size of the opening 20. According to some embodiments, the total thickness of the multilayer sandwich can be at least about 13 mils, at least about 20 mils, at least about 25 mils, at least about 27 mils, at least about 30 mils, at least about 31 mils and / or not more than about 75 mils, not more than about 70 mils, not more than about 65 mils, not more than about 60 mils, or it can be in the range of about 13 to about 75 mils, about 25 to about 70 mils, or about 30 to 60 mils. When the interlayer comprises two or more polymer layers, the thickness of each layer may be at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10 mils and / or no more than about 50, no more than about 40, no more than about 30, no more than about 20, no more than about 17, no more than about 15, no more than about 13, no more than about 12, no more than about 10, no more than about 9 mils. In some embodiments, each layer may have substantially the same thickness, while in other embodiments, one or more layers may have a different thickness than one or more other layers within the interlayer.

[0056] In some embodiments, the interlayer comprises at least three polymer layers, and one or more inner layers may be relatively thin compared to the other outer layers. For example, in some embodiments where the multilayer interlayer is a three-layer interlayer, the innermost layer may have a thickness of no more than about 12, no more than about 10, no more than about 9, no more than about 8, no more than about 7, no more than about 6, or no more than about 5 mils, or it may have a thickness of about 2 to about 12 mils, about 3 to about 10 mils, or about 4 to about 9 mils. In the same or other embodiments, the thickness of each of the outer layers may be at least about 4, at least about 5, at least about 6, at least about 7 mils and / or no more than about 15, no more than about 13, no more than about 12, no more than about 10, no more than about 9, or no more than about 8 mils, or may be in the range of about 2 to about 15, about 3 to about 13, or about 4 to about 10 mils. When the interlayer comprises two outer layers, these layers may have a thickness of at least about 9, at least about 13, at least about 15, at least about 16, at least about 18, at least about 20, at least about 23, at least about 25, at least about 26, at least about 28, or at least about 30 mils, and / or no more than about 73, no more than about 60, no more than about 50, no more than about 45, no more than about 40, or no more than about 35 mils, or a combination of thicknesses within the range of about 9 to about 70 mils, about 13 to about 40 mils, or about 25 to about 35 mils.

[0057] According to some embodiments, the thickness ratio of one of the outer layers to one of the inner layers in a multilayer sandwich can 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 sandwich is a three-layer sandwich having an inner core layer disposed between one pair of outer skin layers, the thickness ratio of one of the skin layers to the core layer can fall within one or more of the above ranges. In some embodiments, the combined thickness ratio of the outer layer to the inner layer may be at least about 2.25:1, at least about 2.4:1, at least about 2.5:1, at least about 2.8:1, at least about 3:1, at least about 3.5:1, at least about 4:1, at least about 4.5:1, at least about 5:1, at least about 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.

[0058] The multilayer sandwich described herein may include a generally flat sandwich having substantially the same thickness along the length or longest dimension and / or width or second longest dimension of a sheet. However, in some embodiments, the multilayer sandwich of the present invention may be a conical or wedge-shaped sandwich comprising at least one conical region having a wedge-shaped profile. The conical sandwich has a varying thickness profile along at least a portion of the length and / or width of the sheet, such that, for example, at least one edge of the sandwich has a thickness greater than that of another edge. When the sandwich is a conical sandwich, at least one, at least two, at least three or more individual resin layers may comprise at least one conical region. Conical sandwiches may be particularly useful for head-up display (HUD) panels, for example, in automotive and aircraft applications.

[0059] In some embodiments, surface roughness can be created on one or more layers of the interlayer. Typically, this surface roughness can be imparted via melt fracture or via embossing. Melt fracture is a process of creating roughness on the surface of a polymer interlayer by controlling the composition of the melt, the temperature of the die lip, and / or by controlling the cooling rate and method of the extruded interlayer, which may, for example, be immersed in a cooling bath shortly after extrusion. (See, for example, U.S. Patent Nos. 5,595,818 and 4,654,179, the entire disclosure of which is incorporated herein by reference). In some embodiments, it may be preferable that one or more layers of the interlayer are formed with a “regular melt fracture pattern.” As used herein, the term “regular melt fracture pattern” or “regular pattern” is used to refer to a pattern that is generally repeatable or reproducible. Examples of regular patterns include, but are not limited to, parallel channels, zigzag patterns, geometries such as squares, pyramids, etc., or combinations of patterns. Figure 4The diagram shows regular melt fracture patterns formed on a polymer layer, often referred to as "tire track" patterns. In contrast, random patterns refer to patterns that do not have regular or repeating patterns across the entire surface. Figure 5 The random pattern formed on the polymer layer is shown.

[0060] In the case where three separate layers are laminated together to form a three-layer sandwich, any surface of these three layers can be formed with a regularly patterned surface roughness by melt fracture before or during the assembly of these layers. In various embodiments, one or both of the surfaces of these individual polymer layers forming the outer skin layer 16 of the three-layer sandwich can be formed with a regularly patterned surface roughness by melt fracture.

[0061] According to embodiments of the invention, controlled melt fracture is used to modify one or both surfaces of the outer polymer layer to produce a polymer layer with a desired regular pattern surface roughness, which may be determined by "R". Z "or "R sm Value measurement. R Z It is a measure of the surface morphology of the polymer layer and an indicator of the deviation of the surface from a plane (e.g., an imaginary plane presented by the flat surface of the polymer layer). R sm It is a measure of the distance between peaks in the surface morphology of the polymer layer. These two measurements will be described in detail below. As used herein, "imparted by melt fracture" refers to the generation of polymers through melt fracture phenomena during extrusion, via R... Z and R sm Surface texture measured.

[0062] For typical surface patterns, surface roughness, or the height of a specific peak on a roughened surface from an imaginary plane on the surface of the planarized polymer layer, it is the R of the surface. Z Value. As described in this application, the surface roughness or R value of the polymer sandwich sheet. Z The standard will be expressed in micrometers (μm), based on the International Organization for Standardization's DIN ES ISO-4287 and the American Society of Mechanical Engineers' A... sm E B46.1 is measured using a 10-point average roughness scale. Typically, under these scales, R... Z The individual roughness depth R calculated as a continuous sampling length Zi The arithmetic mean of (i.e., the vertical distance between the highest peak and the deepest valley within the sampling length):

[0063]

[0064] Another surface parameter described and measured is the average spacing R. sm Average spacing R smThe average width between peaks on the surface of the polymer sandwich sheet is described, expressed in micrometers (μm). Typically, R... sm and R Z The values ​​can be used to measure the surface morphology of embossed and unembossed polymer sandwich sheets. However, the surface roughness imparted to the surface of the polymer layer as described herein is typically imparted by non-embossing methods, such as melt fracture.

[0065] The resulting sandwich, wherein each polymer layer has a specific R Z and / or R sm It can be easily laminated between two glass panes, such as between glass panes. The R given above... Z and R sm The value is generated by melt fracture and exists on at least one surface, preferably two surfaces, of the outer layer of the three-layer sandwich, which produces an outer surface that can be easily degassed after they are placed in contact with the glass layer and laminated (e.g., using a roll or vacuum ring degassing process).

[0066] However, as described above, glass panels comprising multiple laminates may include unsightly visual defects and / or optical distortions in the final single structure. Such defects / distortions can be termed mottle, which is a measure of the graininess or texture of the surface regions of the polymer laminates. Mottle is believed to be caused by small-scale surface variations at the interfaces between the layers of a laminate with different refractive indices.

[0067] Traditionally, shadow mapping techniques are used to assess the degree or amount of mottle in multilayered glass panels. Shadow mapping is an optical method that reveals inhomogeneities in transparent media such as air, water, or glass. In principle, the human eye cannot directly see differences or disturbances in transparent air, water, or glass. However, all these disturbances / differences refract light, and therefore they can cast shadows. Shadow mapping utilizes this property of the ability of disturbances or differences in a laminate to cast shadows and uses it to project an image of the inhomogeneities in the laminate onto a screen.

[0068] In conventional methods for determining mottle, the severity of mottle is assessed and classified by qualitatively comparing a shadow map projection of a multilayer test laminate with a set of standard laminate shadow maps from side to side, representing a series or range of mottle values ​​from 0 to 4 (e.g., a CMS2.5 standard laminate with a scale of 0 to 4), where 0 represents no mottle (e.g., a single sheet of unlaminated glass), 1 represents a low mottle criterion (i.e., low breakage number), and 4 represents a high mottle criterion (i.e., high breakage number), which is optically undesirable. In some embodiments, the qualitative comparison can be performed by the human eye or by a computer-implemented test. For example, a mottle analyzer device can be used, in which a camera is typically positioned perpendicular to a reflective screen on which a shadow map is depicted. The camera can capture an image of the shadow map, and a computing device can perform the necessary comparisons to obtain the mottle value of the sample under test.

[0069] For example, the mottle values ​​provided herein are determined using a transparent mottle analyzer (CMA) comprising a xenon arc lamp, a sample holder, a projection screen, and a digital camera. The xenon arc lamp is used to project a shadow map of the laminated sample onto the screen, and the camera is configured to capture an image of the resulting shadow map. The image is then digitally analyzed using computer imaging software and compared with previously captured images of standard samples to determine the mottle of the sample. The method for measuring mottle using a CMA is described in detail in U.S. Patent No. 9,311,699, which is incorporated herein by reference in its entirety.

[0070] As described above, optical defects known as "frosting" are commonly found in glass panel laminates that include multiple layers. The formation of frosting in triple-layer acoustic PVB laminates can be tested by simulating real-world conditions in windshields and other glass windows, where a combination of large bend gaps and poor venting is known to be one of the root causes of frosting in this field. The following steps describe a frosting test that can be used to measure frosting formation in the laminate. First, a 30cm × 30cm triple-layer laminate is sandwiched between two 30cm × 30cm glass panes, with a polyethylene terephthalate (PET) film ring (7.5cm inner diameter, 14cm outer diameter, and 0.10mm–0.18mm thickness) placed at the center of the laminate. This construction is then pre-laminated with high-pressure steam. 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 rate of ice crystal formation within the laminate (e.g., the percentage of the laminate containing ice crystal defects) and the percentage of the area within the PET ring with ice crystal defects. Additionally, the laminate can be visually inspected to determine the percentage of ice crystal formation throughout the entire laminate (including both the interior and exterior of the PET film area).

[0071] In view of the above, embodiments of the present invention include a polymer interlayer with reduced mottle and resistance to the formation of ice flower defects. The polymer interlayer may comprise a first polymer layer (e.g., a core layer) and a second polymer layer (e.g., a skin layer), wherein 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 comprises a texture greater than 40 micrometers made of R… Z The surface roughness is defined by a value. Furthermore, the polymer interlayer has a mottle value less than 1.0. In some embodiments, the second side of the second polymer layer (opposite to the first side) may also include a surface roughness greater than 40 micrometers, which is defined by R... Z Value defined. The 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 polymer layer and the third polymer layer sandwich the first polymer layer in between. In some embodiments, the first side and / or the second side of the third polymer layer may also include components made of R Z The surface roughness is defined as greater than 40 micrometers. A first side of the third polymer layer may contact the first polymer layer, while a second side of the third polymer layer (opposite to the first side) may form the outer surface of the interlayer. The aforementioned surface roughness of the second and third polymer layers may have a regular pattern formed by melt fracture.

[0072] In some embodiments, the surface roughness of the first and / or second surfaces of the second polymer layer (i.e., one of the skin layers) is formed by melt fracture. In some embodiments, by R Z The specified surface roughness will be greater than 40, 50, 60 or 70 micrometers, and / or R Z The values ​​will be between 40 and 70 micrometers, 40 and 60 micrometers, 40 and 50 micrometers, 50 and 70 micrometers, 50 and 60 micrometers, or 60 and 70 micrometers. In some embodiments, each of the surfaces of the first and second sides of the second and third polymer layers (i.e., the skin layer) may be formed with the surface roughness discussed above. In addition to this surface roughness, in some embodiments, the interlayer may have a mottle value of less than 0.9, 0.8, 0.7, 0.6, or 0.5, and / or the mottle value may be 0.0 to 1.0, 0.25 to 1.0, 0.5 to 1.0, 0.5 to 0.9, or 0.5 to 0.8. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer panel, the multilayer panel may be substantially free of frosting formation.

[0073] Additionally, or in combination, the polymer interlayer may include a first polymer layer (e.g., a core layer) and a second polymer layer (e.g., a skin layer), wherein 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 comprises a texture greater than 500 micrometers made of R sm The surface roughness is defined by a value. Furthermore, the polymer interlayer has a mottle value less than 1.0. In some embodiments, a first side of the second polymer layer may contact the first polymer layer. Additionally, a second side of the second polymer layer (opposite to the first side) may also include a surface roughness greater than 500 micrometers formed by R... sm The surface roughness is defined by a value. The second side of the second polymer layer can form the outer surface of the interlayer. In some embodiments, the polymer interlayer can 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 polymer layer and the third polymer layer sandwich the second polymer layer in between. In some embodiments, the first and / or second sides of the third polymer layer may also include components made of R... sm The surface roughness is defined as greater than 500 micrometers. A first side of the third polymer layer may contact the first polymer layer, while a second side of the third polymer layer (opposite to the first side) may form the outer surface of the interlayer. The aforementioned surface roughness of the second and third polymer layers may have a regular pattern formed by melt fracture.

[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, such as by melt fracture. In some embodiments, by R sm The specified surface roughness will be greater than 400, 500, 600, 700 or 800 micrometers, and / or R sm The values ​​are 400 to 800, 500 to 800, 400 to 700, 500 to 700, 400 to 600, 500 to 600, 600 to 700, 600 to 700, or 700 to 800 micrometers. In some embodiments, each of the surfaces of the first and second sides of the second and third polymer layers (i.e., the skin layer) may be formed with the surface roughness discussed above. In addition to this surface roughness, in some embodiments, the interlayer may have a mottle value of less than 0.9, 0.8, 0.7, 0.6, or 0.5, and / or wherein the mottle value is 0.0 to 1.0, 0.25 to 1.0, 0.5 to 1.0, 0.5 to 0.9, or 0.5 to 0.8. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer, the multilayer may be substantially free of frosting formation.

[0075] The aforementioned polymer sandwich can be formed by controlling the temperature properties of the co-extrusion process. For example, embodiments of the present invention include a method for forming a polymer sandwich resistant to optical defects. The method includes the step of extruding a first polymer layer (e.g., a core layer) through a co-extrusion die. An additional step includes extruding a second polymer layer (e.g., a skin layer) through the co-extrusion die. During the extrusion of the second polymer layer, the second polymer layer contacts the die lip of the co-extrusion die. A further step includes extruding a third polymer layer (e.g., another skin layer) through the co-extrusion die. During the extrusion step, the first polymer layer is located between the second and third polymer layers and is disposed on a first side surface of the second polymer layer. During the extrusion of the second polymer layer, the surface of the first side surface of the second polymer layer is roughened by 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. Furthermore, during the extrusion step, the polymer sandwich has a mottle value of less than 1.0.

[0076] The above method can also be described as follows: the melt flow forming the first polymer layer (e.g., the core layer) is extruded through a co-extruder at a temperature different from that of the melt flow forming the second and / or third polymer layers (e.g., the skin layer). Therefore, during the extrusion of the polymer layers, the surface of the first side of the second polymer layer is formed with a surface roughness (e.g., having the aforementioned R) through melt fracture. Z and / or R sm Value). Specifically, this melt fracture can be controlled by controlling the temperature of the die lip that contacts the melt flow forming the second polymer layer. Therefore, the temperature difference between the first polymer layer (i.e., the core layer that does not contact the die lip) and the second polymer layer (i.e., the skin layer that contacts the die lip) can be controlled during extrusion. For example, in some embodiments, by ensuring that the temperature of the die lip is at least 10°C higher than the temperature of the melt flow used to form the first polymer layer (i.e., the core layer) as the polymer layer leaves the die, the necessary surface roughness (e.g., R0) of the first side surface of the second polymer layer (i.e., the skin layer) necessary for reducing ice crystal formation can be achieved. Z Greater than 40 micrometers and / or R sm The surface roughness of the second polymer layer is greater than 500 micrometers, while maintaining low mottle value in the interlayer. The second surface of the second polymer layer can also be formed with a surface roughness through melt fracture in a manner similar to that discussed above (i.e., by controlling the temperature of the die lip of the co-extruder). In any case, embodiments of the invention provide a polymer interlayer with a mottle value of less than 1.0 when extruding the first and second polymer layers. Furthermore, when the polymer interlayer is laminated between a pair of glass panels to form a multilayer board, the multilayer board can be substantially free of frosting formation.

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

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

[0079] In the extrusion process of the sandwich structure of the present invention, the surface roughness of the regular pattern formed on the surfaces 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 mottled characteristics of the resulting sandwich structure can be controlled by controlling the temperature difference between the die lip and the temperature of the first melt flow used to form the first polymer layer (i.e., the core layer). Controlling this temperature difference can enhance the rheological similarity between the skin layer and the core layer, thereby improving the mottled characteristics of the sandwich structure. For example, during the extrusion of the sandwich structure, the temperature difference between one or both die lips and the temperature of the first melt flow can be at least 10°C, 20°C, 30°C, 40°C, or 50°C and / or not more than 50°C, 40°C, 30°C, 20°C, 10°C, or 5°C. Similarly, in some embodiments, during the extrusion of the interlayer, the temperature difference between one or both die lips and the temperature of the first melt flow can 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.

[0080] The preferred mottled value (e.g., less than 1.0) of the aforementioned interlayer can be associated with a specific ΔG' value and / or ΔG' range for one of the skin layer (e.g., the second or third polymer layer) and the core layer (e.g., the first polymer layer). ΔG' 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 typically provided in Pascals (Pa). The storage modulus of each layer of the interlayer described herein can be measured according to ASTM D-4065. For example, storage modulus values ​​can be obtained using dynamic mechanical thermal analysis (DMTA), for example, by using a TADHR-2 rheometer. The polymer layer sample can be clamped and under tension within a test cell. The temperature of the test cell can be initially set to 75°C. Sinusoidal tensile strain can be applied to the sample at a given frequency within a certain temperature range, and the resulting stress response can be measured. For example, a sinusoidal tensile strain can be applied to the sample at 1 Hz, while the sample temperature can be moved from 20°C to 200°C. The temperature slope can be approximately 3°C / min, and data (i.e., the stress of the sample) can be collected every 10 seconds. The storage modulus can be obtained from the stress-to-strain ratio, where it should be understood that the storage modulus value of a given sample will generally vary with the temperature applied to the sample. For oscillating tensile deformation, the storage modulus is the real part of the complex modulus. When obtaining the storage modulus values ​​of one of the skin layers and the core layer, the difference between these storage modulus values ​​can be calculated to obtain the ΔG' value.

[0081] Embodiments of the present invention include polymer sandwiches and / or methods for preparing polymer sandwiches resistant to optical defect formation, wherein such polymer sandwiches have polymer layers with a preferred ΔG' value. For example, embodiments of the present invention may include polymer sandwiches formed according to the following method: One step includes extruding a first polymer layer (e.g., a core layer) through a co-extrusion die. An additional step includes extruding a second polymer layer (e.g., a skin layer) through a co-extrusion die. A further step includes extruding a third polymer layer (e.g., a skin layer) through a co-extrusion die. During the extrusion step, the first polymer layer is located between the second and third polymer layers. 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 and second storage modulus values ​​(i.e., the ΔG' value) may be less than about 45,000 Pa. After the extrusion step, the polymer sandwich has a mottled value of less than 1.0.

[0082] Embodiments of the present invention may provide a sandwich layer having a ΔG' value measured during co-extrusion of the sandwich layer via a co-extrusion apparatus, wherein the ΔG' 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) is 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. In some embodiments, the ΔG' value between one of the cortex layers and the core layer may be 5,000 Pa to 60,000 Pa, 5,000 Pa to 50,000 Pa, 5,000 Pa to 40,000 Pa, 5,000 Pa to 30,000 Pa, 10,000 Pa to 50,000 Pa, 10,000 Pa to 40,000 Pa, 10,000 Pa to 30,000 Pa, 15,000 Pa to 50,000 Pa, 15,000 Pa to 40,000 Pa, 15,000 Pa to 30,000 Pa, 20,000 Pa to 50,000 Pa, 20,000 Pa to 40,000 Pa, or 20,000 Pa to 30,000 Pa.

[0083] Example 1

[0084] Two three-layer sandwich structures are formed, each comprising a core layer sandwiched between a pair of skin layers. Skin layers with a regular melt fracture pattern are formed by controlling the die lip temperature of the die used to form the skin layers. The skin layers are formed from PVB resin with a unimodal molecular weight distribution and a polydispersity index of less than 3.0. The skin layer resin includes 38 phr of plasticizer, and, if desired, adhesion control agents and UV stabilizers. The core layer resin includes PVB and includes 75 phr of plasticizer, and, if desired, adhesion control agents and UV stabilizers. The sandwich structures are formed via a co-extrusion process. During extrusion, the die lip bolts are operated at 30% power, setting the hot die lip gap to 41 mils (1.04 mm). The extrusion rate is set to 550 psi (250 kg / h). The melt tube, EAMF filter, skin die lip, and body temperatures are set to 204°C. The core melt temperature of the core layer is set between 170°C and 180°C.

[0085] A first three-layer sandwich, EX1-IIL1, was formed, with a surface roughness lower than that of the second three-layer sandwich, EX2-IIL2. Surface roughness measurements of the two outer surfaces (i.e., the two outer surfaces of the relevant skin layer) of each of EX1-IIL1 and EX1-IIL2 are provided in Table 1 below. MD refers to the surface roughness in the machine direction, while CMD refers to the surface roughness in the machine transverse direction. Mottled areas were also measured for each three-layer sandwich.

[0086] Table 1

[0087]

[0088] As shown in the data of Example 1, a preferred mottle value (e.g., a mottle value less than 1.0) is obtained by controlling the regular pattern surface roughness of the skin layer imparted by melt fracture. Specifically, a surface roughness value R... Z Between 40 and 60 micrometers and / or R sm Triple-layer sandwiches in the skin layer between 400 and 700 micrometers, such as EX1-IIL1, provide a preferred mottle value of less than 1.0. Conversely, triple-layer sandwiches with a surface roughness value R... Z Greater than 60 micrometers and / or R sm The three-layer sandwich structure of the cortex with a diameter greater than 800 micrometers showed that this sandwich structure had a non-preferred mottle value greater than 1.0.

[0089] Example 2

[0090] Two three-layer sandwiches of the present invention (the sandwiches of the present invention in Example 2: EX2-IIL1 and EX2-IIL2) are formed according to the same method described for EX1-IIL1 and EX1-IIL2 in Example 1. Therefore, each sandwich of the present invention, EX2-IIL1 and EX2-IIL2, includes a core layer sandwiched between a pair of skin layers, and a skin layer with a regular melt fracture pattern is formed by controlling the die lip temperature of the mold used to form the skin layer. The resulting three-layer sandwiches of the present invention, EX2-IIL1 and EX2-IIL2, have a surface roughness value R between 40 and 60 micrometers. Z R between 400 and 700 micrometers sm And a mottled value less than 1.0.

[0091] Two control three-layer sandwiches (Example 2 control sandwiches: EX2-CIL1 and EX2-CIL2) are formed using standard, existing techniques, wherein embossing is used to create a surface roughness on the skin layer. In contrast to the sandwiches of the present invention, the skin surface of the control sandwiches is not formed by melt fracture. Instead, the control sandwiches comprise a surface pattern on the skin layer formed by embossing.

[0092] Table 2 below shows the measured mottle values ​​for each of EX2-IIL1, EX2-IIL2, EX2-CIL1, and EX2-CIL2. These mottle values ​​were measured at the time of interlayer formation (e.g., at time zero) and thirty-five days after interlayer formation. Table 2 also shows the average mottle values ​​for the interlayer of the present invention and a control interlayer.

[0093] Table 2

[0094] midnight 35 days EX2-IIL1 0.63 0.83 EX2-IIL2 0.53 0.78 average 0.58 0.81 EX2-CIL1 0.73 1.17 EX2-CIL2 0.83 1.14 average 0.78 1.16

[0095] As shown in the data of Example 2, excellent and highly desirable mottle values ​​(e.g., mottle values ​​less than 1.0) can be obtained by controlling the regular pattern surface roughness of the skin layer imparted by melt fracture. For each of the sandwich layers EX2-IIL1 and EX2-IIL2 of the present invention, this mottle value is optimally maintained below 1.0 at formation and thirty-five days after formation. Conversely, although the control sandwich layers EX2-CIL1 and EX2-CIL2 (which include surface roughness formed by embossing) include mottle values ​​below 1.0 at formation, the control sandwich layers have undesirable mottle values ​​greater than 1.0 after thirty-five days.

[0096] Example 3

[0097] Ten three-layer sandwiches of the present invention (the sandwiches of the present invention in Example 3: EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) are formed according to the same method described for EX1-IIL1 and EX1-IIL2 in Example 1. Therefore, each of the sandwiches of the present invention in EX3-IIL1 to EX3-IIL10 includes a core layer sandwiched between a pair of skin layers, and a skin layer with a regular melt fracture pattern is formed by controlling the die lip temperature of the mold used to form the skin layer. The resulting three-layer sandwiches of the present invention EX3-IIL1 to EX3-IIL10 have a surface roughness value R between 40 and 60 micrometers. Z R between 400 and 700 micrometers sm And a mottled value less than 1.0.

[0098] Furthermore, ten control three-layer sandwiches (control sandwiches of Example 3: EX3-CIL1, EX3-CIL2, ..., EX3-CIL10) were formed using standard existing techniques, wherein the method uses embossing to create surface roughness on the skin layer. In contrast to the sandwiches of the present invention, the skin surface of the control sandwiches is not formed by melt fracture. Instead, the control sandwiches comprise a surface pattern on the skin layer formed by embossing.

[0099] Each of the three-layer sandwich structure of the present invention and the control sandwich structure was tested according to the above-described ice flower test. It is noteworthy that the laminates formed using the three-layer sandwich structure of the present invention (EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) did not show any ice flower formation. Specifically, Figure 6 These are photographs of stacked laminates, each laminate comprising one of the three-layer sandwich structures of the present invention (EX3-IIL1, EX3-IIL2, ..., EX3-IIL10) laminated between a pair of glass plates. As shown, none of these laminates exhibit any frosting formation. Conversely, each laminate formed using the control three-layer sandwich structure (EX3-CIL1, EX3-CIL2, ..., EX3-CIL10) was found to exhibit varying degrees of frosting formation, such as... Figure 7 As shown, it is a photograph of a laminated structure formed by three layers of contrast material. Specifically, as... Figure 7 As shown, it was found that the lower part of the laminate formed by the control three-layer interlayer included ice flower formation.

[0100] Example 4

[0101] Two three-layer sandwiches of the present invention (the sandwiches of the present invention in Example 4: EX4-IIL1 and EX4-IIL2) are formed according to the same method described for EX1-IIL1 and EX1-IIL2 in Example 1. Therefore, each sandwich of the present invention, EX4-IIL1 and EX4-IIL2, includes a core layer sandwiched between a pair of skin layers, and a skin layer with a regular melt fracture pattern is formed by controlling the die lip temperature of the mold used to form the skin layer. The resulting three-layer sandwiches of the present invention, EX4-IIL1 and EX4-IIL2, have a surface roughness value R between 40 and 60 micrometers. Z R between 400 and 700 micrometers sm And a mottled value less than 1.0.

[0102] Two embossed control three-layer sandwiches (Example 4 control sandwiches: EX4-CIL1 and EX4-CIL2) are formed using standard, existing techniques, wherein the method uses embossing to create surface roughness on the skin layer. In contrast to the sandwiches of the present invention, the skin surface of the control sandwiches is not formed by melt fracture. Instead, the control sandwiches comprise a surface pattern on the skin layer formed by embossing.

[0103] Furthermore, two random melt fracture control three-layer sandwiches were formed using existing techniques (Example 4 control sandwiches: EX4-RIL1 and EX4-RIL2). In contrast to the sandwiches of the present invention, the skin of the control sandwiches does not exhibit a regular patterned surface roughness resulting from melt fracture. Conversely, the random control sandwiches include random surface patterns on the skin formed by melt fracture.

[0104] After degassing in a vacuum bag, the transmittance of each laminated sample was tested. Vacuum bag degassing is a technique used to remove air from a sample before the final step of high-pressure steam treatment. It is often used to improve autoclave yields in industrial operations. Each laminated sample was placed between two glass panels and laminated to form a laminated panel. Note that one of each sample was laminated with a flat, unformed glass panel (referred to as “unformed” in Table 3), while the other of each sample was laminated with a formed (e.g., curved) glass panel (referred to as “formed” in Table 3). The laminated panels were then placed in an elastic rubber bag and evacuated using a vacuum hose fitted to the bag. The bag was raised to approximately 50°C and held for 60 minutes, then held under vacuum 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.

[0105] Transmittance was measured as a percentage after degassing in the vacuum bag and before high-pressure steam. A low percentage transmittance value indicates insufficient degassing, while a high percentage transmittance value indicates acceptable degassing. Transmittance was tested using a spectrophotometer. Eight tests were performed on each laminate at its dispersion location throughout the entire laminate, and the eight results were averaged to obtain the transmittance value, as shown in Table 3, where LT is the transmittance.

[0106] Table 3

[0107]

[0108]

[0109] As can be seen from Table 3 above, the two embossed control three-layer sandwiches EX4-CIL1 and EX4-CIL2 exhibit the best light transmittance characteristics (highest percentage of transmittance, indicating better or acceptable degassing), while the two random control three-layer sandwiches EX4-RIL1 and EX4-RIL2 exhibit the lowest or worst light transmittance characteristics (lowest percentage of transmittance, indicating unacceptable degassing). The two three-layer sandwiches of the present invention EX4-IIL1 and EX2-IIL4 exhibit improved light transmittance characteristics (i.e., improved or higher percentage of transmittance, indicating acceptable degassing) compared to the two random control three-layer sandwiches EX4-RIL1 and EX4-RIL2. Therefore, this example shows that the three-layer sandwiches of the present invention can be adequately degassed by a standard vacuum bag degassing process, while random three-layer sandwiches formed with random melt fracture patterns cannot be adequately degassed by such a standard vacuum bag degassing process. Specifically, the random three-layer sandwich structure must also be embossed (as in the control three-layer sandwich structure) in order to fully degas, while the three-layer sandwich structure of the present invention does not require further embossing for full degassing.

[0110] Example 5

[0111] Four polymer layers were formed (polymer layers of Example 5: EX5-PL1, EX5-PL2, EX5-PL3, and EX5-PL4). The polymer layers of Example 5 were then tested according to ASTM D-4065, as described below, to determine the storage modulus values ​​of the polymer layers at various temperatures. In determining these storage modulus values, the ΔG' value was calculated to compare EX5-PL4 with each of EX5-PL1, EX5-PL2, and EX5-PL3.

[0112] For the EX5-PL1, EX5-PL2, and EX5-PL3 polymer layers, these polymer layers are formed by mixing PVB resin and a 38 phr plasticizer. The resin of the EX5-PL1 polymer layer has a molecular weight of 150 kDa, while the resins of the EX5-PL2 and EX5-PL3 polymer layers have a molecular weight of 160 kDa.

[0113] For the EX5-PL4 polymer layer, this polymer layer contains PVB and a 75 phr plasticizer. The resin of the EX5-PL4 polymer layer has a molecular weight of 250-300 K Daltons. Considering the composition of the polymer layers in Example 5 above, EX5-PL4 generally corresponds to the core layer of the acoustic triplex sandwich, while EX5-PL1, EX5-PL2, and EX5-PL3 generally correspond to the skin layers of the acoustic triplex sandwich.

[0114] As previously described, the storage modulus values ​​for each of the polymer layers in Example 5 were obtained using dynamic mechanical thermal analysis (DMTA). The storage modulus values ​​for the polymer layers were then obtained at various temperatures shown in Table 4 below. For the EX5-PL1 and EX5-PL2 polymer layers, storage modulus values ​​were obtained at 10-degree intervals at temperatures ranging from 140°C to 200°C. For the EX5-PL3 polymer layer, the storage modulus value was obtained at 200°C. For the EX5-PL4 polymer layer, the storage modulus values ​​were obtained at temperatures of 170°C and 180°C.

[0115] When obtaining the storage modulus values ​​of the polymer layers in Example 5, the differences between the storage modulus values ​​of EX5-PL4 and each of EX5-PL1, EX5-PL2, and EX5-PL3 were calculated to obtain the ΔG' values ​​(at a specified temperature) for these samples. The resulting ΔG' values ​​are provided in Table 4 below. Note that the ΔG' values ​​were obtained by subtracting the storage modulus values ​​of EX5-PL1, EX5-PL2, and / or EX5-PL3 from the storage modulus value of EX5-PL4, respectively. Therefore, a positive ΔG' value indicates that the EX5-PL4 polymer layer (i.e., the core layer) is relatively softer than the EX5-PL1, EX5-PL2, and / or EX5-PL3 polymer layers (i.e., the skin layer). Conversely, a negative ΔG' value indicates that the EX5-PL4 polymer layer is relatively harder than the EX5-PL1, EX5-PL2, and / or EX5-PL3 polymer layers.

[0116] Table 4

[0117]

[0118] As shown in Table 4, when the DMTA test temperature of the EX5-PL1 polymer layer is equal to or greater than approximately 160°C (and the temperature of the EX5-PL4 polymer layer is approximately 170°C or 180°C), the ΔG' value obtained when comparing the EX5-PL1 and EX5-PL4 polymer layers is less than or equal to approximately 30,000 Pa. It is estimated that when the DMTA test temperature of the EX5-PL1 polymer layer is equal to or greater than approximately 160°C, the mottle value of the interlayer formed by the EX5-PL1 and EX5-PL4 polymer layers is equal to or less than 1.0. Conversely, it is estimated that when the DMTA test temperature of the EX5-PL1 polymer layer is less than 160°C, the mottle value of the interlayer formed by the EX5-PL1 and EX5-PL4 polymer layers is greater than 1.0. Therefore, the ΔG' values ​​and corresponding estimated mottle values ​​in Table 4 illustrate that when the ΔG' value is less than or equal to about 30,000 Pa, the interlayer formed by the EX5-PL1 and EX5-PL4 polymer layers has a preferred mottle value (i.e., less than or equal to 1.0). Conversely, Table 4 illustrates that when the ΔG' value is greater than or equal to about 50,000 Pa, the interlayer formed by the EX5-PL1 and EX5-PL4 polymer layers has a non-preferred mottle value (i.e., greater than 1.0).

[0119] As further shown in Table 4, when the DMTA test temperature of the EX5-PL2 polymer layer is equal to or greater than about 160°C (the temperature of the EX5-PL4 polymer layer is about 170°C or 180°C), the ΔG' value obtained when comparing the EX5-PL2 and EX5-PL4 polymer layers is less than or equal to about 42,000 Pa. It is estimated that when the DMTA test temperature of the EX5-PL2 polymer layer is equal to or greater than about 160°C, the mottle value of the interlayer formed by the EX5-PL2 and EX5-PL4 polymer layers is equal to or less than 1.0; conversely, it is estimated that when the DMTA test temperature of the EX5-PL2 polymer layer is less than 160°C, the mottle value of the interlayer formed by the EX5-PL2 and EX5-PL4 polymer layers is greater than 1.0. Therefore, the ΔG' values ​​and the corresponding estimated mottle values ​​in Table 4 indicate that the interlayer formed by the EX5-PL2 and EX5-PL4 polymer layers has a preferred mottle value when the ΔG' value is less than or equal to about 42,000 Pa. Conversely, Table 4 illustrates that when the ΔG' value is greater than or equal to about 60,000 Pa, the interlayer formed with the EX5-PL2 and EX5-PL4 polymer layers has a non-preferred mottled value.

[0120] As further shown in Table 4, when the DMTA test temperature of the EX5-PL3 polymer layer is approximately 200°C (the temperature of the EX5-PL4 polymer layer is approximately 170°C or 180°C), the ΔG' value obtained when comparing the EX5-PL3 and EX5-PL4 polymer layers is less than or equal to approximately -3,300 Pa. It is estimated that when the DMTA test temperature of the EX5-PL3 polymer layer is equal to or greater than approximately 200°C, the mottle value of the interlayer formed with the EX5-PL3 and EX5-PL4 polymer layers is equal to or less than 1.0. Therefore, the ΔG' values ​​and corresponding estimated mottle values ​​in Table 4 indicate that the interlayer formed with the EX5-PL3 and EX5-PL4 polymer layers has a preferred mottle value when the ΔG' value is less than or equal to approximately -3,300 Pa. As described above, a negative ΔG' 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). The preferred mottled value of the polymer interlayer containing EX5-PL3 and EX5-PL4 polymer layers may be due, at least in part, to the fact that a negative ΔG' value indicates that the EX5-PL3 polymer layer (skin layer) is softer than the EX5-PL4 polymer layer (i.e., core layer), and therefore the EX5-PL3 polymer layer has a reduced ability to imprint its melt fracture onto the EX5-PL4 polymer layer.

[0121] While the invention has been disclosed in conjunction with a description of certain embodiments, including those currently considered preferred embodiments, the detailed description is intended to be illustrative and should not be construed as limiting the scope of this disclosure. As will be understood by those skilled in the art, embodiments other than those described in detail herein are also covered by the invention. Modifications and variations may be made to the described embodiments without departing from the spirit and scope of the invention.

[0122] It should also be understood that any range, value, or characteristic given for any single component of this disclosure may be used interchangeably with any range, value, or characteristic given for any other component of this disclosure, where compatible, to form embodiments with defined values ​​for each component, as given throughout this document. For example, polymer layers may be formed that include, in addition to any given range of residual hydroxyl content, any given range of plasticizer content, forming, where appropriate, a number of arrangements within the scope of this invention, but this would be difficult to list.

Claims

1. A polymer interlayer resistant to optical defect formation, the polymer interlayer comprising: First polymer layer; and Second polymer layer; The first polymer layer is disposed on the first side of the second polymer layer. The non-embossed surface of the first side of the second polymer layer includes a texture greater than 40 micrometers made of R Z A surface roughness defined by a value, wherein the surface roughness is a regular pattern surface roughness formed by melt fracture. The polymer interlayer has a mottle value of less than 1.

0.

2. A polymer interlayer resistant to optical defect formation, the polymer interlayer comprising: First polymer layer; and Second polymer layer; The first polymer layer is disposed on the first side of the second polymer layer. The surface of the first side of the second polymer layer includes a layer larger than 500 micrometers made of R SM A surface roughness defined by a value, wherein the surface roughness is a regular pattern surface roughness formed by melt fracture. The polymer interlayer has a mottle value of less than 1.

0.

3. The polymer interlayer according to claim 1 or 2, wherein the R Z The value is greater than 50 micrometers.

4. The polymer interlayer according to claim 1, wherein the surface of the first side of the second polymer layer comprises a layer of R with a diameter greater than 500 micrometers. SM Surface roughness defined by a value.

5. The polymer interlayer according to claim 1 or 2, wherein the R SM The value is greater than 600 micrometers.

6. The polymer interlayer according to claim 1 or 2, wherein the mottle value is less than 0.

9.

7. The polymer interlayer according to claim 1 or 2, wherein the first polymer layer has a first storage modulus, wherein the second polymer layer has a second storage modulus, and wherein the difference between the first storage modulus and the second storage modulus is less than 45,000 Pa.

8. The polymer interlayer according to claim 1 or 2, further comprising a third polymer layer, wherein the first polymer layer is located between the second polymer layer and the third polymer layer.

9. The polymer interlayer according to claim 1 or 2, wherein the thickness of the first polymer layer is generally constant along the length of the polymer interlayer.

10. The polymer interlayer according to claim 1 or 2, 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.

11. A method for forming a polymer interlayer resistant to optical defects, the method comprising the steps of: (a) The first polymer layer is extruded through a co-extrusion die; (b) Extruding a second polymer layer through the co-extrusion die; as well as (c) Extruding a third polymer layer through the co-extrusion die; During the extrusion in steps (a), (b), and (c), the first polymer layer is located between the second polymer layer and the third polymer layer. During the extrusion in step (a), the first polymer layer has a first storage modulus value, and during the extrusion in step (b), the second polymer layer has a second storage modulus value, wherein the difference between the first storage modulus value and the second storage modulus value is less than 45,000 Pa. During the extrusion in steps (a), (b), and (c), the polymer interlayer has a mottle value of less than 1.

0.

12. The method according to claim 11, wherein the difference between the first energy storage modulus value and the second energy storage modulus value is less than 40,000 Pa.

13. The method of claim 11, wherein the surface roughness of the surface of the second polymer layer is determined by R. Z Value limitation, wherein R Z The value is greater than 40 micrometers.

14. The method of claim 11, wherein the surface roughness of the surface of the second polymer layer is determined by R. SM Value limitation, wherein R SM The value is greater than 500 micrometers.

15. The method of claim 11, wherein the mottled value is less than 0.

9.

16. The method of claim 11, wherein the extrusion in steps (a), (b) and (c) is performed simultaneously.

17. The method of claim 16, wherein the extrusion in steps (a), (b) and (c) is performed via co-extrusion.

18. A polymer interlayer resistant to optical defect formation, wherein the polymer interlayer is formed by the method according to any one of claims 11-17.

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