Liquid-crystalline medium for use in a switching element

Abstract

The present invention relates to liquid-crystalline media comprising one or more mesogenic compounds of formula I as set forth hereinafter, wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight. The present invention further relates to a switching layer, a switching element and a window element containing the liquid-crystalline medium.

Claims

1. A window element, comprising a switching element, which switching element comprises a switching layer, which switching layer comprises a liquid-crystalline medium, wherein the switching layer is arranged between two substrates, and wherein the switching element is electrically switchable and operable in an optically transparent state and a scattering state, wherein the liquid-crystalline medium comprises one or more mesogenic compounds of formula I ##STR00430## wherein R.sup.1 and R.sup.2 denote, independently of one another, F, Cl, CF.sub.3, OCF.sub.3, a straight-chain alkyl or alkoxy having 1 to 15 carbon atoms, a branched alkyl or alkoxy having 3 to 15 carbon atoms, a straight-chain alkenyl having 2 to 15 carbon atoms, or a branched alkenyl having 3 to 15 carbon atoms, which is unsubstituted, monosubstituted by CN or CF.sub.3 or mono- or polysubstituted by halogen and wherein one or more CH.sub.2 groups may be, in each case independently of one another, replaced by —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another, ##STR00431## denotes ##STR00432## n denotes 0 or 1, and ##STR00433## denote, independently of one another, ##STR00434## wherein L is on each occurrence, identically or differently, halogen selected from the group consisting of F, Cl and Br, and one or more chiral compounds, wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight, and wherein the medium exhibits a clearing point of 98° C. or more.

2. The window element according to claim 1, wherein the medium exhibits a pitch of 0.55 μm or more.

3. The window element according to claim 1, in which the medium exhibits an optical anisotropy Δn, determined at 20° C. and 589 nm, of 0.13 or more.

4. The window element according to claim 1, in which the medium further comprises one or more mesogenic compounds of formulae II and/or III ##STR00435## wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.6 denote, independently of one another, F, CF.sub.3, OCF.sub.3, CN, a straight-chain alkyl or alkoxy having 1 to 15 carbon atoms, a branched alkyl or alkoxy having 3 to 15 carbon atoms, a straight-chain alkenyl having 2 to 15 carbon atoms or a branched alkenyl having 3 to 15 carbon atoms, which is unsubstituted, monosubstituted by CN or CF.sub.3 or mono- or polysubstituted by halogen and wherein one or more CH.sub.2 groups may be, in each case independently of one another, replaced by —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another, and L.sup.1, L.sup.2, L.sup.3, L.sup.4 and L.sup.5 denote, independently of one another, H or F.

5. The window element according to claim 1, wherein in the one or more mesogenic compounds of formula I L is F and R.sup.1 and R.sup.2 are not Cl.

6. The window element according to claim 1, wherein the one or more chiral compounds in the medium have an absolute value of the helical twisting power of 5 μm.sup.−1 or more.

7. The window element according to claim 1, wherein the medium further comprises one or more polymerisable compounds.

8. The window element according to claim 7, wherein the one or more polymerisable compounds are contained in the medium in an amount, based on the overall contents of the medium, of 10% by weight or less.

9. The window element according to claim 7, wherein one or more of the one or more polymerisable compounds comprise one, two or more acrylate and/or methacrylate groups.

10. The window element according to claim 7, wherein one or more of the one or more polymerisable compounds are polymerisable mesogenic compounds.

11. The window element according to claim 1, wherein the medium further comprises a polymeric component.

12. The window element according to claim 11, wherein the polymeric component is contained in the medium in an amount, based on the overall contents of the medium, of 10% by weight or less.

13. A method for preparing the window element of claim 1, therein a switching layer or a switching element, comprising (a) providing the medium comprising the one or more mesogenic compounds of formula I and the one or more chiral compounds and which medium further comprises one more polymerisable compounds as a layer, and (b) polymerising the one or more polymerisable compounds of said medium.

14. The window element according to claim 11, wherein the polymeric component is obtained by polymerising one or more polymerisable compounds.

15. A cholesteric liquid crystal scattering device, comprising the window element according to claim 1.

16. An automobile, comprising the window element according to claim 1.

17. An architectural building, comprising the window element according to claim 1.

18. A privacy window, comprising the window element according to claim 1.

Description

EXAMPLES

(1) Liquid crystal mixtures and composite systems are realized with the compositions and properties as given in the following. Their properties and optical performance are investigated.

Comparative Example 1

(2) A comparative liquid-crystal base mixture CB-1 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(3) TABLE-US-00009 PP-5-N 51.00% Clearing point: 58.0° C. PP-7-N 25.00% Δn [589 nm, 20° C.]: 0.226 PP-8O-N 16.00% Δε [1 kHz, 20° C.]: 14.3 PPP-5-N 8.00% Σ 100.00%

(4) A comparative cholesteric mixture CC-1 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the comparative base mixture CB-1 such that a pitch of 0.9 μm is obtained, wherein CC-1 contains 99.08% of the mixture CB-1 and 0.92% of R-5011.

Comparative Example 2

(5) A comparative liquid-crystal base mixture CB-2 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(6) TABLE-US-00010 PP-2-N 8.75% Clearing point: 97.0° C. PP-5O-N 18.76% Δn [589 nm, 20° C.]: 0.267 PP-6-ON 8.75% Δε [1 kHz, 20° C.]: 17.0 CPP-5-N 10.01% PPP-5-N 4.97% PGIP-3-N 18.76% PP-5-N 30.00% Σ 100.00%

(7) A comparative cholesteric mixture CC-2 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the comparative base mixture CB-2 such that a pitch of 2 μm is obtained, wherein CC-2 contains 99.57% of the mixture CB-2 and 0.43% of R-5011.

Comparative Example 3

(8) A comparative liquid-crystal base mixture CB-3 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(9) TABLE-US-00011 PZG-2-N 9.00% Clearing point: 92.0° C. PZG-3-N 10.00% Δn [589 nm, 20° C.]: 0.257 PZG-4-N 14.00% Δε [1 kHz, 20° C.]: 41.8 PZG-5-N 14.00% CP-3-N 2.00% PPTUI-3-2 20.00% PPTUI-3-4 28.00% CGPC-3-3 3.00% Σ 100.00%

(10) A comparative cholesteric mixture CC-3 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the comparative base mixture CB-3 such that a pitch of 2 μm is obtained, wherein CC-3 contains 99.46% of the mixture CB-3 and 0.54% of R-5011.

Comparative Example 4

(11) A comparative liquid-crystal base mixture CB-4 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(12) TABLE-US-00012 CP-3-N 16.00% Clearing point: 114.5° C. CP-5-N 16.00% Δn [589 nm, 20° C.]: 0.135 CPG-3-F 5.00% Δε [1 kHz, 20° C.]: 11.3 CPG-5-F 5.00% CPU-3-F 15.00% CPU-5-F 15.00% CCGU-3-F 7.00% CGPC-3-3 4.00% CGPC-5-3 4.00% CGPC-5-5 4.00% CCZPC-3-3 3.00% CCZPC-3-4 3.00% CCZPC-3-5 3.00% Σ 100.00%

(13) A comparative cholesteric mixture CC-4 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the comparative base mixture CB-4 such that a pitch of 2 μm is obtained, wherein CC-4 contains 99.62% of the mixture CB-4 and 0.38% of R-5011.

(14) For the respective comparative cholesteric mixtures the VHR is respectively determined. Moreover, for the comparative cholesteric mixtures the pitch is confirmed by measuring the wavelength of the selective reflection maximum λ.sub.max at 20° C. using the NIR spectroscopic method described above.

(15) The mixtures are placed in electro-optical cells which are provided with orientation layers (antiparallel rubbed polyimide AL-1054 from Japan Synthetic Rubber), wherein the LC mixtures have a layer thickness of 23.2 μm with). The haze of the respective cells in the scattering state is determined according to ASTM 1003-92 using a spectrophotometer (Lambda 1050, Perkin Elmer) and a 150 mm Ulbricht's sphere.

(16) The following Table shows the obtained results.

(17) TABLE-US-00013 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 VHR 20% 20% 30% 85% pitch 0.9 μm 2 μm 2 μm 2 μm voltage for 4 V 10 V 9 V 13 V hazy state haze 68% 84% 89% 74%

Example 1

(18) A liquid-crystal base mixture B-1 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(19) TABLE-US-00014 GGP-5-CI 17.00% Clearing point: 101.0° C. PGIGI-3-F 7.00% Δn [589 nm, 20° C.]: 0.181 CPG-2-F 8.00% n.sub.e [589 nm, 20° C.]: 1.693 CPG-3-F 8.00% Δε [1 kHz, 20° C.]: 13.2 CPG-5-F 5.00% ε.sub.∥ [1 kHz, 20° C.]: 18.0 CGU-2-F 7.00% CGU-3-F 7.00% CGU-5-F 4.00% PGU-2-F 8.00% PGU-3-F 8.00% CPGU-3-F 10.00% CPP-3-2 5.00% CGPC-3-3 3.00% CGPC-5-3 3.00% Σ 100.00%

(20) A cholesteric mixture C-1 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-1 such that a pitch of 2 μm is obtained, wherein C-1 contains 99.65% of the mixture B-1 and 0.35% of R-5011.

(21) The VHR, pitch and haze are determined as described for the Comparative Examples above, and the following values are obtained: VHR: 90%, pitch: 2 μm, voltage for the hazy state: 7 V, haze: 62%.

(22) The mixture exhibits a long shelf life at low temperatures. The shelf life is determined by storing the respective sample at the respective temperature and determining the time period during which no visible crystallisation or decomposition occurs. The following Table shows the determined shelf life

(23) TABLE-US-00015 shelf life (bulk, −20° C.) 70 days shelf life (bulk, −30° C.) 49 days shelf life (bulk, −40° C.) 19 days shelf life (6 μm TN cell, −30° C.) >117 days shelf life (6 μm TN cell, −40° C.) >19 days

(24) The mixture shows favourable electro-optical performance and stability.

Example 2

(25) A liquid-crystal base mixture B-2 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(26) TABLE-US-00016 PP-1-2V1 8.00% Clearing point: 98.0° C. CP-3-O1 7.00% Δn [589 nm, 20° C.]: 0.231 CP-3-CI 3.00% n.sub.e [589 nm, 20° C.]: 1.755 PGP-2-2V 9.00% Δε [1 kHz, 20° C.]: 7.0 PGP-3-2V 6.00% ε.sub.∥ [1 kHz, 20° C.]: 11.0 PGU-3-F 4.00% GGP-3-CI 9.00% GGP-5-CI 20.00% GPEP-2-CI 8.00% GPEP-5-CI 12.00% PGIGI-3-F 5.00% CPGP-4-3 3.00% CPGP-5-2 3.00% DPGU-4-F 3.00% Σ 100.00%

(27) A cholesteric mixture C-2 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-2 such that a pitch of 2 μm is obtained, wherein C-2 contains 99.54% of the mixture B-2 and 0.46% of R-5011.

(28) The pitch and haze are determined as described for the Comparative Examples above, and the following values are obtained:

(29) Pitch: 2 μm, voltage for the hazy state: 21 V, haze: 73%.

(30) The mixture exhibits a long shelf life at −20° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(31) TABLE-US-00017 shelf life (bulk, −20° C.) >203 days shelf life (bulk, −30° C.) 8 days shelf life (bulk, −40° C.) 8 days shelf life (6 μm TN cell, −30° C.) >202 days shelf life (6 μm TN cell, −40° C.) 70 days

(32) The mixture shows favourable electro-optical performance and stability.

Example 3

(33) A liquid-crystal base mixture B-3 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(34) TABLE-US-00018 PGIGI-3-F 12.00% Clearing point: 104.0° C. CPG-2-F 8.00% Δn [589 nm, 20° C.]: 0.161 CPG-3-F 8.00% Δε [1 kHz, 20° C.]: 10.9 CPG-5-F 5.00% ε.sub.∥ [1 kHz, 20° C.]: 15.2 CPU-5-F 10.00% CPU-7-F 10.00% PGU-3-F 4.00% PGU-5-F 9.00% CCGU-3-F 8.00% CPP-3-2 4.00% CGPC-3-3 3.00% CGPC-5-3 3.00% CGPC-5-5 3.00% CPGU-3-OT 3.00% CP-5-N 10.00% Σ 100.00%

(35) A cholesteric mixture C-3 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-3 such that a pitch of 2 μm is obtained.

(36) The mixture exhibits a long shelf life at −20° C. and −30° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(37) TABLE-US-00019 shelf life (bulk, −20° C.) >94 days shelf life (bulk, −30° C.) >94 days shelf life (bulk, −40° C.)  0 days shelf life (6 μm TN cell, −30° C.) >94 days shelf life (6 μm TN cell, −40° C.) >94 days

(38) The mixture shows favourable electro-optical performance and stability.

Example 4

(39) A liquid-crystal base mixture B-4 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(40) TABLE-US-00020 PGIGI-3-F 10.00% Clearing point: 105.0° C. CPG-2-F 6.00% Δn [589 nm, 20° C.]: 0.160 CPG-3-F 7.00% n.sub.e [589 nm, 20° C.]: 1.663 CPG-5-F 5.00% Δε [1 kHz, 20° C.]: 10.0 CPU-5-F 10.00% CPU-7-F 10.00% PGU-3-F 4.00% PGU-5-F 7.00% CCGU-3-F 8.00% CPP-3-2 4.00% CGPC-3-3 3.00% CGPC-5-3 3.00% CGPC-5-5 3.00% CPGU-3-OT 5.00% CP-5-N 15.00% Σ 100.00%

(41) A cholesteric mixture C-4 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-4 such that a pitch of 2 μm is obtained, wherein C-4 contains 99.65% of the mixture B-4 and 0.35% of R-5011.

(42) The mixture exhibits a long shelf life at low temperatures. The following Table shows the determined shelf life values.

(43) TABLE-US-00021 shelf life (bulk, −20° C.) >73 days shelf life (bulk, −30° C.)  49 days shelf life (bulk, −40° C.)  39 days shelf life (6 μm TN cell, −30° C.) >73 days shelf life (6 μm TN cell, −40° C.) >73 days

(44) The mixture shows favourable electro-optical performance and stability.

Example 5

(45) A liquid-crystal base mixture B-5 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(46) TABLE-US-00022 CP-5-N 15.00% Clearing point: 101.0° C. PGIGI-3-F 10.00% Δn [589 nm, 20° C.]: 0.173 CPG-2-F 6.00% n.sub.e [589 nm, 20° C.]: 1.680 CPG-3-F 7.00% Δε [1 kHz, 20° C.]: 11.0 CPG-5-F 5.00% ε.sub.∥ [1 kHz, 20° C.]: 15.2 CPU-5-F 10.00% CPU-7-F 10.00% PGU-3-F 4.00% PGU-5-F 3.00% PGP-2-3 4.00% PGP-2-4 5.00% PGP-2-5 4.00% CCGU-3-F 8.00% CPGP-3-OT 5.00% CPGP-5-2 4.00% Σ 100.00%

(47) A cholesteric mixture C-5 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-5 such that a pitch of 2 μm is obtained, wherein C-5 contains 99.62% of the mixture B-5 and 0.38% of R-5011.

(48) The mixture shows favourable electro-optical performance and stability.

Example 6

(49) A liquid-crystal base mixture B-6 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(50) TABLE-US-00023 APUQU-3-F 8.00% Clearing point: 127.8° C. CPU-3-F 15.00% Δn [589 nm, 20° C.]: 0.206 CCGU-3-F 8.00% n.sub.e [589 nm, 20° C.]: 1.711 CPGP-5-2 4.00% Δε [1 kHz, 20° C.]: 42.7 CPGP-5-3 4.00% ε.sub.∥ [1 kHz, 20° C.]: 48.2 CPGU-3-OT 8.00% DPGU-4-F 4.00% PGU-2-F 10.00% PGU-3-F 11.00% PGUQU-3-F 8.00% PGUQU-4-F 10.00% PGUQU-5-F 10.00% Σ 100.00%

(51) A cholesteric mixture C-6 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-6 such that a pitch of 2 μm is obtained.

(52) The mixture shows favourable electro-optical performance and stability.

Example 7

(53) A liquid-crystal base mixture B-7 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(54) TABLE-US-00024 CP-3-N 14.00% Clearing point: 119.3° C. PTP-1-O2 8.00% Δn [589 nm, 20° C.]: 0.236 PTP-3-O1 6.00% n.sub.e [589 nm, 20° C.]: 1.752 CP-3-O1 8.50% Δε [1 kHz, 20° C.]: 7.2 PGP-2-2V 8.00% ε.sub.∥ [1 kHz, 20° C.]: 11.0 CPGP-4-3 5.00% CPGP-5-2 5.00% PGP-2-3 5.00% PGP-2-4 5.00% PGP-2-5 10.00% CPTP-3-O1 6.00% CPTP-3-O2 6.00% PGUQU-3-F 7.50% PGUQU-4-F 2.00% PP-1-2V1 4.00% Σ 100.00%

(55) A cholesteric mixture C-7 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-7 such that a pitch of 2 μm is obtained.

(56) The mixture shows favourable electro-optical performance and stability.

Example 8

(57) A liquid-crystal base mixture B-8 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(58) TABLE-US-00025 CP-1V-N 16.00% Clearing point: 110.1° C. PP-2-N 7.00% Δn [589 nm, 20° C.]: 0.218 PGUQU-3-F 10.00% n.sub.e [589 nm, 20° C.]: 1.737 CPG-2-F 10.00% Δε [1 kHz, 20° C.]: 11.1 PP-1-2V1 10.00% ε.sub.∥ [1 kHz, 20° C.]: 15.3 PGIGI-3-F 12.00% CPGP-5-2 8.00% CPGP-5-3 8.00% PGP-2-3 7.00% PGP-2-4 6.00% PGP-2-5 6.00% Σ 100.00%

(59) A cholesteric mixture C-8 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-8 such that a pitch of 2 μm is obtained, wherein C-8 contains 99.51% of the mixture B-8 and 0.49% of R-5011.

(60) The mixture shows favourable electro-optical performance and stability.

Example 9

(61) A liquid-crystal base mixture B-9 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(62) TABLE-US-00026 PUQU-2-F 6.00% Clearing point: 98.1° C. PUQU-3-F 12.00% Δn [589 nm, 20° C.]: 0.166 PGU-2-F 5.00% n.sub.e [589 nm, 20° C.]: 1.668 PGU-3-F 11.00% Δε [1 kHz, 20° C.]: 11.4 PPGU-3-F 4.00% ε.sub.∥ [1 kHz, 20° C.]: 15.2 CPGP-5-2 7.00% CPGP-5-3 6.00% CPGP-4-3 7.00% CC-3-V 25.00% PGP-2-3 4.00% PGP-2-4 4.00% CPU-3-F 9.00% Σ 100.00%

(63) A cholesteric mixture C-9 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-9 such that a pitch of 2 μm is obtained.

(64) The mixture shows favourable electro-optical performance and stability.

Example 10

(65) A liquid-crystal base mixture B-10 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(66) TABLE-US-00027 PGUQU-3-F 6.00% Clearing point: 101.0° C. PGUQU-4-F 10.00% Δn [589 nm, 20° C.]: 0.194 PGUCU-5-F 10.00% n.sub.e [589 nm, 20° C.]: 1.699 PUQU-3-F 17.00% Δε [1 kHz, 20° C.]: 37.0 PGU-2-F 10.00% ε.sub.∥ [1 kHz, 20° C.]: 42.9 PGU-3-F 11.00% CPGU-3-OT 8.00% CCGU-3-F 8.00% CPU-3-F 12.00% CPGP-5-2 4.00% CPGP-5-3 4.00% Σ 100.00%

(67) A cholesteric mixture C-10 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-10 such that a pitch of 2 μm is obtained, wherein C-10 contains 99.71% of the mixture B-10 and 0.29% of R-5011.

(68) The mixture shows favourable electro-optical performance and stability.

Example 11

(69) A liquid-crystal base mixture B-11 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(70) TABLE-US-00028 CP-3-O1 8.00% Clearing point: 111.5° C. CC-3-V 12.00% Δn [589 nm, 20° C.]: 0.213 CPGP-5-2 6.00% n.sub.e [589 nm, 20° C.]: 1.729 CPGP-5-3 6.00% Δε [1 kHz, 20° C.]: 3.1 PGP-2-2V 14.00% ε.sub.∥ [1 kHz, 20° C.]: 6.3 PGP-1-2V 13.00% PGP-3-2V 13.00% PGP-2-5 6.00% PP-1-2V1 12.00% PUQU-3-F 6.00% PGUQU-3-F 4.00% Σ 100.00%

(71) A cholesteric mixture C-11 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-11 such that a pitch of 2 μm is obtained.

(72) The mixture shows favourable electro-optical performance and stability.

Example 12

(73) A liquid-crystal base mixture B-12 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(74) TABLE-US-00029 PGIGI-3-F 8.00% Clearing point: 102.0° C. GGP-3-F 8.00% Δn [589 nm, 20° C.]: 0.169 GGP-5-F 7.00% n.sub.e [589 nm, 20° C.]: 1.675 CPG-2-F 7.00% Δε [1 kHz, 20° C.]: 12.2 CPG-3-F 7.00% ε.sub.∥ [1 kHz, 20° C.]: 16.9 CPG-5-F 5.00% CPU-5-F 10.00% PGU-3-F 4.00% PGU-5-F 7.00% CCGU-3-F 8.00% CGPC-3-3 3.00% CGPC-5-3 3.00% CGPC-5-5 3.00% CPGU-3-OT 5.00% CP-5-N 15.00% Σ 100.00%

(75) A cholesteric mixture C-12 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-12 such that a pitch of 2 μm is obtained.

(76) The mixture exhibits a long shelf life at −20° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(77) TABLE-US-00030 shelf life (bulk, −20° C.) >46 days shelf life (bulk, −30° C.)  8 days shelf life (bulk, −40° C.)  8 days shelf life (6 μm TN cell, −30° C.) >46 days shelf life (6 μm TN cell, −40° C.) >46 days

(78) The mixture shows favourable electro-optical performance and stability.

Example 13

(79) A liquid-crystal base mixture B-13 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(80) TABLE-US-00031 PGIGI-3-F 7.00% Clearing point: 99.9° C. GGP-3-F 8.00% Δn [589 nm, 20° C.]: 0.179 GGP-5-F 7.00% n.sub.e [589 nm, 20° C.]: 1.681 CPG-3-F 7.00% Δε [1 kHz, 20° C.]: 13.9 CPG-5-F 5.00% ε.sub.∥ [1 kHz, 20° C.]: 18.7 CPU-5-F 10.00% PGU-2-F 6.00% PGU-3-F 6.00% PGU-5-F 7.00% CCGU-3-F 8.00% CGPC-3-3 3.00% CGPC-5-3 3.00% CGPC-5-5 3.00% CPGU-3-OT 5.00% CP-5-N 15.00% Σ 100.00%

(81) A cholesteric mixture C-13 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-13 such that a pitch of 2 μm is obtained.

(82) The mixture exhibits a long shelf life at −20° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(83) TABLE-US-00032 shelf life (bulk, −20° C.) >41 days shelf life (bulk, −30° C.) 7 days shelf life (bulk, −40° C.) 3 days shelf life (6 μm TN cell, −30° C.) >40 days shelf life (6 μm TN cell, −40° C.) 16 days

(84) The mixture shows favourable electro-optical performance and stability.

Example 14

(85) A liquid-crystal base mixture B-14 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.

(86) TABLE-US-00033 PGIGI-3-F 6.00% Clearing point: 101.0° C. GGP-3-F 7.00% Δn [589 nm, 20° C.]: 0.174 GGP-5-F 8.00% n.sub.e [589 nm, 20° C.]: 1.684 CPG-2-F 9.00% Δε [1 kHz, 20° C.]: 12.6 CPG-3-F 8.00% ε.sub.∥ [1 kHz, 20° C.]: 17.4 CPG-5-F 8.00% PGU-2-F 7.00% PGU-3-F 7.00% PGU-5-F 7.00% CCGU-3-F 8.00% CGPC-3-3 4.00% CGPC-5-3 4.00% CGPC-5-5 4.00% CP-5-N 13.00% Σ 100.00%

(87) A cholesteric mixture C-14 is prepared by adding the chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany to the base mixture B-14 such that a pitch of 2 μm is obtained.

(88) The mixture exhibits a long shelf life at −20° C. and −30° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(89) TABLE-US-00034 shelf life (bulk, −20° C.) >26 days shelf life (bulk, −30° C.)  23 days shelf life (bulk, −40° C.)  12 days shelf life (6 μm TN cell, −30° C.) >26 days shelf life (6 μm TN cell, −40° C.) >26 days

(90) The mixture shows favourable electro-optical performance and stability.

Example 15

(91) A cholesteric mixture C-15 is prepared by mixing 97.01% of mixture B-1 as described in Example 1 above with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 1.25% of compound of formula RM-A

(92) ##STR00423##

(93) 0.62% of compound of formula RM-B

(94) ##STR00424##

(95) 0.62% of compound of formula RM-C

(96) ##STR00425##
and 0.08% of the photoinitiator Irgacure© 651 (abbreviated as IRG-651 in the following)

(97) ##STR00426##
available from Ciba, Switzerland.

(98) The obtained pitch of mixture C-15 is 1.84 μm.

(99) The mixture C-15 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(100) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(101) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 97.9% is obtained. In the clear state a haze value of 5.4% is obtained.

Example 16

(102) A cholesteric mixture C-16 is prepared by mixing 98.28% of mixture B-1 as described in Example 1 with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 0.63% of compound of formula RM-D

(103) ##STR00427##

(104) 0.63% of compound of formula RM-E

(105) ##STR00428##
and 0.04% of IRG-651.

(106) The obtained pitch of mixture C-16 is 1.84 μm.

(107) The mixture C-16 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(108) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(109) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 98% is obtained. In the clear state a haze value of 4% is obtained.

Example 17

(110) A cholesteric mixture C-17 is prepared by mixing 98.28% of mixture B-12 as described in Example 12 with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 0.63% of compound of formula RM-D as shown in Example 16 above, 0.63% of compound of formula RM-E as shown in Example 16 above and 0.04% of IRG-651.

(111) The obtained pitch of mixture C-17 is 1.84 μm.

(112) The mixture C-17 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(113) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(114) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 94.4% is obtained. In the clear state a haze value of 2.3% is obtained.

Example 18

(115) A cholesteric mixture C-18 is prepared by mixing 98.28% of mixture B-4 as described in Example 4 with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 0.63% of compound of formula RM-D as shown in Example 16 above, 0.63% of compound of formula RM-E as shown in Example 16 above and 0.04% of IRG-651.

(116) The obtained pitch of mixture C-18 is 1.84 μm.

(117) The mixture C-18 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(118) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(119) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 95.7% is obtained. In the clear state a haze value of 2.6% is obtained.

Example 19

(120) A cholesteric mixture C-19 is prepared by mixing 98.28% of mixture B-14 as described in Example 14 with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 0.63% of compound of formula RM-D as shown in Example 16 above, 0.63% of compound of formula RM-E as shown in Example 16 above and 0.04% of IRG-651.

(121) The obtained pitch of mixture C-19 is 1.84 μm.

(122) The mixture C-19 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(123) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(124) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 96.7% is obtained. In the clear state a haze value of 3.3% is obtained.

Example 20

(125) A cholesteric mixture C-20 is prepared by mixing 98.28% of mixture B-13 as described in Example 13 with 0.42% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, 0.63% of compound of formula RM-D as shown in Example 16 above, 0.63% of compound of formula RM-E as shown in Example 16 above and 0.04% of IRG-651.

(126) The obtained pitch of mixture C-20 is 1.84 μm.

(127) The mixture C-20 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(128) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(129) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 96.7% is obtained. In the clear state a haze value of 2.5% is obtained.

Example 21

(130) A cholesteric mixture C-21 is prepared by mixing 91.12% of mixture B-1 as described in Example 1 above with 6.49% of chiral dopant CB 15 available from Merck KGaA, Darmstadt, Germany, 2.37% of ethyleneglycol dimethacrylate and 0.02% of IRG-651.

(131) The mixture C-21 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 25 μm.

(132) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(133) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 95.1% is obtained. In the clear state a haze value of 4.3% is obtained.

Example 22

(134) A cholesteric mixture C-22 is prepared by mixing 98.61% of mixture B-4 as described in Example 4 above with 0.64% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F

(135) ##STR00429##

(136) No photoinitiator is added. The obtained pitch of mixture C-22 is 1.1 μm.

(137) The mixture C-22 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 15 μm.

(138) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(139) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 95% is obtained. In the clear state a haze value of 2.1% is obtained.

Example 23

(140) A cholesteric mixture C-23 is prepared by mixing 98.68% of mixture B-4 as described in Example 4 above with 0.57% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(141) No photoinitiator is added. The obtained pitch of mixture C-23 is 1.24 μm.

(142) The mixture C-23 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 18 μm.

(143) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(144) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 97% is obtained. In the clear state a haze value of 3.5% is obtained.

Example 24

(145) A liquid-crystal base mixture B-24 is prepared and characterized with respect to its general physical properties, having the composition as indicated in the following table.

(146) TABLE-US-00035 CCGU-3-F 8.00% BCH-5F.F.F 10.00% PGU-5-F 7.00% PGIGI-3-F 10.00% BCH-2F.F 6.00% BCH-7F.F.F 10.00% BCH-3F.F 7.00% CBC-53F 3.00% BCH-5F.F 5.00% CBC-55F 3.00% BCH-32 4.00% PCH-5 15.00% PGU-3-F 4.00% CPGU-3-OT 5.00% CBC-33F 3.00% Σ 100.00%

(147) A cholesteric mixture C-24 is prepared by mixing 98.61% of mixture B-24 with 0.64% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(148) The mixture C-24 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 20 μm.

(149) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(150) After the polymerisation the haze is determined.

Example 25

(151) A liquid-crystal base mixture B-25 is prepared and characterized with respect to its general physical properties, having the composition as indicated in the following table.

(152) TABLE-US-00036 PGIGI-3-F 10.00% Clearing point: 105.0° C. BCH-2F.F 6.00% Δn [589 nm, 20° C.]: 0.159 BCH-3F.F 7.00% BCH-5F.F 5.00% BCH-5F.F.F 10.00% BCH-7F.F.F 10.00% PGU-3-F 4.00% PGU-5-F 7.00% CCGU-3-F 8.00% BCH-32 4.00% CBC-33F 3.00% CBC-53F 3.00% CBC-55F 3.00% CPGU-3-OT 5.00% PCH-7 15.00% Σ 100.00%

(153) The mixture exhibits a long shelf life at −20° C. and −30° C. as well as at even lower temperatures when placed in cells. The following Table shows the determined shelf life values.

(154) TABLE-US-00037 shelf life (bulk, −20° C.) >5500 h shelf life (bulk, −30° C.) >5500 h shelf life (bulk, −40° C.)  >500 h shelf life (6 μm TN cell, −20° C.) >5500 h shelf life (6 μm TN cell, −30° C.) >5500 h shelf life (6 μm TN cell, −40° C.) >5500 h

(155) A cholesteric mixture C-25 is prepared by mixing 98.884% of mixture B-25 with 0.366% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(156) The mixture C-25 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 22.5 μm.

(157) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(158) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 94.9% is obtained. In the clear state a haze value of 6.7% is obtained.

(159) A test cell of 25 mm×30 mm is fully switched at 31.5 V.

Example 26

(160) A liquid-crystal base mixture B-26 is prepared and characterized with respect to its general physical properties, having the composition as indicated in the following table.

(161) TABLE-US-00038 PGIGI-3-F 10.00% Clearing Point: 107.5° C. BCH-2F.F 4.00% BCH-3F.F 5.00% BCH-5F.F 7.00% BCH-5F.F.F 11.00% BCH-7F.F.F 10.00% PGU-3-F 4.00% PGU-5-F 7.00% DPGU-4-F 4.00% CCGU-3-F 8.00% BCH-32 3.00% CBC-33F 3.00% CBC-53F 3.00% CBC-55F 2.00% CPGU-3-OT 5.00% PCH-7 14.00% Σ 100.00%

(162) A cholesteric mixture C-26 is prepared by mixing 98.884% of mixture B-26 with 0.366% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(163) The mixture C-26 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 22.5 μm.

(164) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(165) After the polymerisation the haze is determined.

(166) A test cell of 25 mm×30 mm is fully switched at 30.0 V.

Example 27

(167) A cholesteric mixture C-27 is prepared by mixing 98.89% of mixture B-4 with 0.36% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(168) The mixture C-27 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 22.5 μm.

(169) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(170) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 95.4% is obtained. In the clear state a haze value of 5.5% is obtained.

(171) A test cell of 25 mm×30 mm is fully switched at 29.0 V.

Example 28

(172) A cholesteric mixture C-28 is prepared by mixing 98.92% of mixture B-4 with 0.33% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(173) The mixture C-28 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 22.5 μm.

(174) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(175) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 95.0% is obtained. In the clear state a haze value of 5.2% is obtained.

(176) A test cell of 25 mm×30 mm is fully switched at 26.0 V.

Example 29

(177) A cholesteric mixture C-29 is prepared by mixing 98.95% of mixture B-4 with 0.30% of chiral dopant R-5011 available from Merck KGaA, Darmstadt, Germany, and 0.75% of compound of formula RM-F as shown in Example 22 above.

(178) The mixture C-29 is filled into a test cell having glass substrates with ITO electrodes as well as polyimide alignment layers (AL-1054 from Japan Synthetic Rubber, planar, TN), wherein the cell gap is 22.5 μm.

(179) Subsequently polymerisation is carried out by irradiating the test cell with UV light (UVACUBE 2000, Hönle, 9 mW/cm.sup.2 light intensity, 340 nm cut-off filter) for 10 minutes while a square-wave voltage (70V, 60 Hz) is applied.

(180) After the polymerisation the haze is determined. In the scattering (hazy) state a haze value of 94.4% is obtained. In the clear state a haze value of 5.5% is obtained.

(181) A test cell of 25 mm×30 mm is fully switched at 24.2 V.