Method of liquid fluid cell lamination and system

Abstract

Method (100) configured to laminate a liquid fluid cell (1) to a substrate (6), particularly a glass substrate, the method (100) comprising the steps of: - arranging(110) at least one liquid fluid cell (1) comprising at least a first cell substrate (15) and a second cell substrate (15) spaced such to form a cell gap (16) comprising a fluid, particularly a liquid crystal material, with at least one substrate (6) and at least one lamination layer (7); - a laminating (120) of the substrate (6) to the liquid fluid cell (1) via at least one of the first cell substrate (15) or the second cell substrate (15) using the lamination layer (7), characterized by at least two of the following steps, particularly performed temporarily overlapping or simultaneously: - a degassing and / or gas dissolving; - applying (130) a controlled pressing, particularly applying a low pressure for a defined timespan; - applying (140) a controlled thermal load; - applying (150) an even distribution of pressure over the liquid fluid cell (1); and - applying (160) an even distribution of temperature over the liquid fluid cell (1).

Description

[0001] Method of liquid fluid cell lamination and system

[0002] The present invention refers to a method configured to laminate a liquid fluid cell to a substrate. The invention refers to a method of manufacturing a liquid fluid cell. The invention refers to a liquid fluid cell. The invention refers to a system. The invention refers to a lamination stack.

[0003] Manufacturing of glass windows for architectural or automotive applications is known in the art. The prior art includes state-of-the-art lamination techniques using high pressures exceeding 1.5 bar and up to 12 bar (autoclave technology) and / or applying pressure in a non-uniform fashion (vacuum bag technology). Lamination particularly refers to a technique of connecting at least two surfaces together, particularly using a thermoplastic or elastomeric polymer or foil of some sort. For example, for lamination a thermoplastic interlayer may be arranged between two glass substrates where the glass substrates are bonded by the application of heat, e.g. using temperatures around 120°C to 140°C, and elevated pressure.

[0004] Liquid crystal windows (LCWs) differ from regular glass laminates used in architectural applications as they contain a liquid layer, in particular a liquid-crystalline layer, for switchable glazing. LCWs are particularly an aesthetic and functional high-quality technology for sun and glare protection as well as privacy applications - primarily for use in architecture, but also for use in a car, a bus, a recreational vehicle, a commercial vehicle, a boat, a train or an airplane. The sun protection variant, which uses attenuation or dimming of light in particular by light absorption, can be realized in different light transmittance bandwidths and can achieve energy savings of up to 40% in building climate control systems. For users, the windows can offer maximum convenience since they offer continuously variable switching within seconds and are particularly transparent and color-neutral in both switching states. LCWs comprise at least two transparent substrates with a respective liquid layer, particularly a liquid crystal (LC) layer, in a cell gap between the substrates. This structure may be referred to as liquid fluid cell. The liquid crystal layer may be filled into the cell using e.g. vacuum filling. Vacuum filling involves creating a (partial) vacuum in the space between the cell substrates, i.e. the cell gap which is spaced by spacers, which may draw the liquid fluid material into the liquid fluid cell. The liquid layer particularly has different mechanical properties than the glass and polymeric layers, particularly PVB layers, which can cause deformation during the lamination process. The lamination techniques known in the art are not suitable for high-quality laminated LCWs due to the presence of the liquid layer. These techniques can lead to inhomogeneous stress and deformation of the glass substrates, resulting in non-uniform thickness of the LC layer and color non-uniformities in the product. Additionally, the buildup of LC glazing can vary for different applications, leading to different stress levels and failure modi.

[0005] The object of the invention is to provide a way to allow manufacturing of laminated structures comprising liquid fluid cells for window applications, to improve the manufacturing of laminated products comprising liquid fluid cells and to provide high- quality fluid cells and respective laminated systems comprising liquid fluid cells, particularly LCWs.

[0006] The object of the invention is solved by a method configured to laminate a liquid fluid cell to a substrate according to claim 1. The object of the invention is solved by a method of manufacturing a liquid fluid cell according to claim 8. The object of the invention is solved by a liquid fluid cell according to claim 10. The object of the invention is solved by a system according to claim 11. The object of the invention is solved by a lamination stack according to claim 15. Features, technical effects, and advantages described with respect to either method may also apply to devices, systems, or their respective use. This also applies the other way around. Therefore, throughout the description, cross-referencing can be used or is used to describe aspects and embodiments described with respect to one category to also describe aspects and embodiments with respect to another category. It may also be possible to transfer features from their respective individual link they are described in to specify embodiments or aspects of the same or a different category. Embodiments are described by the dependent claims.

[0007] Therein, a method may be configured to laminate a liquid fluid cell to a substrate. The substrate can particularly be a glass substrate. The method can comprise the step of an arranging at least one liquid fluid cell, a substrate and a lamination layer, in particular to form a stack, wherein in particular the lamination layer is an interlayer, in particular an intermediate layer which is positioned or situated between the liquid fluid cell and the substrate. The liquid fluid cell can comprise at least a first cell substrate and a second cell substrate spaced such to form a cell gap comprising a fluid, particularly a liquid crystal material. The method can comprise the step of a laminating of the substrate to the liquid fluid cell via at least one of the first cell substrate or the second cell substrate using the lamination layer. The laminating can comprise at least two of the following steps, particularly performed temporarily overlapping or simultaneously, a degassing - alternatively or additionally a gas dissolving of the stack, applying a controlled pressing to the stack, particularly applying a low pressure for a defined timespan, applying a controlled thermal load to the stack, applying an even distribution of pressure over the stack which includes the liquid fluid cell and applying an even distribution of temperature over the stack which includes the liquid fluid cell.

[0008] In some embodiments only two of the steps selected from degassing of the stack and / or gas dissolving in the stack, applying a controlled pressing to the stack, applying a controlled thermal load to the stack, applying an even distribution of pressure over the stack, and applying an even distribution of temperature over the stack are performed in the method. It is preferred that one of these steps is the degassing of the stack and / or gas dissolving in the stack. In other embodiments at least three of the steps, more preferably at least four of the steps, are carried out in the method. It is preferred that the steps of applying a controlled pressing to the stack and applying a controlled thermal load to the stack are combined, in particular in combination with a preceding step of degassing of the stack and / or gas dissolving in the stack. In yet another embodiment all of the steps are included in the method.

[0009] Glass for all applicable layers may be soda lime glass or alkaline glass. Glass may also be an alkali-free glass or a chemically strengthened glass. Suitable alkali-free glass particularly comprises boro-silicate glass or alumino-silicate glass, which may have low alkali content or even no alkali content in the glass recipe. Such glass is, for example, available under the tradename Eagle 2000 glass or EAGLE XG slim glass from Corning and under the tradename AF32 or BOROFLOAT from Schott as sold at the filing date and / or priority date. Suitable chemically strengthened glass is, for example, available under the tradename Gorilla from Corning and under the tradename Dragontrail from Asahi Glass Corporation (AGC) at the filing date and / or priority date.

[0010] An exemplary glass composition comprises SiO2, B2O3 and Na2O, where (SiO2 + B2O3) > 66 mol.%, and Na2O > 9 mol-%. In an embodiment, the glass substrates comprise at least 6 wt-% aluminum oxide. In a further embodiment, a glass substrate comprises one or more alkaline earth oxides, such that a content of alkaline earth oxides is at least 5 wt-%. Suitable glass compositions, in some embodiments, further comprise at least one of K2O, MgO, and CaO. In a particular embodiment, the glass can comprise 61-75 mol-% SiO2; 7- 15 mol-% AI2O3; 0-12 mol-% B2O3; 9-21 mol-% Na2O; 0-4 mol-% K2O; 0-7 mol-% MgO; and 0-3 mol-% CaO. A further exemplary glass composition suitable as glass substrates to be laminated onto the liquid fluid cell comprises: 60-70 mol-% SiCh; 6-14 mol-% AI2O3; 0-15 mol-% B2O3; 0- 15 mol-% U2O; 0-20 mol-% Na2O; 0-10 mol-% K2O; 0-8 mol-% MgO; 0-10 mol-% CaO; 0- 5 mol-% ZrCh; 0-1 mol-% SnCh; 0-1 mol-% CeC>2; less than 50 ppm AS2O3; and less than 50 ppm Sb20s; where 12 mol-% < (U2O + Na2O + K2O) < 20 mol-% and 0 mol-% < (MgO + CaO) < 10 mol-%.

[0011] A still further exemplary glass composition suitable as glass substrates to be laminated onto the liquid fluid cell comprises: 63.5-66.5 mol-% SiO2; 8-12 mol-% AI2O3; 0-3 mol-% B2O3; 0-5 mol-% U2O; 8-18 mol-% Na2O; 0-5 mol-% K2O; 1-7 mol-% MgO; 0-2.5 mol-% CaO; 0-3 mol-% ZrO2; 0.05-0.25 mol-% SnO2; 0.05-0.5 mol-% CeO2; less than 50 ppm AS2O3; and less than 50 ppm Sb2O3; where 14 mol-% < (U2O + Na2O + K2O) <18 mol-% and 2 mol-% < (MgO + CaO) < 7 mol-%.

[0012] The glass substrates preferably have a thickness in the range from 300 pm to 20 mm, preferably from 0.5 mm to 10 mm and in particular from 1 mm to 6 mm.

[0013] In an embodiment it is preferred that the cell substrates, in particular the glass cell substrates, have a thickness in the range from 300 pm to 6 mm, preferably from 0.4 mm to 4 mm, more preferably from 0.5 mm to 3 mm, even more preferably from 0.5 mm to 2 mm, still more preferably from 0.5 mm to 1 mm, and in particular from 0.5 mm to 0.7 mm. The cell substrates are preferably made of alkali-free glass, in particular selected from boro-silicate glass and alumino-silicate glass, and preferably have minimal waviness.

[0014] In an embodiment the substrate to which the cell is laminated, in particular a cover sheet, is made of glass and has a thickness in the range from 1 mm to 20 mm, preferably from 2 mm to 15 mm, more preferably from 3 mm to 12 mm, even more preferably in the range from 4 mm to 10 mm, and in particular in the range from 6 mm to 8 mm. In case the substrate is a coversheet it is preferred that soda lime glass or toughened or tempered glass is used. Alternatively, alkali-free glass may be used.

[0015] The layers assembled in the stack and laminated according to the present method, in particular the glass substrates and / or the lamination layer(s), preferably have a surface area of at least 100 cm2, more preferably at least 2500 cm2, even more preferably at least 1 m2, still more preferably at least 2 m2, yet more preferably at least 2.5 m2and in particular at least 5 m2. In further embodiments it is also possible to assemble and laminate layers, in particular the glass layers of the cell(s) and substrate(s), which exceed 5 m2having sizes of up to 10 m2and beyond.

[0016] The term arranging the at least one liquid fluid cell, the substrate and the lamination layer particularly refers to the components to be set such that the method may be performed. In particular, the mentioned components, but also other components, may be provided as stated elsewhere herein. The respective components may be set to form a prelaminated stack which may already be in the right sorting of the layers for performing the lamination. In particular, in an embodiment the layers assembled for lamination are each positioned horizontally such that the layers in the assembly relative to each other are configured in a vertically stacked manner.

[0017] The layers which are arranged in the stack can comprise the layers used to configure the liquid fluid cell, a lamination layer and a substrate, wherein the substrate may e.g. be a coversheet or one of the substrates of an additional liquid fluid cell. The stack can thus comprise the layers of one or more liquid fluid cells, one or more lamination layers and optionally one or more coversheets.

[0018] The respective components to be arranged may be provided. The term ..providing" may refer to manufacturing the respective structure or device. Alternatively or additionally, the term may refer to handling the respective structure or device for the purpose of any of the methods described herein.

[0019] The method described addresses the issues related to stress and deformation during lamination. This includes particularly providing a laminating technique that applies uniform pressure over the surface(s) of the laminate, reducing the risk of deformation and non- uniform thickness of the liquid fluid layer, particularly a liquid crystal (LC) layer. The method can provide a range of variations in the build-up and edge design of the liquid fluid and / or LC glazing, as well as dimensional freedom (shapes) required for different applications. Additionally, the invention allows addressing the failure modes caused by non-uniform cell gap and insufficient cell gap in solar and privacy products respectively. The method can provide a solution that will improve the manufacturing process of LC windows, resulting in better quality and uniformity of the resulting products.

[0020] The method for laminating a liquid fluid cell to a substrate, particularly a glass substrate, may address the issues related to stress and deformation during lamination. This is achieved by providing a liquid fluid cell structure comprising at least two cell substrates to limit a cell gap, a substrate, and a lamination layer. One of the cell substrates is then laminated to the substrate using the lamination layer, with the process particularly including at least two of the following steps: a degassing and / or gas dissolving, applying a controlled pressing, applying a controlled thermal load, applying an even distribution of pressure over the liquid fluid cell, and applying an even distribution of temperature over the liquid fluid cell.

[0021] A degassing is a particular step to reduce and minimize the amount of air bubbles or residual air potentially placed or trapped between and also within layers of the (pre-)laminate. In an embodiment (pre-)lamination degassing can remove trapped solvents, air bubbles, residual air and / or water vapour bubbles or residues, and reduce the amount of dissolved gas in the interlayer material. To counteract, the laminate or respectively the pre-laminate may be heated in an oven under vacuum. Therefore, volatiles can diffuse out of the laminate. This may prevent unwanted outgassing and delamination later on, particularly during use of the resulting product. Proper lamination processing can be critical to produce flat, well-bonded laminates such as LCWs, particularly free of wrinkles, pits, or other defects between layers.

[0022] Alternatively or additionally, a gas dissolving can be used. In this step, a respective potentially disturbing gas is transferred via adapted temperature and pressure characteristics into a solvent provided e.g., in an autoclave.

[0023] Applying a controlled pressing can refer to the act of exerting pressure on the liquid fluid cell and the entire lamination stack in a controlled manner, typically by applying a low amount of pressure for a defined period of time. This can be done through various means, such as using a press device to apply the pressure.

[0024] Applying a controlled thermal load can refer to the act of applying heat to the liquid fluid cell and the entire lamination stack in a controlled manner, particularly by using a heating element or other heat source to apply the heat. The temperature and duration of the heat application can be carefully controlled to avoid damaging the cell, adding stress in the stack or causing unwanted changes in the optical or mechanical properties of the resulting laminate, particularly the lamination stack as it is described in detail elsewhere herein, or in the LCW.

[0025] Applying an even distribution of pressure over the liquid fluid cell can refer to the act of exerting pressure on the cell and the entire lamination stack in a uniform and consistent manner, so that the stress and forces applied to the liquid layer are uniform across the surface of the cell. This can be achieved through the use of specialized equipment or processes designed to apply pressure evenly as described elsewhere herein e.g., via a pressing device.

[0026] Applying an even distribution of temperature over the liquid fluid cell and also the entire lamination stack can refer to the act of heating the cell in a uniform and consistent manner, so that the temperature and heat applied to the cell are uniform across its surface. This can be achieved through the use of specialized equipment or processes designed to apply heat evenly, such as using vacuum bag with a heat box or other heat source. Preferably, homogeneously heated press plates are used as a heat source e.g., in a flatbed laminator as described elsewhere herein. A heat source may be used as a conducting heat source or a convection heat source.

[0027] A liquid fluid cell can be a structure that contains a liquid layer and which can be used in applications such as liquid crystal windows. For the latter, the liquid fluid may be a liquid crystal. The substrate can be the surface onto which the liquid fluid cell is applied or laminated to. In an embodiment the substrate may be an additional cell substrate of a second liquid fluid cell (identical or similar). In another embodiment the substrate is not part of another liquid fluid cell but may e.g. be a cover sheet. A lamination layer can be a material used to bond the liquid fluid cell to the substrate, and the lamination layer is typically made of a polymeric material, particularly a thermoplastic material. Thermoplastics can be used together with heat and / or pressure. For lamination, the lamination layer is particularly arranged as an interlayer between the two elements to be joined and in a subsequent treatment, which particularly involves application of heat and / or elevated pressure, the two elements and the interlayer can be bonded. The interlayers such as, for example, an ionoplast, ethylene vinyl acetate (EVA), polyvinyl butyral (PVB) or thermoplastic polyurethane (TPU) preferably do not have adhesive properties when they are applied without pressure and heat. Additionally or alternatively, polyolefin elastomers can be used. Another material suitable for functioning as lamination layer / interlayer is SentryGlas SG5000 (DuPont) as it is defined on the date of filing and / or the date of priority, particularly by Deutsches Institut fur Bautechnik. Additionally or alternatively, any of the following may be used as interlayer as defined on the date of filing and / or the date of priority, particularly in the most recent release to the specified date (manufacturers and state of origin in brackets): EVA (STR Corp., Enfield, CT), EMA (Exxon Chemical Co., Baytown, TX), EMAC (Chevron Corp., Orange, TX), PVC plasticized (Geon Company, Avon Lake, OH), PVB plasticized (Solutia, St. Louis, MO), Polyethylene, Metallocene-catalyzed (Exxon Chemical Co., Baytown, TX), Polyurethane Hard (97 Shore A), Polyurethane Semi-rigid (78 Shore A), ISD resin (3M Corp., Minneapolis, MN), Acoustic modified PVB (Sekisui KKK, Osaka, Japan), llvekol A (liquid curable resins) (Cytec, Woodland Park, NJ).

[0028] One or more polymer interlayers may be used as lamination layers, particularly incorporated to form a respective laminate, particularly lamination stack and / or LCW. A plurality of interlayers may provide complimentary or distinct functionality, including adhesion promotion, acoustic control, UV transmission control, tinting, coloration and / or IR transmission control.

[0029] During the lamination process, a lamination layer can be heated to a temperature effective to soften the lamination layer, particularly promoting a conformal mating of the lamination layer to respective surfaces of the glass sheets. For PVB, a lamination temperature can be about 140°C. Mobile polymer chains within the interlayer material develop bonding with the glass surfaces, which promote adhesion. Elevated temperatures may in some cases also accelerate the diffusion of residual air and / or moisture and dissolved gas from the glass-polymer interface.

[0030] The application of pressure both promotes flow of the interlayer material and suppresses bubble formation that otherwise could be induced by the combined vapor pressure of water and air trapped at the interfaces. In an exemplary embodiment, to suppress bubble formation, heat and pressure can simultaneously be applied.

[0031] The laminating process described here or elsewhere herein may provide several advantages over the prior art. By using controlled pressing and temperature loading, the risk of deformation and non-uniform thickness of the liquid fluid layer, in particular the LC layer, can be reduced. Additionally, by applying an even distribution of pressure and temperature over the liquid fluid cell, the invention ensures that the stress and forces applied to the liquid layer are uniform, thus avoiding the formation of defects, e.g. dark(er) or bright(er) spots, in the product.

[0032] A controlled cooling after the lamination is finished may be performed. This allows to reduce deformation upon uncontrolled temperature flux in the laminate. This further stabilizes the resulting structure. Overall, the method described herein offers a more controlled and precise lamination process for liquid fluid cells, resulting in better quality and uniformity of the final product compared to traditional methods.

[0033] In a particular embodiment, the lamination process for liquid fluid cells, in particular LC cells, used e.g. in architectural applications can involve several steps, each of which can be carefully controlled to ensure a high-quality end product. The first step is particularly the stack build up, which involves stacking different glass substrates or liquid crystal cells with an interlayer material in between. This can be followed by a de-gassing, which can remove excess gases such as air and water from the lamination stack to prevent gas bubbles from forming in the final product. The stack can be a symmetrical or unsymmetrical stack. Therefore, the respective resulting laminate can have a symmetrical stacking or an unsymmetrical stacking of layers. The symmetry or lack thereof may refer to the respective middle layer of the structure or a plane that “divides” the respective laminate into two halves.

[0034] In a step, particularly next step, further particularly third step, an elevated temperature processing can be performed, which particularly involves softening the interlayer material to enable proper adhesion to the glass surface. This can also involve cross-linking for curable interlayers to increase durability.

[0035] In a step, particularly next step, further particularly fourth step, applying pressure can be performed. This can be done by e.g. using a vacuum bag or an autoclave process, and can be useful to increase solubility of gas components in the interlayer material and dissolve all residual gas bubbles for a bubble-free laminate. In a preferred embodiment flatbed lamination can be used, as it allows for a more controlled transfer of temperature and pressure to the stack. The pressing can in addition favourably contribute to promoting adhesion and bonding.

[0036] Degassing of the arranged stack and in particular degassing by applying a vacuum or evacuation of the (pre-)lamination stack facilitates the use of lower pressure and lower thermal load in the (following) lamination step. Compared to conventional methods, in particular the combined use of providing cells having underfill / underpressure and of degassing and evacuation of the (pre-)lamination stack enables the reduction of mechanical stress in the lamination. In this respect, in the present method a flatbed laminator is preferably used as it is well suited to give uniform pressing and uniform temperature. Alternatively, an autoclave method or a vacuum bag method may also be used, where compared to standard prior art procedures the combined use of cells with underfill / underpressure and of degassing and evacuation of the (pre-)lamination stack can likewise allow the use of lower pressure and lower temperature load during lamination.

[0037] Therefore, preferably pressure and / or temperature load may be below typical pressure and temperature load values as used in state-of the-art lamination, particularly between 10% and 95% lower than the given values, further particularly between 20% and 80% lower than the given values.

[0038] In a respective state-of-the-art, yet exemplary, lamination method using a vacuum bag or hotbox the temperature can range from 0 °C to 150 °C while vacuum underpressure in bar may be varying from -1 bar to 1 bar, in particular relative to the ambient or atmospheric pressure, over a time of up to 540 min.

[0039] For reference, in a vacuum bag process a temperature profile may start at 20 °C and can remain constant for 120 min. Subsequently, it can undergo a linear increase between 120 min and 150 min to reach 75 °C, particularly remaining constant for approximately 10 min. The temperature then particularly continues to rise linearly from 75 °C to 125 °C between 170 min and 200 min. After that, the temperature can remain constant between 200 min and 380 min. Finally, the temperature experiences a linear decrease to reach 40 °C at 500 min.

[0040] The vacuum underpressure particularly remains at around -0.98 bar up to 190 min, after which it steps to 0.71 bar and remains constant until 490 min. At this point, the pressure can normalize.

[0041] In a respective state-of-the-art, yet exemplary, lamination method using an autoclave temperature may range from 0 °C to 150 °C while pressure in bar can be varying from 0 bar to 14 bar over a time up to 400 min.

[0042] The temperature profile can start at 20 °C and particularly linearly increasing for 110 min to reach 125 °C. Between 110 min and 130 min, the temperature may experience a linear increase to reach 135 °C, particularly remaining constant at this level for approximately 10 min. The temperature particularly then undergoes a linear decrease from 135 °C to 70 °C between 170 min and 290 min. Subsequently, it may decrease linearly from 70 °C to 50 °C between 290 min and 340 min. Finally, the temperature experiences a linear decrease to reach room temperature.

[0043] The pressure profile can be starting at 1 bar and may be increasing up to 10.8 bar around 110 min. It particularly remains constant until 170 min, after which there can be a linear decrease to 10.3 bar up to 290 min. A slight linear decrease particularly follows, reaching 11.2 bar at 340 min. The pressure then particularly normalizes before returning to atmospheric pressure.

[0044] The embodiment described above allow after being adapted in light of the present invention to improve the laminating of liquid fluid / crystal layer containing liquid fluid cells to form laminates. Particularly using flatbed lamination instead of the above-described processes (autoclave, vacuum bag, hotbox) allows manufacturing of high-quality LCWs by addressing issues related to temperature and pressure variations during lamination using the described alternative techniques. Furthermore, flatbed lamination can be preferred over autoclave lamination as the latter can be less suitable for LCWs also because it can require a NIP roll mechanical degas / prefix process. Finally, the stack can be cooled down to ambient temperature to harden the interlayer material and fix the stack. In an embodiment where autoclave processing under high pressure is used, this step can also freeze the dissolved state of gas residues in the interlayer material to further ensure a bubble-free laminate.

[0045] To achieve good quality laminates, maintaining sufficient process parameter uniformity and providing enough time for the process dynamics to accomplish the desired process status and to diminish any non-uniformities over the product can be performed. The presence of a fluid layer in liquid crystal cells particularly creates extra boundary conditions in the lamination process compared to regular glass substrates used in (architectural) safety glass lamination. These particularly include maximum pressure and pressure non-uniformity levels, as well as restricted temperature dynamics and temperature non-uniformities. Therefore, the manufacturing of liquid crystal window cells requires careful consideration of these factors to ensure a high-quality end product.

[0046] Controlled pressing particularly refers to a method of applying uniform pressure to a product during lamination, in order to ensure consistent thickness and quality of the final product. This is particularly achieved through the use of press plates, which in addition can be heated or cooled to a uniform temperature, and controlled by air pressure to provide pressure uniformity over the entire process area, regardless of the (lateral) size or shape of the product. The goal is to create a bubble-free and stress-free laminate with good quality.

[0047] Controlled thermal load particularly refers to the use of heat in a controlled manner during the lamination process. This can include heating or cooling the press plates to a uniform temperature, as well as controlling the rate of heating and cooling to ensure consistent temperature uniformity over the entire product area. Faster ramping up and cooling down rates with better temperature uniformity can be achieved, particularly independent of the (lateral) size or shape of the product.

[0048] Controlled pressing based on the preferred mode of flatbed lamination or using the preferred device of a flatbed laminator particularly involves a process area between two heated or cooled parallel press plates, even giving the possibility for batch processing of multiple laminates. The press plates can be controlled by air pressure and provide pressure uniformity over the entire process area, independent from the product dimensions or shape. The heating press plates can be heated with a + / - 2 °C uniformity over the total process area over a temperature range of 20 to 150 °C. The cooling press plates can have a uniformity of + / - 2 °C over the total process area in a temperature range of 10 to 60 °C, particularly 20 °C to 40 °C. The heating up and cooling down of the product can be performed by heat conduction from the top side and the bottom side simultaneously to allow faster ramping up and cooling down rates (between 10 to 50 min) with better temperature uniformity over the total product area. The temperature uniformity is particularly higher with parallel plates. The ramp up rates and ramp down rates are particularly faster when using the controlled press principle in flatbed lamination, compared to alternative solutions described elsewhere herein. In other embodiments uniform pressing may also be achieved using e.g. a vacuum bag technique.

[0049] Vacuum bag lamination and autoclave lamination are particularly two different types of lamination processes that involve applying heat and pressure to a product in order to bond layers together.

[0050] Making bubble-free laminates particularly comprises a degassing and / or dissolving gases in the stack. Autoclaving particularly uses NIP roll mechanical (incomplete) degassing and prefixing in combination with autoclave high pressure dissolving gas residues at high temperature. Vacuum bag or hot box particularly comprises a vacuum degassing step by the hot box (no high-pressure atmosphere). Vacuum bag techniques particularly may use vacuum degassing particularly followed by autoclave using high temperature with relatively higher pressure (2-3 atm particularly).

[0051] In vacuum bag lamination, a vacuum can be applied to the product to remove gases such as air and / or water vapor and to create adequate pressure, particularly to avoid the high pressure levels needed in autoclaving to dissolve remaining gasses, while in autoclave lamination, the product can be placed in an autoclave and can be subjected to high pressure and temperature. Both processes can be performed in a convection heating system. The ramp up rate can be between 90 to 120 min and the ramp down rate can be between 120 to 180 min.

[0052] In an embodiment for liquid crystal cell lamination, the term "low pressure" may in particular refer to the restrictions on the pressure level for laminating liquid crystal cells, which is particularly limited to 1.0 bar to 2.0 bar due to the mechanical load limitations of LC cells. In standard autoclave lamination, a mechanical degassing process using NiP rolling at 3 bar to 7 bar followed by high pressure autoclave exceeding 10 bar can be used. To meet the maximum pressure level requirements for laminating LC cells, a vacuum degassing method by a vacuum bag method or by using a vacuum process in a flatbed laminator to perform flatbed lamination is provided to avoid gas bubble formation in the stack and in particular in the interlayer(s) and at the interface(s) of the lamination interlayer(s) and the substrate(s) during the lamination process. Flatbed lamination particularly involves degassing of the (pre-)lamination stack by vacuum at 1 mbar to 500 mbar, preferably in the range of 1 mbar to 50 mbar, for a time window of 5 min to 30 min. Softening of the interlayer material typically occurs at elevated temperatures between 20 °C to 90 °C, and the glass surfaces can be contacted with the interlayer material by mechanical pressing at between 0 bar to 1.5 bar (excluding border values), preferably in the range of 0.2 bar to 1.0 bar, particularly for a period of 10 min to 30 min. The interlayers can then be adhered to the glass surface at high temperatures, particularly between 110 °C and 150 °C, preferably between 110 °C and 130 °C, particularly for a time period of 10 min to 50 min. Controlled cooling can be applied between the top temperature (110 °C to 150 °C) and 90 °C to avoid thermal stress in the stack. Fixation of the different layers can be achieved by cooling down to ambient temperatures, particularly with a total cooling down time of 10 min to 80 min, preferably between 20 min to 40 min. In particular embodiments, the bottom and top plates can be set to different temperatures to create homogeneous temperatures in unsymmetric stacks. In embodiments, a vacuum bag and hot box can be used for degassing the lamination stack by reducing the pressure to between 1 mbar to 500 mbar, preferably within the range of 1 mbar to 50 mbar. The degassing process can be carried out for a time window of between 30 min to 180 min, with a particular duration of 120 min to 180 min. This can be followed by softening the interlayer at a temperature range of between 20 °C to 80 °C and adhering it to the substrate, particularly a glass substrate, using a vacuum bag pressure within the range of 50 mbar to 150 mbar, particularly around 130 °C to 140 °C. The process can take place over a time span of 30 min to 180 min. Finally, different stack layers - in embodiments, wherein a stack layer is provided and / or manufactured - can be fixed by slowly cooling down to 40 °C over an extended timespan of 120 min to 180 min, particularly with a controlled thermal load and even distribution of pressure and temperature over the fluidic cell. The extended time span, the controlled thermal load and the even distribution of pressure over the fluidic cell as well as the even distribution of temperature over the fluidic cell may be as described elsewhere herein with respect to the same, similar or different embodiments.

[0053] Here and elsewhere herein, a fluid is a type of liquid material that can exhibit certain characteristics and properties, making it suitable for use in various applications described elsewhere herein. It particularly has a phase between its crystallization point and evaporation point, typically ranging from -40 to 150 °C or more, particularly with a viscosity that is below infinity. This means that the liquid material is capable of flowing and conforming to the shape of its container. Additionally, it may be in a liquid crystalline phase, specifically a (chiral) nematic or smectic phase, preferably a nematic phase or chiral nematic phase, which can exhibit unique optical properties. In some embodiments the liquid may also contain solid parts, such as polymeric materials, with contents of 30 % by weight or less being preferred. The presence of these solid parts can alter the fluid's viscosity and other physical properties. It is preferred that the liquid does not contain solid parts. One particular key characteristic of the fluid is its ability to change its optical properties based on changes in layer (non-)uniformity, in particular the thickness of the layer (also known as cell gap), or when the shape of the container is altered. Thus deviations in the fluid layer thickness may negatively affect optical properties, particularly in the sense of unwanted artefacts or inhomogeneities in transmission and the like.

[0054] Switching of optical states in LCWs is particularly based on a change of the orientation of the LC molecules in the LC cell, either and preferred in response to at least one of an absence, a presence, or a change of an electric field or alternatively in response to a change in temperature, in particular from the nematic phase to the isotropic phase, i.e. across the phase transition temperature. The laminate stacks resulting from the method of laminating may show reduced optical artifacts or defects or they may in particular be artifact-free.

[0055] The optical homogeneity of the resulting product can be defined as the homogeneity of the cell gap in the liquid fluid cell, also for cases where two liquid fluid cells are contained in a laminate stack. Homogeneity in the liquid fluid cells in the laminates according to the invention can be less than 10% over the surface of the liquid fluid cells, preferably less than 5%. The resulting optical homogeneity of the laminate stack can give a value of delta E* of below 10 (delta E* defined by CIE 1976), more preferably below 5, but particularly below 2.3, where 2.3 is the limit for the human eye to see a difference in color. Delta E*, often written as dE* or AE*, is a measure of the perceived color distance (color difference) that is "equivalent" for all colors that occur. The delta stands here as a sign of difference.

[0056] As described herein, the provision of liquid fluid cells which exhibit underfill / underpressure can give beneficial effects both during lamination and in the laminated product.

[0057] Therefore, in the step of providing the liquid fluid cell and arranging the provided cell in the stack, the liquid fluid cell may have a defined underpressure and / or a defined underfill of a liquid fluid, particularly a liquid crystal material, in the liquid fluid cell.

[0058] A structure comprising at least one liquid fluid cell may comprise a liquid fluid cell, which can be designed to have a defined underpressure and / or a defined underfill, preferably both, of a liquid fluid in the liquid fluid cell. The distinction between the terms underpressure and underfill is described below.

[0059] The term underpressure particularly refers to a condition where the pressure inside the liquid fluid cell is lower than it would be with ambient pressure of the liquid fluid cell, particularly when the cell is filled up to a geometric capacity of the liquid fluid cell. Filling of the liquid fluid cell can be carried out using so-called vacuum filling, where a (partial) vacuum is created inside the cell and subsequently the cell is filled with the liquid fluid, in particular the liquid crystal. To obtain and set the desired underpressure, after the filling a pressing is applied to the cell, wherein this post-fill pressing in particular compresses the plastic material, in particular the spacers, and the resulting deformation stress generates the underpressure. This underpressure can help to maintain the shape and stability of the cell gap during manufacturing of the laminate and also in the use of the obtained laminated product, e.g. as used in building fagades or automotive applications. Alternatively, so-called one drop filling may be used for providing the liquid fluid layer in the cell, where the desired amount of the liquid fluid may be set the respective dispensing volume. Underpressure can particularly refer to the internal pressure within the liquid fluid cell that can be created during the preparation of the liquid fluid cell. This pressure can be greater than the forces applied by the environment, such as gravity and lamination stress particularly caused by non-flatness of the cover substrate, particularly the cover glass, as well as application stress caused by frames or other (building construction) elements. The underpressure should particularly be in the range of 0 bar to 0.9 bar (borders excluded), with a typical range of 0.15 bar to 0.8 bar. A technically reasonable upper limit for underpressure particularly does not exceed 1 bar where ambient pressure is normal. In alternative cases where higher ambient pressure is present, the underpressure may also exceed this limit while however being below the ambient pressure. Achieving the correct level of underpressure can be beneficial for the performance of the liquid fluid cell and the assembled stack altogether during lamination and of the product after lamination.

[0060] Thus during the production of the liquid fluid cell an underpressure or negative pressure is preferably set. When vacuum filling is used, pressure can be applied to the cell after filling to generate the underpressure. This can help to achieve a more uniform cell gap and thickness of the liquid fluid layer, in particular the liquid crystal layer, which in turn can improve the optical properties and overall quality of the final product upon lamination. The pressing or pressure applied to the filled cell can e.g. be between 100 mbar and 2000 mbar, preferably between 200 mbar and 1500 mbar.

[0061] The term underfill particularly refers to a condition where the liquid fluid within the liquid fluid cell is completely filled in the sense that there are no voids or bubbles in the cell gap remaining, but not up to the holding capacity of the geometric structure e.g., a geometric expansion where the cell spacers would be relaxed (which would allow more fluid inside the cell gap). The term underfill does not imply that there are parts in the cell that do not have a fluid and thus voids. Underfill is particularly defined as the ratio between the volume of the container (area of the glass multiplied by the cell gap) divided by the designed volume of the container (area of the glass multiplied by the spacer diameter). Applying this principle may result in an underfill that helps to reduce deformation in the cell during lamination. Underfill can be a particularly crucial aspect in the manufacturing of liquid crystal windows for architectural applications. It can refer to the thickness of the liquid layer that is present between the two fluid cell substrates divided by the size of the distance holder (the spacer or spacers) placed between them. The underfill enables to overcome or compensate the thermal expansion of the liquid material, so that at elevated temperatures during processing and application, the liquid volume, in particular the LC volume in the cell gap, remains below 100% of the cell design volume. Typically, the elevated temperatures encountered in processing are below 150 °C, while in particular embodiments they can be below 110 °C. The underfill range is particularly between 80% and 100% (borders excluded), preferably between 90% and 99%, and more preferably 94% to 97.5%, where plastic or physical deformation of the spacers may occur at around 80% underfill at room temperature, which herein is particularly taken to mean 20 °C.

[0062] Both underpressure and underfill can help to improve the stability and uniformity of the liquid fluid cell structure during lamination and during temperature loading in the laminated product, in particular the LCW as used e.g. in architectural and automotive applications, by reducing deformation in the cell and ensuring a more even distribution of liquid fluid throughout the liquid fluid cell and during thermal loading in the LCW.

[0063] In the present lamination method it is therefore preferred to provide the liquid fluid cell(s) with a suitable underfill and / or underpressure.

[0064] According to an aspect the interlayer can comprise a lamination foil, particularly a PVB lamination foil. The use of a lamination foil, particularly a PVB lamination foil, can provide additional strength and stability to the overall structure, particularly in applications where the layers are exposed to high levels of stress or load.

[0065] A lamination foil may be a material or layer that is used to fill any gaps or spaces between two other layers or materials during the lamination process. The lamination foil particularly serves to bond the layers together and provide additional structural integrity or stability to the overall structure. In an embodiment, the lamination foil can be made of any suitable material, such as polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). A "PVB lamination foil" refers to a specific type of lamination foil that can be made of PVB material. The PVB lamination foil typically consists of a thin, flexible PVB sheet, which preferably is not coated on any side with an adhesive layer. In particular, the lamination materials referred to herein do not represent adhesives such as clear optical adhesives or glue. During the lamination process, the lamination foil, in particular the PVB lamination foil, can be positioned between two other layers (such as glass substrates) and subjected to heat and pressure, causing the lamination layer or foil to bond the layers together. In embodiments, the interlayer may not fully reach the edge of the substrate and a void can be created. According to an aspect, the substrate can be laminated to a liquid fluid cell structure. The liquid fluid cell structure can comprise at least a second liquid fluid cell, wherein the substrate is laminated to either a first cell substrate or a second cell substrate of the second liquid fluid cell using a lamination layer. Alternatively or additionally, the substrate can be either one of a first cell substrate of the at least second liquid fluid cell, a second cell substrate of the at least second liquid fluid cell or a coversheet, particularly facing an exterior space. Alternatively or additionally, a symmetrical and / or unsymmetrical lamination stack can be built up.

[0066] Particularly for liquid crystal windows, further particularly for architectural applications, the orientation of the substrates during lamination can be important. Specifically, the substrate can be laminated to the cell substrate either facing an exterior space or the substrate comprising a second cell substrate of another, particularly a second liquid fluid cell. The latter process particularly involves the use of two cell substrates, each with its own set of layers and properties, which are combined to form a lamination stack. The exterior space to the contrary may be the free space outside a window or outside of a lamination stack.

[0067] In respective embodiments a coversheet and two liquid fluid cells can be provided. In other embodiments, such as for specific privacy applications, the lamination stack may contain a first coversheet, a liquid fluid cell, and a second coversheet opposite the first coversheet, where lamination layers are provided between the first coversheet and the cell and between the second coversheet and the opposite surface of the cell. For certain applications it might be desired or advantageous to have coversheet-cell-cell-coversheet or even coversheet-coversheet-cell-cell arrangements, or any combination thereof.

[0068] The term "cell substrate" refers to the individual substrate used in the construction of a liquid fluid cell, particularly for a liquid crystal cell for a light transmission switchable window, particularly made from glass or another transparent material. This substrate can define at least partially the optical properties of the final product, as well as providing mechanical stability and support for the liquid fluid layer, particularly the liquid crystal layer. In a preferred embodiment the cell substrates are made of glass.

[0069] When referring to the orientation of the substrates during lamination, "facing an exterior space" particularly means that one of the substrate’s surfaces is positioned so that it forms the outer surface of the final product, while the other substrate’s surfaces particularly faces the interior space of the fluid liquid cell, particularly the cell gap. In contrast, when a cell substrate forming part of a second fluid liquid cell is used, it is typically placed facing another cell substrate of the first liquid fluid cell.

[0070] As indicated elsewhere herein, there is quite a variety and flexibility of designs for a laminate. A single cell (two substrates with one LC layer) or a so-called double cell (two LC layers with substrates) can be realized. There can also be cover-sheets, and further integration of the laminates into double glazing, triple glazing and insulated glazing units. Lamination can connect a cell to a cover sheet or a cell to another cell or both. The stack is particularly arranged for (mainly) optical, but also mechanical, safety and / or thermal aspects, among others. In other exemplary embodiments there can be a liquid fluid cell plus cover sheet for safety aspects, a double cell for optical purposes, e.g. to set a desired contrast or change in transmission between the switchable optical states, and / or a combinations of all these implementations.

[0071] Particularly in the context of manufacturing liquid fluid cells, particularly manufacturing liquid crystal windows for architectural applications, but also with respect to other applications described elsewhere herein, the method may involve combining different lamination techniques to improve the results, particularly with respect to the optical properties of the resulting products.

[0072] The term "flatbed lamination process" refers to a preferred technique used in the manufacturing of liquid fluid cells, particularly for windows which can be switchable e.g., with respect to their optical properties such as their transmission for certain wavelengths and / or the visible spectrum. Therein, two or more layers are bonded together under heat and pressure on a flat surface, typically using an interlayer, particularly the lamination layer as described elsewhere herein. A lamination process is particularly used in the production of laminated glass for architectural applications, as it allows for precise control over the bonding parameters, such as temperature, pressure, and dwell time, to ensure high-quality bonding between the layers of the substrate and the cell substrate. In an embodiment, the substrate may be at least a glass substrate or may be made from a polymer material, preferably a glass substrate. As described elsewhere herein, the substrate may comprise a cell substrate of at least a second liquid fluid cell, particularly to form a lamination stack. The flatbed lamination process allows for a more consistent and uniform cell gap distribution, particularly resulting in fewer defects and improved overall product quality. According to an aspect, a step of pressing the assembled stack including the liquid fluid cell with a defined pressure can be performed. The pressure, in particular for flatbed lamination, may preferably be between 50 mbar and 1500 mbar, more preferably between 100 and 1000 mbar, even more preferably between 150 mbar and 800 mbar and most preferably between 200 and 600 mbar. This process particularly involves applying a defined pressure to the arranged components during lamination of the components forming the lamination stack, particularly to ensure proper adhesion, exclusion of voids at interfaces, uniform thickness, and consistent optical properties therein.

[0073] A "step of pressing the assembled stack including the liquid fluid cell " particularly refers to a specific stage in the laminating process to form and bond or cure a lamination stack where pressure is applied to the arranged components to create a bonded or laminated lamination stack structure - also referred to as a laminated structure, including cases where several (at least two) liquid fluid cells are provided therein. This step may involve using specialized equipment or machines to apply the necessary pressure, such as hydraulic presses or vacuum-assisted lamination systems, depending on the specific application and requirements of the lamination stack to be laminated.

[0074] The "defined pressure" used in this pressing step in connection with the lamination can vary depending on the specific needs and characteristics of the laminated product containing the liquid fluid cell being produced. In some cases, in particular when using a flatbed laminator, the pressure may be between 50 mbar (millibars or hectopascals) and 1500 mbar, preferably between 100 mbar and 1000 mbar, with a further preferred range being between 150 mbar and 800 mbar and most preferably between 200 and 600 mbar. This range of pressures can provide an optimal balance between ensuring proper adhesion of the interlayer as lamination layer to the components to be connected / laminated together and uniformity of the cell components while avoiding damage to the sensitive cell gap for the liquid crystal layer.

[0075] In embodiments the controlled pressing in the step of laminating particularly comprises a pressure between 50 and 1500 mbar, preferably 100 mbar and 1000 mbar, particularly between 150 and 800 mbar, further particularly between 200 and 600 mbar. The pressing may refer to pressure applied during the lamination process.

[0076] This can help to achieve a more uniform cell gap and thickness of the liquid crystal layer, which in turn can improve the optical properties and overall quality of the final product upon lamination. Additionally, applying a lower pressure during laminating can also help to reduce the risk of damage to the cells or substrates, and can make the overall manufacturing process more efficient. In other words, the lamination does not introduce adverse effects that would become visible upon lamination after a liquid fluid cell is manufactured based on higher pressures described here and elsewhere herein.

[0077] By applying a specific range of pressure during laminating, it is possible to keep a more uniform cell gap and thickness of the liquid fluid / crystal layer, which in turn can improve the optical properties and overall quality of the final product. Additionally, applying the adequate amount of pressure during laminating can also help to minimize any potential deformation or distortion of the substrates or damaging the liquid fluid cell(s), and can make the overall manufacturing process more efficient. The specific range of pressure used may depend on various factors such as the type of liquid fluid cell being laminated, the thickness of the layers involved, and the desired optical properties of the final product.

[0078] In summary, the pressing step can be an aspect of laminating a substrate to a liquid fluid cell, such as a liquid crystal cell for architectural applications. By applying a defined pressure during this step, laminating can create solidified and uniform lamination stack structures with consistent optical properties, adhesion, and thickness. The specific range of pressures used may vary depending on the requirements and characteristics of the particular liquid fluid cell being produced, with isolating this step in the lamination process allowing for more precise control and optimization of the pressure applied.

[0079] According to an aspect the method may comprise a controlling during the step of lamination at least one of the temperature increase or temperature decrease in the liquid fluid cell and the entire lamination stack. Particularly the controlling may be performed by controlling the temperature inhomogeneity through the lamination stack including the liquid fluid cell, further particularly controlling at least one of a top-bottom temperature distribution or a lateral temperature distribution. In the context of manufacturing an LCW containing a liquid fluid cell, such as a liquid crystal cell for architectural applications, an important aspect involves controlling the temperature during the lamination process to ensure consistent and uniform properties throughout the lamination stack including the cell. This may involve controlling the rate and extent of temperature increase or decrease within the cell, particularly by managing temperature inhomogeneities across its topbottom and lateral dimensions. In this respect, deformation and in particular deformation of a layer or deformation in a layer, in particular in the cell, caused by one or more other layers in the stack may be minimized by the controlled and uniform application of pressure and / or temperature as described herein. The term "controlling" refers here particularly to purposively setting and adjusting the temperature during the lamination step to achieve desired results, wherein in a particular embodiment the temperature can be actively monitored and regulated. This can be achieved through various means, such as adjusting heating or cooling parameters, controlling the temperature distribution within the to-be-laminated-on liquid fluid cell, or implementing specific temperature control strategies tailored to the particular liquid fluid cell being laminated.

[0080] "Controlling during the step of lamination" particularly refers to the process of managing and monitoring temperature during the laminating operation, which particularly involves applying pressure and heat to the stack including liquid fluid cell’s components to create a uniform laminated structure, particularly a lamination stack, also in cases where at least two liquid fluid cells are laminated to each other. By actively controlling the temperature dynamics during this step, it is possible that the product comprising the laminated liquid fluid cell can be produced with consistent properties, reduced defects, and improved overall quality and reliability.

[0081] Controlling the temperature (in)homogeneity through the liquid fluid cell and more generally through the assembled stack comprising the cell specifically involves managing any uneven temperature distributions across the top-bottom or lateral dimensions of the stack and the cell during lamination. This can be achieved by carefully regulating the heating or cooling parameters, adjusting the pressure applied to the cell, or implementing specific temperature control strategies that minimize temperature gradients within the assembled stack and the liquid fluid cell to be laminated. By controlling temperature inhomogeneities, the risk of non-uniform coloration, deformation, or other defects in the final product can be reduced.

[0082] "Controlling a top-bottom distribution" particularly refers to managing any uneven temperature distributions across the vertical (top-bottom) dimensions of the assembled stack and the liquid fluid cell comprised in the stack during lamination, in particular during flatbed lamination. This can be achieved by carefully regulating heating or cooling parameters, adjusting the pressure applied to the stack including the liquid fluid cell, or implementing specific temperature control strategies tailored to minimize temperature gradients along this axis. Controlling top-bottom temperature distributions is particularly considered in applications where thermal stress induced during lamination may cause deformation or non-uniform layer thicknesses. "Controlling a lateral temperature distribution" specifically refers to managing any uneven temperature distributions across the horizontal (lateral) dimensions of the layers in the stack and in particular the liquid fluid cell comprised in the stack during lamination, in particular during flatbed lamination. This can be achieved by carefully regulating heating or cooling parameters, adjusting the pressure applied to the assembled stack comprising the cell, or implementing specific temperature control strategies tailored to minimize temperature gradients along this axis. Controlling lateral temperature distributions is particularly considered in applications where thermal stress induced during lamination may cause deformation or non-uniform layer thicknesses in the liquid fluid cell and can also impact the overall dimensions and shape of the final product. Heating via a uniform press plate can also induce homogeneous lateral temperature.

[0083] According to an aspect a flatbed laminator can be equipped with temperature-controlled flat heating or cooling press plates in the thermal stages of a heating step. The flatbed laminator equipped with temperature-controlled flat heating or cooling press plates can be used in the thermal stages of a heating step for the method of laminating the liquid fluid cell to at least one substrate.

[0084] A flatbed laminator is a type of equipment particularly used in the lamination process that may involve laying down multiple layers of materials on a flat surface and applying heat and pressure to bond them together. The flatbed laminator particularly consists of heating and cooling plates, which are used to apply thermal energy to the layers being laminated, as well as pressing plates that apply the necessary pressure to bond the layers together.

[0085] When other laminators are used, e.g. an autoclave, instead of stacking the layers on top of each other where each layer is arranged horizontally, the layers may be arranged as a stack on a vertical rack standing upright where each layer in the stack is arranged vertically.

[0086] The expression "equipped with temperature-controlled flat heating or cooling press plates" particularly refers to the ability of the flatbed laminator to regulate the temperature of its heating or cooling plates, allowing for precise control over the thermal energy being applied to the layers during the lamination process. This can help to ensure that the layers are heated or cooled evenly and to the desired temperature, which is important for achieving a consistent cell gap and thickness of the liquid fluid / crystal layer and / or to remain at a, particularly predefined, cell gap with predefined thickness during lamination. The "thermal stages of a heating step" refers to the various stages in the lamination process where heat is applied to the layers being bonded together. These stages may include pre-heating, temperature regulation, and post-curing, among others. During these stages, the flatbed laminator's temperature-controlled heating or cooling plates can be used to apply thermal energy to the layers in a controlled and precise manner.

[0087] According to an aspect the liquid fluid cell(s) can comprise a cell gap between 1 to 100 pm, preferably 2 to 50 pm, more preferably 5 pm to 30 pm, in particular 7 to 25 pm. Preferred embodiments relate to the use of a liquid fluid cell that comprises a cell gap between 5 pm and 30 pm, particularly in a method of laminating. The cell gap is in particular a parameter in the manufacture of liquid fluid cells, as it can affect the optical properties of the final product.

[0088] To maintain a proper thickness of the cell gap and thus of the switching layer, spacers may be included within the cell gap. Typically, the spacers have a spherical shape with a diameter in the range of the cell gap. For example, non-conductive spacers having a spherical shape with a predetermined diameter made of polymer or glass may be used. In some embodiments it may be useful to provide sticky spacers, i.e. spacers which have some intrinsic adhesive characteristic to better adhere to the surface. Alternatively, the cell thickness may be set or maintained by other suitable means, e.g. by using wall spacers or column spacers. The column spacers may also be formed to give compartments, thus optionally allowing for free-cuttable structures.

[0089] According to an aspect a temperature isolation layer can be provided during the step of laminating. Embodiments can relate to the use of a temperature isolation layer during the step of laminating the liquid fluid cell onto at least one other substrate. The temperature isolation layer is particularly a material or structure that can be placed between the substrates involved in the liquid fluid cell and can be designed to provide thermal insulation between them. Preferably the isolation layer, in particular in flatbed lamination, is placed between the press plates, especially the bottom press plate, and the lamination stack.

[0090] The temperature isolation layer can be made from various materials, such as polyethylene, polystyrene, felt or other thermally insulating materials. The layer may have a thickness in the range of 10 pm to 500 pm, depending on the specific application and desired properties of the final product. The isolation layer can be used to equalize thermal contact over the total product area and to reduce the heat transfer flow in order to reduce temperature differences in the laminate (lateral and top bottom). This can help to reduce the risk of thermal stress or other issues that can affect the optical properties of the final product. By maintaining a consistent temperature across the surface of the laminate, the temperature isolation layer can also facilitate more uniform curing and bonding between the layers involved in the liquid fluid cell laminate and / or lamination stack.

[0091] According to an aspect a lamination temperature can be set between 70 °C and 150 °C, particularly between 100 °C and 140 °C, further particularly between 120 °C and 130 °C. A specific lamination temperature range can be used during the laminating of the liquid fluid cell to the substrate. This lamination temperature can be set within a range of 70°C to 150°C, with particular temperatures between 100°C and 140°C, further particularly temperatures between 120°C and 130°C.

[0092] The lamination temperature particularly represents a parameter in the manufacturing of LCWs containing liquid fluid cells, particularly as it affects the bonding and curing of the layers involved in the liquid fluid cell lamination. A lamination temperature that is too low may result in poor adhesion or bonding between the layers, while a lamination temperature that is too high may cause thermal stress or other issues that can adversely affect the optical and mechanical properties of the final product. By selecting an appropriate lamination temperature within the preferred range, it is possible to achieve more uniform and reliable bonding between the layers involved in the laminate and / or lamination stack.

[0093] According to an independent aspect a method of manufacturing a liquid fluid cell is provided which particularly comprises at least one of an underfill and underpressure. The preparation of the cell may comprise the step of applying pressure to a first and a second cell substrate spaced apart by at least one spacer. The method may comprise filling the liquid fluid cell until it reaches at least one of a predefined underfill or predefined underpressure. Features, technical effects, and advantages described with respect to either method may also apply to devices, systems, or their respective use. This also applies the other way around. Therefore, throughout the description, cross-referencing can be used or is used to describe aspects and embodiments described with respect to one category to also describe aspects and embodiments with respect to another category. It may also be possible to transfer features from their respective individual link they are described in to specify embodiments or aspects of the same or a different category.

[0094] A method of manufacturing a liquid fluid cell particularly involves providing at least two cell substrates configured to be positioned relative to each other to form a cell gap for containing or filling with a liquid fluid, such as a liquid crystal material. This process can involve the use of spacers, which are specifically designed and configured to define the thickness of the cell gap between the cell substrates during the lamination process and in the obtained product. By using this approach, high-quality liquid crystal cells can be produced with consistent properties and reduced defects, thereby improving the overall quality and reliability of these cells for various architectural applications, particularly for a method of laminating a liquid fluid cell with a substrate, particularly using a lamination layer as described elsewhere herein.

[0095] Embodiments relate to a method for manufacturing a liquid fluid cell, such as a liquid crystal window cell. This method comprises filling the liquid fluid cell until it reaches at least one of a predefined underfill and predefined underpressure. In case vacuum filling is used, the filling is followed by the application of pressure. In particular, in this case the method comprises applying pressure to a first and a second substrate that are spaced apart by at least one spacer. In case the liquid fluid, in particular the LC material, is provided by one drop filling (ODF), single droplet deposition or patterning may be applied to place a defined amount of liquid fluid to at least one substrate and to then form the cell by covering with a second cell substrate, typically performed under vacuum conditions.

[0096] The term "underfill" particularly refers to a predetermined amount of liquid fluid that is intentionally deposited in the cell gap between the substrates, typically less than the full design volume of the cell gap. The term "underpressure" refers to a predetermined pressure level within the cell, which is particularly lower than the pressure exerted by the surrounding environment and / or particularly less than the intended final pressure in the cell gap upon laminating the liquid fluid cell to at least one substrate. With respect to underfill and underpressure the definitions and descriptions as described elsewhere herein may also apply.

[0097] The method described above is the preferred method to provide liquid fluid cell as used in the method of laminating the liquid fluid cell. By actively controlling the amount of liquid fluid and / or pressure within the cell during manufacture benefits can be obtained during the subsequent lamination, which involves applying heat and pressure to bond a cell substrate (and therewith the liquid fluid cell) with at least one substrate layer - as the laminate - together. By using an underfill and underpressure, it is possible to achieve more precise control over the optical properties of the final product, particularly wherein the defined and desired pressure and fill level is reached. The method of manufacturing a liquid fluid cell allows to provide the liquid fluid cell to a method of lamination as described elsewhere herein.

[0098] According to embodiments of a method of manufacturing the liquid fluid cell can be provided, such that the liquid fluid cell comprises at least two cell substrates configured to be positioned relative to each other to form a cell gap for filling with a liquid fluid. The liquid fluid can particularly be a liquid crystal material. Therein, a thickness of the cell gap can be defined by spacers particularly configured to be placed between the cell substrates to form the cell gap there-between. In the context of manufacturing liquid fluid cells, particularly liquid crystal windows for architectural applications, one important aspect may involve providing a method for creating / manufacturing fluid crystal cells with defined cell gaps using spacers. This approach allows for precise control over the thickness and uniformity of the cell gap, which is particularly for achieving high-quality and consistent liquid crystal cells.

[0099] A "method of manufacturing a liquid fluid cell" refers to a series of steps or procedures used to create a functional liquid fluid cell, particularly a liquid crystal cell, with specific dimensions, properties, and characteristics. This method can involve various techniques and processes, such as placing of cell substrates and spacers, bonding of the respective components and other steps for producing the final product, particularly in form of an isolated liquid fluid cell, particularly to be provided to the method of manufacturing the respective liquid fluid cell with a substrate, particularly another liquid fluid cell to form a lamination stack, further particularly for a window.

[0100] "At least two cell substrates configured to be positioned relative to each other to form a cell gap for filling with a liquid fluid" particularly refers to the components or layers that make up the cell structure of a liquid fluid cell. These cell substrates are typically made of materials such as glass, plastic, or other suitable substrate materials and are designed to be placed in close proximity to each other to create a defined cell gap.

[0101] A "spacer" is in particular a component or device used in the manufacture of liquid fluid cells to define and control the thickness of the cell gap between the at least two cell substrates. Spacers can be made from various materials, such as plastic or other suitable materials, and are particularly configured to be placed between the cell substrates. By using spacers, a uniform and consistent cell gap thickness can be created, which is particularly useful for achieving high-quality liquid crystal cells with uniform optical properties and reduced defects.

[0102] During the production of the liquid fluid cell, in particular after filling the cell using vacuum filling, a step of pressing out excessive liquid material or liquid volume, in particular LC material, from the liquid fluid cell with a defined pressure to form the liquid fluid cell can be performed. The pressure applied to the isolated cell may particularly be between 500 mbar and 2000 mbar, further particularly between 800 and 1500 mbar. The liquid fluid cell thus prepared may favourably be provided to the present method of laminating at least one cell substrate of the liquid fluid cell with at least one further substrate.

[0103] A "step of pressing out excessive LC volume from the liquid fluid cell" particularly refers to a specific stage in the manufacturing process of a liquid fluid cell where pressure is applied to the cell components. This step may involve using specialized equipment or machines to apply the necessary pressure, such as hydraulic presses, depending on the specific application and requirements of the liquid fluid cell being manufactured. In an embodiment this step of pressing is particularly performed in case vacuum filling is used for providing the liquid fluid, in particular the LC material, during the production of the liquid fluid cell, and is suitably performed after the filling of the cell and before the cell is completely sealed, such that excessive LC material may be removed from the cell layer containing the liquid fluid. In a particular embodiment where in the cell layer containing the liquid fluid spacers are used to set and maintain the cell gap or layer thickness, the pressing generates a compression of the spacers.

[0104] The "defined pressure" used in this pressing step can vary depending on the specific needs and characteristics of the liquid fluid cell being produced. In some cases, the pressure may be between 500 mbar and 2000 mbar, with a further particular range being between 800 mbar and 1500 mbar. This range of pressures can be used to reach sufficient LC press out to reach an underfill and may contribute to uniformity of the cell components while avoiding excessive stress or damage to the sensitive cell gap for the liquid crystal layer.

[0105] In summary, the pressing step can be an aspect of manufacturing a liquid fluid cell, such as a liquid crystal cell for architectural applications. By applying a defined pressure during this step, manufacturing can create solidified and uniform cell structures with consistent optical properties, and thickness, particularly when being at least partially filled with a liquid fluid layer. The specific range of pressures used may vary depending on the requirements and characteristics of the particular liquid fluid cell being produced. Particularly, it is thus possible to provide the respective liquid fluid cell for a method of laminating.

[0106] Pressing can also cause the underfill and underpressure in the cells, in particular by compression of the spacers in the cell or respectively the cell gap. According to an aspect the filled liquid fluid cell can remain open, at least with respect to so-called filling ports or inlet of an otherwise sealed cell, upon filling until the two substrates are pressed against the spacers. Additionally or alternatively, the filled liquid fluid cell can remain open upon filling until a determined pressure level can be reached on the spacers in the liquid fluid cell.

[0107] ODF processes can alternatively be performed, wherein a respective filling is obtained by placing individual droplets onto a cell substrate, in particular in a vacuum ambient, before closing the cell giving the desired amount of fluid material in the cell. After closing of the cell and venting of the ambient a desired underpressure may be obtained.

[0108] An aspect of the manufacturing of the liquid fluid cell therefore may involve managing the filling process to ensure that the liquid fluid cell is underfilled with liquid fluid to set the appropriate underpressure, particularly in view of the performance in the subsequent lamination process.

[0109] The expression "filled liquid fluid cell" particularly refers to a liquid fluid cell structure (or a predecessor thereto) wherein at least one of its compartments or chambers is at least partially or completely filled with a liquid fluid, such as a liquid crystal material. This may involve introducing the liquid fluid into the liquid fluid cell through an inlet. Sealing the cell to maintain the fluid within may be performed.

[0110] In this context, "underfilled" is to be understood as defined elsewhere herein in detail.

[0111] The filled liquid fluid cell can remain open upon filling until the two substrates are pressed against the spacers. This means that after introducing the liquid fluid into the cell, the cell is not immediately sealed or closed off completely, but instead remains open at least at the filling inlet(s) until the time when the two substrates are pressed against the spacers within the cell. Alternatively, the filled liquid fluid cell can remain open upon filling until a determined pressure level can be reached on the spacers in the liquid fluid cell. This means that after introducing the liquid fluid into the cell, the cell is in particular not immediately sealed or closed off, but instead can remain open until a certain pressure threshold is achieved within the liquid fluid cell, particularly measured with respect of the pressure to the spacers. The pressure level may be determined based on factors such as the nature of the liquid fluid, the size and shape of the cell, and the desired thickness of the liquid layer. By allowing the liquid fluid cell to remain open until this pressure level is reached, any excessive stress or deformation that might occur during filling can be minimized, leading to a more uniform and consistent final product.

[0112] The liquid fluid cell may be filled using a vacuum filling technique. Therein, the at least two substrates can engage with the spacers before filling the liquid fluid cell. In alternative embodiments droplet deposition onto at least a single substrate may provide the respective amount of liquid fluid (being particularly viscous enough for the droplet deposition) before the at least two substrates engage with the spacers.

[0113] According to an aspect an underfill in the liquid fluid cell can be between 80% and 99.9%, preferably between 85% and 99.75%, particularly between 94% and 97.5% (at 20 °C). Alternatively or additionally, an underpressure can be between 0.10 and 1 bar, preferably between 0.15 and 0.95 bar, further particularly between 0.20 and 0.80 bar. In the context of liquid fluid cells, such as liquid crystal cells for architectural applications, the aspect particularly involves managing the amount of underfill and underpressure within the cell during manufacturing.

[0114] An "underfill" in a liquid fluid cell refers to the difference between the volume of the liquid layer the liquid fluid cell is capable of holding e.g., in case the spacers are relaxed and the actual volume occupied by the liquid fluid layer upon compression of the spacers for example. It is particularly expressed as a percentage, with 100% particularly representing the ideal, nominal or desired fill level for the liquid fluid cell.

[0115] Particularly, an "underpressure" in a liquid fluid cell refers to the difference between the ideal or desired pressure within the liquid fluid cell upon laminating it with at least one substrate and the actual pressure measured within the liquid fluid cell upon manufacturing it. It is typically expressed in units such as bar or Pascals. It is preferred that the liquid fluid cell as provided in the assembling of the stack for lamination has an underpressure as defined herein. Therefore, preceding the lamination method, i.e. before further integration in the lamination process, it is preferred that during the preparation of the initial liquid fluid cell the underpressure of the liquid fluid layer in the cell is set and obtained as desired.

[0116] Embodiments of the invention involve managing the underfill and underpressure within the liquid fluid cell during cell manufacturing, in order to achieve a more uniform and consistent final laminated product, particularly after laminating the liquid fluid cell to at least one substrate. Particularly, an underfill in the liquid fluid cell can be between 80% and 99.9%, preferably between 85% and 99.75%, particularly between 94% and 97.5%, in particular determined at 20 °C. This means that the actual volume of the liquid layer within the liquid fluid cell can be within this range, relative to the intended or desired fill level for the liquid fluid cell after laminating it to at least one substrate. By maintaining an appropriate underfill level, the risk of non-uniform layer thicknesses or other defects in the final laminated product can be reduced or minimized, e.g. during operation of laminated LC window products at different ambient temperatures or under different solar irradiation conditions.

[0117] Additionally, an underpressure within the liquid fluid cell can also be managed during cell manufacturing. Specifically, an underpressure can be between 0.10 and 0.9 bar, further particularly between 0.15 and 0.80 bar. This means that the actual pressure measured within the liquid fluid cell can be within this range, relative to the ideal or desired pressure for the liquid fluid cell after laminating it to at least one substrate. By maintaining an appropriate underpressure level may lead to a more consistent and uniform final laminated product, particularly in the steps of de-gassing and lamination as described elsewhere herein.

[0118] Filling the liquid fluid cell can be performed in a method of manufacture, particularly during a method of manufacturing the liquid fluid cell. Embodiments relate to the use of a step of filling, at least partially, the liquid fluid cell during the method of manufacturing the liquid fluid cell. The filling step can be performed using various techniques, including single droplet deposition on at least one of the substrates, as well as vacuum filling techniques.

[0119] Single droplet deposition - also called one drop deposition or one drop filling (ODF) - can be a technique in which individual drops or droplets of the liquid fluid material are deposited onto at least one of the substrates involved in the cell. This can be accomplished using various methods, such as dispensing or printing, and allows for precise control over the amount of material being deposited. Single droplet deposition can provide a uniform distribution of the liquid fluid material within the cell, which can lead to improved optical properties and overall quality of the final product. Alternatively or additionally, certain patterns may be deposited onto at least one of the cell substrates.

[0120] In the ODF technique, the liquid crystal material is “dropped” onto one of the cell substrates using a precise dispensing system, such as a nozzle or a printing head. One droplet deposition, droplet printing and inkjet deposition may be used. ODF may in principle comprise inkjet deposition as well, since therein no large droplets can be placed anymore, but small inkjet droplets.

[0121] A step of dispensing the liquid crystal material may be performed, particularly using a controlled dispensing system, particularly comprising at least one nozzle and / or printing head. A small amount of liquid crystal material can be precisely dropped onto one of the substrates. The droplet's size and placement can be adjusted to ensure uniform coverage.

[0122] A step of aligning and bonding the cell substrates may be performed. The droplet-coated cell substrate can then be positioned opposite the other cell substrate, and they may be securely held together, typically with a temporary adhesive or clamping mechanism. This particularly creates an enclosed liquid fluid cell with the liquid fluid / crystal material sandwiched between the two (glass) surfaces. A step of sealing the liquid fluid cell may be performed. The liquid fluid cell can be sealed, particularly using a suitable sealing technique such as thermal compression bonding, ultrasonic welding, or a sealant, preferably using a sealant. A step of curing and finishing may be performed if necessary. Depending on the specific application requirements, the cell may undergo additional processing steps to cure any adhesives used in the bonding process. Examples of suitable materials for sealing of the cell(s) include epoxy-based sealants, polyurethanes, hot melt sealants and acrylates.

[0123] A step of preparing the substrates, in particular the glass substrates, may be performed. The glass substrates can be cleaned. The cell substrates, in particular the cell substrates made of glass, are typically coated with electrode layers, in particular using a transparent conductive material, e.g. a transparent conductive oxide, preferably indium tin oxide (ITO), SnO2:F or doped zinc oxide, in particular ITO, or a thin transparent metal and / or metal oxide layer, for example silver, to facilitate electrical connections for applying voltage to control the switching of the liquid crystal material. The electrically conductive layers are preferably provided with electrical connections, in particular busbars. The voltage is preferably supplied by a battery, a rechargeable battery, a supercapacitor or an external current source, more preferably by an external current source. In this respect, bonding of a terminal to a busbar may be achieved by soldering, welding, or use of a conductive adhesive or a conductive film. In particular, anisotropic conductive film bonding may be used to bond a flat cable as a terminal wire to the respective busbar. The terminals may be used to provide a connection to a controller or driver which generates a driving signal for controlling the state of the switchable medium located inside the electrooptical cell. The terminal may, for example, be configured as a terminal wire or a connector for attaching a wire.

[0124] It is preferred that the liquid fluid cells, in particular the LC cells, are electrically switchable, in particular by applying voltage or respectively an electric field. Electrical connections are particularly made to the electrode layers on the cell substrates, particularly not in a line of sight, and a voltage can be applied to control the orientation of the liquid crystal molecules. By adjusting the voltage, the liquid crystal material can be switched between different optical states, e.g. from a bright state to a dark state in solar dimming applications or from an optically clear state to a scattering or opaque state for privacy applications.

[0125] Furthermore, alignment layer such as polyimide alignment layers may be applied. In this respect, in order to orient or align liquid crystal molecules at the cell wall, i.e. the substrate surface, it is possible to use alignment layers, also known as orientation layers, to provide an interface which specifically causes or induces a predetermined or desired molecular orientation.

[0126] In an embodiment a lamination stack can be provided comprising at least one layer, particularly a glass substrate, at least one interlayer and at least two liquid fluid cells. By providing a lamination stack with two or more liquid fluid cells, it is possible to adjust the optical properties in the final product.

[0127] In general the present methods allows to adapt the lamination stack and the resulting window to given requirements e.g., with respect to size, shape and electronic configuration.

[0128] A substrate may be a material or layer that serves as a base or foundation for another layer or structure. In the context of the present invention, the substrate can be made of any suitable material, such as glass or plastic. Specifically, a "glass substrate" refers to a substrate made of glass material. The substrate, particularly glass substrate, may be the respective structure to laminate to a first liquid fluid cell with one of its cell substrates. In an embodiment the substrate may be the cell substrate of another, particularly a second, liquid fluid cell.

[0129] An interlayer may be a layer that is positioned between two other layers or materials, specifically a cell substrate and another substrate, which may be a cell substrate of another liquid fluid cell or a coversheet, particularly for the purpose of providing additional structural integrity or stability to the overall structure. In the context of the present invention, the interlayer can be made of any suitable material, such as polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). The interlayer may also be referred to as lamination layer in the context of other aspects as described elsewhere herein.

[0130] A lamination layer, in particular a PVB layer, as used in the method typically has a thickness in the range from 0.1 mm to 4 mm, preferably from 0.2 mm to 3 mm, and in particular from 0.3 mm to 2 mm. In a preferred embodiment the thickness of the lamination layer, in particular the PVB layer, is in the range from 0.4 mm to 2 mm, preferably from 1 mm to 2 mm, and in particular from 1.4 mm to 1.6 mm. In another embodiment the thickness of the lamination layer, in particular the PVB layer, is in the range between 0.4 mm and 0.8 mm.

[0131] A lamination stack may be a composite structure consisting of multiple layers that are bonded together through a lamination process. The lamination stack can be used for various applications, such as architectural glazing or automotive glazing such as windshields or sunroofs or glazing used in trains, airplanes etc. In the context of embodiments described herein, the lamination stack comprises at least one substrate, such as a glass substrate, from one liquid fluid cell, at least one interlayer, contacting at least a second liquid fluid cell’s cell substrate. In case two or more liquid fluid cells are provided in the stack, these cells can be arranged in any suitable configuration within the lamination stack, such as side-by-side or stacked on top of each other.

[0132] According to an independent aspect a liquid fluid cell can be manufactured by a method as described elsewhere herein. Features, technical effects, and advantages described with respect to either method may also apply to devices, systems, or their respective use. This also applies the other way around. Therefore, throughout the description, crossreferencing can be used and is used to specify the respective methods, devices, systems and their uses with respect to each other and with respect to the relationships between their different categories. Thus, individual features may be isolated from the described link to specify other embodiments or aspects as well - in the same or a different category.

[0133] The liquid fluid cell is particularly manufactured using a method comprising applying pressure to a first and second cell substrate spaced apart by at least one spacer. This process may involve filling the liquid fluid cell until it reaches at least one of a predefined underfill or predefined underpressure.

[0134] In contrast, a method of laminating a liquid fluid cell particularly involves applying heat and pressure to bond the layers - cell substrate and at least one other substrate - together, particularly without actively controlling the amount of liquid fluid or pressure within the liquid fluid cell. The method of manufacturing a liquid fluid cell with an underfill and / or underpressure provides more precise control over the optical properties of the final product, resulting in improved performance and consistency, as a desired and defined final pressure and / or final fill may be reached during lamination.

[0135] According to an independent aspect, a system may comprise at least one liquid fluid cell, at least one substrate, particularly glass substrate, and at least one lamination layer. Therein, the substrate can be laminated to the liquid fluid cell via a lamination layer, particularly by a method as described elsewhere herein. Features, technical effects, and advantages described with respect to either method may also apply to devices, systems, or their respective use. This also applies the other way around. Therefore, throughout the description, cross-referencing can be used or is used to describe aspects and embodiments described with respect to one category to also describe aspects and embodiments with respect to another category. It may also be possible to transfer features from their respective individual link they are described in to specify embodiments or aspects of the same or a different category.

[0136] The system may comprise at least one liquid fluid cell, at least one substrate (particularly glass), and at least one lamination layer. In this system, the substrate can be laminated to the liquid fluid cell via the lamination layer, particularly through a method described elsewhere herein.

[0137] The term "substrate" when used in connection with the liquid fluid cell, in particular “cell substrate”, particularly refers to a material that serves as the foundation or base for the liquid fluid cell. It can be made of various materials such as glass or plastic. The substrate is particularly used to support and protect the liquid fluid / crystal layer and preferably is transparent or substantially transparent.

[0138] The term "liquid fluid cell" particularly refers to an enclosed space containing a liquid fluid layer. In this description, it particularly refers to a liquid crystal cell used in windows for architectural applications and automotive and transportation applications. It can be made of glass or plastic substrates with a liquid crystal layer sandwiched between them.

[0139] The term "lamination layer" particularly refers to the material used to laminate the substrate to the liquid fluid cell. This layer can be made of various materials such as polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), thermoplastic olefins or thermoplastic polyurethane. The lamination layer may help to bond the substrate and the liquid fluid cell together, providing mechanical stability and protecting the liquid fluid / crystal layer from external factors. The lamination layer may also be made from polyolefin elastomers (POE), which preferably comprise a range of copolymers based on metallocene catalysis utilizing butene or octene comonomers. Key characteristics of POEs are their low hardness, low density and high impact / toughness.

[0140] The technical effect of this system particularly is to create a stable and secure structure that can withstand various environmental conditions and provide an aesthetically pleasing architectural feature. The advantages of this system include improved durability, enhanced optical properties, and increased energy efficiency compared to traditional glass structures. Furthermore, it may provide the means to switch windows in their transparency and / or their color.

[0141] One may refer back to the definitions provided elsewhere herein regarding substrate, liquid fluid cell, and at least one lamination layer. These terms are components describing the system accordingly. The technical effect and advantages described elsewhere herein apply to this system as well.

[0142] According to an aspect the substrate is particularly dimensioned in at least one direction of the lamination area such that the substrate forms a protrusion. This design enables e.g. the placement of a second liquid fluid cell, which provides an overhang over the first liquid fluid cell. The use of protrusions allows for the implementation of complex geometries and facilitates the integration of electrical connections and controlling electronics, especially electrical components such as wires, cables, busbars and / or connectors placed directly on the substrates, into the system. The substrate's protrusion in at least one direction creates a raised area on the surface, allowing for an additional layer of liquid fluid cells to be placed overhanging the first layer. This design feature can be advantageous in various applications where complex shapes or designs are desired, and it also offers the possibility of integrating electrical and electronic components within the system.

[0143] The placement of electrical components and controlling electronics on the protrusion provides an accessible location for these components without interfering with the overall functionality of the liquid fluid cells. This design allows for efficient control of the system while maintaining its aesthetic appeal and structural integrity.

[0144] According to an aspect at least one electrical / electronic component can be placed along at least a part of the protrusion. In embodiments, a system where at least one electronic component can be placed along at least a part of the protrusion formed by the substrate in at least one direction can be provided. The substrate's protrusion particularly creates a raised area on the surface, enabling an additional layer of liquid fluid cells to be placed overhanging the first layer.

[0145] By positioning electrical or electronic components along the protrusion, a compact and efficient configuration can be achieved without compromising the functionality of the liquid fluid cells. This design allows for improved accessibility to these components while maintaining the structural integrity of the entire system. Moreover, this approach enables seamless integration of electronics into the overall architecture, preserving the aesthetic appeal of the architectural feature. Furthermore the electronics do not interfere with line of sight through a window.

[0146] According to an aspect the lamination layer can be a lamination foil. Embodiments particularly relate to a system wherein the lamination layer can be a lamination foil. The term "lamination foil" particularly refer to a thin, flexible material commonly used in laminating processes to bond two or more layers together. This foil is particularly made from polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyurethane and particularly serves to provide mechanical stability, protect the liquid fluid cell from external factors, and enhance the overall performance of the system.

[0147] In this description, the lamination foil plays a critical role in bonding the substrate and the liquid fluid cell together, ensuring a uniform distribution of stress throughout the laminate. The use of a lamination foil allows for improved control over the lamination process, resulting in more consistent and reliable products. Furthermore, this approach enables the creation of various laminates with different thicknesses, colors, and optical properties, meeting the diverse requirements of different applications.

[0148] According to an independent aspect, a lamination stack comprising at least one system as described elsewhere herein, particularly manufactured by a method as described elsewhere herein, may be provided. The lamination stack may in an embodiment comprise at least two liquid fluid / liquid crystal cells, particularly as described elsewhere herein. Features, technical effects, and advantages described with respect to either method may also apply to devices, systems, or their respective use. This also applies the other way around. Therefore, throughout the description, cross-referencing can be used or is used to describe aspects and embodiments described with respect to one category to also describe aspects and embodiments with respect to another category. It may also be possible to transfer features from their respective individual link they are described in to specify embodiments or aspects of the same or a different category.

[0149] An embodiment particularly relates to a lamination stack comprising at least one system, particularly as previously described, and manufactured by a method particularly as described elsewhere herein. The lamination stack may in an embodiment consist of at least two liquid fluid cells, specifically designed for architectural applications, which can be integrated together using a lamination foil.

[0150] This lamination stack particularly offers several advantages. By carefully aligning and combining one or more liquid fluid cells with at least one other substrate, the overall performance, functionality, and aesthetic appeal of the system can be enhanced. The resulting lamination stack can exhibit unique optical properties, such as variable transparency or color, that make it suitable for various architectural applications. Moreover, this approach allows for the creation of complex designs and shapes in the laminated structure, opening up new possibilities for the use of liquid fluid cells in architectural settings. The use of a lamination stack also enables better control over the manufacturing process, resulting in more consistent and reliable products that meet the diverse requirements of different applications.

[0151] According to an aspect the lamination stack may comprise an optical homogeneity of the lamination stack of delta E* below 10, particularly below 2.3. Regarding the definition of delta E* it is referred to the definition provided elsewhere herein. The respective features and advantages linked to certain features throughout the text are not limited to the respective method, the apparatus and / or the system. Furthermore, all features can be used to specify all other respective categories and the respective advantages apply accordingly.

[0152] The nomenclature "feature A and / or feature B" is used throughout the description. It can be transferred to "feature A, feature B, or feature A and feature B". As the full listing would lead to a respective long and repetitive recasting of big portions of the description this nomenclature is used as a short abbreviate sentence construction.

[0153] Certain embodiments shall be described to explain the respective general aspects described above with respect to the figures in the following.

[0154] Brief description of the drawings

[0155] The drawings show in:

[0156] Fig. 1 a schematic of an exemplary embodiment of a method complex comprising a method of manufacturing a liquid fluid cell and a method of laminating;

[0157] Fig. 2A to Fig. 2D a comparison of exemplary embodiments of liquid fluid cells;

[0158] Fig. 3 illustrations of laminates comprising liquid fluid cells;

[0159] Fig. 4 a schematic of an exemplary embodiment of a lamination stack in a flatbed laminator;

[0160] Fig. 5A a diagram showing underfill over operating temperature;

[0161] Fig. 5B a diagram showing cell underpressure in relation to spacer compression or underfill levels for different spacer densities;

[0162] Fig. 5C a diagram showing a flatbed lamination method; Fig. 6A a diagram showing a lamination method using a vacuum bag with hotbox; and

[0163] Fig. 6B a diagram showing a lamination method using an autoclave.

[0164] Like-functioning and corresponding means and like-functioning and corresponding structures, as well as corresponding method steps, are numbered using the same reference signs throughout the description of the drawings. The reference signs shall not be interpreted as limiting the scope of protection. The wording "embodiment", "example" and "part of the invention" may be used throughout the following description also as matter of example for explanatory reasons.

[0165] Fig. 1 shows a method complex 200 for manufacturing a liquid fluid cell 1 particularly comprising a method 50 of manufacturing a liquid fluid cell 1 which can be coupled with a method 100, configured to laminate a liquid fluid cell 1 to a substrate 6, particularly a glass substrate.

[0166] The method 50 of manufacturing a liquid fluid cell 1 can comprise a step of setting at least one of an underfill and underpressure in the cell. The underfill is a particular measure to overcome or compensate the thermal expansion volume of the liquid fluid, preferably of the liquid-crystalline medium, in particular during lamination but also during operation of the laminated product at different temperatures. The underpressure is a particular measure to overcome or compensate external cell deformation forces, in particular during lamination. The underpressure is a result of underfill, in particular with simultaneous spacer compression, which may depend on spacer concentration and / or the E-modulus of the spacers. The method 50 particularly comprises the step of applying 51 pressure to a first cell substrate S1 and a second cell substrate S2 spaced apart by at least one spacer 10. Alternatively and additionally, the method 50 particularly comprises the step of filling 52 the liquid fluid cell 1 until it reaches at least one of a predefined underfill and predefined underpressure.

[0167] The method 100 comprises the steps of providing 110 a liquid fluid cell structure - here a liquid fluid cell 1 manufactured in a method 50 of manufacturing the liquid fluid cell 1 - comprising a first cell substrate 15 and a second cell substrate 15 limiting a cell gap 16, a substrate 6 and a lamination layer 7. Before lamination, a pre-lamination stack comprising at least the cell 1, the lamination layer 7 and the substrate 6 is assembled, and preferably a step of degassing the pre-lamination stack is carried out. Next, the cell substrate 15 is laminated 120 to the substrate 6 using the lamination layer 7. At least two of the following steps can be used during lamination 120, particularly performed temporarily overlapping or simultaneously: A controlled pressing can be applied 130, particularly applying a low pressure for a defined timespan. A controlled thermal load can be applied 140. An even distribution of pressure can be applied 150 over the stack including the liquid fluid cell 1. An even distribution of temperature can be applied 160 over the stack including the liquid fluid cell 1. These steps are designed to ensure that the liquid fluid cell is manufactured with uniform layer thickness, resulting in improved optical properties.

[0168] The method complex 200 for manufacturing laminated products, preferably liquid crystal windows, containing the cell(s) can overcome the drawbacks of prior art techniques. Respective liquid crystal windows are exemplarily shown in Fig. 3. In particular, the method complex 200 provides improved uniformity and appearance of the product by being able to control thermal load, pressure distribution, and temperature distribution during a lamination 120. The object of the invention is to provide a manufacturing method 50 and a lamination method 100 that allow the production of large-scale liquid crystal windows containing LC cells with uniform cell gap 16, reduced stress, and improved optical homogeneity. The method 50 of manufacturing and the method of laminating 100 can be distinctly applied. The resulting liquid fluid cell 1 from a method of manufacturing may be provided 110 to the method 100 of laminating, where the two methods 50 and 100 may or may not be performed in a timely coordinated manner, but they preferably are combined and performed consecutively.

[0169] A fluid or liquid fluid used in the context of the described embodiments may comprise a liquid crystal component, preferably is a liquid crystal material, and in particular has a liquid-crystalline phase at the typical working temperatures of the final product, preferably between -20 °C and 90° C. These fluids particularly have a phase between the crystallization point and the evaporation point, e.g. between -40 to 150 °C, with a viscosity below infinity. The liquid can be in a liquid-crystalline phase, such as a (chiral) nematic or smectic phase, preferably a nematic phase or chiral nematic phase. In an embodiment the fluid may comprise solid parts, such as polymeric components up to 30%.

[0170] The method 100 particularly involves laminating two glass substrates with an interlayer, where the lamination stack contains a liquid crystal layer in a cell 1 or even two liquid crystal layers in cells 1a and 1b as shown in Fig. 4. The method 50 particularly involves manufacturing at least one liquid fluid cell, here a liquid crystal cell, to be used in the method 100. The cell gap 16 is particularly formed by cell substrates 15 spaced apart by spacers 10 as shown in Fig. 2A to Fig. 2D. The cell gap 16 provides a volume for filling the space between the cell substrates 15 with the liquid crystal material. This method 50 provides better uniformity, appearance, and optical homogeneity compared to prior art techniques when followed by method 100, which applies heat and pressure, by favourably contributing to obtaining uniform thickness of the cell gap in the final product.

[0171] One aspect of the invention relates to the use of extended ranges of variations in the built- up and edge design of the liquid crystal glazing for different applications. Another aspect relates to the need for a large variation in dimensional freedom and shapes which may accommodate the various modes and uses of the liquid crystal materials and cells.

[0172] The product, particularly in form of a liquid fluid cell 1 laminated to at least one substrate 6 or windows containing liquid fluid cells, resulting from the method complex 200 may exhibit improved uniformity, better appearance, and optical homogeneity compared to prior art products, including the performance of the products at low operating temperatures and at high operating temperatures. For example, the cell gap variation can be reduced to less than 10% over the surface of the cell, preferably less than 5%, resulting in a delta E* value below 10, preferably below 2.3, where delta E* is defined by CIE 1976. This superior performance makes the product more suitable for e.g. architectural and automotive applications where optical uniformity and uniform appearance are desired.

[0173] In addition to these advantages, the described method complex allows for the production of larger windows of various shapes, including triangles, octagons, and rectangles, and particularly any other circumferential shape, with particularly the same quality standards.

[0174] Fig. 2A to Fig. 2D depict embodiments of liquid fluid cells comprising spacers 10 in a cell gap 16 between cell substrates 15. Fig. 2A shows an exemplary embodiment of a liquid fluid cell 1 with an initial cell gap smaller than the spacer diameter d at room temperature (20 °C). This particularly represents an underfill exhibiting a force 12. The compression of the spacer 10 exerts a force 11 on the cell substrates 15. The spacer compression is particularly in a range of an elastic mode region of spacer compression. In the exemplary embodiment the spacer compression is at 97.2 % of the respective compressed spacer 10a.

[0175] Fig. 2B shows the effect of heating to 80 °C of the exemplary embodiment shown in Fig.

[0176] 2A. The respective compressed spacers 10a can expand and a compensation of force 14 is possible. The thickness d of the spacer 10b may reach 99.5 % of the spacer 10 in a relaxed state. Thus, it may be avoided that external forces 13 may introduce dark spots 19 or bright spots 18 which compensate liquid crystal’s thermal expansion volume 17.

[0177] For matter of comparison in Fig. 2C an exemplary embodiment is shown with the thickness d of the spacers 10 starts at 100% at room temperature (20°C). In the respective embodiment external forces 11 may not be compensated as there is no counterforce 21. Therefore, a bright spot 18 may arise with a decrease of liquid crystal volume 17 which is then compensated by an increase of volume forming a dark spot 19 as shown in Fig. 2D, e.g. when heating to 70 °C.

[0178] Fig. 3 depicts systems or laminates 36 including liquid fluid cells 1, in particular an exemplary embodiment 30b according to the invention, and for comparison laminates 30a, 30c and 30d. The laminate 30b comprising a triangular cell 1 has a uniform appearance without defects such as dark or bright spots or stripes or wave patterns at room temperature and also at higher operating temperatures. This may be achieved by avoiding the deformation of the cell and substrates as described with respect to Figs. 2A to 2D. By comparison, laminates 30a, 30c and 30d which are not prepared according to the invention exhibit defects, in particular stripes 32a in laminate 30a, dark spots 32b in laminate 30c and bright spots 32c in laminate 30d.

[0179] In other embodiments e.g. rectangular liquid fluid cell laminates without cell gap deformation may be produced. In general form restraints may be overcome using any of the particularly described methods allowing to implement rectangular, triangular, polygonic, circular or any other given circumferential form.

[0180] Fig. 4 depicts a schematic of an exemplary embodiment of a lamination stack 36, 37 comprising two LC cells 1a, 1b, a coversheet 5 and two lamination layers 7 placed respectively between the coversheet 5 and the first cell 1a and between the first cell 1a and the second cell 1b in a flatbed laminator. The lamination stack 37 comprises multiple layers that are arranged from bottom to top. At the bottom is a heating or cooling flatbed plate 41 which contacts a face F6 of a substrate S1 of a second liquid fluid cell 1b, which further contains an LC layer and a second substrate S2. This cell 1b particularly is configured to face the interior 44 of a building. On top of this the first liquid fluid cell 1a can be placed which comprises a first substrate S1 , an LC layer and a second substrate S2. The second surface S2 of the first liquid fluid cell 1a can contact a lamination layer 7, particularly as a PVB foil 3, particularly a UV-blocking PVB foil 3 blocking UV radiation from an exterior 42 of the building, where the lamination layer 7 is also in contact with a cover sheet 5, which is configured to face the exterior 42 of a building.

[0181] The first liquid fluid cell 1a and the second liquid fluid cell 1b can be laminated using a lamination layer 7, particularly a PVB foil 2. The liquid fluid cell 1b has a contact face F5 with the first cell substrate S1 of the cell 1a (with face F4) via the lamination layer 7, particularly as PVB foil 2. The lamination stack 37 is shown placed in a flatbed laminator with bottom and top heating or cooling flatbed plates 41.

[0182] The UV-blocking PVB foil may be with added or intrinsic absorption. In a respective embodiment a PVB foil may be utilized and particularly designed to block UV radiation, either through the addition of UV-blocking additives or through inherent self-absorption properties.

[0183] In other embodiments, one or more low-emissivity (low-e) layers allow IR absorption for improved thermal insulation. In respective embodiments incorporated low-e layers can facilitate infrared (IR) absorption, particularly enhancing thermal insulation properties of the laminate including the liquid fluid cell(s) 1, preferably in addition to one or more layer(s) blocking UV radiation. This may not only extend the lifetime of the liquid fluid, in particular the liquid crystals, but may also contribute to improved energy efficiency, e.g. within buildings.

[0184] The type of glass for cell substrates 15 may be selected as desired. Alkaline glass as well as alkali-free glass can be used. Both types can be used, even in a combination of layers. In a particular embodiment the use of alkali-free glass is preferred. The coversheet 5 is in particular a structural glass material with favourable mechanical crash or impact performance. The glasses can be connected together advantageously due to the corresponding modulation of pressure and temperature properties. This allows for stable structures regarding the sheet glass used while maintaining beneficial optical properties. The thickness of the cell substrates 15 and the coversheet 5 may be the same or different In a particular embodiment the cell substrates 15 are thinner, e.g. ranging from 0.5 mm to 2 mm, than the coversheet, which may typically have a thickness between 2 mm and 10 mm.

[0185] Alkaline glass and alkali-free glass can be used, also in combination, for the construction of liquid fluid cells 1, with a cover sheet 5 particularly made from a structural glass material. This design allows for high structural stability while maintaining the beneficial optical properties. Liquid crystal cells may preferably be manufactured with thinner glass and high-quality glass having minimal waviness, in particular glass that can be alkali-free.

[0186] On top of the first liquid fluid cell 1a a cover sheet 5 can be laminated, which is laminated to the first liquid fluid cell 1a via the lamination layer 7 as a UV-blocking PVB foil 3. The UV-blocking PVB foil enhances the lifetime of the liquid fluid cells 1a, 1b, particularly of the liquid crystal material. The first liquid fluid cell 1a and the second liquid fluid cell 1b are then particularly laminated together via the lamination layer 7 as a PVB foil 2.

[0187] The cover sheet 5 can also contact a peripheral mask 4 to stabilize a cell coversheet offset 45, where the coversheet 5 protrudes from the stack of laminated liquid fluid cells 1a, 1b. This offset can include stabilizing and mounting structures.

[0188] The liquid fluid cells 1a, 1b may also contain a protrusion 46 of the first cell substrate S1 over the second cell substrate S2, which may be used to attach a wire 47 and a wire guide 49 useful for connecting electrodes for electrical switching of the liquid crystal material in the liquid fluid cell 1.

[0189] In a further embodiment it is possible to provide the lamination stack as depicted in Fig. 4, wherein however the respective layers in the stack are placed in the flatbed laminator in the inverted order, i.e. upside down, such that the coversheet 5 is placed at the bottom. This can provide benefits in terms of the reliability of the lamination process, especially when the coversheet 5 is thicker and / or extends in the surface area beyond the extension of the cells 1a, 1b.

[0190] In another embodiment it is possible to provide a lamination stack similar to the stack as depicted in Fig. 4, wherein the stack however contains only a single cell 1 and only a single lamination layer 7 which is placed between the cell 1 and the coversheet 5.

[0191] Fig. 5A depicts a diagram 501 showing underfill over operating temperature of an LC cell. Fig. 5A presents a diagram 501 that illustrates the relationship between underfill of the LC cell and operating temperature during lamination of the LC to the substrate and also as useful in the final product, with eight exemplary traces depicted. The y-axis displays the underfill ratio between 93% and 103% in 1% increments. The x-axis represents operating temperature from 0 °C to 120 °C in 10 °C increments. The relation between temperature and underfill is in principle determined by the thermal expansion, in particular the thermal expansion coefficient, of the LC material. The diagram shows that as the underfill increases above 96% at 20°C at an operating temperature of 80 °C a nominal filling of 100% is reached. Particularly, in this embodiment the operating window 550 can be defined between 0°C and 80°C for all underfill levels between 93% and 96%. To maintain the underfill level below 100% the underfill and temperatures can be kept within the respective ranges to prevent overfilling in the cell and to ensure proper filling status after lamination 120 and with thermal load in the field.

[0192] Starting from an underfill level of 93%, each trace in the diagram particularly represents a different underfill level, ultimately reaching full filling at 100% with 80 °C for a starting underfill level of 96%. It is possible to carefully manage the underfill during manufacturing 50 to enable optimal performance and to particularly prevent any adverse effects on the liquid crystal window laminates such as unwanted spots or other patterns.

[0193] Fig. 5B depicts a diagram 502 showing spacer pressure, directly related to the underpressure of the liquid fluid cell 1 , over spacer compression for different spacer densities. Fig. 5B presents a diagram 502 that illustrates the relationship between spacer compression and spacer pressure, as well as different spacer densities. The y-axis displays the compression ratio of the spacer, ranging from 93% to 100%, with increments of 1%. The x-axis represents the spacer pressure or respectively underpressure, measured in bar, and ranges from 0 bar to 1 bar, with increments of 0.1 bar.

[0194] The diagram particularly depicts three graphs that intersect at 0 bar and 100 % spacer compression, representing full expansion. The average of 4.65 spacers per square mm is represented by the straight line, while the lower limit of 3.0 spacers per square mm is shown by the dashed line. The upper limit of 6.33 spacers per square mm is depicted by the dotted line. The underfill range is given between 94.0% and 97.5%, and the underpressure range falls between 0.18 bar and 0.78 bar. In an embodiment this combination of parameters defines an operating window 550 for different spacer densities.

[0195] For the lower limit configuration, the graph may linearly decrease to 93% compression at a pressure of 0.44 bar. For the average configuration, the graph may decrease at 93% compression at a pressure of 0.67 bar. Lastly, for the upper limit configuration, the graph may decrease at 93% compression at a pressure of 0.93 bar. This diagram provides particular information on how to manage spacer compression and pressure based on different spacer densities in order to maintain optimal performance of Liquid Crystal windows containing laminated LC cells. Fig. 5C depicts a diagram 503 showing exemplary parameter combinations of a flatbed lamination method 100 and their temporal evolution. The lamination method 100 for laminating liquid crystal cell(s) 1 to further substrate(s) particularly involves several stages, including stack build up, vacuum de-gassing I, elevated temperature and / or elevated pressure for plastic deformation II of the interlayer, additionally or alternatively interlayer glass adhesion III, and temperature cool down IV to ambient. In the stack build up stage, different glass substrates and / or liquid crystal cells can be stacked with interlayer material 2, 3, 4 in between. Degassing I is then performed to remove excessive gases such as air and water vapour from the lamination stack 37 to prevent gas bubbles in the final product.

[0196] Elevated temperature is particularly applied to soften the interlayer material, allowing it to adhere properly to the glass surface. Pressure is then particularly applied to ensure the interlayer material sticks to the glass surface and to prevent voids at the interface of the interlayer and the glass. The temperature is then cooled down IV to ambient to harden the interlayer material, fixing the stack and preventing delamination and any gas bubbles from forming.

[0197] The step of the arranging 110 of a liquid fluid cell 1 preferably comprises the provision of a cell 1 which exhibits at least one of a defined underpressure and a defined underfill of a liquid fluid in the liquid fluid cell 1. Different from the method of manufacturing the liquid fluid cell 1, the pressure 504, temperature 506 and vacuum 509 can differ in a method of laminating 100.

[0198] Fig. 5C depicts a diagram 503 illustrating exemplary parameter combinations of a lamination method 100 and their temporal evolution. The left y-axis displays temperature in °C, ranging from 0 °C to 160 °C in steps of 10 °C. The x-axis represents time in minutes, starting from 0 min and extending to 60 min. The right y-axis shows vacuum underpressure or pressure 504 in bar, varying from -1 bar to 3 bar in 0.5 bar increments.

[0199] The lamination process particularly commences with vacuum de-gassing I between 0 and 10 min, during which a vacuum window 509 is established between -1 bar and -0.5 bar, without any pressure applied. The temperature particularly starts at room temperature (20 °C). Next, plastic deformation of the interlayer II may occur between 10 min and 20 min with the same vacuum window as during vacuum de-gassing I. A pressure window b can be established, with pressure 504 ranging from 0 bar to 1.5 bar (the upper limit may not be included). Temperature 506 increases particularly linearly up to 90 °C during this phase.

[0200] Interlayer glass adhesion III particularly takes place between 20 min and 40 min, with pressure 504 dropping to between 0.2 bar and 0.24 bar and remaining constant. Vacuum 509 becomes 0 bar, and temperature increases, linearly or nonlinearly, from 90 °C to 125 °C within a temperature window c, which is centered around the potential top temperature between 110 °C and 150 °C.

[0201] A cool-down phase IV may occur between 40 min and 60 min. The temperature drops from 125 °C to 90 °C between 40 min and 50 min in a controlled cooling window e, which is situated between 90 °C and 150 °C. Subsequently, there is a decrease in temperature from 90 °C to 40 °C between 50 min and 60 min. Pressure 504 remains constant at 0.2 to 0.24 bar throughout this process.

[0202] For laminates having favourable quality, sufficient process parameter uniformity and adequate time can be set to accomplish the required fulfilled process status and diminish any non-uniformities over the product. The presence of a fluid layer in liquid crystal cells with strict uniformity requirements in terms of the thickness of the fluid layer particularly creates additional boundary conditions in the lamination method 100 compared to regular glass substrates used in safety glass lamination. Particularly, maximum pressure and pressure non-uniformity levels must be observed, as well as restricted temperature dynamics and temperature non-uniformities.

[0203] Fig. 6A depicts a diagram 601 illustrating an exemplary state-of-the-art lamination method 100 using a vacuum bag with hotbox. The left y-axis particularly represents temperature, ranging from 0 °C to 160 °C with increments of 10 °C, while the right y-axis particularly displays vacuum underpressure in bar, varying from -1 bar to 1 bar with 0.5 bar increments. The x-axis particularly indicates time, extending from 0 min to 540 min in 30 min increments.

[0204] The straight line on the graph particularly represents the temperature profile, starting at 20 °C and remaining constant for 120 min. Subsequently, it can undergo a linear increase between 120 min and 150 min to reach 75 °C, particularly remaining constant for approximately 10 min. The temperature then particularly continues to rise linearly from 75 °C to 125 °C between 170 min and 200 min. After that, the temperature can remain constant between 200 min and 380 min. Finally, the temperature experiences a linear decrease to reach 40 °C at 500 min.

[0205] The vacuum underpressure particularly remains at around -0.95 bar up to 190 min, after which it steps to about -0.775 bar and remains constant until 490 min. At this point, the pressure can normalize. This temperature and vacuum profile in Fig. 6A provides comparative information for managing heat and vacuum conditions during the lamination process for optimal performance of laminating liquid fluid cells 1 such as liquid crystal cells to liquid crystal window cells.

[0206] Fig. 6B illustrates a diagram 602 showcasing a state-of-the-art lamination method 100 using an autoclave. The left y-axis particularly represents temperature, ranging from 0 °C to 160 °C with increments of 10 °C, while the right y-axis displays pressure in bar, varying from 0 bar to 14 bar with 2 bar increments. The x-axis indicates time, extending from 0 min to 400 min in 50 min increments.

[0207] The graph particularly represents the temperature profile, starting at 20 °C and, particularly linearly or nonlinearly, increasing for 110 min to reach 125 °C. Between 110 min and 130 min, the temperature may experience a linear increase to reach 135 °C, particularly remaining constant at this level for approximately 10 min. The temperature then undergoes a decrease from 135 °C to 70 °C between 180 min and 290 min. Subsequently, it decreases from 70 °C to 50 °C between 290 min and 340 min. Finally, the temperature experiences a decrease to reach room temperature.

[0208] The dotted line in Fig. 6B particularly represents the pressure profile, starting at 1 bar and increasing up to 12 bar around 110 min. It remains constant until 180 min, after which there is a decrease to 10.65 bar up to 290 min. A slight decrease follows, reaching 10.4 bar at 340 min. The pressure then normalizes before returning to atmospheric pressure.

[0209] Fig. 6B provides comparative information which may allow to improve the manufacturing of liquid fluid / crystal layer containing liquid fluid cells 1 and windows by addressing issues related to temperature and vacuum variations during lamination using autoclaves.

[0210] In particular, the described method allows to minimize non-uniformities in layer thickness and ultimately produce products with enhanced optical properties and fewer defects. Preferably pressure and / or temperature, in particular temperature load, according to embodiments of the invention may be below typical pressure and temperature load values as used in state-of the-art lamination, in particular as shown in Figs. 6A and 6B, preferably between 10% and 95% lower than the stated values, more preferably between 20% and 80% lower than the stated values.

[0211] Reference signs

[0212] 1 liquid fluid cell

[0213] 1a first liquid fluid cell

[0214] 1b second liquid fluid cell

[0215] 2 PVB

[0216] 3 UV-blocking PVB

[0217] 4 peripheral mask

[0218] 5 cover sheet

[0219] 6 substrate

[0220] 7 lamination layer

[0221] 8 lamination foil

[0222] 10 spacer

[0223] 11 force exerted from spacer

[0224] 12 force exerted by underpressure

[0225] 13 external force

[0226] 14 counter force

[0227] 15 cell substrate

[0228] 16 cell gap

[0229] 17 liquid crystal expansion volume

[0230] 18 light spot area

[0231] 19 dark spot area

[0232] 21 lack of counter force

[0233] 36 system

[0234] 37 lamination stack as system

[0235] 41 flat heating or cooling plates

[0236] 42 building exterior

[0237] 44 building interior

[0238] 45 cell-coversheet offset

[0239] 46 protrusion

[0240] 47 wire

[0241] 49 wire guide

[0242] 50 method of manufacture

[0243] 51 applying pressure to a first cell substrate and a second cell substrate spaced apart by at least one spacer

[0244] 52 filling the liquid fluid cell until it reaches at least one of a predefined underfill or predefined underpressure 100 method of lamination

[0245] 110 arranging a liquid fluid cell structure

[0246] 120 laminating of the cell substrate to the substrate using the lamination layer

[0247] 130 applying a controlled pressing

[0248] 140 applying a controlled thermal load

[0249] 150 applying an even distribution of pressure over the liquid fluid cell

[0250] 160 applying an even distribution of temperature over the liquid fluid cell

[0251] 200 method complex

[0252] 501 diagram showing underfill vs. operating temperature

[0253] 502 diagram showing spacer pressure vs. spacer compression for different spacer densities

[0254] 503 diagram showing the lamination process

[0255] 504 pressure

[0256] 506 temperature

[0257] 509 vacuum

[0258] 601 diagram showing temperature and pressure over time of a lamination process in a vacuum bag / hot box

[0259] 602 diagram showing temperature and pressure over time of a lamination process in an autoclave a vacuum b press window c temperature window d thickness of cell gap e controlled cooling window

[0260] I vacuum de-gassing

[0261] II plastic deformation interlayer

[0262] 111 interlayer glass adhesion

[0263] IV cool down

[0264] T temperature

[0265] F1 first surface

[0266] F2 second surface

[0267] F3 third surface

[0268] F4 fourth surface

[0269] F5 fifth surface

[0270] F6 sixth surface

[0271] 51 first cell substrate

[0272] 52 second cell substrate

Claims

Claims1. Method (100) for producing a laminate comprising a liquid fluid cell (1) and a substrate (6), particularly a glass substrate, the method (100) comprising the steps of:- arranging (110) at least one liquid fluid cell (1) comprising at least a first cell substrate (15) and a second cell substrate (15) spaced such to form a cell gap (16) comprising a liquid fluid, particularly a liquid crystal material, with at least one substrate (6) and at least one lamination interlayer (7) to form a stack; and- laminating (120) of the at least one substrate (6) to the liquid fluid cell (1) via at least one of the first cell substrate (15) or the second cell substrate (15) using the lamination interlayer (7), characterized by at least two of the following steps, particularly performed temporarily overlapping or simultaneously: a degassing of the stack and / or gas dissolving in the stack; applying (130) a controlled pressing to the stack, particularly applying a low pressure for a defined timespan; applying (140) a controlled thermal load to the stack; applying (150) an even distribution of pressure over the stack including the liquid fluid cell (1); and applying (160) an even distribution of temperature over the stack including the liquid fluid cell (1).

2. Method (100) according to claim 1 , characterized by a step of providing (110) the liquid fluid cell (1) having a defined underpressure and / or a defined underfill of the liquid fluid, preferably the liquid crystal material, in the liquid fluid cell (1).

3. Method (100) according to claim 1 or 2, characterized in that the substrate (6) is laminated to a liquid fluid cell structure, the liquid fluid cell structure comprising at least two liquid fluid cells (1a, 1 b); and / or in that the substrate (6) is either one of a first cell substrate (15) or a second cell substrate (15) of a second liquid fluid cell (1 b), or a coversheet, particularly facing an exterior space; and / or in that a symmetrical and / or unsymmetrical lamination stack is built up; and / or in that the lamination interlayer (7) comprises a lamination foil, particularly a PVB lamination foil (2, 3).

4. Method (50, 100) according to any of the preceding claims, characterized by the step of controlled pressing (130) with a defined pressure (504) between 50 and 1500 mbar, preferably between 100 and 1000 mbar, more preferably between 150 and 800 mbar, and in particular between 200 and 600 mbar.

5. Method (100) according to any of the preceding claims, characterized by controlling during the step of lamination (120) at least one of a temperature increase or a temperature decrease in the stack including the liquid fluid cell (1), particularly by controlling the temperature inhomogeneity through the liquid fluid cell (1), further particularly controlling at least one of a top-bottom temperature distribution or a lateral temperature distribution.

6. Method (50, 100) according to any of the preceding claims, characterized by an underfill in the liquid fluid cell (1) between 80% and 99.9%, particularly between 90 % and 97.5 %, preferably determined at 20 °C, and / or an underpressure between 0.10 and 1 bar, further particularly between 0.15 and 0.80 bar, preferably determined at 20 °C.

7. Method (100) according to any of the preceding claims, characterized by at least one of the following:- a flatbed laminator is used in the laminating (120) and is equipped with temperature controlled flat heating and / or cooling press plates (41) in the thermal stages of a heating step;- the liquid fluid cell (1) comprises a cell gap (16) between 1 pm to 100 pm, particularly between 5 pm and 30 pm;- a temperature isolation layer is provided during the step (120) of laminating; or- a lamination temperature (506) is set between 70 °C and 150 °C, particularly between 100 °C and 140 °C, further particularly between 120 °C and 130 °C.

8. Method (50) of manufacturing a liquid fluid cell (1) comprising an underfill and / or underpressure, comprising the step of:- preparing (52) the liquid fluid cell (1) by filling the liquid fluid cell (1) with a liquid fluid such that a predefined underfill and / or predefined underpressure are reached, preferably by applying (51) pressure to a first cell substrate (S1) and a second cell substrate (S2) spaced apart by at least one spacer (10) defining a thickness (d) ofthe cell gap (16), particularly a pressure between 500 and 2000 mbar, further particularly between 800 and 1500 mbar.

9. Method according to claim 8, characterized in that in the step of preparing the liquid fluid cell (1) to reach an underpressure, the underpressure is either reached by compressing the at least one spacer (10) and a pressing out of liquid fluid after vacuum filling, or by sealing the liquid fluid cell (1) after reaching a predefined filling level using droplet printing or one drop filling.

10. System (36) comprising at least one liquid fluid cell (1), at least one substrate (6), particularly a glass substrate, and at least one lamination interlayer (7), wherein the substrate (6) is laminated to the liquid fluid cell (1) via the lamination interlayer (7), particularly by a method (50, 100) according to any of the claims 1 to 9.

11. System (36) according to claim 10, wherein the liquid fluid cell (1) exhibits a delta E* value below 10, particularly below 2.3.

12. System (36) according to claim 10 or 11 , characterized in that the substrate (6) is dimensioned in at least one direction of the lamination area such that a substrate protrusion is formed.

13. System (36) according to claim 12, characterized in that at least one electrical component or electronic component is positioned on the substrate protrusion (46).

14. System (36) according to any of the claims 10 to 13, characterized in that the lamination interlayer (7) is a lamination foil (8), preferably a PVB foil.

15. Lamination stack (37) comprising at least one system (36) according to any of the claims 10 to 14, particularly laminated by a method (50, 100) according to any of the claims 1 to 9, and wherein the lamination stack (37) comprises at least two liquid fluid cells (1a, 1b), particularly according to claim 10.

16. Lamination stack (37) according to claim 15, having an optical homogeneity of the lamination stack of delta E* below 10, particularly below 2.3.

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