Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
  • C09K19/54—Additives having no specific mesophase characterised by their chemical composition
  • C09K19/542—Macromolecular compounds
  • C09K19/544—Macromolecular compounds as dispersing or encapsulating medium around the liquid crystal
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
  • C09K19/14—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain
  • C09K19/18—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain the chain containing carbon-to-carbon triple bonds, e.g. tolans
  • C09K2019/183—Ph-Ph-C≡C-Ph
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings
  • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
  • C09K2019/3016—Cy-Ph-Ph
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
  • C09K19/54—Additives having no specific mesophase characterised by their chemical composition
  • C09K19/542—Macromolecular compounds
  • C09K2019/546—Macromolecular compounds creating a polymeric network

Definitions

• the invention relates to the field of electrically controllable glazings with variable optical properties and more particularly to a variable light scattering system comprising a PDLC layer located between two electrodes carried by supports.
• Glazes are known whose characteristics can be modified under the effect of a suitable power supply, especially the transmission, absorption, reflection in certain wavelengths of electromagnetic radiation, especially in the visible and / or in the infrared, or the light diffusion.
• the switchable glazings between a transparent state and a currently available diffusing state comprise a functional film consisting of two electrode-carrying supports in the form of plastic sheets enclosing a layer incorporating liquid-crystal droplets, all laminated via spacers or glued on a glass substrate or between two glass substrates.
• Liquid crystals when the film is switched on (ON state), are oriented along a preferred axis, which allows vision through the functional film.
• OFF state in the absence of alignment in the liquid crystal droplets, the film becomes diffusive and prevents vision.
• switchable windows comprising liquid crystals not using functional film technology.
• These switchable glazings comprise a layer comprising a multitude of liquid crystal droplets without preferential orientations dispersed in a polymer matrix (hereinafter PDLC layer, "Polymer-Dispersed Liquid Crystal”).
• PDLC layer Polymer-Dispersed Liquid Crystal
• the PDLC layer is directly encapsulated between two glass substrates.
• the assembly consisting of the substrates and the PDLC layer is sealed via a sealing gasket or peripheral adhesive bead.
• Patent applications WO 2012/028823 and WO 2012/045973 describe such glazings. The use of this technique makes it possible to manufacture less expensive glazings by saving on the materials used and more efficient from an electro-optical point of view.
• the switchable glazings comprising a layer based on liquid crystals incorporated in a functional film or directly encapsulated between two glass substrates have the disadvantage of not requiring significant tensions of use.
• the effective values of the sinusoidal operating voltages are typically greater than 50 Vrms (rms: "root mean square"). Indeed, in addition to the interest related to the reduction of the electrical consumption and / or the limitation of electrical failures (reduction of the risk of short circuit), the lowering of the operating voltages makes it possible to envisage the use of such systems. for applications requiring greater security such as bathroom applications.
• the switching voltage corresponds to a minimum operating voltage to have a low blur.
• Blur haze is the amount of transmitted light that is scattered at angles of more than 2.5 °. Liquid crystals are all the better ordered (so less blurred) than the applied voltage is high. When the applied voltage is insufficient, the PDLC layer remains diffusing and can generate a white haze. This white veil is the main cause of non-transparency printing.
• the lowering of the switching voltages must therefore not be to the detriment of the optical properties and performances of the systems with variable light diffusion, which are in particular the absence of blur in the transparent state, a good transmission of the light in the state transparent, a transmission of the correct light in the diffusing state and a good hiding power regardless of the angle of view in the diffusing state.
• the hiding power of a glazing in the diffusing state corresponds to its ability not to allow vision through.
• the diffusing systems comprising diffusers dispersed in a matrix diffuse the light differently according to the size and density of the diffusers they contain.
• the variable light scattering systems of the invention in the diffusing state, correspond to diffusing layers comprising as diffusers droplets of liquid crystals dispersed in a volume. These diffusers must have dimensions and a density such that the light passing through the medium constituted by the diffusing layer undergoes Mie diffusion. To observe this phenomenon, the size of the diffusers must be larger than the wavelengths of the visible, typically one or a few micrometers.
• the spatial distribution of the light scattered in transmission is not isotropic and strongly depends on the shape of the diffusers (sphere, cylinder, plate, etc.), their size. and their density.
• a given scattering layer determines its transmission diffusion indicator. This consists in illuminating the diffusing layer at normal incidence and measuring in transmission the intensity of the scattered rays as a function of the angle with respect to the initial direction of illumination.
• This diffusion indicator can be measured using a device measuring the bidirectional transmission distribution function (BTDF) such as the REFLET bench of the STIL company.
• BTDF bidirectional transmission distribution function
• This indicator obtained by measuring the light transmitted over a 90 ° -90 ° arc in the hemisphere opposite that of the incident light, constitutes a peak-shaped curve.
• the information that can be extracted from these scattering indicia results from the height of the peak apex, the shape and width of the peak base.
• the vertex of the peak centered on 0 ° corresponds to the normal angle of incidence, to which the light that has not been diffused comes out.
• the diffusion indicatrices have a variable shape.
• the diffusion indicatrices have a shape close to a quasi-triangular peak.
• the half-width of the base of the triangle corresponds to the limit angle (in absolute value) beyond which almost no ray is diffused. It is then considered that the transmission diffusion indicator is very pointed forward.
• the diffusion indicator can be divided into two main parts. A peak is obtained superimposed on a curve that is called "the bottom" having a bell shape. In this case, rays can be scattered at large angles. It is considered that the transmission diffusion indicator is less pointed forward.
• the transmission scattering indicator analysis makes it possible to demonstrate that when the diffusing layer comprises particles of dimension and density such that the diffusion profile is pointed towards the front, almost no ray is scattered at angles. above a limit value. In this case, the weakness of the average angular deviation of the rays that passes through the scattering layer relative to their initial direction results in a low hiding power. On the other hand, when the scattering layer has a diffusion profile that is not pointed forwardly, the greatest average angular deviation of the rays which passes through the scattering layer relative to their initial direction seems to allow a better hiding power to be obtained.
• Obtaining good hiding power in the diffusing state requires optimization of the size and density of the liquid crystal droplets as well as the thickness of the scattering layer.
• variable light scattering systems comprising a PDLC layer are complex systems, each characteristic of which is capable of influencing the decrease or increase of the switching voltages.
• a number of features affecting hiding power and switching voltages are common. Among the characteristics influencing the switching voltage are:
• the processes for preparing the PDLC layers comprise a phase separation step for forming the liquid crystal droplets dispersed in the polymer matrix.
• the lowering of switching voltages of the variable light scattering systems comprising a PDLC layer depends not only on the starting components but also on the method of preparing said PDLC layer. It is not possible to correlate in a simple manner the parameters of the preparation process and / or the characteristics of the PDLC layer with the decrease of the switching voltage and the improvement of the hiding power.
• variable light diffusion having improved optical properties including good hiding power regardless of the angle of view and better quality in normal vision in the transparent state and at lower cost and with switching voltages lowered.
• the invention thus relates to a variable light scattering system switching between a transparent state and a translucent state comprising a PDLC layer located between two electrodes, the PDLC layer comprising a mixture of liquid crystals forming microdroplets dispersed in a polymer matrix and satisfying the criteria. following:
• the polymer matrix is obtained from a photopolymerizable composition comprising vinyl compounds,
• the proportions by weight of the liquid crystal mixture with respect to the total mass of the liquid crystal and photopolymerizable composition mixture are between 40 and 70%
• the PDLC layer has a thickness of between 5 and 25 ⁇
• the average diameter of the droplets of liquid crystals dispersed in the polymer matrix is between 0.25 ⁇ and 2.00 ⁇ .
• variable light scattering system of the invention combining the claimed characteristics contributes to obtaining the desired properties and in particular exhibits excellent transparency for low applied effective stresses, especially of less than 30 Vrms, and even less than 20 Vrms. or 15 Vrms, and good hiding power in the diffusing state.
• These advantageous properties are in particular obtained with PDLC layers of approximately 15 ⁇ of thickness.
• the PDLC layer has, in order of increasing thickness of 10 to 20 ⁇ or 12 to 17 ⁇ .
• the invention also relates to the use of such a system operating with a switching voltage of less than 30 Vrms.
• a PDLC layer obtained by phase separation induced by polymerization from a radically photopolymerizable composition makes it possible to reduce the ionic pollution in the final product and therefore to limit the screening of the electric field at the level of the droplets of liquid crystal.
• the presence of ionic impurities in a PDLC layer requires the application of a larger voltage to switch to the transparent state because these impurities tend to decrease the effective field at each liquid crystal droplet.
• Radical polymerization does not require as starting compounds ionic species. This type of polymerization does not generate ionic species either. Therefore, in the case of radical polymerization no ionic species is likely to dissolve in the liquid crystal and participate in the screening of the electric field.
• the density of the droplets in the PDLC layer can be estimated indirectly by the average droplet size and the relative mass proportions of the liquid crystal mixture relative to the photopolymerizable composition (assuming very little liquid crystal is dissolved in the matrix). polymer).
• the average size of the droplets and their homogeneity in terms of size and distribution in the PDLC layer strongly depend on the polymerization conditions.
• the ratio of size, droplet density, type of porosity (closed, open or semi-open) of the PDLC layer and the switching voltage is complex.
• the switching voltage for closed porosity spherical droplets is expected to decrease as the size of the droplets increases.
• the increase in droplet size is to the detriment of obtaining a good hiding state diffusing state.
• the choice of a particular morphology for the PDLC layers used according to the invention resulting from the choice of the size of the liquid crystal droplets and the proportion ratio between the mixture of liquid crystals and the photopolymerizable composition contributes to the lowering of the voltages of switching and improving optical properties.
• the morphology of the PDLC layer used according to the invention can be defined by an excellent individualization or non-coalescence of the liquid crystal droplets with each other. These liquid crystal droplets have substantially closed porosity and comprise a lower proportion of liquid crystal at the interface between the liquid crystal mixture and the polymer matrix that can be blocked.
• the choice of this particular morphology is an excellent compromise to lower the switching voltage without impairing optical properties such as obtaining a good hiding power.
• variable light diffusion systems of the invention advantageously have a light transmission that varies little between the transparent state and the diffusing state.
• the variable light scattering system has:
• the light transmission TL it is at least 75%, preferably at least 80% measured according to ASTM D1003 and the blur in the transmission is H is at most 5%, preferably not more than 3% as measured by ASTM D1003, and / or
• the light transmission TL 0 ff is at least 50%, preferably at least 60% measured according to the ASTM D1003 standard and the Hoff transmission blur of at least 95%, preferably at least 88% measured by hazemeter HazeGard plus BYK, and / or
• the luminous reflection RL measured according to the ISO 9050: 2003 standard is strictly less than 30%, preferably less than 25% and better still less than 20% ,
• a variation of light reflection RL between the transparent state RL on and the translucent state RL 0 ff defined by (RL on -RL 0 ff) less than 15%, preferably less than 10% and better still less than 5%.
• the blur and transmission values (H and TL) in% are measured by hazemeter Hazegard plus BYK.
• the RL light reflection is measured according to the ISO 9050: 2003 standard (illuminant D65, 2 ° observer).
• the light transmission, light reflection and blur values given above in the transparent state, ie in the ON state, are preferably obtained for an applied voltage of 30 Vrms, preferably 20 Vrms. and better than 15 Vrms.
• a PDLC layer comprising liquid crystals can be obtained by preparing a precursor composition of the PDLC layer comprising a mixture of liquid crystals and a photopolymerizable composition, followed by crosslinking or polymerization of said composition.
• the photopolymerizable composition comprises monomers, oligomers and / or prepolymers and a polymerization initiator.
• This precursor composition of the PDLC layer is deposited on a support coated with an electrode in the form of a "layer".
• a second electrode carried by a support sandwiches said layer.
• a polymer matrix is formed in which the liquid crystals are incorporated as microdroplets.
• the PDLC layer is thus obtained by a phase separation step induced by radical photopolymerization.
• liquid crystals used according to the invention are preferably nematic at room temperature and with positive dielectric anisotropy.
• Examples of liquid crystals and liquid crystal mixtures suitable according to the invention are described in particular in patents EP 0 564 869 and EP 0 598 086.
• liquid crystal mixture that is particularly suitable according to the invention, it is possible to use the product marketed by Merck under the reference MDA-00-3506 comprising a mixture of 4 - ((4-ethyl-2,6- difluorophenyl) ethinyl) -4'-propylbiphenyl and 2-fluoro-4,4'-bis (trans-4-propylcyclohexyl) biphenyl.
• Nematic liquid crystals are birefringent materials.
• n m 2 1/3 (n e 2 + 2n 0 2 ).
• the polymer matrix also has a refractive index n p .
• the PDLC layer satisfies the following conditions:
• the difference between the ordinary and extraordinary refractive indices of the liquid crystals is between 0.2 and 0.3
• the liquid crystals or the mixture of liquid crystals and the polymer matrix respectively have an ordinary refractive index and a refractive index that are substantially equal, the difference between the ordinary refractive index of the liquid crystal mixture and the refractive index of the polymer matrix is less than 0.050, better still less than 0.010,
• the difference between the average refractive index of the liquid crystal mixture and the refractive index of the polymer matrix is greater than 0.100, better still greater than 0.125.
• Substantially equal refractive indices when the absolute value of the difference between the refractive indices at a wavelength of 550 nm is less than or equal to 0.050, preferably less than 0.015 and better still less than 0.010,
• the droplets of liquid crystals have, in order of increasing preference, a mean diameter of between 0.25 and 1.80 ⁇ , between 0.60 and 1, 30 ⁇ or between 0.70 and 1.00 ⁇ (limits included). .
• the proportions by weight of the liquid crystal mixture relative to the total mass of the liquid crystal and photopolymerizable composition mixture are advantageously between 50 and 65%.
• the photopolymerizable composition corresponds to the precursor composition of the polymer matrix of the PDLC layer.
• This composition comprises compounds capable of polymerizing or cross-linking by radical means under the action of radiation preferably UV.
• vinyl compounds or compounds comprising vinyl groups mention may be made of monomers, oligomers, prepolymers and polymers comprising acryloyl or methacryloyl, allyl or vinylbenzene groups. These compounds comprising vinyl groups may be monofunctional or multifunctional. Mention may be made in particular of monoacrylates, diacrylates, N-substituted acrylamides, N-vinylpyrrolidone, styrene and its derivatives, polyester acrylates, epoxy acrylates, polyurethane acrylates and polyether acrylates.
• various compounds comprising photocurable vinyl groups may be used.
• compounds comprising (meth) acrylate groups since they allow an excellent phase separation between the polymer matrix and the liquid crystals by irradiation with in particular a high rate of hardening and thus obtaining a stable and homogeneous product.
• Vinyl compounds that are suitable according to the present invention are for example described in patent EP 0272 585, in particular acrylate oligomers.
• the vinyl compounds are preferably acrylate compounds or methacrylate or (meth) acrylate compounds.
• (meth) acrylate is meant an acrylate or a methacrylate.
• the photopolymerizable composition according to the invention preferably comprises acrylate and / or methacrylate compounds (hereinafter (meth) acrylate).
• the (meth) acrylate compounds used according to the invention may be chosen from monofunctional and polyfunctional (meth) acrylates such as mono-, di-, tri-, polyfunctional (meth) acrylates. Examples of such monomers are:
• monofunctional (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, n- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, phenyloxyethyl (meth) acrylate, hydroxyethylacrylate, hydroxypropyl (meth) acrylate, vinyl (meth) acrylate caprolactone acrylate, isobornyl methacrylate, lauryl methacrylate, polypropylene glycol monomethacrylate,
• difunctional (meth) acrylates such as 1,4-butanediol di (meth) acrylate, ethylene dimethacrylate, 1,6-hexandiol di (meth) acrylate, bisphenol A di (meth) acrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, triethylene glycol diacrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate,
• trifunctional (meth) acrylates such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol triacrylate,
• the (meth) acrylate of higher functionality such as pentaerythritol tetra (meth) acrylate, ditrimethylpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate or hexa (meth) acrylate.
• the photopolymerizable composition comprises at least one monofunctional vinyl compound, preferably an acrylate monomer, at least one difunctional vinyl compound, preferably a diacrylate monomer, and at least one mono-, di- or polyfunctional vinyl oligomer, of preferably an acrylate oligomer.
• the photopolymerizable composition comprises in mass relative to the total mass of the photopolymerizable composition:
• the photopolymerizable composition comprises, by weight relative to the total weight of the photopolymerizable composition, in order of increasing preference, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of vinyl compounds.
• the polymer matrix once crosslinked will therefore comprise at least 50% of polymer obtained by polymerization of vinyl compounds.
• the polymer matrix comprises, in order of increasing preference, in mass relative to the total mass of the polymer matrix, at least 60%, at least 70%, at least 80%, at least 90%, at least 92% at least 95% of polymers obtained by polymerization of the vinyl compounds.
• the photopolymerizable composition comprising vinyl compounds comprises, by weight relative to the total mass of the photopolymerizable composition, in order of increasing preference, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of acrylate compounds and / or methacrylate compounds.
• the photopolymerizable composition may further comprise 0.01 to 5% of a photoinitiator by mass relative to the total weight of the photopolymerizable composition.
• Suitable photoinitiators according to the invention include 2,2-dimethoxy-1,2-diphenylethanone.
• the polymerizable composition may comprise other polymerizable comonomers.
• An example of a photopolymerizable composition is a composition obtained from the product MXM 035 sold by Nematel. This product includes:
• the PDLC layer may further comprise spacers.
• the spacers may be glass such as glass beads or hard plastics for example polymethyl methacrylate (PMMA) or divinylbenzene polymer. These spacers are preferably transparent and preferably have an optical index substantially equal to the refractive index of the polymer matrix.
• the spacers are of non-conductive material.
• the electrodes are each carried by a support preferably chosen from glass substrates.
• the supports are attached to each other at their edge by a seal.
• the electrode-carrying supports are fixed on the edge by a sealing joint.
• the seal is chosen from a material of the same nature as the polymer matrix forming the PDLC layer, that is to say based on a vinyl compound, preferably (meth) acrylate.
• the invention also relates to an electrically controllable glazing comprising a variable light diffusion system switching between a transparent state and a translucent state comprising a PDLC layer comprising liquid crystals forming microdroplets dispersed in a polymer matrix located between two electrodes each carried by a support.
• Said supports may be sheets of glass, preferably of mineral glass, maintained at their edges on the side of the electrodes by a sealing gasket, preferably based on crosslinked polymer.
• the invention relates to the use of a variable light scattering system switching between a transparent state and a translucent state as defined above, characterized in that a lower switching voltage is applied to 30 Vrms, preferably less than 20 Vrms and better still less than 15 Vrms.
• the PDLC layer is framed by two electrodes, the electrodes being in contact with the diffusing layer.
• the electrodes each comprise at least one electroconductive layer.
• the electroconductive layer may comprise transparent conductive oxides (TCO), that is, materials that are both good conductors and transparent in the visible, such as indium oxide doped with tin. (ITO), antimony or fluorine doped tin oxide (SnO 2 : F) or aluminum doped zinc oxide (ZnO: Al).
• TCO transparent conductive oxides
• ITO indium oxide doped with tin.
• SnO 2 antimony or fluorine doped tin oxide
• ZnO aluminum doped zinc oxide
• An electroconductive layer based on ITO has a surface resistance of 50 to 200 ohms per square.
• electroconductive layers based on oxides are preferably deposited on thicknesses of the order of 50 to 100 nm, directly on a substrate or on an intermediate layer, by a large number of known techniques such as cathodic sputtering assisted by Magnetic field, evaporation, sol-gel technique, as well as vapor deposition techniques (CVD).
• CVD vapor deposition techniques
• the electroconductive layer may also be a metal layer, preferably a thin layer or a stack of thin layers, called TCC (for "transparent conductive coating” in English) for example Ag, Al, Pd, Cu, Pd, Pt In, Mo, Au and typically of thickness between 2 and 50 nm.
• TCC transparent conductive coating
• the electrodes comprising an electrically conductive layer are connected to a power supply.
• the electrodes comprise for example a transparent electrically conductive layer with a thickness of about 20 to 400 nm made of indium tin oxide (ITO) for example.
• ITO layers have a surface electrical resistance of between 5 ⁇ / ⁇ and 300 ⁇ / ⁇ .
• the layers made of ITO it is also possible to use for the same purpose for the first and / or the second electrode other layers of electrically conductive oxide or silver stacks whose surface resistance is comparable.
• the electroconductive layers of the electrodes can then be deposited directly on a face of a substrate and thus form the electrode-carrying substrates.
• the substrates may be glass substrates, for example flat float glass sheets.
• the electrode support is a glass substrate, it may be chosen from among the glass substrates sold by Saint-Gobain Glass in the DIAMANT® or Planilux® range.
• the glass substrates preferably have a thickness of between 0.4 and 12 mm, preferably 0.7 and 6 mm.
• the invention also relates to an electrically controllable glazing comprising a variable light diffusion system according to the invention and two supports each carrying an electrode of the variable light scattering system.
• the electrically controllable liquid crystal glazing can be used everywhere, both in the construction sector and in the automotive sector, whenever the view through the glazing must be prevented at given times and in particular:
• the glazing according to the invention can form all or part of a partition and other window (transom type).
• the electrically controllable glazings comprising a variable light diffusion system according to the invention have low switching voltages while keeping good optical properties. The power consumption is then low enough to allow the use of a less bulky power supply.
• the electrically controllable glazing according to the invention can thus be integrated into "ready-to-use" devices. The installation of said glazings is simplified and costs are reduced.
• the invention therefore also relates to a device comprising a glazing unit as defined above, a frame and a power supply.
• the power supply is included in the frame.
• the power supply corresponds to the system which transfers the electric current of an electrical network to supply it, under the appropriate parameters (power, voltage), in a stable and constant manner to the variable light scattering system. Due to its small size, the power supply can be placed inside the frame, for example in an amount.
• the power supply is connected to a power cord comprising an electrical outlet that can be connected to the electrical network. The device is ready to use in that it can be easily installed and switched on with only the connection of the electrical outlet to the mains.
• Power supplies can be small enough to fit inside the frame and run on batteries rather than being connected to a power supply. Having battery power allows direct use after installation.
• the power supply is a battery powered.
• the device further comprises a compartment for receiving the batteries.
• the compartment is located on the frame and may for example include a flap openable and closable, accessible on the amount of the frame. The valve allows access to the battery compartment and change them when necessary.
• the integration of the power supply in the device makes it more robust for handling during installation as well as for transport.
• the device can easily be removed and replaced to examine the causes, regardless of whether the fault is due to power or electrically controllable glazing.
• the device may further comprise a switch mounted on the frame.
• the switch can be connected to the socket and the power supply.
• the power supply can be a push button or an infrared receiver that can be remotely controlled.
• Structures of large dimensions can be realized by putting side by side several devices.
• each device comprises an infrared receiver
• the same remote control can individually control these infrared receivers either by ordering them at once, or in a rhythmic program over time.
• the choice of frame is based on the use of glazing, as a glass door, window or partition for example.
• FIG. 4 illustrates a device according to the invention integrated in a glazed door or window element 6.
• the device comprises an electrically controllable glazing unit 1, a frame 2, a power supply 3, a switch 4 fixed on a frame post 2 and a power cord comprising a power outlet 5 located side to which the door or window opens.
• FIG. 5 illustrates a device according to the invention integrated in a glazed door or window element 6.
• the device comprises an electrically controllable glazing unit 1, a frame 2, a power supply 3, a switch 4 fixed on a frame upright 2 and a compartment to hold the batteries 7.
• the transparent substrates used are Planilux® glasses marketed by Saint-Gobain.
• the electrodes consist of a layer of ITO (tin doped indium oxide) with a surface resistance of about 50 to 200 ohms per square.
• liquid crystal mixture used corresponds to the product marketed by Merck under the reference MDA-00-3506 comprising:
• This liquid crystal mixture has the following properties:
• the photopolymerizable composition is obtained from the product MXM 035 sold by Nematel.
• This two-part product A and B includes:
• the polymer matrix resulting from the crosslinking of such a photopolymerizable composition has a refractive index of 1.482 (without liquid crystal droplets).
• the spacers are beads marketed under the name Sekisui Micropearl of 15 ⁇ average diameter.
• the seal is composed of a photo-crosslinkable acrylate glue.
• the photopolymerizable composition is prepared from product MXM35 by mixing 13.5% by weight of Part A with 86.5% by weight of Part B relative to the total weight of Parts A and B,
• Sekisui micropearl spacers are added relative to the total mass of the liquid crystal mixture and photopolymerizable composition.
• a layer of ITO is deposited by magnetron process on Planilux® glass.
• the acrylate adhesive used as a seal is applied at the edge of the support
• the precursor composition of the PDLC layer is deposited on an electrode carried by a support
• a second support coated with an electrode is deposited on the first with the two conductive layers facing each other separated by the precursor composition layer of the PDLC layer,
• the insolation conditions ie the insolation power and the duration of the UV exposure, are varied.
• FIG. 1 shows the three images A, B and C taken under the scanning electron microscope of the SDLV1, SDLV2 and SDLV3 variable light scattering systems.
• Figures 2 and 3 are graphs showing the evolution of the blur (in%) for the variable light scattering systems SDLV1, SDLV2 and SDLV3 as a function of the applied voltage (in Vrms).
• the optimal variable light scattering system is SDLV1 with spherical droplets and a switching voltage of 15 Vrms.
• SDLV3 has smaller droplet sizes which results in some increase in switching voltage. This may be due to the increase in the interface area / volume ratio.
• Electrically controllable glazing comprising a variable luminous diffusion system of SDLV1 type laminated with 4 mm glass weighs 35 kg / m 2 .
• the electrical consumption per m 2 of glazing at 30 Vrms is 1 W / m 2 .
• the power consumption per m 2 of glazing at 12 Vrms is 0.16 W / m 2 .
• a glazing of square form of dimensions 20x20 cm 2 below glazing pane has the following characteristics: - weight 1, 4 kg,
• a device comprising a battery power supply and an active glazing tile of 1 m 2 has an autonomy of 3 days.

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• 2012
  • 2012-10-31 FR FR1260427A patent/FR2997517B1/fr not_active Expired - Fee Related
• 2013
  • 2013-07-19 DE DE201320006516 patent/DE202013006516U1/de not_active Expired - Lifetime
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