Fixtures and method for controlling bow in laminate structures

Abstract

A method for forming a laminate structure is disclosed. The method comprises positioning a prelamination on a fixture. The prelamination comprises first and second layers having first and second coefficients of thermal expansion (CTE), respectively, with the second CTE being greater than the first CTE. The prelamination comprises a polymer interlayer disposed between the first and second layers. The method further comprises inducing a target counter bow in a major surface of the prelamination via the fixture. The fixture is configured to orient a reference plane of the prelamination transversely with respect to gravity to induce the target counter bow. The method further comprises laminating the prelamination on the fixture while inducing the target counter bow to form the laminate structure. The target counter bow is configured to reduce a reference bow in the major surface that would result if the prelamination was laminated without the target counter bow.

Description

SP25-091FIXTURES AND METHOD FOR CONTROLLING BOW IN LAMINATE STRUCTURESCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 726114 filed on November 27, 2024, and U.S. Provisional Application Serial No. 63 / 813101 filed on May 28, 2025, the content of which is relied upon and incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure generally relates to laminate structures comprising dissimilar substrates. In particular, the present disclosure relates to fixtures and methods for controlling bow in laminate structures having outer substrates of material with different coefficients of thermal expansion.BACKGROUND

[0003] Laminate structures may be used for a wide range of applications in a variety of industries. For example, laminate structures may be used in architectural applications such as siding, decorative panels, cabinet installations, wall coverings, and the like. Laminate structures may also be used for furniture items and / or household appliances. For instance, laminate structures may be incorporated as outer panels for a cabinet, furniture item, and / or household appliance.

[0004] Automotive, transportation, aviation, and architectural windows are often made from laminate structures comprising two glass sheets of similar thickness and composition. However, for various applications it may be desirable to provide laminate structures comprising dissimilar substrates, e.g., substrates of different composition and / or thickness. For instance, metal-glass laminates, plastic-glass laminates, glass-ceramic laminates, and other similar laminates may be desirable for aesthetic or structural qualities.

[0005] In addition, glass-glass laminates comprising dissimilar glass substrates may also be desirable for various applications, for example, laminates comprising glasses having different compositions, thicknesses, and / or other properties such as coefficient of thermal expansion (CTE). By way of a non-limiting example, a thin sheet of ion-exchanged glass may be laminated on a thicker soda lime glass sheet to provide enhanced damage resistance.SP25-091Electrochromic windows and mirrors may comprise a thin, alkali-free glass substrate upon which an electrically active thin fdm is deposited, which may be laminated to a thicker soda lime glass substrate for enhanced structural rigidity.SUMMARY

[0006] The following summary is a brief description of certain aspects of the present disclosure. The summary should not be considered as limiting of the breadth, scope, or applicability of the present disclosure.

[0007] According to aspect (1), a method for forming a laminate structure is provided. The method comprises: positioning a prelamination on a fixture, the prelamination comprising a first layer having a first coefficient of thermal expansion (CTE), a second layer having a second CTE that is greater than the first CTE, and a polymer interlayer disposed between and bonding the first layer and the second layer with a first bond strength; inducing a target counter bow in a second major surface of the prelamination via the fixture, the fixture configured to orient a reference plane of the prelamination transversely with respect to the direction of gravity to induce the target counter bow, the reference plane corresponding to the second major surface in a flat state with the prelamination remaining positioned on the fixture; and laminating the prelamination on the fixture while inducing the target counter bow to form the laminate structure, wherein the laminating comprises heating the prelamination to a lamination temperature configured to increase the first bond strength of the polymer interlayer to a second bond strength, wherein the target counter bow is configured to reduce or eliminate a reference bow in the second major surface that would result if the pre lamination was laminated without the target counter bow.

[0008] According to aspect (2), the method of aspect (1) is provided, wherein the reference plane forms an angle of from about 1° to about 45° with the direction of gravity.

[0009] According to aspect (3), the method of aspect (1) is provided, wherein the reference plane forms an angle of from about 1° to about 35° with the direction of gravity.

[0010] According to aspect (4), the method of aspect (1) is provided, wherein the reference plane forms an angle of from about 5° to about 25° with the direction of gravity.

[0011] According to aspect (5), the method of any one of the preceding aspects is provided, wherein the second layer defines the second major surface of the prelamination, and whereinSP25-091 the first layer defines a first major surface of the prelamination opposite the second major surface.

[0012] According to aspect (6), the method of any one of the preceding aspects is provided, wherein: the prelamination has a thickness defined as a distance between the second major surface and a first major surface opposite the second major surface, a width defined as a first dimension of one of the first or second major surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second major surfaces orthogonal to both the thickness and the width, the length is greater than the width and extends between a first end and a second end of the prelamination, and the prelamination is positioned on the fixture in a portrait orientation such that the length is vertically aligned relative to the width.

[0013] According to aspect (7), the method of aspect (6) is provided, wherein the fixture comprises a plurality of support regions configured to contact the second major surface of the prelamination at different positions along the length.

[0014] According to aspect (8), the method of aspect (7) is provided, wherein the support regions are spaced apart from one another along the length of the prelamination.

[0015] According to aspect (9), the method of any one of aspects (7) to (8) is provided, wherein the support regions comprise a first support region proximate the first end of the prelamination and a second support region proximate the second end of the prelamination, the first and second support regions contacting the second major surface during the laminating.

[0016] According to aspect (10), the method of any one of aspects (7) to (9) is provided, wherein the support regions comprise a third support region proximate a middle region of the prelamination disposed between the first end and the second end.

[0017] According to aspect (11), the method of aspect (10) is provided, wherein the third support region is spaced from the pre lamination during the laminating.

[0018] According to aspect (12), the method of aspect (11) is provided, wherein the third support region has a clearance defined as a minimum distance between the reference plane and the third support region, the clearance following the equation: clearance = L2x CF, where L is the length of the prelamination in meters (m) and CF is a clearance factor in a range of from about 2 mm / m2to about 8 mm / m2.

[0019] According to aspect (13), the method of any one of aspects (7) to (12) is provided, wherein each support region has a horizontal offset from at least one other support region whenSP25-091 viewed in a longitudinal section plane parallel to the length and the thickness of the prelamination and passing through the support regions of the fixture.

[0020] According to aspect (14), the method of any one of aspects (7) to (13) is provided, wherein at least one support region is configured to contact the second major surface along an entirety of the width of the prelamination.

[0021] According to aspect (15), the method of aspect (14) is provided, wherein the at least one support region has a surface that extends linearly across the second major surface along the entirety of the width of the prelamination.

[0022] According to aspect (16), the method of any one of the preceding aspects is provided, wherein: the target counter bow comprises a target offset of the second major surface in a first direction from the reference plane, the reference bow comprises a reference offset of the second major surface from the reference plane in a second direction opposite the first direction, and wherein the target offset is within ± 25% of the reference offset.

[0023] According to aspect (17), the method of aspect (16) is provided, wherein the target offset is greater than or equal to the reference offset.

[0024] According to aspect (18), the method of any one of the preceding aspects is provided, wherein the laminating comprises cooling the heated prelamination to a setting temperature below which the polymer interlayer is configured to transfer shear forces between the first layer and the second layer.

[0025] According to aspect (19), the method of any one of the preceding aspects is provided, wherein positioning the prelamination on the fixture comprises positioning a plurality of further prelaminations on the fixture, each further prelamination configured to be substantially identical to the prelamination.

[0026] According to aspect (20), the method of any one of the preceding aspects is provided, wherein one or more of: the first layer is a first glass layer, and the second layer is a second glass layer, and the first layer has a first thickness, and the second layer has a second thickness that is greater than the first thickness.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various exemplary embodiments of the present disclosure are described in detail below with reference to the following drawings. The drawings are provided for purposes ofSP25-091 illustration only and merely depict exemplary embodiments of the present disclosure to facilitate the understanding of the present disclosure. Therefore, the drawings should not be considered as limiting of the breadth, scope, or applicability of the present disclosure. It should be noted that for clarity and ease of illustration these drawings are not necessarily drawn to scale.

[0028] FIG. 1 is a schematic cross-sectional view of a laminate structure that comprises dissimilar substrates;

[0029] FIG. 2 schematically depicts differential expansion of a stack of dissimilar substrates, such as the substrates used to form the laminate structure of FIG. 1, during a heating step under typical lamination;

[0030] FIG. 3 schematically depicts differential contraction of the dissimilar substrates of the stack of FIG. 2 and the resulting bow that can occur in the laminate structure during a cooling step under typical lamination;

[0031] FIG. 4 is a flow chart of a method for forming a laminate structure with reduced or eliminated bow according to embodiments of the present disclosure;

[0032] FIG. 5 is a perspective view of a first fixture and two prelaminations configured to be positioned and oriented by the first fixture to induce a target counter bow in a major surface of each prelamination according to aspects of the method of FIG. 4;

[0033] FIG. 6 is a section view along a longitudinal section plane passing through the first fixture and prelaminations of FIG. 5;

[0034] FIG. 7 is a duplicate of the section view of FIG. 6 except one prelamination is omitted and the other prelamination is replaced with schematic representations of the major surface thereof in different positions;

[0035] FIG. 8 is an enlarged detail view of a middle region of the prelamination showing aspects of the target counter bow induced in the second major surface of the prelamination;

[0036] FIG. 9 is a substantial duplicate of the section view of FIG. 6 except the first fixture is replaced with a second fixture configured to induce a target counter bow in a major surface of each prelamination;

[0037] FIG. 10 is a duplicate of the section view of FIG. 9 except one prelamination is omitted and the other prelamination is replaced with schematic representations of the major surface thereof in different positions;SP25-091

[0038] FIG. 11 is a duplicate of the section view of FIG. 10 except the schematic representations of the major surface are omitted and a horizontal spacing is shown between adjacent support regions of the second fixture;

[0039] FIG. 12 and FIG. 13 are schematic depictions of a third fixture supporting one prelamination (FIG. 12) or a plurality of prelaminations (FIG. 13), respectively;

[0040] FIG. 14 is a schematic depiction of a fourth fixture configured to contact a substantial portion of the second major surface of the pre lamination to induce the target counter bow therein;

[0041] FIG. 15 is a graph that illustrates the relationship between part size and long edge bow;

[0042] FIGS. 16-20 graphically depict the results of a bow simulation using different tilt angles to induce the target counter bow according to Example 1 ; and

[0043] FIG. 21 shows dimensions of a prototype fixture that was fabricated, the prototype fixture corresponding to the first fixture of FIG. 5.DETAILED DESCRIPTION

[0044] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles disclosed herein as would normally occur to one skilled in the art to which this disclosure pertains.

[0045] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0046] In this document, relational terms, such as first and second, top and bottom, and the like, are used solely to distinguish one entity or action from another entity or action, withoutSP25-091 necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0047] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to. Whether or not a numerical value or end-point of a range in the specification recites “about,” the numerical value or end-point of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the end-points of each of the ranges are significant both in relation to the other end-point, and independently of the other end-point.

[0048] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range was explicitly recited. As an illustration, a numerical range of “about 1 to about 5” should be interpreted to include not only the explicitly recited values of about 1 to about 5, but also to include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4, the sub ranges such as from 1-3, from 2-4, from 3-5, etc., as well as 1, 2, 3, 4, and 5 individually. The same principle applies to ranges reciting only one numerical value as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described by the range.

[0049] The terms “substantial,” “substantially,” and variations thereof as used herein, unless defined elsewhere in association with specific terms or phrases, are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.SP25-091

[0050] Directional terms as used herein — for example up, down, right, left, front, back, top, bottom, above, below, and the like — are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0051] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, when a method claim does not recite an order to be followed by its steps, or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This requirement holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and / or the number or type of embodiments described in the specification.

[0052] As used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0053] Laminate structures comprising dissimilar substrates may be referred to herein as "asymmetric" laminates. While asymmetric laminates may present one or more advantages as compared to symmetric laminates, asymmetric laminates can also present various challenges. For example, asymmetric laminates can comprise two or more substrates with different CTEs. During the lamination process, the substrates can be heated to a lamination temperature and subsequently cooled, e.g., to room temperature. When the laminate structure cools, the CTE mismatch between the substrates can lead to out-of-plane deflection (often referred to as "bow"). Bow in laminate structures can interfere with subsequent processing steps (e.g., film deposition), can result in unwanted optical distortion in the final product, and / or can result in a product that is unsuitable for the intended application and / or does not meet the desired target shape. Bow is a measurable attribute that can be measured according to ASTM Cl 172.

[0054] FIGS. 1-3 schematically illustrate lamination techniques that can lead to bow in asymmetric laminates. FIG. 1 is a schematic cross-sectional view of a laminate structure 1 that comprises dissimilar substrates. The laminate structure 1 includes a first layer 2, a second layer 3, and an interlayer 4 disposed between the first layer 2 and the second layer 3. The first layer 2 can have a first thickness T1 and comprise a first material (e.g., a glass material) with a firstSP25-091CTE. The second layer 3 can have a second thickness T2 and comprise a second material (e.g., glass material) with a second CTE. The interlayer 4 can have a third thickness T3 and comprise a third material (e.g., a polymer material) with a third CTE. The substrates of the laminate structure 1 can be dissimilar in that the first CTE of the first material of the first layer 2 is different (e.g., substantially different) than the second CTE ofthe second material ofthe second layer 3. While the laminate structure 1 of FIG. 1 is schematically depicted having a substantially flat configuration (e.g., no perceivable bow along the sides / surfaces thereof), the actual (final) configuration of the laminate structure 1 depends on many factors, including the lamination techniques used to fabricate the laminate structure 1.

[0055] FIG. 2 schematically depicts the differential expansion of a stack of dissimilar substrates, such as the substrates used to form the laminate structure 1 of FIG. 1, during a heating step under typical lamination. As shown in FIG. 2, during fabrication, the polymer interlayer 4 is positioned between the first layer 2 and the second layer 3 to form an intermediate assembly or stack 10. The stack 10 is then heated to soften the polymer interlayer 4, and a force such as pressures P 1 and P2 may be applied to upper and lower sides 12 and 14, respectively, of stack 10 to pretreat stack 10. Various suitable pretreatment processes are known in the art. For example, air can be removed from the prelamination 10 using a variety of methods, including nip rollers, evacuated pouches, vacuum rings, a flatbed laminator, or platen type press laminators. The polymer interlayer 4 can be configured to (partially) bond the first layer 2 and the second glass layer 3 with a first bond strength after pretreatment. The partially bonded stack 10 may be hereinafter referred to as a prelamination.

[0056] Several hot press operations can be utilized during the fabrication process. For example, following pretreatment, the stack 10 can be further heated and additional pressure Pl and P2 can be applied in one or more additional hot press steps. Various suitable hot press processes are known in the art. During the hot press operation(s), the first layer 2 and the second layer 3 expand at different rates, as shown by the arrows El and E2 in FIG. 2, due to the different CTEs of the different layers. It will be understood that FIG. 2 is schematic in nature and the expansion indicated by arrows El and E2 is intended to be illustrative and non-limiting. At elevated temperatures (e.g., during the hot press operations), the material of polymer interlayer 4 is soft such that minimal shear force is transmitted through the polymer interlayer 4 between the first layer 2 and the second layer 3.

[0057] FIG. 3 schematically depicts the differential contraction of the dissimilar substrates of the stack 10 of FIG. 2 and the resulting bow that can occur (in the laminate structure) duringSP25-091 a cooling step under typical lamination. As shown in FIG. 3, following hot press operation(s), the stack 10 is allowed to cool. Due to the cooling and differences in CTE between the first and second materials of the first and second layers, respectively, the first layer 2 and the second layer 3 contract as shown by the arrows Cl and C2. As described with reference to FIG. 1, the second CTE of the second layer 3 can be greater than (e.g., significantly greater than) the first CTE of the first layer 2. Upon cooling, this CTE mismatch can result in greater contraction of the second layer 3 compared to the first layer 2, leading to the bowed laminate structure 15 shown in FIG. 3. The bowed laminate structure 15 has a convex surface 16 defined by the first layer 2 and a concave surface 17 defined by the second layer 3. As the polymer interlayer 4 cools (e.g., to a setting temperature of the polymer material), shear forces are transferred between the first layer 2 and the second layer 3, leading to the bowed shape of the bowed laminate structure 15. It will be understood that the curvature of the bowed laminate structure 15 shown in FIG. 3 is exaggerated, and the actual curvature of the bowed laminate structure 15 may be less than the amount depicted in FIG. 3.

[0058] FIG. 4 is a flow chart of a method 100 for forming a laminate structure 1 with reduced or eliminated bow according to embodiments of the present disclosure. In embodiments, as disclosed herein, the reduction or elimination of the bow can be along at least one dimension (e.g., a length (height), a width, or both the length and the width) of the laminate structure 1. The method 100 is described with reference to FIGS. 5-14, which illustrate various fixtures 300 that can be used to implement the method 100 according to embodiments of the present disclosure. The reference number 300 is used to refer generally to all fixtures disclosed herein whereas the reference number 300 with letters a, b, c, and so on appended thereto may be used to denote specific embodiments of the fixture, such as a first fixture 300a (FIGS. 5-8), a second fixture 300b (FIGS. 9-11), a third fixture 300c (FIG. 12 and FIG. 13), and a fourth fixture 300d (FIG. 14).

[0059] The method 100, in a step 102, comprises positioning a pre lamination on a fixture 300. In embodiments, the prelamination corresponds generally to the stack or prelamination 10 described with reference to FIG. 1 and FIG. 2 except as otherwise described hereinbelow. For example, the prelamination 10 used in the method 100 includes a first layer 2, a second layer 3, and an interlayer 4 disposed between the first layer 2 and the second layer 3. The first layer 2 has a first thickness T1 and comprises a first material (e.g., a glass material) with a first CTE (CTEi). The second layer 3 has a second thickness T2 and comprises a second material (e.g., glass material) with a second CTE (CTE2). The interlayer 4 has athird thicknessSP25-091T3 and comprises a third material (e.g., a polymer material) with a third CTE (CTE3). The polymer interlayer 4 is configured to (partially) bond the first layer 2 and the second layer 3 with a first bond strength after pretreatment. Various suitable pretreatment processes are known in the art. The fixture 300 and its various configurations are described later in the present disclosure.

[0060] In embodiments, the first thickness T1 of the first layer 2 is less than the second thickness T2 of the second layer 3. For example, the first layer 2 can be a thin glass layer with the first thickness T1 in a range of from about 0.1 mm to about 1.5 mm, from about 0. 1 mm to about 1.4 mm, from about 0.2 mm to about 1.5 mm, from about 0.1 mm to about 1.3 mm, from about 0.3 mm to about 1.5 mm, from about 0.1 mm to about 1.0 mm, from about 0.2 mm to about 1.0 mm, from about 0.3 mm to about 0.9 mm, from about 0.1 mm to about 0.8 mm, from about 0.4 mm to about 0.7 mm, from about 0.5 mm to about 1.2 mm, from about 0.6 mm to about 1.1 mm, from about 0.7 mm to about 1.0 mm, from about 1.0 mm to about 1.5 mm, or from about 1.1 mm to about 1.4 mm, and also comprising all sub-ranges and sub-values between these range endpoints.

[0061] The second layer 3 can be a thick glass layer with the second thickness T2 in a range of from about 2 mm to about 10 mm, from about 2 mm to about 9 mm, from about 3 mm to about 10 mm, from about 2 mm to about 8 mm, from about 4 mm to about 10 mm, from about 2 mm to about 7 mm, from about 5 mm to about 10 mm, from about 5 mm to about 9 mm, from about 6 mm to about 10 mm, from about 5 mm to about 8 mm, from about 7 mm to about 10 mm, from about 3 mm to about 8 mm, from about 4 mm to about 7 mm, from about 6 mm to about 9 mm, or from about 2 mm to about 6 mm, and also comprising all sub-ranges and subvalues between these range endpoints.

[0062] In embodiments, the third thickness T3 of the interlayer 4 (e.g., the polymer interlayer) can be between the first thickness T1 of the first layer 2 and the second thickness T2 of the second layer 3. In embodiments, the third thickness T3 is in a range of from about 0.3 mm to about 2.5 mm, from about 0.3 mm to about 2.4 mm, from about 0.4 mm to about 2.5 mm, from about 0.3 mm to about 2.3 mm, from about 0.5 mm to about 2.5 mm, from about 0.3 mm to about 1.4 mm, from about 0.4 mm to about 1.4 mm, from about 0.5 mm to about 1.3 mm, from about 0.6 mm to about 1.2 mm, from about 0.7 mm to about 1.1 mm, from about 1.4 mm to about 2.5 mm, from about 1.5 mm to about 2.4 mm, from about 1.6 mm to about 2.3 mm, from about 1.7 mm to about 2.2 mm, or from about 1.8 mm to about 2.1 mm, and also comprising all sub-ranges and sub-values between these range endpoints. It will be appreciatedSP25-091 that the present disclosure is not limited to specific thicknesses, and the thicknesses Tl, T2, and T3 may be larger or smaller than the examples noted above as required for a particular application.

[0063] In embodiments, the first material of the first layer 2 can comprise boro- aluminosilicate glass, such as alkaline earth boro-aluminosilicate glass, alkali-free boro- aluminosilicate glass, or other similar glass types. In an exemplary embodiment, the first material comprises Coming® ATG™ Glass available from Coming Incorporated (Coming, New York, USA).

[0064] In embodiments, the first CTE of the first material can be less than about 70 x 10"7 / °C, less than about 60 x 10'7 / °C, less than about 50 x 10'7 / °C, less than about, less than about 45 x 10'7 / °C, less than about 40 x 10'7 / °C, less than about 35 x 10'7 / °C, less than about 30 x 10"7 / °C, less than about 25 x 10'7 / °C, or from about 10 x 10'7 / °C to about 70 x 10'7 / °C, and also comprising all sub-ranges and sub-values between these range endpoints.

[0065] In embodiments, the second material of the second layer 3 can comprise soda lime glass (e.g., tempered soda lime glass), aluminosilicate glasses, alkali aluminosilicate glasses, or other like glasses. In embodiments, the second CTE of the second layer 3 can be greater than about 70 x 10'7 / °C, greater than about 75 x 10'7 / °C, greater than about 80 x 10'7 / °C, greater than about 85 x 10'7 / °C, greater than about 90 x 10'7 / °C, greater than about 95 x 10'7 / °C, greater than about lO x 100'7 / °C, or from about 70 x 10'7 / °C to about 150 x 10'7 / °C, and also comprising all sub-ranges and sub-values between these range endpoints.

[0066] In embodiments, the substrates or layers of the prelamination 10 are dissimilar with respect to one or more of different compositions, different thicknesses, and / or differences in other properties such as CTEs. For example, the first CTE of the first material of the first layer 2 can be different than (e.g., substantially different than) the second CTE of the second material of the second layer 3. In embodiments, the second CTE (CTE2) of the second layer 3 is greater than (e.g., substantially greater than) the first CTE (CTEi) of the first layer 2 such that CTE2 > 1.25*CTEi, CTE2> 1.5*CTEi, CTE2> I.75*CTEi, CTE2> 2*CTEi, CTE2> 2.25*CTEi, CTE2> 2.5*CTEi, CTE2> 2.75*CTEi, or CTE2> 3*CTEi.

[0067] In embodiments, the third material of the polymer interlayer 4 can comprise polyvinyl butyral (PVB), such as the product Saflex® Clear (R series) PVB Interlayer (e.g., RA41 / RB41) available from Eastman Chemical Company (Kingsport, Tennessee, USA). In some embodiments, the third material may comprise a low modulus PVB, such as the productSP25-091Trosifol® SC Monolayer from Kuraray Co., Ltd. (Tokyo, Japan). In general, the third thickness T3, softening temperature, melting temperature, and other properties of the polymer interlayer 4 may be selected as required for a particular application.

[0068] Referring still to FIGS. 4-14, further aspects of the method 100 are shown. The method 100 further comprises, in a step 104, inducing a target counter bow TCB in a major surface 12, 14 (FIG. 2) of the prelamination 10 via the fixture 300. As noted above, FIGS. 5- 14 illustrate various fixtures 300 that can be used to implement the method 100. In each of FIGS. 5-10, the individual layers of the prelamination 10 (e.g., the first layer 2, the second layer 3, and the polymer interlayer 4) are not depicted in order to simplify the drawing views. However, it will be understood that the prelamination 10 shown or otherwise represented in FIGS. 5-10 can comprise each of the layers previously described herein and, in embodiments, additional layers.

[0069] FIGS. 5-8 illustrate aspects of a first fixture 300, 300a that can be used to implement the method 100. FIG. 5 is a perspective view of the first fixture 300, 300a and two prelaminations 10 configured to be positioned and oriented by the first fixture according to aspects of the method 100 of FIG. 4. FIG. 6 is a section view along a longitudinal section plane (e.g., dashed rectangular plane 302 depicted in FIG. 5) passing through the prelaminations 10 and the first fixture 300, 300a of FIG. 5, showing longitudinal cross sections of the prelaminations and the fixture. FIG. 7 is a duplicate of the section view of FIG. 6 except one prelamination is omitted and the other prelamination is replaced with schematic representations of the major surface thereof in different (reference) positions. FIG. 8 is an enlarged detail view of a middle region of the prelamination 10 showing aspects of the target counter bow TCB induced in the second major surface 14 of the prelamination 10.

[0070] FIGS. 9-11 illustrate aspects of a second fixture 300, 300b that can be used to implement the method 100. FIG. 9 is a substantial duplicate of the section view of FIG. 6 except the first fixture 300, 300a is replaced with the second fixture 300, 300b. FIG. 10 is a duplicate of the section view of FIG. 9 except one pre lamination is omitted and the other prelamination is replaced with schematic representations of the major surface thereof in different (reference) positions. FIG. 11 is a duplicate of the section view of FIG. 10 except the schematic representations of the major surface are omitted and a horizontal spacing between adjacent support regions of the second fixture 300, 300b are shown.SP25-091

[0071] FIGS. 12-14 illustrate aspects of a third fixture 300, 300c and a fourth fixture 300, 300d that can be used to implement the method 100. FIG. 12 and FIG. 13 are schematic depictions of the third fixture 300, 300c supporting one pre lamination 10 (FIG. 12) or a plurality of prelaminations 10 (FIG. 13), respectively. FIG. 14 is a schematic depiction of the fourth fixture 300, 300d configured to contact a substantial portion of the second major surface 14 of the prelamination 10 to induce the target counter bow TCB therein.

[0072] Referring briefly again to FIG. 2, the first layer 2 and the second layer 3 have outward-facing (exposed) surfaces that define the major surfaces of the prelamination 10. For example, the first layer 2 defines a first major surface of the prelamination 10 (e.g., corresponding to the upper side 12 in FIG. 2), and the second layer 3 defines a second major surface of the prelamination 10 (e.g., corresponding to the lower side 14 in FIG. 2). In practice, the fixture 300 induces the target counter bow TCB in both the first major surface 12 and the second major surface 14, as depicted in FIGS. 5, 6, 9, 12, and 13. However, for ease of description and not for the purpose of limiting the disclosure in any way, the target counter bow TCB is described (and claimed) with reference to the second major surface 14 of the prelamination 10.

[0073] Referring now to FIGS. 2, 5, 6, and 9, the prelamination 10 has a (total) thickness T (FIG. 6 and FIG. 9) defined as a distance between the second major surface 14 and the first major surface 12 (e.g., opposite the second major surface 14). The thickness T comprises the sum of the first thickness T1 of the first layer 2, the second thickness T2 of the second layer 3, and the third thickness T3 of the polymer interlayer 4 (e.g., the individual thicknesses of which are shown in and described with reference to FIG. 2). The prelamination 10 has a width W (FIG. 5) defined as a first dimension of one of the first or second major surfaces 12, 14 orthogonal to the thickness T. The prelamination 10 has a length L (FIG. 5) defined as a second dimension of one of the first or second major surfaces 12, 14 orthogonal to both the thickness T and the width W. In embodiments, the length L is greater than the width W and extends between a first end 24 and a second end 26 of the prelamination 10.

[0074] Referring now to FIGS. 6, 7, 9 and 10, the fixture 300 is configured to orient a reference plane (represented by dashed line RP in FIG. 7 and FIG. 10) of the prelamination 10 transversely with respect to the direction of gravity (e.g., -z direction) to induce the target counter bow TCB. As shown in FIG. 7 and FIG. 10, the reference plane RP corresponds to the second major surface 14 in a flat state (e.g., without the target counter bow TCB) while the prelamination 10 remains positioned on the fixture 300. In embodiments, the reference planeSP25-091RP represents not only the position and curvature of the second major surface 14 of the prelamination 10 prior to inducement of the target counter bow TCB, but also an ideal, flat (non-bowed) configuration of the second major surface 14 (and the first major surface 12) of the laminate structure 1 desired after lamination. The target counter bow TCB, when induced concurrently during the laminating of the pre lamination 10 (as described later in the present disclosure in connection with the method 100), is configured to reduce or eliminate a reference bow (represented by dotted line RB in FIG. 7 and FIG. 10) in the second major surface 14 that would result if the prelamination 10 was laminated without the target counter bow TCB.

[0075] As shown in FIGS. 6, 7, 9 and 10, the fixture 300 is configured to orient the prelamination 10 such that the reference plane RP forms an angle a with the direction of gravity (e.g., -z direction). In embodiments, the angle is in a range of from about 1° to about 45°, from about 1° to about 43°, from about 2° to about 45°, from about 1° to about 40°, from about 5° to about 45°, from about 1° to about 35°, from about 5° to about 35°, from about 5° to about 25°, from about 10° to about 25°, from about 15° to about 25°, from about 15° to about 20°, from about 10° to about 30°, from about 20° to about 35°, from about 25° to about 40°, from about 30° to about 45°, or from about 35° to about 40°, and also comprising all sub-ranges and sub-values between these range endpoints.

[0076] The fixture 300 is configured to position and orient one or more prelaminations 10 having a variety of sizes and shapes. For example, the fixture 300 can accommodate prelaminations 10 having standard sizes, such as 1.2 m (4 ft) x 1.2 m (4 ft), 1.5 m (5 ft) x 1.0 m (3.3 ft), 1.8 m (6 ft) x 1.2 m (4 ft), or 2.0 m (6.6 ft) x 1.5 m (5 ft); half jumbo sizes, such as 1.5 m (5 ft) x 3.0 m (10 ft), 1.6 m (5.2 ft) x 2.8 m (9.2 ft), 2.4 m (7.9 ft) x 3.2 m (10.5 ft), or 2.45 m (8 ft) x 3.2 m (10.5 ft); and jumbo sizes, such as 3.2 m (10.5 ft) x 6.0 m (19.7 ft), 3.0 m (10 ft) x 5.0 m (16.4 ft), 3.1 m (10.2 ft) x 4.5 m (14.8 ft), or 3.6 m (11.8 ft) x 7.0 m (23 ft). In embodiments, the fixture 300 can accommodate prelaminations 10 having sizes that are greater than or less than the length (height) and / or the width dimensions listed herein.

[0077] In embodiments, as shown in FIG. 5, the prelamination 10 is positioned on the fixture 300 in a portrait orientation such that the length L is vertically aligned relative to the width W. The positioning of the prelamination 10 on the fixture 300 in the portrait orientation maximizes the buckling effect of gravity acting on the prelamination 10 when the reference plane RP is oriented transversely with respect to the direction of gravity (e.g., -z direction). In embodiments, as described later in the present disclosure, the fixture 300 comprises various features configured to position and orient the prelamination 10 such that the reference planeSP25-091RP forms the angle a with the direction of gravity. Additionally or alternatively, the fixture 300 can be inclined or tilted so as to form an angle relative to a horizontal direction (e.g., x-axis) and further increase, decrease, or otherwise set or control the angle a (absolute) of the reference plane RP of the prelamination 10 relative to gravity.

[0078] Referring now to FIGS. 7, 8, and 10, further aspects of the target counter bow TCB are shown. As shown in FIG. 8, the target counter bow TCB comprises a target offset TO of the second major surface 14 in a first direction (e.g., generally to the right along the arrow TO) from the reference plane RP. The reference bow RB comprises a reference offset RO of the second major surface 14 from the reference plane RP in a second direction (e.g., generally to the left along the arrow RO) opposite the first direction. As used herein, the target offset TO refers to a maximum out-of-plane deflection or bow of the second major surface 14 from the reference plane RP in the first direction as a result of the (induced) target counter bow TCB. Similarly, as used herein, the reference offset RO refers to a maximum out-of-plane deflection or bow of the second major surface 14 from the reference plane RP in the second direction as a result of the reference bow RB.

[0079] In embodiments, the target offset TO is within ± 50% of the reference offset RO of the reference bow RB, such as within ±45%, ±40%, ±35%, ±30%, ±25%, ±20%, ±15%, ±10%, ±5%, ±4%, ±3%, ±2%, or ±1% of the reference offset RO. For example, if the reference offset RO was 25 mm and the target offset TO was configured to be within ±25% of the reference offset RO, the fixture 300 would be configured to induce the target counter bow TCB to have a target offset TO of between 18.75 mm (25 mm - 6.25 mm) and 31.25 mm (25 mm ± 6.25 mm) since ±25% of 25 mm is ±6.25 mm.

[0080] In embodiments, the target offset TO is greater than or equal to the reference offset RO, such as from equal to the reference offset RO to within ±50% of the reference offset RO (e.g., within ±45%, ±40%, ±35%, ±30%, ±25%, ±20%, ±15%, ±10%, ±5%, ±4%, ±3%, ±2%, or ±1% of the reference offset RO). For example, if the reference offset RO was 25 mm and the target offset TO was configured to be from equal to the reference offset RO to within ±25% of the reference offset RO, the fixture 300 would be configured to induce the target counter bow TCB to have a target offset TO of between 25 mm (25 mm - 0 mm [equal to the reference offset RO]) and 31.25 mm (25 mm ± 6.25 mm) since ±25% of 25 mm is ±6.25 mm. Setting the target offset TO to be greater than or equal to the reference offset RO can be help ensure the target counter bow TCB effectively reduces or eliminates the reference bow RB after the prelamination 10 is laminated to form the laminate structure 1.SP25-091

[0081] Referring again to FIGS. 4-14, the method 100 further comprises, in a step 106, laminating the prelamination 10 on the fixture 300 while (e.g., concurrently) inducing the target counter bow TCB to form the laminate structure 1 . In embodiments, the laminating comprises heating the pre lamination 10 to a lamination temperature configured to increase the first bond strength of the polymer interlayer 4 to a second bond strength (e.g., after the laminating). In embodiments, the laminating further comprises applying additional force or pressure (e.g., pressure Pl and P2 shown in FIG. 2) to one or more of the upper side 12 and the lower side 14 of the pre lamination 10 concurrently and / or selectively during the heating. In embodiments, the laminating further comprises cooling the heated pre lamination 10 (at least) to a setting temperature below which the polymer interlayer 4 is configured to transfer shear forces between first layer 2 and the second layer 3 (e.g., during the laminating). Various suitable hot press processes (e.g., laminating) are known in the art.

[0082] In embodiments, the heating and / or the applying additional force or pressure step(s) of the method 100 is / are preferably implemented using an autoclave, such as any commercially-available autoclave known in the art. The fixtures 300 and the method 100 disclosed herein are particularly suited for use in autoclaves since the fixtures 300 are configured to position the prelamination(s) 10 vertically, which corresponds to the orientation in which laminate structures are typically processed in known autoclaves. However, it should be appreciated that the fixtures 300 disclosed herein are also suitable for any thermal equipment. For example, in the case of laminate structures already laminated in an autoclave using conventional lamination processes and not using the fixtures 300 disclosed herein, the laminated structures can be post-processed using the fixtures 300 disclosed herein according to post-processing methods configured to reduce bow in laminates structures after lamination as described in International Application No. PCT / US2025 / 020872, filed on March 21, 2025, which is incorporated herein by reference in its entirety.

[0083] As noted above, the reference bow RB is the bow (e.g., the reference offset RO) that would result if the prelamination 10 was laminated without inducing the target counter bow TCB while the reference plane RP is oriented vertically (e.g., 0° angle relative to direction of gravity) and while using the same process parameters (e.g., heat, pressure, etc.) that would have been used if the prelamination was laminated with the induced target counter bow TCB. Numerous variables may influence the reference bow RB. A non-exhaustive (and non-limiting) list of such variables includes the respective thicknesses (e.g., Tl, T2, T3) of the first layer 2, the second layer 3, and the polymer interlayer 4, the shear modulus of the polymer interlayer 4,SP25-091 the lamination temperature(s) used during the laminating (e.g., including the heating and / or cooling ramp rates), the compositions of the different layers, and other variables known to influence the reference bow RB. In embodiments, the reference bow RB can be determined in any manner that provides a reasonably accurate value or ranges of values for the reference bow RB. In embodiments, the reference bow RB for a given configuration of an asymmetric laminate structure can be measured (e.g., actual reference bow RB measured during large-scale manufacturing trials or lab-scale fabrication trials) or estimated (e.g., estimated reference bow RB derived from calculations and / or simulations performed using modeling data), as needed.

[0084] Referring now to FIGS. 5-14, further aspects of the various fixtures 300 that can be used to implement the method 100 are shown. In embodiments, the fixture 300a, 300b, 300c comprises a plurality of support regions 304 configured to contact the second major surface 14 of the prelamination 10 at different positions along the length L of the prelamination 10 to induce the target counter bow TCB in the second major surface 14. In such embodiments, as shown in FIGS. 5-13, the support regions 304 are spaced apart from one another along the length L of the prelamination 10. In other embodiments, as shown in FIG. 14, the fixture 300d comprises a support region 306 configured to contact a substantial portion of the second major surface 14 of the prelamination 10 to induce the target counter bow TCB therein. In such embodiments, the support region 306 defines a support surface 308 (e.g., a substantially continuous support surface) that corresponds to the target counter bow TCB such that when the prelamination 10 is positioned on the fixture 300d, the second major surface 14 of the prelamination 10 conforms to the shape of the support surface 308.

[0085] In embodiments in which the support regions 304 are spaced apart, as shown in FIGS. 5-13, the support regions 304 can comprise a first support region 310 proximate the first end 24 of the prelamination 10 and a second support region 312 proximate the second end 26 of the pre lamination 10. The first support region 310 and the second support region 312 are configured to contact the second major surface 14 of the prelamination 10 during the laminating (e.g., step 106 of the method 100).

[0086] In embodiments in which the support regions 304 are spaced apart, as shown in FIGS. 5-13, the support regions 304 can comprise a third support region 314 proximate a middle region 28 of the prelamination 10 disposed between the first end 24 and the second end 26 of the prelamination 10. In embodiments, the middle region 28 can be a region that approximates a midpoint of the prelamination 10 between the first end 24 and the second end 26. In embodiments, the middle region 28 can be a region that extends for a distance fromSP25-091 the midpoint towards both the first end 24 and the second end 26. In embodiments, the middle region 28 encompasses the target offset TO, such as the region identified by the dashed circle 8 in FIG. 7 and schematically depicted in FIG. 8.

[0087] In embodiments, as shown in FIGS. 6, 9, 10, 12, and 13, the third support region 314 is configured to contact the second major surface 14 proximate the middle region 28 of the prelamination so as to set or otherwise define the target counter bow TCB once the prelamination 10 is positioned on the fixture 300a, 300b, 300c and during the laminating. In such embodiments, the magnitude of the target counter bow TCB (e.g., the target offset TO) and / or the position of the third support region 314 are configured to ensure contact therebetween. In some embodiments, if the prelamination 10 does not flex enough at room temperature for the second major surface 14 to contact the third support region 314 when positioned appropriately to set or otherwise define the target counter bow TCB, the fixture 300a, 300b, 300c can include a mechanism (not shown) configured to apply a force to push the prelamination 10 against the third support region 314. In such embodiments, the force can be applied using one or more of a weight, a strap mechanism, and similar force-applying components.

[0088] In embodiments, as shown in FIG. 7 and FIG. 8, the third support region 314 is configured to be spaced from the prelamination 10 during the laminating . In such embodiments, the magnitude or extent of the target counter bow TCB (e.g., the target offset TO) and / or the position of the third support region 314 are configured to ensure the third support region 314 is spaced from the second major surface 14 after the prelamination 10 is positioned on the fixture 300a, 300b, 300c and the target counter bow TCB is induced in the second major surface 14 via the fixture 300a, 300b, 300c.

[0089] In embodiments in which the third support region 314 is configured to be spaced from the prelamination 10 during the laminating, the third support region 314 can be positioned to have a clearance defined as a minimum distance between the reference plane RP of the prelamination 10 and the third support region 314. In such embodiments, the clearance follows the equation: clearance = / x CF, where L is the length of the prelamination 10 in meters (m) and CF is a clearance factor in a range of from about 2 mm / m2to about 8 mm / m2(e.g., from about 2.25 mm / m2to about 7.75 mm / m2, from about 2.5 mm / m2to about 7.5 mm / m2, or from about 2.75 mm / m2to about 7.25 mm / m2). FIG. 15 is a graph (based on experimental data) that illustrates the relationship between part size (e.g., length or diagonal of laminate structure) and long edge bow (e.g., lengthwise bow). As shown in FIG. 15, the reference bow RB typicallySP25-091 increases with the square of part size. The clearance factor CF in the equation above accounts for this relationship. When the third support region 314 is positioned to have the clearance, the prelamination 10 can achieve 100% of its target counter bow TCB without interference with the third support region during the laminating. However, the clearance is also configured to position the third support region 314 close enough to the prelamination 10 to provide a safety function to stop or prevent an unintended over-flexion of the prelamination that could result in the prelamination falling out of the fixture 300a, 300b, 300c.

[0090] In embodiments, as shown in FIG. 7 and FIG. 11, each support region 304 is configured to have a horizontal offset HO along a horizontal direction (e.g., x-axis) from at least one other support region 304 when viewed in a longitudinal section plane (e.g., dashed rectangular plane 302 depicted in FIG. 5) passing through the support regions 304 of the fixture 300a, 300b, 300c. For example, in the embodiment of the first fixture 300a shown in FIG. 6 and FIG. 7, the first support region 310 has a (first) horizontal offset HO from the third support region 314, and the third support region 314 has a (second) horizontal offset HO from the second support region 312. Similarly, in the embodiment of the second fixture 300b shown in FIG. 11, the first support region 310 has a (first) horizontal offset HO from the third support region 314, and the third support region 314 has a (second) horizontal offset HO from the second support region 312. The (vertical) spacing of the support regions 304 along the length L of the prelamination 10, and the horizontal offsets HO between the support regions 304 cooperate to enable the fixture 300a, 300b, 300c to orient the reference plane RP of the prelamination 10 to form the angle a relative to gravity, which in turn induces the target counter bow TCB along the length L of the prelamination 10. In embodiments, the vertical spacing and / or the horizontal offsets HO for the support regions 304 are infinitely adjustable to accommodate difference sizes of the prelamination(s) and induce different target counter bows TCB, as needed for a particular application.

[0091] In embodiments, as shown in FIG. 5, at least one support region 304 is configured to contact the second major surface 14 along an entirety of the width W of the pre lamination 10. For example, in the embodiment of the first fixture 300a shown in FIG. 5 and FIG. 6, each of the first support region 310, the second support region 312, and the third support region 314 contacts the second major surface 14 along an entirety of the width W of the prelamination 10. In embodiments, at least one support region 304 has a contact feature, such as an edge or a surface, which extends linearly across the second major surface 14 along the entirety of the width W of the prelamination 10. When the support regions 304 have linear contact featuresSP25-091 that extend across the entire width W of the second major surface 14 of the prelamination 10, the fixture 300a, 300b, 300c may not be configured to reduce bow along the width W of the prelamination 10 (e.g., since no counter bow can be provided in the direction of the width JV). Nevertheless, the fixture 300a, 300b, 300c is still configured to reduce bow along the length L of the prelamination 10.

[0092] In embodiments of the method 100, as depicted in FIGS. 5, 6, 9, 13, and 14, positioning the prelamination 10 on the fixture 300, 300a, 300b, 300c, 300d comprises positioning a plurality of further pre laminations 10 on the fixture. In embodiments, the further prelaminations can be configured to be substantially identical to the prelamination 10, or one or more of the pre laminations can be different than the prelamination 10 with respect to one or more features (e.g., size, thicknesses, compositions, etc.). In embodiments, the various fixtures 300 can be configured to accommodate the further prelaminations in different ways.

[0093] As shown in FIG. 5 and FIG. 6, the support regions 304 of the first fixture 300a can be configured to position and orient the prelamination 10 and one or more further prelaminations 10 in spaced relation to one another. For example, a first group of the first support region 310, the second support region 312, and (optionally) the third support region 314 can be configured to position and orient a first prelamination, and a second group of the first support region 310, the second support region 312, and (optionally) the third support region 314 can be configured to position and orient a second prelamination. As shown in FIG. 5, the first prelamination 10 (e.g., positioned in front of the second prelamination in the view of FIG. 5) and the second prelamination 10 are spaced from one another and both include the target counter bow TCB included by the first fixture 300a. In embodiments, the second edge 26 of the prelaminations 10 can be configured to rest on the same surface on which the first fixture 300a rests, as shown in FIG. 5, or the first fixture can include or otherwise define a bottom surface (not shown) on which the pre laminations 10 rest. In embodiments, each of the first support region 310 and the second support region 312 may have an auxiliary support region (not shown) that is spaced horizontally (e.g., x-axis) therefrom in order to retain or surround the first end 24 and the second end 26 of the prelaminations 10 therebetween.

[0094] As shown in FIG. 9, the support regions 304 of the second fixture 300b can be configured to position and orient the prelamination 10 and one or more further pre laminations 10 in spaced relation to one another. For example, a first group of the first support region 310, the second support region 312, and the third support region 314 can be configured to position and orient a first prelamination, and a second group of the first support region 310, the secondSP25-091 support region 312, and a fourth support region 316 can be configured to position and orient a second prelamination spaced from the first prelamination. As shown in FIG. 9, the fourth support region 316 is similar in size and / or shape to the first support region 310 and the second support region 312, but the fourth support region 316 is configured to contact the second major surface 14 proximate the middle region 28 of the prelamination.

[0095] As shown in FIG. 12 and FIG. 13, the third fixture 300c is similar to the second fixture 300b in that the third fixture 300c comprises a first fixture portion (e.g., left half of the third fixture 300c shown in FIG. 13) that substantially corresponds to the second fixture 300b and a second fixture portion (e.g., right half of the third fixture 300c shown in FIG. 13) that is symmetrical to the first fixture portion about a central symmetry line 318. The configuration of the third fixture 300c may be referred to as an A-frame. The third fixture 300c in the form of an A-frame is configured to maximize the glass load in the thermal equipment used to perform the laminating. Similar to the second fixture 300b, the third fixture 300c includes the first group of the first support region 310, the second support region 312, and the third support region 314, and the second group of the first support region 310, the second support region 312, and the fourth support region 316. However, as shown in FIG. 13, the support regions 304 of the third fixture 300c can be configured to position and orient groups of two or more prelaminations 10 in abutment with one another, thereby increasing throughout when forming laminate structures according to the method 100 described herein.

[0096] In embodiments in which two or more prelaminations 10 are positioned in abutment with one another, such as shown in FIG. 13, care needs to be taken to ensure possible overflow of polymer material from the polymer interlayer 4 does not cause cascade sticking. “Cascade sticking,” as used herein, refers to a condition in which polymer material overflow causes a first prelamination 10 to stick or otherwise adhere to a second prelamination 10 in abutment with the first prelamination, the second prelamination 10 to stick or otherwise adhere to a third prelamination 10 in abutment with the second prelamination, and so on during lamination of the pre laminations. To avoid cascade sticking, the first layer 2 and the second layer 3 of each prelamination should have close size correspondence with the first layer 2 being only slightly smaller than the second layer 3. For example, in an exemplary embodiments, one or more of the length (long axis) and the width (short axis) of the first layer 2 of the prelamination 10 is in a range of from about 0 mm to about 1 mm smaller than the corresponding dimension(s) of the second layer 3 of the pre lamination 10. If the first layer 2 is more than 1 mm smaller than the corresponding dimension(s) of the second layer 3, excess polymer material may cause cascadeSP25-091 sticking as described herein. Alternatively, if the first layer 2 is substantially smaller than the second layer 3 along one or more dimensions of the prelamination 10 (e.g., 5 mm smaller), then cascade sticking may be avoided by configuring the polymer interlayer 4 to be smaller than the first layer 2 along the corresponding one or more dimensions. However, the usable area of the resulting laminate structure 1 may be reduced when the first layer 2 and the polymer interlay 4 are smaller than the second layer 3.

[0097] EXAMPLES

[0098] Various embodiments of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

[0099] Example 1 - Bow Reduction Using Different Tilt Angles

[0100] Simulations were performed to estimate bow reduction using different tilt angles. The laminate structure model used in the simulation had a size of 2.22 m x 3. 125 m. Although the laminate structure model described in Example 1 is configured with a specific size, it will be appreciated that the fixtures and method disclosed herein can be used to reduce or eliminate bow in laminate structures of any size. The laminate structure model had the following layer structure: a first layer (e.g., first layer 2 in FIG. 1) comprising Coming® ATG™ Glass and having a thickness of 0.5 mm, a second layer (e.g., second layer 3 in FIG. 1) comprising soda lime glass (SLG) and having a thickness of 3 mm, and a polymer interlayer (e.g., polymer interlay 4 in FIG. 1) comprising PVB and having a thickness of 0.76 mm. The laminate structure model was positioned to have a portrait orientation with the first layer facing out (e.g., similar to the prelaminations 10 shown in FIGS. 5, 6, and 9)

[0101] In the simulation, the laminate structure model was supported at short edges along the top and bottom (e.g., first end 24 and second end 26 in FIGS. 5, 6, and 9). The polymer interlayer becomes soft enough during the autoclave cycle to decouple the layers (e.g., no shear forces are transferred between the first layer and the second layer). The sag or bow of the laminate structure model are generally determined by the stiffness of the 3 mm-thick SLG glass modeled as the second layer 3. In the simulation, the final bow is a superposition of CTE- induced laminate bow and gravity sag. Table 1 below reports the results of the simulation. The attributes (i) peak to valley (PV) bow, (ii) maximum bow, (iii) bow at center, and (iv) minimum bow were modeled at reference plane RP angles (tilt angle) of 0°, 2°, 5°, 7.5°, and 10°. FIGS. 16-20 graphically depict the results of the simulation according to Example 1.SP25-091

[0102] Table 1. Bow Simulation at Different Tilt Angles

[0103] In Table 1, the maximum bow values and the minimum bow values are relative the reference plane RP. The maximum bow refers to the largest simulated bow on one side of the reference plane RP (e.g., above the reference plane RP), and the minimum bow refers to the largest simulated bow on the other side of the reference plane RP (e.g., below the reference plane RP). The minimum bow of 0 mm for Simulation Nos. S1-S3 means the simulated bow did not extend below the reference plane RP. The minimum bow of -1.7 mm and -12.8 mm for Simulation Nos. S4 and S5, respectively, means the simulated bow extended below the reference plane RP by the indicated amounts for these simulations. Based on the results of the simulation, a tilt angle of about 7.5° provides the minimum overall bow for the laminate structure model used in the simulation.

[0104] Example 2 - Prototype Fixture

[0105] A prototype fixture corresponding generally to the first fixture 300a described above with reference to FIGS. 5-8 was constructed. FIG. 21 shows various dimensions (mm) of the prototype fixture. Bow reduction trials are performed using the prototype fixture.

[0106] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected.

Claims

SP25-091CLAIMSWhat is claimed is:1 . A method for forming a laminate structure, comprising: positioning a prelamination on a fixture, the prelamination comprising a first layer having a first coefficient of thermal expansion (CTE), a second layer having a second CTE that is greater than the first CTE, and a polymer interlayer disposed between and bonding the first layer and the second layer with a first bond strength; inducing a target counter bow in a second major surface of the prelamination via the fixture, the fixture configured to orient a reference plane of the prelamination transversely with respect to a direction of gravity to induce the target counter bow, the reference plane corresponding to the second major surface in a flat state with the pre lamination remaining positioned on the fixture; and laminating the prelamination on the fixture while inducing the target counter bow to form the laminate structure, wherein the laminating comprises heating the prelamination to a lamination temperature configured to increase the first bond strength of the polymer interlayer to a second bond strength, wherein the target counter bow is configured to reduce or eliminate a reference bow in the second major surface that would result if the prelamination was laminated without the target counter bow.

2. The method of claim 1, wherein the reference plane forms an angle of from about 1° to about 45° with the direction of gravity.

3. The method of claim 1, wherein the reference plane forms an angle of from about 1° to about 35° with the direction of gravity.

4. The method of claim 1, wherein the reference plane forms an angle of from about 5° to about 25° with the direction of gravity.

5. The method of any one of the preceding claims, wherein the second layer defines the second major surface of the prelamination, and wherein the first layer defines a first major surface of the prelamination opposite the second major surface.SP25-0916. The method of any one of the preceding claims, wherein: the prelamination has a thickness defined as a distance between the second major surface and a first major surface opposite the second major surface, a width defined as a first dimension of one of the first or second major surfaces orthogonal to the thickness, and a length defined as a second dimension of one of the first or second major surfaces orthogonal to both the thickness and the width, the length is greater than the width and extends between a first end and a second end of the prelamination, and the prelamination is positioned on the fixture in a portrait orientation such that the length is vertically aligned relative to the width.

7. The method of claim 6, wherein the fixture comprises a plurality of support regions configured to contact the second major surface of the prelamination at different positions along the length.

8. The method of claim 7, wherein the plurality of support regions are spaced apart from one another along the length of the prelamination.

9. The method of any one of claims 7-8, wherein the plurality of support regions comprise a first support region proximate the first end of the prelamination and a second support region proximate the second end of the prelamination, the first and second support regions contacting the second major surface during the laminating.

10. The method of any one of claims 7-9, wherein the plurality of support regions comprise a third support region proximate a middle region of the prelamination disposed between the first end and the second end.

11. The method of claim 10, wherein the third support region is spaced from the prelamination during the laminating.SP25-09112. The method of claim 11, wherein the third support region has a clearance defined as a minimum distance between the reference plane and the third support region, the clearance following the equation: clearance = L2x CF, where L is the length of the prelamination in meters (m) and CF is a clearance factor in a range of from about 2 mm / m2to about 8 mm / m2.

13. The method of any one of claims 7-12, wherein each support region of the plurality of support regions has a horizontal offset from at least one other support region when viewed in a longitudinal section plane parallel to the length and the thickness of the prelamination and passing through the support regions of the fixture.

14. The method of any one of claims 7-13, wherein at least one support region of the plurality of support regions is configured to contact the second major surface along an entirety of the width of the prelamination.

15. The method of claim 14, wherein the at least one support region of the plurality of support regions has a surface that extends linearly across the second major surface along the entirety of the width of the prelamination.

16. The method of any one of the preceding claims, wherein: the target counter bow comprises a target offset of the second major surface in a first direction from the reference plane, the reference bow comprises a reference offset of the second major surface from the reference plane in a second direction opposite the first direction, and wherein the target offset is within ± 25% of the reference offset.

17. The method of claim 16, wherein the target offset is greater than or equal to the reference offset.

18. The method of any one of the preceding claims, wherein the laminating comprises cooling the heated prelamination to a setting temperature below which the polymer interlayer is configured to transfer shear forces between the first layer and the second layer.SP25-09119. The method of any one of the preceding claims, wherein positioning the prelamination on the fixture comprises positioning a plurality of further prelaminations on the fixture, each further prelamination configured to be substantially identical to the prelamination.

20. The method of any one of the preceding claims, wherein one or more of: the first layer is a first glass layer, and the second layer is a second glass layer, and the first layer has a first thickness, and the second layer has a second thickness that is greater than the first thickness.

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