Method for manufacturing a liquid crystal display device and liquid crystal mixture

Abstract

The invention relates to a method of manufacturing a liquid crystal display device wherein a liquid crystal mixture having positive dielectric anisotropy or negative dielectric anisotropy is interposed between a first substrate and a second substrate, the liquid crystal mixture comprising liquid crystal molecules, a self assembling photoalignment agent, a polymerisable compound, and wherein said LC mixture is photoaligned by irradiation with linearly polarised ultraviolet light and then cured by irradiation with ultraviolet light.

Claims

1. A method for manufacturing a liquid crystal display device comprising at least the steps of: providing a first substrate which includes a pixel electrode and a common electrode; providing a second substrate, the second substrate being disposed opposite to the first substrate; interposing a liquid crystal mixture between the first substrate and the second substrate, the liquid crystal mixture comprising liquid crystal molecules, at least one self assembling photoalignment compound of formula S below and at least one polymerisable compound of formula P below; irradiating the liquid crystal mixture with linearly polarised light causing photoalignment of the liquid crystal mixture; curing the polymerisable compound by irradiation with ultraviolet light causing fixation of alignment; wherein formula S is ##STR00358## wherein Y denotes (R.sup.b).sub.2N, R.sup.cC(O)O, or a group L.sup.s, Sp denotes a spacer group, G denotes OH or Si(OR.sup.a).sub.3, R.sup.a, R.sup.b, R.sup.c each denote, identically or differently, straight chain or branched alkyl with 1 to 6 C atoms, L.sup.s each, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5, or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, t1, t2 denote 0, 1, 2, 3 or 4, and formula P is
P.sup.a-(Sp.sup.a).sub.s1-A.sup.2-(Z.sup.1-A.sup.1).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP wherein P.sup.a, P.sup.b each, independently of one another, denote a polymerisable group, Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, A.sup.1, A.sup.2 each, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 4,4-bicyclohexylene, in which one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and wherein one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which one or two CH groups may be replaced by N and wherein one or more H atoms may be replaced by L, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may be replaced by heteroatoms, n2 denotes 0, 1, 2 or 3, Z.sup.1 in each case, independently of one another, denotes COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, or (CH.sub.2).sub.n, where n is 2, 3 or 4, O, CO, C(R.sup.0R.sup.00), CH.sub.2CF.sub.2, CF.sub.2CF.sub.2 or a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, R.sup.0, R.sup.00 each, independently of one another, denote H, F or straight-chain or branched alkyl having 1 to 12 C atoms, wherein one or more H atoms may be replaced by F, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, and Y.sup.1 and Y.sup.2 each, independently of one another, have one of the meanings indicated above for R.sup.0 or denote Cl or CN.

2. The method according to claim 1, wherein the linearly polarised light is linearly polarised ultraviolet light.

3. The method according to claim 1, wherein the total concentration of the at least one compound of formula S in the liquid crystal mixture is 0.01 to 10%.

4. The method according to claim 1, wherein the total concentration of the at least one or compound of formula P in the liquid crystal mixture is in the range of from 0.01 to 10%.

5. The method according to claim 1, wherein the LC mixture comprises at least one compound selected from the group of compounds of formulae P10-1-1 and P10-1-2 ##STR00359## wherein n4 denotes an integer between 2 and 10.

6. The method according to claim 1, wherein the at least one compound of formula S is of formula S-1 ##STR00360## wherein Y and G have the meaning as defined for formula S, X.sup.s denotes O, C(O)O, C(O)NH or a single bond, and n1 is an integer from 0 to 10.

7. The method according to claim 1, wherein the LC mixture has negative dielectric anisotropy.

8. The method according to claim 7, wherein the LC mixture comprises at least one compound selected from the group of the following formulae: ##STR00361## wherein a denotes 1 or 2, b denotes 0 or 1, ##STR00362## R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH.sub.2 groups may be replaced by O, CHCH, CO, OCO or COO in such a way that O atoms are not linked directly to one another, Z.sup.x denotes CHCH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, O, CH.sub.2, CH.sub.2CH.sub.2 or a single bond, and L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, or CHF.sub.2.

9. The method according to claim 1, wherein the LC mixture has positive dielectric anisotropy.

10. The method according to claim 9, wherein the LC mixture comprises at least one compound selected from the group of compounds of formulae II and III, ##STR00363## wherein R.sup.20 each, identically or differently, denotes a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH.sub.2 groups may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00364## O, COO or OCO in such a way that O atoms are not linked directly to one another, X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, Y.sup.20-24 each, identically or differently, denote H or F, and ##STR00365## each, identically or differently, denote ##STR00366##

11. The method according to claim 9, wherein the liquid crystal mixture comprises at least one compound selected from the group of compounds of formulae XI and XII ##STR00367## wherein ##STR00368## and each, independently of one another, denote ##STR00369## ##STR00370## R.sup.20 each, identically or differently, denotes a halogenated or unsubstituted alkyl or alkoxy radical 1 to 15 C atoms, in which one or more CH.sub.2 groups may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00371## O, COO or OCO in such a way that O atoms are not linked directly to one another, X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, and Y.sup.20-23 each, identically or differently, denotes H or F.

12. The method according to claim 1, wherein the LC mixture comprises at least one compound of formula D: ##STR00372## wherein ##STR00373## R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH.sub.2 groups may be replaced by O, CHCH, CO, OCO or COO in such a way that O atoms are not linked directly to one another, and Z.sup.y denotes CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF or a single bond.

13. The method according to claim 1, wherein the LC mixture comprises at least one compound selected from the following formulae: ##STR00374##

14. A liquid crystal display, which is manufactured according to the method of claim 1.

15. The liquid crystal display according to claim 14, which is an IPS or FFS display.

16. A compound of formula S ##STR00375## wherein Y denotes (R.sup.b).sub.2N, R.sup.cC(O)O, or a group L.sup.s, Sp denotes a spacer group, G denotes OH or Si(OR.sup.a).sub.3, R.sup.a, R.sup.b, R.sup.c each denote, identically or differently, straight chain or branched alkyl with 1 to 6 C atoms, L.sup.s each, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5, or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy have up to 12 C atoms, and t1, t2 denotes 0, 1, 2, 3 or 4, with the proviso that the following compound is excluded: ##STR00376##

17. An LC mixture, comprising a compound of formula S according to claim 16 and liquid crystal molecules and a polymerisable compound of formula P
P.sup.a-(Sp.sup.a).sub.s1-A.sup.2-(Z.sup.1-A.sup.1).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP wherein P.sup.a, P.sup.b each, independently of one another, denote a polymerisable group, Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, A.sup.1, A.sup.2 each, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 4,4-bicyclohexylene, in which one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and wherein one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which one or two CH groups may be replaced by N and wherein one or more H atoms may be replaced by L, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may be replaced by heteroatoms, n2 denotes 0, 1, 2 or 3, Z.sup.1 in each case, independently of one another, denotes COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, or (CH.sub.2).sub.n, where n is 2, 3 or 4, O, CO, C(R.sup.0R.sup.00), CH.sub.2CF.sub.2, CF.sub.2CF.sub.2 or a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 12 C atoms, R.sup.0, R.sup.00 each, independently of one another, denote H, F or straight-chain or branched alkyl having 1 to 12 C atoms, in which one or more H atoms may be replaced by F, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, and Y.sup.1 and Y.sup.2 each, independently of one another, have one of the meanings indicated above for R.sup.0 or denote Cl or CN.

18. A process for preparing an LC mixture according to claim 17, comprising mixing at least one mesogenic or liquid crystalline compound with at least one self assembling photoalignment compound of formula S and at least one polymerisable compound of formula P.

19. A liquid crystal display, comprising an LC mixture according to claim 17.

20. The liquid crystal display according to claim 19, which is an IPS or FFS display.

Description

EXAMPLES

(1) Hereinafter, the present invention is described in more detail and specifically with reference to the Examples, which however are not intended to limit the present invention.

Synthesis

Synthesis of Example S-2

Stage 1: 2-[2-(4-acetoxyphenyl)-diazenyl]benzoic acid

(2) ##STR00355##

(3) To a solution of 2-[2-(4-hydroxyphenyl)-diazenyl]benzoic acid (20.0 g, 0.083 mol) in dichloromethane (150 ml) and pyridine (43 ml) was added acetic anhydride (17.3 g; 0.17 mol). After stirring overnight at ambient temperature the mixture was partitioned between dichloromethane (500 ml) and 2M hydrochloric acid (500 ml). The aqueous layer was re-extracted with dichloromethane (300 ml) and the combined organic layers were dried over sodium sulphate, filtered and then evaporated in vacuo. The residue was purified by chromatography on silica gel (300 g) eluting with 0-5% ethyl acetate in dichloromethane to yield the product as an orange solid.

Stage 2

(4) ##STR00356##

(5) To a solution of 2-[2-(4-acetoxyphenyl)-diazenyl]benzoic acid (2.58 g; 0.0092 mol) and N-hydroxysuccinimide (1.15 g; 0.01 mol) in anhydrous dichloromethane (24 ml) was added dicyclohexylcarbodiimide (1M in dichloromethane; 9.5 ml; 0.0095 mol). After 30 minutes, (3-aminopropyl)trimethoxysilane (2.13 g; 2.1 ml; 0.012 moles) was added to the red slurry. After 20 hours, the reaction mixture was evaporated, slurried in 1:1 ethyl acetate/petroleum ether (70 ml), filtered and the solids were washed with 1:1 ethyl acetate:40/60 petroleum ether (250 ml). The filtrate was evaporated in vacuo to a dark red oil and layered onto a 60 g silica gel column. Elution with 20-33% ethyl acetate in 40/60 petroleum ether afforded Example S:2 as a red oil.

(6) Fabrication of Display Cells

(7) The display cells are made with raw untreated alkali-free glass using 5 m spacer beads in Norland 65 adhesive. The cells are assembled by hand and then cured using a high pressure mercury lamp at 50 mW/cm.sup.2 and 3000mJ/cm.sup.2.

(8) Cell Filling and Curing

(9) The LC mixtures are capillary filled on a hot plate at 100 C., then left to stand for a further hour at 100 C. and then irradiated with linearly polarised UV light (50 mW/cm.sup.2) for 60s. The cells are cooled slowly to room temperature at a cooling rate of 5 C. per minute.

(10) Mixture Examples

(11) A nematic LC host mixture N-1 was prepared as follows:

(12) TABLE-US-00007 Mixture N-1: Composition Compound No. Abbreviation c/% 1 CC-3-V 37.00 2 CCY-3-O1 5.00 3 CCY-3-O2 9.50 4 CCY-4-O2 5.00 5 CPY-2-O2 10.00 6 CPY-3-O2 10.00 7 CY-3-O2 11.50 8 PY-3-O2 12.00 100.0 Physical properties T(N, I) = 73.5 C. n.sub.e (20 C., 589.3 nm) = 1.583 n (20 C., 589.3 nm) = 0.1005 .sub.|| (20 C., 1 kHz) = 3.70 (20 C., 1 kHz) = 3.65 k.sub.1(20 C.) = 12.7 k.sub.3(20 C.) = 14.7 .sub.1 (20 C.) = 93

(13) A nematic LC host mixture N-2 was prepared as follows:

(14) TABLE-US-00008 Mixture N-2: Composition Compound No. Abbreviation c/% 1 APUQU-2-F 6.00 2 APUQU-3-F 6.00 3 CC-3-V 44.5 4 CC-3-V1 4.00 5 CCP-3OCF.sub.3 7.00 6 CCP-V-1 5.00 7 CPGU-3-OT 3.00 8 PGP-2-2V 5.50 9 PGUQU-3-F 3.00 10 PGUQU-4-F 7.00 11 PGUQU-5-F 3.00 12 PUQU-3-F 6.00 100.0 Physical properties T(N, I) = 73.5 C. n.sub.e (20 C., 589.3 nm) = 1.5902 n (20 C., 589.3 nm) = 0.1086 .sub.|| (20 C., 1 kHz) = 12.9 (20 C., 1 kHz) = 9.6 k.sub.1(20 C.) = 12.4 k.sub.3(20 C.) = 13.8 .sub.1 (20 C.) = 67

Example 1

(15) A test display is fabricated according to the procedure described above without the UV-irradiation step, using 1% of S-2 in nematic host mixture N-1. The cell is placed between crossed polarisers on a light table and aligned so that a dark state is achieved. Rotation by 45 gives the bright state. Both dark and bright state appear uniform which proves uniform planar alignment.

(16) The alignment is reversible when the cell is heated above the clearing point of the liquid crystal host mixture for 30 min.

Example 2

(17) To fix the alignment, 3% of compound 10-1-1a are added to the mixture from Example 1 and the fabrication process was performed in the same way.

(18) ##STR00357##

(19) The cell is investigated in the same way as described in Example 1 and uniform planar alignment is observed. Afterwards the cell is heated at 100 C. and at the same time illuminated with polarised white light for 30 min. Investigation between crossed polarizer show no change of the uniform planar alignment nor rotation of the alignment direction.

Example 3

(20) A test display is fabricated according to the procedure described above without the UV-irradiation step, using 1% of S-2 in nematic host mixture N-2. The cell is placed between crossed polarisers on a light table and aligned so that a dark state is achieved. Rotation by 45 gives the bright state. Both dark and bright state appear uniform which proves uniform planar alignment.

(21) In each case the alignment can be equally achieved using either UV or white linearly polarised light.