Liquid crystal-based light valve

Abstract

The invention relates to a method of preparing a light valve which is operable in an optically clear and transparent state and an opaque state and which is electrically switchable between the optically clear and transparent state and the opaque state, wherein one or more polymerizable mesogenic compounds provided in a layer comprising a liquid crystalline medium are subjected to photopolymerization, the liquid crystalline medium comprising one or more mesogenic compounds, one or more chiral compounds, one or more dichroic dyes and one or more polymerizable mesogenic compounds. The invention further relates to a liquid crystalline medium for use in the method, to a light valve obtained or obtainable by carrying out the method, and to the use of the light valve in a mobile device.

Description

[0001] This application is a divisional application of Chinese patent application No. 202080044188.3, ​​filed on June 15, 2020, entitled "Light Valve Based on Liquid Crystal". Technical Field

[0002] This invention relates to a method for preparing a light valve operable in optically clear and transparent states and opaque states, and electrically switchable between these states. The method involves photopolymerizing one or more polymerizable mesocrystalline compounds provided in a layer containing a liquid crystal medium, the liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, one or more dichroic dyes, and one or more polymerizable mesocrystalline compounds. The invention further relates to a liquid crystal medium used in the method, to a light valve obtained or obtainable by performing the method, and to the use of the light valve in a mobile device. Background Technology

[0003] Devices used to control or modulate the transmission of light are commonly used in display applications and can also be used in various mobile devices, such as eyewear, spectacle, goggles, and visors, and in the context of augmented and virtual reality environments. Light intensity modulators (such as light valves or shutters) can be based on liquid crystals (LC). In principle, such light valves or shutters can rely on light absorption or light scattering.

[0004] In some devices, light transmission can be reversibly altered, typically by electrical switching, whereby the intensity of the incident light can be attenuated, darkened, or tinted, while simultaneously exhibiting little or no scattering or haze in different operating states. Therefore, such devices can operate in bright and dark states (i.e., relatively high and relatively low light transmission states) and switch between bright and dark states, both of which are substantially non-hazy.

[0005] Several modes or configurations can be employed to provide this reversible transmission variation. For twisted nematic (TN), super-twisted nematic (STN), and vertically aligned (VA) liquid crystal cells, polarizers are used to control light transmission. Guest-host liquid crystal cells, based on liquid crystal hosts doped with dichroic dye molecules, can also be used. These guest-host systems can be used without any polarizers to modify light transmission. However, in some embodiments and applications, guest-host liquid crystal cells are used in combination with at least one polarizer.

[0006] LC-based optical modulators that utilize light scattering include so-called polymer-dispersed liquid crystals (PDLCs) or encapsulated or nematically aligned phase liquid crystals (NCAPs), polymer network liquid crystals (PNLCs), cholesterol-type liquid crystals (CLCs), polymer-stabilized cholesterol-textured liquid crystals (PSCTs), and dynamically scattering liquid crystal devices. These scattering devices can switch between a transparent state (i.e., optically clear or hazy) and a light-scattering state (i.e., translucent or hazy).

[0007] When this scattering device switches from a non-scattering state (i.e., an optically clear state) to a scattering state, light transmission is altered, resulting in a translucent appearance, which can also be considered cloudy, hazy, diffuse, or foggy. Scattering-mode-based devices are particularly useful for temporarily providing privacy or masking of features or information when needed by switching the device from an optically clear state (usually electrically) to a scattering state.

[0008] D.-K. Yang et al. describe a low-concentration polymer dispersion with a cholesterol-type liquid crystal and its use in a light modulator that can switch between an opaque light scattering state and a transparent state in “Cholesteric liquid crystal / polymer dispersion for haze-free light shutters”, Applied Physics Letters, 60 (1992), pp. 3102-3104.

[0009] Light can also be modulated and combined in the device through absorption and scattering. This method can achieve an opaque state, which, in addition to providing haze, also exhibits a reduction in overall light intensity. In certain implementations, dichroic dyes can be used to attenuate the light, and in some instances, these dyes can also provide coloration.

[0010] In WO 00 / 60407 A1, an electro-optic glass structure with opaque and transparent operating modes is described.

[0011] In “Simultaneous control of haze and transmittance using adye-doped cholesteric liquid crystal cell”, Liquid Crystals, 42 (2015), pp. 1460-1464, B.-H. Yu et al. proposed the use of a shutter device for a dye-doped cholesteric liquid crystal for a transparent display.

[0012] J. Heo et al., in “Fast-switching initially-transparent liquid crystallight shutter with crossed patterned electrodes,” AIP Advances, 5, 047118 (2015), describe a shutter using a polymer network liquid crystal and dichroic dyes with crossed patterned electrodes, which can switch between a transparent and an opaque state. In the opaque state, the device blocks background images and provides black. The proposed shutter has potential applications in see-through displays and smart windows.

[0013] B.-H. Yu et al. proposed using a light shutter of a cholesteric liquid crystal with dye-doped cholesteric liquid crystals with polymer network structure in a transparent display, in "Light shutter using dye-doped cholesteric liquid crystals with polymer network structure", Journal of Information Display, 18 (2017), pp. 13-17.

[0014] There is a need in the art for additional optical modulators with improved optical and electro-optical properties, particularly optical valves (such as shutters). There is also a need in the art for suitable methods for fabricating such switchable devices. Summary of the Invention

[0015] Therefore, one object of the present invention is to provide a convenient, efficient, and robust method for fabricating a light valve that is operable in both optically transparent and opaque states and electrically switchable between the two states, and possesses improved optical and electro-optical properties. Another object of the present invention is to provide a light valve with advantageous properties and particularly suitable for use in mobile and portable devices and in augmented or virtual reality settings. Another object is to provide a liquid crystal medium with advantageous chemical, physical, and electro-optical properties, which are particularly suitable for the method according to the present invention and result in advantageous modulation materials in the light valve. Other objects of the present invention will readily become apparent to those skilled in the art from the following detailed description.

[0016] This objective is achieved by means of the objective defined in the independent claim, however preferred embodiments are set forth in the dependent claims and further described below.

[0017] In particular, the present invention provides the following provisions, which include key aspects, preferred embodiments and specific features, which individually and in combination contribute to solving the above objectives and ultimately provide additional advantages. Detailed Implementation

[0018] A first aspect of the present invention provides a method for fabricating a light valve, which is operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, the method comprising:

[0019] (i) A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, one or more dichroic dyes, and one or more polymerizable mesocrystalline compounds is provided as a layer inserted between two opposing transparent substrates, each substrate having electrodes.

[0020] The liquid crystal medium has a clearing point of 70°C or higher, and

[0021] The one or more polymerizable mesocrystalline compounds are contained in the medium in an amount of 4% by weight or less based on the total contents of the medium, and

[0022] (ii) Using photopolymerization to polymerize one or more polymerizable mesocrystalline compounds in the layer.

[0023] In this article, "light valve" refers to a component that modulates light, which is constructed as a box formed by two walls, specifically two transparent substrates, which are spaced apart and provided with electrodes, and the box contains light modulation material.

[0024] Optically transparent refers to a state of low haze and high transmittance. Preferably, in the optically transparent state, the prepared light valve has a haze of less than 15% as measured according to ASTM D 1003 and a light transmittance of more than 45% as measured according to DIN EN410. Opaque refers to a state of high haze and low transmittance. Preferably, in the opaque state, the prepared light valve has a haze of more than 65% as measured according to ASTM D 1003 and a light transmittance of less than 35% as measured according to DIN EN410.

[0025] In this invention, it is recognized that, for certain situations and applications, it is desirable to provide optical valves that are particularly advantageous for use in mobile or portable devices. In addition to lightweight construction, rapid switching, low operating voltage, and low power consumption are desired in these situations. It has been unexpectedly found that optical valves exhibiting rapid switching, operability at suitable low voltages, and low power consumption can be obtained by using a combination of methods and materials according to the invention. Furthermore, the method provides optical valves with advantageous performance even at low temperatures, particularly regarding switching speed. Given the use of the device in mobile applications, the properties of these combinations provide significant benefits. Moreover, despite exposing the medium to photopolymerization in this method, it has been unexpectedly found that optical valves exhibiting good reliability, durability, and stability (e.g., in terms of electrolysis and photostability) can be prepared.

[0026] Surprisingly, the method according to the invention provides a convenient and efficient method for preparing a light valve that exhibits the advantageous properties described herein.

[0027] Another aspect of the invention relates to a light valve operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, wherein the light valve is obtained or can be obtained by performing the method of the invention as described above and below.

[0028] In this invention, it is recognized that advantageous performance and appearance are desired not only in the opaque state but also in the optically transparent state, in which undesirable haze should be avoided or minimized and relatively high transmittance should be required. The light valve provided according to the invention advantageously provides this low-haze transparent state, while also providing the possibility of appropriately efficient and sufficiently uniform scattering and adjustment, and particularly minimizing overall light transmission in the opaque state. Furthermore, the device provides additional benefits such as advantageously low switching voltage and low power consumption, rapid switching between states, and good reliability, durability, and stability, for example, in terms of electrolysis and optical stability.

[0029] Furthermore, the materials and methods used according to the present invention also provide the possibility of using active matrix addressing in a switchable box. By dividing the light valve into many pixels, information can be displayed and used in backgrounds for augmented or virtual reality applications.

[0030] In an aspect of the invention, a light valve is provided that is operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, and includes a switching layer containing a material comprising

[0031] - A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, and one or more dichroic dyes, wherein the liquid crystal medium has a clearing point of 70°C or higher, and

[0032] - A polymeric component comprising one or more polymeric structures obtained or obtainable by polymerization of one or more polymerizable mesocrystalline compounds, wherein the polymeric component is contained in the material in an amount of 4% by weight or less based on the total contents of the material.

[0033] The light valve, in its optically transparent state, preferably has a haze of less than 15% as measured according to ASTM D 1003 and preferably a light transmittance of more than 45% as measured according to DIN EN410, and in its opaque state, preferably has a haze of more than 65% as measured according to ASTM D 1003 and preferably a light transmittance of less than 35% as measured according to DIN EN410.

[0034] According to the present invention, a device for light management is provided, capable of both absorbing and scattering light. The device can therefore switch between two different optical states: a low-haze, high-transmittance state and a high-haze, low-transmittance state. This light valve can be used to adjust or modulate light paths, particularly sunlight paths, as well as light paths from artificial light sources (such as lamps), light-emitting diodes (especially organic light-emitting diodes), and luminaires. In an opaque state, the light valve can create a visual barrier.

[0035] According to a preferred embodiment, the liquid crystal medium in the material contained in the switching layer of the light valve exhibits a pitch of 0.55 µm or greater in an opaque state.

[0036] It has been unexpectedly discovered that an improved optical valve can be obtained by providing a switching layer containing a liquid crystal medium and a polymeric component as described above and below. In particular, providing a cholesterol-type or chiral nematic medium with high-definition highlights and preferably long pitch, as currently defined, combined with a relatively small amount of polymeric component (containing a polymeric structure obtainable by polymerization of at least one polymerizable mesocrystalline compound) unexpectedly provides a device with a favorable clear state, i.e., a favorable uniform low-haze and optically transparent state, and a scattering state with enhanced scattering efficiency, wherein the device can be conveniently switched between states by applying a voltage.

[0037] In particular, the preferred combination of long-pitch cholesterol-type media and the presence of polymeric components as described herein can provide unexpectedly strong scattering with a suitable wide-angle scattering distribution. This is advantageous because a single switching layer in the provided assembly can result in suitable haze. Furthermore, the thickness of the switching layer can be relatively low, particularly substantially less than 50 µm, which thus reduces operating voltage and power consumption, and also reduces material usage.

[0038] Furthermore, by suitably providing one or more dichroic dyes in a liquid crystal medium preferably in solution, the light transmittance, especially in the opaque state, can be advantageously adjusted and minimized as desired, while also providing the possibility of a colored opaque state.

[0039] By setting and adjusting the combination of materials as currently defined, a light valve with advantageous performance can be obtained.

[0040] Therefore, another aspect of the present invention relates to a liquid crystal medium, particularly those used in the methods according to the invention, the liquid crystal medium comprising one or more polymerizable mesocrystalline compounds, one or more mesocrystalline compounds, one or more chiral compounds, and one or more dichroic compounds in an amount of 4% by weight or less based on the total contents of the medium.

[0041] It has been unexpectedly discovered that by providing the liquid crystal medium according to the invention, a medium with improved properties, particularly suitable for high-definition bright spots and preferably suitable for long pitches, can be obtained, which is particularly useful for preparing modulation materials for switching layers and light valves according to the invention. Furthermore, the medium provides other benefits such as a wide liquid crystal phase, suitable high optical anisotropy, advantageous high voltage retention ratio (VHR), good low-temperature stability, and good light stability.

[0042] In another aspect of the invention, an optical modulation material is provided, particularly for use in those optical valves according to the invention, comprising...

[0043] - A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, and one or more dichroic dyes, wherein the liquid crystal medium has a clearing point of 70°C or higher, and

[0044] - A polymeric component comprising one or more polymeric structures obtained by or obtainable by polymerization of one or more polymerizable mesocrystalline compounds, wherein the polymeric component is contained in the material in an amount of 4% by weight or less based on the total contents of the material.

[0045] The modulation material according to the invention can be advantageously used in switching elements, preferably in optically variable devices to adjust light, and particularly in light valves based on light scattering and dimming. The modulation material according to the invention can be used in devices for regulating electromagnetic radiation, preferably light, and particularly sunlight, and light paths from artificial light sources.

[0046] Particularly preferred is the modulation material according to the invention used in CLC scattering devices. It is now recognized that when the material contains a chiral nematic or cholesteric liquid crystal medium having advantageous high-definition highlights and preferably a relatively long pitch, combined with a polymeric component as defined herein, and particularly when a so-called polymer-stabilized cholesteric texture (PSCT) is provided, specific benefits can be obtained, for example, in terms of scattering efficiency or uniformity and the appearance of the scattering effect.

[0047] Surprisingly, the modulated materials obtained by the methods described herein exhibit good reliability and stability, particularly photostable stability. Stable and efficient modulated materials containing one or more dichroic dyes are available by advantageously adjusting and matching the provided material combinations and the conditions described herein, despite subjecting the initial medium to photopolymerization.

[0048] According to the present invention, the liquid crystal medium and modulation material as described herein can be advantageously configured and used in the switching layer. In another aspect, a switching layer is thus provided, comprising the medium or the material according to the present invention, preferably composed of it.

[0049] The switching layer can be configured between two substrates to provide a switching element that is electrically switchable and operable in an optically transparent state and an opaque state.

[0050] Polymerization stabilization can provide benefits for scattering performance and efficiency in the scattering state, while still allowing favorable transparency in the transparent state.

[0051] Another aspect of the present invention relates to the use of light valves in mobile or portable devices.

[0052] In addition to low operating voltage and low power consumption, light valves offer the advantages of fast switching times, reduced temperature dependence, and reliable switching even at low temperatures (e.g., at 0°C and below). This combination of properties is particularly beneficial for mobile applications. Light valves can temporarily (i.e., for a given period of time but not other periods) contribute to enhanced contrast or information readability, as required in mobile applications (e.g., in transparent or normal-view displays) and under varying lighting conditions (especially different ambient light conditions).

[0053] The present invention will be described below by way of detailed description of aspects, embodiments and specific features, without limiting the invention, and by describing specific embodiments in more detail.

[0054] In this document, the term "liquid crystal" (LC) preferably refers to a material or medium having a liquid crystal mesophase within certain temperature ranges (thermotropic LC). It contains mesocrystalline compounds.

[0055] The terms "mesocrystalline compound" and "liquid crystal compound" refer to compounds containing one or more rod-shaped (bar-shaped or plate / strip-shaped) or disc-shaped (disc-shaped) mesocrystalline groups (i.e. groups capable of inducing liquid crystal phase or mesophase characteristics).

[0056] LC compounds or materials containing mesocrystalline groups and mesocrystalline compounds or materials themselves do not necessarily exhibit a liquid crystal phase. They may also exhibit liquid crystal phase properties only in mixtures with other compounds. These compounds include low molecular weight nonreactive liquid crystal compounds, reactive or polymerizable liquid crystal compounds, and liquid crystal polymers.

[0057] Rod-shaped mesocrystalline compounds typically comprise a mesocrystalline nucleus consisting of one or more aromatic or non-aromatic cyclic groups directly connected to each other or linked via bonding groups, optionally comprising end groups attached to the ends of the mesocrystalline nucleus, and optionally comprising one or more side groups attached to the long sides of the mesocrystalline nucleus, wherein these end groups and side groups are typically selected from, for example, carbonyl or hydrocarbon groups; polar groups such as halogens, nitro groups, hydroxyl groups, etc.; or polymerizable groups.

[0058] For simplicity, the term "liquid crystal" or "liquid-crystalline" is used for liquid crystal materials or media and mesocrystalline materials or media, and vice versa, and the term "mesocrystalline" is used for the mesocrystalline group of the material.

[0059] The term "non-mesocrystalline compound or material" means a compound or material that does not contain mesocrystalline groups as defined above.

[0060] As used herein, the term "polymer" should be understood to mean a molecule with a backbone comprising one or more different types of repeating units (the smallest constituent units of a molecule), and includes commonly known terms such as "oligomer," "copolymer," and "homogeneous polymer." Furthermore, it should be understood that the term "polymer" includes, in addition to the polymer itself, residues from initiators, catalysts, and other elements accompanying the synthesis of such polymers, wherein such residues should be understood as not covalently incorporated therein. Moreover, although such residues and other elements are typically removed during post-polymerization purification processes, they are often mixed or blended with the polymer so that they are typically retained with the polymer when it is transferred between containers or between solvents or dispersion media.

[0061] The term "polymerization" refers to the chemical process of forming a polymer by bonding together multiple polymerizable groups or polymer precursors (polymerizable compounds) containing such polymerizable groups.

[0062] A polymerizable compound with one polymerizable group is also called a "single-reactive" compound, a compound with two polymerizable groups is called a "two-reactive" compound, and a compound with more than two polymerizable groups is called a "multi-reactive" compound. A compound without polymerizable groups is also called a "non-reactive" or "non-polymerizable" compound.

[0063] The terms “thin film” and “layer” include rigid or flexible self-supporting or freestanding thin films or layers that have more or less significant mechanical stability, as well as coatings or layers on or between two substrates.

[0064] The term "chirality" is generally used to describe objects that are not superimposed on their mirror images. Conversely, a "chiral" object is an object that is identical to its mirror image. The medium according to the invention exhibits chirality. This can be achieved by providing a cholesterol-type liquid crystal (also known as a chiral nematic liquid crystal). Unless otherwise explicitly stated, the terms chiral nematic and cholesterol-type are used synonymously herein.

[0065] In this article,

[0066] , and

[0067] It represents the trans-1,4-cyclohexyl group.

[0068] In this document, unless otherwise explicitly stated, all concentrations are given as weight percentages and refer to the individual whole mixtures.

[0069] All temperatures are given in degrees Celsius (°C), and all temperature differences are given in degrees Celsius. Unless otherwise explicitly stated, all physical properties and physicochemical or electro-optic parameters are measured and given for a temperature of 20°C.

[0070] The preferred range for light transmission and scattering is the spectral range of 380 nm to 780 nm.

[0071] The preferred switching refers to the switching between two binary states, where one state is preferably a non-scattering state that appears substantially transparent or clear to the human eye, and the other state is a scattering state or has diffuse transmission and appears translucent or opaque to the human eye. The opaque state can simultaneously provide black or another color that does not cover the entire visible spectrum.

[0072] However, the switching layer according to the invention may also have other switching states, particularly intermediate states.

[0073] Therefore, according to the present invention, it is preferable and advantageous to be able to switch between a completely opaque state and a state with visibility through the transmission device.

[0074] In the optically transparent state according to the invention, the light valve preferably has a haze of less than 15%, more preferably less than 10%, even more preferably less than 5%, and particularly less than 2.5%, as determined according to ASTM D 1003, and a light transmittance of more than 45%, more preferably more than 50%, even more preferably more than 55%, and particularly more than 65%, as determined according to DIN EN410.

[0075] In its opaque state according to the invention, the light valve preferably has a haze of more than 65%, more preferably more than 80%, and even more preferably more than 90% as measured according to ASTM D 1003, and preferably less than 35%, more preferably less than 25%, and even more preferably less than 10%, and particularly less than 5% as measured according to DIN EN 410. Particularly preferably, in its opaque state, the light valve according to the invention has a haze of 75% or more as measured according to ASTM D 1003.

[0076] To measure haze, a haze meter manufactured by BYK-Gardner can be used. Spectrophotometers, particularly Ulbricht's sphere, may also be used.

[0077] The switching according to the present invention preferably refers to electrical switching. Electrical switching is typically achieved by providing a substrate with electrodes, such as a glass or plastic substrate. In one embodiment, a conductive layer is provided on the substrate, wherein the conductive layer comprises or is formed of: a transparent conductive material, such as a transparent conductive oxide, preferably indium tin oxide (ITO) or SnO2:F, especially ITO, or a conductive polymer; or a thin transparent metal and / or metal oxide layer, such as silver. The conductive layer is preferably provided with electrical connections. The voltage is preferably supplied by a battery, a rechargeable battery, a supercapacitor, or an external current source, more preferably by an external current source.

[0078] In one embodiment, an alignment layer, for example made of polyimide (PI), is provided on a substrate. It is particularly preferred that a conductive layer and an alignment layer are provided together on the substrate. In this case, an alignment layer or alignment layer is provided on top of the conductive layer so that the alignment layer is in contact with the LC medium. The alignment layer, preferably a polyimide layer, can be configured such that it contains liquid crystal medium molecules oriented planarly or vertically, particularly at the interface. In a particular embodiment, rubbed polyimide is used on a substrate with a 90° orientation difference, such as that used in a so-called twisted nematic (TN) geometry.

[0079] In one particular embodiment, an alignment layer with a pretilt angle is used, for example, a pretilt angle in the range of 0° to 20° for TN geometry, or a pretilt angle of 80° to 90° for vertical alignment (VA) geometry.

[0080] Alternatively, according to another embodiment, a substrate without an orientation layer is used. Surprisingly, it has been found that it is advantageous to avoid setting an orientation layer, such as a polyimide layer, as an additional layer, while still achieving effective and efficient switching characteristics.

[0081] Alternatively, in addition to the alignment layer, a passivation layer or barrier layer may be provided on the substrate, such as a passivation layer comprising silicon oxide or silicon nitride, preferably a passivation layer composed of silicon oxide or silicon nitride. When both a passivation layer and an alignment layer are provided on the substrate, they are arranged such that the alignment layer is at the very top, i.e., in contact with the LC dielectric.

[0082] The method according to the invention provides a switching element, and in particular a light valve, operable in an optically transparent state and an opaque state, electrically switchable between the optically transparent and opaque states, and comprising a switching layer. The switching layer, obtainable by this method, contains a material comprising a liquid crystal medium and a polymeric component. The liquid crystal medium comprises one or more mesocrystalline compounds, one or more dichroic dyes, and one or more chiral compounds. The polymeric component comprises one or more polymeric structures obtained by or obtainable from the polymerization of one or more polymerizable mesocrystalline compounds.

[0083] According to the invention, the polymeric component is contained in the material in an amount of 4% by weight or less, preferably 3% by weight or less, more preferably 2% by weight or less, and particularly 1% by weight or less, based on the total content of the material. In a preferred embodiment, the polymeric component is contained in the material in an amount ranging from 0.5% by weight to 1.5% by weight, based on the total content of the material.

[0084] The polymeric component comprises one or more polymeric structures obtained by polymerizing one or more polymerizable mesocrystalline compounds or respectively obtainable by polymerizing one or more polymerizable mesocrystalline compounds. The polymeric component is preferably obtained by exclusive polymerization of one or more polymerizable mesocrystalline compounds, that is, the polymeric component preferably consists of one or more polymeric structures based solely on or respectively derived solely from one or more polymerizable mesocrystalline compounds as precursors.

[0085] According to the method of the present invention, the polymerizing component is preferably prepared in situ, particularly in the switching layer, by polymerizing one, two or three polymerizable mesocrystalline compounds, or even more preferably one or two polymerizable mesocrystalline compounds.

[0086] The polymerizable mesocrystalline compounds according to the present invention contain a mesocrystalline group and one or more polymerizable groups, i.e., functional groups suitable for polymerization. These compounds are also called reactive mesocrystalline (RM) or mesocrystalline monomers. RM can be monoreactive and / or direactive or multireactive.

[0087] Preferably, the liquid crystal medium used in the method comprises at least one di-reactive or multi-reactive polymerizable mesocrystalline compound.

[0088] Although the polymerizable compounds used in this invention preferably comprise only reactive mesomorphs, i.e., all reactive monomers are mesomorphous, in alternative embodiments one or more RMs and one or more non-mesomorphous polymerizable compounds may also be used.

[0089] The polymerizable and mesocrystalline compounds can be selected based on the polymerizable components in the obtained modulated material and the refractive index of the LC medium, which advantageously contributes to improving the clarification state.

[0090] According to the present invention, in particular, the liquid crystal medium used in the method and provided in the light valve has a clearing point of 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, even more preferably 98°C or higher, even more preferably 102°C or higher, and especially 115°C or higher. Preferably, the medium has a clearing point in the range of 90°C to 160°C, and more preferably 100°C to 150°C.

[0091] All physical properties and physicochemical or electro-optic parameters were determined by generally known methods, especially according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany.

[0092] The clearing point, especially the phase transition temperature between the chiral nematic or cholesterol phase and the isotropic phase, can be measured and determined by commonly known methods, such as using a Mettler oven, a hot stage under a polarizing microscope, or differential scanning calorimetry (DSC). According to the present invention, a Mettler oven is preferably used to determine the clearing point.

[0093] Furthermore, according to the present invention, preferably, the liquid crystal medium used in the switching layer of the light valve exhibits a pitch of 0.55 µm or greater in the scattering state.

[0094] The cholesterol-type or chiral nematic media currently available preferably have relatively long pitches, and particularly preferably have pitches greater than 780 nm for Bragg-type reflection. In this case, planar textures can also provide favorable transmission in the visible spectrum.

[0095] In this document, pitch refers to the pitch p of a cholesterol-type helix, where pitch p is the distance from the orientation axis (director) of the CLC undergoing 2π rotations. In a preferred embodiment, the medium exhibits a pitch of 0.75 µm or longer, even more preferably 1.00 µm or longer, and especially 1.50 µm or longer.

[0096] The concentration of one or more chiral dopants is preferably set such that the resulting chiral pitch is in the range of 0.55 µm to 10 µm.

[0097] According to the present invention, the pitch is particularly determined by the maximum selective reflection wavelength λ at 20°C. max The NIR spectroscopic measurements were performed. The pitch p was determined by λ. max The measured value is obtained using the equation λ. max = n(λ max )×p is determined, where n(λ) max ) is λ maxThe refractive index below.

[0098] Alternatively, wedge cell methods known in the art, particularly for measuring helical torsional force (HTP) and determining the measurement pitch at 20°C, can be used.

[0099] Surprisingly, the light valve according to the invention can be switched to an opaque state and operated in the opaque state, providing effective and sufficiently strong scattering, particularly diffuse transmittance, with a uniform appearance to the eye, especially over a large area. This uniform appearance advantageously includes a color-neutral appearance, meaning that unwanted color artifacts (such as a rainbow-like appearance) can be minimized or even avoided.

[0100] It is believed that the material provided in the switching layer according to the invention can, for example, generate sufficient scattering with the desired haze by scattering from the material region, especially from the boundary, defect or irregular structure. However, the diffraction of incident light generated by the periodic structure can be substantially suppressed or avoided by sufficiently disrupting or destroying the periodicity on the relevant length scale, especially by introducing polymeric components. In this regard, it can be surprisingly effective even when only a small amount is contained.

[0101] Furthermore, by using the method according to the invention, a light valve that advantageously possesses optical clarity and little or no indistinguishable residual haze and relatively high light transmittance can be obtained.

[0102] The light valve itself preferably does not contain any light source. The light valve can be suitably integrated into an electro-optical device, such as a display, screen, or glasses, for example by lamination, adhesive bonding, or mounting.

[0103] Preferably, the optical valve does not contain a polarizer.

[0104] The light valve is available in various sizes, for example, approximately 1 mm. 2 Small sizes up to 1 m 2 It can be implemented in dimensions beyond the stated dimensions, and can have different shapes, such as squares, rectangles, circles, ellipses, triangles, or polygons.

[0105] According to the present invention, the state of the switching layer and the optical valve is controlled by an electric field applied by means of electrodes. The electrodes are preferably transparent electrodes, which are disposed on the substrate in the form of a coating. The coating is typically applied to the substrate side or surface facing the switching layer.

[0106] In one embodiment, the electrodes are unpatterned and / or unstructured, making them adjacent. Therefore, the entire switchable region is simultaneously addressed and switched by applying an electric field. In an alternative embodiment, the electrodes may be patterned to form individual addressable regions or pixels, which can be switched independently of other regions by applying an electric field. In this case, conventionally used TFT technology can be used for active and independent addressing of segmented regions.

[0107] As described herein, the liquid crystal medium is used in the method and provided in the obtained switching layer and light valve.

[0108] In a preferred embodiment, the LC medium used according to the invention has positive dielectric anisotropy. In this case, a liquid crystal mixture having a dielectric anisotropy Δε in the range of 3 to 45, more preferably in the range of 5 to 30, is preferred.

[0109] Δε represents dielectric anisotropy, where Δε = ε ‖ - ε ⊥ Dielectric anisotropy Δε was measured at 20 °C and 1 kHz.

[0110] In alternative embodiments, however, an LC medium with negative dielectric anisotropy may also be provided. In this case, a liquid crystal mixture having a dielectric anisotropy Δε in the range of -6 to -3 is preferred.

[0111] Advantageously, the medium according to the invention can have a suitablely high optical anisotropy Δn, which is also referred to as birefringence. The medium used as described herein and in the switching layer and optical valve according to the invention preferably exhibits an optical anisotropy Δn of 0.13 or more, more preferably 0.16 or more, and even more preferably 0.20 or more, as measured at 20°C and 589 nm.

[0112] In the preceding and following text, Δn represents optical anisotropy, where Δn = n e - n o Furthermore, the optical anisotropy Δn was measured at 20℃ and a wavelength of 589.3 nm.

[0113] Preferably, the medium used according to the invention comprises one or more mesocrystalline compounds selected from compounds of formulas I and II.

[0114]

[0115] in

[0116] R 1 and R 2 The groups, independently of each other, are selected from the following groups: F, Cl, CF3, OCF3, and straight-chain or branched alkyl or alkoxy groups having 1 to 15 carbon atoms, or straight-chain or branched alkenyl groups having 2 to 15 carbon atoms, which are unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other.

[0117] A 11 express

[0118]

[0119] n represents 0 or 1, and

[0120] A 21 A 31 and A 41 Representing each other independently

[0121]

[0122] Wherein L appears each time as a halogen selected from F, Cl, and Br, and

[0123] R 3 and R 4 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other.

[0124] L 1 L 2 and L 3 H or F can be represented independently of each other.

[0125] Particularly preferably, the medium used according to the invention contains at least 5% by weight, more preferably at least 10% by weight and even more preferably 15% by weight of one or more mesocrystalline compounds selected from compounds of formula I and II, based on the total contents of the medium.

[0126] In addition to a suitably high optical anisotropy, the medium according to the invention advantageously exhibits a high voltage retention rate (VHR), good optical stability, and a suitably high clearing point.

[0127] The use of, especially in the presence of low amounts of reactive mesomorphs as specified, and preferably in the presence of chiral dopants with high HTP that can be used at low concentrations, advantageously helps to maintain a favorable high clearing point.

[0128] The medium is either cholesterol-type or chiral nematic. Cholesterol-type liquid crystals (CLCs) typically contain a medium that, in its initial state, has a flat structure, for example, reflecting light of a specific wavelength, and can be switched to a focal conic light-scattering structure, or vice versa, by applying an alternating voltage pulse. When a stronger voltage, especially a stronger voltage pulse, is applied, the CLC medium can switch to a vertically transparent state, relax from this vertically transparent state to a flat state after a rapid voltage cut-off, or relax to a focal conic state after a slow voltage cut-off.

[0129] Bragg reflection occurs in planar textures, where the reflected light has the same dechirality as the cholesterol-type helix.

[0130] In the focal cone state, the spiral axis is randomly configured, and the texture exhibits light scattering due to the spatial variation of the refractive index at the region boundary.

[0131] Planar and focal conic configurations are generally stable in the absence of an external electric field. The effect of the electric field-driven texture transition between the planar and focal conic states forms the basis of the operation of CLC displays, where Bragg reflections disappear when the CLC texture switches from a planar texture to a focal conic texture, and the incident light is scattered by the CLC due to the random distribution of the helical axes.

[0132] However, the switching between these states is usually achieved only via the vertical state, where the cholesterol-type helix completely unwinds through dielectric coupling between the LC molecule with positive dielectric anisotropy (Δε > 0) and the vertical electric field.

[0133] In one embodiment of the present invention, the hazy, opaque state of the switching layer can be the focal cone state described above.

[0134] Alternatively, and according to a preferred embodiment, in this invention, the hazy, opaque state is formed by a multi-domain structure. This multi-domain structure preferably produces sufficiently strong scattering, while Bragg-type reflection characteristics remain at least partially observable. This includes, preferably, a phase composed of multiple domains, in which the orientation of the helical axis generally differs between regions, and region boundaries are typically present. However, macroscopically, the phase can appear homogeneous to the human eye, particularly uniformly opaque or hazy, and free of visible defects across the entire layer region.

[0135] Multi-domain structures can be obtained, for example, using conventional orientation layers oriented in a planar or vertical manner, and advantageously, switching to a multi-domain state can be achieved at relatively low voltages. However, multi-domain structures can also be obtained when no orientation layer is present.

[0136] In addition, the presence of polymeric components in the modulation material and switching layer can advantageously influence and stabilize the scattering performance.

[0137] In a preferred embodiment, the non-scattering or clear state can be formed by the vertical state described above. In this respect, the currently available advantageous high VHR can be used to stabilize the element in this state to avoid self-discharge characteristics, and thus maintain a state with even significantly lower refresh rates and / or lower power consumption.

[0138] Alternatively, the non-scattering or clarified state can be formed by the planar texture described above.

[0139] The advantage of using chiral nematic or cholesterol-type dielectrics is that they can provide relatively stable states, and even bistable states, so that devices containing such dielectrics can consume less energy. In particular, the states can be maintained for at least a considerable period of time after the electric field has been disconnected, and less frequent addressing or refreshing of the voltage is possible.

[0140] In a preferred embodiment, the light valve can be switched to an optically transparent state by applying an AC voltage V1, and can be switched to an opaque state by applying an AC voltage V2, wherein V1 > V2.

[0141] In one embodiment, the switched clarification state (particularly the state with vertical alignment) is maintained by applying a voltage in the range of 15 V to 100 V, more preferably 20 V to 80 V, and especially 25 V to 50 V, while the switched opaque state can be stabilized even at 0 V for at least some time.

[0142] Preferably, the optical valve according to the invention does not use dual-frequency addressing, which simplifies the required electronics.

[0143] As mentioned above, the medium preferably exhibits selective reflectance at wavelengths greater than 780 nm. Therefore, the medium is preferably reflective in the near-infrared (NIR) spectral region.

[0144] Chiral dopants and their concentrations can be provided to suitably set or adjust the cholesterol-type pitch of the medium. CLC media can be prepared, for example, by doping a nematic LC medium with a chiral dopant having high torsional force. The induced cholesterol-type helix pitch p is then given by the concentration c of the chiral dopant and the helical torsional force HTP according to equation (1):

[0145] p = (HTP c) -1 (1)

[0146] Two or more dopants can also be used, for example, to compensate for the temperature dependence of the HTP of each dopant and thus achieve a smaller temperature dependence of the helical pitch and reflection wavelength of the CLC medium. For the total HTP (HTP) 总 Then, roughly apply equation (2):

[0147] HTP总 = ∑ i c i HTP i (2)

[0148] Where c i It is the concentration of each individual dopant and HTP i It is the helical twisting force of each individual dopant.

[0149] The liquid crystal medium contains one or more chiral compounds, particularly one or more chiral dopants. The chiral dopants preferably have high absolute HTP values ​​and can typically be added to the mesocrystalline base mixture at relatively low concentrations, and have good solubility in the achiral components. If two or more chiral compounds are used, they may have the same or opposite rotational directions and the same or opposite torsion temperature dependence.

[0150] Preferably, one or more chiral compounds according to the invention have a concentration of 5 µm in a commercial liquid crystal mixture MLC-6828 from Merck KGaA. -1 Or larger, more preferably 10 µm -1 Or larger, and even more preferably 15 µm -1 Or a larger absolute value of helical torsion force. Particularly preferred is a 20 µm value in the commercial liquid crystal mixture MLC-6828 from Merck KGaA. -1 Or larger, preferably 40 µm -1 Or larger, or even more preferably 60 µm -1 Or larger, with the optimal size being 80 µm. -1 Or even larger than 260 µm -1 Chiral compounds with absolute values ​​of helical torsional force (HTP) within a smaller range.

[0151] The content of one or more chiral compounds in the liquid crystal medium is preferably 2% by weight or less, more preferably 1% by weight or less, and even more preferably 0.5% by weight or less, based on the total content of the medium.

[0152] In a preferred embodiment of the invention, the chiral component consists of two or more chiral compounds, each having the same HTP label. The temperature dependence of the HTP of each compound can be high or low. The temperature dependence of the media pitch can be compensated by mixing compounds with different HTP temperature dependencies in appropriate ratios.

[0153] Suitable chiral dopants are known in the art, some of which are commercially available, such as cholesterol nonanoate, R / S-811, R / S-1011, R / S-2011, R / S-3011, R / S-4011, R / S-5011, and especially R-5011, B(OC)2C HC-3 or CB15 (both from Merck KGaA, Darmstadt, Germany).

[0154] Particularly suitable chiral dopants are compounds containing one or more chiral groups and one or more mesomorphic groups, or one or more aromatic or alicyclic groups that form mesomorphic groups with the chiral groups.

[0155] Suitable chiral groups are, for example, chiral branched hydrocarbon groups, chiral ethylene glycol, binaphthol, or dioxolane, and are also selected from mono- or polyvalent chiral groups such as sugar derivatives, sugar alcohols, sugar acids, lactic acids, chiral substituted diols, steroid derivatives, terpene derivatives, amino acids, or sequences of several (preferably 1 to 5) amino acids.

[0156] Preferred chiral groups are sugar derivatives, such as glucose, mannose, galactose, fructose, arabinose, and dextrose; sugar alcohols, such as sorbitol, mannitol, idoteol, galactitol, or their dehydrated derivatives, particularly disohydrated hexotols, such as disohydrated sorbitol (1,4:3,6-disohydrated-D-sorbitol, isosorbitol), disohydrated mannitol (isosorbitol), or disohydrated idoteol (isoidoteol); sugar acids, such as gluconic acid, gulonic acid, and ketogulonic acid; chiral substituted glycol groups, such as mono- or oligomeric polyethylene glycol or propylene glycol, wherein one or more CH2 groups are substituted with alkyl or alkoxy groups; amino acids, such as alanine, valine, phenylglycerol, etc. A sequence of amino acids or phenylalanine or 2 to 5 of these amino acids; steroid derivatives, such as cholesterol or bile acid groups; terpene derivatives, such as menthyl, neomenthyl, campheyl, pineyl, terpineyl, isolongifolyl, frangyl, carreyl, myrthenyl, nopyl, geraniyl, linaloyl, neryl, citronellyl, or dihydrocitronellyl.

[0157] Suitable chiral groups and mesocrystalline chiral compounds are described, for example, in DE 34 25 503, DE 35 34 777, DE 35 34 778, DE 35 34 779 and DE 35 34 780, DE 43 42 280, EP 01 038 941 and DE 195 41820.

[0158] The preferred chiral compounds used in this invention are selected from the group consisting of the following compounds.

[0159] In one embodiment, the dopant is preferably selected from the group consisting of compounds of the following formulas: AI to A-III.

[0160]

[0161] in

[0162] R a11 and R a12 Each is independently an alkyl, oxane, or alkenyl group having 2 to 9, preferably up to 7, carbon atoms, and R a11 Alternatively, it may be methyl or alkoxy having 1 to 9 carbon atoms, preferably both of which are alkyl, and more preferably n-alkyl.

[0163] R a21 and R a22 Independently, they are alkyl or alkoxy groups having 1 to 9, preferably up to 7 carbon atoms, or oxaalkyl, alkenyl, or alkenyloxy groups having 2 to 9, preferably up to 7 carbon atoms, preferably both of which are alkyl groups, and more preferably n-alkyl groups.

[0164] R a31 and R a32 Each is independently an alkyl, oxane, or alkenyl group having 2 to 9, preferably up to 7, carbon atoms, and R a11 Alternatively, it may be methyl or alkoxy having 1 to 9 carbon atoms, preferably both of which are alkyl, and more preferably n-alkyl.

[0165] Chiral dopants, especially those composed of compounds of the following formula, are preferred:

[0166]

[0167] More preferably, the dopant is a derivative of isosorbide, isomannitol, or isoidutol of the following formulas A-IV:

[0168]

[0169]

[0170]

[0171] The preferred choice is disohydrated sorbitol.

[0172] And chiral ethylene glycols, such as diphenylethylene glycol (hydrogenated benzoin), especially mesocrystalline hydrogenated benzoin derivatives of the following formula AV:

[0173]

[0174] Including (R,S), (S,R), (R,R), and (S,S) enantiomers, which are not shown.

[0175] in

[0176]

[0177] L is H, F, Cl, CN, or optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, or alkoxycarbonyloxy groups having 1 to 7 carbon atoms.

[0178] c is 0 or 1.

[0179] Z 0 It is -COO-, -OCO-, -CH2CH2- or a single bond, and

[0180] R 0 It is an alkyl, alkoxy, alkyl carbonyl, alkoxy carbonyl or alkyl carbonyloxy group having 1 to 12 carbon atoms.

[0181] Compounds of formula A-IV are described in WO 98 / 00428. Compounds of formula AV are described in GB-A-2,328,207.

[0182] In another embodiment, the chiral dopant is particularly preferred to be a chiral binaphthyl derivative, as described in WO 02 / 94805; a chiral binaphthol acetal derivative, as described in WO 02 / 34739; a chiral TADDOL derivative, as described in WO 02 / 06265; and a chiral dopant having at least one fluorinated bridging group and a terminal or central chiral group, as described in WO 02 / 06196 and WO 02 / 06195.

[0183] Chiral compounds of formula A-VI are particularly preferred.

[0184]

[0185] in

[0186] X 1 X 2 Y 1 and Y 2Each of the following is independently an F, Cl, Br, I, CN, SCN, SF5, a straight-chain or branched alkyl group having 1 to 25 carbon atoms, which may be mono- or poly-substituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH2 groups may be independently substituted by -O-, -S-, -NH-, NR in such a manner that the O and / or S atoms are not directly bonded to each other. 0 -, -CO-, -COO-, -OCO-, -OCOO-, -S-CO-, -CO-S-, -CH=CH- or -C≡C- substitution, polymerizable groups or cycloalkyl or aryl groups having up to 20 carbon atoms, optionally halogenated, preferably F, or mono- or poly-substituted with polymerizable groups.

[0187] x 1 and x 2 Each is independently 0, 1, or 2.

[0188] y 1 and y 2 Each is independently 0, 1, 2, 3, or 4.

[0189] B 1 and B 2 Each is an aromatic or partially or fully saturated aliphatic six-membered ring, wherein one or more CH groups may be substituted with N atoms, and one or more non-adjacent CH2 groups may be substituted with O and / or S atoms.

[0190] W 1 and W 2 Each is independent of the others -Z 1 -A 1 -(Z 2 -A 2 ) m -R, and one of them is alternatively R 1 Or A 3 However, the two are not both H, or

[0191]

[0192] U 1 and U 2 Each of these elements is independently CH2, O, S, CO, or CS.

[0193] V 1 and V 2 Each is (CH2) independently of the others. n One to four non-adjacent CH2 groups may be substituted with O and / or S, and V 1 and V 2 One of them and in

[0194]

[0195] Z 1 and Z 2 Each of the following is independent of the others: -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-, -O-CH2-, -CH2-O-, -S-CH2-, -CH2-S-, -CF2-O-, -O-CF2-, -CF2-S-, -S-CF2-, -CH2-CH2-, -C F2-CH2-, -CH2-CF2-, -CF2-CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C C-, combinations of two of these groups, wherein there are no two O and / or S and / or N atoms directly bonded to each other, preferably -CH=CH-COO- or -COO-CH=CH-, or single bonds.

[0196] A 1 A 2 and A 3 Each is independently 1,4-phenylene, wherein one or two non-adjacent CH groups may be substituted with N; 1,4-cyclohexylene, wherein one or two non-adjacent CH2 groups may be substituted with O and / or S; 1,3-dioxacyclopentane-4,5-diyl, 1,4-cyclohexenyl, 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthyl-2,6-diyl, decahydronaphthyl-2,6-diyl or 1,2,3,4-tetrahydronaphthyl-2,6-diyl, wherein each of these groups may be mono- or poly-substituted with L, and additionally A 1 It's a single key.

[0197] L is a halogen atom, preferably F, CN, NO2, an alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, or alkoxycarbonyloxy group having 1 to 7 carbon atoms, wherein one or more H atoms may be replaced by F or Cl.

[0198] m is independently 0, 1, 2, or 3 in each case, and

[0199] R and R 1 Each of the following is independently H, F, Cl, Br, I, CN, SCN, SF5, a straight-chain or branched alkyl group having 1 or 3 to 25 carbon atoms, which may optionally be mono- or poly-substituted by F, Cl, Br, I or CN, and one or more of the non-adjacent CH2 groups may be substituted with -O-, -S-, -NH-, or -NR. 0The substitutions are -, -CO-, -COO-, -OCO-, -O-COO-, -S-CO-, -CO-S-, -CH=CH-, or -C≡C-, where there are no two O and / or S atoms directly bonded to each other, or polymerizable groups.

[0200] Especially preferred are chiral binaphthyl derivatives of formula A-VI-1.

[0201]

[0202] Especially those compounds selected from the following formulas A-VI-1a to A-VI-1c:

[0203]

[0204] Among them, B and Z 0 As defined with respect to equation A-IV, and Z 0 More preferably, it is -OCO- or a single bond, R 0 It is as defined with respect to formulas A-IV, or H or an alkyl group having 1 to 4 carbon atoms, and

[0205] b is 0, 1, or 2.

[0206] Furthermore, chiral binaphthyl derivatives of formula A-VI-2 are particularly preferred.

[0207]

[0208] Especially those compounds selected from the following formulas A-VI-2a to A-VI-2f:

[0209]

[0210] Where R 0 It is as defined with respect to equations A-VI, and X is H, F, Cl, CN, or R. 0 F is preferred.

[0211] In a particularly preferred embodiment, the chiral medium according to the invention comprises one or more compounds of formulas R-5011 and S-5011, shown in Table F below. In one embodiment, the medium contains R-5011. In another embodiment, the medium contains S-5011.

[0212] The LC dielectric according to the invention preferably and advantageously exhibits high reliability and high resistivity. The LC dielectric according to the invention also preferably and advantageously exhibits high voltage retention rate (VHR), see S. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); T. Jacob and U. Finkenzeller, “Merck Liquid Crystals - Physical Properties of Liquid Crystals”, 1997. The VHR of the LC dielectric according to the invention is preferably ≥ 75%, more preferably ≥ 85%, even more preferably ≥ 95%, and particularly preferably ≥ 98%. Unless otherwise described, VHR measurements are performed as described in T. Jacob, U. Finkenzeller, “Merck Liquid Crystals - Physical Properties of Liquid Crystals”, 1997.

[0213] According to the method of the present invention, a liquid crystal medium comprising one or more polymerizable mesocrystalline compounds in an amount of 4% by weight or less based on the total content of the medium is provided.

[0214] Preferably, based on the total content of the medium, the content of one or more polymerizable mesocrystalline compounds in the medium is 3% by weight or less, even more preferably 2% by weight or less, and particularly preferably 1.25% by weight or less.

[0215] Preferably, one or more polymerizable mesocrystalline compounds contain one, two or more acrylate groups and / or methacrylate groups.

[0216] In the medium according to the invention, one or more polymerizable, curable or hardenable compounds are preferably provided, preferably one or more photocurable monomers, which can advantageously serve as precursors for polymeric components in modulating materials and switching layers.

[0217] The reactive mesomorphs (RM) or mesomorphic monomers used contain mesomorphic groups and one or more polymerizable groups, i.e., functional groups suitable for polymerization.

[0218] In a particularly preferred embodiment, the polymerizable compound used contains only reactive mesomorphs, i.e., all reactive monomers are mesomorphous. Alternatively, RM may be provided in combination with one or more non-mesomorphous polymerizable compounds.

[0219] The reactive energy source (RM) can be monoreactive and / or direactive or multireactive. Preferably, the RM used is direactive or multireactive, particularly direactive. In one embodiment, one or more direactive RMs are used in combination with at least one monoreactive RM.

[0220] In a preferred embodiment of the present invention, the one or more polymerizable mesocrystalline compounds are selected from compounds of formula M.

[0221] R Ma -A M1 -(Z M1 -A M2 ) m1 -R Mb M

[0222] The definitions of each group are as follows:

[0223] R Ma and R Mb Each of the following is independently P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5, or a straight-chain or branched alkyl group having 1 to 25 carbon atoms, wherein one or more non-adjacent CH2 groups may also be independently arranged such that oxygen and / or sulfur atoms are not directly connected to each other via -C(R 0 )=C(R 00 )-、-C≡C-、-N((R 00 The hydrogen atoms can be replaced by -, -O-, -S-, -CO-, -CO-O-, -O-CO-, or -O-CO-O-, and one or more of these hydrogen atoms can also be replaced by F, Cl, Br, I, CN, P, or P-Sp-, with R being preferred. Ma and R Mb At least one of the groups is or contains a P or P-Sp- group;

[0224] Preferably

[0225] R Ma and R Mb Each is independently P, P-Sp-, H, halogen, SF5, NO2, alkyl, alkenyl or alkynyl, wherein R is preferred. Ma and R Mb At least one of the groups is or contains a P or P-Sp- group.

[0226] P is a polymerizable group.

[0227] Sp is a spacer group or a single bond.

[0228] A M1 and A M2Each is independently preferably an aromatic, heteroaromatic, alicyclic, or heterocyclic group having 4 to 25 ring atoms, preferably carbon atoms, and may also contain or contain a fused ring and may optionally be mono- or poly-substituted with L.

[0229] L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2、-C(=O)Y 1 -C(=O)R x -N(R) x 2. Optionally substituted silyl, optionally substituted aryl having 6 to 20 carbon atoms, or straight-chain or branched alkyl, alkoxy, alkyl carbonyl, alkoxy carbonyl, alkyl carbonyloxy, or alkoxy carbonyloxy or alkenyl or alkynyl having 2 to 25 carbon atoms, wherein one or more hydrogen atoms may also be substituted with F, Cl, P or P-Sp-, preferably with P, P-Sp-, H, OH, CH2OH, halogen, SF5, NO2, alkyl, alkenyl or alkynyl.

[0230] Y 1 It is a halogen, preferably F.

[0231] Z M1 is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-, -COO-, -OCO-CH=CH-, CR 0 R 00 Or a single key,

[0232] R 0 and R 00 Each is independently H or an alkyl group having 1 to 12 carbon atoms.

[0233] R xIt is P, P-Sp-, H, halogen, straight-chain, branched, or cycloalkyl having 1 to 25 carbon atoms, wherein one or more non-adjacent CH2 groups may be substituted with -O-, -S-, -CO-, -CO-O-, -O-CO-, or -O-CO-O- in such a way that oxygen and / or sulfur atoms are not directly connected to each other, and one or more hydrogen atoms may be substituted with F, Cl, P, or P-Sp-, optionally with substituted aryl or aryloxy groups having 6 to 40 carbon atoms, or optionally with substituted heteroaryl or heteroaryloxy groups having 2 to 40 carbon atoms.

[0234] m1 is 0, 1, 2, 3, or 4, and

[0235] n1 is 1, 2, 3, or 4.

[0236] Among them comes from the current R Ma R Mb The group consisting of at least one substituent of the substituent L, preferably one, two or three substituents, and more preferably one or two substituents being a P or P-Sp- group or containing at least one P or P-Sp- group.

[0237] R is particularly preferred. ma and R mb One or both of them are P or P-Sp- compounds of formula M.

[0238] Suitable and preferred RMs for the liquid crystal medium according to the present invention are selected, for example, from the following formula:

[0239]

[0240]

[0241]

[0242]

[0243] The definitions of each group are as follows:

[0244] P 1 To P 3 Each group is independently a polymerizable group, preferably having one of the definitions specified for P above and below, more preferably acrylate, methacrylate, fluoroacrylate, oxetane, ethylene oxy, or epoxy group.

[0245] Sp 1 To Sp 3 Each of the components is preferably a single bond or spacer group having one of the definitions of Sp given above and below, and more preferably -(CH2). P1 -、-(CH2) P1-O-、-(CH2) P1 -CO-O- or -(CH2) P1 -O-CO-O-, where p1 is an integer from 1 to 12, and where the bond between the latter group and the adjacent ring is via an oxygen atom, where P 1 -Sp 1 -、P 2 -Sp 2 -and P 3 -Sp 3 - One of the groups can also be R aa ,

[0246] R aa It is H, F, Cl, CN, or a straight-chain or branched alkyl group having 1 to 25 carbon atoms, wherein one or more non-adjacent CH2 groups may also be independently arranged such that oxygen and / or sulfur atoms are not directly connected to each other via C(R) 0 )=C(R 00 )-、-C≡C-、-N(R 0 The following hydrogen atoms can be replaced by F, Cl, CN, or P: -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-, -O-CO-O-, and one or more of these hydrogen atoms can also be replaced by F, Cl, CN, or P. 1 -Sp 1 - Alternatively, more preferably, straight-chain or branched groups having 1 to 12 carbon atoms, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, or alkylcarbonyloxy groups (wherein the alkenyl and alkynyl groups have at least two carbon atoms and the branched groups have at least three carbon atoms).

[0247] R 0 and R 00 Each occurrence may be the same or different, and each is independently H or an alkyl group having 1 to 12 carbon atoms.

[0248] R y and R z Each is independently H, F, CH3 or CF3.

[0249] Z 1 It is -O-, -CO-, -C(R) y R z - or -CF2CF2-,

[0250] Z 2 and Z 3 Each can be independently -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2-, or -(CH2). n - where n is 2, 3, or 4.

[0251] L is the same or different each time it appears and has the meaning given under the formula M above. It is preferably F, Cl, CN or a straight or branched chain having 1 to 12 carbon atoms, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy, preferably F.

[0252] L' and L" are each independently H, F, or Cl.

[0253] X 1 To X 3 They are independent of each other: -CO-O-, -O-CO-, or single bonds.

[0254] r is 0, 1, 2, 3, or 4.

[0255] s is 0, 1, 2, or 3.

[0256] t is 0, 1, or 2, and

[0257] x is 0 or 1.

[0258] Suitable polymerizable compounds are listed, for example, in Table G. Particularly preferred reactive mesomorphs are compounds of formula RM-A, RM-B and RM-C, as shown in Examples 1 and 3, respectively.

[0259] The polymerizable compound has at least one polymerizable group. The polymerizable group is preferably selected from CH2=CW. 1 -COO-、 , CH2=CW 2 -(O) k1 -, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, HO-CW 2 W 3 -、HS-CW 2 W 3 -、HW 2 N-, HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、Phe-CH=CH-、HOOC-、OCN-、W 1 It is H, Cl, CN, phenyl, or an alkyl group having 1 to 5 carbon atoms, especially H, Cl, or CH3; W 2 and W 3Each group is independently H or an alkyl group having 1 to 5 carbon atoms, especially H, methyl, ethyl, or n-propyl; Phe is 1,4-phenylene; and k1 and k2 are independently 0 or 1. The polymerizable or reactive groups are preferably selected from vinyl, acrylate, methacrylate, fluoroacrylate, oxetyl, or epoxy groups, with acrylate or methacrylate groups being particularly preferred.

[0260] In one embodiment, the medium includes a non-mesomorphic monomer other than one or more RMs. Preferably, one or more polymerizable compounds, a non-mesomorphic monomer or RM or both, are selected from acrylates, methacrylates, fluoroacrylates and vinyl acetate, wherein the composition more preferably further comprises one or more two-reactive and / or three-reactive polymerizable compounds, preferably selected from diacrylates, dimethacrylates, triacrylates and trimethacrylates.

[0261] In a preferred embodiment, the medium according to the invention comprises one or more non-mesocrystalline monoacrylates, particularly preferably one or more compounds selected from the following: methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, nonyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, and isobornyl acrylate.

[0262] Alternatively, the medium according to the invention preferably comprises one or more non-mesomorphous monomethacrylates, and more preferably one or more compounds selected from the following: methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, nonyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxybutyl methacrylate, isobornyl methacrylate, and 1-adamantane methacrylate.

[0263] It is particularly preferred to add at least one crosslinking agent to the medium, i.e., a polymerizable compound containing two or more polymerizable groups, wherein a di-reactive or multi-reactive RM is preferred.

[0264] In this respect, di-reactive and multi-reactive compounds can be used to form their own polymer network structures and / or to crosslink polymer chains that are substantially formed by polymerizing mono-reactive compounds.

[0265] Alternatively, conventional crosslinking agents known in the art may be used. It is also particularly preferred to provide di-reactive or multi-reactive acrylates and / or methacrylates. Particularly preferred compounds are selected from ethylene diacrylate, propylene diacrylate, butyl diacrylate, amyl diacrylate, hexyl diacrylate, ethylene glycol diacrylate, glycerol diacrylate, pentaerythritol tetraacrylate, dimethacrylate (also known as ethylene glycol dimethacrylate), propylene dimethacrylate, butyl dimethacrylate, amyl dimethacrylate, hexyl dimethacrylate, tripropylene glycol diacrylate, ethylene glycol dimethacrylate, glycerol dimethacrylate, trimethylpropane trimethacrylate, and pentaerythritol triacrylate.

[0266] The ratio of monoreactive monomers to direactive or multireactive monomers can be advantageously set and adjusted to influence the properties of the resulting polymeric components.

[0267] Suitable and conventionally used initiators, particularly photoinitiators (e.g., azo compounds or organic peroxides, such as Luperox-type initiators), can be added to the medium to facilitate the reaction. Furthermore, suitable polymerization conditions and suitable types and amounts of initiators are known in the art and described in the literature. When the medium includes a polymerization initiator, a photoinitiator is preferred.

[0268] For example, when using UV photopolymerization, a photoinitiator can be used, which decomposes under UV irradiation to generate free radicals or ions that initiate the polymerization reaction. For the polymerization of acrylate or methacrylate groups, a free radical photoinitiator is preferred. For the polymerization of vinyl, epoxy, or oxetane groups, a cationic photoinitiator is preferred. Thermal polymerization initiators can also be used, which decompose upon heating to generate free radicals or ions that initiate the polymerization reaction. Typical free radical photoinitiators are, for example, commercially available Irgacure®, such as Irgacure 651 (available from BASF, containing 2,2-dimethoxy-1,2-diphenylethyl-1-one), or Darocure® (Ciba Geigy AG, Basel, Switzerland). Typical cationic photoinitiators are, for example, UVI 6974 (Union Carbide). Other suitable photoinitiators include α-aminoketones (e.g., Irgacure 907), coumarins, phosphine oxides (e.g., Irgacure 2100), and acylphosphines (e.g., Irgacure 819).

[0269] In one particular embodiment, the added polymerization initiator, preferably a photoinitiator, comprises, and is preferably composed of, one or more mesocrystalline polymerization initiators, preferably one or more mesocrystalline photoinitiators, i.e., one or more reactive compounds that can initiate polymerization and are themselves anisotropic and mesocrystalline.

[0270] However, according to a particularly preferred embodiment, no polymerization initiator, especially a photoinitiator, is used. In some cases, this can improve VHR and reduce the tendency to generate ions in the switching layer. This helps to obtain and maintain modulation materials and light valves with good reliability and stability. Therefore, according to a preferred embodiment, no polymerization initiator is added to the liquid crystal medium used in the method according to the invention.

[0271] To maintain and achieve a good VHR (Vibration Harmony Rate), impurities in the polymerization reaction products are preferably kept to a minimum or substantially avoided. In particular, residual reactive species and charged contaminants are suitably and preferably kept to a minimum. For example, in the case of UV polymerization, in a preferred embodiment, light with a relatively long wavelength close to the visible spectrum is used, preferably advantageously in the range of 340 nm to 380 nm, and even more preferably in the range of 360 nm to 380 nm. In this way, undesirable photodegradation or decomposition of components of the LC medium, and especially one or more dichroic dyes, can be avoided or at least minimized. When using a photoinitiator, the irradiation wavelength and the photoinitiator can be suitably matched or adjusted.

[0272] In a preferred embodiment where no photoinitiator is used, the wavelength range of light can be set such that at least some of the polymerizable compounds undergo photoreaction and self-initiate polymerization, while simultaneously avoiding or at least minimizing the degradation or decomposition of non-reactive components of the LC medium, and particularly one or more dichroic dyes. The desired wavelength range can be obtained and set using conventional methods known in the art, such as the use of optical filters, particularly edge filters.

[0273] Surprisingly, the medium according to the invention has been found to be advantageously used for in-situ generation of polymeric structures by providing one or more polymerizable mesocrystalline compounds as described above and below within the medium. Furthermore, by suitably selecting one or more polymerizable mesocrystalline compounds along with one or more dichroic dyes and by setting and adjusting the wavelength of the light used in photopolymerization relative to the absorption characteristics of the dichroic dyes, an efficient and robust method can be provided to generate the desired polymer and polymeric products in the material, while simultaneously preserving the dichroic dyes and their properties. In one embodiment, the wavelength or wavelength spectrum of the irradiating light is selected such that overlap with the absorption bands of the dichroic dyes is minimized.

[0274] The polymerizable compound in the medium can be selected to obtain a stable system after polymerization, which can be stabilized, for example, in other processing steps such as heating steps, in which good VHR can be maintained.

[0275] Furthermore, according to the invention, only a relatively small amount of (a) polymerizable mesocrystalline compound is used, which can advantageously affect stability and minimize unwanted degradation.

[0276] According to the present invention, a modulated material comprising a polymeric component, particularly a polymeric network structure, is prepared using a medium, wherein the polymeric component is obtained by polymerizing one or more polymerizable compounds as described above and below, or may be obtained by polymerizing one or more polymerizable compounds as described above and below.

[0277] The polymer components provided can be used to stabilize one or more states or phases of LC media.

[0278] Preferably, the polymeric component is contained in the medium in an amount ranging from 0.1% to 4% by weight, more preferably from 0.5% to 1.5% by weight, based on the total content of the medium.

[0279] Polymer components can contribute to the desirable properties of available materials. For example, polymeric components can contribute to a significantly more stable haze state, particularly a multi-domain state, allowing this haze state to be maintained for a longer period of time without refreshing or reapplying voltage, particularly up to several days. It can also contribute to achieving rapid switching times, particularly as observed in the superior τ... off Switch time.

[0280] Furthermore, the polymeric components provided in materials containing CLC media according to the invention can advantageously influence scattering efficiency and appearance, for example, in terms of uniformity and viewing angle dependence. This can significantly reduce color artifacts that may occur at tilted viewing angles.

[0281] In a preferred embodiment, the modulation material comprises a liquid crystal medium and a polymeric component, wherein the polymeric component comprises a polymer network obtained by polymerization of reactive mesomorphs, wherein the reactive mesomorphs preferably contain at least one group selected from acrylate groups, particularly preferably selected from monoacrylate, diacrylate or triacrylate, vinyl ether, and epoxide groups. Compounds containing acrylate groups as used herein include acrylic monomers, methacrylate monomers, and mixtures of these monomers.

[0282] Polymerization can be carried out using conventional methods. Polymerization can be performed in one or more steps. In the method according to the invention, the polymerization of the polymerizable compound is achieved by exposure to photochemical radiation, wherein exposure to photochemical radiation means irradiation with light (such as UV light, visible light, or IR light), irradiation with X-rays or gamma rays, or irradiation with high-energy particles, such as ions or electrons. In a preferred embodiment, free radical polymerization is carried out.

[0283] For photopolymerization, UV light is preferred. UV light can also be used in combination with visible light, particularly violet or blue light. For example, light in the spectral range of 340 nm to 420 nm, preferably 360 nm to 405 nm, can be used. In an alternative embodiment, visible light alone, particularly in the range of 380 nm to 415 nm, such as visible light from a laser source, can also be used.

[0284] Polymerization can be carried out at a suitable temperature. In one embodiment, polymerization is carried out at a temperature below the clearing point of the mesocrystalline mixture. In an alternative embodiment, however, polymerization can also be carried out at or above the clearing point.

[0285] In this method, polymerization is carried out by light irradiation, specifically, by light irradiation, preferably UV light. As a source of photochemical radiation, a single UV lamp or a group of UV lamps can be used. Using high lamp power can reduce curing time. Another possible source of light radiation is laser, such as UV laser, visible laser, or IR laser.

[0286] In one embodiment, polymerization is carried out by adding one or more polymerizable compounds (preferably including a direactive compound and optionally a suitable photoinitiator) to a chiral liquid crystal host mixture doped with dyes, and by exposing the polymerizable compound to UV irradiation to polymerize it.

[0287] Preferably, polymerization is carried out in an electro-optic cell maintained in a predetermined state of the chiral liquid crystal host mixture. In a preferred embodiment, polymerization is carried out when the medium is in a vertical state, preferably using UV light polymerization, wherein an electric field is typically and preferably applied.

[0288] For photopolymerization of materials in layers, an exposure time of 30 s to 300 min, more preferably 1 min to 240 min, is preferred, and the preferred range is between 0.01 mW / cm². 2 Up to 100 mW / cm 2 More preferably 0.1 mW / cm 2 Up to 100 mW / cm 2 And even more preferably 0.5 mW / cm 2 Up to 75 mW / cm 2The irradiation intensity. In a particular embodiment, the preferred time period for photopolymerization, and especially the preferred UV exposure time range, is between 1 minute and 120 minutes, more preferably 5 minutes to 60 minutes, and especially 10 minutes to 30 minutes, wherein the UV light intensity preferably ranges from 1 mW / cm². 2 Up to 50 mW / cm 2 .

[0289] Photopolymerization can be carried out at room temperature, but in an alternative embodiment, photopolymerization at a high temperature is preferred.

[0290] Therefore, in one embodiment, the thermal preheating step is performed before photopolymerization to raise the temperature above ambient room temperature. In this case, it is preferable to set and maintain a temperature below the clearing point. This method allows polymerization to be carried out at higher temperatures, however, the medium having a nematic or chiral nematic phase.

[0291] According to the present invention, the medium contains one or more polychromatic dyes, particularly one or more dichromatic dyes, preferably in a content of 0.05% to 5% by weight, more preferably 0.1% to 2.5% by weight.

[0292] Preferably, the concentration of the dye is selected so that the method, and in particular photopolymerization, can be carried out effectively and efficiently, while ensuring the appropriate properties of the obtained modulated material, especially in terms of the desired color and darkening effect.

[0293] Dichroic dyes can be selected from, for example, azo dyes, anthraquinones, thiophene anthraquinones, methine compounds, methylimine compounds, anthocyanin compounds, naphthoquinones, tetraazines, pyrrole methylene dyes, malononitrile dyes, rylene (especially perylene and terylene), thiadiazole dyes, thienothiadiazole dyes, benzothiadiazoles, pyrrole methylene, Irgaphor Black X11 DC, and diketopyrrolopyrroles. Azo compounds are particularly preferred; anthraquinones; thiophene anthraquinones; benzothiadiazoles, especially as described in WO 2014 / 187529; diketopyrrolopyrroles, especially as described in WO 2015 / 090497; and rylene, especially as described in WO 2014 / 090373.

[0294] The liquid crystal medium used in this method preferably contains 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 different dichroic dyes, and particularly preferably two or three dichroic dyes.

[0295] In one embodiment, the liquid crystal medium contains at least three different dichroic dyes, preferably in an amount of 3% by weight or less, more preferably 1.5% by weight or less, based on the total contents of the medium.

[0296] In one embodiment, the absorption spectra of the dichroic dyes in the switching layer are preferably complementary to each other in a way that makes the eye perceive a black impression. Preferably, two or more, more preferably three or more, dichroic dyes of the liquid crystal medium according to the invention preferably cover most of the visible spectrum. Precise methods for preparing mixtures of dyes that appear black or gray to the eye are known in the art and described, for example, in M. Richter, *Einführung in dieFarbmetrik* [Introduction to Colorimetry], 2nd edition, 1981, ISBN 3-11-008209-8, Walter de Gruyter & Co.

[0297] In another implementation, different colors are set, such as red, green, or blue.

[0298] The color positions of the dye mixtures are described in the colorimetric section. For this purpose, the spectra of each dye are calculated considering the Lambert-Beer rule to obtain the overall spectrum and converted into brightness values ​​for the corresponding color positions and relevant illumination (e.g., for daylight luminescent material D65) according to colorimetric rules. The positions of the white points are fixed by each luminescent material, such as D65, and are referenced in tables, such as those in the above references. Different color positions can be set by varying the proportions of the various dyes.

[0299] According to a preferred embodiment, the medium and switching layer comprise one or more dichroic dyes that absorb light in the red and NIR regions, i.e., wavelengths in the range of 600 nm to 2000 nm, preferably 600 nm to 1800 nm, and particularly preferably 650 nm to 1300 nm.

[0300] Preferred dichroic dyes are selected from azo dyes, anthraquinones, thiophene anthraquinones, methine compounds, methylimine compounds, anthocyanin compounds, naphthoquinones, tetraazines, perylene, quaterrylene, higher naphthophenones, pyrrole methylene, thiadiazoles, benzothiadiazoles, dithiolene, (metallic) phthalocyanines, (metallic) naphthocyanines, and (metallic) porphyrins. Among these, azo dyes, thiophene anthraquinones, thiadiazoles, and benzothiadiazoles are particularly preferred.

[0301] In one embodiment, the dichroic dye provided in the medium and switching layer is preferably selected from the dye classes indicated in section 11.2.1 of B. Bahadur, Liquid Crystals - Applications and Uses, Vol. 3, 1992, World Scientific Publishing, and particularly preferably from the specific compounds provided in the tables of this invention.

[0302] The dye belongs to the category of dichroic dyes known in the art and has been described in the literature. Therefore, for example, anthraquinone dyes are described in EP 34832, EP 44893, EP 48583, EP 54217, EP 56492, EP 59036, GB 2065158, GB 2065695, GB 2081736, GB 2082196, GB 2094822, GB 2094825, JP-A 55-123673, DE3017877, DE 3040102, DE 3115147, DE 3115762, DE 3150803 and DE 3201120, naphthoquinone dyes are described in DE 3126108 and DE 3202761, and azo dyes are described in EP 43904, DE 3123519, WO 82 / 2054, GB2079770, JP-A 56-57850, JP-A 56-104984, US 4308161, US 4308162, US 4340973, T. Uchida, C. Shishido, H. Seki and M. Wada: Mol. Cryst. Liq. Cryst. 39, 39-52 (1977) and H. Seki, C. Shishido, S. Yasui and T. Uchida: Jpn. J. Appl. Phys. 21,191-192 (1982), and described in EP 60895, EP 68427 and WO 82 / 1191. Naphthalene-based phenylene dyes are as described in EP2166040, US 2011 / 0042651, EP 68427, EP 47027, EP 60895, DE 3110960 and EP 698649.

[0303] The following shows examples of preferred dichroic dyes that can be present in the medium and switching layer of the light valve.

[0304]

[0305]

[0306]

[0307]

[0308]

[0309]

[0310] The dye in the switching layer can provide variability in overall transmittance and can provide a colored or black appearance in an opaque state.

[0311] In a preferred embodiment, the switching layer of the device according to the invention comprises one or more quencher compounds. This is particularly preferred if the switching layer of the device according to the invention comprises one or more fluorescent dyes. For effective quenching, the quencher compound should be tailored to the corresponding dye system, particularly to the dyes in the dye combination that absorb at the longest wavelength. In a preferred embodiment of the switching layer according to the invention, any optionally added quencher compound is selected such that fluorescence in the visible portion of the spectrum is suppressed.

[0312] Preferably, the optical valve according to the present invention contains only one switching layer.

[0313] However, in an alternative implementation, more than one switching layer may also be provided, specifically two switching layers.

[0314] Preferably, the medium used according to the invention contains at least 5% by weight, more preferably at least 10% by weight, and even more preferably 15% by weight, of one or more mesocrystalline compounds selected from compounds of formulas I and II, based on the total contents of the medium. In one embodiment, the medium contains one or more compounds of formula I, preferably in an amount ranging from 5% by weight to 30% by weight based on the total contents of the medium. In some cases, it may be advantageous and preferred to include two, three, or more compounds of formula I in the medium.

[0315] Preferably, group A as defined in Formula I 11 express

[0316]

[0317] In one implementation scheme, n, as defined in Equation I, represents 0.

[0318] In a preferred embodiment, the one or more compounds of formula I are selected from compounds of formulas Ia, Ib and Ic, more preferably from compounds of formulas Ia and Ib.

[0319]

[0320] in

[0321] R 1 and R 2 Each group independently represents a group selected from: F, Cl, CF3, OCF3, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other, preferably selected from F, CF3, OCF3, a straight-chain alkyl or alkoxy group having 1 to 9 carbon atoms, or an alkenyl group having 2 to 9 carbon atoms, and

[0322] L is either the same or different each time it appears, and is either H or selected from F, Cl and Br, preferably halogens selected from F and Cl, and more preferably H or F each time it appears.

[0323] Particularly preferred is if the phenylene ring of compound I is substituted, in which case the substituent is F, and the external terminal group is R. 1 and R 2 It does not contain Cl.

[0324] In a particularly preferred embodiment, the one or more compounds of formula I are selected from compounds that do not contain Cl.

[0325] In a particularly preferred embodiment, the liquid crystal medium does not contain compounds containing Cl.

[0326] Furthermore, particularly preferably, ring A according to formula I 21 A 31 and A 41 At least one of them has at least one F substituent. Furthermore, particularly preferably, the ring A according to formula I... 21 A 31 and A 41 Together they have at least two F substituents.

[0327] In the medium according to the invention, the use of CN-containing compounds is preferably and advantageously limited to 75% by weight or less, more preferably 50% by weight or less, even more preferably 25% by weight or less, and particularly 15% by weight or less. In a particularly preferred embodiment, the use of CN-containing compounds is completely avoided.

[0328] The liquid crystal medium preferably contains a mesocrystalline compound, which is added in view of its beneficial properties, such as good VHR and favorable stability.

[0329] In one embodiment, the liquid crystal medium according to the invention comprises one or more compounds of Formula II, preferably in an amount ranging from 1% to 45% by weight, more preferably from 5% to 25% by weight, based on the total contents of the medium. In some cases, it may be advantageous and preferred to include two, three or more compounds of Formula I in the medium.

[0330] In another embodiment, the liquid crystal medium according to the invention comprises one or more compounds of formula III.

[0331]

[0332] Where R 5 and R 6 For example, R for equation II 3 Defined and L 4 and L 5 For example, L for type II 1 Defined.

[0333] The compound of Formula III is preferably used in the medium at a total concentration of 1% to 45% by weight, more preferably 5% to 25% by weight.

[0334] Preferably, the medium comprises one or more mesocrystalline compounds of formula I, optionally one or more photoinitiators, and one or more mesocrystalline compounds selected from the group consisting of compounds of formulas II and III.

[0335] Particularly preferably, the medium comprises one or more compounds of formula I, one or more compounds of formula II, and one or more compounds of formula III as described above.

[0336] Preferably, the liquid crystal medium according to the invention further comprises one or more compounds of formula IV.

[0337]

[0338] in

[0339] R 7 This indicates a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 7 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other.

[0340] i is 0, 1, or 2.

[0341] L 6 and L7 Each is independent of the other, being either H or F, and

[0342] X 1 It represents F, CF3, OCF3, or CN.

[0343] The compound of formula IV is preferably used in the medium at a total concentration of 1% to 45% by weight, more preferably 5% to 25% by weight.

[0344] Particularly preferably, the medium comprises one or more compounds of formula I, one or more compounds of formula II, one or more compounds of formula III and one or more compounds of formula IV as described above and below.

[0345] In another embodiment, the liquid crystal medium according to the invention comprises one or more compounds of formula V, preferably in an amount ranging from 1% to 15% by weight, more preferably from 5% to 10% by weight, based on the total contents of the medium.

[0346]

[0347] in

[0348] R 8 This indicates a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 7 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case one or more CH2 groups can be independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other.

[0349] X 2 It can be represented as F, CF3, OCF3 or CN, with CF3 being the most preferred.

[0350] In a particularly preferred embodiment, the one or more compounds of formula I are selected from compounds of formulas I-1 and I-2.

[0351]

[0352] in

[0353] R 1 and R 2 As defined for the above equation Ia, and

[0354] L appears in either the same or different forms, either H or F.

[0355] Optionally, the medium further comprises one or more compounds selected from those designated as CC-nV and CC-n-Vm as shown and explained in Table D, wherein preferably n and m are integers from 1 to 7 independently of each other, particularly at a concentration of 1% to 25% by weight.

[0356] Optionally, the medium according to the invention may contain other liquid crystal compounds to adjust physical properties. These compounds are known in the art. The concentration of these optionally additionally contained liquid crystal compounds in the medium according to the invention is preferably from 0% to 30% by weight, more preferably from 0.1% to 20% by weight, and most preferably from 1% to 15% by weight.

[0357] Preferably, the medium according to the invention comprises a compound of formula R-5011 as shown in Table F below.

[0358] The liquid crystal medium according to the invention may contain additional additives at typical concentrations. The total concentration of these additional components is in the range of 0% to 5%, preferably 0.1% to 4%, based on the total mixture. The concentration of each compound used is preferably in the range of 0.01% to 3%. The concentrations of these and similar additives are not considered herein with regard to the values ​​and ranges of the concentrations of the liquid crystal components and compounds in the liquid crystal medium. In particular, the medium may additionally contain conventional and suitable additives, such as stabilizers, antioxidants, free radical scavengers, chain transfer agents (e.g., thioethers), and / or plasticizers, preferably in amounts of 0.01% to 5% by weight. Stabilizers may be used to further stabilize the medium and modulated materials against degradation or oxidation, for example, degradation or oxidation due to thermal or photo-stress.

[0359] In this document, all concentrations are given as a weight percentage unless otherwise stated.

[0360] The liquid crystal medium according to the invention comprises a number of compounds, preferably 3 to 30, more preferably 4 to 20, and most preferably 4 to 16. These compounds are mixed using conventional methods. Typically, a smaller amount of the desired compound is dissolved in a larger amount of the compound. The completion of the dissolution process is particularly easy to observe if the temperature is higher than the clearing point of the compound used at a higher concentration. However, the medium may also be prepared by other conventional methods, such as using so-called premixes, which may be, for example, homologous mixtures or eutectic mixtures of compounds, or using so-called multi-bottle systems whose components are themselves ready-to-use mixtures.

[0361] The various mesocrystalline compounds or mixtures thereof described above and below are commercially available. As described in the literature (e.g., in standard works such as Houben-Weyl, Methoden der OrganischenChemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), these compounds are known or can be prepared by methods known per se, precisely under known and suitable reaction conditions. Variations known per se but not mentioned in more detail herein may also be used. The media according to the invention are prepared in their conventional manner. Generally, it is preferred to dissolve the components in each other at elevated temperatures. Suitable additives or substances may be added to improve the dielectric anisotropy, viscosity, and / or orientation of the liquid crystal phase.

[0362] According to the invention, the term "alkyl" preferably covers straight-chain and branched alkyl groups having 1 to 7 carbon atoms, especially straight-chain groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl. Groups having 2 to 5 carbon atoms are generally preferred.

[0363] The alkoxy group can be straight-chain or branched, and it is preferably straight-chain and has 1, 2, 3, 4, 5, 6 or 7 carbon atoms, and is therefore preferably methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.

[0364] The term "alkenyl" according to the invention preferably includes straight-chain and branched alkenyl groups having 2-7 carbon atoms, particularly straight-chain groups. Particularly preferred alkenyl groups are C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, C5-C7-4E-alkenyl, C6-C7-5E-alkenyl, and C7-6E-alkenyl, especially C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, and C5-C7-4E-alkenyl. Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, and 6-heptenyl. Groups with up to 5 carbon atoms are generally preferred.

[0365] Fluorinated alkyl or alkoxy groups preferably include CF3, OCF3, CFH2, OCFH2, CF2H, OCF2H, C2F5, OC2F5, CFHCF3, CFHCF2H, CFHCFH2, CH2CF3, CH2CF2H, CH2CFH2, CF2CF2H, CF2CFH2, OCFHCF3, OCFHCF2H, OCFHCFH2, OCH2CF3, OCH2CF2H, OCH2CFH2, OC F2CF2H, OCF2CFH2, C3F7 or OC3F7, especially CF3, OCF3, CF2H, OCF2H, C2F5, OC2F5, CFHCF3, CFHCF2H, CFHCFH2, CF2CF2H, CF2CFH2, OCFHCF3, OCFHCF2H, OCFHCFH2, OCF2CF2H, OCF2CFH2, C3F7 or OC3F7, particularly preferred is OCF3 or OCF2H. In preferred embodiments, the fluoroalkyl group comprises a straight-chain group having a terminal fluorine, namely fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl, and 7-fluoroheptyl. However, other positions of fluorine are not excluded.

[0366] Oxyalkyl groups preferably include those of formula C n H 2n+1 -O-(CH2) m The linear group, wherein n and m are each independently 1 to 6. Preferably, n = 1 and m is 1 to 6.

[0367] The oxane is preferably a straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0368] The preferred halogen is F or Cl, especially F.

[0369] If one of the above groups is an alkyl group in which one of the CH2 groups has been replaced by -CH=CH-, it can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 carbon atoms. Therefore, it is particularly vinyl, prop-1- or prop-2-enyl, but-1-, -2- or but-3-enyl, pent-1-, -2-, -3- or pent-4-enyl, hex-1-, -2-, -3-, -4- or hex-5-enyl, hep-1-, -2-, -3-, -4-, -5- or hep-6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or oct-7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or non-8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or dec-9-enyl.

[0370] If one of the above groups is an alkyl group in which one CH2 group has been substituted with -O- and another alkyl group in which one has been substituted with -CO-, then they are preferably adjacent. Therefore, they contain an acyloxy group (-CO-O-) or an oxycarbonyl group (-O-CO-). They are preferably straight-chain and have 2-6 carbon atoms.

[0371] Therefore, they are specifically acetoxy, propionyloxy, butyryloxy, valeryloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl, butyryloxymethyl, valeryloxymethyl, 2-acetoxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetoxypropyl, 3-propionyloxypropyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl, propionylcarbonyl, butoxycarbonyl, valeryloxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propionylcarbonylmethyl, butoxycarbonylmethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(propionyl)ethyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)propyl or 4-(methoxycarbonyl)butyl.

[0372] If one of the aforementioned groups is an alkyl group in which one of the CH2 groups has been replaced by an unsubstituted or substituted -CH=CH-, and the adjacent CH2 group has been replaced by an alkyl group with CO, CO-O, or O-CO, then it can be straight-chain or branched. It is preferably straight-chain and has 4 to 13 carbon atoms. Therefore, it is particularly acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl, or 9-methacryloyloxynonyl.

[0373] If one of the above groups is an alkyl or alkenyl group monosubstituted with CN or CF3, then the group is preferably straight-chain. The substitution of CN or CF3 can be at any position.

[0374] If one of the above groups is an alkyl or alkenyl group that is at least monosubstituted with a halogen, then the group is preferably straight-chain, and the halogen is preferably F or Cl, more preferably F. In the case of multiple substitution, the halogen is preferably F. The resulting groups also include perfluorinated groups. In the case of monosubstituted substitution, the fluorine or chlorine substituent can be at any desired position, but is preferably at the ω-position.

[0375] Compounds containing branched groups can occasionally be important because they exhibit better solubility in some conventional liquid crystal base materials. However, if they are optically active, they are particularly suitable as chiral dopants.

[0376] This type of branched group typically contains no more than one branch. Preferred branched groups are isopropyl, 2-butyl (=1-methylpropyl), isobutyl (=2-methylpropyl), 2-methylbutyl, isopentyl (=3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexyloxy, 1-methylhexyloxy, or 1-methylheptoxy.

[0377] If one of the above groups is an alkyl group in which two or more CH2 groups have been replaced by -O- and / or -CO-O-, it can be straight-chain or branched. It is preferably branched and has 3 to 12 carbon atoms. Therefore, it is particularly suitable for dicarboxymethyl, 2,2-dicarboxyethyl, 3,3-dicarboxypropyl, 4,4-dicarboxybutyl, 5,5-dicarboxypentyl, 6,6-dicarboxyhexyl, 7,7-dicarboxyheptyl, 8,8-dicarboxyoctyl, 9,9-dicarboxynonyl, 10,10-dicarboxydecyl, bis(methoxycarbonyl)methyl, 2,2-bis(methoxycarbonyl)ethyl, 3,3-bis(methoxycarbonyl)propyl, 4,4-bis(methoxycarbonyl)butyl, 5,5-bis(methoxycarbonyl)pentyl, 6,6-bis(methoxycarbonyl)hexyl, 7,7-bis(methoxycarbonyl)heptyl, 8,8-bis(methoxycarbonyl)octyl, bis(ethoxycarbonyl)methyl, 2,2-bis(ethoxycarbonyl)ethyl, 3,3-bis(ethoxycarbonyl)propyl, 4,4-bis(ethoxycarbonyl)butyl or 5,5-bis(ethoxycarbonyl)pentyl.

[0378] In another aspect of the invention, a switching layer is provided, which comprises a medium or modulation material according to the invention.

[0379] The switching layer according to the invention preferably has a thickness in the range of 2 µm to 50 µm, even more preferably 4 µm to 40 µm, and particularly 10 µm to 25 µm.

[0380] In the light valve, the switching layer is disposed between two substrates (specifically two transparent substrates).

[0381] The substrate may comprise, and preferably comprises, glass or polymer, particularly glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), COP (cyclic olefin polymer) or TAC (triacetyl cellulose).

[0382] In a particularly preferred embodiment, a glass substrate is used.

[0383] The final assembled light valve may further include one or more layers that block UV light.

[0384] Advantageously, the light valve can be produced by the convenient and efficient method described herein.

[0385] In the preparation method, a liquid crystal medium comprising one or more polymerizable mesocrystalline compounds is provided as a layer between two opposing transparent substrates, each having electrodes. Preferably, the electrodes are disposed above the inner surface of each substrate as conductive layers, more preferably, the conductive layers are disposed on passivation layers, even more preferably, between passivation layers, and optionally, an alignment layer in direct contact with the liquid crystal medium is further provided.

[0386] Subsequently, photopolymerization is specifically used to polymerize the one or more polymerizable mesocrystalline compounds. Preferably, the photopolymerization of the one or more polymerizable mesocrystalline compounds is carried out in the presence of an electric field in the layer, preferably an alternating electric field, wherein the layer preferably has a thickness in the range of 2 µm to 50 µm, more preferably 5 µm to 25 µm, and wherein the applied electric field preferably induces vertical alignment in the layer containing the liquid crystal medium.

[0387] In the methods described herein, photopolymerization is performed, preferably using UV light. In a particularly preferred embodiment, an electric field is applied at least temporarily during polymerization to induce the orientation of the medium, preferably vertical orientation. Applying a voltage during polymerization to set a predetermined orientation can advantageously influence the product properties of the switching layer and the light valve. For example, inducing vertical orientation during polymerization can help achieve a uniform, low-haze clarification state, and simultaneously obtain a uniform and appropriately strong haze in an opaque state.

[0388] The temperature during photopolymerization can be controlled, for example, in the range of 20°C to 100°C, preferably below the cleaning point.

[0389] In one preferred embodiment, reactive mesomorphism is initiated, while in another embodiment, a photoinitiator is used to trigger polymerization.

[0390] For photopolymerization of the material in the switching layer, an exposure time of 30 seconds to 240 minutes is preferably used, more preferably 1 minute to 120 minutes, and preferably 0.01 mW / cm² is used. 2 Up to 100 mW / cm 2 More preferably 0.1 mW / cm 2 Up to 50 mW / cm 2 Even more preferably 1 mW / cm 2 Up to 50 mW / cm 2 And specifically 2 mW / cm 2 Up to 20 mW / cm 2 Irradiation intensity within the range.

[0391] For polymerization, several parameters can be appropriately set or changed, such as the irradiation dose, the optional magnitude or frequency of the applied voltage or the electric field strength, and the amount of chiral dopant and dichroic dye in the medium.

[0392] Further processing can be performed after photopolymerization. Preferably, heat treatment is performed after the polymerization step. This heat treatment (i.e., exposure to an increased temperature relative to the previous polymerization step) can result in further curing or further conversion, or complete polymerization. This can be beneficial in terms of product properties and stability, especially because it minimizes the amount of residual unreacted monomers in the product.

[0393] Following polymerization, the optional heat treatment step is preferably performed for a period of 5 to 240 minutes, more preferably 10 to 120 minutes, and particularly 20 to 60 minutes. The heat treatment is preferably performed at a temperature ranging from 85°C to 200°C, more preferably 110°C to 190°C, and particularly 140°C to 180°C.

[0394] It is also possible to pre-treat the substrate used, such as surface treatment methods (e.g., UV-ozone treatment or plasma treatment), which can improve the alignment and wetting behavior over a larger area and help improve homogeneity and advantageously reduce unwanted haze in the clarified state.

[0395] The methods described herein can be advantageously used to generate light valves with favorable durability, low haze clarity, and good opacity, even when only a single switching layer is used in the device.

[0396] In this invention, and particularly in the following embodiments, the structure of the mesocrystalline compounds is indicated by abbreviations (also known as acronyms). In these acronyms, the chemical formulas are abbreviated using Tables A through C below. All C... n H 2n+1 C m H 2m+1 and C l H 2l+1 Or C n H 2n-1 C m H 2m-1 and C l H 2l-1 The groups represent straight-chain alkyl or alkenyl groups, preferably 1-E-alkenyl groups, each having n, m, and l carbon atoms, respectively. Table A lists the codes for the ring elements used in the core structure of the compounds, while Table B shows the linking groups. Table C gives the meaning of the codes for the left or right end groups. Acronyms consist of: the code for the ring element with optional linking groups, followed by the first hyphen and the code for the left end group, and the second hyphen and the code for the right end group. Table D shows the illustrative structure of the compounds and their various abbreviations.

[0397] Table A: Ring Elements

[0398]

[0399]

[0400] Table B: Linking Groups

[0401]

[0402] Table C: End groups

[0403]

[0404] Where n and m each represent integers, and the three dots “…” are placeholders for other abbreviations from this table.

[0405] The table below shows illustrative structures and their corresponding abbreviations. These are shown to explain the meaning of the abbreviation rules. Furthermore, they indicate preferred compounds.

[0406] Table D: Explanatory Structure

[0407]

[0408]

[0409]

[0410]

[0411]

[0412]

[0413]

[0414]

[0415]

[0416]

[0417]

[0418]

[0419]

[0420]

[0421]

[0422]

[0423]

[0424]

[0425]

[0426]

[0427]

[0428]

[0429]

[0430]

[0431]

[0432]

[0433]

[0434]

[0435]

[0436]

[0437]

[0438]

[0439]

[0440]

[0441]

[0442]

[0443]

[0444]

[0445]

[0446]

[0447]

[0448]

[0449]

[0450]

[0451]

[0452]

[0453]

[0454]

[0455]

[0456]

[0457]

[0458]

[0459]

[0460]

[0461]

[0462]

[0463]

[0464]

[0465]

[0466]

[0467]

[0468]

[0469]

[0470]

[0471]

[0472]

[0473]

[0474]

[0475]

[0476]

[0477]

[0478]

[0479]

[0480]

[0481]

[0482]

[0483]

[0484]

[0485]

[0486]

[0487]

[0488]

[0489]

[0490]

[0491]

[0492]

[0493] BCH-nF.FF

[0494]

[0495] BCH-7F.FF

[0496]

[0497] BCH-nF.F

[0498] Wherein n, m and l preferably represent 1 to 7 independently of each other.

[0499] The table below shows illustrative compounds that can be used as stabilizers in media according to the present invention.

[0500] Table E

[0501] Table E shows possible stabilizers that can be added to the LC media according to the invention, where n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups are not shown.

[0502]

[0503]

[0504]

[0505]

[0506]

[0507]

[0508] The LC medium preferably contains 0 to 10% by weight, particularly 1 ppm to 5% by weight, and especially preferably 1 ppm to 1% by weight of a stabilizer.

[0509] Table F below shows illustrative compounds that are preferably used as chiral dopants in mesocrystalline media according to the present invention.

[0510] Table F

[0511]

[0512]

[0513]

[0514]

[0515]

[0516]

[0517]

[0518]

[0519]

[0520]

[0521]

[0522]

[0523]

[0524]

[0525] In a preferred embodiment of the invention, the mesocrystalline medium comprises one or more compounds selected from those shown in Table F.

[0526] The mesocrystalline medium according to the invention preferably comprises two or more, more preferably four or more, compounds selected from the compounds shown in Tables D to F above.

[0527] In one embodiment, the LC medium according to the invention preferably contains three or more, more preferably five or more compounds shown in Table D.

[0528] Table G

[0529] Table G summarizes the compounds used in the embodiments of the present invention in the LC medium, preferably as reactive mesocrystalline compounds. Preferably, one initiator or a mixture of two or more initiators is added for polymerization. The initiator or initiator mixture is preferably added in an amount from 0.001% to 2% by weight, based on the mixture. Suitable initiators are, for example, Irgacure® 651 (from BASF).

[0530]

[0531]

[0532]

[0533]

[0534]

[0535]

[0536]

[0537]

[0538]

[0539]

[0540]

[0541]

[0542]

[0543]

[0544]

[0545] In a preferred embodiment of the invention, the mesocrystalline medium comprises one or more compounds selected from the group consisting of compounds from Table G.

[0546] The liquid crystal medium according to the invention preferably comprises four or more compounds, more preferably six or more compounds, even more preferably seven or more compounds, and particularly preferably eight or more compounds selected from the group consisting of compounds in Table D, and preferably three or more compounds selected from different formulas in the group consisting of formulas in Table D. The medium particularly preferably further comprises one, two or more compounds selected from the group consisting of formulas in Table E. Even more preferably, the medium further comprises one, two or more compounds selected from the group consisting of formulas in Table G.

[0547] The following embodiments are merely illustrative of the invention and should not be construed as limiting the scope of the invention in any way. In view of the invention, the embodiments, modifications, or other equivalents thereof will become apparent to those skilled in the art.

[0548] However, the physical properties and composition shown below illustrate what characteristics can be achieved and to what extent they can be modified. Therefore, it is essential to fully define the preferred combinations of particularly different characteristics that can be achieved.

[0549] Example

[0550] In an embodiment,

[0551] V o The threshold voltage at 20°C, capacitance [V],

[0552] n e This indicates the unusual refractive index at 20°C and 589 nm.

[0553] n o This represents the ordinary refractive index at 20°C and 589 nm.

[0554] Δn represents the optical anisotropy at 20℃ and 589nm.

[0555] ε This represents the dielectric constant parallel to the director at 20℃ and 1kHz.

[0556] ε ⊥ This represents the dielectric constant perpendicular to the director at 20℃ and 1kHz.

[0557] Δε represents the dielectric anisotropy at 20℃ and 1kHz.

[0558] cl.p., T(N,I) represents the clearing point [°C].

[0559] 1 represents the rotational viscosity [mPa] measured at 20°C using a rotational method in a magnetic field. s],

[0560] K1 represents the elastic constant, and the deformation [pN] at 20℃.

[0561] K2 represents the elastic constant, the "torsional" deformation at 20℃ [pN].

[0562] K3 represents the elastic constant, the bending deformation at 20℃ [pN].

[0563] Unless otherwise explicitly stated, the term "threshold voltage" in this invention refers to a capacitive threshold (V0). In embodiments, as is generally the case, the optical threshold may also be for 10% relative contrast (V0). 10 (This is what was pointed out.)

[0564] Liquid crystal mixtures and composite systems are realized by the compositions and properties given below. Their properties and optical properties are investigated.

[0565] Refer to Example 1

[0566] Liquid crystal base mixture B-1 was prepared and characterized regarding its general physical properties, and it has the composition and properties indicated in the table below.

[0567]

[0568] Refer to Example 2

[0569] The liquid crystal base mixture B-2 was prepared and characterized regarding its general physical properties, and it has the composition and properties indicated in the table below.

[0570]

[0571] Cholesterol-type mixture C-2 was prepared by mixing 99.00% of mixture B-2 with 1.00% of chiral dopant R-5011 purchased from Merck KgaA, Darmstadt, Germany.

[0572] Refer to Example 3

[0573] The liquid crystal base mixture B-3 was prepared and characterized regarding its general physical properties, and it has the composition and properties indicated in the table below.

[0574]

[0575] Cholesterol-type mixture C-3 was prepared by mixing 99.54% of mixture B-3 with 0.46% of chiral dopant R-5011 purchased from Merck KgaA, Darmstadt, Germany.

[0576] Comparative Example 1

[0577] The cholesterol-type mixture CC-1 was prepared by mixing 91.125% of mixture B-1 as described in Reference Example 1 above with 6.493% of chiral dopant CB15 purchased from Merck KgaA, Darmstadt, 2.370% of ethylene glycol dimethacrylate, 0.010% of polydimethylsiloxane and 0.002% of 2,6-di-tert-butyl-4-methylphenol.

[0578] The mixture CC-1 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054, planar, TN-rubbed, purchased from Japan Synthetic Rubber), wherein the cell gap was 25 µm.

[0579] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0580] The obtained box is opaque, white in appearance, and has a haze of 96%, which was measured according to ASTM 1003-92 using a spectrophotometer (Lambda 1050, Perkin Elmer) and a 150 mm Ulbricht sphere. The obtained box is optically clear at 50 V with a haze of 5.2% and a τ of 99 ms at 20 °C. on and τ at 32 ms off At 0°C, the box exhibits a τ of 750 ms. on and τ at 134 ms off .

[0581] Example 1

[0582] Mixture M-1, a dye-doped compound, was prepared by mixing 99.50% of the cholesterol-type mixture C-2 described in Reference Example 2 with 0.50% of Irgaphor Black X11 DC (from BASF). Mixture M-1-1 was prepared by mixing 99.225% of mixture M-1 with 0.75% of compound RM-A.

[0583]

[0584] and 0.025% of the photoinitiator Irgacure ® It is prepared by mixing 651 (hereinafter abbreviated as IRG-651).

[0585] Purchased from Ciba, Switzerland.

[0586] The mixture M-1-1 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054 from Japan Synthetic Rubber, planar, TN-rubbed), wherein the cell gap was 25 µm.

[0587] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0588] The obtained cell exhibits 67% haze in its opaque state. The obtained cell is optically clear at 100 V with 2.0% haze and has a τ of 65 ms at 20 °C. on and τ at 2.8 ms off At 0°C, the box has a τ of 236 ms. on and τ of 10.0 ms off .

[0589] Example 2

[0590] The mixture M-2 of doped dyes is made by adding 0.118% of compound DD-1.

[0591]

[0592] 0.142% of compound DD-2

[0593]

[0594] and 0.242% of compound DD-3

[0595]

[0596] It is prepared by adding it to the cholesterol-type mixture C-2 described in Reference Example 2 above.

[0597] Mixture M-2-1 was prepared by mixing 99.225% of mixture M-2 with 0.750% of compound of formula RM-A as described in Example 1 above and 0.025% of IRG-651 as described in Example 1 above.

[0598] The mixture M-2-1 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054 from Japan Synthetic Rubber, planar, TN-rubbed), wherein the cell gap was 25 µm.

[0599] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0600] The obtained box is opaque, with a black appearance and 84% haze. It exhibits optical clarity at 100 V with 2.5% haze and a τ of 101 ms at 20°C. on and τ at 2.8 ms off At 0°C, the box has a τ of 368 ms. on and τ of 9.8 ms off .

[0601] Example 3

[0602] Mixture M-3 is prepared by combining 98.713% of mixture M-2 as prepared in Example 2 above with 0.037% of IRG-651 and 0.625% of compound of formula RM-B.

[0603]

[0604] and 0.625% of the RM-C compound

[0605]

[0606] Prepared by mixing.

[0607] Mixture M-3 was processed and measured as described for mixture M-2-1 in Example 2 above. The resulting box exhibited favorable electro-optical properties in both opaque and optically transparent states.

[0608] Example 4

[0609] Mixture M-4 was prepared by adding 0.750% of compound RM-A as described in Example 1 above, 0.025% of IRG-651, 0.109% of compound DD-1 as described in Example 2 above, 0.132% of compound DD-2 as described in Example 2 above, and 0.254% of compound DD-3 as described in Example 2 above to cholesterol-type mixture C-3 as described in Reference Example 3 above.

[0610] The mixture M-4 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054 from Japan Synthetic Rubber, planar, TN-rubbed), wherein the cell gap was 25 µm.

[0611] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0612] The obtained box is opaque, with a black appearance and 93% haze. It exhibits optical clarity at 50 V with 5.0% haze and a τ of 68 ms at 20°C. on and τ at 2.8 ms off At 0°C, the box has a τ of 126 ms. on and τ of 9.0 ms off .

[0613] Example 5

[0614] Mixture M-5 was prepared by mixing 98.298% of mixture B-3 as described in Reference Example 3 above with 0.458% of chiral dopant R-5011, 0.750% of compound RM-A as described in Example 1 above, 0.109% of compound DD-1 as described in Example 2 above, 0.132% of compound DD-2 as described in Example 2 above, and 0.253% of compound DD-3 as described in Example 2 above.

[0615] The mixture M-5 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054 from Japan Synthetic Rubber, planar, TN-rubbed), wherein the cell gap was 25 µm.

[0616] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0617] The obtained box is opaque, with a black appearance and 83% haze. It exhibits optical clarity at 50 V with 1.5% haze and a τ of 56 ms at 20°C. on and τ at 7.7 ms off At 0°C, the box has a τ of 116 ms. on and τ at 25 ms off .

[0618] Example 6

[0619] Mixture M-6 is prepared by combining 0.458% chiral dopant R-5011, 0.750% of compound RM-A as described in Example 1 above, 0.025% of IRG-651, and 0.123% of compound DD-4.

[0620]

[0621] A mixture of 0.337% of compounds of formula DD-5 and DD-6,

[0622]

[0623] 0.117% of compound DD-7

[0624]

[0625] and 0.173% of compound DD-8

[0626]

[0627] It is prepared by adding it to mixture B-3 as described in Reference Example 3 above.

[0628] The mixture M-6 was filled into an electro-optic cell having a glass substrate (0.7 mm alkali-free glass) with ITO electrodes and a polyimide alignment layer (AL-1054 from Japan Synthetic Rubber, planar, TN-rubbed), wherein the cell gap was 25 µm.

[0629] The box was preheated to 40°C. It was then subjected to UV light (facial tanner, intensity cutoff below 340nm, 3 mW / cm²). 2 Polymerization was carried out at 40°C for 60 minutes under light intensity irradiation, while a voltage (100 V rms) was applied simultaneously.

[0630] The obtained box is opaque, with a black appearance and 94% haze. It exhibits optical clarity at 100 V with 7.6% haze and a τ of 15 ms at 20°C. on and τ at 3.3 ms off At 0°C, the box has a τ of 42 ms. on and τ of 9.8 ms off .

[0631] Example 7

[0632] Mixture M-7 was prepared by adding 0.037% IRG-651, 0.625% of compound RM-B as described in Example 3 above, 0.625% of compound RM-C as described in Example 3 above, 0.109% of compound DD-1 as described in Example 2 above, 0.132% of compound DD-2 as described in Example 2 above, and 0.254% of compound DD-3 as described in Example 2 above to mixture C-3 as described in Reference Example 3 above.

[0633] Mixture M-7 was processed and measured as described for mixture M-2-1 in Example 2 above. The resulting box exhibited favorable electro-optical properties in both opaque and optically transparent states.

Claims

1. A method for fabricating a portable device including a light valve, the light valve being operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, the method comprising: (i) A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, at least three different dichroic dyes, and one or more polymerizable mesocrystalline compounds is provided as a layer inserted between two opposing transparent substrates, each substrate having an electrode, wherein the absorption spectra of the dichroic dyes are complementary to each other in such a way that the eye perceives a black impression, wherein the at least three different dichroic dyes are selected from azo dyes, thiophene anthraquinones, thiadiazoles, and benzothiadiazoles, and the dyes are present in the medium at a concentration of 0.05% by weight to 5% by weight. The liquid crystal medium has a clearing point of 70°C or higher, and The one or more polymerizable mesocrystalline compounds are contained in the medium in an amount of 4% by weight or less based on the total contents of the medium, and (ii) Using photopolymerization to polymerize the one or more polymerizable mesocrystalline compounds in the layer. The optical valve is applied to this portable device. The liquid crystal medium contains one or more mesocrystalline compounds selected from compounds of formulas I and II. in R 1 and R 2 The groups, independently of each other, are selected from the following groups: F, Cl, CF3, OCF3, and straight-chain or branched alkyl or alkoxy groups having 1 to 15 carbon atoms, or straight-chain or branched alkenyl groups having 2 to 15 carbon atoms, which are unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. A 11 express n represents 0 or 1, and A 21 A 31 and A 41 Representing each other independently Wherein L appears each time as a halogen selected from F, Cl, and Br, and R 3 and R 4 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. L 1 L 2 and L 3 H or F can be represented independently of each other. The liquid crystal medium must contain one or more compounds of formula II, in an amount of 5% to 45% by weight. The liquid crystal medium contains one or more CPU-nF compounds and one or more CCGU-nF compounds. Where n represents 1 to 7.

2. The method of claim 1, wherein the photopolymerization of the one or more polymerizable mesocrystalline compounds is carried out in the presence of an electric field in the layer.

3. The method of claim 1 or 2, wherein the one or more polymerizable mesocrystalline compounds comprise one, two or more acrylate and / or methacrylate groups.

4. The method according to claim 1 or 2, wherein the photopolymerization uses a concentration of 0.1 mW / cm². 2 Up to 100 mW / cm 2 The intensity of the light ranges from 1 minute to 240 minutes over a period of time.

5. A portable device including a light valve, the light valve being operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, wherein the portable device including the light valve is obtained by performing the method according to any one of claims 1 to 4 or can be obtained by performing the method.

6. A portable device including a light valve, the light valve being operable in an optically transparent state and an opaque state and electrically switchable between the optically transparent state and the opaque state, and the light valve including a switching layer containing a material comprising: - A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, and at least three different dichroic dyes, wherein the absorption spectra of the dichroic dyes are complementary to each other in a manner that allows the eye to perceive a black image, wherein the liquid crystal medium has a clearing point of 70°C or higher, and the at least three different dichroic dyes are selected from azo dyes, thiophene anthraquinones, thiadiazoles, and benzothiadiazoles, wherein the dyes are present in the medium at a concentration of 0.05% to 5% by weight. - A polymeric component comprising one or more polymeric structures obtained or obtainable by polymerization of one or more polymerizable mesocrystalline compounds, wherein the polymeric component is contained in the material in an amount of 4% by weight or less based on the total contents of the material. in, The optical valve has less than 5% haze and greater than 45% light transmittance in an optically transparent state, and greater than 65% haze and less than 35% light transmittance in an opaque state. The liquid crystal medium contains one or more mesocrystalline compounds selected from compounds of formulas I and II. in R 1 and R 2 The groups, independently of each other, are selected from the following groups: F, Cl, CF3, OCF3, and straight-chain or branched alkyl or alkoxy groups having 1 to 15 carbon atoms, or straight-chain or branched alkenyl groups having 2 to 15 carbon atoms, which are unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. A 11 express n represents 0 or 1, and A 21 A 31 and A 41 Representing each other independently Wherein L appears each time as a halogen selected from F, Cl, and Br, and R 3 and R 4 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. L 1 L 2 and L 3 H or F can be represented independently of each other. The liquid crystal medium must contain one or more compounds of formula II, in an amount of 5% to 45% by weight. The liquid crystal medium contains one or more CPU-nF compounds and one or more CCGU-nF compounds. Where n represents 1 to 7.

7. The portable device including a light valve according to claim 5 or 6, wherein the liquid crystal medium displays a pitch of 0.55µm or greater in an opaque state.

8. A liquid crystal medium for use in the method according to any one of claims 1 to 4, comprising... - One or more polymerizable mesocrystalline compounds, wherein the amount based on the total contents of the medium is 4% by weight or less. -One or more mesocrystalline compounds, - One or more chiral compounds, and - At least three different dichroic dyes, wherein the absorption spectra of the dichroic dyes are complementary to each other in a manner that makes the eye perceive black, said at least three different dichroic dyes are selected from azo dyes, thiophene anthraquinones, thiadiazoles, and benzothiadiazoles, said dyes being present in the medium at a concentration of 0.05% to 5% by weight. The liquid crystal medium contains one or more mesocrystalline compounds selected from compounds of formulas I and II. in R 1 and R 2 The groups, independently of each other, are selected from the following groups: F, Cl, CF3, OCF3, and straight-chain or branched alkyl or alkoxy groups having 1 to 15 carbon atoms, or straight-chain or branched alkenyl groups having 2 to 15 carbon atoms, which are unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. A 11 express n represents 0 or 1, and A 21 A 31 and A 41 Representing each other independently Wherein L appears each time as a halogen selected from F, Cl, and Br, and R 3 and R 4 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. L 1 L 2 and L 3 H or F can be represented independently of each other. The liquid crystal medium contains one or more mesocrystalline compounds selected from compounds of formulas III, IV, and V. in R 5 and R 6 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. L 4 L 5 L 6 and L 7 H or F can be represented independently of each other. R 7 and R 8 Each of the following independently represents a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. i is 0, 1 or 2, and X 1 and X 2 Each can be represented independently as F, CF3, OCF3, or CN. The liquid crystal medium must contain one or more compounds of formula II, in an amount of 5% to 45% by weight. The liquid crystal medium contains one or more CPU-nF compounds and one or more CCGU-nF compounds. Where n represents 1 to 7.

9. The liquid crystal medium of claim 8, wherein the liquid crystal medium exhibits a positive dielectric anisotropy Δε and an optical anisotropy Δn of 0.13 or higher measured at 20°C and 589 nm, and The one or more chiral compounds contained in the liquid crystal medium have a diameter of 5 µm. -1 Or an absolute value of a higher helical torsion force.

10. The liquid crystal medium of claim 8 or 9, wherein the liquid crystal medium comprises at least three different dichroic dyes in an amount of 3% by weight or less based on the total contents of the medium.

11. The liquid crystal medium according to claim 8 or 9, wherein the liquid crystal medium comprises at least one di-reactive or multi-reactive polymerizable mesocrystalline compound.

12. A modulation material for use in a portable device comprising a light valve according to any one of claims 5 to 7, comprising: - A liquid crystal medium comprising one or more mesocrystalline compounds, one or more chiral compounds, and at least three different dichroic dyes, wherein the absorption spectra of the dichroic dyes are complementary to each other in a manner that allows the eye to perceive a black image, wherein the liquid crystal medium has a clearing point of 70°C or higher, and the at least three different dichroic dyes are selected from azo dyes, thiophene anthraquinones, thiadiazoles, and benzothiadiazoles, wherein the dyes are present in the medium at a concentration of 0.05% to 5% by weight. - A polymeric component comprising one or more polymeric structures obtained or obtainable by polymerization of one or more polymerizable mesocrystalline compounds, wherein the polymeric component is contained in the material in an amount of 4% by weight or less based on the total contents of the material. The liquid crystal medium contains one or more mesocrystalline compounds selected from compounds of formulas I and II. in R 1 and R 2 The groups, independently of each other, are selected from the following groups: F, Cl, CF3, OCF3, and straight-chain or branched alkyl or alkoxy groups having 1 to 15 carbon atoms, or straight-chain or branched alkenyl groups having 2 to 15 carbon atoms, which are unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with halogens, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. A 11 express n represents 0 or 1, and A 21 A 31 and A 41 Representing each other independently Wherein L appears each time as a halogen selected from F, Cl, and Br, and R 3 and R 4 Each group independently represents a group selected from the following: F, CF3, OCF3, CN, and a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, or a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted with CN or CF3, or monosubstituted or polysubstituted with a halogen, and in each case, one or more CH2 groups are independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, or -C≡C- in such a manner that the oxygen atoms are not directly connected to each other. L 1 L 2 and L 3 H or F can be represented independently of each other. The liquid crystal medium must contain one or more compounds of formula II, in an amount of 5% to 45% by weight. The liquid crystal medium contains one or more CPU-nF compounds and one or more CCGU-nF compounds. Where n represents 1 to 7.

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