JP2007272211A - Optical element, and method for the manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having an anisotropic optical film with excellent uniformity. <P>SOLUTION: The optical element has a substrate and the anisotropic optical film formed by applying a composition for forming the anisotropic optical film to the substrate, wherein the optical element is characterized in that average surface roughness of a substrate surface to which the composition for forming the anisotropic optical film is applied is 300Å or less, and a contact angle between the composition for forming the anisotropic optical film and the substrate surface to which the composition is applied is 75° or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element or the like, and more particularly to an optical element or the like provided with an anisotropic optical film on a substrate.

In an LCD (liquid crystal display), a linearly polarizing plate and a circularly polarizing plate are used to control optical rotation and birefringence in display. Also in OLED (organic EL element), a circularly polarizing plate is used to prevent reflection of external light.
Conventionally, in these polarizing plates (polarizing elements), iodine or a dichroic organic dye is dissolved or adsorbed in a polymer material such as polyvinyl alcohol, and the film is stretched into a film in one direction to obtain two colors. A polarizing film obtained by orienting a functional dye has been widely used. However, the conventional polarizing film manufactured in this way has insufficient heat resistance and light resistance depending on the dye or polymer material used; problems such as poor yield of bonding of the polarizing film when manufacturing a liquid crystal device; was there.

  On the other hand, a method of producing a polarizing film by orienting a dichroic dye by applying a solution containing the dichroic dye on a substrate such as glass or a transparent film while applying a shearing force has been studied. (For example, see Patent Documents 1 and 2).

JP-T 8-511109 JP 2002-277636 A

  However, when a solution containing a dichroic dye is applied on various substrates using the methods described in Patent Documents 1 and 2 and the like, a polarizing film may not be obtained in a preferred mode. That is, for example, when a solution containing a dichroic dye is applied to the surface of a base material made of a polymer material, a uniform coating film cannot be obtained, resulting in a coating defect, and an optically uniform polarizing film, and thus optical In some cases, a homogeneous optical element cannot be obtained.

  The present invention has been made to solve the technical problems as described above, and an object of the present invention is to provide an optical element having excellent uniformity.

  As a result of intensive studies to achieve the above object, the present inventors have a certain smoothness on the surface when an optical element is formed by applying the composition for forming an anisotropic optical film on a substrate. Discovered that an optical element with excellent uniformity can be realized by combining a substrate and a composition for an anisotropic optical film having a certain wettability with the surface of the substrate, and completed the present invention. It came to do.

  That is, the optical element of the present invention is an optical element having a substrate and an anisotropic optical film formed by applying a composition for forming an anisotropic optical film on the substrate, The average surface roughness of the surface on which the film-forming composition is applied is 300 mm or less, and the contact angle of the anisotropic optical film-forming composition with respect to the substrate-coated surface is 75 degrees or less.

  Here, the average surface roughness of the substrate is 20 mm or more, and the contact angle is 40 degrees or more and 65 degrees or less. Further, the average surface roughness of the substrate may be from 20 to 100 mm, and the contact angle may be from 20 to 40 degrees. Furthermore, the average surface roughness of the substrate may be from 20 to 200 mm, and the contact angle may be from 20 to 40 degrees. Still further, the average surface roughness of the substrate may be from 1 to 20 mm, and the contact angle may be from 15 to 75 degrees.

  On the other hand, the substrate includes a polymer base material, and the total light transmittance of the substrate is 80% or more. Further, the water absorption rate of the substrate may be 5% or less.

  Further, the present invention can be regarded as an optical element manufacturing method, and the optical element manufacturing method of the present invention is an optical element manufacturing method including a substrate and an anisotropic optical film laminated on the substrate. An anisotropic optical film is formed by applying a composition for forming an anisotropic optical film having a contact angle with respect to the substrate coating surface of 75 degrees or less onto the substrate coating surface having an average surface roughness of 300 mm or less. It is characterized by that.

  According to the present invention, an optical element including a uniform anisotropic optical film is provided.

  Hereinafter, the best mode (embodiment) for carrying out the present invention will be described. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

The anisotropic optical film in the present embodiment is anisotropic in the electromagnetic properties in any two directions selected from a total of three directions in the three-dimensional coordinate system of the film thickness direction and any two orthogonal in-plane directions. It is an optical film having properties. Examples of electromagnetic properties include optical properties such as absorption and refraction, and electrical properties such as resistance and capacitance. Examples of the film having optical anisotropy such as absorption and refraction include a linearly polarizing film, a circularly polarizing film, a retardation film, and a conductive anisotropic film. In particular, the anisotropic optical film in the present embodiment is an optical film that can be suitably used as a polarizing film, a retardation film, and a conductive anisotropic film.
The optical element in the present embodiment includes a substrate and an anisotropic optical film formed by applying an anisotropic optical film forming composition on the substrate. Hereinafter, this embodiment will be described in detail.

(substrate)
Although it does not specifically limit as a board | substrate in this Embodiment, It is preferable that it is a board | substrate which has favorable surface property, a contact angle characteristic, and a water absorption characteristic. As a base material for forming such a substrate, for example, an inorganic material such as glass; triacetate resin, acrylic resin, polyester resin, polycarbonate resin, polyethylene terephthalate resin, triacetyl cellulose resin, norbornene resin , Polymer materials such as cyclic polyolefin resin or urethane resin; and the like. These may be used alone or in combination of two or more. In particular, the substrate is preferably a substrate including a polymer base material containing a polymer material.

  The substrate surface is not particularly limited, but may be subjected to surface treatment such as corona treatment, plasma treatment, ultraviolet irradiation (UV ozone) treatment, which is a physical or chemical modification treatment means. A coating treatment may be applied to coat a resin such as polyimide, polyvinyl butyral, or polyvinyl acetal. The above corona treatment or the like may be further performed after the coating treatment. By performing such treatment, an appropriate average surface roughness (Ra) can be imparted to the substrate surface, and the wettability of the substrate can be controlled. In particular, when a physical modification treatment means is used, the surface properties and coatability of the coated surface are improved, dichroism is improved, and light scattering (haze) is decreased.

The Ra value of the surface of the substrate surface to which the composition for forming an anisotropic optical film is applied is 300 mm or less, preferably 250 mm or less, more preferably 200 mm or less, still more preferably 150 mm or less, and particularly preferably 100 mm or less. The lower limit is usually 1 mm or more, preferably 3 mm or more, more preferably 5 mm or more, further preferably 10 mm or more, particularly preferably 15 mm or more, and most preferably 20 mm or more. If the Ra value is excessively small, movement of molecules such as a dye on the substrate is facilitated, and a uniform optical element may not be obtained.
The Ra value can be measured using an alpha step IQ manufactured by KLA-Tencor Corporation. In the present embodiment, the Ra value is a value calculated as an average value obtained by measuring two locations in the MD direction and TD direction on the substrate surface with a length of 500 μm.

The water absorption rate of the substrate is usually 5% or less, preferably 3% or less, more preferably 1% or less. If the water absorption is excessively large, the substrate may absorb moisture when the film of the anisotropic optical material is formed by a wet film formation method, and the substrate may be warped, which may easily cause a coating defect. In addition, after the anisotropic optical film is formed by a wet film forming method, the substrate may swell and an optical defect may occur.
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.

  An anisotropic optical material such as a dye contained in the anisotropic optical film forming composition is better oriented in a certain direction on the surface of the substrate on which the anisotropic optical film forming composition is applied. From the viewpoint, an alignment treatment layer can be provided in advance. About the formation method of an orientation processing layer, it can be based on the well-known method as described in "Liquid Crystal Handbook" (Maruzen Co., Ltd., issued on October 30, 2000) pp. 226-239.

  Moreover, as a shape of a board | substrate, the film form (sheet-fed form) of a fixed dimension may be sufficient, and a continuous film form (strip | belt shape) may be sufficient. Moreover, as a film thickness of a board | substrate, it is 0.01 mm-3 mm normally, Preferably it is 0.02 mm-2 mm.

The total light transmittance of the substrate is usually 80% or more, preferably 85% or more, more preferably 90% or more.
The “total light transmittance” in the present embodiment is measured using an integrating sphere color measuring device, and is a value obtained by combining diffuse transmission light and parallel light transmission light.

(Anisotropic optical film forming composition)
The composition for forming an anisotropic optical film in the present embodiment includes an anisotropic optical material and a solvent (hereinafter, the composition for forming an anisotropic optical film may be abbreviated as “dye solution”). Moreover, binder resin, a monomer, a hardening | curing agent, an additive, etc. may be mix | blended with the composition for anisotropic optical film formation as needed. The anisotropic optical film forming composition may be in the form of a solution or gel. The anisotropic optical material may be dispersed in a solvent.

Here, the composition for forming an anisotropic optical film is preferably in a liquid crystal phase as a composition from the viewpoint of forming an anisotropic optical film formed after the solvent evaporates with a high degree of orientation. In the present embodiment, the state of the liquid crystal phase refers to the state described on pages 1 to 16 of “Basics and Applications of Liquid Crystal” (Shoichi Matsumoto and Ryo Tsunoda, 1991). Say. In particular, the nematic phase described on page 3 is preferred.
Here, any anisotropic optical material may be used as long as it can form an anisotropic optical film, and examples thereof include pigments and transparent materials.

(Dye)
As the dye, a dichroic dye is usually used. The dye is preferably a dye having a liquid crystal phase for alignment control. Here, the dye having a liquid crystal phase means a dye exhibiting lyotropic liquid crystallinity in a solvent.

  Specific examples of the dye include azo dyes, stilbene dyes, cyanine dyes, phthalocyanine dyes, and condensed polycyclic dyes (perylene and oxazine dyes). Among these dyes, azo dyes that can take a high molecular arrangement in the anisotropic optical film are preferable. An azo dye means a dye having at least one azo group. The number of azo groups in one molecule is preferably 2 or more, preferably 6 or less, more preferably 4 or less, from the viewpoint of color tone and production.

As the dye, a dye represented by the following formula (1) is preferable.

In the above formula (1), A represents a phenylene group which may have a substituent or a naphthylene group which may have a substituent. R ₁ represents a hydrogen atom, a hydroxyl group or an alkoxy group which may have a substituent. R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group that may have a substituent, or a phenyl group that may have a substituent. n represents 0 or 1. X represents 1 or 2. When X is 2, a plurality of A contained in one molecule may be the same or different.

Moreover, the pigment | dye represented by following formula (2) is also preferable.

In the above formula (2), B represents a phenylene group which may have a substituent or a naphthylene group which may have a substituent. R ₄ represents a hydrogen atom, a hydroxyl group or an alkoxy group which may have a substituent. R ₅ and R ₆ represent a hydrogen atom, an alkyl group which may have a substituent, or a phenyl group which may have a substituent. m represents 0 or 1. Y represents 1 or 2. When Y is 2, the plurality of B contained in one molecule may be the same or different.

Furthermore, the pigment | dye represented by following formula (3) is also preferable.

In the above formula (3), D ¹ represents a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. To express. A ¹ represents an aromatic hydrocarbon group which may have a substituent. R ₇ and R ₈ each independently represent a hydrogen atom, an optionally substituted alkyl group or an optionally substituted phenyl group. p represents 0 or 1.

  In the present embodiment, “may have a substituent” means having one or more substituents. The dyes represented by the above formulas (1) to (3) in the present embodiment are usually water-soluble dyes depending on the number of hydrophilic groups in the molecule. It is a chromatic dye.

In the formula (3), when D ¹ is an aromatic heterocyclic group which may have a substituent, examples of the hetero atom of the aromatic heterocyclic group include a nitrogen atom and a sulfur atom. In particular, it is preferable to have an aromatic heterocyclic group having a nitrogen atom for decreasing the liquid crystal expression density. Specific examples of the aromatic heterocyclic group include a pyridyl group, a quinolyl group, a thiazolyl group, and a benzothiazolyl group, and a pyridyl group is preferable.

In the formula (3), A ¹ represents an aromatic hydrocarbon group which may have a substituent. Specific examples of the aromatic hydrocarbon group include a phenylene group and a naphthylene group.
The phenylene group is preferably a 1,4-phenylene group, and the naphthylene group is preferably a 1,4-naphthylene group because the dyes interact with each other.

In the above formulas (1) to (3), the substituents which the phenylene group, naphthylene group, aromatic hydrocarbon group or aromatic heterocyclic group of A, B, D ¹ and A ¹ may have. Includes an alkyl group, an alkoxy group, an amino group, an acyl group, a carbamoyl group, a carboxy group, a sulfo group, a hydroxyl group and a cyano group. In particular, a hydrophilic group introduced to enhance the solubility of the dye, an electron donating group introduced to adjust the color tone, or a group having an electron withdrawing property are preferable. These substituents may further have a substituent, and examples thereof include an alkyl group, an alkoxy group, an amino group, an acyl group, a carbamoyl group, a carboxy group, a sulfo group, a hydroxyl group and a cyano group.

  Specifically, an alkyl group (preferably having 1 to 4 carbon atoms) which may have a substituent such as a methyl group, an ethyl group, an n-propyl group, a hydroxyethyl group, or a 1,2-dihydroxypropyl group. Alkyl group); alkoxy group (preferably carbon number) which may have a substituent such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, hydroxyethoxy group, 1,2-dihydroxypropoxy group, etc. An alkylamino group such as a methylamino group, an ethylamino group, a propylamino group, or a dimethylamino group (preferably an amino group substituted with an alkyl group having 1 to 4 carbon atoms); a phenylamino group An acetyl group such as an acetyl group or a benzoyl group (preferably an amino group substituted with an acyl group having 2 to 7 carbon atoms) Cyano group; a phenylamino group, a substituted carbamoyl group such as naphthyl amino group; a carboxyl group; a sulfo group; a hydroxyl group; and a cyano group.

Of these substituents, preferred are a sulfo group, a hydroxyl group and a carboxy group.
In the above formulas (1) to (3), when R ₂ , R ₃ , R _{5 to} R ₈ are alkyl groups, the alkyl group is preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group may have a substituent.
Moreover, when R < ₁ > and R < ₄ > in said Formula (1)-(2) is an alkoxy group, as this alkoxy group, a C1-C4 alkoxy group is preferable. The alkoxy group may have a substituent.
Furthermore, examples of the substituent that the alkyl group, alkoxy group, or phenyl group of R _{1 to} R ₈ in formulas (1) to (3) may have include a hydroxyl group, a carboxy group, and a sulfo group.

  The molecular weight of the dyes represented by the formulas (1) to (3) is preferably 450 or more, preferably 1500 or less, more preferably 1100 or less in the form of a free acid.

The dyes represented by the formulas (1) to (3) are suitable as dyes for anisotropic dye films formed by a wet film forming method, have low wavelength dispersion, and have a high dichroic ratio. Therefore, an anisotropic dye film showing a high degree of molecular orientation can be obtained using the dye. Therefore, if a dye composition using the dye is used for the anisotropic dye film, an anisotropic dye film having high polarization characteristics can be obtained.
An anisotropic optical film manufactured using a dye as the anisotropic optical material is referred to as an anisotropic dye film.

  The dye in the present embodiment may be used in the form of a free acid as represented by the above formulas (1) to (3), and a part of the acid group takes a salt form. Also good. Further, a salt-type dye and a free acid-type dye may be mixed. Moreover, when it is 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 a salt type exchange method, a known method can be arbitrarily used, and examples thereof include the following methods.

1) A strong acid such as hydrochloric acid is added to an aqueous solution of a dye obtained in a salt form, the dye is acidified in the form of a free acid, and then the dye is added with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). A method of neutralizing acidic groups and salt exchange.
2) A method of performing salt exchange in the form of a salting-out cake by adding a large excess of a neutral salt (eg, lithium chloride) having a desired counter ion to an aqueous dye solution obtained in a salt form.
3) An aqueous solution of a dye obtained in a salt form is treated with a strongly acidic cation exchange resin, and the dye is acidified in the form of a free acid, and then an alkali solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). ) To neutralize the acidic group of the dye and perform salt exchange.
4) A method of performing salt exchange by allowing an aqueous solution of a dye obtained in a salt form to act on a strongly acidic cation exchange resin previously treated with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution).

Whether the acidic group of the dye in the present embodiment is a free acid type or a salt type depends on the pKa of the dye and the pH of the aqueous dye solution.
Examples of the salt type include salts of alkali metals such as Na, Li and K, ammonium salts which may be substituted with alkyl groups or hydroxyalkyl groups, and organic amine salts. Examples of the organic amine include a lower alkyl amine having 1 to 6 carbon atoms, a hydroxy substituted lower alkyl amine having 1 to 6 carbon atoms, a carboxy substituted lower alkyl amine having 1 to 6 carbon atoms, and the like. In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed.

  Preferable examples of the dyes represented by the formulas (1) to (3) in the present embodiment in the form of free acid include, but are not limited to, dyes having the structure shown below, for example. .

  Although the above-mentioned pigment | dyes can be used independently, these 2 or more types may be used together, and pigment | dyes other than the said exemplary pigment | dye can also be mix | blended and used to such an extent that orientation is not reduced. Thereby, anisotropic dye films having various hues can be produced.

Examples of blending pigments when blending other pigments include C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 34, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 142, C.I. I. Direct
Yellow 132, C.I. I. Acid Yellow 25, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Orange 79, C.I. I. Acid Orange 28, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Acid Red 37, C.I. I. Direct Violet 9, C.I. I. Direct Violet 35, C.I. I. Direct Violet 48, C.I. I. Direct Violet 57, C.I. I. Direct Blue 1, C.I. I. Direct Blue 67, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Green 42, C.I. I. Direct Green 51, C.I. I. Direct Green 59 etc. are mentioned.

(Transparent material)
On the other hand, examples of the transparent material among anisotropic materials include lyotropic liquid crystalline compounds such as the following A-1 to A-21. The lyotropic liquid crystalline compound is a compound that exhibits liquid crystallinity when dissolved in a specific solvent in a specific concentration range (see Maruzen Co., Ltd., Liquid Crystal Handbook 3p, etc.).

  Other transparent materials include the following compounds B-1 to B-7. These B-1 to B-7 compounds are preferred because they are easily combined with the lyotropic liquid crystalline compound when used in combination with the lyotropic liquid crystalline compound.

  In addition, 1 type may be used for a transparent material and it may use 2 or more types together by arbitrary combinations and a ratio.

(solvent)
As the solvent, water, a water-miscible organic solvent, or a mixture thereof is suitable. 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, cellosolves such as methyl cellosolve and ethyl cellosolve, or a mixture of two or more. A solvent is mentioned.

(concentration)
The concentration of the anisotropic optical material in the composition for forming an anisotropic optical film is usually 0.01% by weight or more, particularly preferably 0.1% by weight or more, although it depends on the film forming conditions. Usually, it is preferably 50% by weight or less, particularly preferably 30% by weight or less. If the anisotropic optical material concentration is excessively low, sufficient anisotropy such as a dichroic ratio cannot be obtained in the obtained anisotropic optical film. If it is excessively high, the viscosity becomes high and uniform thin film coating is possible. May become difficult, or an anisotropic optical material may precipitate in the composition for forming an anisotropic optical film.

(Additive)
In the composition for forming an anisotropic optical film, additives such as a surfactant, a leveling agent, a coupling agent, and a pH adjuster can be further blended as necessary. Depending on the additive, wettability, applicability and the like may be improved.
As the surfactant, any of anionic, cationic and nonionic can be used. The concentration of the additive is not particularly limited, but is usually sufficient for obtaining the added effect and does not inhibit the molecular orientation, and is usually the concentration in the composition for forming an anisotropic optical film. 0.05 wt% or more and 0.5 wt% or less is preferable.
In addition, for the purpose of suppressing instability such as salt formation and aggregation of the anisotropic optical material in the composition for forming an anisotropic optical film, a known pH adjuster such as acid / alkali is added. Further, it may be added either before or after mixing the constituent components of the composition for forming an anisotropic optical film or during mixing.
As additives other than those mentioned above, “Additive for Coating”, Edited by J. et al. Known additives described in Bieleman, Willy-VCH (2000) can also be used.

The contact angle of the composition for forming an anisotropic optical film in the present embodiment with respect to the substrate coating surface is 75 degrees or less, preferably 65 degrees or less, more preferably 55 degrees or less, and particularly preferably 40 degrees or less. The lower limit is usually 15 degrees or more, preferably 20 degrees or more, more preferably 25 degrees or more, and particularly preferably 40 degrees or more. If the contact angle is too small, liquid flow may occur and uneven portions may occur in the film.
Examples of the method for adjusting the contact angle include a method for changing the surface treatment conditions for the substrate surface described above, and a method for changing the composition of the composition for forming an anisotropic optical film.
As a method for changing the surface treatment conditions, for example, the treatment time can be changed or the treatment intensity can be changed.
For example, when an ultraviolet irradiation treatment is performed on a resin substrate such as a polyethylene terephthalate resin, the contact angle can be lowered by increasing the treatment time. For example, when a plasma treatment is performed on a resin substrate such as a polyethylene terephthalate resin, the contact angle can be lowered by increasing the plasma treatment strength.
Also, the contact angle varies depending on the commercially available substrate. For example, if the surface roughness of the substrate is increased, the contact angle can be lowered.
And as a method of changing the composition of the composition for anisotropic optical film formation, the kind and density | concentration of the anisotropic optical material to add, an additive, etc. can be changed.
For example, when an anisotropic optical film forming composition using water as a solvent is used for a hydrophobic substrate, the contact angle can be lowered by using an anisotropic optical material having hydrophobicity. .
Moreover, if an anisotropic optical material having an alkyl group is used, the contact angle can be lowered.
Furthermore, when the concentration of the anisotropic optical material is increased, the contact angle can be decreased.
Furthermore, if an additive such as a surfactant is used, the contact angle can be lowered.
In the above specific examples, the case of lowering the contact angle has been described, but it goes without saying that the contact angle can be increased by performing the reverse operation to the above.
In addition, as a measuring method of the contact angle in this Embodiment, Kyowa Interface Science Co., Ltd. contact angle meter (surface tension meter) CA-DT can be used. A droplet having a diameter of about 1.5 mm is formed, the substrate surface is brought into contact with the droplet, and θ / 2 of the droplet is measured 30 seconds after the droplet gently moves to the substrate surface. Thereby, the contact angle θ is obtained (θ / 2 method).

(Anisotropic optical film)
The anisotropic optical film in the present embodiment is an anisotropic optical film formed by applying the anisotropic optical film forming composition on the substrate, and the orientation direction of the anisotropic optical film Usually coincides with the application direction. In the present embodiment, the orientation direction of the anisotropic optical film is, for example, a polarizing transmission axis or absorption axis in the case of a polarizing film, and a fast axis or slow axis in the case of a retardation film. That is.

  The anisotropic optical film in this embodiment functions as a polarizing film or retardation film that obtains linearly polarized light, circularly polarized light, elliptically polarized light, etc. by utilizing the anisotropy of light absorption, as well as a film forming process and a substrate. Or a composition containing an organic compound (pigment or transparent material) can be functionalized as various anisotropic films such as refractive anisotropy and conduction anisotropy.

  The anisotropic optical film in the present embodiment is usually manufactured by a wet film forming method. Here, the wet film forming method refers to a method in which a coating solution is applied on a substrate, and a compound (pigment or transparent material) contained in the coating solution is oriented and / or laminated.

The wet film forming method is not particularly limited. For example, the method described in pages 253 to 277 of Yuji Harasaki, “Coating Engineering” (Asakura Shoten Co., Ltd., published on March 20, 1971), Supervised by Kunihiro Ichimura, “Creation and Application of Molecular Coordination Materials” (CMC Publishing Co., Ltd., published on March 3, 1998), pages 118 to 149, on the substrate (which may be pre-aligned) Examples thereof include a slot die coating method, a spin coating method, a spray coating method, a bar coating method, a roll coating method, a blade coating method, a curtain coating method, a fountain method, and a dip method.
Among these, the slot die coating method is preferable because an anisotropic optical film with high uniformity can be obtained.

  In the case of employing the wet film forming method, the coating speed is usually 5 mm / second to 1000 mm / second, preferably 10 mm / second to 300 mm / second. If the coating speed is too small, the anisotropy of the anisotropic optical film may be lowered. On the other hand, when too large, there exists a possibility that it cannot apply | coat uniformly.

  In addition, as temperature at the time of application | coating on the board | substrate of the composition for anisotropic optical film formation, it is 0 degreeC or more and 80 degrees C or less, Preferably it is 40 degrees C or less. Moreover, the humidity at the time of application | coating on the board | substrate of the composition for anisotropic optical film formation is 10% RH or more normally, Preferably it is 30% RH or more, and is normally 80RH% or less.

  The thickness of the anisotropic optical film is usually 10 nm or more, preferably 50 nm or more as the dry film thickness, and is usually 30 μm or less, preferably 1 μm or less as the upper limit. If the film thickness of the anisotropic optical film is excessively large, it may be difficult to obtain a uniform orientation of molecules within the film, while if it is excessively small, it may be difficult to obtain a uniform film thickness. There is.

(Optical element)
In the optical element in the present embodiment, the surface of the substrate on which the anisotropic optical film-forming composition is applied has an average surface roughness of 300 mm or less, and the anisotropic optical film-forming composition has the substrate. The contact angle with respect to the coated surface is 75 degrees or less.
By this combination, a uniform anisotropic optical film can be obtained, and an optical element having this anisotropic optical film has a high anisotropy such as a dichroic ratio or a light scattering (haze). It will be low.
In particular, when the average surface roughness of the substrate is 20 ° or more and the contact angle is 40 ° or more and 65 ° or less; the average surface roughness of the substrate is 20 ° or more and 100 ° or less, and the contact angle is 20 °. When the average surface roughness of the substrate is 20 ° to 200 ° and the contact angle is 20 ° to 40 °; or the average surface roughness of the substrate is 1 ° to A particularly high effect is obtained when the contact angle is 20 ° or less and the contact angle is 15 ° or more and 75 ° or less.
The optical element in the present embodiment has a substrate and an anisotropic optical film, but can be used by stacking a protective layer as necessary. This protective layer is formed by lamination with a transparent polymer film such as triacetate, acrylic, polyester, polyimide, triacetyl cellulose, or urethane film, and is put to practical use.

The optical element in the present embodiment can employ various configurations depending on the application. When the anisotropic optical film according to the present embodiment is used as a polarizing film or a retardation film for various display elements such as LCDs and OLEDs, the anisotropic optical film is directly anisotropic on the surface of the electrode substrate constituting these display elements. For example, a substrate having an anisotropic optical film formed thereon or a substrate having an anisotropic optical film formed thereon can be used as a constituent member of these display elements.
In addition, the anisotropic optical film in this embodiment can be directly formed on a high heat resistant substrate such as glass, and a high heat resistant polarizing element can be obtained. It can be an optical element suitable not only for organic EL displays but also for applications that require high heat resistance such as liquid crystal projectors and in-vehicle display panels.

  The optical element in the present embodiment can be configured in combination with another member having an optical function or another optical film. Other members having an optical function are not particularly limited. For example, an antireflection film, a retardation film, a brightness enhancement film, a reflection film, a transflective film, a diffusion film, an optical compensation film, and a circularly polarized light are used. A film etc. can be mentioned. In addition, these can be laminated | stacked suitably using an adhesive film etc.

Further, the other members having these optical functions are not particularly limited, but can be formed by the following method, for example.
The retardation film is formed, for example, by applying a stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or a process described in Japanese Patent No. 3168850. can do.
For example, the brightness enhancement film may be formed by a method of forming micropores by a method as described in, for example, Japanese Patent Application Laid-Open No. 2002-169025 or Japanese Patent Application Laid-Open No. 2003-29030, or two or more cholesteric layers having different central wavelengths of selective reflection It can be formed by adopting a method of superposing liquid crystal layers.
The reflective film or transflective film can be formed by employing a technique using a metal thin film obtained by vapor deposition or sputtering.
Moreover, a diffusion film can be formed by employ | adopting the method of coating the resin solution containing microparticles | fine-particles on said protective layer.
Further, the retardation film and the optical compensation film can be formed by adopting a method of applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound.

  As described above, in this embodiment, in order to obtain a uniform anisotropic optical film, it is considered necessary that the orientation direction of the anisotropic optical material be as uniform as possible in the film thickness direction. Therefore, the smoothness of the substrate surface needs to be higher than a certain level. Next, if the wettability of the anisotropic optical material solution is too good, it is affected by the alignment of molecules on the substrate surface, and in some cases the in-plane orientation of the anisotropic optical material is deteriorated. If the wettability of the anisotropic optical material solution is poor, coating defects such as repellency are considered. In addition, when the substrate has high hygroscopicity, the substrate may absorb moisture when the film of the anisotropic optical material is formed by a wet film formation method, and the substrate may be warped. In such a case, defects are likely to occur as a result, and the optical defects may occur due to swelling after the anisotropic optical film is formed by the wet film formation method.

  Next, the present embodiment will be described more specifically by way of examples. However, the present embodiment is not limited to the following examples unless it exceeds the gist.

(Production Example 1)
21 parts of Li salt of Exemplified Dye (I) and 1 part of Exemplified Dye (II) below were stirred and dissolved in 78 parts of water to obtain a composition for forming an anisotropic optical film.

(Examples 1 to 19)
The obtained composition for forming an anisotropic optical film was formed on various substrate surfaces subjected to various treatments shown in Table 1 by a wet film forming method, and the coating property was evaluated. The results are shown in Table 1. For the film formation by the wet film formation method, wire bar # 2 (manufactured by Matsuo Sangyo Co., Ltd.) was used. The film thickness of the obtained anisotropic optical film was about 0.5 μm. The coating speed was about 30 mm / second.

[Surface roughness (Ra)]
It is the average surface roughness of the substrate measured using an alpha step IQ manufactured by KLA-Tencor Corporation.
[Contact angle (degrees)]
It is a contact angle of the composition for forming an anisotropic optical film with respect to the substrate surface. It measured using Kyowa Interface Science Co., Ltd. surface tension meter CA-DT.
[Water absorption rate (%)]
It is the water absorption rate of the substrate measured using METTLER Electronic Balance DRAGON204.
[Total light transmittance (%)]
It is the total light transmittance of the board | substrate measured using Shimadzu Corporation Solidspec3700.
[Applicability]
The state in which the composition for forming an anisotropic optical film was applied on the substrate was visually observed and evaluated according to the following criteria.
A: Uniform and defect-free.
○: Uniform but has a defect of 1 mm or less in diameter.
Δ: Almost uniform, but has defects with a diameter of 1 mm or more.
X: It is nonuniform and has a defect.
[Dual color ratio]
It is a dichroic ratio of an anisotropic optical film. It was measured as the value of the ratio of the logarithm (absorbance) of parallel and orthogonal transmittance at a specific wavelength (550 nm).

[substrate]
PET (T100): Mitsubishi Chemical Polyester Film Co., Ltd. Diafoil (registered trademark) T100.
PET (T600): Mitsubishi Chemical Polyester Film Co., Ltd. Diafoil (registered trademark) T600.
PET (O300): Diafoil (registered trademark) O300 manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.
PET (T680): Diafoil (registered trademark) T680 manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.
Arton: Arton film manufactured by JSR Corporation.

[processing]
Antistatic layer coat G-01: Coated by Mitsubishi Chemical Polyester Corporation.
Antistatic layer coat J-30: Coated by Mitsubishi Chemical Polyester Corporation.
Easy adhesion layer 07 coat: Coated by Mitsubishi Chemical Polyester Corporation.
Easy-adhesion layer 36 coat: Coated by Mitsubishi Chemical Polyester Corporation.
Easy-adhesion layer 54 coat: Coated by Mitsubishi Chemical Polyester Corporation.
Corona treatment: Corona Scanner ASA-4, 13 kV, 150 mm / sec, d≈1 mm, manufactured by Shinko Electric Instrumentation Co., Ltd.
Plasma treatment: Compact etcher FA-1, 10W, 1 second, manufactured by Samco Corporation.

(Example 20)
The composition for forming an anisotropic optical film obtained in Production Example 1 was formed on a surface of a substrate subjected to various treatments shown in Table 2 by a wet film forming method, and the coating property was evaluated. The results are shown in Table 2. For the film formation by the wet film formation method, wire bar # 2 (manufactured by Matsuo Sangyo Co., Ltd.) was used. The film thickness of the obtained anisotropic optical film was about 0.5 μm. The coating speed was 240 mm / second.

(Examples 21 to 26)
The composition for forming an anisotropic optical film obtained in Production Example 1 was formed on a surface of a substrate subjected to various treatments shown in Table 2 by a wet film forming method, and the coating property was evaluated. The results are shown in Table 2. A slot die coater was used for film formation by the wet film formation method. The film thickness of the obtained anisotropic optical film was about 0.5 μm. The coating speed was 12 mm / second.

(Examples 27 to 35, Comparative Example 1)
The composition for forming an anisotropic optical film obtained in Production Example 1 was formed on a surface of a substrate which was not subjected to the treatment shown in Table 2 or was subjected to various treatments by a wet film formation method, and the coating property was evaluated. The results are shown in Table 2. For the film formation by the wet film formation method, wire bar # 2 (manufactured by Matsuo Sangyo Co., Ltd.) was used. The film thickness of the obtained anisotropic optical film was about 0.5 μm. The coating speed was about 30 mm / second.

The indices other than the following indices are the same as in Table 1.
[substrate]
TAC: Triacetate film manufactured by LONZA.
[processing]
Polyimide layer coat: Hitachi Chemical DuPont Microsystems LX-1400.
Plasma treatment: Compact etcher FA-1, 20 W, 1 second (Example 21), 20 W, 3 seconds (Example 22), 20 W, 5 seconds (Example 23), 20 W, 10 seconds (Example) manufactured by Samco Corporation 24), 100 W, 1 second (Example 25), 50 W, 1 second (Example 26), 10 W, 1 second (Example 27).

FIG. 1 summarizes the results of Tables 1 and 2 above. As shown in FIG. 1, the average surface roughness (Ra) of the surface of the substrate on which the composition for forming an anisotropic optical film is applied is 300 mm or less, and the contact angle of the composition with respect to the substrate application surface is 75 degrees. In the case of the following, it is possible to provide an optical element having good coatability and having a uniform anisotropic optical film. In this case, since a uniform coating film can be obtained even when high-speed coating is performed, the manufacturing cost can be reduced as a result.
In addition, as a technique for obtaining a substrate having an appropriate surface roughness and wettability, a technique of subjecting the substrate surface to corona treatment, plasma treatment, ultraviolet irradiation (UV ozone) treatment, or the like can be employed.
In addition, good values for dichroism are achieved.

(Production Example 2)
13 parts of exemplary compound (III) was stirred and dissolved in 87 parts of water to obtain a composition for forming an anisotropic optical film.

(Examples 36 to 38, Comparative Example 2)
The anisotropic optical film-forming composition produced in Production Example 2 was formed on a surface of a substrate that had not been treated as shown in Table 3 or was subjected to various treatments by a wet film-forming method, and the coating property was evaluated. Film formation was performed at 20 ° C. or lower. The results are shown in Table 3. Film formation by the wet film formation method used an applicator (manufactured by Imoto Seisakusho Co., Ltd.) with a gap of 20 μm. The film thickness of the obtained anisotropic optical film was about 1 μm. The coating speed was 240 mm / second.

[Haze]
Measured using an automatic haze computer, TM double beam system HZ-2, manufactured by Suga Test Instruments Co., Ltd. The haze value was determined by Td / Tt (Td: diffuse light transmittance, Tt: total light transmittance). D65 was used as the light source.

[processing]
Polyimide layer coat: SE-5300 manufactured by Nissan Chemical Industries, Ltd.
UVO3 treatment: UV dry processor manufactured by Oak Manufacturing Co., Ltd.

The results of Tables 1 and 2 are summarized.

Claims (8)

An optical element having a substrate and an anisotropic optical film formed by applying a composition for forming an anisotropic optical film on the substrate,
The surface of the substrate on which the anisotropic optical film-forming composition is applied has an average surface roughness of 300 mm or less, and the contact angle of the anisotropic optical film-forming composition with respect to the substrate-coated surface is 75 degrees. An optical element characterized by the following.   2. The optical element according to claim 1, wherein the average surface roughness of the substrate is 20 mm or more, and the contact angle is 40 degrees or more and 65 degrees or less.   2. The optical element according to claim 1, wherein the average surface roughness of the substrate is 20 to 100 degrees and the contact angle is 20 to 40 degrees.   2. The optical element according to claim 1, wherein the average surface roughness of the substrate is 20 to 200 ° and the contact angle is 20 to 40 degrees.   2. The optical element according to claim 1, wherein the average surface roughness of the substrate is 1 to 20 ° and the contact angle is 15 to 75 °.   The optical element according to claim 1, wherein the substrate includes a polymer base material, and the total light transmittance of the substrate is 80% or more.   The optical element according to claim 1, wherein the substrate has a water absorption of 5% or less. A manufacturing method of an optical element comprising a substrate and an anisotropic optical film laminated on the substrate,
An anisotropic optical film is formed by applying a composition for forming an anisotropic optical film having a contact angle with respect to the substrate coating surface of 75 ° or less onto a substrate coating surface having an average surface roughness of 300 mm or less. A method for producing an optical element characterized by the above.

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