Sandwich frame for encapsulating functional film

Abstract

Disclosed herein is a method for constructing a functional sandwich stack, the method comprising: a) cutting two L-shaped pieces from a corner of a body sheet of sandwich material, leaving a cut sheet; b) optionally trimming one or more of the two L-shaped pieces or the cut sheets; c) connecting the L-shaped pieces to form a rectangular frame defining a rectangular opening; d) placing the rectangular frame around a functional material to obtain a frame-type functional sheet; and e) covering the framed functional sheet with a cut sheet to form the functional sandwich stack, wherein the cut sheet of step e) is the same sheet as or a different sheet from the cut sheet of step a).

Description

TECHNICAL FIELD

[0001] The present invention relates generally to interlayers for encapsulating functional films. BACKGROUND

[0002] The present invention relates to a method for effectively reducing scrap or process waste in the encapsulation process of functional films, such as switchable films. Smart glass or switchable glass is manufactured by adding a switchable film to a laminate. The most common switchable films are based on polymer dispersed liquid crystals (PDLC), suspended particle devices (SPD) or electrochromic (EC) devices, photochromic devices or photochromic / electrochromic devices. To adhere to glass, the switchable film is confined between thermoplastic interlayer films, such as plasticized polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or thermoplastic polyurethane (TPU).

[0003] Typically, these switchable films are cut slightly smaller than the total area of the laminate so that there is a border of glass and interlayer to protect the edges of the switchable film (U.S. Patent No. 8,995,039). One issue with this is that the absence of switchable film at the border of the laminate causes optical distortion. To compensate for this thickness imbalance, the switchable film is constructed with an interlayer frame.

[0004] For example, this “picture frame” design is described in U.S. Patent No. 10,596,787. These interlayer frames are cut from 0.5 mm thick PVB sheets, for example, so that the switchable film can be placed within the frame, while the corner scraps in the middle of each sheet are currently considered waste ( Figure 1 ). The switchable film and interlayer frame are then sandwiched between interlayer films and laminated between glass sheets.

[0005] Accordingly, what is needed in the art is an improved method of making interlayer frames that reduces scrap or process waste. SUMMARY

[0006] In one aspect, the present invention relates to a method of constructing a functional interlayer stack comprising the steps of: a) cutting two L-shaped pieces from a corner of a bulk sheet of interlayer material, leaving a cut sheet; b) optionally trimming one or more of the two L-shaped pieces or the cut sheet; c) joining the L-shaped pieces to form a rectangular frame defining a rectangular opening; d) placing the rectangular frame around a functional material to obtain a framed functional sheet; and e) covering the framed functional sheet with a cut sheet to form a functional interlayer stack, the functional interlayer stack being a multilayer stack. According to the present invention, the cut sheet of step e) can be the same sheet as the cut sheet of step a) or a different sheet.

[0007] Further aspects of the present invention are as disclosed and claimed herein.BRIEF DESCRIPTION OF DRAWINGS BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 Prior art methods of cutting sandwich frames from a bulk sheet of interlayer material are depicted, which result in a large amount of waste.

[0009] Figure 2 An embodiment of the present invention is depicted, wherein L-shaped pieces can be cut from a bulk sandwich sheet or an oversized sandwich sheet and connected together to form a rectangular frame for a functional sheet. The remaining portion of the cut sheet can be used as a top layer for a functional stack. DETAILED DESCRIPTION

[0010] In an embodiment, the present invention relates to a method of constructing a functional sandwich stack comprising the steps of: a) cutting two L-shaped pieces from a corner of a bulk sheet of interlayer material, leaving a cut sheet; b) optionally trimming one or more of said two L-shaped pieces or said cut sheet; c) connecting said L-shaped pieces to form a rectangular frame defining a rectangular opening; d) placing said rectangular frame around a functional material to obtain a framed functional sheet; and e) covering the framed functional sheet with the cut sheet to form a functional sandwich stack, said functional sandwich stack being thus a multilayer sandwich having a reference function. According to the present invention, the cut sheet of step e) can be the same sheet as the cut sheet of step a) or a different sheet.

[0011] In an embodiment, a variety of functional materials can be used. Thus, the functional material can comprise a photopolymer material, an electrically conductive material, a solar reflective material, a polymer dispersed liquid crystal material, a suspended particle material, an electrochromic material, a photochromic material, an electrochromic / photochromic material, etc.

[0012] In an embodiment according to any of the preceding embodiments, the cut sheet of step e) can be the same sheet as the cut sheet of step a).

[0013] In an embodiment according to any of the preceding embodiments, the cut sheet of step e) can be a different sheet than the cut sheet of step a).

[0014] In an embodiment according to any of the preceding embodiments, the interlayer material can be a viscoelastic polymer.

[0015] In an embodiment according to any of the preceding embodiments, the viscoelastic polymer can comprise one or more of a polyvinyl acetal such as polyvinyl butyral, a thermoplastic polyurethane, or an ethylene vinyl acetate.

[0016] In embodiments according to any of the preceding embodiments, the cut sheet of step a) and the cut sheet of step e) comprise polyvinyl butyral having a thickness of, for example, about 0.1 mm to 1.0 mm.

[0017] In embodiments according to any of the preceding embodiments, the cut sheet of step a) and the cut sheet of step e) comprise polyvinyl butyral having a thickness of, for example, about 0.2 mm to 0.8 mm.

[0018] In embodiments according to any of the preceding embodiments, the present invention can further comprise covering the framed switchable sheet with another cut sheet on the side opposite the cut sheet of step e). In this aspect, the stack is of course a multi-ply sandwich and can be considered to be three-ply, with the framed switchable sheet having a cut sheet on either side thereof.

[0019] In embodiments according to any of the preceding embodiments, the present invention can further comprise placing a rigid substrate on either side of the functional sandwich stack to form a functional laminate.

[0020] According to the present invention, we have discovered a new method of constructing a sandwich frame that reduces waste or process scrap in the encapsulation process of functional films such as switchable films, photopolymers films, conductive films, solar reflective films, and the like. Thus, the present invention relates to a method of effectively reducing waste or process scrap in the encapsulation process of functional films such as switchable films.

[0021] According to the present invention, a functional laminate such as switchable glass is manufactured by adding a functional film to the laminate. The most common switchable film is based on polymer dispersed liquid crystals (PDLC), suspended particle devices (SPD) or electrochromic (EC) devices. To be bonded to glass, the switchable film can be confined between thermoplastic interlayer films such as plasticized polyvinyl butyral (PVB), ethyl vinyl acetate (EVA) or thermoplastic polyurethane (TPU).

[0022] The present invention provides a new method for designing a sandwich frame for functions such as switchable glass. According to the present invention, the sandwich frame is made from two L-shaped segments cut from an oversized PVB sheet ( Figure 2 ) The two L-shaped segments are then welded or brazed together to form a single sandwich frame, while the middle segment of the oversized PVB sheet can be used as a top or bottom ply to laminate a switchable film to glass. The method of constructing a sandwich frame from L-shaped segments and reducing waste to an absolute minimum is non-obvious to one skilled in the art as it belongs to a unique method that has not been considered or practiced heretofore.

[0023] It will be appreciated that while particularly effective for switchable films, the method can be used for any functional film, including for example, a photopolymer film, a conductive film, or a solar reflective film, regardless of the functionality provided by the laminate. There are also many methods to weld the connections between the preformed L-shaped PVB segments according to the present invention. Examples are hot air welding or ultrasonic welding (see for example US patent publication number US20200278540A1).

[0024] Thus, in one aspect, the present invention relates to a method of constructing a functional interlayer stack. The present invention can thus include a wide variety of functionality. In various embodiments, the functional material can include one or more of: the functional material can include a photopolymer material, a conductive material, a solar reflective material, a polymer dispersed liquid crystal material, a suspended particle material, an electrochromic material, a photochromic material, or an electrochromic / photochromic material, or a holographic optical element. Other suitable functions include photovoltaics, transparent displays such as heads-up displays, signage, or roofing materials, etc.

[0025] According to the present invention, two L-shaped pieces can be cut from the corner of a bulk sheet of interlayer material, leaving a cut sheet. After any optional trimming that can be required, the L-shaped pieces will be cut to fit to form a rectangular frame. The L-shaped pieces will roughly define a rectangular frame by having a corner shape of approximately 90 degrees, and thus, once connected together, each L-shaped piece is able to form two sides of a rectangular frame.

[0026] The bulk sheet of interlayer material can be selected from a variety of materials, and its dimensions will be suitable for the L-shaped pieces and a cut sheet of suitable dimensions cut therefrom and used as, for example, a top layer and / or a bottom layer.

[0027] According to the intended use, in one aspect, when used to form a windshield / roof laminate, the bulk sheet can be about 140 cm x 180 cm, or 120 to 160 cm or 130 to 150 cm in size. In another aspect, for example in the case of a conventional sunroof, the bulk sheet can be about 80 cm x 100 cm, or for example 150 to 180 or 100 to 150 in size.

[0028] One or both of the two L-shaped pieces and the cut sheet can be further trimmed as required or desired prior to use.

[0029] Accordingly, in accordance with the present application, the bulk sheet of interlayer material can be selected from a variety of materials, and in particular, viscoelastic materials. The viscoelastic material can be a polyvinyl acetal, such as polyvinyl butyral. As noted above, the L-shaped pieces forming the rectangular frame can be the same or different from the cut sheet material, which can be considered to be an outer layer that can be contacted with a rigid substrate to form a functional laminate. If the material of the L-shaped pieces is different from the material of the cut sheet material, then a different bulk sheet material will naturally be required.

[0030] Accordingly, embodiments of the present application are directed to multilayer panels and methods of manufacturing multilayer panels. Generally, a multilayer laminate is constructed of two sheets of glass or other suitable substrate with one or more polymeric interlayer sheets sandwiched therebetween. The multilayer panel is generally produced by placing at least one polymeric interlayer sheet between two substrates to form an assembly. As noted above, the multilayer interlayer can be configured as a three-layer interlayer having three separate polymeric interlayer sheets, including a core layer and two skin layers on either side of the core layer.

[0031] In some embodiments, the interlayer (e.g., core layer and skin layers) will have a substantially constant or uniform thickness with respect to the length of the interlayer. However, in alternative embodiments, the interlayer can have at least one region of non-uniform thickness. For example, the interlayer constructed of a core layer and skin layers can be wedge-shaped such that the thickness of the interlayer varies (e.g., linearly or non-linearly) around the length of the interlayer. In some such embodiments, the thickness of the interlayer can vary due to a change in thickness of the core layer (i.e., the skin layers have a substantially constant thickness). Alternatively, the thickness of the interlayer can vary due to a change in thickness of the skin layers (i.e., the core layer has a substantially constant thickness). In further alternatives, the thickness of the interlayer can vary due to a change in thickness of both the core layer and the skin layers.

[0032] To facilitate a more complete understanding of the interlayers and multilayer panels disclosed herein, the meaning of certain terms used in this application will be defined.

[0033] As used herein, the terms“polymeric interlayer sheet,”“interlayer,”“polymeric layer,” and“polymeric melt sheet” can refer to a single layer sheet or a multi-layer interlayer. As the name implies, a“single layer sheet” is a single polymeric layer that is extruded as one layer. On the other hand, a multi-layer interlayer can include multiple layers, including individually extruded layers, co-extruded layers, or any combination of individually and co-extruded layers. Thus, a multi-layer interlayer can include, for example: two or more single layer sheets combined together (“multi-layer sheet”); two or more layers co-extruded together (“co-extruded sheet”); 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 multi-layer sheet and at least one co-extruded sheet. In various embodiments of the present application, a multi-layer interlayer includes at least two polymeric layers (e.g., single layer or multi-layer co-extruded) disposed in direct contact with each other, wherein each layer comprises a polymeric resin. As used herein, the term“resin” refers to the polymeric component (e.g., PVB) removed from the process, such as those discussed more fully below. Typically, a plasticizer, such as those discussed more fully below, is added to the resin to produce a plasticized polymer. Additionally, as described below, the resin can have other components in addition to the polymer and plasticizer, including, for example, acetates, salts, and alcohols.

[0034] It should also be noted that while polyvinyl butyral (“PVB”) interlayers are specifically discussed throughout this application as the polymeric resin of the polymeric interlayer, it should be understood that other thermoplastic interlayers can also be used in addition to PVB interlayers. Contemplated polymers include, but are not limited to, polyurethanes, polyvinyl chlorides, poly(ethylene vinyl acetate), and combinations thereof. These polymers can be used individually, or in combination with other polymers. Thus, it should be understood that when ranges, values, and / or methods (e.g., plasticizer component percentages, thicknesses, and property enhancing additives) are given in this application for PVB interlayers, these ranges, values, and / or methods also apply to other polymers and polymer blends disclosed herein, where applicable, or can be modified as known to one of ordinary skill in the art to apply to different materials.

[0035] As used herein, the term“molecular weight” refers to weight average molecular weight (Mw). The molecular weight of a PVB resin can range from about 50,000 Daltons to about 600,000 Daltons, from about 70,000 Daltons to about 450,000 Daltons, or from about 100,000 Daltons to about 425,000 Daltons.

[0036] PVB resins can be prepared by known aqueous or solvent acetalization processes in which polyvinyl alcohol ("PVOH") is reacted with butyraldehyde in the presence of an acid catalyst, followed by resin isolation, stabilization, and drying. Such acetalization processes are disclosed, for example, in U.S. Patent Nos. 2,282,057 and 2,282,026, the relevant disclosures of which are incorporated herein by reference.

[0037] While generally referred to herein as "poly(vinyl acetal)" or "poly(vinyl butyral)", the resins described herein can include residues of any suitable aldehyde, including but not limited to isobutyraldehyde, as previously described. In some embodiments, one or more poly(vinyl acetal) resins can comprise at least one Ci to C 10 residue of a C4to C8aldehyde. Examples of suitable C4to C8aldehydes can include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylpentanal, n-hexanal, 2- ethylhexanal, n-octanal, and combinations thereof.

[0038] In many embodiments, plasticizers are added to the polymer resins to form the polymer layers or interlayers. Plasticizers are generally added to the polymer resins to increase the flexibility and durability of the resulting polymer interlayer. Plasticizers lower the glass transition temperature (T g ) of the polymer resins by intercalating themselves between the polymer chains, spacing the polymer chains apart (increasing "free volume"), thereby making the material more flexible. In this regard, the amount of plasticizer in the interlayer can be adjusted to affect the glass transition temperature (T g ). The glass transition temperature (T g ) is the temperature marking the transition from the glassy to the rubbery state of the interlayer. Generally, a higher amount of plasticizer loading will result in a lower T g In some embodiments, such as when the interlayer is an acoustic tri-layer, the inner core layer (i.e., soft layer) will have a glass transition temperature less than about 20°C, while the outer skin layers (e.g., hard layers) will have a glass transition temperature greater than about 25°C.

[0039] Considered plasticizers include, but are not limited to, polyacid esters, polyol esters, 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, hexyl cyclohexyl adipate, a mixture of heptyl and nonyl adipate, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and polymeric plasticizers such as oil modified sebacic acid alkyd resins, mixtures of phosphates and adipates, and mixtures and combinations thereof. 3-GEH is particularly preferred. Other examples of suitable plasticizers can include, but are not limited to, tetraethylene glycol di-(2-ethylhexanoate) (“4-GEH”), di(butoxyethyl) adipate and bis(2-(2-butoxyethoxy)ethyl) adipate, dioctyl sebacate, nonyl phenyl tetraethylene glycol, and mixtures thereof.

[0040] Other suitable plasticizers can include a blend of two or more different plasticizers, including but not limited to those described above. Other suitable plasticizers or blends of plasticizers can be formed from aromatic groups such as polyadipates, epoxides, phthalates, terephthalates, benzoates, toluates, mellitates, and other specialty plasticizers. Other examples include, but are not limited to, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-l,3-pentanediol dibenzoate, 2,2,4-trimethyl-l,3-pentanediol benzoate isobutyrate, 1,3-butanediol dibenzoate, diethylene glycol di-o-toluylate, triethylene glycol di-o-toluylate, dipropylene glycol di-o-toluylate, 1,2-octyl dibenzoate, tri-2-ethylhexyl mellitate, di-2-ethylhexyl terephthalate, bisphenol A bis(2-ethylhexanoate), ethoxylated nonyl phenol, and mixtures thereof. In some embodiments, the plasticizer can be selected from the group consisting of dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, and combinations thereof.

[0041] Generally, the plasticizer content of the polymeric interlayers of the present application is measured in parts per hundred resin (“phr”) on a weight / weight basis. For example, if 30 grams of plasticizer is added to 100 grams of polymeric resin, the plasticizer content of the resulting plasticized polymer is 30 phr. When the plasticizer content of a polymeric layer is given in the present application, the plasticizer content of a particular layer is determined with reference to the phr of plasticizer in the melt used to produce that particular layer. In some embodiments, the high stiffness interlayer includes a layer having a plasticizer content of less than about 35 phr and less than about 30 phr.

[0042] According to some embodiments of the application, one or more of the polymer layers described herein can have a total plasticizer content of one or more plasticizers of at least about 20 phr, at least about 25 phr, at least about 30 phr, at least about 35 phr, at least about 38 phr, at least about 40 phr, at least about 45 phr, at least about 50 phr, at least about 55 phr, at least about 60 phr, at least about 65 phr, at least about 67 phr, at least about 70 phr, at least about 75 phr, in some embodiments, the polymer layer can further comprise no more than about 100 phr, no more than about 85 phr, no more than about 80 phr, no more than about 75 phr, no more than about 70 phr, no more than about 65 phr, no more than about 60 phr, no more than about 55 phr, no more than about 50 phr, no more than about 45 phr, no more than about 40 phr, no more than about 38 phr, no more than about 35 phr, or no more than about 30 phr of one or more plasticizers. In some embodiments, the total plasticizer content of at least one polymer layer can be in the range of about 20 phr to about 40 phr, about 20 phr to about 38 phr, or about 25 phr to about 35 phr. In other embodiments, the total plasticizer content of at least one polymer layer can be in the range of about 38 phr to about 90 phr, about 40 phr to about 85 phr, or about 50 phr to 70 phr.

[0043] When the interlayer includes multiple layers, two or more of the polymer layers within the interlayer can have substantially the same plasticizer content and / or at least one polymer layer can have a different plasticizer content than one or more other polymer layers. When the interlayer includes two or more polymer layers having different plasticizer contents, the two layers can be adjacent to one another. In some embodiments, the difference in plasticizer content between adjacent polymer layers can be at least about 1 phr, at least about 2 phr, at least about 5 phr, at least about 7 phr, at least about 10 phr, at least about 20 phr, at least about 30 phr, at least about 35 phr, and / or no more than about 80 phr, no more than about 55 phr, no more than about 50 phr, or no more than about 45 phr, or in the range of about 1 phr to about 60 phr, about 10 phr to about 50 phr, or about 30 phr to 45 phr. When three or more layers are present in the interlayer, at least two of the polymer layers of the interlayer can have a plasticizer content similar to one another, e.g., within 10 phr, 5 phr, 2 phr, or 1 phr of one another, while at least two of the polymer layers can have a plasticizer content different from one another according to the ranges described above.

[0044] In some embodiments, one or more polymer layers or interlayers described herein can include a blend of two or more plasticizers, including, for example, two or more of the plasticizers listed above. When a polymer layer includes two or more plasticizers, the total plasticizer content of the polymer layer and the difference in total plasticizer content between adjacent polymer layers can fall within one or more of the ranges described above. When an interlayer is a multilayer interlayer, one or more of the polymer layers can include two or more plasticizers. In some embodiments, when an interlayer is a multilayer interlayer, at least one of the polymer layers including a plasticizer blend can have a higher glass transition temperature than the glass transition temperature of a conventional plasticized polymer layer. In some cases, this can provide additional stiffness to the layer, which can be used, for example, as an outer “skin” layer in a multilayer interlayer.

[0045] In addition to plasticizers, it is contemplated that adhesion control agents (“ACAs”) can also be added to the polymer resin to form the polymer interlayer. ACAs are generally used to alter and / or improve the adhesion of the interlayer to the glass panels when forming a laminated panel. Contemplated ACAs include, but are not limited to, magnesium / alkali carboxylates. In addition, contemplated ACAs can also include those disclosed in U.S. Patent 5,728,472, such as residual sodium acetate, potassium acetate, and / or bis(2-ethylbutyrate) magnesium, which is incorporated herein by reference in its entirety.

[0046] Other additives can be incorporated into the interlayer to enhance its performance in the final product and to impart certain additional properties to the interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers (e.g., ultraviolet light stabilizers), antioxidants, anti-blocking agents, flame retardants, IR absorbing or blocking agents (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, adhesion agents, primers, reinforcing additives and fillers, and other additives known to those of ordinary skill in the art.

[0047] One parameter used to describe the polymeric resin components of the polymeric interlayers of the present application is residual hydroxyl content (as vinyl hydroxyl content or poly(vinyl alcohol) (“PVOH”) content). Residual hydroxyl content refers to the amount of hydroxyl groups remaining on the polymer chain as pendant groups after processing is complete. For example, PVB can be manufactured by hydrolyzing poly(vinyl acetate) to poly(vinyl alcohol), and then reacting the poly(vinyl alcohol) with butyraldehyde to form PVB. During the process of hydrolyzing poly(vinyl acetate), not all of the acetate pendant groups are typically converted to hydroxyl groups. Additionally, the reaction with butyraldehyde does not typically result in the conversion of all of the hydroxyl groups to acetal groups. Thus, in any finished PVB, there will typically be both residual acetate groups (e.g., vinyl acetate groups) and residual hydroxyl groups (e.g., vinyl hydroxyl groups) present on the polymer chain as pendant groups. Generally, the residual hydroxyl content of a polymer can be adjusted by controlling the reaction time and reactant concentrations, as well as other variables in the polymer manufacturing process. When used as a parameter herein, residual hydroxyl content is measured as a weight % according to ASTM D-1396.

[0048] In various embodiments, the polyvinyl butyral resin comprises about 8 to about 35 weight % (wt. %) residual hydroxyls calculated as PVOH, about 13 to about 30 wt. % residual hydroxyls calculated as PVOH, about 8 to about 22 wt. % residual hydroxyls calculated as PVOH, or about 15 to about 22 wt. % residual hydroxyls calculated as PVOH; and for some high stiffness interlayers disclosed herein, for one or more layers, the polyvinyl butyral resin comprises greater than about 19 wt. % residual hydroxyls calculated as PVOH, greater than about 20 wt. % residual hydroxyls calculated as PVOH, greater than about 20.4 wt. % residual hydroxyls calculated as PVOH, and greater than about 21 wt. % residual hydroxyls calculated as PVOH.

[0049] In some embodiments, the polyvinyl butyral resin in at least one polymer layer for the interlayer can include a polyvinyl butyral resin having a residual hydroxyl content as measured as described above of at least about 18 wt. %, at least about 18.5 wt. %, at least about 18.7 wt. %, at least about 19 wt. %, at least about 19.5 wt. %, at least about 20 wt. %, at least about 20.5 wt. %, at least about 21 wt. %, at least about 21.5 wt. %, at least about 22 wt. %, at least about 22.5 wt. %, and / or no more than about 30 wt. %, no more than about 29 wt. %, no more than about 28 wt. %, no more than about 27 wt. %, no more than about 26 wt. %, no more than about 25 wt. %, no more than about 24 wt. %, no more than about 23 wt. %, or no more than about 22 wt. %.

[0050] Additionally, one or more of the other polymeric layers in the interlayer described herein can include another polyvinyl butylal resin having a lower residual hydroxyl content. For example, in some embodiments, at least one polymeric layer of the interlayer can include a polyvinyl butylal 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 no more than about 16 wt%, no more than about 15 wt%, no more than about 14 wt%, no more than about 13.5 wt%, no more than about 13 wt%, no more than about 12 wt%, or no more than about 11.5 wt%, as measured above.

[0051] When the interlayer includes two or more polymeric layers, the layers can include polyvinyl butylal resins having substantially the same residual hydroxyl content, or the residual hydroxyl content of the polyvinyl butylal resins in each layer can differ from one another. When two or more layers include polyvinyl butylal resins having substantially the same residual hydroxyl content, the difference between the residual hydroxyl content of the polyvinyl butylal resins in each layer can be less than about 2 wt%, less than about 1 wt%, or less than about 0.5 wt%. As used herein, the terms “wt% different” and “a difference of at least… wt% between” refer to the difference between two given wt% values, calculated by subtracting one value from the other. For example, a polyvinyl butylal resin having a residual hydroxyl content of 12 wt% differs by 2 wt% from a polyvinyl butylal resin having a residual hydroxyl content of 14 wt% (14 wt% - 12 wt% = 2 wt%). As used herein, the term “different” can refer to a value that is higher or lower than another value. Unless otherwise specified, all “differences” herein refer to the numerical value of the difference, not the specific sign of the value due to the order in which the numbers are subtracted. Thus, unless otherwise specified, all “differences” herein refer to the absolute value of the difference between two numbers.

[0052] When two or more layers include polyvinyl butylal resins having different residual hydroxyl contents, the difference between the residual hydroxyl content of the polyvinyl butylal resins can 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%, at least about 15 wt%, as measured above.

[0053] The resin can also include less than 35 wt% residual ester groups, 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% residual ester groups (calculated as polyvinyl ester (e.g., acetate)) with the balance being acetal, preferably butyral, but optionally including small amounts of other acetal groups, such as 2-ethylhexylal groups (see, e.g., U.S. Patent No. 5,137,954, the entire disclosure of which is incorporated herein by reference). The residual acetate content of the resin can also be determined according to ASTM D-1396.

[0054] In some embodiments, as described above, one or more polymer layers of the interlayer can be formed from a polyvinyl acetal resin. Such poly(vinyl acetal) resins can have a residual acetate content of at least about 1 wt%, at least about 3 wt%, at least about 5 wt%, at least about 7 wt%, and / or no more than about 15 wt%, no more than about 12 wt%, no more than about 10 wt%, no more than about 8 wt%, as measured as described above. When the interlayer includes a multilayer interlayer, two or more of the polymer layers can include resins having substantially the same residual acetate content, or one or more of the resins in different layers can have substantially different acetate contents. When the residual acetate contents of two or more resins are substantially the same, the difference in residual acetate content can be, for example, less than about 3 wt%, less than about 2 wt%, less than about 1 wt%, or less than about 0.5 wt%. In some embodiments, the difference in residual acetate content between two or more polyvinyl butyral resins in a multilayer interlayer can be at least about 3 wt%, at least about 5 wt%, at least about 8 wt%, at least about 15 wt%, at least about 20 wt%, or at least about 30 wt%. When such resins are used in a multilayer interlayer, the resins having different residual acetate contents can be located in adjacent polymer layers. When the multilayer interlayer is a three-layer interlayer (which includes a pair of outer “skin” layers that surround or sandwich an inner “core” layer), for example, the core layer can include a resin having a higher or lower residual acetate content. At the same time, the residual hydroxyl content of the resin in the inner core layer can have a higher or lower residual hydroxyl content than the outer skin layers and fall within one or more of the ranges provided earlier.

[0055] Poly(vinyl acetal) resins with higher or lower residual hydroxyl content and / or residual acetate content can also ultimately include different amounts of plasticizer when combined with at least one plasticizer. Thus, layers or domains formed from first and second polyvinyl acetal resins having different compositions can also have different properties within a single polymer layer or interlayer. Notably, for a given type of plasticizer, plasticizer compatibility in a polymer is largely dependent on the hydroxyl content of the polymer. Polymers with greater residual hydroxyl content are generally associated with decreased plasticizer compatibility or capacity. Conversely, polymers with lower residual hydroxyl content will generally result in increased plasticizer compatibility or capacity. Thus, poly(vinyl acetal) resins with higher residual hydroxyl content tend to have lower plasticizability and exhibit higher stiffness compared to similar resins with lower residual hydroxyl content. Conversely, poly(vinyl acetal) resins with lower residual hydroxyl content can tend to incorporate higher amounts of plasticizer when plasticized with a given plasticizer, which can result in softer polymer layers that exhibit lower glass transition temperatures than similar resins with higher residual hydroxyl content. These trends can be reversed depending on the specific resin and plasticizer.

[0056] When two poly(vinyl acetal) resins with different levels of residual hydroxyl content are blended with a plasticizer, the plasticizer can partition between the polymer layers or domains such that more plasticizer can be present in the layer or domain with lower residual hydroxyl content and less plasticizer can be present in the layer or domain with higher residual hydroxyl content. Ultimately, an equilibrium state is reached between the two resins. Generally, this correlation between residual hydroxyl content of a polymer and plasticizer compatibility / capacity can be manipulated and utilized to allow for the addition of appropriate amounts of plasticizer to a polymer resin and to stably maintain differences in plasticizer content within a multi-layer interlayer. This correlation also aids in stably maintaining differences in plasticizer content between two or more resins when the plasticizer would otherwise migrate between resins.

[0057] The glass transition temperature of one or more polymer layers, when measured alone or as part of a multi-layered interlayer, can differ as a result of migration of the plasticizer within the interlayer as a plasticizer. In some embodiments, the interlayer can include at least one polymer layer having a glass transition temperature outside of the interlayer of at least about 33 °C, at least about 34 °C, at least about 35 °C, at least about 36 °C, at least about 37 °C, at least about 38 °C, at least about 39 °C, at least about 40 °C, at least about 41 °C, at least about 42 °C, at least about 43, at least about 44 °C, at least about 45 °C, or at least about 46 °C. In some embodiments, the same layer can have a glass transition temperature within the polymer layer of at least about 34 °C, at least about 35 °C, at least about 36 °C, at least about 37 °C, at least about 38 °C, at least about 39 °C, at least about 40 °C, at least about 41 °C, at least about 42 °C, at least about 43 °C, at least about 44 °C, at least about 45 °C, at least about 46 °C, or at least about 47 °C.

[0058] In the same or other embodiments, at least one other polymer layer of a multi-layered interlayer can have a glass transition temperature of less than 30 °C, and can for example have a glass transition temperature of no more than about 25 °C, no more than about 20 °C, no more than about 15 °C, no more than about 10 °C, no more than about 9 °C, no more than about 8 °C, no more than about 7 °C, no more than about 6 °C, no more than about 5 °C, no more than about 4 °C, no more than about 3 °C, no more than about 2 °C, no more than about 1 °C, no more than about 0 °C, no more than about -1 °C, no more than about -2 °C, or no more than about -5 °C, when measured when the interlayer is not part of an interlayer. The same polymer layer can have a glass transition temperature of no more than about 25 °C, no more than about 20 °C, no more than about 15 °C, no more than about 10 °C, no more than about 9 °C, no more than about 8 °C, no more than about 7 °C, no more than about 6 °C, no more than about 5 °C, no more than about 4 °C, no more than about 3 °C, no more than about 2 °C, no more than about 1 °C, or no more than about 0 °C, when measured outside of the interlayer.

[0059] According to some embodiments, the difference between the glass transition temperatures of two polymer layers, typically adjacent polymer layers within an interlayer, 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, while in other embodiments the glass transition temperatures of two or more polymer layers can differ from each other by about 5 °C, about 3 °C, about 2 °C, or about 1 °C. Typically, a lower glass transition temperature layer has a lower stiffness than a higher glass transition temperature layer in an interlayer, and can be positioned between higher glass transition temperature polymer layers in a final interlayer construction.

[0060] 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, a central soft layer is sandwiched between two hard / rigid outer layers. This (hard) / / (soft) / / (hard) configuration produces a multilayer sandwich that is easy to handle, can be used in conventional lamination methods, and can be composed of relatively thin and lightweight 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 more of any range disclosed), a higher plasticizer content (e.g., greater than or equal to about 48 phr or greater than or equal to about 70 phr, or more of any range disclosed), and / or a lower glass transition temperature (e.g., less than 30°C or less than 10°C, or more of any range disclosed).

[0061] 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 method 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, doctor blade, paddle, air knife, printing, powder coating, spraying, or other methods known to those skilled in the art. While all methods known to those skilled in the art for producing polymer sandwich sheets are contemplated as methods for producing the polymer sandwich sheets described herein, this application will focus on polymer sandwich sheets produced by extrusion and / or co-extrusion methods. The final multilayer glass panel laminate of this disclosure is formed using methods known in the art.

[0062] During extrusion, thermoplastic resins and plasticizers (including any of the resins and plasticizers mentioned above) are typically premixed and fed into the extruder unit. Additives such as colorants and UV inhibitors (in liquid, powder, or granular form) can be used and can be mixed into the thermoplastic resin or plasticizer before reaching the extruder unit. These additives are incorporated into the thermoplastic polymer resin and, by extension, 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.

[0063] In an extruder unit, particles of thermoplastic raw materials and plasticizers (including any of the aforementioned resins, plasticizers, and other additives) are further mixed and melted to produce a melt with a substantially homogeneous temperature and composition. Embodiments of the invention provide a melt temperature of approximately 200°C. Once the melt reaches the end of the extruder unit, it is forced into an 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 much larger in one dimension than in the vertical dimension. Typically, the die is designed so that the cylindrical profile of the melt exiting the die flows uniformly into the final profile shape of the product. As long as a continuous profile exists, the die can impart a variety of shapes to the final polymer sandwich sheet. Generally, in its most basic sense, extrusion is a process used to create an object with a fixed cross-sectional profile. This is achieved by pushing or pulling material through a die with the desired cross-section of the final product.

[0064] In some embodiments, a co-extrusion method can be utilized. 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 stable volumetric quantities of different thermoplastic melts with different viscosities or other properties through a co-extrusion die to achieve the desired final form. For example, the multilayer sandwich of the present invention (e.g., in the form of a three-layer sandwich) 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. The co-extrusion apparatus can be operated by simultaneously extruding polymer melt from each manifold through the die and extrusion opening, wherein the multilayer sandwich is extruded as a composite material of three separate polymer layers. The polymer melt can flow through the die such that a core layer is positioned between the surface layers to result in the manufacture of a three-layer sandwich, wherein the core layer is sandwiched between the surface layers. The die opening may include a pair of lips positioned on either side of the opening. Given the positional orientation of the polymer melt, the surface layers may contact the lips. In any case, the sandwich thickness can be varied by adjusting the distance between the die lips located at the die opening.

[0065] The thickness of the multiple polymer layers exiting the extrusion die during co-extrusion is typically controlled by adjusting the relative speed of the melt through the extrusion die and the dimensions of the melt through the individual die lips. 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 can be in the range of about 13 mils to about 75 mils, about 25 mils to about 70 mils, or about 30 mils to about 60 mils. When the interlayer comprises two or more polymer layers, the thickness of each layer may be at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 7 mils, at least about 8 mils, at least about 9 mils, at least about 10 mils, and / or no more than about 50 mils, no more than about 40 mils, no more than about 30 mils, no more than about 20 mils, no more than about 17 mils, no more than about 15 mils, no more than about 13 mils, no more than about 12 mils, no more than about 10 mils, and 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.

[0066] In some embodiments where the interlayer comprises at least three polymer layers, one or more of the inner layers may be relatively thin compared to the other outer layers. For example, in some embodiments where the multilayer interlayer is a three-layer interlayer, the innermost layer may have a thickness of no more than about 12 mils, no more than about 10 mils, no more than about 9 mils, no more than about 8 mils, no more than about 7 mils, no more than about 6 mils, or no more than about 5 mils, or it may have a thickness in the range of about 2 mils to about 12 mils, no more than about 3 mils to about 10 mils, or no more than about 4 mils to about 9 mils. In the same or other embodiments, the thickness of each outer layer may be at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 7 mils and / or no more than about 15 mils, no more than about 13 mils, no more than about 12 mils, no more than about 10 mils, no more than about 9 mils, or no more than about 8 mils, or may be in the range of about 2 to about 15 mils, about 3 to about 13 mils, or about 4 to about 10 mils. When the interlayer comprises two outer layers, the combined thickness of these layers may be at least about 9 mils, at least about 13 mils, at least about 15 mils, at least about 16 mils, at least about 18 mils, at least about 20 mils, at least about 23 mils, at least about 25 mils, at least about 26 mils, at least about 28 mils, or at least about 30 mils, and / or not more than about 73 mils, not more than about 60 mils, not more than about 50 mils, not more than about 45 mils, not more than about 40 mils, not more than about 35 mils, or in the range of about 9 mils to about 70 mils, about 13 mils to about 40 mils, or about 25 mils to about 35 mils.

[0067] According to some implementation schemes, 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 a pair of outer layers, the thickness ratio of one of the outer layers to the core layer can fall within one or more of the above ranges. In some implementations, the ratio of the combined thickness of the outer layer to the inner layer may be at least about 2.25:1, at least about 2.4:1, at least about 2.5:1, at least about 2.8:1, at least about 3:1, at least about 3.5:1, at least about 4:1, at least about 4.5:1, at least about 5:1, at least about 5.5:1, at least about 6:1, at least about 6.5:1, or at least about 7:1 and / or no more than about 30:1, no more than about 20:1, no more than about 15:1, no more than about 10:1, no more than about 9:1, or no more than about 8:1.

[0068] The multilayer sandwich as described herein may comprise 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 thickness distribution that varies 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 of the individual resin layers may comprise at least one conical region. Conical sandwiches may be particularly useful in head-up display (HUD) panels, for example, in automotive and aircraft applications.

[0069] Therefore, in any of the foregoing embodiments, the sheet cut in step a) and the sheet cut in step e) may contain polyvinyl butyral with a thickness of about 0.1 mm to 1.0 mm.

[0070] In any of the foregoing embodiments, the sheet cut in step a) and the sheet cut in step e) comprise polyvinyl butyral having a thickness of 0.2 mm to 0.8 mm.

[0071] According to the present invention, L-shaped parts can be joined to form a rectangular frame defining a rectangular opening. Various methods can be used to join the materials together. Methods for joining L-shaped parts include thermal welding, solvent welding, etc. They can also be joined by fitting the shapes of the individual parts together, so that they can be held together by friction.

[0072] According to the invention, a rectangular frame can then be placed around the functional material to obtain a framed functional sheet. This can also be described as placing the functional material within a rectangular frame or within a rectangular opening defined by the frame.

[0073] According to the present invention, a frame-type functional sheet can be covered with cut sheets to form a functional sandwich stack. According to the present invention, the cut sheet in step e) can be the same sheet as the cut sheet in step a) or a different sheet. Therefore, the cut sheet in step e) can be the same sheet as the cut sheet in step a), or alternatively, the cut sheet in step e) can be a different sheet than the cut sheet in step a).

[0074] In any of the foregoing embodiments, the invention may further include covering the frame-type switchable sheet with another cut sheet located on the side opposite to the cut sheet of step e). In this respect, the cut sheet may serve as both the top and bottom layer of the frame-type switchable sheet.

[0075] In any of the foregoing embodiments, the invention may further include placing a rigid substrate on either side of a switchable sandwich stack to form a switchable laminate. A variety of rigid substrates can be used, particularly glass. Other rigid substrates may include polycarbonate, ethylene vinyl alcohol, and other thermoplastic polymers, including thermoplastic ionomers.

[0076] Unless otherwise stated, all figures used in the specification and claims to indicate quantities of components, properties (such as molecular weight, reaction conditions, etc.) should be understood to be modified by the term "about" in all cases. Unless otherwise indicated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​and may vary according to the desired properties sought to be obtained according to the invention. At a minimum, each numerical parameter should be interpreted based on the reported significant figures and by applying ordinary rounding techniques. Furthermore, the ranges defined in this disclosure and claims are intended to specifically include the entire range, and not just one or more endpoints. For example, a range specified as 0 to 10 is intended to disclose all integers between 0 and 10 (such as, for example, 1, 2, 3, 4, etc.), all fractions between 0 and 10 (such as 1.5, 2.3, 4.57, 6.1113, etc.), and the endpoints 0 and 10. Furthermore, ranges related to chemical substituents, such as "C1 to C5 diols," are intended to specifically include and disclose C1, C2, C3, C4, and C5 diols.

[0077] Although the numerical ranges and parameters stated in relation to the broad scope of the invention are approximate, the values ​​stated in particular embodiments are reported as accurately as possible. However, any numerical value inherently includes some error that must be caused by the standard deviation found in their respective test measurements.

[0078] As used in this specification and the appended claims, unless otherwise expressly indicated, the singular forms “a” and “the” include a plurality of their indicators. For example, references to “polyester,” “dicarboxylic acid,” “residue” are synonymous with “at least one” or “one or more” polyesters, dicarboxylic acids, or residues, and are therefore intended to refer to a single or multiple polyesters, dicarboxylic acids, or residues. Furthermore, references to a composition “comprising,” “containing,” “having,” or “including” “a” component or “a” polyester are intended to also include other components or other polyesters besides the specifically identified component or residue. Thus, the terms “containing,” “having,” or “including” are intended to be synonymous and can be used interchangeably with the term “comprising,” meaning that at least the stated compound, element, particle, or method step, etc., is present in the composition or article or method, but does not exclude the presence of other compounds, catalysts, materials, particles, method steps, etc., even if other such compounds, materials, particles, method steps, etc., have the same function as those specified, unless expressly excluded in the claims.

[0079] Furthermore, it should be understood that mentioning one or more method steps does not preclude the presence of additional method steps before or after the combined steps, or the insertion of method steps between those explicitly identified steps. Additionally, the letters used for method steps or ingredients are a convenient means of identifying discrete activities or ingredients, and the letters may be arranged in any order unless otherwise specified.

[0080] Although the compositions of the present invention have been described in detail above with respect to two exemplary embodiments having two end uses, those skilled in the art will understand that the compositions of the present invention can be used in a wide variety of end-use applications.

[0081] The following embodiments illustrate suitable and / or preferred methods and results according to the invention. However, it should be understood that these embodiments are provided by way of illustration, and nothing herein should be considered as a limitation on the overall scope of the invention. Unless otherwise stated, all percentages are by weight.

[0082] Example Predictive Example 1 In this proposed embodiment, the sandwich frame is formed from two L-shaped segments cut from an oversized PVB sheet (see...). Figure 2 The two L-shaped segments are then welded or brazed together to form a single sandwich frame, while the middle section of the oversized PVB sheet can be recycled and used as the top layer to laminate the switchable film onto the glass. The method of constructing the sandwich frame from L-shaped segments and reducing waste to an absolute minimum is not obvious to those skilled in the art, as it represents a unique approach that has not been considered or practiced to date.

[0083] Predictive Example 2 In this proposed embodiment, the sandwich frame is formed from two L-shaped segments cut from an oversized PVB sheet (see...). Figure 2 The two L-shaped segments are then fitted together to form a single sandwich frame (which connects the individual pieces together during lamination), while the middle section of the oversized PVB sheet is recycled and used as the top layer to laminate the switchable film onto the glass. The method of constructing the sandwich frame from L-shaped segments and reducing waste to an absolute minimum is not obvious to those skilled in the art, as it represents a unique approach that has not been considered or practiced to date.

Claims

1. A method of constructing a functional interlayer stack, the method comprising: a) cutting two L-shaped pieces from a corner of a bulk sheet of interlayer material, leaving a cut sheet; b) optionally trimming one or more of the two L-shaped pieces or the cut sheet; c) joining the L-shaped pieces to form a rectangular frame defining a rectangular opening; d) placing the rectangular frame around a functional material to obtain a framed functional sheet; and e) covering the framed functional sheet with a cut sheet to form a functional interlayer stack, wherein the cut sheet of step e) is the same sheet as the cut sheet of step a) or a different sheet.

2. The method of claim 1, wherein the functional material comprises one or more of a photopolymer material, a conductive material, a solar reflective material, a polymer dispersed liquid crystal material, a suspended particle material, an electrochromic material, a photochromic material, or an electrochromic / photoc hro mic material.

3. The method of claim 1, wherein the cut sheet of step e) is the same sheet as the cut sheet of step a).

4. The method of claim 1, wherein the cut sheet of step e) is a different sheet than the cut sheet of step a).

5. The method of any of the preceding claims, wherein the interlayer material is a viscoelastic polymer.

6. The method of any of the preceding claims, wherein the viscoelastic polymer comprises one or more of polyvinyl acetal, thermoplastic polyurethane, or ethylene vinyl acetate.

7. The method of any of the preceding claims, wherein the cut sheet of step a) and the cut sheet of step e) comprise polyvinyl butyral having a thickness of about 0.1 mm to 1.0 mm.

8. The method of any of the preceding claims, wherein the cut sheet of step a) and the cut sheet of step e) comprise polyvinyl butyral having a thickness of about 0.2 mm to 0.8 mm.

9. The method of any of the preceding claims, further comprising covering the framed switchable sheet on a side opposite the cut sheet of step e) with another cut sheet.

10. The method of any of the preceding claims, further comprising placing a rigid substrate on either side of the switchable interlayer stack to form a functional laminate.

11. The method of any of the preceding claims, wherein the joining of the L-shaped pieces is achieved by one or more of heat welding, solvent welding, or form-fitting the pieces together. ​

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