KR20160065072A - Method for manufacturing anisotropic dye film, anisotropic dye film manufactured by said manufacturing method, optical element including said anisotropic dye film, and liquid crystal element including said optical element - Google Patents

Abstract

An object of the present invention is to provide a die having a lip having a specific shape capable of obtaining a uniform coating film by suppressing occurrence of film thickness irregularities or coating streaks when applying an anisotropic dye film forming composition. A method of producing an anisotropic dye film comprising a step of applying a composition for forming an anisotropic dye film on a substrate using a die coater, the die coater comprising: a front lip located on a side of the die coater in the advancing direction; Wherein a length of a lower end surface of the front lip along the advancing direction is A and a length of a lower end surface of the lower lip of the rear lip is equal to a length And the length along the direction is B, A> B, and the viscosity of the composition for anisotropic dye film formation is 10 cP or more.

Description

TECHNICAL FIELD [0001] The present invention relates to an anisotropic dye film, an anisotropic dye film produced by the method, an optical element including the anisotropic dye film, and a liquid crystal device including the optical element. BACKGROUND ART [0002] METHOD, OPTICAL ELEMENT INCLUDING SAID ANISOTROPIC DYE FILM, AND LIQUID CRYSTAL ELEMENT INCLUDING SAID OPTICAL ELEMENT}

The present invention relates to a method for producing an anisotropic dye film using a die, an anisotropic dye film produced by the method, an optical element including the anisotropic dye film, and a liquid crystal device including the optical element.

BACKGROUND ART In a liquid crystal display (LCD), a linear polarizing film or a circular polarizing film is used for controlling optical rotation and birefringence in display. In addition, a circular polarizing film is used to prevent reflection of external light, even in a light-emitting display device such as an organic EL display or an input / output device such as a touch panel.

Examples of techniques for forming these polarizing films (hereinafter also referred to as " anisotropic dye films ") include a method in which a polymer film such as polyvinyl alcohol is impregnated with a dichroic substance (iodine or dye) Quot;), and a method in which a liquid crystal dye is coated (hereinafter also referred to as " coating method "). In the stretching method, a complicated process as described above is required for forming a polarizing film. In order to use the polarizing film as an optical element (polarizing element) of an LCD, a step of bonding the polarizing film to the glass substrate is required. In addition, since it is necessary not only to manufacture a polarizing film but also a technique of an adhesive or a bonding process, it is generally expensive. On the other hand, in the coating method, since only the step of directly applying a liquid crystal dye to a glass substrate or the like is possible, it is possible to easily thin the polarizing film and is generally low in cost.

As a coating method, there is disclosed a method of continuously producing a polarizing film by using a free span method, for example, for the purpose of suppressing occurrence of film thickness irregularity, coating striations, and coating speed (for example, , See Patent Document 1). In order to improve the dichroism ratio of the polarizing film and the uniformity of the film, it has been disclosed that the viscosity of the coating liquid is made to be a specific value or less (see Patent Document 2). Further, for the purpose of improving the dichroic ratio of the polarizing film, it has been disclosed that the coating speed is increased (see Patent Document 3).

On the other hand, for the purpose of forming a coating film having a uniform film thickness with no appearance defects by coating a coating liquid having a high viscosity containing a polymer on a base film, the atmosphere on the application front side in the die coater is reduced (See Patent Document 4).

As a color filter application, it has been disclosed that a die coater having a specific shape is used for easy ejection onto a rigid substrate such as glass and for obtaining a uniform film thickness (see Patent Document 5) .

Japanese Patent Application Laid-Open No. 2007-61755 Japanese Patent Application Laid-Open No. 2007-93938 International publication 2009/022494 pamphlet Japanese Patent Application Laid-Open No. 2008-714 Japanese Patent Application Laid-Open No. 9-131559

However, in the above Patent Documents 1 to 5, for the purpose of improving the polarization performance and the like of the anisotropic dye film, the shape of the die used for applying the composition for forming an anisotropic dye film by using a die coater, The preparation method such as the viscosity of the composition has not been studied.

As methods for improving the polarization performance of the polarizing film, the methods of Patent Documents 2 and 3 are exemplified, but the improvement of the polarization performance is still insufficient. In addition, the inventors of the present invention have found that when the coating speed is increased as in Patent Document 3, liquid breakage tends to occur and coating defects tend to occur.

On the other hand, Patent Document 4 discloses a coating method using a die coater, and Patent Document 5 discloses a shape of a die. However, since it is disclosed as a suitable method other than the use of the anisotropic dye film, the problems peculiar to the anisotropic dye film have not been studied, and it is difficult to devote the patent documents 4 and 5 to the production method of the anisotropic dye film. In addition, the methods disclosed in Patent Documents 1 and 4 can be used only for the continuous coating method, and thus can not be applied to the sheet method.

The present invention relates to a die having a lip having a specific shape and capable of obtaining a uniform coating film with excellent polarizing performance and suppressing occurrence of film thickness irregularities or coating streaks when the composition for forming an anisotropic dye film is applied, It is another object of the present invention to provide a method for producing an anisotropic dye film using a specific composition for forming an anisotropic dye film.

In order to obtain an anisotropic dye film by the wet film formation method described later, it is necessary to align the dye column associated with the dye contained in the composition for forming an anisotropic dye film. However, due to the unique properties of the anisotropic dye film-forming composition such as fluidity and orientation, it is not possible to obtain a high flow orientation property of an anisotropic dye by simply using a die coater.

Generally, when a thin film is applied using a die coater, the length along the advancing direction on the lower end face of the rear lip (hereinafter sometimes referred to as the downstream side lip) It is known that the shearing force with respect to the substrate interface is strengthened by making the length along the advancing direction on the lower end face of the front lip located on the advancing direction side (hereinafter sometimes referred to as the upstream lips) longer. On the other hand, it is known that, in a place where the liquid of the rear lip is high at the time of application (hereinafter, the place where the liquid of the rear or front lip is high is sometimes referred to as a coating bit), vortex due to the circulating flow is generated.

According to the study by the present inventor, the vortex caused by the circulating flow disturbs the orientation of the composition for forming an anisotropic dye film due to the shearing force with the substrate interface. Therefore, even if the length of the rear lip is increased, the orientation by the shearing force is not promoted, But rather tended to be inhibited.

On the other hand, in the case of coating using a die coater, the coating liquid is uniformly filled in the die slot at the time of application of the coating, and a liquid having a proper amount between the die lip portion and the coated surface causes coating defects such as unevenness of coating thickness, It is important not to generate. In particular, in the case of the pine needle method, since all substrates to be coated have a coating start portion, adjustment of the liquid amount of the die coater and the coating liquid at the start of coating becomes important.

The inventors of the present invention have further studied based on the above findings and have studied a method for obtaining a uniform anisotropic dye film with high orientation property and excellent polarizing performance and suppressing occurrence of unevenness of film thickness or occurrence of coating striations , A die having a specific shape used for applying the composition for forming an anisotropic dye film and a composition for forming a specific anisotropic dye film can be used to accomplish the present invention.

A first embodiment of the present invention is a method of producing an anisotropic dye film comprising a step of applying a composition for forming an anisotropic dye film on a substrate using a die coater, Wherein the front lip has a front lip and a rear lip located opposite to the traveling direction, both ribs each having a lip lower end face opposing the substrate, and a length along the advancing direction of the lower end face of the front lip is A, And the length of the lower end of the rear lip along the traveling direction is represented by B, A> B, and the viscosity of the composition for forming an anisotropic dye film is 10 cP or more.

In the above manufacturing method, the B is preferably 0.03 mm or more and 2 mm or less.

Further, in the above production method, it is preferable that the composition for forming an anisotropic dye film contains an azo compound and a solvent.

A second embodiment of the present invention is an anisotropic dye film obtained by the above production method.

A third embodiment of the present invention is an optical element including the anisotropic dye film.

A fourth embodiment of the present invention is a liquid crystal element including the optical element.

An anisotropic dye film excellent in polarization performance can be obtained by the production method of the present invention. In addition, when applying the composition for forming an anisotropic dye film, it is possible to obtain a uniform anisotropic dye film by suppressing unevenness of film thickness and occurrence of coating streaks.

1 is an enlarged view of a die lip portion.
2 is a schematic view showing a specific embodiment of a die coater.

Hereinafter, the present invention will be described in detail with reference to specific embodiments thereof, but it goes without saying that the present invention is not limited to the specific embodiments illustrated.

A first embodiment of the present invention is a method of producing an anisotropic dye film comprising a step of applying a composition for forming an anisotropic dye film on a substrate using a die coater, Wherein the front lip has a front lip and a rear lip located opposite to the traveling direction, both ribs each having a lip lower end face opposing the substrate, and a length along the advancing direction of the lower end face of the front lip is A, And the length of the lower end of the rear lip along the traveling direction is denoted by B, A> B, and the viscosity of the composition for anisotropic dye film formation is 10 cP or more.

The reason why a uniform anisotropic dye film can be obtained by having a high orientation property and excellent polarizing performance and suppressing the occurrence of unevenness of film thickness or coating striations by the production method related to this embodiment is not clear, do.

When the length A along the advancing direction on the lower end face of the front lip is A > B with respect to the length B along the advancing direction on the lower end face of the rear lip, the vortex generated in the application bit of the rear lip is reduced do. On the other hand, the composition for forming an anisotropic dye film which flows out from the die slot portion is increased from the slot width (for example, 50 mu m or more) to the coating film thickness (for example, several mu m) of the composition for forming an anisotropic dye film It accepts a large elongation at the time. Further, when the viscosity of the composition for forming an anisotropic dye film is not less than a specific value, the stress due to this elongational deformation effectively works. That is, a good alignment state can be obtained even if the shearing force with the substrate interface is not made strong.

In addition, since A > B, the application bit of the rear lip becomes an appropriate amount and the application bit of the rear lip becomes an appropriate amount with respect to the application bit of the front lip, The application liquid applied to the application surface can be maintained in an appropriate amount. By virtue of this property, when a composition for forming an anisotropic dye film is applied to a substrate, it is possible to suppress the occurrence of unevenness in film thickness and occurrence of coating streaks, thereby obtaining a uniform coating film.

(Anisotropic pigment film)

The anisotropic dye film is an optical film having anisotropy in electromagnetism in any two directions selected from the three directions in total, in the thickness direction of the film and the two-dimensional coordinate system in two arbitrary orthogonal planes. Electromagnetic properties include optical properties such as absorption and refraction, electrical properties such as resistance and capacitance, and the like. Examples of the film having optical anisotropy such as absorption and refraction include a linearly polarizing layer, a circularly polarizing layer, a retardation film, and a conductive anisotropic film. The anisotropic dye film in the present embodiment can be preferably used as a retardation film and a conductive anisotropic film in addition to the anisotropic dye film.

The transmittance in the visible light wavelength region of the anisotropic dye film obtained by this embodiment is preferably 25% or more. More preferably 35% or more, and particularly preferably 40% or more. The upper limit is not particularly limited and may be an upper limit according to the use. For example, when the degree of polarization is high, it is preferably 50% or less. And is useful as an optical element for a liquid crystal display used for color display.

When the anisotropic dye film obtained by this embodiment is used as a polarizing element, the alignment characteristic of the anisotropic dye film can be expressed using a dichroic ratio. The dichroic ratio functions as a polarizing element when the dichroic ratio is 8 or more, preferably 25 or more, more preferably 30 or more, and particularly preferably 35 or more. The higher the dichroic ratio is, the better, and there is no upper limit. Since the dichroic ratio is a specific value or more, it is useful as an optical element, particularly a polarizing element described below.

In the present embodiment, the dichroic ratio (D) is expressed by the following formula when the anisotropic dye is uniformly oriented.

D = Less / Month

Here, Az is the absorbance observed when the polarization direction of the light incident on the anisotropic dye film is parallel to the alignment direction of the anisotropic dye, and Ay is the absorbance observed when the polarization direction is perpendicular. Any of the wavelengths may be selected depending on the purpose without particular limitation if each of the absorbances having the same wavelength is used. In the case of indicating the degree of orientation of the anisotropic dye film, it is preferable to use a value at the maximum absorption wavelength of the anisotropic dye film Do.

When the anisotropic dye film obtained by this embodiment is used as a polarizing element, the orientation characteristic of the anisotropic dye film can be indicated by the polarization. The polarization degree is preferably 36% or more, and usually 95% or more, preferably 98% or more, and more preferably 99% or more. The higher the degree of polarization, the better, and the maximum value is 100%. Since the degree of polarization is equal to or higher than the value shown in the above, it is useful as the following optical element, particularly a polarizing element.

Any of the wavelengths may be selected depending on the purpose without particular limitation if the transmittance of each wavelength is the same, but when the degree of orientation of the anisotropic dye film is indicated, it is preferable to use a value at the maximum absorption wavelength of the anisotropic dye film Do.

Specifically, according to JIS Z 8701, the visibility-corrected transmittance of polarized light in the absorption axis direction of the anisotropic dye film and the polarity of the polarized light in the direction of the polarization axis of the anisotropic dye film are measured from the stimulation value Y in the D65 light source 2 ° field of Tz and Ty The transmittance is calculated, and the degree of polarization can be calculated by the following formula.

The degree of polarization P (%) = {(Yy - Yz) / (Yy + Yz)} ^1/2 100

Yz: Visible sensitivity for polarized light in the absorption axis direction of the anisotropic dye film Transmittance

Yy: Visibility-corrected transmittance of polarized light in the polarization axis direction of the anisotropic dye film

The film thickness of the anisotropic dye film obtained by this embodiment is preferably 10 nm or more, and more preferably 50 nm or more as a dry film thickness. On the other hand, it is preferably 30 占 퐉 or less, and more preferably 1 占 퐉 or less. The film thickness of the anisotropic coloring film is in an appropriate range, so that uniform orientation of molecules and uniform film thickness can be obtained in the film.

In this embodiment, the anisotropic dye film may be subjected to an insolubilization treatment. Insolubilization means a treatment process in which the solubility of a compound in an anisotropic dye film is lowered to thereby control the elution of the compound from the anisotropic dye film to enhance the stability of the film. Specifically, for example, a process in which ions of a smaller valence are replaced with ions of a larger valence (for example, a monovalent ion is replaced with a multivalent ion), a process of substituting an ionic group with an organic molecule or a polymer . As such a treatment method, for example, known methods such as those described in Hosoda Utsuka, " Theoretical Preparation and Dyeing Chemistry " (Kibo, 1957, pages 435 to 437) can be used.

Preferably, the obtained anisotropic dye film is treated by the method described in Japanese Patent Application Laid-Open No. 2007-241267 or the like to obtain an anisotropic dye film insoluble in water, from the viewpoints of easiness in the post-process and durability.

(Composition for forming anisotropic dye film)

The composition for forming an anisotropic dye film used for forming the anisotropic dye film is not particularly limited as long as it exhibits the above-mentioned anisotropy when the film is formed and has the properties described later. In this embodiment, in order to form an anisotropic dye film on a substrate by coating, a composition for forming an anisotropic dye film containing such an anisotropic material and a solvent is used.

(Viscosity of composition for forming anisotropic dye film)

The viscosity of the composition for anisotropic dye film formation in this embodiment is not particularly limited as long as it is 10 cP or more. The viscosity of the composition for forming an anisotropic dye film can be suitably adjusted so that the polarizing performance of the anisotropic dye film obtained in accordance with the characteristics of the contained dye, solvent, additives, etc. becomes a desired value.

The viscosity of the composition for forming an anisotropic dye film in this embodiment is usually 10 cP or more, preferably 15 cP or more, more preferably 20 cP or more, particularly preferably 25 cP or more. It is preferably 100 cP or less, more preferably 80 cP or less, particularly preferably 60 cP or less. Within this range, stress due to elongation deformation of the composition for forming an anisotropic dye when a specific die coater is used effectively acts, and an anisotropic dye film having high orientation property and excellent polarization performance can be obtained .

The measurement viscosity was measured using a rheometer VAR-50 (manufactured by REOLOGICA), a parallel plate (diameter 40 mm, gap 0.8 mm), and the measurement temperature was set to 25 ° C and pre-shearing was performed at a shear rate of 1000 s ^-1 for 5 seconds After shearing, the shear rate is changed from 1000 s ^-1 to 100 s ^-1 for 180 seconds, which indicates the value in shear rate sweep measurement.

The method for adjusting the viscosity of the composition for forming an anisotropic dye film in the present embodiment is not particularly limited and can be adjusted depending on the addition amount and combination of coloring matters, solvents, additives, and the like.

The pH of the composition for anisotropic dye film formation in this embodiment is preferably less than 7 from the viewpoint of improving the wettability of the substrate surface. The application step may be performed in a sheet-like manner or in a roll-to-roll manner, but the present embodiment is preferably applied when the sheet-like method is employed as described above.

The composition for forming an anisotropic dye film is preferably a liquid crystal phase as a composition from the viewpoint of forming a highly anisotropic dye film formed after the solvent is evaporated. The state of the liquid crystal phase in this embodiment refers to the state described on pages 1 to 16 of " Fundamentals and Application of Liquid Crystals " (Shoichi Matsumoto, Ichiro Tsunoda, 1991). Particularly, the nematic phase described on page 3 is preferable.

The material may be any one capable of forming an anisotropic dye film, and may include a dye or a transparent material.

 The composition for forming an anisotropic dye film may contain a binder resin, a monomer, a curing agent, and an additive, if necessary. The composition for forming the anisotropic dye film may be in a solution state or in a gel state. The composition for forming an anisotropic coloring matter film may be in a state in which a dye or the like is dissolved or dispersed in a solvent.

(Coloring matter)

For dyes, a dichroic dye is usually used. Examples of the dichroic dye include a dye that expresses a liquid crystal and a dye that expresses a thermotropic liquid crystal, and any of them may be used.

In this embodiment, the dye is preferably a dye having a liquid crystal phase for orientation control. Here, the dye having a liquid crystal phase means a dye exhibiting lyotropic liquid crystallinity in a solvent. When the composition is used as an anisotropic dye film-forming composition, it may or may not express a liquid crystal phase. However, Phase state.

The coloring matter is preferably soluble in water or an organic solvent, and is preferably water-soluble, in order to provide a composition for forming an anisotropic coloring film to a liquid crystal phase and to be provided in a wet film forming method to be described later. More preferred is a compound having an inorganic value smaller than an organic value as defined in " Organic Concept Diagram - Basis and Application " (Kodama Yoshio, Sankyo Publ., 1984). The molecular weight is preferably 200 or more, more preferably 300 or more, more preferably 1,500 or less, and particularly preferably 1,200 or less, in a free state without taking a salt form. Further, the water-solubility means that the compound is usually dissolved in water at 0.1% by mass or more, preferably 1% by mass or more at room temperature.

In the present embodiment, only one kind of dye may be used, or two or more kinds of dye may be used in combination. In the case of combining two or more kinds, at least one dye may be a dye that expresses a liquid crystal phase so that the composition for forming an anisotropic dye film can express a liquid crystal phase.

Specific examples of the colorant include an azo pigment, a stilbene pigment, a cyanine pigment, a phthalocyanine pigment, and a condensed polycyclic pigment (perylene, oxazine).

For example, JP-A-2006-079030, JP-A-2010-168570, JP-A-2007-302807, JP-A-2008-081700, JP-A-09-23012, Japanese Unexamined Patent Application Publication No. 2007-272211, Japanese Unexamined Patent Application Publication No. 2007-186428, Japanese Unexamined Patent Application Publication No. 2008-69300, Japanese Unexamined Patent Publication No. 2009-169341, Japanese Unexamined Patent Application Publication No. 2009-161722, Japanese Unexamined Patent Application Publication No. 2009 -173849, JP-A-2010-039154, JP-A-2010-180314, JP-A-2010-266769, JP-A-2011-012152, JP-A-2011-016922, JP- Japanese Unexamined Patent Application Publication No. 2001-150538, Japanese Unexamined Patent Application Publication No. 2006-48078, and the like are disclosed in Japanese Unexamined Patent Publication No. 2001-100059, Japanese Unexamined Patent Application Publication No. 2011-141331, Japanese Unexamined Patent Publication No. Hei 08-511109, Japanese Unexamined Patent Publication No. 2001-504238 .

Among these dyes, an azo dye is preferable because the viscosity of the composition for forming an anisotropic dye film can be easily controlled within the range of this embodiment and a high molecular arrangement can be obtained in the anisotropic dye film. The azo-based dye means a dye having at least one azo group. The number of azo groups in one molecule is preferably 2 or more, and is preferably 6 or less. Further, it is more preferably 4 or less. With a suitable number of azo groups, a color tone having a low wavelength dispersibility and absorption in a wide region in a visible region is obtained, and the production tends to be easy.

Among the azo dyes, each of the disazo, trisazo and tetraquisazo dyes having a structure of the following formula (A) in the form of a free acid has a low wavelength dispersibility and a color tone having absorption in the wide region in the visible region is obtained .

[Chemical Formula 1]

In the formula (A), E ¹ represents an arbitrary organic group, R ²⁰ and R ²¹ each independently represent a hydrogen atom, an alkyl group which may have a substituent or a phenyl group which may have a substituent, and p and q represent Independently represents an integer of 1 or more and 5 or less, and p + q represents 2 or more and 6 or less.

Among the structures of the above formula (A), the disazo, trisazo and tetrakisazato dyes having the structure of the following formula (B) in the form of the free acid have low wavelength dispersibility and absorption in the wide region in the visible region Is obtained, and a high dichroism is obtained when an anisotropic dye film is used.

(2)

In the above formula (B), E ² represents an arbitrary organic group, and R ²² and R ²³ each independently represent a hydrogen atom, an alkyl group which may have a substituent or a phenyl group which may have a substituent.

The dye in this embodiment may be used in the form of a free acid, or a part of the acid group may take a salt form. In addition, a salt dye dye and a free acid dye dye may be mixed. When obtained in a salt form at the time of production, it may be used as it is or may be converted into a desired salt form. As the exchange method of the salt type, known methods can be used arbitrarily. For example, the following methods can be mentioned.

1) A strong acid such as hydrochloric acid is added to an aqueous solution of a dye obtained in a salt form, the pigment is acid-precipitated in the form of a free acid, and then an alkali solution (for example, an aqueous solution of lithium hydroxide) How to neutralize and exchange salts.

2) A method in which a large excess of a neutral salt (for example, lithium chloride) having a desired counter ion is added to an aqueous solution of a dye obtained in a salt form, and salt exchange is performed in the form of a salting-out cake.

3) An aqueous solution of the dye obtained in a salt form is treated with a strongly acidic cation exchange resin, the dye is calcined in the form of the free acid, and the dye acid group is neutralized with an alkali solution having a desired counter ion (for example, an aqueous solution of lithium hydroxide) Method of salt exchange.

4) A method in which an aqueous solution of a dye obtained in a salt form is caused to act on a strongly acidic cation-exchange resin treated with an alkali solution (for example, an aqueous solution of lithium hydroxide) having a desired counter ion in advance and subjected to salt exchange.

Whether the acidic group of the dye of the present embodiment has a free acid form or a salt form depends on the pKa of the dye and the pH of the aqueous solution of the dye.

Examples of the salt form include salts of alkali metals such as Na, Li and K, salts of ammonium which may be substituted with an alkyl group or a hydroxyalkyl group, and salts of organic amines. Examples of the organic amine include a lower alkylamine having 1 to 6 carbon atoms, a hydroxy-substituted lower alkylamine having 1 to 6 carbon atoms, and a carboxy-substituted lower alkylamine having 1 to 6 carbon atoms. In the case of these salt forms, the kind thereof is not limited to one kind but may be mixed plural kinds.

 The dye may be used alone, but two or more of these dyes may be used in combination, or a dye other than the above exemplified dye may be blended to such an extent that the orientation is not deteriorated. Thus, an anisotropic dye film having various colors can be produced.

Examples of formulating dyes for mixing other dyes include CI Direct Yellow 12, CI Direct Yellow 34, CI Direct Yellow 86, CI Direct Yellow 142, CI Direct Yellow 132, CI Acid Yellow 25, CI Direct Orange 39, CI Direct Orange 72, CI Direct Orange 79, CI Acid Orange 28, CI Direct Red 39, CI Direct Red 79, CI Direct Red 81, CI Direct Red 83, CI Direct Red 89, Direct Violet 35, CI Direct Violet 48, CI Direct Violet 57, CI Direct Blue 1, CI Direct Blue 67, CI Direct Blue 83, CI Direct Blue 90, CI Direct Green 42, CI Direct Green 51, .

(menstruum)

The solvent is not particularly limited as long as it dissolves or disperses the compound. Particularly, water, a water-miscible organic solvent, or a mixture thereof is suitable, since the coloring matter easily forms a state of association with the lyotropic liquid crystal in the solvent. Specific examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and glycerin, glycols such as ethylene glycol and diethylene glycol, cellosolve such as methyl cellosolve and ethyl cellosolve Or a mixed solvent of two or more kinds.

Above all, water, methanol and ethanol are preferable, and water is particularly preferable because it accelerates association of highly organic parts such as aromatic rings of dyes.

The concentration of the dye in the composition for forming an anisotropic dye film may vary depending on the film forming conditions, but is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and preferably 50 mass% or less, Is not more than 30% by mass. If the concentration of the dye is excessively low, the association of the dye in the composition becomes insufficient, and anisotropy such as a sufficient dichroic ratio can not be obtained in the obtained anisotropic dye film. If the dye is excessively high, viscosity becomes high and uniform application of the thin film becomes difficult, There are cases where an anisotropic material is precipitated in the composition for forming an anisotropic dye film.

Additives such as a surfactant, a leveling agent, a coupling agent, and a pH adjuster may be added to the composition for forming an anisotropic dye film, if necessary. The wettability and the coatability can be improved by the additive.

As the surfactant, any of anionic, cationic and nonionic surfactants can be used. The concentration of the additive is not particularly limited, but is sufficient to obtain the effect to be added, and is an amount that does not inhibit the orientation of the molecule. The concentration in the composition for forming an anisotropic dye film is usually 0.01 mass% or more, By mass or more is more preferable. The content is preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less.

For the purpose of suppressing instability such as salt formation and agglomeration of an anisotropic material in a composition for forming an anisotropic dye film, it is preferable to add a known pH / adjusting agent such as an acid / alkali to the mixture of constituents of the composition for anisotropic dye film It may be added before, after, or during mixing. As additives other than the above, known additives described in "Additive for Coating", edited by J. Bieleman, Willey-VCH (2000) may be used.

(Board)

The substrate in the present embodiment is not particularly limited, but is preferably a substrate having good surface properties, contact angle characteristics, and absorption characteristics. Examples of the substrate for forming such a substrate include inorganic materials such as glass; A polymer material such as a triacetate resin, an acrylic resin, a polyester resin, a polycarbonate resin, a polyethylene terephthalate resin, a triacetylcellulose resin, a norbornene resin, a cyclic polyolefin resin or a urethane resin . These may be used singly or in combination of two or more. In particular, the substrate is preferably a substrate including a polymer substrate containing a polymer material.

The absorption rate of the substrate is usually 5% or less, preferably 3% or less, and more preferably 1% or less. When the water absorption rate is excessively large, when the film of an anisotropic material such as a coloring matter is formed by a coating method, the substrate is absorbed by moisture, and the substrate is warped, and coating defects are likely to occur. Further, after the anisotropic dye film is formed by the coating method, the substrate may be swollen to cause optical defects.

The "water absorption rate" in the present embodiment is a value obtained by measuring the rate of change in weight when immersed in water at 23 ° C for 4 hours using the test method of ASTM D570.

From the viewpoint of better orienting the anisotropic material such as coloring matter contained in the anisotropic coloring film in a predetermined direction on the surface of the substrate on which the anisotropic dye film is formed, the alignment treatment layer and the like can be formed in advance. The method of forming the alignment treatment layer can be performed according to a known method described in " Liquid Crystal Handbook " (Maruzen Co., Ltd., published on October 30, 2000), pages 226 to 239 and the like.

The shape of the substrate may be a film of a certain size (a leaf) or a continuous film (roll). The film thickness of the substrate is usually 0.01 mm or more, preferably 0.02 mm or more, and usually 3 mm or less, preferably 2 mm or less.

The total light transmittance of the substrate is usually 80% or more, preferably 85% or more, and more preferably 90% or more. The " total light transmittance " in the present embodiment is measured using an integral color acceptance measuring apparatus, and is a sum of the diffused transmitted light and the parallel light transmitting light.

(die)

Fig. 1 is an enlarged view of a die lip as a tip end portion of the die 101, and is a view showing a cut face in the direction a-a 'of the die 101 shown in Fig. In Fig. 1, application is performed toward the direction of the arrow D by the die 101, and the advancing direction side is the front (upstream). The die 101 in this embodiment includes a front-side die 101a and a rear-side die 101b. The inner surfaces of the front side die 101a and the rear side die 101b are opposed to each other with a predetermined gap therebetween to form a slot 106 through which the anisotropic dye film forming composition 103 is discharged.

As described above, the die 101 in this embodiment has, at its tip end portion, a front lip 102a positioned on the advancing direction side of the die coater and a rear lip 102b positioned on the opposite side of the advancing direction (102b) has a lip lower end face opposing the substrate, a length A of the lower end face of the front lip (102a) along the advancing direction is A, a length of the lower end face of the rear lip If the length along the direction is B, then A > B.

(A)

The length of A is usually 0.5 mm or more, preferably 0.7 mm or more, and more preferably 1 mm or more. On the other hand, it is usually 2.5 mm or less, preferably 2.0 mm or less, more preferably 1.5 mm or less, and further preferably 1.2 mm or less.

These ranges make it possible to keep the liquid amount of the lip portion and the coating surface appropriately and to prevent the occurrence of coating streaks during coating due to the lack of the coating liquid at the time of initiation of coating of the lip portion and liquid diffusion have.

(B)

The length of B is usually 0.03 mm or more, preferably 0.05 mm or more, and more preferably 0.1 mm or more. When the lower limit is within these ranges, there is a tendency to prevent damage to the lip portion, to prevent scratches caused by damage, and to prevent streaks from being generated due to dust adhered to the scratches, coating liquid foam, and the like.

On the other hand, it is usually 2 mm or less, preferably 1 mm or less, more preferably 0.5 mm, and further preferably 0.3 mm or less. When the upper limit is in these ranges, reduction of vortexes generated in the coated bit of the rear lip, elongation deformation of the composition for forming an anisotropic dye film that flows out from the die slot portion can be obtained, and wetting of the composition for forming anisotropic dye film on the lip The diffusion tends to be improved.

(Relationship between A and B)

The lengths of A and B are not particularly limited as long as A > B, and the length ratio and difference are not particularly limited.

The difference in length of A and B is preferably 0.1 mm or more, and more preferably 0.3 mm or more. On the other hand, it is preferably 2.0 mm or less, and more preferably 1.5 mm or less.

The ratio (A / B) of the lengths of A and B is preferably 2 or more, more preferably 5 or more, and further preferably 10 or more. On the other hand, it is preferably 30 or less, more preferably 25 or less.

With these ranges, the liquid amount of the application bit of the rear lip and the front lip is suitably maintained, the vortex generated in the application bit of the rear lip is reduced, and the composition for forming the anisotropic dye film, There is a tendency that improvement of liquid diffusion (liquid passing) at the time of initiation of application of the lip portion and improvement of the wet diffusion of the composition for forming an anisotropic dye film to the lip portion tends to be obtained.

The slot width is usually 10 占 퐉 or more, preferably 30 占 퐉 or more, and more preferably 50 占 퐉 or more. On the other hand, it is usually 0.5 mm or less, preferably 0.3 mm or less, and more preferably 0.1 mm or less.

With these ranges, stress due to stretching deformation accommodated in the composition for forming an anisotropic dye film effectively acts, and there is a tendency to obtain an anisotropic dye film having high orientation properties and excellent polarization performance. In addition, the film thickness distribution of the anisotropic coloring film becomes good, and clogging due to foreign substances and coating streaks tend to be suppressed.

In order to improve the wettability with the composition for forming an anisotropic dye film, the die in the present embodiment may be formed into a layer such as a plasma or an acidic aqueous solution A method of forming a film for improving wettability on the surface in contact with the composition for forming an anisotropic dye film, a method of forming a film for improving wettability on the surface in contact with the composition for forming an anisotropic dye film, A method of polishing the surface, or the like may be combined.

Parallel to the substrate surface includes not only complete parallel but also substantially parallel with a slight angle deviation. The allowable deviation of the angles is usually 5 DEG or less, preferably 3 DEG or less, more preferably 1 DEG or less, still more preferably 0.5 DEG.

The distance between the front lip and the rear lip is preferably equal to the distance from the substrate surface, but may be different. In this case, since the speed of the die coater for obtaining a uniform coating film can be increased, the distance between the front lip and the substrate surface may be shorter than the distance between the rear lip and the substrate surface. When the distance between the front lip and the substrate surface is shorter than the distance between the rear lip and the substrate surface, the difference is usually 0.1 mm or less, preferably 0.05 mm or less, and more preferably 0.01 mm or less. Here, the distance refers to the length of the shortest part between the substrate-side surface of the rib and the substrate surface.

The distance between the front lip and the rear lip and the surface of the substrate may be different as described above. However, it is possible to prevent collision between the front and rear ribs and the substrate surface due to the surface roughness of the die lip and the substrate, In order to obtain a film, each independently preferably is at least 0.01 mm, more preferably at least 0.03 mm, and even more preferably at least 0.05 mm.

On the other hand, as the distance between the front lip and the rear lip and the substrate surface is as small as possible, it is possible to increase the coating speed independently of each other so that it is preferably not more than 0.3 mm, more preferably not more than 0.2 mm, still more preferably not more than 0.1 mm to be. Here, the distance is the length of the shortest part between the lip and the substrate surface.

(Die coater)

The die coater in this embodiment is a die coater including the die. The die coater in this embodiment may be a sheet-fed type or a roll-to-roll type. Hereinafter, the structure of a die coater used in the sheet-fed system will be described with reference to Fig.

2 is a perspective view showing an embodiment of a die coater. The die coater 100 is an apparatus for applying an anisotropic dye film forming composition as a coating liquid to a substrate S and is used for forming an anisotropic dye film included in an optical element constituting a liquid crystal element. The die coater 100 includes a coating table 105 for mounting a substrate S, a die 101 for applying a composition for forming an anisotropic color film to a substrate S on a coating table 105, 101 for moving the die driving mechanisms 108a, 108b. The substrate S is loaded at a predetermined position of the application table 105. The die 101 is formed by sandwiching shims (not shown) between two opposing die blocks. A slot is formed by two die blocks and shims, and the composition for forming an anisotropic dye film is discharged from the discharge port 104 at the tip of the die via the slot.

The die driving mechanism is provided with a holding portion 108a for holding the die 101 and a driving portion 108b for driving the holding portion 108a to reciprocate in the drawing. The holding portion 108a holds the die 101 so that the ejection orifice for ejecting the composition for forming an anisotropic dye film maintains a certain distance from the substrate S. [ Incidentally, although not shown, it has a positioning mechanism capable of appropriately changing the distance between the discharge port and the substrate S.

The driving unit 108b is constituted by various motors, encoders, and the like, and drives the holding unit 108a to move the die 101 inward. In this manner, the die 101 applies the composition for forming an anisotropic dye film on the substrate S.

(Production method of anisotropic dye film)

The manufacturing method of this embodiment has a coating step described later, but it may have other steps. Other steps include, for example, a cleaning step and a supplying step. When a liquid crystal device is manufactured, a step of forming another film such as an alignment film or a protective film on the substrate, a drying step of drying the formed film, and the like can be given.

(Coating step)

In the application step, a composition for forming an anisotropic dye film is applied on a substrate to form an anisotropic dye film. One of the specific aspects of the optical element described below is a polarizing element, and the polarizing element includes an anisotropic dye film. The polarizing element may be composed of only an anisotropic dye film, and may have another film for the purpose of improving the polarization performance or improving the mechanical strength.

The application step in this embodiment is a step of forming an anisotropic dye film by a wet film formation method. The wet film formation method is a method in which a composition for forming an anisotropic dye film is applied on a substrate by any method and the dye is aligned and laminated on the substrate through the process of drying the solvent. In this embodiment, a die coater is used as an application means. In the wet film-forming method, when a composition for forming an anisotropic dye film is formed on a substrate, the dye itself is self-assembled in the composition for forming an anisotropic dye film or in the course of drying the solvent, thereby causing orientation in a small area. By applying an external field to this state, it is possible to obtain an anisotropic dye film having a desired performance by being oriented in a certain direction in a macroscopic region. In this respect, this method is different from a method in which a so-called polyvinyl alcohol (PVA) film is dyed and stretched with a solution containing a dye, and the dye is oriented only by a stretching process. The sheathing may be effected in advance by the effect of the orientation treatment layer on the substrate, shearing force, elongation deformation, magnetic field, etc., and they may be used alone or in combination.

The process of applying the composition for forming an anisotropic dye film onto the substrate, the process of orienting the mask by applying an external coating, and the drying process of the solvent may be performed sequentially or simultaneously.

The orientation direction of the anisotropic dye film is usually the same as the application direction, but may be different from the application direction. In this embodiment, the orientation direction of the anisotropic dye film is, for example, a transmission axis or absorption axis of polarized light if it is an anisotropic dye film and a fast axis or a slow axis if it is a retardation film.

The feeding method and supply interval to the die coater of the composition for forming an anisotropic dye film at the time of continuously applying the composition for forming an anisotropic dye film are not particularly limited but the operation of feeding the application liquid may become complicated, And when the film thickness of the anisotropic dye film is small, it is preferable to apply the composition for forming the anisotropic dye film continuously while supplying it to the die coater.

In this embodiment, the application of the composition for forming an anisotropic dye film may be continuously applied to the entire substrate subjected to the treatment for forming the lyophilic portion and / or the liquid-repelling portion, or may be partially applied.

As described above, the die coater used in this embodiment has the tip of the die defined by predetermined A and B, so that the coating liquid does not excessively stay on the coating side, . Since this optimum state is stable even during coating, the coating speed can be improved without causing defects on the substrate. Therefore, since the shearing force against the applied composition for forming an anisotropic dye film can be increased, the orientation property is improved and the polarizing performance of the anisotropic dye film after application is improved.

At this time, the speed of the die coater is preferably 5 mm / s or more, more preferably 7 mm / s or more, and still more preferably 10 mm / s or more, from the viewpoints of productivity such as mass production, Or more, and particularly preferably 15 mm / s or more.

On the other hand, from the viewpoint of uniformly coating the composition for forming an anisotropic film on the substrate, it is preferably 200 mm / s or less, more preferably 150 mm / s or less, and further preferably 100 mm / s or less.

The application temperature of the composition for forming an anisotropic dye film is usually from 0 캜 to 80 캜, preferably 40 캜 or less. The humidity at the time of application of the composition for forming an anisotropic dye film is preferably 10% RH or more, more preferably 30% RH or more, and preferably 80% RH or less.

A second embodiment of the present invention is an anisotropic dye film obtained by the above production method. The description of the anisotropic dye film related to this embodiment is cited for the description of the anisotropic dye film described in the first embodiment.

A third embodiment of the present invention is an optical element including the anisotropic dye film.

(Optical element)

The optical element in this embodiment is a polarizing element, a retardation element, and an element having functions of refractive anisotropy and conduction anisotropy for obtaining linearly polarized light, circularly polarized light, elliptically polarized light and the like by utilizing anisotropy of light absorption. Such a function can be suitably adjusted by selecting a film-forming process and a composition containing a substrate or an organic compound (a dye or a transparent material). In this embodiment, it is preferable to use it as a polarizing element.

(Polarizing element)

A polarizing element in an optical element is obtained by laminating a composition for forming an anisotropic dye film on a substrate. In addition, it may have a certain film (layer). For example, it can be produced by forming a composition for forming an anisotropic dye film on the surface of an alignment film. In the polarizing element of the present embodiment, in addition to the alignment film and the anisotropic dye film, a function as an overcoat layer, an adhesive layer or an antireflection layer, an orientation film, a retardation film, a function as a luminance enhancement film, A layer having various functions such as a layer having optical functions such as a function as a reflecting film and a function as a diffusing film may be laminated and formed as a laminate by coating or bonding. The layer having these optical functions can be formed, for example, by the following method.

The layer having a function as a retardation film may be subjected to a stretching treatment described in, for example, Japanese Unexamined Patent Application Publication No. 2-59703 and Japanese Unexamined Patent Publication No. 4-230704 or the like as disclosed in Japanese Unexamined Patent Application Publication No. 7-230007 Followed by treatment.

The layer having a function as a brightness enhancement film can be obtained by forming micropores by the method described in, for example, Japanese Patent Application Laid-Open No. 2002-169025 or Japanese Patent Application Laid-Open No. 2003-29030, Can be formed by superimposing two or more different cholesteric liquid crystal layers.

The layer having a function as a reflective film or a transflective film can be formed using a metal thin film obtained by vapor deposition, sputtering or the like. The layer having a function as a diffusion film can be formed by coating a resin solution containing fine particles in the protective layer.

The layer having a function as a retardation film or an optical compensation film can be formed by applying a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound and orienting the liquid crystal compound.

When the anisotropic dye film in this embodiment is used as an anisotropic dye film in various display elements such as LCD and OLED, it is preferable to form an anisotropic dye film directly on the surface of the electrode substrate constituting these display elements, And the formed substrate can be used as constituent members of these display elements.

The polarizing element can be formed directly on a high heat-resistant substrate such as glass to obtain a polarizing element with high heat resistance. Therefore, the polarizing element can be used not only for a liquid crystal display or an organic electroluminescence display, but also for a liquid crystal projector, And can be suitably used for required applications.

A fourth embodiment of the present invention is a liquid crystal element including the optical element.

(Liquid crystal element)

The liquid crystal device of this embodiment is usually formed by sandwiching a liquid crystal material between two substrates. The basic constitution of the liquid crystal element is as shown in Fig. 1 on page 45 of "Industrial Co., Ltd." Flat Panel Display Encyclopedia "(issued by Tatsuo Uchida, . That is, the liquid crystal device of the present embodiment has a pair of substrates arranged opposite to each other, a pair of alignment films (alignment layers for orienting the liquid crystal material) formed inside each substrate, (For example, an ITO electrode or the like) for applying an electric field to the liquid crystal layer, and an electric field is applied to the liquid crystal layer by means of the electrodes to form an array of liquid crystals Thereby controlling transmission and blocking of light.

As a specific display method of the liquid crystal element, there are TN mode, STN mode (see Japanese Patent Laid-Open Publication No. Hei 10 Mode, ECB mode, VA mode, π cell, OCB mode, HAN mode, phase transition-cholesteric liquid crystal mode, ECE mode, ferroelectric liquid crystal mode, antiferroelectric liquid crystal mode, guest-host liquid crystal mode, IPS mode, A liquid crystal device using various liquid crystal modes such as a composite mode, a polymer liquid crystal mode, and a photoluminescence mode can be mentioned, but the liquid crystal device of this embodiment can be applied to any of them.

It is possible to change the arrangement, shape, stacking order, and the like of each constituent element, omit a part of constituent elements, to integrate a plurality of constituent elements integrally, or to change the constituent elements of other constituent elements Or the like, or by appropriately deforming it.

For example, a reflective liquid crystal element having no auxiliary light source such as a backlight, a transmissive or semi-transmissive liquid crystal element having a front light or a side edge light, a monochrome liquid crystal element having no micro color filter, It is also possible to constitute a liquid crystal element.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but it should be understood that the scope of the present invention is not limited to the Examples. In the following, " parts " and " parts "

[Method of measuring viscosity]

The viscosity was measured using a rheometer VAR-50 (manufactured by REOLOGICA) in a parallel plate (diameter 40 mm, gap 0.8 mm). Shear rate sweep measurement was performed by changing the shear rate from 1000 s ^-1 to 100 s ^-1 for 180 seconds after measuring the temperature at 25 ° C and pre-shaking at a shear rate of 1000 s ^-1 for 5 seconds.

In general, the viscosity of the liquid crystalline material varies with the shear rate, and therefore, the viscosity at a shear rate of 1000 s ^-1 as a representative value is defined as the viscosity of each sample.

[Measurement method of transmittance, dichroism ratio and polarization degree for polarized light in the absorption axis direction of anisotropic dye film]

In Examples and Comparative Examples, the transmittance, dichroism ratio, and degree of polarization of the anisotropic dye film with respect to the polarization in the absorption axis direction were measured with a spectrophotometer (product name: "MCPD-2000", manufactured by Otsuka Electronics Co., Ltd.) Lt; / RTI > First, the measurement light of linearly polarized light was incident on the anisotropic dye film, the transmittance of the anisotropic dye film to the polarized light in the absorption axis direction and the transmittance to the polarized light in the polarization axis direction were measured, and then the dichroic ratio was calculated by the following equation.

Dichroic ratio (D) = Az / Ay

Az = -log (Tz)

Month = -log (Ty)

Tz: transmittance of polarized light in the absorption axis direction of the anisotropic dye film

Ty: transmittance of polarized light in the polarization axis direction of the anisotropic dye film

Further, according to JIS Z 8701, the visibility-corrected transmittance of polarized light in the direction of the absorption axis of the anisotropic dye film and the corrected transmittance of the visibility-corrected transmittance of polarized light in the direction of the polarization axis of the anisotropic dye film were measured from the stimulus value Y in the D65 light source 2 ° field of Tz and Ty And the degree of polarization was calculated by the following formula.

The degree of polarization P (%) = {(Yy - Yz) / (Yy + Yz)} ^1/2 100

Yz: Visible sensitivity for polarized light in the absorption axis direction of the anisotropic dye film Transmittance

Yy: Visibility-corrected transmittance of polarized light in the polarization axis direction of the anisotropic dye film

[Film Thickness Unevenness and Occurrence of Coated Streaks]

The resultant anisotropic dye film was visually inspected for the presence of film thickness unevenness and occurrence of coating streaks, and evaluated as follows.

?: There was no film thickness unevenness or coating streaking, and it was a very uniform film.

?: Though film thickness unevenness and coating streaks were slightly seen, it was a uniform film of an acceptable degree.

B: Film thickness unevenness and coating streaks were slightly increased, and the film was partially uneven.

X: Film thickness unevenness and coated stripes were shown on the entire surface, and the film was entirely uneven.

≪ Preparation of composition for forming anisotropic dye film >

<Preparation of composition 1 for forming anisotropic dye film>

18 parts of the azo compound represented by the formula (I) and 1 part of the compound represented by the formula (II) were added to 81 parts of water and dissolved by stirring to remove the insoluble matter, whereby the composition 1 for forming an anisotropic dye film was obtained . The viscosity of the composition 1 for anisotropic dye film formation was 16.0 cP.

(3)

[Chemical Formula 4]

&Lt; Preparation of composition 2 for forming anisotropic dye film &gt;

20 parts of the azo compound represented by the formula (I) and 1 part of the compound represented by the formula (II) were added to 79 parts of water and dissolved by stirring to remove the insoluble matter, thereby obtaining the composition 2 for anisotropic dye film formation . The viscosity of the composition 2 for anisotropic dye film formation was 40.0 cP.

<Preparation of composition 3 for forming anisotropic dye film>

 25 parts of the azo compound represented by the formula (I) and 1 part of the compound represented by the formula (II) were added to 74 parts of water and dissolved by stirring to remove the insoluble matter, thereby obtaining the composition 3 for forming an anisotropic dye film . The viscosity of the composition 3 for anisotropic dye film formation was 82.5 cP.

&Lt; Preparation of coated substrate &

A substrate (polyimide film thickness of about 800 Å) having a polyimide alignment film formed on a glass substrate (100 mm × 100 mm, thickness: 0.7 mm) was previously rubbed with a cloth.

[Example 1]

The length A of the portion of the front lip parallel to the coated surface of the anisotropic dye film was 0.5 mm, the length B of the portion of the rear lip parallel to the coated surface of the anisotropic dye film was 0.1 mm, the slot width of the die was 50 μm Using a single die, the composition 1 for forming an anisotropic dye film was applied so that the rubbing direction of the base material and the coating direction were parallel to each other and the film thickness at the time of coating was 3 占 퐉.

As a result of finding the coating speed of the upper limit that can be applied to the entire surface of the substrate without defects, the coating was carried out at 15 mm / s. Thereafter, the anisotropic dye film 1 having a film thickness of about 0.3 μm was obtained.

The coating conditions were 24 to 26 ° C and 40% RH to 60% RH. The resulting anisotropic dye film 1 did not have film thickness unevenness or coating streaks, and the entire anisotropic dye film was uniform. The transmittance, dichroism ratio and polarization degree of the anisotropic dye film 1 were measured. Table 1 shows the measurement results.

[Examples 2 to 6]

Anisotropic dye films 2 to 6 were obtained in the same manner as in Example 1 except that the lengths of A and B, the film thickness at the time of coating and the composition for forming an anisotropic dye film used were changed to the values shown in Table 1.

Table 1 shows the results of measurement of the application speed of the composition for forming an anisotropic dye film, the film thickness of the obtained anisotropic dye film, the occurrence of film thickness irregularity, the occurrence of coating striations, the transmittance of the anisotropic dye film, the dichroism ratio and the degree of polarization.

[Comparative Examples 1 to 8]

Anisotropic dye films 7 to 14 were obtained in the same manner as in Example 1 except that the lengths of A and B, the film thickness at the time of coating, and the composition for forming an anisotropic dye film used were changed to the values shown in Table 1.

Table 1 shows the results of measurement of the application speed of the composition for forming an anisotropic dye film, the film thickness of the obtained anisotropic dye film, the occurrence of film thickness irregularity, the occurrence of coating striations, the transmittance of the anisotropic dye film, the dichroism ratio and the degree of polarization.

As shown in Examples 1 to 3, when a composition for forming an anisotropic dye film having the same diagrip length and a different viscosity is used, by using the manufacturing method related to the first embodiment of the present invention, the dichroic ratio and the degree of polarization And an anisotropic dye film which is excellent in film thickness unevenness and no occurrence of coating streaks can be obtained.

Also, as shown in Examples 1 and 4 and Comparative Examples 1 to 4, even when the same composition for forming an anisotropic dye film was used and different lengths of the diaplay were used, the manufacturing method related to the first embodiment of the present invention It was found that an anisotropic dye film excellent in dichroism ratio and degree of polarization and free from occurrence of film thickness unevenness and coating streaks was obtained.

100: die coater
101: Die
101a: front side die
101b: rear side die
102a: Front lip
102b: rear lip
103: Composition for forming anisotropic dye film
104:
105: dispensing table
106: Slot
108a: holding portion of the die driving mechanism
108b: Driving portion of the die driving mechanism
S: substrate

Claims (6)

A method for producing an anisotropic dye film comprising a step of applying a composition for forming an anisotropic dye film on a substrate using a die coater,
Wherein the die coater has a front lip located on the side of the advancing direction of the die coater and a rear lip located on the opposite side of the advancing direction and both lips each have a lip lower end face facing the substrate, A is A> B, and the viscosity of the composition for forming an anisotropic dye film is 10 cP or more, where A is a length along the direction of the lower end of the lower lip, and B is a length of the lower end of the lower lip along the traveling direction. / RTI &gt; The method according to claim 1,
Wherein the B is 0.03 mm or more and 2 mm or less. 3. The method according to claim 1 or 2,
Wherein the composition for forming an anisotropic dye film contains an azo compound and a solvent. An anisotropic dye film obtained by the production method according to any one of claims 1 to 3. An optical element comprising the anisotropic dye film according to claim 4. A liquid crystal element comprising the optical element according to claim 5.

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