KR20150081274A - Variable light diffusion system comprising a pdlc layer - Google Patents

Abstract

The present invention relates to a variable light-scattering system comprising a PDLC layer positioned between two electrodes and being switched between a transparent state and a translucent state. The PDLC layer comprises a mixture of liquid crystals forming microcapsules dispersed in a polymer matrix obtained from a photopolymerizable composition comprising a vinyl compound. The invention also relates to the use of a variable light-scattering system which is switched between a transparent state and a semitransparent state and which operates at a switching voltage of less than 30 Vrms.

Description

[0001] The present invention relates to a variable light scattering system including a PDLC layer,

The present invention relates to the field of a variable light-scattering system comprising an electrically adjustable glazing with variable optical properties, more particularly a PDLC layer positioned between two electrodes supported by a support.

Glazing is known that has certain characteristics that can be changed by an appropriate power supply effect, specifically, electromagnetic waves of a specific wavelength, particularly transmission, absorption or reflection within a visible light or infrared wavelength range, or light scattering characteristics.

Currently available glazing, which can be switched between a transparent state and a scattering state, includes a functional film consisting of two electrode-supporting supports in the form of a plastic sheet flanking a layer comprising a liquid crystal droplet, The assembly is laminated or adhesively bonded by a middle layer between a glass substrate or two glass substrates. When the film is powered (in the "on" state), the liquid crystal is oriented along the preferred axis, thereby providing visibility through the functional film. When power is turned off (in the "off" state), the liquid droplet interior is not aligned and the film becomes scattering and blocks visibility.

Applicants have developed a novel switchable glazing comprising a liquid crystal, which does not use the technology of functional films. This switchable glazing includes a layer comprising a plurality of liquid crystal droplets (hereinafter referred to as a PDLC (polymer-dispersed liquid crystal) layer) dispersed without preferential orientation in the polymer matrix. The PDLC layer is directly encapsulated between two glass substrates. The assemblies formed by the substrates and the PDLC layer are sealed by edge adhesive beads or sealing gaskets. Patent applications WO 2012/028823 and WO 2012/045973 describe such glazing. By using such a technique, the materials used can be made more economical, and glazing can be manufactured which is less expensive, and has better performance in terms of electro-optics.

Switchable glazing, including layers based on liquid crystals embedded in a functional film or directly encapsulated between two glass substrates, has a minor drawback that requires high operating voltages. The operating voltage effective value of the sinusoidal form typically exceeds 50 Vrms (rms: square root mean square). In fact, in addition to the advantages associated with reducing power consumption and / or limiting power cut-off (reducing the risk of shorting), using such a system for lower safety requirements, It is possible.

According to the present invention,

The switching voltage is a sinusoidal effective voltage starting from a value at which a haze value of less than 5% is obtained when measured according to ASTM D 1003 standard,

- The operating voltage is the effective voltage in the sinusoidal form recommended to obtain a clear state without obtaining the haze value specified by the functional film supplier.

Thus, the switching voltage corresponds to the minimum operating voltage to achieve low haze. The haze corresponds to the amount of transmitted light scattered at an angle exceeding 2.5 degrees. The liquid crystal is better aligned when the applied voltage is high (thus, a lower haze appears). When the applied voltage is insufficient, the PDLC layer may remain in a scattering state to produce a white bloom. These white blooms are the main reason why transparency is not felt.

Thus, lowering the switching voltage is advantageous in terms of optical characteristics and performance of the variable light-scattering system, particularly in the absence of haze in the transparent state, good light transmittance in the transparent state, appropriate transmittance in the scattering state, and good shielding performance independent of the viewing angle in the scattering state. You should not get up. The ability to shield glazing in a scattering state is a performance that does not allow visibility through it.

Consequently, in order to improve the optical characteristics of the variable light-scattering system while lowering the switching voltage, the Applicant has paid attention to a mechanism for controlling such complex systems.

The scattering system, which includes scattering agents dispersed in the matrix, diffuses light differently depending on the size and density of the scattering agents they contain. The variable light-scattering system of the present invention corresponds to a scattering layer including a liquid crystal droplet dispersed in a certain volume as a scattering agent in a scattering state. These scatterers must have a size and density that causes light passing through the medium formed by the scattering layer to cause Mie scattering. To observe this phenomenon, the size of the scattering agent is larger than the visible range wavelength, typically 1 or several micrometers.

The spatial distribution of transmitted and scattered light when it is normally incident on this type of scattering layer is not isotropic and varies considerably depending on the form of scattering agent (spheres, cylinders, plates, etc.), size and density.

For a given scattering layer, the indicatrix of scattering during transmission can be determined. This is done by vertically illuminating the scattered layer with light and measuring the intensity of the scattered light as a function of angle to the initial irradiating direction during transmission. This scattering indikatrix can be measured using a device that measures the BTF or BTF, such as the REFLET bench (manufacturer STIL). These indications are obtained by measuring the transmitted light on the arc from -90 ° to 90 ° of the semicircle opposite to the incident light, forming a peak-shaped curve. The information that can be extracted from such a scattering indicatrix comes from the height of the peak top and the shape and width of the peak bottom. The top of the peak centered at 0 ° corresponds to the normal incidence angle, where the light is not scattered.

A distinction must be made between the scattering layers which represent the scattering explained by the non-scattering. Depending on the size and density of the scattering agent, and also the thickness of the PDLC layer, the scattering indicators have a variable shape.

When the scattering layer comprises a larger or less dense scattering agent, the scattering indicatrix has a similar shape to the quasi-triangular peak. The half-width of the base of the triangle corresponds to the critical angle (absolute value) at which scattering does not occur in excess of the half-width. At this time, the scattering indications at the time of transmission are considered very forward-pointing.

In contrast, if the scattering layer contains smaller particles, the scattering indicatrix can be split into two major portions. A superimposed peak is obtained on a curve called a bell-shaped "baseline ". In this case, the light beam can be scattered at a wide angle. In this case, scattering indications in transmission are considered to be less forward-pointing.

Analysis of Scattering Indicatrix at Transmission can prove that if the scattered layer includes particles of a size and density that are forward-pointing and the scattering profile includes particles of a density, substantially no light is scattered at an angle exceeding the threshold. In this case, the average angular deviation with respect to the initial direction of the light ray passing through the scattering layer is small, so that the shielding ability is low. In contrast, if the scattering layer has a scattering profile that is not very forward-pointing, a better shielding capability will be obtained since the average angular deviation with respect to its initial direction of the rays passing through the scattering layer is greater.

It is necessary to optimize the size and density of the liquid crystal droplet and the thickness of the scattering layer in order to obtain a good shielding ability in the scattering state.

In the case of a variable light-scattering system, obtaining a satisfactory transparent state with a low operating voltage should not occur while compromising the improvement in shielding ability in the scattering state. However, since the variable line light-scattering system including the PDLC layer is a complex system, each characteristic may affect the decrease or increase of the switching voltage. Some characteristics that affect shielding ability and switching voltage are common. Among the characteristics that affect the switching voltage are:

- Size, density and shape of liquid crystal droplets,

The quality of the liquid droplet droplets and the polymer matrix, in particular the quality when one is not present in the other,

- the presence of residual impurities, such as ionic species, resulting from the process of manufacturing the PDLC layer,

- the thickness of the PDLC layer,

- Properties of liquid crystals.

Among these properties, some depend on the method of manufacturing the PDLC layer, the choice of starting materials or both.

The method of making the PDLC layer comprises a phase separation step for forming liquid crystal droplets dispersed in the polymer matrix. Particularly in terms of their size, shape, purity and optionally interconnection structure (open or closed voids), in particular the nature, concentration, temperature and operating conditions of the components in the PDLC layer precursor composition, .

As a result, lowering the operating voltage of the variable light-scattering system including the PDLC layer depends on the starting component of the PDLC layer as well as its manufacturing method. It is impossible to simply associate the parameters and / or characteristics of the PDLC layer fabrication method with the reduction of the switching voltage and the improvement of the shielding ability.

Therefore, there is a need to develop a novel variable optical-scattering system with improved optical properties, particularly good viewing angle-independent, and better quality when viewed in the transparent state, with lower cost and lower switching voltage.

The present invention therefore relates to a variable light-scattering system comprising a PDLC layer positioned between two electrodes and being switched between a transparent state and a translucent state, said PDLC layer being capable of forming microcapsules dispersed in a polymer matrix A liquid crystal mixture comprising:

The polymer matrix is obtained from a photopolymerizable composition comprising a vinyl compound,

The weight ratio of the liquid crystal mixture to the total weight of the liquid crystal mixture and the photopolymerizable composition is from 40% to 70%

The thickness of the PDLC layer is between 5 and 25 μm,

The mean diameter of the liquid crystal droplets dispersed in the polymer matrix is from 0.25 to 2.00

.

Surprisingly, the variable light-scattering system of the present invention in combination with the claimed features makes it possible to obtain the desired properties, and in particular to achieve excellent transparency at low effective voltage applied, in particular less than 30 Vrms, less than 20 Vrms or less than 15 Vrms And good shielding ability in a scattering state. Such advantageous properties are obtained especially for PDLC layers with a thickness of about 15 [mu] m. The thickness of the PDLC layer is preferably 10 to 20 占 퐉, more preferably 12 to 17 占 퐉.

The present invention also relates to the use of such a system operating at a switching voltage of less than 30 Vrms.

Starting from a radical photopolymerizable composition, the choice of the PDLC layer obtained by polymerization-induced derivatization reduces ion contamination in the final product, thus limiting the screening of the electric field in liquid crystal droplets. When ionic impurities are present in the PDLC layer, it is necessary to apply a higher voltage to switch to a transparent state because these impurities tend to reduce the electric field in each liquid crystal droplet. Radical polymerization does not require ionic species as the starting compound. This type of polymerization also does not produce ionic species. As a result, in the case of radical polymerization, ionic species are dissolved in liquid crystals and can not participate in the screening of the electric field.

The density of the droplets in the PDLC layer can be indirectly evaluated by the average size of the droplet (assuming that the liquid crystal is hardly dissolved in the polymer matrix) and the relative weight ratio of the liquid crystal mixture to the photopolymerizable composition. The average size and size of the droplets and the homogeneity in the distribution within the PDLC layer vary considerably with polymerization conditions.

The ratio between droplet size, density, porosity type (closed, open or semi-open) and switching voltage of the PDLC layer is complex.

The switching voltage for spherical droplets of closed pores is expected to decrease as the droplet size increases.

However, the increase in droplet size offset the gain in good shielding ability in the scattering state.

Increasing the droplet density improves the shielding ability. However, the increase in droplet density also increases the risk of interconnection (open or semi-open gap) between the droplets. Experiments show that open pores cause an increase in switching voltage. This is explained by the fact that in the case of closed pores, the ratio of the polymer matrix / liquid crystal mixture-based area to the volume of the PDLC layer is significantly lower than in the case of open pores. However, the liquid crystal located at the interface in particular is somewhat "blocked" by the polymer matrix, making switching less easy.

By selecting the specific form for the PDLC layer to be used in accordance with the present invention through the choice of the size of the liquid crystal droplet and the ratio between the liquid crystal mixture and the photopolymerizable composition, it contributes to lowering the switching voltage and improving the optical properties. The form of the PDLC layer used in accordance with the present invention can be defined by the individualization of the liquid crystal droplets or the excellent property of not sticking to each other. These liquid crystal droplets have essentially closed pores and contain a smaller proportion of liquid crystals that can be blocked at the interface of the liquid crystal mixture and the polymer matrix. By choosing this particular form, the switching voltage can be lowered without compromising the optical properties such as good shielding capability.

By selecting a particular vinyl compound among the various compounds that may be considered as constituent monomers, oligomers or prepolymers of the polymer matrix, excellent phase separation can be obtained for the desired liquid crystal droplet density during crosslinking. As a result, a PDLC layer having a uniform droplet size and a high density can be obtained, especially at a small size of about micrometers. The liquid crystal is well distributed in the droplets and is not dispersed and dispersed in the polymer matrix.

Thus, liquid crystals diluted in the polymer matrix are scarcely found, and almost no monomers or prepolymers are found in the liquid crystal droplets. Thus, the dielectric anisotropy of the liquid crystal can be reduced, and as a result, the presence of the residual monomer or prepolymer in the liquid crystal droplet, in which a higher voltage is required to align the liquid crystal, is prevented. By being dissolved in the polymer matrix without belonging to a droplet, the presence of a liquid crystal that can not be switched when connected to a power source is also prevented.

By selecting a combination of the method of preparing the PDLC layer including the radical polymerization, the specific ratio and properties of the starting compound, and the polymerization conditions, it is possible to obtain an optimum thickness, a droplet density And a PDLC layer having the shape.

The variable light-scattering system of the present invention advantageously has a light transmission rate with little change between the transparent state and the scattering state. Preferably, the variable light-scattering system

The change in the light transmittance between the transparent state TL _on and the translucent state TL _off , defined as - (TL _on - TL _off ) is less than 35%, preferably less than 30%, more preferably less than 25%

The change in haze between the transparent state H _on and the translucent state H _off , defined as - (H _off - H _on ) is greater than 90%, preferably greater than 95%, more preferably greater than 97%

In the transparent state, the transmittance TL _on measured according to the ASTM D1003 standard is not less than 75%, preferably not less than 80%, and the haze H _on when projected according to the ASTM D1003 standard is not more than 5%, preferably not more than 3% And /

In the scattering state, the transmittance TL _off measured according to the ASTM D1003 standard is 50% or more, preferably 60% or more, and the haze _off (off) measured by the haze guard plus hazemeter of BYK Is at least 95%, preferably at least 88% and /

- the light reflectance RL measured in accordance with ISO 9050: 2003 standard (Investigator D65, 2 ° observer) in the scattering and transparent states is strictly less than 30%, preferably less than 25%, more preferably less than 20%

- change in the light reflection RL of between - (RL _on RL _off), the transparent state (RL _on) and a semi-transparent state (RL _off) is defined as less than 15%, preferably less than 10%, more preferably from 5% .

The haze and the transmittance (H and TL) expressed in% are measured by the haze-guard plus haze meter from BYK. The light reflectance RL is measured according to the ISO 9050: 2003 standard (light source D65, 2 ° observer). The transparent state, that is, the transmittance, the light reflectance and the haze value in the switch "on" state are preferably obtained for an applied voltage of 30 Vrms, preferably 20 Vrms, more preferably 15 Vrms.

In the scattering state, most of the incident light is transmitted in a scattering manner, with only a small portion reflected or backscattered by the liquid crystal droplet.

A PDLC layer comprising a liquid crystal can be obtained by preparing a precursor composition of a PDLC layer comprising a liquid crystal mixture and a photopolymerizable composition, and then cross-linking or polymerizing the composition. The photopolymerizable composition includes a monomer, an oligomer and / or a prepolymer, and a polymerization initiator. Such a PDLC layer precursor composition is deposited on a support wherein the electrode is coated in the "layer" form. A second electrode supported by the support sandwiches the PDLC layer. During the curing by irradiation with UV light, a polymer matrix is formed in which the liquid crystal is contained in an uncleaved form. Thus, the PDLC layer is obtained by a phase separation step induced by radical photopolymerization.

The liquid crystal used according to the present invention is preferably nematic at ambient temperature and has a positive dielectric anisotropy. Examples of suitable liquid crystals and liquid crystal mixtures according to the invention are described in particular in patent EP 0 564 869 and EP 0 598 086.

A product which is commercially available from Merck as MDA-00-3506, which can be used as a very particularly suitable liquid crystal mixture in accordance with the present invention is 4 - ((4-ethyl-2,6-difluorophenyl) (Ethynyl) -4'-propylbiphenyl and 2-fluoro-4,4'-bis (trans-4-propylcyclohexyl) biphenyl.

Nematic liquid crystals are birefringent materials. The birefringence Δn of the liquid crystal or liquid crystal mixture corresponds to the difference between the two principal indices of the material, ie normal refractive index n _o and extra refractive index n _e (Δn = n _e - n _o ).

The liquid crystal is irregularly oriented in the droplet. Therefore, in the absence of an applied electric field, the average refractive index of the liquid crystal droplet defined by the formula n _m ² = 1/3 (n _e ² + 2n _o ² ) can be calculated.

The polymer matrix also has a refractive index n _p .

Preferably, the PDLC layer satisfies the following conditions:

The difference between the normal refractive index and the extraordinary refractive index of the liquid crystal is 0.2 to 0.3.

The liquid crystal or liquid crystal mixture, and the polymer matrix each have a normal refractive index and a substantially the same refractive index.

The difference between the normal refractive index of the liquid crystal mixture and the refractive index of the polymer matrix is less than 0.050, more preferably 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, more preferably greater than 0.125.

In accordance with the present invention, the terms have the following meanings:

"Substantially the same refractive index" refers to the case where the absolute value of the difference between the refractive indices at a wavelength of 550 nm is less than 0.050, preferably less than 0.015, more preferably less than 0.010.

"Different refractive indexes" refers to cases where the absolute value of the difference between the refractive indices at a wavelength of 550 nm is strictly greater than 0.050, preferably greater than 0.100, more preferably greater than 0.125.

The average diameter of the liquid crystal droplets is preferably 0.25 to 1.80 μm, more preferably 0.60 to 1.30 μm, and still more preferably 0.70 to 1.00 μm (including the limit value).

The weight ratio of the liquid crystal mixture to the total weight of the liquid crystal mixture and the photopolymerizable composition is advantageously between 50% and 65%.

The photopolymerizable composition corresponds to a precursor composition of the polymer matrix of the PDLC layer. The composition includes a compound that can be polymerized or crosslinked through a radical pathway by the action of light, preferably UV radiation.

The term "vinyl compound" as used herein means a monomer, oligomer, prepolymer or polymer containing at least one (CH ₂ ═CR) -vinyl functional group, and the vinyl functional group is a polymer network provided in a solid structure . According to the invention, the vinyl compound comprises acrylic and methacrylic compounds comprising at least one (CH ₂ ═CH-CO-O-) or (CH ₂ ═C (CH ₃ ) -CO-O-) functional group .

Thus, what may be referred to as compounds containing vinyl or vinyl groups are monomers, oligomers, prepolymers and polymers comprising acryloyl or methacryloyl, allyl or vinylbenzene groups. These compounds, including vinyl groups, may be monofunctional or multifunctional. Particular mention may be made of monoacrylates, diacrylates, N-substituted acrylamides, N-vinylpyrrolidone, styrene and derivatives thereof, polyester acrylates, epoxy acrylates, polyurethane acrylates and polyether acrylates Rate.

According to the present invention, various compounds including a photocurable vinyl group may be used. However, it is preferable to use a compound containing a (meth) acrylate group, whereby a stable and homogeneous product is produced by obtaining excellent phase separation through light irradiation between the polymer matrix and the liquid crystal at a particularly rapid curing rate to be.

Suitable vinyl compounds according to the invention are described, for example, in patent EP 0272 585, in particular acrylate oligomers. The vinyl compound is preferably an acrylate compound or a methacrylate or (meth) acrylate compound. "(Meth) acrylate" means acrylate or methacrylate.

The photopolymerizable composition according to the present invention preferably comprises an acrylate and / or methacrylate (hereinafter, (meth) acrylate) compound. The (meth) acrylate compounds used in accordance with the present invention may be selected from monofunctional and multifunctional (meth) acrylates such as monofunctional, bifunctional, trifunctional or multifunctional (meth) acrylates. Examples of such monomers include:

- monofunctional (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, n- or tertiary butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (Meth) acrylate, hydroxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, vinyl (meth) acrylate, caprolactone acrylate, isobornyl methacrylate, lauryl methacrylate, polypropylene glycol monomethacrylate,

(Meth) acrylate such as 1,4-butanediol di (meth) acrylate, ethylene dimethacrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A di 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 Tri-propylene glycol triacrylate, and

(Meth) acrylates such as pentaerythritol tetra (meth) acrylate, ditrimethylpropanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate or hexa Acrylate

to be.

Preferably, the photopolymerizable composition comprises at least one monofunctional vinyl compound, preferably an acrylate monomer, at least one bifunctional vinyl compound, preferably a diacrylate monomer, at least one monofunctional, bifunctional or multifunctional Vinyl oligomers, preferably acrylate oligomers.

The photopolymerizable composition is a weight ratio of the photopolymerizable composition to the total weight,

- 30% to 95%, preferably 35% to 60%, more preferably 40% to 55% of the monovalent vinyl compound,

- 1% to 35%, preferably 10% to 25%, more preferably 5% to 25% of a bifunctional vinyl compound,

- 1% to 50%, preferably 20% to 40%, more preferably 25% to 35% of a monofunctional, difunctional or multifunctional vinyl oligomer and

- from 0 to 15%, preferably from 5% to 10% of at least one mercaptan compound

.

According to one embodiment, the photopolymerizable composition is present in a weight ratio relative to the total weight of the photopolymerizable composition in the order of 50%, 60%, 70%, 80%, 90% 95% or more vinyl compounds.

If no solvent is used, once the polymer matrix is crosslinked, it will contain at least 50% of the polymer obtained by polymerization of the vinyl compound. Preferably, the polymer matrix is present in the polymer matrix in a weight ratio relative to the total weight of the polymer matrix, in a more preferred order, greater than 60%, greater than 70%, greater than 80%, greater than 90%, greater than 92%, or greater than 95% ≪ / RTI >

According to one advantageous embodiment, the photopolymerizable composition comprising the vinyl compound is present in a proportion by weight relative to the total weight of the photopolymerizable composition in an order of greater than 50%, greater than 60%, greater than 70%, greater than 80% , 90% or more, or 95% or more of an acrylate compound and / or a methacrylate compound.

The photopolymerizable composition may also comprise from 0.01% to 5% by weight of the photoinitiator, based on the total weight of the photopolymerizable composition. Mention may be made, as appropriate photoinitiators according to the invention, of 2,2-dimethoxy-1,2-diphenylethanone.

The photopolymerizable composition may comprise other photopolymerizable co-monomers.

As an example of a photopolymerizable composition, mention may be made of the product MXM 035, marketed by Nematel. This product is:

A mixture of two acrylate monomers ethylhexyl acrylate and hexanediol diacrylate, and acrylate oligomer,

- mercaptans,

- photoinitiator for UV polymerization

.

Other examples of compositions based on acrylates and mercaptans are described in patents US 4,891,152, EP 0 564 869 and EP 0 598 086.

The PDLC layer may also include spacers. The spacer may be made of a glass such as glass beads or a hard plastic such as polymethylmethacrylate (PMMA) or a divinylbenzene polymer. These spacers are preferably transparent and preferably have an optical index that is substantially the same as the refractive index of the polymer matrix. The spacers are made of a non-conductive material.

The electrodes are each preferably supported by a support selected from a glass substrate. The supports are attached to each other by a sealing gasket at the edges.

The electrode-support support is attached to the edge by a sealing gasket. Preferably, the sealing gasket is selected from a material having the same properties as the polymer matrix forming the PDLC layer, i.e., a material based on a vinyl compound, preferably a (meth) acrylate compound.

Another subject of the present invention is an electrically adjustable glazing comprising a liquid crystal which is switched between a transparent state and a translucent state and forms a microcapsule dispersed in a polymer matrix located between two electrodes supported by a support Scattering system comprising a PDLC layer, wherein the support is a sheet of glass, preferably inorganic glass, of a sealing gasket, preferably a crosslinkable polymer, on the edge on the side of the electrode, As shown in Fig.

Finally, the present invention relates to the use of a variable light-scattering system that is switched to a transparent state and a translucent state as defined above, and is characterized by switching less than 30 Vrms, preferably less than 20 Vrms, more preferably less than 15 Vrms And a voltage is applied.

The PDLC layer is flattened by two electrodes in contact with the scattering layer. Each electrode comprises at least one electro-conductive layer. The electro-conductive layer may be a transparent conductive oxide (TCO), that is, a transparent conductive oxide, such as tin-doped indium oxide (ITO), antimony-doped or fluorine-doped tin oxide an Al): a doped zinc oxide (ZnO - F) or aluminum: SnO _2. The surface resistance of the electro-conductive layer based on ITO is 50 to 200 ohm / sq.

These oxide-based electro-conductive layers can be formed on the substrate directly or on the intermediate layer, preferably in a thickness of about 50 to 100 nm, by various known techniques such as magnetron sputtering, evaporation, sol- (CVD).

The electro-conductive layer may be a metallic layer, preferably a thin layer or a thin layer stack, referred to as a TCC (transparent conductive coating), for example, Ag, Al, Pd, Cu, Pd, PtIn, Mo, Typically the thickness is from 2 to 50 nm.

An electrode comprising an electro-conductive layer is connected to a power source.

The electrode is, for example, about 20 to 400 nm thick and includes a transparent electro-conductive layer made of, for example, indium tin oxide (ITO). The ITO layer has a surface electrical resistance of 5 to 300 ohm / sq. Instead of a layer made of ITO, other electro-conductive oxide layers or stacks containing silver, for example with similar surface resistance, may be used for the same purpose as the first and / or second electrode.

The electro-conductive layer of the electrode is then deposited directly on one side of the substrate to form an electrode-supporting substrate. The substrate may be a glass substrate, for example, a flat float glass sheet. When the electrode support is a glass substrate, lay may be selected from Diamants (DIAMANT) ^® or flash you lux (Planilux) ^® series of gobaeng glass (Saint-Gobain Glass). The thickness of the glass substrate is preferably 0.4 to 12 mm, preferably 0.7 to 6 mm.

The present invention also relates to a variable light-scattering system according to the present invention and to an electrically adjustable glazing comprising two supports each supported by an electrode of a variable light-scattering system.

Electrically adjustable liquid crystal glazing can be used in any application where the visibility through glazing is to be blocked for a given period of time in the construction and automotive sectors,

- buildings (in between two rooms or in one space), internal partitions of land, air or sea vehicles (between two sections or in cabs)

- glazed doors, windows, ceilings or tiling (floors, ceilings),

- side windows or roofs of land, air or sea vehicles,

- Projection screen,

- Shop windows or showcases, especially counters

Lt; / RTI >

The glazing according to the present invention may form all or part of a partition and other windows (skylight types).

The installation of the electrically adjustable glazing is generally carried out,

- Glazing is installed in the frame,

- installing a special power source for glazing

need.

This installation is typically carried out separately in each field, i.e., by a glazing installer and an electrician.

Electrically adjustable glazing comprising a variable light-scattering system according to the present invention has a low rectification voltage while maintaining good optical properties. Electricity consumption is low enough to use a smaller power source. Thus, the electrically adjustable glazing according to the present invention can be incorporated into an "immediate use" device. The installation of the glazing is simplified, and the cost is reduced.

Thus, the invention also relates to an apparatus comprising a glazing, a frame and a power source as defined above. Power is included in the frame.

The power supply corresponds to a system for delivering current from a power supply network for supplying it to a variable light-scattering system in a stable and constant manner under appropriate parameters (power, voltage). Due to the reduced size, the power source may be placed inside the frame, for example, in a jamb.

As a first variant, the power supply is connected to a power supply lead comprising an electrical plug which can be plugged into the power supply network. The device is an instant-on device in that it can be easily installed and only the switch can be turned on by plugging the electrical plug into the mains.

The power source may be sufficiently small to be able to be operated by the battery rather than being connected to the main power source installed inside the frame. It has battery power so it can be used immediately after installation.

According to a second variant, the power source is battery power. The device also has a zone for receiving the battery. Such a zone may be located on the frame and may comprise, for example, an openable flap that may be mounted on the jam of the frame. The flap allows access to the battery compartment to replace the battery if necessary.

Since the power is already included in the unit, there is no need to call an electrician during installation. Advantageously, by integrating power within the device, it is easier to handle during installation and transportation. Ultimately, in the event of a failure, the device can easily be removed and replaced to determine its cause, whether due to power supply or electrically adjustable glazing.

The apparatus may also include a switch mounted on the frame. The switch can be connected to a plug and a power source. The switch may be a push button type or an infrared receiver which may be operated by a remote control.

Large structures can be produced by arranging several devices side by side. If each device includes an infrared receiver, a single remote control can be individually adjusted by adjusting these infrared receivers at once or over time according to a rhythmic program.

The choice of frame depends, for example, on the use of glazing as a glazed door, window or partition.

Figure 4 shows a device according to the invention integrated into a part 6 of glazed door or window type. The device comprises an electrically adjustable glazing 1, a frame 2, a power supply 3, a switch 4 fixed to the jam of the frame 2 and a main plug 5 facing the door or window opening side, And a power cord.

Figure 5 shows a device according to the invention integrated into a part 6 of glazed door or window type. The apparatus comprises an electrically adjustable glazing 1, a frame 2, a power supply 3, a switch 4 fixed to the jam of the frame 2, and a zone 7 for receiving the battery.

<Examples>

I. Materials Used

A transparent substrate is used lay was flash you lux ^® glass commercially available from gobaeng.

The thickness of these substrates was 3.85 mm. The electrode consisted of an ITO (tin-doped indium oxide) layer having a surface resistance of about 50 to 200 ohm / sq.

The liquid crystal mixture used is a product sold under the number MDA-00-3506 from Merck,

-4 - ((4-ethyl-2,6-difluorophenyl) ethynyl) -4'-propylbiphenyl, and

- 2-fluoro-4,4'-bis (trans-4-propylcyclohexyl) biphenyl

.

Such a liquid crystal mixture had the following characteristics:

- normal refractive index: 1.5164,

- extraordinary refractive index: 1.7738,

- Tuna crossing rate: 0.2574.

The photopolymerizable composition was the product MXM 035 from the manufacturer Nematel. This product has two Parts A and B,

A mixture of ethylhexyl acrylate and hexanediol diacrylate, and acrylate oligomer (part B), two acrylate monomers,

- mercaptans (Part A),

- Photoinitiator for UV polymerization (Part A)

.

The polymer matrix resulting from the crosslinking of such photopolymerizable compositions had a refractive index of 1.482 (without liquid crystal droplets).

The spacer was a bead called Sekisui Micropearl, which has an average diameter of 15 [mu] m.

The sealing gasket was made of a photocurable acrylate adhesive.

II. Fabrication of Variable Light-scattering System

Preparation of the precursor composition of the PDLC layer :

The photopolymerizable composition was prepared from the product MXM35 by mixing 13.5% by weight of Part A and 86.5% by weight of Part B relative to the total weight of Parts A and B,

47.5% by weight of the photopolymerizable composition and 52.5% by weight of the liquid crystal mixture MDA 00-3506 are mixed with respect to the total weight of the liquid crystal mixture and the photopolymerizable composition,

- 0.3% by weight of Sekisui micro-pellet spacer based on the total weight of the liquid crystal mixture and the photopolymerizable composition was added.

Preparation of the support coated with the electrode: you flash the ITO layer was deposited on a magnetron process lux ^® glass.

Fabrication of Variable Optical-Scattering System :

- an acrylate adhesive used as a sealing gasket is applied to the edge of the support,

Depositing a precursor composition of the PDLC layer on an electrode supported by a support,

A second support coated with an electrode is deposited on the first support such that two conductive layers facing each other are separated by a layer of the precursor composition of the PDLC layer,

- squeeze two sheets of glass,

The assembly was exposed to UV light.

Further details on encapsulating the precursor layer between the electrode-supporting glass substrate can be found in patent applications WO 2012/028823 and WO 2012/045973 which describe these fabrication processes in detail.

III. Characterization of Variable Light-scattering System

* In the switched on state, the measurement was performed at an applied effective voltage of 30 Vrms.

In order to vary the average size of the droplets and the density of the droplets, the exposure conditions, i.e., UV exposure and UV exposure time, were varied.

Figure 1 shows three images A, B and C taken with a scanning electron microscope of the variable light-scattering systems SDLV1, SDLV2 and SDLV3.

Figures 2 and 3 show the change in haze (%) as a function of applied effective voltage (Vrms) for the variable light-scattering systems SDLV1, SDLV2 and SDLV3.

The optimal variable light-scattering system is SDLV1 with a spherical droplet and a switching voltage of 15 Vrms. SDLV3 had droplets of smaller dimensions and showed some increase in switching voltage. This may be due to an increase in the system area / volume ratio.

IV. Ready-to-use device

Variable light of the laminated type SDLV1 on 4 mm glass-weight of the electrically controllable glazing comprising a scattering system was 35 kg / m ^2. Electrical consumption per glazing m ² was 1 W / m ² at 30 V rms. The electrical consumption per glazing m ² was 0.16 W / m ² at 12 V rms. A square glazing of 20 x 20 cm ² , hereinafter referred to as glazing plate glass, had the following characteristics:

- Weight 1.4 kg,

- Electric consumption: 6.4 mW, ie a current of 0.53 mA.

As a result, the device containing glazing plate glass powered by AA battery power (1A capacity) at 12 Vrms to 0.53 mA was 78 days (24 h / 24 h; 1000 mAh / 0.53 mA = 1875 h) Of the battery life.

Under the same conditions, the battery life of the device including battery power and 1 m ² of active glazing plate was 3 days.

Claims (24)

A variable light-scattering system comprising a PDLC layer positioned between two electrodes and being switched between a transparent state and a translucent state,
The PDLC layer comprises a liquid crystal mixture that forms a microcapsule dispersed in a polymer matrix,
The polymer matrix is obtained from a photopolymerizable composition comprising a vinyl compound,
The weight ratio of the liquid crystal mixture to the total weight of the liquid crystal mixture and the photopolymerizable composition is from 40% to 70%
The thickness of the PDLC layer is between 5 and 25 μm,
The mean diameter of the liquid crystal droplets dispersed in the polymer matrix is from 0.25 to 2.00
/ RTI &gt; of the diffractive light-scattering system. The variable optical-scattering system according to claim 1, wherein the thickness of the PDLC layer is 10 to 20 占 퐉. The liquid crystal composition according to claim 1 or 2, wherein the liquid crystal mixture is 4 - ((4-ethyl-2,6-difluorophenyl) ethynyl) -4'-propylbiphenyl and 2-fluoro- -Bis (trans-4-propylcyclohexyl) biphenyl. &Lt; / RTI &gt; 4. The variable optical-scattering system according to any one of claims 1 to 3, wherein the difference between the standard refractive index of the liquid crystal mixture and the refractive index of the polymer matrix is less than 0.050. 5. The variable optical-scattering system according to any one of claims 1 to 4, characterized in that the difference between the average refractive index of the liquid crystal mixture and the refractive index of the polymer matrix exceeds 0.100. 6. The variable light-scattering system according to any one of claims 1 to 5, wherein the liquid crystal droplet has an average diameter of 0.70 to 1.00 m. 7. The variable light-scattering system according to any one of claims 1 to 6, wherein the weight ratio of the liquid crystal mixture to the total weight of the liquid crystal mixture and the photopolymerizable composition is from 50% to 65%. 8. The variable light-scattering system according to any one of claims 1 to 7, wherein the vinyl compound is an acrylate compound or a methacrylate compound. 9. A composition according to any one of claims 1 to 8, wherein 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 monofunctional, difunctional or multifunctional vinyl oligomer, preferably an acrylate oligomer
And a variable optical-scattering system. 10. The composition according to any one of claims 1 to 9, wherein the photopolymerizable composition is present in a weight ratio to the total weight of the photopolymerizable composition,
- from 30% to 95% of a monofunctional vinyl compound,
- from 1% to 35% of a bifunctional vinyl compound,
- 1% to 50% of a mono-functional, difunctional or multifunctional vinyl oligomer, and
- from 0 to 15% of at least one mercaptan compound
And a variable optical-scattering system. 11. The composition according to any one of claims 1 to 10, wherein the photopolymerizable composition comprising a vinyl compound comprises at least 50% of an acrylate compound and / or a methacrylate compound in a weight ratio based on the total weight of the photopolymerizable composition Wherein the diffractive optical-scattering system is a diffractive optical-scattering system. 12. The variable optical-scattering system according to any one of claims 1 to 11, characterized in that the PDLC layer also comprises spacers. 13. The variable optical-scattering system according to any one of claims 1 to 12, characterized in that the electrodes are each supported by a support selected from a glass substrate. 14. The variable optical-scattering system according to claim 13, wherein the supports are attached to each other by sealing gaskets at their edges. The variable optical-to-electrical conversion device according to any one of the preceding claims, characterized in that the change in the light transmission between the transparent state TL _on and the translucent state TL _off is less than 35%, defined as (TL _on - TL _off ) Scattering system. Claim 1 to claim 15, wherein of the method according to any one of the _{preceding, (H off - H on)} , the transparent state to be defined by the H _on and semi-transparent state variable characterized in that the change in the haze value between H _off more than 90% Light-scattering system. 17. The method according to any one of claims 1 to 16,
- in the transparent state, the light transmittance TL _on measured according to the ASTM D1003 standard is 75% or more, the haze H _on is 5%
- in the scattering state, ASTM D1003, and the tugwangyul TL _off at least 50% measured according to the standard, the haze guard plus the BYK (Hazegard Plus) when the light projection measured in a haze meter (hazemeter) Haze H _off is less than 95% and / or ,
- the light reflectance RL measured strictly in accordance with ISO 9050: 2003 standards in scattering and in transparent conditions of less than 30%
/ RTI &gt; and the variable optical-scattering system. Use of a variable light-scattering system switched between a transparent state and a translucent state according to any one of claims 1 to 17, characterized in that a switching voltage of less than 30 Vrms is applied. 17. An electronically adjustable glazing comprising a variable optical-scattering system according to any one of claims 1 to 17 and two supports each supporting an electrode of a variable optical-scattering system. 20. An apparatus comprising an electrically adjustable glazing according to claim 19, a frame, and a power source contained within the frame. 21. The apparatus of claim 20, wherein the power source is connected to a power lead comprising a power plug. 21. The apparatus of claim 20, wherein the power source is battery power. 23. The apparatus of claim 22, further comprising a zone for receiving a battery. 24. Apparatus according to any one of claims 20 to 23, further comprising a switch mounted on the frame.

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