JPH0383001A - Phase difference plate and production thereof - Google Patents

Abstract

PURPOSE:To obtain the phase difference plate which exhibits double refractiveness in accordance with the orientability of crystals by developing the fluid state matter of a liquid crystal high polymer to orient the molecules or crystals, solidifying this matter under the uncollapse of the orientation state thereof and thereby forming the film. CONSTITUTION:The production of the phase difference plate formed by using the liquid crystal high polymer is executed by developing the fluid state matter consisting of the soln., melt, etc., of the liquid crystal high polymer to orient the molecules or the crystals and solidifying the same under the uncollapse of the orientation state thereof to form the film. A method of dissolving the liquid crystal high polymer into a liquid crystal developable solvent consisting of water or org. solvent, etc., developing the soln. under the imparation of shearing force to form the development layer oriented with the molecules or the crystals and subjecting this layer to a drying treatment is above all preferable in the case of a lyotropic liquid crystal high polymer. The resulted phase difference plate exhibits the holdability of the orientation state of the molecules or crystals in the development layer and the anisotropy as double refraction in the development direction. The drying treatment of the development layer may be executed by heating and drying in the range where the orientation state is not decayed and above all the range where the orientation state is preserved at a high degree.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a retardation plate made of a solidified liquid crystal polymer, and a method for manufacturing the same.

Conventional technologies and problems Conventionally, retardation plates made of plastic films have been produced by forming films from plastics such as polycarbonate, cellulose acetate, polyvinyl chloride, polyolefin, etc., and then stretching the resulting films to orient molecules or crystals. What was made was known.

However, while retardation plates require high optical-level precision in uniformity of thickness, orientation, etc., conventional retardation plates require advanced technology to achieve optical-level high-precision uniformity. However, there were problems in that the yield was poor and that the production efficiency was poor because two steps were required: a film forming process and a stretching process.

Means for Solving the Problems The present invention has succeeded in manufacturing a retardation plate using a liquid crystal polymer, thereby overcoming the above problems.

That is, the present invention provides a retardation plate that is made of a solidified liquid crystal polymer and exhibits birefringence based on the orientation of molecules or crystals, and a retardation plate that is made of a solidified liquid crystal polymer and that is characterized in that it exhibits birefringence based on the orientation of molecules or crystals. The method for producing the retardation plate is characterized in that crystals are oriented and solidified to form a film while the oriented state remains uncollapsed, and a solution in which a lyotropic liquid crystal polymer is dissolved in a solvent is subjected to shearing force. The present invention provides a method for producing the retardation plate described above, which is characterized in that the layer is expanded to form a layer in which molecules or crystals are oriented, and the layer is dried.

The working liquid crystal polymer exhibits liquid crystallinity in a fluid state such as a solution or a melt showing a good orientation state of molecules or crystals. Therefore, it is possible to form an oriented state during the film forming process, and since it is a fluidized material, the formed layer has excellent uniformity or homogeneity. By solidifying without collapsing the orientation of molecules or crystals in the forming layer, a retardation plate exhibiting birefringence based on orientation can be obtained.

Examples of Constituent Elements of the Invention The retardation plate of the present invention is made of a solidified liquid crystal polymer. As the liquid crystal polymer, any suitable material that forms a transparent film or plate may be used.

To manufacture a retardation plate using a liquid crystal polymer, a liquid crystal polymer solution or melt is developed, the molecules or crystals are oriented, and the film is solidified while the oriented state remains uncollapsed. This can be done by In particular, in the case of lyotropic liquid crystal polymers, it is dissolved in a liquid crystal forming solvent such as water or an organic solvent to form a solution, and the solution is expanded under shearing force to orient the molecules or crystals. A method of forming a layer and drying the layer is preferred.

Examples of lyotropic liquid crystal polymers include cellulose derivatives such as hydroxypropyl cellulose and ethyl cellulose, and poly(γ-benzy-L-glutamate).
Examples include polypeptides such as, polyalkyl isocyanates, and the like.

A preferred developing solution can be obtained by dissolving a lyotropic liquid crystal polymer in a liquid crystal-producing solvent to a concentration higher than that which indicates a liquid crystal state. Examples of methods for developing the solution under shearing force include methods using a coater such as an extrusion coater, a rod coater, a curtain coater, a fountain coater, a reverse coater, and a kiss coater.

By developing a solution of lyotropic liquid crystal polymer under shearing force, it is possible to form a developed layer in which molecules or crystals are oriented in the direction of the development, and by drying the developed layer, molecules or crystals can be oriented in the direction of the development. A retardation plate is formed by solidifying and forming a film in an oriented, uncollapsed state.

The obtained retardation plate has excellent ability to maintain the orientation state of molecules or crystals in the spreading layer, and exhibits anisotropy as birefringence in the spreading direction. The spreading layer may be dried by heating within a range that does not disrupt the orientation state, particularly within a range where the orientation state is highly preserved. The birefringence (retardation) of the obtained retardation plate can be controlled by adjusting the degree of orientation by adjusting the viscosity or concentration of the liquid crystal polymer in a fluid state, the thickness of the spreading layer, the applied shear force, etc. .

In the present invention, ultraviolet curable monomers and their curing initiators are blended into a liquid crystal polymer in a fluid state. A retardation plate can also be obtained by a method of developing an A material and then curing the developed layer by irradiating ultraviolet rays or the like to fix the alignment state of the liquid crystal polymer.

The retardation plate of the present invention can be used, for example, as an anti-glare material in which a 1/4 wavelength plate is combined with a polarizing plate to form a circularly polarizing plate, a material for improving the contrast and viewing angle of liquid crystal displays, and a birefringent material for STN liquid crystals. It can be used in various fields, such as optical compensation materials such as coloring prevention materials for liquid crystal cells, and light modulation materials.

Example 1 A 631i% aqueous solution of hydroxypropylcellulose was spread under shearing force using a rod coater to a thickness of 30%.
A 0- spread layer was formed, and this was dried at 95° C. to solidify and form a film to obtain a film-like retardation plate. This retardation plate adhesive tarpsion (wavelength 633 nm, the same applies hereinafter) is
It was 340nlI+.

Example 2 20% by weight of poly(γ-benzy-L-glutamate)
The m-cresol solution was spread with an extrusion coater under shearing force to form a spread layer with a thickness of 300 ua, and this was
A film-form retardation plate was obtained by drying at 20° C. to solidify and form a film. This retardation plate glue tarpsion is 250
It was nIm.

Comparative Example A 35% by weight methylene chloride solution of polycarbonate was spread with a rod coater under shearing force to a thickness of 300 μm.
A spreading layer was formed, and this was dried at 35° C. to form a solidified film, thereby obtaining a film. However, this film did not exhibit birefringence, no retardation was measured, and did not exhibit characteristics as a retardation plate.

Effects of the Invention Since the retardation plate of the present invention is formed by solidifying a liquid crystal polymer in a fluidized state, a stretching process is unnecessary and the production efficiency is excellent. In addition, it has excellent controllability of birefringence properties, and can easily form homogeneous or homogeneous materials.
Excellent yield.

Claims (1)

[Claims] 1. A retardation plate comprising a solidified liquid crystal polymer and exhibiting birefringence based on the orientation of molecules or crystals. 2. The method for manufacturing a retardation plate according to claim 1, characterized in that the liquid crystal polymer in a fluid state is expanded to orient the molecules or crystals, and the film is solidified while the oriented state remains undisintegrated. 3. A solution of a lyotropic liquid crystal polymer dissolved in a solvent is developed under application of shearing force to form a layer in which molecules or crystals are oriented, and the layer is dried. Manufacturing method described.