U.S. patent application number 16/934466 was filed with the patent office on 2021-01-14 for liquid-crystal display devices containing polymerisable compounds.
This patent application is currently assigned to Merck Patent GmbH. The applicant listed for this patent is Merck Patent GmbH. Invention is credited to Kaja Christina DEING, Dmitry USHAKOV.
Application Number | 20210009901 16/934466 |
Document ID | / |
Family ID | 1000005002840 |
Filed Date | 2021-01-14 |
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United States Patent
Application |
20210009901 |
Kind Code |
A1 |
USHAKOV; Dmitry ; et
al. |
January 14, 2021 |
Liquid-Crystal Display Devices Containing Polymerisable
Compounds
Abstract
Liquid-crystal (LC) display devices comprising polymerisable
compounds, processes and intermediates for the preparation of the
devices and compounds, LC media comprising the compounds, and the
use of the polymerisable compounds and LC media for optical,
electro-optical and electronic purposes, in particular in LC
displays, especially in LC displays of the polymer sustained
alignment type.
Inventors: |
USHAKOV; Dmitry; (Muenster,
DE) ; DEING; Kaja Christina; (Darmstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Merck Patent GmbH |
Darmstadt |
|
DE |
|
|
Assignee: |
Merck Patent GmbH
Darmstadt
DE
|
Family ID: |
1000005002840 |
Appl. No.: |
16/934466 |
Filed: |
July 21, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15834518 |
Dec 7, 2017 |
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16934466 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 2019/301 20130101;
G02F 1/133397 20210101; C09K 19/542 20130101; G02F 1/13775
20210101; G02F 1/133703 20130101; C09K 2019/3009 20130101; C09K
2019/3016 20130101; C09K 2019/3004 20130101; C09K 19/3003 20130101;
G02F 1/137 20130101; C09K 2019/548 20130101; C09K 19/0208
20130101 |
International
Class: |
C09K 19/54 20060101
C09K019/54; C09K 19/02 20060101 C09K019/02; C09K 19/30 20060101
C09K019/30; G02F 1/137 20060101 G02F001/137; G02F 1/1337 20060101
G02F001/1337 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2016 |
EP |
16202818.7 |
Claims
1. A liquid crystal (LC) display device, which is a PSA display or
a polymer stabilised SA-VA display, and which comprises two
substrates, at least one which is transparent to light, an
electrode provided on each substrate or two electrodes provided on
only one of the substrates, and located between the substrates a
layer of an LC medium, wherein the LC medium comprises one or more
polymerisable compounds of the following formula I and the
polymerisable compounds are polymerised between the substrates of
the display: ##STR00568## wherein the individual radicals,
independently of each other, and on each occurrence identically or
differently, have the following meanings P are a methacrylate group
or an acrylate group, wherein both groups P have the same meaning,
Sp are a single bond or --(CH.sub.2).sub.p1--,
--O--(CH.sub.2).sub.p1--, --O--CO--(CH.sub.2).sub.p1--, or
--CO--O--(CH.sub.2).sub.p1--, wherein p1 is 2, 3, 4, 5 or 6, and,
if Sp is --O--(CH.sub.2).sub.p1--, --O--CO--(CH.sub.2).sub.p1-- or
--CO--O--(CH.sub.2).sub.p1-- the O-atom or CO-group, respectively,
is linked to the benzene ring, L.sup.11, L.sup.12 are F, CI or OR,
R is straight-chain or branched alkyl with 1 to 4 C atoms that is
optionally fluorinated, L.sup.13, L.sup.14 are 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 or Cl, r1, r2 are 0, 1, 2, 3 or
4, wherein r1+r2.gtoreq.2, r3, r4 are 0, 1, 2, 3 or 4, wherein
r1+r3.ltoreq.4 and r2+r4.ltoreq.4, wherein the compounds contain at
least group L.sup.11 or L.sup.12 that is F or Cl, and at least one
group L.sup.11 or L.sup.12 that is OR, and with the proviso that
the following compounds are excluded ##STR00569## wherein P, Sp,
L.sup.11 and L.sup.12 are as defined above.
2. A liquid crystal (LC) display device, which comprises and an LC
medium, wherein the LC medium comprises one or more polymerisable
compounds of the following formula I: ##STR00570## wherein the
individual radicals, independently of each other, and on each
occurrence identically or differently, have the following meanings
P are a methacrylate group or an acrylate group, wherein both
groups P have the same meaning, Sp are a single bond or
--(CH.sub.2).sub.p1--, --O--(CH.sub.2).sub.p1--,
--O--CO--(CH.sub.2).sub.p1--, or --CO--O--(CH.sub.2).sub.p1--,
wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is
--O--(CH.sub.2).sub.p1--, --O--CO--(CH.sub.2).sub.p1-- or
--CO--O--(CH.sub.2).sub.p1-- the O-atom or CO-group, respectively,
is linked to the benzene ring, L.sup.11, L.sup.12 are F, Cl or OR,
R is straight-chain or branched alkyl with 1 to 4 C atoms that is
optionally fluorinated, L.sup.13, L.sup.14 are 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 or Cl, r1, r2 are 0, 1, 2, 3 or
4, wherein r1+r2.gtoreq.2, r3, r4 are 0, 1, 2, 3 or 4, wherein
r1+r3.ltoreq.4 and r2+r4.ltoreq.4, wherein the compounds contain at
least group L.sup.11 or L.sup.12 that is F or Cl, and at least one
group L.sup.11 or L.sup.12 that is OR, and with the proviso that
the following compounds are excluded ##STR00571## wherein P, Sp,
L.sup.11 and L.sup.12 are as defined above.
3. The LC display device of claim 2, which is a PS-VA, PS-OCB,
PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN or polymerized SA-VA
display.
4. The LC display device of claim 1, wherein the compound of
formula I is selected from the following subformulae: ##STR00572##
wherein P, Sp, R, L.sup.11, L.sup.12, L.sup.13, L.sup.14, r2, r3,
r4 have the meanings given in claim 1, r5 is 0, 1, 2 or 3,
r3+r5.ltoreq.3, and r2+r5 is .gtoreq.1.
5. The LC display device of claim 1, wherein the compound of
formula I is selected from the following subformulae: ##STR00573##
##STR00574## wherein P, Sp and R have the meanings given in claim 1
and L' is F or Cl.
6. The LC display device of claim 1, wherein the compound of
formula I is selected from the following subformulae: ##STR00575##
##STR00576## ##STR00577## wherein P and R have the meanings given
in claim 1, L' is F or CI and Sp has one of the meanings given in
claim 1 which is different from a single bond.
7. The LC display device of claim 1, wherein the compound of
formula I is selected from the following subformulae: ##STR00578##
##STR00579## ##STR00580## ##STR00581## ##STR00582## wherein P, Sp
and R have the meanings given in claim 1, L' is F or CI and L'' has
one of the meanings of L.sup.13 given in claim 1.
8. The LC display device of claim 5, wherein, in the compound of
formula I, R is CH.sub.3 and L' is F.
9. The LC display device of claim 1, wherein the LC medium
comprises: a polymerisable component A) comprising one or more
polymerisable compounds of formula I, and a liquid-crystalline LC
component B) comprising one or more mesogenic or liquid-crystalline
compounds.
10. The LC display device of claim 1, wherein the LC medium further
comprises one or more compounds of the formulae CY and/or PY:
##STR00583## in which the individual radicals have the following
meanings: a denotes 1 or 2, b denotes 0 or 1, ##STR00584## denotes
##STR00585## 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.dbd.CH--, --CO--, --O--CO-- or --CO--O-- in such a way that O
atoms are not linked directly to one another, Z.sup.x denotes
--CH.dbd.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, 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.
11. The LC display device of claim 1, wherein the LC medium further
comprises one or more compounds selected from the following
formulae: ##STR00586## in which the individual radicals, on each
occurrence identically or differently, each, independently of one
another, have the following meaning: ##STR00587## 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.dbd.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.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--,
--CH.sub.2O--, --OCH.sub.2--, --CO--O--, --O--CO--,
--C.sub.2F.sub.4--, --CF.dbd.CF--, --CH.dbd.CH--CH.sub.2O--, or a
single bond L.sup.1-4 each, independently of one another, H, F, Cl,
OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, x 1 ort, z
0 or 1.
12. The LC display device of claim 1, wherein the LC medium further
comprises one or more compounds of the following formula:
##STR00588## in which the individual radicals have the following
meanings: ##STR00589## denotes ##STR00590## denotes ##STR00591##
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.dbd.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.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--,
--CH.sub.2O--, --OCH.sub.2--, --COO--, --OCO--, --C.sub.2F.sub.4--,
--CF.dbd.CF-- or a single bond.
13. A process for the production of an LC display device according
to claim 1, comprising the steps of providing the LC medium
comprising one or more polymerisable compounds of formula I between
the substrates of the display and polymerising the polymerisable
compounds.
14. The LC display device of claim 2, wherein the compound of
formula I is selected from the following subformulae: ##STR00592##
wherein P, Sp, R, L.sup.11, L.sup.12, L.sup.13, L.sup.14, r2, r3,
r4 have the meanings given in claim 1, r5 is 0, 1, 2 or 3,
r3+r5.ltoreq.3, and r2+r5 is .gtoreq.1.
15. The LC display device of claim 2, wherein the compound of
formula I is selected from the following subformulae: ##STR00593##
wherein P, Sp and R have the meanings given in claim 1 and L' is F
or Cl.
16. The LC display device of claim 2, wherein the compound of
formula I is selected from the following subformulae: ##STR00594##
##STR00595## ##STR00596## ##STR00597## wherein P and R have the
meanings given in claim 1, L' is F or Cl and Sp has one of the
meanings given in claim 1 which is different from a single
bond.
17. The LC display device of claim 2, wherein the compound of
formula I is selected from the following subformulae: ##STR00598##
##STR00599## ##STR00600## ##STR00601## ##STR00602## wherein P, Sp
and R have the meanings given in claim 1, L' is F or CI and V has
one of the meanings of L.sup.13 given in claim 1.
18. The LC display device of claim 15, wherein, in the compound of
formula I, R is CH.sub.3 and L' is F.
19. The LC display device of claim 2, wherein the LC medium
comprises: a polymerisable component A) comprising one or more
polymerisable compounds of formula I, and a liquid-crystalline LC
component B) comprising one or more mesogenic or liquid-crystalline
compounds.
20. The LC display device of claim 2, wherein the LC medium further
comprises one or more compounds of the formulae CY and/or PY:
##STR00603## in which the individual radicals have the following
meanings: a denotes 1 or 2, b denotes 0 or 1, ##STR00604## denotes
##STR00605## 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.dbd.CH--, --CO--, --O--CO-- or --CO--O-- in such a way that O
atoms are not linked directly to one another, Z.sup.x denotes
--CH.dbd.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, 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.
21. The LC display device of claim 2, wherein the LC medium further
comprises one or more compounds selected from the following
formulae: ##STR00606## in which the individual radicals, on each
occurrence identically or differently, each, independently of one
another, have the following meaning: ##STR00607## 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.dbd.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.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--,
--CH.sub.2O--, --OCH.sub.2--, --CO--O--, --O--CO--,
--C.sub.2F.sub.4--, --CF.dbd.CF--, --CH.dbd.CH--CH.sub.2O--, or a
single bond L.sup.1-4 each, independently of one another, H, F, Cl,
OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, x 1 ort, z
0 or 1.
22. The LC display device of claim 2, wherein the LC medium further
comprises one or more compounds of the following formula:
##STR00608## in which the individual radicals have the following
meanings: ##STR00609## denotes ##STR00610## denotes ##STR00611##
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.dbd.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.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--,
--CH.sub.2O--, --OCH.sub.2--, --COO--, --OCO--, --C.sub.2F.sub.4--,
--CF.dbd.CF-- or a single bond.
Description
[0001] The present invention relates to liquid-crystal (LC) display
devices containing polymerisable compounds, to processes and
intermediates for the preparation of the devices and compounds, to
LC media comprising the compounds, and to the use of the
polymerisable compounds and LC media for optical, electro-optical
and electronic purposes, in particular in LC displays, especially
in LC displays of the polymer sustained alignment type.
BACKGROUND OF THE INVENTION
[0002] One of the liquid-crystal display (LCD) modes used at
present is the TN ("twisted nematic") mode. However, TN LCDs have
the disadvantage of a strong viewing-angle dependence of the
contrast.
[0003] In addition, so-called VA ("vertically aligned") displays
are known which have a broader viewing angle. The LC cell of a VA
display contains a layer of an LC medium between two transparent
electrodes, where the LC medium usually has a negative dielectric
anisotropy. In the switched-off state, the molecules of the LC
layer are aligned perpendicular to the electrode surfaces
(homeotropically) or have a tilted homeotropic alignment. On
application of an electrical voltage to the two electrodes, a
realignment of the LC molecules parallel to the electrode surfaces
takes place.
[0004] Furthermore, OCB ("optically compensated bend") displays are
known which are based on a birefringence effect and have an LC
layer with a so-called "bend" alignment and usually positive
dielectric anisotropy. On application of an electrical voltage, a
realignment of the LC molecules perpendicular to the electrode
surfaces takes place. In addition, OCB displays normally contain
one or more birefringent optical retardation films in order to
prevent undesired transparency to light of the bend cell in the
dark state. OCB displays have a broader viewing angle and shorter
response times compared with TN displays.
[0005] Also known are so-called IPS ("in-plane switching")
displays, which contain an LC layer between two substrates, where
the two electrodes are arranged on only one of the two substrates
and preferably have intermeshed, comb-shaped structures. On
application of a voltage to the electrodes, an electric field which
has a significant component parallel to the LC layer is thereby
generated between them. This causes realignment of the LC molecules
in the layer plane.
[0006] Furthermore, so-called FFS ("fringe-field switching")
displays have been reported (see, inter alia, S. H. Jung et al.,
Jpn. J. Appl. Phys., Volume 43, No. 3, 2004, 1028), which contain
two electrodes on the same substrate, one of which structured in a
comb-shaped manner and the other is unstructured. A strong,
so-called "fringe field" is thereby generated, i.e. a strong
electric field close to the edge of the electrodes, and, throughout
the cell, an electric field which has both a strong vertical
component and also a strong horizontal component. FFS displays have
a low viewing-angle dependence of the contrast. FFS displays
usually contain an LC medium with positive dielectric anisotropy,
and an alignment layer, usually of polyimide, which provides planar
alignment to the molecules of the LC medium.
[0007] FFS displays can be operated as active-matrix or
passive-matrix displays. In the case of active-matrix displays,
individual pixels are usually addressed by integrated, non-linear
active elements, such as, for example, transistors (for example
thin-film transistors ("TFTs")), while in the case of
passive-matrix displays, individual pixels are usually addressed by
the multiplex method, as known from the prior art.
[0008] Furthermore, FFS displays have been disclosed (see S. H. Lee
et al., Appl. Phys. Lett. 73(20), 1998, 2882-2883 and S. H. Lee et
al., Liquid Crystals 39(9), 2012, 1141-1148), which have similar
electrode design and layer thickness as FFS displays, but comprise
a layer of an LC medium with negative dielectric anisotropy instead
of an LC medium with positive dielectric anisotropy. The LC medium
with negative dielectric ansiotropy shows a more favourable
director orientation that has less tilt and more twist orientation
compared to the LC medium with positive dielectric anisotropy, as a
result of which these displays have a higher transmission. The
displays further comprise an alignment layer, preferably of
polyimide provided on at least one of the substrates that is in
contact with the LC medium and induces planar alignment of the LC
molecules of the LC medium. These displays are also known as "Ultra
Brightness FFS (UB-FFS)" mode displays. These displays require an
LC medium with high reliability.
[0009] The term "reliability" as used hereinafter means the quality
of the performance of the display during time and with different
stress loads, such as light load, temperature, humidity, voltage,
and comprises display effects such as image sticking (area and line
image sticking), mura, yogore etc. which are known to the skilled
person in the field of LC displays. As a standard parameter for
categorising the reliability usually the voltage holding ratio
(VHR) value is used, which is a measure for maintaining a constant
electrical voltage in a test display. The higher the VHR value, the
better the reliability of the LC medium.
[0010] In VA displays of the more recent type, uniform alignment of
the LC molecules is restricted to a plurality of relatively small
domains within the LC cell. Disclinations may exist between these
domains, also known as tilt domains. VA displays having tilt
domains have, compared with conventional VA displays, a greater
viewing-angle independence of the contrast and the grey shades. In
addition, displays of this type are simpler to produce since
additional treatment of the electrode surface for uniform alignment
of the molecules in the switched-on state, such as, for example, by
rubbing, is no longer necessary. Instead, the preferential
direction of the tilt or pretilt angle is controlled by a special
design of the electrodes.
[0011] In so-called MVA ("multidomain vertical alignment")
displays, this is usually achieved by the electrodes having
protrusions which cause a local pretilt. As a consequence, the LC
molecules are aligned parallel to the electrode surfaces in
different directions in different, defined regions of the cell on
application of a voltage. "Controlled" switching is thereby
achieved, and the formation of interfering disclination lines is
prevented. Although this arrangement improves the viewing angle of
the display, it results, however, in a reduction in its
transparency to light. A further development of MVA uses
protrusions on only one electrode side, while the opposite
electrode has slits, which improves the transparency to light. The
slitted electrodes generate an inhomogeneous electric field in the
LC cell on application of a voltage, meaning that controlled
switching is still achieved. For further improvement of the
transparency to light, the separations between the slits and
protrusions can be increased, but this in turn results in a
lengthening of the response times. In so-called PVA ("patterned
VA") displays, protrusions are rendered completely superfluous in
that both electrodes are structured by means of slits on the
opposite sides, which results in increased contrast and improved
transparency to light, but is technologically difficult and makes
the display more sensitive to mechanical influences ("tapping",
etc.). For many applications, such as, for example, monitors and
especially TV screens, however, a shortening of the response times
and an improvement in the contrast and luminance (transmission) of
the display are demanded.
[0012] A further development are displays of the so-called PS
("polymer sustained") or PSA ("polymer sustained alignment") type,
for which the term "polymer stabilised" is also occasionally used.
In these, a small amount (for example 0.3% by weight, typically
<1% by weight) of one or more polymerisable, compound(s),
preferably polymerisable monomeric compound(s), is added to the LC
medium and, after filling the LC medium into the display, is
polymerised or crosslinked in situ, usually by UV
photopolymerisation, optionally while a voltage is applied to the
electrodes of the display. The polymerisation is carried out at a
temperature where the LC medium exhibits a liquid crystal phase,
usually at room temperature. The addition of polymerisable
mesogenic or liquid-crystalline compounds, also known as reactive
mesogens or "RMs", to the LC mixture has proven particularly
suitable.
[0013] Unless indicated otherwise, the term "PSA" is used
hereinafter when referring to displays of the polymer sustained
alignment type in general, and the term "PS" is used when referring
to specific display modes, like PS-VA, PS-TN and the like.
[0014] Also, unless indicated otherwise, the term "RM" is used
hereinafter when referring to a polymerisable mesogenic or
liquid-crystalline compound.
[0015] In the meantime, the PS(A) principle is being used in
various conventional LC display modes. Thus, for example, PS-VA,
PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS and PS-TN displays are known. The
polymerisation of the RMs preferably takes place with an applied
voltage in the case of PS-VA and PS-OCB displays, and with or
without, preferably without, an applied voltage in the case of
PS-IPS displays. As can be demonstrated in test cells, the PS(A)
method results in a pretilt in the cell. In the case of PS-OCB
displays, for example, it is possible for the bend structure to be
stabilised so that an offset voltage is unnecessary or can be
reduced. In the case of PS-VA displays, the pretilt has a positive
effect on response times. For PS-VA displays, a standard MVA or PVA
pixel and electrode layout can be used. In addition, however, it is
also possible, for example, to manage with only one structured
electrode side and no protrusions, which significantly simplifies
production and at the same time results in very good contrast at
the same time as very good transparency to light.
[0016] Furthermore, the so-called posi-VA displays ("positive VA")
have proven to be a particularly suitable mode. Like in classical
VA displays, the initial orientation of the LC molecules in posi-VA
displays is homeotropic, i.e. substantially perpendicular to the
substrates, in the initial state when no voltage is applied.
However, in contrast to classical VA displays, in posi-VA displays
LC media with positive dielectric anisotropy are used. Like in the
usually used IPS displays, the two electrodes in posi-VA displays
are arranged on only one of the two substrates, and preferably
exhibit intermeshed and comb-shaped (interdigital) structures. By
application of a voltage to the interdigital electrodes, which
create an electrical field that is substantially parallel to the
layer of the LC medium, the LC molecules are transferred into an
orientation that is substantially parallel to the substrates. In
posi-VA displays polymer stabilisation, by addition of RMs to the
LC medium which are polymerised in the display, has also proven to
be advantageous, as a significant reduction of the switching times
could thereb<be realised.
[0017] PS-VA displays are described, for example, in EP 1 170 626
A2, U.S. Pat. Nos. 6,861,107, 7,169,449, US 2004/0191428 A1, US
2006/0066793 A1 and US 2006/0103804 A1. PS-OCB displays are
described, for example, in T.-J-Chen et al., Jpn. J. Appl. Phys.
45, 2006, 2702-2704 and S. H. Kim, L.-C-Chien, Jpn. J. Appl. Phys.
43, 2004, 7643-7647. PS-IPS displays are described, for example, in
U.S. Pat. No. 6,177,972 and Appl. Phys. Lett. 1999, 75(21), 3264.
PS-TN displays are described, for example, in Optics Express 2004,
12(7), 1221.
[0018] Like the conventional LC displays described above, PSA
displays can be operated as active-matrix or passive-matrix
displays. In the case of active-matrix displays, individual pixels
are usually addressed by integrated, non-linear active elements,
such as, for example, transistors (for example thin-film
transistors ("TFTs")), while in the case of passive-matrix
displays, individual pixels are usually addressed by the multiplex
method, as known from the prior art.
[0019] The PSA display may also comprise an alignment layer on one
or both of the substrates forming the display cell. The alignment
layer is usually applied on the electrodes (where such electrodes
are present) such that it is in contact with the LC medium and
induces initial alignment of the LC molecules. The alignment layer
may comprise or consist of, for example, a polyimide, which may
also be rubbed, or may be prepared by a photoalignment method.
[0020] In particular for monitor and especially TV applications,
optimisation of the response times, but also of the contrast and
luminance (thus also transmission) of the LC display continues to
be demanded. The PSA method can provide significant advantages
here. In particular in the case of PS-VA, PS-IPS, PS-FFS and
PS-posi-VA displays, a shortening of the response times, which
correlate with a measurable pretilt in test cells, can be achieved
without significant adverse effects on other parameters.
[0021] Prior art has suggested biphenyl diacrylates or
dimethacrylates, which are optionally fluorinated as RMs for use in
PSA displays
[0022] However, the problem arises that not all combinations
consisting of an LC mixture and one or more RMs are suitable for
use in PSA displays because, for example, an inadequate tilt or
none at all becomes established or since, for example, the
so-called "voltage holding ratio" (VHR or HR) is inadequate for TFT
display applications. In addition, it has been found that, on use
in PSA displays, the LC mixtures and RMs known from the prior art
do still have some disadvantages. Thus, not every known RM which is
soluble in LC mixtures is suitable for use in PSA displays. In
addition, it is often difficult to find a suitable selection
criterion for the RM besides direct measurement of the pretilt in
the PSA display. The choice of suitable RMs becomes even smaller if
polymerisation by means of UV light without the addition of
photoinitiators is desired, which may be advantageous for certain
applications.
[0023] In addition, the selected combination of LC host mixture/RM
should have the lowest possible rotational viscosity and the best
possible electrical properties. In particular, it should have the
highest possible VHR. In PSA displays, a high VHR after irradiation
with UV light is particularly necessary since UV exposure is a
requisite part of the display production process, but also occurs
as normal exposure during operation of the finished display.
[0024] In particular, it would be desirable to have available novel
materials for PSA displays which produce a particularly small
pretilt angle. Preferred materials here are those which produce a
lower pretilt angle during polymerisation for the same exposure
time than the materials known to date, and/or through the use of
which the (higher) pretilt angle that can be achieved with known
materials can already be achieved after a shorter exposure time.
The production time ("tact time") of the display could thus be
shortened and the costs of the production process reduced.
[0025] A further problem in the production of PSA displays is the
presence or removal of residual amounts of unpolymerised RMs, in
particular after the polymerisation step for production of the
pretilt angle in the display. For example, unreacted RMs of this
type may adversely affect the properties of the display by, for
example, polymerising in an uncontrolled manner during operation
after finishing of the display.
[0026] Thus, the PSA displays known from the prior art often
exhibit the undesired effect of so-called "image sticking" or
"image burn", i.e. the image produced in the LC display by
temporary addressing of individual pixels still remains visible
even after the electric field in these pixels has been switched off
or after other pixels have been addressed.
[0027] This "image sticking" can occur on the one hand if LC host
mixtures having a low VHR are used. The UV component of daylight or
the backlighting can cause undesired decomposition reactions of the
LC molecules therein and thus initiate the production of ionic or
free-radical impurities. These may accumulate, in particular, at
the electrodes or the alignment layers, where they may reduce the
effective applied voltage. This effect can also be observed in
conventional LC displays without a polymer component.
[0028] In addition, an additional "image sticking" effect caused by
the presence of unpolymerised RMs is often observed in PSA
displays. Uncontrolled polymerisation of the residual RMs is
initiated here by UV light from the environment or by the
backlighting. In the switched display areas, this changes the tilt
angle after a number of addressing cycles. As a result, a change in
transmission in the switched areas may occur, while it remains
unchanged in the unswitched areas.
[0029] It is therefore desirable for the polymerisation of the RMs
to proceed as completely as possible during production of the PSA
display and for the presence of unpolymerised RMs in the display to
be excluded as far as possible or reduced to a minimum. Thus, RMs
and LC mixtures are required which enable or support highly
effective and complete polymerisation of the RMs. In addition,
controlled reaction of the residual RM amounts would be desirable.
This would be simpler if the RM polymerised more rapidly and
effectively than the compounds known to date.
[0030] A further problem that has been observed in the operation of
PSA displays is the stability of the pretilt angle. Thus, it was
observed that the pretilt angle, which was generated during display
manufacture by polymerising the RM as described above, does not
remain constant but can deteriorate after the display was subjected
to voltage stress during its operation. This can negatively affect
the display performance, e.g. by increasing the black state
transmission and hence lowering the contrast.
[0031] Another problem to be solved is that the RMs of prior art do
often have high melting points, and do only show limited solubility
in many currently common LC mixtures, and therefore frequently tend
to spontaneously crystallise out of the mixture. In addition, the
risk of spontaneous polymerisation prevents the LC host mixture
being warmed in order to dissolve the polymerisable component,
meaning that the best possible solubility even at room temperature
is necessary. In addition, there is a risk of separation, for
example on introduction of the LC medium into the LC display
(chromatography effect), which may greatly impair the homogeneity
of the display. This is further increased by the fact that the LC
media are usually introduced at low temperatures in order to reduce
the risk of spontaneous polymerisation (see above), which in turn
has an adverse effect on the solubility.
[0032] Another problem observed in prior art is that the use of
conventional LC media in LC displays, including but not limited to
displays of the PSA type, often leads to the occurrence of mura in
the display, especially when the LC medium is filled in the display
cell manufactured using the one drop filling (ODF) method. This
phenomenon is also known as "ODF mura". It is therefore desirable
to provide LC media which lead to reduced ODF mura.
[0033] Another problem observed in prior art is that LC media for
use in PSA displays, including but not limited to displays of the
PSA type, do often exhibit high viscosities and, as a consequence,
high switching times. In order to reduce the viscosity and
switching time of the LC medium, it has been suggested in prior art
to add LC compounds with an alkenyl group. However, it was observed
that LC media containing alkenyl compounds often show a decrease of
the reliability and stability, and a decrease of the VHR especially
after exposure to UV radiation. Especially for use in PSA displays
this is a considerable disadvantage, because the
photo-polymerisation of the RMs in the PSA display is usually
carried out by exposure to UV radiation, which may cause a VHR drop
in the LC medium.
[0034] There is thus still a great demand for PSA displays and LC
media and polymerisable compounds for use in such displays, which
do not show the drawbacks as described above, or only do so to a
small extent, and have improved properties.
[0035] In particular, there is a great demand for PSA displays, and
LC media and polymerisable compounds for use in such PSA displays,
which enable a high specific resistance at the same time as a large
working-temperature range, short response times, even at low
temperatures, and a low threshold voltage, a low pretilt angle, a
multiplicity of grey shades, high contrast and a broad viewing
angle, have high reliability and high values for the "voltage
holding ratio" (VHR) after UV exposure, and, in case of the
polymerisable compounds, have low melting points and a high
solubility in the LC host mixtures. In PSA displays for mobile
applications, it is especially desired to have available LC media
that show low threshold voltage and high birefringence.
[0036] The invention is based on the object of providing novel
suitable materials, in particular RMs and LC media comprising the
same, for use in PSA displays, which do not have the disadvantages
indicated above or do so to a reduced extent.
[0037] In particular, the invention is based on the object of
providing RMs, and LC media comprising them, for use in PSA
displays, which enable very high specific resistance values, high
VHR values, high reliability, low threshold voltages, short
response times, high birefringence, show good UV absorption
especially at longer wavelengths, enable quick and complete
polymerisation of the RMs, allow the generation of a low pretilt
angle as quickly as possible, enable a high stability of the
pretilt even after longer time and/or after UV exposure, reduce or
prevent the occurrence of "image sticking" and "ODF mura" in the
display, and in case of the RMs polymerise as rapidly and
completely as possible and show a high solubility in the LC media
which are typically used as host mixtures in PSA displays.
[0038] A further object of the invention is the provision of novel
RMs, in particular for optical, electro-optical and electronic
applications, and of suitable processes and intermediates for the
preparation thereof.
[0039] These and other objects have been achieved in accordance
with the present invention by materials and processes as described
in the present application. In particular, it has been found,
surprisingly, that the use of RMs of formula I as described
hereinafter allows achieving the advantageous effects as mentioned
above. These compounds are characterized in that they contain a
mesogenic biphenyl core with two or more polymerisable reactive
groups, one or more alkoxy substituents and one or more F or Cl
atoms attached thereto, and wherein all polymerisable reactive
groups have the same meaning.
[0040] It was surprisingly found that the use of these RMs, and of
LC media comprising them, in PSA displays facilitates a quick and
complete UV-photopolymerisation reaction in particular at longer UV
wavelengths in the range from 300-380 nm and especially above 320
nm, even without the addition of photoinitiator, leads to a fast
generation of a large and stable pretilt angle, reduces image
sticking and ODF mura in the display, leads to a high reliability
and a high VHR value after UV photopolymerisation, especially in
case of LC host mixtures containing LC compounds with an alkenyl
group, and enables to achieve fast response times, a low threshold
voltage and a high birefringence.
[0041] In addition, the RMs according to the invention have low
melting points, good solubility in a wide range of LC media,
especially in commercially available LC host mixtures for PSA use,
and a low tendency to crystallisation. Besides, they show good
absorption at longer UV wavelengths, in particular in the range
from 300-380 nm, and enable a quick and complete polymerisation
with small amounts of residual, unreacted RMs in the cell.
[0042] JP 2012-018215 A and WO 2014/174929 A1 disclose hybrid type
RMs which contain at least two different polymerisable reactive
groups and wherein the mesogenic core may also be substituted by an
alkoxy group, but do neither disclose nor suggest RMs as disclosed
and claimed hereinafter.
SUMMARY OF THE INVENTION
[0043] The invention relates to polymerisable compounds of formula
I
##STR00001##
wherein the individual radicals, independently of each other, and
on each occurrence identically or differently, have the following
meanings [0044] P a methacrylate group or an acrylate group,
wherein both groups P have the same meaning, [0045] Sp a single
bond, --(CH.sub.2).sub.p1--, --O--(CH.sub.2).sub.p1--,
--O--CO--(CH.sub.2).sub.p1--, or --CO--O--(CH.sub.2).sub.p1--,
wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is
--O--(CH.sub.2).sub.p1--, --O--CO--(CH.sub.2).sub.p1-- or
--CO--O--(CH.sub.2).sub.p1-- the O-atom or CO-group, respectively,
is linked to the benzene ring, [0046] L.sup.11, L.sup.12 F, CI or
OR, [0047] R straight-chain or branched alkyl with 1 to 4 C atoms
that is optionally fluorinated, [0048] L.sup.13, L.sup.14 the
options for L.sup.11, L.sup.12, or --CN or straight chain, branched
or cyclic alkyl having 1 to 12, preferably 1 to 6, 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 or CI, [0049] r1, r2 0, 1, 2, 3 or 4, wherein r1+r2.gtoreq.2,
[0050] r3, r4 0, 1, 2, 3 or 4, wherein r1+r3.ltoreq.4 and
r2+r4.ltoreq.4, wherein the compounds contain at least group
L.sup.11 or L.sup.12 that is F or CI, and at least one group
L.sup.11 or L.sup.12 that is OR, and with the proviso that the
following compounds are excluded
##STR00002##
[0050] wherein P, Sp, L.sup.11 and L.sup.12 are as defined
above.
[0051] The invention further relates to the use of compounds of
formula I as polymerisable compounds in LC media and LC displays,
especially in the LC medium, active layer or alignment layer of an
LC display, wherein the LC displays are preferably PSA
displays.
[0052] The invention further relates to methods for preparing
compounds of formula I, and to novel intermediates used or obtained
in these methods.
[0053] The invention furthermore relates to an LC medium comprising
one or more compounds of formula I.
[0054] The invention furthermore relates to an LC medium comprising
one or more polymerisable compounds, at least one of which is a
compound of formula I.
[0055] The invention furthermore relates to an LC medium comprising
[0056] a polymerisable component A) comprising, preferably
consisting of, one or more polymerisable compounds, at least one of
which is a compound of formula I, and [0057] a liquid-crystalline
component B), hereinafter also referred to as "LC host mixture",
comprising, preferably consisting of, one or more mesogenic or
liquid-crystalline compounds.
[0058] The liquid-crystalline component B) of an LC medium
according to the present invention is hereinafter also referred to
as "LC host mixture", and preferably comprises one or more,
preferably at least two mesogenic or LC compounds selected from
low-molecular-weight compounds which are unpolymerisable.
[0059] The invention furthermore relates to an LC medium as
described above and below, wherein the LC host mixture or component
B) comprises at least one mesogenic or LC compound comprising an
alkenyl group.
[0060] The invention furthermore relates to an LC medium or LC
display as described above, wherein the compounds of formula I, or
the polymerisable compounds of component A), are polymerised.
[0061] The invention furthermore relates to a process for preparing
an LC medium as described above and below, comprising the steps of
mixing one or more mesogenic or LC compounds, or an LC host mixture
or LC component B) as described above and below, with one or more
compounds of formula I, and optionally with further LC compounds
and/or additives.
[0062] The invention furthermore relates to the use of compounds of
formula I and LC media according to the invention in PSA displays,
in particular the use in PSA displays containing an LC medium, for
the production of a tilt angle in the LC medium by in-situ
polymerisation of the compound(s) of the formula I in the PSA
display, preferably in an electric or magnetic field.
[0063] The invention furthermore relates to an LC display
comprising one or more compounds of formula I or an LC medium
according to the invention, in particular a PSA display,
particularly preferably a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS,
PS-posi-VA or PS-TN display.
[0064] The invention furthermore relates to the use of compounds of
formula I and LC media according to the invention in polymer
stabilised SA-VA displays, and to a polymer stabilised SA-VA
display comprising one or more compounds of formula I or an LC
medium according to the invention.
[0065] The invention furthermore relates to an LC display
comprising a polymer obtainable by polymerisation of one or more
compounds of formula I or of a polymerisable component A) as
described above, or comprising an LC medium according to the
invention, which is preferably a PSA display, very preferably a
PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA or PS-TN
display.
[0066] The invention furthermore relates to an LC display of the
PSA type comprising two substrates, at least one which is
transparent to light, an electrode provided on each substrate or
two electrodes provided on only one of the substrates, and located
between the substrates, a layer of an LC medium that comprises one
or more polymerisable compounds and an LC component as described
above and below, wherein the polymerisable compounds are
polymerised between the substrates of the display.
[0067] The invention furthermore relates to a process for
manufacturing an LC display as described above and below,
comprising the steps of filling or otherwise providing an LC
medium, which comprises one or more polymerisable compounds as
described above and below, between the substrates of the display,
and polymerising the polymerisable compounds.
[0068] The PSA displays according to the invention have two
electrodes, preferably in the form of transparent layers, which are
applied to one or both of the substrates. In some displays, for
example in PS-VA, PS-OCB or PS-TN displays, one electrode is
applied to each of the two substrates. In other displays, for
example in PS-posi-VA, PS-IPS or PS-FFS or PS-UB-FFS displays, both
electrodes are applied to only one of the two substrates.
[0069] In a preferred embodiment the polymerisable component is
polymerised in the LC display while a voltage is applied to the
electrodes of the display.
[0070] The polymerisable compounds of the polymerisable component
are preferably polymerised by photo-polymerisation, very preferably
by UV photo-polymerisation.
[0071] The invention furthermore relates to compounds of formula
II
##STR00003##
wherein Sp, L.sup.11, L.sup.12, L.sup.13, L.sup.14, r1-r4 have the
meanings given in formula I or one of the preferred meanings given
above and below, and Pg denotes OH, a protected hydroxyl group or a
masked hydroxyl group.
[0072] The invention furthermore relates to the use of compounds of
formula II as intermediates in the synthesis of polymerisable
compounds, especially those of formula I.
[0073] The invention furthermore relates to a process for
synthesizing compounds of formula I by esterification or
etherification of the compounds of formula II, wherein Pg denotes
OH, using corresponding acids, acid derivatives, or halogenated
compounds containing a polymerisable group P.
DETAILED DESCRIPTION OF THE INVENTION
[0074] Unless stated otherwise, the compounds of formula I are
preferably selected from achiral compounds.
[0075] 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.
[0076] 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.degree.) 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.degree. 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.
[0077] 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 polymerisation and are also referred
to as "polymerisable group" or "P".
[0078] Unless stated otherwise, the term "polymerisable compound"
as used herein will be understood to mean a polymerisable monomeric
compound.
[0079] 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 polymerisation reaction, as opposed to a
"polymeric compound" or a "polymer".
[0080] As used herein, the term "unpolymerisable compound" will be
understood to mean a compound that does not contain a functional
group that is suitable for polymerisation under the conditions
usually applied for the polymerisation of the RMs.
[0081] 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
behaviour only after mixing with other compounds and/or after
polymerisation. 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.
[0082] 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 polymerisable
group(s) in a polymerisable mesogenic compound.
[0083] Above and below,
##STR00004##
denotes a trans-1,4-cyclohexylene ring, and
##STR00005##
denotes a 1,4-phenylene ring.
[0084] In a group
##STR00006##
the single bond shown between the two ring atoms can be attached to
any free position of the benzene ring.
[0085] Above and below "organic group" denotes a carbon or
hydrocarbon group.
[0086] "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.ident.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.
[0087] "Halogen" denotes F, Cl, Br or I, preferably F or Cl.
[0088] --CO--, --C(.dbd.O)-- and --C(O)-- denote a carbonyl group,
i.e.
##STR00007##
[0089] 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.
[0090] The terms "alkyl", "aryl", "heteroaryl", etc., also
encompass polyvalent groups, for example alkylene, arylene,
heteroarylene, etc.
[0091] 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.
[0092] 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.
[0093] 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.
[0094] Particular preference for carbon and hydrocarbon groups 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.
[0095] 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).dbd.C(R.sup.x)--, --C.ident.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.
[0096] 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.
[0097] 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.
[0098] Preferred alkenyl groups are, for example, ethenyl,
propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl,
heptenyl, cycloheptenyl, octenyl, cyclooctenyl, etc.
[0099] Preferred alkynyl groups are, for example, ethynyl,
propynyl, butynyl, pentynyl, hexynyl, octynyl, etc.
[0100] 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.
[0101] Preferred amino groups are, for example, dimethylamino,
methylamino, methylphenylamino, phenylamino, etc.
[0102] 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.
[0103] 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.
[0104] 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.
[0105] 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.
[0106] 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.
[0107] 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. Heterocyclic rings contain
one or more heteroatoms, preferably selected from Si, O, N, S and
Se.
[0108] 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--.
[0109] 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.
[0110] 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.
[0111] Preferred substituents, hereinafter also referred to as
"L.sup.S", are, for example, F, Cl, Br, I, --CN, --NO.sub.2, --NCO,
--NCS, --OCN, --SCN, --C(.dbd.O)N(R.sup.x).sub.2,
--C(.dbd.O)Y.sup.1, --C(.dbd.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 CI, optionally substituted silyl having 1 to 20 Si
atoms, or optionally substituted aryl having 6 to 25, preferably 6
to 15, C atoms,
[0112] 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
[0113] Y.sup.1 denotes halogen.
[0114] "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.
[0115] Particularly preferred substituents L.sup.S 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.
##STR00008##
is preferably
##STR00009##
in which each L, independently, has one of the meanings given for
L.sup.S above.
[0116] The compounds of formula I show the following advantageous
properties when used in PSA displays: [0117] a tilt suitable for
tilt generation which is inside a certain process window, [0118]
fast polymerization leading to minimal residues of RM after the
UV-process, [0119] a high voltage-holding-ratio after the
UV-process, [0120] sufficient stability against heat, [0121]
sufficient solubility in organic solvents typically used in display
manufacture.
[0122] Preferred compounds of formula I are selected from the
following subformulae:
##STR00010##
wherein P, Sp, R, L.sup.11, L.sup.12, L.sup.13, L.sup.14, r2, r3,
r4 have the meanings given in formula I, r5 is 0, 1, 2 or 3,
r3+r5.ltoreq.3, and r2+r5 is .gtoreq.1, preferably 1, 2 or 3, very
preferably 1 or 2, most preferably 1.
[0123] Especially preferred are compounds of formula I1.
[0124] Preferred compounds of formula I1 are those wherein r3 is 0
and r4 is 0.
[0125] Very preferred compounds of formula I, I1 and I2 are
selected from the following subformulae:
##STR00011## ##STR00012##
wherein P, Sp and R have the meanings given in formula I or one of
the preferred meanings given above and below, and L' is F or CI,
preferably F.
[0126] Preferred compounds are those of formula I1-1, I1-2, I1-4,
I2-1 and I2-2, very preferred those of formula I1-1.
[0127] Very preferred compounds of formula I are selected from the
following subformulae:
##STR00013## ##STR00014## ##STR00015## ##STR00016##
##STR00017##
wherein P, R and L' have the meanings given in formula I1-1, and Sp
has one of the meanings given in formula I which is different from
a single bond.
[0128] Preferred compounds are those of formula I1-1-1, I-1-1-2,
I1-1-3, I1-2-1, I1-2-1, I1-2-3, I1-4-1, I1-4-2, I1-4-3, I2-1-1,
I2-1-2, I2-1-3, I2-2-1, I2-2-2 and I2-2-3, very preferred those of
formula I1-1-1, I1-1-2 and I1-1-3.
[0129] Another preferred embodiment relates to compounds of formula
I1 and I2 wherein r3+r4>0, preferably r3+r4 is 1 or 2.
[0130] Preferred compounds of this preferred embodiment are those
wherein r3+r4>0, preferably r3+r4 is 1 or 2, and L.sup.13 and
L.sup.14 denote F, Cl, CN, alkyl, alkoxy, alkylcarbonyl,
alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1
to 6 C atoms, in which one or more H atoms may optionally be
replaced by F or CI, and very preferably L.sup.13 and L.sup.14
denote F, CI or OR wherein R is as defined above.
[0131] Very preferred compounds of this preferred embodiment are
selected from the following subformulae:
##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022##
##STR00023##
wherein P, Sp and R have the meanings given in formula I or one of
the preferred meanings given above and below, L' is F or CI,
preferably F, and V has one of the meanings given for L.sup.13 in
formula I or one of its preferred meanings given above and
below.
[0132] Preferred compounds of formula I1-6 to I2-14 are those
wherein both groups Sp denote a single bond.
[0133] Further preferred compounds of formula I1-6 to I2-14 are
those wherein one of the two groups Sp is a single bond and the
other is different from a single bond.
[0134] Preferred compounds of formula I and II and their
subformulae are selected from the following preferred embodiments,
including any combination thereof: [0135] P is methacrylate, [0136]
both groups Sp are a single bond, [0137] one of the two groups Sp
is a single bond and the other is --(CH.sub.2).sub.p1--,
--O--(CH.sub.2).sub.p1--, --O--CO--(CH.sub.2).sub.p1, or
--CO--O--(CH.sub.2).sub.p1, wherein p1 is 2, 3, 4, 5 or 6, [0138]
if Sp is different from a single bond, it is selected from
--(CH.sub.2).sub.p1--, --O--(CH.sub.2).sub.p1--,
--O--CO--(CH.sub.2).sub.p1, or --CO--O--(CH.sub.2).sub.p1, wherein
p1 is 2, 3, 4, 5 or 6, [0139] r1+r2 is 2, [0140] r1 is 1 and r2 is
1, [0141] r1 is 2 and r2 is 0, or r1 is 0 and r2 is 2, [0142] r1+r2
is 3, [0143] r1 is 1 and r2 is 2, or r1 is 2 and r2 is 1, [0144] r3
is 0, [0145] r4 is 0, [0146] r3+r4 is 0, [0147] r3+r4 is 1 or 2,
[0148] r2+r5 is 1 or 2, preferably 1, [0149] L.sup.11 and L.sup.12
are selected from F or OR, [0150] R is OCH.sub.3 or
OC.sub.2H.sub.5, preferably OCH.sub.3, [0151] L.sup.11 and L.sup.12
are selected from F, OCH.sub.3 or OC.sub.2H.sub.5, [0152] the
compound contains two groups L.sup.11 and L.sup.12, one of which is
F or Cl, and the other of which is OR, [0153] the compound contains
two groups L.sup.11 and L.sup.12, one of which is F, and the other
of which is OCH.sub.3, [0154] L' is F, [0155] L.sup.13 and L.sup.14
denote F, Cl, CN, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl,
alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 6 C atoms,
in which one or more H atoms may optionally be replaced by F or CI,
[0156] L.sup.13 and L.sup.14 are F, CI or OR wherein R is as
defined above. [0157] L'' is F, Cl, CN, alkyl, alkoxy,
alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or
alkoxycarbonyloxy each having 1 to 6 C atoms, in which one or more
H atoms may optionally be replaced by F or CI, [0158] L'' is F, CI
or OR wherein R is as defined above.
[0159] Preferred compounds of formula II are those selected form
the above preferred subformulae I1-1 to I2-4, I1-1-1 to I2-4-3, and
I1-6 to I2-14 wherein P is replaced by Pg as defined in formula
II.
[0160] Suitable protected hydroxyl groups Pg for use in compounds
of formula II and its subformulae are known to the person skilled
in the art. Preferred protecting groups for hydroxyl groups are
alkyl, alkoxyalkyl, acyl, alkylsilyl, arylsilyl and arylmethyl
groups, especially 2-tetrahydropyranyl, methoxymethyl,
methoxyethoxymethyl, acetyl, triisopropylsilyl,
tert-butyl-dimethylsilyl or benzyl.
[0161] The term "masked hydroxyl group" is understood to mean any
functional group that can be chemically converted into a hydroxyl
group. Suitable masked hydroxyl groups Pg are known to the person
skilled in the art.
[0162] The compounds of formula II are suitable as intermediates
for the preparation of compounds of the formula I and its
subformulae.
[0163] The invention further relates to the use of the compounds of
formula II as intermediates for the preparation of compounds of the
formula I and its subformulae.
[0164] The compounds and intermediates of the formulae I and II and
sub-formulae thereof can be prepared analogously to processes known
to the person skilled in the art and described in standard works of
organic chemistry, such as, for example, in Houben-Weyl, Methoden
der organischen Chemie [Methods of Organic Chemistry],
Thieme-Verlag, Stuttgart.
[0165] For example, compounds of formula I can be synthesised by
esterification or etherification of the intermediates of formula
II, wherein Pg denotes OH, using corresponding acids, acid
derivatives, or halogenated compounds containing a polymerisable
group P.
[0166] For example, acrylic or methacrylic esters can be prepared
by esterification of the corresponding alcohols with acid
derivatives like, for example, (meth)acryloyl chloride or
(meth)acrylic anhydride in the presence of a base like pyridine or
triethyl amine, and 4-(N,N-dimethylamino)pyridine (DMAP).
Alternatively the esters can be prepared by esterification of the
alcohols with (meth)acrylic acid in the presence of a dehydrating
reagent, for example according to Steglich with
dicyclohexylcarbodiimide (DCC),
N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or
N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and
DMAP.
[0167] Further suitable methods are shown in the examples.
[0168] For the production of PSA displays, the polymerisable
compounds contained in the LC medium are polymerised or crosslinked
(if one compound contains two or more polymerisable 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.
[0169] 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.
[0170] A preferred PSA type LC display of the present invention
comprises: [0171] 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, [0172] 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, [0173] an LC layer
disposed between the first and second substrates and including an
LC medium comprising a polymerisable component A and a liquid
crystal component B as described above and below, wherein the
polymerisable component A may also be polymerised.
[0174] 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.
[0175] 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 polymerisable component of the
LC medium is then polymerised for example by UV
photopolymerisation. The polymerisation can be carried out in one
step or in two or more steps.
[0176] The PSA display may comprise further elements, like a colour
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.
[0177] 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.
[0178] Upon polymerisation the polymerisable 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 polymerisable
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.
[0179] The polymerisation can be carried out in one step. It is
also possible firstly to carry out the polymerisation, optionally
while applying a voltage, in a first step in order to produce a
pretilt angle, and subsequently, in a second polymerisation step
without an applied voltage, to polymerise or crosslink the
compounds which have not reacted in the first step ("end
curing").
[0180] Suitable and preferred polymerisation methods are, for
example, thermal or photopolymerisation, preferably
photopolymerisation, in particular UV induced photopolymerisation,
which can be achieved by exposure of the polymerisable compounds to
UV radiation.
[0181] Optionally one or more polymerisation initiators are added
to the LC medium. Suitable conditions for the polymerisation 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 polymerisation are, for example, the commercially
available photoinitiators Irgacure651.RTM., Irgacure184e,
Irgacure907.RTM., Irgacure369.RTM. or Darocure1173.RTM. (Ciba AG).
If a polymerisation initiator is employed, its proportion is
preferably 0.001 to 5% by weight, particularly preferably 0.001 to
1% by weight.
[0182] The polymerisable compounds according to the invention are
also suitable for polymerisation 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 polymerisation can thus also be carried out
without the addition of an initiator. In a preferred embodiment,
the LC medium thus does not contain a polymerisation initiator.
[0183] 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.RTM. series (Ciba AG), such as, for example, Irganox.RTM.
1076. If stabilisers are employed, their proportion, based on the
total amount of RMs or the polymerisable component (component A),
is preferably 10-500,000 ppm, particularly preferably 50-50,000
ppm.
[0184] The polymerisable 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: [0185] the polymerisable 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,
[0186] the polymerisable 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. [0187] the
polymerisable 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.
[0188] 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.
[0189] 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: [0190] the
polymerisable 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
polymerization, [0191] the polymerisable 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, [0192] the polymerisable LC medium is exposed to UV light
having a wavelength of 340 nm or more, and preferably 400 nm or
less.
[0193] 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 .lamda. 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<.lamda.<400 nm. When irradiation with UV light of
wavelength .lamda. of more than 340 nm is desired, UV exposure can
be carried out using a cut-off filter being substantially
transmissive for wavelengths .lamda.>340 nm.
[0194] "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 .lamda., and in case of a cut-off
filter means the wavelengths above (below) the given value of
.lamda..
[0195] 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.
[0196] UV radiation energy is in general from 6 to 100 J, depending
on the production process conditions.
[0197] Preferably the LC medium according to the present invention
does essentially consist of a polymerisable component A), or one or
more polymerisable compounds of formula I, 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.
[0198] Particular preference is given to LC media comprising one,
two or three polymerisable compounds of formula I.
[0199] Preference is furthermore given to LC media in which the
polymerisable component A) comprises exclusively polymerisable
compounds of formula I.
[0200] Preference is furthermore given to LC media in which the
liquid-crystalline component B) or the LC host mixture has a
nematic LC phase, and preferably has no chiral liquid crystal
phase.
[0201] The LC component B), or LC host mixture, is preferably a
nematic LC mixture.
[0202] 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.
[0203] Preferably the proportion of the polymerisable 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%.
[0204] Preferably the proportion of compounds of formula I in the
LC medium is from >0 to <5%, very preferably from >0 to
<1%, most preferably from 0.01 to 0.5%.
[0205] Preferably the proportion of the LC component B) in the LC
medium is from 95 to <100%, very preferably from 99 to
<100%.
[0206] In a preferred embodiment the polymerisable compounds of the
polymerisable component B) are exclusively selected from formula
I.
[0207] In another preferred embodiment the polymerisable component
B) comprises, in addition to the compounds of formula I, one or
more further mesogenic polymerisable compounds ("co-monomers"),
preferably selected from RMs.
[0208] Suitable and preferred mesogenic polymerisable comonomers
are selected from the following formulae:
##STR00024## ##STR00025## ##STR00026## ##STR00027##
##STR00028##
in which the individual radicals have the following meanings:
[0209] P.sup.1, P.sup.2 and P.sup.3 each, independently of one
another, denote an acrylate or methacrylate group, [0210] Sp.sup.1,
Sp.sup.2 and Spa each, independently of one another, denote a
single bond or a spacer group having one of the meanings indicated
above and below for Sp, and particularly preferably denote
--(CH.sub.2).sub.p1--, --(CH.sub.2).sub.p1--O--,
--(CH.sub.2).sub.p1--CO--O--, --(CH.sub.2).sub.p1--O--CO-- or
--(CH.sub.2).sub.p1--O--CO--O--, in which p1 is an integer from 1
to 12, where, in addition, one or more of the radicals
P.sup.1-Sp.sup.1-, P.sup.1-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, [0211] R.sup.aa denotes 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).dbd.C(R.sup.00)--, --C.ident.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), [0212] R.sup.0, R.sup.00
each, independently of one another and identically or differently
on each occurrence, denote H or alkyl having 1 to 12 C atoms,
[0213] R.sup.y and R.sup.z each, independently of one another,
denote H, F, CH.sub.3 or CF.sub.3, [0214] X.sup.1, X.sup.2 and
X.sup.3 each, independently of one another, denote --CO--O--,
--O--CO-- or a single bond, [0215] Z.sup.1 denotes --O--, --CO--,
--C(R.sup.yR.sup.z)-- or --CF.sub.2CF.sub.2--, [0216] Z.sup.2 and
Z.sup.3 each, independently of one another, denote --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, [0217]
L on each occurrence, identically or differently, denotes 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,
preferably F, [0218] L' and L'' each, independently of one another,
denote H, F or CI, [0219] r denotes 0, 1, 2, 3 or 4, [0220] s
denotes 0, 1, 2 or 3, [0221] t denotes 0, 1 or 2, [0222] x denotes
0 or 1.
[0223] Especially preferred are compounds of formulae M2, M13, M17,
M22, M23, M24 and M30.
[0224] Further preferred are trireactive compounds M15 to M30, in
particular M17, M18, M19, M22, M23, M24, M25, M26, M30 and M31.
[0225] In the compounds of formulae M1 to M31 the group
##STR00029##
is preferably
##STR00030##
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 oder OCF.sub.3, especially F or
CH.sub.3.
[0226] Besides the polymerisable compounds described above, the LC
media for use in the LC displays according to the invention
comprise an LC mixture ("host mixture") comprising one or more,
preferably two or more LC compounds which are selected from
low-molecular-weight compounds that are unpolymerisable. These LC
compounds are selected such that they stable and/or unreactive to a
polymerisation reaction under the conditions applied to the
polymerisation of the polymerisable compounds.
[0227] In principle, any LC mixture which is suitable for use in
conventional displays is suitable as host mixture. Suitable LC
mixtures are known to the person skilled in the art and are
described in the literature, for example mixtures in VA displays in
EP 1 378 557 A1 and mixtures for OCB displays in EP 1 306 418 A1
and DE 102 24 046 A1.
[0228] The polymerisable compounds of formula I are especially
suitable for use in an LC host mixture that comprises one or more
mesogenic or LC compounds comprising an alkenyl group (hereinafter
also referred to as "alkenyl compounds"), wherein said alkenyl
group is stable to a polymerisation reaction under the conditions
used for polymerisation of the compounds of formula I and of the
other polymerisable compounds contained in the LC medium. Compared
to RMs known from prior art, the compounds of formula I in such an
LC host mixture exhibit improved properties, like solubility,
reactivity or capability of generating a tilt angle.
[0229] Thus, in addition to the polymerisable compounds of formula
I, the LC medium according to the present invention comprises one
or more mesogenic or liquid crystalline compounds comprising an
alkenyl group, ("alkenyl compound"), where this alkenyl group is
preferably stable to a polymerisation reaction under the conditions
used for the polymerisation of the polymerisable compounds of
formula I or of the other polymerisable compounds contained in the
LC medium.
[0230] The alkenyl groups in the alkenyl compounds are preferably
selected from straight-chain, branched or cyclic alkenyl, in
particular having 2 to 25 C atoms, particularly preferably having 2
to 12 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 and/or Cl.
[0231] Preferred alkenyl groups are straight-chain alkenyl having 2
to 7 C atoms and cyclohexenyl, in particular ethenyl, propenyl,
butenyl, pentenyl, hexenyl, heptenyl, 1,4-cyclohexen-1-yl and
1,4-cyclohexen-3-yl.
[0232] The concentration of compounds containing an alkenyl group
in the LC host mixture (i.e. without any polymerisable compounds)
is preferably from 5% to 100%, very preferably from 20% to 60%.
[0233] Especially preferred are LC mixtures containing 1 to 5,
preferably 1, 2 or 3 compounds having an alkenyl group.
[0234] The mesogenic and LC compounds containing an alkenyl group
are preferably selected from formulae AN and AY as defined
below.
[0235] Besides the polymerisable 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 unpolymerisable. These LC
compounds are selected such that they stable and/or unreactive to a
polymerisation reaction under the conditions applied to the
polymerisation of the polymerisable compounds.
[0236] In a first 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 are those of sections a)-z3)
below: [0237] a) LC medium wherein the component B) or LC host
mixture comprises one or more compounds selected from formulae CY
and PY:
[0237] ##STR00031## [0238] wherein [0239] a denotes 1 or 2, [0240]
b denotes 0 or 1,
##STR00032##
[0240] denotes
##STR00033## [0241] 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.dbd.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, [0242] Z.sup.x and Z.sup.y each,
independently of one another, denote --CH.sub.2CH.sub.2--,
--CH.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--, --CH.sub.2O--,
--OCH.sub.2--, --CO--O--, --O--CO--, --C.sub.2F.sub.4--,
--CF.dbd.CF--, --CH.dbd.CH--CH.sub.2O-- or a single bond,
preferably a single bond, [0243] 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. [0244] 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 CI, 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. [0245] The
compounds of the formula CY are preferably selected from the group
consisting of the following sub-formulae:
[0245] ##STR00034## ##STR00035## ##STR00036## ##STR00037## [0246]
in which a denotes 1 or 2, 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, and (O) denotes an oxygen atom or a single bond.
Alkenyl preferably denotes CH.sub.2.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0247] The compounds of
the formula PY are preferably selected from the group consisting of
the following sub-formulae:
[0247] ##STR00038## ##STR00039## ##STR00040## [0248] 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, and
(O) denotes an oxygen atom or a single bond. Alkenyl preferably
denotes CH.sub.2.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0249] b) LC medium
wherein the component B) or LC host mixture comprises one or more
mesogenic or LC compounds comprising an alkenyl group (hereinafter
also referred to as "alkenyl compounds"), wherein said alkenyl
group is stable to a polymerisation reaction under the conditions
used for polymerisation of the polymerisable compounds contained in
the LC medium. [0250] Preferably the component B) or LC host
mixture comprises one or more alkenyl compounds selected from
formulae AN and AY
[0250] ##STR00041## [0251] in which the individual radicals, on
each occurrence identically or differently, and each, independently
of one another, have the following meaning:
[0251] ##STR00042## [0252] 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, [0253] 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.dbd.CH--, --CO--,
--OCO-- or --COO-- in such a way that O atoms are not linked
directly to one another, [0254] Z.sup.x --CH.sub.2CH.sub.2--,
--CH.dbd.CH--, --CF.sub.2O--, --OCF.sub.2--, --CH.sub.2O--,
--OCH.sub.2--, --CO--O--, --O--CO--, --C.sub.2F.sub.4--,
--CF.dbd.CF--, --CH.dbd.CH--CH.sub.2O--, or a single bond,
preferably a single bond, [0255] L.sup.1,2 H, F, Cl, OCF.sub.3,
CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, preferably H, F or Cl,
[0256] x 1 or 2, [0257] z 0 or 1. [0258] Preferred compounds of
formula AN and AY are those wherein R.sup.A2 is selected from
ethenyl, propenyl, butenyl, pentenyl, hexenyl and heptenyl. [0259]
In a preferred embodiment the component B) or LC host mixture
comprises one or more compounds of formula AN selected from the
following sub-formulae:
[0259] ##STR00043## [0260] 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.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0261] Preferably the
component B) or LC host mixture comprises one or more compounds
selected from formulae AN1, AN2, AN3 and AN6, very preferably one
or more compounds of formula AN1. [0262] In another preferred
embodiment the component B) or LC host mixture comprises one or
more compounds of formula AN selected from the following
sub-formulae:
[0262] ##STR00044## [0263] 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. [0264] In another preferred embodiment the
component B) or LC host mixture comprises one or more compounds
selected from the following sub-formulae:
[0264] ##STR00045## [0265] Most preferred are compounds of formula
AN1a2 and AN1a5. [0266] In another preferred embodiment the
component B) or LC host mixture comprises one or more compounds of
formula AY selected from the following sub-formulae:
[0266] ##STR00046## ##STR00047## ##STR00048## [0267] in which alkyl
and alkyl* each, independently of one another, denote a
straight-chain alkyl radical having 1-6 C atoms, "(0)" denotes an
0-atom or a single bond, 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.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0268] In another
preferred embodiment the component B) or LC host mixture comprises
one or more compounds of formula AY selected from the following
sub-formulae:
[0268] ##STR00049## [0269] in which m and n each, independently of
one another, denote 1, 2, 3, 4, 5 or 6, and alkenyl denotes
CH.sub.2.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0270] Preferably the
proportion of compounds of formula AN and AY in the LC medium is
from 2 to 70% by weight, very preferably from 5 to 60% by weight,
most preferably from 10 to 50% by weight. [0271] Preferably the LC
medium or LC host mixture contains 1 to 5, preferably 1, 2 or 3
compounds selected from formulae AN and AY. [0272] In another
preferred embodiment of the present invention the LC medium
comprises one or more compounds of formula AY14, very preferably of
AY14a. The proportion of compounds of formula AY14 or AY14a in the
LC medium is preferably 3 to 20% by weight. [0273] The addition of
alkenyl compounds of formula AN and/or AY enables a reduction of
the viscosity and response time of the LC medium. [0274] c) LC
medium wherein the component B) or LC host mixture comprises one or
more compounds of the following formula:
[0274] ##STR00050## [0275] in which the individual radicals have
the following meanings:
##STR00051##
[0275] denotes
##STR00052##
denotes
##STR00053## [0276] 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.dbd.CH--, --CO--, --O--CO-- or --CO--O-- in such a
way that O atoms are not linked directly to one another, [0277]
Z.sup.y denotes --CH.sub.2CH.sub.2--, --CH.dbd.CH--, --CF.sub.2O--,
--OCF.sub.2--, --CH.sub.2O--, --OCH.sub.2--, --CO--O--, --O--CO--,
--C.sub.2F.sub.4--, --CF.dbd.CF--, --CH.dbd.CH--CH.sub.2O-- or a
single bond, preferably a single bond. [0278] The compounds of the
formula ZK are preferably selected from the group consisting of the
following sub-formulae:
[0278] ##STR00054## [0279] 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.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0280] Especially
preferred are compounds of formula ZK1. [0281] Particularly
preferred compounds of formula ZK are selected from the following
sub-formulae:
[0281] ##STR00055## [0282] wherein the propyl, butyl and pentyl
groups are straight-chain groups. [0283] Most preferred are
compounds of formula ZK1a. [0284] d) LC medium wherein component B)
or the LC host mixture additionally comprises one or more compounds
of the following formula:
[0284] ##STR00056## [0285] in which the individual radicals on each
occurrence, identically or differently, have the following
meanings: [0286] 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.dbd.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,
##STR00057##
[0286] denotes
##STR00058##
denotes and
##STR00059## [0287] e denotes 1 or 2. [0288] The compounds of the
formula DK are preferably selected from the group consisting of the
following sub-formulae:
[0288] ##STR00060## [0289] 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.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0290] e) LC medium
wherein component B) or the LC host mixture additionally comprises
one or more compounds of the following formula:
[0290] ##STR00061## [0291] in which the individual radicals have
the following meanings:
##STR00062##
[0291] denotes
##STR00063## [0292] with at least one ring F being different from
cyclohexylene, [0293] f denotes 1 or 2, [0294] 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.dbd.CH--, --CO--, --OCO-- or --COO--
in such a way that O atoms are not linked directly to one another,
[0295] Z.sup.x denotes --CH.sub.2CH.sub.2--, --CH.dbd.CH--,
--CF.sub.2O--, --OCF.sub.2--, --CH.sub.2O--, --OCH.sub.2--,
--CO--O--, --O--CO--, --C.sub.2F.sub.4--, --CF.dbd.CF--,
--CH.dbd.CH--CH.sub.2O-- or a single bond, preferably a single
bond, [0296] 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. [0297] 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. [0298] The compounds of the formula LY are
preferably selected from the group consisting of the following
sub-formulae:
[0298] ##STR00064## ##STR00065## ##STR00066## [0299] 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.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0300] f) LC medium
wherein component B) or the LC host mixture additionally comprises
one or more compounds selected from the group consisting of the
following formulae:
[0300] ##STR00067## [0301] in which alkyl denotes C.sub.1-6-alkyl,
Lx denotes H or F, and X denotes F, Cl, OCF.sub.3, OCHF.sub.2 or
OCH.dbd.CF.sub.2. Particular preference is given to compounds of
the formula G1 in which X denotes F. [0302] g) LC medium wherein
component B) or the LC host mixture additionally comprises one or
more compounds selected from the group consisting of the following
formulae:
[0302] ##STR00068## ##STR00069## [0303] 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. [0304] h) LC
medium wherein component B) or the LC host mixture additionally
comprises one or more biphenyl compounds selected from the group
consisting of the following formulae:
[0304] ##STR00070## [0305] 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.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0306] The proportion of
the biphenyls of the formulae B1 to B3 in the LC host mixture is
preferably at least 3% by weight, in particular .gtoreq.5% by
weight. [0307] The compounds of the formula B2 are particularly
preferred. [0308] The compounds of the formulae B1 to B3 are
preferably selected from the group consisting of the following
sub-formulae:
[0308] ##STR00071## [0309] 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. [0310] i) LC medium wherein component B)
or the LC host mixture additionally comprises one or more terphenyl
compounds of the following formula:
[0310] ##STR00072## [0311] in which R.sup.5 and R.sup.6 each,
independently of one another, have one of the meanings indicated
above, and
[0311] ##STR00073## [0312] each, independently of one another,
denote
[0312] ##STR00074## [0313] in which L.sup.5 denotes F or CI,
preferably F, and L.sup.6 denotes F, Cl, OCF.sub.3, CF.sub.3,
CH.sub.3, CH.sub.2F or CHF.sub.2, preferably F. [0314] The
compounds of the formula T are preferably selected from the group
consisting of the following sub-formulae:
[0314] ##STR00075## ##STR00076## ##STR00077## [0315] 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.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0316] R preferably
denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy,
ethoxy, propoxy, butoxy or pentoxy. [0317] The LC host mixture
according to the invention preferably comprises the terphenyls of
the formula T and the preferred sub-formulae thereof in an amount
of 0.5-30% by weight, in particular 1-20% by weight. [0318]
Particular preference is given to compounds of the formulae T1, T2,
T3 and T21. In these compounds, R preferably denotes alkyl,
furthermore alkoxy, each having 1-5 C atoms. [0319] The terphenyls
are preferably employed in LC media according to the invention if
the .DELTA.n value of the mixture is to be 0.1. Preferred LC media
comprise 2-20% by weight of one or more terphenyl compounds of the
formula T, preferably selected from the group of compounds T1 to
T22. [0320] k) LC medium wherein component B) or the LC host
mixture additionally comprises one or more quaterphenyl compounds
selected from the group consisting of the following formulae:
[0320] ##STR00078## [0321] wherein [0322] R.sup.Q is 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, [0323] 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, [0324] L.sup.Q1 to L.sup.Q6 independently of each
other are H or F, with at least one of L.sup.Q1 to L.sup.Q6 being
F. [0325] Preferred compounds of formula Q are those wherein
R.sup.Q denotes straight-chain alkyl with 2 to 6 C-atoms, very
preferably ethyl, n-propyl or n-butyl. [0326] Preferred compounds
of formula Q are those wherein L.sup.Q3 and L.sup.Q4 are F. Further
preferred compounds of formula Q are those wherein L.sup.Q3,
L.sup.Q4 and one or two of L.sup.Q1 and L.sup.Q2 are F. [0327]
Preferred compounds of formula Q are those wherein X.sup.Q denotes
F or OCF.sub.3, very preferably F. [0328] The compounds of formula
Q are preferably selected from the following subformulae
[0328] ##STR00079## [0329] 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. [0330]
Especially preferred are compounds of formula Q1, in particular
those wherein R.sup.0 is n-propyl. [0331] Preferably the proportion
of compounds of formula Q in the LC host mixture is from >0 to
5% by weight, very preferably from 0.1 to 2% by weight, most
preferably from 0.2 to 1.5% by weight. [0332] Preferably the LC
host mixture contains 1 to 5, preferably 1 or 2 compounds of
formula Q. [0333] The addition of quaterphenyl compounds of formula
Q to the LC host mixture enables to reduce ODF mura, whilst
maintaining high UV absorption, enabling quick and complete
polymerisation, enabling strong and quick tilt angle generation,
and increasing the UV stability of the LC medium. [0334] Besides,
the addition of compounds of formula Q, which have positive
dielectric anisotropy, to the LC medium with negative dielectric
anisotropy allows a better control of the values of the dielectric
constants .epsilon..sub..parallel. and .epsilon..sub..perp., and in
particular enables to achieve a high value of the dielectric
constant .epsilon..sub..parallel. while keeping the dielectric
anisotropy .DELTA..epsilon. constant, thereby reducing the
kick-back voltage and reducing image sticking. [0335] I) LC medium
wherein component B) or the LC host mixture additionally comprises
one or more compounds of formula C:
[0335] ##STR00080## [0336] wherein [0337] R.sup.C denotes 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, [0338] X.sup.C denotes F, Cl, halogenated alkyl or
alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy
having 2 to 6 C atoms, [0339] L.sup.C1, L.sup.C2 independently of
each other denote H or F, with at least one of L.sup.C1 and
L.sup.C2 being F. [0340] Preferred compounds of formula C are those
wherein R.sup.C denotes straight-chain alkyl with 2 to 6 C-atoms,
very preferably ethyl, n-propyl or n-butyl. [0341] Preferred
compounds of formula C are those wherein L.sup.C1 and L.sup.C2 are
F. [0342] Preferred compounds of formula C are those wherein
X.sup.C denotes F or OCF.sub.3, very preferably F. [0343] Preferred
compounds of formula C are selected from the following formula
[0343] ##STR00081## [0344] wherein R.sup.C has one of the meanings
of formula C or one of its preferred meanings given above and
below, and is preferably ethyl, n-propyl or n-butyl, very
preferably n-propyl. [0345] Preferably the proportion of compounds
of formula C in the LC host mixture is from >0 to .ltoreq.10% by
weight, very preferably from 0.1 to 8% by weight, most preferably
from 0.2 to 5% by weight. [0346] Preferably the LC host mixture
contains 1 to 5, preferably 1, 2 or 3 compounds of formula C.
[0347] The addition of compounds of formula C, which have positive
dielectric anisotropy, to the LC medium with negative dielectric
anisotropy allows a better control of the values of the dielectric
constants .epsilon..sub..parallel. and .epsilon..sub..perp., and in
particular enables to achieve a high value of the dielectric
constant .epsilon..sub..parallel. while keeping the dielectric
anisotropy .DELTA..epsilon. constant, thereby reducing the
kick-back voltage and reducing image sticking. Besides, the
addition of compounds of formula C enables to reduce the viscosity
and the response time of the LC medium. [0348] m) LC medium wherein
component B) or the LC host mixture additionally comprises one or
more compounds selected from the group consisting of the following
formulae:
[0348] ##STR00082## [0349] 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. [0350] Preferred
media comprise one or more compounds selected from the formulae O1,
O3 and O4. [0351] n) LC medium wherein component B) or the LC host
mixture additionally comprises one or more compounds of the
following formula:
[0351] ##STR00083## [0352] in which
##STR00084##
[0352] denotes
##STR00085## [0353] 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. [0354] Particularly preferred compounds of the formula FI
are selected from the group consisting of the following
sub-formulae:
[0354] ##STR00086## [0355] 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. [0356] o) LC medium
wherein component B) or the LC host mixture additionally comprises
one or more compounds selected from the group consisting of the
following formulae:
[0356] ##STR00087## [0357] 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. [0358] p) LC medium wherein component
B) or the LC host mixture additionally 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:
[0358] ##STR00088## ##STR00089## [0359] in which [0360] 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.dbd.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, [0361] 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 [0362] Z.sup.1
and Z.sup.2 each, independently of one another, denote
--C.sub.2H.sub.4--, --CH.dbd.CH--, --(CH.sub.2).sub.4--,
--(CH.sub.2).sub.3O--, --O(CH.sub.2).sub.3--,
--CH.dbd.CH--CH.sub.2CH.sub.2--, --CH.sub.2CH.sub.2CH.dbd.CH--,
--CH.sub.2O--, --OCH.sub.2--, --CO--O--, --O--CO--,
--C.sub.2F.sub.4--, --CF.dbd.CF--, --CF.dbd.CH--, --CH.dbd.CF--,
--CH.sub.2-- or a single bond. [0363] q) LC medium wherein
component B) or the LC host mixture additionally comprises one or
more difluorodibenzochromans and/or chromans of the following
formulae:
[0363] ##STR00090## [0364] in which [0365] R.sup.11 and R.sup.12
each, independently of one another, have one of the meanings
indicated above for R.sup.11, [0366] ring M is
trans-1,4-cyclohexylene or 1,4-phenylene, [0367] Z.sup.m
--C.sub.2H.sub.4--, --CH.sub.2O--, --OCH.sub.2--, --CO--O-- or
--O--CO--, [0368] c is 0, 1 or 2, [0369] preferably in amounts of 3
to 20% by weight, in particular in amounts of 3 to 15% by weight.
[0370] Particularly preferred compounds of the formulae BC, CR and
RC are selected from the group consisting of the following
sub-formulae:
[0370] ##STR00091## ##STR00092## ##STR00093## [0371] 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.dbd.CH--, CH.sub.2.dbd.CHCH.sub.2CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.3-0H.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0372] Very particular
preference is given to LC host mixtures comprising one, two or
three compounds of the formula BC-2. [0373] r) LC medium wherein
component B) or the LC host mixture additionally comprises one or
more fluorinated phenanthrenes and/or dibenzofurans of the
following formulae:
[0373] ##STR00094## [0374] 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. [0375] Particularly preferred compounds of the formulae PH
and BF are selected from the group consisting of the following
sub-formulae:
[0375] ##STR00095## [0376] in which R and R' each, independently of
one another, denote a straight-chain alkyl or alkoxy radical having
1-7 C atoms. [0377] s) LC medium wherein component B) or the LC
host mixture additionally comprises one or more monocyclic
compounds of the following formula
[0377] ##STR00096## [0378] wherein [0379] 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.dbd.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, [0380] 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. [0381]
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 CI, [0382] The compounds of
the formula Y are preferably selected from the group consisting of
the following sub-formulae:
[0382] ##STR00097## [0383] 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, Alkenyl and Alkenyl* each, independently of one
another, denote a straight-chain alkenyl radical having 2-6 C
atoms, and 0 denotes an oxygen atom or a single bond. Alkenyl and
Alkenyl* preferably denote CH.sub.2.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--. [0384] Particularly
preferred compounds of the formula Y are selected from the group
consisting of the following sub-formulae:
[0384] ##STR00098## [0385] wherein Alkoxy preferably denotes
straight-chain alkoxy with 3, 4, or C atoms. [0386] t) LC medium
which, apart from the polymerisable compounds as described above
and below, does not contain a compound which contains a terminal
vinyloxy group (--O--CH.dbd.CH.sub.2). [0387] u) LC medium wherein
component B) or the LC host mixture 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 LC host 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%.
[0388] v) LC medium wherein component B) or the LC host mixture
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 LC
host 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%. [0389] w) LC medium wherein
component B) or the LC host mixture 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 LC host 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%. [0390] x) LC medium in which the
proportion of compounds of the formulae CY, PY and ZK in the LC
host mixture as a whole is greater than 70%, preferably greater
than 80%. [0391] y) LC medium in which the LC host mixture contains
one or more compounds containing an alkenyl group, preferably
selected from formulae AN and AY, very preferably selected from
formulae AN1, AN3, AN6 and AY14, most preferably from formulae
AN1a, AN3a, AN6a and AY14. The concentration of these compounds in
the LC host mixture is preferably from 2 to 70%, very preferably
from 3 to 55%. [0392] z) LC medium wherein component B) or the LC
host mixture 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 LC host 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%.
[0393] z1) LC medium wherein component B) or the LC host mixture
contains one or more, preferably 1, 2 or 3, compounds selected from
formulae T1, T2 and T5, very preferably from formula T2. The
content of these compounds in the LC host mixture as a whole is
preferably 1 to 20%. [0394] z2) LC medium in which the LC host
mixture contains one or more compounds selected from formulae CY
and PY, one or more compounds selected from formulae AN and AY, and
one or more compounds selected from formulae T and Q. [0395] z3) LC
medium in which the LC host mixture contains one or more,
preferably 1, 2 or 3, compounds of formula BF1, and one or more,
preferably 1, 2 or 3, compounds selected from formulae AY14, AY15
and AY16, very preferably of formula AY14. The proportion of the
compounds of formula AY14-AY16 in the LC host mixture is preferably
from 2 to 35%, very preferably from 3 to 30%. The proportion of the
compounds of formula BF1 in the LC host mixture is preferably from
0.5 to 20%, very preferably from 1 to 15%. Further preferably the
LC host mixture according to this preferred embodiment contains one
or more, preferably 1, 2 or 3 compounds of formula T, preferably
selected from formula T1, T2 and T5, very preferably from formula
T2 or T5. The proportion of the compounds of formula T in the LC
host mixture medium is preferably from 0.5 to 15%, very preferably
from 1 to 10%.
[0396] In a second preferred embodiment the LC medium contains an
LC host mixture based on compounds with positive dielectric
anisotropy. Such LC media are especially suitable for use in
PS-OCB-, PS-TN-, PS-Posi-VA-, PS-IPS- or PS-FFS-displays.
[0397] Preferred LC medium for this embodiment comprise an LC host
mixture comprising one or more compounds of the formula A or B
below:
##STR00099##
in which the individual radicals have, independently of each other
and on each occurrence identically or differently, the following
meanings:
##STR00100##
each, independently of one another, and on each occurrence,
identically or differently
##STR00101## [0398] R.sup.21, R.sup.31 each, independently of one
another, 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, [0399] X.sup.0 F, Cl, halogenated alkyl
or alkoxy having 1 to 6 C atoms or halogenated alkenyl or
alkenyloxy having 2 to 6 C atoms, [0400] Z.sup.31
--CH.sub.2CH.sub.2--, --CF.sub.2CF.sub.2--, --COO--,
trans-CH.dbd.CH--, trans-CF.dbd.CF--, --CH.sub.2O-- or a single
bond, preferably --CH.sub.2CH.sub.2--, --COO--, trans-CH.dbd.CH--
or a single bond, particularly preferably --COO--,
trans-CH.dbd.CH-- or a single bond, [0401] L.sup.21, L.sup.22,
L.sup.31, L.sup.32 each, independently of one another, H or F,
[0402] g 0, 1, 2 or 3.
[0403] In the compounds of formula A and B, X.sup.0 is preferably
F, Cl, CF.sub.3, CHF.sub.2, OCF.sub.3, OCHF.sub.2, OCFHCF.sub.3,
OCFHCHF.sub.2, OCFHCHF.sub.2, OCF.sub.2CH.sub.3,
OCF.sub.2CHF.sub.2, OCF.sub.2CHF.sub.2, OCF.sub.2CF.sub.2CHF.sub.2,
OCF.sub.2CF.sub.2CHF.sub.2, OCFHCF.sub.2CF.sub.3,
OCFHCF.sub.2CHF.sub.2, OCF.sub.2CF.sub.2CF.sub.3,
OCF.sub.2CF.sub.2CCIF.sub.2, OCCIFCF.sub.2CF.sub.3 or
CH.dbd.CF.sub.2, very preferably F or OCF.sub.3, most preferably
F.
[0404] In the compounds of formula A and B, R.sup.21 and R.sup.31
are preferably selected from straight-chain alkyl or alkoxy with 1,
2, 3, 4, 5 or 6 C atoms, and straight-chain alkenyl with 2, 3, 4,
5, 6 or 7 C atoms.
[0405] In the compounds of formula A and B, g is preferably 1 or
2.
[0406] In the compounds of formula B, Z.sup.31 is preferably COO,
trans-CH.dbd.CH or a single bond, very preferably COO or a single
bond.
[0407] Preferably component B) of the LC medium of this embodiment
comprises one or more compounds of formula A selected from the
group consisting of the following formulae:
##STR00102##
in which A.sup.21, R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have
the meanings given in formula A, L.sup.23 and L.sup.24 each,
independently of one another, are H or F, and X.sup.0 is preferably
F. Particularly preferred are compounds of formulae A1 and A2.
[0408] Particularly preferred compounds of formula A1 are selected
from the group consisting of the following subformulae:
##STR00103##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning
given in formula A1, L.sup.23, L.sup.24, L.sup.25 and L.sup.26 are
each, independently of one another, H or F, and X.sup.0 is
preferably F.
[0409] Very particularly preferred compounds of formula A1 are
selected from the group consisting of the following
subformulae:
##STR00104##
[0410] In which R.sup.21 is as defined in formula A1.
[0411] Particularly preferred compounds of formula A2 are selected
from the group consisting of the following subformulae:
##STR00105## ##STR00106##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning
given in formula A2, L.sup.23, L.sup.24, L.sup.25 and L.sup.26
each, independently of one another, are H or F, and X.sup.0 is
preferably F.
[0412] Very particularly preferred compounds of formula A2 are
selected from the group consisting of the following
subformulae:
##STR00107## ##STR00108##
in which R.sup.21 and X.sup.0 are as defined in formula A2.
[0413] Particularly preferred compounds of formula A3 are selected
from the group consisting of the following subformulae:
##STR00109##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning
given in formula A3, and X.sup.0 is preferably F.
[0414] Particularly preferred compounds of formula A4 are selected
from the group consisting of the following subformulae:
##STR00110##
in which R.sup.21 is as defined in formula A4.
[0415] Preferably component B) of the LC medium of this embodiment
comprises one or more compounds of formula B selected from the
group consisting of the following formulae:
##STR00111##
in which g, A.sup.31, A.sup.32, R.sup.31, X.sup.0, L.sup.31 and
L.sup.32 have the meanings given in formula B, and X.sup.0 is
preferably F. Particularly preferred are compounds of formulae B1
and B2.
[0416] Particularly preferred compounds of formula B1 are selected
from the group consisting of the following subformulae:
##STR00112##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning
given in formula B1, and X.sup.0 is preferably F.
[0417] Very particularly preferred compounds of formula B1a are
selected from the group consisting of the following
subformulae:
##STR00113##
in which R.sup.31 is as defined in formula B1.
[0418] Very particularly preferred compounds of formula B1b are
selected from the group consisting of the following
subformulae:
##STR00114##
in which R.sup.31 is as defined in formula B1.
[0419] Particularly preferred compounds of formula B2 are selected
from the group consisting of the following subformulae:
##STR00115## ##STR00116##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning
given in formula B2, L.sup.33, L.sup.34, L.sup.35 and L.sup.36 are
each, independently of one another, H or F, and X.sup.0 is
preferably F.
[0420] Very particularly preferred compounds of formula B2 are
selected from the group consisting of the following
subformulae:
##STR00117##
in which R.sup.31 is as defined in formula B2.
[0421] Very particularly preferred compounds of formula B2b are
selected from the group consisting of the following subformulae
##STR00118##
in which R.sup.31 is as defined in formula B2.
[0422] Very particularly preferred compounds of formula B2c are
selected from the group consisting of the following
subformulae:
##STR00119##
in which R.sup.31 is as defined in formula B2.
[0423] Very particularly preferred compounds of formula B2d and B2e
are selected from the group consisting of the following
subformulae:
##STR00120##
in which R.sup.31 is as defined in formula B2.
[0424] Very particularly preferred compounds of formula B2f are
selected from the group consisting of the following
subformulae:
##STR00121##
in which R.sup.31 is as defined in formula B2.
[0425] Very particularly preferred compounds of formula B2g are
selected from the group consisting of the following
subformulae:
##STR00122##
in which R.sup.31 is as defined in formula B2.
[0426] Very particularly preferred compounds of formula B2h are
selected from the group consisting of the following
subformulae:
##STR00123##
in which R.sup.31 is as defined in formula B2.
[0427] Very particularly preferred compounds of formula B2i are
selected from the group consisting of the following
subformulae:
##STR00124##
in which R.sup.31 is as defined in formula B2.
[0428] Very particularly preferred compounds of formula B2k are
selected from the group consisting of the following
subformulae:
##STR00125##
in which R.sup.31 is as defined in formula B2.
[0429] Very particularly preferred compounds of formula B21 are
selected from the group consisting of the following
subformulae:
##STR00126##
in which R.sup.31 is as defined in formula B2.
[0430] Alternatively to, or in addition to, the compounds of
formula B1 and/or B2 component B) of the LC medium may also
comprise one or more compounds of formula B3 as defined above.
[0431] Particularly preferred compounds of formula B3 are selected
from the group consisting of the following subformulae:
##STR00127##
in which R.sup.31 is as defined in formula B3.
[0432] Preferably component B) of the LC medium in this embodiment
comprises, in addition to the compounds of formula A and/or B, one
or more compounds of formula C
##STR00128##
in which the individual radicals have the following meanings:
##STR00129##
each, independently of one another, and on each occurrence,
identically or differently
##STR00130## [0433] R.sup.41, R.sup.42 each, independently of one
another, 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, [0434] Z.sup.41, Z.sup.42 each,
independently of one another, --CH.sub.2CH.sub.2--, --COO--,
trans-CH.dbd.CH--, trans-CF.dbd.CF--, --CH.sub.2O--, --CF.sub.2O--,
--C.ident.C-- or a single bond, preferably a single bond, [0435] h
0, 1, 2 or 3.
[0436] In the compounds of formula C, R.sup.41 and R.sup.42 are
preferably selected from straight-chain alkyl or alkoxy with 1, 2,
3, 4, 5 or 6 C atoms, and straight-chain alkenyl with 2, 3, 4, 5, 6
or 7 C atoms.
[0437] In the compounds of formula C, h is preferably 0, 1 or
2.
[0438] In the compounds of formula C, Z.sup.41 and Z.sup.42 are
preferably selected from COO, trans-CH.dbd.CH and a single bond,
very preferably from COO and a single bond.
[0439] Preferred compounds of formula C are selected from the group
consisting of the following subformulae:
##STR00131## ##STR00132##
wherein R.sup.41 and R.sup.42 have the meanings given in formula U,
and preferably denote each, independently of one another, alkyl,
alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C
atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl
with 2 to 7 C atoms.
[0440] Further preferably component B) of the LC medium in this
embodiment comprises, in addition to the compounds of formula A
and/or B, and optionally compound of the formula C, one or more
compounds of formula D
##STR00133##
in which A.sup.41, A.sup.42, Z.sup.41, Z.sup.42, R.sup.41, R.sup.42
and h have the meanings given in formula C above or one of the
preferred meanings given above.
[0441] Preferred compounds of formula D are selected from the group
consisting of the following subformulae:
##STR00134##
in which R.sup.41 and R.sup.42 have the meanings given in formula D
and R.sup.41 preferably denotes alkyl bedeutet, and in formula D1
R.sup.42 preferably denotes alkenyl, particularly preferably
--(CH.sub.2).sub.2--CH.dbd.CH--CH.sub.3, and in formula D2 R.sup.42
preferably denotes alkyl, --(CH.sub.2).sub.2--CH.dbd.CH.sub.2 or
--(CH.sub.2).sub.2--CH.dbd.CH--CH.sub.3.
[0442] Further preferably component B) of the LC medium in this
embodiment comprises, in addition to the compounds of formula A
and/or B, and optionally C and/or D, one or more compounds of
formula E containing an alkenyl group
##STR00135##
in which the individual radicals, on each occurrence identically or
differently, each, independently of one another, have the following
meaning:
##STR00136## [0443] RA.sup.1 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, [0444] 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.dbd.CH--, --CO--, --OCO-- or
--COO-- in such a way that O atoms are not linked directly to one
another, [0445] x 1 or 2. [0446] R.sup.A2 is preferably
straight-chain alkyl or alkoxy having 1 to 8 C atoms or
straight-chain alkenyl having 2 to 7 C atoms.
[0447] Preferred compounds of formula E are selected from the
following sub-formulae:
##STR00137##
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.dbd.CH--,
CH.sub.2.dbd.CHCH.sub.2CH.sub.2--, CH.sub.3--CH.dbd.CH--,
CH.sub.3--CH.sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.2--CH.dbd.CH--,
CH.sub.3--(CH.sub.2).sub.3--CH.dbd.CH-- or
CH.sub.3--CH.dbd.CH--(CH.sub.2).sub.2--.
[0448] Very preferred compounds of the formula E are selected from
the following sub-formulae:
##STR00138##
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.
[0449] Very particularly preferred compounds of the formula E are
selected from the following sub-formulae:
##STR00139##
[0450] Most preferred are compounds of formula E1a2, E1a5, E3a1 and
E6a1.
[0451] Further preferably component B) of the LC medium in this
embodiment comprises, in addition to the compounds of formula A
and/or B, and optionally C, D and/or E, one or more compounds of
formula F
##STR00140##
in which the individual radicals have, independently of each other
and on each occurrence identically or differently, the following
meanings:
##STR00141##
denote
##STR00142## [0452] R.sup.21, R.sup.31 each, independently of one
another, 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, [0453] X.sup.0 F, Cl, halogenated alkyl
or alkoxy having 1 to 6 C atoms or halogenated alkenyl or
alkenyloxy having 2 to 6 C atoms, [0454] Z.sup.21
--CH.sub.2CH.sub.2--, --CF.sub.2CF.sub.2--, --COO--,
trans-CH.dbd.CH--, trans-CF.dbd.CF--, --CH.sub.2O-- or a single
bond, preferably --CH.sub.2CH.sub.2--, --COO--, trans-CH.dbd.CH--
or a single bond, particularly preferably --COO--,
trans-CH.dbd.CH-- or a single bond, [0455] L.sup.21, L.sup.22,
L.sup.23, L.sup.24 each, independently of one another, H or F,
[0456] g 0, 1, 2 or 3.
[0457] Particularly preferred compounds of formula F are selected
from the group consisting of the following formulae:
##STR00143##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning
given in formula F, L.sup.25 and L.sup.26 are each, independently
of one another, H or F, and X.sup.0 is preferably F.
[0458] Very particularly preferred compounds of formula F1-F3 are
selected from the group consisting of the following
subformulae:
##STR00144##
[0459] In which R.sup.21 is as defined in formula F1.
[0460] The concentration of the compounds of formula A and B in the
LC host mixture is preferably from 2 to 60%, very preferably from 3
to 45%, most preferably from 4 to 35%.
[0461] The concentration of the compounds of formula C and D in the
LC host mixture is preferably from 2 to 70%, very preferably from 5
to 65%, most preferably from 10 to 60%.
[0462] The concentration of the compounds of formula E in the LC
host mixture is preferably from 5 to 50%, very preferably from 5 to
35%.
[0463] The concentration of the compounds of formula F in the LC
host mixture is preferably from 2 to 30%, very preferably from 5 to
20%.
[0464] Further preferred embodiments of this second preferred
embodiment of the present invention are listed below, including any
combination thereof. [0465] 2a) The LC host mixture comprises one
or more compounds of formula A and/or B with high positive
dielectric anisotropy, preferably with .DELTA..epsilon.>15.
[0466] 2b) The LC host mixture comprises one or more compounds
selected from the group consisting of formulae A1a2, A1b1, A1d1,
A1f1, A2a1, A2h1, A212, A2k1, B2h3, B2l1, F1a. The proportion of
these compounds in the LC host mixture is preferably from 4 to 40%,
very preferably from 5 to 35%. [0467] 2c) The LC host mixture
comprises one or more compounds selected from the group consisting
of formulae B2c1, B2c4, B2f4, C14. The proportion of these
compounds in the LC host mixture is preferably from 4 to 40%, very
preferably from 5 to 35%. [0468] 2d) The LC host mixture comprises
one or more compounds selected from the group consisting of
formulae C.sub.3, C4, C.sub.5, C9 and D2. The proportion of these
compounds in the LC host mixture is preferably from 8 to 70%, very
preferably from 10 to 60%. [0469] 2e) The LC host mixture comprises
one or more compounds selected from the group consisting of
formulae G1, G2 and G5, preferably G1a, G2a and G5a. The proportion
of these compounds in the LC host mixture is preferably from 4 to
40%, very preferably from 5 to 35%. [0470] 2f) The LC host mixture
comprises one or more compounds selected from the group consisting
of formulae E1, E3 and E6, preferably E1a, E3a and E6a, very
preferably E1a2, E1a5, E3a1 and E6a1. The proportion of these
compounds in the LC host mixture is preferably from 5 to 60%, very
preferably from 10 to 50%.
[0471] The combination of compounds of the preferred embodiments
mentioned above with the polymerised 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.
[0472] 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
.ltoreq.250 mPas, preferably .ltoreq.200 mPas, at 20.degree. C.
[0473] 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 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.
[0474] LC media according to the invention based on compounds with
negative dielectric anisotropy according to the first preferred
embodiment, in particular for use in displays of the PS-VA and
PS-UB-FFS type, have a negative dielectric anisotropy 4E,
preferably from -0.5 to -10, in particular from -2.5 to -7.5, at
20.degree. C. and 1 kHz.
[0475] The birefringence .DELTA.n in LC media according to the
invention for use in displays of the PS-VA and PS-UB-FFS type is
preferably below 0.16, particularly preferably from 0.06 to 0.14,
very particularly preferably from 0.07 to 0.12.
[0476] In the OCB-type displays according to the invention, the
molecules in the layer of the LC medium have a "bend" alignment. On
application of an electrical voltage, a realignment of the LC
molecules takes place with the longitudinal molecular axes
perpendicular to the electrode surfaces.
[0477] LC media according to the invention for use in displays of
the PS-OCB, PS-TN, PS-IPS, PS-posi-VA and PS-FFS type are
preferably those based on compounds with positive dielectric
anisotropy according to the second preferred embodiment, and
preferably have a positive dielectric anisotropy .DELTA..epsilon.
from +4 to +17 at 20.degree. C. and 1 kHz.
[0478] The birefringence .DELTA.n in LC media according to the
invention for use in displays of the PS-OCB type is preferably from
0.14 to 0.22, particularly preferably from 0.16 to 0.22.
[0479] The birefringence .DELTA.n in LC media according to the
invention for use in displays of the PS-TN-, PS-posi-VA-, PS-IPS-
oder PS-FFS-type is preferably from 0.07 to 0.15, particularly
preferably from 0.08 to 0.13.
[0480] LC media according to the invention, based on compounds with
positive dielectric anisotropy according to the second preferred
embodiment, for use in displays of the PS-TN-, PS-posi-VA-, PS-IPS-
oder PS-FFS-type, preferably have a positive dielectric anisotropy
.DELTA..epsilon. from +2 to +30, particularly preferably from +3 to
+20, at 20.degree. C. and 1 kHz.
[0481] 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 may be polymerisable or
non-polymerisable. Polymerisable additives are accordingly ascribed
to the polymerisable component or component A). Non-polymerisable
additives are accordingly ascribed to the non-polymerisable
component or component B).
[0482] In a preferred embodiment the LC media contain one or more
chiral dopants, preferably in a concentration from 0.01 to 1%, very
preferably from 0.05 to 0.5%. The chiral dopants are preferably
selected from the group consisting of compounds from Table B below,
very preferably from the group consisting of R- or S-1011, R- or
S-2011, R- or S-3011, R- or S-4011, and R- or S-5011.
[0483] 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.
[0484] 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, tetrabutyl-ammonium
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.
[0485] The individual components of the preferred embodiments
above, including a)-z3), 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. Corresponding compounds of the formula CY are
described, for example, in EP-A-0 364 538. Corresponding compounds
of the formula ZK are described, for example, in DE-A-26 36 684 and
DE-A-33 21 373.
[0486] 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 of the above-mentioned compounds with one or
more polymerisable compounds as defined above, and optionally with
further liquid-crystalline compounds and/or additives. In general,
the desired amount of the components used in lesser 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. The invention
furthermore relates to the process for the preparation of the LC
media according to the invention.
[0487] 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.
[0488] 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.
[0489] Preferred mixture components are shown in Tables A1 and A2
below. The compounds shown in Table A1 are especially suitable for
use in LC mixtures with positive dielectric anisotropy. The
compounds shown in Table A2 are especially suitable for use in LC
mixtures with negative dielectric anisotropy.
[0490] In Table A1, 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.
TABLE-US-00001 TABLE A1 ##STR00145## ##STR00146## ##STR00147##
##STR00148## ##STR00149## ##STR00150## ##STR00151## ##STR00152##
##STR00153## ##STR00154## ##STR00155## ##STR00156## ##STR00157##
##STR00158## ##STR00159## ##STR00160## ##STR00161## ##STR00162##
##STR00163## ##STR00164## ##STR00165## ##STR00166## ##STR00167##
##STR00168## ##STR00169## ##STR00170## ##STR00171## ##STR00172##
##STR00173## ##STR00174## ##STR00175## ##STR00176## ##STR00177##
##STR00178## ##STR00179## ##STR00180## ##STR00181## ##STR00182##
##STR00183## ##STR00184## ##STR00185## ##STR00186## ##STR00187##
##STR00188## ##STR00189## ##STR00190## ##STR00191## ##STR00192##
##STR00193## ##STR00194## ##STR00195## ##STR00196## ##STR00197##
##STR00198## ##STR00199## ##STR00200## ##STR00201## ##STR00202##
##STR00203## ##STR00204## ##STR00205## ##STR00206## ##STR00207##
##STR00208## ##STR00209## ##STR00210## ##STR00211## ##STR00212##
##STR00213## ##STR00214## ##STR00215## ##STR00216## ##STR00217##
##STR00218## ##STR00219## ##STR00220## ##STR00221## ##STR00222##
##STR00223## ##STR00224## ##STR00225## ##STR00226## ##STR00227##
##STR00228## ##STR00229## ##STR00230## ##STR00231## ##STR00232##
##STR00233## ##STR00234## ##STR00235## ##STR00236## ##STR00237##
##STR00238## ##STR00239## ##STR00240##
[0491] In Table A2, 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.
TABLE-US-00002 TABLE A2 ##STR00241## ##STR00242## ##STR00243##
##STR00244## ##STR00245## ##STR00246## ##STR00247## ##STR00248##
##STR00249## ##STR00250## ##STR00251## ##STR00252## ##STR00253##
##STR00254## ##STR00255## ##STR00256## ##STR00257## ##STR00258##
##STR00259## ##STR00260## ##STR00261## ##STR00262## ##STR00263##
##STR00264## ##STR00265## ##STR00266## ##STR00267## ##STR00268##
##STR00269## ##STR00270## ##STR00271## ##STR00272## ##STR00273##
##STR00274## ##STR00275## ##STR00276## ##STR00277## ##STR00278##
##STR00279## ##STR00280## ##STR00281## ##STR00282## ##STR00283##
##STR00284## ##STR00285## ##STR00286## ##STR00287## ##STR00288##
##STR00289## ##STR00290## ##STR00291## ##STR00292## ##STR00293##
##STR00294## ##STR00295## ##STR00296## ##STR00297## ##STR00298##
##STR00299## ##STR00300## ##STR00301## ##STR00302## ##STR00303##
##STR00304## ##STR00305## ##STR00306## ##STR00307## ##STR00308##
##STR00309## ##STR00310## ##STR00311## ##STR00312## ##STR00313##
##STR00314## ##STR00315## ##STR00316## ##STR00317## ##STR00318##
##STR00319## ##STR00320## ##STR00321## ##STR00322## ##STR00323##
##STR00324## ##STR00325## ##STR00326## ##STR00327## ##STR00328##
##STR00329## ##STR00330## ##STR00331## ##STR00332## ##STR00333##
##STR00334## ##STR00335## ##STR00336## ##STR00337## ##STR00338##
##STR00339## ##STR00340## ##STR00341## ##STR00342## ##STR00343##
##STR00344## ##STR00345## ##STR00346## ##STR00347## ##STR00348##
##STR00349## ##STR00350## ##STR00351## ##STR00352## ##STR00353##
##STR00354## ##STR00355## ##STR00356## ##STR00357## ##STR00358##
##STR00359## ##STR00360## ##STR00361## ##STR00362## ##STR00363##
##STR00364##
##STR00365## ##STR00366## ##STR00367## ##STR00368## ##STR00369##
##STR00370##
[0492] In a first preferred embodiment of the present invention,
the LC media according to the invention, especially those with
positive dielectric anisotropy, comprise one or more compounds
selected from the group consisting of compounds from Table A1.
[0493] In a second preferred embodiment of the present invention,
the LC media according to the invention, especially those with
negative dielectric anisotropy, comprise one or more compounds
selected from the group consisting of compounds from Table A2.
[0494] Table B shows possible chiral dopants which can be added to
the LC media according to the invention.
TABLE-US-00003 TABLE B ##STR00371## ##STR00372## ##STR00373##
##STR00374## ##STR00375## ##STR00376## ##STR00377## ##STR00378##
##STR00379## ##STR00380## ##STR00381## ##STR00382##
##STR00383##
[0495] The LC media preferably comprise 0 to 10% by weight, in
particular 0.01 to 5% by weight, particularly preferably 0.1 to 3%
by weight, of dopants. The LC media preferably comprise one or more
dopants selected from the group consisting of compounds from Table
B.
[0496] Table C shows possible stabilisers which can be added to the
LC media according to the invention. Therein n denotes an integer
from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal
methyl groups are not shown.
TABLE-US-00004 TABLE C ##STR00384## ##STR00385## ##STR00386##
##STR00387## ##STR00388## ##STR00389## ##STR00390## ##STR00391##
##STR00392## ##STR00393## ##STR00394## ##STR00395## ##STR00396##
##STR00397## ##STR00398## ##STR00399## ##STR00400## ##STR00401##
##STR00402## ##STR00403## ##STR00404## ##STR00405## ##STR00406##
##STR00407## ##STR00408## ##STR00409## ##STR00410## ##STR00411##
##STR00412## ##STR00413## ##STR00414## ##STR00415## ##STR00416##
##STR00417## ##STR00418## ##STR00419## ##STR00420## ##STR00421##
##STR00422## ##STR00423## ##STR00424## ##STR00425## ##STR00426##
##STR00427## ##STR00428## ##STR00429## ##STR00430##
##STR00431##
[0497] The LC media preferably comprise 0 to 10% by weight, in
particular 1 ppm to 5% by weight, particularly preferably 1 ppm to
1% by weight, of stabilisers. The LC media preferably comprise one
or more stabilisers selected from the group consisting of compounds
from Table C.
[0498] Table D shows illustrative reactive mesogenic compounds
which can be used in the LC media in accordance with the present
invention.
TABLE-US-00005 TABLE D ##STR00432## RM-1 ##STR00433## RM-2
##STR00434## RM-3 ##STR00435## RM-4 ##STR00436## RM-5 ##STR00437##
RM-6 ##STR00438## RM-7 ##STR00439## RM-8 ##STR00440## RM-9
##STR00441## RM-10 ##STR00442## RM-11 ##STR00443## RM-12
##STR00444## RM-13 ##STR00445## RM-14 ##STR00446## RM-15
##STR00447## RM-16 ##STR00448## RM-17 ##STR00449## RM-18
##STR00450## RM-19 ##STR00451## RM-20 ##STR00452## RM-21
##STR00453## RM-22 ##STR00454## RM-23 ##STR00455## RM-24
##STR00456## RM-25 ##STR00457## RM-26 ##STR00458## RM-27
##STR00459## RM-28 ##STR00460## RM-29 ##STR00461## RM-30
##STR00462## RM-31 ##STR00463## RM-32 ##STR00464## RM-33
##STR00465## RM-34 ##STR00466## RM-35 ##STR00467## RM-36
##STR00468## RM-37 ##STR00469## RM-38 ##STR00470## RM-39
##STR00471## RM-40 ##STR00472## RM-41 ##STR00473## RM-42
##STR00474## RM-43 ##STR00475## RM-44 ##STR00476## RM-45
##STR00477## RM-46 ##STR00478## RM-47 ##STR00479## RM-48
##STR00480## RM-49 ##STR00481## RM-50 ##STR00482## RM-51
##STR00483## RM-52 ##STR00484## RM-53 ##STR00485## RM-54
##STR00486## RM-55 ##STR00487## RM-56 ##STR00488## RM-57
##STR00489## RM-58 ##STR00490## RM-59 ##STR00491## RM-60
##STR00492## RM-61 ##STR00493## RM-62 ##STR00494## RM-63
##STR00495## RM-64 ##STR00496## RM-65 ##STR00497## RM-66
##STR00498## RM-67 ##STR00499## RM-68 ##STR00500## RM-69
##STR00501## RM-70 ##STR00502## RM-71 ##STR00503## RM-72
##STR00504## RM-73 ##STR00505## RM-74 ##STR00506## RM-75
##STR00507## RM-76 ##STR00508## RM-77 ##STR00509## RM-78
##STR00510## RM-79 ##STR00511## RM-80 ##STR00512## RM-81
##STR00513## RM-82 ##STR00514## RM-83 ##STR00515## RM-84
##STR00516## RM-85 ##STR00517## RM-86 ##STR00518## RM-87
##STR00519## RM-88 ##STR00520## RM-89 ##STR00521## RM-90
##STR00522## RM-91 ##STR00523## RM-92 ##STR00524## RM-93
##STR00525## RM-94 ##STR00526## RM-95 ##STR00527## RM-96
##STR00528## RM-97 ##STR00529## RM-98 ##STR00530## RM-99
##STR00531## RM-100 ##STR00532## RM-101 ##STR00533## RM-102
##STR00534## RM-103 ##STR00535## RM-104 ##STR00536## RM-105
##STR00537## RM-106 ##STR00538## RM-107 ##STR00539## RM-108
##STR00540## RM-109 ##STR00541## RM-110 ##STR00542## RM-111
##STR00543## RM-112 ##STR00544## RM-113 ##STR00545## RM-114
##STR00546## RM-115 ##STR00547## RM-116 ##STR00548## RM-117
##STR00549## RM-118 ##STR00550## RM-119 ##STR00551## RM-120
##STR00552## RM-121 ##STR00553## RM-122 ##STR00554## RM-123
##STR00555## RM-124
##STR00556## RM-125 ##STR00557## RM-126 ##STR00558## RM-127
##STR00559## RM-128 ##STR00560## RM-129 ##STR00561## RM-130
##STR00562## RM-131
[0499] In a preferred embodiment, the mixtures according to the
invention comprise one or more polymerisable compounds, preferably
selected from the polymerisable 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.
[0500] 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.
EXAMPLES
[0501] 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.
[0502] In addition, the following abbreviations and symbols are
used: [0503] V.sub.0 threshold voltage, capacitive [V] at
20.degree. C., [0504] n.sub.e extraordinary refractive index at
20.degree. C. and 589 nm, [0505] n.sub.0 ordinary refractive index
at 20.degree. C. and 589 nm, [0506] .DELTA.n optical anisotropy at
20.degree. C. and 589 nm, [0507] .epsilon..sub..perp. dielectric
permittivity perpendicular to the director at 20.degree. C. and 1
kHz, [0508] .epsilon..sub..parallel. dielectric permittivity
parallel to the director at 20.degree. C. and 1 kHz, [0509]
.DELTA..epsilon. dielectric anisotropy at 20.degree. C. and 1 kHz,
[0510] cl.p., T(N,I) clearing point [.degree. C.], [0511]
.gamma..sub.1 rotational viscosity at 20.degree. C. [mPas], [0512]
K.sub.1 elastic constant, "splay" deformation at 20.degree. C.
[pN], [0513] K.sub.2 elastic constant, "twist" deformation at
20.degree. C. [pN], [0514] K.sub.3 elastic constant, "bend"
deformation at 20.degree. C. [pN].
[0515] 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.
[0516] 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 (.degree. 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.
[0517] 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.degree. C., and .DELTA.n is
determined at 589 nm and .DELTA..epsilon. at 1 kHz, unless
explicitly indicated otherwise in each case.
[0518] 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).
[0519] Unless stated otherwise, the process of polymerising the
polymerisable 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.
[0520] 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.
[0521] The display used for measurement of the capacitive threshold
voltage consists of two plane-parallel glass outer plates at a
separation of 25 .mu.m, 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.
[0522] 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 .mu.m, 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.
[0523] The polymerisable compounds are polymerised in the display
or test cell by irradiation with UV 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 100 mW/cm.sup.2 is used for polymerisation. The
intensity is measured using a standard meter (Hoenle UV-meter high
end with UV sensor).
[0524] The tilt angle is determined using the Mueller Matrix
Polarimeter "AxoScan" from Axometrics. A low value (i.e. a large
deviation from the 90.degree. angle) corresponds to a large tilt
here.
[0525] Unless stated otherwise, the term "tilt angle" means the
angle between the LC director and the substrate, and "LC director"
means in a layer of LC molecules with uniform orientation the
preferred orientation direction of the optical main axis of the LC
molecules, which corresponds, in case of calamitic, uniaxially
positive birefringent LC molecules, to their molecular long
axis.
Example 1
[0526] Polymerisable compound (or "RM") 1 is prepared as
follows.
##STR00563##
[0527] 3: The preparation of boronic ester 3 is described in WO
2014/133361 A1.
[0528] 5: A solution of boronic ester 3 (3.0 g, 95%, 36.3 mmol) and
phenol 4 (7.0 g, 36.4 mmol) in tetrahydrofuran (120 mL) was added
to a stirred solution of sodium metaborate (tetrahydrate, 8.9 g,
64.5 mmol) in water (30 mL) at room temperature. The resulting
mixture was treated with bis(triphenylphosphine)-palladium(II)
chloride (1.5 g, 2.0 mmol), followed by addition of hydrazine
hydrate (0.07 mL, 1.5 mmol). The reaction mixture was stirred
overnight at 70.degree. C., before it was treated with 2M HCl and
ethyl acetate. Aqueous phase was separated and extracted with ethyl
acetate (2 times). The combined organic phase was washed with sat.
NaCl solution, dried over Na.sub.2SO.sub.4, filtered and
concentrated in vacuo. The residue was purified with flash
chromatography (heptane/ethyl acetate) to give 5 as a yellowish
oil. (9.0 g, 65%; GC: 86.0%)
##STR00564##
[0529] 6: A solution of 5 (9.0 g, 27.7 mmol) in tetrahydrofuran (90
mL) was hydrogenated over Pd/C (5%, 3.0 g) at room temperature for
15h, before it was treated with additional 3.0 g of Pd/C. The
resulted mixture was hydrogenated for additional 15 h, filtered and
concentrated in vacuo. The residue was used in the next step
without further purification (oil, 6.3 g, 97%).
##STR00565##
[0530] 16: Methacrylic acid (7.0 g, 80.7 mmol) and
4-dimethylaminopyridine (DMAP, 0.33 g, 2.7 mmol) were added to a
stirred solution of biphenol 6 (6.3 g, 26.9 mmol) in
dichloromethane (100 mL) at room temperature. The resulting mixture
was cooled to 3.degree. C. followed by dropwise addition
1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (12.5 g, 155 mmol).
The reaction mixture was allowed to warm to room temperature and
stirred over two days, before it was concentrated in vacuo. The
residue was purified by flash chromatography (heptane/ethyl
acetate) and recrystallized from heptane/ethanol (5:1) to give 2 as
white crystals (6.5 g, 65%; GC: 99.7%; HPLC: 99.7%). .sup.1H NMR:
2.04-2.06 (m, 6H), 3.81 (s, 3H), 5.85-5.87 (m, 2H), 6.34 (br.s.,
2H), 6.87 (dd, J=8.2, 2.1 Hz, 1H), 6.97 (d, J=2.2 Hz, 1H),
7.07-7.14 (m, 2H), 7.33 (d, J=8.2 Hz, 1H), 7.44 (dd, J=8.3, 8.3 Hz,
1H); EI-MS: 370.1.
[0531] DSC: Tg -5 K 83 I.
Examples 2-5
[0532] The following polymerisable monomeric compounds are prepared
in analogy to the methods described in Example 1.
##STR00566##
Polymerisable Mixture Examples
[0533] The nematic LC host mixture N1 is formulated as follows:
TABLE-US-00006 CCH-501 9.00% cl.p. 70.0.degree. C. CCH-35 14.00%
.DELTA.n 0.0825 PCH-53 8.00% .DELTA..epsilon. -3.5 CY-3-O4 14.00%
.epsilon..sub..parallel. 3.5 CY-5-O4 13.00% K.sub.3/K.sub.1 1.00
CCY-2-1 9.00% .gamma..sub.1 141 mPa s CCY-3-1 9.00% V.sub.0 2.10 V
CCY-3-O2 8.00% CCY-5-O2 8.00% CPY-2-O2 8.00%
[0534] The nematic LC host mixture N2 is formulated as follows:
TABLE-US-00007 CY-3-O2 18.00% cl.p. +74.5.degree. C. CPY-2-O2
10.00% .DELTA.n 0.1021 CPY-3-O2 10.00% .DELTA..epsilon. -3.1
CCY-3-O2 9.00% .epsilon..sub..parallel. 3.5 CCY-4-O2 4.00%
K.sub.3/K.sub.1 1.16 PYP-2-3 9.00% .gamma..sub.1 86 mPa s CC-3-V
40.00% V.sub.0 2.29 V
[0535] Polymerisable mixtures are prepared by adding various
individual polymerisable monomeric compounds (hereinafter referred
to as reactive mesogen or "RM") to nematic LC host mixtures N1 and
N2.
[0536] As reference, polymerisable mixtures C11 and C21 are
prepared by adding RM C1 which has no substituents, and which is
typically used in PSA mixtures of prior art, to nematic LC host
mixtures N1 and N2, at a concentration of 0.300% by weight.
##STR00567##
[0537] Polymerisable mixtures P11-P22 according to the invention
are prepared by adding RM 1 or 2 of Example 1 or 2, respectively,
to nematic LC host mixtures N1 and N2 at a concentration of 0.345%
by weight, to have an equimolar amount of 0.093 mmol RM per 10 g
mixture compared to mixtures C11 and C21.
[0538] The compositions of the individual polymerisable mixtures
are shown in Table 1.
TABLE-US-00008 TABLE 1 Polymerisable mixture composition Mix. No.
P11 P12 C11 P21 P22 C21 LC Host N1 N1 N1 N2 N2 N2 RM 1 2 C1 1 2
C1
Use Examples
[0539] The individual polymerisable mixtures are filled into PSA
test cells, the RM is polymerised under application of a voltage,
and several properties like tilt angle generation, VHR under UV
stress and residual RM content are measured.
Residual RM Measurement
[0540] The polymerisation speed is measured by determining the
residual content of residual, unpolymerised RM (in % by weight) in
the mixture after UV exposure with a given intensity and lamp
spectrum after a given UV exposure time. The smaller the residual
RM content after a given time interval, the faster the
polymerization,
[0541] For this purpose the polymerisable mixtures are inserted
into electrooptic test cells from Varitronics made of two soda-lime
glass substrates caoted with an ITO electrode layer and a rubbed
VA-polyimide alignment layer. The LC layer thickness is approx. 7
.mu.m.
[0542] The test cells are illuminated by a MH-lamp (UV-Cube 2000)
using a 320 nm long pass filter (N-WG320) and a light intensity of
100 mW/cm.sup.2, causing polymerisation of the RM. Illumination
times are given in the respective tables below.
[0543] After polymerization the test cells are opened, and the
mixture is dissolved and rinsed out of the test cell with 2 ml
ethyl methyl ketone and analyzed by High Performance Liquid
Chromatography (HPLC). For better comparison, the results are given
by % rel. At 0 min illumination time, a 100% of RM are present and
after x min illumination time y % of the RM are still present. The
results are shown in Table 3.
TABLE-US-00009 TABLE 3 Residual RM content Mixture UV Time/min 0 2
4 6 C11 residual RM/ 100 80 63 53 P11 % rel 100 72 51 40 P12 100 59
32 19 Mixture UV Time/min 0 2 6 C21 residual RM/ 100 49 19 P21 %
rel 100 47 17 P22 100 30 7
[0544] It can be seen that, compared to mixtures C.sub.11 and
C.sub.21, for polymerisable mixtures P11, P12, P21 and P22 the
amount of residual RM is lower, and thus polymerisation speed is
faster.
Tilt Angle Generation
[0545] For measuring the tilt angle generation the polymerisable
mixtures are inserted into electrooptic test cells made of two
soda-lime glass substrates coated with an ITO electrode layer of
approx. 200 nm thickness and a VA-polyimide alignment layer
(JALS-2096-R1) of approx. 30 nm thickness which is rubbed
antiparallel. The LC-layer thickness d is approx. 4 .mu.m.
[0546] The test cells are illuminated by a MH-lamp (UV-Cube 2000)
using a 320 nm long pass filter (N-WG320) and a light intensity of
100 mW/cm.sup.2 at 20.degree. C. with an applied square voltage of
24 VRMS (alternating current, 1 khz), causing polymerisation of the
RM and a generation of a tilt angle. Illumination times are given
in the respective tables. The generated tilt was measured after a
period of time of 12 hours using the Mueller Matrix Polarimeter
"AxoScan" from Axometrics. The results are shown in Table 4.
TABLE-US-00010 TABLE 4 Tilt angles Mixture UV Time/min 0 2 6 C11
Tilt/.degree. 90 85 78 P11 89 82 74 P12 89 81 72 C21 89 77 70 P21
88 80 76 P22 89 77 74
[0547] It can be seen that, compared to mixtures C.sub.11 and
C.sub.21, polymerisable mixtures P11, P12, P21 and P22 show a
comparable or even faster and stronger tilt angle generation.
[0548] In conclusion, the use examples demonstrate that, compared
to RMs of prior art, the RMs and polymerisable mixtures according
to the present invention show an improved polymerization speed and
more complete polymerization, while maintaining a sufficient
pretilt generation or even enhancing pretilt angle generation for
display applications.
[0549] The entire disclosure[s] of all applications, patents and
publications, cited herein and of corresponding European
application No. 16202818.7 filed Dec. 8, 2016 is incorporated by
reference herein.
[0550] 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.
[0551] 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.
* * * * *