Polymerisable LC medium and polymer film with negative optical dispersion

Abstract

The invention relates to a polymerizable LC medium with negative optical dispersion, a polymer film with negative optical dispersion obtainable from such a medium, and the use of the polymerizable LC medium and polymer film in optical, electro optical, electronic, semiconducting or luminescent components or devices.

Claims

1. A polymerizable liquid crystal medium comprising one or more compounds of formula A, ##STR00036## wherein P is independently of one another, a polymerizable group, Sp is a spacer group or a single bond, L.sup.a is, in case of multiple occurrence identically or differently, F, Cl, CN, SCN, SF.sub.5 or a straight-chain or branched, unsubstituted or mono- or polyfluorinated, alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, or optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 5 C atoms, r is 0, 1, 2, 3 or 4, wherein the amount of compounds of formula A in the medium as a whole is from 5 to 40 wt. %; and one or more compounds of formula I, ##STR00037## wherein U.sup.1,2 are independently of each other selected from ##STR00038## including their mirror images, wherein the rings U.sup.1 and U.sup.2 are each bonded to the bridging group (B).sub.q- via the axial bond, and one or two non-adjacent CH.sub.2 groups in these rings are each optionally replaced by O or S, and the rings U.sup.1 and U.sup.2 are optionally substituted by one or more groups L, L is, in case of multiple occurrence identically or differently, P-Sp-, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X, C(O)OR.sup.0, C(O)R.sup.0, NR.sup.0R.sup.00, OH, SF.sub.5, optionally substituted silyl, aryl or heteroaryl with up to 12 C atoms, and straight chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 12 C atoms, wherein one or more H atoms are each optionally replaced by F or Cl, X is halogen, Q.sup.1,2 are independently of each other CH or SiH, Q.sup.3 is C or Si, B is in each occurrence independently of one another CC-, CY.sup.1CY.sup.2- or an optionally substituted aromatic or heteroaromatic group, Y.sup.1,2 are independently of each other H, F, Cl, CN or R.sup.0, q is an integer from 1 to 10, A.sup.1-4 are independently of each other selected from non-aromatic, aromatic or heteroaromatic carbocylic or heterocyclic groups, which are unsubstituted or substituted by one or more groups R.sup.5, and wherein each of -(A.sup.1-Z.sup.1).sub.m-U.sup.1-(Z.sup.2-A.sup.2).sub.n- and -(A.sup.3-Z.sup.3).sub.oU.sup.2-(Z.sup.4-A.sup.4).sub.p- does not contain more aromatic groups than non-aromatic groups, Z.sup.1-4 are independently of each other O, S, CO, COO, OCO, OCOO, CONR.sup.0, NR.sup.0CO, NR.sup.0CONR.sup.0, 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.2CH.sub.2, (CH.sub.2.sup.).sub.3, (CH.sub.2).sub.4, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHCH, CY.sup.1CY.sup.2, CHN, NCH, NN, CHCR.sup.0, CC, CHCHCOO, OCOCHCH, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.00 are independently of each other H or alkyl with 1 to 12 C-atoms, m and n are independently of each other 0, 1, 2, 3 or 4, o and p are independently of each other 0, 1, 2, 3 or 4, R.sup.1-5 are independently of each other identical or different groups selected from H, halogen, CN, NC, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X.sup.0, C(O)R.sup.0, NH.sub.2, NR.sup.0R.sup.00, SH, SR.sup.0, SO.sub.3H, SO.sub.2R.sup.0, OH, NO.sub.2, CF.sub.3, SF.sub.5, PSp-, optionally substituted silyl, and carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, or denote P or P-Sp-, or are substituted by P or P-Sp-, wherein the compounds comprise at least one group R.sup.1-5 denoting or being substituted by P or P-Sp-, P is a polymerizable group, and Sp is a spacer group or a single bond.

2. The polymerizable liquid crystal medium according to claim 1, wherein compounds of formula A are selected from the following subformula, ##STR00039## wherein x, y, z, are independently of each other 0 or identical or different integers from 1 to 12.

3. The polymerizable liquid crystal medium according to claim 1, wherein the bridging group (B).sub.q is selected from CC, CCCC, CCCCCC, CCCCCCCC, ##STR00040## wherein r is 0, 1, 2, 3 or 4, L is selected from P-Sp-, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X, C(O)OR.sup.0, C(O)R.sup.0, NR.sup.0R.sup.00, OH, SF.sub.5, optionally substituted silyl, aryl with up to 12 C atoms, and straight chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 12 C atoms, wherein one or more H atoms are each optionally replaced by F or Cl, R.sup.0 and R.sup.00 are independently of each other H or alkyl with 1 to 12 C-atoms, and X is halogen.

4. The polymerizable liquid crystal medium according to claim 1, wherein the non-aromatic rings of the mesogenic groups U.sup.1 and U.sup.2 are selected from ##STR00041## wherein R.sup.5 has one of the meanings as given above in claim 1.

5. The polymerizable liquid crystal medium according to claim 1, wherein A.sup.1-4 are trans-1,4-cyclohexylene or 1,4-phenylene, which in each case is unsubstituted or substituted with one or more groups L, wherein L is P-Sp-, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X, C(O)OR.sup.0, C(O)R.sup.0, NR.sup.0R.sup.00, OH, SF.sub.5, optionally substituted silyl, aryl with up to 12 C atoms, or straight chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 12 C atoms, wherein one or more H atoms are optionally replaced by F or Cl, wherein R.sup.0 and R.sup.00 are independently of each other H or alkyl with 1 to 12 C-atoms, and X is halogen.

6. The polymerizable liquid crystal medium according to claim 1, wherein Z.sup.1-4 are selected from O, S, CO, COO, OCO, OCOO, CONR.sup.0, NR.sup.0CO, NR.sup.0CONR.sup.0, 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.2CH.sub.2, (CH.sub.2.sup.).sub.3, (CH.sub.2).sub.4, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHCH, CY.sup.1CY.sup.2, CHN, NCH, NN, CHCR.sup.0, CC, CHCHCOO, OCOCHCH, CR.sup.0R.sup.00 or a single bond, wherein R.sup.0, R.sup.00, Y.sup.1 and Y.sup.2 have the meanings given in claim 1.

7. The polymerizable liquid crystal according to claim 1, wherein the polymerizable compounds of formula I are selected from the following subformulae: ##STR00042## ##STR00043## ##STR00044## wherein R.sup.1-5, A.sup.1-4, Z.sup.1-4, B, m, n, o, p and q have the meanings given in claim 1.

8. The polymerizable liquid crystal medium according claim 1, characterized in that the polymerizable compounds of formula I are selected from the following subformulae: ##STR00045## ##STR00046## ##STR00047## ##STR00048## ##STR00049## wherein Z is O, S, CO, COO, OCO, OCOO, CONR.sup.0, NR.sup.0CO, NR.sup.0CONR.sup.0, 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.2CH.sub.2, (CH.sub.2.sup.).sub.3, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHCH, CY.sup.1CY.sup.2, CHN, NCH, NN, CHCR.sup.0, CC, CHCHCOO, OCOCHCH, CR.sup.0R.sup.00 or a single bond, R is H, halogen, CN, NC, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X.sup.0, C(O)R.sup.0, NH.sub.2, NR.sup.0R.sup.00, SH, SR.sup.0, SO.sub.3H, SO.sub.2R.sup.0, OH, NO.sub.2CF.sub.3, SF.sub.5, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, and P, Sp, L and r are as defined in claim 1, and the benzene rings in the mesogenic groups are optionally substituted by one or more groups L as defined in claim 1.

9. The polymerizable liquid crystal medium according to claim 8, wherein the polymerizable compounds of formula I are selected from sub formulae I 25 or I 26, Z denotes COO, and r is in each occurrence 0.

10. The polymerizable liquid crystal medium according to claim 1, further comprising one or more further compounds that are optionally polymerizable and/or mesogenic or liquid crystalline.

11. A polymer film obtainable by polymerizing the polymerizable LC medium as defined in claim 1 having a liquid crystal in an oriented state in form of a thin film.

12. An optical, electronic or electro optical device, or a component thereof, comprising a polymer film according to claim 11.

13. An optical component according to claim 12, wherein said optical component is an optically uniaxial film selected from an A-plate, C-plate, negative C-plate or O-plate, a twisted optical retarder, a twisted quarter wave foil, an optically biaxial film, an achromatic retarder, an achromatic quarter wave foil or half wave foil, a film having a cholesteric, smectic, nematic or blue phase, and a film having homeotropic, splayed, tilted, planar or blue-phase alignment, which is uniformly oriented or exhibits a pattern of different orientations.

14. An optical component according to claim 12, wherein said optical component is an optical compensation film for viewing angle enhancement of a liquid crystal display, a component in a brightness enhancement film, or an achromatic element in reflective or transflective liquid crystal display.

15. A device or component according to claim 12, wherein said device or component is selected from electrooptical displays, liquid crystal displays, optical films, polarizers, compensators, beam splitters, reflective films, alignment layers, color filters, holographic elements, hot stamping foils, colored images, decorative or security markings, LC pigments, adhesives, non-linear optic devices, optical information storage devices, electronic devices, organic semiconductors, organic field effect transistors, integrated circuits, thin film transistors, Radio Frequency Identification (RFID) tags, organic light emitting diodes, organic light emitting transistors, electroluminescent displays, organic photovoltaic devices, organic solar cells, organic laser diodes, organic integrated circuits, lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarizing layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic applications, electrophotographic recording, organic memory devices, biosensors, biochips, optoelectronic devices requiring similar phase shift at multiple wavelengths, combined CD/DVD/HD-DVD/Blu-Rays, reading, writing re-writing data storage systems, and cameras.

16. Device or component according to claim 12, wherein said device or component is selected from electro optical displays, liquid crystal displays, optical films, polarizers, compensators, beam splitters, reflective films, alignment layers, filters, holographic elements, hot stamping foils, colored images, decorative or security markings, liquid crystal pigments, adhesives, non-linear optic devices, optical information storage devices, electronic devices, organic semiconductors, organic field effect transistors, integrated circuits, thin film transistors, Radio Frequency Identification tags, organic light emitting diodes, organic light emitting transistors, electroluminescent displays, organic photovoltaic devices, organic solar cells, organic laser diodes, organic integrated circuits, lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarizing layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic applications, electrophotographic recording, organic memory devices, biosensors, and biochips.

17. An optical, electronic or electro optical device, or a component thereof, comprising a polymerizable liquid crystal medium according to claim 1.

18. An optical component according to claim 17, wherein said component is an optically uniaxial film selected from an A-plate, C-plate, negative C-plate or O-plate, a twisted optical retarder, a twisted quarter wave foil, an optically biaxial film, an achromatic retarder, an achromatic quarter wave foil or half wave foil, a film having a cholesteric, smectic, nematic or blue phase, and a film having homeotropic, splayed, tilted, planar or blue-phase alignment, which is uniformly oriented or exhibits a pattern of different orientations.

19. An optical component according to claim 17, wherein said optical component is an optical compensation film for viewing angle enhancement of liquid crystal displays, a component in a brightness enhancement films, or an achromatic element in a reflective or transflective liquid crystal display.

20. The polymerizable liquid crystal medium according to claim 1, wherein the amount of compounds of formula A in the medium as a whole is from 5 to 35 wt. %.

21. The polymerizable liquid crystal medium according to claim 20, wherein said medium has a negative retardation dispersion, R.sub.450/R.sub.550, of <0.9.

22. The polymerizable liquid crystal medium according to claim 20, wherein said medium has a negative retardation dispersion, R.sub.450/R.sub.550, of <0.8.

23. The polymerizable liquid crystal medium according to claim 1, wherein the bridging group (B).sub.q- is selected from CC, CCCC, CCCCCC, CCCCCCCC, ##STR00050## wherein r is 0, 1, 2, 3 or 4, L is selected from P-Sp-, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)NR.sup.0R.sup.00, C(O)X, C(O)OR.sup.0, C(O)R.sup.0, NR.sup.0R.sup.00, OH, SF.sub.5, optionally substituted silyl, aryl with up to 12 C atoms, and straight chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 12 C atoms, wherein one or more H atoms are each optionally replaced by F or Cl, R.sup.0 and R.sup.00 are independently of each other H or alkyl with 1 to 12 C-atoms, and X is halogen.

24. The polymerizable liquid crystal medium according claim 8, wherein the polymerizable compounds of formula I are selected from the subformulae I1 to I24.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a and 1b show the retardation dispersion and retardation versus viewing angle at different wavelengths for the mixture of Comparative Example 1;

(2) FIGS. 2a and 2b show the retardation dispersion and retardation versus viewing angle at different wavelengths for the mixture of Example 1;

(3) FIGS. 3a and 3b show the retardation dispersion and retardation versus viewing angle at different wavelengths for the mixture of Comparative Example 2; and

(4) FIGS. 4a and 4b show the retardation dispersion and retardation versus viewing angle at different wavelengths for the mixture of Example 4.

EXAMPLES

(5) For the preparation of the following mixtures, the following compounds and abbreviations are used:

(6) ##STR00035##

(7) LC242 is a polymerisable chiral material commercially available from BASF AG (Ludwigshafen, Germany).

(8) General Method for the Polymer Film Preparation:

(9) First, a 33.3% w/w solution of the corresponding LC medium in Toluene/Cyclohexane solution (7:3) is prepared.

(10) The solution is spin coated at 3000 rpm for 30 s onto a rubbed polyimide coated glass slide where it aligns homeotropically.

(11) The sample is annealed at the given temperature for 60 s on a temperature controlled hot plate.

(12) The sample is cooled for 60 s to 20 C. under a nitrogen atmosphere and then UV cured (365 nm filter, 80 mW/cm.sup.2) for 60 s at 20 C.

(13) Retardation is measured at angles of incidence from 40 to 60 at 20 intervals at a temperature of 20 C. and at a wavelengths ranging from 400 to 700 nm.

Comparative Example 1

(14) The following mixture having a clearing point of 81 C. and a birefringence of 0.06 at 550 nm is formulated (in wt. %):

(15) TABLE-US-00001 Irgacure 369 1.00 Irganox 1076 0.12 LC242 24.98 RM 2 40.00 RM 3 17.91 RM 4 14.99 Zonyl FSO 100 1.00

(16) The mixture can be annealed at temperatures ranging from 69 to 61 C.

(17) The retardation profile (retardation dispersion and retardation versus viewing angle at different wavelengths) as shown in FIGS. 1a and 1b is measured using an ellipsometer, and the thickness of 2.29 m is measured using a surface profiler.

(18) The retardation dispersion values at different angles of incidence are shown in Table 1 below.

(19) TABLE-US-00002 TABLE 1 Angle () 60 40 20 0 20 40 R.sub.550 119.1 131.5 141.8 146.2 143.7 135.2 R.sub.450/R.sub.550 0.909 0.906 0.905 0.905 0.905 0.905

(20) In order to test the durability of the polymer film, the film is exposed to a temperature of 80 C. for a time up to 169 h. Table 1.1 summarizes the result of the durability test

(21) TABLE-US-00003 TABLE 1.1 Time at 80 C. [h] 0 0.5 1 2 4 7 24 169 R(450)/R(550) 0.905 0.935 0.939 0.943 0.947 0.950 0.953 0.961

Example 1

(22) The following mixture having a clearing point of 81 C. and a birefringence of 0.06 at 550 nm is formulated (in wt. %):

(23) TABLE-US-00004 Irgacure 369 1.00 Irganox 1076 0.12 LC242 16.66 RM 1 37.63 RM 2 30.00 RM 4 13.59 Zonyl FSO 100 1.00

(24) The mixture can be annealed at temperatures ranging from 80 to 51 C.

(25) The retardation profile (retardation dispersion and retardation versus viewing angle at different wavelengths) as shown in FIGS. 2a and 2b is measured using an ellipsometer, and the thickness of 2.29 m is measured using a surface profiler.

(26) The retardation dispersion values at different angles of incidence are shown in Table 2 below.

(27) TABLE-US-00005 TABLE 2 Angle () 60 40 20 0 20 40 R550 131.2 145.7 157.9 163.4 160.6 150.7 R450/R550 0.925 0.920 0.919 0.918 0.918 0.919

(28) In order to test the durability of the polymer film, the film is exposed to a temperature of 80 C. for a time up to 169 h. Table 2.1 summarizes the result of the durability test

(29) TABLE-US-00006 TABLE 2.1 Time at 80 C. [h] 0 0.5 1 2 4 7 24 169 R(450)/R(550) 0.900 0.909 0.910 0.912 0.912 0.913 0.915 0.919

Comparative Example 2

(30) The following mixture having a clearing point of 83 C. and a birefringence of 0.06 at 550 nm is formulated (in wt. %):

(31) TABLE-US-00007 Irgacure 369 1.00 Irganox 1076 0.12 LC242 26.30 RM 2 40.00 RM 3 18.87 RM 4 13.11 TegoTwin 4100 0.60

(32) The mixture can be annealed at temperatures ranging from 71 to 65 C.

(33) The retardation profile (retardation dispersion and retardation versus viewing angle at different wavelengths) as shown in FIGS. 3a and 3b is measured using an ellipsometer and the thickness of 2.29 m is measured using a surface profiler.

(34) The retardation dispersion values at different angles of incidence are shown in Table 3 below.

(35) TABLE-US-00008 TABLE 3 Angle () 60 40 20 0 20 40 R550 129.4 142.5 153.8 159.1 156.7 147.9 R450/R550 0.925 0.920 0.918 0.917 0.918 0.920

(36) In order to test the durability of the polymer film, the film is exposed to a temperature of 80 C. for a time up to 260 h. Table 3.1 summarizes the result of the durability test

(37) TABLE-US-00009 TABLE 3.1 Time at 80 C. [h] 0 0.5 1 2 5 22 97 260 R(450)/R(550) 0.918 0.949 0.953 0.956 0.961 0.968 0.976 0.986

Example 2

(38) The following mixture having a clearing point of 76 C. and a birefringence of 0.06 at 550 nm is formulated (in wt. %):

(39) TABLE-US-00010 Irgacure 369 1.00 Irganox 1076 0.12 LC242 26.88 RM 1 37.63 RM 2 30.00 RM 4 3.77 TegoTwin 4100 0.60

(40) The mixture can be annealed at temperatures ranging from 70 to 52 C.

(41) The retardation profile (retardation dispersion and retardation versus viewing angle at different wavelengths) as shown in FIGS. 4a and 4b is measured using an ellipsometer and the thickness of 2.29 m is measured using a surface profiler.

(42) The retardation dispersion values at different angles of incidence are shown in Table 4 below.

(43) TABLE-US-00011 TABLE 4 Angle () 60 40 20 0 20 40 R550 109.0 120.2 129.8 134.2 132.2 124.8 R450/R550 0.921 0.917 0.914 0.914 0.914 0.916

(44) In order to test the durability of the polymer film, the film is exposed to a temperature of 80 C. for a time up to 260 h. Table 4.1 summarizes the result of the durability test

(45) TABLE-US-00012 TABLE 4.1 Time at 80 C. [h] 0 0.5 1 2 5 22 97 260 R(450)/R(550) 0.914 0.922 0.924 0.924 0.926 0.928 0.931 0.934

(46) Dispersion Control

(47) The following mixtures comprising each 1.00 wt. % Irgacure 369, 0.08 wt. % Irganox 1076 and 1.00 wt. % Zonyl FSO 100, are formulated (in wt. %):

(48) TABLE-US-00013 No. RM 1 RM 2 RM 3 RM 4 LC 242 R.sub.450/R.sub.550 I 0.00 40.00 17.92 15.00 25.00 0.90 II 3.25 40.00 14.67 15.00 25.00 0.88 III 6.51 40.00 11.41 15.00 25.00 0.87 IV 9.77 40.00 8.15 15.00 25.00 0.85 V 13.04 40.00 4.88 15.00 25.00 0.83 VI 17.92 40.00 0.00 15.00 25.00 0.79

(49) As can be seen from the values for R.sub.450/R.sub.550, RM 1 is required to achieve a strong negative dispersion effect and by using RM 1, dispersions as low as 0.79 can be achieved.