JP3310403B2 - Oriented liquid crystal polymer film, method for producing the same, retardation plate and liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oriented liquid crystal polymer film, an oriented liquid crystal oligomer polymer film, a method for producing them, and an oriented liquid crystal oligomer polymer film useful as a member of a retardation film used for a liquid crystal display device or the like. TECHNICAL FIELD The present invention relates to a laminate comprising a substrate and a substrate, a composite retardation film comprising the laminate and a uniaxially oriented retardation film, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A retardation film is a polymer film having optical homogeneity and durability and having uniaxial orientation.
It is generally used as an optical compensator for improving the display quality of a liquid crystal display device. A super twisted nematic (hereinafter sometimes referred to as STN) type liquid crystal display device using a retardation film has advantages such as lightness, thinness, and inexpensiveness, but has poor viewing angle characteristics and inferior black and white levels. Had such disadvantages. Although these disadvantages have been considerably improved by a method such as laminating two retardation films, the viewing angle characteristics have not yet reached a satisfactory level, and the method of controlling the viewing angle in a specific direction has not been improved. No industrial method has been developed.

The viewing angle characteristics of a liquid crystal display element are greatly correlated not only with the angle dependence of the birefringence of the liquid crystal cell for display but also with the angle dependence of the retardation of the retardation film. It is known that the smaller the change in retardation angle, the better. For this purpose, it has been proposed to vertically align a liquid crystalline material and use a retardation film having a high refractive index in a direction normal to the film surface.

For example, Japanese Patent Application Laid-Open No. 2-256023 discloses that a film having an optical axis in the normal direction of a film surface and a retardation film having a positive birefringence value are used to change the angle of retardation. It is described that a retardation film having improved viewing angle characteristics can be obtained. As a film having an optical axis in the normal direction of the film, a photopolymerizable compound and a liquid crystal monomer are mixed, and while maintaining the orientation of the liquid crystal monomer in an electric field, the polymerization proceeds to fix the orientation in the normal direction. There is a way to do that.

[0005] Also, Japanese Patent Application Laid-Open No. 4-16916 discloses that
A birefringent layer having a refractive index in the thickness direction larger than the in-plane refractive index is disclosed, and the birefringent layer is composed of a vertically aligned polymer liquid crystal. As for the method of vertically aligning the polymer liquid crystal, heating to the liquid crystal temperature and then applying an electric or magnetic field in the thickness direction, and sandwiching between two substrates whose surfaces have been treated with a vertical alignment agent such as a silane compound ,
A method of vertically aligning at a liquid crystal temperature is disclosed, and it is shown that a retardation film having excellent viewing angle characteristics can be obtained by combining with a retardation film obtained by stretching a polymer. Next, Society for Information Di
splay International Symposium Digest of Technical
Papers (1993) p. 277 describes the viewing angle characteristics of a TN liquid crystal display device by using two optical anisotropic bodies whose optical axes are inclined from the film normal direction and an optical anisotropic body having an optical axis in the film plane. Is reported to be able to be improved in principle.

Many attempts have been made to obtain the alignment of liquid crystal molecules because the alignment of the liquid crystal molecules in the display cell greatly affects the display quality. In general, a method of controlling the orientation by controlling the orientation is described. As an alignment film, for example, a polymer film such as polyimide is provided on a substrate in order to obtain horizontal alignment, and the surface is rubbed with a cloth or the like, and then a low-molecular liquid crystal is aligned.
_2, SiO, MgO, inorganic materials such as MgF ₂ and oblique deposition method using a horizontal alignment film, and a method of using a stretched polymer film is known (LCD Fundamentals and Applications, 97
-100 pages, Industrial Research Council, 1991). Also, a method for obtaining a tilt alignment of a low-molecular liquid crystal is known, and an organic alignment film such as polyimide, SiO ₂ , SiO, Mg
Oblique deposition of inorganic substances such as O and MgF ₂ is known.
These alignment films make the alignment of liquid crystal molecules in the liquid crystal display element uniform and provide a pretilt, thereby realizing good display image quality.

[0007]

However, the optical axis of a polymer laminated film in which a side chain type liquid crystal polymer or liquid crystal oligomer and an alignment-treated substrate are laminated is inclined with respect to the normal direction, and the Which were oriented in any direction of the above was not known. As for the method of aligning the liquid crystal polymer, in the vertical alignment, the liquid crystal polymer film oriented by a method of performing photopolymerization while maintaining the alignment of the liquid crystal monomer having large relaxation in the external field such as an electric field, a magnetic field, and a shearing force. Although it is known that it can be obtained, the alignment method is complicated for a high molecular weight liquid crystal, and it is difficult to fix the alignment for a low molecular weight liquid crystal. Furthermore, as for the method for producing a liquid crystal polymer or a liquid crystal oligomer film in which the optical axis is inclined from the substrate surface, it is only known that the film is oriented by sandwiching a glass plate with a transparent electrode by applying an electric field (40th Spring 1993). Japanese Society of Applied Physics Lecture No. 29aZK-11)
There has been a problem that an industrially advantageous production method has not been established. The present invention provides a liquid crystal polymer film or a liquid crystal oligomer polymer film that provides a wide viewing angle composite retardation film and an industrial production method thereof, a wide viewing angle composite retardation film laminated with the retardation film, and And a liquid crystal display device having excellent viewing angle characteristics using the same.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a liquid crystal polymer or a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase. Was found to be able to fix the orientation by orienting the substrate on the substrate subjected to the orientation treatment at an angle to the normal direction of the substrate, and in the case of liquid crystal oligomer, by crosslinking. An oriented liquid crystal polymer film having an optical axis inclined with respect to the normal direction of the surface, and an oriented liquid crystal oligomer polymer film can be obtained, and the oriented liquid crystal polymer film, the oriented liquid crystal oligomer polymer film and the uniaxial orientation can be obtained. It was found that a liquid crystal display device with excellent black-and-white level and good viewing angle characteristics could be obtained by combining with a retardation film The has been completed.

That is, the present invention comprises the following inventions. (1) A film made of a side chain type liquid crystal polymer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, wherein the liquid crystal polymer is a linear or cyclic liquid crystal composed of the following repeating unit (I) A liquid crystal polymer, wherein the number of repeating units is 4 to 10,000 on average per molecule, and the optical axis of the film is inclined from the film surface in an angle of 10 ° to 80 ° as an elevation angle. Liquid crystal polymer film.

Embedded image (In the formula, A is a group represented by the following formula (II) or (III); in formula (II), -Si-O- is a main chain of formula (I); C—CH ₂ — has the formula (I)
And the COO group is located on a side chain other than R ₁ of the side chain. In the formula (I), when A is the formula (II), R ₁ is hydrogen, an alkyl group having 1 to 6 carbon atoms or a phenyl group. In the formula (I), when A is the formula (III), R ₁ is hydrogen or an alkyl group having 1 to 6 carbon atoms.

Embedded image

Embedded image k is an integer of 2 to 10, m is 0 or 1, p
Is 0 or 1, and Ar ₁ or Ar ₂ is independently 1,
4-phenylene group, a 1,4-cyclohexane group, pyridine-2,5-diyl group or pyrimidine-2,5-diyl group, L is _{-CH 2 -O-, -O-CH 2} -, -COO -, -OCO-
, -CH ₂ -CH _2- , -CH = N-, -N = CH- or

Embedded image Wherein R is hydrogen, halogen, cyano, alkyl having 1 to 10 carbons or 1 to 1 carbon
It is an alkoxy group of 0. )

(2) A film comprising a polymer of a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, wherein the liquid crystal oligomer comprises the repeating unit (I) described in (1) and the following A linear or cyclic liquid crystal oligomer composed of the repeating unit (IV), wherein n and n ′ are respectively represented by n and n ′, where the number of the repeating units (I) and (IV) in one molecule of the oligomer is n and n ′, respectively. Is independently an integer of 1 to 20, 4 ≦ n + n ′ ≦ 21, and the terminal group of the repeating unit (IV) is polymerized, and the optical axis of the film is 10 ° or more and 80 ° as an elevation angle from the film surface. An oriented liquid crystal oligomer polymer film characterized by being inclined in the following range.

Embedded image Wherein A is the same as described in the repeating unit (I), k ′ is an integer of 2 to 10, m ′ is 0 or 1, p ′ is 0 or 1, and Ar ₃ and Ar ₄ is independently a 1,4-phenylene group, a 1,4-cyclohexane group, a pyridine-2,5-diyl group, a pyrimidine-2,5,
- diyl group, L 'is _{-CH 2 -O-, -O-CH 2} -, -COO-
_{, -OCO-, -CH 2 -CH 2 -} , -CH = N -, - N = CH- or

Embedded image Wherein R ′ is hydrogen or carbon number 1
To 5 alkyl groups. )

(3) After forming a linear or cyclic liquid crystal polymer comprising the repeating unit (I) of the above (1) on a substrate which has been subjected to an alignment treatment, the liquid crystal polymer is formed into a film by performing a heat treatment. (1) The method for producing an oriented liquid crystal polymer film according to (1), wherein the film is oriented at an elevation angle of 10 ° or more and 80 ° or less from the surface. (4) The repeating units (I) and (IV) according to the above (2)
After forming a linear or cyclic liquid crystal oligomer consisting of on a substrate that has been subjected to an alignment treatment, a heat treatment is performed to align the optical axis from the film surface to an angle of elevation of 10 ° or more and 80 ° or less, and then the repeating unit (IV) The method for producing an oriented liquid crystal oligomer polymer film according to (2), wherein the terminal group is polymerized.

(5) The method for producing an oriented liquid crystal polymer film according to (3), wherein the alignment treatment of the substrate is oblique vapor deposition of an inorganic substance. (6) The method for producing an oriented liquid crystal oligomer polymer film according to (4), wherein the alignment treatment of the substrate is oblique deposition of an inorganic substance.

(7) A laminate of the oriented liquid crystal polymer film and the substrate, wherein the oriented liquid crystal polymer film according to the above (1) and a transparent or translucent, oriented substrate are laminated. . (8) A laminate of an oriented liquid crystal oligomer polymer film and a substrate, wherein the oriented liquid crystal oligomer polymer film according to (2) and a transparent or translucent, alignment-treated substrate are laminated.

(9) The base material is a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy. (7) A laminate of the oriented liquid crystal polymer film and the substrate. (10) The substrate is a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy (8).
A laminate of the oriented liquid crystal oligomer polymer film and a substrate. (11) a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy; and an oriented liquid crystal polymer film according to (7). A composite retardation plate obtained by laminating a laminate of a material and a laminate of the oriented liquid crystal oligomer polymer film according to (8) and a substrate.

(12) sandwiched between substrates having electrodes;
It has a positive dielectric anisotropy, and between a liquid crystal cell composed of a liquid crystal layer in which a helical axis is twisted in a direction substantially horizontal and a direction perpendicular to the substrate when no voltage is applied, and a polarizing film disposed outside the liquid crystal cell. , The oriented liquid crystal polymer film according to (1), the oriented liquid crystal oligomer polymer film according to (2), or the oriented liquid crystal polymer film or oriented liquid crystal oligomer polymer film according to (7) or (8), and a substrate A liquid crystal display device comprising at least one selected from a laminate and a composite retardation plate according to (11).

Hereinafter, the present invention will be described in detail. The liquid crystal polymer comprising the repeating unit (I) or the liquid crystal oligomer comprising the repeating units (I) and (IV) used in the present invention is:
A side chain type liquid crystal polymer or side chain type liquid crystal oligomer having a positive refractive index anisotropy in a liquid crystal state and having a nematic phase or a smectic phase. The side chain type liquid crystal polymer or the side chain type liquid crystal oligomer has a skeleton chain of poly-1-substituted acrylate, polysiloxane, etc., and a linear or cyclic one can be used. A cyclic structure is preferred from the viewpoint of stability.
In the poly-1-substituted acrylate, polymethacrylate or polyacrylate is preferable,
More preferred are polymethacrylates. Among these, a polysiloxane-based side chain type liquid crystal polymer or side chain type liquid crystal oligomer is preferable. As a group imparting liquid crystallinity (hereinafter sometimes referred to as a mesogen group), a group bonded to a main chain via a bent chain (hereinafter sometimes referred to as a spacer) can be generally used.

The side chain type liquid crystal polymer or side chain type liquid crystal oligomer needs to be in a liquid crystal state at a use temperature, that is, from room temperature to about 60 ° C. A transition temperature from a liquid crystal phase to an isotropic phase (hereinafter, sometimes referred to as a liquid crystal phase / isotropic phase transition temperature) becomes 200 ° C. or less due to drying and orientation treatment during lamination with a substrate. Thus, it is preferable to select the length of the spacer, the type of the mesogen group, and the degree of polymerization so that the temperature is preferably 170 ° C. or lower, more preferably 150 ° C. or lower.

The side chain type liquid crystal polymer or oligomer used in the present invention needs to be oriented in order to have anisotropy of the refractive index. Number is important. If the number of repeating units is large, the viscosity is high, and the liquid crystal transition temperature is high.
A high temperature or a long time is required for orientation, and a small number of repeating units is not preferable because the orientation is relaxed at room temperature.
The degree of polymerization of the liquid crystal polymer composed of the repeating unit (I) is 4
Not less than 10,000 and preferably not less than 4 and not more than 1,0.
00 or less, more preferably 4 or more and 21 or less. Further, in the case of the liquid crystal oligomer composed of the repeating units (I) and (IV), the numbers n and n ′ of the repeating units are each independently an integer from 1 to 20, and the sum of n and n ′ is from 4 to 21. Is chosen as From the viewpoint of the orientation of the liquid crystal oligomer and the fixation of the orientation after the polymerization, the ratio of n to n ′ is 1: 5.
To 5: 1, more preferably 1: 3 to 3: 1. Control of the ratio of n and n 'can be performed when synthesizing these liquid crystal oligomers as described later.

The side chain type liquid crystal polymer or the side chain type liquid crystal oligomer can also be formed by a spacer connecting the main chain and a mesogen group.
The liquid crystal transition temperature and the orientation are affected. As a short spacer, the orientation of the mesogen group is not good, and a long spacer tends to relax after the orientation of the mesogen group. Therefore, the spacer is preferably an alkylene group or an alkyleneoxy group having 2 to 10 carbon atoms. Particularly, an alkylene group or an alkyleneoxy group having 2 to 6 carbon atoms is preferable from the viewpoint of high orientation. In addition, an alkyleneoxy group is more preferable because of ease of synthesis. Specifically, preferred groups are-(CH ₂ ) ₂ -,-(CH ₂ ) ₃ -,-(CH ₂ ) ₄ -,-(CH
₂ ) ₅ -,-(CH ₂ ) ₆ -,-(CH ₂ ) ₃ -O-,-(CH ₂ ) ₄ -O-,-(CH ₂ ) ₅ -O
-,-(CH ₂ ) ₆ -O- and the like.

In the oriented liquid crystal polymer film or liquid crystal oligomer polymer film of the present invention, it is industrially advantageous that the refractive index anisotropy is large. For this purpose, the mesogen group is preferably a group having a large refractive index anisotropy. In the structure providing such a mesogen group, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ in the repeating unit (I) or (IV) each independently represent a 1,4-phenylene group, 1,4- Examples thereof include a cyclohexane group, a pyridine-2,5-diyl group and a pyrimidine-2,5-diyl group. Ar ₁ and Ar ₂ or Ar ₃
And the divalent group L connecting Ar ₄ is -CH ₂ -O-, -O-CH _2- , -C
_{OO-, -OCO-, -CH 2 -CH 2} -, -CH = N -, - N = CH- or

[0021]

Embedded image Or a group in which Ar ₁ and Ar ₂ are directly bonded, or
And a group in which Ar ₃ and Ar ₄ are directly bonded. More preferably, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently 1,
4-phenylene group, pyridine-2,5-diyl group, pyrimidine
-2,5-diyl group, and more preferably 1,4-phenylene group. The linking groups L and L ′ are each independently —CH ₂
-CH _2- , -COO- and -OCO- groups are preferred, and more preferred.
-COO- group.

The R group in the repeating unit (I) affects the dielectric anisotropy and orientation of the mesogenic group, and therefore, from the viewpoint of obtaining a liquid crystal polymer or oligomer film having a high refractive index anisotropy, A cyano group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms is selected. Preferably, it is a cyano group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and more preferably a cyano group or an alkoxy group having 1 to 10 carbon atoms.

The terminal group in the repeating unit (IV) is a group for fixing the orientation of the liquid crystal oligomer by polymerization. The polymer group is —OCO—C (R ′)） CH ₂ (R ′ represents hydrogen or an alkyl group having 1 to 5 carbon atoms), and examples thereof include an acrylate group and a methacrylate group. The method for polymerizing these groups is not particularly limited, and examples include photopolymerization and thermal polymerization using a radical initiator, and photopolymerization is preferred from the viewpoint of simplicity of operation and efficiency of fixing the orientation. Known photopolymerization initiators can be used.

The non-polymerizable mesogenic group used for the linear or cyclic liquid crystal polymer or oligomer having the repeating unit represented by the repeating unit (I) is exemplified below.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

Among these mesogen groups, those having a cyano group or an alkoxy group have a number of 1 to 18, 31 to 48, and 61.
To 78, 181 to 198, 211 to 228 are preferred, and the numbers 31 to 42 are more preferred. These mesogenic groups are preferably bonded to a polysiloxane-based main chain because they exhibit high orientation, and more preferably those bonded to a cyclic siloxane.

Further, examples of the polymerizable mesogen group used for a linear or cyclic liquid crystal oligomer having a repeating unit (IV) are shown below.

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

Among these polymerizable mesogen groups, 241 to 246, 253 to 2
58, 265-270, 313-318, 325-33
The group of 0 is preferred, and more preferably the numbers 253 to 258
It is a group of. These mesogenic groups are preferably bonded to a linear or cyclic polysiloxane-based main chain because they exhibit good properties, and more preferably those bonded to a cyclic polysiloxane.

Methods for synthesizing these liquid crystal polymers or oligomers are disclosed in JP-B-63-47759 and JP-A-Hei.
-16916 can be adopted. Examples thereof include a method of adding a mesogen group of the side chain to a polysiloxane chain and a method of polymerizing an acrylate or methacrylate having a mesogen via a flexible spacer group. When a mesogen group is added to the polysiloxane chain, the mesogen group has the same structure as the side chain mesogen group of the repeating unit (I) or (IV), and has an unsaturated double bond at the terminal where an alkyleneoxy group serving as a spacer is formed. It can be obtained by reacting a reaction material having a ω-alkenyloxy group having a bond with polysiloxane under a platinum catalyst.

In the case of a liquid crystal oligomer composed of the repeating units (I) and (IV), two kinds of mesogen groups are combined at the reaction material charging ratio corresponding to the non-polymerizable mesogen group and the polymerizable mesogen group during the reaction. The ratio can be controlled. Similarly, in the case where the main chain is an acrylate ester type or an α-alkyl-acrylate ester type, two kinds of monomers having a corresponding mesogen group are copolymerized by controlling the charge ratio of monomers when copolymerizing the mesogen group. The ratio of non-polymerizable mesogenic groups can be controlled. As the thus obtained liquid crystal polymer or oligomer, those exhibiting a nematic phase or a smectic phase are preferably used.

The transition temperature between the crystal phase or glass phase of these liquid crystal polymer or liquid crystal oligomer and the liquid crystal phase is not particularly limited, and a transition temperature below room temperature can be used.

As a method for producing a liquid crystal polymer film or a liquid crystal oligomer polymer film having an optical axis inclined with respect to the film surface according to the present invention, a liquid crystal polymer or oligomer film may be formed on an alignment-treated substrate. And performing a heat treatment. The heat treatment is performed at a transition temperature from a crystal phase or a glass phase to a liquid crystal phase (hereinafter referred to as Tg
It may be written. The above is carried out at a transition temperature from the liquid crystal phase to the isotropic phase (hereinafter, sometimes referred to as Ti). The heat treatment temperature (hereinafter sometimes referred to as Tt) preferably satisfies (Tg + 30 ° C.) ≦ Tt <Ti, and more preferably heat treatment in the range of (Tg + 40 ° C.) ≦ Tt <Ti. The heat treatment time is not particularly limited, but if it is too short, the vertical orientation is not sufficient, and if it is too long, it is not industrially preferable. Therefore, the heat treatment time is preferably from 0.2 minutes to 20 hours, more preferably from 1 minute to 1 hour. .
By the above heat treatment, the mesogenic group of the liquid crystal polymer or oligomer is oriented in a direction inclined with respect to the film surface, and has an optical axis inclined with respect to the film surface.

The method for preparing the liquid crystal polymer film or the liquid crystal oligomer polymer film is not limited, and examples thereof include a method of applying the liquid crystal polymer or the liquid crystal oligomer in a solution state and a method of applying the liquid crystal polymer or the liquid crystal oligomer in an isotropic state. Is a method of applying from a solution state. As a coating method, a usual roll coating method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a printing method,
The dipping method is exemplified. The obtained liquid crystal polymer film or liquid crystal oligomer polymer film can be used as it is, but it is preferable to use it by laminating it on a substrate.

The thickness of the liquid crystal polymer film or the liquid crystal oligomer polymer film is preferably from 0.1 to 20 μm, more preferably from 0.5 to 10 μm, and still more preferably from 1 to 7 μm. When the thickness is less than 0.1 μm, the expression of optical characteristics becomes small.

The liquid crystal oligomer polymer film is subjected to an alignment treatment so as to have an optical axis inclined with respect to the film surface, and then the liquid crystal oligomer is polymerized. The polymerization method is not limited, but it is necessary to carry out the polymerization while maintaining the orientation, photopolymerization, radiation polymerization such as γ-ray,
Thermal polymerization is exemplified. In photopolymerization or thermal polymerization, a known polymerization initiator can be used. Among these polymerization methods, photopolymerization and thermal polymerization are preferred from the simplicity of the process, and further,
Photopolymerization is more preferred from the viewpoint of maintaining good orientation.

The alignment treatment of the substrate used in the present invention depends on the phase structure of the liquid crystal used. For example, in a liquid crystal material showing nematic or smectic A, a method of using an obliquely vapor-deposited film of an inorganic material on a base material, or a surfactant such as lecithin or a silane coupling agent after forming the obliquely-deposited film of these inorganic materials. A method of performing a surface treatment with a known vertical alignment agent such as a titanium coupling agent is exemplified. When performing oblique vapor deposition of an inorganic substance, it is preferable that the inorganic substance is incident from a shallow angle with respect to the substrate from the viewpoint of obtaining a uniform oblique orientation, and specifically, an elevation angle of 45 ° or less from the substrate surface is preferable. Preferably, it is more preferably within 30 °. Since the tilting direction of the optical axis of the liquid crystal polymer or oligomer film obtained using these obliquely deposited films coincides with the deposition direction, by setting the deposition direction, the optical axis can be adjusted in any direction within the film plane. Axis can be set. However, the inclination angle of the optical axis and the deposition angle generally do not coincide with each other, and differ depending on the alignment agent and the liquid crystal material used.

The inorganic substance used in the vapor deposition of the present invention is vapor-deposited.
Sometimes it is preferable to grow columnar, SiO, SiO_Two,
SiO_X, MgO, MgO_X, MgF_Two, Pt, Zn
O, MoO_Three, WO_Three, Ta_TwoO_Five, SnO_Two, CeO
_Two, LiNbO_Three, LiTaO _Three, ZrO_Two, Bi_TwoO
_Three, TiZrO_Four, HfO_TwoFor example (1 <x <
2) Among them, SiO, SiO_Two, SiO_X, Mg
O, MgO_X, MgF_Two, Pt, and ZnO are preferably used.
And more preferably SiO, SiO_Two, SiO_XUse
Can be.

There is no particular limitation on the oblique deposition method.
A vapor deposition method by resistance heating, a vapor deposition method by electron beam heating, and a sputtering method are exemplified, and a vapor deposition method by electron beam heating and a sputtering method are preferable for depositing a high melting point inorganic substance. The degree of vacuum at the time of vapor deposition is not particularly limited, but the upper limit of the pressure is determined from the viewpoint of uniformity of the deposited film, and the lower limit of the pressure is determined from the viewpoint of productivity. Specifically, 1 × 10 ⁻³ to 1 ×
10 ^-7 Torr is exemplified, and preferably 5 × 10 ^{-4 to} 5
× 10 ⁻⁶ Torr. Although there is no particular limitation on the deposition rate of the inorganic substance, the deposition rate is 0.01 to 10 nm / sec from the viewpoint that the productivity is deteriorated when the deposition rate is low, and the uniformity of the deposited film is deteriorated when the deposition rate is high. Preferably, it is more preferably 0.1 to 5 nm / sec. Regarding the thickness of the deposited inorganic substance, the orientation is poor when the thickness is small, and 0.01 μm to 1 from the viewpoint that the productivity is poor when the thickness is large.
000 μm, preferably 0.05-100 μm
m, more preferably 0.1 to 5 μm.

When the liquid crystal material shows smectic C, a liquid crystal material is formed on a substrate which has been subjected to a vertical alignment treatment,
By performing the alignment treatment, a liquid crystal polymer or oligomer polymer film having an optical axis of 10 ° or more and 80 ° or less can be obtained. In this case, in order to align the inclination direction of the mesogen group, an oblique deposition method is used. Rubbing treatment, a magnetic field and an electric field can also be used. As the vertical alignment treatment, it is general to make the substrate surface hydrophobic with a surfactant such as lecithin, a silane coupling agent, a titanium coupling agent, or the like. In addition, good vertical alignment may be obtained by making the obliquely deposited substrate hydrophilic.

Examples of a method for making the surface of the obliquely deposited film hydrophilic include a method of applying a hydrophilic polymer containing a hydroxyl group, a carboxylate ion group or a sulfonate ion group, a plasma treatment in an oxygen or water vapor atmosphere, Known surface modification techniques such as corona discharge treatment and ozone treatment with ultraviolet light can be used.

Among the hydrophilic polymers, examples of the polymer having a hydroxyl group include polyvinyl alcohol, polyethylene vinyl alcohol copolymer, and polymers selected from natural polysaccharides such as pullulan and dextrin obtained by microbial fermentation from starch syrup. Is exemplified. Polyvinyl alcohol is preferred from the viewpoint of solubility and ease of providing vertical alignment. Examples of the polymer having a carboxylate ion include polyacrylic acid, sodium polyacrylate, polymethacrylic acid, polysodium alginate, polycarboxymethylcellulose soda salt, and the like. Acids are preferred. As a polymer containing a sulfonic acid ion, polystyrene sulfonic acid is exemplified. Among these hydrophilic polymers, polyvinyl alcohol, polysodium alginate, polycarboxymethylcellulose soda salt, polyacrylic acid, pullulan, and polystyrenesulfonic acid are preferable, and polyvinyl alcohol and sodium polyalginate are more preferable.

The thickness of these hydrophilic polymer films is not particularly limited, but is 1 nm or more and 10 μm or less, preferably 5 nm or more and 2 μm or less, more preferably 5 nm or more and 1 μm or less.
μm or less. The solvent used is not particularly limited as long as it dissolves the hydrophilic polymer, but water is preferably used.

As a base material used in a laminate of an oriented liquid crystal polymer film or a liquid crystal oligomer polymer film and a substrate which has been subjected to an alignment treatment according to another embodiment of the present invention, a glass plate, a transparent or semi-transparent A transparent polymer film can be used, and the above-described orientation treatment is performed. The shape of the substrate used is a thin plate or a film when used for a liquid crystal display device, and a film is preferable for a polymer material.

The transparent or translucent polymer film used as the substrate of the present invention includes polycarbonate, polysulfone, polyarylate, polyether sulfone,
Examples of cellulose acetate, cellulose acetate, polystyrene, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, and the like,
Preferred are polycarbonate, polysulfone, cellulose triacetate, polyethylene terephthalate, and polystyrene.

The thickness of the transparent or translucent polymer film used is not particularly limited, but is preferably 1 μm or more and 500 μm or less, more preferably 10 μm or more and 300 μm or less, and still more preferably 40 μm or more and 200 μm or less.

When a liquid crystal oligomer is formed on the alignment-treated substrate, the method for forming the film is not particularly limited.
For example, a film can be formed in the same manner as a liquid crystal oligomer film, and after dissolving the liquid crystal oligomer in a solvent that dissolves or swells the substrate or hydrophilic polymer little, a roll coating method, a gravure coating method, a bar coating method, a spin coating method, and a spraying method are used. A coating method such as a coating method, a printing method, and a dipping method, or a method in which a liquid crystal oligomer is heated to a temperature higher than a solid phase / liquid crystal phase transition temperature to reduce the viscosity of the liquid crystal oligomer, and then a roll coating method, a gravure coating method, and a bar coating method are used. A method of applying by a known method such as a spray coating method and a dipping method is exemplified.

Among these coating methods, from the viewpoint of easy production, a film can be formed from a liquid crystal oligomer solution by a roll coating method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a dipping method, or the like. preferable.

The thickness of the obtained liquid crystal polymer or oligomer polymer layer is preferably from 0.1 μm to 20 μm, more preferably from 0.5 μm to 10 μm, and still more preferably from 1 μm to 7 μm. When the thickness is less than 0.1 μm, the expression of optical characteristics becomes small, and when the thickness is more than 20 μm, it is not preferable because the orientation is difficult.

As described above, in order to obtain the degree of tilt alignment of the liquid crystal polymer or the liquid crystal oligomer, the liquid crystal oligomer / liquid crystal oligomer /
The polymer laminated film is heat-treated in the same manner as in the case of the above-mentioned liquid crystal oligomer polymer film, both in temperature and in processing time. However, in the substrate to which the glass transition temperature of the substrate to be used or the additive is added, since there is a problem in the production method such as the deformation of the substrate or the hydrophilic polymer occurs at the flow temperature of the substrate or higher,
The upper limit temperature is preferably equal to or lower than the glass transition temperature or the flow temperature of the substrate. By this treatment, the liquid crystal oligomer film on the polymer base material is tilted. There are no particular restrictions on the rate of temperature rise and cooling in the heat treatment.

Even when a glass plate or a hydrophilic polymer film is used as the substrate, a laminate of the liquid crystal oligomer polymer and the substrate can be obtained in the same manner.

The method for producing the transparent or translucent polymer film of the present invention includes a solvent casting method, an extrusion molding method,
A molding method such as a press molding method may be used.

Since the optical axis of the oriented liquid crystal oligomer polymer film or the laminate of the liquid crystal oligomer polymer film of the present invention and the oriented substrate is inclined at an elevation angle of 10 ° or more and 80 ° or less on the film surface. , Having an optical axis in the film plane, and having a positive refractive index anisotropy, by simultaneously using a uniaxially oriented retardation film made of a thermoplastic polymer, a composite retardation plate or a composite retardation film can do. Hereinafter, the composite retardation film or the composite retardation film is generically referred to as a composite retardation film.

The thermoplastic polymer having a positive refractive index anisotropy used in the composite retardation plate of the present invention includes polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose acetate, cellulose acetate, polyvinyl alcohol, and the like. Examples include polyethylene vinyl alcohol copolymer and polyethylene terephthalate. The thermoplastic polymer is uniaxially oriented and used as a retardation film. The laminate of the liquid crystal polymer or the liquid crystal oligomer / substrate and the uniaxially oriented retardation film may be laminated by bonding with an adhesive or the like, or may be used separately.

As a method for producing a film (hereinafter, sometimes referred to as a raw film) used as a raw material of a retardation film composed of these thermoplastic polymers, there are a solvent casting method, an extrusion molding method, a press molding method and the like. A molding method may be used. Examples of a stretching method for converting the raw film into a uniaxially oriented retardation film having an optical axis in the film plane include a tenter stretching method, a roll-to-roll stretching method, and a roll-to-roll compression stretching method. In order to obtain a uniform retardation film, it is preferable to stretch a film formed by a solvent casting method by a tenter stretching method.

The liquid crystal display device of the present invention includes an oriented liquid crystal polymer or liquid crystal oligomer polymer film, a laminate of a liquid crystal polymer or liquid crystal oligomer polymer film and a substrate, a liquid crystal polymer or liquid crystal oligomer polymer film. There is no particular limitation on the position where the laminated composite retardation plate is placed, and it may be anywhere between the two polarizing plates of the liquid crystal display. For example, between a polarizing plate and a display liquid crystal cell, between a polarizing plate and a protective film for a polarizing plate, between a retardation film and a polarizing plate, between a retardation film and a display liquid crystal cell, and between a retardation film and a protective film for a retardation film. And the like.

[0062]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The glass transition point and the transition temperature between the liquid crystal phase and the isotropic phase of the obtained liquid crystal oligomer were evaluated by observation with a polarizing microscope and a differential scanning calorimeter (DSC). The liquid crystal oligomer was scanned at a scanning rate of 10 ° C./min, and the transition temperature was evaluated from the second and subsequent data.
For Tg, the peak of the first derivative of the endothermic curve at the time of temperature rise was regarded as Tg, and for Ti, the endothermic peak considered to be due to the liquid crystal phase / isotropic phase transition was regarded as Ti.

It was confirmed that the obtained liquid crystal polymer or liquid crystal oligomer polymer film / substrate laminate had an optical axis inclined with respect to the film normal by obliquely tilting the laminated film under crossed Nicols. This can be done by observing changes in Referring to FIG. 1, when the incident direction of the inorganic substance is c, there is a position where the amount of transmitted light is minimized under crossed Nicols when the laminated film is rotated with b as the tilt axis. Since the transmitted light amount does not change so much when the substrate is rotated in this manner, it can be confirmed that the inclined orientation with respect to the substrate is realized in the plane including a and c.

To evaluate the laminated composite retardation film or film of the present invention, first the in-plane birefringence is evaluated. In a polarizing microscope equipped with a tilt stage, the laminated film is placed horizontally, and a retardation (hereinafter abbreviated as R (0)) is determined by a method of measuring birefringence of Senarumon using a Senarumon compensator. Next, the evaluation of the birefringence in the thickness direction was performed by using the optical axis direction in the horizontal plane as the tilt axis,
The retardation (hereinafter referred to as R
(Abbreviated as (θ)).

Example 1 A washed glass substrate was masked with a cellophane tape and then placed in a vapor deposition apparatus. The evaporation was performed by adjusting the substrate angle so that the evaporated SiO ₂ was incident on the substrate from the substrate surface at an elevation angle of 10 °. The pressure during the evaporation was 3 × 10 ⁻³ Pa or less. After the evaporation, the cellophane tape was peeled off. Washed with acetone. The thickness of the obtained SiO ₂ was 500 nm. 4- (allyl-oxy) -benzoic acid-4'methoxyphenyl ester is reacted with pentamethylcyclopentasiloxane in the same manner as described in JP-B-63-41400 to obtain a 5-membered ring pentasiloxane liquid crystal polymer. Was. This liquid crystal polymer showed a nematic phase. This was dissolved in methylene chloride to a concentration of 10% and spin-coated on a substrate with a SiO ₂ film. The laminate of the obtained oriented liquid crystal polymer film and the substrate was clouded under crossed nicols, and had a thickness of 1.8 μm. The obtained film was heated at 60 ° C for 3 hours.
After heating under crossed Nicols after heating for
It was found that uniform deposition of the liquid crystal polymer was obtained when iO ₂ was deposited. FIG. 1 shows the vapor deposition direction and the tilt axis when measuring the amount of transmitted light, and FIG. 2 shows the change in the amount of transmitted light when tilted along the tilt axis. FIG. 2 shows that the light was quenched when the tilt axis was set to b and the tilt angle was 30 °, and it was found that the liquid crystal polymer was oriented at an angle of elevation of 60 ° from the film surface.

Comparative Example 1 A liquid crystal polymer was applied and heat-treated in the same manner as in Example 1 except that the portion masked with cellophane tape in Example 1 was used as a substrate. When observed under crossed Nicols, schlieren texture was observed, and it was found that there was no extinction position even when rotated in the plane of the substrate, indicating that it was not oriented in the plane. Although the substrate was tilted around the tilt axis a and the tilt axis b, it was found that there was no extinction position, and thus no tilt orientation was observed.

Example 2 Polyvinyl alcohol (Poval 117, manufactured by Kuraray Co., Ltd.) was coated on a cellulose acetate film having a thickness of 80 μm.
A 0% aqueous solution was applied and dried in hot air at 100 ° C. The thickness of the obtained polyvinyl alcohol was 2 μm.
A laminate of an oriented liquid crystal polymer film and a substrate was obtained in the same manner as in Example 1 except that this film was used as a substrate. The laminate of the obtained oriented liquid crystal polymer film and the substrate was clouded under crossed nicols, and had a thickness of 1.8 μm. After heating the obtained film at 60 ° C. for 3 minutes and observing it under crossed Nicols, it was found that a uniform alignment of the liquid crystal polymer was obtained when SiO ₂ was deposited. FIG. 1 shows the vapor deposition direction and the tilt axis when measuring the amount of transmitted light, and FIG. 3 shows the change in the amount of transmitted light when tilted along the tilt axis. FIG. 3 shows that the light was extinguished when the inclination axis was b and the inclination angle was 30 °, indicating that the oriented liquid crystal polymer was oriented at an inclination of 30 ° from the normal direction.

By using the oriented liquid crystal polymer film or oriented liquid crystal oligomer polymer film in which the optical axis of the film is at an elevation angle of 10 ° to 80 ° from the film surface, a transparent or translucent polymer can be obtained. By laminating it with a film or combining it with a uniaxially oriented retardation film, a composite retardation plate having a wide viewing angle can be obtained. Further, by applying these to an STN liquid crystal display device, the display characteristics of the liquid crystal display device, particularly, the viewing angle characteristics can be significantly improved.

[0069]

The use of the oriented liquid crystal polymer film or oriented liquid crystal oligomer polymer film in which the optical axis of the film is at an elevation angle of 10 ° to 80 ° from the film plane according to the present invention is transparent or translucent. A composite retardation plate having a wide viewing angle can be obtained by laminating with a polymer film or combining with a uniaxially oriented retardation film. Further, by applying these to an STN liquid crystal display device, the display characteristics of the liquid crystal display device, particularly, the viewing angle characteristics can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a layout diagram when measuring the amount of transmitted light.

FIG. 2 is a diagram illustrating a relationship between a tilt angle and a transmitted light amount under crossed Nicols in the first embodiment.

FIG. 3 is a diagram illustrating a relationship between a tilt angle and a transmitted light amount under crossed Nicols in a second embodiment.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G02F 1/1335 510 G02F 1/1335 510 // C08L 67:04 C08L 67:04 83:04 83:04 (56) Kaihei 5-80326 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91 C08G 77/00-77/62 C08J 5/18 WPI / L ( QUESTEL)

Claims (12)

(57) [Claims] 1. A film comprising a side chain type liquid crystal polymer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, wherein said liquid crystal polymer comprises a linear or linear polymer comprising the following repeating unit (I): A cyclic liquid crystal polymer, the average number of repeating units per molecule is 4 or more and 10,000 or less, and the optical axis of the film is 10 ° or more and 8 ° or more as an elevation angle from the film surface.
An oriented liquid crystal polymer film, which is inclined at an angle of 0 ° or less. Embedded image (In the formula, A is a group represented by the following formula (II) or (III); in formula (II), -Si-O- is a main chain of formula (I); C—CH ₂ — has the formula (I)
And the COO group is located on a side chain other than R ₁ of the side chain. In the formula (I), when A is the formula (II), R ₁ is hydrogen, an alkyl group having 1 to 6 carbon atoms or a phenyl group. In the formula (I), when A is the formula (III), R ₁ is hydrogen or an alkyl group having 1 to 6 carbon atoms. Embedded image Embedded image k is an integer of 2 to 10, m is 0 or 1, p
Is 0 or 1, and Ar ₁ or Ar ₂ is independently 1,
4-phenylene group, a 1,4-cyclohexane group, pyridine-2,5-diyl group or pyrimidine-2,5-diyl group, L is _{-CH 2 -O-, -O-CH 2} -, -COO -, -OCO-
, -CH ₂ -CH _2- , -CH = N-, -N = CH- or Wherein R is hydrogen, halogen, cyano, alkyl having 1 to 10 carbons or 1 to 1 carbon
It is an alkoxy group of 0. ) 2. A film comprising a polymer of a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, wherein the liquid crystal oligomer comprises the repeating unit (I) according to claim 1 and the following repeating unit: A linear or cyclic liquid crystal oligomer comprising units (IV), wherein the number of repeating units (I) and (IV) in one molecule of the oligomer is n
And n ′, n and n ′ are each independently an integer of 1 to 20, 4 ≦ n + n ′ ≦ 21, and the terminal group of the repeating unit (IV) is polymerized; The optical axis is 10 ° or more from the film surface as an elevation angle of 8
An oriented liquid crystal oligomer polymer film, which is inclined at an angle of 0 ° or less. Embedded image Wherein A is the same as described in the repeating unit (I), k ′ is an integer of 2 to 10, m ′ is 0 or 1, p ′ is 0 or 1, and Ar ₃ and Ar ₄ is independently a 1,4-phenylene group, a 1,4-cyclohexane group, a pyridine-2,5-diyl group, a pyrimidine-2,5,
- diyl group, L 'is _{-CH 2 -O-, -O-CH 2} -, -COO-
_{, -OCO-, -CH 2 -CH 2 -} , -CH = N -, - N = CH- or embedded image Wherein R ′ is hydrogen or carbon number 1
To 5 alkyl groups. ) 3. A linear or cyclic liquid crystal polymer comprising the repeating unit (I) of claim 1 is formed on a substrate which has been subjected to an alignment treatment, and then subjected to a heat treatment so that the liquid crystal polymer is removed from the film surface. The method for producing an oriented liquid crystal polymer film according to claim 1, wherein the film is oriented at an elevation angle of 10 ° or more and 80 ° or less. 4. The repeating units (I) and (I) according to claim 2,
After forming a linear or cyclic liquid crystal oligomer composed of V) on a substrate that has been subjected to an alignment treatment, heat treatment is performed to align the optical axis from the film surface to an angle of elevation of 10 ° or more and 80 ° or less, and then a repeating unit 3. The method for producing an oriented liquid crystal oligomer polymer film according to claim 2, wherein the terminal group of (IV) is polymerized. 5. The method for producing an oriented liquid crystal polymer film according to claim 3, wherein the orientation treatment of the substrate is oblique vapor deposition of an inorganic substance. 6. The method for producing an oriented liquid crystal oligomer polymer film according to claim 4, wherein the orientation treatment of the base material comprises oblique vapor deposition of an inorganic substance. 7. A laminate of an oriented liquid crystal polymer film and a substrate obtained by laminating the oriented liquid crystal polymer film according to claim 1 and a transparent or translucent, oriented substrate. 8. A laminate of an oriented liquid crystal oligomer polymer film and a substrate, wherein the oriented liquid crystal oligomer polymer film according to claim 2 and a transparent or translucent, alignment-treated substrate are laminated. . 9. The method according to claim 1, wherein the base material is a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy. Item 8. A laminate of the oriented liquid crystal polymer film according to item 7 and a substrate. 10. A base material having an optical axis in the film plane,
9. The laminate of an oriented liquid crystal oligomer polymer film and a substrate according to claim 8, which is a uniaxially retardation film made of a thermoplastic polymer and having a positive refractive index anisotropy. 11. A uniaxially oriented retardation film comprising a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy, and the oriented liquid crystal polymer film according to claim 7. A composite retardation plate comprising a laminate of a base material and a laminate of the oriented liquid crystal oligomer polymer film according to claim 8 and a substrate. 12. A liquid crystal cell comprising a liquid crystal layer sandwiched between substrates having electrodes, having a positive dielectric anisotropy and having a helix axis twisted in a direction substantially horizontal and a direction perpendicular to the substrate when no voltage is applied. An oriented liquid crystal polymer film according to claim 1, an oriented liquid crystal oligomer polymer film according to claim 2, or an oriented liquid crystal polymer film according to claim 7, between the film and a polarizing film disposed outside thereof. A liquid crystal display device comprising at least one selected from a laminate of an oriented liquid crystal oligomer polymer film and a substrate or the composite retardation plate according to claim 11.