Liquid-crystal medium
A liquid-crystal (LC) medium comprising polymerizable compounds, its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the PSA (polymer sustained alignment) or SA (self-aligning) mode, an LC display of the PSA or SA mode comprising the LC medium, and a process of manufacturing the LC display.
1 . An LC medium comprising:
(i) a polymerizable component A) comprising one or more polymerizable compounds selected from formula M13:
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
P 1 , P 2 an acrylate or methacrylate group,
Sp 1 , Sp 2 a single bond,
L F, Cl, CN or straight-chain, optionally mono- or polyfluorinated alkyl or alkoxy 1 to 12 C atoms, straight-chain, optionally mono- or polyfluorinated alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 to 12 C atoms, or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 3 to 12 C atoms, and
r 0, 1, 2, 3 or 4;
(ii) a liquid-crystalline component B), comprising one or more mesogenic or liquid-crystalline compounds, wherein component B) comprises
one or more compounds of formula IIB2
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and
at least two compounds of formula IA, one or more compounds of formula IB, and at least one compound of formula IC-1 and/or IC-2 as defined below
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
R 1 , R 2 straight chain alkyl having 1 to 25 C atoms, branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, CR 0 ═CR 00 —, —C≡C—,
in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl,
R 0 , R 00 H or alkyl having 1 to 12 C atoms,
L 1 , L 2 F,
alkyl an alkyl radical having 1 to 7 C atoms, and
alkenyl an alkenyl radical having 2 to 5 C atoms,
wherein the proportion of compounds of formula IA in the component B) of the LC medium is >8% by weight, and wherein the total proportion of compounds of formulae IC-1 and/or IC-2 in the LC medium is from 20 to 45% by weight; and
(iii) one or more compounds of formula III2-2:
in which
L 11 and L 12 each, independently of one another, denote F, Cl, CF 3 or CHF 2 ,
(O) denotes O or a single bond,
R IIIA denotes an alkyl having 1-7 C atoms, an alkenyl having 2-7 C atoms or a group Cy-C m H 2m+1 —,
m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, and
Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, wherein the cycloaliphatic group is optionally substituted with an alkyl having 1-3 carbon atoms, an alkenyl having 2-3 C atoms or with halogen or CN.
2 . The LC medium according to claim 1 , wherein the one or more compounds of formula IA are selected from the group consisting of the formulae IA-1 to IA-10:
in which
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms,
alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms,
alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and
L 1 and L 2 each, independently of one another, denote F or Cl.
3 . The LC medium according to claim 1 , wherein the one or more compounds of formula IB are selected from the group consisting of the following subformulae:
in which alkyl and alkyl* independently of each other denote a straight-chain alkyl radical having 1-6 C atoms and (O) denotes an oxygen atom or a single bond.
4 . The LC medium according claim 1 , further comprising one or more compounds selected from the group consisting of the formulae IC-3 to IC-12:
5 . The LC medium according to claim 1 , comprising, in addition to and other than the one or more compounds of formula IIB-2, one or more compounds of formula II
wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
R 1 and R 2 straight chain alkyl having 1 to 25 C atoms, branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, CR 0 ═CR 00 —, —C≡C—,
in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, H or alkyl having 1 to 12 C atoms,
R 0 , R 00 H or alkyl having 1 to 12 C atoms,
A1 and A2 a group selected from the following formulae
Z 1 and Z 2 —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O-, —OCH 2 —, —CO—O—, —O—CO—, —C 2 F 4 —, —CF═CF—, —CH═CH—CH 2 O— or a single bond,
L 1 , L 2 , L 3 and L 4 F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F or CHF 2 ,
Y H, F, Cl, CF 3 , CHF 2 or CH 3 ,
L C CH 3 or OCH 3 ,
a1 1 or 2, and
a2 0 or 1.
6 . The LC medium according claim 5 , wherein the one or more compounds of formula II in addition to and other than the one or more compounds of formula IIB-2 comprise one or more compounds of the formulae IIA, IIB, IIC and IID
in which
R 2A and R 2B each, independently of one another, denote H, an alkyl radical having up to 15 C atoms or an alkenyl radical having 2 to 15 C atoms, the alkyl or alkenyl radical being unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals may be replaced by —O—, —S—,
—C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another,
L 1 to L 4 each, independently of one another, denote F, Cl, CF 3 or CHF 2 ,
Y denotes H, F, Cl, CF 3 , CHF 2 or CH 3 ,
Z 2 , Z 2 B and Z 2 D each, independently of one another, denote a single bond, —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —COO—, —OCO—, —C 2 F 4 —, —CF═CF—, —CH═CHCH 2 O—,
p denotes 0, 1 or 2, and
q on each occurrence, identically or differently, denotes 0 or 1.
7 . The LC medium according to claim 1 , wherein it additionally comprises one or more compounds of formula IV
in which
R 41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, and
R 42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms.
8 . The LC medium according to claim 7 , wherein it additionally comprises one or more compounds of formula V
in which
R 51 and R 52 independently of one another, have one of the meanings given for R 41 and R 42 ,
identically or differently, denote
Z 51 , Z 52 each, independently of one another, denote —CH 2 —CH 2 —, —CH 2 —O—, —CH═CH—, —C≡C—, —COO— or a single bond, and
n is 1 or 2.
9 . The LC medium according to claim 1 , further comprising one or more compounds of formula V-16
in which R 1 and R 2 each, independently of one another, denote straight-chain alkyl with 1 to 6 C atoms.
10 . The LC medium according to claim 1 , wherein the one or more polymerizable compounds comprise, in addition to and other than the one or more polymerizable compounds selected from formula M13, one or more compounds of formula M
R a —B 1 —(Z b —B 2 ) m —R b
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
R a and R b P, P-Sp-, H, F, Cl, Br, I, —CN, —NO 2 , —NCO, —NCS, —OCN, —SCN, SF 5 or straight-chain alkyl having 1 to 25 C atoms or branched alkyl having 3 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may each be replaced, independently of one another, by —C(R 0 )═C(R 00 )—, —C≡C—, —N(R 00 )—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, where, if B 1 and/or B 2 contain a saturated C atom, R a and/or R b may also denote a radical which is spiro-linked to this saturated C atom, wherein at least one of the radicals R a and R b denotes or contains a group P or P-Sp-,
P a polymerizable group,
Sp spacer group or a single bond,
B 1 and B 2 an aromatic, heteroaromatic, alicyclic or heterocyclic group having 4 to 25 ring atoms, which may also contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L,
Z b —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —OCH 2 —, —CH 2 O—, —SCH 2 —, —CH 2 S—, —CF 2 O—, —OCF 2 —, —CF 2 S—, —SCF 2 —, —(CH 2 ) n1 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —(CF 2 ) n1 —, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR 0 R 00 or a single bond,
R 0 and R 00 H or alkyl having 1 to 12 C atoms,
m 0, 1, 2, 3 or 4,
n1 1, 2, 3 or 4,
L P, P-Sp-, OH, CH 2 OH, F, Cl, Br, I, —CN, —NO 2 , —NCO, —NCS, —OCN, —SCN, —C(═O)N(R x ) 2 , —C(═O)Y 1 , —C(═O) R x , —N(R x ) 2 , optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 3 to 25 C atoms, in which, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-,
Y 1 halogen, and
R x P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.
11 . The LC medium according claim 1 , wherein it additionally comprises one or more additives selected from the group consisting of stabilizers, chiral dopants, polymerization initiators and self alignment additives.
12 . A process of preparing an LC medium, comprising the steps of: mixing one or more polymerizable compounds selected from formula M13:
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
P 1 , P 2 an acrylate or methacrylate group,
Sp 1 , Sp 2 a single bond,
L F, Cl, CN or straight-chain, optionally mono- or polyfluorinated alkyl or alkoxy having 1 to 12 C atoms, straight-chain, optionally mono- or polyfluorinated alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 2 to 12 C atoms, or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 3 to 12 C atoms, and
r 0, 1, 2, 3 or 4,
with one or more compounds of formula IIB2
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and at least two compounds of formula IA, one or more compounds of formula IB, and at least one compound of formula IC-1 and/or IC-2
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
R 1 , R 2 straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, CR 0 ═CR 00 —, —C≡C—,
in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl,
R 0 , R 00 H or alkyl having 1 to 12 C atoms,
L 1 , L 2 F,
alkyl an alkyl radical having 1 to 7 C atoms, and
alkenyl an alkenyl radical having 2 to 5 C atoms,
wherein the proportion of compounds of formula IA of the LC medium is >8% by weight based on the total weight of compounds of formulae IA, IB, and IC present, and wherein the total proportion of compounds of formulae IC-1 and/or IC-2 in the LC medium is from 20 to 45% by weight, and
one or more compounds of formula III2-2:
in which
L 11 and L 12 each, independently of one another, denote F, Cl, CF 3 or CHF 2 ,
(O) denotes O or a single bond,
R IIIA denotes an alkyl having 1-7 C atoms, an alkenyl having 2-7 C atoms or a group Cy-C m H 2m+1 —,
m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, and
Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, wherein the cycloaliphatic group is optionally substituted with an alkyl having 1-3 carbon atoms, an alkenyl having 2-3 C atoms or with halogen or CN,
and optionally with one or more compounds of formula II, III, IV and/or V
wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
R 1 and R 2 straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, CR 0 ═CR 00 —, —C≡C—,
in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, H or alkyl having 1 to 12 C atoms,
R 0 , R 00 H or alkyl having 1 to 12 C atoms,
A1 and A2 a group selected from the following formulae
Z 1 and Z 2 —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CO—O—, —O—CO—, —C 2 F 4 —, —CF═CF—, —CH═CH—CH 2 O— or a single bond,
L 1 , L 2 , L 3 and L 4 F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F or CHF 2 ,
Y H, F, Cl, CF 3 , CHF 2 or CH 3 ,
L C CH 3 or OCH 3 ,
a1 1 or 2, and
a2 0 or 1,
in which
R 11 and R 12 each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH 2 groups in these radicals may each be replaced, independently of one another, by
—C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, by —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,
A 3 on each occurrence, independently of one another, denotes
a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH 2 groups may be replaced by —O— or —S—,
b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or
c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, denotes 0, 1 or 2,
n denotes 0, 1 or 2,
Z 1 on each occurrence independently of one another denotes-CO—O—, —O—CO—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CH 2 —, —CH 2 CH 2 —, —(CH 2 ) 4 —, —CH═CH—CH 2 O—, —C 2 F 4 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—, —C≡C— or a single bond, and
L 11 and L 12 each, independently of one another, denote F, Cl, CF 3 or CHF 2 , and
W denotes O or S, and if n is 0 then Wis not S, wherein the one or more compounds of formula III2-2 are excluded from the one or more compounds of formula III,
in which
R 41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, and
R 42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms,
in which
R 51 and R 52 independently of one another, have one of the meanings given for R 41 and R 42 ,
identically or differently, denote
Z 51 , Z 52 each, independently of one another, denote —CH 2 —CH 2 —, —CH 2 —O—, —CH═CH—, —C≡C—, —COO— or a single bond, and
n is 1 or 2,
optionally with further liquid-crystalline compounds and/or additives, and optionally polymerizing the polymerizable compounds.
13 . An LC display comprising the LC medium as claimed in claim 1 .
14 . The LC display of claim 13 , which is a PSA or SA display.
15 . The LC display of claim 14 , which is a PS-VA, PS-IPS, PS-FFS or SA-VA display.
16 . The LC display of claim 14 , wherein it comprises two substrates, at least one of which is transparent to light, an electrode provided on each substrate or two electrodes provided on only one of the substrates, and located between the substrates a layer of the LC medium, wherein the polymerizable compounds are polymerized between the substrates of the display by UV photopolymerization.
17 . A process for the production of an LC display comprising two substrates, at least one of which is transparent to light, an electrode provided on each substrate or two electrodes provided on only one of the substrates, and located between the substrates a layer of an LC medium, the process comprising the steps of providing the LC medium of claim 1 between the substrates of the display, and polymerizing the polymerizable compounds by irradiation with UV light.
18 . The process according to claim 17 , wherein the UV light has a wavelength in the range from 340 to 380 nm.
19 . The process according to claim 17 , wherein irradiation with UV light is carried out using an UV-LED lamp.
20 . The LC medium according to claim 1 , wherein the one or more compounds of formula III2-2 are selected from the group consisting of formulae III2-2-1 to III2-2-3:
in which alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms.