LIQUID-CRYSTALLINE MEDIUM

Abstract

The present invention relates to a liquid-crystal material (LC media) comprising thiophene derivatives which are stabilised by sterically hindered amines or amine derivatives (HALS, hindered amine light stabilisers), and to liquid-crystal displays (LC displays) which contain these LC materials.

Claims

1. LC medium, characterised in that it comprises one or more compounds of the formula I, ##STR00208## in which the individual radicals have the following meanings: R.sup.1 and R.sup.2 denote H, F, Cl, Br, —CN, —SCN, —NCS, SF.sub.5 or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that 0 atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, C.sub.1 or Br, A.sup.0, A.sup.1 and A.sup.2 each, independently of one another, denote phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH.sub.3, CHF.sub.2, CH.sub.2F, CF.sub.3, OCH.sub.3, OCHF.sub.2 or OCF.sub.3, cyclohexane-1,4-diyl, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced, independently of one another, by 0 and/or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, Z.sup.1 and Z.sup.2 each, independently of one another, denote —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2H.sub.4—, —C.sub.2F.sub.4—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —CFHCFH—, —CFHCH.sub.2—, —CH.sub.2CFH—, —CF.sub.2CFH—, —CFHCF.sub.2—, —CH═CH—, —CF═CH—, —CH═CF—, —CF═CF—, —C≡C— or a single bond, m and n each, independently of one another, denote 0, 1, 2 or 3, and and one or more compounds of the formula H ##STR00209## in which R.sup.H denotes H, O.sup.−, CH.sub.3, OH or OR.sup.S, R.sup.S denotes alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms; R.sup.11 on each occurrence, independently of one another, denotes H, F, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one —CH.sub.2— group or, if present, a plurality of —CH.sub.2— groups may be replaced by —O— or —C(═O)—, but two adjacent —CH.sub.2— groups cannot be replaced by —O—, and one or, if present, a plurality of —CH.sub.2— groups may be replaced by —CH═CH— or —C≡C—, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.12 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl chain having 1-20 C atoms, in which one —CH.sub.2— group or a plurality of —CH.sub.2— groups may be replaced by —O— or —C(═O)—, but two adjacent —CH.sub.2— groups cannot be replaced by —O—, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one —CH.sub.2— group or a plurality of —CH.sub.2— groups may be replaced by —O— or —C(═O)—, but two adjacent —CH.sub.2— groups cannot be replaced by —O—, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.13 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms, R.sup.14 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms, R.sup.15 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms, in which one —CH.sub.2— group or a plurality of —CH.sub.2— groups may be replaced by —O— or —C(═O)—, but two adjacent —CH.sub.2— groups cannot be replaced by —O—, S.sup.11 and S.sup.12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, which is branched or straight-chain, in which one —CH.sub.2— group or, if present, a plurality of —CH.sub.2— groups may be replaced by —O— or —C(═O)—, but two adjacent —CH.sub.2— groups cannot be replaced by —O—, and one or, if present, a plurality of —CH.sub.2— groups may be replaced by —CH═CH— or —C≡C— and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or denote a single bond, X.sup.11 denotes C, Y.sup.11 to Y.sup.14 each, independently of one another, denote methyl or ethyl, Z.sup.11 to Z.sup.14 on each occurrence, independently of one another, denote —O—, —(C═O)—, —O—(C═O)—, —(C═O)—O—, —O—(C═O)—O—, —(N—R.sup.13)—, —N—R.sup.13—(C═O)— or a single bond if S.sup.11 is a single bond, but both Z.sup.11 and Z.sup.12 do not simultaneously denote —O—, and, however, if S.sup.12 is a single bond, both Z.sup.13 and Z.sup.14 do not simultaneously denote —O—, and, however, if —X.sup.11[—R.sup.11].sub.o— is a single bond, both Z.sup.12 and Z.sup.13 are not simultaneously —O—, n*p denotes an integer from 3 to 10, p denotes 1 or 2, o denotes (3-p), in the case where p=1, n denotes 3, 4, 5, 6 or 8, and m denotes (10-n), and In the case where p=2, n denotes an integer from 2 to 4, and m denotes (4-n), ##STR00210## denotes an organic radical having (m+n) bonding sites, in which, in addition to the m groups R.sup.12 present in the molecule, but independently thereof, a further H atom may be replaced by R.sup.12 or a plurality of further H atoms may be replaced by R.sup.12, in which one —CH.sub.2— group or a plurality of —CH.sub.2— groups may be replaced by —O— or —(C═O)— in such a way that two O atoms are not bonded directly to one another, or a substituted or unsubstituted aromatic or heteroaromatic hydrocarbon radical having up to 10 valences, in which, in addition to the m groups R.sup.12 present in the molecule, but independently thereof, a further H atom may be replaced by R.sup.12 or a plurality of further H atoms may be replaced by R.sup.12, and, in the case where p=1, —X.sup.11[—R.sup.11].sub.o— may alternatively also denote a single bond.

2. LC medium according to claim 1, characterised in that it comprises one or more compounds of the formula I selected from the group of the compounds I1 to I16, ##STR00211## ##STR00212## in which R.sup.1, R.sup.2 and L.sup.1 to L.sup.6 have the meanings indicated in claim 1.

3. LC medium according to claim 1, characterised in that, the compounds of formula H is selected from the following group of the compounds of the formulae H-1 to H-13, ##STR00213## ##STR00214## ##STR00215## ##STR00216## ##STR00217## ##STR00218##

4. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds of the formula II and/or III: ##STR00219## in which R.sup.2 an alkyl radical having 1 to 15 C atoms, wherein one or more CH.sub.2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by —C≡C—, —CH═CH—, ##STR00220##  —O—, —S—, —(CO)—O—, —O—(CO)— in such a way that O or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F or Cl, or H, ##STR00221## on each appearance, independently of one another, denote ##STR00222## L.sup.21 and L.sup.22 denote H or F, L.sup.23 H or CH.sub.3, X.sup.2 denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, m denotes 0, 1, 2 or 3, R.sup.3 an alkyl radical having 1 to 15 C atoms, wherein one or more CH.sub.2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by —C≡C—, —CH═CH—, ##STR00223##  —O—, —S—, —(CO)—O—, —O—(CO)— in such a way that O or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F or Cl, or H, ##STR00224## on each appearance, independently of one another, are ##STR00225## L.sup.31 and L.sup.32, independently of one another, denote H or F, L.sup.33 H or CH.sub.3, X.sup.3 denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, Z.sup.3 denotes —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH.sub.2O— or a single bond, and n denotes 0, 1, 2 or 3.

5. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the group consisting of the following formulae, ##STR00226## in which R.sup.41 and R.sup.42, independently of one another, have the meaning indicated above for R.sup.3 under formula III, ##STR00227## independently of one another and, if ##STR00228##  occurs twice, also these independently of one another, denote ##STR00229## Z.sup.41 and Z.sup.42, independently of one another and, if Z.sup.41 occurs twice, also these independently of one another, denote —CH.sub.2CH.sub.2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH.sub.2O—, —CF.sub.2O—, —C≡C— or a single bond, p denotes 0, 1 or 2, and R.sup.51 and R.sup.52, independently of one another, have one of the meanings given for R.sup.41 and R.sup.42, ##STR00230## if present, each, independently of one another, denote ##STR00231## Z.sup.51 to Z.sup.53 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, i and j each, independently of one another, denote 0 or 1, (i+j) denotes 0, 1 or 2, wherein the respective rings optionally may each be substituted by one or two alkyl groups.

6. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the group consisting of the following formulae, ##STR00232## wherein R.sup.61 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, R.sup.62 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, C.sub.3-5-cycloalkyloxy or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, L.sup.61, L.sup.62 independently H or methyl, l denotes 0 or 1, R.sup.71 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, R.sup.72 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, L.sup.71, L.sup.72 independently H or methyl, ##STR00233## independently denote ##STR00234## R.sup.81 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, R.sup.82 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, L.sup.81, L.sup.82 independently H or methyl, ##STR00235## denotes ##STR00236## Z.sup.8 denotes —(C═O)—O—, —CH.sub.2—O—, —CF.sub.2—O— or —CH.sub.2—CH.sub.2—, denotes 0 or 1, R.sup.91 and R.sup.92 independently of one another have the meaning given for R.sup.72 above, R.sup.91 denotes an alkyl radical having 2 to 5 C atoms, R.sup.92 denotes an alkyl or alkoxy radical having 2 to 5 C atoms, or an alkenyloxy radical having 2 to 4 C atoms. ##STR00237## denotes ##STR00238## p and q independently of each other denote 0 or 1, and (p+q) denotes 0 or 1, in case ##STR00239## denotes ##STR00240## Alternatively, p=q=1.

7. LC medium according to claim 1, characterised in that comprises one or more compounds of formula IVa ##STR00241## in which R.sup.41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, and R.sup.42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms,

8. LC medium according to claim 1, characterised in that the total concentration of the compounds of the formula I in the medium as a whole is 1% to 25%.

9. LC medium according to claim 1, characterised in that the total concentration of the compounds of the formula H in the LC medium is in the range from 10 ppm to 10,000 ppm.

10. An electro-optical device comprising an LC display comprising an LC medium according to claim 1.

11. LC display containing an LC medium according to claim 1.

12. Display according to claim 11, characterised in that it is based on the IPS or FFS effect.

13. Process for the preparation of an LC medium according to claim 1, characterised in that one or more compounds of the formula I are mixed with one or more compounds of the formula H.

Description

EXAMPLES

[0430] Utilized Stabilizers

##STR00207##

Mixture Examples

[0431] For measuring the VHR the corresponding mixture is filled into electrooptic test cells which consist of two AF glass substrates with an approximately 20 nm thick ITO layer and a 100 nm thick polyimide layer.

[0432] The VHR is measured at 60° C. with application of a voltage of 1 V/60 Hz before and after the given time. The difference in VHR before and after stress is expressed according to:

ΔVHR=VHR (after stress)−VHR (initial)

[0433] Thermal stress usually causes the decrease of VHR in LC mixtures, therefore the smaller the absolute decrease of VHR value after stress, the better performance for display applications.

[0434] Host Mixture—H-1

[0435] The following mixture is prepared according to the following table:

TABLE-US-00006 CP-5-3 20.0 cl.p. [° C.]: 74 CC-3-5 10.0 Δn [589 nm, 20° C.]: 0.0730 CCU-2-F 12.0 n.sub.e [589 nm, 20° C.]: 1.5484 CCU-3-F 10.0 n.sub.o [589 nm, 20° C.]: 1.4754 CCU-5-F 8.0 Δε [1 kHz, 20° C.]: 5.4 CCEG-3-F 10.0 ε.sub.|| [1 kHz, 20° C.]: 8.6 CCEG-5-F 10.0 ε.sub.⊥ [1 kHz, 20° C.]: 3.2 CCG-3-OT 10.0 K.sub.1 [pN, 20° C.]: 12.6 CCG-5-OT 10.0 K.sub.3 [pN, 20° C.]: 15.6 Σ 100.0 K.sub.3/K.sub.1 [pN, 20° C.]: 1.23 V.sub.0 [V, 20° C.]: 1.62
and 10% w/w of PUS-3-2 according to the above-given acronym tables are added resulting in Host Mixture H-1

TABLE-US-00007 Mixture Initial After 1000 h H-1 ΔVHR/% 95.1 19.5

[0436] Host Mixture—H-2

[0437] The following mixture is prepared according to the following table:

TABLE-US-00008 CP-5-3 20.0 cl.p. [° C.]: 74 CC-3-5 10.0 Δn [589 nm, 20° C.]: 0.0730 CCU-2-F 12.0 n.sub.e [589 nm, 20° C.]: 1.5484 CCU-3-F 10.0 n.sub.o [589 nm, 20° C.]: 1.4754 CCU-5-F 8.0 Δε [1 kHz, 20° C.]: 5.4 CCEG-3-F 10.0 ε.sub.|| [1 kHz, 20° C.]: 8.6 CCEG-5-F 10.0 ε.sub.⊥ [1 kHz, 20° C.]: 3.2 CCG-3-OT 10.0 K.sub.1 [pN, 20° C.]: 12.6 CCG-5-OT 10.0 K.sub.3 [pN, 20° C.]: 15.6 Σ 100.0 K.sub.3/K.sub.1 [pN, 20° C.]: 1.23 V.sub.0 [V, 20° C.]: 1.62
and 10% w/w of PUS-2-2 according to the above-given acronym tables are added resulting in Host Mixture H-2

[0438] Mixture M-1

[0439] To mixture H-1, 0.03% w/w of the stabilizer S-1 is added resulting in Mixture M-1

TABLE-US-00009 Mixture Initial After 1000 h M-1 ΔVHR/% 73.5 82.4

[0440] Comparative Mixture CM-1

[0441] To mixture H-1, 0.03% w/w of Tinuvin®770 is added resulting in Comparative mixture CM-1 comparative to mixture M-1.

TABLE-US-00010 Mixture Initial After 1000 h CM-1 ΔVHR/% 40.1 66.0

[0442] Mixture M-2

[0443] To mixture H-1, 0.1% w/w of S-1 is added resulting in Mixture M-2

TABLE-US-00011 Mixture Initial After 1000 h M-2 ΔVHR/% 82.9 74.6

[0444] Mixture M-3

[0445] To mixture H-1, 0.1% w/w of S-2 is added resulting in Mixture M-4.

TABLE-US-00012 Mixture Initial After 1000 h M-3 ΔVHR/% 78.9 83.8

[0446] Comparative Mixture CM-2

[0447] To mixture H-1, 0.1% w/w of Tinuvin®770 is added resulting in Comparative Mixture CM-2 comparative to mixture M-2 and M-3.

TABLE-US-00013 Mixture Initial After 1000 h CM-2 ΔVHR/% 67.9 53.2

[0448] Mixture M-4

[0449] To mixture H-1, 10% w/w of mixture M-2 is added resulting in Mixture M-4

[0450] Mixture M-5

[0451] To mixture H-1, 10% w/w of mixture M-3 is added resulting in Mixture M-5

[0452] Comparative Mixture CM-3

[0453] To mixture H-1, 10% w/w of mixture CM-2 is added resulting in Comparative Mixture CM-3 comparative to mixture M-4 and M-5.

[0454] Mixture M-6

[0455] To mixture H-2, 0.1% w/w of S-1 is added resulting in Mixture M-6.

[0456] Mixture M-7

[0457] The following mixture is prepared according to the following table resulting in Mixture M-7

TABLE-US-00014 CC-3-V 47.0 CC-3-V1 4.5 CLP-3-T 7.0 PGP-1-2V 5.5 PGP-2-2V 10.0 PGU-2-F 1.0 PGUQU-3-F 4.0 PGUQU-4-F 2.5 PP-1-2V1 7.5 PPGU-3-F 0.99 PUS-3-2 10.0 S-1 0.01 Σ 100

[0458] Mixture M-8

[0459] The following mixture is prepared according to the following table resulting in Mixture M-8

TABLE-US-00015 CC-3-V 47.0 CC-3-V1 4.5 CLP-3-T 7.0 PGP-1-2V 5.5 PGP-2-2V 10.0 PGU-2-F 1.0 PGUQU-3-F 4.0 PGUQU-4-F 2.5 PP-1-2V1 7.5 PPGU-3-F 0.99 PUS-3-2 10.0 S-2 0.01 Σ 100

[0460] 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.

[0461] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.