EP0364534A1 - Melanges de cristaux liquides a faible indice de refraction - Google Patents

Melanges de cristaux liquides a faible indice de refraction

Info

Publication number
EP0364534A1
EP0364534A1 EP19890903481 EP89903481A EP0364534A1 EP 0364534 A1 EP0364534 A1 EP 0364534A1 EP 19890903481 EP19890903481 EP 19890903481 EP 89903481 A EP89903481 A EP 89903481A EP 0364534 A1 EP0364534 A1 EP 0364534A1
Authority
EP
European Patent Office
Prior art keywords
mixture
formulas
compounds
refractive index
liquid crystal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19890903481
Other languages
German (de)
English (en)
Inventor
Bernhard Rieger
Georg Weber
Volker Reiffenrath
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Merck Patent GmbH
Original Assignee
Merck Patent GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Merck Patent GmbH filed Critical Merck Patent GmbH
Publication of EP0364534A1 publication Critical patent/EP0364534A1/fr
Withdrawn legal-status Critical Current

Links

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
    • C09K19/02—Liquid crystal materials characterised by optical, electrical or physical properties of the components, in general
    • 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)

Definitions

  • the invention relates to liquid crystal mixtures with a low refractive index and their use as overlay materials in integrated optics.
  • liquid crystal mixtures Due to their diverse physical and chemical properties, liquid crystal mixtures have found ever increasing technical application.
  • the optical properties such as light absorption, light scattering, birefringence, reflectivity or color can be changed.
  • the targeted selection of the mixture components allows the setting of parameters suitable for a specific technical application.
  • liquid crystal phases are required for the technical application of these effects in electronic and optical components, which must meet a variety of requirements.
  • the chemical resistance to moisture, air and physical influences such as heat, radiation in the infrared, visible and ultraviolet range and electrical DC and AC fields are particularly important here.
  • the rapid growth of integrated optics makes it necessary to develop new optical components such as switches, couplers, modulators and polarizers. Such components are used in optical data transmission and optical sensor technology.
  • electro-optical switching elements are usually based on electro-optical switching elements. While it is often very difficult to design the waveguide itself to be electro-optically active, the use of evanescent fields in electro-optically active overlay materials enables the desired influencing of the light propagation behavior in a simpler manner.
  • liquid crystals in connection with glass waveguides e.g. required that one of the
  • fluorinated molecules have smaller refractive indices than the corresponding hydrogenated compounds.
  • Mixtures containing such fluorine th components are described in GB 87 02 126.
  • the corresponding compounds are fluorinated to a high degree [(CF 2 -CF 2 ) n units with n ⁇ 3].
  • adding fluorinated liquid crystal components to liquid crystal mixtures can lead to destabilization of the liquid crystalline phases.
  • these materials are sometimes sparingly soluble to insoluble in conventional LC mixtures containing essentially non-fluorinated liquid crystal compounds. The higher the degree of fluorination of such a mixture component, the greater the disadvantages mentioned.
  • the invention was therefore based on the object of providing new FIÜSsig crystal materials which, in particular, have favorable n o and n e values for use as electro-optically active materials in conjunction with optical glass or polymer waveguides and which do not or only to a lesser extent have the disadvantages described exhibit.
  • liquid crystal mixtures the components of which contain no (CF 2 -CF 2 ) n units, are also outstandingly suitable as overlay materials in integrated optics.
  • the invention therefore relates to a liquid-crystal mixture free of liquid-crystalline components having (CF 2 -CF 2 ) n units, where n is a natural number, characterized in that the value of the refractive index n of the mixture is smaller and the value of the refractive index n of the mixture is at least as large as a value selected from the interval 1.46-1.52.
  • a preferred object of the invention is a mixture of this type, comprising a dielectrically positive component, selected from the group of the compounds of the formulas I and II,
  • R 1 , R 2 , R 3 non-polar wing groups
  • the invention further relates to the use of such mixtures as overlay materials in the integrated optics.
  • the invention relates to an electro-optical switching element, which essentially consists of a waveguide and an optical switching element, the overlay material consisting of at least one such mixture.
  • Dielectric neutral components here mean compounds whose value for the dielectric anisotropy is -2 ⁇ ⁇ ⁇ +2, with dielectrically positive components with a value significantly higher ( ⁇ ⁇ +5), preferably ⁇ +7.
  • R 1 , R 2 , R 3 , X and Z have the meanings customary in LC chemistry.
  • R 1 , R 2 and R 3 denote non-polar wing groups, in each case independently of one another preferably an alkyl, alkenyl, alkoxy or one
  • R 1 , R 2 and / or R 3 are alkyl radicals and / or alkoxy radicals, these can be straight-chain or branched. They are preferably straight-chain and accordingly are preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore octyl, nonyl, decyl, undecyl, dodecyl, octoxy, nonoxy , Decoxy, undecoxy.
  • Branched groups of this type usually contain no more than one chain branch.
  • R 1 , R 2 and / or R 3 are alkenyl radicals, these can be straight-chain or branched. They are preferably straight-chain and have 2 to 10 carbon atoms. Accordingly, they mean in particular vinyl, prop-1- or prop2-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.
  • Q 1 represents 1,4-cyclohexylene or 1,4-phenylene
  • Q 2 and Q 3 1,4-cyclohexylene and 1,4-cyclohexenylene, but only one of these two in a compound containing Q 2 and Q 3 Rings can be 1,4-cyclohexenylene.
  • Double bond isomers of 1,4-cyclohexenylene are very particularly preferred those in which one of the atoms C 1 or C 4 is part of the double bond.
  • X denotes a polar wing group, preferably -CF 3 , -NO 2 , -CN and F. -CF 3 , -CN and F are particularly preferred.
  • the bridge member Z preferably denotes -CO-O-, -O-CO -, -CH 2 O-, -OCH 2 - or -CH 2 CH 2 -. Z also means a single bond. -CO-O-, -O-CO-, -CH 2 CH 2 - and single bond are particularly preferred.
  • the dielectric positive compounds of formula I thus correspond to those of sub-formulas Ia and Ib.
  • the dielectric positive compounds of formula II thus correspond to those of sub-formulas IIa and IIb.
  • the preferred dielectric neutral compounds of formula III correspond to those of subforms IIIa to IIIc
  • the preferred dielectrically neutral compounds of the formula IV correspond to those of the sub-formulas IVa to IVj. _ *
  • Sub-formulas IVaa to IVac are particularly preferred.
  • liquid crystal mixtures preference is given in particular to those which contain at least one dielectrically positive component I or II and at least one dielectrically neutral component III or IV, or those which contain at least two dielectrically positive components, at least one of components I or II not having 1, Contains 4-phenyl radical.
  • the mixture preferably contains 2 to 60, in particular 5 to 40% of a dielectrically positive component and 40 to 98, in particular 60 to 95% of one or more dielectrically neutral components.
  • At least one of components I or II having no 1,4-phenylene radical contains, so preferably 50 to 95%, in particular 70 to 90% of the 1,4-phenylene-free compound in the mixture.
  • liquid crystal mixtures according to the invention are preferably 50 to 100%, in particular 80 to 95%. Contain individual compounds selected from the group of formulas I to IV.
  • the mixture contains only fluorine-free components.
  • the mixtures according to the invention are prepared in a conventional manner.
  • the desired amount of the components used in smaller amounts is dissolved in the components which make up the main constituent, advantageously at elevated temperature.
  • 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.
  • the mixtures according to the invention are suitable as overlay materials for polymeric or glass waveguides and are notable for their low viscosity and a wide mesophase range.
  • the usual poly (meth) acrylates, polysiloxanes, polyimides or other materials known to the person skilled in the art can be used as polymers.
  • FIG. 1 shows an example of the structure of an electro-optical switching element. For the sake of clarity, components 1 to 6 are not reproduced to one another to scale.
  • the element consists of a substrate (1) with an inscribed waveguide (2).
  • An electrode (3) which is applied to the substrate surface and is connected to a voltage source (not shown), is arranged on both sides of the waveguide.
  • the space above the waveguide and part of the electrodes is filled by the overlay material, the liquid crystal mixture (4). This space is delimited on the side by spacers (5) and on the top by a glass plate (6).
  • the value of the refractive index of the waveguide material is larger than that of the substrate and lies between the values for no and ne
  • Liquid crystal mixture but is at most as large as that for n e .
  • the longitudinal axes of the liquid crystal molecules are so pre-oriented in the field-free state that the preferred direction between the electrodes is perpendicular to the substrate surface (homeotropic).
  • the application of an electric field causes the molecules to flip in the direction of the field and thus to change the waveguide properties. For example, once the field has been created, a T E wave arriving in the waveguide is no longer continued.
  • This component can thus serve, for example, as a polarizer for unpolarized light or as an ON / OFF switch for linearly polarized light. If the control is varied, it can also be used as a modulator.
  • the electrodes can also be attached above and below the waveguide and the liquid crystal molecules can also be pre-oriented parallel to the substrate surface. The switching principle remains unchanged.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Liquid Crystal Substances (AREA)

Abstract

Des mélanges de cristaux liquides comprennent au moins deux composants, l'indice de réfraction du mélange no étant inférieur à une valeur sélectionnée dans la plage comprise entre 1,46 et 1,52 et l'indice de réfraction du mélange ne étant au moins égal à ladite valeur. Les composants du mélange ne contiennent aucune unité de (CF2-CF2)n. Ces mélanges sont utiles comme matériaux de recouvrement en optique intégrée.
EP19890903481 1988-04-02 1989-03-22 Melanges de cristaux liquides a faible indice de refraction Withdrawn EP0364534A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3811333 1988-04-02
DE19883811333 DE3811333A1 (de) 1988-04-02 1988-04-02 Fk-mischungen mit niedrigem brechungsindex

Publications (1)

Publication Number Publication Date
EP0364534A1 true EP0364534A1 (fr) 1990-04-25

Family

ID=6351368

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890903481 Withdrawn EP0364534A1 (fr) 1988-04-02 1989-03-22 Melanges de cristaux liquides a faible indice de refraction

Country Status (4)

Country Link
EP (1) EP0364534A1 (fr)
JP (1) JPH03500058A (fr)
DE (1) DE3811333A1 (fr)
WO (1) WO1989009252A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5456860A (en) * 1990-03-31 1995-10-10 Merck Patent Gesellschaft Mit Beschrankter Haftung Matrix liquid-crystal display

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5734176A (en) * 1980-08-08 1982-02-24 Hitachi Ltd Liquid crystal composition
JPS57118526A (en) * 1981-01-14 1982-07-23 Dainippon Ink & Chem Inc Dicyclohexylethane derivative
DE3566901D1 (en) * 1984-04-07 1989-01-26 Merck Patent Gmbh Liquid crystal phase

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8909252A1 *

Also Published As

Publication number Publication date
DE3811333A1 (de) 1989-10-19
WO1989009252A1 (fr) 1989-10-05
JPH03500058A (ja) 1991-01-10

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