Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-05-18
2001-04-03
Acquah, Samuel A. (Department: 1711)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C528S176000, C528S188000, C430S020000, C430S627000, C430S495100
Reexamination Certificate
active
06210872
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel optical film superior in liquid crystal orientability, permitting easy fixing of an oriented state in glass phase, having a high liquid crystal orientation holding ability, and suitable for application to optical elements.
PRIOR ART
Various liquid crystalline polymers have been developed and commercialized in the field of high-performance materials, utilizing their dynamic characteristics such as having high elasticity, high rigidity, high heat resistance, and superior moldability. It is well known that liquid crystalline polymers possess both a structural and optical anisotropy based on the liquid crystal and an orientation fixing ability based on the polymers. In recent years, researches and developments have been done actively for using liquid crystalline polymers in the field of functional materials such as optical members for a liquid crystal display by utilizing their property just mentioned above.
For making the most of the optical anisotropy of liquid crystalline polymers it is necessary that liquid crystal molecules be oriented to a sufficient extent. For enhancing the orientability of liquid crystal molecules it is preferable that the structural units of the liquid crsytalline polymers be structural units obtained from bifunctional compounds and assume the form of a molecular structure wherein they are arranged on straight lines with respect to each other. From such a standpoint, liquid crystalline polymers with a twisted nematic orientation fixed, which are used for optical elements, are made up of only such structural units as are obtained from bifunctional compounds, as is disclosed in Japanese Patent Nos. 2592694 and 2592701. However, optical elements fabricated from such liquid crystalline polymers have so far not satisfactory in point of an orientation holding ability because there the orientation formed is disordered upon exertion of an external force thereon at a temperature above the glass transition points of the polymers.
OBJECT OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problem of the prior art and particularly provide a novel optical film easy to fix a liquid crystal orientation in glass phase, superior in the orientation holding ability, and suitable for the application to optical elements.
SUMMARY OF THE INVENTION
Using a liquid crystalline polyester with a specific structural unit introduced into a polymer chain as a main chain, the present inventors have formed the polyester into an optical film and found that the optical film is superior in both orientability and orientation holding ability.
More specifically, the present invention is firstly concerned with an optical film formed substantially from a liquid crystalline material. constituted essentially by a liquid crystalline polyester, the liquid crystalline polyester having the following structural units (A) and (B) as essential structural units, assuming a liquid crystal state at a temperature higher than the liquid crystal transition point of the polyester and a glassy state at a temperature lower than the liquid crystal transition point of the polyester, and having an inherent viscosity, &eegr;, of 0.04 to 0.4 dl/g as determined in a mixed phenol/tetrachloroethane (weight ratio: 60/40) solvent at 30° C.:
where each X represents O or C═O independently, each Y is independently selected from F, Cl, Br, and an alkyl group having 1 to 4 carbon atoms, and n is 0 or 1.
The present invention is secondly concerned with the above optical film wherein the liquid crystalline material does not essentially contain any optically active component.
The present invention is thirdly concerned with the above optical film wherein the liquid crystalline material is a twisted nematic or smectic liquid crystalline polyester having an optically active group in the molecule thereof.
The present invention is fourthly concerned with the above optical film wherein the liquid crystalline material is a composition consisting essentially of a liquid crystalline polyester and an optically active compound, which liquid crystalline polyester is the polyester mentioned in the above second aspect of the invention.
EMBODIMENTS OF THE INVENTION
The present invention will be described in detail herein under.
As liquid crystalline materials employable in the present invention are mentioned the following materials:
{circle around (1)} a nematic (or smectic) liquid crystalline polyester having the structural units (A) and (B) as essential structural units;
{circle around (2)} a composition comprising a nematic (or smectic) liquid crystalline polyester having the structural units (A) and (B) as essential structural units and an optically active low-molecular compound;
{circle around (3)} a composition comprising a nematic (or smectic) liquid crystalline polyester having the structural units (A) and (B) as essential structural units and an optically active high-molecular compound; and
{circle around (4)} a twisted nematic (or smectic) liquid crystalline polyester having the structural units (A) and (B) as essential structural units and having an optically active group in the molecule thereof.
The nematic (or smectic) liquid crystalline polyester mentioned in each of the above {circle around (1)}, {circle around (2)} and {circle around (3)} forms a nematic (or smectic) orientation free from a twist structure in the state of liquid crystal.
Description will first be directed to the structural units (A) and (B).
The structural unit (A) is formed from a benzenetricarboxylic acid or a trihydroxybenzene. To be more specific, it is a structural unit formed from any of trimesic acid (1,3,5-bezenetricarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), phloroglucinol (1,3,5-trihydroxybenzene), and derivatives thereof. In the present invention, structural units formed from trimesic acid and derivatives thereof are particularly preferred.
In the structural units which constitute the liquid crystalline polyester concerned, the proportion of the structural unit (A) is usually in the range of 0.05 to 15 mol %, preferably 0.10 to 7.5 mol %, particularly preferably 0.20 to 5 mol %. If its proportion is smaller than 0.05 mol %, it may be impossible to improve the orientation holding ability, and if it is larger than 15 mol %, the orientability may be deteriorated markedly.
The structural unit (B) is formed from catechol and derivatives thereof. Examples are as follows:
Among them, the following are particularly preferred in the present invention:
In the structural units which constitute the liquid crystalline polyester, the proportion of the structural unit (B) is in the range of usually 5 to 60 mol %, preferably 7 to 60 mol %. If its proportion is less than 5 mol %, it may be impossible to fix a liquid crystal orientation in glass phase.
In the liquid crystalline polyester used in the present invention, other structural units are not specially limited insofar as they can form the polyester structure and insofar as the structural units (A) and (B) are contained as essential structural units in the bond which constitutes a main chain. As examples of such other structural units, mention may be made of the following aromatic structural units:
where A and B, which may be the same or different, are each independently a carbonyl bond (C═O) or oxygen (O), X and Y, which may be the same or different, are each independently selected from the group consisting of F, Cl, Br, and alkyl groups having 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl), and m and n, which may be the same or different, are each an integer of 0 to 4.
These structural units are formed from terephthalic acid or derivatives thereof, substituted terephthalic acid or derivatives thereof, hydroquinone or derivatives thereof, substituted hydroquinone or derivatives thereof, 4-hydroxybenzoic acid or derivatives thereof, substituted 4-hydroxybenzoic acid or derivatives thereof, isophthalic acid or derivatives thereof
Hosaki Kenji
Kaminade Tadahiro
Kumagai Yoshihiro
Acquah Samuel A.
Nippon Mitsubishi Oil Corporation
Scully Scott Murphy & Presser
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