This application filed under 35 U.S.C. § 111(a) claims priority benefit under 35 U.S.C. § 119(a) of and to EP Patent Application No. 23218161.0, filed Dec. 19, 2023, the entire contents of which are incorporated herein by reference in their entirety and for all purposes.
The present invention relates to liquid-crystalline (LC) media and to energy saving liquid-crystal displays (LCDs) containing these media, especially to high contrast, fast switching gaming displays and AR/VR headsets having reduced short term image sticking and reduced long term image sticking especially after light load and/or temperature load. In particular, it relates to LC displays of the TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilised SA-HB-FFS, polymer stabilised SA-XB-FFS, positive VA or positive PS-VA type. In a preferred embodiment, the LC media have positive dielectric anisotropy.
LCDs are used in many areas for the display of information. LCDs are used both for direct-view displays and for projection-type displays. The electro-optical modes used are, for example, the twisted nematic (TN), super twisted nematic (STN), optically compensated bend (OCB) and electrically gontrolled birefringence (ECB) modes together with their various modifications, as well as others. All these modes utilise an electric field which generated substantially perpendicular to the substrates and the LC layer.
Besides these modes, there are also electro-optical modes that utilise an electric field which is substantially parallel to the substrates or the LC layer. For example, WO 91/10936 discloses a LC display in which the electric signals are generated in such a way that the electric fields have a significant component parallel to the LC layer, and which has since then become known as “in-plane switching” (IPS) display. The principles of operating such a display are described, for example, by R. A. Soref in Journal of Applied Physics, Vol. 45, No. 12, pp. 5466-5468 (1974).
IPS displays contain an LC layer between two substrates with planar orientation, where the two electrodes are arranged on only one of the two substrates and preferably have interdigitated, comb-shaped structures. On application of a voltage to the electrodes an electric field with a significant component parallel to the LC layer is generated between them. This causes realignment of the LC molecules in the layer plane.
EP 0 588 568, for example, discloses various possibilities for the design of the electrodes and for addressing an IPS display. DE 198 24 137 likewise describes various embodiments of such IPS displays.
LC materials for IPS displays of this type are described, for example, in DE 195 28 104.
Furthermore, so-called “fringe-field switching” (FFS) displays have been reported (see, inter alia S. H. Jung et al., Jpn. J. Appl. Phys., Volume 43, No. 3, 2004, 1028), which contain two electrodes on the same substrate, one of which is structured in a comb-shaped manner and the other is unstructured. A strong, so-called “fringe field” is thereby generated, i.e. a strong electric field close to the edge of the electrodes, and, throughout the cell, an electric field which has both a strong vertical component and also a strong horizontal component. FFS displays have a low viewing-angle dependence of the contrast. FFS displays usually contain an LC medium with positive dielectric anisotropy, and an alignment layer, usually of polyimide, which provides planar alignment to the molecules of the LC medium.
LCDs of the IPS and FFS electro-optical mode are, in particular, suitable for use in modern desktop monitors, TV sets and multimedia applications. The LC media according to the present invention are preferably used in displays of this type. In general, dielectrically positive LC media having rather lower values of the dielectric anisotropy are used in FFS displays, but in some cases LC media having a dielectric anisotropy of only about 3 or even less are also used in IPS displays.
A further improvement has been achieved by the HB-FFS mode. One of the unique features of the HB-FFS mode in contrast to the traditional FFS technology is that it enables higher transmittance which allows operation of the panel with less energy consumption.
Another recently developed mode is the XB-FFS mode, wherein the LC medium additionally contains a polar liquid crystal compound with low dielectric anisotropy.
FFS and IPS displays can be operated as active-matrix displays (AMD) or passive-matrix displays (PMD). In the case of active-matrix displays individual pixels are usually addressed by integrated, non-linear active elements such as, for example, thin-film transistors (TFTs), while in the case of passive-matrix displays individual pixels are usually addressed by the multiplex method as known from the prior art.
The displays according to the present invention are preferably addressed by an active matrix, preferably by a matrix of TFT. However, the LC media according to the invention can also advantageously be used in displays having other known addressing means.
Typical applications of IPS and FFS technologies are monitors, notebooks, televisions, mobile telephones, tablet PCs, etc. Both the IPS and the FFS technology have certain advantages over other LCD technologies, such as, for example, the vertical alignment (VA) technology, e.g. a broad viewing angle dependency of the contrast.
Provision of LC media and the use thereof in a display having a particularly low short-term image sticking and low long-term image-sticking in combination with short response times is a central challenge for modern FFS and IPS applications.
In addition, modern applications also require good low-temperature stability and stability against UV radiation and increased temperatures.
The present invention has the object of providing LC media, in particular for FFS and IPS displays, but also for TN, positive VA or STN displays, and in particular for active-matrix displays like those addressed by TFTs, which have low short-term image sticking and low long-term image-sticking as well as short response times.
This object was achieved by providing LC media as described and claimed hereinafter.
The LC media according to the present invention are especially suitable for use in LC displays of the FFS, HB-FFS, XB-FFS and IPS mode based on dielectrically positive liquid crystals, and polymer stabilised variants thereof.
Surprisingly, the above technical problem is solved by providing LC media as described and claimed hereinafter.
It has now been surprisingly found that LC media according to the present invention which contain one or more compounds of the Formula I
Additionally, the LC media according to the present invention have high clearing points, an excellent low temperature stability (LTS) and provide a best motion picture quality and an improved overall image quality, in particular a high contrast.
The present invention relates to a LC medium, characterised in that it comprises one or more compounds of the Formula I
The antioxidants for use in the present invention are per se known in the prior art and are not particularly limited. The inventors found that an antioxidant described by the formula ST shown below in combination with the compound of Formula I allows achieving a particularly low rotational viscosity γ1 and low short-term image sticking and low long-term image sticking, especially after a high radiation exposure or thermal stress:
In addition to the compound of Formula I and an antioxidant, the LC medium of the present invention may comprise a light stabilizer. The presence of a light stabilizer synergistically increases the stabilizing effect of the antioxidant in terms of reduced short-term image sticking and reduced long-term image sticking resulting in significant reduction of mura defects such as star mura or edge mura. Use of one or more light stabilizer of the following Formula H showed to be particularly advantageous:
The LC media according to the present invention are especially suitable for use in energy saving LC displays of the FFS, HB-FFS, XB-FFS and IPS mode for gaming based on dielectrically positive liquid crystals, and polymer stabilised variants thereof.
The invention further relates to the use of a LC medium as described above and below for electro-optical purposes, in particular for the use in LC displays, shutter glasses, LC windows, 3D applications, preferably in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilised SA-HB-FFS, polymer stabilised SA-XB-FFS, positive VA and positive PS-VA displays, very preferably in FFS, HB-FFS, IPS, PS-HB-FFS and PS-IPS displays.
The invention further relates to an electro-optical LC display containing a LC medium as described above and below, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilised SA-HB-FFS, polymer stabilised SA-XB-FFS, positive VA or positive PS-VA display, preferably a FFS, HB-FFS, IPS, PS—HB—FFS or PS-IPS display.
In the present application, all atoms may optionally include their isotopes. In some embodiments, one or more hydrogen atoms (H) may be optionally replaced by deuterium (D); a high degree of deuteration enables or simplifies analytical determination of compounds, in particular in the case of low concentrations.
In the Formula I, ST and H, if R0, R21, R22, R11, R12 or R13 to R17 denote an alkyl group and/or an alkoxy group, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, or 6 C atoms and preferably denotes ethyl, propyl, butyl, pentyl, hexyl, ethoxy, propoxy, butoxy, pentoxy, or hexyloxy, furthermore methyl, methoxy. R0 preferably denotes straight-chain alkyl having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms.
Oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl.
If R0, R21, R22, R11, R12 or R13 to R17 denotes an alkoxy or oxaalkyl group it may also contain one or more additional oxygen atoms, provided that oxygen atoms are not linked directly to one another.
In another preferred embodiment, one or more of R0, R21, R22, R11, R12 or R13 to R17 are selected from the group consisting of
—S1—F, —O—S1—F, —O—S1—O—S2, wherein S1 is C1-12-alkylene or C2-12-alkenylene and S2 is H, C1-12-alkyl or C2-12-alkenyl, and very preferably one or more of R0, R21, R22, R11, R12 or R13 to R17 are selected from the group consisting of
—OCH2—OCH3, —O(CH2)2OCH3, —O(CH2)3OCH3, —O(CH2)4OCH3, —O(CH2)2F, —O(CH2)3F, —O(CH2)4F.
If R0, R21, R22, R11, R12 or R13 to R17 denotes an alkenyl group, 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 -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.
If R0, R21, R22, R11, R12 or R13 to R17 denotes an alkyl or alkenyl group which is at least monosubstituted by halogen, this group is preferably straight-chain, and halogen is preferably F or Cl. In the case of polysubstitution, halogen is preferably F. The resultant groups also include perfluorinated groups. In the case of mono-substitution, the fluorine or chlorine substituent may be in any desired position, but is preferably in the w-position.
Particularly preferred group R0 in the Formula I denotes alkyl, alkenyl, alkynyl or alkoxy having up to 12, preferably up to 8 C atoms, each of which is optionally substituted by halogen, in particular by F, particularly preferred are H, F, alkyl, alkenyl or alkynyl having up to 8 C atoms.
Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl. Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl and pentenyl. Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl and octynyl. Preferred alkoxy groups are, for example, methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy. Halogen preferably denotes F or Cl, F being mostly preferred.
The one or more compounds of the Formula I is preferably selected from one of the following structures:
In a more preferred embodiment, R0, X0 and Y0 are as follows:
Particularly preferred compounds of Formula I-1 are those selected from the group consisting of the following subformulae
Very preferred are the compounds of formulae 1-1-1, 1-1-2, 1-1-3 and 1-1-4, most preferred is the compound formula 1-1-2.
Preferred compounds of Formulae 1-2 and 1-3 are as follows:
The proportion of the compounds of Formula I or its subformulae in the LC medium is preferably from 2 to 35%, very preferably from 3 to 30%, most preferably from 4 to 20% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of Formula I or its subformulae.
The term “antioxidant” as used in the present application is well known to a skilled person and refers to a compound added to a LC medium which is capable of retarding autooxidation. The antioxidants for use in the present invention are not particularly limited as long as they do not substantially deteriorate physical properties of the LC medium, in particular, in terms of their voltage holding ratio and mesogenic behaviour.
In one preferred embodiment, the antioxidant in the LC medium of the present invention is described by the general Formula ST as specified above. LC media comprising compounds of the following sub-formulae ST-1, ST-2 and ST-3 showed a particularly high long-term thermal and UV stability:
in which
In particularly preferred embodiments, the compounds of the general Formula ST can be selected from the following specific structures:
In a further preferred embodiment, the LC medium according to the present invention may comprise at least one further sterically hindered phenol as an additional antioxidant, which is mentioned in Table B below.
The preferred content of the one or more compounds of Formula ST in the LC medium depends inter alia on the inherent chemical stability of the LC medium as well as on the nature of the compound of Formula ST. They are preferably used in proportion ranging from 10 ppm to 10000 ppm, more preferably from 20 ppm to 2000 ppm, based on the weight of the LC medium.
The term “light stabilizer” as used in the present application is well known to a skilled person and refers to a compound added to a LC medium which is capable of protecting it against degradation resulting from a long term exposure to UV radiation. Suitable light stabilizers include, inter alia, hindered amine light stabilizers (HALS) and ultraviolet (UV) absorbers as well as a combination thereof. The light stabilizers for use in the present invention are not particularly limited as long as they do not substantially deteriorate physical properties of the LC medium, in particular, in terms of voltage holding ratio and mesogenic behaviour.
In one preferred embodiment, the light stabilizer in the LC medium of the present invention is described by the general Formula H as described above. In some preferred embodiments of the present invention, in the compounds of the Formula H,
In a preferred embodiment of the present application, in the compounds of the Formula H,
In a further preferred embodiment of the present application, in the compounds of the Formula H,
In yet a further preferred embodiment of the present invention, in the compounds of the Formula H in which p preferably denotes 1,
In a further preferred embodiment of the present invention, in the compounds of the Formula H, the group
In a further preferred embodiment of the present invention, in which p is 2, which may be identical to or different from those described above, in the compounds of the Formula H,
In yet a further preferred embodiment of the present invention, which may be identical to or different from those described above, in the compounds of the Formula H, the group
Compounds of the following general Formulae H-1-1, H-1-2 and H-1-3, showed to be particularly efficient UV stabilisers in LC mixtures, in particular, in terms of VHR stability:
In a particularly preferred embodiment, the one or more compounds of the Formula H may be selected from the group consisting of the compounds the following Formulae H-2-1 to H-2-6:
In a preferred embodiment of the present invention, the LC media according to the invention comprise in each case one or more compounds of the Formula H selected from the following group of the compounds of the formulae:
The preferred content of the one or more compounds of Formula H in the LC medium depends inter alia on the inherent chemical stability of the LC medium as well as on the nature of the compound of Formula H. Compounds of Formula H in which R16 denotes O•, which are known as NO radical type HALS are preferably used in proportion ranging from 50 ppm to 1000 ppm, based on the weight of the LC medium. Compounds of Formula H in which R16 denotes an H atom, which are known as NH radical type HALS are advantageously used in proportion ranging from 50 ppm to 2000 ppm, based on the weight of the LC medium.
In one preferred embodiment, the LC medium may additionally comprise one or more compounds selected from the following Formulae II and Ill:
Preferred compounds of the Formula II and Ill are those wherein Y0 is H.
Further preferred compounds of the Formula II and Ill are those wherein R0 denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl and X0 denotes F, CF3 or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl, very preferably F.
In a preferred embodiment, the LC medium comprises one or more compounds of the Formula II selected from the following subformulae:
Preferred compounds are those of the Formula II-1, ∥-2 and 11-3, very preferred those of the Formula II-1 and 11-2.
In the compounds of the Formulae II-1 to 11-7 R0 preferably denotes R0 denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl and X0 denotes F, CF3 or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl, very preferably F.
In one embodiment, the LC medium contains one or more compounds of the Formula II or their subformulae as described above and below, wherein Y0 is CH3. Very preferably, the LC medium according to this preferred embodiment comprises one or more compounds of the Formula II selected from the following subformulae:
Preferred compounds are those of the Formula IIA-1, IIA-2 and IIA-3, very preferred are those of Formula IIA-1 and IIA-2.
In the compounds of the Formulae IIA-1 to IIA-7 R0 preferably denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl and X0 denotes F, CF3 or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl, very preferably F.
The proportion of the compounds of the Formula II in the LC medium is typically from 0 to 20%, very preferably from 1 to 15%, most preferably from 2 to 10% by weight.
In a further preferred embodiment, the LC medium comprises one or more compounds of the Formula III selected from the following subformulae:
Particularly preferred compounds are those of the Formulae Ill-1, Ill-4, Ill-6, Ill-16, Ill-19 and Ill-20.
In the compounds of the Formulae Ill-1 to Ill-22 R0 denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl and X0 denotes F, CF3 or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl, very preferably F, and Y0 preferably denotes H.
The LC medium may contain one or more compounds of the Formula III or their subformulae as described above and below wherein Y0 is CH3. Very preferably, the LC medium according to this preferred embodiment comprises one or more compounds of the Formula III selected from the following subformulae:
Preferred compounds are those of the Formula IIIA-1, IIIA-4, IIIA-6, IIIA-16, IIIA-19 and IIIA-20.
In the compounds of the Formulae IIIA-1 to IIIA-21 R0 denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl and X0 denotes F, CF3 or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl, very preferably F.
The proportion of the compounds of the Formula III in the LC medium is preferably from 5 to 60%, very preferably from 10 to 50%, most preferably from 20 to 40% by weight.
In a further preferred embodiment, the LC medium may additionally comprise one or more compounds selected from the following formulae:
The compounds of the Formula IV are preferably selected from the following formulae:
R0 preferably denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl. X0 preferably denotes F or OCF3, furthermore OCF=CF2, OCHFCF3 or Cl.
The compounds of the Formula IVa are preferably represented by the following subformulae:
The compounds of the Formula IVb are preferably represented by the following formulae:
The compounds of the Formulae IVc are preferably represented by the following subformulae:
The compound(s) of the Formula IVc, in particular of the Formula IVc-1, is (are) preferably employed in the LC media according to the invention in amounts of 1-20% by weight, particularly preferably 2-15% by weight.
The compounds of the Formula V are preferably selected from the following subformulae:
The compounds of the Formula VI are preferably selected from the following subformulae:
R0 preferably denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, n-propyl, n-butyl or n-pentyl. X0 preferably denotes F, furthermore OCF3, CF3, CF=CF2, OCHF2, OCHFCF3 and OCH═CF2;
Preferred compounds of the Formulae Via to Vie are those selected from the following subformulae:
The compounds of the Formula VII are preferably selected from the following subformulae:
R0 preferably denotes alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms, very preferably ethyl, propyl, butyl or pentyl. X0 preferably denotes F, furthermore OCF3, OCHF2, OCHFCF3 and OCH═CF2.
In some embodiments, the LC medium additionally comprises one or more compounds selected from the following formulae:
Very preferably, the LC medium according to the invention comprises one or more compounds of the Formula XXa:
The compound(s) of the Formula XX, in particular of the Formula XXa, is (are) preferably employed in the LC media according to the invention in amounts of 0-15% by weight, particularly preferably 1-10% by weight.
Very preferably, the LC medium according to the invention comprises one or more compounds of the Formula XXIa:
The compound(s) of the Formula XXI, in particular of the Formula XXIa, is (are) preferably employed in the LC media according to the invention in amounts of 1-15% by weight, particularly preferably 2-10% by weight.
Further preferably, the LC medium according to the invention comprises one or more compounds of the Formula XXIIIa:
Preferred specific compounds of Formula XXIIIa include, in particular
The compound(s) of the Formula XXIII, in particular of the Formula XXIIIa, is (are) preferably employed in the LC media according to the invention in amounts of 0.5-5% by weight, particularly preferably 0.5-2% by weight.
The LC medium may additionally comprise one or more compounds of the Formula XXIV:
In the Formula XXIV, X0 may also denote an alkyl group having 1 to 6 C atoms or an alkoxy group having 1 to 6 C atoms. The alkyl or alkoxy group is preferably straight-chain.
R0 preferably denotes alkyl having 1 to 6 C atoms. X0 preferably denotes F.
The compounds of the Formula XXIV are preferably selected from the following subformulae:
The LC medium may further comprise one or more compounds of the following formulae:
The LC medium may further optionally comprise one or more compounds of the following formulae:
The compounds of the Formula XXVIII are preferably selected from the subformulae XXVIIIa, wherein XXVIIIa-1 and XXVIIIa-2 are mostly preferred:
The compound(s) of the Formulae XXVII-XXX is (are) preferably employed in the LC media according to the invention in amounts of 1-20% by weight, particularly preferably 1-15% by weight. Particularly preferred LC media comprise at least one compound of the Formula XXIX and/or the Formula XXX.
Very preferably, the LC medium according to the invention comprises one or more compounds of the Formulae XXIXa and/or XXXa:
The compound(s) of the Formulae XXIXa and/or XXXa is/are preferably employed in the LC media according to the invention in amounts of 1-15% by weight, particularly preferably 2-10% by weight.
The LC medium may further comprise one or more compounds of the following pyrimidine or pyridine compounds of the following formulae:
Preferably, in addition to the compounds of the Formula I, an antioxidant and, optionally, a light stabilizer, the LC medium contains one or more compounds of the Formulae N1 and N2:
In some embodiments, the LC medium contains one or more compounds selected from the following formulae:
Very preferred are compounds of the Formula Z1 and Z2.
Preferred compounds of the Formulae Z1 to Z6 are those selected from the following subformulae:
In another preferred embodiment, the LC medium contains one or more compounds of the Formula Z1 or its preferred subformulae and/or one or more compounds selected from the Formulae Z2, Z3, Z4 and Z5 or their preferred subformulae.
Preferably, the total proportion of compounds of the Formula Z1, Z2, Z3, Z4, Z5 and Z6 or their subformulae, such as CC-3-V in the medium is from 10 to 65%, very preferably from 20 to 60%, most preferably from 25 to 55% by weight. In yet a more preferred embodiment, the compound of the Formula Z1-1 is used in concentrations ranging from 10 wt.-% to 60 wt.-%, more preferably 25 wt.-% to 50 wt.-%, based on the total weight of the LC medium. In a further preferred embodiment, the LC medium comprises 50 wt.-% to 70 wt.-% of compounds represented by the Formulae Z1-1 and Z4-2 in total.
Preferably, the medium contains 1, 2 or 3 compounds selected from the Formulae Z1, Z2, Z3 and Z4 or their subformulae.
The LC medium may additionally comprise one or more compounds of the following general formulae:
The compounds of the Formula XII are preferably selected from the following subformulae:
wherein “alkyl” and “alkyl*” each, independently from one another, denote methyl, ethyl, propyl, butyl, pentyl or hexyl.
Particular preference is given to the compounds of the Formulae XIIa and XIIc. In the Formula XIIb, “alkyl” preferably, independently of one another, denotes n-C3H7, n-C4H9 or n-C5H11, in particular n-C3H7. In the Formula XIIc, “alkyl” preferably denotes n-C3H7 and “alkyl” is preferably CH3 or n-C3H7.
Particularly preferred compounds of the Formula XII are described by the following structures:
The LC medium may additionally comprise one or more compounds selected from the following formulae:
in which L1 and L2 have the meanings indicated in the Formula III, and R1 and R2 each, independently of one another, denote n-alkyl, cycloalkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each, independently of one another, denote alkyl having 1 to 6 C atoms; in the compound of the Formula XIV, at least one of the substituents R1 and R2 preferably denotes alkenyl having 2 to 6 C atoms.
The LC medium may further optionally comprise one or more compounds of the Formula XIV in which at least one of the substituents R1 and R2 denotes alkenyl having 2 to 6 C atoms, preferably those selected from the following subformulae:
in which “alkyl” and “alkyl*” have the meaning indicated above, and each, independently of one another, preferably denote methyl, ethyl or propyl.
The compounds of the Formulae XIV are preferably selected from the following subformulae:
Very preferred are compounds of the Formulae XIVd-1, XIVe-1, XIVe-2 and XIVe-3.
The LC medium may further optionally comprise one or more compounds of the Formula XV in which at least one of the substituents R1 and R2 denotes alkyl or alkoxy having 2 to 6 C atoms, preferably those selected from the following subformulae:
In yet a further embodiment, the LC medium comprises one or more compounds of the Formula XVI:
in which R1 and R2 have the meanings indicated for R0 in the Formula II, and preferably each, independently of one another, denote alkyl having 1 to 6 C atoms. L denotes H or F.
Particularly preferred compounds of the Formula XVI are those of the subformulae:
Particular preference is given to the compounds of the Formulae XVIb and XVIc. Very particular preference is given to the compounds of the following subformulae:
In yet a further embodiment, the LC medium comprises one or more compounds of the Formula XIII:
in which R1 and R2 have the meanings indicated for R0 in the Formula II, and preferably each, independently of one another, denote alkyl having 1 to 6 C atoms. L denotes H, F or Cl.
Particularly preferred compounds of the Formula XIII are those of the subformulae:
Particular preference is given to the compounds of the Formulae XIIla and XIIlb. Very particular preference is given to the compounds of the following subformulae:
In yet a further embodiment, the LC medium comprises one or more compounds of the Formula XIII:
Particularly preferred compounds of the Formula XIII are those of the subformulae:
Particular preference is given to the compounds of the Formulae XIIla and XIIlb. Very particular preference is given to the compounds of the following subformulae:
The LC medium may optionally comprise one or more compounds of the following formulae:
Very preferred are compounds of the Formula XVIIa, wherein L is H or F. Very preferred are compounds of the Formula XVIIb, wherein L is F.
The LC medium may additionally comprise one or more compounds of the following formula:
Particularly preferred compounds of the Formula XXXII are those of the subformulae:
in which
Very particular preference is given to the compounds of the following subformulae:
In some further embodiments, the LC medium comprises one or more compounds of the following formulae:
Very particular preference is given to the compounds of the following subformulae:
Advantageously, the LC medium of the present invention may comprise one or more compounds of the Formula LP1
The one or more compounds of the Formulae LP1 and LP2 may be preferably described by the following Formulae:
The compounds of the general Formulae LP1 and LP2 can also be represented by one of the following structures:
Particularly preferred compounds of the Formula LP1 are those selected from the group consisting of the following subformulae:
Particularly preferred compounds of the Formula LP2 are those selected from the group consisting of the following subformulae:
Very preferred are compounds of the Formulae LP2-1a, LP2-1b, LP2-1c, LP2-1d, and LP2-1 i, LP2-2b, LP2-3a, LP2-3c mostly preferred is the compound Formula LP2-1 b.
Preferably, the LC medium comprises one or more compounds of the Formula LP1 and one or more compounds of the Formula LP2.
The total proportion of the compounds of the Formula LP1 or its subformulae in the LC medium is preferably from 2 to 35%, very preferably from 3 to 25%, mostly preferred from 4 to 15% by weight. The total proportion of the compounds of the Formula LP2 or its subformulae in the LC medium is preferably from 2 to 35%, very preferably from 3 to 25%, mostly preferred from 4 to 15% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula LP1 or their subformulae. In a particularly preferred embodiment, the LC medium comprises at least one compound of the Formula LP1.
In addition to the compounds of the Formula I, an antioxidant and, optionally, a light stabilizer, the LC medium may optionally contain one or more compounds selected from the Formulae Y and B:
The LC medium according to this first preferred embodiment may contain one or more compounds of the Formula I, one or more antioxidants, one or more light stabilizers, one or more compounds selected from the Formulae Z1, Z2 and Z3, and one or more compounds selected from the Formulae Y and B.
The LC media according to this first preferred embodiment are especially suitable for use in LC displays of the HB-FFS or PS-HB-FFS mode.
In the compounds of the Formula Y and its subformulae, R1 and R2 preferably denote straight-chain alkyl or alkoxy having 1 to 6 C atoms, furthermore alkenyl having 2 to 6 C atoms, in particular vinyl, 1E-propenyl, 1E-butenyl, 3-butenyl, 1E-pentenyl, 3E-pentenyl or 4-pentenyl.
In the compounds of the Formula Y and its subformulae, preferably both substituents L1 and L2 denote F. In another preferred embodiment of the present invention, in the compounds of the Formula Y and its subformulae one of the substituents L1 and L2 denotes F and the other denotes Cl.
In a preferred embodiment of the present invention, the LC medium contains one or more compounds of the Formula Y selected from the following subformulae:
Preferably, in the compounds of the Formula Y1 and Y2 both L1 and L2 denote F or one of L1 and L2 denotes F and the other denotes C1, or both L1 and L2 denote F or one of L1 and L2 denotes F and the other denotes Cl.
Preferably, the LC medium comprises one or more compounds of the Formula Y1 selected from the group consisting of the following subformulae:
Very preferably, the LC medium contains one or more compounds of the Formula Y1 selected from the Formulae Y1-1, Y1-2, Y1-7, Y1-12, Y1-17, Y1-22, Y1-40, Y1-41, Y1-42, Y1-44, Y1-50 and Y1-68. L5 preferably denotes a H atom.
Further preferably, the LC medium comprises one or more compounds of the Formula Y2 selected from the group consisting of the following subformulae:
Very preferably, the LC medium contains one or more compounds of the Formula Y2 selected from Formulae Y2-2 and Y2-10.
The proportion of the compounds of the Formula Y1 or its subformulae in the LC medium is preferably from 0 to 10% by weight.
The proportion of the compounds of the Formula Y2 or its subformulae in the LC medium is preferably from 0 to 10% by weight.
The total proportion of the compounds of the Formula Y1 and Y2 or their subformulae in the medium is preferably from 1 to 20%, very preferably from 2 to 15% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula Y1 and Y2 or their subformulae, very preferably selected from the Formulae Y1-2, Y1-22, Y1-66, Y1-70, Y2-6 and Y2-22.
In another preferred embodiment of the present invention, the LC medium contains one or more compounds of the Formula Y of the following subformula:
Preferred compounds of the Formula Y3 are selected from the group consisting of the following subformulae:
Particularly preferred compounds of the Formula Y3 are selected from the group consisting of following subformulae:
Preferably, in the compounds of the Formula Y3 and its subformulae both L1 and L2 denote F. Further preferably in the compounds of the Formula Y3 one of the substituents L1 and L2 denotes F and the other denotes Cl.
The proportion of the compounds of the Formula Y3 or its subformulae in the LC medium is preferably from 0 to 10%, very preferably from 1 to 6% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula Y3 or its subformulae, more preferably of the Formula Y3-6, very preferably of the Formula Y3-6A.
In yet another preferred embodiment of the present invention, the LC medium contains one or more compounds of the Formula Y of the subformula Y4:
Mostly preferred compounds of the Formula Y4 are selected from the group consisting of the following subformulae:
R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.
The proportion of the compounds of the Formula Y4 or its subformulae in the medium is preferably from 0 to 10%, very preferably from 1 to 6% by weight.
Particularly preferred compounds are those of the subformulae
in which
Use of the following compounds is particularly advantageous:
In another preferred embodiment of the present invention, the LC medium contains one or more compounds of the Formula Y selected from the group consisting of the following subformulae:
R5 in these compounds is particularly preferably C2-6-alkyl or -alkoxy or C2-6-alkenyl, d is preferably 1. The LC medium according to the invention preferably comprises one or more compounds of the above-mentioned formulae in amounts of >5% by weight.
Further preferred embodiments are indicated below:
Preferably, both substituents L1 and L2 denote F. Further preferably, one of the substituents L1 and L2 denotes F and the other denotes Cl.
The compounds of the Formula LY are preferably selected from the group consisting of the following subformulae:
R1 preferably denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, in particular CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, 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—.
Very preferred are compounds of the Formula LY4.
Preferably, the medium contains 1, 2 or 3 compounds of the Formula LY, very preferably of the Formula LY4.
The proportion of the compounds of the Formula LY or its subformulae in the medium is preferably from 1 to 10% by weight.
The compounds of the Formula AY are preferably selected from the group consisting of the following subformulae:
R1 preferably denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, in particular CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, 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—.
In the compounds of the Formula B and its subformulae, R1 and R3 preferably denote straight-chain alkyl or alkoxy having 1 to 6 C atoms, in particular methoxy, ethoxy, propoxy or butoxy, furthermore alkenyl having 2 to 6 C atoms, in particular vinyl, 1E-propenyl, 1E-butenyl, 3-butenyl, 1E-pentenyl, 3E-pentenyl or 4-pentenyl.
In a preferred embodiment of the present invention, the medium contains one or more compounds of the Formula B selected from the following subformulae:
Preferred compounds of the Formula B1 are selected from the following subformulae:
Very preferred are compounds of the Formula B1-1 and B1-2 wherein both groups (O) denote an oxygen atom and R1 and R3 independently denote an alkyl group being methyl, ethyl, propyl, butyl, pentyl or hexyl, which are preferably straight-chained. Very preferably one “alkyl” is ethyl and the other “alkyl” is n-pentyl.
Particularly preferred are compounds of the Formula B1-2.
Preferably, the compounds of the Formula B1-1 are selected from the group of compounds of the Formulae B1-1-1 to B1-1-11, preferably of the Formula B1-1-6:
Preferably, the compounds of the Formula B1-2 are selected from the group of compounds of Formulae B1-2-1 to B1-2-10, preferably of Formula B1-2-6:
Optionally, the LC medium comprises one or more compounds of the Formula B1-1A and/or B1-2A:
The compounds of the Formulae B1-1A and/or B1-2A are contained in the medium either alternatively or in addition to the compounds of the Formulae B1-1 and B1-2, preferably additionally.
Preferred compounds of the Formulae B1-1A and/or B1-2A are also the following:
The proportion of the compounds of the Formula B1 or its subformulae in the LC medium is preferably from 1 to 20%, very preferably from 1 to 15% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula B1 or its subformulae.
In a preferred embodiment of the present invention, the LC medium may comprise one or more compounds of the Formula B2-2
The compounds of the Formula B2-2 are preferably selected from the group of compounds of the Formulae B2-2-1 to B2-2-10:
Particularly preferred compounds of the Formula B2 are selected from the following subformulae:
The proportion of the compounds of the Formula B2 or its subformulae in the LC medium is preferably from 1 to 20%, very preferably from 1 to 15% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula B2 or its subformulae.
Preferred compounds of the Formula B3 are selected from the following subformulae:
Preferred compounds of the Formula B3 are selected from the following subformulae:
Most preferred are compounds of the Formulae B3-1-1 and B3-2-2.
In a preferred embodiment, the LC medium contains one or more compounds of the Formula B or its subformulae B1, B2, B3, B1-1, B1-2, B2-1, B2-2, B2-3, B3-1, B3-2, B3-1-1, B3-1-2, B3-2-1 and B3-2-2 wherein the dibenzofuran or dibenzothiophene group is substituted by a methyl or methoxy group, preferably by a methyl group, preferably in p-position to the substituent F, very preferably in p-position to the substituent F (i.e. in m-position to the terminal group R2 or X1).
The proportion of the compounds of the Formula B3 or its subformulae in the LC medium is preferably from 1 to 20%, very preferably from 1 to 10% by weight.
Preferably, the LC medium contains 1, 2 or 3 compounds of the Formula B3 or its subformulae.
Preferably, the total proportion of compounds of the Formula Y and B or their subformulae in the LC medium is from 2 to 25%, very preferably from 3 to 20% by weight.
Further preferred LC media are selected from the following preferred embodiments, including any combination thereof:
The term “alkyl” or “alkyl” in this application encompasses straight-chain and branched alkyl groups having 1 to 6 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl and hexyl. Groups having 2 to 5 carbon atoms are generally preferred.
The term “alkenyl” or “alkenyl*” encompasses straight-chain and branched alkenyl groups having 2 to 6 carbon atoms, in particular the straight-chain groups. Preferred alkenyl groups are C2-7-1E-alkenyl, C4-C6-3E-alkenyl, in particular C2-C6-1E-alkenyl. Examples of particularly preferred alkenyl groups are vinyl, E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl and 5-hexenyl. Groups having up to 5 carbon atoms are generally preferred, in particular CH2═CH, CH3CH═CH.
The term “fluoroalkyl” preferably encompasses straight-chain groups having 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 term “oxaalkyl” or “alkoxy” preferably encompasses straight-chain groups 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=1 to 6 or m=0 and n=1 to 3. Further preferably the alkoxy or oxaalkyl group can also contain one or more further O atoms such that oxygen atoms are not directly linked to one another.
Through a suitable choice of the meanings of R0 and X0 in Formulae II and III, 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 groups, 3E-alkenyl groups, 2E-alkenyloxy groups and the like generally result in shorter addressing times, improved nematic tendencies and a higher ratio between the elastic constants K3 (bend) and K1 (splay) compared with alkyl and alkoxy groups. 4-Alkenyl groups, 3-alkenyl groups and the like generally give lower threshold voltages and lower values of K3/K1 compared with alkyl and alkoxy groups. The LC media according to the invention are distinguished, in particular, by high Δε values and thus have significantly faster response times than the LC media 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 LC media according to the invention is not crucial. The LC media can therefore comprise one or more further components for the purposes of optimisation of various properties.
However, the observed effect on the desired improvement in the properties of the medium is generally greater, the higher the total concentration of compounds of the above-mentioned formulae.
In a particularly preferred embodiment, the LC media according to the invention comprise compounds of the Formulae IV to VIII (preferably IV and V) 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, an antioxidant and, if present, a light stabilizer results in particularly advantageous properties. In particular, LC media comprising compounds of the Formula I, an antioxidant, a light stabilizer, II and/or III are distinguished by their low threshold voltage.
The individual compounds of the above-mentioned formulae and the subformulae thereof which can be used in the LC media according to the invention are either known or can be prepared analogously to the known compounds.
The invention also relates to a process for the preparation of a LC medium as described above and below, by mixing one or more compounds of the Formula I, an antioxidant, a light stabilizer and one or more compounds selected from the group consisting of the Formulae II, III, Z1, Z2, Z3, Z4, IV, VI, XIV, XVI, XVIIa, XVIIb, XVIIc, XX, XXIII, XXIX.
The LC medium of the present invention may optionally comprise one or more polymerisable compounds. The polymerisable compounds are preferably selected from the Formula M
Ra—B1—(Zb—B2)m—Rb M
Further preferably, the LC media according to the present invention comprise one or more polymerisable compounds selected from Table H below.
Preferably, the proportion of polymerisable compounds in the LC medium, preferably selected from the Formula M and Table H, is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.
It was observed that the addition of one or more polymerisable compounds to the LC medium, like those selected from the Formula M and Table H, leads to advantageous properties like fast response times. Such a LC medium is especially suitable for use in PSA displays where it shows low image sticking, a quick and complete polymerisation, the quick generation of a low pretilt angle which is stable after UV exposure, a high reliability, high VHR value after UV exposure, and a high birefringence. By appropriate selection of the polymerisable compounds it is possible to increase the absorption of the LC medium at longer UV wavelengths, so that it is possible to use such longer UV wavelengths for polymerisation, which is advantageous for the display manufacturing process.
The polymerisable group P is a group which is suitable for a polymerisation reaction, such as, for example, free-radical or ionic chain polymerisation, polyaddition or polycondensation, or for a polymer-analogous reaction, for example addition or condensation onto a main polymer chain. Particular preference is given to groups for chain polymerisation, in particular those containing a C═C double bond or —C≡C— triple bond, and groups which are suitable for polymerisation with ring opening, such as, for example, oxetane or epoxide groups.
Preferred groups P are selected from the group consisting of CH2═CW1—CO—O—, CH2=CW1—CO—,
CH2=CW2—(O)k3—, CW1═CH—CO—(O)k3—, CW1═CH—CO—NH—, CH2=CW1—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—, HO—CW2W3—, HS—CW2W3—, HW2N—, HO—CW2W3—NH—, CH2=CW1—CO—NH—, CH2═CH—(COO)k1-Phe-(O)k2—, CH2═CH—(CO)k1-Phe-(O)k2—, Phe-CH═CH—, HOOC—, OCN— and W4W5W6Si—, in which W1 denotes H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, C1 or CH3, W2 and W3 each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W4, W5 and W6 each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W7 and W8 each, independently of one another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, which is optionally substituted by one or more substituents L as defined for the Formula M above which are other than P-Sp-, k1, k2 and k3 each, independently of one another, denote 0 or 1, k3 preferably denotes 1, and k4 denotes an integer from 1 to 10.
Very preferred groups P are selected from the group consisting of CH2═CW1—CO—O—, CH2=CW1—CO—,
CH2=CW2—O—, CH═CW2—, CW1═CH—CO—(O)k3—, CW1═CH—CO—NH—, CH2=CW1—CO—NH—, (CH2═CH)2CH—OCO—, (CH2═CH—CH2)2CH—OCO—, (CH2═CH)2CH—O—, (CH2═CH—CH2)2N—, (CH2═CH—CH2)2N—CO—, CH2=CW1—CO—NH—, CH2═CH—(COO)k1-Phe-(O)k2—, CH2═CH—(CO)k1-Phe-(O)k2—, Phe-CH═CH— and W4W5W6Si—, in which W1 denotes H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W2 and W3 each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W4, W5 and W6 each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W7 and W8 each, independently of one another, denote H, C or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, k1, k2 and k3 each, independently of one another, denote 0 or 1, k3 preferably denotes 1, and k4 denotes an integer from 1 to 10.
Very particularly preferred groups P are selected from the group consisting of CH2═CW1—CO—O—, in particular CH2═CH—CO—O—, CH2=C(CH3)—CO—O— and CH2=CF—CO—O—, furthermore CH2═CH—O—, (CH2═CH)2CH—O—CO—, (CH2═CH)2CH—O—,
Further preferred polymerisable groups P are selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.
If Sp is different from a single bond, it is preferably of the Formula Sp″-X″, so that the respective substituent P-Sp- conforms to the Formula P-Sp″-X″—, wherein
Typical spacer groups Sp and -Sp″-X″— are, for example, —(CH2)p1—, —(CH2CH2O)g1—CH2CH2—, —CH2CH2—S—CH2CH2—, —CH2CH2—NH—CH2CH2— or —(SiR0R00—O)p1—, in which p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R0 and R00 have the meanings indicated in the Formula M above.
Particularly preferred groups Sp and -Sp″-X″— are —(CH2)p1—, —(CH2)p1—O—, —(CH2)p1—O—CO—, —(CH2)p1—CO—O—, —(CH2)p1—O—CO—O—, in which p1 and q1 have the meanings indicated above.
Particularly preferred groups Sp″ are, in each case straight-chain, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.
For the production of PSA displays, the polymerisable compounds contained in the LC medium are polymerised or crosslinked (if one compound contains two or more polymerisable groups) by in-situ polymerisation in the LC medium between the substrates of the LC display, optionally while a voltage is applied to the electrodes.
The structure of the PSA displays according to the invention corresponds to the usual geometry for PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, in particular those in which, in addition, the electrode on the colour filter side is unstructured and only the electrode on the TFT side has slots. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006/0066793 A1.
The combination of compounds of the preferred embodiments mentioned above with the polymerised compounds described above causes low threshold voltages, low rotational viscosities and very good low-temperature stabilities in the LC media according to the invention at the same time as constantly high clearing points and high VHR values.
The use of LC media containing polymerisable compounds allows the rapid establishment of a particularly low pretilt angle in PSA displays. In particular, the LC media exhibit significantly shortened response times, in particular also the grey-shade response times, in PSA displays compared with the media from the prior art.
Preference is generally given to LC media which have a nematic LC phase, and preferably have no chiral liquid crystal phase.
The invention also relates to the use of a LC medium according to the present invention as described above and below for electro-optical purposes, in particular for the use is in shutter glasses, for 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA and positive PS-VA displays, and to electro-optical displays, in particular of the aforementioned types, containing a LC medium according to the present invention as described above and below, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA (vertically aligned) or positive PS-VA display.
The invention also relates to electro-optical displays, such as, for example, STN or matrix LC (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 LC medium having positive dielectric anisotropy and high specific resistance located in the cell, wherein the nematic LC medium is a LC medium according to the present invention as described above and below.
The LC media according to the invention enable a significant broadening of the available parameter latitude. The achievable combinations of clearing point, rotational viscosity, thermal- and UV stability and high optical anisotropy are far superior to previous materials from the prior art.
In particular, the combination of compounds of the Formula I with at least one antioxidant, at least one light stabilizer and, optionally, with compounds selected from the Formulae II-XXXII or their subformulae, leads to LC media which show a reduced short-term image sticking and reduced long-term image sticking as well as low rotational viscosity resulting in fast response times. This enables fast energy saving LC displays, especially of the FFS, HB-FFS, XB-FFS and IPS mode.
The LC media according to the invention are suitable for mobile applications and TFT applications, such as, for example, mobile telephones and PDAs. Furthermore, the LC media according to the invention are particularly suitably for use in FFS, HB-FFS, XB-FFS and IPS displays based on dielectrically positive liquid crystals.
The LC media according to the present 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 ≥75° C., preferably 80° C., at the same time allow rotational viscosities γ1 of ≤120 mPa·s, particularly preferably ≤100 mPa-s, to be achieved, enabling excellent MLC displays having fast response times to be achieved. The rotational viscosities are determined at 20° C.
The dielectric anisotropy Δε of the LC media according to the invention at 20° C. and 1 kHz is preferably ≥+1.5, very preferably from +3 to +18, most preferred from +5 to +15.
The birefringence Δn of the LC media according to the invention at 20° C. is preferably from 0.08 to 0.2, very preferably from 0.09 to 0.15.
The rotational viscosity γ1 of the LC media according to the invention is preferably ≤120 mPa·s, more preferably ≤110 mPa·s, very preferably 90 mPa·s.
The ratio γ1/K1 (wherein γ1 is the rotational viscosity and K1 is the elastic constant for splay deformation) of the LC media according to the invention is preferably 7 mPa·s/pN, very preferably 6 mPa·s/pN, most preferably ≤5.5 mPa·s/pN.
The average elasticity constant ratio Kav of the LC media according to the invention is preferably at least 14.0 pN, very preferably at least 15.0 pN, most preferably at least 16.0 pN. Kav can be calculated according to the following formula: Kav=(K1+K2+K3)/3≈(K1+1/2%2*K1+K3)/3.
The nematic phase range of the LC media according to the invention preferably has a width of at least 90° C., more preferably of at least 100° C., in particular at least 110° C. This range preferably extends at least from −25° C. to +90° C.
It goes without saying that, through a suitable choice of the components of the LC media 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 LC media having a higher Δε 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 LC media according to the invention at the first minimum than in the case of LC media 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.
Measurements of the voltage holding ratio (VHR) [S. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); G. Weber et al., Liquid Crystals 5, 1381 (1989)]have shown that LC media according to the invention exhibit a significantly smaller decrease in the VHR on UV exposure than analogous LC media comprising cyanophenylcyclohexanes of the Formula
or esters of the Formula.
The light stability and UV stability of the LC media according to the invention are considerably better, i.e. they exhibit a significantly smaller decrease in the HR on exposure to light, heat or UV.
The construction of the MLC display according to the invention from polarisers, 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 LC parameters of the LC layer.
The LC media which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing compounds of Formula I with one or more compounds of the Formulae II-XXXII or with further LC compounds and/or additives. In general, the desired amount of the components used in lesser 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 thor-ough mixing.
The LC media may also comprise further additives known to the person skilled in the art and described in the literature, such as, for example, polymerisation initiators, inhibitors, surface-active substances, microparticles, free-radical scaven-gers, nanoparticles, etc. For example, 0 to 15% of pleochroic dyes or chiral dopants or initiators like Irgacure®651 or Irgacure®907 can be added. Suitable stabilisers and dopants are mentioned below in Tables F and G. In a preferred embodiment, the LC medium comprises one or more stabilisers selected from Table G. Preferably, the proportion of antioxidants and light stabilisers, like those of the Formula ST and H, as described above or listed in Table G, in the LC medium is from 10 to 2000 ppm, very preferably from 30 to 1000 ppm.
Furthermore, it is possible to add to the LC media, for example, 0 to 15% by weight of pleochroic dyes, furthermore nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)), for improving the conductivity, or substances for modifying the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases. Substances of this type are described, for example, in DE-A 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.
For the present invention and in the following examples, the structures of the LC compounds are indicated by means of acronyms, with the transformation into chemical formulae taking place in accordance with Tables A to C below. All substituents CmH2m+1, CnH2n+1, and ClH2l+1 or CmH2m−1, CnH2n−1 and ClH2l−1 are straight-chain alkyl groups or alkylene groups, in each case having n, m and I C atoms respectively. Preferably, n, m and l are independently of each other 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes for the ring elements of the nuclei of the compound, Table B lists the bridging units, and Table C lists the meanings of the symbols for the left- and right-hand end groups of the molecules. The acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group. Table D shows illustrative structures of compounds together with their respective abbreviations.
The following abbreviations are used:
Preferred components of the LC medium are shown in Tables D and E.
Particular preference is given to LC media which, besides the compounds of the Formulae I, an antioxidant and a light stabilizer comprise at least one, two, three, four or more compounds from Table E.
n = 1, 2, 3, 4, 5, 6 or 7
n = 1, 2, 3, 4, 5, 6 or 7
n = 1, 2, 3, 4, 5, 6 or 7
q = 1, 2, 3, 4, 5, 6 or 7
q = 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10
In a preferred embodiment, the LC media, SA-VA and SA-FFS displays according to the present invention com¬prise one or more SA additives selected from the Formulae SA-1 to SA-49, preferably from the Formulae SA-14 to SA-49, very preferably from the Formulae SA-20 to SA-34 and SA-44, in combination with one or more RMs.
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. m.p. denotes melting point, cl.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase, S=smectic phase and I=isotropic phase. The data between these symbols represent the transition temperatures. Furthermore, the following symbols are used
voltage holding ratio.
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.
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
ST-2-3
H-3-3
A nematic L9 medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
ST-1-8
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
H-3-11
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
ST-1-3
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
APUQU-3-F(1)
PGUQU-3-F(1)
PGUQU-4-F(1)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
H-3-1
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
H-3-7
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
H-3-22
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
H-3-23
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
PPGU-(c5)-F
A nematic LC medium is formulated as follows:
A nematic LC medium is formulated as follows:
CLU-3-F(1)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
APUQU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUQU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
DGUQU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
DPGU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
DLGU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUS-(c5)-2
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUS-3-(c5)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUS-3-1(c5)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUS-3-O(c5)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PUS-3-O1(c5)
A nematic LC mixture according to the invention is formulated as follows:
ST-4-1
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
ST-4-2
A nematic LC medium is formulated as follows:
PGS-(c5)-1
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PGS-2-(c5)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
PGS-2-O(c5)
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
A nematic LC mixture according to the invention is formulated as follows:
A nematic LC medium is formulated as follows:
DUQU-(c5)-F
A nematic LC mixture according to the invention is formulated as follows:
| Number | Date | Country | Kind |
|---|---|---|---|
| 23218161 | Dec 2023 | EP | regional |