LIQUID-CRYSTALLINE MEDIUM AND LIQUID-CRYSTAL DISPLAY

Abstract

Dielectrically positive liquid-crystalline media comprising one or more compounds of each of the formulae S1 and S2,

##STR00001##

and one or more compounds selected from the group of the compounds of the formulae II and III and/or IV and/or VIII,

##STR00002##

in which the parameters have the meanings indicated in the specification, and optionally one or more further dielectrically positive compounds and optionally one or more further dielectrically neutral compounds. Also, liquid-crystal displays, especially active-matrix displays and in particular TN, IPS and FFS displays, containing these media.

Claims

1. A liquid-crystal medium having positive dielectric anisotropy, which comprises: a) one or more compounds of the formulae S1 and one or more compounds of the S2, ##STR00319## in which the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings: ##STR00320## R.sup.a to R.sup.d independently of one another, are straight chain or branched alkyl with 1 to 10 C atoms, X independently of one another, are H, CH.sub.3, OH or O., A is a straight-chain, branched or cyclic alkylene with 1 to 20 C-atoms which is optionally substituted, and n is an integer from 1 to 6; and b) one or more compounds selected from the group of the compounds of the formulae II and III ##STR00321## in which R.sup.2 and R.sup.3 independently of one another, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, ##STR00322## on each appearance, independently of one another, denote ##STR00323## L.sup.21, L.sup.22,L.sup.31 and L.sup.32 independently of one another, denote H or F, X.sup.2 and X.sup.3 independently of one another, denote 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-CHCH, trans-CFCF, CH.sub.2O or a single bond, and m and n independently of one another, denote 0, 1, 2 or 3, and/or c) one or more compounds of the formula IV ##STR00324## in which R.sup.41 and R.sup.42 independently of one another, have the meaning indicated for R.sup.2 above under formula II, ##STR00325## independently of one another, and, if ##STR00326## occurs twice, also these independently of one another, denote ##STR00327## 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-CHCH, trans-CFCF, CH.sub.2O, CF.sub.2O, CC or a single bond, and p denotes 0, 1 or 2, and/or d) one or more compounds of the formula VIII ##STR00328## in which R.sup.81 and R.sup.82 independently of one another, have the meaning indicated for R.sup.2, and ##STR00329## Z.sup.81 and Z.sup.82 independently of one another, denote CH.sub.2CH.sub.2, CC, COO, trans-CHCH, trans-CFCF, CH.sub.2O, CF.sub.2O or a single bond, s denotes 0 or 1 and L.sup.81 and L.sup.82 independently of one another, denote CF or N, and in case ##STR00330## one of L.sup.81 and L.sup.82 or both alternatively may denote CH.

2. The medium according to claim 1, which comprises one or more compounds selected from the group of the compounds of the formulae II and III ##STR00331## in which R.sup.2 and R.sup.3 independently of one another, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, ##STR00332## on each appearance, independently of one another, denote ##STR00333## L.sup.21, L.sup.22, L.sup.31 and L.sup.32 independently of one another, denote H or F, X.sup.2 and X.sup.3 independently of one another, denote 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-CHCH, trans-CFCF, CH.sub.2O or a single bond, and m and n independently of one another, denote 0, 1, 2 or 3.

3. The medium according to claim 1, which comprises one or more compounds of the formula IV ##STR00334## in which R.sup.41 and R.sup.42 independently of one another, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, ##STR00335## independently of one another, and, if ##STR00336## occurs twice, also these independently of one another, denote ##STR00337## 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-CHCH, trans-CFCF, CH.sub.2O, CF.sub.2O, CC or a single bond, and p denotes 0, 1 or 2.

4. The medium according to claim 1, wherein the total concentration of the compounds of the formulae S1 and S2 together in the medium is in the range of from 1 ppm to 5,000 ppm.

5. The medium according to claim 1, wherein the compounds of the formulae S1 and S2 are compounds selected from the group of the compounds of their following sub-formulae S1a and S1 b and S2a and S2b, respectively: ##STR00338## in which n denotes an integer from 1 to 6.

6. The medium according to claim 2, which comprises one or more compounds of the formula II.

7. The medium according to claim 2, which comprises one or more compounds of the formula III.

8. The medium according to claim 1, characterised in that it comprises one or more dielectrically neutral compounds of the formula V, ##STR00339## in which R.sup.51 and R.sup.52, independently of one another, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, ##STR00340## on each occurrence, independently of one another, denotes ##STR00341## Z.sup.51 and Z.sup.52, independently of one another and, if Z.sup.51 occurs twice, also these independently of one another, denote CH.sub.2CH.sub.2, COO, trans-CHCH, trans-CFCF, CH.sub.2O, CF.sub.2O or a single bond, and r denotes 0, 1 or 2.

9. A liquid-crystal display, which comprises a medium according to claim 1.

10. The display according to claim 9, which is addressed by an active matrix.

11. A process for the preparation of a medium according to claim 1, comprising: mixing one or more compounds of each of the formulae S1 and S2 with one or more of the compounds of the formulae II, III, IV or VIII and, optionally, with one or more further mesogenic compounds and optionally with one or more additives.

12. The medium according to claim 1, which comprises a compound of the formula S-1 wherein R.sup.a to R.sup.d independently of one another, are straight chain or branched alkyl with 1 to 6 C atoms.

13. The medium according to claim 1, which comprises a compound of the formula S-1 wherein R.sup.a to R.sup.d independently of one another, are straight chain or branched alkyl with 1 to 4 C atoms.

14. The medium according to claim 1, which comprises a compound of the formula S-1 wherein R.sup.a to R.sup.d are each methyl.

15. The medium according to claim 1, which comprises a compound of the formula S-1 wherein each X is H.

16. The medium according to claim 1, which comprises a compound of the formula S-1 wherein A is (CH.sub.2).sub.8.

17. The medium according to claim 1, which comprises one or more compounds of the formulae II and/or III and one or more compounds of the formula IV.

18. The medium according to claim 8, which comprises one or more compounds of the formulae II and/or III.

19. The medium according to claim 8, which comprises one or more compounds of the formula IV.

20. The medium according to claim 8, which comprises one or more compounds of the formulae II and/or III and one or more compounds of the formula IV.

Description

EXAMPLES

[0208] The examples below illustrate the present invention without limiting it in any way.

[0209] However, the physical properties exemplify to the person skilled in the art what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

[0210] Liquid-crystal mixtures having the composition and properties as indicated in the following tables are prepared and investigated.

Example 1

[0211] An LC mixture (M-1.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00007 Composition Compound c [%] Properties CC-3-V 37.0 T(N, I) [ C.]: 94.5 CC-3-V1 9.5 n.sub.e (589 nm, 20 C.): 1.5894 CCP-V-1 11.5 n.sub.o (589 nm, 20 C.): 1.4845 CCP-V2-1 3.0 n (589 nm, 20 C.): 0.1049 PGP-2-2V 10.5 .sub.|| (1 kHz, 20 C.): 7.8 APUQU-3-F 5.0 .sub. (1 kHz, 20 C.): 2.9 APUQU-2-F 5.0 (1 kHz, 20 C.): 4.9 PGUQU-4-F 3.5 .sub.1 (20 C.) [mPa .Math. s] 67 PGUQU-3-F 2.0 K.sub.1 (20 C.) [pN]: 15.6 CCP-3-OT3 9.0 K.sub.3 (20 C.) [pN]: 17.1 CCP-5-OT 2.0 V.sub.0 (20 C.) [V]: 1.87 CCQU-3-F 2.0 100.0

[0212] The above mixture (M1-0) is separated in to four parts. The first part is investigated as such. To one each of the further three parts either 300 ppm, 500 ppm or 1,000 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added (mixtures M1-1 to M1-3).

##STR00318##

[0213] Use Examples

[0214] The LC media M1-1 to M1-3 formulated as in Example 1 are filled into VHR test cells as described above.

[0215] The test cells are subjected to thermal stress (100 C.). The VHR is measured as described above after various time intervals (t.sub.heat). For comparison purpose the measurement is repeated with the reference LC medium M1-0, which is formulated as in Example 1. The VHR values are shown in Table 1 below.

TABLE-US-00008 TABLE 1 VHR after Heat Load Example C1 E1.1 E1.2 E1.3 LC M1-0 M1-1 M1-2 M1-3 c(S1a) /ppm 0 300 500 1,000 c(S2a1) /ppm 0 500 t.sub.heat/h VHR/% 0 98.8 98.0 97.9 97.7 24 98.7 98.8 98.7 98.6 48 98.5 98.9 98.8 98.7 120 98.6 98.9 98.9 98.5

[0216] Another set of filled test cells is subjected to an exposure by a back light unit of an LCD. The VHR is measured as described above after various time intervals (t.sub.light). The VHR values are shown in Table 2 below.

TABLE-US-00009 TABLE 2 VHR after Back Light Load Example C1 E1.1 E1.2 E1.3 LC M1-0 M1-1 M1-2 M1-3 c(S1a) /ppm 0 300 500 1,000 c(S2a1) /ppm 0 500 t.sub.light/h VHR/% 0 99.2 98.0 97.7 97.5 24 98.5 99.0 98.9 98.8 168 95.6 98.4 98.2 98.4 336 94.5 98.7 97.9 98.2 504 91.3 97.4 97.1 97.4

[0217] It can be seen that the LC media M1-1 to M-1-3, which contain both stabilizers S1a and S2a1, show significantly lower decrease of the VHR after long heat exposure and/or back light load compared to LC medium M-1, which does not contain any compounds of formulae S1 and S2.

[0218] The absence of the formulae S1 and S2 additives results in a significant drop in the HR of the mixture after heating, as well as after the back light test.

Example 2

[0219] An LC mixture (M-2.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00010 Composition Compound c [%] Properties CC-3-V 36.0 T(N, I) [ C.]: 78 CC-3-V1 5.0 n.sub.e (589 nm, 20 C.): 1.5907 CCP-V-1 8.0 n.sub.o (589 nm, 20 C.): 1.4812 PGP-2-2V 3.0 n (589 nm, 20 C.): 0.1095 CCQU-3-F 9.5 .sub.|| (1 kHz, 20 C.): 16.6 PUQU-3-F 8.5 .sub. (1 kHz, 20 C.): 3.7 APUQU-2-F 5.0 (1 kHz, 20 C.): 12.9 APUQU-3-F 8.0 .sub.1 (20 C.) [mPa .Math. s] 78 PGUQU-3-F 4.0 K.sub.1 (20 C.) [pN]: 12.1 PGUQU-4-F 8.0 K.sub.3 (20 C.) [pN]: 13.4 PGUQU-5-F 5.0 V.sub.0 (20 C.) [V]: 1.01 100.0

[0220] To the above mixture are added 1,000 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1. The resultant mixture with the stabilizers shows excellent stability against both heat load and back light load.

Example 3

[0221] An LC mixture (M-3.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00011 Composition Compound c [%] Properties CC-3-V 32.0 T(N, I) [ C.]: 85 CC-3-V1 11.0 n.sub.e (589 nm, 20 C.): 1.5865 CC-3-2V1 4.5 n.sub.o (589 nm, 20 C.): 1.4776 PP-1-2V1 2.0 n (589 nm, 20 C.): 0.1089 CCP-3-OT 7.5 .sub.|| (1 kHz, 20 C.): 19.0 CCP-5-OT 1.5 .sub. (1 kHz, 20 C.): 3.7 PUQU-3-F 1.5 (1 kHz, 20 C.): 15.3 APUQU-2-F 7.0 .sub.1 (20 C.) [mPa .Math. s] 89 APUQU-3-F 7.0 K.sub.1 (20 C.) [pN]: 14.4 PGUQU-3-F 3.0 K.sub.3 (20 C.) [pN]: 15.1 PGUQU-4-F 8.0 V.sub.0 (20 C.) [V]: 1.01 PGUQU-5-F 2.0 DPGU-4-F 5.0 DGUQU-4-F 8.0 100.0

[0222] To the above mixture are added 500 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1. The resultant mixture with the stabilizers shows excellent stability against both heat load and back light load.

Example 4

[0223] An LC mixture (M-4.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00012 Composition Compound c [%] Properties CC-3-V 27.5 T(N, I) [ C.]: 110.5 CCP-V-1 10.0 n.sub.e (589 nm, 20 C.): 1.5874 CCP-3-OT 5.0 n.sub.o (589 nm, 20 C.): 1.4793 CCU-3-F 5.5 n (589 nm, 20 C.): 0.1081 CCQU-3-F 12.0 .sub.|| (1 kHz, 20 C.): 17.5 CCGU-3-F 5.0 .sub. (1 kHz, 20 C.): 3.7 CPGU-3-OT 5.0 (1 kHz, 20 C.): 13.9 APUQU-2-F 8.0 .sub.1 (20 C.) [mPa .Math. s] APUQU-3-F 8.0 K.sub.1 (20 C.) [pN]: 14.3 PGUQU-3-F 3.0 K.sub.3 (20 C.) [pN]: 17.8 PGUQU-4-F 3.0 V.sub.0 (20 C.) [V]: 1.06 CDUQU-3-F 6.0 CPGP-4-3 2.0 100.0

[0224] To each one of respective part of the above mixture are added 500 ppm of stabilizer S2a1 and either 100 ppm, 500 ppm, 1,000 ppm or 1,500 ppm of stabilizer S1a are added. The resultant mixtures with the stabilizers show excellent stability against both heat load and back light load.

Example 5

[0225] An LC mixture (M-5.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00013 Composition Compound c [%] Properties CC-3-V 29.5 T(N, I) [ C.]: 110 CCP-V2-1 10.0 n.sub.e (589 nm, 20 C.): 1.5842 PGP-1-2V 5.0 n.sub.o (589 nm, 20 C.): 1.4800 PGP-2-2V 5.0 n (589 nm, 20 C.): 0.1042 CCP-3-OT 8.0 .sub.|| (1 kHz, 20 C.): 8.2 CCU-2-F 5.5 .sub. (1 kHz, 20 C.): 2.9 CCQU-2-F 6.0 (1 kHz, 20 C.): 5.3 CCQU-3-F 12.0 .sub.1 (20 C.) [mPa .Math. s] 102 CCQU-5-F 8.0 K.sub.1 (20 C.) [pN]: 16.2 CCGU-3-F 4.5 K.sub.3 (20 C.) [pN]: 19.1 CPGU-3-OT 3.5 V.sub.0 (20 C.) [V]: 1.84 CPGP-5-2 3.0 100.0

[0226] To the above mixture are added 300 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1. The resultant mixture with the stabilizers shows excellent stability against both heat load and back light load.

Example 6

[0227] An LC mixture (M-6.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00014 Composition Compound c [%] Properties CC-3-V 33.5 T(N, I) [ C.]: 109 CC-3-V1 10.5 n.sub.e (589 nm, 20 C.): 1.5821 CCP-V-1 13.0 n.sub.o (589 nm, 20 C.): 1.4835 CCP-V2-1 8.0 n (589 nm, 20 C.): 0.0986 PGP-2-2V 6.5 .sub.|| (1 kHz, 20 C.): 6.0 CCQU-3-F 11.0 .sub. (1 kHz, 20 C.): 2.6 CCQU-5-F 4.5 (1 kHz, 20 C.): 3.3 CCGU-3-F 5.0 .sub.1 (20 C.) [mPa .Math. s] 83 CPGU-3-OT 6.0 K.sub.1 (20 C.) [pN]: 17.1 CPGP-5-2 2.0 K.sub.3 (20 C.) [pN]: 19.8 100.0 V.sub.0 (20 C.) [V]: 2.38

[0228] To the above mixture are added 300 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1. The resultant mixture with the stabilizers shows excellent stability against both heat load and back light load.

Example 7

[0229] An LC mixture (M-7.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00015 Composition Compound c [%] Properties CC-3-V 44.5 T(N, I) [ C.]: 80.5 CC-3-V1 5.5 n.sub.e (589 nm, 20 C.): 1.5880 CCP-V-1 8.0 n.sub.o (589 nm, 20 C.): 1.4828 PGP-2-3 4.0 n (589 nm, 20 C.): 0.1052 PGP-2-4 5.0 .sub.|| (1 kHz, 20 C.): 9.1 PUQU-3-F 2.5 .sub. (1 kHz, 20 C.): 3.0 CCP-3-OT 8.0 (1 kHz, 20 C.): 6.1 CCQU-3-F 5.0 .sub.1 (20 C.) [mPa .Math. s] 59 PGUQU-3-F 3.0 K.sub.1 (20 C.) [pN]: 13.2 PGUQU-4-F 9.0 K.sub.3 (20 C.) [pN]: 14.7 PGUQU-5-F 5.5 V.sub.0 (20 C.) [V]: 1.54 100.0

[0230] To respective parts of the above mixture each are added 300 ppm of stabilizer S1a and respectively 200 ppm, 500 ppm or 800 ppm of stabilizer S2a1. The resultant mixtures with the stabilizers show excellent stability against both heat load and back light load.

Example 8

[0231] An LC mixture (M-8.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00016 Composition Compound c [%] Properties CC-3-V 42.0 T(N, I)/ C.: 79.5 CC-3-V1 5.5 n.sub.e (589 nm, 20 C.): 1.5864 CCP-V-1 4.0 n.sub.o (589 nm, 20 C.): 1.4810 CCP-3-OT 7.0 n (589 nm, 20 C.): 0.1054 PGP-2-2V 6.5 .sub.|| (1 kHz, 20 C.): 8.4 APUQU-2-F 3.0 .sub. (1 kHz, 20 C.): 3.9 APUQU-3-F 8.0 (1 kHz, 20 C.): 4.5 PGUQU-3-F 4.0 .sub.1 (20 C.) [mPa .Math. s] 62 CPGU-3-OT 5.0 K.sub.1 (20 C.) [pN]: 13.1 CPY-3-O2 3.0 K.sub.3 (20 C.) [pN]: 14.4 CY-3-O2 9.0 V.sub.0 (20 C.) [V]: 1.78 PYP-2-3 3.0 100.0

[0232] To respective parts of the above mixture each are added 600 ppm of stabilizer S2a1 and respectively 300 ppm or 500 ppm of stabilizer S1a. The resultant mixtures with the stabilizers show excellent stability against both heat load and back light load.

Example 9

[0233] An LC mixture (M-9.0) with positive dielectric anisotropy is formulated as follows.

TABLE-US-00017 Composition Compound c [%] Properties CC-3-V 46.0 T(N, I)/ C.: 78.5 CC-3-V1 4.0 n.sub.e (589 nm, 20 C.): 1.5891 PGP-2-2V 8.5 n.sub.o (589 nm, 20 C.): 1.4835 PUQU-3-F 2.5 n (589 nm, 20 C.): 0.1056 APUQU-3-F 6.0 .sub.|| (1 kHz, 20 C.): 8.4 PGUQU-3-F 4.0 .sub. (1 kHz, 20 C.): 3.6 PGUQU-4-F 8.0 (1 kHz, 20 C.): 4.8 CCY-2-1 9.0 .sub.1 (20 C.) [mPa .Math. s] 12.9 CPY-3-1 10.0 K.sub.1 (20 C.) [pN]: 14.5 PYP-2-3 2.0 K.sub.3 (20 C.) [pN]: 63 100.0 V.sub.0 (20 C.) [V]: 1.71

[0234] To the above mixture are added 500 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1. The resultant mixture with the stabilizers shows excellent stability against both heat load and back light load.

[0235] 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 !imitative of the remainder of the disclosure in any way whatsoever.

[0236] The entire disclosure[s] of all applications, patents and publications, cited herein and of corresponding EP application No. 18191059.7, filed Aug. 28, 2018, are incorporated by reference herein.

[0237] 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.

[0238] 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.