Liquid crystal medium and PNLC light modulation element

Abstract

A liquid crystal medium and a PNLC light modulation element are provided. The present invention relates to a cholesteric liquid crystal (LC) medium for polymer network liquid crystal (PNLC) light modulation elements, to a method for their manufacture, and to the use of such a cholesteric LC medium in PNLC light modulation elements. The present invention further relates to such PNLC light modulation elements, to methods for their manufacture, to the use of such light modulation elements in optical or electro-optical devices, in particular LC displays, and to optical or electro-optical devices comprising such light modulation elements according to the invention.

Description

[Technical Field]

[0001] The present invention relates to a cholesteric liquid crystal (LC) medium for polymer network liquid crystal (PNLC) light modulation elements, to a method for their manufacture, and to the use of such a cholesteric LC medium in PNLC light modulation elements. The invention further relates to such PNLC light modulation elements, to methods for their manufacture, to the use of such light modulation elements in optical or electro-optical devices, in particular LC displays, and to optical or electro-optical devices comprising such light modulation elements according to the invention. [Background technology]

[0002] Switchable waveguides are transparent displays that use liquid crystal devices. When the liquid crystal cell is edge-lit, light can undergo total internal reflection at the boundaries of the LC cell.

[0003] As long as the refractive index of the LC host is higher than that of the glass substrate in the normal alignment state, the light path is unimpeded. When the chiral liquid crystal cell is switched, focal conic domains are formed, and this large change in apparent refractive index leads to haze and subsequent light outcoupling from the LC cell.

[0004] In this case, the helical pitch is required to be on the order of microns so that the reflection band is within the infrared spectrum. This eliminates any color effects in the LC cell, and the application of liquid crystal windows has been reported in WO 2017 / 041872 (Patent Document 1). However, these systems have a long switch-off time (t off ) and is not applicable to display applications where high-speed switching is required.

[0005] Additionally, WO 2018 / 215393 (Patent Document 2) suggested a polymer network system for dynamic scattering with a moderate haze value of 44%. Thus, there remains a great need to develop systems for display applications with high haze values ​​while maintaining fast switching speeds for these devices. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2017 / 041872 [Patent Document 2] International Publication No. 2018 / 215393 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above-mentioned problems, the present invention is based on the object of providing new and suitable materials, in particular cholesteric LC media, for use in PNLC light modulation elements whose helical pitch is of the order of microns and whose reflection band lies in the infrared spectrum, which do not have the above-mentioned drawbacks or exhibit them to a reduced extent. Other objects of the present invention will be immediately apparent to those skilled in the art from the following description.

[0008] Surprisingly, the inventors have found that by means of the invention as defined in claim 1 one or more of the objects defined above and below can be achieved. [Means for solving the problem]

[0009] The present invention therefore provides a cholesteric LC medium for a PNLC light modulator, comprising: A) one or more polymerizable compounds in an amount of 2% by weight or more and 10% by weight or less, provided that at least one of the compounds is a compound of formula I;

[0010] [ka]

[0011] During the ceremony, Ar is a group selected from the following formulae:

[0012] [ka]

[0013] [ka]

[0014] the group may be substituted with one or more groups L; L is, in each occurrence, identically or differently, F, Cl, CN, P-Sp- or a linear, branched or cyclic alkyl having 1 to 25 C atoms, provided that one or more non-adjacent CH groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, respectively, and provided that one or more H atoms may be replaced by F or Cl, P 11 and P 12 each independently represents a polymerizable group, Sp 11 and Sp 12 each independently represents one or more groups P 11 or P 12 represents a spacer group which may be substituted with B) one or more non-polymerizable mesogenic or liquid crystal compounds, and C) one or more chiral compounds; The present invention relates to a cholesteric LC medium comprising:

[0015] The liquid crystal component B) of the cholesteric LC medium according to the invention, hereinafter also referred to as "LC host mixture", preferably comprises one or more, preferably at least two, mesogenic or LC compounds selected from low molecular weight compounds that are non-polymerizable.

[0016] The invention further relates to a cholesteric LC medium or a PNLC light modulator element as described above and below, in which a compound of formula I or a polymerizable compound of component A) has been polymerized.

[0017] The present invention further relates to a method for preparing a cholesteric LC medium as described above and below, comprising the steps of: one or more mesogenic or LC compounds or LC host mixtures or LC components B) as described above and below, a polymerizable component A) comprising, and preferably consisting of, one or more polymerizable compounds, at least one of which is a compound of formula I, in an amount of 2% to 10%; and a chiral component C) comprising one or more chiral compounds, Optionally with further LC compounds and / or additives The present invention relates to a method comprising the step of mixing.

[0018] The invention further relates to the use of a cholesteric LC medium as described above and below in a light modulation element based on the PNLC mode.

[0019] The present invention further relates to a PNLC light modulation element comprising a pair of opposing substrates, an in-plane electrode structure and a cholesteric LC medium located between said substrates, characterized in that the light modulation element comprises a polymer network obtainable from the cholesteric LC medium according to the invention by exposing the cholesteric LC medium to actinic radiation which induces photopolymerization of polymerizable compounds in the cholesteric LC medium.

[0020] The invention further relates to a PNLC light modulating element comprising a polymer network obtainable by polymerization of one or more compounds of formula I or polymerizable components A) as described above and below.

[0021] The present invention further relates to the use of a PNLC light-modulating element as described above and below in an optical or electro-optical device, and thus also to such an optical or electro-optical device comprising a PNLC light-modulating element as described above and below.

[0022] The present invention further relates to a method for manufacturing a PNLC light modulation element as described above and below, in which a cholesteric LC medium as described above and below is introduced into an LC cell having two substrates and an electrode structure as described above and below, with the proviso that the polymerizable compound of the cholesteric LC medium is polymerized.

[0023] The use of a cholesteric LC medium according to the invention in a PNLC light modulator preferably simultaneously satisfies the requirements as set out above and below, among others.

[0024] In particular, the PNLC light modulation element according to the present invention preferably High haze, Favorably fast response times, especially favorably fast switch-off times (t off ), and -Preferred low voltage required for address In addition, the PNLC light modulation elements are interchangeable and can be manufactured by commonly known methods for mass production. DETAILED DESCRIPTION OF THE INVENTION

[0025] <Terms and definitions>

[0026] Unless expressly stated otherwise, the following meanings apply above and below:

[0027] The terms "liquid crystal," "meso-type compound," or "mesogenic compound" (also called "mesogen" for short) refer to compounds that can exist as a mesophase (nematic, smectic, etc.), in particular as an LC phase, under appropriate conditions of temperature, pressure, and concentration. Non-hydrophilic mesogenic compounds contain, for example, one or more calamitic, banana-shaped, or discotic mesogenic groups.

[0028] The term "mesogenic group" refers to a group capable of inducing liquid crystal phase (or mesophase) behavior. Compounds containing mesogenic groups do not necessarily exhibit liquid crystal mesophases by themselves; they may exhibit liquid crystal mesophases only in mixtures with other compounds, or when the mesogenic compound or material, or a mixture thereof, is polymerized. This includes low molecular weight non-reactive liquid crystal compounds, reactive or polymerizable liquid crystal compounds, and liquid crystal polymers. For simplicity, the term "liquid crystal" will be used hereinafter for both mesogens and liquid crystal materials.

[0029] Calamitic mesogenic groups typically comprise a mesogenic core consisting of one or more aromatic or non-aromatic cyclic groups bonded to each other directly or via linking groups, optionally comprising terminal groups attached to the ends of the mesogenic core, and optionally comprising one or more side groups attached to the long chain of the mesogenic core, where these terminal and side groups are typically selected from, for example, carbyl groups, hydrocarbyl groups, polar groups such as halogen groups, nitro groups, hydroxy groups, etc., or polymerizable groups.

[0030] The term "reactive mesogen" or "polymerizable LC compound" refers to a polymerizable mesogen or liquid crystal compound, preferably a monomeric compound. These compounds can be used as pure compounds or as mixtures of reactive mesogens with other compounds that function as photoinitiators, inhibitors, surfactants, stabilizers, chain transfer agents, non-polymerizable compounds, etc.

[0031] Polymerizable compounds with one polymerizable group are also called "monoreactive" compounds, compounds with two polymerizable groups are called "direactive" compounds, compounds with three, four, five or more polymerizable groups are called "multireactive" compounds, and compounds with no polymerizable groups are called "nonreactive" compounds.

[0032] The term "non-mesogenic compound or material" means a compound or material that does not contain a mesogenic group as defined above or below.

[0033] As used herein, the term "non-polymerizable compound or non-polymerizable mesogenic or liquid crystalline compound" will be understood to mean a liquid crystalline compound 1 that does not contain functional groups suitable for polymerization under conditions normally applied for the polymerization of RMs.

[0034] The "polymerizable group" (P) is preferably selected from groups containing a C=C double bond or a C≡C triple bond and groups suitable for polymerization with ring opening, such as oxetane or epoxide groups.

[0035] Preferably, the polymerizable group (P) is CH2=CW 1 -COO-, CH2=CW 1 -CO-, [ka] CH2=CW 2 -(O) k3 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1-Phe-(O) k2 -, Phe-CH=CH-, During the ceremony, W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 carbon atoms, in particular H, F, Cl or CH3, W 2 represents H or alkyl having 1 to 5 carbon atoms, in particular H, methyl, ethyl or n-propyl, W 3 and W 4 each, independently of one another, denotes H, Cl or alkyl having 1 to 5 carbon atoms, Phe denotes 1,4-phenylene, which is optionally substituted by one or more groups L as defined above, but which are different from P-Sp, preferably preferred substituents L are F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, also phenyl, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 is an integer of 1-10.

[0036] Particularly preferred polymerizable groups (P) are CH2=CH-COO-, CH2=C(CH3)-COO-, CH2=CF-COO-, CH2=CH-, CH2=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH)2CH-O-, [ka] where W 2 represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, and k1 represents 0 or 1.

[0037] More preferred polymerizable groups (P) are vinyl, vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably acrylate or methacrylate, especially acrylate.

[0038] Preferably, all multireactive polymerizable compounds and subformulas thereof contain one or more groups PS Instead of p-, it contains one or more branched groups containing two or more polymerizable groups P (multireactive polymerizable groups).

[0039] Suitable groups of this type, and polymerizable compounds containing them, are described, for example, in US Pat. No. 7,060,200 or US Patent Application Publication No. 2006 / 0172090.

[0040] In particular, the following formula: [ka] Preferred are multi-reactive polymerizable groups selected from During the ceremony, alkyl represents a single bond or a straight or branched alkylene having 1 to 12 carbon atoms, wherein one or more non-adjacent CH groups are each, independently of one another, -C(R x )=C(R x )-, -C≡C-, -N(R x )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, wherein, further, one or more H atoms may be replaced by F, Cl or CN, wherein R x has one of the meanings given above, aa and bb each independently represent 0, 1, 2, 3, 4, 5 or 6; X has one of the meanings given for X', and P v ~P zeach, independently of one another, has one of the meanings given above for P.

[0041] As used herein, the term "spacer group", hereinafter also referred to as "Sp", is known to those skilled in the art and described in the literature, see, for example, Pure Appl. Chem. 2001, vol. 73 (No. 5), p. 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, vol. 116, pp. 6340-6368. As used herein, the term "spacer group" or "spacer" refers to a flexible group, such as an alkylene group, that connects a mesogenic group and a polymerizable group(s) in a polymerizable mesogenic compound.

[0042] When the spacer group Sp is different from a single bond, it is preferably of the formula Sp'-X', where each group P-Sp- is a group in the formula P-Sp'-X', Sp' represents alkylene having 1 to 20, preferably 1 to 12, carbon atoms, optionally mono- or polysubstituted by F, Cl, Br, I or CN, wherein, in addition, one or more non-adjacent CH groups are each independently -O-, -S-, -NH-, -NR-, so that O and / or S atoms are not directly bonded to each other. xx -, -SiR xx R yy -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR xx -CO-O-, -O-CO-NR 0xx -, -NR xx -CO-NR yy may be replaced by -, -CH=CH- or -C≡C-; X' is -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR xx -, -NR xx -CO-, -NR xx -CO-NR yy-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR xx -, -CY xx =CY xx represents -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH- or a single bond; R xx and R yy each independently represent H or alkyl having 1 to 12 carbon atoms, and Y xx and Y yy each independently represent H, F, Cl or CN.

[0043] A typical spacer group Sp' is, for example, -(CH2) p1 -, -(CH2CH2O) q1 -, -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR xx R yy -O) p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R xx and R yy has the above meaning.

[0044] Particularly preferred groups -X'-Sp'- are -(CH2) p1 -, -O-(CH2) p1 -, -OCO-(CH2) p1 -, -OCOO-(CH2) p1 -, where p1 is an integer from 1 to 12.

[0045] Particularly preferred groups Sp and / or Sp′ are, for example, linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene, respectively.

[0046] As used herein, the term "polymer" will be understood to mean a molecule that includes a backbone of one or more different types of repeating units (the smallest building blocks of a molecule), and includes well-known terms such as "oligomer," "copolymer," "homopolymer," and the like. Furthermore, the term polymer will be understood to include, in addition to the polymer itself, residues from initiators, catalysts, and other elements incident to the synthesis of such a polymer, where such residues are understood not to be covalently incorporated therein. Furthermore, such residues and other elements are usually removed in post-polymerization purification processes, but are typically mixed or entrained with the polymer, and they generally remain with the polymer when transferred between containers or solvents or dispersion media.

[0047] As used herein, the term "(meth)acrylic polymer" includes polymers obtained from acrylic monomers, polymers obtained from methacrylic monomers, and the corresponding copolymers obtained from mixtures of such monomers.

[0048] A "polymer network" is a network in which all polymer chains are interconnected by multiple cross-links to form a single macroscopic entity, and when utilized in a PNLC device, preferably spans the entire cell.

[0049] Polymer networks occur in the following types:

[0050] 1. A graft polymer molecule is a branched polymer molecule in which one or more side chains differ structurally or configurationally from the main chain.

[0051] 2. A star polymer molecule is a branched polymer molecule in which multiple linear chains or arms arise from a single branch point. If the arms are identical, the star polymer molecule is said to be regular. If adjacent arms are composed of different repeating subunits, the star polymer molecule is said to be diverse.

[0052] 3. Comb polymer molecules consist of a main chain with two or more three-way branch points and linear side chains. Comb polymer molecules are said to be regular if the main chains are identical.

[0053] 4. Brush polymer molecules consist of a main chain and linear, unbranched side chains, with one or more branching points carrying functional groups in four or more directions.

[0054] The term "polymerization" refers to the chemical process of combining multiple polymerizable groups or polymer precursors (polymerizable compounds) containing those groups to form a polymer.

[0055] The definitions as given in C. Tschierske, G. Pelzl and S. Diele, Angew. Chem. 2004, pp. 116, 6340-6368 apply in addition to the definitions given above, and in particular to non-defined terms related to liquid crystal materials in this application.

[0056] In this specification, the birefringence Δn is defined by the following formula. Δn=n e -n o In the formula, n e is the extraordinary refractive index, and n o is the ordinary refractive index, and the effective mean refractive index n av. is given by the following formula: n av. =[(2n o 2 +n e2 ) / 3] 1 / 2

[0057] Anomalous refractive index n e and the ordinary refractive index n o can be measured, for example, using a modified Abbe refractometer according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", November 1997, Merck, Germany.

[0058] Visible (VIS) light is electromagnetic radiation having a wavelength in the range of about 400 nm to about 800 nm. Unless otherwise specified, ultraviolet (UV) light is electromagnetic radiation having a wavelength in the range of about 200 nm to about 400 nm. Unless otherwise specified, infrared (IR) light is electromagnetic radiation having a wavelength in the range of about 800 nm to about 1 mm.

[0059] The term "transparent" in the context of this application is understood to mean that the transmission of VIS light through the PNLC light-modulating element is at least 65%, more preferably at least 80%, and even more preferably at least 90% of the incident light.

[0060] Irradiance (E e ) or radiation power is defined as the electromagnetic power (dθ) per unit area (dA) incident on a surface: E e = dθ / dA.

[0061] Radiation dose (H e ) is the irradiance or radiation output (E e ) is defined as: H e =E e ·t.

[0062] The term "clearing point" means the temperature at which the transition between the mesophase and the isotropic phase occurs over the maximum temperature range.

[0063] The term "chiral" is generally used to describe an object that is not superimposable on its mirror image.

[0064] "Achiral" objects are objects that are identical to their mirror images.

[0065] Unless otherwise specified, the terms "chiral nematic" and "cholesteric" are used interchangeably herein.

[0066] Chiral nematic textures or cholesteric liquid crystals (CLC) exhibit selective reflection of circularly polarized light, where the direction of rotation of the light vector corresponds to the direction of rotation of the cholesteric helix.

[0067] The reflected wavelength λ is given by the pitch p of the cholesteric helix and the average birefringence n of the cholesteric liquid crystal according to the following formula:

[0068]

number

[0069] CLC media can be prepared, for example, by doping a nematic LC medium with a chiral dopant having a high twisting power, and the pitch p of the induced cholesteric helix is ​​given by the concentration c of the chiral dopant and the helical twisting power HTP according to the following equation:

[0070]

number

[0071] It is also possible to use two or more dopants, for example, to compensate for the temperature dependence of the HTP of the individual dopants and achieve a low temperature dependence of the helical pitch and reflection wavelength of the CLC medium. total ), the following equation holds approximately:

[0072]

number

[0073] c in the formula i are the concentrations of the individual dopants, and HTP i are the helical twisting powers of the respective individual dopants.

[0074] Unless otherwise specified throughout this application, all concentrations are quoted in weight percent and relate to the respective mixture as a whole, all temperatures are quoted in degrees Celsius, and all temperature differences are quoted in degrees differential.

[0075] In this application, the term "dielectrically positive" is used for compounds or components with Δε>3.0, "dielectrically neutral" for -1.5≦Δε≦3.0, and dielectrically negative for Δε<-1.5.

[0076] Δε is determined at a frequency of 1 kHz and 20°C. The dielectric anisotropy of each compound is determined from a 10% solution of each individual compound in a nematic host mixture. If the solubility of the respective compound in the host mixture is less than 10%, the concentration is reduced to 5%. The capacitance of the test mixtures is determined in both cells with homeotropic alignment and cells with homogeneous alignment. The cell thickness of both types of cells is approximately 20 μm. The applied voltage is a square wave with a frequency of 1 kHz and an effective value typically between 0.5 V and 1.0 V, which is always selected to be below the capacitance threshold of each test mixture.

[0077] Δε is (ε ∥ -ε ⊥ ), while ε ave is (ε ∥ +2ε ⊥ ) / 3. The dielectric constant of a compound is determined from the change in the respective values ​​of the host medium upon addition of the compound of interest. Values ​​are extrapolated to a 100% concentration of the compound of interest. Typical host media are ZLI-4792 or BL-087, both commercially available from Merck, Darmstadt.

[0078] As used herein, unless the context clearly dictates otherwise, the plural forms of the terms herein are intended to include the singular form and vice versa.

[0079] In the case of the present invention, [ka] represents trans-1,4-cyclohexylene, [ka] represents 1,4-phenylene.

[0080] In the present invention, the groups -COO-, -C(=O)O- or -CO2- are represented by the formula [ka] and the groups -OCO-, -OC(=O)-, -OC- or -OOC- represent an ester group of the formula [ka] represents an ester group of the formula:

[0081] base [ka] The single bond shown between two ring atoms in can be attached to any non-bonded position on the ring.

[0082] Above and below, "carbon group" refers to a monovalent or polyvalent organic group containing at least one carbon atom, which either contains no additional atoms (such as, for example, -C≡C-) or may contain one or more additional atoms (such as, for example, carbonyl), such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge. The term "hydrocarbon group" refers to a carbon group which additionally contains one or more H atoms and may contain one or more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge.

[0083] The carbon or hydrocarbon group may be saturated or unsaturated. Unsaturated groups are, for example, aryl, alkenyl, or alkynyl groups. The carbon or hydrocarbon group having more than three carbon atoms may be linear, branched, and / or cyclic, and may contain spiro-linked or fused rings.

[0084] Unless otherwise specified throughout this application, the terms "aryl and heteroaryl groups" include groups that may be monocyclic or polycyclic, i.e., they may have one ring (e.g., phenyl, etc.) or two or more rings, which may be fused (e.g., naphthyl) or covalently linked (e.g., biphenyl), or may include a combination of fused and linked rings.

[0085] Heteroaryl groups preferably contain one or more heteroatoms selected from O, N, S, and Se. In particular, monocyclic, bicyclic, or tricyclic aryl groups having 6 to 25 carbon atoms and monocyclic, bicyclic, or tricyclic heteroaryl groups having 2 to 25 carbon atoms are preferred, which optionally contain fused rings and are optionally substituted. Furthermore, 5-, 6-, or 7-membered aryl and heteroaryl groups are preferred, where, in addition, one or more CH groups may be replaced by N, S, or O so that the O and / or S atoms are not directly bonded to each other. Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1':3',1"]terphenyl-2'-yl, naphthyl, anthracene, binaphthyl, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, more preferably 1,4-phenylene, 4,4'-biphenylene, and 1,4-tetraphenylene.

[0086] Preferred heteroaryl groups are, for example, five-membered rings such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole. , 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, or fused groups such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridoimidazole, pyrazineimidazole, quinoxalineimidazole, benzoxazole, naphth Heteroaryl groups include oxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene, or combinations of these groups. Heteroaryl groups may be substituted with alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl, or further aryl or heteroaryl groups.

[0087] In the context of this application, the term "(non-aromatic) alicyclic and heterocyclic groups" includes both saturated rings, i.e., those containing only single bonds, and partially unsaturated rings, i.e., those which may contain multiple bonds. Heterocyclic rings preferably contain one or more heteroatoms selected from Si, O, N, S, and Se. (Non-aromatic) alicyclic and heterocyclic groups can be monocyclic, i.e., containing only one ring (e.g., cyclohexane), or polycyclic, i.e., containing multiple rings (e.g., decahydronaphthalene or bicyclooctane). Saturated groups are particularly preferred. Furthermore, monocyclic, bicyclic, or tricyclic groups having 3 to 25 carbon atoms are preferred, which optionally contain fused rings and are optionally substituted. Furthermore, 5-, 6-, 7- or 8-membered carbocyclic groups are preferred, wherein, further, one or more carbon atoms may be replaced by Si, and / or one or more CH groups may be replaced by N, and / or one or more non-adjacent CH groups may be replaced by -O- and / or -S-. Preferred alicyclic and heterocyclic groups are, for example, 5-membered ring groups such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine, 6-membered ring groups such as cyclohexane, silylan, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, 7-membered ring groups such as cycloheptane, and fused groups such as tetrahydronaphthalene, decahydronaphthalene, indan, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindan-2,5-diyl, more preferably 1,4-cyclohexylene, 4,4'-bicyclohexylene, 3,17-hexadecahydrocyclopenta[a]phenanthrene, optionally substituted by one or more identical or different groups L.Particularly preferred aryl, heteroaryl, alicyclic and heterocyclic groups are 1,4-phenylene, 4,4'-biphenylene, 1,4-terphenylene, 1,4-cyclohexylene, 4,4'-bicyclohexylene and 3,17-hexadecahydrocyclopenta[a]-phenanthrene, which may be substituted by one or more identical or different groups L.

[0088] Preferred substituents (L) for the above-mentioned aryl, heteroaryl, alicyclic and heterocyclic groups are, for example, solubility-promoting groups such as alkyl or alkoxy, electron-withdrawing groups such as fluorine, nitro or nitrile.

[0089] Preferred substituents, hereinafter also referred to as "L", are, for example, F, Cl, Br, I, -OH, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y x , -C(=O)R x , -C(=O)OR x , -N(R x )2, where R x has the above meaning, and Y x represents halogen, optionally substituted silyl, optionally substituted aryl or heteroaryl having 4 to 40, preferably 4 to 20, ring atoms, and straight-chain or branched alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 carbon atoms, wherein one or more H atoms may optionally be replaced by F or Cl.

[0090] "Substituted silyl or aryl" preferably includes halogen, -CN, R y , -OR y , -CO-R y , -CO-OR y , -O-CO-R y or -O-CO-OR y (In the formula, R ymeans substituted with H, a straight, branched or cyclic alkyl chain having 1 to 12 carbon atoms.

[0091] In the formulas shown above and below, the substituted phenylene ring [ka] In the formula, L is each the same or different and has one of the meanings given above and below and is preferably F, Cl, CN, NO, CH, C, H, C(CH), CH(CH), CH, CH(CH)C, H, OCH, OC, H, COCH, COC, H, COOCH, COOC, H, CF, OCF, OCHF, OC, F or P-Sp-, very preferably F, Cl, CN, CH, C, H, OCH, COCH, OCF or P-Sp-, most preferably F, Cl, CH, OCH, COCH or OCF.

[0092] "Halogen" represents F, Cl, Br or I, preferably F or Cl, more preferably F.

[0093] Also, the terms "alkyl", "aryl", "heteroaryl", etc., above and below, also encompass polyvalent groups such as alkylene, arylene, heteroarylene, etc.

[0094] The term "aryl" refers to an aromatic carbon group or a group derived therefrom.

[0095] The term "heteroaryl" refers to an "aryl" as defined above containing one or more heteroatoms.

[0096] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, and the like.

[0097] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, and the like.

[0098] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, and the like.

[0099] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, and the like.

[0100] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, and the like.

[0101] Throughout the description and claims of this specification, the words "comprise" and "containing" and variations of these words, such as "comprising" and "comprises," mean "including, but not limited to," and are not intended to exclude (or exclude) other elements. On the other hand, the term "comprise" also encompasses, but is not limited to, the term "consisting of."

[0102] Throughout the description and claims of this specification, the words "obtainable" and "obtained" and variations of these words mean "including, but not limited to," and are not intended to exclude (or exclude) other elements. Meanwhile, the term "obtainable" also encompasses, but is not limited to, the term "obtained."

[0103] The term "alignment" or "orientation" refers to the alignment (orientational order) of anisotropic units of a material, such as small molecule and macromolecular fragments, in a common direction called the "orientation direction." In an alignment layer of a liquid crystal material, the orientation direction corresponds to the direction of the anisotropic axis of the material, so that the liquid crystal director coincides with the orientation direction.

[0104] The term "planar orientation / alignment" means that, for example in a layer of liquid crystal material, a proportion of the liquid crystal molecules have their long molecular axes (in the case of calamitic compounds) or short molecular axes (in the case of discotic compounds) oriented substantially parallel (approximately 180°) to the plane of the layer.

[0105] The term "homeotropic orientation / alignment" means that, for example in a layer of liquid crystal material, a proportion of the liquid crystal molecules are oriented with their long molecular axes (in the case of calamitic compounds) or their short molecular axes (in the case of discotic compounds) at an angle θ ("tilt angle") between about 80° and 90° to the plane of the layer.

[0106] <Detailed explanation>

[0107] Preferably, in the compounds of formula I and its sub-formulas as described above and below, all polymerizable groups P present in the compound have the same meaning, more preferably they represent acrylate or methacrylate, most preferably methacrylate.

[0108] Further preferred are compounds of formula I and its sub-formulae, in which the groups Ar are selected from the formulae Ar5, Ar6 and Ar7 and the groups P present in the compounds are the same or different.

[0109] In the compounds of formula I and its subformulae as described above and below, Ar is preferably selected from formulae Ar1, Ar2 and Ar5.

[0110] Preferred compounds of formula I are selected from the following subformulae:

[0111] [ka]

[0112] [ka]

[0113] wherein P, Sp and L have one of the meanings given in formula I, r1, r3, and r7 are each independently 0, 1, 2, or 3; r2 is 0, 1, 2, 3 or 4; r4, r5, and r6 are each independently 0, 1, or 2.

[0114] Compounds of formulae I1, I2 and I5 are highly preferred.

[0115] Further preferred compounds of formula I are selected from the following subformulae:

[0116] [ka]

[0117] [ka]

[0118] wherein P, Sp, L, r1 to r17 have the meanings given in formula I or one of the preferred meanings as given above and below.

[0119] Highly preferred compounds of formula I are selected from the following sub-formulae:

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] where P, Sp have the meanings given above and below, and L a and L b each independently has one of the meanings given for L above or below.

[0126] Highly preferred compounds of the sub-formulae I1-1-1 to I2-1-18 are those in which all groups P are identical and represent either an acrylate or a methacrylate, and in addition Sp is -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO- or -(CH2) p1 -CO-O-, where p1 is an integer of 1 to 12, preferably 1 to 6, and an O or CO group is linked to the benzene ring; and further L a and L b represents F, CH3, CH2CH3, OCH3, OC2H5, O(CH2)2CH3, OC(CH3)3 or OCF3.

[0127] Further preferred compounds of formula I and its sub-formulas are selected from the following preferred embodiments, including any combination thereof.

[0128] All groups P in the compound have the same meaning.

[0129] ·Ar is selected from the formulae Ar1, Ar2, Ar3 and Ar4, and all groups P present in the compound have the same meaning.

[0130] ·Ar is selected from the formulae Ar1, Ar2, Ar3, Ar4 and Ar5, and all groups P present in the compound have the same meaning.

[0131] ·Ar is selected from the formulae Ar1, Ar2, Ar3, Ar4 and Ar6, and all groups P present in the compound have the same meaning.

[0132] Ar is selected from the formulae Ar1, Ar2, Ar3, Ar4 and Ar7, and all groups P present in the compound have the same meaning.

[0133] Ar is selected from the formulae Ar1, Ar2, Ar3, Ar4, Ar5 and Ar7, and all groups P present in the compound have the same meaning.

[0134] Ar is selected from the formulae Ar1, Ar2, Ar3, Ar4, Ar6 and Ar7, and all groups P present in the compound have the same meaning.

[0135] ·Ar is selected from the group of formula Ar5, and the groups P present in the compound may have the same or different meanings.

[0136] ·Ar is selected from the group of formula Ar6, and the groups P present in the compound may have the same or different meanings.

[0137] ·Ar is selected from the group of formula Ar7, and the groups P present in the compound may have the same or different meanings.

[0138] The compound contains only two polymerizable groups (represented by the group P).

[0139] ·P is selected from the group consisting of acrylates, methacrylates and oxetanes.

[0140] If Sp is different from a single bond, -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or CO group, respectively, is linked to the benzene ring.

[0141] L b L a If different from, represents F, Cl or CN.

[0142] L a is F, CH3, CH2CH3, OCH3, OC2H5, O(CH2)2CH3, OC(CH3)3 or OCF3.

[0143] r1, r2, and r3 represent 0 or 1.

[0144] r1, r2, r3, r4, r5 and r6 represent 0 or 1.

[0145] ·One of r1 and r7 is 0 and the other is 1.

[0146] r1 is 1, r2 and r3 are 0.

[0147] r3 is 1, r1 and r2 are 0.

[0148] ·One of r4 and r5 is 0 and the other is 1.

[0149] r4 and r6 are 0, and r5 is 1.

[0150] ·r1 and r4 are 0, and r3 is 1.

[0151] ·r1 and r3 are 0, and r4 is 1.

[0152] r3 and r4 are 0 and r1 is 1.

[0153] More preferred compounds of formula I and its subformulas are those in which P is selected from the group consisting of acrylates, methacrylates and oxetanes, and L a and L b are selected from the compounds of the formulae I1-1-1, I1-1-3, I1-2-2 and I2-1-1 to I2-1-6, each independently F, CH3, CH2CH3, OCH3, OC2H5, O(CH2)2CH3, OC(CH3)3 or OCF3.

[0154] Compounds and intermediates of formula I and its sub-formulas are known to those skilled in the art and can be prepared analogously to methods described, for example, in standard works of organic chemistry such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

[0155] For example, acrylic or methacrylic acid esters can be prepared by esterifying the corresponding alcohol with an acid derivative such as (meth)acrylic chloride or (meth)acrylic anhydride in the presence of a base such as pyridine or triethylamine and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, esters can be prepared by esterifying the alcohol with (meth)acrylic acid in the presence of a dehydrating reagent such as dicyclohexylcarbodiimide (DCC) according to Steglich, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP.

[0156] Particularly preferred are cholesteric LC media in which the polymerizable component A) comprises one, two or three polymerizable compounds of formula I.

[0157] Further preferred is a cholesteric LC medium wherein the polymerizable component A) comprises only polymerizable compounds of formula I.

[0158] Optionally, one or more polymerization initiators can be added to the cholesteric LC medium. Suitable conditions for polymerization and suitable types and amounts of initiators are known to those skilled in the art and are described in the literature.

[0159] For example, commercially available photopolymerization initiators such as Irgacure 651 (registered trademark), Irgacure 184 (registered trademark), Irgacure 907 (registered trademark), Irgacure 369 (registered trademark), and Darocure 1173 (registered trademark) (Ciba) are suitable for free radical polymerization. When a polymerization initiator is used, the proportion of the initiator is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.

[0160] The polymerizable compounds according to the present invention are also suitable for polymerization without initiators, which entails significant advantages, such as lower material costs and, in particular, less contamination of the cholesteric LC medium with residual amounts of initiators or their degradation products.Therefore, polymerization can also be carried out without adding initiators.In a preferred embodiment, the cholesteric LC medium does not contain a polymerization initiator.

[0161] The cholesteric LC medium may also contain one or more stabilizers, e.g., to prevent undesired spontaneous polymerization of the RM during storage or transport. Suitable types and amounts of stabilizers are known to those skilled in the art and are described in the literature.

[0162] Particularly suitable are commercially available stabilizers from the Irganox® series (Ciba), such as Irganox® 1076. When a stabilizer is used, the proportion of the stabilizer is preferably 10 to 500,000 ppm, particularly preferably 50 to 50,000 ppm, based on the total amount of RM or polymerizable component (component A).

[0163] Preferably, the cholesteric LC medium according to the present invention consists essentially of polymerizable component A) or one or more polymerizable compounds of formula I, LC component B) or an LC host mixture, and chiral component C) comprising one or more chiral compounds, as described above and below.

[0164] However, the cholesteric LC medium may additionally comprise one or more further components or additives, preferably selected without limitation from the list which includes inhibitors, further stabilizers, wetting agents, lubricants, dispersants, hydrophobizing agents, adhesives, flow improvers, antifoaming agents, defoamers, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0165] In another preferred embodiment, in addition to the compound of formula I, the polymerizable component A) comprises one or more further polymerizable compounds (“comonomers”), which are preferably selected from RMs.

[0166] Suitable and preferred mesogenic comonomers are selected from the following formulae:

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] wherein the individual groups have the following meanings: P 1 , P 2 and P 3 each independently represents an acrylate or methacrylate group, Sp 1 , Sp 2 and Sp 3 each independently of one another represents a single bond or a spacer having one of the meanings given above and below for Sp, particularly preferably -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -CO-O-, -(CH2) p1-O-CO- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer of 1 to 12; In addition, the group P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 -At least one of R aa one or more groups P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - is R aa may also represent R aa is H, F, Cl, CN, or a linear or branched alkyl having 1 to 25 C atoms (provided that in addition, one or more non-adjacent CH groups may each independently be C(R) such that O and / or S atoms are not directly linked to each other). 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that in addition, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 -), particularly preferably represents a linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, with the proviso that alkenyl and alkynyl groups have at least 2 C atoms and branched groups have at least 3 C atoms, R 0 , R 00 each, independently of one another, identically or differently in each occurrence, represents H or alkyl having 1 to 12 C atoms, R y and R zeach independently represents H, F, CH3 or CF3, X 1 , X 2 and X 3 each independently represents -CO-O-, -O-CO- or a single bond, Z 1 -O-, -CO-, -C(R y R z )- or -CF2CF2-, Z 2 and Z 3 are each independently -CO-O-, -O-CO-, -CHO-, -OCH-, -CFO-, -OCF- or -(CH) n -, where n is 2, 3 or 4; L is, identically or differently in each occurrence, F, Cl, CN, or an alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 carbon atoms, which may be linear or branched and monofluorinated or polyfluorinated, preferably F; L' and L" each independently represent H, F or Cl; r represents 0, 1, 2, 3 or 4; s represents 0, 1, 2 or 3; t represents 0, 1, or 2; x represents 0 or 1.

[0174] Compounds of formulae M2, M13, M17, M22, M23, M24 and M30 are particularly preferred.

[0175] Furthermore, trireactive compounds M15 to M30, particularly M17, M18, M19, M22, M23, M24, M25, M26, M30 and M31 are preferred.

[0176] In the compounds of formulae M1 to M31, [ka]

[0177] wherein L, identically or differently, in each occurrence has one of the meanings given above and below, preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3 or OCF3, in particular F or CH3.

[0178] Besides the above-mentioned polymerizable compounds, the LC medium for use in the LC displays according to the invention comprises a liquid crystal component B) or LC host mixture exhibiting positive dielectric anisotropy, which preferably comprises one or more, more preferably two or more LC compounds selected from non-polymerizable low molecular weight compounds.

[0179] These LC compounds are selected to be stable and / or non-reactive to the polymerization reaction under the conditions applied to polymerize the polymerizable compounds.

[0180] Preferred LC compounds that can be employed in the liquid crystal component B) according to the present invention are shown below.

[0181] [ka]

[0182] In the formula, the individual radicals each independently of one another have the following meanings, which may be the same or different at each occurrence: [ka] R 21 , R 31each independently represent alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms, or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which may be fluorinated; X 0 represents F, Cl, a halogenated alkyl or alkoxy having 1 to 6 C atoms, or a halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, Z 31 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO- or a single bond, preferably -CH2CH2-, -COO-, trans-CH=CH- or a single bond, particularly preferably -COO-, trans-CH=CH- or a single bond, L 21 , L 22 , L 31 , L 32 each independently represents H or F, g represents 0, 1, 2 or 3.

[0183] In the compounds of formula A and B, X 0 is preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCH2F, OCF2CH3, OCF2CHF2, OCF2CH2F, OCF2CF2CHF2, OCF2CF2CH2F, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCClFCF2CF3 or CH=CF2, very preferably F or OCF3, most preferably F.

[0184] In the compounds of formula A and B, R 21 and R 31 is preferably selected from straight-chain alkyl or alkoxy having 1, 2, 3, 4, 5 or 6 C atoms and straight-chain alkenyl having 2, 3, 4, 5, 6 or 7 C atoms.

[0185] In compounds of formula A and B, g is preferably 1 or 2.

[0186] In the compound of formula B, Z 31 is preferably COO, trans-CH=CH or a single bond, very preferably COO or a single bond.

[0187] Preferably, component B) of the LC medium comprises one or more compounds of formula A selected from the group consisting of the following formulae:

[0188] [ka]

[0189] In the formula, A 21 , R 21 , X 0 , L 21 and L 22 has the meaning given in formula A, and L 23 and L 24 are each independently H or F, and X 0 is preferably F. Compounds of formulae A1 and A2 are particularly preferred.

[0190] Particularly preferred compounds of formula A1 are selected from the group consisting of the following subformulae:

[0191] [ka]

[0192] [ka]

[0193] In the formula, R 21 , X 0 , L 21 and L 22 has the meaning given in formula A1, and L 23 , L 24 , L 25 and L26 are each independently H or F, and X 0 is preferably F.

[0194] Very particularly preferred compounds of formula A1 are selected from the group consisting of the following subformulae:

[0195] [ka]

[0196] In the formula, R 21 is as defined in formula A1.

[0197] Highly preferred compounds of formula A2 are selected from the group consisting of the following subformulae:

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] In the formula, R 21 , X 0 , L 21 and L 22 has the meaning given in formula A2, and L 23 , L 24 , L 25 and L 26 are each independently H or F, and X 0 is preferably F.

[0202] Very particularly preferred compounds of formula A2 are selected from the group consisting of the following subformulae:

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] In the formula, R 21 and X 0 is as defined in formula A2.

[0207] Particularly preferred compounds of formula A3 are selected from the group consisting of the following subformulae:

[0208] [ka]

[0209] In the formula, R 21 , X 0 , L 21 and L 22 has the meaning given in equation A3, and X 0 is preferably F.

[0210] Particularly preferred compounds of formula A4 are selected from the group consisting of the following subformulae:

[0211] [ka]

[0212] In the formula, R 21 is as defined in equation A4.

[0213] Preferably, component B) of the LC medium comprises one or more compounds of formula B selected from the group consisting of the following formulae:

[0214] [ka]

[0215] In the formula, g, A 31 , A 32 , R 31 , X 0 , L 31 and L 32 has the meaning given in formula B, and X 0 is preferably F. Compounds of formula B1 and B2 are particularly preferred.

[0216] Particularly preferred compounds of formula B1 are selected from the group consisting of the following subformulae:

[0217] [ka]

[0218] In the formula, R 31 , X 0 , L 31 and L 32 has the meaning given in formula B1, and X 0 is preferably F.

[0219] Very particularly preferred compounds of formula B1a are selected from the group consisting of the following subformulae:

[0220] [ka]

[0221] In the formula, R 31 is as defined in formula B1.

[0222] Very particularly preferred compounds of formula B1b are selected from the group consisting of the following subformulae:

[0223] [ka]

[0224] In the formula, R 31 is as defined in formula B1.

[0225] Particularly preferred compounds of formula B2 are selected from the group consisting of the following subformulae:

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] In the formula, R 31 , X 0 , L 31 and L 32 has the meaning given in formula B2, and L 33 , L 34 , L 35 and L 36 are each independently H or F, and X 0 is preferably F or CN.

[0230] Very particularly preferred compounds of formula B2 are selected from the group consisting of the following subformulae:

[0231] [ka]

[0232] In the formula, R 31 is as defined in formula B2.

[0233] Very particularly preferred compounds of formula B2b are selected from the group consisting of the following subformulae:

[0234] [ka]

[0235] In the formula, R 31 is as defined in formula B2.

[0236] Very particularly preferred compounds of formula B2c are selected from the group consisting of the following subformulae:

[0237] [ka]

[0238] In the formula, R 31 is as defined in formula B2.

[0239] Very particularly preferred compounds of the formulae B2d and B2e are selected from the group consisting of the following subformulae:

[0240] [ka]

[0241] In the formula, R 31 is as defined in formula B2.

[0242] Very particularly preferred compounds of formula B2f are selected from the group consisting of the following subformulae:

[0243] [ka]

[0244] In the formula, R 31 is as defined in formula B2.

[0245] Very particularly preferred compounds of formula B2g are selected from the group consisting of the following subformulae:

[0246] [ka]

[0247] In the formula, R 31 is as defined in formula B2.

[0248] Very particularly preferred compounds of the formula B2h are selected from the group consisting of the following subformulae:

[0249] [ka]

[0250] In the formula, R 31 is as defined in formula B2.

[0251] Very particularly preferred compounds of formula B2i are selected from the group consisting of the following subformulae:

[0252] [ka]

[0253] In the formula, R 31 is as defined in formula B2.

[0254] Very particularly preferred compounds of formula B2k are selected from the group consisting of the following subformulae:

[0255] [ka]

[0256] In the formula, R 31 is as defined in formula B2.

[0257] Very particularly preferred compounds of formula B21 are selected from the group consisting of the following subformulae:

[0258] [ka]

[0259] In the formula, R 31 is as defined in formula B2.

[0260] Alternatively or in addition to the compounds of the formulae B1 and / or B2, component B) of the LC medium may also comprise one or more compounds of the formula B3 as defined above.

[0261] Particularly preferred compounds of formula B3 are selected from the group consisting of the following subformulae:

[0262] [ka]

[0263] In the formula, R 31 is as defined in Equation B3.

[0264] Preferably, component B) of the LC medium comprises, in addition to the compounds of the formulae A and / or B, one or more compounds of the formula C.

[0265] [ka]

[0266] In the formula, the individual groups have the following meanings: [ka] R 41 , R 41 each independently represent alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms, or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which may be fluorinated; Z 41 , Z 41 each independently represent -CHCH-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CFO-, -C≡C- or a single bond, preferably a single bond; h represents 0, 1, 2 or 3.

[0267] In the compound of formula C, R 41 and R 41 is preferably selected from straight-chain alkyl or alkoxy having 1, 2, 3, 4, 5 or 6 C atoms and straight-chain alkenyl having 2, 3, 4, 5, 6 or 7 C atoms.

[0268] In compounds of formula C, h is preferably 0, 1 or 2.

[0269] In the compound of formula C, Z 41 and Z 41 is preferably selected from COO, trans-CH=CH or a single bond, very preferably COO or a single bond.

[0270] Preferred compounds of formula C are selected from the group consisting of the following subformulae:

[0271] [ka]

[0272] [ka]

[0273] In the formula, R 41 and R 42 have the meanings given in formula C and preferably each independently of one another denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms.

[0274] More preferably, component B) of the LC medium comprises, in addition to the compounds of the formulae A and / or B, one or more compounds of the formula D

[0275] [ka]

[0276] In the formula, A 41 , A 42 , Z 41 , Z 42 , R 41 , R 42 and h have one of the meanings given in formula C or the preferred meanings given above.

[0277] Preferred compounds of formula D are selected from the group consisting of the following subformulae:

[0278] [ka]

[0279] In the formula, R 41 and R 42 has the meaning given in formula D, and R 41 preferably represents alkyl, and in formula D1, R 42 preferably denotes alkenyl, particularly preferably -(CH2)2-CH=CH-CH3, and in formula D2, R 42 preferably represents alkyl, —(CH 2 ) 2 —CH═CH 2 or —(CH 2 ) 2 —CH═CH—CH 3 .

[0280] More preferably, component B) of the LC medium comprises, in addition to the compounds of the formulae A and / or B, one or more compounds of the formula E

[0281] [ka]

[0282] In the formulae, the individual radicals, which are identical or different at each occurrence, each have the following meanings independently of one another: [ka] [ka] R A1 represents alkenyl having 2 to 9 carbon atoms, and when at least one of rings X, Y and Z represents cyclohexenyl, R A2 It also has one of the meanings R A2 represents alkyl having 1 to 12 C atoms, provided that in addition, one or two non-adjacent CH groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO-, in such a way that the O atoms are not directly linked to one another, x represents 1 or 2.

[0283] R A2 is preferably straight-chain alkyl or alkoxy having 1 to 8 C atoms or straight-chain alkenyl having 2 to 7 C atoms.

[0284] Preferred compounds of formula E are selected from the group consisting of the following subformulae:

[0285] [ka]

[0286] [ka]

[0287] In the formula, alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl * each independently represents a straight-chain alkenyl group having 2 to 7 carbon atoms. * preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0288] Highly preferred compounds of formula E are selected from the group consisting of the following subformulae:

[0289] [ka]

[0290] In the formula, m represents 1, 2, 3, 4, 5, or 6, i represents 0, 1, 2, or 3, and R b1 represents H, CH3 or C2H5.

[0291] Very particularly preferred compounds of formula E are selected from the group consisting of the following subformulae:

[0292] [ka]

[0293] Compounds of formula E1a2, E1a5, E3a1 and E6a1 are most preferred.

[0294] More preferably, component B) of the LC medium comprises, in addition to the compounds of the formulae A and / or B, one or more compounds of the formula F

[0295] [ka]

[0296] In the formula, the individual radicals each independently of one another have the following meanings, which may be the same or different at each occurrence: [ka] represents R 21 , R 31 each independently represent alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms, or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which may be fluorinated; X 0 represents F, Cl, a halogenated alkyl or alkoxy having 1 to 6 C atoms, or a halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, Z 21 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -C2O-, -CF2O-, -C≡C- or a single bond, preferably -CF2O-, L 21 , L 22 , L 23 , L 24 each independently represents H or F, g represents 0, 1, 2 or 3.

[0297] Particularly preferred compounds of formula F are selected from the group consisting of the following formulae:

[0298] [ka]

[0299] In the formula, R 21 , X 0 , L 21 and L 22 has the meaning given in formula F, and L 25 and L 26 are each independently H or F, and X 0 is preferably F.

[0300] Very particularly preferred compounds of the formulae F1 to F3 are selected from the group consisting of the following subformulae:

[0301] [ka]

[0302] [ka]

[0303] In the formula, R 21 is as defined in formula F1.

[0304] The medium preferably comprises one or more neutral compounds of general formula N.

[0305] [ka]

[0306] During the ceremony, R N1 and R N2 each independently represent an alkyl or alkoxy group having 1 to 15 C atoms, provided that in addition, one or more CH groups in these groups are each independently -C≡C-, -CF2O-, ... [ka] may be replaced by -O-, -CO-O-, or -O-CO-, in which one or more H atoms may additionally be replaced by halogen; Ring A N1 , A N2 and A N3 each independently represent 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, trans-1,4-cyclohexylene (in which one or two CH groups may additionally be replaced by -O-) or 1,4-cyclohexenylene, Z N1 and Z N2 each independently represents a single bond or -C≡C-, provided that at least one Z N1 and Z N2 represents -C≡C-, n represents 0, 1 or 2.

[0307] Preferred compounds of formula N are shown below.

[0308] [ka]

[0309] During the ceremony, Alkyl and alkyl * each independently represent a linear alkyl group having 1 to 9 C atoms, preferably 2 to 6 C atoms, and alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms.

[0310] The concentration of the compounds of formula A and B in the LC host mixture is preferably 2-60%, very preferably 3-55%, most preferably 4-50%.

[0311] The concentration of compounds of formulae C and D in the LC host mixture is preferably 5-75%, very preferably 10-70%, most preferably 15-60%.

[0312] The concentration of the compound of formula E in the LC host mixture is preferably 5-30%, very preferably 10-25%.

[0313] The concentration of the compound of formula F in the LC host mixture is preferably 2-30%, very preferably 5-20%.

[0314] Further preferred embodiments of the present invention are listed below, including any combination thereof.

[0315] 2a) The LC host mixture comprises one or more compounds of formula A and / or B having a high positive dielectric anisotropy, preferably Δε higher than 15.

[0316] 2b) The LC host mixture comprises one or more compounds selected from the group consisting of A1a2, A1b1, A1d1, A1f1, A2a1, A2h1, A2l2, A2k1, B2g3 and / or B2F. The proportion of these compounds in the LC host mixture is preferably 5-50.

[0317] 2c) The LC host mixture comprises one or more compounds selected from the group consisting of formulae C3, C4, C5, C9 and D2, the proportion of these compounds in the LC host mixture being preferably 8-75%, very preferably 10-70%.

[0318] 2d) The LC host mixture comprises one or more compounds selected from the group consisting of formulae E1, E3 and E6, preferably E1a, E3a and E6a, very preferably E1a2, E1a5, E3a1 and E6a1, the proportion of these compounds in the LC host mixture being preferably 5-40%, very preferably 10-25%.

[0319] The optimum mixing ratio of the compounds of the above formula in the liquid crystal component B) depends essentially on the desired properties, the choice of the components of the above formula and the choice of further components that may be present. Preferred physical properties are given below.

[0320] In a preferred embodiment, the liquid crystal component B) according to the present invention is characterized by an optical anisotropy value that is as high as possible. Preferably, the liquid crystal component B) exhibits an optical anisotropy (Δn) in the range of 0.05 to 0.500, more preferably 0.100 to 0.300, and particularly 0.150 to 0.250.

[0321] Preferably, the liquid crystal component B) according to the present invention is characterized by a relatively high, preferably as high as possible, positive value of the dielectric anisotropy (Δε). In a preferred embodiment, the liquid crystal component B) exhibits a positive dielectric anisotropy in the range of 3 to 50, preferably 4 to 25, particularly preferably 5 to 20.

[0322] The nematic phase of the liquid crystal component B) according to the present invention preferably ranges from at least 0°C or lower to 70°C or higher, more preferably from at least -20°C or lower to 75°C or higher, very preferably from at least -30°C or lower to 75°C or higher, and particularly preferably from at least -40°C or lower to 80°C or higher.

[0323] The clearing point of the liquid crystal component B) according to the invention is preferably in the range from 10°C to 120°C, particularly preferably in the range from 40°C to 110°C, very particularly preferably in the range from 60°C to 100°C.

[0324] The rotational viscosity of liquid crystal component B) is preferably as low as possible. Liquid crystal component B) preferably exhibits a rotational viscosity of about 500 mPas or less, preferably in the range of 1 mPas to 500 mPas, more preferably in the range of 10 mPas to 300 mPas, and particularly in the range of 50 mPas to 200 mPas.

[0325] The cholesteric LC media according to the invention comprise one or more chiral dopants or chiral components c).

[0326] Preferably, the cholesteric LC media according to the invention, either alone or in combination with one another, have a viscosity of 5 μm -1 More than 10 μm, preferably -1 More preferably, 15 μm -1 The absolute value of the helical twisting force (|HTP total It includes one or more chiral compounds having |).

[0327] Chiral dopants with higher helical twisting power (HTP) are preferred, especially those disclosed in WO 98 / 00428.

[0328] Typically used chiral compounds are, for example, commercially available R / S-5011, CD-1, R / S-811 and CB-15 (Merck, Darmstadt, Germany).

[0329] In another preferred embodiment, the chiral dopant is preferably selected from formula ChI and / or formula ChII, each including the (S,S) enantiomer.

[0330] [ka]

[0331] In the formula, E and F are each independently 1,4-phenylene or trans-1,4-cyclohexylene, v is 0 or 1, and Z 0 is -COO-, -OCO-, -CH2CH2- or a single bond, and R is alkyl, alkoxy or alkanoyl having 1 to 12 C atoms.

[0332] Compounds of formula ChI and their synthesis are described in WO 98 / 00428. Compounds of formula ChII and their synthesis are described in GB 2,328,207.

[0333] The chiral dopant R / S-5011 and the compounds of formulae ChI and ChII described above exhibit very high helical twisting power (HTP) and are therefore particularly useful for the purposes of the present invention.

[0334] The liquid crystal medium preferably comprises preferably 1 to 5, in particular 1 to 3, very preferably 1 or 2 chiral dopants selected from the above formulae ChI and / or ChII and / or R-5011 or S-5011, very preferably the chiral compounds are R-5011, S-5011.

[0335] Typically, the absolute value of the helical twisting force (|HTP total The total amount of chiral compounds having |) in the cholesteric liquid crystal medium is preferably 0.1% by weight or more to 0.9% by weight or more of the total mixture.

[0336] The cholesteric LC media should additionally be of such a nature that different reflection wavelengths, especially in the infrared region, can be achieved by simple and targeted changes. Preferably, the cholesteric pitch of the cholesteric LC media is selected so that their reflection wavelengths are within the infrared region of the electromagnetic spectrum, i.e., in the range of 800 nm to 5000 nm, more preferably in the form of 1000 to 4000 nm. In particular, the reflection wavelength of the liquid crystal medium is in the range of 2000 nm to 3500 nm.

[0337] The cholesteric LC media according to the invention are prepared in a manner conventional per se, for example by mixing one or more of the above-mentioned polymerizable compounds with one or more non-polymerizable compounds and one or more chiral compounds, both as defined above, and optionally with further liquid crystalline compounds and / or additives.

[0338] The desired amount of the component that is generally used in a small amount is dissolved in the component that constitutes the main component, preferably at high temperature.It is also possible to mix the solution of the components in an organic solvent, such as acetone, chloroform or methanol, and after thorough mixing, remove the solvent again, for example by distillation.Therefore, the present invention also relates to the process for preparing the cholesteric LC medium according to the present invention.

[0339] The cholesteric LC media according to the invention are highly suitable for use in different types of PNLC light modulator elements. The invention therefore also relates to the use of a cholesteric LC medium as described below in a PNLC light modulator element.

[0340] The present invention therefore also relates to a PNLC light modulation element comprising a pair of opposing substrates, an electrode structure, preferably an in-plane electrode structure, and a cholesteric LC medium located in the gap between the substrates, characterized in that the PNLC light modulation element comprises a polymer network obtainable from the cholesteric LC medium by exposing the cholesteric LC medium to actinic radiation that induces photopolymerization of a polymerizable compound in the cholesteric LC medium.

[0341] The present invention further provides a method for manufacturing a PNLC light-modulating element, comprising the steps of: cutting and cleaning the substrate; providing an electrode structure on one or both substrates; Optionally, providing an alignment layer on the electrode structure; Assembling the cells; - filling the cell with a cholesteric LC medium according to the invention, exposing the cholesteric LC medium to actinic radiation that induces photopolymerization of the polymerizable compound in the LC medium; The present invention relates to a method comprising at least

[0342] In one embodiment of the present invention, the cholesteric LC medium is injected between the first and second substrates or filled into the assembled cell by capillary forces or vacuum filling after combining the first and second substrates.

[0343] However, it is also preferable that the liquid crystal composition be interposed between the first and second substrates by mounting the liquid crystal composition on the first substrate and then combining the second substrate with the first substrate. In a preferred embodiment, the liquid crystal is dispensed by dropping it onto the first substrate using a process known as the "one drop filling (ODF)" method, as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 63-179323 and 10-239694, or by ink jet printing (IJP).

[0344] In the irradiation step, the cell is exposed to actinic radiation that photopolymerizes the polymerizable functional groups of the polymerizable compound contained in the cholesteric liquid crystal medium.

[0345] Polymerization is achieved, for example, by exposing the polymerizable material to heat or, preferably, actinic radiation, which means irradiation with light such as UV, IR or visible light, irradiation with X-rays or gamma rays, or irradiation with high-energy particles such as ions or electrons.

[0346] Preferably, the polymerization is carried out by UV radiation. As a source of actinic radiation, for example, a single UV lamp or a set of UV lamps can be used. Another possible source of actinic radiation is a laser, for example, a UV, IR or visible laser.

[0347] Upon irradiation, the polymerizable compound is crosslinked substantially in situ within the liquid crystal medium between the substrates forming the PNLC light modulating element, thereby forming a polymer network that preferably extends throughout the entire switch layer.

[0348] As a result, the formed polymer network results in an effective cell gap that is much smaller than the typical cell gap typically considered for liquid crystal cells. This allows the focal conic texture to switch and relax back to the aligned helical twist very quickly. Instead of switching times on the order of 10 seconds or more, switching times can be reduced to the order of (sub) milliseconds.

[0349] The utilized wavelength of the actinic radiation should not be too low to avoid damage to the LC molecules of the medium and should preferably be different from, and very preferably higher than, the UV absorption maximum of the LC host mixture.

[0350] On the other hand, the wavelength of the light radiation is preferably not too high in order to rapidly and completely UV photopolymerize the polymerizable compound, and is desirably equal to or higher than the UV absorption maximum of the polymerizable component, preferably equal to or lower than that.

[0351] A suitable wavelength is preferably selected from the range of 250 to 450 nm, for example, a wavelength of 400 nm or less, preferably 350 nm or less, more preferably 300 nm or less.

[0352] The irradiation or exposure time should be selected to ensure that polymerization is as complete as possible, but not too high to allow for a smooth manufacturing process. Additionally, the radiation intensity should be high enough to allow for as rapid and complete polymerization as possible, but not too high to avoid damage to the cholesteric liquid crystal medium.

[0353] The curing time depends, inter alia, on the reactivity of the polymerizable material, the thickness of the coating layer, the type of polymerization initiator, and the power of the UV lamp. The curing time is preferably 10 minutes or less, very preferably 5 minutes or less, and most preferably 1 minute or less. Generally, shorter curing times, such as about 60 seconds to 1 second, are preferred for mass production.

[0354] The suitable UV radiation power is preferably 5 to 150 mW cm -2 in the range of 10 to 75 mWcm -2 in the range of 25-60mWcm -2 , especially 45-55mWcm -2 is within the range.

[0355] The polymerization is preferably carried out under an inert gas atmosphere, preferably under a nitrogen atmosphere, although polymerization in air is also possible.

[0356] The polymerization is carried out at a temperature in the range of preferably -10°C to +70°C, more preferably 0°C to +50°C, and even more preferably +15°C to +40°C.

[0357] In a preferred embodiment, the PNLC light modulation element can be further annealed after polymerization at a temperature preferably between 20°C and 140°C, more preferably between 40°C and 130°C, and most preferably between 70°C and 120°C, to reach complete conversion of the monomer and to achieve optimal stability.

[0358] Typically, the structure of a PNLC light-modulating element according to the invention corresponds to a conventional structure for a display known to a person skilled in the art.

[0359] The substrate can be, for example, a glass or quartz sheet, a plastic film, etc. If two substrates are used for curing by actinic radiation, at least one of the substrates must be transparent to the actinic radiation used for polymerization.

[0360] Suitable and preferred plastic substrates include, for example, polyesters such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyvinyl alcohol (PVA), polycarbonate (PC) or triacetyl cellulose (TAC) films, with PET or TAC films being highly preferred. As the birefringent substrate, for example, a uniaxially stretched plastic film can be used. PET films are commercially available, for example, from DuPont Teijin Films under the trade name Melinex®.

[0361] In a preferred embodiment, the substrates are spaced apart from each other by about 1 μm to about 20 μm, preferably from about 3 μm to about 10 μm, more preferably from about 3 μm to about 6 μm, such that the layer of cholesteric LC medium is located in the internal space.

[0362] The substrate layers can be kept at a defined separation from one another, for example, by spacers or protruding structures within the layers. Typical spacer materials are commonly known to experts as spacers, consisting of, for example, plastics, silica, epoxy resins, etc.

[0363] In a further preferred embodiment of the present invention, the layer of the liquid crystal medium is arranged between two flexible layers, for example flexible polymer films. As a result, the corresponding PNLC light modulation element according to the present invention is flexible and bendable, for example, rollable. The flexible layers may represent substrate layers, alignment layers and / or polarizers. Further layers, which are preferably flexible, may also be present. For a more detailed disclosure of a preferred embodiment in which the layer of the liquid crystal medium is arranged between flexible layers, reference is made to the application of US Patent Application Publication No. 2010 / 0045924.

[0364] Furthermore, in order to facilitate electrical switching of the PNLC light-modulating element and make it comparable to the switching of an LC display, electrode arrangements as well as optionally further electrical components are present in the PNLC light-modulating element according to the invention.

[0365] Preferably, the PNLC light modulator comprises an electrode arrangement to which an electric field can be applied, the electrode arrangement being substantially perpendicular to the major planes of the substrates or the cholesteric liquid crystal medium layer. Suitable electrode arrangements or in-plane electrode structures that meet this requirement are generally known to experts.

[0366] For example, the first substrate includes a pixel electrode and a common electrode for generating an electric field substantially parallel to the surface of the first substrate in the pixel region. Various types of displays having at least two electrodes on one substrate are known to those skilled in the art, the most significant difference being that either both the pixel electrode and the common electrode are structured, as is typical in IPS displays, or only the pixel electrode is structured and the common electrode is unstructured, as is typical in FFS displays.

[0367] It should be understood that the present invention refers to any kind of electrode configuration suitable for generating an electric field substantially parallel to the surface of the first substrate in the pixel area mentioned above, i.e. in IPS and FFS displays.

[0368] Suitable electrode materials are usually known to the expert, for example electrode structures made from metals or metal oxides, such as indium tin oxide (ITO), which are preferred according to the invention.

[0369] The ITO film is preferably deposited on the substrate by, for example, physical vapor deposition, electron beam evaporation, or sputtering deposition techniques.

[0370] Preferably, the electrodes of the PNLC light modulating element are associated with a switching element, such as a thin film transistor (TFT) or thin film diode (TFD).

[0371] In a preferred embodiment, the PNLC light modulation element comprises at least one dielectric layer, preferably on the electrode structure. Common dielectric layer materials are generally known to experts, such as SiOx, SiNx, Cytop, Teflon, and PMMA.

[0372] The dielectric layer material can be applied to the substrate or electrode layer by conventional coating techniques, such as spin coating, roll coating, blade coating or vacuum deposition such as PVD or CVD. The dielectric layer material can also be applied by conventional printing techniques known to the expert, such as screen printing, offset printing, reel-to-reel printing, letterpress printing, grating printing, etc. It can also be applied to the substrate or electrode layer by rabure printing, rotogravure printing, flexographic printing, intaglio printing, pad printing, heat seal printing, ink jet printing or printing with a stamp or printing plate.

[0373] In a further preferred embodiment, the PNLC light modulating element comprises at least one alignment layer provided adjacent to the cholesteric LC medium. The PNLC light modulating element may have a further alignment layer in direct contact with the layer of liquid crystal medium.

[0374] In PNLC light modulation elements, a substrate layer is not required since the alignment layer can also function as a substrate layer, if one is further present, in which case the alignment layer is in any case arranged between the substrate layer and the layer of liquid-crystalline medium.

[0375] Preferably, the alignment layer(s) induce a planar alignment throughout the liquid crystal medium.

[0376] Suitable planar alignment layer materials are commonly known to those skilled in the art, such as, for example, AL-3046 or AL-1254, both commercially available from JSR Corporation.

[0377] The alignment layer material can be applied to the substrate array or electrode structure by conventional coating techniques, such as spin coating, roll coating, dip coating or blade coating. The alignment layer material can also be applied by vapor deposition or conventional printing techniques known to the expert, such as screen printing, offset printing, reel-to-reel printing, letterpress printing, gravure printing, rotogravure printing, flexographic printing, intaglio printing, pad printing, heat seal printing, inkjet printing or printing with a stamp or printing plate.

[0378] In a preferred embodiment, the planar alignment layer is treated by rubbing or photoalignment techniques known to those skilled in the art, preferably by rubbing. Therefore, a uniform, preferred direction of the director can be achieved without physical treatment of the cell, such as shearing (mechanical treatment in one direction). The rubbing direction is not important and primarily affects the direction in which the polarizer must be applied. However, a planar alignment layer rubbed antiparallel is preferred. Typically, the rubbing direction is within ±45°, more preferably within ±20°, even more preferably within ±10°, and especially within ±5° relative to the maximum extension of the substrate.

[0379] In a further preferred embodiment of the present invention, the PNLC light modulator optionally comprises two or more polarizers, at least one of which is arranged in one layer of the liquid-crystalline medium and at least one of which is arranged in the opposite layer of the liquid-crystalline medium, the layers of the liquid-crystalline medium and the polarizers being preferably arranged parallel to one another.

[0380] The polarizers can be linear polarizers. Preferably, exactly two polarizers are present in the PNLC light modulation element. In this case, it is even more preferred that both polarizers are linear polarizers. If two linear polarizers are present in the PNLC light modulation element, it is preferred according to the present invention that the polarization directions of the two polarizers cross.

[0381] If two circular polarizers are present in the PNLC light modulation element, it is further preferred that these circular polarizers have the same polarization direction, i.e., both right-handed or both left-handed circular polarizers.

[0382] Polarizers can be reflective or absorptive polarizers. A reflective polarizer in the sense of this application reflects light with one polarization direction or one type of circularly polarized light while transmitting light with another polarization direction or other types of circularly polarized light. Similarly, an absorptive polarizer absorbs light with one polarization direction or one type of circularly polarized light while transmitting light with another polarization direction or other types of circularly polarized light. The reflection or absorption is usually not quantitative, which means that the light passing through the polarizer is not completely polarized.

[0383] For the purpose of the present invention, both absorptive polarizers and reflective polarizers can be used. It is preferable to use a polarizer in the form of a thin optical film. Examples of reflective polarizers that can be used in the PNLC light modulation element according to the present invention are DRPF (Diffuse Reflective Polarizer Film, 3M), DBEF (Dual Brightness Enhancement Film, 3M), DBR (Layered Polymer Distributed Bragg Reflector, as described in U.S. Patent No. 7,038,745 and U.S. Patent No. 6,099,758) and APF (Advanced Polarizing Film, 3M).

[0384] Examples of absorptive polarizers that can be used in the PNLC light modulator according to the present invention are the Itos XP38 polarizing film and the Nitto Denko GU-1220DUN polarizing film. An example of a circular polarizer that can be used in the present invention is the APNCP37-035-STD polarizer (American Polarizers). Another example is the CP42 polarizer (ITOS). The PNLC light modulator may further include a filter that blocks light of a specific wavelength, such as a UV filter. According to the present invention, additional functional layers, such as a protective film, a heat insulating film, or a metal oxide layer, may also be present.

[0385] The functional principle of the PNLC light modulation element according to the invention is explained in detail below. It should be noted that no limitations on the scope of the claimed invention that are not present in the claims can be derived from the discussion of the envisaged ways of functioning.

[0386] In a first preferred embodiment, the retardation or phase change of the PNLC light modulation element according to the present invention depends on the applied electric field, preferably with gradually increasing applied electric fields, the retardation gradually increases.

[0387] In this preferred embodiment, polymerizable components A and B are selected independently so that the birefringence of component A matches the birefringence of component B. Preferably, the difference between the values ​​for birefringence is less than 10%, more preferably less than 5%, and even more preferably less than 3%.

[0388] The required applied field strength depends mainly on the electrode gap and the Δε coefficient of the LC mixture. Generally, the applied field strength is approximately 50 V / μm. -1 Lower, preferably around 30 V / μm -1 Lower, preferably around 25V / μm -1 In particular, the applied electric field strength is 1V / μm -1 ~20V / μm -1 is within the range.

[0389] Preferably, the drive voltage applied to switch the PNLC light modulation element should be as low as possible. In general, the applied drive voltage is in the range of 2 V to approximately 200 V, more preferably in the range of approximately 5 V to approximately 10 V.

[0390] In this first preferred embodiment, the retardation change or phase change (Γ) is given according to the following formula:

[0391]

number

[0392] where d is the layer thickness of the applied liquid crystal medium, λ is the wavelength of the incident light, n eff is the effective birefringence induced by the reorientation of the LC in the applied electric field.

[0393] In a second preferred embodiment, the PNLC light modulation element according to the present invention has a boundary state A and a boundary state B.

[0394] The PNLC light modulator preferably has a transmittance T A At this point, the hologram has a boundary state A, the so-called "off state" or transparent state.

[0395] The PNLC light-modulating element preferably has another boundary state B, the so-called "on state" or opaque state, when an electric field is applied, whereby T A >T B This becomes:

[0396] In this second preferred embodiment, components A and B are selected dependently on one another such that the birefringence of polymerizable component A differs from the birefringence of component B. Preferably, the difference in the values ​​for birefringence is greater than 3%, more preferably greater than 5%, and even more preferably greater than 10%.

[0397] The required applied field strength depends mainly on the electrode gap and the Δε coefficient of the LC mixture. Generally, the applied field strength is approximately 50 V / μm. -1 Lower, preferably around 30 V / μm -1 Lower, preferably around 25V / μm -1 In particular, the applied electric field strength is 1V / μm -1 ~20V / μm -1 is within the range.

[0398] Preferably, the drive voltage applied to switch the PNLC light modulation element should be as low as possible. In general, the applied drive voltage is in the range of 2 V to approximately 200 V, more preferably in the range of approximately 3 V to approximately 100 V, and even more preferably in the range of approximately 5 V to approximately 50 V.

[0399] The change in transmittance is governed by the strength of the applied electric field. Applying a stronger electric field to the system increases the degree of scattering, reducing the intensity of forward-propagating light and increasing the amount of light emitted in other directions. Thus, for a side-illuminated device, increasing the applied electric field intensity increases the amount of light seen in the direction perpendicular to the illumination direction.

[0400] As described above, the PNLC light modulation element of the present invention can be used in various optical and electro-optical devices. Accordingly, the present invention is also directed to the use of the PNLC light modulation element as described above in optical and electro-optical devices, and to optical and electro-optical devices comprising the PNLC light modulation element of the present invention.

[0401] The optical and electro-optical devices include, without limitation, electro-optical displays, liquid crystal displays (LCDs), non-linear optical (NLO) devices, optical information recording devices, optical shutters, smart windows, privacy windows, lenses, virtual reality devices, and augmented reality devices.

[0402] It will be understood that many of the features described above, particularly the preferred embodiments, are inventive in their own right and are not merely part of the embodiments of the present invention, for which independent protection may be sought in addition to or instead of the claimed invention.

[0403] It is understood that modifications can be made to the embodiments of the invention described above while still falling within the scope of the invention. Unless otherwise stated, each feature disclosed herein may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless otherwise stated, each feature disclosed is merely an example of a generic series of equivalent or similar features.

[0404] All features disclosed herein may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. In particular, preferred features of the invention are applicable to all aspects of the invention and can be used in any combination. Similarly, features described in non-essential combinations can be used individually (not in combination).

[0405] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Accordingly, the following examples are to be construed as merely illustrative. These should be interpreted as meaning only, and do not limit the remainder of the disclosure in any way whatsoever.

[0406] All parameter ranges given in this application include limits that include the maximum acceptable error known to those skilled in the art. The different upper and lower limits given for the various ranges of properties combined with each other result in further preferred ranges.

[0407] In this application, and particularly in the following examples, the structures of liquid crystal compounds are represented by abbreviations, also called "acronyms." The conversion of the abbreviations to the corresponding structures is simply according to Tables A to C. Table A lists the symbols used for ring elements, Table B lists the symbols for linking groups, and Table C lists the symbols for the left- and right-hand terminal groups of the molecule.

[0408] All groups C n H 2n+1 , C m H 2m+1 and C I H2 I+1 are preferably linear alkyl groups having n, m and 1 C atoms, respectively, and all groups C n H 2n , C m H 2m and C I H 2I are preferably each (CH) n , (CH2) m and (CH2) I and each -CH=CH- is preferably trans-E vinylene.

[0409] <Table A: Ring elements>

[0410] [Table 1]

[0411] [Table 2]

[0412] [Table 3]

[0413] <Table B: Linking group>

[0414] [Table 4]

[0415] <Table C: Terminal group>

[0416] [Table 5]

[0417] [Table 6]

[0418] In the table, n and m are each integers, and the three dots "..." indicate space for other symbols in this table. [Example]

[0419] <Compound>

[0420] <Polymerizable liquid crystal compound used - component A)>

[0421] [ka]

[0422] <Host mixture used - component B)>

[0423] [Table 7]

[0424] <Chiral compound used - component C)>

[0425] [ka]

[0426] <Test cell>

[0427] <Test cell 1> VHR AL16301 type Cell gap = 6 μm, no spacer Cell type: Anti-parallel planar aligned PI Electrode structure: ITO = 200A, 1cm x 1cm square pattern

[0428] <Test cell 2> VHR AL16301 type Cell gap = 6 μm, no spacer Cell type: Anti-parallel planar aligned PI Electrode structure: ITO = 200A, 1cm x 1cm square pattern

[0429] <Method>

[0430] <Switch speed measurement> The switching time is recorded using either a microscope or a 632.8 nm HeNe laser, with the sample placed between crossed polarizers. The transmitted light is received by an oscilloscope in the case of the microscope, or by a photodiode connected to a data acquisition board in the case of the laser. The switching time is obtained from the oscilloscope or by analyzing the data acquired from the data acquisition board.

[0431] <Haze> The level of haze is determined according to the definition of haze in the ASTM D1003 standard.

[0432] Four different transmittance measurements (T1-T4) commonly known to those skilled in the art are performed. T1: Transmittance without sample and white reflectance standard T2: Transmittance with sample and white reflective standard T3: Transmittance with light trap and no sample T4: Transmittance with a light trap and sample

[0433] As is commonly known to those skilled in the art, total transmittance (T2) is thereby defined as the sum of the specular transmittance and the diffuse transmittance (T4).

[0434] Thereby, haze is defined as follows: Haze = [(T4 / T2)-(T3 / T1)] x 100%.

[0435] Haze data is taken from only the active area of ​​the cell, with the adhesive masked from the measurement system to avoid discrepancies.

[0436] <Example>

[0437] <Experiment 1> Cholesteric LC mixtures are prepared as given in the table below. The corresponding mixtures are capillary filled into test cell 1 using capillary action at room temperature, annealed at 100°C for 1 hour, and then irradiated with linearly polarized UV light (35 mW / cm) at the same temperature. 2 ) for a predetermined time. The cell is then cooled to room temperature.

[0438] V op , t on and t off was measured using a rapid electro-optical microscope setup.

[0439] The % haze was measured in transmission mode on a Shimadzu 3600 UV-Vis at a single wavelength of 550 nm. op was determined when the maximum % haze was achieved. on and T off was taken as the time when the switch between 10% and 90% switched. The results are summarized in the table below.

[0440] [Table 8]

[0441] As can be seen from above, chiral systems allow for better haze levels to be achieved compared to non-chiral systems (see Experiment 1.1). Importantly, compared to systems without polymer networks, the polymer network chiral systems achieve a higher haze level. off The time is dramatically reduced (see Experiment 1.2), indicating good relaxation to a well-ordered state.

[0442] <Experiment 2> Cholesteric LC mixtures are prepared as given in the table below. The corresponding mixtures are capillary filled into test cell 2 using capillary action at room temperature, annealed at 100°C for 1 hour, and then irradiated with linearly polarized UV light (35 mW / cm) at the same temperature. 2 ) for a predetermined time. The cell is then cooled to room temperature.

[0443] V op , t on and t off was measured using a rapid electro-optical microscope setup.

[0444] The % haze was measured in transmission mode on a Shimadzu 3600 UV-Vis at a single wavelength of 550 nm. op was determined when the maximum % haze was achieved. on and T off was taken as the time when the switch between 10% and 90% switched. The results are summarized in the table below.

[0445] [Table 9]

[0446] As can be seen from above, the reduced cell thickness compared to the thicker cell as given in Experiment 1 is V op This also slightly reduces the maximum % haze that can be achieved.

Claims

1. A cholesteric LC medium for a PNLC light modulator, comprising: A) one or more polymerizable compounds in an amount of 2% to 10% by weight, with at least one of the compounds being selected from the compounds of formulae I1-1-1 to I2-1-18 (note that the compounds of formulae I1-1-1 to I2-1-18 are limited to the compounds described in [Chemical Formula 1] to [Chemical Formula 5], but polymerizable component A) may also include other compounds); 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 (In the formula, all groups P are identical and represent either an acrylate or a methacrylate group; Sp is -(CH ２ ) ｐ１ -, -(CH ２ ) ｐ１ -O-, -(CH ２ ) ｐ１ —O—CO— or —(CH ２ ) ｐ１ -CO-O-, where p1 is an integer from 1 to 6, and the O or CO group is linked to the benzene ring; L ａ , L b and L′ are each independently F, CH ３ , C.H. ２ CH ３ , OCH ３ , O.C. ２ H ５ , O(CH ２ ) ２ CH ３ , OC(CH ３ ) ３ or OCF ３ Represents.) and B) a liquid crystal component B) comprising one or more non-polymerizable mesogenic or liquid crystal compounds selected from compounds of formula A and / or B in a total concentration of 2 to 60% by weight and having a dielectric anisotropy (Δε) in the range of 5 to 20; 【Transformation 6】 wherein the individual radicals, each independently of one another, have the following meanings, which may be the same or different at each occurrence: 【Transformation 7】 and R ２１ , R ３１ are each independently of one another alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which may be fluorinated, X ０ is F, Cl, a halogenated alkyl or alkoxy having 1 to 6 C atoms or a halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, Z ３１ is -CH ２ CH ２ -, -CF ２ CF ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ O— or a single bond, L ２１ , L ２２ , L ３１ and L ３２ are each independently H or F, g is 0, 1, 2 or 3. and C) one or more chiral compounds in a total concentration of 0.1 to 0.9 wt. %; Including, However, liquid crystal component B) contains at least one compound selected from the group consisting of PGUQU-n-F, CPU-n-F, and PGU-n-F as compounds of formulae A and B (provided that liquid crystal component B) may also contain other compounds of formulae A and B as long as it contains at least one of these compounds). 【Transformation 8】 (In the formula, n is an integer from 1 to 9.) However, the liquid crystal component B) contains, as the compound of formula B, one or more compounds of formula PP-n-N, 【Chemistry 9】 (In the formula, n is an integer from 1 to 9.) Cholesteric LC medium.

2. One or more chiral compounds may be used alone or in combination with each other. －１ The absolute value of the helical twisting power (|HTP ｔｏｔａｌ 2. Cholesteric LC medium according to claim 1, wherein |

3. 3. Cholesteric LC medium according to claim 1, wherein the polymerizable compound is selected from the compounds of the formulae I1-1-1, I1-1-3, I1-2-2 and I2-1-1 to I2-1-6

4. Polymerizable component A) comprises one or more polymerizable compounds selected from formulae I1-1-1, I1-1-3, I1-2-2, or I2-1-1 to I2-1-6, liquid crystal component B) comprises one or more compounds of the formula PGUQU-n-F, one or more compounds of the formula CPU-n-F, one or more compounds of the formula PGU-n-F and one or more compounds of the formula PP-n-N, Cholesteric LC medium according to any one of claims 1 to 3.

5. Cholesteric LC medium according to any one of claims 1 to 4, wherein the total concentration of compounds of the formulae A and B is in the range from 4 to 50% by weight.

6. Cholesteric LC medium according to any one of claims 1 to 5, wherein at least one chiral compound is R-5011. 【Chemistry 10】

7. 7. A method for producing a cholesteric LC medium according to any one of claims 1 to 6, comprising at least the step of mixing a non-polymerizable compound and a chiral compound with 2 wt. % to 10 wt. % of a polymerizable LC compound.

8. Use of a cholesteric LC medium according to any one of claims 1 to 6 in a PNLC light modulator element.

9. 1. A PNLC light modulation element comprising a pair of opposing substrates, an in-plane electrode structure, and a cholesteric LC medium located in the space between the substrates, PNLC light modulation element, characterized in that it comprises a polymer network obtainable from a cholesteric LC medium according to any one of claims 1 to 6 by exposing said cholesteric LC medium to actinic radiation which induces photopolymerization of polymerizable compounds in the cholesteric LC medium.

10. 10. The PNLC light modulation element of claim 9, comprising an electrode structure corresponding to an IPS or FFS electrode structure.

11. 11. The PNLC light modulation element according to claim 9, wherein the distance between the two opposing substrates is in the range of 1 to 20 μm.

12. A method for manufacturing the PNLC light modulation element according to any one of claims 9 to 11, comprising the steps of: - cutting and cleaning the substrate; - providing an in-plane electrode structure on one of the substrates; Optionally, providing an alignment layer on the electrode structure; - assembling the cells; - filling a cell with a cholesteric LC medium according to any one of claims 1 to 6, and exposing the cholesteric LC medium to actinic radiation that induces photopolymerization of the polymerizable compound in the cholesteric LC medium; The method includes at least the following.

13. The method of claim 12, wherein the photopolymerization step is carried out with light having a wavelength in the range of 250 to 450 nm.

14. The photopolymerization process is performed at 5 to 150 mW / cm ２ 14. The method according to claim 12 or 13, which is carried out at a radiation intensity in the range of

15. Use of a PNLC light modulation element according to any one of claims 9 to 11 in an optical or electro-optical device.

16. An optical or electro-optical device comprising a PNLC light modulation element according to any one of claims 9 to 11.

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