LIQUID-CRYSTAL MEDIUM

Abstract

A liquid-crystal (LC) media having a negative dielectric anisotropy containing a compound of formula I

##STR00001##

and the use of the LC media for optical, electro-optical and electronic purposes, in particular in energy-efficient LC displays, especially in IPS, FFS, VA or PS-VA displays.

Claims

1. A liquid-crystal medium having a negative dielectric anisotropy and comprising one or more compounds of formula I ##STR00531## in which R.sup.1 denotes a straight-chain or branched alkenyl radical having 2 to 15 C atoms, where one or more CH.sub.2 groups may each be replaced, independently of one another, by ##STR00532## —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, R.sup.2 denotes H, a straight-chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups may each be replaced, independently of one another, by ##STR00533## —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, and Y.sup.1 denotes H, F, Cl or CH.sub.3.

2. The liquid-crystal medium according to claim 1, further comprising one or more compounds selected from the group consisting of compounds of formulae IIA, IIB, IIC and IID ##STR00534## in which R.sup.2A, R.sup.2B, R.sup.2C and R.sup.2D each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, where one or more CH.sub.2 groups may be replaced by —O—, —S—, ##STR00535## —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, L.sup.1 to L.sup.4 each, independently of one another, denote F, C, CF.sub.3 or CHF.sub.2, Y denotes H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, Z.sup.2, Z.sup.2B and Z.sup.2D each, independently of one another, denote a single bond, —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —COO—, —OCO—, —C.sub.2F.sub.4—, —CF═CF— or —CH═CHCH.sub.2O—, p denotes 0, 1 or 2, q denotes 0 or 1, and v denotes 1, 2, 3, 4, 5 or 6.

3. The medium according to claim 1, further comprising one or more compounds of formula III ##STR00536## in which R.sup.11 and R.sup.12 each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups may each be replaced, independently of one another, by ##STR00537## —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, A.sup.1 on each occurrence, independently of one another, denotes a) a 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH.sub.2 groups may be replaced by —O— or —S—, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, where the radicals in a), b) and c) may be mono- or polysubstituted by halogen atoms, n is 0, 1 or 2, Z.sup.1 on each occurrence, independently of one another, denotes —CO—O—, —O—CO—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CH.sub.2—, —CH.sub.2CH.sub.2—, —(CH.sub.2).sub.4—, —CH═CH—CH.sub.2O—, —C.sub.2F.sub.4—, —CH.sub.2CF.sub.2—, —CF.sub.2CH.sub.2—, —CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—, —C═C— or a single bond, L.sup.11 and L.sup.12 each, independently of one another, denote F, Cl, CF.sub.3 or CHF.sub.2, and W denotes O or S.

4. The medium according to claim 1, further comprising one or more compounds of formula IV ##STR00538## in which R.sup.41 denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, and R.sup.42 denotes alkyl having 1 to 7 C atoms or alkoxy having 1 to 6 C atoms or alkenyl having 2 to 7 C atoms.

5. The medium according to claim 1, further comprising one or more compounds selected from the group consisting of compounds of the following formulae ##STR00539##

6. The medium according to claim 1, further comprising one or more compounds of formulae IVb-1 to IVb-3 ##STR00540## in which alkyl and alkyl* each, independently of one another, denote alkyl having 1 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote alkenyl having 2 to 6 C atoms.

7. The medium according to claim 1, further comprising one or more compounds of formula V ##STR00541## in which R.sup.51 and R.sup.52 each, independently of one another, denote alkyl having 1 to 7 C atoms, alkoxy having 1 to 7 C atoms or alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, ##STR00542## and ##STR00543## identically or differently, denote ##STR00544## Z.sup.51 and Z.sup.52 each, independently of one another, denote —CH.sub.2—CH.sub.2—, —CH.sub.2—O—, —CH═CH—, —C≡C—, —COO— or a single bond, and n is 1 or 2.

8. The medium according to claim 1, further comprising a chiral dopant.

9. The medium according to claim 1, further comprising one or more polymerisable compounds of formula P
P-Sp-A.sup.1-(Z.sup.1-A.sup.2).sub.r-R  P in which P denotes a polymerisable group, Sp denotes a spacer group or a single bond, A.sup.1 and A.sup.2 identically or differently, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L, L denotes F, Cl, —CN, P—Sp- or a straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH.sub.2 groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a manner that O and/or S atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl, Z.sup.1 denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —OCH.sub.2—, —CH.sub.2O—, —SCH.sub.2—, —CH.sub.2S—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —(CH.sub.2).sub.n1—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1—, —CH═CH—, —CF═CF—, —CH═CF—, —CF═CH—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH.sub.2—CH.sub.2—CO—O—, —O—CO—CH.sub.2—CH.sub.2—, —CR.sup.0R.sup.00— or a single bond, R.sup.0 and R.sup.00 identically or differently, denote H or alkyl having 1 to 12 C atoms, R denotes H, L, or P-Sp-, z is 0, 1, 2 or 3, and n1 is 1, 2, 3 or 4.

10. The medium according to claim 9, wherein the one or more polymerisable compounds of formula P are polymerised.

11. A liquid-crystal display, comprising the medium according to claim 1.

12. The display according to claim 11, which is a PSA display.

13. The display according to claim 12, which is a PS-VA, PS-IPS, PS-FFS, PS—UB-FFS, polymer stabilised SA-VA or polymer stabilised SA-FFS display.

14. The display according to claim 11, wherein the display is a VA, IPS, U-IPS, FFS, UB-FFS, SA-FFS or SA-VA display.

15. An electro-optical display, comprising the medium according to claim 1.

16. The medium according to claim 1, exhibiting a dielectric anisotropy Δε of −6 to −2.

17. The medium according to claim 1, exhibiting an optical anisotropy Δn of 0.08 to 0.13.

18. The medium according to claim 1, wherein the compound of formula I is a compound of one of formulae I-1 to I-10 ##STR00545## in which R.sup.1 and R.sup.2 have the meanings given for formula I.

19. The medium according to claim 1, wherein the compound of formula I is a compound of one of formulae I-a to I-f ##STR00546## in which R.sup.2 has the meaning given for formula I.

20. The medium according to claim 1, wherein the compound of formula I is a compound of one of formulae I-a-1 or I-a-2 ##STR00547##

Description

WORKING EXAMPLES

[0454] Unless indicated otherwise, all concentrations herein are indicated in percent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents. 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.

[0455] The symbols and abbreviations have the following meanings: [0456] V.sub.0 Freedericksz threshold voltage, capacitive [V] at 20° C., [0457] V.sub.10 voltage [V] for 10% transmission, [0458] n.sub.e extraordinary refractive index measured at 20° C. and 589 nm, [0459] n.sub.0 ordinary refractive index measured at 20° C. and 589 nm, [0460] Δn optical anisotropy measured at 20° C. and 589 nm, [0461] ε.sub.⊥ dielectric susceptibility (or “dielectric constant”) perpendicular to the longitudinal axes of the molecules at 20° C. and 1 kHz, [0462] ε.sub.∥ dielectric susceptibility (or “dielectric constant”) parallel to the longitudinal axes of the molecules at 20° C. and 1 kHz, [0463] Δε dielectric anisotropy at 20° C. and 1 kHz, cl.p. or [0464] T(N,I) clearing point [° C.], [0465] ν flow viscosity measured at 20° C. [mm.sup.2.Math.s.sup.−1], [0466] γ.sub.1 rotational viscosity measured at 20° C. [mPa.Math.s], [0467] K.sub.11 elastic constant, “splay” deformation at 20° C. [pN], [0468] K.sub.22 elastic constant, “twist” deformation at 20° C. [pN], [0469] K.sub.33 elastic constant, “bend” deformation at 20° C. [pN], [0470] LTS low-temperature stability of the phase, determined in bulk, and [0471] VHR voltage holding ratio.

[0472] The term “threshold voltage” for the present invention relates to the capacitive threshold (V.sub.0), unless explicitly indicated otherwise. In the Examples, as is generally usual, the optical threshold can also be indicated, for example for 10% relative contrast (V.sub.10).

Examples and Comparative Examples

Mixture Examples and Comparative Mixture Examples

[0473]

TABLE-US-00008 Comparative Mixture C1 CC-3-V 31.0% Clearing point/° C.: 82.5 CC-3-V1 4.0% Δn (589 nm, 20° C.): 0.1096 PP-1-2V1 2.0% Δε (1 kHz, 20° C.): −4.2 CY-3-O2 14.0% K.sub.1 (pN, 20° C.): 14.2 CCY-3-O1 6.0% K.sub.3 (pN, 20° C.): 15.6 CCY-3-O2 6.0% γ.sub.1 (20° C.)/mPa .Math. s: 90 CCY-5-O2 6.0% γ.sub.1/K.sub.1: 6.3 CPY-2-O2 8.0% CPY-3-O2 9.0% PGIY-2-O4 2.0% PYP-2-3 3.0% B(S)-2O-O4 5.0% B(S)-2O-O5 4.0% Σ 100.0% Comparative Mixture C2 CC-3-V 33.0% Clearing point/° C.: 83.1 CC-3-V1 4.0% Δn (589 nm, 20° C.): 0.1088 CY-3-O2 14.0% Δε (1 kHz, 20° C.): −4.3 CCY-3-O1 2.0% K.sub.1 (pN, 20° C.): 14.1 CCY-3-O2 12.0% K.sub.3 (pN, 20° C.): 15.7 CLY-3-O2 2.0% γ.sub.1 (20° C.)/mPa .Math. s: 91 CPY-2-O2 9.0% γ.sub.1/K.sub.1: 6.5 CPY-3-O2 10.0% PGIY-2-O4 2.0% PYP-2-3 3.0% B(S)-2O-O4 5.0% B(S)-2O-O5 4.0% Σ 100.0% Comparative Mixture C3 CC-3-V 34.0% Clearing point/° C.: 83.2 CC-3-V1 3.0% Δn (589 nm, 20° C.): 0.1097 CY-3-O2 14.0% Δε (1 kHz, 20° C.): −4.3 CCY-3-O2 7.0% K.sub.1 (pN, 20° C.): 14.1 CLY-4-O2 5.0% K.sub.3 (pN, 20° C.): 15.5 CLY-3-O2 5.0% γ.sub.1 (20° C.)/mPa .Math. s: 88 CPY-2-O2 8.0% γ.sub.1/K.sub.1: 6.2 CPY-3-O2 10.0% PGIY-2-O4 2.0% PYP-2-3 3.0% B(S)-2O-O4 5.0% B(S)-2O-O5 4.0% Σ 100.0% Comparative Mixture C4 CC-3-V 30.0% Clearing point/° C.: 80.4 CC-3-V1 5.0% Δn (589 nm, 20° C.): 0.1108 PP-1-2V1 6.0% Δε (1 kHz, 20° C.): −4.0 CY-3-O2 13.0% K.sub.1 (pN, 20° C.): 14.3 CCY-3-O1 5.0% K.sub.3 (pN, 20° C.): 16.0 CCY-3-O2 10.0% γ.sub.1 (20° C.)/mPa .Math. s: 85 CPY-2-O2 11.0% γ.sub.1/K.sub.1: 5.9 CPY-3-O2 11.0% B(S)-2O-O4 4.0% B(S)-2O-O5 5.0% Σ 100.0% Comparative Mixture C5 CC-3-V 33.0% Clearing point/° C.: 78.1 PP-1-2V1 6.0% Δn (589 nm, 20° C.): 0.1075 CY-3-O2 15.0% Δε (1 kHz, 20° C.): −4.0 CY-5-O2 4.0% K.sub.1 (pN, 20° C.): 13.4 CCY-3-O2 11.0% K.sub.3 (pN, 20° C.): 14.9 CPY-2-O2 11.0% γ.sub.1 (20° C.)/mPa .Math. s: 88 CPY-3-O2 11.0% γ.sub.1/K.sub.1: 6.6 COB(S)-2-O4 9.0% Σ 100.0% Mixture M1 CC-3-V 30.0% Clearing point/° C.: 80.4 CC-3-V1 5.0% Δn (589 nm, 20° C.): 0.1099 PP-1-2V1 5.0% Δε (1 kHz, 20° C.): −4.0 CLP-V-1 1.0% K.sub.1 (pN, 20° C.): 14.4 CY-3-O2 14.0% K.sub.3 (pN, 20° C.): 15.8 CCY-3-O1 4.0% γ.sub.1 (20° C.)/mPa .Math. s: 86 CCY-3-O2 10.0% γ.sub.1/K.sub.1: 6.0 CPY-2-O2 11.0% CPY-3-O2 11.0% B(S)-2O-O4 4.0% B(S)-2O-O5 5.0% Σ 100.0% Mixture M2 CC-3-V 30.0% Clearing point/° C.: 81.2 CC-3-V1 4.0% Δn (589 nm, 20° C.): 0.1101 PP-1-2V1 4.0% Δε (1 kHz, 20° C.): −4.0 CLP-V-1 3.0% K.sub.1 (pN, 20° C.): 14.3 CY-3-O2 15.0% K.sub.3 (pN, 20° C.): 15.9 CCY-3-O1 3.0% γ.sub.1 (20° C.)/mPa .Math. s: 87 CCY-3-O2 10.0% γ.sub.1/K.sub.1: 6.1 CPY-2-O2 11.0% CPY-3-O2 11.0% B(S)-2O-O4 4.0% B(S)-2O-O5 5.0% Σ 100.0% Mixture M3 CC-3-V 32.0% Clearing point/° C.: 79.3 PP-1-2V1 6.0% Δn (589 nm, 20° C.): 0.1088 CY-3-O2 15.0% Δε (1 kHz, 20° C.): −4.0 CY-5-O2 4.0% K.sub.1 (pN, 20° C.): 13.6 CLP-V-1 1.0% K.sub.3 (pN, 20° C.): 15.2 CCY-3-O2 11.0% γ.sub.1 (20° C.)/mPa .Math. s: 92 CPY-2-O2 11.0% γ.sub.1/K.sub.1: 6.8 CPY-3-O2 11.0% COB(S)-2-O4 9.0% Σ 100.0% Mixture M4 CC-3-V 30.0% CC-3-V1 4.0% PP-1-2V1 4.0% CLP-V-1 3.0% CY-3-O2 15.0% CCY-3-O1 3.0% CCY-3-O2 10.0% CPY-2-O2 11.0% CPY-3-O2 11.0% B(S)-(c5)2O-O4 4.0% B(S)-2O-O5 5.0% Σ 100.0%

[0474] Mixture M5

[0475] The following mixture is prepared, wherein the compound I-a-2 is specified and shown in the description above.

TABLE-US-00009 CC-3-V 32.0% PP-1-2V1 6.0% CY-3-O2 15.0% CY-5-O2 4.0% compound I-a-2 1.0% CCY-3-O2 11.0% CPY-2-O2 11.0% CPY-3-O2 11.0% COB(S)-2-O4 9.0% Σ 100.0% Mixture M6 CC-3-V 32.0% PP-1-2V1 6.0% CY-3-O2 15.0% CY-5-O2 4.0% CLP-V-1 1.0% CCY-(c5)-O2 11.0% CPY-2-O2 11.0% CPY-3-O2 11.0% COB(S)-2-O4 9.0% Σ 100.0%

[0476] Mixtures M7, M8 and M9

[0477] Mixtures M7, M8 and M9 are respectively prepared by mixing 99.70% of mixtures M1, M2 and respectively M3 as described above with 0.30% of the compound of formula

##STR00528##

[0478] Mixture M10

[0479] A mixture M10 is prepared by mixing 99.51% of mixture M7 and 0.49% of chiral dopant S-811 available from Merck KGaA, Darmstadt, Germany.

[0480] Mixture M11

[0481] A mixture M11 is prepared by mixing 99.70% of mixture M8 and 0.30% of the compound of formula

##STR00529##

[0482] Mixture M12

[0483] A mixture M12 is prepared by mixing 99.60% of mixture M9 and 0.40% of the compound of formula

##STR00530##

[0484] The mixtures M1 to M12 having negative dielectric anisotropy are suitable for liquid-crystal displays, in particular IPS, FFS, UB-FFS (ultra-bright FFS) and VA displays.

[0485] VHR Measurements

[0486] The VHR values of the comparative mixtures C4 and C5 and the mixtures M1, M2 and M3 are measured at 60° C. in VHR test cells (3 μm cell gap thickness), using 1V with a frequency of 3 Hz, before and after UV exposure using a metal halide lamp (600W, 200-780 nm with a 320 nm cut filter) for 128 s at room temperature. The results are shown below in Table 1.

TABLE-US-00010 TABLE 1 VHR values VHR/% before UV VHR/% after UV C4 95.8 92.7 M1 95.6 93.9 M2 95.9 93.9 C5 96.2 94.2 M3 96.8 95.3

[0487] The comparisons show favourable VHR characteristics of the liquid-crystal media according to the invention, while at the same time exhibiting suitable electro-optical performance.

[0488] It is surprisingly found that the compounds of formula I can contribute to the stabilising effect giving favourable reliability of the media.

[0489] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0490] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. From the description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

[0491] The entire disclosures of all applications, patents and publications, cited herein and of corresponding EO application No. 21159636.6, filed Feb. 26, 2021, are incorporated by reference herein.