JPH08278409A - Oriented dyestuff film and its production, polarizing element and liquid crystal display device - Google Patents

Abstract

PURPOSE: To obtain a high contrast picture by using an oriented dyestuff film consisting of plural kinds of dyestuff and high in dichroism ratio. CONSTITUTION: The thin film is composed of at least one kind polyazo based dye-stuff material having a structure expressed by formula I and at least one kind of polyazo based dyestuff material having the structure expressed by formula II, and these dyestuff are oriented uniaxially, and the thin film has at least one kind of absorption peak within a range of 400-800nm, and the thickness of the thin film is >=10nm and <=1μm and the two-color ratio of at least one kind of absorption peak wave length is >=40. In formula I, Ar1 and Ar3 are selected independently from a group of formula III respectively. In this case, X1 and X2 are selected independently from the group of formula IV respectively, and (m) is an integer of 0-8. Ar2 is selected from the group of formula V. In formula II, X1 has the same definition with the formula IV. And, Ar4 is selected from the group of formula IV. In this way, a high contrast and high performance polarizing element and liquid crystal display device is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment dye film useful for a polarizing element, a method for producing the same, a polarizing element using the same, and a liquid crystal display device. More specifically, the present invention relates to an alignment dye film composed of a plurality of types of polyazo dichroic dyes, a method for producing the same, and a high-performance polarizing element and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A polarizing element is a liquid crystal display (hereinafter referred to as L
Sometimes referred to as a CD. ) Is widely used as an indispensable display. Currently, a polarizing element is manufactured by adsorbing iodine or a plurality of types of dichroic dyes on a stretched and oriented polyvinyl alcohol (hereinafter sometimes referred to as PVA) or its derivative film.

Of these, a polarizing film using iodine as a polarizing element has excellent initial polarizing performance in a wide wavelength range.
It is weak against water and heat and has a problem in its durability when used for a long time under high temperature and high humidity conditions. Various measures such as a protective film have been taken to increase durability, but they are not sufficient. Further, a polarizing element having a dye adsorbed thereto has excellent durability against water and heat, but has poor polarizing performance, as compared with a polarizing element having adsorbed iodine. Further, in this case, a plurality of types of dyes are used to ensure polarization performance in a wide wavelength range.

Full-color LCDs have been extremely actively developed. In these LCDs, the liquid crystal cell is required to have a high contrast ratio in order to display various colors. One effective method of increasing the contrast ratio of the liquid crystal cell is to improve the polarization performance of the polarizing element used in a wide wavelength range.

A color filter is used to make the liquid crystal cell full color. In this case, the amount of transmitted light is very small due to the light absorption of the polarizing element and the color filter. In order to obtain a bright LCD, a strong backlight must be used, and there are problems that the temperature of the liquid crystal cell rises and power consumption increases.

That is, in order to manufacture a high-performance full-color LCD, the polarization performance is excellent, and by maintaining an extremely high degree of polarization, a high contrast ratio is realized to improve the image quality, and durability to withstand a temperature rise due to the backlight is provided. A polarizing element having a property is extremely useful.

On the other hand, J. C. Wittmann et al. Have shown that an oriented PTFE thin film can be obtained by rubbing a polytetrafluoroethylene (hereinafter sometimes referred to as PTFE) on a glass substrate while applying pressure while heating. It has been reported that alkanes, liquid crystal molecules, polymers, oligomers, inorganic salts and the like can be aligned on this film as an alignment film [NATURE (Vol.352, 414, 1991)].
Year)〕.

As described above, a polarizing element having high polarization performance and durability required for a high performance full color LCD has not yet been known. A dichroic dye dyed with a stretch-oriented polymer has excellent durability, but has insufficient polarization characteristics. This is a problem due to insufficient orientation of dichroic dye molecules in the conventional technique. That is, if almost perfect uniaxial orientation is achieved with a dichroic dye, the polarization performance will be dramatically improved and this problem can be achieved. Therefore, there is a demand for a dichroic dye film which is easy to manufacture and is uniaxially oriented, and a method for manufacturing the same.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an alignment dye film having a high dichroic ratio composed of a plurality of types of dyes, a method for producing the same, and a high contrast and high performance polarizing element and liquid crystal using the same. It is to provide a display device.

[0010]

The inventors of the present invention have reached the present invention as a result of extensive studies to solve the above problems. That is, the present invention comprises the inventions described below. [1] A thin film comprising at least one polyazo dye material having a structure represented by the general formula (1) and at least one polyazo dye material having a structure represented by the general formula (2), These dyes are uniaxially oriented and the thin film is
It has at least one absorption peak in the range of 0 nm to 800 nm, the thickness of the thin film is 10 nm or more and 1 μm or less, and the dichroic ratio of at least one absorption peak wavelength is 4 or less.
An oriented dye film, which is 0 or more.

Embedded image Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃ (1) (In the formula, Ar ₁ and Ar ₃ are each independently selected from the following groups.

Embedded image Here, X ₁ and X ₂ are each independently selected from the following groups, and m is an integer of 0-8.

[Chemical 9] Ar ₂ is selected from the following groups.

[Chemical 10]

[Chemical 11] (In the formula, X ₁ has the same definition as above. Further, Ar ₄
Is selected from the following groups.

[Chemical 12]

[2] A polyazo dye material having the structure represented by the general formula (1) is formed on a thin film of the polyazo dye material having the structure represented by the general formula (2) described in [1] above. A thin film in which thin films are laminated, these dyes are uniaxially oriented, the thin film has at least one absorption peak in the range of 400 nm to 800 nm, and the thin film has a thickness of 10 nm or more and 1 μm or less and at least one of An alignment dye film having a dichroic ratio of absorption peak wavelengths of 40 or more. [3] At least one polyazo dye material having a structure represented by the general formula (2) described in [1] and at least one polyazo dye material having a structure represented by the general formula (1). And vapor deposition simultaneously from the vapor phase on a substrate having a fluorine-based resin alignment film on its surface [1]
A method for producing an alignment dye film as described above.

[4] A film of a polyazo dye material having a structure represented by the general formula (2) described in [1] above is vapor-deposited from a gas phase on a substrate having a fluorine resin alignment film on its surface. ,
The method for producing an alignment dye film according to [2], wherein a film of a polyazo dye material having a structure represented by the general formula (1) is deposited on the obtained vapor deposition film. [5] A polarizing element comprising a polymer film having the alignment dye film according to [1] on the surface, or a glass plate or a glass plate having a transparent electrode.

[6] A polarizing element comprising a polymer film having the alignment dye film according to [2] on the surface, or a glass plate or a glass plate having a transparent electrode. [7] Twisted between substrates having electrodes and having a positive dielectric anisotropy, substantially horizontally when no voltage is applied and with the spiral axis perpendicular to the substrate between approximately 90 ° and 270 °. A liquid crystal display device comprising a liquid crystal cell composed of an oriented liquid crystal layer, wherein the polarizing element according to [5] is arranged outside the liquid crystal cell. [8] Twisted between substrates having an electrode, having positive dielectric anisotropy, substantially horizontally when no voltage is applied, and with the spiral axis perpendicular to the substrate between approximately 90 ° and 270 °. A liquid crystal display device comprising a liquid crystal cell comprising an aligned liquid crystal layer, and the polarizing element according to [6] being arranged outside the liquid crystal cell.

In the present invention, a polyazo dye having a structure represented by the general formula (1) and a polyazo dye having a structure represented by the general formula (2) are used. All of the polyazo dyes having the structure represented by the general formula (1) have a rigid linear molecular structure, but achieve the perfect uniaxial orientation as far as the polarization performance of the obtained polarizing element is concerned. Preferably. For that purpose, it is preferable that the skeleton is a rigid linear chain (mesogen) having a shape as long as possible within the range of the general formula (1). Therefore, the substituents X ₁ , X ₂
Is preferably located only at the end of the molecular chain.

More specifically, as the polyazo dye, nine kinds of dyes D1 to D9 shown in Table 1 can be exemplified. Among them, D1, D6 and D6 are included.
The dyes represented by 7, D8 and D9 are preferable. Hereinafter, these compounds are referred to as D1, D6, D7, D8 and D9.

[0016]

[Table 1]

By combining the dye represented by the general formula (2), particularly good orientation useful as a polarizing element can be obtained.
In terms of orientation, the structure of X ₁ in the general formula (2) is
It is preferable to use hydrogen or an alkyl group in terms of orientation of the obtained dye film. N in the general formula (2) representing the length of the alkyl group is 0 to 8, preferably 0 to 5, and more preferably 2 to 3. More specifically,
D10 shown in Table 1 can be illustrated.

The required purity of the dye used depends on the type of impurities. Depending on the type of impurities, the orientation may not be lowered even if the purity is considerably lowered, but it is generally preferable that the purity is high. Depending on the type of impurities,
The purity is preferably 90 wt% or more and 100 wt% or less, more preferably 95 wt% or more and 100 wt% or less, and particularly preferably 99 wt% or more and 100 wt% or less.

The oriented dye film of the present invention is characterized by high orientation, and the oriented dye film has a structure represented by the general formula (1) and a dye represented by the general formula (2). As a state in which a plurality of dyes are contained in the film, the plurality of dyes may be contained substantially uniformly in a single layer, or the respective dye films may be laminated to form a single film. .

As a method of containing a plurality of dyes substantially uniformly in a single layer, there is a method of simultaneously vapor-depositing a plurality of the dyes from a vapor phase on an alignment film of a fluororesin. Also,
As a method for laminating each dye film into one film, first, a dye having a structure represented by the general formula (2) is vapor-deposited on a substrate provided with a fluorine-based resin alignment film, and then, A method of obtaining a multilayer film of a plurality of dyes by repeating the step of depositing another dye having a structure represented by the general formula (1) on the formed dye film is mentioned.

The orientation film of the fluororesin can be prepared by a known method, but a highly oriented film can be obtained by using the method described in US Pat. No. 5,180,470. In particular,
It can be prepared by rubbing a lump of fluororesin on the substrate under heating while applying pressure.

Fluorine-based resins used for the orientation film include polytetrafluoroethylene (PTFE) and poly-3.
Ethylene fluoride, polyvinylidene fluoride (hereinafter PVD
Sometimes referred to as F. ), A tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter, P
Sometimes referred to as FA. ), Tetrafluoroethylene-
An ethylene copolymer and the like are exemplified, but PTFE is preferable.

The heating temperature of the substrate at this time depends on the type of the substrate to be rubbed with the resin, but is not higher than the decomposition temperature of the resin and is preferably 100 ° C. or higher and 350 ° C. or lower. Resin is P
When it is TFE and the rubbing substrate is glass, the temperature is preferably 130 ° C. or higher and 340 ° C. or lower, more preferably 250 ° C. or higher and 340 ° C. or lower, and particularly preferably 300 ° C. or higher and 340 ° C. or lower.

The rubbing pressure can be appropriately selected depending on the types of the resin and the rubbing substrate. When the resin is PTFE and the rubbing substrate is glass, 0.5 kgf / cm ² is required to obtain a uniform alignment film having excellent alignment characteristics.
40 kgf / cm ² or less is preferable and 5 kgf / c
It is more preferably m ² or more and 20 kgf / cm ² or less.

The rubbing speed can be appropriately selected depending on the types of the resin and the rubbing substrate. When the resin is PTFE and the substrate to be rubbed is glass, in order to obtain an alignment film having uniform and excellent alignment characteristics, 0.01 cm / sec or more and 10 cm / sec or less is preferable, and 0.01 cm / sec or more. It is more preferably 5 cm / sec or less.

If the thickness of the alignment film is too thin, the dye film deposited on the alignment film will not be oriented, which is not preferable. On the other hand, if the thickness of the alignment film is too thick, absorption in the visible region becomes large, and the dye film as a polarizing element is not provided. It is not preferable because it lowers the transmittance.
Therefore, the thickness of the fluorine-based resin alignment film is preferably 1 n.
m to 1 μm, more preferably 1 nm to 0.2 μm, and particularly preferably 1 nm to 50 nm.

As the substrate for rubbing the alignment film, when the alignment dye film is used as it is as a polarizing element, a substrate that is transparent and smooth to visible light is used, and a glass or transparent electrode [(Indium-Tin Oxide)] is used. , In
₂ O ₃ , SnO _2, etc.] coated glass, polyethylene terephthalate, polycarbonate, etc. are exemplified.

When the produced alignment dye film is peeled off or transferred to another substrate for use, a metal plate or a metal roll can be used in addition to the above-mentioned base material. In this case, a material having a surface plated with a metal such as Ni can be used as the metal material.

However, since it is particularly preferable to rub the PTFE at a temperature of 300 ° C. or higher and 340 ° C. or lower in terms of the orientation of the obtained alignment dye film, in this case, the substrate on which the alignment film is rubbed is sufficiently heated to 300 ° C. or higher. It is preferable that it can withstand. As such a substrate, glass, transparent electrode [(Indium-Tin Oxide), In
₂ O ₃ , SnO _2, etc.] coated glass, metal plate, metal roll, etc. are exemplified. In the case of metallic materials, Ni on the surface
Although a material plated with a metal such as the above can also be used, it is preferable that the underlying material to be plated also sufficiently withstand heat of 300 ° C. or higher.

In the production of the alignment dye film by co-evaporation, any dye can be selected and combined from the dye groups represented by the general formulas (1) and (2). In combination, the blending ratio can be adjusted so as to obtain a desired color.

As a method for producing an alignment dye film by co-evaporation, there is a method of heating the dye at a temperature below the decomposition temperature to sublimate the dye and deposit it on a substrate provided with a fluorine resin alignment film. Therefore, the dye used is one that sublimes without being decomposed by the heat required for evaporation, but it is necessary to set the temperature of the evaporation source below the decomposition temperature of the dye. Although the specific temperature varies depending on the structure of the dye, it is preferably 400 ° C. or lower, more preferably 350 ° C. or lower from the general characteristics of polyazo dyes.

The degree of vacuum at the time of simultaneous vapor deposition can be lower than the atmospheric pressure, but in order to lower the heating temperature of the dye and to secure the distance between the evaporation source and the substrate, exhaust to the vacuum state as much as possible. Is preferred. Specifically, 10 ^-4 to
It is preferably rr or less, more preferably 10 ^-5 torr or less.

In the case of simultaneous vapor deposition, if the content of the dye represented by the general formula (2) is increased, a film having good polarization performance can be obtained. In this case, the content of the dye represented by the general formula (2) is preferably 50% or more and 100% or less, more preferably 60% or more and 100% or less, and particularly preferably 70% or more and 100% or less.

The optimum film thickness of the alignment dye film in the case of simultaneous vapor deposition needs to be adjusted depending on the dichroism of the dye, the molar extinction coefficient, and the degree of alignment of the dye in the film, but generally there is no pinhole. From the viewpoint of forming a uniform thin film, it is preferable that the thickness is thick, and to obtain a high degree of orientation, it is advantageous to make the thickness thin. On the other hand, if it is too thin, the single substance transmittance is too large, so that even if it is used as a polarizing element, sufficient performance cannot be obtained. Therefore, the film thickness is usually 10 nm or more and 1 μm or less, preferably 20 nm or more and 0.4 μm or less, more preferably 20 n.
m or more and 0.2 μm or less.

When the dye films are laminated to form one oriented dye film, the dye having the structure represented by the general formula (1) is laminated on the dye film having the structure represented by the general formula (2). The number of layers of the film is preferably small in terms of the orientation of the layers to be laminated. Generally, 1 to 4 layers can be used, but 1 to 3 layers are preferable, and 1 layer is more preferable.

In the case of stacking, the color tone of the dye film obtained by adjusting the film thickness of each dye film changes, so the film thickness is adjusted so as to obtain a desired color tone. However, since the film thickness of each dye film significantly affects the alignment of each dye, care must be taken not to impair the alignment. Specifically, it is preferable to keep the film thickness of the dye film having the structure represented by the general formula (2) within a certain range. It is preferable to adjust the dichroism of the dye and the molar extinction coefficient, but it is usually 10 nm or more and 0.4 μm or less, preferably 20 nm or more and 0.2 μm or less, and more preferably 20 nm or more and 0.2 μm or less.

The orientation dye film has a thickness of 400 nm to 80 nm.
It has at least one absorption peak in the range of 0 nm, and the dichroic ratio at at least one absorption peak wavelength is 40 or more, preferably 60 or more, more preferably 80 or more. Furthermore, it is preferable that the simple substance transmittance is 35% or more and 80% or less.

In the present invention, a film having another function may be laminated in addition to the alignment dye film which is indispensable when used as a polarizing element. For example, an epoxy resin or a photocurable resin may be provided as a protective film on the uppermost part. You may form a thin film, such as.

The alignment dye film of the present invention can be easily used as a polarizing element. The simplest method of use is to form the alignment dye film of the present invention on a fluororesin alignment film formed on a transparent substrate and directly use it as a polarizing element.

On the other hand, the present alignment dye film may be transferred to form a polarizing element. In this case, the manufacturing method is a method in which an alignment dye film is once formed on a base material, and then strongly pressed against another base material having higher adhesiveness, or transferred by pressing while heating, and an adhesive is applied to the surface. An example is a method of transferring by peeling off and attaching another base material attached with.

The structure of the liquid crystal display device of the present invention will be described.
To prepare a liquid crystal display device using the polarizing element made of the alignment dye film of the present invention, a polarizing element having a required size may be incorporated outside the liquid crystal cell. FIG. 1 shows a schematic view of an example of the liquid crystal display device of the present invention. In FIG. 1, 1 is a polarizing element of the present invention, 2 is a glass substrate, 3 is a transparent electrode, 4 is an insulating liquid crystal alignment control film, 5 is a liquid crystal layer, and 6 is a spacer. However, FIG. 1 shows only the minimum basic configuration required for the liquid crystal display device of the present invention, and other components may be included if necessary. Examples of such constituent elements include color filters, thin film transistors, antiglare films, and the like.

The transparent electrode 3 is coated on the glass substrate 2 on the liquid crystal layer side, and is usually ITO (Indium-Tin).
Oxide), In ₂ O ₃ , SnO _{2 and the} like are used. An insulating liquid crystal orientation control film is provided on the liquid crystal layer side 5 of the transparent electrode 3. At this time, when the liquid crystal alignment control film has a sufficient insulating property by itself, only the alignment film is necessary. However, if necessary, an insulating layer may be provided under the liquid crystal alignment control film, and the insulating property may be provided between them. It may be an alignment film.

As the liquid crystal alignment control film, known materials such as organic substances, inorganic substances, low molecular weight compounds and high molecular substances can be used. Examples of the polymer compound include polyimide,
Polyamide, polyamide imide, polyvinyl alcohol, polystyrene, polyester, polyester imide and various photoresists can be used as necessary.

When these polymer substances are used as a liquid crystal alignment control film, the surface of these films is rubbed in one direction by using gauze or acetate flocking cloth, if necessary, so-called rubbing. By performing the treatment, the alignment of the liquid crystal molecules can be further promoted. As the insulating film, for example, titanium oxide, aluminum oxide, zirconium oxide, silicon oxide, silicon nitride, or the like can be used.

As a method for forming these liquid crystal orientation control film and insulating film, an optimum method can be used according to the materials used, if necessary. For example, in the case of a polymer substance, the polymer substance or its precursor is
After dissolving these substances in a solvent that can dissolve them, they can be applied by a method such as a screen printing method, a spinner coating method, or a dipping method. In the case of inorganic substances, dipping method, vapor deposition method,
An oblique vapor deposition method or the like can be used. The thickness of these insulating alignment films is not particularly limited, but is preferably 1 nm to 2 μm, more preferably 2 nm to 1
00 nm.

These liquid crystal orientation control film 4 and transparent electrode 3
The two glass substrates 2 provided with are held at predetermined intervals via the spacer 6. As the spacer, beads, fibers, or a film-shaped insulating material having a predetermined diameter or thickness can be used. Specific examples thereof include silica, alumina, and polymer substances (polystyrene etc.). These spacers 6 can be sandwiched between two glass substrates 2 and the periphery thereof can be sealed with, for example, an epoxy adhesive or the like, and then liquid crystal can be enclosed.

Generally, a polarizing element is required outside each of the two glass substrates, so that two polarizing elements made of the alignment dye film of the present invention are installed. However, it is possible to use one of the two polarizing plates as another type of polarizing element depending on the purpose. In the case of a so-called guest-host type liquid crystal element in which a liquid crystal layer contains a dichroic dye, one polarizing element is omitted, and the other polarizing element is the polarizing element of the present invention. FIG. 1 illustrates the case where two polarizing elements are used.

A suitable lead wire is connected to the transparent electrode 3 and is connected to an external drive circuit. It is particularly useful to form a thin film transistor circuit (commonly called a TFT) formed on a liquid crystal cell as a part of the external drive circuit because a display element with extremely high performance can be obtained.

[0049]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. The dichroic ratio in the present invention means the absorbance (A1) of polarized light in a direction parallel to the alignment direction of the alignment dye film and the absorbance of polarized light in the direction orthogonal to the alignment direction of the alignment dye film at a specific wavelength. (A
2) was measured and determined by the following formula, and in particular, the value at the absorption peak wavelength was used. As the absorbance value, the alignment dye film alone was used after subtracting the absorption by the substrate.

## EQU1 ## Dichroic ratio = A1 / A2

Example 1 <Formation of Alignment Film> A PTFE alignment film was obtained by using the method described in US Pat. No. 5,180,470. Specifically, a glass substrate (2.5 cm x
8.0 cm), similarly heated length 2 cm diameter 1.
By pressing the side surface of the 0 cm PTFE cylinder and moving the substrate at a speed of 0.1 cm / sec, a PTFE alignment film having a width of 2.0 cm and a length of 7.0 cm was obtained.
At this time, the cylinder was pressed against the substrate with a pressure of 5 kgf. The contact area with the substrate was observed to be about 0.4 cm ² . <Formation of Dye Film> On the obtained PTFE alignment film, a polyazo dye D10 (manufactured by Japan Photosensitive Dye Company, trade name G2
05) and a polyazo dye D6 (manufactured by Japan Photosensitive Dye Company, trade name G232) were vapor-deposited at the same time. The degree of vacuum at the time of vapor deposition was 10 ⁻⁵ Torr or less, and the thickness of the obtained alignment dye film was about 100 nm. At this time, D10
The deposition rate was 3 times that of D6. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm was measured, there was an absorption peak at 510 nm. The dichroic ratio at the absorption peak was 40 or more. In addition, the obtained alignment dye film is provided on both sides of the TN type liquid crystal cell at 90.
When the TN type liquid crystal cell is twisted and driven, a good contrast is exhibited.

Example 2 <Formation of Dye Film> On the PTFE alignment film obtained in the same manner as in Example 1, a polyazo dye D10 (manufactured by Japan Photosensitive Dye Company, trade name G205) and a polyazo dye are used. D1 is vapor deposited at the same time. The degree of vacuum during vapor deposition is 10 ^-5 Torr
The thickness of the obtained alignment dye film is about 100 n or less.
m. At this time, the deposition rate of D10 is three times that of D1. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm is measured, there is an absorption peak at 510 nm. The dichroic ratio at the absorption peak is 40 or more. Also,
When the obtained alignment dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, good contrast is exhibited.

Example 3 <Formation of Dye Film> On the PTFE alignment film obtained in the same manner as in Example 1, a polyazo dye D10 (manufactured by Japan Photosensitive Dye Company, trade name G205) and a polyazo dye D7 were formed. At the same time. The degree of vacuum at the time of vapor deposition is 10 ⁻⁵ Torr or less, and the thickness of the obtained composite dye film is about 50 nm. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm is measured, there is an absorption peak at 495 nm. The dichroic ratio at the absorption peak is 40 or more. Also,
When the obtained alignment dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, good contrast is exhibited.

Example 4 <Formation of Dye Film> On the PTFE alignment film obtained in the same manner as in Example 1, a polyazo dye D10 (manufactured by Japan Photosensitive Dye Company, trade name G205) and a polyazo dye were used. Simultaneously vapor-deposit D9. The degree of vacuum during vapor deposition is 10 ^-5 Tor
The thickness of the resulting alignment dye film is about 100 or less.
nm. At this time, the vapor deposition rate of D10 is three times that of D9.

<Evaluation of dichroic ratio> From 300 nm to 700
When the polarized light absorbance in the nm range is measured, there is an absorption peak at 510 nm. The dichroic ratio at the absorption peak is 40 or more. Further, when the obtained alignment dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, good contrast is exhibited.

Example 5 <Formation of dye film> On the PTFE alignment film obtained in the same manner as in Example 1, D10 (manufactured by Japan Photosensitive Dye Company, trade name G20) was used.
5) was vapor-deposited. The degree of vacuum during vapor deposition is 10 ^-5 Torr
The thickness of the obtained dye film was about 100 nm. Next, on this film, D6
2) was vapor-deposited. The degree of vacuum during vapor deposition is 10 ^-5 Torr
The thickness of the obtained dye film was about 50 nm. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm is measured, there is an absorption peak at 510 nm. The dichroic ratio at the absorption peak was 40 or more. When the obtained dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, colorless and red color changes are exhibited, and good contrast is exhibited.

Example 6 <Formation of Dye Film> D10 (manufactured by Nippon Senshi Dye Co., Ltd., trade name G20) was formed on a PTFE alignment film obtained in the same manner as in Example 1.
5) is vapor-deposited. The degree of vacuum during vapor deposition is 10 ^-5 Torr
And the thickness of the resulting dye film is about 50 nm. Next, D1 is vapor-deposited on this film. The degree of vacuum during vapor deposition is 10 ⁻⁵ Torr or less, and the thickness of the dye film obtained is about 50 nm. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm is measured, there is an absorption peak at 495 nm. The dichroic ratio at the absorption peak is 40 or more. Also,
When the obtained dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, it shows colorless and red changes and shows a good contrast.

Example 7 <Formation of dye film> On the PTFE alignment film obtained in the same manner as in Example 1, D10 (manufactured by Japan Photosensitive Dye Company, trade name G20) was used.
5) is vapor-deposited. The degree of vacuum during vapor deposition is 10 ^-5 Torr
The thickness of the obtained dye film is about 100 nm. Next, D7 is vapor-deposited on this film. The degree of vacuum during vapor deposition is 10 ⁻⁵ Torr or less, and the thickness of the dye film obtained is about 50 nm. <Evaluation of dichroic ratio> When the polarized light absorbance in the range of 300 nm to 700 nm is measured, there is an absorption peak at 510 nm. The dichroic ratio at the absorption peak is 40 or more. Also,
When the obtained dye film is twisted by 90 ° on both sides of the TN type liquid crystal cell and the TN type liquid crystal cell is driven, it shows colorless and red changes and shows a good contrast.

Example 8 <Formation of Dye Film> D10 (manufactured by Nippon Senshi Dye Co., Ltd., trade name G20) was formed on the PTFE alignment film obtained in the same manner as in Example 1.
5) is vapor-deposited. The degree of vacuum during vapor deposition is 10 ^-5 Torr
And the thickness of the resulting dye film is about 50 nm. Next, D8 is vapor-deposited on this film. The degree of vacuum during vapor deposition is 10 ⁻⁵ Torr or less, and the thickness of the dye film obtained is about 50 nm.

<Evaluation of dichroic ratio> 300 nm to 700 n
When the polarized light absorbance in the range of m is measured, there is an absorption peak at 495 nm. The dichroic ratio at the absorption peak is 40 or more. In addition, the obtained dye film is provided on both sides of the TN type liquid crystal cell.
When the TN type liquid crystal cell is arranged by twisting at 0 °, a colorless and red change is exhibited and a good contrast is exhibited.

[0060]

The alignment dye film of the present invention is an alignment dye film of a plurality of types of dyes and having a high dichroic ratio, which can be easily prepared by the production method of the present invention, and a polarizing element using the same can be obtained. When used in a liquid crystal display device, a high-contrast image can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a liquid crystal display device of the present invention.

[Explanation of symbols]

 1 ... Polarizing element 2 ... Glass substrate 3 ... Transparent electrode 4 ... Insulating liquid crystal orientation control film 5 ... Liquid crystal layer 6 ... Spacer

Claims (8)

[Claims] 1. A thin film comprising at least one polyazo dye material having a structure represented by the general formula (1) and at least one polyazo dye material having a structure represented by the general formula (2). And these dyes are uniaxially oriented, the thin film has at least one absorption peak in the range of 400 nm to 800 nm, the thickness of the thin film is 10 nm or more and 1 μm or less, and the dichroism of at least one absorption peak wavelength is An orientation dye film having a sex ratio of 40 or more. Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃ (1) (In the formula, Ar ₁ and Ar ₃ are each independently selected from the following groups. Here, X ₁ and X ₂ are each independently selected from the following groups, and m is an integer of 0-8. Embedded image Ar ₂ is selected from the following groups. [Chemical 4] Embedded image (In the formula, X ₁ has the same definition as above. Further, Ar ₄
Is selected from the following groups. [Chemical 6] 2. A thin film of the polyazo dye material having the structure represented by the general formula (1) is formed on the thin film of the polyazo dye material having the structure represented by the general formula (2). A laminated thin film in which these dyes are uniaxially oriented, the thin film has at least one absorption peak in the range of 400 nm to 800 nm, and the thickness of the thin film is 10 nm or more and 1 μm or less.
m or less, and at least one of the absorption peak wavelengths has a dichroic ratio of 40 or more. 3. At least one polyazo dye material having a structure represented by the general formula (2) according to claim 1, and at least one polyazo dye material having a structure represented by the general formula (1). 2. The method for producing an alignment dye film according to claim 1, wherein is simultaneously vapor-deposited from a gas phase on a substrate having a fluorine-based resin alignment film on the surface. 4. A film of a polyazo dye material having a structure represented by the general formula (2) according to claim 1 is vapor-deposited on a substrate having a fluorine resin alignment film on the surface thereof to obtain a film. A film of a polyazo dye material having a structure represented by the general formula (1) is vapor-deposited on the vapor-deposited film thus obtained.
A method for producing an alignment dye film as described above. 5. A polarizing element comprising a polymer film having the alignment dye film according to claim 1 on its surface, or a glass plate or a glass plate having a transparent electrode. 6. A polarizing element comprising a polymer film having the alignment dye film according to claim 2 on its surface, or a glass plate or a glass plate having a transparent electrode. 7. A substrate having electrodes, which has a positive dielectric anisotropy and is substantially horizontal when no voltage is applied, and whose helical axis is perpendicular to the substrate between 90 ° and 270 °. 7. A liquid crystal display device comprising a liquid crystal cell comprising a liquid crystal layer twist-aligned with the polarizing element according to claim 5 disposed outside the liquid crystal cell. 8. A substrate having an electrode, which has a positive dielectric anisotropy, is substantially horizontal when no voltage is applied, and the spiral axis is between 90 ° and 270 ° in a direction perpendicular to the substrate. 7. A liquid crystal display device comprising a liquid crystal cell comprising a liquid crystal layer which is twisted and aligned, and the polarizing element according to claim 6 being arranged outside the liquid crystal cell.