Polymerizable liquid crystal compound having amido bond...

Details Polymerizable liquid crystal compound having amido bond... Polymerizable liquid crystal compound having amido bond...

2001-03-12

2003-09-02

Huff, Mark F. (Department: 1756)

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

C252S299640, C252S299680, C252S299010, C428S001400

Reexamination Certificate

active

06613246

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a polymerizable liquid crystal compound having an amido bond between two cyclic groups. The invention also relates to an optically anisotropic element prepared from the compound.
BACKGROUND OF THE INVENTION
Alignment of molecules of a polymerizable liquid crystal compound can be fixed by polymerization after the molecules are aligned. The polymerizable liquid crystal compounds are described in U.S. Pat. Nos. 4,683,327, 4,983,479, 5,622,648 and 5,770,107; and W.O. Patent Nos. 95/22586 and 97/00600.
An optically anisotropic polymer prepared by the polymerization can be used as an optically anisotropic element. For example, a polarizing prism made of the optically anisotropic polymer is described in European Patent No. 428213. Further, an optical compensatory sheet (for liquid crystal display of STN mode) made of the optically anisotropic polymer is described in European Patent No. 428881. Furthermore, a cholesteric polarizer made of the optically anisotropic polymer is described in European Patent No. 606940.
SUMMARY OF THE INVENTION
The present inventors have studied polymerizable liquid crystal compounds, and have found that the known compounds have disadvantages in phase transition temperature and optical characteristics. For example, the known compounds often change into isotropic liquid at low temperatures or exhibit liquid phase within narrow temperature ranges. Further, known polymerizable liquid crystal compounds sometimes have small birefringent indexes to be used in an optically anisotropic material (such as an optically anisotropic element).
An object of the present invention is to provide a polymerizable liquid crystal compound having an appropriate phase transition temperature.
Another object of the invention is to provide a polymerizable liquid crystal compound having a large birefringent index.
A further object of the invention is to provide an optically anisotropic element having optical anisotropy, which can be easily produced.
The present invention provides a polymerizable liquid crystal compound represented by the formula (I):
Q
1
—L
1
—Cy
1
—(CH═CH)
n
—CO—NR
1
—Cy
2
—L
2
—Q
2
  (I)
in which each of Q
1
and Q
2
independently is a polymerizable group; each of L
1
and L
2
independently is a divalent linking group; each of Cy
1
and Cy
2
independently is a divalent cyclic group; R
1
is hydrogen or an alkyl group having 1 to 7 carbon atoms; and n is 0 or 1.
The invention also provides An optically anisotropic element comprising a transparent support and a liquid crystal layer formed by polymerization of a polymerizable liquid crystal compound, wherein the polymerizable liquid crystal compound is represented by the formula (I).
The present inventors have found that the polymerizable liquid crystal compound represented by the formula (I) changes into isotropic liquid at a high temperature and exhibits liquid phase within a wide temperature range. Further, the compound has a large birefringent index. The compound of the formula (I) has a specific mesogen structure, in which an amide bond (—CO—NR—) is present between two cyclic groups (Cy
1
and Cy
2
), each of which further links to a polymerizable group (Q) through a linking group (L). Because of the specific mesogen structure, the compound can exhibit liquid phase within a wide temperature range and has a large birefringent index.
Since the polymerizable liquid crystal compound gives liquid phase within a wide temperature range, alignment of the liquid crystal molecules can be easily maintained during polymerization reaction. Accordingly, an optically anisotropic element can be easily prepared by polymerization reaction of the polymerizable liquid crystal compound represented by the formula (I).
Since the compound of the formula (I) has a large birefringent index, an optically anisotropic element having high anisotropy can be obtained.
DETAILED DESCRIPTION OF THE INVENTION
The polymerizable liquid crystal compound of the invention is represented by the formula (I).
Q
1
—L
1
—Cy
1
—(CH═CH)
n
—CO—NR
1
—Cy
2
—L
2
—Q
2
.  (I)
In the formula (I), each of Q
1
and Q
2
independently is a polymerizable group. The polymerizable group is preferably polymerized by addition (including ring-opening) or condensation polymerization reaction. In other words, the polymerizable group is preferably a functional group which can be subjected to addition or condensation polymerization reaction.
Examples of the polymerizable groups (Q) are shown below.
The polymerizable group (Q
1
or Q
2
) preferably is an unsaturated polymerizable group (Q-1 to Q-7), an epoxy group (Q-8) or an aziridinyl group (Q-9), more preferably is an unsaturated polymerizable group, and most preferably is an ethylenically unsaturated group (Q-1 to Q-6).
In the formula (I), each of L
1
and L
2
independently is a divalent linking group. The divalent linking group is preferably selected from the group consisting of —O—, —S—, —CO—, —NR
2
—, a divalent chain group, a divalent cyclic group and a combination thereof. R
2
is hydrogen or an alkyl group having 1 to 7 carbon atoms.
Examples of the combined divalent linking group are shown below. In the examples, the left side is attached to Q (Q
1
or Q
2
), and the right side is attached to Cy (Cy
1
or Cy
2
). CH means a divalent chain group, and CY means a divalent cyclic group.
L1: —CO—O—CH—O—
L2: —CO—O—CH—O—CY—CO—O—
L3: —CO—O—CH—O—CY—O—CO—
L4: —CO—O—CH—O—CY—CH—
L5: —CO—O—CH—O—CY—
L6: —CO—O—CH—O—CY—CH—CO—O—
L7: —CO—O—CH—O—CY—O—CO—CH—
The divalent chain groups (CH) include an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group or a substituted alkynylene group. An alkylene group, a substituted alkylene group, an alkenylene group and a substituted alkenylene group are preferred, and an alkylene group and an alkenylene group are more preferred.
The alkylene group may have a branched structure. The alkylene group preferably has 1 to 12 carbon atoms, more preferably has 2 to 10 carbon atoms, and most preferably has 3 to 8 carbon atoms.
The alkylene moiety of the substituted alkylene group is the same as the above-described alkylene group. Examples of the substituent groups of the substituted alkylene groups include a halogen atom.
The alkenylene group may have a branched structure. The alkenylene group preferably has 2 to 12 carbon atoms, more preferably has 2 to 8 carbon atoms, and most preferably has 2 to 4 carbon atoms.
The alkenylene moiety of the substituted alkenylene group is the same as the above-described alkenylene group. Examples of the substituent groups of the substituted alkylene groups include a halogen atom.
The alkynylene group may have a branched structure. The alkynylene group preferably has 2 to 12 carbon atoms, more preferably has 2 to 8 carbon atoms, and most preferably has 2 to 4 carbon atoms.
The alkynylene moiety of the substituted alkynylene group is the same as the above described alkynylene group. Examples of the substituent groups of the substituted alkylene groups include a halogen atom.
The definition and the examples of the divalent cyclic groups (CY) are the same as those for Cy
1
and Cy
2
described below.
R
2
preferably is hydrogen or an alkyl group having 1 to 4 carbon atoms, more preferably is hydrogen or an alkyl group having 1 or 2 carbon atoms, and most preferably is hydrogen.
L
2
is preferably —O—CO—(CH═CH)
m
—Cy
3
—L
3
— or —(CH═CH)
m
—CO—O—Cy
3
—L
3
—, in which m is 0 or 3, Cy
3
is a divalent cyclic group and L
3
is a divalent linking group.
The above m is preferably 0 rather than 1.
The definition and the examples of the divalent cyclic group are the same as those for Cy
1
and Cy
2
described below.
L
3
preferably is a divalent linking group selected from the group consisting of —O—, —S—, —CO—, —NR
2
—, a divalent chain group and a combination thereof. R
2
is hydrogen or an alkyl group having 1 to 7 carbon atoms. R
2
preferably is hydrogen or an alkyl group having 1 to 4 carbon atoms, more preferably i

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