Patent Application
20170037316
The present invention relates to a liquid-crystalline medium (LC medium), to the use thereof for electro-optical purposes, and to LC displays containing this medium.
Liquid crystals are used principally as dielectrics in display devices, since the optical properties of such substances can be modified by an applied voltage. Electro-optical devices based on liquid crystals are extremely well known to the person skilled in the art and can be based on various effects. Examples of such devices are cells having dynamic scattering, DAP (deformation of aligned phases) cells, guest/host cells, TN cells having a “twisted nematic” structure, STN (“super-twisted nematic”) cells, SBE (“super-birefringence effect”) cells and OMI (“optical mode interference”) cells. The commonest display devices are based on the Schadt-Helfrich effect and have a twisted nematic structure. In addition, there are also cells which work with an electric field parallel to the substrate and liquid-crystal plane, such as, for example, IPS (“in-plane switching”) cells. TN, STN, FFS (fringe field switching) and IPS cells, in particular, are currently commercially interesting areas of application for the media according to the invention.
The liquid-crystal materials must have good chemical and thermal stability and good stability to electric fields and electromagnetic radiation. Furthermore, the liquid-crystal materials should have low viscosity and produce short addressing times, low threshold voltages and high contrast in the cells.
They should furthermore have a suitable mesophase, for example a nematic or cholesteric mesophase for the above-mentioned cells, at the usual operating temperatures, i.e. in the broadest possible range above and below room temperature. Since liquid crystals are generally used as mixtures of a plurality of components, it is important that the components are readily miscible with one another. Further properties, such as the electrical conductivity, the dielectric anisotropy and the optical anisotropy, have to satisfy various requirements depending on the cell type and area of application. For example, materials for cells having a twisted nematic structure should have positive dielectric anisotropy and low electrical conductivity.
For example, for matrix liquid-crystal displays with integrated non-linear elements for switching individual pixels (MLC displays), media having large positive dielectric anisotropy, broad nematic phases, relatively low birefringence, very high specific resistance, good UV and temperature stability and low vapour pressure are desired.
Matrix liquid-crystal displays of this type are known. Examples of non-linear elements which can be used to individually switch the individual pixels are active elements (i.e. transistors). The term “active matrix” is then used, where a distinction can be made between two types:
1. MOS (metal oxide semiconductor) or other diodes on silicon wafers as substrate.
2. Thin-film transistors (TFTs) on a glass plate as substrate.
The use of single-crystal silicon as substrate material restricts the display size, since even modular assembly of various part-displays results in problems at the joints.
In the case of the more promising type 2, which is preferred, the electro-optical effect used is usually the TN effect. A distinction is made between two technologies: TFTs comprising compound semiconductors, such as, for example, CdSe, or TFTs based on polycrystalline or amorphous silicon. Intensive work is being carried out worldwide on the latter technology.
The TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries the transparent counterelectrode on its inside. Compared with the size of the pixel electrode, the TFT is very small and has virtually no adverse effect on the image. This technology can also be extended to fully color-capable displays, in which a mosaic of red, green and blue filters is arranged in such a way that a filter element is opposite each switchable pixel.
The TFT displays usually operate as TN cells with crossed polarizers in transmission and are backlit.
The term MLC displays here encompasses any matrix display with integrated non-linear elements, i.e., besides the active matrix, also displays with passive elements, such as varistors or diodes (MIM=metal-insulator-metal).
MLC displays of this type are particularly suitable for TV applications (for example pocket televisions) or for high-information displays for computer applications (laptops) and in automobile or aircraft construction. Besides problems regarding the angle dependence of the contrast and the response times, difficulties also arise in MLC displays due to insufficiently high specific resistance of the liquid-crystal mixtures [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, September 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, September 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 ff., Paris]. With decreasing resistance, the contrast of an MLC display deteriorates, and the problem of after-image elimination may occur. Since the specific resistance of the liquid-crystal mixture generally drops over the life of an MLC display owing to interaction with the interior surfaces of the display, a high (initial) resistance is very important in order to obtain acceptable lifetimes. In particular in the case of low-volt mixtures, it was hitherto impossible to achieve very high specific resistance values. It is furthermore important that the specific resistance exhibits the smallest possible increase with increasing temperature and after heating and/or UV exposure. The low-temperature properties of the mixtures from the prior art are also particularly disadvantageous. It is demanded that no crystallization and/or smectic phases occur, even at low temperatures, and the temperature dependence of the viscosity is as low as possible. The MLC displays from the prior art thus do not satisfy today's requirements.
Besides liquid-crystal displays which use backlighting, i.e. are operated transmissively and if desired transflectively, reflective liquid-crystal displays are also particularly interesting. These reflective liquid-crystal displays use the ambient light for information display. They thus consume significantly less energy than backlit liquid-crystal displays having a corresponding size and resolution. Since the TN effect is characterized by very good contrast, reflective displays of this type can even be read well in bright ambient conditions. This is already known of simple reflective TN displays, as used, for example, in watches and pocket calculators. However, the principle can also be applied to high-quality, higher-resolution active matrix-addressed displays, such as, for example, TFT displays. Here, as already in the transmissive TFT-TN displays which are generally conventional, the use of liquid crystals of low birefringence (Δn) is necessary in order to achieve low optical retardation (d·Δn). This low optical retardation results in usually acceptably low viewing-angle dependence of the contrast (cf. DE 30 22 818). In reflective displays, the use of liquid crystals of low birefringence is even more important than in transmissive displays since the effective layer thickness through which the light passes is approximately twice as large in reflective displays as in transmissive displays having the same layer thickness.
For TV and video applications, displays having fast response times are required in order to be able to reproduce multimedia content, such as, for example, films and video games, in near-realistic quality. Such short response times can be achieved, in particular, if liquid-crystal media having low values for the viscosity, in particular the rotational viscosity γ1, and having high optical anisotropy (Δn) are used.
In order to achieve 3D effects by means of shutter spectacles, use is made of, in particular, fast-switching mixtures having low rotational viscosities and correspondingly high optical anisotropy (Δn). Electro-optical lens systems by means of which a 2-dimensional representation of a display can be converted into a 3-dimensional autostereoscopic representation can be achieved using mixtures having high optical anisotropy (Δn).
In the case of TN (Schadt-Helfrich) cells, media are desired which facilitate the following advantages in the cells:
The media available from the prior art do not enable these advantages to be achieved while simultaneously retaining the other parameters.
In the case of supertwisted (STN) cells, media are desired which facilitate greater multiplexability and/or lower threshold voltages and/or broader nematic phase ranges (in particular at low temperatures). To this end, a further widening of the available parameter latitude (clearing point, smectic-nematic transition or melting point, viscosity, dielectric parameters, elastic parameters) is urgently desired.
One of the most important properties of modern LCDs is correct reproduction of moving images. If the response speed of the liquid-crystalline medium used is too slow, this causes undesired artefacts in the display of such content. The physical parameters which essentially determine the response time of a liquid-crystal mixture are the rotational viscosity γ1 and the elastic constants. The latter are also particularly important for ensuring a good black state of the LCD. In general, however, it is observed that the clearing point of the mixture and thus the rotational viscosity of the mixture is also increased with an increase in the elastic constants, meaning that an improvement in the response time is not possible. In particular in the case of LC displays for TV and video applications (for example LCD TVs, monitors, PDAs, notebooks, games consoles), a significant reduction in the response times is desired. A reduction in the layer thickness d (“cell gap”) of the LC medium in the LC cell theoretically results in faster response times, but requires LC media having higher birefringence Δn in order to ensure an adequate optical retardation (dΔn). However, the LC materials of high birefringence known from the prior art generally also have high rotational viscosity at the same time, which in turn has an adverse effect on the response times.
There is thus still a great need for liquid-crystalline media having good reliability properties, such as, for example, high VHR (voltage holding ratio), which do not exhibit these properties or only do so to a lesser extent.
The invention is based on the object of providing media, in particular for MLC, TN, STN, OCB, positive VA, FFS, HB (=high brightness)-FFS, PS (=polymer stabilized)-FFS, IPS, PS-IPS displays of this type, which have the desired properties indicated above and do not exhibit the disadvantages indicated above or only do so to a reduced extent. In particular, the LC media should have fast response times and low rotational viscosities at the same time as relatively high birefringence. In addition, the LC media should have a high clearing point and very good low-temperature stability (LTS).
It has now been found that this object can be achieved if LC media comprising one or more compounds of the formula I are used.
The invention relates to a liquid-crystalline medium, characterized in that it comprises one or more compounds of the formula I,
in which
in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, and
The compounds of the formula I lead to LC mixtures having the desired properties indicated above, in particular in LC mixtures having very low rotational viscosity. The mixtures according to the invention have very large elastic constants and thus facilitate very good response times. Furthermore, the mixtures according to the invention are stable at at least −20° C. and exhibit no tendency towards crystallization. The rotational viscosities γ1 are generally <120 mPa·s. Furthermore, the mixtures according to the invention are distinguished by a very good ratio of rotational viscosity γ1 and clearing point, low γ1/K11 values, which lead to faster response times, as well as a high clearing point and a broad nematic phase range. Furthermore, the compounds of the formula I are readily soluble in liquid-crystalline media.
The compounds of the formula I have a broad range of applications and are distinguished, in particular, by their very large elastic constants. Depending on the choice of substituents, they can serve as base materials of which liquid-crystalline media are predominantly composed; however, liquid-crystalline base materials from other classes of compound can also be added to the compounds of the formula I in order, for example, to influence the dielectric and/or optical anisotropy of a dielectric of this type and/or to optimise its threshold voltage and/or its rotational viscosity. The result are LC mixtures according to the invention which support a good black state of the display, which is crucial for the contrast of the display, owing to high elastic constants and at the same time facilitate very good response times.
R1 in the compounds of the formula I and the sub-formulae preferably denotes a straight-chain alkyl radical, in particular having 3-5 C atoms. In a further preferred embodiment, one or more CH2 groups in the alkyl radical may also be replaced by —CH═CH—.
Particularly preferred compounds of the formula I are shown below:
in which R1 has the meanings indicated in claim 1, preferably straight-chain alkyl or alkenyl having up to 5 C atoms, and “alkyl” denotes a straight-chain alkyl radical having 1-5 C atoms.
Very particular preference is given to the compounds of the formulae I-1, I-2 and I-5.
Very particularly preferred compounds are shown below:
In the compounds of the formulae I-5a to I-5k, alkyl particularly preferably denotes CH3 or C2H5., in particular CH3.
In the pure state, the compounds of the formula I are colorless and form liquid-crystalline mesophases in a temperature range which is favourably located for electro-optical use. They are stable chemically, thermally and to light.
The compounds of the formula I are prepared by methods known per se, as described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and suitable for the said reactions. Use can also be made here of variants known per se which are not mentioned here in greater detail. The compounds of the formula I can be prepared, for example, as follows:
If R1 in the compounds of the formula I above and below denotes an alkyl radical and/or an alkoxy radical, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6, or 7 C atoms and accordingly preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradedoxy.
Oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxaheptyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6-, or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadexyl.
If R1 denotes an alkyl radical in which one CH2 group has been replaced by —CH═CH—, this may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Accordingly, it denotes, in particular, vinyl, prop-1-, or prop-2-enyl, but-1-, 2- or but-3-enyl, pent-1-, 2-, 3- or pent-4-enyl, hex-1-, 2-, 3-, 4- or hex-5-enyl, hept-1-, 2-, 3-, 4-, 5- or hept-6-enyl, oct-1-, 2-, 3-, 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, dec-1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyl. These radicals may also be mono- or polyhalogenated.
If R1 denotes an alkyl or alkenyl radical which is at least monosubstituted by halogen, this radical is preferably straight-chain and halogen is preferably F or Cl. In the case of polysubstitution, halogen is preferably F. The resultant radicals also include perfluorinated radicals. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω position.
X1 preferably denotes an alkyl radical, in particular CH3, and CF3, furthermore OCF3.
The present invention likewise relates to the compounds of the formula I and sub-formulae thereof.
Preferred embodiments of the liquid-crystal mixtures according to the invention are indicated below:
each, independently of one another, denote
each, independently of one another, denote
in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,
Of the compounds of the formula N, particular preference is given to the compounds of the formulae N-1, N-2, N-3, N-4, N-8, N-9, N-14, N-15, N-17, N-18, N-19, N-20, N-21, N-22, N-23, N-24, N-25, N-31, N-33 and N-36.
in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,
preferably denotes
It has been found that even a relatively small proportion of compounds of the formula I mixed with conventional liquid-crystal materials, but in particular with one or more compounds of the formulae II to XXVIII, results in a clear reduction in the switching-time parameter γ1/K1. The liquid-crystalline medium according to the invention is furthermore distinguished by its relatively high values for the birefringence and by its light stability. At the same time, the mixtures exhibit very good values for the VHR after exposure to UV.
The expression “alkyl” or “alkyl*” in this application encompasses straight-chain and branched alkyl groups having 1-7 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups having 1-6 carbon atoms are generally preferred.
The expression “O-alkyl” in this application encompasses straight-chain and branched alkoxy groups.
The expression “alkenyl” or “alkenyl*” in this application encompasses straight-chain and branched alkenyl groups having 2-7 carbon atoms, in particular the straight-chain groups. Preferred alkenyl groups are C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, C5-C7-4-alkenyl, C6-C7-5-alkenyl and C7-6-alkenyl, in particular C2-C7-1E-alkenyl, C4-C7-3E-alkenyl and C5-C7-4-alkenyl. Examples of particularly preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5 carbon atoms are generally preferred.
The expression “fluoroalkyl” in this application encompasses straight-chain groups having at least one fluorine atom, preferably a terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, other positions of the fluorine are not excluded.
The expression “oxaalkyl” or “alkoxy” in this application encompasses straight-chain radicals of the formula CnH2n+1—O—(CH2)m, in which n and m each, independently of one another, denote 1 to 6. m may also denote 0. Preferably, n=1 and m=I-6 or m=0 and n=I-3.
Through a suitable choice of the meanings of R1 and R2 in formula I, the addressing times, the threshold voltage, the steepness of the transmission characteristic lines, etc., can be modified in the desired manner. For example, 1E-alkenyl radicals, 3E-alkenyl radicals, 2E-alkenyloxy radicals and the like generally result in shorter addressing times, improved nematic tendencies and a higher ratio between the elastic constants k33 (bend) and k11 (splay) compared with alkyl and alkoxy radicals. 4-Alkenyl radicals, 3-alkenyl radicals and the like generally give lower threshold voltages and lower values of k33/k11 compared with alkyl and alkoxy radicals. The mixtures according to the invention are distinguished, in particular, by high K1 values and thus have significantly faster response times than the mixtures from the prior art.
The optimum mixing ratio of the compounds of the above-mentioned formulae depends substantially on the desired properties, on the choice of the components of the above-mentioned formulae and on the choice of any further components that may be present.
Suitable mixing ratios within the range indicated above can easily be determined from case to case.
The total amount of compounds of the above-mentioned formulae in the mixtures according to the invention is not crucial. The mixtures can therefore comprise one or more further components for the purposes of optimization of various properties. However, the observed effect on the desired improvement in the properties of the mixture is generally greater, the higher the total concentration of compounds of the above-mentioned formulae.
In a particularly preferred embodiment, the media according to the invention comprise compounds of the formulae IV to VIII in which X0 denotes F, OCF3, OCHF2, OCH═CF2, OCF═CF2 or OCF2—CF2H. A favourable synergistic action with the compounds of the formula I results in particularly advantageous properties. In particular, mixtures comprising compounds of the formulae I and VI, or I and XI, or I and VI and XI are distinguished by their low threshold voltages.
The individual compounds of the above-mentioned formulae and the sub-formulae thereof which can be used in the media according to the invention are either known or can be prepared analogously to the known compounds.
The invention also relates to electro-optical displays, such as, for example, TN, STN, TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive VA or MLC displays, having two plane-parallel outer plates, which, together with a frame, form a cell, integrated non-linear elements for switching individual pixels on the outer plates, and a nematic liquid-crystal mixture having positive dielectric anisotropy and high specific resistance located in the cell, which contain media of this type, and to the use of these media for electro-optical purposes.
Furthermore, the mixtures according to the invention are also suitable for positive VA applications, also referred to as HT-VA applications. These are taken to mean electro-optical displays having an in-plane drive electrode configuration and homeotropic arrangement of the liquid-crystal medium having positive dielectric anisotropy. The mixtures according to the invention are particularly preferably suitable for TN-TFT display applications having a low operating voltage, i.e. particularly preferably for notebook applications.
The liquid-crystal mixtures according to the invention enable a significant broadening of the available parameter latitude. The achievable combinations of clearing point, rotational viscosity and elastic constants, thermal and UV stability and high optical anisotropy are far superior to previous materials from the prior art.
The mixtures according to the invention are particularly suitable for mobile applications and high-Δn TFT applications, such as, for example, PDAs, notebooks, LCD TVs and monitors.
The liquid-crystal mixtures according to the invention, while retaining the nematic phase down to −20° C. and preferably down to −30° C., particularly preferably down to −40° C., and the clearing point ≧70° C., preferably 74° C., at the same time allow rotational viscosities γ1 of ≦120 mPa·s, particularly preferably 60 mPa·s, to be achieved, enabling excellent MLC displays having fast response times to be achieved.
The dielectric anisotropy Δ∈ of the liquid-crystal mixtures according to the invention is preferably ≧+2, particularly preferably ≧+4.
The birefringence Δn of the liquid-crystal mixtures according to the invention is preferably ≧0.08, in particular ≧0.10.
The nematic phase range of the liquid-crystal mixtures according to the invention preferably has a width of at least 90°, in particular at least 100°. This range preferably extends at least from −20° C. to +70° C.
If the mixtures according to the invention are used in IPS or FFS applications, the mixtures preferably have a dielectric anisotropy value of 2-30 and an optical anisotropy value of 0.07-0.13.
It goes without saying that, through a suitable choice of the components of the mixtures according to the invention, it is also possible for higher clearing points (for example above 100° C.) to be achieved at higher threshold voltages or lower clearing points to be achieved at lower threshold voltages with retention of the other advantageous properties. At viscosities correspondingly increased only slightly, it is likewise possible to obtain mixtures having higher Δ∈ and thus low thresholds. The MLC displays according to the invention preferably operate at the first Gooch and Tarry transmission minimum [C. H. Gooch and H. A. Tarry, Electron. Lett. 10, 2-4, 1974; C. H. Gooch and H. A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], where, besides particularly favourable electro-optical properties, such as, for example, high steepness of the characteristic line and low angle dependence of the contrast (German patent 30 22 818), lower dielectric anisotropy is sufficient at the same threshold voltage as in an analogous display at the second minimum. This enables significantly higher specific resistance values to be achieved using the mixtures according to the invention at the first minimum than in the case of mixtures comprising cyano compounds. Through a suitable choice of the individual components and their proportions by weight, the person skilled in the art is able to set the birefringence necessary for a pre-specified layer thickness of the MLC display using simple routine methods.
The construction of the MLC display according to the invention from polarizers, electrode base plates and surface-treated electrodes corresponds to the usual design for displays of this type. The term usual design is broadly drawn here and also encompasses all derivatives and modifications of the MLC display, in particular including matrix display elements based on poly-Si TFTs or MIM.
A significant difference between the displays according to the invention and the hitherto conventional displays based on the twisted nematic cell consists, however, in the choice of the liquid-crystal parameters of the liquid-crystal layer.
The liquid-crystal mixtures which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing one or more compounds of the formula I with one or more compounds of the formulae II-XXVII or with further liquid-crystalline compounds and/or additives. In general, the desired amount of the components used in the smaller amount is dissolved in the components making up the principal constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing.
The dielectrics may also comprise further additives known to the person skilled in the art and described in the literature, such as, for example, UV stabilizers, such as Tinuvin® from Ciba Chemicals, in particular Tinuvin® 770, antioxidants, free-radical scavengers, nanoparticles, etc. For example, 0-15% of pleochroic dyes or chiral dopants can be added. Suitable stabilizers and dopants are mentioned below in Tables C and D.
In order to increase the anchoring force, polymerizable compounds, so-called “reactive mesogens”, may also additionally be added to the mixtures according to the invention. Preferred polymerizable compounds are listed in Table E.
The following examples are intended to explain the invention without limiting it. Above and below, percentage data denote percent by weight; all temperatures are indicated in degrees Celsius.
Throughout the patent application, 1,4-cyclohexylene rings and 1,4-phenylene rings are represented as follows:
The cyclohexylene rings are trans-1,4-cyclohexylene rings.
Throughout the patent application and in the working examples, the structures of the liquid-crystal compounds are indicated by means of acronyms. Unless indicated otherwise, the transformation into chemical formulae takes place in accordance with Tables I-3. All radicals CnH2n+1, CmH2m+1 and Cm′H2m′+1 or CnH2n and CmH2m are straight-chain alkyl radicals or alkenyl radicals respectively, in each case having n, m, m′ or z C atoms; n, m, m′ and z each, independently of one another, denote 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1, 2, 3, 4, 5 or 6. In Table 1 the ring elements of the respective compound are coded, in Table 2 the bridging members are listed and in Table 3 the meanings of the symbols for the left-hand and right-hand side chains of the compounds are indicated.
Preferred mixture components are shown in Tables A and B.
Particular preference is given to liquid-crystalline mixtures which, besides the compounds of the formula I, comprise at least one, two, three, four or more compounds from Table B.
Table C indicates possible dopants which are generally added to the mixtures according to the invention. The mixtures preferably comprise 0-10% by weight, in particular 0.001-5% by weight and particularly preferably 0.001-3% by weight, of dopants.
In a preferred embodiment, the mixtures according to the invention comprise one or more polymerizable compounds, preferably selected from the polymerizable compounds of the formulae RM-1 to RM-94. Media of this type are particularly suitable for PS-FFS and PS-IPS applications. Of the reactive mesogens mentioned in Table E, compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-11, RM-17, RM-35, RM-41, RM-44, RM-62, RM-81 and RM-99 are particularly preferred.
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. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.
The entire disclosures of all applications, patents and publications, cited herein and of corresponding German application No. 10 2015 009 955.8, filed Aug. 5, 2015, are incorporated by reference herein.
The electro-optical data are measured in a TN cell at the 1st minimum (i.e. at a d·Δn value of 0.5 μm) at 20° C., unless expressly indicated otherwise. The optical data are measured at 20° C., unless expressly indicated otherwise. All physical properties are determined in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals” Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20° C., unless explicitly indicated otherwise.
Liquid-crystalline mixture M26 is additionally stabilized with 300 ppm of the compound of the formula ST-2
300 ppm of
Liquid-crystalline mixture M27 is additionally stabilized with 300 ppm of the compound of the formula ST-2
300 ppm of
Liquid-crystalline mixture M28 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and 1000 ppm of the compound of the formula ST-2
400 ppm of
and
1000 ppm of
Liquid-crystalline mixture M29 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and 1000 ppm of the compound of the formula ST-2
400 ppm of
and
1000 ppm of
Liquid-crystalline mixture M30 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and 1000 ppm of the compound of the formula ST-2
400 ppm of
and
1000 ppm of
Liquid-crystalline mixture M31 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and 1000 ppm of the compound of the formula ST-2
400 ppm of
and
1000 ppm of
Liquid-crystalline mixture M40 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and various concentrations of the compound of the formula ST-2 or ST-3:
Liquid-crystalline mixture M50 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and various concentrations of the compounds of the formula ST-2 or ST-3:
Liquid-crystalline mixture M51 is additionally stabilized with 400 ppm of the compound of the formula ST-1 and various concentrations of the compounds of the formula ST-2 or ST-3:
Liquid-crystalline mixture M55 is additionally stabilized with 0.05% of the compound of the formula ST-1
Liquid-crystalline mixture M56 is additionally stabilized with 0.05% of the compound of the formula ST-1
Liquid-crystalline mixture M59 is additionally stabilized with 0.04% of the compound of the formula ST-1
Liquid-crystalline mixture M60 is additionally stabilized with 0.04% of the compound of the formula ST-1
Liquid-crystalline mixture M61 is additionally stabilized with 0.04% of the compound of the formula ST-1
Liquid-crystalline mixture M62 is additionally stabilized with 0.04% of the compound of the formula ST-1
Liquid-crystalline mixture M63 is additionally stabilized with 0.04% of the compound of the formula ST-1
Liquid-crystalline mixture M117 is additionally stabilized with 0.05% of the compound of the formula ST-1
Liquid-crystalline mixture M118 is additionally stabilized with 0.05% of the compound of the formula ST-1
Liquid-crystalline mixture M119 is additionally stabilized with 0.04% of the compound of the formula ST-1 and with 0.02% of the compound of the formula ST-3
The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 009 955.8 | Aug 2015 | DE | national |
