Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings
  • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/42—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
  • C09K19/44—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40 containing compounds with benzene rings directly linked
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings
  • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
  • C09K2019/3021—Cy-Ph-Ph-Cy

Definitions

• the present invention relates to a liquid-crystalline medium, its use for electro-optical purposes and displays containing this medium.
• Liquid crystals are mainly used as dielectrics in display devices, since the optical properties of such substances can be influenced by an applied voltage.
• Electro-optical devices based on liquid crystals are well known to the person skilled in the art and can be based on various effects. Such devices are, for example, cells with dynamic scattering, DAP cells (deformation of aligned phases), guest / host cells, TN cells with a twisted nematic ("twisted nematic”) structure, STN cells ("super-twisted”)
• the liquid crystal materials must have good chemical and thermal stability and good stability against electric fields and electromagnetic radiation. Furthermore, the liquid crystal materials should have a low viscosity and result in short response times, low threshold voltages and a high contrast in the cells. Furthermore, they should have a suitable mesophase at the usual operating temperatures, ie in the widest possible range below and above room temperature, for example a nematic or cholesteric mesophase for the above-mentioned cells. Since liquid crystals are generally used as mixtures of several components, it is important that the components are readily miscible with one another. Other properties, such as electrical conductivity, dielectric anisotropy and optical anisotropy, must meet different requirements depending on the cell type and area of application. For example, materials for cells with a twisted nematic structure should have positive dielectric anisotropy and low electrical conductivity.
• MLC displays matrix liquid crystal displays with integrated non-linear elements for switching individual pixels
• MLC displays are media with large positive dielectric anisotropy, wide nematic phases, relatively low birefringence, very high specific resistance, good UV and temperature stability of the resistance and low Vapor pressure desired.
• Such matrix liquid crystal displays are known.
• active elements i.e. transistors
• non-linear elements for the individual switching of the individual pixels.
• active matrix whereby one can distinguish two types:
• MOS Metal Oxide Semiconductor
• TFT Thin film transistors
• the TN effect is usually used as the electro-optical effect.
• TFTs made of compound semiconductors such as CdSe or TFT's based on polycrystalline or amorphous silicon The latter technology is being worked on with great intensity worldwide.
• the TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries the transparent counter electrode on the inside. Compared to the size of the pixel electrode, the TFT is very small and practically does not disturb the image.
• This technology can also be expanded for fully color-compatible image representations, a mosaic of red, green and blue filters being arranged in such a way that a filter element is located opposite a switchable image element.
• the TFT displays usually work as TN cells with crossed polarizers in transmission and are illuminated from behind.
• the invention has for its object media in particular for such MFK, TN or STN displays
• the invention thus relates to a liquid-crystalline medium based on a mixture of polar compounds with positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I.
• R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 7 carbon atoms and LH or F.
• the invention also relates to electro-optical displays (in particular STN or MFK displays with two plane-parallel carrier plates which form a cell with a border, integrated non-linear elements for switching individual pixels on the carrier plates and a nematic liquid crystal mixture in the cell with a positive one dielectric
• electro-optical displays in particular STN or MFK displays with two plane-parallel carrier plates which form a cell with a border, integrated non-linear elements for switching individual pixels on the carrier plates and a nematic liquid crystal mixture in the cell with a positive one dielectric
• liquid crystal mixtures according to the invention allow a significant expansion of the available parameter space.
• liquid crystal mixtures according to the invention enable dielectric anisotropy values ⁇ ⁇ 5.0 at the same time at low viscosities at low temperatures (at -30 ° C. 600 600, preferably 550 550 mPa.s; at -40 ° C 1800 1800, preferably 17 1700 mPa.s) , preferably ⁇ 6.0, clearing points above 75 °, preferably above
• the MFK displays according to the invention preferably work in the first
• the person skilled in the art can set the birefringence required for a given layer thickness of the MLC display by means of suitable routine selection of the individual components and their proportions by weight.
• the media according to the invention also enable short switching times due to high absolute values of the elastic variables.
• the viscosity at 20 ° C is preferably ⁇ 25 mPa.s.
• the nematic phase range is preferably at least 70 °, in particular at least 80 °. This range preferably extends at least from -30 ° to + 70 °.
• the UV stability of the mixtures according to the invention is also considerably better, ie they show a significantly smaller decrease in HR under UV exposure.
• the media according to the invention are also distinguished by extraordinarily high elastic constants at very
• the media according to the invention are preferably based on several (preferably three or more) compounds
• Clarification point 135 °
• Clarification point 129 ° C
• Medium additionally contains one or more compounds selected from the group consisting of the general formulas II, m and IV:
• R alkyl, oxaalkyl, fluoroalkyl or alkenyl
• - Medium additionally contains one or more compounds selected from the group consisting of the general formulas V to VIII:
• R, X and Y each independently have one of the meanings given in claim 1.
• - Medium additionally contains one or more compounds selected from the group consisting of the general forms IX to XII:
• the medium contains compounds of the formulas II and III or IV - R is straight-chain alkyl or alkenyl with 2 to 7 carbon atoms -
• the medium consists essentially of compounds of the formulas I to IV -
• the medium contains further compounds, preferably selected from the following group:
• the weight ratio I: (II + III + IV) is preferably 1: 4 to 1: 1.
• the medium essentially consists of compounds selected from the group consisting of the general formulas I to XII.
• alkyl 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 of 2-5 carbon atoms are generally preferred.
• alkenyl encompasses straight-chain and branched alkenyl groups having 2-7 carbon atoms, in particular the straight-chain groups.
• Alkenyl groups in particular are C 2 -C 7 -1E alkenyl, C 4 -C 7 -3E alkenyl,
• preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl,
• fluoroalkyl preferably encompasses straight chain groups with terminal fluorine, i.e. Fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorhexyl and 7-fluoroheptyl. However, other positions of the fluorine are not excluded.
• oxaalkyl preferably includes straight chain
• Residues of the formula C n H 2n + 1 -O- (CH 2 ) m in which n and m each independently represent 1 to 6.
• the response times, the threshold voltage, the steepness of the transmission characteristics, etc. can be modified in a desired manner by a suitable choice of the meanings of R, X and Y.
• 1E-alkenyl residues, 3E-alkenyl residues, 2E-alkenyloxy residues and the like generally lead to shorter response times, improved nematic tendencies and a higher ratio of the elastic constants k 33 (bend) and k 11 (splay) in comparison to alkyl or Alkoxy residues.
• 4-alkenyl residues, 3-alkenyl residues and the like generally give lower threshold voltages and smaller values of k 33 / k 11 compared to alkyl and alkoxy residues.
• a group -CH 2 CH 2 - in Z 1 or Z 2 generally leads to higher values of k 33 / k 11 compared to a simple covalent bond.
• Higher values of k 33 / k 11 enable, for example, flatter transmission characteristics in TN cells with 90 ° twist (to achieve gray tones) and steeper transmission characteristics in STN, SBE and OMI cells (higher multiplexability) and vice versa.
• Formulas I and II + III + IV largely depend on the desired properties, on the choice of the components of the formulas I, II, III and / or IV and on the choice of further components which may be present.
• the total amount of compounds of the formulas I to XII in the mixtures according to the invention is not critical.
• the mixtures can therefore contain one or more further components in order to optimize various properties.
• the observed effect on the response times and the threshold voltage is generally greater the higher the total concentration of compounds of the formulas I to XII.
• the media according to the invention contain compounds of the formula II, III, V and / or VII (preferably II and / or III), in which X is preferably OCHF 2 .
• X is preferably OCHF 2 .
• the media preferably contain compounds selected from the group consisting of the formulas V to VIII, where X is preferably OCHF 2 .
• the media according to the invention can also contain a component A consisting of one or more compounds having a dielectric anisotropy of -1.5 to +1.5 of the general formula I ' V
• R 1 and R 2 each independently of one another n-alkyl, n-alkoxy, ⁇ -fluoroalkyl or n-alkenyl having up to 9 carbon atoms, the rings A 1 , A 2 and A 3
• Cyclohexylene or 1,4-cyclohexenylene, Z 1 and Z 2 each independently of one another -CH 2 CH 2 -, -C ⁇ C-,
• n 0, 1 or 2.
• Component A preferably contains one or more
• Component A preferably additionally contains one or more compounds selected from the group consisting of 118 to 1120:
• R 1 and R 2 have the meaning given for formula I 'and the 1,4-phenylene groups in 118 to 1117 can each be substituted independently or independently by fluorine.
• Component A also preferably additionally contains one or more compounds selected from the group consisting of 1121 to 1125:
• R 1 and R 2 have the meaning given for formula I 'and the 1,4-phenylene groups in 1121 to 1125 can each be substituted, independently of one another, by fluorine one or more times.
• mixtures of this type are preferred, whose component A contains one or more compounds selected from the group consisting of 1126 and 1127: 0 f ⁇ wherein C r H 2r + 1 is a straight-chain alkyl group with up to 7 C atoms.
• Z 0 is a single bond, -CH 2 CH 2 -, or
• liquid crystal mixtures which select one or more compounds from the
• R 1 and R 2 have the meaning given for formula I '.
• the type and amount of polar compounds with positive dielectric anisotropy is not critical in six. The person skilled in the art can select suitable materials in simple routine tests from a wide range of known and in many cases also commercially available components and base mixtures.
• the media according to the invention preferably contain one or more compounds of the formula I "
• Z 1 , Z 2 and m have the meaning given for formula I ', Q 1 and Q 2 each independently
• R 0 n-alkyl, n-alkenyl, n-alkoxy or n-oxaalkyl, each with up to 9 C atoms, YH or F and X 'CN,
• the media according to the invention for STN or TN applications are based on compounds of the formula I "in which X 'CN. It is understood that smaller or larger proportions of other compounds of the formula I"(X' ⁇ CN) come into question.
• the structure of the STN or MFK according to the invention -Display made of polarizers, electrode base plates and electrodes with surface treatment corresponds to the design customary for such displays, whereby the term conventional design is broad here and also includes all modifications and modifications of the MLC display, in particular also matrix display elements based on poly-Si TFT or MIM.
• liquid crystal mixtures which can be used according to the invention are prepared in a manner which is conventional per se. As a rule, the desired amount is less
• the amount of components used is dissolved in the components which make up the main constituent, expediently at elevated temperature. It is also possible to use solutions of the components in an organic solvent, e.g. in acetone, chloroform or methanol, and to remove the solvent after mixing, for example by distillation.
• an organic solvent e.g. in acetone, chloroform or methanol
• the dielectrics can also contain further additives known to the person skilled in the art and described in the literature.
• C means a crystalline
• S a smectic S B a smectic B
• N a nematic
• I the isotropic phase.
• V 10 denotes the voltage for 10% transmission
• t on denotes the switch-on time and t off the switch-off time at an operating voltage corresponding to 2.5 times the value of V 10 .
• ⁇ n denotes the optical anisotropy and n the refractive index.
• the electro-optical data were recorded in a TN cell in the 1st
• EPCH-50CF2 7.0 viscosity at -30 ° C 540 mPa.s

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• 1991
  • 1991-03-21 JP JP3506789A patent/JPH04506376A/ja active Pending
  • 1991-03-21 EP EP91906706A patent/EP0474823A1/de not_active Withdrawn
  • 1991-03-21 KR KR1019910701745A patent/KR920701386A/ko not_active Application Discontinuation
  • 1991-03-21 WO PCT/EP1991/000553 patent/WO1991015556A1/de not_active Application Discontinuation

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