Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Reexamination Certificate
2001-11-08
2003-06-24
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
C252S299630, C560S079000, C560S083000, C560S095000
Reexamination Certificate
active
06582626
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel compound useful to make an optically anisotropic medium such as a wave plate and an optical low pass filter, a polymerizable liquid crystal composition comprising the compound, and an optically anisotropic medium obtained by polymerizing the composition.
BACKGROUND OF THE INVENTION
Optically anisotropic media having a fixed oriented structure can be produced by subjecting a polymerizable liquid crystal composition comprising a compound having a polymerizable functional group to orientation processing in its liquid crystal state and then polymerizing the oriented composition, while maintaining in its oriented state, by irradiation with active energy rays such as ultraviolet (UV) rays or electron beams. The optically anisotropic media thus produced show anisotropy in physical properties, such as refractive index, dielectric constant, magnetic susceptibility, elastic modulus, and thermal expansion coefficient, and are useful as a wave plate, a polarizer, a polarizing prism, a waveguide, etc.
JP-A-8-3111 (corresponding to U.S. Pat. No. 5,863,457) (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a polymerizable liquid crystal composition for these applications. The composition disclosed therein has a feature that it exhibits liquid crystalline properties at room temperature but has a drawback of insufficient transparency after polymerization.
JP-A-9-40585 (corresponding to U.S. Pat. No. 5,800,733) teaches that compounds having a folding molecular structure having long chains bonded to the 1- and 2-positions of a benzene ring, respectively, are effective in developing liquid crystalline properties at low temperature, and discloses, as an example, a compound having a —CH
2
CH
2
COO— bond represented by formula (I-d):
wherein s represents an integer of 3 to 12; R
34
represents a fluorine atom, a chlorine atom, a cyano group or an alkoxycarbonyl group; and X
1
, X
2
and X
3
each represent a hydrogen atom.
Because of the two long chains introduced for facilitating development of liquid crystalline properties, these compounds have a high molecular weight and a very high viscosity. As a result, in case orientation defects such as disclination occur in orientation, it needs a lot of time to eliminate the defects, resulting in poor productivity.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an optically anisotropic medium having excellent transparency with a small haze.
Another object of the invention is to provide a polymerizable compound useful for the production of the optically anisotropic medium.
A still other object of the invention is to provide a polymerizable liquid crystal composition comprising the polymerizable compound.
Other objects and effects of the invention will become apparent from the following description.
The above-described objects of the invention has been achieved by providing a novel polymerizable compound of a linear molecule in which three phenylene groups are linked via a 1,4-bond with one of the two linking groups that link the 1,4-phenylene groups being —CH
2
CH
2
COO— or —CH
2
CH
2
OCO—. The inventors found that the compound has a low under limit temperature of liquid crystalline phase owing to this structure and that a polymerizable liquid crystal composition containing the compound has a low under limit temperature of liquid crystalline phase as well. The inventors also found that an optically anisotropic medium obtained by subjecting the composition to orientation processing in its crystal state and then polymerizing the resulting composition with active energy ray irradiation while maintaining the oriented state has high transparency with a small haze.
That is, the present invention provides a polymerizable compound represented by formula (I):
wherein Q
1
and Q
2
each independently represent a hydrogen atom or a methyl group; p and q each independently represent an integer of 2 to 18; X
1
and X
2
each independently represent a single bond, —O—, —COO— or —OCO—; L
1
represents —COO— or —OCO—; L
2
represents —CH
2
CH
2
COO— or —CH
2
CH
2
OCO—; and Y
1
, Y
2
and Y
3
each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, an alkanoyl group having 2 to 7 carbon atoms, a cyano group or a halogen atom.
In addition, the present invention also provides a polymerizable liquid crystal composition for producing an optically anisotropic medium, which comprises:
a polymerizable compound represented by the above formula (I); and
a compound represented by formula (II):
wherein Q
3
represents a hydrogen atom or a methyl group; X
3
represents a single bond or —O—; X
4
represents a single bond, —O—, —OCO—, —COO— or —CH═CH—COO—; B
1
, B
2
and B
3
each independently represent a 1,4-phenylene group, a 1,4-phenylene group in which one CH group or not adjoining two CH groups thereof are displaced with a nitrogen atom, a 1,4-cyclohexylene group, a 1,4-cyclohexylene group in which one CH
2
group or not adjoining two CH
2
groups thereof are displaced with an oxygen atom or a sulfur atom, a 1,4-cyclohexenylene group, or a 1,4-cyclohexenylene group in which one CH
2
group or not adjoining two CH
2
groups thereof are displaced with an oxygen atom or a sulfur atom, and B
1
, B
2
and B
3
each may have one or more substituents selected from an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, an alkanoyl group having 2 to 7 carbon atoms, a cyano group, and a halogen atom; L
3
and L
4
each independently represent a single bond, —CH
2
CH
2
—, —CH
2
O—, —OCH
2
—, —COO—, —OCO—, —C≡C—, —CH═CH—, —CF═CF—, —(CH
2
)
4
—, —CH
2
CH
2
CH
2
O—, —OCH
2
CH
2
CH
2
—, —CH═CH—CH
2
CH
2
—, —CH
2
CH
2
—CH═CH—, —CH═CH—COO— or —OCO—CH═CH—; Z
1
represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, wherein one or more CH
2
groups of the alkyl group or the alkenyl group may be displaced with —O—, —CO—, —COO—, —OCO— or —OCOO—, provided that the displacement does not make an O—O bond; r represents 0 or an integer of 1 to 18; and s represents 0 or 1.
Since the polymerizable liquid crystal composition contains the compound of formula (I), the under limit temperature of liquid crystalline phase thereof is low. Therefore, it is not necessary to excessively raise a temperature upon producing an optically anisotropic medium by orienting the polymerizable liquid crystal composition in its liquid crystal state and then polymerizing the same while maintaining the oriented state. This affords convenience in handling and suppresses an increase in haze, caused by thermal polymerization or oxidation due to heating, in the resulting optically anisotropic medium. Hence, an optically anisotropic medium having high transparency can be produced from the polymerizable liquid crystal composition of the invention.
DETAILED DESCRIPTION OF THE INVENTION
In formula (I), p and q are each preferably 3 to 12, particularly preferably 3 to 8. X
1
and X
2
are each preferably —O—. Y
1
, Y
2
and Y
3
are each preferably a hydrogen atom, a fluorine atom, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms. Of the alkyl and alkoxy groups preferred are a methyl group and a methoxy group. A hydrogen atom and a fluorine atom are particularly preferred as Y
1
, Y
2
and Y
3
.
The compounds represented by formula (I) include those represented by formulae (1) through (12) shown blow, in which p and q each independently represent an integer of 2 to 18:
Of the above compounds preferred are those of formula (1) in which p and q are each independently an integer of 3 to 8.
An example of the synthesis method of the compound according to the present invention is shown below.
In the above formulae, p, q, Q
1
and Q
2
are as defined in formula (I).
The compound of the invention is structurally char
Hasebe Hiroshi
Takehara Sadao
Takeuchi Kiyofumi
Armstrong Westerman & Hattori, LLP
Dainippon Ink and Chemicals Inc.
Wu Shean C.
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