JP2001330729A - Optical anisotropic film and liquid crystal display - Google Patents

Abstract

(57) Abstract: An optically anisotropic film having a high wavelength dispersion of retardation and capable of controlling the wavelength dispersion, and a good black-and-white display using the optically anisotropic film can be obtained. Provided is a liquid crystal display device having low performance. [1] An optically anisotropic film including a polymer and a compound having at least two or more kinds of compounds having no absorption peak in a visible region and having an absorption peak in an ultraviolet region. Retardation (measuring wavelength 546n
m) is 50 to 3000 nm, and the value of α defined by the following mathematical formula (1) of the optically anisotropic film is 1.07 or more. ## STR1 ## _{α = R F / R D ···} (1) [ wherein, Letter R _F is measured at a wavelength corresponding to the hydrogen F line (wavelength 486 nm) - de - the value of Deployment, R _D Is the retardation value measured at the wavelength corresponding to the sodium D line (wavelength 589 nm). ] [2] The above [1]
A liquid crystal display device using the optically anisotropic film described in 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optically anisotropic film used for a nonlinear optical element or a liquid crystal display device, and a liquid crystal display device using the optically anisotropic film.

[0002]

2. Description of the Related Art A retardation film is obtained by uniaxially stretching a transparent thermoplastic polymer film, and is used for a liquid crystal display device, particularly a super twisted nematic (hereinafter sometimes referred to as STN) type liquid crystal display device or an electric field. Controlled birefringence (hereinafter sometimes referred to as ECB) type liquid crystal display device (hereinafter, referred to as ECB)
(Which may be referred to as an LCD) and is used as an optical compensator for improving display quality by compensating coloring. A liquid crystal display device using the retardation film is light, thin,
It has the advantages of being inexpensive. However, ST
The N-type LCD has a problem that its response speed is low, and its improvement is being studied. In order to improve the response speed, it is effective to reduce the cell gap by using a liquid crystal having a large refractive index anisotropy (Δn). However, a liquid crystal having a large Δn generally has a large wavelength dependence of Δn. Therefore, a retardation film used in combination with a liquid crystal cell also has a large wavelength dependence of Δn, that is, a retardation having a large wavelength dependence of retardation. It is known that using a film is effective. High response speed, that is, Δn of liquid crystal
When a liquid crystal cell having a large value and a conventional retardation film are used, a liquid crystal display device having high contrast cannot be obtained. Therefore, the wavelength dispersion characteristic of Δn of the liquid crystal material used in a high-speed response STN type liquid crystal display device. There is a demand for a retardation film having a large wavelength dispersion characteristic that conforms to the above. Further, it is ideal to use a retardation film having a wavelength dispersion characteristic that completely matches the wavelength dispersion characteristic of Δn of the liquid crystal material in combination. However, for that purpose, the wavelength dispersion can be increased, and Fine adjustment of the wavelength dispersion is required.

As a method for improving the wavelength dispersion of a retardation film, Japanese Unexamined Patent Publication (Kokai) No. 5-107413 discloses a retardation film using polysulfone (hereinafter sometimes referred to as PSf) having high wavelength dispersion. Have been. Similarly, JP-A-6-174923 discloses the use of polyarylate having high wavelength dispersion. However, polysulfone and polyarylate are difficult to process due to their high glass transition temperatures, and have a problem in industrial production. Further, since the wavelength dispersion characteristics of the retardation vary depending on the liquid crystal material used for the liquid crystal cell, it may be necessary to control the wavelength dispersion of the retardation film.
JP-A-5-27119 and JP-A-6-1302
No. 27 discloses that the wavelength dispersion is controlled by a combination of optically anisotropic bodies having different wavelength dispersion values.

Japanese Patent Laid-Open Publication No. Hei 4-500284 discloses that a side-chain type liquid crystal polymer having a linear or cyclic main chain is used to obtain the same temperature dependence and liquid crystal molecules as those used in a liquid crystal cell. A retardation film having wavelength dependence is illustrated. It is disclosed that an oriented liquid crystal polymer film can be obtained by forming a liquid crystal polymer on an alignment film or applying an external field such as an electric field or a magnetic field to the liquid crystal polymer film. However, it is difficult to actually form a liquid crystal polymer using an alignment film or to perform alignment by applying an external field such as an electric field or a magnetic field to the liquid crystal polymer film from the viewpoint of the degree of alignment. In addition, Japanese Patent Application Laid-Open No. Hei.
No. 3 discloses a retardation film having a wavelength dispersion of the same refractive index anisotropy as liquid crystal molecules used in a liquid crystal cell by dispersing liquid crystal molecules in a polymer film and stretching the polymer film together. Has been described. However, there is no description of specifically preferable wavelength dispersibility and how much physical properties and structure of liquid crystal should be dispersed.

In Example 6 of Japanese Patent Publication No. Hei 7-13683, an example is shown in which a liquid crystal compound is blended with polyvinyl chloride to increase the wavelength dispersion. A substance having a low point causes deformation and deterioration of optical characteristics when used in a high-temperature environment, and is difficult to use. Japanese Patent Application Laid-Open No. 7-13023 discloses a method of adjusting wavelength dispersion by adding a plasticizer to polycarbonate or polyarylate.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optically anisotropic film having a high wavelength dispersion of retardation and capable of easily controlling the wavelength dispersion, and a good black-and-white film using the optically anisotropic film. An object of the present invention is to provide a liquid crystal display device which can provide a display and has small viewing angle dependence.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, at least two or more types of specific polymers are sometimes referred to as "matrix polymers". By adding a compound in combination, an optically anisotropic film having a large wavelength dependence of retardation can be easily obtained without using a polymer having a large wavelength dispersion of retardation. They have found that they can be easily controlled, and have completed the present invention.

That is, the present invention relates to [1] an optically anisotropic film containing a polymer and a compound having no absorption peak in at least two kinds of visible regions and having an absorption peak in an ultraviolet region. The retardation (measuring wavelength 546 nm) of the rectangular film is 50 to 3000 nm,
Α of the optically anisotropic film defined by the following equation (1)
Is 1.07 or more.

[0009]

Α = R _F / R _D (1)

[0010] [wherein, R _F is hydrogen F line (wavelength 486n
m) is the value of the retardation measured at the wavelength corresponding to, and _RD is the value of the retardation measured at the wavelength corresponding to the sodium D line (wavelength 589 nm). ]

[0011] The present invention also relates to [2] a liquid crystal display device using the optically anisotropic film described in [1].

[0012]

Next, the present invention will be described in detail.
The matrix polymer used in the present invention will be described. Polymer used in the matrix of the optical anisotropic film, when using the optical anisotropic film at high temperature,
A polymer that does not change optical properties or shape at the temperature of the bonding step with the liquid crystal cell is preferable, and a thermoplastic engineering polymer having a glass transition temperature to some extent or a polymer to which a plasticizer is added has a flowing temperature. A polymer having a high degree of is preferably used.

The lower limit of the glass transition temperature or softening temperature of the matrix polymer is determined within the temperature range in which the liquid crystal display device is used so that there is no change in optical characteristics or deformation such as film shrinkage. When the glass transition temperature is too high, the upper limit is determined because it is industrially unfavorable if the glass transition temperature is too high.

The range of the glass transition temperature or softening temperature required for the matrix polymer is 80 to 250 ° C.
Is preferably 90 to 230 ° C, more preferably 100 to 200 ° C.

Preferred polymers satisfying these conditions include polycarbonate, polyallylate, cellulose acetate, cellulose acetate, cellulose acetate, ethylene vinyl alcohol copolymer and the like, and preferably, polycarbonate, polyarylate, cellulose acetate and the like. Is done.

As a method of expressing retardation, there is a method in which a film obtained by mixing a polymer and a compound is stretched while being heated at a temperature not lower than the glass transition temperature or softening point of the polymer and not higher than the melting temperature of the polymer. No.
Polymers suitable for the method include polycarbonate, 2
Examples of cellulose acetate, cellulose acetate, polystyrene, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, and the like,
Preferably, polycarbonate, cellulose triacetate, polyethylene terephthalate and polystyrene are exemplified.

Additives may be used for the purpose of imparting mechanical strength to these matrix polymers or improving adhesiveness when pasting them to LCD cells. The type and amount of the additive are not particularly limited as long as the purpose of the present invention is not impaired.

Next, the absorption peak wavelength of each compound having no absorption peak in at least two kinds of visible regions and having an absorption peak in an ultraviolet region used in the present invention is 250.
It is more preferably in the range of from 400 to 400 nm, particularly preferably from 330 to 385 nm. Here, the peak in the present invention refers to the maximum absorption point of the absorption peak. When each of the compounds has an absorption peak in the visible region, coloring is observed in the optically anisotropic film, which may cause a problem when used as a film, and the absorption peak wavelength of each of the compounds is reduced. If it is less than 250 nm, the effect on the wavelength dispersion is small.

The compound having no absorption peak in the visible region and having an absorption peak in the ultraviolet region used in the present invention is represented by the following general formula (1):

[0020]

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[In the formula, R ₁ and R ₂ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 15 carbon atoms, and m and n each independently represent Represents an integer of 0 to 4; Or a compound represented by the following general formula (2)

[0022]

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[Wherein R ₃ and R ₄ each independently represent a hydrogen atom, a fluorine atom, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, an alkyl group having 1 to 12 carbon atoms, A 12-alkoxy group, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxyalkyl group having 2 to 12 carbon atoms. A ₁ , A ₃
Are each independently a hydrogen atom which may be substituted with an alkyl group having 1 to 10 carbon atoms or a fluorine atom,
It represents a 1,4-phenylene group or a 1,4-cyclohexylene group. A ₂ may have a hydrogen atom substituted with an alkyl group having 1 to 10 carbon atoms or a fluorine atom,
Shows a 1,4-phenylene group. p and r are each independently 0 or 1. a and b are each independently an integer of 0 to 2. q is an integer of 1 to 3. However, when q is 1, p and r do not become 0 at the same time. Or a compound represented by the following general formula (3)

[0024]

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[Wherein, R_Five, R₆Are each independently water
Element atom, fluorine atom, trifluoromethyl group, trifluoro
Oromethoxy group, cyano group, alkyl having 1 to 12 carbons
Group, an alkoxy group having 1 to 12 carbon atoms, 2 to 12 carbon atoms
Alkenyl group, alkynyl group having 2 to 12 carbon atoms or carbon
It represents an alkoxyalkyl group having a prime number of 2 to 12. A_Four,
A_Five, A₆Is independently a hydrogen atom having 1 to 1 carbon atoms
An alkyl group having 10 or an alkoxy group having 1 to 10 carbon atoms
Or furan-2, which may be substituted by a fluorine atom.
5-diyl, pyrrole-2,5-diyl, imidazole
-2,5-diyl, thiazole-2,5-diyl, oxo
Sadiazole-2,5-diyl, triazole-2,5
-Diyl, thiadiazole-2,5-diyl, indene
-2,5-diyl, indene-2,6-diyl, benzo
Furan-2,5-diyl, benzofuran-2,6-dii
Benzothiophene-2,5-diyl, benzothiophene
2,6-diyl, quinoline-2,7-diyl,
Norin-2,6-diyl, fluorene-2,7-dii
Fluorene-2,6-diyl, carbazole-2,
7-diyl or carbazole-2,6-diyl
Shows any of these groups. B₁, B_Two , B_Three, B_FourAre independent
A hydrogen atom may be a linear or branched carbon
An alkyl group of the formulas 1 to 10, even if linear or branched
Good C1-C10 alkoxy group or fluorine atom
Represents a 1,4-phenylene group which may be substituted
You. c, d, e, f, g, and h are each independently 0 or
Is 1. Where c, d, e, f, g, and h are simultaneously
It cannot be zero. Or a compound represented by the following
General formula (4)

[0026]

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[In the formula, R ₇ , R ₈ and R ₉ are a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkyl group having 1 to 12 carbon atoms. And an optionally substituted alkoxy group, cyclohexyl group or halogen atom. And the like. In the optical film of the invention, two or more individual compounds selected from these are used in combination.

In the compound represented by the general formula (1) used in the present invention, R ₁ and R ₂ are each independently a hydrogen atom, a linear or branched methyl, ethyl or propyl group. , Butyl, pentyl, hexyl,
Heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl. Preferably, it is a compound having 4 or more carbon atoms.

In the compound represented by the general formula (2) used in the present invention, R ₃ and R ₄ are each independently specifically methyl, ethyl, propyl, butyl, pentyl,
Hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, ethenyl, propenyl, butenyl,
Pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, noninyl, desinyl, dodecinyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, pentyloxy, pentyloxy, pentoxy , Octyloxy, nonyloxy, decyloxy, undecyloxy,
Dodecyloxy, methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, pentyloxymethyl, hexyloxymethyl, heptyloxymethyl, octyloxymethyl, nonyloxymethyl, decyloxymethyl, methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl , Pentyloxyethyl, hexyloxyethyl, heptyloxyethyl, octyloxyethyl, nonyloxyethyl, decyloxyethyl, methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl, pentyloxypropyl, hexyloxypropyl, heptyloxypropyl, octyl Oxypropyl, nonyloxypropyl,
Decyloxypropyl, methoxybutyl, ethoxybutyl, propoxybutyl, butoxybutyl, pentyloxybutyl, hexyloxybutyl, heptyloxybutyl, octyloxybutyl, nonyloxybutyl, decyloxybutyl, methoxypentyl, ethoxypentyl, propoxypentyl, butoxy Pentyl, pentyloxypentyl, hexyloxypentyl, heptyloxypentyl, heptyloxypentyl, octyloxypentyl, nonyloxypentyl, decyloxypentyl, etc., a hydrogen atom, a fluorine atom, a trifluoromethyl group, a trifluoromethoxy group, And a cyano group. These groups may be linear or branched.

A ₁ and A ₃ each independently represent a 1,4-phenylene group or 1,4-cyclohexylene in which a hydrogen atom may be substituted by an alkyl group having 1 to 10 carbon atoms or a fluorine atom. Represents a group. As A ₁ and A ₃ ,
Specific examples include a 1,4-phenylene group and a 1,4-cyclohexylene group, and a 1,4-phenylene group is preferable. A ₂ represents a hydrogen atom which may be substituted with an alkyl group having 1 to 10 carbon atoms or a fluorine atom,
Shows a phenylene group. A ₂ is specifically 1,4-
Phenylene groups are preferred. p and r are each independently 0
Or 1. a and b are each independently an integer of 0 to 2. q is an integer of 1 to 3. However, when q is 1, p and r do not become 0 at the same time. Specifically, it is preferable that p = q = r = a = b = 1.

In the compound represented by formula (3) used in the present invention, R ₅ and R ₆ are each independently specifically a hydrogen atom, a fluorine atom, a trifluoromethyl group,
Trifluoromethoxy group, cyano group, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, 2 carbon atoms
An alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxyalkyl group having 2 to 12 carbon atoms.
Specifically, R ₅ and R ₆ each independently represent methyl,
Ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, propynyl, butynyl, pentynyl Hexynyl, heptynyl, octynyl, noninyl, decynyl, dodecinyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, methoxymethyl, ethoxymethyl, propoxy Methyl, butoxymethyl, pentyloxymethyl, hexyloxymethyl, heptyloxymethyl, octyloxymethyl, nonyloxy Tyl, decyloxymethyl, methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl, pentyloxyethyl, hexyloxyethyl, heptyloxyethyl, octyloxyethyl, nonyloxyethyl, decyloxyethyl, methoxypropyl, ethoxypropyl, propoxypropyl ,
Butoxypropyl, pentyloxypropyl, hexyloxypropyl, heptyloxypropyl, octyloxypropyl, nonyloxypropyl, decyloxypropyl, methoxybutyl, ethoxybutyl, propoxybutyl, butoxybutyl, pentyloxybutyl, hexyloxybutyl, heptyloxybutyl Octyloxybutyl, nonyloxybutyl, decyloxybutyl, methoxypentyl, ethoxypentyl, propoxypentyl, butoxypentyl, pentyloxypentyl, hexyloxypentyl, heptyloxypentyl, heptyloxypentyl, octyloxypentyl, nonyloxypentyl, decyl Each group such as oxypentyl, hydrogen atom, fluorine atom, trifluoromethyl group,
Examples include a trifluoromethoxy group and a cyano group. These groups may be linear or branched.

A ₄ , A ₅ and A ₆ each independently represent a hydrogen atom having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms,
2,5-diyl, pyrrole-2,5-diyl, imidazole-2,5-diyl, thiazole- which may be substituted by an alkoxy group or a fluorine atom of
2,5-diyl, oxadiazole-2,5-diyl,
Triazole-2,5-diyl, thiadiazole-2,
5-diyl, indene-2,5-diyl, indene-
2,6-diyl, benzofuran-2,5-diyl, benzofuran-2,6-diyl, benzothiophene-2,5
-Diyl, benzothiophen-2,6-diyl, quinoline-2,7-diyl, quinoline-2,6-diyl, fluorene-2,7-diyl, fluorene-2,6-diyl, carbazole-2,7- It represents any of diyl and carbazole-2,6-diyl. B ₁ , B ₂ , B
₃ and B ₄ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be linear or branched, an alkoxy group having 1 to 10 carbon atoms which may be linear or branched, Or 1, which may be substituted with a fluorine atom,
Shows a 4-phenylene group. Specifically, it is preferably a 1,4-phenylene group. c, d, e, f, g, h
Is each independently 0 or 1. Where c,
d, e, f, g, and h do not become 0 at the same time.

In the compound represented by the general formula (4) used in the present invention, R ₇ , R ₈ and R _{9 each} represent a hydrogen atom, a carbon atom
~ 12 linear or branched alkyl groups,
A linear or branched alkoxy group having 1 to 12 carbon atoms, a cyclohexyl group or a halogen atom; Specifically, each of R ₇ , R ₈ and R ₉ is, independently and independently, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, methoxy, ethoxy, Propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, cyclohexyl and other groups, hydrogen atom, fluorine atom,
Examples include a chlorine atom, a bromine atom and an iodine atom. These groups may be linear or branched.

The mixing ratio of the compound used in the optical film of the present invention, which does not have at least two absorption peaks in the visible region but has an absorption peak in the ultraviolet region, to the matrix polymer, is large. If it is too much, the mechanical strength of the optically anisotropic film is lowered, and it becomes difficult to handle, so there is a preferable upper limit. On the other hand, if the proportion of the compound is too small, the optical properties of the optically anisotropic film are hardly developed, which is not preferable.

When the compound is mixed with a matrix polymer, [(compound) / (sum of compound and polymer)] is 1 for each compound.
% Or more, and [(sum of compound) / (sum of compound and sum of polymer)] is preferably 2 to 30% by mass, and 2 to 15% by mass.
% Is more preferred.

Next, the form of the compound having no absorption peak in at least two visible regions and having an absorption peak in an ultraviolet region in the optically anisotropic film of the present invention will be described. In the optically anisotropic film of the present invention, each of the compounds may be phase-separated from the matrix polymer to form a domain, or may be compatible. Individual compounds may be adsorbed on the polymer. Whether the phases are separated, compatible or adsorbed is determined by the combination of each compound used and the polymer used.

In the optically anisotropic film of the present invention, when each compound is phase-separated from the matrix polymer, scattering of visible light may occur at the interface between the domain of each compound and the matrix polymer. There is. In the optically anisotropic film of the present invention, it is preferable that internal scattering due to scattering at these interfaces is small. This is because the scattered light generally changes its polarization state, so that in the case of an optically anisotropic film having large internal scattering, the properties may be deteriorated, and the transmittance of visible light is deteriorated. In order to reduce internal scattering, the length of the major axis of the individual compound or the domain of the individual compound is preferably 20 to 500 nm, more preferably 30 to 400 nm.

In the optically anisotropic film of the present invention, when it is desired to make each compound compatible with a polymer or to adsorb each compound to a polymer, a known compatibilizer is used. You may.

Retardation (measurement wavelength: 550 nm) observed from the normal direction of the optically anisotropic film of the present invention.
Should be 50 to 3000 nm, preferably 10 to 3000 nm.
0 to 2500 nm. The retardation is 50n
If it is less than m, the effect as a retardation film is small, and if it exceeds 3000 nm, it is not preferable because it is not practical as a retardation film.

As an index indicating the wavelength dispersion of the retardation of the optically anisotropic film of the present invention, the F line of hydrogen (wavelength 486 nm) was obtained from the normal direction of the film using the Senarmont method.
m) Retardation RF measured at a wavelength corresponding to
When, using the ratio α = R _F / R _D retardation R _D measured at a wavelength corresponding to sodium D ray (wavelength 589 nm).

In the optically anisotropic film of the present invention, the index α indicating the wavelength dispersion is essential to be not less than 1.07, preferably from 1.07 to 1.300, more preferably 1. 080 to 1.250. If the index α is 1.
If the value is less than 07, it is not practical to achieve the object, and therefore it is not preferable.

As an index indicating the characteristics of an optically anisotropic film exhibiting good viewing angle characteristics, retardation (R) measured from the normal direction of the film using light of 550 nm is used.
₀ ) and the retardation (R ₄₀ ) ratio R ₄₀ / R ₀ when the incident angle of light on the film is inclined by 40 ° around the slow axis of the film. In the optically anisotropic film of the present invention, the ratio is preferably larger than 0.900 and smaller than 1.100 in order to reduce the viewing angle dependency. If the ratio is 0.900 or less, it is not practical because it is not practical for widening the viewing angle of the retardation film. If the ratio is 1.100 or more, it is not practical for widening the viewing angle of the retardation film. Absent.
More preferably, the ratio is close to one. However, the ratio can be appropriately selected depending on the viewing angle dependence of the liquid crystal cells used in combination.

Next, a method for producing the optically anisotropic film of the present invention will be described. The optically anisotropic film of the present invention is obtained by mixing a polymer and a compound having no absorption peak in at least two or more visible regions and having an absorption peak in an ultraviolet region, forming the film, and then stretching the film. (Hereinafter, may be referred to as a first manufacturing method). Alternatively, it is also obtained by stretching the film after forming it into a film with a polymer, and adsorbing at least two or more compounds having no absorption peak in the visible region and having an absorption peak in the ultraviolet region to the stretched film ( Hereinafter, it may be referred to as a second manufacturing method). As a method of mixing the compound and the matrix polymer in the first production method, it is preferable to mix them in a solution state in order to uniformly mix them. Specifically, there is a method in which a polymer is suspended or dissolved in a solvent, and the compound is suspended or dissolved in the solvent and mixed. The solvent used in the present invention preferably has high solubility in a polymer.

As a method for forming a film comprising the compound and the matrix polymer, a solvent casting method in which the compound or the matrix polymer is dissolved in a solvent and casting is performed, and the mixture is kneaded in a solid state, extruded from a die or the like, and extruded into a film. Examples thereof include a molding method, a calendering method in which a film is kneaded in a solid state and then formed into a film with a calendar roll, and a press molding method in which a film is formed by pressing. Among them, the solvent casting method having excellent film thickness accuracy is preferable. The thickness of the film after film formation is not particularly limited, but if it is too thin, the mechanical strength is adversely affected, and if it is too thick, the evaporation rate of the solvent when the film is formed by the solvent casting method becomes slow, and the productivity becomes poor. For this reason, the thickness is preferably within a certain range. The thickness of the film after film formation is preferably from 20 to 500 μm, more preferably from 50 to 300 μm.

Further, the second optical anisotropic film of the present invention
The compound may be adsorbed on a film that has been formed and stretched in the same manner as in the first method. For the method of adsorbing the compound, for example, a method of dissolving the compound in a good solvent for the compound with a poor solvent for the stretched film and impregnating the stretched film with the compound in the compound solution, or a temperature lower than the softening temperature of the film, A method of melting the compound at a temperature equal to or higher than the melting point of the compound, impregnating the stretched film with the compound in the compound melt,
Examples of the method include impregnating the powdered compound with the stretched film.

As the stretching method when the film is stretched while heating after film formation, a tenter stretching method, an inter-roll stretching method, an inter-roll compression stretching method and the like are exemplified. From the viewpoint of the uniformity of the film surface, a tenter stretching method and a roll-to-roll stretching method are preferred. There is no particular limitation on the method of heating the film.

As a stretching method, a known method can be used. For example, (A) the film produced in the film production step is uniaxially stretched, and as described in JP-A-6-300916, when the film is thermally relaxed at a temperature higher than the glass transition temperature or the softening temperature, it is parallel to the film surface. And (B) uniaxially stretching the film prepared in the film forming step while suppressing elongation in a direction perpendicular to the stretching axis, and applying a heat-shrinkable film to at least one surface of the film. A method in which the heat-shrinkable film is bonded so that the heat-shrinkable axis of the film is orthogonal to the stretch axis of the uniaxially stretched polymer film, and the obtained bonded body is heated and shrunk; As disclosed in JP-A-5-157911, a film having heat shrinkability on at least one surface of the film prepared in the film forming step is used. That heat shrinkage axis stuck to perpendicular to the stretching axis of the polymer film that is said uniaxially stretched film, and a method of stretching the resulting bonded body. Among them, the methods (A) and (B) are preferable in terms of mass productivity and cost.

Here, the method of uniaxially stretching the film is as follows.
Although any of the methods described above may be used, a method of uniaxially stretching by a roll-to-roll stretching method or a tenter stretching method is preferable in terms of controllability of the refractive index in the thickness direction and uniformity of retardation in the film plane. .

The heating temperature when the film is stretched by these stretching methods is appropriately selected depending on the softening temperature of the matrix polymer used and the transition temperature of the compound. Regarding the draw ratio, if the draw ratio is low, the orientation of the compound becomes insufficient, and if it is too high, the film thickness becomes too thin and handling becomes difficult. Specifically, the stretching ratio is preferably from 1.1 to 20 times, more preferably from 1.2 to 15 times. The stretching speed and the cooling speed after stretching are not particularly limited.

When the optically anisotropic film of the present invention is used in combination with an STN cell, a liquid crystal display device with good black-and-white display and small viewing angle dependence can be obtained.

[0051]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. The absorption peak wavelength of the compound was measured by dissolving the compound in a solvent and using a spectrophotometer (U-350, manufactured by Hitachi, Ltd.). The retardation of the optically anisotropic film of the present invention is 420, 440, 480, 550, 575, 60
Using a λ / 4 plate of 0 and 700 nm, the measurement was carried out by a polarization analyzer equipped with a spectroscope by using the Senarmont method. The value of α defined by the mathematical formula (1) indicating the wavelength dispersion of the optically anisotropic film is obtained by measuring the retardation measured using the Senarmont method using Lorentz's formula (Igor Pro3.0, manufactured by WaveMetrics) using a graph drawing software (Igor Pro3.0). Curve fitting is performed using the following mathematical expression 3), and a fitting coefficient obtained as a result of the fitting is used to calculate 48.
The retardation values of 6 nm and 589 nm are calculated by the formula (3).
And was calculated from Equation (1).

[0052]

(Equation 4)

[Where λ is the measurement wavelength, R (λ) is the retardation at the measurement wavelength, and A, B and λ ₀ are the fitting coefficients. The viewing angle dependency of the optically anisotropic film is determined by measuring the retardation and the slow axis of the film observed from the normal direction with light having a wavelength of 550 nm using the Senarmont method using a polarization analyzer equipped with a tilting jig. Evaluation was made by measuring the retardation when the film was tilted around.

Comparative Example 1 A compound represented by the following formula (1-1) (absorption peak wavelength 37
6 parts by mass of 5 nm (DMF solution) and polycarbonate resin (trade name: Panlite C-1400, manufactured by Teijin Limited) 9
4 parts by mass were dissolved and mixed in methylene chloride so as to be 20% by mass. The obtained solution was cast on a glass plate to obtain a film having a thickness of 100 μm.

[0055]

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The obtained film was stretched 1.5 times at 175 ° C., and the wavelength dispersion of retardation was measured. As a result, α was 1.099. The retardation of the obtained film at each wavelength of 400 nm, 460 nm, 500 nm, and 550 nm was R (400) and R (46).
0), R (500) and R (550), R (40
0) / R (550), R (460) / R (550), R
(500) / R (550) is shown in Table 1.

Comparative Example 2 A compound represented by the formula (1-1) (absorption peak wavelength: 375)
nm (DMF solution)) and a polycarbonate resin (trade name: Panlite C-1400, manufactured by Teijin Limited) 93
A mass part was dissolved and mixed in methylene chloride so as to be 20 mass%. The resulting solution was cast on a glass plate and
A film of 00 μm was obtained. The obtained film was 175
The film was stretched 1.5 times at ℃ and the wavelength dispersion of the retardation of the film was measured to be α = 1.104.
In addition, 400 nm, 460 nm, 50 nm
R (400), R (460), R (500), R (55)
0), R (400) / R (550), R (46)
0) / R (550) and R (500) / R (550) are shown in Table 1.

Example 1 The compound represented by the formula (1-1) (absorption peak wavelength 3
75 nm (DMF solution)) 3 parts by mass and the following formula (2-1)
10 parts by mass of a compound represented by the following formula (absorption peak wavelength: 340 nm (n-hexane solution)) and a polycarbonate resin (trade name: Panlite C-1400, manufactured by Teijin Limited) 87
A mass part was dissolved and mixed in methylene chloride so as to be 20 mass%. The resulting solution was cast on a glass plate and
A film of 00 μm was obtained.

[0059]

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The obtained film was stretched 1.5 times at 140 ° C., and the wavelength dispersion of the retardation was measured. As a result, an optically anisotropic film having α = 1.108 was obtained.
In addition, 400 nm, 460 nm, 50 nm
R (400), R (460), R (500), R (55)
0), R (400) / R (550), R (46)
0) / R (550) and R (500) / R (550) are shown in Table 1.

[0061]

[Table 1]

As described above, the optically anisotropic film of the present invention was prepared in Comparative Example 1 in which the addition concentration of one compound was changed.
Compared with Comparative Example 2, R (400) / R (550) falls in the range between Comparative Example 1 and Comparative Example 2, but R (460) /
R (550), R (500) / R (550) are Comparative Example 1.
And Comparative Example 2 do not fall within the range. In such an optical anisotropic film of the present invention, it is possible to obtain a wavelength dispersion different from the wavelength dispersion when the addition concentration of one kind of compound is changed, and it is possible to easily control the wavelength dispersion. Understand.

Example 2 The retardation ratio (R) of the film obtained in Example 1
₄₀ / R ₀ ) was R ₄₀ / R ₀ = 1.082. A film having heat shrinkability is bonded on both sides of the obtained film so that the heat shrink axis is orthogonal to the stretching axis of the uniaxially stretched polymer film, and the obtained bonded product is heated to 150 ° C. , And then heat-shrinked and stretched for 3.5 minutes. Retardation ratio of optically anisotropic film (R ₄₀ / R ₀ )
Was R ₄₀ / R ₀ = 0.961.
Thus, the obtained optically anisotropic film of the present invention was
When used in combination with a TN cell, a display with small viewing angle dependence can be obtained.

[0064]

The optically anisotropic film of the present invention exhibits a retardation suitable for the wavelength dependence of the retardation of the liquid crystal cell, and has a large wavelength dispersion of the retardation, and has a large wavelength dispersion of the retardation. Controllable, high-speed ST
When used suitably in combination with an N-type liquid crystal cell, a good black-and-white display can be obtained, and a liquid crystal display device with small viewing angle dependence can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/353 C08K 5/353 C08L 101/12 C08L 101/12 C09K 3/00 104 C09K 3/00 104B G02F 1/13363 G02F 1/13363 // C07D 413/14 C07D 413/14 F-term (reference) 2H049 BA12 BA25 BB13 BB47 BB49 BC03 BC09 BC22 2H091 FA11X FA11Z KA02 LA19 4C063 AA03 BB01 CC92 DD52 EE10 4F071 AA08 AA08A AC19 AF35 AH12 AH19 BA01 BB02 BB03 BB04 BB06 BB07 BC01 4J002 AB021 BB221 BC031 BE031 CF061 CF081 CG011 EL076 EU026 EU106 EU116 EU166 EV326 GP00

Claims (6)

[Claims] 1. An optically anisotropic film comprising a polymer and at least two or more compounds having no absorption peak in the visible region and having an absorption peak in the ultraviolet region, and a retardation of the optically anisotropic film. (Measurement wavelength 546 nm) is 5
0 to 3000 nm, wherein the value of α defined by the following formula (1) of the optically anisotropic film is 1.07 or more. [Number 1] alpha = in _{R F / R D ··· (1} ) [ wherein, Letter R _F is measured at a wavelength corresponding to the hydrogen F line (wavelength 486 nm) - de - the value of Deployment, R _D Is the retardation value measured at the wavelength corresponding to the sodium D line (wavelength 589 nm). ] 2. A polymer having no absorption peak in the visible region,
For the sum with the compound having an absorption peak in the ultraviolet region,
The optically anisotropic film according to claim 1, wherein the proportion of the compound is 2 to 30% by mass. 3. A compound having no absorption peak in the visible region and having an absorption peak in the ultraviolet region, has an absorption peak wavelength of 2
The optically anisotropic film according to claim 1 or 2, wherein the thickness is in a range of 50 to 400 nm. 4. An ultraviolet light region having no absorption peak in a visible light region.
A compound having an absorption peak at the following general formula (1):[Wherein, R₁, R_TwoIs independently a hydrogen atom or
C1-C15 linear or branched alkyl
M and n are each independently an integer of 0 to 4;
Represents a number. Or a compound represented by the following general formula:
(2)[Wherein, R_Three, R_FourAre each independently a hydrogen atom,
Elemental atom, trifluoromethyl group, trifluoromethoxy
Group, cyano group, alkyl group having 1 to 12 carbon atoms, 1 carbon atom
To 12 alkoxy groups, alkenyl having 2 to 12 carbon atoms
Group, alkynyl group having 2 to 12 carbon atoms or 2 to 1 carbon atoms
2 represents an alkoxyalkyl group. A₁, A_ThreeEach
Independently, the hydrogen atom may be an alkyl group having 1 to 10 carbon atoms.
Or a 1,4-phenylene atom which may be substituted by a fluorine atom
It represents a phenylene group or a 1,4-cyclohexylene group.
A_TwoIs an alkyl group having 1 to 10 carbon atoms.
1,4-phenyl optionally substituted by a fluorine atom
Shows a nylene group. p and r are each independently 0 or 1
It is. a and b are each independently an integer of 0 to 2;
You. q is an integer of 1 to 3. Where q
When p is 1, p and r do not become 0 at the same time. ]so
Or a compound represented by the following general formula (3):[Wherein, R_Five, R₆Are each independently a hydrogen atom,
Elemental atom, trifluoromethyl group, trifluoromethoxy
Group, cyano group, alkyl group having 1 to 12 carbon atoms, 1 carbon atom
To 12 alkoxy groups, alkenyl having 2 to 12 carbon atoms
Group, alkynyl group having 2 to 12 carbon atoms or 2 to 1 carbon atoms
2 represents an alkoxyalkyl group. A_Four, A_Five, A₆Is
Each independently represents an alkyl group having 1 to 10 carbon atoms;
Group, an alkoxy group having 1 to 10 carbon atoms or a fluorine atom
Furan-2,5-diyl, which may be substituted by
Pyrrole-2,5-diyl, imidazole-2,5-di
Yl, thiazole-2,5-diyl, oxadiazole
-2,5-diyl, triazole-2,5-diyl,
Asiazol-2,5-diyl, indene-2,5-di
Yl, indene-2,6-diyl, benzofuran-2,
5-diyl, benzofuran-2,6-diyl, benzothi
Offen-2,5-diyl, benzothiophene-2,6
-Diyl, quinoline-2,7-diyl, quinoline-2,
6-diyl, fluorene-2,7-diyl, fluorene
-2,6-diyl, carbazole-2,7-diyl or
Represents any group of carbazole-2,6-diyl
You. B₁, B_Two , B_Three, B_FourIs independently a hydrogen atom
Has 1 to 10 carbon atoms which may be linear or branched
Alkyl group, linear or branched carbon number 1
Substituted with 10 to 10 alkoxy groups or fluorine atoms
Represents a 1,4-phenylene group which may be present. c, d,
e, f, g, and h are each independently 0 or 1.
However, c, d, e, f, g, h must be 0 at the same time.
There is no. Or a compound represented by the following general formula (4):[Wherein, R₇, R₈, R₉Is a hydrogen atom, having 1 to 12 carbon atoms
Linear or branched alkyl group, carbon number of
1-12 straight-chain or optionally branched alkoxy
A cyclohexyl group or a halogen atom. ]so
2. The compound according to claim 1, which is a compound selected from the compounds shown
4. The optically anisotropic film according to any one of 3. 5. The optically anisotropic film according to claim 1, wherein a retardation ratio (R ₄₀ / R ₀ ) of the optically anisotropic film satisfies the following expression (2). . 0.900 <R ₄₀ / R ₀ <1.100 (2) [In the formula, R ₀ is a film normal measured by a polarization analyzer using a Senarmont method (measurement wavelength: 550 nm). R ₄₀ is the retardation as viewed from the direction, and R ₄₀ is an angle of incidence of light on the film of ₄₀ with the slow axis of the film as a rotation axis.
レ タ ー Retardation when measured at an angle. ] 6. A liquid crystal display device using the optically anisotropic film according to claim 1.