Liquid crystalline medium
The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (Δ∈), which is distinguished by the fact that it has a value for the ratio γ 1 /Δn 2 in the range 6-45 with a clearing point of >60° C. and a Δ∈ of ≦−2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.
1. A liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (Δ∈), which has a value for the ratio γ 1 /Δn 2 in the range 6-45 Pa·s with a clearing point of >60° C. and a Δ∈ of ≦−2.3, and comprises
at least one compound of formula B-4
and
at least one compound of formula IB
and
at least one compound of formula II
and
optionally at least one compound of formula IA
in which
alkyl each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms;
R 1 and R 2 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 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are each, independently of one another, optionally replaced by —O—, —S—,
—C≡C—, —CF 2 O—, —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that O atoms are not linked directly to one another, and
v denotes 1 to 6,
and
at least one of the following compounds from groups A, B, or C:
A)
one or more compounds of the following formulae T-1 to T-22
in which
R denotes H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,
—C≡C—, —OCF 2 —, —CF 2 O—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another;
B)
one or more compounds of the following formulae To-1 and To-2
in which
R denotes H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,
—C≡C—, —OCF 2 —, —CF 2 O—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and
alkyl denotes a straight-chain alkyl radical having 1-6 C atoms;
C)
the following compound
wherein alkyl* denotes a straight-chain alkyl radical having 1-6 C atoms.
2. A liquid-crystalline medium according to claim 1 , which contains at least one compound of formula IA.
3. A liquid-crystalline medium according to claim 1 , which contains at least 10% of one or more compounds of formula IB and of formula II.
4. A liquid-crystalline medium according to claim 1 , which has a clearing point of 60-90° C.
5. A liquid-crystalline medium according to claim 1 , which has a Δ∈ value of −2.3 to −5.5.
6. A liquid-crystalline medium according to claim 1 , which having a clearing point of 70° C.±5° C. and a Δ∈ of −3.0±0.6 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦125 mPa · s
0.09 ± 0.005
≦130 mPa · s
0.10 ± 0.005
≦135 mPa · s
0.11 ± 0.005
≦145 mPa · s
0.12 ± 0.005
≦150 mPa · s
0.13 ± 0.005
≦160 mPa · s
0.15 ± 0.01
≦170 mPa · s.
7. A liquid-crystalline medium according to claim 1 , which having a clearing point of 70° C.±5° C. and a Δ∈ of >−3.6 and ≦−4.4 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦140 mPa · s
0.09 ± 0.005
≦165 mPa · s
0.10 ± 0.005
≦185 mPa · s
0.11 ± 0.005
≦190 mPa · s
0.12 ± 0.005
≦195 mPa · s
0.13 ± 0.005
≦205 mPa · s
0.15 ± 0.01
≦220 mPa · s.
8. A liquid-crystalline medium according to claim 1 , which having a clearing point of 70° C.±5° C. and a Δ∈ of >−4.4 and ≦−5.6 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦185 mPa · s
0.09 ± 0.005
≦200 mPa · s
0.10 ± 0.005
≦210 mPa · s
0.11 ± 0.005
≦220 mPa · s
0.12 ± 0.005
≦230 mPa · s
0.13 ± 0.005
≦250 mPa · s
0.15 ± 0.01
≦270 mPa · s.
9. A liquid-crystalline medium according to claim 1 , which having a clearing point of 90° C.±5° C. and a Δ∈ of −3.0±0.6 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦160 mPa · s
0.09 ± 0.005
≦170 mPa · s
0.10 ± 0.005
≦180 mPa · s
0.11 ± 0.005
≦190 mPa · s
0.12 ± 0.005
≦200 mPa · s
0.13 ± 0.005
≦210 mPa · s
0.15 ± 0.01
≦220 mPa · s.
10. A liquid-crystalline medium according to claim 1 , which having a clearing point of 90° C.±5° C. and a Δ∈ of >−3.6 and ≦−4.4 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦185 mPa · s
0.09 ± 0.005
≦195 mPa · s
0.10 ± 0.005
≦215 mPa · s
0.11 ± 0.005
≦215 mPa · s
0.12 ± 0.005
≦215 mPa · s
0.13 ± 0.005
≦235 mPa · s
0.15 ± 0.01
≦250 mPa · s.
11. A liquid-crystalline medium according to claim 1 , which having a clearing point of 90° C.±5° C. and a Δ∈ of >−4.4 and ≦−5.6 has the following rotational viscosities γ 1 at a defined Δn value:
Δn
γ 1
0.08 ± 0.005
≦280 mPa · s
0.09 ± 0.005
≦275 mPa · s
0.10 ± 0.005
≦275 mPa · s
0.11 ± 0.005
≦275 mPa · s
0.12 ± 0.005
≦280 mPa · s.
12. A liquid-crystalline medium according to claim 1 , which has thresholds (capacitive) in the range 1.8-2.3 V.
13. A liquid-crystalline medium according to claim 1 , which additionally comprises one or more compounds of the formula III
in which
R 31 and R 32 each, independently of one another, denote a straight-chain alkenyl, alkyl, alkylalkoxy or alkoxy radical having up to 12 C atoms, and
denotes
and
Z denotes a single bond, —C 2 H 4 —, —CH═CH—, —(CH 2 ) 4 —, —(CH 2 ) 3 O—, —O(CH 2 ) 3 —, —CH═CHCH 2 CH 2 —, —CH 2 CH 2 CH═CH—, —CH 2 O—, —OCH 2 —, —CF 2 O—, —OCF 2 —, —COO—, —OCO—, —C 2 F 4 —, —CHFCF 2 —, —CF═CF—, —CH═CF—, —CF═CH—, or —CH 2 —.
14. A liquid-crystalline medium according to claim 1 , which further comprises in total four compounds of formulae
15. A liquid-crystalline medium according to claim 1 , which further comprises at least one compound of formula IIIa and/or IIIb and at least one compound of formula IIIe
in which
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and
alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms.
16. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of formulae IIIa to IIIj:
in which
denotes
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and
alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms.
17. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of the following formulae
18. A liquid-crystalline medium according to claim 1 , which further comprises at least three compounds of the following formulae
wherein alkyl denotes C n H 2n+1 , where n=3, 4 or 5.
19. A liquid-crystalline medium according to claim 1 , wherein when R 1 denotes alkenyl, said group is CH 2 ═CH, CH 3 —CH═CH, C 3 H 7 —CH═CH, CH 2 ═CH—C 2 H 4 or CH 3 —CH═CH—C 2 H 4 .
20. A liquid-crystalline medium according to claim 1 , which comprises
10-40% by weight of one or more compounds of the formulae IA and IB, and
10-40% by weight of one or more compounds of the formula II.
21. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of the following formulae, which compounds when present are each in an amount of at least 5% by weight
in which
R 13 -R 27 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 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,
—C≡C—, —OCF 2 —, —CF 2 O—, —OC—O— in such a way that O atoms are not linked directly to one another,
z and m each, independently of one another, denote 1-6,
R E denotes H, CH 3 , C 2 H 5 or n-C 3 H 7 , and
x denotes 0, 1, 2 or 3.
22. A liquid-crystalline medium according to claim 1 , which comprises one or more compounds of the following formulae T-1 to T-22
in which
R denotes H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,
—C≡C—, —OCF 2 —, —CF 2 O—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another.
23. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of the following formulae B-1 to B-2
in which
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and
alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms.
24. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of the following formulae
25. A liquid-crystalline medium according to claim 1 , which comprises one or more compounds of the following formulae To-1 and To-2
in which
R denotes H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,
—C≡C—, —OCF 2 —, —CF 2 O—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and
alkyl denotes a straight-chain alkyl radical having 1-6 C atoms.
26. A liquid-crystalline medium according to claim 1 , which comprises one or more compounds of the following formula
alkyl* denotes a straight-chain alkyl radical having 1-6 C atoms.
27. A liquid-crystalline medium according to claim 1 , which comprises at least one compound of the formulae
28. A liquid-crystalline medium according to claim 1 , which further comprises one or more compounds of the following formulae
wherein n=1-12.
29. A liquid-crystalline medium according to claim 1 , which comprises the following compound
wherein alkyl* denotes a straight-chain alkyl radical having 1-6 C atoms.
30. An electro-optical display having active-matrix addressing based on the ECB, PA LCD, FFS or the IPS effect, which contains, as dielectric, a liquid-crystalline medium according to claim 1 .
31. A liquid-crystalline medium according to claim 1 , which contains at least one compound of formula IA
in which
R 1 denotes straight-chain alkyl or straight-chain alkenyl having up to 15 C atoms,
and
v denotes 2-5.