Liquid-crystal medium
11299673 · 2022-04-12
Assignee
Inventors
- Ji-Won JEONG (Gyeonggi-do, KR)
- Eun-Kyu LEE (Gyeonggi-do, KR)
- Hyun-Jin Yoon (Gyeonggi-do, KR)
- Min-Ok JIN (Gyeonggi-do, KR)
- Yong-Kuk Yun (Gyeonggi-do, KR)
Cpc classification
C09K2019/3027
CHEMISTRY; METALLURGY
C09K2019/3425
CHEMISTRY; METALLURGY
C09K2019/0411
CHEMISTRY; METALLURGY
C09K19/322
CHEMISTRY; METALLURGY
C09K2019/0448
CHEMISTRY; METALLURGY
C09K19/32
CHEMISTRY; METALLURGY
C09K19/44
CHEMISTRY; METALLURGY
C09K2019/121
CHEMISTRY; METALLURGY
C09K19/3447
CHEMISTRY; METALLURGY
C09K19/3444
CHEMISTRY; METALLURGY
C09K19/12
CHEMISTRY; METALLURGY
C09K19/0403
CHEMISTRY; METALLURGY
International classification
C09K19/32
CHEMISTRY; METALLURGY
C09K19/04
CHEMISTRY; METALLURGY
C09K19/44
CHEMISTRY; METALLURGY
Abstract
A liquid crystal (LC) medium comprising a polymerizable compound, a process for its preparation, its use for optical, electro-optical and electronic purposes, such as LC displays, including LC displays of the polymer sustained alignment (PSA) type, and LC displays, including PSA displays, comprising the LC medium.
Claims
1. A LC display, which is a PS-VA, PS-IPS or PS-UB-FFS display, which comprises a first substrate and second substrate, at least one which is transparent to light, an electrode provided on each of the first and second substrates or two electrodes provided on only one of the first and second substrates, a first and/or second alignment layer of polyimide, the first alignment layer positioned on the first substrate and the second alignment layer positioned on the second substrate and a layer of a liquid crystal (LC) medium located between the first and second substrates adjacent the first and/or second alignment layer the liquid crystal (LC) medium comprising one or more polymerizable compounds which are polymerized, one or more compounds of formula B in a proportion of from 3 to 20%, and one or more compounds of formula Q in an amount sufficient to reduce the VHR drop following polymerization of the polymerizable compounds by at least 35%, in a proportion from 0.1 to 1.0%, ##STR00443## in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.1, R.sup.2, R.sup.Q are alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.Q is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L.sup.1, L.sup.2 are F or Cl, L.sup.Q1-L.sup.Q6 are H, F or Cl, with at least one of L.sup.Q1 to L.sup.Q6 being F or Cl.
2. A The LC display according to claim 1, wherein the LC medium comprises a polymerizable component A) comprising one or more polymerizable compounds, and a liquid-crystalline component B) comprising one or more mesogenic or liquid-crystalline compounds, wherein component B) comprises one or more compounds of formula B and one or more compounds of formula Q as defined in claim 1.
3. The LC display according to claim 1, wherein the compounds of formula B are selected from the following formula: ##STR00444## wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond.
4. The LC display according to claim 1, wherein the proportion of compounds of formula B in the LC medium is 4 to 15%.
5. The LC display according to claim 1, wherein the compounds of formula Q are selected from the following formulae: ##STR00445## wherein R.sup.Q has the meanings of claim 1.
6. The LC display according to claim 1, wherein the proportion of compounds of formula Q in the LC medium is from 0.1 up to 0.5%.
7. The LC display according to claim 1, wherein the polymerizable compounds are selected of formula I
R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b I in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.a and R.sup.b P, P-Sp-, H, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, SF.sub.5 or straight-chain or branched alkyl having 1 to 25 C atoms, wherein the branched hydrocarbon radicals have at least three C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.0)═C(R.sup.00)—C≡C—, —N(R.sup.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.sup.1 and/or B.sup.2 contain a saturated C atom, R.sup.a and/or R.sup.b may also denote a radical which is spiro-linked to this saturated C atom, wherein at least one of the radicals R.sup.a and R.sup.b denotes or contains a group P or P-Sp-, P a polymerizable group, Sp a spacer group or a single bond, B.sup.1 and B.sup.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.sup.b —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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.2).sub.n1—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.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.sub.2OH, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.x).sub.2, —C(═O)Y.sup.1, —C(═O).sup.Rx, —N(R.sup.x).sub.2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain alkyl or alkoxy having 1 to 25 C atoms, or straight-chain alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 2 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.sup.1 halogen, R.sup.x P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein branched or cyclic alkyl radicals have at least three C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that 0 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, wherein the branched hydrocarbon radicals have at least three C atoms.
8. The LC display according to claim 1, wherein the polymerizable compounds are selected from the following formulae: ##STR00446## ##STR00447## ##STR00448## ##STR00449## ##STR00450## in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: P.sup.1, P.sup.2, P.sup.3 a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane or epoxy group, Sp.sup.1, Sp.sup.2, Sp.sup.3 a single bond or a spacer group where, in addition, one or more of the radicals P.sup.1-Sp.sup.1-, P.sup.2-Sp.sup.2- and P.sup.3-Sp.sup.3- may also denote R.sup.aa, with the proviso that at least one of the radicals P.sup.1-Sp.sup.1-, P.sup.2-Sp.sup.2- and P.sup.3-Sp.sup.3- present is different from R.sup.aa, R.sup.aa H, F, Cl, CN 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.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —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, CN or P.sup.1—Sp.sup.1-, R.sup.0, R.sup.00 H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z H, F, CH.sub.3 or CF.sub.3, X.sup.1, X.sup.2, X.sup.3 —CO—O—, —O—CO— or a single bond, Z.sup.1 —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2, Z.sup.3 —CO—O—, —O—CO—, —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, L F, Cl, CN or straight-chain, optionally mono- or polyfluorinated, alkyl or alkoxy having 1 to 12 C atoms, or 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, L′, L″ H, F or Cl, r 0, 1, 2, 3 or 4, s 0, 1, 2 or 3, t 0, 1 or 2, x 0 or 1.
9. The LC display according to claim 1, wherein the LC medium comprises one or more compounds selected from the formulae AN and AY: ##STR00451## in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: ##STR00452## is ##STR00453## ##STR00454## is ##STR00455## ##STR00456## is ##STR00457## R.sup.A1 alkenyl having 2 to 9 C atoms or, if at least one of the rings X, Y and Z denotes cyclohexenyl, also one of the meanings of R.sup.A2, R.sup.A2 alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that 0 atoms are not linked directly to one another, Z.sup.x —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O—, or a single bond, L.sup.1-4 H, F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, x 1 or 2, z 0 or 1.
10. The LC display according to claim 1, wherein the LC medium comprises one or more compounds selected from the formulae CY and PY: ##STR00458## in which the individual radicals have the following meanings: a denotes 1 or 2, b denotes 0 or 1, ##STR00459## denotes ##STR00460## R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that 0 atoms are not linked directly to one another, Z.sup.x denotes —CH═CH—, —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, L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2.
11. The LC display according to claim 1, wherein the LC medium comprises one or more compounds selected from formulae ZK and DK: ##STR00461## in which the individual radicals on each occurrence, identically or differently, have the following meanings: ##STR00462## denotes ##STR00463## ##STR00464## denotes ##STR00465## ##STR00466## denotes ##STR00467## and R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that 0 atoms are not linked directly to one another, Z.sup.y denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —COO—, —OCO—, —C.sub.2F.sub.4—, —CF═CF— or a single bond, R.sup.5 and R.sup.6 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that 0 atoms are not linked directly to one another, e denotes 1 or 2.
12. A process for the production of the LC display according to claim 1, comprising the steps of providing components of a liquid crystal (LC) medium between the first and second substrates of the display, and polymerising the polymerizable compounds therein, wherein the components of the liquid crystal (LC) medium comprises one or more polymerizable compounds, one or more compounds of formula B, and one or more compounds of formula Q ##STR00468## in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.1, R.sup.2, R.sup.Q are alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.Q is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L.sup.1, L.sup.2 are F or Cl, L.sup.Q1-L.sup.Q6 are H, F or Cl, with at least one of L.sup.Q1 to L.sup.Q6 being F or Cl.
13. A process of preparing an LC medium of the LC display according to claim 1, comprising the steps of mixing one or more compounds of formula B defined below with one or more compounds of formula Q defined below and one or more polymerizable compounds of formula I defined below, and optionally with further LC compounds and/or additives, ##STR00469##
R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b 1 in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.1, R.sup.2, R.sup.Q are alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.Q is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L.sup.1, L.sup.2 are F or Cl, L.sup.Q1-L.sup.Q6 are H, F or Cl, with at least one of L.sup.Q1 to L.sup.Q6 being F or Cl; R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b I R.sup.a and R.sup.b P, P-Sp-, H, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, SF.sub.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.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.0)═C(R.sup.00)—,—C≡C—, —N(R.sup.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.sup.1 and/or B.sup.2 contain a saturated C atom, R.sup.a and/or R.sup.b may also denote a radical which is Spiro-linked to this saturated C atom, wherein at least one of the radicals R.sup.a and R.sup.b denotes or contains a group P or P-Sp-, P a polymerizable group, Sp a spacer group or a single bond, B.sup.1 and B.sup.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.sup.b —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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.2).sub.n1, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.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.sub.2OH, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.x).sub.2, —C(═O)Y′, —C(═O)R.sup.x, —N(R.sup.x).sub.2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain alkyl or alkoxy having 1 to 25 C atoms, or straight-chain alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 2 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.sup.1 halogen, R.sup.x P, P-Sp-, H, halogen, straight-chain alkyl having 1 to 25 C atoms, or branched or cyclic alkyl having 3 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.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.
14. The LC display according to claim 8 wherein R.sup.aa is H, F, Cl, CN or straight-chain, optionally mono- or polyfluorinated alkyl or alkoxy having 1 to 12 C atoms, or 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.
15. The LC display according to claim 11 wherein R.sup.5 and R.sup.6 each, independently of one another, denote alkyl or alkoxy having 1 to 6 C atoms.
Description
DETAILED DESCRIPTION OF THE INVENTION
(1) Unless stated otherwise, the polymerizable compounds are preferably selected from achiral compounds.
(2) As used herein, the terms “active layer” and “switchable layer” mean a layer in an electrooptical display, for example an LC display, that comprises one or more molecules having structural and optical anisotropy, like for example LC molecules, which change their orientation upon an external stimulus like an electric or magnetic field, resulting in a change of the transmission of the layer for polarized or unpolarized light.
(3) As used herein, the terms “tilt” and “tilt angle” will be understood to mean a tilted alignment of the LC molecules of an LC medium relative to the surfaces of the cell in an LC display (here preferably a PSA display). The tilt angle here denotes the average angle (<90°) between the longitudinal molecular axes of the LC molecules (LC director) and the surface of the plane-parallel outer plates which form the LC cell. A low value for the tilt angle (i.e. a large deviation from the 90° angle) corresponds to a large tilt here. A suitable method for measurement of the tilt angle is given in the examples. Unless indicated otherwise, tilt angle values disclosed above and below relate to this measurement method.
(4) As used herein, the terms “reactive mesogen” and “RM” will be understood to mean a compound containing a mesogenic or liquid crystalline skeleton, and one or more functional groups attached thereto which are suitable for polymerization and are also referred to as “polymerizable group” or “P”.
(5) Unless stated otherwise, the term “polymerizable compound” as used herein will be understood to mean a polymerizable monomeric compound.
(6) As used herein, the term “low-molecular-weight compound” will be understood to mean to a compound that is monomeric and/or is not prepared by a polymerization reaction, as opposed to a “polymeric compound” or a “polymer”.
(7) As used herein, the term “unpolymerizable compound” will be understood to mean a compound that does not contain a functional group that is suitable for polymerization under the conditions usually applied for the polymerisation of the RMs.
(8) The term “mesogenic group” as used herein is known to the person skilled in the art and described in the literature, and means a group which, due to the anisotropy of its attracting and repelling interactions, essentially contributes to causing a liquid-crystal (LC) phase in low-molecular-weight or polymeric substances. Compounds containing mesogenic groups (mesogenic compounds) do not necessarily have to have an LC phase themselves. It is also possible for mesogenic compounds to exhibit LC phase behavior only after mixing with other compounds and/or after polymerization. Typical mesogenic groups are, for example, rigid rod- or disc-shaped units. An overview of the terms and definitions used in connection with mesogenic or LC compounds is given in Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.
(9) The term “spacer group”, hereinafter also referred to as “Sp”, as used herein is known to the person skilled in the art and is described in the literature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. As used herein, the terms “spacer group” or “spacer” mean a flexible group, for example an alkylene group, which connects the mesogenic group and the polymerizable group(s) in a polymerizable mesogenic compound.
(10) Above and below,
(11) ##STR00002##
(12) denote a trans-1,4-cyclohexylene ring, and
(13) ##STR00003##
(14) denote a 1,4-phenylene ring.
(15) Above and below “organic group” denotes a carbon or hydrocarbon group.
(16) “Carbon group” denotes a mono- or polyvalent organic group containing at least one carbon atom, where this either contains no further atoms (such as, for example, —C≡C—) or optionally contains one or more further atoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge (for example carbonyl, etc.). The term “hydrocarbon group” denotes a carbon group which additionally contains one or more H atoms and optionally one or more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge.
(17) “Halogen” denotes F, Cl, Br or I.
(18) —CO—, —C(═O)— and —C(O)— denote a carbonyl group, i.e.
(19) ##STR00004##
(20) A carbon or hydrocarbon group can be a saturated or unsaturated group. Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. A carbon or hydrocarbon radical having more than 3 C atoms can be straight-chain, branched and/or cyclic and may also contain spiro links or condensed rings.
(21) The terms “alkyl”, “aryl”, “heteroaryl”, etc., also encompass polyvalent groups, for example alkylene, arylene, heteroarylene, etc.
(22) The term “aryl” denotes an aromatic carbon group or a group derived therefrom. The term “heteroaryl” denotes “aryl” as defined above, containing one or more heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.
(23) Preferred carbon and hydrocarbon groups are optionally substituted, straight-chain, branched or cyclic, alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy having 1 to 40, preferably 1 to 20, very preferably 1 to 12, C atoms, optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to 25, C atoms, or optionally substituted alkylaryl, arylalkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to 25, C atoms, wherein one or more C atoms may also be replaced by hetero atoms, preferably selected from N, O, S, Se, Te, Si and Ge.
(24) Further preferred carbon and hydrocarbon groups are C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.2-C.sub.20 alkynyl, C.sub.3-C.sub.20 allyl, C.sub.4-C.sub.20 alkyldienyl, C.sub.4-C.sub.20 polyenyl, C.sub.6-C.sub.20 cycloalkyl, C.sub.4-C.sub.15 cycloalkenyl, C.sub.6-C.sub.30 aryl, C.sub.6-C.sub.30 alkylaryl, C.sub.6-C.sub.30 arylalkyl, C.sub.6-C.sub.30 alkylaryloxy, C.sub.6-C.sub.30 arylalkyloxy, C.sub.2-C.sub.30 heteroaryl, C.sub.2-C.sub.30 heteroaryloxy.
(25) Particular preference is given to C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl, C.sub.6-C.sub.25 aryl and C.sub.2-C.sub.25 heteroaryl.
(26) Further preferred carbon and hydrocarbon groups are straight-chain, branched or cyclic alkyl having 1 to 20, preferably 1 to 12, C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN and in which one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.x)═C(R.sup.x)—, —C≡C—, —N(R.sup.x)—, —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.
(27) R.sup.x preferably denotes H, F, Cl, CN, a straight-chain, branched or cyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one or more non-adjacent C atoms may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— and in which one or more H atoms may be replaced by F or Cl, or denotes an optionally substituted aryl or aryloxy group with 6 to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group with 2 to 30 C atoms.
(28) Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.
(29) Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, etc.
(30) Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, etc.
(31) Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxy-ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.
(32) Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, etc.
(33) Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e. they can contain one ring (such as, for example, phenyl) or two or more rings, which may also be fused (such as, for example, naphthyl) or covalently bonded (such as, for example, biphenyl), or contain a combination of fused and linked rings. Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se.
(34) Particular preference is given to mono-, bi- or tricyclic aryl groups having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groups having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Preference is furthermore given to 5-, 6- or 7-membered aryl and heteroaryl groups, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that O atoms and/or S atoms are not linked directly to one another.
(35) Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1′:3′,1″]terphenyl-2′-yl, naphthyl, anthracene, binaphthyl, phenanthrene, 9,10-dihydro-phenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, etc.
(36) Preferred heteroaryl groups are, for example, 5-membered rings, such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene, or combinations of these groups.
(37) The aryl and heteroaryl groups mentioned above and below may also be substituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or further aryl or heteroaryl groups.
(38) The (non-aromatic) alicyclic and heterocyclic groups encompass both saturated rings, i.e. those containing exclusively single bonds, and also partially unsaturated rings, i.e. those which may also contain multiple bonds.
(39) Heterocyclic rings contain one or more heteroatoms, preferably selected from Si, O, N, S and Se.
(40) The (non-aromatic) alicyclic and heterocyclic groups can be monocyclic, i.e. contain only one ring (such as, for example, cyclohexane), or polycyclic, i.e. contain a plurality of rings (such as, for example, decahydronaphthalene or bicyclooctane). Particular preference is given to saturated groups. Preference is furthermore given to mono-, bi- or tricyclic groups having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Preference is furthermore given to 5-, 6-, 7- or 8-membered carbocyclic groups, in which, in addition, one or more C atoms may be replaced by Si and/or one or more CH groups may be replaced by N and/or one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S—.
(41) Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups, such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine, 6-membered groups, such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, 7-membered groups, such as cycloheptane, and fused groups, such as tetrahydronaphthalene, decahydronaphthalene, indane, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindane-2,5-diyl.
(42) Preferred substituents are, for example, solubility-promoting groups, such as alkyl or alkoxy, electron-withdrawing groups, such as fluorine, nitro or nitrile, or substituents for increasing the glass transition temperature (Tg) in the polymer, in particular bulky groups, such as, for example, t-butyl or optionally substituted aryl groups.
(43) Preferred substituents, hereinafter also referred to as “L”, are F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.x).sub.2, —C(═O)Y.sup.1, —C(═O)R.sup.x, —N(R.sup.x).sub.2, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more H atoms may optionally be replaced by F or Cl, optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15, C atoms,
(44) wherein R.sup.x denotes H, F, Cl, CN, or straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— 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, Cl, P— or P-Sp-, and
(45) Y.sup.1 denotes halogen.
(46) “Substituted silyl or aryl” preferably means substituted by halogen, —CN, R.sup.0, —OR.sup.0, —CO—R.sup.0, —CO—O—R.sup.0, —O—CO—R.sup.0 or —O—CO—O—R.sup.0, wherein R.sup.0 denotes H or alkyl with 1 to 20 C atoms.
(47) Particularly preferred substituents L are, for example, F, Cl, CN, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5, furthermore phenyl.
(48) ##STR00005##
is preferably
(49) ##STR00006##
(50) in which L has one of the meanings indicated above.
(51) The polymerizable group P is a group which is suitable for a polymerization reaction, such as, for example, free-radical or ionic chain polymerisation, polyaddition or polycondensation, or for a polymer-analogous reaction, for example addition or condensation onto a main polymer chain. Particular preference is given to groups for chain polymerization, in particular those containing a C═C double bond or —C≡C— triple bond, and groups which are suitable for polymerization with ring opening, such as, for example, oxetane or epoxide groups.
(52) Preferred groups P are selected from the group consisting of CH.sub.2═CW.sup.1—CO—O—, CH.sub.2═CW.sup.1—CO—,
(53) ##STR00007##
CH.sub.2═CW.sup.2—(O).sub.k3—, CW.sup.1═CH—CO—(O).sub.k3—, CW.sup.1═CH—CO—NH—, CH.sub.2═CW.sup.1—CO—NH—, CH.sub.3—CH═CH—O—, (CH.sub.2═CH).sub.2CH—OCO—, (CH.sub.2═CH—CH.sub.2).sub.2CH—OCO—, (CH.sub.2═CH).sub.2CH—O—, (CH.sub.2═CH—CH.sub.2).sub.2N—, (CH.sub.2═CH—CH.sub.2).sub.2N—CO—, HO—CW.sup.2W.sup.3—, HS—CW.sup.2W.sup.3—, HW.sup.2N—, HO—CW.sup.2W.sup.3—NH—, CH.sub.2═CW.sup.1—CO—NH—, CH.sub.2═CH—(COO).sub.k1-Phe-(O).sub.k2—, CH.sub.2═CH—(CO).sub.k1-Phe-(O).sub.k2—, Phe-CH═CH—, HOOC—, OCN— and W.sup.4W.sup.5W.sup.6Si—, in which W.sup.1 denotes H, F, Cl, CN, CF.sub.3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH.sub.3, W.sup.2 and W.sup.3 each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W.sup.4, W.sup.5 and W.sup.6 each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W.sup.7 and W.sup.8 each, independently of one another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, which is optionally substituted by one or more radicals L as defined above which are other than P-Sp-, k.sub.1, k.sub.2 and k.sub.3 each, independently of one another, denote 0 or 1, k.sub.3 preferably denotes 1, and k.sub.4 denotes an integer from 1 to 10.
(54) Very preferred groups P are selected from the group consisting of CH.sub.2═CW.sup.1—CO—O—, CH.sub.2═CW.sup.1—CO—,
(55) ##STR00008##
CH.sub.2═CW.sup.2—O—, CH.sub.2═CW.sup.2—, CW.sup.1═CH—CO—(O).sub.k3—, CW.sup.1═CH—CO—NH—, CH.sub.2═CW.sup.1—CO—NH—, (CH.sub.2═CH).sub.2CH—OCO—, (CH.sub.2═CH—CH.sub.2).sub.2CH—OCO—, (CH.sub.2═CH).sub.2CH—O—, (CH.sub.2═CH—CH.sub.2).sub.2N—, (CH.sub.2═CH—CH.sub.2).sub.2N—CO—, CH.sub.2═CW.sup.1—CO—NH—, CH.sub.2═CH—(COO).sub.k1-Phe-(O).sub.k2—, CH.sub.2═CH—(CO).sub.k1-Phe-(O).sub.k2—, Phe-CH═CH— and W.sup.4W.sup.5W.sup.6Si—, in which W.sup.1 denotes H, F, Cl, CN, CF.sub.3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH.sub.3, W.sup.2 and W.sup.3 each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W.sup.4, W.sup.5 and W.sup.6 each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W.sup.7 and W.sup.8 each, independently of one another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, k.sub.1, k.sub.2 and k.sub.3 each, independently of one another, denote 0 or 1, k.sub.3 preferably denotes 1, and k.sub.4 denotes an integer from 1 to 10.
(56) Very particularly preferred groups P are selected from the group consisting of CH.sub.2═CW.sup.1—CO—O—, in particular CH.sub.2═CH—CO—O—, CH.sub.2═C(CH.sub.3)—CO—O— and CH.sub.2═CF—CO—O—, furthermore CH.sub.2═CH—O—, (CH.sub.2═CH).sub.2CH—O—CO—, (CH.sub.2═CH).sub.2CH—O—,
(57) ##STR00009##
(58) Further preferred polymerizable groups P are selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.
(59) If Sp is different from a single bond, it is preferably of the formula Sp″-X″, so that the respective radical P-Sp- conforms to the formula P-Sp″-X″—, wherein Sp″ denotes alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN and in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —O—, —S—, —NH—, —N(R.sup.0)—, —Si(R.sup.0R.sup.00)—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —N(R.sup.00)—CO—O—, —O—CO—N(R.sup.0)—, —N(R.sup.0)—CO—N(R.sup.00)—, —CH═CH— or —C≡C— in such a way that O and/or S atoms are not linked directly to one another, X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—N(R.sup.0)—, —N(R.sup.0)—CO—, —N(R.sup.0)—CO—N(R.sup.00)—, —OCH.sub.2—, —CH.sub.2O—, —SCH.sub.2—, —CH.sub.2S—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —CF.sub.2CF.sub.2—, —CH═N—, —N═CH—, —N═N—, —CH═CR.sup.0—, —CY.sup.2═CY.sup.3—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH— or a single bond, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 20 C atoms, and Y.sup.2 and Y.sup.3 each, independently of one another, denote H, F, Cl or CN. X″ is preferably —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR.sup.0—, —NR.sup.0—CO—, —NR.sup.0—CO—NR.sup.00— or a single bond.
(60) Typical spacer groups Sp and -Sp″-X″— are, for example, —(CH.sub.2).sub.p1—, —(CH.sub.2CH.sub.2O).sub.q1—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—S—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—NH—CH.sub.2CH.sub.2— or —(SiR.sup.0R.sup.00—O).sub.p1—, in which p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R.sup.0 and R.sup.00 have the meanings indicated above.
(61) Particularly preferred groups Sp and -Sp″-X″— are —(CH.sub.2).sub.p1—, —(CH.sub.2).sub.p1—O—, —(CH.sub.2).sub.p1—O—CO—, —(CH.sub.2).sub.p1—CO—O—, and —(CH.sub.2).sub.p1—O—CO—O—, in which p1 and q1 have the meanings indicated above.
(62) Particularly preferred groups Sp″ are, in each case straight-chain, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.
(63) The compounds of formula B are preferably selected of formula B1
(64) ##STR00010##
(65) wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Very preferred are compounds of formula B1 wherein both groups (O) denote an oxygen atom and alkyl is methyl, ethyl, propyl, butyl, pentyl or hexyl, which are preferably straight-chained.
(66) Preferably the proportion of compounds of formula B or B1 in the LC medium, preferably in component B) of the LC medium, is from 0.5 to 20%, very preferably from 1 to 15%, most preferably from 1 to 10%.
(67) In another preferred embodiment of the present invention the proportion of compounds of formula B or B1 in the LC medium, preferably in component B) of the LC medium, is ≥3%, more preferably ≥4%. In another preferred embodiment of the present invention the proportion of compounds of formula B or B1 in the LC medium, preferably in component B) of the LC medium, is ≤20%, more preferably ≤15%. Very preferably the proportion of compounds of formula B or B1 in the LC medium, preferably in component B) of the LC medium, is from 3 to 20%, most preferably from 4 to 15%.
(68) Preferably the LC medium contains 1 to 5, preferably 1, 2 or 3 compounds of formula B or B1.
(69) Preferred compounds of formula Q, Q1 and Q2 are those wherein L.sup.Q3 and L.sup.Q4 are F. Further preferred compounds of formula Q, Q1 and Q2 are those wherein L.sup.Q3, L.sup.Q4 and one or two of L.sup.Q1 and L.sup.Q2 are F.
(70) Further preferred compounds of formula Q are those wherein X.sup.Q denotes F or OCF.sub.3, very preferably F.
(71) The compounds of formula Q are preferably selected from the following subformulae
(72) ##STR00011##
(73) wherein R.sup.Q has one of the meanings of formula Q or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl.
(74) Preferred compounds of formula Q, Q1 and Q2 are those wherein R.sup.Q denotes straight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl, n-propyl or n-butyl.
(75) Especially preferred are compounds of formula Q1, in particular those wherein R.sup.Q is n-propyl.
(76) Preferably the proportion of compounds of formula Q in the LC medium, preferably in component B) of the LC medium, is from >0 to ≤5%, very preferably from 0.05 to 2%, most preferably from 0.1 to 1%.
(77) Preferably the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula Q.
(78) In the LC medium according to the present invention, the use of an LC host mixture comprising compounds of formula B and Q together with the use of a polymerizable component comprising preferably direactive and/or trireactive RMs, leads to advantageous properties in PSA displays. In particular, one or more of the following advantages could be achieved: good UV absorption also at longer wavelengths, quick and complete polymerisation of the RMs, quick generation of a low pretilt angle, especially already at low UV energy and/or at longer UV wavelengths, high UV absorption, increased UV stability, high pretilt angle stability after UV exposure, reduced image sticking, reduced ODF mura, high reliability and high VHR value after UV exposure and/or heat treatment, high birefringence, reduced viscosity faster response times.
(79) It was surprisingly found that especially in LC media according to the present invention containing a higher amount of compounds of formula B, preferably at least 3% or even 4%, the VHR can be more significantly improved, e.g. the VHR can be maintained at high level even after polymerization of the polymerizable compound, by adding a compound of formula Q. Since the addition of a higher amount of compounds of formula B leads to a more significantly improvement (i.e. reduction) of the viscosity, the addition of both a compound of formula B and a compound of formula Q allows to combine the advantages of high VHR and reduced viscosity.
(80) Moreover, the LC medium according to the present invention shows high absorption at longer UV wavelengths, and thus enables using longer UV wavelengths for polymerization, which is advantageous for the display manufacturing process.
(81) The polymerizable compounds are preferably selected from formula I
R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b I
(82) in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.a and R.sup.b P, P-Sp-, H, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, SF.sub.5 or straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.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.sup.1 and/or B.sup.2 contain a saturated C atom, R.sup.a and/or R.sup.b may also denote a radical which is spiro-linked to this saturated C atom, wherein at least one of the radicals R.sup.a and R.sup.b denotes or contains a group P or P-Sp-, P a polymerizable group, Sp a spacer group or a single bond, B.sup.1 and B.sup.2 an aromatic, heteroaromatic, alicyclic or heterocyclic group, preferably having 4 to 25 ring atoms, which may also contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L, Z.sup.b —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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.2).sub.n1—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, m denotes 0, 1, 2, 3 or 4, n1 denotes 1, 2, 3 or 4, L P, P-Sp-, OH, CH.sub.2OH, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.x).sub.2, —C(═O)Y.sup.1, —C(═O)R.sup.x, —N(R.sup.x).sub.2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxy-carbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, P and Sp have the meanings indicated above, Y.sup.1 denotes halogen, R.sup.x denotes 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.sub.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 hetero-aryloxy group having 2 to 40 C atoms.
(83) Particularly preferred compounds of the formula I are those in which B.sup.1 and B.sup.2 each, independently of one another, denote 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarine, flavone, where, in addition, one or more CH groups in these groups may be replaced by N, cyclohexane-1,4-diyl, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, bicycle[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, where all these groups may be unsubstituted or mono- or polysubstituted by L as defined above.
(84) Particularly preferred compounds of the formula I are those in which B.sup.1 and B.sup.2 each, independently of one another, denote 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.
(85) Very preferred compounds of formula I are selected from the following formulae:
(86) ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016##
(87) in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: P.sup.1, P.sup.2, P.sup.3 a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloro-acrylate, oxetane or epoxy group, Sp.sup.1, Sp.sup.2, Sp.sup.3 a single bond or a spacer group where, in addition, one or more of the radicals P.sup.1-Sp.sup.1-, P.sup.2-Sp.sup.2- and P.sup.3-Sp.sup.3- may denote R.sup.aa, with the proviso that at least one of the radicals P.sup.1-Sp.sup.1-, P.sup.2-Sp.sup.2 and P.sup.3-Sp.sup.3- present is different from R.sup.aa,
(88) R.sup.aa H, F, Cl, CN or straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —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, CN or P.sup.1-Sp.sup.1-, particularly preferably straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms (where the alkenyl and alkynyl radicals have at least two C atoms and the branched radicals have at least three C atoms), R.sup.0, R.sup.00 H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z H, F, CH.sub.3 or CF.sub.3, X.sup.1, X.sup.2, X.sup.3 —CO—O—, —O—CO— or a single bond, Z.sup.1 —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2, Z.sup.3 —CO—O—, —O—CO—, —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, L F, Cl, CN or straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, L′, L″ H, F or Cl, r 0, 1, 2, 3 or 4, s 0, 1, 2 or 3, t 0, 1 or 2, x 0 or 1.
(89) Very preferred are compounds of formulae M2 and M13, especially direactive compounds containing exactly two polymerizable groups P.sup.1 and P.sup.2.
(90) Further preferred are compounds M15 to M31, in particular M17, M18, M19, M22, M23, M24, M25, M26, M30 and M31, especially trireactive compounds containing exactly three polymerizable groups P.sup.1, P.sup.2 and/or P.sup.3.
(91) In the compounds of formulae M1 to M31 the group
(92) ##STR00017##
is preferably
(93) ##STR00018##
(94) wherein L on each occurrence, identically or differently, has one of the meanings given above or below, and is preferably F, Cl, CN, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, C(CH.sub.3).sub.3, CH(CH.sub.3).sub.2, CH.sub.2CH(CH.sub.3)C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5 or P-Sp-, very preferably F, Cl, CN, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, COCH.sub.3, OCF.sub.3 or P-Sp-, more preferably F, Cl, CH.sub.3, OCH.sub.3, COCH.sub.3 or OCF.sub.3, especially F or CH.sub.3.
(95) Preferred compounds of formulae M1 to M30 are those wherein P.sup.1, P.sup.2 and P.sup.3 denote an acrylate, methacrylate, oxetane or epoxy group, very preferably an acrylate or methacrylate group.
(96) Further preferred compounds of formulae M1 to M31 are those wherein Sp.sup.1, Sp.sup.2 and Sp.sup.3 are a single bond.
(97) Further preferred compounds of formulae M1 to M31 are those wherein one of Sp.sup.1, Sp.sup.2 and Sp.sup.3 is a single bond and another one of Sp.sup.1, Sp.sup.2 and Sp.sup.3 is different from a single bond.
(98) Further preferred compounds of formulae M1 to M31 are those wherein those groups Sp.sup.1, Sp.sup.2 and Sp.sup.3 that are different from a single bond denote —(CH.sub.2).sub.s1—X″—, wherein s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X″ is the linkage to the benzene ring and is —O—, —O—CO—, —CO—O, —O—CO—O— or a single bond.
(99) Particular preference is given to LC media comprising one, two or three polymerizable compounds of formula I.
(100) Preferably the proportion of compounds of formula I in the LC medium is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.
(101) It was observed that, the combination of polymerizable compounds of formulae M1 to M31 with the compounds of formula B and Q leads to advantageous behavior of the LC medium, where a quick and complete polymerization, the quick generation of a low pretilt angle which is stable after UV exposure, at the same time a high reliability and high VHR value after UV exposure can be achieved together with a high birefringence. Besides, the LC medium shows high absorption at longer UV wavelengths, so that it is possible to use such longer UV wavelengths for polymerization, which is advantageous for the display manufacturing process.
(102) For the production of PSA displays, the polymerizable compounds contained in the LC medium are polymerized or crosslinked (if one compound contains two or more polymerizable groups) by in-situ polymerisation in the LC medium between the substrates of the LC display, optionally while a voltage is applied to the electrodes.
(103) The structure of the PSA displays according to the invention corresponds to the usual geometry for PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, in particular those in which, in addition, the electrode on the colour filter side is unstructured and only the electrode on the TFT side has slots. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006/0066793 A1.
(104) A preferred PSA type LC display of the present invention comprises: a first substrate including a pixel electrode defining pixel areas, the pixel electrode being connected to a switching element disposed in each pixel area and optionally including a micro-slit pattern, and optionally a first alignment layer disposed on the pixel electrode, a second substrate including a common electrode layer, which may be disposed on the entire portion of the second substrate facing the first substrate, and optionally a second alignment layer, an LC layer disposed between the first and second substrates and including an LC medium comprising a polymerizable component A and a liquid crystal component B as described above and below, wherein the polymerizable component A may also be polymerized.
(105) The first and/or second alignment layer controls the alignment direction of the LC molecules of the LC layer. For example, in PS-VA displays the alignment layer is selected such that it imparts to the LC molecules homeotropic (or vertical) alignment (i.e. perpendicular to the surface) or tilted alignment. Such an alignment layer may for example comprise a polyimide, which may also be rubbed, or may be prepared by a photoalignment method.
(106) The LC layer with the LC medium can be deposited between the substrates of the display by methods that are conventionally used by display manufacturers, for example the so-called one-drop-filling (ODF) method. The polymerizable component of the LC medium is then polymerized for example by UV photopolymerization. The polymerization can be carried out in one step or in two or more steps.
(107) The PSA display may comprise further elements, like a color filter, a black matrix, a passivation layer, optical retardation layers, transistor elements for addressing the individual pixels, etc., all of which are well known to the person skilled in the art and can be employed without inventive skill.
(108) The electrode structure can be designed by the skilled person depending on the individual display type. For example for PS-VA displays a multi-domain orientation of the LC molecules can be induced by providing electrodes having slits and/or bumps or protrusions in order to create two, four or more different tilt alignment directions.
(109) Upon polymerisation the polymerizable compounds form a crosslinked polymer, which causes a certain pretilt of the LC molecules in the LC medium. Without wishing to be bound to a specific theory, it is believed that at least a part of the crosslinked polymer, which is formed by the polymerizable compounds, will phase-separate or precipitate from the LC medium and form a polymer layer on the substrates or electrodes, or the alignment layer provided thereon. Microscopic measurement data (like SEM and AFM) have confirmed that at least a part of the formed polymer accumulates at the LC/substrate interface.
(110) The polymerization can be carried out in one step. It is also possible firstly to carry out the polymerization, optionally while applying a voltage, in a first step in order to produce a pretilt angle, and subsequently, in a second polymerization step without an applied voltage, to polymerize or crosslink the compounds which have not reacted in the first step (“end curing”).
(111) Suitable and preferred polymerization methods are, for example, thermal or photopolymerization, preferably photopolymerization, in particular UV induced photopolymerization, which can be achieved by exposure of the polymerizable compounds to UV radiation.
(112) Optionally one or more polymerization initiators are added to the LC medium. Suitable conditions for the polymerization and suitable types and amounts of initiators are known to the person skilled in the art and are described in the literature. Suitable for free-radical polymerization are, for example, the commercially available photoinitiators Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369® or Darocure1173® (Ciba AG). If a polymerization initiator is employed, its proportion is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.
(113) The polymerizable compounds according to the invention are also suitable for polymerization without an initiator, which is accompanied by considerable advantages, such, for example, lower material costs and in particular less contamination of the LC medium by possible residual amounts of the initiator or degradation products thereof. The polymerization can thus also be carried out without the addition of an initiator. In a preferred embodiment, the LC medium thus does not contain a polymerization initiator.
(114) The LC medium may also comprise one or more stabilisers in order to prevent undesired spontaneous polymerisation of the RMs, for example during storage or transport. Suitable types and amounts of stabilisers are known to the person skilled in the art and are described in the literature. Particularly suitable are, for example, the commercially available stabilisers from the Irganox® series (Ciba AG), such as, for example, Irganox® 1076. If stabilisers are employed, their proportion, based on the total amount of RMs or the polymerizable component (component A), is preferably 10-500,000 ppm, particularly preferably 50-50,000 ppm.
(115) The polymerizable compounds of formula I do in particular show good UV absorption in, and are therefore especially suitable for, a process of preparing a PSA display including one or more of the following features: the polymerizable medium is exposed to UV light in the display in a 2-step process, including a first UV exposure step (“UV-1 step”) to generate the tilt angle, and a second UV exposure step (“UV-2 step”) to finish polymerization, the polymerizable medium is exposed to UV light in the display generated by an energy-saving UV lamp (also known as “green UV lamps”). These lamps are characterized by a relative low intensity ( 1/100- 1/10 of a conventional UV1 lamp) in their absorption spectra from 300-380 nm, and are preferably used in the UV2 step, but are optionally also used in the UV1 step when avoiding high intensity is necessary for the process. the polymerizable medium is exposed to UV light in the display generated by a UV lamp with a radiation spectrum that is shifted to longer wavelengths, preferably 340 nm or more, to avoid short UV light exposure in the PS-VA process.
(116) Both using lower intensity and a UV shift to longer wavelengths protect the organic layer against damage that may be caused by the UV light.
(117) A preferred embodiment of the present invention relates to a process for preparing a PSA display as described above and below, comprising one or more of the following features: the polymerizable LC medium is exposed to UV light in a 2-step process, including a first UV exposure step (“UV-1 step”) to generate the tilt angle, and a second UV exposure step (“UV-2 step”) to finish polymerisation, the polymerizable LC medium is exposed to UV light generated by a UV lamp having an intensity of from 0.5 mW/cm.sup.2 to 10 mW/cm.sup.2 in the wavelength range from 300-380 nm, preferably used in the UV2 step, and optionally also in the UV1 step, the polymerizable LC medium is exposed to UV light having a wavelength of 340 nm or more, and preferably 400 nm or less.
(118) This preferred process can be carried out for example by using the desired UV lamps or by using a band pass filter and/or a cut-off filter, which are substantially transmissive for UV light with the respective desired wavelength(s) and are substantially blocking light with the respective undesired wavelengths. For example, when irradiation with UV light of wavelengths λ of 300-400 nm is desired, UV exposure can be carried out using a wide band pass filter being substantially transmissive for wavelengths 300 nm<λ<400 nm. When irradiation with UV light of wavelength λ of more than 340 nm is desired, UV exposure can be carried out using a cut-off filter being substantially transmissive for wavelengths λ>340 nm.
(119) “Substantially transmissive” means that the filter transmits a substantial part, preferably at least 50% of the intensity, of incident light of the desired wavelength(s). “Substantially blocking” means that the filter does not transmit a substantial part, preferably at least 50% of the intensity, of incident light of the undesired wavelengths. “Desired (undesired) wavelength” e.g. in case of a band pass filter means the wavelengths inside (outside) the given range of λ, and in case of a cut-off filter means the wavelengths above (below) the given value of λ.
(120) This preferred process enables the manufacture of displays by using longer UV wavelengths, thereby reducing or even avoiding the hazardous and damaging effects of short UV light components.
(121) UV radiation energy is in general from 6 to 100 J, depending on the production process conditions.
(122) Preferably the LC medium according to the present invention does essentially consist of a polymerizable component A) and an LC component B) (or LC host mixture) as described above and below. However, the LC medium may additionally comprise one or more further components or additives, preferably selected from the list including but not limited to co-monomers, chiral dopants, polymerisation initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricating agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colourants, dyes, pigments and nanoparticles.
(123) Preference is given to LC media in which the polymerizable component A) consists exclusively of polymerizable compounds of formula I.
(124) In another preferred embodiment the polymerizable component A) contains, in addition to the compounds of formula I, one or more further polymerizable compounds (“co-monomers”), preferably selected from RMs.
(125) Preferably the proportion of the polymerizable component A) in the LC medium is from >0 to <5%, very preferably from >0 to ≤1%, most preferably from 0.01 to 0.5%.
(126) Preferably the proportion of the LC component B) in the LC medium is from 95 to <100%, very preferably from 99 to <100%.
(127) Besides the polymerizable component A) as described above, the LC media according to the present invention comprise an LC component B), or LC host mixture, comprising one or more, preferably two or more LC compounds which are selected from low-molecular-weight compounds that are unpolymerizable. These LC compounds are selected such that they are stable and/or unreactive to a polymerization reaction under the conditions applied to the polymerization of the polymerizable compounds.
(128) Examples of these compounds are the aforementioned compounds of formulae B and Q.
(129) Preference is given to LC media in which the LC component B), or the LC host mixture, has a nematic LC phase, and preferably has no chiral liquid crystal phase.
(130) Preference is furthermore given to achiral compounds of formula I, and to LC media in which the compounds of component A and/or B are selected exclusively from the group consisting of achiral compounds.
(131) The LC component B), or LC host mixture, is preferably a nematic LC mixture.
(132) In a preferred embodiment of the present invention the LC component B), or LC host mixture, of the LC medium comprises, in addition to the compounds of formula A, one or more further mesogenic or LC compounds comprising a straight-chain, branched or cyclic alkenyl group (hereinafter also referred to as “alkenyl compounds”), wherein said alkenyl group is stable to a polymerisation reaction under the conditions used for polymerization of the polymerizable compounds contained in the LC medium.
(133) These further alkenyl compounds are preferably selected from formula AN and AY
(134) ##STR00019##
(135) in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:
(136) ##STR00020##
is
(137) ##STR00021##
(138) ##STR00022##
is
(139) ##STR00023##
(140) ##STR00024##
is
(141) ##STR00025## R.sup.A1 alkenyl having 2 to 9 C atoms or, if at least one of the rings X, Y and Z denotes cyclohexenyl, also one of the meanings of R.sup.A2, R.sup.A2 alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, Z.sup.x —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O—, or a single bond, preferably a single bond, L.sup.1-4 H, F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, preferably H, F or Cl, x 1 or 2, z 0 or 1.
(142) Preferred compounds of formula AN and AY are those wherein R.sup.A2 is selected from ethenyl, propenyl, butenyl, pentenyl, hexenyl and heptenyl.
(143) Further preferred compounds of formula AN and AY are those wherein L.sup.1 and L.sup.2 denote F, or one of L.sup.1 and L.sup.2 denotes F and the other denotes Cl, and L.sup.3 and L.sup.4 denote F, or one of L.sup.3 and L.sup.4 denotes F and the other denotes Cl.
(144) The compounds of the formula AN are preferably selected from the following sub-formulae:
(145) ##STR00026##
(146) in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—.
(147) Very preferred compounds of the formula AN are selected from the following sub-formulae:
(148) ##STR00027##
(149) in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, and R.sup.b1 denotes H, CH.sub.3 or C.sub.2H.sub.5.
(150) Very particularly preferred compounds of the formula AN are selected from the following sub-formulae:
(151) ##STR00028##
(152) Most preferred are compounds of formula AN1a2, AN1a5, AN6a1 and AN6a2.
(153) The compounds of the formula AY are preferably selected from the following sub-formulae:
(154) ##STR00029## ##STR00030## ##STR00031##
(155) in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—.
(156) Very preferred compounds of the formula AY are selected from the following sub-formulae:
(157) ##STR00032##
(158) in which m and n each, independently of one another, denote 1, 2, 3, 4, 5 or 6, and alkenyl denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—.
(159) The LC medium preferably comprises no compounds containing a terminal vinyloxy group (—O—CH═CH.sub.2), in particular no compounds of the formula AN or AY in which R.sup.A1 or R.sup.A2 denotes or contains a terminal vinyloxy group (—O—CH═CH.sub.2).
(160) In a preferred embodiment the LC medium contains an LC component B), or LC host mixture, based on compounds with negative dielectric anisotropy. Such LC media are especially suitable for use in PS-VA and PS-UB-FFS displays. Particularly preferred embodiments of such an LC medium, and of the corresponding LC component B) or LC host mixture, are those of sections a)-y) below: a) The LC medium or LC host mixture comprises one or more compounds of the formulae CY and/or PY:
(161) ##STR00033## wherein a denotes 1 or 2, b denotes 0 or 1,
(162) ##STR00034##
denotes
(163) ##STR00035## R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms, Z.sup.x and Z.sup.y each, independently of one another, denote —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond, L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. Preferably, both L.sup.1 and L.sup.2 denote F or one of L.sup.1 and L.sup.2 denotes F and the other denotes Cl, or both L.sup.3 and L.sup.4 denote F or one of L.sup.3 and L.sup.4 denotes F and the other denotes Cl. The compounds of the formula CY are preferably selected from the group consisting of the following sub-formulae:
(164) ##STR00036## ##STR00037## ##STR00038## ##STR00039## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. The compounds of the formula PY are preferably selected from the group consisting of the following sub-formulae:
(165) ##STR00040## ##STR00041## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. b) The LC medium or LC host mixture comprises one or more compounds of the following formula:
(166) ##STR00042## in which the individual radicals have the following meanings:
(167) ##STR00043##
denotes
(168) ##STR00044##
(169) ##STR00045##
denotes
(170) ##STR00046## R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, Z.sup.y denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond. The compounds of the formula ZK are preferably selected from the group consisting of the following sub-formulae:
(171) ##STR00047## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. Especially preferred are compounds of formula ZK1. Particularly preferred compounds of formula ZK are selected from the following sub-formulae:
(172) ##STR00048## wherein the propyl, butyl and pentyl groups are straight-chain groups. Most preferred are compounds of formula ZK1a. c) The LC medium or LC host mixture comprises one or more compounds of the following formula:
(173) ##STR00049## in which the individual radicals on each occurrence, identically or differently, have the following meanings: R.sup.5 and R.sup.6 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms,
(174) ##STR00050##
denotes
(175) ##STR00051##
(176) ##STR00052##
denotes
(177) ##STR00053##
and e denotes 1 or 2. The compounds of the formula DK are preferably selected from the group consisting of the following sub-formulae:
(178) ##STR00054## ##STR00055## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. d) The LC medium or LC host mixture comprises one or more compounds of the following formula:
(179) ##STR00056## in which the individual radicals have the following meanings:
(180) ##STR00057##
denotes
(181) ##STR00058## with at least one ring F being different from cyclohexylene, f denotes 1 or 2, R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, Z.sup.x denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond. L.sup.1 and L.sup.2 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. Preferably, both radicals L.sup.1 and L.sup.2 denote F or one of the radicals L.sup.1 and L.sup.2 denotes F and the other denotes Cl. The compounds of the formula LY are preferably selected from the group consisting of the following sub-formulae:
(182) ##STR00059## ##STR00060## ##STR00061## in which R.sup.1 has the meaning indicated above, alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygen atom or a single bond, and v denotes an integer from 1 to 6. R.sup.1 preferably denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, in particular CH.sub.3, C.sub.2H.sub.5, n-C.sub.3H.sub.7, n-C.sub.4H.sub.9, n-C.sub.5H.sub.11, CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. e) The LC medium or LC host mixture comprises one or more compounds of the following formula:
(183) ##STR00062## in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.1, R.sup.2 alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, L.sup.T1-L.sup.T6 H, F or Cl, with at least one of L.sup.T1 to L.sup.T6 being F or Cl, The compounds of the formula T are preferably selected from the group consisting of the following sub-formulae:
(184) ##STR00063## ##STR00064## ##STR00065## in which R denotes a straight-chain alkyl or alkoxy radical having 1-7 C atoms, R* denotes a straight-chain alkenyl radical having 2-7 C atoms, (O) denotes an oxygen atom or a single bond, and m denotes an integer from 1 to 6. R* preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. R and R* preferably denote methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy. Very preferred are compounds of formulae T1, T2 and T3, especially those of formula T1 and T2. Very preferred are compounds of formula T1-T24 wherein (O) denotes an oxygen atom, m is 1, 2, 3, 4 or 5 and R is methyl, ethyl, propyl, butyl of pentyl or hexyl, which are preferably straight-chained. Preferably, the LC medium does not contain more than 15% of compounds of formula T or T1-T24 or any other compounds with a terphenyl group. Preferably the proportion of compounds of formula T or T1-T24 or any other compounds with a terphenyl group in the LC medium is at least 5%, very preferably from 5 to 15%, most preferably from 5 to 10%. Preferably the LC medium contains 1 to 5, very preferably 1 or 2 compounds of formula T or T1-T24. f) The LC medium or LC host mixture comprises one or more compounds selected from the group consisting of the following formulae:
(185) ##STR00066## in which alkyl denotes C.sub.1-6-alkyl, L.sup.x denotes H or F, and X denotes F, Cl, OCF.sub.3, OCHF.sub.2 or OCH═CF.sub.2. Particular preference is given to compounds of the formula G1 in which X denotes F. g) The LC medium or LC host mixture comprises one or more compounds selected from the group consisting of the following formulae:
(186) ##STR00067## ##STR00068## in which R.sup.5 has one of the meanings indicated above for R.sup.1, alkyl denotes C.sub.1-6-alkyl, d denotes 0 or 1, and z and m each, independently of one another, denote an integer from 1 to 6. R.sup.5 in these compounds is particularly preferably C.sub.1-6-alkyl or -alkoxy or C.sub.2-6-alkenyl, d is preferably 1. The LC medium according to the invention preferably comprises one or more compounds of the above-mentioned formulae in amounts of ≥5% by weight. h) The LC medium or LC host mixture comprises one or more biphenyl compounds selected from the group consisting of the following formulae:
(187) ##STR00069## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. The proportion of the biphenyls of the formulae B1 to B3 in the LC mixture is preferably at least 3% by weight, in particular ≥5% by weight. The compounds of the formula B2 are particularly preferred. The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following sub-formulae:
(188) ##STR00070## in which alkyl* denotes an alkyl radical having 1-6 C atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formulae B1a and/or B2c. i) The LC medium or LC host mixture comprises one or more compounds selected from the group consisting of the following formulae:
(189) ##STR00071## in which R.sup.1 and R.sup.2 have the meanings indicated above and preferably each, independently of one another, denote straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms. Preferred media comprise one or more compounds selected from the formulae O1, O3 and O4. k) The LC medium or LC host mixture comprises one or more compounds of the following formula:
(190) ##STR00072## in which
(191) ##STR00073##
denotes
(192) ##STR00074## R.sup.9 denotes H, CH.sub.3, C.sub.2H.sub.5 or n-C.sub.3H.sub.7, (F) denotes an optional fluorine substituent, and q denotes 1, 2 or 3, and R.sup.7 has one of the meanings indicated for R.sup.1, preferably in amounts of >3% by weight, in particular ≥5% by weight and very particularly preferably 5-30% by weight. Particularly preferred compounds of the formula FI are selected from the group consisting of the following sub-formulae:
(193) ##STR00075## in which R.sup.7 preferably denotes straight-chain alkyl, and R.sup.9 denotes CH.sub.3, C.sub.2H.sub.5 or n-C.sub.3H.sub.7. Particular preference is given to the compounds of the formulae FI1, FI2 and FI3. l) The LC medium or LC host mixture comprises one or more compounds selected from the group consisting of the following formulae:
(194) ##STR00076## in which R.sup.8 has the meaning indicated for R.sup.1, and alkyl denotes a straight-chain alkyl radical having 1-6 C atoms. m) The LC medium or LC host mixture comprises one or more compounds which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, the compounds selected from the group consisting of the following formulae:
(195) ##STR00077## ##STR00078## in which R.sup.10 and R.sup.11 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms, and R.sup.10 and R.sup.11 preferably denote straight-chain alkyl or alkoxy having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, and Z.sup.1 and Z.sup.2 each, independently of one another, denote —C.sub.2H.sub.4—, —CH═CH—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.3O—, —O(CH.sub.2).sub.3—, —CH═CH—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2CH═CH—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CF═CH—, —CH═CF—, —CH.sub.2— or a single bond. n) The LC medium or LC host mixture comprises one or more difluoro-dibenzochromans and/or chromans of the following formulae:
(196) ##STR00079## in which R.sup.11 and R.sup.12 each, independently of one another, have one of the meanings indicated above for R.sup.11, ring M is trans-1,4-cyclohexylene or 1,4-phenylene, Z.sup.m —C.sub.2H.sub.4—, —CH.sub.2O—, —OCH.sub.2—, —CO—O— or —O—CO—, c is 0, 1 or 2, preferably in amounts of 3 to 20% by weight, in particular in amounts of 3 to 15% by weight. Particularly preferred compounds of the formulae BC, CR and RC are selected from the group consisting of the following sub-formulae:
(197) ##STR00080## ##STR00081## ##STR00082## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygen atom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2. o) The LC medium or LC host mixture comprises one or more fluorinated phenanthrenes and/or dibenzofurans of the following formulae:
(198) ##STR00083## in which R.sup.11 and R.sup.12 each, independently of one another, have one of the meanings indicated above for R.sup.11, b denotes 0 or 1, L denotes F, and r denotes 1, 2 or 3. Particularly preferred compounds of the formulae PH and BF are selected from the group consisting of the following sub-formulae:
(199) ##STR00084## in which R and R′ each, independently of one another, denote a straight-chain alkyl or alkoxy radical having 1-7 C atoms. p) The LC medium or LC host mixture comprises one or more monocyclic compounds of the following formula
(200) ##STR00085## wherein R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms, L.sup.1 and L.sup.2 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. Preferably, both L.sup.1 and L.sup.2 denote F or one of L.sup.1 and L.sup.2 denotes F and the other denotes Cl, The compounds of the formula Y are preferably selected from the group consisting of the following sub-formulae:
(201) ##STR00086## in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, and Alkenyl and Alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl and Alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. Particularly preferred compounds of the formula Y are selected from the group consisting of the following sub-formulae:
(202) ##STR00087## wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5 C atoms. q) The LC medium does not contain a compound which contains a terminal vinyloxy group (—O—CH═CH.sub.2). r) The LC medium comprises 1 to 5, preferably 1, 2 or 3, polymerizable compounds, preferably selected from formula I or sub-formulae thereof. s) In the LC medium the proportion of polymerizable compounds, in particular of formula I or sub-formulae thereof, in the mixture as a whole is 0.05 to 5%, preferably 0.1 to 1%. t) The LC medium comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY1, CY2, PY1 and/or PY2. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. u) The LC medium comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY9, CY10, PY9 and/or PY10. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. v) The LC medium comprises 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formulae ZK1, ZK2 and/or ZK6. The proportion of these compounds in the mixture as a whole is preferably 3 to 25%, particularly preferably 5 to 45%. The content of these individual compounds is preferably in each case 2 to 20%. w) In the LC medium the proportion of compounds of formulae CY, PY and ZK in the mixture as a whole is greater than 70%, preferably greater than 80%. x) The LC medium or LC host mixture contains one or more compounds containing an alkenyl group, preferably selected from the group consisting of formula CY, PY and LY, wherein one or both of R.sup.1 and R.sup.2 denote straight-chain alkenyl having 2-6 C atoms, formula ZK and DK, wherein one or both of R.sup.3 and R.sup.4 or one or both of R.sup.5 and R.sup.6 denote straight-chain alkenyl having 2-6 C atoms, and formula B2 and B3, very preferably selected from formulae CY15, CY16, CY24, CY32, PY15, PY16, ZK3, ZK4, DK3, DK6, B2 and B3. The concentration of these compounds in the LC host mixture is preferably from 2 to 70%, very preferably from 3 to 55%. y) The LC medium contains one or more, preferably 1 to 5, compounds selected of formula PY1-PY8, very preferably of formula PY2. The proportion of these compounds in the mixture as a whole is preferably 1 to 30%, particularly preferably 2 to 20%. The content of these individual compounds is preferably in each case 1 to 20%.
(203) The combination of compounds of the preferred embodiments mentioned above with the polymerized compounds described above causes low threshold voltages, low rotational viscosities and very good low-temperature stabilities in the LC media according to the invention at the same time as constantly high clearing points and high HR values, and allows the rapid establishment of a particularly low pretilt angle in PSA displays. In particular, the LC media exhibit significantly shortened response times, in particular also the grey-shade response times, in PSA displays compared with the media from the prior art.
(204) The LC media and LC host mixtures according to the invention, while retaining the nematic phase down to −20° C. and preferably down to −30° C., particularly preferably down to −40° C., and the clearing point ≥70° C., preferably ≥74° C., at the same time allow rotational viscosities γ.sub.1 of ≤120 mPa.Math.s to be achieved, enabling excellent MLC displays having fast response times to be achieved.
(205) The LC media and LC host mixtures of the present invention preferably have a nematic phase range of at least 80 K, particularly preferably at least 100 K, and a rotational viscosity ≤150 mPa.Math.s, preferably ≤120 mPa.Math.s, at 20° C.
(206) In the VA-type displays according to the invention, the molecules in the layer of the LC medium in the switched-off state are aligned perpendicular to the electrode surfaces (homeotropically) or have a tilted homeotropic alignment. On application of an electrical voltage to the electrodes, a realignment of the LC molecules takes place with the longitudinal molecular axes parallel to the electrode surfaces.
(207) The LC media according to the invention, in particular for use in displays of the PS-VA and PS-UB-FFS type, preferably have a negative dielectric anisotropy Ac, very preferably from −0.5 to −10, most preferably from −2.5 to −7.5, at 20° C. and 1 kHz.
(208) The birefringence Δn in LC media according to the invention, in particular for use in displays of the PS-VA and PS-UB-FFS type is preferably below 0.16, very preferably from 0.06 to 0.14, most preferably from 0.07 to 0.12.
(209) In order to increase the anchoring force, polymerizable compounds, so-called “reactive mesogens”, may also additionally be added to the mixtures according to the invention. Preferred polymerizable compounds are listed in Table D.
(210) The LC media according to the invention may also comprise further additives which are known to the person skilled in the art and are described in the literature, such as, for example, polymerisation initiators, inhibitors, stabilisers, surface-active substances or chiral dopants. These additives may be polymerizable or non-polymerizable. Polymerizable additives are accordingly ascribed to the polymerizable component or component A). Non-polymerizable additives are accordingly ascribed to the non-polymerizable component or component B).
(211) The LC media according to the present invention may, for example, also comprise one or more UV stabilisers, such as Tinuvin® from Ciba Chemicals, in particular Tinuvin® 770, antioxidants, free-radical scavengers, nanoparticles, etc. Suitable stabilisers are mentioned below in Tables C.
(212) The LC media according to the present invention may, for example, also comprise one or more chiral dopants, preferably in a concentration from 0.01 to 1%, very preferably from 0.05 to 0.5%. Suitable chiral dopants are mentioned below in Table B. Preferred chiral dopants are for example selected from R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, or R- or S-5011.
(213) In another preferred embodiment the LC media contain a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.
(214) Furthermore, it is possible to add to the LC media, for example, 0 to 15% by weight of pleochroic dyes, furthermore nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)), for improving the conductivity, or substances for modifying the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases. Substances of this type are described, for example, in DE-A 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.
(215) The individual components of the preferred embodiments a)-y) of the LC media according to the invention are either known or methods for the preparation thereof can readily be derived from the prior art by the person skilled in the relevant art, since they are based on standard methods described in the literature. Compounds of the formula CY are described, for example, in EP-A-0 364 538. Compounds of the formula ZK are described, for example, in DE-A-26 36 684 and DE-A-33 21 373.
(216) It goes without saying to the person skilled in the art that the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes like deuterium etc.
(217) The LC media which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing one or more compounds of the formula B and Q with one or more compounds of the above-mentioned preferred embodiments and/or with further liquid-crystalline compounds and/or additives, like polymerizable compounds or RMs. In general, the desired amount of the components used in the smaller amount is dissolved in the components making up the principal constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing.
(218) It goes without saying that, through a suitable choice of the components of the LC mixtures according to the invention, it is also possible for higher clearing points (for example above 100° C.) to be achieved at higher threshold voltages or lower clearing points to be achieved at lower threshold voltages with retention of the other advantageous properties. At viscosities correspondingly increased only slightly, it is likewise possible to obtain mixtures having higher Δε and thus low thresholds. The MLC displays according to the invention preferably operate at the first Gooch and Tarry transmission minimum [C. H. Gooch and H. A. Tarry, Electron. Lett. 10, 2-4, 1974; C. H. Gooch and H. A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], where, besides particularly favorable electro-optical properties, such as, for example, high steepness of the characteristic line and low angle dependence of the contrast (German patent 30 22 818), lower dielectric anisotropy is sufficient at the same threshold voltage as in an analogous display at the second minimum. This enables significantly higher specific resistance values to be achieved using the mixtures according to the invention at the first minimum than in the case of mixtures comprising cyano compounds. Through a suitable choice of the individual components and their proportions by weight, the person skilled in the art is able to set the birefringence necessary for a pre-specified layer thickness of the MLC display using simple routine methods.
(219) The construction of an LC display according to the invention from polarisers, electrode base plates and surface-treated electrodes corresponds to the usual design for displays of this type. The term usual design is broadly drawn here and also encompasses all derivatives and modifications of the LC display, in particular including matrix display elements based on poly-Si TFTs or MIM.
(220) The following examples are intended to explain the invention without limiting it. Above and below, percentage data denote percent by weight; all temperatures are indicated in degrees Celsius.
(221) Throughout the patent application and in the working examples, the structures of the liquid-crystal compounds are indicated by means of acronyms. Unless indicated otherwise, the transformation into chemical formulae takes place in accordance with Tables I-III. All radicals C.sub.nH.sub.2n+1, C.sub.mH.sub.2m+1, C.sub.nH.sub.2n, C.sub.mH.sub.2m and C.sub.kH.sub.2k are straight-chain alkyl radicals or alkenyl radicals respectively, in each case having n, m or k C atoms; n and m each, independently of one another, denote 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1, 2, 3, 4, 5 or 6, and k is 0, 1, 2, 3, 4, 5 or 6. In Table I the ring elements of the respective compound are coded, in Table II the bridging members are listed and in Table III the meanings of the symbols for the left-hand and right-hand side chains of the compounds are indicated.
(222) TABLE-US-00001 TABLE I Ring elements
(223) TABLE-US-00002 TABLE II Bridging members E —CH.sub.2CH.sub.2— V —CH═CH— T —C≡C— W —CF.sub.2CF.sub.2— Z —COO— ZI —OCO— O —CH.sub.2O— OI —OCH.sub.2— Q —CF.sub.2O— QI —OCF.sub.2—
(224) TABLE-US-00003 TABLE III Side chains Left-hand side chain Right-hand side chain n- C.sub.nH.sub.2n+1— -n —C.sub.nH.sub.2n+1 nO- C.sub.nH.sub.2n+1—O— -On —O—C.sub.nH.sub.2n+1 V- CH.sub.2═CH— -V —CH═CH.sub.2 nV- C.sub.nH.sub.2n+1—CH═CH— -nV —C.sub.nH.sub.2n—CH═CH.sub.2 Vn- CH.sub.2═CH—C.sub.nH.sub.2n— -Vn —CH═CH—C.sub.nH.sub.2n+1 nVm- C.sub.nH.sub.2n+1—CH═CH—C.sub.mH.sub.2m— -nVm —C.sub.nH.sub.2n—CH═CH—C.sub.mH.sub.2m+1 N- N≡C— -N —C≡N F- F— -F —F Cl- Cl— -Cl —Cl M- CFH.sub.2— -M —CFH.sub.2 D- CF.sub.2H— -D —CF.sub.2H T- CF.sub.3— -T —CF.sub.3 MO- CFH.sub.2O— -OM —OCFH.sub.2 DO- CF.sub.2HO— -OD —OCF.sub.2H TO- CF.sub.3O— -OT —OCF.sub.3 T- CF.sub.3— -T —CF.sub.3 A- H—C≡C— -A —C≡C—H FXO- CF.sub.2═CHO— -OXF —OCH═CF.sub.2
(225) Preferred mixture components are shown in Table A.
(226) In the formulae below m and n are independently of each other an integer from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6, and (O)C.sub.mH.sub.2m+1 means C.sub.mH.sub.2m+1 or OC.sub.mH.sub.2m+1.
(227) TABLE-US-00004 TABLE A
(228) Particular preference is given to liquid-crystalline mixtures which comprise at least one, two, three, four or more compounds from Table A.
(229) Table B indicates possible dopants which are generally added to the mixtures according to the invention. The mixtures preferably comprise 0-10% by weight, in particular 0.001-5% by weight and particularly preferably 0.001-3% by weight, of dopants.
(230) TABLE-US-00005 TABLE B
(231) Stabilisers which can be added, for example, to the mixtures according to the invention in amounts of 0-10% by weight are mentioned below.
(232) TABLE-US-00006 TABLE C
(233) Table D shows illustrative reactive mesogenic compounds which can be used in the LC media in accordance with the present invention.
(234) TABLE-US-00007 TABLE D
(235) In a preferred embodiment, the mixtures according to the invention comprise one or more polymerizable compounds, preferably selected from the polymerizable compounds of the formulae RM-1 to RM-131. Of these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-43, RM-47, RM-49, RM-51, RM-59, RM-69, RM-71, RM-83, RM-97, RM-98, RM-104, RM-112, RM-115 and RM-116 are particularly preferred.
(236) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
(237) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.
(238) The entire disclosures of all applications, patents and publications, cited herein and of corresponding European application No. 16183932.9, filed Aug. 12, 2016 are incorporated by reference herein.
EXAMPLES
(239) The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combinations are accessible.
(240) In addition, the following abbreviations and symbols are used: V.sub.0 threshold voltage, capacitive [V] at 20° C., n.sub.e extraordinary refractive index at 20° C. and 589 nm, n.sub.o ordinary refractive index at 20° C. and 589 nm, Δn optical anisotropy at 20° C. and 589 nm, ε.sub.⊥ dielectric permittivity perpendicular to the director at 20° C. and 1 kHz, ε.sub.| dielectric permittivity parallel to the director at 20° C. and 1 kHz, Δε dielectric anisotropy at 20° C. and 1 kHz, cl.p., T(N,I) clearing point [° C.], γ.sub.1 rotational viscosity at 20° C. [mPa.Math.s], K.sub.1 elastic constant, “splay” deformation at 20° C. [pN], K.sub.2 elastic constant, “twist” deformation at 20° C. [pN], K.sub.3 elastic constant, “bend” deformation at 20° C. [pN].
(241) Unless explicitly noted otherwise, all concentrations in the present application are quoted in percent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents.
(242) Unless explicitly noted otherwise, all temperature values indicated in the present application, such as, for example, for the melting point T(C,N), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (° C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase, S=smectic phase and I=isotropic phase. The data between these symbols represent the transition temperatures.
(243) All physical properties are and have been determined in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals”, Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20° C., and Δn is determined at 589 nm and Δε at 1 kHz, unless explicitly indicated otherwise in each case.
(244) The term “threshold voltage” for the present invention relates to the capacitive threshold (V.sub.0), also known as the Freedericks threshold, unless explicitly indicated otherwise. In the examples, the optical threshold may also, as generally usual, be quoted for 10% relative contrast (V.sub.10).
(245) Unless stated otherwise, the process of polymerizing the polymerizable compounds in the PSA displays as described above and below is carried out at a temperature where the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably is carried out at room temperature (also abbreviated as “RT”).
(246) Unless stated otherwise, methods of preparing test cells and measuring their electrooptical and other properties are carried out by the methods as described hereinafter or in analogy thereto.
(247) The display used for measurement of the capacitive threshold voltage consists of two plane-parallel glass outer plates at a separation of 25 μm, each of which has on the inside an electrode layer and an unrubbed polyimide alignment layer on top, which effect a homeotropic edge alignment of the liquid-crystal molecules.
(248) The display or test cell used for measurement of the tilt angles consists of two plane-parallel glass outer plates at a separation of 4 μm, each of which has on the inside an electrode layer and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to one another and effect a homeotropic edge alignment of the liquid-crystal molecules.
(249) The polymerizable compounds are polymerized in the display or test cell by irradiation with UVA light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz). In the examples, unless indicated otherwise, a metal halide lamp and an intensity of 50 mW/cm.sup.2 is used for polymerisation. The intensity is measured using a standard UVA meter (Hoenle UV-meter high end with UVA sensor).
(250) The tilt angle is determined by crystal rotation experiment (Autronic-Melchers TBA-105). A low value (i.e. a large deviation from the 90° angle) corresponds to a large tilt here.
(251) The VHR value is measured as follows: 0.3% of a polymerizable monomeric compound is added to the LC host mixture, and the resultant mixture is introduced into VA-VHR test cells which comprise an unrubbed VA-polyimide alignment layer. The LC-layer thickness d is approx. 6 μm, unless stated otherwise. The VHR value is determined before and after UV exposure at 1 V, 60 Hz, 64 μs pulse (measuring instrument: Autronic-Melchers VHRM-105).
(252) LC Host Mixtures
Comparison Example 1A
(253) The nematic LC host mixture C0 is formulated as follows.
(254) TABLE-US-00008 BCH-32 9.00% cl.p. 74.7° C. .sup. CC-3-V1 6.00% Δn 0.1105 CCH-301 3.00% Δε −3.3 CCH-34 8.00% ε.sub.|| 3.6 CCH-35 8.00% γ.sub.1 117 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.12 CCY-3-O2 11.00% CPY-2-O2 4.50% CPY-3-O2 5.50% CY-3-O2 15.00% PCH-301 4.00% PY-3-O2 18.00%
(255) The mixture does not contain a compound of formula B or Q.
Comparison Example 1B
(256) The nematic LC host mixture C1 is formulated as follows.
(257) TABLE-US-00009 BCH-32 10.50% cl.p. 75.0° C. .sup. CC-3-V1 6.00% Δn 0.1109 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.6 CCH-35 8.00% γ.sub.1 116 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.12 CCY-3-O2 11.00% CPY-3-O2 6.50% CY-3-O2 15.00% PCH-301 3.00% PY-3-O2 18.00% B(S)-2O-O5 2.00%
(258) The mixture contains a compound of formula B (B(S)-2O-O5), but does not contain a compound of formula Q.
Example 1
(259) The nematic LC host mixture N1 is formulated as follows.
(260) TABLE-US-00010 BCH-32 9.50% cl.p. 75.0° C. .sup. CC-3-V1 6.00% Δn 0.1115 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.7 CCH-35 8.00% γ.sub.1 120 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.10 CCY-3-O2 12.00% CPY-2-O2 3.50% CPY-3-O2 3.00% CY-3-O2 15.00% PCH-301 2.50% PY-3-O2 18.00% B(S)-2O-O5 2.00% PPGU-3-F 0.50%
(261) The mixture contains a compound of formula B (B(S)-2O-O5) and a compound of formula Q (PPGU-3-F).
Comparison Example C2
(262) The nematic LC host mixture C2 is formulated as follows.
(263) TABLE-US-00011 BCH-32 8.50% cl.p. 74.8° C. .sup. CC-3-V1 6.00% Δn 0.1104 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.6 CCH-35 8.00% γ.sub.1 114 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.13 CCY-3-O2 11.00% CPY-3-O2 7.00% CY-3-O2 11.50% PCH-301 7.00% PY-3-O2 17.00% B(S)-2O-O5 4.00%
(264) The mixture contains a compound of formula B (B(S)-2O-O5), but does not contain a compound of formula Q.
Example 2
(265) The nematic LC host mixture N2 is formulated as follows.
(266) TABLE-US-00012 BCH-32 10.00% cl.p. 74.5° C. .sup. CC-3-V1 6.00% Δn 0.1114 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.7 CCH-35 8.00% γ.sub.1 114 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.11 CCY-3-O2 11.00% CPY-3-O2 5.00% CY-3-O2 15.00% PCH-301 3.50% PY-3-O2 17.00% B(S)-2O-O5 4.00% PPGU-3-F 0.50%
(267) The mixture contains a compound of formula B (B(S)-2O-O5) and a compound of formula Q (PPGU-3-F).
Comparison Example C3
(268) The nematic LC host mixture C3 is formulated as follows.
(269) TABLE-US-00013 BCH-32 10.50% cl.p. 74.9° C. .sup. CC-3-V1 6.00% Δn 0.1110 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.6 CCH-35 8.00% γ.sub.1 112 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.11 CCY-3-O2 11.00% CPY-3-O2 4.00% CY-3-O2 12.50% PCH-301 6.50% PY-3-O2 15.50% B(S)-2O-O4 2.00% B(S)-2O-O5 4.00%
(270) The mixture contains two compounds of formula B (B(S)-2O-O4, B(S)-2O-O5), but does not contain a compound of formula Q.
Example 3
(271) The nematic LC host mixture N3 is formulated as follows.
(272) TABLE-US-00014 BCH-32 9.00% cl.p. 75.2° C. .sup. CC-3-V1 6.00% Δn 0.1109 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.7 CCH-35 8.00% γ.sub.1 112 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.11 CCY-3-O2 11.00% CPY-3-O2 5.00% CY-3-O2 13.50% PCH-301 6.50% PY-3-O2 14.50% B(S)-2O-O4 2.00% B(S)-2O-O5 4.00% PPGU-3-F 0.50%
(273) The mixture contains two compounds of formula B (B(S)-2O-O4, B(S)-2O-O5) and a compound of formula Q (PPGU-3-F).
Comparison Example C4
(274) The nematic LC host mixture C4 is formulated as follows.
(275) TABLE-US-00015 BCH-32 8.00% cl.p. 74.9° C. CC-3-V1 6.00% Δn 0.1106 CCH-301 3.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.6 CCH-35 8.00% γ.sub.1 109 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.12 CCY-3-O2 12.00% CPY-3-O2 4.00% CY-3-O2 8.00% PCH-301 11.50% PY-3-O2 14.50% B(S)-2O-O4 4.00% B(S)-2O-O5 4.00%
(276) The mixture contains two compounds of formula B (B(S)-2O-O4, B(S)-2O-O5), but does not contain a compound of formula Q.
Example 4
(277) The nematic LC host mixture N4 is formulated as follows.
(278) TABLE-US-00016 BCH-32 8.50% cl.p. 74.9° C. CC-3-V1 6.00% Δn 0.1106 CCH-301 2.00% Δε −3.3 CCH-34 9.00% ε.sub.|| 3.7 CCH-35 8.00% γ.sub.1 111 mPa s CCP-3-1 8.00% K.sub.3/K.sub.1 1.13 CCY-3-O2 12.00% CPY-3-O2 3.00% CY-3-O2 12.00% PCH-301 10.00% PY-3-O2 13.00% B(S)-2O-O4 4.00% B(S)-2O-O5 4.00% PPGU-3-F 0.50%
(279) The mixture contains two compounds of formula B (B(S)-2O-O4, B(S)-2O-O5) and a compound of formula Q (PPGU-3-F).
Use Examples
(280) Table 1 shows the rotational viscosity of the LC host mixtures C0-C4 and N1-N4 in relation to the concentration of compounds of formula B.
(281) TABLE-US-00017 TABLE 1 Rotational Viscosity Host Mixture C0 C1 C2 C3 C4 Conc. B(S)-nO-Om (%) 0 2 4 6 8 Rot. Viscosity γ.sub.1 (mPa s) 117 116 114 112 109 Host Mixture N1 N2 N3 N4 Conc. B(S)-nO-Om (%) 2 4 6 8 Rot. Viscosity γ.sub.1 (mPa s) 120 114 112 111
(282) From Table 1 it can be seen that, with increasing concentration of the compound B(S)-nO-Om of formula B, the rotational viscosity of the LC host mixture is decreasing. This shows that the addition of compounds of formula B leads to the advantageous effect of reducing the rotational viscosity, which results in shorter response times.
(283) Polymerizable Mixtures
(284) Polymerizable mixtures are prepared by adding reactive mesogen M1 to each of nematic LC host mixtures C0-C4 and N1-N4, respectively, at a concentration of 0.35 by weight.
(285) ##STR00442##
(286) The composition of the polymerizable mixtures is shown in Table 2 below.
(287) TABLE-US-00018 TABLE 2 Polymerizable Mixture Composition Mix. No. LC Host RM RM conc. (%) CP0 C0 M1 0.35 CP1 C1 M1 0.35 CP2 C2 M1 0.35 CP3 C3 M1 0.35 CP4 C4 M1 0.35 P1 N1 M1 0.35 P2 N2 M1 0.35 P3 N3 M1 0.35 P4 N4 M1 0.35
(288) The VHR values of the polymerizable mixtures are measured at 60° C. in VA-VHR test cells before and after UV exposure for 80 min at RT using a fluorescent UV lamp type C (305 nm˜355 nm).
(289) The VHR values of the polymerizable mixtures are shown in Table 3.
(290) TABLE-US-00019 TABLE 3 VHR values CP0 CP1 CP2 CP3 CP4 VHR at 60° C. (%) VHR/% Initial 98.2 98.2 98.4 98.3 98.3 After UV (80 min) 98.1 97.5 96.6 95.2 94.2 P1 P2 P3 P4 VHR at 60° C. (%) VHR/% Initial 98.1 97.8 98.1 97.9 After UV (80 min) 97.0 96.7 96.1 95.7
(291) From Table 3 it can be seen that the initial VHR value of all polymerizable mixtures CP0-CP4 and P1-P4 is approximately at the same level.
(292) However, after polymerization the mixtures CP1-CP4 and P1-P4 show, with increasing amount of compounds of formula B, an increasing VHR drop, compared to the mixture CP0 without a compound of formula B.
(293) On the other hand, in the mixtures P1-P4 according to the present invention, which do additionally contain a compound of formula Q, after polymerization the increase of the VHR drop with increasing amount of compounds of formula B is reduced, compared to mixtures CP1-CP4 which do not contain a compound of formula Q.
(294) This effect is especially significant in the mixtures P2-P4 with higher concentration of compounds of formula B, where the VHR after polymerisation is higher than in the comparative mixtures C2-C4.
(295) Thus, the addition of a compound of formula Q to the LC medium can reduce the VHR drop that is observed when adding increasing amounts of a compound B to the LC medium. The effect is especially significant for mixtures with a higher amount of compounds of formula B. Since the addition of a higher amount of compounds of formula B is desirable because it leads to lower viscosity as shown above, the use of mixtures P1-P4 according to the present invention allows to combine the advantages of both low viscosity and high reliability.
(296) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
(297) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.