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WO2025196049A1 - Laminated glazing with variable transmission - Google Patents

Laminated glazing with variable transmission

Info

Publication number
WO2025196049A1
WO2025196049A1 PCT/EP2025/057366 EP2025057366W WO2025196049A1 WO 2025196049 A1 WO2025196049 A1 WO 2025196049A1 EP 2025057366 W EP2025057366 W EP 2025057366W WO 2025196049 A1 WO2025196049 A1 WO 2025196049A1
Authority
WO
WIPO (PCT)
Prior art keywords
glass substrate
laminated glazing
wavelength range
filter element
filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/057366
Other languages
French (fr)
Inventor
Axel FOUQUES
Nicolas Chemin
Maxence WILMET
Laurent Maillaud
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Sekurit France
Original Assignee
Saint Gobain Sekurit France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint Gobain Sekurit France filed Critical Saint Gobain Sekurit France
Publication of WO2025196049A1 publication Critical patent/WO2025196049A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10009—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets
    • B32B17/10036—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10165—Functional features of the laminated safety glass or glazing
    • B32B17/10431—Specific parts for the modulation of light incorporated into the laminated safety glass or glazing
    • B32B17/10467—Variable transmission
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10165—Functional features of the laminated safety glass or glazing
    • B32B17/10431—Specific parts for the modulation of light incorporated into the laminated safety glass or glazing
    • B32B17/10467—Variable transmission
    • B32B17/10495—Variable transmission optoelectronic, i.e. optical valve
    • B32B17/10504—Liquid crystal layer

Definitions

  • the invention relates to the field of electrically controllable glazing with variable optical properties, in particular laminated glazing with variable transmission by liquid crystals and comprising dichroic dyes as well as a UV filter.
  • An electrically controllable glazing with variable optical properties has the ability to opacify the transparency of the glazing when an electrical voltage is applied to switchable functional elements integrated into the glazing.
  • These functional elements are, for example, liquid crystals.
  • the invention will be more particularly described with regard to the use of a laminated glazing with variable transmission by liquid crystals in an application of exterior glazing (for vehicles such as motor vehicles, trains, aircraft), without however being limited thereto. It may in particular be applied to interior glazed surfaces (for buildings).
  • a laminated glazing with variable transmission by liquid crystals comprises at least two main glass substrates, two interlayer lamination films made of plastic, very often polyvinyl butyral (PVB), and a liquid crystal cell placed between the two interlayer lamination films.
  • the liquid crystal cell comprises liquid crystals in combination most often with dichroic dyes (such a host-guest cell is called "GHLC” for "Guest-Host Liquid Crystal” in English), encapsulated between two encapsulation substrates (generally polymeric encapsulation films) which are kept at a constant distance thanks to spacers such as glass or plastic beads.
  • Each of the encapsulation substrates is provided with an electrode.
  • the liquid crystals change orientation and modify the light transmission through the cell, the glazing changing from a clear state to a dark state, or vice versa.
  • the terms “clear state” and “dark state” mean the state of the glazing at its maximum or minimum light transmission respectively.
  • the optical performance deteriorates over time because the dichroic dyes of the liquid crystal cell are sensitive to light irradiation and/or heat.
  • the ultraviolet (UV) spectral component and the infrared (IR) spectral component in particular lead to a degradation of the dichroic dyes, manifesting itself for example by their change of color and causing an unsightly discoloration of the glazing as well as a reduced contrast between the two switching states.
  • the glazing may comprise UV blockers or absorbers or UV reflectors filtering ultraviolet radiation and IR reflectors or IR absorbers.
  • the UV blockers or absorbers are, for example, made up of intermediate layers in the glazing or liquid crystals charged with UV-absorbing molecules.
  • IR reflectors are layers integrated into laminated glazing, which are capable of reflecting IR and are called low-emissivity layers or solar control layers.
  • liquid crystal cells which have high optical performance use dichroic dyes which unfortunately have limited stability to light and/or temperature, and the UV and IR filters which can be associated do not yet have sufficient performance with regard to the durability of liquid crystal cells with dichroic dyes.
  • the invention therefore aims to propose a laminated glazing with switchable functional elements of the liquid crystal and dichroic dye type (usually called a "guest-host" system), which does not have the aforementioned drawbacks, in particular a glazing whose switchable functional elements do not deteriorate rapidly over time.
  • a laminated glazing with switchable functional elements of the liquid crystal and dichroic dye type usually called a "guest-host" system
  • the laminated glazing with variable light transmission by liquid crystals comprises at least a first main glass substrate, a second main glass substrate, at least one liquid crystal cell including dichroic dyes, the cell being arranged between the first and second glass substrates, and at least one UV filter blocking UV up to 380 nm, and is characterized in that the laminated glazing further comprises a first filtering element which filters visible light in the wavelength range A from 380 to 450 nm, and a second filtering element which filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B waves, and transmission colorimetric coordinates a* from 6 to 5, preferably from -4 to 0, and b* from -5 to 5, preferably from -3 to 3.
  • the light transmission (TL) through a glazing is measured according to the ISO 9050:2023 standard with illuminant D65.
  • An average transmission corresponds to the arithmetic mean of the transmissions over the wavelength range considered, considering for example a step of 1 nm.
  • the term "which filters” means that part of the light radiation is blocked or attenuated, by absorption or by reflection, i.e. to say that only a part of the radiation, over the wavelength range considered, passes through the filter element.
  • an element which filters at least X% over a given wavelength range means that it has an average transmission of at most 100-X% over this range considered.
  • liquid crystal cell means a liquid crystal cell incorporating dichroic dyes.
  • the solution of the invention makes it possible to retain a UV filter coupled to the liquid crystal cell (the UV filter being a simple and inexpensive means of protecting the glazing and therefore the liquid crystal cell from wavelengths up to 380 nm) and to further increase the durability of the liquid crystal glazing while preserving both the functional and aesthetic aspects of the glazing.
  • the second filter element has an absorption spectrum comprising at least one absorption peak having a half-height width L of at least 10 nm and at most 100 nm over the wavelength range B, in particular a half-height width L of less than or equal to 50 nm over the wavelength range B.
  • the absorption peak has a maximum intensity l max of between 5% and 100%.
  • the ratio l max /L is preferably between 10 1 nm 1 and 5.10 -4 nm 4 .
  • the first filtering element filters at least 40% of the visible light in the wavelength range A, in particular at least 50%, or even at least 60% in the wavelength range A between 380 nm and 450 nm, in particular at least 90%, preferably at least 95%, or even at least 98%, in the wavelength range A from 380 to 450 nm.
  • the first filter element further filters at least 99%, preferably 100%, of the wavelengths below 380 nm and thus also constitutes the UV filter.
  • the first filter element is physically distinct from the UV filter.
  • the first filter element is a mass-colored glass substrate, or a thin layer deposited on a glass substrate providing coloring of said glass substrate, or a colored plastic film.
  • the second filter element is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film.
  • Each of the first and second filter elements may be a colored element that includes one or more coloring agents in combination.
  • the first filtering element when the first main glass substrate is turned towards the external environment in the position of use of the glazing, the first filtering element is arranged between said first main glass substrate and the liquid crystal cell, while the second filtering element is arranged between the first filtering element and the liquid crystal cell, or between the liquid crystal cell and the second main glass substrate.
  • the first filter element and the second filter element form a single film of plastic material.
  • this single film absorbs, by the plastic material of which it is made or by the presence of additives, in the wavelength range A, in particular beyond 410 nm, so as to provide the first filter element and further comprises one or more coloring agents absorbing in the wavelength range B so as to provide the second filter element.
  • the UV filter, the first filter element and the second filter element form a single film made of plastic.
  • this single film comprises anti-UV agents and absorbs, by the plastic material of which it is made or by the presence of additives (including possibly the anti-UV agents), in the wavelength range A, in particular beyond 410 nm, so as to provide the first filter element and further comprises one or more coloring agents absorbing in the wavelength range B so as to provide the second filter element.
  • the second filter element is a colored plastic film (comprising a polymer matrix and at least one coloring agent dispersed in the matrix).
  • the first filter element is a mass-colored glass substrate and the second filter element is a colored polymer layer deposited on a glass substrate.
  • the polymer layer constituting the second filter element has a thickness of between 0.1 mm and 2 mm, preferably at most 1 mm.
  • the glazing has, in its clear state at maximum light transmission, a light transmission (TL) greater than 5%.
  • a laminated glazing according to the invention in the automobile such as a glass roof or a windshield (lower and/or upper zones)
  • the TL of the glazing is less than or equal to 5% in the dark state, preferably less than 2%, more preferably less than 1% or even less than 0.5%
  • the TL is greater than or equal to 5% in the clear state, preferably at least between 15% and 20%
  • the contrast of the TL between the dark and light states is between 2 and 100.
  • the UV filter is a thin layer applied to the internal or external face of the first main glass substrate (glass substrate intended to be turned outwards in the position of use of the glazing), or is a plastic film arranged between the first main glass substrate and the liquid crystal cell.
  • the UV filter and/or the first filter element and/or the second filter element is a film made of polymeric material which is based on at least one polymer chosen from the following polymers: polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene, polycarbonate, polymethylmethacrylate, polyacrylate, polyvinyl chloride, polyacetate resin, acrylate, fluorinated ethylene propylene, polyvinyl fluoride, ethylene tetrafluoroethylene, cyclic olefin copolymer (COC), transparent adhesive material (OCA for "Optical Clear Adhesive" in English).
  • PVB polyvinyl butyral
  • EVA ethylene vinyl acetate
  • PU polyurethane
  • PET polyethylene terephthalate
  • polyethylene polycarbonate
  • polymethylmethacrylate polyacrylate
  • polyvinyl chloride polyacetate resin
  • the OCA is in particular of the acrylic, polyvinyl acetate (PVA), polyurethane (PU), silicone, or epoxy type.
  • the transparent adhesive material (OCA) can be deposited in the solid state of pressure-sensitive type (PSA film), or in the liquid state (resin) and cured during the lamination process, forming an interlayer film after curing.
  • the thickness of the polymeric film is preferably between 0.02 mm and 2 mm, preferably from 0.3 mm to 1 mm.
  • the liquid crystal cell comprises encapsulation substrates made of encapsulation films made of polymeric material.
  • the liquid crystal cell comprises encapsulation substrates made of encapsulation glass substrates, the cell being laminated so that each of the two encapsulation glass substrates is made integral with one of the two main glass substrates via at least one plastic interlayer, at least one interlayer being the UV filter and at least one interlayer being the first filter element and/or the second filter element.
  • the laminated glazing comprises at least one coating of infrared protection, in particular the infrared protection coating being arranged on the inner or outer face of the first main glass substrate and preferably on the outer or inner face of the second main glass substrate.
  • the infrared protection coating is for example a thin layer applied to the inner or outer face of the first main glass substrate and/or an interlayer film arranged between the first main glass substrate and the liquid crystal cell. This configuration makes it possible to reflect IR so that heat and/or IR radiation do not degrade the dichroic coloring agents of the liquid crystal cell.
  • the liquid crystal cell integrating dichroic dyes is a host-guest cell called “GHLC” (for “Guest-Host Liquid Crystal” in English) or a polymer-based cell such as a PDLC cell (for “Polymer-Dispersed Liquid Crystal” in English), or a PNLC cell (for “Polymer Network Liquid Crystal” in English) or a PSLC cell (for “Polymer stabilized liquid crystal”).
  • GHLC host-guest cell
  • PDLC cell for “Polymer-Dispersed Liquid Crystal” in English
  • PNLC cell for “Polymer Network Liquid Crystal” in English
  • PSLC cell for “Polymer stabilized liquid crystal”.
  • the laminated glazing may include other functionalities, which are added via coatings in direct contact with the main glass substrates and/or (the encapsulation substrates of) the liquid crystal cell and/or with interlayer films, or which are provided directly by one or more interlayer films.
  • These various functionalities are, for example, acoustic, anti-reflective, non-stick, anti-scratch, photocatalytic, anti-fingerprint, anti-fog, light extraction properties, etc.
  • the laminated glazing of the invention can constitute building glazing.
  • the laminated glazing of the invention may constitute vehicle glazing, in particular a vehicle chosen from an automobile, a train, a truck, an aircraft, a military vehicle, a tractor and a bus.
  • the laminated glazing is in particular chosen from roof glazing, a rear window, a side window, a windshield, and a gradient band of the upper part of the windshield.
  • Laminated glazing can be flat or curved.
  • Laminated glazing can be used in double glazing or in triple glazing.
  • FIG. 1 represents a schematic sectional view of a laminated glazing according to an exemplary embodiment of the invention.
  • the laminated glazing 1 of the invention illustrated in Figure 1 is a laminated glazing with variable transmission by liquid crystals comprising a liquid crystal cell 2 integrating dichroic dyes.
  • the glazing of the invention aims to effectively increase the durability and stability over time of the dichroic dyes of the liquid crystal cell 2.
  • the glazing 1 comprises a first filtering element which filters visible light in the wavelength range A from 380 to 450 nm and a second filtering element which filters visible light in the wavelength range B from 451 to 700 nm.
  • the laminated glazing 1 is intended for a building application or a vehicle application.
  • the laminated glazing 1 has its light transmission modified when an electrical voltage is applied to the electrodes of the liquid crystal cell 2.
  • the glazing 1 can be normally clear (with maximum light transmission) in the absence of voltage, and it becomes dark (with minimum light transmission), by applying a voltage. Conversely, the glazing can be conceived as normally dark, without voltage; it then becomes clear by applying a voltage. The normally clear or normally dark state depends on the use of the glazing.
  • the laminated glazing 1 will be used in a single-piece manner as is as single glazing, or will be combined with one or more other laminated or spaced glass substrates.
  • the laminated glazing 1 illustrated in FIG. 1 comprises a first main glass substrate 10, a second main glass substrate 11 arranged at a distance and opposite the first substrate 10, the liquid crystal cell 2 arranged at the heart of the glazing, a UV filter 3 blocking UV up to 380 nm and intermediate elements, here 40, 41 and 42, for securing the liquid crystal cell 2 to the glass substrates 10 and 11 and/or to the first and second filtering elements, and said first and second filtering elements 5 and 6.
  • the intermediate securing elements may for example be a PVB film or an OCA layer.
  • the intermediate securing elements have a thickness of between 0.1 mm and 2 mm, in particular 0.38 mm or 0.76 mm.
  • the main glass substrates 10 and 11 have a thickness suitable for the use of laminated glazing.
  • the thickness may be between 0.3 mm and 15 mm, preferably between 1 and 5 mm; it is for example 1.6 mm, 1.8 mm or 2.1 mm.
  • the liquid crystal cell 2 is for example a guest-host liquid crystal cell comprising a liquid volume of liquid crystals mixed with dichroic dyes.
  • the liquid crystal cell 2 is of the known type.
  • the first glass substrate 10 being intended to be turned towards the external environment, the UV filter 3 is associated with it.
  • the UV filter 3 is made of a polymeric material such as PVB, having the property of cutting ultraviolet rays up to 380 nm.
  • the ultraviolet cutting property is preferably provided by molecules dispersed in the polymeric matrix of the film, which are capable of blocking ultraviolet rays and which do not absorb visible radiation.
  • the UV filter 3 has a transmission for each wavelength in the wavelength range from 280 nm to 380 nm of less than 1%, preferably less than 0.1%, more preferably less than 0.01%, preferably equal to 0%.
  • the glazing 1 comprises the first filtering element 5 which filters visible light in the wavelength range A from 380 to 450 nm, and the second filtering element 6 which filters visible light in the wavelength range B from 451 to 700 nm, the first and second filtering elements 5 and 6 being such that the laminated glazing 1, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B, and colorimetric coordinates in transmission a* of -6 to 5, preferably of -4 to 0, and b* of -5 to 5, preferably of -3 to 3.
  • the first filter element 5 is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film.
  • the second filter element 6 is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film.
  • the coloring agents of the first and second filter elements 5 and 6 are selected to provide the aforementioned filtering properties for the glazing.
  • the glazing 1 preferably comprises an infrared protective coating 70 (solar control) which is arranged on the internal face (called face F2) of the first main glass substrate 10 (when this first glass substrate is intended to be turned towards the outside, such as the outside of the passenger compartment of the vehicle).
  • This IR protective coating protects the liquid crystal cell 2 from the heat that the glazing can undergo due to solar radiation.
  • the glazing 1 may comprise a low-emissive layer 71 on the external face of the second main glass substrate 11 (face intended to be turned towards the passenger compartment of the vehicle, called face F4) to minimize heat loss in the passenger compartment in winter and the sensation of a cold wall.
  • the infrared protective coating 70 stacked from the first glass substrate 10 and between said first glass substrate 10 and the liquid crystal cell 2 are the infrared protective coating 70, the UV filter 3, the first filter element 5 which is a colored glass substrate, an interlayer 40 such as a PVB film, a glass substrate 60 whose TL is preferably at least 91%, the second filter element 6 with a polymer matrix deposited on the glass substrate 60, and an OCA 41.
  • the interlayer 40 made it possible to secure the first glass filter element 5 to the glass substrate 60.
  • the OCA 41 made it possible to secure the polymer matrix of the second filter element 6 to the liquid crystal cell 2 whose encapsulation substrates are polymeric.
  • said cell is secured to the second glass substrate 11 by an OCA 42.
  • the UV 3 filter is a commercial PVB film that filters ultraviolet rays, for example the film sold under the name Saflex®PVB from the Eastman company, 0.76 mm thick, which filters 99% up to 380 nm;
  • the first filter element 5 is a glass substrate which is colored (the glass of the glass substrate comprising a coloring agent) and has a thickness of 0.38 mm.
  • the colored glass substrate constituting the first filter element 5 is commercially available, for example the product marketed under the name GG435 from the company SCHOTT. This first filter element 5 filters visible light up to 435 nm, so that it has zero transmission for each wavelength up to 435 nm;
  • the second filter element 6 is a polymeric layer comprising a coloring agent.
  • the coloring agent is for example the product marketed under the name FDG-005 from the company Yamada Chemicals.
  • This dye FDG-005 has an absorbance peak at 580 nm, and a width at half-maximum of 30 nm at a concentration of 0.26% relative to the total dry weight and for a film thickness of 8 ⁇ m;
  • the glass substrate 60 comprising the second filter element 6 is a clear glass such as the product marketed under the name PLANICLEAR® from the company SAINT-GOBAIN; its thickness is 2.1 mm.
  • a solution is prepared comprising a solvent such as methyl ethyl ketone (MEK) at 70% by weight, polymethyl methacrylate acrylic (PMMA) at 29.3% by weight and FDG-005 at 0.7% by weight.
  • MEK methyl ethyl ketone
  • PMMA polymethyl methacrylate acrylic
  • FDG-005 FDG-005
  • the combination of the UV filter 3 as well as the first filter element 5 and second filter element 6 acting respectively in the visible wavelength ranges A and B, makes it possible to effectively increase the durability and stability over time of the dichroic dyes of the liquid crystal cell 2, while preserving its aesthetic properties.
  • the light transmission of the glazing of the aforementioned example remains entirely acceptable in the clear state with an average transmission T(A) of 3% over the wavelength range A, an average transmission T(B) of 17% over the wavelength range B, and colorimetric coordinates in transmission a* of -2 and b* of 1 according to the CIE illuminant D65 2° (CIE 1931).
  • the color variation AE of the glazing of the aforementioned example is less than 5, after an accelerated aging test which corresponds to 1400 hours of operation of the liquid crystal cell 2, whereas comparatively, a glazing with the same liquid crystal cell 2 protected by the single and same UV filter 3 has a AE color variation of 26 after the same accelerated aging test.
  • the inventors have surprisingly demonstrated that by adding to the UV filter which filters up to 380 nm, the first filtering element and the second filtering element according to the invention which filter respectively in the visible beyond 380 nm up to 450 nm and between 451 nm and 700 nm, it is possible to increase the durability and stability of the liquid crystal cell 2 and the dichroic dyes, and therefore of the glazing 1, while preserving the aesthetic and functional aspects of the glazing.

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  • Liquid Crystal (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Joining Of Glass To Other Materials (AREA)
  • Optical Filters (AREA)

Abstract

The invention relates to laminated glazing (1) with variable light transmission by liquid crystals, the glazing including at least a first main glass substrate (10), a second main glass substrate (11), at least one liquid crystal cell (2) including dichroic dyes, the cell (2) being arranged between the first and second glass substrates (10, 11), and at least one UV filter (3) blocking UV up to 380 nm, characterised in that the laminated glazing further comprises a first filtering element (5) which filters visible light in the wavelength range A of 380 to 450 nm, and a second filtering element (6) which filters visible light in the wavelength range B of 451 to 700 nm, such that the laminated glazing, in its clear state with maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength domain A, an average transmission T(B) of 0.1 to 40% over the wavelength domain B, and colorimetric transmission coordinates a* of -6 to 5, preferably of -4 to 0, and b* of -5 to 5, preferably of -3 to 3.

Description

Description Description

Titre de l'invention : Vitrage feuilleté à transmission variable Title of the invention: Laminated glazing with variable transmission

[0001] L'invention concerne le domaine des vitrages électro-commandables à propriétés optiques variables, en particulier les vitrages feuilletés à transmission variable par cristaux liquides et comprenant des colorants dichroïques ainsi qu'un filtre UV. [0001] The invention relates to the field of electrically controllable glazing with variable optical properties, in particular laminated glazing with variable transmission by liquid crystals and comprising dichroic dyes as well as a UV filter.

[0002] Un vitrage électro-commandable à propriétés optiques variables a la capacité d'opacifier la transparence du vitrage lorsqu'une tension électrique est appliquée à des éléments fonctionnels commutables intégrés au vitrage. Ces éléments fonctionnels sont par exemple des cristaux liquides. [0002] An electrically controllable glazing with variable optical properties has the ability to opacify the transparency of the glazing when an electrical voltage is applied to switchable functional elements integrated into the glazing. These functional elements are, for example, liquid crystals.

[0003] L'invention sera plus particulièrement décrite quant à l'utilisation d'un vitrage feuilleté à transmission variable par cristaux liquides dans une application de vitrages extérieurs (pour véhicule tel que véhicule automobile, train, aéronef), sans toutefois y être limitée. Elle pourra notamment s'appliquer à des surfaces vitrées d'intérieur (pour bâtiment). [0003] The invention will be more particularly described with regard to the use of a laminated glazing with variable transmission by liquid crystals in an application of exterior glazing (for vehicles such as motor vehicles, trains, aircraft), without however being limited thereto. It may in particular be applied to interior glazed surfaces (for buildings).

[0004] Un vitrage feuilleté à transmission variable par cristaux liquides, comporte au moins deux substrats verriers principaux, deux films intercalaires de feuilletage en matière plastique, très souvent en polybutyral de vinyle (PVB), et une cellule à cristaux liquides placée entre les deux films intercalaires de feuilletage. La cellule à cristaux liquides comporte des cristaux liquides en combinaison le plus souvent avec des colorants dichroïques (une telle cellule hôte-invité est dite « GHLC » pour « Guest-Host Liquide Crystal » en anglais), encapsulés entre deux substrats d'encapsulation (généralement des films polymériques d'encapsulation) qui sont maintenus à distance constante grâce à des espaceurs tels que des billes en verre ou en matière plastique. Chacun des substrats d'encapsulation est pourvu d'une électrode. Lorsqu'une tension est appliquée aux électrodes, les cristaux liquides changent d'orientation et modifient la transmission lumineuse à travers la cellule, le vitrage passant d'un état clair à un état sombre, ou inversement. On entend par « état clair » et « état sombre » l'état du vitrage à sa transmission lumineuse maximum, respectivement minium. [0004] A laminated glazing with variable transmission by liquid crystals comprises at least two main glass substrates, two interlayer lamination films made of plastic, very often polyvinyl butyral (PVB), and a liquid crystal cell placed between the two interlayer lamination films. The liquid crystal cell comprises liquid crystals in combination most often with dichroic dyes (such a host-guest cell is called "GHLC" for "Guest-Host Liquid Crystal" in English), encapsulated between two encapsulation substrates (generally polymeric encapsulation films) which are kept at a constant distance thanks to spacers such as glass or plastic beads. Each of the encapsulation substrates is provided with an electrode. When a voltage is applied to the electrodes, the liquid crystals change orientation and modify the light transmission through the cell, the glazing changing from a clear state to a dark state, or vice versa. The terms "clear state" and "dark state" mean the state of the glazing at its maximum or minimum light transmission respectively.

[0005] Toutefois, dans certaines applications, en particulier pour des vitrages extérieurs, les performances optiques se dégradent avec le temps car les colorants dichroïques de la cellule à cristaux liquides sont sensibles à une irradiation lumineuse et/ou à la chaleur. La composante spectrale ultraviolette (UV) et celle infrarouge (IR) conduisent tout particulièrement à une dégradation des colorants dichroïques se manifestant par exemple par leur changement de couleur et engendrant une décoloration inesthétique du vitrage ainsi qu'un contraste réduit entre les deux états de commutation. [0005] However, in certain applications, in particular for exterior glazing, the optical performance deteriorates over time because the dichroic dyes of the liquid crystal cell are sensitive to light irradiation and/or heat. The ultraviolet (UV) spectral component and the infrared (IR) spectral component in particular lead to a degradation of the dichroic dyes, manifesting itself for example by their change of color and causing an unsightly discoloration of the glazing as well as a reduced contrast between the two switching states.

[0006] Afin de protéger les colorants dichroïques des rayons UV (entre 320 nm et 380 nm) et des rayons du proche IR (entre 0,7 et 2,5 pm), le vitrage peut comprendre des bloqueurs ou absorbeurs d'UV ou encore des réflecteurs UV filtrant le rayonnement ultraviolet et des réflecteurs d'IR ou absorbeurs d'IR. Les bloqueurs ou absorbeurs d'UV sont par exemple constitués de couches intermédiaires dans le vitrage ou de cristaux liquides chargés de molécules absorbant les UV. Les réflecteurs d'IR sont quant à eux des couches intégrées au vitrage feuilleté, qui sont aptes à réfléchir les IR et sont dites couches à faible émissivité ou couche de contrôle solaire. Cependant, on s'est aperçu que la durabilité des cellules à cristaux liquides avec colorants dichroïques n'est pas encore celle attendue. [0006] In order to protect the dichroic dyes from UV rays (between 320 nm and 380 nm) and near IR rays (between 0.7 and 2.5 pm), the glazing may comprise UV blockers or absorbers or UV reflectors filtering ultraviolet radiation and IR reflectors or IR absorbers. The UV blockers or absorbers are, for example, made up of intermediate layers in the glazing or liquid crystals charged with UV-absorbing molecules. IR reflectors are layers integrated into laminated glazing, which are capable of reflecting IR and are called low-emissivity layers or solar control layers. However, it has been found that the durability of liquid crystal cells with dichroic dyes is not yet as expected.

[0007] Par ailleurs, des progrès significatifs ont été réalisés en matière de stabilité à la lumière et/ou à la température des cellules GHLC en travaillant sur la formulation chimique des colorants dichroïques. Ainsi, certaines molécules se révèlent moins sensibles à la dégradation par la lumière et/ou la température, ce qui peut permettre de s'affranchir de l'ajout de filtres UV. Néanmoins, ces molécules présentent des performances optiques qui sont inférieures à celles attendues pour des vitrages. [0007] Furthermore, significant progress has been made in the light and/or temperature stability of GHLC cells by working on the chemical formulation of dichroic dyes. Thus, certain molecules are less sensitive to degradation by light and/or temperature, which can make it possible to dispense with the addition of UV filters. Nevertheless, these molecules have optical performances that are lower than those expected for glazing.

[0008] Par conséquent, les cellules à cristaux liquides qui possèdent une haute performance optique utilisent des colorants dichroïques qui ont malencontreusement une stabilité limitée à la lumière et/ou à la température, et les filtres UV et IR que l'on peut associer n'ont pas encore des performances suffisantes quant à la durabilité des cellules à cristaux liquides avec colorants dichroïques. [0008] Consequently, liquid crystal cells which have high optical performance use dichroic dyes which unfortunately have limited stability to light and/or temperature, and the UV and IR filters which can be associated do not yet have sufficient performance with regard to the durability of liquid crystal cells with dichroic dyes.

[0009] L'invention a donc pour but de proposer un vitrage feuilleté à éléments fonctionnels commutables du type à cristaux liquides et colorants dichroïques (système dit usuellement « guest-host »), qui ne présente pas les inconvénients précités, en particulier un vitrage dont les éléments fonctionnels commutables ne se dégradent pas rapidement avec le temps. [0009] The invention therefore aims to propose a laminated glazing with switchable functional elements of the liquid crystal and dichroic dye type (usually called a "guest-host" system), which does not have the aforementioned drawbacks, in particular a glazing whose switchable functional elements do not deteriorate rapidly over time.

[0010] Selon l'invention, le vitrage feuilleté à transmission lumineuse variable par cristaux liquides comporte au moins un premier substrat verrier principal, un deuxième substrat verrier principal, au moins une cellule à cristaux liquides incluant des colorants dichroïques, la cellule étant disposée entre les premier et deuxième substrats verriers, et au moins un filtre UV bloquant les UV jusqu'à 380 nm, et est caractérisé en ce que le vitrage feuilleté comprend en outre un premier élément filtrant qui filtre la lumière visible dans le domaine de longueurs d'ondes A de 380 à 450 nm, et un second élément filtrant qui filtre la lumière visible dans le domaine de longueurs d'ondes B de 451 à 700 nm, tels que le vitrage feuilleté, dans son état clair à transmission lumineuse maximum, présente une transmission moyenne T(A) inférieure à 30% sur le domaine de longueurs d'ondes A, une transmission moyenne T(B) de 0,1 à 40 % sur le domaine de longueurs d'ondes B, et des coordonnées colorimétriques en transmission a* de 6 à 5, de préférence de -4 à 0, et b* de -5 à 5, de préférence de -3 à 3. [0010] According to the invention, the laminated glazing with variable light transmission by liquid crystals comprises at least a first main glass substrate, a second main glass substrate, at least one liquid crystal cell including dichroic dyes, the cell being arranged between the first and second glass substrates, and at least one UV filter blocking UV up to 380 nm, and is characterized in that the laminated glazing further comprises a first filtering element which filters visible light in the wavelength range A from 380 to 450 nm, and a second filtering element which filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B waves, and transmission colorimetric coordinates a* from 6 to 5, preferably from -4 to 0, and b* from -5 to 5, preferably from -3 to 3.

[0011] La transmission lumineuse (TL) à travers un vitrage est mesurée selon la norme ISO 9050:2023 avec l'illuminant D65. Une transmission moyenne correspond à la moyenne arithmétique des transmissions sur le domaine de longueurs d'ondes considéré, en considérant par exemple un pas de 1 nm. [0011] The light transmission (TL) through a glazing is measured according to the ISO 9050:2023 standard with illuminant D65. An average transmission corresponds to the arithmetic mean of the transmissions over the wavelength range considered, considering for example a step of 1 nm.

[0012] On entend par « qui filtre » dans la suite de la description, le fait qu'une partie du rayonnement lumineux est bloqué ou atténué, par absorption ou par réflexion, c'est-à- dire qu'une partie seulement du rayonnement, sur le domaine de longueurs d'ondes considéré, passe à travers l'élément filtrant. En d'autres termes, un élément qui filtre au moins X % sur un domaine de longueurs d'ondes donné signifie qu'il présente une transmission moyenne d'au plus 100-X % sur ce domaine considéré. [0012] In the remainder of the description, the term "which filters" means that part of the light radiation is blocked or attenuated, by absorption or by reflection, i.e. to say that only a part of the radiation, over the wavelength range considered, passes through the filter element. In other words, an element which filters at least X% over a given wavelength range means that it has an average transmission of at most 100-X% over this range considered.

[0013] Par la suite, l'expression « cellule à cristaux liquides » signifie une cellule à cristaux liquides intégrant des colorants dichroïques. [0013] Hereinafter, the expression “liquid crystal cell” means a liquid crystal cell incorporating dichroic dyes.

[0014] En ajoutant volontairement au moins un élément à fonction de filtre dans la lumière visible, non seulement dans la lumière visible jusqu'à 450 nm mais également jusqu'à 700 nm, tout en conférant une transmission telle que précitée, les inventeurs ont mis en évidence que la durabilité du vitrage à cristaux liquides incluant des colorants dichroïques était significativement améliorée. En outre, le vitrage conserve son aspect esthétique, c'est-à-dire qu'il ne présente pas de déviation de couleur notable, en particulier vers le jaune. Enfin, le choix de la combinaison des éléments filtrants selon l'invention permet de maximiser la transmission lumineuse du vitrage à l'état clair, conservant ainsi son aspect fonctionnel : la fourniture de deux états, clair et sombre, à transmission lumineuse suffisamment différenciée. Ainsi, la solution de l'invention permet de conserver un filtre UV couplé à la cellule à cristaux liquides (le filtre UV étant un moyen simple et peu onéreux de protéger le vitrage et donc la cellule à cristaux liquides des longueurs d'onde jusqu'à 380 nm) et d'augmenter encore la durabilité du vitrage à cristaux liquides tout préservant et les aspects fonctionnels et esthétiques du vitrage. [0014] By deliberately adding at least one element with a filter function in visible light, not only in visible light up to 450 nm but also up to 700 nm, while providing a transmission as mentioned above, the inventors have demonstrated that the durability of the liquid crystal glazing including dichroic dyes was significantly improved. In addition, the glazing retains its aesthetic appearance, that is to say that it does not exhibit any notable color deviation, in particular towards yellow. Finally, the choice of the combination of filter elements according to the invention makes it possible to maximize the light transmission of the glazing in the clear state, thus retaining its functional aspect: the provision of two states, clear and dark, with sufficiently differentiated light transmission. Thus, the solution of the invention makes it possible to retain a UV filter coupled to the liquid crystal cell (the UV filter being a simple and inexpensive means of protecting the glazing and therefore the liquid crystal cell from wavelengths up to 380 nm) and to further increase the durability of the liquid crystal glazing while preserving both the functional and aesthetic aspects of the glazing.

[0015] Selon une caractéristique, le second élément filtrant présente un spectre d'absorption comprenant au moins un pic d'absorption ayant une largeur à mi-hauteur L d'au moins 10 nm et d'au plus 100 nm sur le domaine de longueurs d'ondes B, en particulier une largeur à mi-hauteur L inférieure ou égale à 50 nm sur le domaine de longueurs d'ondes B. De plus, selon une caractéristique, le pic d'absorption présente une intensité maximum lmax comprise entre 5% et 100 %. En particulier, le rapport lmax/L est de préférence compris entre 101 nm 1 et 5.10-4 nm4. [0015] According to one characteristic, the second filter element has an absorption spectrum comprising at least one absorption peak having a half-height width L of at least 10 nm and at most 100 nm over the wavelength range B, in particular a half-height width L of less than or equal to 50 nm over the wavelength range B. In addition, according to one characteristic, the absorption peak has a maximum intensity l max of between 5% and 100%. In particular, the ratio l max /L is preferably between 10 1 nm 1 and 5.10 -4 nm 4 .

[0016] Selon une caractéristique, le premier élément filtrant filtre au moins 40% de la lumière visible sur le domaine de longueurs d'ondes A, notamment au moins 50%, voire au moins 60% sur le domaine de longueurs d'ondes A entre 380 nm et 450 nm, en particulier au moins 90%, de préférence au moins 95%, voire au moins 98%, sur le domaine de longueurs d'ondes A de 380 à 450 nm. [0016] According to one characteristic, the first filtering element filters at least 40% of the visible light in the wavelength range A, in particular at least 50%, or even at least 60% in the wavelength range A between 380 nm and 450 nm, in particular at least 90%, preferably at least 95%, or even at least 98%, in the wavelength range A from 380 to 450 nm.

[0017] Il n'était pas évident de parvenir à un résultat de protection aussi performant de la cellule à cristaux liquides incorporant des colorants dichroïques avec le vitrage de l'invention. Le gain en durabilité se révèle en effet très supérieur par rapport à une simple relation de proportionnalité de pourcentage de filtration. Par exemple, si on filtre 5% de la lumière visible incidente sur le domaine de longueurs d'ondes A, on s'attendrait à réduire la dégradation due à la lumière visible de 5% environ. Or, une filtration inférieure à 5% de la lumière visible sur le domaine de longueurs d'ondes A, couplée à une filtration sur le domaine de longueurs d'ondes B, permet de réduire d'un facteur 4 ou 5 la dégradation de la cellule à cristaux liquides. Les inventeurs ont de plus mis en évidence que la combinaison des deux éléments filtrants au filtre UV préserve l'aspect esthétique du vitrage (sans déviation de couleur), ce qui est grandement apprécié, en particulier pour un vitrage de véhicule ou de bâtiment. [0017] It was not obvious how to achieve such a high-performance protection result for the liquid crystal cell incorporating dichroic dyes with the glazing of the invention. The gain in durability is in fact much higher compared to a simple relationship of proportionality of filtration percentage. For example, if 5% of the incident visible light is filtered in the wavelength range A, one would expect to reduce the degradation due to visible light by approximately 5%. However, filtration of less than 5% of the visible light in the wavelength range A, coupled with filtration in the wavelength range B, makes it possible to reduce the degradation of the liquid crystal cell by a factor of 4 or 5. The inventors have also demonstrated that the combination of the two filtering elements with the UV filter preserves the aesthetic appearance of the glazing (without color deviation), which is greatly appreciated, particularly for vehicle or building glazing.

[0018] Dans un exemple de réalisation, le premier élément filtrant filtre en outre au moins 99%, de préférence 100%, des longueurs d'onde inférieures à 380 nm et constitue ainsi également le filtre UV. En variante, le premier élément filtrant est distinct physiquement du filtre UV. [0018] In an exemplary embodiment, the first filter element further filters at least 99%, preferably 100%, of the wavelengths below 380 nm and thus also constitutes the UV filter. Alternatively, the first filter element is physically distinct from the UV filter.

[0019] Selon une caractéristique, le premier élément filtrant est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier procurant une coloration dudit substrat verrier, ou un film en matière plastique colorée. [0019] According to one characteristic, the first filter element is a mass-colored glass substrate, or a thin layer deposited on a glass substrate providing coloring of said glass substrate, or a colored plastic film.

[0020] Selon une caractéristique, le second élément filtrant est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier, ou un film en matière plastique colorée. [0020] According to one characteristic, the second filter element is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film.

[0021] Chacun des premier et second éléments filtrants peut être un élément coloré qui comprend un agent colorant ou plusieurs agents colorants combinés. [0021] Each of the first and second filter elements may be a colored element that includes one or more coloring agents in combination.

[0022] Selon une caractéristique, lorsque le premier substrat verrier principal est tourné vers l'environnement extérieur en position d'utilisation du vitrage, le premier élément filtrant est agencé entre ledit premier substrat verrier principal et la cellule à cristaux liquides, tandis que le second élément filtrant est agencé entre le premier élément filtrant et la cellule à cristaux liquides, ou bien entre la cellule à cristaux liquides et le deuxième substrat verrier principal. [0022] According to one characteristic, when the first main glass substrate is turned towards the external environment in the position of use of the glazing, the first filtering element is arranged between said first main glass substrate and the liquid crystal cell, while the second filtering element is arranged between the first filtering element and the liquid crystal cell, or between the liquid crystal cell and the second main glass substrate.

[0023] Dans un exemple de réalisation, le premier élément filtrant et le second élément filtrant forment un film unique en matière plastique. En particulier, ce film unique absorbe, par la matière plastique dont il est constitué ou par la présence d'additifs, dans le domaine de longueurs d'ondes A, notamment au-delà de 410 nm, de façon à procurer le premier élément filtrant et comporte en outre un ou plusieurs agents colorants absorbant dans le domaine de longueurs d'ondes B de façon à procurer le second élément filtrant. [0023] In an exemplary embodiment, the first filter element and the second filter element form a single film of plastic material. In particular, this single film absorbs, by the plastic material of which it is made or by the presence of additives, in the wavelength range A, in particular beyond 410 nm, so as to provide the first filter element and further comprises one or more coloring agents absorbing in the wavelength range B so as to provide the second filter element.

[0024] Dans un autre exemple de réalisation, le filtre UV, le premier élément filtrant et le second élément filtrant forment un film unique en matière plastique. En particulier, ce film unique comprend des agents anti-UV et absorbe, par la matière plastique dont il est constitué ou par la présence d'additifs (dont éventuellement les agents anti-UV), dans le domaine de longueurs d'ondes A, notamment au-delà de 410 nm, de façon à procurer le premier élément filtrant et comporte en outre un ou plusieurs agents colorants absorbant dans le domaine de longueurs d'ondes B de façon à procurer le second élément filtrant. [0024] In another embodiment, the UV filter, the first filter element and the second filter element form a single film made of plastic. In particular, this single film comprises anti-UV agents and absorbs, by the plastic material of which it is made or by the presence of additives (including possibly the anti-UV agents), in the wavelength range A, in particular beyond 410 nm, so as to provide the first filter element and further comprises one or more coloring agents absorbing in the wavelength range B so as to provide the second filter element.

[0025] Dans un exemple de réalisation particulier, le second élément filtrant est un film en matière plastique coloré (comprenant une matrice polymérique et au moins un agent colorant dispersé dans la matrice). [0026] Dans un autre exemple de réalisation, le premier élément filtrant est un substrat verrier coloré dans la masse et le second élément filtrant est une couche polymérique colorée déposée sur un substrat verrier. En particulier, la couche polymérique constituant le second élément filtrant présente une épaisseur comprise entre 0,1 mm et 2 mm, de préférence d'au plus 1 mm. [0025] In a particular embodiment, the second filter element is a colored plastic film (comprising a polymer matrix and at least one coloring agent dispersed in the matrix). [0026] In another embodiment, the first filter element is a mass-colored glass substrate and the second filter element is a colored polymer layer deposited on a glass substrate. In particular, the polymer layer constituting the second filter element has a thickness of between 0.1 mm and 2 mm, preferably at most 1 mm.

[0027] Selon une caractéristique, le vitrage présente, dans son état clair à transmission lumineuse maximum, une transmission lumineuse (TL) supérieure à 5%. En particulier, un vitrage feuilleté selon l'invention dans l'automobile, tel qu'un toit vitré ou un parebrise (zones inférieure et/ou supérieure), la TL du vitrage est inférieure ou égale à 5% dans l'état sombre, de préférence inférieure à 2%, encore préférentiellement inférieure à 1% ou même inférieure à 0,5%, et la TL est supérieure ou égale à 5% à l'état clair, de préférence au moins comprise entre 15% et 20%, et le contraste de la TL entre les états sombre et clair est compris entre 2 et 100. [0027] According to one characteristic, the glazing has, in its clear state at maximum light transmission, a light transmission (TL) greater than 5%. In particular, a laminated glazing according to the invention in the automobile, such as a glass roof or a windshield (lower and/or upper zones), the TL of the glazing is less than or equal to 5% in the dark state, preferably less than 2%, more preferably less than 1% or even less than 0.5%, and the TL is greater than or equal to 5% in the clear state, preferably at least between 15% and 20%, and the contrast of the TL between the dark and light states is between 2 and 100.

[0028] Dans un exemple de réalisation, le filtre UV est une couche mince appliquée sur la face interne ou externe du premier substrat verrier principal (substrat verrier destiné à être tourné vers l'extérieur en position d'utilisation du vitrage), ou bien est un film en matière plastique agencé entre le premier substrat verrier principal et la cellule à cristaux liquides. [0028] In an exemplary embodiment, the UV filter is a thin layer applied to the internal or external face of the first main glass substrate (glass substrate intended to be turned outwards in the position of use of the glazing), or is a plastic film arranged between the first main glass substrate and the liquid crystal cell.

[0029] Selon une caractéristique, le filtre UV et/ou le premier élément filtrant et/ou le second élément filtrant est un film en matière polymérique qui est à base d'au moins un polymère choisi parmi les polymères suivants : polybutyral de vinyle (PVB), éthylène vinyle acétate (EVA), polyuréthane (PU), polyéthylène téréphtalate (PET), polyéthylène, polycarbonate, polyméthylméthacrylate, polyacrylate, polychlorure de vinyle, résine de polyacétate, acrylate, éthylène propylène fluoré, polyfluorure de vinyle, éthylène tétrafluoroéthylène, copolymère d'oléfine cyclique (COC), matériau adhésif transparent (OCA pour « Optical Clear Adhesive » en anglais). L'OCA est notamment du type acrylique, acétate de polyvinyle (PVA), polyuréthane (PU), silicone, ou époxy. Le matériau adhésif transparent (OCA) peut être déposé à l'état solide de type sensible à la pression (film PSA), ou à l'état liquide (résine) et durci pendant le procédé de feuilletage formant après durcissement un film intercalaire. L'épaisseur du film polymérique est de préférence comprise entre 0,02 mm et 2 mm, de préférence de 0,3 mm à 1 mm. [0029] According to one characteristic, the UV filter and/or the first filter element and/or the second filter element is a film made of polymeric material which is based on at least one polymer chosen from the following polymers: polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene, polycarbonate, polymethylmethacrylate, polyacrylate, polyvinyl chloride, polyacetate resin, acrylate, fluorinated ethylene propylene, polyvinyl fluoride, ethylene tetrafluoroethylene, cyclic olefin copolymer (COC), transparent adhesive material (OCA for "Optical Clear Adhesive" in English). The OCA is in particular of the acrylic, polyvinyl acetate (PVA), polyurethane (PU), silicone, or epoxy type. The transparent adhesive material (OCA) can be deposited in the solid state of pressure-sensitive type (PSA film), or in the liquid state (resin) and cured during the lamination process, forming an interlayer film after curing. The thickness of the polymeric film is preferably between 0.02 mm and 2 mm, preferably from 0.3 mm to 1 mm.

[0030] Selon un exemple de réalisation, la cellule à cristaux liquides comporte des substrats d'encapsulation faits de films d'encapsulation en matière polymérique. [0030] According to an exemplary embodiment, the liquid crystal cell comprises encapsulation substrates made of encapsulation films made of polymeric material.

[0031] Selon un autre exemple de réalisation, la cellule à cristaux liquides comporte des substrats d'encapsulation faits de substrats verriers d'encapsulation, la cellule étant feuilletée de façon que chacun des deux substrats verriers d'encapsulation soit rendu solidaire de l'un des deux substrats verriers principaux via au moins un intercalaire en matière plastique, au moins un intercalaire étant le filtre UV et au moins un intercalaire étant le premier élément filtrant et/ou le second élément filtrant. [0031] According to another exemplary embodiment, the liquid crystal cell comprises encapsulation substrates made of encapsulation glass substrates, the cell being laminated so that each of the two encapsulation glass substrates is made integral with one of the two main glass substrates via at least one plastic interlayer, at least one interlayer being the UV filter and at least one interlayer being the first filter element and/or the second filter element.

[0032] Selon une autre caractéristique, le vitrage feuilleté comporte au moins un revêtement de protection infrarouge, en particulier le revêtement de protection infrarouge étant disposé sur la face interne ou externe du premier substrat verrier principal et de préférence sur la face externe ou interne du deuxième substrat verrier principal. Le revêtement de protection infrarouge est par exemple une couche mince appliquée sur la face interne ou externe du premier substrat verrier principal et/ou un film intercalaire agencé entre le premier substrat verrier principal et la cellule à cristaux liquides. Cette configuration permet de réfléchir les IR afin que la chaleur et/ou les radiations IR ne dégradent pas les agents colorants dichroïques de la cellule à cristaux liquides. [0032] According to another characteristic, the laminated glazing comprises at least one coating of infrared protection, in particular the infrared protection coating being arranged on the inner or outer face of the first main glass substrate and preferably on the outer or inner face of the second main glass substrate. The infrared protection coating is for example a thin layer applied to the inner or outer face of the first main glass substrate and/or an interlayer film arranged between the first main glass substrate and the liquid crystal cell. This configuration makes it possible to reflect IR so that heat and/or IR radiation do not degrade the dichroic coloring agents of the liquid crystal cell.

[0033] Selon une autre caractéristique, la cellule à cristaux liquides intégrant des colorants dichroïques est une cellule hôte-invité dite « GHLC » (pour « Guest-Host Liquide Crystal » en anglais) ou une cellule à base de polymère telle qu'une cellule PDLC (pour « Polymer- Dispersed Liquid Crystal » en anglais), ou une cellule PNLC (pour « Polymer Network Liquid Crystal » en anglais) ou une cellule PSLC (pour « Polymer stabilized liquid crystal »). [0033] According to another characteristic, the liquid crystal cell integrating dichroic dyes is a host-guest cell called “GHLC” (for “Guest-Host Liquid Crystal” in English) or a polymer-based cell such as a PDLC cell (for “Polymer-Dispersed Liquid Crystal” in English), or a PNLC cell (for “Polymer Network Liquid Crystal” in English) or a PSLC cell (for “Polymer stabilized liquid crystal”).

[0034] Le vitrage feuilleté peut comporter d'autres fonctionnalités, qui sont ajoutées via des revêtements en contact direct avec les substrats verriers principaux et/ou (les substrats d'encapsulation de) la cellule à cristaux liquides et/ou avec des films intercalaires, ou qui sont apportées par directement un ou des films intercalaires. Ces fonctionnalités diverses sont par exemple des propriétés acoustiques, antireflets, antiadhésifs, anti-rayures, photocatalytiques, anti-traces de doigts, antibuée, d'extraction de lumière, etc. [0034] The laminated glazing may include other functionalities, which are added via coatings in direct contact with the main glass substrates and/or (the encapsulation substrates of) the liquid crystal cell and/or with interlayer films, or which are provided directly by one or more interlayer films. These various functionalities are, for example, acoustic, anti-reflective, non-stick, anti-scratch, photocatalytic, anti-fingerprint, anti-fog, light extraction properties, etc.

[0035] Le vitrage feuilleté de l'invention peut constituer un vitrage de bâtiment. [0035] The laminated glazing of the invention can constitute building glazing.

[0036] Le vitrage feuilleté de l'invention peut constituer un vitrage de véhicule, notamment de véhicule choisi parmi une automobile, un train, un camion, un aéronef, un véhicule militaire, un tracteur et un bus. [0036] The laminated glazing of the invention may constitute vehicle glazing, in particular a vehicle chosen from an automobile, a train, a truck, an aircraft, a military vehicle, a tractor and a bus.

[0037] S'il s'agit d'un vitrage de véhicule, le vitrage feuilleté est en particulier choisi parmi un vitrage de toit, une lunette arrière, une vitre latérale, un pare-brise, et une bande en dégradé de la partie supérieure du pare-brise. [0037] If it is vehicle glazing, the laminated glazing is in particular chosen from roof glazing, a rear window, a side window, a windshield, and a gradient band of the upper part of the windshield.

[0038] Le vitrage feuilleté peut être plat ou bombé. [0038] Laminated glazing can be flat or curved.

[0039] Le vitrage feuilleté peut être utilisé dans un double vitrage ou dans un triple vitrage. [0039] Laminated glazing can be used in double glazing or in triple glazing.

[0040] La présente invention est maintenant décrite à l'aide d'exemples uniquement illustratifs et nullement limitatifs de la portée de l'invention, et à partir de la figure [Fig. 1] qui représente une vue schématique en coupe d'un vitrage feuilleté selon un exemple de réalisation de l'invention. [0040] The present invention is now described using examples which are purely illustrative and in no way limitative of the scope of the invention, and from the figure [Fig. 1] which represents a schematic sectional view of a laminated glazing according to an exemplary embodiment of the invention.

[0041] Par souci de clarté, les différents éléments représentés sur les figures ne sont pas reproduits à l'échelle. [0041] For the sake of clarity, the various elements represented in the figures are not reproduced to scale.

[0042] Le vitrage feuilleté 1 de l'invention illustré sur la figure 1 est un vitrage feuilleté à transmission variable par cristaux liquides comportant une cellule à cristaux liquides 2 intégrant des colorants dichroïques. Le vitrage de l'invention a pour but d'augmenter efficacement la durabilité et la stabilité dans le temps des colorants dichroïques de la cellule à cristaux liquides 2. A cet effet, outre un filtre UV bloquant les UV jusqu'à 380 nm, le vitrage 1 comporte un premier élément filtrant qui filtre la lumière visible dans le domaine de longueurs d'ondes A de 380 à 450 nm et un second élément filtrant qui filtre la lumière visible dans le domaine de longueurs d'ondes B de 451 à 700 nm. [0042] The laminated glazing 1 of the invention illustrated in Figure 1 is a laminated glazing with variable transmission by liquid crystals comprising a liquid crystal cell 2 integrating dichroic dyes. The glazing of the invention aims to effectively increase the durability and stability over time of the dichroic dyes of the liquid crystal cell 2. To this end, in addition to a UV filter blocking UV up to 380 nm, the glazing 1 comprises a first filtering element which filters visible light in the wavelength range A from 380 to 450 nm and a second filtering element which filters visible light in the wavelength range B from 451 to 700 nm.

[0043] Le vitrage feuilleté 1 est destiné à une application bâtiment ou une application de véhicule. Le vitrage feuilleté 1 voit sa transmission lumineuse modifiée lorsqu'une tension électrique est appliquée aux électrodes de la cellule à cristaux liquides 2. Le vitrage 1 peut être normalement clair (de transmission lumineuse maximale) en l'absence de tension, et il devient sombre (de transmission lumineuse minimale), en appliquant une tension. Inversement, on peut concevoir le vitrage comme normalement sombre, hors tension ; il devient alors clair par application d'une tension. L'état normalement clair ou normalement sombre est fonction de l'utilisation du vitrage. [0043] The laminated glazing 1 is intended for a building application or a vehicle application. The laminated glazing 1 has its light transmission modified when an electrical voltage is applied to the electrodes of the liquid crystal cell 2. The glazing 1 can be normally clear (with maximum light transmission) in the absence of voltage, and it becomes dark (with minimum light transmission), by applying a voltage. Conversely, the glazing can be conceived as normally dark, without voltage; it then becomes clear by applying a voltage. The normally clear or normally dark state depends on the use of the glazing.

[0044] Selon les utilisations faites du vitrage feuilleté 1 décrit ci-après en regard de la figure 1 ou dans des variantes envisagées non illustrées, il sera employé de manière monobloc tel quel en tant que vitrage simple, ou sera combiné à un ou d'autres substrats verriers en feuilleté ou espacés. [0044] Depending on the uses made of the laminated glazing 1 described below with reference to FIG. 1 or in envisaged variants not illustrated, it will be used in a single-piece manner as is as single glazing, or will be combined with one or more other laminated or spaced glass substrates.

[0045] Le vitrage feuilleté 1 illustré sur la figure 1 comporte un premier substrat verrier principal 10, un deuxième substrat verrier principal 11 agencé à distance et à l'opposé du premier substrat 10, la cellule à cristaux liquides 2 agencée au cœur du vitrage, un filtre UV 3 bloquant les UV jusqu'à 380 nm et des éléments intercalaires, ici 40, 41 et 42, de solidarisation de la cellule à cristaux liquides 2 aux substrats verriers 10 et 11 et/ou aux premier et second éléments filtrants, et lesdits premier et second éléments filtrants 5 et 6. Selon la nature de la cellule à cristaux liquides 2 et le support constitutif (la matrice) des éléments filtrants, les éléments intercalaires de solidarisation pourront par exemple être un film PVB ou une couche d'OCA. Les éléments intercalaires de solidarisation présentent notamment une épaisseur comprise entre 0,1 mm et 2 mm, en particulier est de 0,38 mm ou 0,76 mm. [0045] The laminated glazing 1 illustrated in FIG. 1 comprises a first main glass substrate 10, a second main glass substrate 11 arranged at a distance and opposite the first substrate 10, the liquid crystal cell 2 arranged at the heart of the glazing, a UV filter 3 blocking UV up to 380 nm and intermediate elements, here 40, 41 and 42, for securing the liquid crystal cell 2 to the glass substrates 10 and 11 and/or to the first and second filtering elements, and said first and second filtering elements 5 and 6. Depending on the nature of the liquid crystal cell 2 and the constituent support (the matrix) of the filtering elements, the intermediate securing elements may for example be a PVB film or an OCA layer. The intermediate securing elements have a thickness of between 0.1 mm and 2 mm, in particular 0.38 mm or 0.76 mm.

[0046] Les substrats verriers principaux 10 et 11 possèdent une épaisseur adaptée à l'utilisation du vitrage feuilleté. L'épaisseur peut être comprise entre 0,3 mm et 15 mm, de préférence entre 1 à 5 mm ; elle est par exemple de 1,6 mm, 1,8 mm ou 2,1 mm. [0046] The main glass substrates 10 and 11 have a thickness suitable for the use of laminated glazing. The thickness may be between 0.3 mm and 15 mm, preferably between 1 and 5 mm; it is for example 1.6 mm, 1.8 mm or 2.1 mm.

[0047] La cellule à cristaux liquides 2 est par exemple une cellule à cristaux liquides guest-host comprenant un volume liquide de cristaux liquides mélangés à des colorants dichroïques. La cellule à cristaux liquides 2 est du type connu. [0047] The liquid crystal cell 2 is for example a guest-host liquid crystal cell comprising a liquid volume of liquid crystals mixed with dichroic dyes. The liquid crystal cell 2 is of the known type.

[0048] Le premier substrat verrier 10 étant destiné à être tourné vers l'environnement extérieur, le filtre UV 3 lui est associé. [0048] The first glass substrate 10 being intended to be turned towards the external environment, the UV filter 3 is associated with it.

[0049] Le filtre UV 3 est dans une matière polymérique telle qu'en PVB, possédant la propriété de couper les ultraviolets jusqu'à 380 nm. La propriété de coupure dans l'ultraviolet est fournie de préférence par des molécules dispersées dans la matrice polymérique du film, qui sont aptes à bloquer les ultraviolets et qui n'absorbent pas dans le rayonnement visible. [0050] Le filtre UV 3 présente une transmission pour chaque longueur d'onde dans le domaine de longueurs d'ondes de 280 nm à 380 nm inférieure à 1%, de préférence inférieure à 0,1 %, de préférence encore inférieure à 0,01%, de préférence égale à 0%. [0049] The UV filter 3 is made of a polymeric material such as PVB, having the property of cutting ultraviolet rays up to 380 nm. The ultraviolet cutting property is preferably provided by molecules dispersed in the polymeric matrix of the film, which are capable of blocking ultraviolet rays and which do not absorb visible radiation. [0050] The UV filter 3 has a transmission for each wavelength in the wavelength range from 280 nm to 380 nm of less than 1%, preferably less than 0.1%, more preferably less than 0.01%, preferably equal to 0%.

[0051] De plus, le vitrage 1 comporte le premier élément filtrant 5 qui filtre la lumière visible dans le domaine de longueurs d'ondes A de 380 à 450 nm, et le second élément filtrant 6 qui filtre la lumière visible dans le domaine de longueurs d'ondes B de 451 à 700 nm, les premier et second éléments filtrants 5 et 6 étant tels que le vitrage feuilleté 1, dans son état clair à transmission lumineuse maximum, présente une transmission moyenne T(A) inférieure à 30% sur le domaine de longueurs d'ondes A, une transmission moyenne T(B) de 0,1 à 40 % sur le domaine de longueurs d'ondes B, et des coordonnées colorimétriques en transmission a* de -6 à 5, de préférence de -4 à 0, et b* de -5 à 5, de préférence de -3 à 3. [0051] In addition, the glazing 1 comprises the first filtering element 5 which filters visible light in the wavelength range A from 380 to 450 nm, and the second filtering element 6 which filters visible light in the wavelength range B from 451 to 700 nm, the first and second filtering elements 5 and 6 being such that the laminated glazing 1, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B, and colorimetric coordinates in transmission a* of -6 to 5, preferably of -4 to 0, and b* of -5 to 5, preferably of -3 to 3.

[0052] Le premier élément filtrant 5 est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier, ou un film en matière plastique colorée. Le second élément filtrant 6 est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier, ou un film en matière plastique colorée. Les agents colorants des premier et second éléments filtrants 5 et 6 sont sélectionnés pour conférer les propriétés filtrantes précitées pour le vitrage. [0052] The first filter element 5 is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film. The second filter element 6 is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film. The coloring agents of the first and second filter elements 5 and 6 are selected to provide the aforementioned filtering properties for the glazing.

[0053] Afin de préserver la cellule à cristaux liquides 2 contre la chaleur du rayonnement infrarouge, le vitrage 1 comporte de préférence un revêtement de protection infrarouge 70 (de contrôle solaire) qui est agencé sur la face interne (dite face F2) du premier substrat verrier principal 10 (lorsque ce premier substrat verrier est destiné à être tourné vers l'extérieur, tel que l'extérieur de l'habitacle du véhicule). Ce revêtement de protection IR protège la cellule à cristaux liquides 2 de la chaleur que peut subir le vitrage par le rayonnement solaire. [0053] In order to protect the liquid crystal cell 2 against the heat of infrared radiation, the glazing 1 preferably comprises an infrared protective coating 70 (solar control) which is arranged on the internal face (called face F2) of the first main glass substrate 10 (when this first glass substrate is intended to be turned towards the outside, such as the outside of the passenger compartment of the vehicle). This IR protective coating protects the liquid crystal cell 2 from the heat that the glazing can undergo due to solar radiation.

[0054] Le vitrage 1 peut comprendre une couche basse émissive 71 sur la face externe du deuxième substrat verrier principal 11 (face destinée à être tournée vers l'habitacle du véhicule, dite face F4) pour minimiser la déperdition de chaleur dans l'habitacle en hiver et la sensation de paroi froide. [0054] The glazing 1 may comprise a low-emissive layer 71 on the external face of the second main glass substrate 11 (face intended to be turned towards the passenger compartment of the vehicle, called face F4) to minimize heat loss in the passenger compartment in winter and the sensation of a cold wall.

[0055] Dans l'exemple illustré de la figure 1, sont empilés depuis le premier substrat verrier 10 et entre ledit premier substrat verrier 10 et la cellule à cristaux liquides 2, le revêtement de protection infrarouge 70, le filtre UV 3, le premier élément filtrant 5 qui est un substrat verrier coloré, un intercalaire 40 tel qu'un film en PVB, un substrat verrier 60 dont la TL est de préférence d'au moins 91%, le second élément filtrant 6 à matrice polymérique déposé sur le substrat verrier 60, et un OCA 41. L'intercalaire 40 a permis de solidariser le premier élément filtrant 5 en verre au substrat verrier 60. L'OCA 41 a permis de solidariser la matrice polymérique du second élément filtrant 6 à la cellule à cristaux liquides 2 dont les substrats d'encapsulation sont polymériques. De l'autre côté de la cellule à cristaux liquides 2, ladite cellule est solidarisée au deuxième substrat verrier 11 par un OCA 42. [0056] Dans cet exemple illustré, [0055] In the example illustrated in FIG. 1, stacked from the first glass substrate 10 and between said first glass substrate 10 and the liquid crystal cell 2 are the infrared protective coating 70, the UV filter 3, the first filter element 5 which is a colored glass substrate, an interlayer 40 such as a PVB film, a glass substrate 60 whose TL is preferably at least 91%, the second filter element 6 with a polymer matrix deposited on the glass substrate 60, and an OCA 41. The interlayer 40 made it possible to secure the first glass filter element 5 to the glass substrate 60. The OCA 41 made it possible to secure the polymer matrix of the second filter element 6 to the liquid crystal cell 2 whose encapsulation substrates are polymeric. On the other side of the liquid crystal cell 2, said cell is secured to the second glass substrate 11 by an OCA 42. [0056] In this illustrated example,

- le filtre UV 3 est un film du commerce en PVB filtrant les ultraviolets, par exemple le film commercialisé sous la dénomination Saflex®PVB de la société Eastman d'épaisseur 0,76 mm qui filtre à 99% jusqu'à 380 nm ; - the UV 3 filter is a commercial PVB film that filters ultraviolet rays, for example the film sold under the name Saflex®PVB from the Eastman company, 0.76 mm thick, which filters 99% up to 380 nm;

- le premier élément filtrant 5 est un substrat verrier qui est coloré (le verre du substrat verrier comprenant un agent colorant) et présente une épaisseur de 0,38 mm. Le substrat verrier coloré constituant le premier élément filtrant 5 est du commerce, il s'agit par exemple du produit commercialisé sous la dénomination GG435 de la société SCHOTT. Ce premier élément filtrant 5 filtre la lumière visible jusqu'à 435 nm, de sorte qu'il présente une transmission nulle pour chaque longueur d'onde jusqu'à 435 nm ; - the first filter element 5 is a glass substrate which is colored (the glass of the glass substrate comprising a coloring agent) and has a thickness of 0.38 mm. The colored glass substrate constituting the first filter element 5 is commercially available, for example the product marketed under the name GG435 from the company SCHOTT. This first filter element 5 filters visible light up to 435 nm, so that it has zero transmission for each wavelength up to 435 nm;

- le second élément filtrant 6 est une couche polymérique comprenant un agent colorant. L'agent colorant est par exemple le produit commercialisé sous la dénomination FDG-005 de la société Yamada Chemicals. Ce colorant FDG-005 présente un pic d'absorbance à 580 nm, et une largeur à mi-hauteur de 30 nm à une concentration de 0,26 % par rapport au poids total sec et pour une épaisseur de film de 8 pm ; - the second filter element 6 is a polymeric layer comprising a coloring agent. The coloring agent is for example the product marketed under the name FDG-005 from the company Yamada Chemicals. This dye FDG-005 has an absorbance peak at 580 nm, and a width at half-maximum of 30 nm at a concentration of 0.26% relative to the total dry weight and for a film thickness of 8 μm;

- le substrat verrier 60 comprenant le second élément filtrant 6 est un verre clair tel que le produit commercialisé sous la dénomination PLANICLEAR® de la société SAINT- GOBAIN ; son épaisseur est de 2,1 mm. - the glass substrate 60 comprising the second filter element 6 is a clear glass such as the product marketed under the name PLANICLEAR® from the company SAINT-GOBAIN; its thickness is 2.1 mm.

[0057] Plus particulièrement, dans l'exemple précité pour le second élément filtrant 6, on prépare une solution comprenant un solvant tel que le méthyléthylcétone (MEK) selon 70 % en poids, du polyméthacrylate de méthyle acrylique (PMMA) selon 29,3 % en poids et du FDG-005 selon 0,7 % en poids. Après mélange, la solution est déposée sur le substrat verrier 60 au moyen d'un tire-film pour obtenir une couche de 8 pm. Après accouplement du second élément filtrant 6 au premier élément filtrant 5 en assemblant le substrat verrier 60 du second élément filtrant 6 au premier élément filtrant 5 via l'intercalaire 40, le second élément filtrant 6 se situe du côté de la cellule à cristaux liquides 2. [0057] More particularly, in the above-mentioned example for the second filter element 6, a solution is prepared comprising a solvent such as methyl ethyl ketone (MEK) at 70% by weight, polymethyl methacrylate acrylic (PMMA) at 29.3% by weight and FDG-005 at 0.7% by weight. After mixing, the solution is deposited on the glass substrate 60 by means of a film puller to obtain a layer of 8 μm. After coupling the second filter element 6 to the first filter element 5 by assembling the glass substrate 60 of the second filter element 6 to the first filter element 5 via the interlayer 40, the second filter element 6 is located on the side of the liquid crystal cell 2.

[0058] La combinaison du filtre UV 3 ainsi que des premier élément filtrant 5 et second élément filtrant 6 agissant respectivement dans les domaines du visible de longueurs d'ondes A et B, permet d'augmenter efficacement la durabilité et la stabilité dans le temps des colorants dichroïques de la cellule à cristaux liquides 2, tout en préservant ses propriétés esthétiques. La transmission lumineuse du vitrage de l'exemple précité reste tout à fait acceptable en état clair avec une transmission moyenne T(A) de 3% sur le domaine de longueurs d'ondes A, une transmission moyenne T(B) de 17% sur le domaine de longueurs d'ondes B, et des coordonnées colorimétriques en transmission a* de -2 et b* de 1 selon l'illuminant CIE D65 2° (CIE 1931). [0058] The combination of the UV filter 3 as well as the first filter element 5 and second filter element 6 acting respectively in the visible wavelength ranges A and B, makes it possible to effectively increase the durability and stability over time of the dichroic dyes of the liquid crystal cell 2, while preserving its aesthetic properties. The light transmission of the glazing of the aforementioned example remains entirely acceptable in the clear state with an average transmission T(A) of 3% over the wavelength range A, an average transmission T(B) of 17% over the wavelength range B, and colorimetric coordinates in transmission a* of -2 and b* of 1 according to the CIE illuminant D65 2° (CIE 1931).

[0059] Par ailleurs, la variation de couleur AE du vitrage de l'exemple précité est inférieur à 5, après un test de vieillissement accéléré qui correspond à 1400 heures de fonctionnement de la cellule à cristaux liquides 2, alors que comparativement, un vitrage avec la même cellule à cristaux liquides 2 protégée par le seul et même filtre UV 3 présente une variation de couleur AE de 26 après le même test de vieillissement accéléré. [0059] Furthermore, the color variation AE of the glazing of the aforementioned example is less than 5, after an accelerated aging test which corresponds to 1400 hours of operation of the liquid crystal cell 2, whereas comparatively, a glazing with the same liquid crystal cell 2 protected by the single and same UV filter 3 has a AE color variation of 26 after the same accelerated aging test.

[0060] Ainsi, les inventeurs ont mis en évidence de manière surprenante qu'en ajoutant au filtre UV qui filtre jusqu'à 380 nm, le premier élément filtrant et le second élément filtrant selon l'invention qui filtrent respectivement dans le visible au-delà de 380 nm jusqu'à 450 nm et entre 451 nm et 700 nm, on parvient à augmenter la durabilité et la stabilité de la cellule 2 à cristaux liquides et des colorants dichroïques, et donc du vitrage 1, tout en préservant les aspects esthétique et fonctionnel du vitrage. [0060] Thus, the inventors have surprisingly demonstrated that by adding to the UV filter which filters up to 380 nm, the first filtering element and the second filtering element according to the invention which filter respectively in the visible beyond 380 nm up to 450 nm and between 451 nm and 700 nm, it is possible to increase the durability and stability of the liquid crystal cell 2 and the dichroic dyes, and therefore of the glazing 1, while preserving the aesthetic and functional aspects of the glazing.

Claims

Revendications Claims [Revendication 1] Vitrage feuilleté (1) à transmission lumineuse variable par cristaux liquides comportant au moins un premier substrat verrier principal (10), un deuxième substrat verrier principal (11), au moins une cellule (2) à cristaux liquides incluant des colorants dichroïques, la cellule (2) étant disposée entre les premier et deuxième substrats verriers (10, 11), et au moins un filtre UV (3) bloquant les UV jusqu'à 380 nm, caractérisé en ce que le vitrage feuilleté comprend en outre un premier élément filtrant (5) qui filtre la lumière visible dans le domaine de longueurs d'ondes A de 380 à 450 nm, et un second élément filtrant (6) qui filtre la lumière visible dans le domaine de longueurs d'ondes B de 451 à 700 nm, tels que le vitrage feuilleté, dans son état clair à transmission lumineuse maximum, présente une transmission moyenne T(A) inférieure à 30% sur le domaine de longueurs d'ondes A, une transmission moyenne T(B) de 0,1 à 40 % sur le domaine de longueurs d'ondes B, et des coordonnées colorimétriques en transmission a* de -6 à 5, de préférence de 4 à 0, et b* de -5 à 5, de préférence de -3 à 3. [Claim 1] Laminated glazing (1) with variable light transmission by liquid crystals comprising at least a first main glass substrate (10), a second main glass substrate (11), at least one liquid crystal cell (2) including dichroic dyes, the cell (2) being arranged between the first and second glass substrates (10, 11), and at least one UV filter (3) blocking UV up to 380 nm, characterized in that the laminated glazing further comprises a first filter element (5) which filters visible light in the wavelength range A from 380 to 450 nm, and a second filter element (6) which filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, a average transmission T(B) of 0.1 to 40% over the wavelength range B, and colorimetric coordinates in transmission a* of -6 to 5, preferably of 4 to 0, and b* of -5 to 5, preferably of -3 to 3. [Revendication 2] Vitrage feuilleté selon la revendication 1, caractérisé en ce que le second élément filtrant (6) présente un spectre d'absorption comprenant au moins un pic d'absorption ayant une largeur à mi-hauteur L d'au moins 10 nm et d'au plus 100 nm sur le domaine de longueurs d'ondes B, en particulier une largeur à mi- hauteur L inférieure ou égale à 50 nm sur le domaine de longueurs d'ondes B. [Claim 2] Laminated glazing according to claim 1, characterized in that the second filter element (6) has an absorption spectrum comprising at least one absorption peak having a half-height width L of at least 10 nm and at most 100 nm over the wavelength range B, in particular a half-height width L of less than or equal to 50 nm over the wavelength range B. [Revendication 3] Vitrage feuilleté selon la revendication précédente, caractérisé en que le pic d'absorption présente une intensité maximum lmax comprise entre 5% et 100 %, le rapport lmax/L étant de préférence compris entre 10 1 nm 1 et 5.10-4 nm4.[Claim 3] Laminated glazing according to the preceding claim, characterized in that the absorption peak has a maximum intensity l max of between 5% and 100%, the ratio l max /L preferably being between 10 1 nm 1 and 5.10 -4 nm 4 . [Revendication 4] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce que le premier élément filtrant (5) filtre au moins 40% de la lumière visible sur le domaine de longueurs d'ondes A, notamment au moins 50%, voire au moins 60%, en particulier au moins 90%, de préférence au moins 95%, voire au moins 98%, sur le domaine de longueurs d'ondes A. [Claim 4] Laminated glazing according to any one of the preceding claims, characterized in that the first filtering element (5) filters at least 40% of the visible light in the wavelength range A, in particular at least 50%, or even at least 60%, in particular at least 90%, preferably at least 95%, or even at least 98%, in the wavelength range A. [Revendication 5] Vitrage feuilleté selon l'une des revendications précédentes, caractérisé en ce que le premier élément filtrant (5) filtre au moins 99%, de préférence 100%, des longueurs d'onde inférieures à 380 nm et constitue également le filtre UV[Claim 5] Laminated glazing according to one of the preceding claims, characterized in that the first filtering element (5) filters at least 99%, preferably 100%, of wavelengths below 380 nm and also constitutes the UV filter [Revendication 6] Vitrage feuilleté selon l'une des revendications 1 à 4, caractérisé en ce que le premier élément filtrant (5) est distinct physiquement du filtre UV (3). [Claim 6] Laminated glazing according to one of claims 1 to 4, characterized in that the first filtering element (5) is physically distinct from the UV filter (3). [Revendication 7] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce que le premier élément filtrant (5) est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier, ou un film en matière plastique colorée. [Claim 7] Laminated glazing according to any one of the preceding claims, characterized in that the first filtering element (5) is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film. [Revendication 8] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce que le second élément filtrant (6) est un substrat verrier coloré dans la masse, ou une couche mince déposée sur un substrat verrier, ou un film en matière plastique colorée. [Claim 8] Laminated glazing according to any one of the preceding claims, characterized in that the second filtering element (6) is a mass-colored glass substrate, or a thin layer deposited on a glass substrate, or a colored plastic film. [Revendication 9] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce que lorsque le premier substrat verrier principal (10) est tourné vers l'environnement extérieur en position d'utilisation du vitrage, le premier élément filtrant (5) est agencé entre ledit premier substrat verrier principal (10) et la cellule à cristaux liquides (2), tandis que le second élément filtrant (6) est agencé entre le premier élément filtrant (5) et la cellule à cristaux liquides (2), ou bien entre la cellule à cristaux liquides (2) et le deuxième substrat verrier principal (11). [Claim 9] Laminated glazing according to any one of the preceding claims, characterized in that when the first main glass substrate (10) is turned towards the external environment in the position of use of the glazing, the first filtering element (5) is arranged between said first main glass substrate (10) and the liquid crystal cell (2), while the second filtering element (6) is arranged between the first filtering element (5) and the liquid crystal cell (2), or between the liquid crystal cell (2) and the second main glass substrate (11). [Revendication 10] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce que le premier élément filtrant (5) et le second élément filtrant (6) forment un film unique en matière plastique. [Claim 10] Laminated glazing according to any one of the preceding claims, characterized in that the first filter element (5) and the second filter element (6) form a single film of plastic material. [Revendication 11] Vitrage feuilleté selon l'une quelconque des revendications 1 à 5, caractérisé en ce que le filtre UV (3), le premier élément filtrant (5) et le second élément filtrant (6) forment un film unique en matière plastique. [Claim 11] Laminated glazing according to any one of claims 1 to 5, characterized in that the UV filter (3), the first filter element (5) and the second filter element (6) form a single film of plastic material. [Revendication 12] Vitrage feuilleté selon l'une quelconque des revendications 1 à 9, caractérisé en ce que le premier élément filtrant (5) est un substrat verrier coloré dans la masse et le second élément filtrant (6) est une couche polymérique colorée déposée sur un substrat verrier. [Claim 12] Laminated glazing according to any one of claims 1 to 9, characterized in that the first filter element (5) is a mass-colored glass substrate and the second filter element (6) is a colored polymeric layer deposited on a glass substrate. [Revendication 13] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comporte au moins un revêtement de protection infrarouge (70, 71), en particulier le revêtement de protection infrarouge étant disposé sur la face interne ou externe du premier substrat verrier principal (10) et de préférence sur la face externe ou interne du deuxième substrat verrier principal (11). [Claim 13] Laminated glazing according to any one of the preceding claims, characterized in that it comprises at least one infrared protective coating (70, 71), in particular the infrared protective coating being arranged on the internal or external face of the first main glass substrate (10) and preferably on the external or internal face of the second main glass substrate (11). [Revendication 14] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il est plat ou bombé, pouvant être utilisé en tant que vitrage simple, ou utilisé dans un double vitrage ou dans un triple vitrage. [Claim 14] Laminated glazing according to any one of the preceding claims, characterized in that it is flat or curved, able to be used as single glazing, or used in double glazing or in triple glazing. [Revendication 15] Vitrage feuilleté selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il s'agit d'un vitrage de véhicule choisi parmi une automobile, un train, un camion, un aéronef, un véhicule militaire, un tracteur et un bus. [Claim 15] Laminated glazing according to any one of the preceding claims, characterized in that it is a vehicle glazing chosen from an automobile, a train, a truck, an aircraft, a military vehicle, a tractor and a bus.
PCT/EP2025/057366 2024-03-19 2025-03-18 Laminated glazing with variable transmission Pending WO2025196049A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR2402716A FR3160354A1 (en) 2024-03-19 2024-03-19 Laminated glazing with variable transmission
FRFR2402716 2024-03-19

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WO2025196049A1 true WO2025196049A1 (en) 2025-09-25

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WO (1) WO2025196049A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170192257A1 (en) * 2012-05-29 2017-07-06 Switch Materials Inc. Optical filter comprising a variable transmittance layer
FR3114266A1 (en) * 2020-09-18 2022-03-25 Saint-Gobain Glass France LAMINATED GLAZING WITH LIQUID CRYSTAL AND UV CUTTING
FR3121873A1 (en) * 2021-04-14 2022-10-21 Saint-Gobain Glass France LAMINATED VEHICLE GLAZING, DEVICE WITH ASSOCIATED NEAR INFRARED DETECTION SYSTEM

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170192257A1 (en) * 2012-05-29 2017-07-06 Switch Materials Inc. Optical filter comprising a variable transmittance layer
FR3114266A1 (en) * 2020-09-18 2022-03-25 Saint-Gobain Glass France LAMINATED GLAZING WITH LIQUID CRYSTAL AND UV CUTTING
FR3121873A1 (en) * 2021-04-14 2022-10-21 Saint-Gobain Glass France LAMINATED VEHICLE GLAZING, DEVICE WITH ASSOCIATED NEAR INFRARED DETECTION SYSTEM

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