JPH10206637A - Film for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for an optical element which is easily manufactured and has a large visibility angle expanding effect by fixing a nematic hybrid orientation formed in a liquid crystal condition by a specific liquid crystal polymer. SOLUTION: A unifunctional structural unit is substantially formed of a liquid crystal polymer which has a high molecular chain on the single tail end or both tail ends and optically shows positive uniaxiality. A nematic hybrid orientation formed in a liquid crystal condition by the liquid crystal polymer is fixed. The unifunctional structural unit has a long chain alkyl group having the carbon number 3 to 20 or a long chain fluoroalkyl group having the carbon bumber of 2 to 15 or the like, and is a unit induced from a compound having a functional part such as monoalcohol and a monocarboxylic acid by one. The liquid crystal polymer is a principal chain type liquid crystal polymer such as polyester and polyimide having a unifunctional structural unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for an optical element in which the orientation of an optically positive uniaxial liquid crystalline polymer is fixed, a compensation film for a liquid crystal display element using the film, and a film. The present invention relates to a twisted nematic liquid crystal display device incorporating the same.

[0002]

2. Description of the Related Art An active drive twisted nematic liquid crystal display device (hereinafter abbreviated as a TN-LCD) using a TFT element or an MIM element, etc., is not only thin but light and has low power consumption. Since it has an image quality comparable to that of a CRT when viewed from the front, it is widely used as a display device for notebook computers, portable televisions, portable information terminals, and the like. However, in the conventional TN-LCD, the problem of the viewing angle that the display color changes or the display contrast decreases when viewed obliquely due to the refractive index anisotropy of the liquid crystal molecules is essentially unavoidable. There is a strong demand for improvement, and various attempts have been made for improvement. A method of dividing one pixel and changing the applied voltage to each pixel at a fixed ratio (halftone gray scale method), and a method of dividing one pixel and changing the rising direction of liquid crystal molecules in each pixel ( Domain splitting method), applying a horizontal electric field to liquid crystal (IPS method), driving vertically aligned liquid crystal (VA liquid crystal method), or combining bend alignment cell and optical compensator (OCB method). It has been developed and prototyped. However, although these methods have a certain effect, it is necessary to change the alignment film, electrodes, liquid crystal alignment, etc., and it is necessary to establish a manufacturing technology and to newly install manufacturing equipment. Inviting.

On the other hand, there is a method of expanding the viewing angle by incorporating an optical compensation film into a conventional TN-LCD without changing the structure of the TN-LCD at all. This method uses TN-LC
The D production equipment does not require improvement or expansion, and is excellent in cost, and has the advantage of being easily used. The cause of the problem of the viewing angle in the normally white (NW) mode TN-LCD is the alignment state of the liquid crystal in the cell at the time of displaying black when a voltage is applied. In this case, the liquid crystal is substantially vertically aligned and optically positive uniaxial. Therefore, as an optical compensation film for widening the viewing angle, a proposal has been made to use a film having an optically negative uniaxial property in order to compensate for a positive uniaxial property during black display of a liquid crystal cell. Focusing on the fact that the liquid crystal in the cell has an orientation parallel or inclined to the cell interface near the interface of the alignment film even during black display, compensation is performed using a negative uniaxial film with an inclined optical axis. By doing so, a method of further enhancing the viewing angle expanding effect has been proposed.

For example, Japanese Patent Application Laid-Open No. 4-349424, 6-25
No. 0166 discloses an optical compensation film using a cholesteric film having a helical axis inclined and an L-compensation film using the same.
A CD has been proposed. However, it is difficult to produce a cholesteric film with a helical axis inclined,
In fact, none of these publications describes a method for tilting the helical axis. Further, Japanese Patent Application Laid-Open No. H5-2495
47, 6-331979 proposes an LCD using a negative uniaxial compensator whose optical axis is inclined, and uses a multilayer thin film compensator as a specific embodiment. Further, Japanese Patent Application Laid-Open Nos. 7-146409 and 8-5837 have proposed an optical compensation film in which discotic liquid crystals are inclined and oriented, and an LCD using the same as a negative uniaxial compensation film with an inclined optical axis. However, the discotic liquid crystal has a complicated chemical structure and is complicated to synthesize. In addition, when a film is formed from a low-molecular liquid crystal, a complicated process such as photocrosslinking is required, and industrial production is difficult, resulting in an increase in cost.

As another form of the compensation film, an alignment film using a liquid crystal polymer having positive uniaxiality has been proposed. For example, Japanese Patent Application Laid-Open No. Hei 7-140326 proposes an LCD compensator comprising a liquid crystal polymer film having a twisted tilt orientation, which is used for expanding the viewing angle of the LCD. Although the liquid crystalline polymer film uses a liquid crystalline polymer compound (composition) composed of a difunctional monomer unit, there is a limitation in obtaining bifunctional monomers manufactured on an industrial scale. In addition, it is not industrially easy to simultaneously introduce a twist orientation in addition to the tilt orientation. Also, JP-A-7-198942, 7-18
No. 1324 proposes, as a similar technique, a viewing angle compensator made of a film in which a nematic liquid crystalline polymer is oriented so that an optical axis intersects a plate surface, and an LCD using the same. However, also in this case, since the compensating plate in which the optical axis is simply inclined is used, the viewing angle expanding effect cannot be said to be sufficient.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present inventors can easily obtain a raw material for a liquid crystal compound, and can easily manufacture a liquid crystal compound as a raw material for a film and a film itself. We focused on a novel liquid crystalline polymer. In addition, it avoids the drawbacks of conventional optical compensation films made of liquid crystalline polymers, such as the introduction of twists to improve performance, and achieves a viewing angle widening effect that cannot be obtained with a simple tilt alignment film. As a result of intensive studies, the present invention was finally completed.

[0007]

That is, the first aspect of the present invention is as follows.
Is formed substantially from a liquid crystalline polymer having a monofunctional structural unit at one end or both ends of a polymer chain and exhibiting optically positive uniaxiality. The present invention relates to a film for an optical element, in which a nematic hybrid orientation formed in a state is fixed. Further, a second aspect of the present invention has a monofunctional structural unit at one end or both ends of a polymer chain, and is substantially formed from a liquid crystal polymer which exhibits optically positive uniaxiality. A third aspect of the present invention relates to a compensatory film for a liquid crystal display device, wherein a liquid crystal polymer fixes a nematic hybrid alignment formed in a liquid crystal state. A third aspect of the present invention relates to a nematic liquid crystal and a pair of transparent substrates having electrodes. A driving liquid crystal cell, and an upper polarizing plate disposed above and below the substrate, a twisted nematic liquid crystal display device having at least a lower polarizing plate, wherein the substrate and the upper or lower polarizing plate 3. A liquid crystal display device comprising at least one compensating film for a liquid crystal display element according to claim 2, wherein at least one of the compensating films according to claim 2 is incorporated between at least one of the substrates or between the substrate and the upper and lower polarizing plates. On the nematic liquid crystal display device.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The compensation film of the present invention greatly improves the viewing angle dependence of a TN-LCD. First, a TN-LCD to be compensated will be described. TN-L
When the CD is classified by the driving method, a simple matrix method and a TFT (Thin Film) using an active element as an electrode are used.
Transistor) electrode, MIM (Metal I)
nsulator Metal or TFD; Th
It can be subdivided as in an active matrix method using an (in Film Diode) electrode. The compensation film of the present invention is effective for any driving method.
The halftone gray scale method (pixel division method) and the domain division method, which are well-known techniques, were conceived in an attempt to expand the viewing angle of the LCD from the liquid crystal cell side. L in which such a viewing angle is improved to some extent
The compensating film of the present invention also works effectively on CDs, and can further enhance the viewing angle.

The compensation film for a liquid crystal display element of the present invention comprises:
This is a state in which the nematic hybrid alignment state is fixed. In the present invention, the nematic hybrid orientation refers to an orientation mode in which a liquid crystalline polymer is in a nematic orientation, and an angle between a director of the liquid crystalline polymer and a film plane is different between an upper surface and a lower surface of the film. . Therefore, since the angle formed by the director and the film plane is different between the vicinity of the upper surface interface and the vicinity of the lower surface interface, it is assumed that the angle continuously changes between the upper surface and the lower surface of the film. I can say.

Further, since the compensating film of the present invention is a film in which the nematic hybrid alignment state is fixed, directors of the liquid crystalline polymer are oriented at different angles everywhere in the film thickness direction. Therefore, when viewed as a film structure, the compensation film of the present invention no longer has an optical axis. Next, the monofunctional structural unit which is an essential structural unit of the liquid crystalline polymer of the present invention will be described. The monofunctional structural unit referred to in the present invention has a long-chain alkyl group having 3 to 20 carbon atoms or a long-chain fluoroalkyl group having 2 to 15 carbon atoms, and has a functionality such as monoalcohol and monocarboxylic acid. A unit derived from a compound having one site. The structural unit is represented by the following general formula.

[0011]

Embedded image

In the above general formula, R1 and R2 may be the same or different. R1 and R2 represent a long-chain alkyl group having 3 to 20 carbon atoms or a long-chain fluoroalkyl group having 2 to 15 carbon atoms. In particular,

[0013]

Embedded image

And the like can be exemplified as preferable ones. X is a halogen such as hydrogen, fluorine and chlorine. I is 0 or 1. And j is
It is 0 or 1. K is 0 or 1. A is 0 or 1, and b is 0 or 1. However, a + b
≠ 0. As the monofunctional structural unit of the present invention formed from the above monoalcohol, monocarboxylic acid and their functional derivatives,

[0015]

Embedded image

And the like can be exemplified as the preferred unit. One end or both ends of the polymer chain are constituted by one or two selected from the monofunctional structural units exemplified above. When the structural units are present at both ends, the units at both ends need not be the same. The monofunctional structural unit is important for the compensation film for a liquid crystal display device of the present invention. It is important for the compensation film to set an arbitrary optical parameter, but in the compensation film of the present invention, the optical parameter can be set to a desired value depending on the type and combination of the structural units. Due to this characteristic, the present compensation film has a TN
-It exhibits an excellent viewing angle compensation effect that has not been achieved in conventional LCDs.

The liquid crystalline polymer of the present invention will be further described. The liquid crystalline polymer having a monofunctional structural unit and exhibiting optically positive uniaxiality according to the present invention has a nematic phase as a liquid crystal phase. Further, at a temperature exceeding the liquid crystal transition point on the alignment substrate, it is essential that the film be capable of forming a nematic hybrid alignment and fixing it in a glassy state without impairing the alignment form.

As the liquid crystalline polymer having the above-mentioned properties, it has one or two monofunctional structural units described above at one end or both ends, and has an optically positive uniaxial property. Liquid crystalline polymer shown, specifically, a homeotropically oriented main chain type liquid crystalline polymer compound having the structural unit or a liquid crystalline polymer composition containing at least one kind of the liquid crystalline polymer compound, One or more kinds of homeotropically-aligned liquid crystalline polymers having the structural unit, and one or more kinds of liquid crystalline polymers different from the liquid crystalline polymers and / or polymers showing no liquid crystallinity And a composition containing at least one or more of the following. Hereinafter, description will be made in order.

First, a liquid crystalline polymer having one or two kinds of monofunctional structural units at one end or both ends and exhibiting homeotropic alignment will be described. The homeotropic alignment refers to an alignment state in which the director is substantially perpendicular to the substrate plane. This homeotropic alignment liquid crystalline polymer is an essential component for realizing the nematic hybrid alignment of the present invention. The determination as to whether the liquid crystalline polymer has homeotropic alignment is performed by forming a liquid crystalline polymer layer on a substrate and determining the alignment state.
The substrate that can be used for this determination is not particularly limited, but examples thereof include a glass substrate (specifically, an optical glass such as soda glass, potash glass, borosilicate glass, crown glass, and flint glass), Plastic film or sheet having heat resistance at the liquid crystal temperature of molecules, for example, polyethylene terephthalate, polyethylene naphthalate, polyphenylene oxide, polyimide, polyamide imide, polyether imide, polyamide, polyether ketone, polyether ether ketone, polyketone sulfide, polyether Sulfone etc. can be mentioned. The substrate exemplified above is used after its surface is cleaned with an acid, alcohol, detergent or the like. Further, the determination of the orientation should be performed on a substrate that has not been subjected to a surface treatment such as a silicon treatment, a rubbing treatment, or a uniaxial stretching treatment.

The liquid crystalline polymer having one or two kinds of monofunctional structural units at one end or both ends and exhibiting homeotropic alignment used in the present invention is obtained by subjecting these to suitable surface treatment. When a film of a liquid crystalline polymer is formed on a substrate that has not been subjected to heat treatment at a temperature at which the liquid crystalline polymer exhibits a liquid crystal state, at least one of these exemplified substrates is used.
In the present invention, what is homeotropically aligned on a kind of substrate is defined as the liquid crystalline polymer. However, some liquid crystalline polymers are specifically homeotropically aligned at a temperature near the liquid crystal-isotropic phase transition point. So usually
The heat treatment operation as described above is performed at a temperature of 15 to
It is desirable to carry out at a temperature of not more than 20 ° C, preferably at most 20 ° C. A liquid crystalline polymer having one or two types of monofunctional structural units at one end or both ends and exhibiting homeotropic alignment will be specifically described. The liquid crystalline polymer that can be used in the present invention is not particularly limited as long as it has one or two types of monofunctional structural units at one end or both ends and has the above properties. Not done. In order for the liquid crystalline polymer used in the present invention to exhibit homeotropic alignment, it is important that the polymer has the above-described monofunctional structural unit and that the molecular weight is appropriate.

Specific examples of the liquid crystalline polymer include a main chain type liquid crystalline polymer having a monofunctional structural unit such as polyester, polyimide, polyamide, polycarbonate, and polyesterimide. Among these, liquid crystalline polyesters are particularly preferred from the viewpoints of easiness of synthesis, easiness of forming a film and stability of physical properties of the obtained film. The main chain forming component of the liquid crystalline polyester is not particularly limited, such as a difunctional structural unit such as a dicarboxylic acid unit, a diol unit, and an oxycarboxylic acid unit, and a polyfunctional structural unit other than the unit. However, when used as a compensating film for a liquid crystal display element as in the present invention, a liquid crystalline polyester having an ortho-substituted aromatic unit as a structural unit in the main chain is more preferable. Specifically, catechol units, salicylic acid units, phthalic acid units, 2,3-naphthalenediol units, 2,3
-Naphthalenedicarboxylic acid units and those having a substituent on the benzene ring thereof.

[0022]

Embedded image

(Y is hydrogen, halogen such as Cl, Br,
Methyl group, ethyl group, methoxy group, ethoxy group tert
-Represents a butyl group or a phenyl group. K is 0 to 2; Hereinafter, specific structural examples of the liquid crystalline polymer having homeotropic alignment used in the present invention will be described.

[0024]

Embedded image

M + n = k / 2 + l k / l = 80/60 to 2/99, preferably 40/8
0/10/95 m / n = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0026]

Embedded image

L = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0028]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10) preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0030]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0032]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0034]

Embedded image

N + o = k / 2 + m k / m = 80/60 to 2/99, preferably 40/8
0/10/95 n / o = 100/0 to 0/100, preferably 95 /
5/5/95 1 / (n + o) = 20 / 10-0 / 10, preferably
15/10 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0036]

Embedded image

M + n = k / 2 + l k / l = 80/60 to 2/99, preferably 40/8
0/10/95 m / n = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0038]

Embedded image

M = k / 2 + n k / n = 80/60 to 2/99, preferably 40/8
0/10/95 l / m = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, and n each indicate a molar composition ratio.

[0040]

Embedded image

1 = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0042]

Embedded image

1 + m = k / 2 + n k / n = 80/60 to 2/99, preferably 40/8
0/10/95 l / m = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0044]

Embedded image

N + o = k / 2 + m k / m = 80/60 to 2/99, preferably 40/8
0/10/95 n / o = 100/0 to 0/100, preferably 95 /
5/5/95 1 / (n + o) = 20 / 10-0 / 10, preferably 1
5/10 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0046]

Embedded image

M + n = k / 2 + ok k / o = 80/60 to 2/99, preferably 40/8
0/10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 1 / (m + n) = 20 / 10-0 / 10, preferably
15/10 to 5/10 i represents an integer of 2 to 12. k, l, m, n, and o each represent a molar composition ratio.

[0048]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0050]

Embedded image

M + n = k / 2 + ok k / o = 80/60 to 2/99, preferably 40/8
0/10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 1 / (m + n) = 20 / 10-0 / 10, preferably
15/10 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0052]

Embedded image

L + m = k / 2 + n + ok k / (n + o) = 80/60 to 2/99, preferably
40 / 80-10 / 95 l / m = 100 / 0-0 / 100, preferably 95 /
5/5/95 n / o = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m, n, and o each represent a molar composition ratio.

[0054]

Embedded image

N + o = k / 2 + m k / m = 80/60 to 2/99, preferably 40/8
0/10/95 n / o = 100/0 to 0/100, preferably 95 /
5/5/95 l / m = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0056]

Embedded image

1 + m = k / 2 + 7 k / 7 = 80/60 to 2/99, preferably 40/8
0/10/95 l / m = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0058]

Embedded image

N + o = k / 2 + l + mk / (l + m) = 80/60 to 2/99, preferably
40 / 80-10 / 95 l / m = 100 / 0-0 / 100, preferably 95 /
5/5/95 n / o = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m, n, and o each represent a molar composition ratio.

[0060]

Embedded image

M = k / 2 + n + ok k / (n + o) = 80/60 to 2/99, preferably
40 / 80-10 / 95 n / o = 100 / 0-0 / 100, preferably 95 /
5/5/95 l / m = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0062]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / m = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0064]

Embedded image

N + o = k / 2 + 1 + m k / (l + m) = 80/60 to 2/99, preferably
40 / 80-10 / 95 l / m = 100 / 0-0 / 100, preferably 95 /
5/5/95 n / o = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m, n, and o each represent a molar composition ratio.

[0066]

Embedded image

O = k / 2 + m + nk / (m + n) = 80/60 to 2/99, preferably
40/80 to 10/95 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0068]

Embedded image

L + m = k / 2 + n + ok k / (n + o) = 80/60 to 2/99, preferably
40 / 80-10 / 95 l / m = 100 / 0-0 / 100, preferably 95 /
5/5/95 n / o = 100/0 to 0/100, preferably 95 /
5-5 / 95 i represents an integer of 2-12. k, l, m, n, and o each represent a molar composition ratio.

[0070]

Embedded image

O = k / 2 + n k / n = 80/60 to 2/99, preferably 40/8
0/10/95 l / m = 100/0 to 0/100, preferably 95 /
5/5/95 (l + m) / o = 20/10/1/10, preferably
15/10 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0072]

Embedded image

O = k / 2 + l / 2 + m + n (k + 1) / (m + n) = 80/60 to 2/99, preferably 40/80 to 10/95 k / l = 100/0 to 0/100, preferably 90 /
10-10 / 90 m / n = 100 / 0-0 / 100, preferably 95 /
5 to 5/95 k, l, m, n, and o each represent a molar composition ratio.

[0074]

Embedded image

O + p = k / 2 + 1/2 + n (k + 1) / n = 80/60 to 2/99, preferably
40/80 to 10/95 k / l = 100/0 to 0/100, preferably 90 /
10-10 / 90 o / p = 100 / 0-0 / 100, preferably 95 /
5/5/95 m / n = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, o, and p each represent a molar composition ratio.

Among the above, particularly, [Structural formula 1], [Structural formula 3], [Structural formula 4], [Structural formula 9], [Structural formula 1]
1], [Structural formula 16], [Structural formula 20], [Structural formula 2]
2], liquid crystalline polyesters of [Structural Formula 23] and [Structural Formula 25] are preferable. The homeotropically-aligned liquid crystalline polymer described above may be used alone or in at least one form.
The present invention can be used as a composition containing a kind of the liquid crystalline polymer. When used as a composition, even a composition containing a plurality of liquid crystalline polymers having different structural units can be used in the present invention without any problem as long as the composition has the above-mentioned properties. In order to exhibit good homeotropic alignment, the molecular weight of the liquid crystalline polymer is also important as described above. As for the molecular weight of the liquid crystalline polymer, the logarithmic viscosity measured at 30 ° C. in various solvents such as a phenol / tetrachloroethane (60/40 (weight ratio)) mixed solvent is preferably 0.04 to 1.5, More preferably, it is in the range of 0.06 to 1.0. If the logarithmic viscosity is less than 0.04, the mechanical strength of the compensating film is undesirably weak. If it is larger than 1.5, homeotropic orientation may be lost. Also, the viscosity may be too high in the liquid crystal state,
Even if homeotropic alignment is performed, the time required for alignment may be long.

The method for synthesizing the above liquid crystalline polymer is not particularly limited. It can be synthesized by a polymerization method known in the art. For example, taking the synthesis of a liquid crystalline polyester as an example, it can be synthesized by a melt polymerization method or an acid chloride method using a corresponding acid chloride of dicarboxylic acid.

In synthesizing the liquid crystalline polymer of the present invention, the monofunctional structural unit includes the above-described monoalcohol, monocarboxylic acid compound and their functional derivatives, specifically, acetylated compounds and halogenated compounds. Is supplied to the polymerization reaction as a compound. The content of the monofunctional structural unit in the liquid crystalline polymer, specifically, the content in the liquid crystalline polyester,
The molar fraction of the remaining constituent components excluding the hydroxycarboxylic acid structural unit is in the range of 2/201 to 80/240. More preferably, 10/205 to 20/220
Range. When the content of the monofunctional structural unit is 2/21
If it is less than 0 (molar fraction), the liquid crystalline polyester may not show homeotropic alignment. When the content of the monofunctional structural unit is larger than 80/240, the molecular weight of the liquid crystalline polyester may not be increased to a desired value. Further, when a compensation film is produced, the mechanical strength of the film becomes weak, which is not preferable. The content of the monofunctional structural unit depends on the charged amount of the monomer component.

In the present invention, another liquid crystal polymer compound (or composition) or a polymer compound having no liquid crystal property (or composition) is added to the above-described homeotropic alignment liquid crystal polymer. A liquid crystalline polymer composition can also be used. The use of the composition has advantages in that the average tilt angle of the nematic hybrid alignment can be freely controlled by adjusting the composition ratio, and the nematic hybrid alignment can be stabilized. When used as a composition, it is desirable to contain the homeotropically-aligned liquid crystalline polymer described above in an amount of 5% by weight or more. If it is less than 5% by weight, the nematic hybrid orientation of the present invention may not be obtained.

As the polymer compound (or composition) to be added to the homeotropically-aligned liquid crystalline polymer, various polymers that do not exhibit liquid crystallinity can be used. From the viewpoint of compatibility, it is also preferable to use a liquid crystalline polymer. As the type of the liquid crystal polymer used, a main chain type liquid crystal polymer, for example, polyester, polyimide, polyamide,
Examples include polyester, polycarbonate, and polyesterimide. In addition, side chain type liquid crystalline polymers such as polyacrylate, polymethacrylate, polysiloxane, and polymalonate can also be exemplified. It is not particularly limited as long as it has compatibility with the homeotropic alignment liquid crystalline polymer, and among them, the liquid crystalline polyester having an ortho-substituted aromatic unit in the main chain as exemplified above is most preferable. . Further, these liquid crystalline polymers may have any orientation, such as homogeneous, tilt orientation or other orientation, but are not particularly limited. Among them, homogeneously oriented liquid crystalline polymers (compositions) Is more preferred. The determination of the homogeneous orientation is performed using the substrate that has not been subjected to a surface treatment such as a silicon treatment, a rubbing treatment, or a uniaxial stretching treatment, similarly to the determination of the homeotropic orientation. Forming a liquid crystalline polymer layer on the substrate,
It is determined whether or not a homogeneous orientation is exhibited according to the orientation state. Hereinafter, specific structural examples of the liquid crystalline polymer exhibiting homogeneous alignment will be described.

[0081]

Embedded image

K = l + ml / m = 80/20 to 20/80, preferably 75 /
25 to 25/75 k, l, and m each indicate a molar composition ratio.

[0083]

Embedded image

O = m + n (k + 1) / o = 20/10 to 0/10, preferably
15/10 to 0/10 m / n = 100/0 to 0/10
0, preferably 98/2 to 2/98 k, l, m, n and o each represent a molar composition ratio.

[0085]

Embedded image

N = 1 + m k / m = 20/10 to 0/10, preferably 15/1
0 to 0/10 k, l, m and n each indicate a molar composition ratio.

[0087]

Embedded image

K + 1 = m + n k / l = 100/0 to 0/100, preferably 95/0
5/5/95 m / l = 100 / 0-0 / 100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0089]

Embedded image

K + 1 = m + n k / l = 100/0 to 0/100, preferably 95 /
5/5/95 m / n = 100 / 0-0 / 100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0091]

Embedded image

L = m + nk / l = 15/10 to 0/10, preferably 10/1
0/0/10 m / n = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0093]

Embedded image

M + n = k / 2 + l k / l = 40/80 to 0/100, preferably 20 /
90-0 / 100 m / n = 100 / 0-0 / 100, preferably 95/0
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0095]

Embedded image

O = k / 2 + m + nk / (m + n) = 40/80 to 0/100, preferably 20/90 to 0/100 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0097]

Embedded image

O = k / 2 + m + nk / (m + n) = 40/80 to 0/100, preferably 20/90 to 0/100 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0099]

Embedded image

1 = k / 2 + m + nk / (m + n) = 40/80 to 0/100, preferably 20/90 to 0/100 n / m = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m and n each represent a molar composition ratio.

[0101]

Embedded image

M = k / 2 + n + ok k / (n + o) = 40/80 to 0/100, preferably 20/90 to 0/100 n / o = 100/0 to 0/100, preferably 95 /
5/5/95 l / m = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0103]

Embedded image

O = k / 2 + m + nk / (m + n) = 40/80 to 0/100, preferably 20/90 to 0/100 m / n = 100/0 to 0/100, preferably 95 /
5/5/95 l / o = 20 / 10-0 / 10, preferably 15/1
0 to 5/10 k, l, m, n, and o each indicate a molar composition ratio.

[0105]

Embedded image

N + o = k / 2 + l + m k / (l + m) = 40/80 to 0/100, preferably 20/90 to 0/100 l / m = 100/0 to 0/100, preferably 95 /
5/5/95 n / o = 100/0 to 0/100, preferably 95 /
5 to 5/95 k, l, m, n, and o each represent a molar composition ratio.

The logarithmic viscosity of these compounds as measured at 30 ° C. in various solvents, for example, a mixed solvent of phenol / tetrachloroethane (60/40 (weight ratio)) is preferably 0.05 to 3.0. Preferably 0.
Range from 07 to 2.0. If the logarithmic viscosity is less than 0.05, the mechanical strength of the compensation film may be weak. On the other hand, if it is larger than 3.0, the homeotropic alignment may be impaired, or the viscosity at the time of forming the liquid crystal may become too high, and the time required for the alignment may become longer, which is not desirable. The method for synthesizing the above liquid crystalline polymer is not particularly limited. The liquid crystalline polymer that can be used in the present invention can be synthesized by a polymerization method known in the art. For example, if polyester synthesis is taken as an example, it can be synthesized by a melt polymerization method or an acid chloride method using a corresponding acid chloride of dicarboxylic acid. One or two types at one or both ends described above
The optical system according to the present invention, in which a nematic hybrid alignment is uniformly performed on an alignment substrate using a liquid crystalline polymer having a kind of monofunctional structural unit and exhibiting positive uniaxiality, and the alignment form is fixed. In order to obtain a film for an element, it is preferable in the present invention that an alignment substrate and each step described below are taken.

First, the alignment substrate will be described. As in the present invention, in order to obtain a nematic hybrid alignment using the liquid crystalline polymer, it is desirable to sandwich the upper and lower sides of the liquid crystalline polymer layer at different interfaces. The alignment at the upper and lower interfaces of the liquid crystalline polymer layer becomes the same, and it becomes difficult to obtain the nematic hybrid alignment of the present invention. As a specific mode, one alignment substrate and the air interface are used, and the lower interface of the positive uniaxial liquid crystal polymer layer is used as the alignment substrate, and the upper interface of the liquid crystal polymer layer is used as the air interface. Contact with Although it is possible to use an alignment substrate having different upper and lower interfaces, it is preferable to use one alignment substrate and an air interface from the viewpoint of the manufacturing process.

The alignment substrate that can be used in the present invention includes:
It is desirable to have anisotropy so that the tilt direction of the liquid crystal molecules (projection of the director onto the alignment substrate) can be defined. If the alignment substrate cannot define the direction in which the liquid crystal is tilted at all, only an alignment mode tilted in a random direction can be obtained (the vector projected from the director onto the substrate becomes disordered).

As the alignment substrate that can be used in the present invention, specifically, one having in-plane anisotropy is desirable, and polyimide, polyamide imide, polyamide, polyether imide, polyether ether ketone, polyether Ether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol,
Plastic film substrates such as polypropylene, cellulosic plastics, epoxy resin, and phenolic resin, and uniaxially stretched plastic film substrates; metal substrates such as aluminum, iron, and copper with slit-shaped grooves on the surface;
Glass substrates such as alkali glass, borosilicate glass, and flint glass, the surfaces of which are etched in a slit shape, and the like.

In the present invention, a rubbing plastic film substrate obtained by subjecting the above-mentioned plastic film substrate to rubbing treatment, a plastic thin film subjected to rubbing treatment, such as the above-mentioned various substrates having a rubbing polyimide film, a rubbing polyvinyl alcohol film, etc., and further comprising silicon oxide The various substrates described above having an obliquely deposited film or the like can also be used. In the above various alignment substrates, suitable substrates for forming the liquid crystalline polymer of the present invention in a nematic hybrid alignment include various substrates having a rubbing polyimide film, a rubbing polyimide substrate, a rubbing polyetheretherketone substrate, and a rubbing polyether substrate. Ether ketone substrate, rubbing polyether sulfone substrate,
A rubbing polyphenylene sulfide substrate, a rubbing polyethylene terephthalate substrate, a rubbing polyethylene naphthalate substrate, a rubbing polyarylate substrate, and a cellulose-based plastic substrate can be given.

In the film for an optical element of the present invention, the angle formed by the director of the positive uniaxial liquid crystalline polymer and the film plane is different between the upper surface and the lower surface of the film. The film surface on the substrate side can be adjusted to any angle range of 0 ° or more and 50 ° or less or 60 ° or more and 90 ° or less depending on the method of the alignment treatment and the type of the positive uniaxial liquid crystalline polymer. Normally, it is desirable in the manufacturing process to adjust the angle between the director of the liquid crystalline polymer near the interface of the film in contact with the alignment substrate and the plane of the film within the range of 0 to 50 degrees. The film for an optical element of the present invention,
It is obtained by applying a positive uniaxial liquid crystalline polymer uniformly on the alignment substrate as described above, followed by a uniform alignment process and a process of fixing the alignment form. The application of the liquid crystalline polymer to the alignment substrate can be usually performed in a solution state in which a positive uniaxial liquid crystalline polymer is dissolved in various solvents or in a molten state in which the liquid crystalline polymer is melted. From the viewpoint of the production process, it is preferable to apply a solution by applying the solution obtained by dissolving a positive uniaxial liquid crystalline polymer in a solvent.

The solution coating will be described. The liquid crystalline polymer of the present invention is dissolved in a solvent to prepare a solution having a predetermined concentration.
The thickness of the film (thickness of the layer formed from the positive uniaxial liquid crystalline polymer) is determined at the stage of applying the liquid crystalline polymer to the substrate, so that the concentration, the thickness of the coating film, etc., are precisely determined. Need to be controlled.

The above-mentioned solvent cannot be specified unconditionally depending on the type (composition ratio, etc.) of the positive uniaxial liquid crystalline polymer, but usually, chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene. , Chlorobenzene, halogenated hydrocarbons such as orthodichlorobenzene, phenols, phenols such as parachlorophenol,
Benzene, toluene, xylene, methoxybenzene,
Aromatic hydrocarbons such as 1,2-dimethoxybenzene, acetone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone, N-methyl-2-pyrrolidone, pyridine, triethylamine, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, acetonitrile, butyronitrile, carbon disulfide and the like, and a mixed solvent thereof such as halogenated hydrocarbons and phenol And the like.

The concentration of the solution cannot be determined unconditionally because it depends on the solubility of the positive uniaxial liquid crystalline polymer to be used and the final thickness of the target compensating film, but is usually 3 to 50% by weight. And preferably in the range of 7 to 30% by weight. A positive uniaxial liquid crystalline polymer solution adjusted to a desired concentration using the above-mentioned solvent is then applied onto the above-described alignment substrate. The coating method includes spin coating, roll coating, die coating, printing,
An immersion pulling method, a curtain coating method, or the like can be employed.
After the application, the solvent is removed, and a layer of a liquid crystalline polymer having a uniform thickness is formed on the alignment substrate. The solvent removal conditions are not particularly limited, and it is sufficient that the solvent can be removed substantially and the layer of the positive uniaxial liquid crystalline polymer does not flow or fall off. Usually, the solvent is removed by drying at room temperature, drying in a drying furnace, or blowing hot or hot air. The purpose of this coating / drying step is to first form a liquid crystal polymer layer uniformly on the substrate, and the liquid crystal polymer has not yet formed a nematic hybrid orientation. In the next heat treatment step, a monodomain nematic hybrid alignment is completed.

In forming the nematic hybrid alignment by the heat treatment, the viscosity of the positive uniaxial liquid crystalline polymer is preferably lower in order to assist the alignment by the interface effect, and therefore, the heat treatment temperature is preferably higher. Also, depending on the liquid crystalline polymer, the average tilt angle obtained may vary depending on the heat treatment temperature. In that case, it is necessary to set the heat treatment temperature in order to obtain an average tilt angle according to the purpose. For example, when it is necessary to perform heat treatment at a relatively low temperature in order to obtain an alignment having a certain tilt angle, the viscosity of the liquid crystalline polymer is high at a low temperature, and the time required for the alignment becomes long. In such a case, a method is effective in which a heat treatment is once performed at a high temperature to obtain a monodomain orientation, and then the temperature of the heat treatment is gradually or gradually reduced to a target temperature. In any case, it is preferable to perform heat treatment at a temperature equal to or higher than the glass transition point according to the characteristics of the positive uniaxial liquid crystalline polymer to be used. The heat treatment temperature is usually 50 ° C to 30 ° C.
A range of 0 ° C. is preferred, and a range of 100 ° C. to 260 ° C. is particularly preferred. In addition, the heat treatment time required for the positive uniaxial liquid crystal polymer to be sufficiently aligned on the alignment substrate varies depending on the type (for example, composition ratio) of the liquid crystal polymer to be used and the heat treatment temperature. Although it cannot be said, usually the range of 10 seconds to 120 minutes is preferable,
A range from 0 seconds to 60 minutes is preferred. If the time is shorter than 10 seconds, the orientation may be insufficient. If the time is longer than 120 minutes, productivity may decrease, which is not desirable.
In this way, a uniform nematic hybrid alignment can be obtained in the liquid crystal state over the entire surface of the alignment substrate.

In the present invention, in the heat treatment step, a magnetic field or an electric field may be used in order to align the positive uniaxial liquid crystalline polymer in a nematic hybrid orientation. However, when a magnetic field or an electric field is applied while performing heat treatment, a uniform field force acts on the liquid crystalline polymer during the application, so that the director of the liquid crystal tends to turn in a certain direction. That is, it is difficult to obtain a nematic hybrid orientation in which the director forms different angles depending on the film thickness direction as in the present invention. Once a non-nematic hybrid orientation, such as homeotropic, homogenous, tilt orientation or other orientation, is formed, a thermally stable nematic hybrid orientation can be obtained by removing the force of the field, but this is particularly advantageous in the process. There is no.

The nematic hybrid alignment formed in the liquid crystal state of the positive uniaxial liquid crystalline polymer is
Next, by cooling to a temperature below the liquid crystal transition point of the liquid crystalline polymer, the liquid crystal polymer can be fixed without impairing the uniformity of the alignment at all. In general, when a liquid crystalline polymer having a smectic phase or a crystalline phase in a lower temperature portion than a nematic phase is used, nematic alignment in a liquid crystal state may be broken by cooling. In the present invention, it has no smectic phase or crystalline phase at a temperature lower than the temperature range showing the nematic phase, and even if it has a potential crystalline phase or smectic phase, no smectic phase or crystalline phase appears upon cooling. The use of a liquid crystalline polymer that has properties such that it has no fluidity in the operating temperature range of the optical element film and does not change its alignment form even when an external field or external force is applied. Thus, the orientation morphology is not destroyed by the phase transition, and the monodomain nematic hybrid orientation can be completely fixed.

The cooling temperature is not particularly limited as long as it is lower than the liquid crystal transition point. For example, 10 ° C from the liquid crystal transition point
By cooling at a low temperature, uniform nematic hybrid orientation can be fixed. There is no particular limitation on the cooling means, and the cooling is carried out by simply taking out from the heating atmosphere in the heat treatment step to an atmosphere below the liquid crystal transition point, for example, room temperature. In order to increase production efficiency, forced cooling such as air cooling or water cooling or cooling may be performed.
However, the average tilt angle obtained depending on the cooling rate may be slightly different depending on the positive uniaxial liquid crystalline polymer. When it is necessary to use such a liquid crystalline polymer and strictly control the angle, it is preferable to perform a cooling operation in consideration of cooling conditions as appropriate.

Next, the angle control in the film thickness direction of the nematic hybrid orientation in the present invention will be described. In the present compensation film, the absolute value of the angle formed by the director of the positive uniaxial liquid crystalline polymer and the film plane in the vicinity of the film interface is 0 ° or more and 50 ° or less on one of the upper surface and the lower surface of the film. Within the range, and on the surface opposite to the surface, the range is 60 degrees or more and 90 degrees or less. The desired angle can be controlled by appropriately selecting the type (composition, etc.) of the positive uniaxial liquid crystalline polymer to be used, the alignment substrate, the heat treatment conditions, and the like.
Even after the nematic hybrid orientation is fixed, the angle can be controlled to a desired angle by using a method such as uniformly shaving the film surface or immersing the film surface in a solvent to uniformly dissolve the film surface. The solvent used at this time is appropriately selected depending on the type (composition or the like) of the positive uniaxial liquid crystalline polymer and the type of the alignment substrate. The film for an optical element of the present invention obtained by the above steps is obtained by uniformly aligning and fixing an alignment form called nematic hybrid alignment. Further, since the orientation is formed, the upper and lower portions of the film are not equivalent, and there is anisotropy in the in-plane direction. Accordingly, various characteristics can be obtained by using the film as a compensation film for a liquid crystal display element and disposing the film on an LCD.

The method of using the film for an optical element as a compensation film for a liquid crystal display element will be described in detail below. When the compensation film of the present invention is actually arranged in a twisted nematic liquid crystal cell, the orientation substrate described above is peeled off from the film as a mode of use of the film, and the compensation film is used alone. It is possible to use the compensation film laminated on another substrate different from the alignment substrate. When used as a single film, a method of mechanically peeling the oriented substrate with a roll at the interface with the compensation film, a method of mechanically peeling after dipping in a poor solvent for all structural materials, A method of peeling by applying ultrasonic waves, a method of peeling by applying a temperature change using a difference in thermal expansion coefficient between the oriented substrate and the film, dissolving and removing the oriented substrate itself or the oriented film on the oriented substrate A film alone is obtained by a method or the like. Since the releasability depends on the type (composition or the like) of the positive uniaxial liquid crystalline polymer to be used and the adhesion to the alignment substrate, a method most suitable for the system should be adopted. When the compensation film is used alone, it may not have self-supporting property depending on the film thickness. In that case, a substrate which is preferable in optical properties, for example, polymethacrylate, polycarbonate, polyvinyl alcohol, polyether sulfone, polysulfone, polyarylate , Polyimide,
It is more desirable to use the film by fixing it on a plastic substrate such as amorphous polyolefin or triacetyl cellulose via an adhesive or a pressure-sensitive adhesive for the strength and reliability of the compensation film.

Next, a case where the compensation film is used in a state formed on an alignment substrate will be described. The alignment substrate is transparent and optically isotropic, or the alignment substrate is TN-L
If the member is necessary for the CD, it can be incorporated into the TN-LCD as a target compensating element as it is. Further, the compensatory film of the present invention obtained by aligning and fixing the positive uniaxial liquid crystalline polymer on the alignment substrate is peeled off from the substrate, and laminated on another substrate more suitable for optical use. That is, a laminate composed of at least the film and another substrate different from the alignment substrate can be incorporated in the TN-LCD as a compensation element.

For example, the alignment substrate to be used is necessary for obtaining a nematic hybrid alignment.
In the case where such a substrate having an unfavorable effect on the N-LCD is used, the substrate can be used after being removed from the compensation film after the alignment is fixed. Specifically, the following method can be adopted. Target TN-LC
A substrate (hereinafter, referred to as a second substrate) suitable for a liquid crystal display element incorporated in D and a compensation film on an alignment substrate are attached using, for example, an adhesive or an adhesive. Next, the alignment substrate is peeled off at the interface with the compensation film of the present invention, and the compensation film can be transferred to a second substrate side suitable for a liquid crystal display element to obtain a compensation element. The second substrate used for the transfer is not particularly limited as long as it has appropriate flatness, but a glass substrate or a transparent plastic film having optical isotropy is preferably used. Examples of such a plastic film include polymethyl methacrylate, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, polyarylate, amorphous polyolefin, triacetyl cellulose, and epoxy resin. Among them, polymethyl methacrylate, polycarbonate, polyarylate, polyether sulfone,
Triacetyl cellulose and the like are preferably used. Even if it is optically anisotropic, an optically anisotropic film can be used if it is a necessary member for a TN-LCD. Examples of such a film include a retardation film and a polarizing film obtained by stretching a plastic film such as polycarbonate or polystyrene.

Further, a liquid crystal cell itself can be cited as an example of the second substrate used. The liquid crystal cell is
The upper and lower glass or plastic substrates with electrodes are used, and if the compensating film of the present invention is transferred onto either the upper or lower glass or plastic substrate, the incorporation of the compensating film has already been achieved. become. Of course, it is also possible to manufacture the present compensation film using the glass or plastic substrate itself forming the liquid crystal cell as an alignment substrate. The second substrate described above does not need to have substantially the ability to control the alignment of the positive uniaxial liquid crystalline polymer. Further, an alignment film or the like is not required between the second substrate and the film. The adhesive or pressure-sensitive adhesive for adhering the second substrate used for the transfer and the compensation film of the present invention is not particularly limited as long as it is of an optical grade, but may be acrylic, epoxy or ethylene-vinyl acetate. Polymers, rubbers, urethanes, and mixtures thereof can be used. As the adhesive, any adhesive such as a thermosetting type, a photocuring type, and an electron beam curing type can be used without any problem as long as it has optical isotropy.

The transfer of the compensating film of the present invention to a second substrate suitable for a liquid crystal display device can be performed by peeling the oriented substrate at the interface with the film after bonding. As described above, the method of peeling is a method of mechanical peeling using a roll or the like, a method of mechanically peeling after immersing in a poor solvent for all structural materials, and a peeling by applying ultrasonic waves in a poor solvent. Examples of the method include a method of performing separation by giving a temperature change using a difference in thermal expansion coefficient between an oriented substrate and the film, a method of dissolving and removing an oriented substrate itself or an oriented film on an oriented substrate, and the like. it can. Since the releasability depends on the type (composition and the like) of the positive uniaxial liquid crystalline polymer to be used and the adhesion to the alignment substrate, a method most suitable for the system should be adopted. The compensation film of the present invention may be provided with a protective layer such as a transparent plastic film for the purpose of protecting the surface, increasing the strength, and improving environmental reliability.

The compensation film thus obtained is
The TN-LCD has a particularly excellent viewing angle compensation effect. The thickness of the compensation film is such that the film exhibits a more suitable compensation effect for various TN-LCDs.
Since it depends on the target TN-LCD system and various optical parameters, it cannot be said unconditionally.
In the range of not less than 20 μm and more preferably not more than 0.2 μm.
μm or more and 10 μm or less, particularly preferably 0.3 μm
The range is at least 5 μm. When the film thickness is less than 0.1 μm, there is a possibility that a sufficient compensation effect cannot be obtained. If the thickness exceeds 20 μm, the display may be unnecessarily colored. However, in order to further enhance the performance of the compensation film of the present invention, it is desirable to consider the optical parameters and the axial arrangement of the compensation film in more detail. This will be individually described below. First, the in-plane apparent retardation value when viewed from the normal direction of the film will be described. In a film having a nematic hybrid orientation, the refractive index in the direction parallel to the director (hereinafter referred to as n)
e) and the refractive index in the direction perpendicular to the direction (hereinafter referred to as no). When a value obtained by subtracting no from ne is an apparent birefringence, the apparent retardation value is given by the product of the apparent birefringence and the absolute film thickness. This apparent retardation value can be easily obtained by polarization optical measurement such as ellipsometry. The apparent retardation value of the compensation film of the present invention is:
For monochromatic light of 550 nm, usually 5 nm to 500 n
m, more preferably 10 nm to 300 nm, particularly preferably 15 nm to 150 nm. When the apparent retardation value is less than 5 nm,
There is substantially no difference from homeotropic alignment, and a sufficient viewing angle expanding effect may not be obtained. Also,
If it is larger than 500 nm, there is a possibility that the liquid crystal display may be colored unnecessarily when viewed obliquely.

Next, the angle of the director will be described. The angle range of the director in the film thickness direction of the nematic hybrid oriented film is the acute angle formed by the director of the positive uniaxial liquid crystalline polymer at the film interface and the projected component of the director onto the film interface. However, on one of the upper surface and the lower surface of the film, the angle is usually 60 degrees or more and 90 degrees or less, and on the opposite surface of the film, it is usually 0 degrees or more and 50 degrees or less. More preferably, the absolute value of one angle is 80 degrees or more and 90 degrees or less, and the absolute value of the other angle is 0 degrees or more and 30 degrees or less.

Next, the average tilt angle will be described. In the present invention, an average value in the film thickness direction of an angle formed by a director of a positive uniaxial liquid crystalline polymer and a component projected by the director onto a substrate plane is defined as an average tilt angle.
The average tilt angle can be obtained by applying a crystal rotation method. The average tilt angle of the compensation film of the present invention is in the range of 10 degrees to 60 degrees, preferably 2 degrees.
It is in the range of 0 to 50 degrees. When the average tilt angle is smaller than 10 degrees or larger than 60 degrees, a certain viewing angle expanding effect is recognized but a satisfactory effect may not be obtained.

Next, the TN-LC
The arrangement when used for expanding the viewing angle of D will be specifically described. The position of the compensation film may be any position between the polarizing plate and the liquid crystal cell, and one or more compensation films can be arranged. In the present invention, it is practically preferable to perform viewing angle compensation using one or two compensation films. Even if three or more compensation films are used,
Although viewing angle compensation is possible, it is not very preferable because it leads to an increase in cost. An example of a specific arrangement position is as follows. However, these are merely typical arrangement positions, and the present invention is not limited to these.

First, the upper and lower surfaces of the present compensation film are defined as follows. The plane where the angle between the director of the liquid crystalline polymer having optically positive uniaxiality and the plane of the film forms an angle of 60 degrees or more and 90 degrees or less on the acute angle side is referred to as a b-plane. A plane in which the angle forms an angle of 0 ° or more and 50 ° or less on the acute angle side is referred to as a c-plane. Next, the tilt direction of the present compensation film is defined as follows. When viewing the c-plane from the b-plane of the compensation film through the liquid crystal layer, the direction in which the angle between the director and the projection component on the c-plane of the director is an acute angle and the direction parallel to the projection component is the tilt of the compensation film. Defined as direction. Next, the pretilt direction of the liquid crystal cell is defined as follows. Usually, at the liquid crystal cell interface, the driving low-molecular liquid crystal is not parallel to the cell interface but is inclined at an angle. This is called a pretilt angle. The direction in which the angle between the director of the liquid crystal at the cell interface and the projection component on the interface of the director is an acute angle, and the direction parallel to the projection component of the director is defined as the pretilt direction of the liquid crystal cell.

Based on the above definition, this compensation film
A case in which a TN-LCD is used will be described. The compensation film is disposed between the polarizing plate and the liquid crystal cell, and may be on the upper surface side or the lower surface side of the cell. It is preferable that the tilt direction of the compensation film and the pretilt direction of the liquid crystal of the cell at the interface of the liquid crystal cell not adjacent to each other substantially coincide. The angle between the tilt direction and the pretilt direction is preferably in the range of 0 to 15 degrees, more preferably in the range of 0 to 10 degrees, and particularly preferably in the range of 0 to 5 degrees. If the angle between them is 15 degrees or more, there is a possibility that a sufficient viewing angle compensation effect cannot be obtained. Next, a case where two compensating films are used for a TN-LCD will be described. The two compensation films are arranged on the upper or lower surface of a liquid crystal cell sandwiched between a pair of upper and lower polarizing plates. When arranging, two compensating films may be on the same side, or one each may be above and below. The two compensation films may be combined with the same parameter or may be different.

In the present invention, when two compensating films are arranged above and below a liquid crystal cell, it is preferable that each compensating film is arranged in the same manner as when only one compensating film is used. That is, it is preferable that the tilt direction of the liquid crystalline polymer in each compensation film and the pretilt direction of the cell liquid crystal at the interface of the liquid crystal cell not adjacent to each other substantially coincide. The angle between the tilt direction and the pretilt direction is preferably in the range of 0 to 15 degrees, more preferably in the range of 0 to 10 degrees, and particularly preferably in the range of 0 to 5 degrees. When two compensating films are arranged on either the upper surface or the lower surface of the liquid crystal cell, the compensating film on the side closer to the liquid crystal cell is arranged in the same manner as when one compensating film is used. That is, it is preferable that the tilt direction of the compensating film and the pretilt direction of the nematic liquid crystal at the liquid crystal cell interface not adjacent to each other are arranged so as to substantially coincide with each other. The angle between the tilt direction and the pretilt direction is preferably in the range of 0 to 15 degrees, more preferably in the range of 0 to 10 degrees, and particularly preferably in the range of 0 to 5 degrees. The second compensation film is to be arranged between the first compensation film and the polarizing plate,
It is preferable that the pre-tilt direction of the nematic liquid crystal at the liquid crystal cell interface adjacent to the first compensation film and the tilt direction of the second compensation film are substantially aligned.

Further, since the compensation film of the present invention has a nematic hybrid orientation, the upper and lower sides of the compensation film are not equivalent. Therefore, when the compensation film is mounted on a liquid crystal cell, a slight difference in the compensation effect is seen depending on which surface is closer to the liquid crystal cell. When the compensating film of the present invention is actually incorporated in a TN-LCD, the surface formed by the director of the liquid crystalline polymer with the film plane has a larger angle (the surface having an angle of 60 degrees or more and 90 degrees or less).
It is more desirable to dispose the liquid crystal near the liquid crystal cell and far from the polarizing plate. Finally, the arrangement of the polarizing plates will be described. Normally, in a TN-LCD, there are cases where the transmission axes of the upper and lower polarizers are arranged so as to be orthogonal to each other and where they are arranged so as to be parallel. Further, when the transmission axes of the upper and lower polarizers are perpendicular to each other, the transmission axis of the polarizer and the rubbing direction of the liquid crystal cell near the polarizer may be parallel or perpendicular, or may form an angle of 45 degrees. . When a polarizing plate is mounted on the compensating film of the present invention, the arrangement of the polarizing plate can obtain a viewing angle expanding effect in any of the above arrangements, but the transmission axes of the upper and lower polarizing plates are orthogonal to each other and the polarizing plate has An arrangement in which the transmission axis and the rubbing direction of the liquid crystal cell on the side closer to the polarizing plate are parallel is most preferable.

The compensation film is a TFT element or M
There is a great effect on the improvement of the viewing angle of a TN-LCD using an IM device, and the LCD of another mode, that is, STN (Su)
per Twisted Nematic) -LCD,
ECB (Electrically Control)
ed Birefringence)-LCD, OMI
(Optical Mode Interferenc
e) -LCD, OCB (Optically Comp)
enhanced Birefringence) -LC
D, HAN (Hybrid Aligned Nema)
tic) -LCD, IPS (In Plane Swi)
tching) -It is also effective for color compensation of a LCD or the like and improvement of viewing angle characteristics. In addition, since the raw materials of the liquid crystal compound are easily available, and the production of the liquid crystal compound as the raw material of the film and the production of the film itself are simple, the industrial use value thereof is very large.

[0135]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. In addition, each analysis method used in the Example is as follows. (1) Determination of Composition of Liquid Crystalline Polymer The polymer was dissolved in deuterated chloroform or deuterated trifluoroacetic acid, and measured and determined by 400 MHz 1H-NMR (JNM-GX400 manufactured by JEOL Ltd.). (2) Measurement of logarithmic viscosity The viscosity was measured at 30 ° C. in a phenol / tetrachloroethane (60/40 weight ratio) mixed solvent using an Ubbelohde viscometer. (3) Determination of liquid crystal phase series Determined by DSC (Perkin Elmer DSC-7) measurement and observation with an optical microscope (BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd.). (4) Measurement of Refractive Index The refractive index was measured with an Abbe refractometer (Type-4 manufactured by Atago Co., Ltd.). (5) Polarization analysis Ellipsometer DVA-36V manufactured by Mizojiri Optical Co., Ltd.
Performed using WLD. (6) Film thickness measurement SURFACE TEXTURE ANA manufactured by SLOAN
LYSIS SY-STEM Dektak 3030
ST was used. In addition, interference wave measurement (manufactured by JASCO Corporation)
An ultraviolet / visible / near-infrared spectrophotometer V-570) and a method of determining the film thickness from the data of the refractive index were also used.

Example 1 4-n-hexylbenzoic acid 10 mmol, terephthalic acid 95 mmol, hydroquinone diacetate 50 mmol
1, 50 mmol of 3-methylcatechol diacetate,
Polymerization was carried out at 270 ° C. for 12 hours in a nitrogen atmosphere using 100 mg of sodium acetate. Next, the obtained reaction product was dissolved in tetrachloroethane, and then reprecipitated with methanol for purification, thereby obtaining 22.0 g of a liquid crystalline polyester (formula (1)). This liquid crystalline polyester had a logarithmic viscosity of 0.15, a nematic phase as a liquid crystal phase, a transition temperature between isotropic phase and liquid crystal of 240 ° C., and a glass transition point of 75 ° C. Using this liquid crystalline polyester,
A 0 wt% phenol / tetrachloroethane mixed solvent (6/4 weight ratio) solution was prepared. This solution was applied to a soda glass plate by a bar coating method, dried, and dried.
After heat treatment at 90 ° C. for 30 minutes, it was cooled and fixed at room temperature. A uniformly oriented liquid crystalline film having a thickness of 15 μm was obtained. Conoscopic observation revealed that the polymer liquid crystal had a positive uniaxial structure, indicating that the polymer had homeotropic alignment.

Next, 8 of the liquid crystalline polyester of the formula (1)
A wt% tetrachloroethane solution was prepared, applied on a glass having a rubbing polyimide film by spin coating, dried, heat-treated at 190 ° C. for 20 minutes, air-cooled and fixed to obtain a film for an optical element. . The resulting film on the substrate was transparent, uniform without any alignment defects, and had a thickness of 1.55 μm. Using the optical measurement system shown in FIGS. 1 and 2, the film was tilted in the rubbing direction of the substrate, and the retardation value was measured. As a result, FIG.
As a result, there was obtained a result in which there was no angle at which the retardation value was 0, which was asymmetrical left and right. From this result, it was found that the director of the liquid crystalline polyester was inclined with respect to the substrate and was not in a uniform tilt orientation (the angle between the director and the substrate surface was not constant in the film thickness direction).

Next, the film on the substrate was cut into five pieces, each of which was immersed in a methanol solution containing 3 wt% of chloroform for a certain period of time, and eluted from the upper surface of the liquid crystal layer. When the immersion time was 15 seconds, 30 seconds, 1 minute, 2 minutes, and 5 minutes, the thickness of the liquid crystal layer remaining without being eluted was 1.3, respectively.
5 μm, 1.10 μm, 0.88 μm, 0.56 μm,
It was 0.37 μm. Using the optical system of FIGS. 1 and 2, θ
The retardation value (front retardation value) when = 0 ° was measured, and the relationship between the film thickness and the retardation value in FIG. 4 was obtained. As can be seen from FIG. 4, the film thickness and the retardation value do not have a linear relationship, and this also indicates that the film is not in a uniform tilt orientation. The dotted line in the figure is a straight line observed in a film having a uniform tilt orientation. Next, a high refractive index glass substrate having a rubbing polyimide film of the liquid crystalline polyester of the formula (1) (refractive index is 1.84)
Above, orientation and fixation were performed using the same method as described above to prepare a compensation film, and the refractive index was measured using this.
Place the glass substrate in contact with the prism surface of the refractometer,
When the compensation film is arranged so that the substrate interface side is lower than the air interface side, the refractive index in the film surface is anisotropic, and the refractive index in the plane perpendicular to the rubbing direction is 1.55; Was 1.70, and the refractive index in the film thickness direction was constant at 1.55 regardless of the direction of the sample. From this, it was found that on the glass substrate side, rod-like liquid crystal molecules constituting the liquid crystalline polyester were planarly oriented parallel to the substrate. Next, when the optical element film is arranged such that the air interface side of the optical element film is in contact with the prism surface of the refractometer, the in-plane refractive index has no anisotropy, the refractive index is constant at 1.55, The refractive index is 1.7 regardless of the direction of the sample.
It was constant at 0. From this, it was found that rod-like liquid crystal molecules constituting the liquid crystalline polyester were oriented perpendicular to the substrate plane on the air interface side. From the above, the optical element film formed of a positive uniaxial liquid crystalline polymer forms a nematic hybrid orientation,
It was found that the orientation was as shown in FIG. 5 by the regulating force of the substrate interface and the regulating force of the air interface by the rubbing.

Next, the following operation was performed in order to more accurately determine the azimuth of the director at the substrate interface.
Another glass substrate having a rubbing polyimide film was placed over and adhered to the optical element film formed on the high refractive glass substrate having the above rubbing polyimide film. That is, the compensation film was sandwiched between two rubbing polyimide films. At this time, the upper and lower rubbing films were arranged such that the rubbing directions were 180 degrees with respect to each other.
In this state, heat treatment was performed at 190 ° C. for 30 minutes. The sample thus obtained was subjected to refractive index measurement and ellipsometry. As a result of the refractive index measurement, the same value was obtained for the top and bottom of the optical element film, and the refractive index in the film surface was 1.55 in a plane perpendicular to the rubbing direction, and 1. in a plane parallel to the rubbing direction.
70 in the film thickness direction of the film. This indicates that the director is substantially parallel to the substrate plane both above and below the compensation film near the interface of the substrate. Furthermore, as a result of polarization analysis, the refractive index structure is almost positive uniaxial, and as a result of detailed analysis based on the crystal rotation method, the director has a slight inclination near the substrate interface, and the director plane and the director The angle formed was about 3 degrees. The direction in which the director was inclined coincided with the rubbing direction (the tilt direction and the rubbing direction of the optical element film coincided with each other). Based on the above, considering that the director orientation at the substrate interface is almost determined by the interaction between the liquid crystalline polymer and the alignment substrate interface, the nematic of the optical element film formed on a single alignment substrate described above is considered. It is estimated that the director orientation at the substrate interface in the hybrid orientation is 3 degrees.

[0140]

Embedded image

Example 2 A liquid crystalline polyester of the formula (2) was synthesized in the same manner as in Example 1. Logarithmic viscosity of the liquid crystalline polyester,
0.16, having nematic phase as liquid crystal phase, isotropic phase
The liquid crystal phase transition temperature was 220 ° C, and the glass transition point was 100 ° C. As a result of the same orientation test as in Example 1, it was found that this liquid crystalline polyester exhibited homeotropic orientation and was positive uniaxial. A 7 wt% chloroform solution of the polymer of the formula (2) was prepared. The solution was applied to glass having a rubbing polyimide film by spin coating, dried, heat-treated at 250 ° C. for 30 minutes, and then cooled and fixed. The compensation film on the substrate was transparent, uniform without any alignment defects, had a film thickness of 0.40 μm, and an average tilt angle in the film thickness direction of 45 °. The axial arrangement of each optical element was the arrangement shown in FIG. 6, and one liquid crystal optical film was disposed above and below the liquid crystal cell such that the air interface side of the compensation film was closer to the liquid crystal cell. The liquid crystal cell used was ZLI-4792 as a liquid crystal material, and cell parameters were a cell gap of 4.8 μm, a twist angle of 90 ° (left twist), and a pretilt angle of 4 °. 3 for liquid crystal cell
A voltage was applied with a 00 Hz rectangular wave. The contrast ratio from all directions was measured using the FFP optical system DVS-3000 manufactured by Hamamatsu Photonics KK, with the ratio of the transmittance of white display 0 V and black display 6 V (white display) / (black display) as the contrast ratio. , An isocontrast curve was drawn. FIG. 7 shows the result. In the arrangement shown in FIG. 6, a voltage that divides the difference between the transmittances of the white display and the black display into eight is applied to the liquid crystal cell, and the gradation characteristics in the horizontal direction (0-180 degrees) are obtained. The measurement was performed using a color luminance meter BM-5. FIG. 8 shows the results.

[0142]

Embedded image

Comparative Example 1 The same TN liquid crystal cell as in Example 2 was used, and the arrangement with respect to the polarizing plate liquid crystal cell in the state where the compensation film was not mounted was the same as in FIG. , And the measurement of the gradation characteristics in the horizontal direction (0 ° -180 ° direction). The results are shown in FIGS.

Example 3 Liquid crystalline polyesters of the formulas (3) and (4) were synthesized.
The logarithmic viscosity of the liquid crystalline polyester of the formula (3) is 0.12,
It had a nematic phase as a liquid crystal phase, an isotropic phase-liquid crystal phase transition temperature of 200 ° C., and a glass transition point of 90 ° C. As a result of the same orientation test as in Example 1, it was found that the liquid crystalline polyester of the formula (3) exhibited homeotropic orientation and was positive uniaxial. The logarithmic viscosity of the liquid crystalline polyester of the formula (4) was 0.15, the liquid crystal phase had a nematic phase, and the isotropic phase-liquid crystal phase transition temperature was 300 ° C. or more. A 10 wt% phenol / tetrachloroethane mixed solvent (6/4 weight ratio) solution of the liquid crystalline polyester was prepared, applied to various orientation test substrates by screen printing, dried, and then heat-treated at 230 ° C. for 10 minutes. Was done. Soda glass, borosilicate glass,
A polyethylene terephthalate film, a polyimide film, a polyetherimide film, a polyetheretherketone film, and a polyethersulfone film were used. A schlieren structure was observed on any of the substrates by microscopic observation of the liquid crystal phase. It turned out to be. A 5 wt% tetrachloroethane solution of the liquid crystalline polyester containing the liquid crystalline polyesters of the formulas (3) and (4) at a weight ratio of 20:80 was prepared. Coating, drying and heat treatment were performed under the same conditions as in Example 2 to obtain a compensation film. The thickness of the compensation film was 0.50 μm. The average tilt angle in the thickness direction of this film was 30 degrees. The contrast ratio was measured from all directions in the same manner as in Example 2. The result is shown in FIG.

[0145]

Embedded image

[0146]

Embedded image

Example 4 Liquid crystalline polyesters of the formulas (5) and (6) were synthesized.
The logarithmic viscosity of the liquid crystalline polyester of the formula (5) is 0.15,
It had a nematic phase as a liquid crystal phase, an isotropic phase-liquid crystal phase transition temperature of 220 ° C., and a glass transition point of 100 ° C. As a result of the same orientation test as in Example 1, it was found that the liquid crystalline polyester of the formula (5) exhibited homeotropic orientation and was positive uniaxial. The logarithmic viscosity of the liquid crystalline polyester of the formula (6) was 0.18, the liquid crystal phase had a nematic phase, and the isotropic phase-liquid crystal phase transition temperature was 200 ° C. As a result of the same orientation test as in Example 3, it was found that the liquid crystalline polyester of the formula (6) had homogeneous orientation. A 5 wt% solution of the liquid crystalline polyester containing the liquid crystalline polyesters of the formulas (5) and (6) in a weight ratio of 25:75 was prepared in tetrachloroethane.
Coating, drying and heat treatment were performed under the same conditions as in Example 2 to obtain a compensation film. The thickness of the compensation film was 0.48 μm. The average tilt angle in the thickness direction of this film is 28
Degree. The contrast ratio was measured from all directions by the same method as in Example 2, and the same result as in Example 3 was obtained.

[0148]

Embedded image

[0149]

Embedded image

Example 5 Liquid crystalline polyesters of the formulas (7) and (8) were synthesized.
The logarithmic viscosity of the liquid crystalline polyester of the formula (7) is 0.20,
The liquid crystal phase had a nematic phase and the isotropic-liquid crystal phase transition temperature was 220 ° C. The logarithmic viscosity of the liquid crystalline polyester of the formula (8) was 0.21, the liquid crystal phase had a nematic phase, and the isotropic phase-liquid crystal phase transition temperature was 190 ° C. As a result of the same orientation test as in Example 1, it was found that both the liquid crystalline polyesters of the formulas (7) and (8) exhibited homeotropic orientation and were optically positive uniaxial. A 4 wt% phenol / tetrachloroethane mixed solvent (6/4 weight ratio) solution containing the polymers of formulas (7) and (8) in a weight ratio of 90:10 was prepared. It was applied over a length of 10 m by a roll coating method on a rubbed polyethylene terephthalate film having a width of 40 cm and dried with hot air at 120 ° C.
Heat treatment was performed for 0 minutes to cool and fix. A triacetyl cellulose film having an adhesive was adhered to the surface of the obtained compensation film via the adhesive, then the polyethylene terephthalate film was peeled off, and the compensation film was transferred to the triacetyl cellulose film. The thickness of the compensation film was 0.60 μm, and the average tilt angle in the thickness direction was 35 degrees. The axial arrangement of each optical element was as shown in FIG. 6, and compensation films were arranged one above each other above and below the liquid crystal cell so that the triacetyl cellulose film of the liquid crystal optical film was on the side closer to the liquid crystal cell. The contrast ratio was measured in all directions by the same method as in Example 2. The result is shown in FIG.

[0151]

Embedded image

[0152]

Embedded image

Example 6 Liquid crystalline polyesters of the formulas (9) and (10) were synthesized. The logarithmic viscosity of the liquid crystalline polyester of the formula (9) is 0.1.
0, having a nematic phase as a liquid crystal phase and having an isotropic phase-liquid crystal phase transition temperature of 180 ° C. As a result of conducting an orientation test in the same manner as in Example 1, it was found that the liquid crystalline polyester of the formula (9) exhibited homeotropic orientation and was optically positive uniaxial. The logarithmic viscosity of the liquid crystalline polyester of the formula (10) was 0.18, the liquid crystal phase had a nematic phase, and the transition temperature between isotropic phase and liquid crystal phase was 300 ° C. or more.
As a result of performing the same orientation test as in Example 3, the result of the formula (10) was obtained.
Was found to have a homogeneous orientation. The polymer of the formulas (9) and (10) is
8 wt% N-methyl-containing at a weight ratio of 0:50
A 2-pyrrolidone solution was prepared. Rubbed width 4
It is applied over a length of 10 m on a 0 cm polyether ether ketone by a die coating method, dried with hot air at 120 ° C., heat-treated at 220 ° C. for 10 minutes, and cooled.
Immobilized. A triacetyl cellulose film having an adhesive was adhered to the surface of the obtained compensation film via the adhesive, then the polyetheretherketone film was peeled off, and the compensation film was transferred to the triacetyl cellulose film. Compensation film thickness is 0.62μ
m, the average tilt angle in the film thickness direction was 37 degrees. The axial arrangement of each optical element was the arrangement shown in FIG. 6, and compensation films were arranged one above each other above and below the liquid crystal cell such that the triacetyl cellulose film of the liquid crystal optical film was on the side closer to the liquid crystal cell. The contrast ratio was measured in all directions by the same method as in Example 2, and the same result as in Example 5 was obtained.

[0154]

Embedded image

[0155]

Embedded image

Example 7 A liquid crystalline polyester represented by the formula (11) was synthesized. The liquid crystalline polyester had a logarithmic viscosity of 0.25, a nematic phase as a liquid crystal phase, and an isotropic-liquid crystal phase transition temperature of 190 ° C. As a result of conducting an orientation test in the same manner as in Example 1, it was found that the liquid crystalline polyester exhibited homeotropic orientation and was optically positive uniaxial. A 15 wt% chloroform solution of the liquid crystalline polyester is applied to a 40 cm wide polyarylate film having a rubbing polyimide film over a length of 10 m by a die coating method, dried with hot air at 100 ° C., and heat treated at 200 ° C. for 5 minutes. Then, a compensation film was obtained. The thickness of the compensation film was 0.62 μm, and the average tilt angle in the thickness direction was 35 degrees. The polarizing plate of the liquid crystal color television XTL-610 manufactured by Sony was peeled off, and the compensating films were attached one by one to the top and bottom of the liquid crystal cell so that the air interface side of the compensating film was closer to the liquid crystal cell. Thereafter, a polarizing plate was attached to the polyarylate film one by one at the top and at the bottom. The axial arrangement of each optical element was the same as the arrangement shown in FIG. The contrast ratio in all directions was measured in the same manner as in Example 2. The result is shown in FIG.

[0157]

Embedded image

Comparative Example 2 A liquid crystal color television XTL-610 manufactured by Sony of Example 7
The contrast ratio was measured in all directions when no compensation film was attached. FIG. 14 shows the results.

Example 8 A liquid crystalline polyester represented by the formula (12) was synthesized. The liquid crystalline polyester had a logarithmic viscosity of 0.21, a nematic phase as a liquid crystal phase, and an isotropic phase-liquid crystal phase transition temperature of 180 ° C. As a result of conducting an orientation test in the same manner as in Example 1, it was found that the liquid crystalline polyester exhibited homeotropic orientation and was optically positive uniaxial. The liquid crystal property 10
wt% phenol / tetrachloroethane mixed solvent (6
/ 4 weight ratio) A solution was prepared and applied over a length of 10 m to a polyimide film having a width of 40 cm, which was rubbed by a roll coating method, and dried with hot air at 120 ° C.
Heat treatment was performed at 20 ° C. for 5 minutes to obtain a compensation film. Next, apply an ultraviolet curable adhesive on the surface of the compensation film,
A polyvinyl alcohol film was bonded via an adhesive. After irradiating ultraviolet rays to cure the adhesive, the polyimide film was peeled off and the compensation film was transferred to a polyvinyl alcohol film. The thickness of the compensation film was 0.58 μm, and the average tilt angle in the thickness direction was 35 degrees. The polarizing plate of Casio's liquid crystal color television VM-101 was peeled off, and the compensating films were bonded one by one on the upper and lower sides of the liquid crystal cell such that the air interface side of the compensating film was closer to the liquid crystal cell. Thereafter, a polarizing plate was attached to polyether sulfone one by one at the top and at the bottom. The axial arrangement of each optical element was the same as the arrangement shown in FIG. The contrast ratio in all directions was measured in the same manner as in Example 2. The result is shown in FIG.

[0160]

Embedded image

Comparative Example 3 Casio liquid crystal color television VM-101 of Example 7
The contrast ratio was measured in all directions when no compensation film was attached. FIG. 16 shows the results.

[Brief description of the drawings]

FIG. 1 is a layout diagram of an optical measurement system used for measuring a tilt angle of a compensation film of the present invention.

FIG. 2 shows the relationship between the axial orientation of a sample of an optical measurement system used for measuring the tilt angle of the compensation film of the present invention and the polarizing plate.

FIG. 3 shows a relationship between an apparent retardation value measured by tilting the substrate along the rubbing direction and a sample tilt angle in Example 1.

FIG. 4 shows the measurement results of the film thickness of the compensation film after immersion and the apparent retardation value in front of the sample in Example 1.

FIG. 5 is a conceptual diagram of an orientation structure of a compensation film of the present invention.

FIG. 6 shows the axial arrangement of each optical element in the second embodiment.

FIG. 7 shows an isocontrast curve of Example 2.

FIG. 8 shows a measurement result of a gradation characteristic in a horizontal direction in Example 2.

FIG. 9 shows an isocontrast curve of Comparative Example 1.

FIG. 10 shows the gradation characteristics in the horizontal direction of Comparative Example 1.

FIG. 11 shows an isocontrast curve of Example 3.

FIG. 12 shows an isocontrast curve of Example 5.

FIG. 13 shows an isocontrast curve of Example 7.

14 shows an isocontrast curve of Comparative Example 2. FIG.

FIG. 15 shows an isocontrast curve of Example 8.

FIG. 16 shows an isocontrast curve of Comparative Example 3.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yosuke Numao 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Nippon Oil & Oil Co., Ltd.

Claims (3)

[Claims] 1. A liquid crystalline polymer having a monofunctional structural unit at one or both ends of a polymer chain and substantially exhibiting optically positive uniaxiality. A film for an optical element, in which a nematic hybrid alignment formed by molecules in a liquid crystal state is fixed. 2. A liquid crystalline polymer having a monofunctional structural unit at one or both ends of a polymer chain and substantially formed of an optically positive uniaxial liquid crystalline polymer. A compensation film for a liquid crystal display device, wherein a nematic hybrid alignment formed by molecules in a liquid crystal state is fixed. 3. A twisted nematic liquid crystal display comprising a driving liquid crystal cell comprising a pair of transparent substrates provided with electrodes and a nematic liquid crystal, and at least an upper polarizing plate and a lower polarizing plate disposed above and below the substrate. An apparatus, wherein at least one of the compensation films for a liquid crystal display element according to claim 2 is provided between the substrate and one of the upper and lower polarizing plates or between the substrate and the upper and lower polarizing plates.
A twisted nematic liquid crystal display device characterized by incorporating one or more sheets.