Polymerizable mesogenic tolanes

Details Polymerizable mesogenic tolanes Polymerizable mesogenic tolanes

2000-06-22

2003-02-04

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

C428S001200, C428S001300, C428S001500, C252S299610, C252S299620, C252S299630, C252S299640, C252S299650, C252S299660, C560S064000, C560S065000

Reexamination Certificate

active

06514578

ABSTRACT:

The invention relates to polmyerizable mesogenic tolanes, to polymerizable liquid crystal compositions comprising the polymerizable mesogenic tolanes, to linear or crosslinked liquid crystal polymers obtainable from the polymerizable mesogenic tolanes and the compositions comprising them, and to the use of the polymerizable mesogenic tolanes, and the polymerizable compositions and polymers obtained thereof in optical elements, liquid crystal displays, adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, liquid crystal pigments, decorative and security applications, nonlinear optics and optical information storage.
Polymerizable mesogenic compounds, which are also known as reactive mesogenic compounds, have been described in prior art for various purposes. For example, they can be aligned in their liquid crystal phase and subsequently polymerized in situ, to give linear or crosslinked liquid crystal polymer films with uniform orientation of high quality. These films can be used for example as optical elements, like polarization filters as described in EP 0 397 263, broadband circular polarizers as described in EP 0 606 940 and WO 97/35219, or compensation or retardation films as described in WO 98/00475, WO 98/04651 or WO 98/12584.
The polymerizable mesogenic compounds described in prior art, however, do often exhibit liquid crystalline phases only in a small temperature range or do not show mesophase behavior at all. Furthermore, polymerizable mesogenic compounds of prior art do often exhibit only low or moderate values of the birefringence.
When preparing oriented liquid crystal polymer films for the uses as described above, it is especially desired to have available polymerizable compositions exhibiting a nematic liquid crystal phase at room temperature, so that it is possible to carry out alignment and polymerization of the composition at low temperatures. For this purpose, it is advantageous if the single polymerizable components exhibit broad liquid crystalline phases, too.
Thus, there is a demand for polymerizable mesogenic compounds with a broad liquid crystalline phase and a high birefringence, which can be used for the preparation of oriented liquid crystal polymer films for optical applications.
Furthermore, regarding the broad range of applications for polymerizable mesogenic compounds it is desirable for the expert to have available further compounds of this type which are easy to synthesize and fulfill the various requirements as described above.
It was an aim of the invention to provide polymerizable mesogenic compounds with advantageous properties, thus extending the pool of reactive mesogenic compounds available to the expert. Other aims of the present invention are immediately evident to the person skilled in the art from the following detailed description.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
It was now found that these aims can be achieved by providing polymerizable mesogenic tolanes according to the present invention.
Polymerizable mesogenic compounds comprising a tolane group are disclosed in WO 98/52905, EP 0 659 865, JP 11-147853, JP 11-080090, JP 08-231958, JP 07-109351 and JP 07-017910.
The terms reactive or polymerizable mesogenic compound as used in the foregoing and the following comprise compounds with a rod-shaped, board-shaped or disk-shaped mesogenic group, i.e. a group with the ability to induce mesophase behavior. These compounds do not necessarily have to exhibit mesophase behavior by themselves. It is also possible that these compounds show mesophase behavior only in mixtures with other compounds or when the polymerizable mesogenic compounds or the mixtures comprising them are polymerized.
One object of the present invention are polymerizable mesogenic tolanes of formula I
wherein
P is CH
2
═CW—COO—, WCH═CH—O—,
 or CH
2
═CH— Phenyl-(O)
k
— with W being H, CH
3
or Cl and k being 0 or 1,
Sp is a spacer group having 1 to 25 C atoms,
X is —O—, —S—, —CO—, —COO—, —OCO—, —CO—NH—, —NH—CO—, —CH
2
CH
2
—, —OCH
2
—, —CH
2
O—, —SCH
2
—, —CH
2
S—, —CH═CH—, —CH═CH—COO—, —OCO—CH═CH—, —C≡C—, or a single bond,
n is 0 or 1,
Z
1
and Z
2
are each independently —COO—, —OCO—, —CH
2
CH
2
—, —OCH
2
—, —CH
2
O—, —CH═CH—, —CH═CH—COO—, —OCO—CH═CH—, —C≡C—, or a single bond,
A
1
and A
2
are each independently 1,4-phenylene in which, in addition, one or more CH groups may be replaced by N, 1,4-cyclohexylene in which, in addition, one or two non-adjacent CH
2
groups may be replaced in each case by O or S, 1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, or 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, it being possible for all these groups to be unsubstituted, mono- or polysubstituted with F,Cl, OH, CN, NO
2
or alkyl, alkoxy or alkanoyl groups having 1 to 7 C atoms wherein one or more H atoms may be replaced by F or Cl,
m1 and m2 are each independently 0, 1 or 2, with m1+m2<3,
L
1
and L
2
are each independently F, Cl, CN, OH, NO
2
or an alkyl, alkoxy or alkanoyl group having 1 to 7 C atoms wherein one or more H atoms may be substituted by F or Cl,
r is in each case independently 0, 1, 2, 3 or 4,
R is H, CN, halogen or a straight-chain or branched alkyl radical with up to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH
2
groups to be replaced, in each case independently from one another, by —O—, —S—, —NH—, —N(CH
3
)—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another, or alternatively R is P—(Sp—X)
n
—.
with the provisos that
a) in case P is CH
2
═CW—COO— or
 and m1+m2 is 0, then R is P—(Sp—X)
n
— and/or at least one r is different from 0,
b) in case P is CH
2
═CW—COO— and one of —(A
1
—Z
1
)
m1
— and —(A
2
—Z
2
)
m2
— is substituted or unsubstituted phenylene and the other is a single bond, then R is P—(Sp—X)
n
and/or n is 1,
c) in case m1+m2 is 2, then A
1
and A
2
are not cyclohexylene.
Another object of the invention is a polymerizable liquid crystal composition comprising at least two polymerizable components, at least one of which is a compound of formula I.
Another object of the invention is a linear or crosslinked polymer obtainable by polymerization of one or more compounds of formula I or of a polymerizable composition comprising one or more compounds of formula I.
Yet another object of the invention is the use of a compound of formula I, or a polymerizable composition or polymer obtainable thereof, in optical elements such as polarizers, optical retardation or compensation films, alignment layers, colour filters or holographic elements, in liquid crystal displays such as PDLC (polymer dispersed liquid crystals), polymer gel or polymer stabilized cholesteric texture (PSCT) displays, in adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics or liquid crystal pigments, for decorative and security applications, and for nonlinear optics or optical information storage.
Especially preferred are compounds of formula I wherein
m1+m2≧1
at least one of A
1
and A
2
is an aryl group as previously described, preferably when m1+m2=1,
one of m1 and m2 is 1 and the other is 0,
m1 is 1 and m2 is 0,
at least one of Z
1
and Z
2
is —COO— or —OCO—,
R has one of the meanings given for P—(Sp—X)
n
—,
R is halogen, cyano or an optionally fluorinated achiral or chiral alkyl or alkoxy group with 1 to 15 C atoms,
n is 1,
Sp is alkylene with 1 to 12 C atoms,
X is —O— or a single bond.
Of the compounds of formula I wherein P is CH
2
═CW—COO— especially preferred are those wherein n is 1.
Of the compounds of formula I wherein m1+m2 is 1 or 2, especially preferred are those wherein n is 1, those wherein one or both of Z

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