JP2023049680A - Method for manufacturing optical film, optical film, and optical laminate - Google Patents

Abstract

To provide a method for manufacturing an optical film that excels in the liquid crystal alignment of an optical anisotropic layer and excels in moisture heat durability and adhesion, as well as provide said optical film and an optical laminate that includes said optical film.SOLUTION: Provided is a method for manufacturing an optical film, comprising: a step 1 for applying a coating of composition for alignment films that contains an alignment agent and a solvent to a substrate to form a coating film; a step 2 for applying alignment processing to the coating film to form an alignment film that has an alignment restricting force; a step 3 for applying a coating of a composition that contains a liquid crystal compound having a polymerizable group to the alignment film to form a composition layer; a step 4 for applying alignment processing to the composition layer and causing the liquid crystal compound to be torsion oriented, with the thickness direction of the composition layer as a spiral axis; and a step 5 for applying curing processing to the composition layer and fixing the alignment state of the liquid crystal compound to form an optical anisotropic layer. The torsion angle, with the thickness direction of the liquid crystal compound serving as the spiral axis in the optical anisotropic layer, is over 0° to 180° inclusive, and the difference between the SP value of the substrate and the SP value of the solvent is 4.0 to 10.0 MPa1/2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical film manufacturing method, an optical film, and an optical laminate.

Retardation layers (optically anisotropic layers) with refractive index anisotropy are applied to various applications such as antireflection films for display devices such as organic EL (Electroluminescence) displays and optical compensation films for liquid crystal display devices. It is
It is known to provide an alignment film on a support forming an optically anisotropic layer in order to orient a liquid crystal compound when producing an optical film having an optically anisotropic layer.

For example, Patent Literature 1 discloses a method for producing an optical layered body, in which an optical layered body having a support, a binder layer imparted with an orientation regulating force, and an optically anisotropic layer in this order is produced. there is

WO2020/110817

The inventors of the present invention have examined an optical film comprising an alignment film provided on a substrate and an optically anisotropic layer containing a liquid crystal compound provided thereon with reference to Patent Document 1. It was found that there is room for further improvement in terms of durability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an optical film having an optically anisotropic layer with excellent liquid crystal orientation, wet heat durability, and adhesion.
Another object of the present invention is to provide the above optical film and an optical laminate including the above optical film.

As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by the following configuration.

[1] Step 1 of coating a substrate with an alignment film composition containing an alignment agent and a solvent to form a coating film, and subjecting the coating film to an alignment treatment to form an alignment film having an alignment regulating force. a step 2 of forming a composition containing a liquid crystal compound having a polymerizable group on the alignment film, a step 3 of forming a composition layer, and performing an alignment treatment on the composition layer, Step 4 for twisting the liquid crystal compound with the thickness direction of the composition layer as a helical axis, and subjecting the composition layer to a curing treatment to fix the alignment state of the liquid crystal compound and optically anisotropic forming a layer, wherein the optically anisotropic layer has a twist angle of more than 0° and 180° or less with the thickness direction of the liquid crystal compound as a spiral axis, and the SP value of the base material and the solvent A method for producing an optical film, wherein the difference from the SP value of is 4.0 to 10.0 MPa ^1/2 .
[2] The method for producing an optical film according to [1], wherein the substrate contains a polymer having an alicyclic structure.
[3] The method for producing an optical film according to [1] or [2], wherein the alignment agent contains a photo-alignment agent.
[4] The substrate has an in-plane retardation of 67.5 to 127.5 nm at a wavelength of 550 nm, and the product of the refractive index anisotropy Δn of the optically anisotropic layer and the thickness d of the optically anisotropic layer. The optical device according to any one of [1] to [3], wherein Δnd is 317 to 377 nm, and the twist angle with respect to the thickness direction of the liquid crystal compound in the optically anisotropic layer as the helical axis is 20 to 60°. Film production method.
[5] An optical film comprising a substrate, an alignment film and an optically anisotropic layer in this order, wherein the alignment film contains an alignment agent, and the optically anisotropic layer contains a liquid crystal compound having a polymerizable group. , The optical film is fixed in a twisted orientation state at a twist angle of more than 0° and 180° or less with the thickness direction of the optically anisotropic layer as a helical axis, and satisfies requirements 1 and 2 described later.
[6] The optical film of [5], wherein the substrate contains a polymer having an alicyclic structure.
[7] The optical film of [5] or [6], wherein the alignment agent contains a photo-alignment agent.
[8] The substrate has an in-plane retardation of 67.5 to 127.5 nm at a wavelength of 550 nm, and the product of the refractive index anisotropy Δn of the optically anisotropic layer and the thickness d of the optically anisotropic layer. The optical film according to any one of [5] to [7], wherein Δnd is 240 to 320 nm, and the twist angle with respect to the thickness direction of the liquid crystal compound in the optically anisotropic layer as the helical axis is 20 to 60. .
[9] An optical laminate comprising the optical film according to any one of [5] to [8] and a polarizer.
[10] The optical laminate according to [9], wherein the angle between the absorption axis of the polarizer and the slow axis of the base material of the optical film is 0±5° or 90±5°.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical film which is excellent in the liquid-crystal orientation property of an optically anisotropic layer, and is excellent in wet-heat durability and adhesiveness can be provided.
Further, according to the present invention, the optical film and an optical laminate including the optical film can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of a structure of the optical film which concerns on this invention. FIG. 2 is a schematic diagram showing an example of a profile obtained by analyzing an optical film along the thickness direction by time-of-flight secondary ion mass spectrometry (TOF-SIMS); It is a schematic diagram showing an example of composition of an optical layered product concerning the present invention. FIG. 4 is a schematic diagram showing another example of the configuration of the optical layered body according to the present invention;

The present invention will be described in detail below. In this specification, the numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits. First, the terms used in this specification will be explained.

The slow axis is the slow axis for light with a wavelength of 550 nm unless otherwise specified.

In this specification, Re(λ) and Rth(λ) represent in-plane retardation and thickness direction retardation at wavelength λ, respectively. Unless otherwise specified, the retardation wavelength λ is 550 nm.
In the present specification, Re(λ) and Rth(λ) are values measured at wavelength λ using AxoScan (a polarimeter device manufactured by Axometrics). By entering the average refractive index ((nx+ny+nz)/3) and film thickness (d (μm)) in AxoScan,
・Slow axis direction (°)
・Re(λ)=R0(λ)
・Rth(λ)=((nx+ny)/2−nz)×d
is calculated.
Note that R0(λ) is a calculated value displayed by AxoScan and means Re(λ). Further, nx, ny and nz are respectively the refractive index in the in-plane slow axis direction of the optical member (the direction in which the in-plane refractive index is maximized), the in-plane slow axis and the in-plane It means the index of refraction in the direction and the index of refraction in the thickness direction.

In this specification, the refractive indices nx, ny, and nz are measured by using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) and using a sodium lamp (λ=589 nm) as the light source. value. When measuring the wavelength dependence of each optical characteristic, the measurement is performed by combining a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) with an interference filter.
Also, as the average refractive index of the polymer film, values in Polymer Handbook (JOHN WILEY & SONS, INC) and various optical film catalogs can be used. Average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
In this specification, the thickness of each optical member can be measured by a known measuring device such as a scanning electron microscope (SEM).

The term "light" used herein means actinic rays or radiation, and includes, for example, the emission line spectrum of mercury lamps, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays (EUV light: Extreme Ultraviolet), X-rays, ultraviolet rays, and an electron beam (EB). Among them, ultraviolet rays are preferable.

As used herein, "visible light" means light with a wavelength of 380-780 nm. In this specification, the measurement wavelength is 550 nm unless otherwise specified.

As used herein, "SP (Solubility Parameter) value" means the Hansen solubility parameter (δd, δp and δh) calculated by the atomic group contribution method, and "Hansen solubility parameter: A User's Handbook, Second Edition, CM Hansen (2007), Taylor and Francis Group, LLC (HSPiP Manual).
As the SP value, a value calculated using commercially available software can be used. The CYCLICOLE FINCOPOLYMER (COC) value described in version 5.1.08) can be used.
The SP value represents the solubility of a compound as a multidimensional vector (dispersion term (δd), polarization term (δp), and hydrogen bonding term (δh)), and these three parameters are Hansen space and It can be thought of as the coordinates of a point in a three-dimensional space called In addition, the “difference” between the SP values of two components means the distance between two points in Hansen space, and the dispersion term (δd ₁ ), polarization term (δp ₁ ) and hydrogen bonding term ( _A value ₍ unit _: ^MPa _1/2 ).
(Difference)={4×(δd ₁ −δd ₂ ) ² +(δp ₁ −δp ₂ ) ² +(δh ₁ −δh ₂ ) ² } ^1/2
When one component contains two or more compounds, the SP value of the component is calculated by summing the values obtained by multiplying the SP value of each compound by the mass fraction of each compound, Hansen It is a value corresponding to the center of gravity of the SP value of each compound in space.

[Method for producing optical film]
The method for producing an optical film according to the present invention is characterized in that predetermined steps are performed, the polymerizable liquid crystal compound contained in the optically anisotropic layer has predetermined physical properties, and the SP value of the substrate and the The difference from the SP value of the solvent contained in the composition is within a predetermined range.
Hereinafter, with regard to the optical film, the fact that at least one of the optically anisotropic layer is excellent in liquid crystal orientation, wet heat durability and adhesion is also described as "excellent effects of the present invention".

The method for producing an optically anisotropic layer according to the present invention (hereinafter also referred to as "this production method") has the following steps 1 to 5.
Step 1: A step of applying an alignment film composition containing an alignment agent and a solvent onto a substrate to form a coating film.
Step 2: A step of subjecting the coating film to an orientation treatment to form an orientation film having an orientation regulating force.
Step 3: A step of applying a composition containing a liquid crystal compound having a polymerizable group onto the alignment film to form a composition layer.
Step 4: A step of subjecting the composition layer to orientation treatment to twist-align the liquid crystal compound with the thickness direction of the composition layer as the helical axis.
Step 5: A step of curing the composition layer to fix the alignment state of the liquid crystal compound to form an optically anisotropic layer.
The procedure of each of the above steps will be described in detail below.

[Step 1]
Step 1 is a step of applying an alignment film composition containing an alignment agent and a solvent onto a substrate to form a coating film.
First, the members and materials used in this process will be described in detail, and then the procedure of the process will be described in detail.

<Base material>
The substrate is a member that supports the optical film.
A transparent substrate is preferable as the substrate. The transparent base material is intended to be a base material having a visible light transmittance of 60% or more, preferably 80% or more, more preferably 90% or more.

Materials constituting the substrate are not particularly limited, but polymers having excellent properties such as optical performance, transparency, mechanical strength, thermal stability, moisture shielding properties, and isotropy are preferred.
Examples of the polymer contained in the substrate include polymers having an alicyclic structure, cellulose ester, polyvinyl alcohol, polyimide, UV-transmitting acrylic, polycarbonate, polysulfone, polyethersulfone, epoxy polymer, polystyrene, and these. A combination is mentioned. Among them, from the viewpoint of transparency, low hygroscopicity, dimensional stability, light weight, etc., a polymer having an alicyclic structure or a cellulose ester is preferable, and a polymer having an alicyclic structure is more preferable. .

The polymer having an alicyclic structure is not particularly limited as long as it is an amorphous polymer having an alicyclic structure in the repeating unit, a polymer having an alicyclic structure in the main chain, and Any polymer having an alicyclic structure in its side chain can be used.
The alicyclic structure includes, for example, a cycloalkane structure and a cycloalkene structure, and the cycloalkane structure is preferred from the viewpoint of thermal stability and the like.
The number of carbon atoms constituting a repeating unit of one alicyclic structure is not particularly limited, and is, for example, 4 to 30, preferably 5 to 20, more preferably 6 to 15.

The proportion of repeating units having an alicyclic structure in the polymer having an alicyclic structure is appropriately selected depending on the purpose of use. % by mass or more is preferable, and 90% by mass or more is more preferable. The upper limit is not particularly limited, and may be 100% by mass.

Examples of polymers having an alicyclic structure include (1) norbornene polymers, (2) monocyclic cyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and polymers selected from these hydrogenated products are preferred.
Among them, norbornene polymers or hydrogenated products thereof are more preferable from the viewpoint of transparency and moldability.

Norbornene polymers include, for example, ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers and other monomers capable of ring-opening copolymerization, and hydrogenated products thereof; Included are copolymers and addition copolymers of norbornene monomers and other copolymerizable monomers.
Among them, a ring-opening polymer of a norbornene monomer or a hydrogenated product thereof is preferable from the viewpoint of transparency.
As for the polymer having the above alicyclic structure, for example, the polymer described in JP-A-2002-321302 can be referred to, and the description of the above document is incorporated herein.

The weight average molecular weight (Mw) of the polymer having an alicyclic structure is, for example, 10,000 to 100,000, preferably 25,000 to 80,000, more preferably 25,000 to 50,000. When the weight average molecular weight is within the above range, the mechanical strength and moldability of the film are well balanced.
The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the polymer having an alicyclic structure is not particularly limited, but is, for example, 1 to 10, preferably 1 to 4, and 1.2 to 3. .5 is more preferred.
In the present specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer (polymer) are determined by gel permeation chromatography using cyclohexane (toluene if the polymer does not dissolve) as a solvent. It is a value measured and converted to polyisoprene (polystyrene when the solvent is toluene).

When the substrate contains a polymer having an alicyclic structure, it may contain only the polymer having an alicyclic structure, and other polymers and/or additives other than the polymer having an alicyclic structure It may contain a drug.
Examples of the above other polymer include the polymers already exemplified as the polymer constituting the base material.
Additives that the substrate may contain include, for example, optical anisotropy modifiers, wavelength dispersion modifiers, fine particles, plasticizers, UV inhibitors, antidegradants, and release agents.
The content of the polymer having an alicyclic structure in the substrate is preferably 70% by mass or more, more preferably 80% by mass or more, relative to the total mass of the substrate. The upper limit is not particularly limited, and may be 100% by mass or less.

Although the thickness of the base material is not particularly limited, it is preferably 10 to 200 μm, more preferably 10 to 100 μm, even more preferably 20 to 70 μm. Moreover, the base material may consist of lamination|stacking of several sheets.

The in-plane retardation value (Re(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably 50 to 300 nm, more preferably 60 to 180 nm, more preferably 60 to 130 nm, in terms of better antireflection performance. More preferred.
The thickness direction retardation value (Rth(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably −150 to 150 nm, more preferably −80 to 80 nm.

The substrate may be an elongated substrate.
As used herein, "long" or "long shape" means that the length in the longitudinal direction is at least 5 times (preferably 10 times or more) the length in the transverse direction (width direction). It refers to the shape, and specifically refers to the shape of a film that is long enough to be wound into a roll and stored or transported.

For example, when an antireflection film for an OLED panel is produced using a long base material, the angle formed by the in-plane slow axis of the base material and the longitudinal direction of the base material is 0 ± 10° or 90 ± It is preferably within the range of 10°, more preferably within the range of 0±5° or 90±5°.
Further, when an antireflection film for an OLED panel is produced using a long base material, the angle formed by the in-plane slow axis of the base material and the longitudinal direction of the base material is 10 ± 10° or 80°. It is preferably within the range of ±10°, more preferably within the range of 10±5° or 80±5°.

A method for preparing the substrate is not particularly limited, and examples thereof include a method of producing the above-mentioned substrate using a material containing a polymer having an alicyclic structure, according to a known method for producing a resin film.
Examples of commercially available materials containing a polymer having an alicyclic structure include "Zeonor (registered trademark) 1420" and "Zeonor 1420R" (both manufactured by Nippon Zeon Co., Ltd.), and "ARTON (registered trademark) G7810" (manufactured by JSR Corporation).
Moreover, you may use the commercial item of the said base material acquired from the market.

From the viewpoint of imparting in-plane anisotropy, the method for producing the substrate preferably includes a step of stretching a film made of the above material. The direction of stretching is longitudinal stretching (stretching in the longitudinal direction of the substrate), lateral stretching (stretching in the width direction of the substrate), oblique stretching, and any of these stretching directions, depending on the direction of the slow axis required for the substrate. It is appropriately selected from the combination. In addition, the draw ratio is appropriately set so that the refractive index anisotropy Δn and/or Re(λ) of the resulting base material falls within a desired range.
Stretching of the film can be performed using a known stretching machine such as a tenter stretching machine and a longitudinal stretching machine.

In order to improve the adhesion between the substrate and the alignment film, the surface of the substrate may be surface-treated (for example, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment and flame treatment).
Further, the substrate may have a functional layer on the surface on which the alignment film is formed. Functional layers include a barrier layer, a shock absorbing layer and an easy adhesion layer.

<Composition for Alignment Film>
The alignment film composition (hereinafter also referred to as “composition A”) used in step 1 contains at least an alignment agent and a solvent. Here, the solvent contained in composition A (hereinafter also referred to as "solvent A") has a difference of 4.0 to 10.0 MPa ^1/2 between the SP value of the base material and the SP value of solvent A. fulfill the relationship.
Each component contained in composition A will be described below.

(Orientation agent)
The alignment agent contained in the composition A is not particularly limited as long as it is a material to which an alignment regulating force is imparted by the alignment treatment in step 2 described later. ) is preferred.
As the photo-alignment material, for example, a photo-dimerization type material, particularly a compound containing a cinnamic acid derivative can be used. Photoisomerizable materials such as azo compounds can also be suitably used.

From the viewpoint of maintaining the alignment regulating force even after applying the composition for the optically anisotropic layer, the alignment film should be made of a material that is difficult to dissolve or swell by the solvent contained in the composition for the optically anisotropic layer. preferable. From the above viewpoints, the composition for forming an alignment film includes a polymer having a photoalignable group as an alignment agent, and optionally at least one polymer selected from the group consisting of a cross-linking agent, a cross-linking accelerator and a cross-linking reaction initiator. preferably include one.
Moreover, from the viewpoint of achieving close adhesion between the alignment film and the optically anisotropic layer, it is preferable to use a polymer having a photo-orienting group, which has a hydrophobicity close to that of the optically anisotropic layer.
Examples of the polymer having a photo-alignable group include, for example, JP-A-6-289374, JP-A-10-506420, JP-A-2009-501238, JP-A-2012-078421, JP-A-2015-106062. JP, JP 2016-079189 A photo-alignable acrylate polymer described in JP 2012-037868, JP 2014-026261, JP 2015-026050, etc. Light described in Oriented polysiloxane, JP-A-2015-151548, JP-A-2015-151549, photo-oriented polystyrene described in JP-A-2016-098249 - acrylate copolymer, JP-A-2012-027471 , a photo-alignable polynorbornene polymer described in JP-A-2015-533883.

The photo-alignment group refers to a group having a photo-alignment function that induces rearrangement or an anisotropic chemical reaction by irradiation with anisotropic light (e.g., plane polarized light). A photoalignable group that undergoes at least one of dimerization and isomerization by the action of light is preferred because it has excellent thermal stability and good chemical stability.

Photoalignable groups that dimerize under the action of light include, for example, cinnamic acid derivatives (M. Schadt et al., J. Appl. Phys., vol. 31, No. 7, page 2155 (1992)), coumarin Derivatives (M. Schadt et al., Nature., vol. 381, page 212 (1996)), chalcone derivatives (Toshihiro Ogawa et al., Lecture Proceedings of the Liquid Crystal Symposium, 2AB03 (1997)), Maleimide Derivatives, and Benzophenone Derivatives (YK Jang et al., SID Int. Symposium Digest, P-53 (1997)).
Examples of photoalignable groups that are isomerized by the action of light include azobenzene compounds (K. Ichimura et al., Mol. Cryst. Liq. Cryst., 298, 221 (1997)), stilbene compounds (JG Victor and JM Torkelson, Macromolecules, 20, 2241 (1987)), spiropyran compounds (K. Ichimura et al., Chemistry Letters, page 1063 (1992); K. Ichimura et al., Thin Solid Films, vol. 235, page 101 (1993)) , cinnamic acid compounds (K. Ichimura et al., Macromolecules, 30, 903 (1997)), and hydrazono-β-ketoester compounds (S. Yamamura et al., Liquid Crystals, vol. 13, No. 2, page 189 (1993)) having at least one compound skeleton selected from the group consisting of:

The photo-alignable group is preferably a group having a skeleton of at least one compound selected from the group consisting of cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, maleimide derivatives, azobenzene compounds, stilbene compounds and spiropyran compounds. A group having a derivative skeleton or a coumarin derivative skeleton is more preferable.

The structure of the main chain of the polymer having a photoalignment group is not particularly limited, and includes known structures such as acrylate skeleton, methacrylate skeleton, siloxane skeleton, and polystyrene skeleton, acrylate skeleton, methacrylate skeleton, Alternatively, a siloxane skeleton is preferred, and an acrylate skeleton or methacrylate skeleton is more preferred.
The acrylate skeleton is a skeleton composed of repeating units derived from an acrylate compound (a compound having an acryloyl group). A methacrylate skeleton is a skeleton composed of repeating units derived from a methacrylate compound (a compound having a methacryloyl group). A polystyrene skeleton is a skeleton composed of repeating units derived from styrene. A siloxane skeleton is a skeleton in which the polymer main chain is composed of Si—O bonds.

The alignment agent preferably has a crosslinkable group capable of reacting with a crosslinker described below. The types of crosslinkable groups are not particularly limited, and include hydroxyl groups, carboxyl groups, amino groups, radically polymerizable groups (e.g., acryloyl groups, methacryloyl groups, vinyl groups, styryl groups, and allyl groups), and cationically polymerizable groups. (eg, epoxy group, epoxycyclohexyl group, and oxetanyl group).
When the alignment agent is a polymer having the photo-alignment group described above, the polymer may have a repeating unit having a crosslinkable group, or the repeating unit having the photo-alignment group further has a crosslinkable group. may have

The content of the alignment agent is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the solvent.

(Solvent A)
As described above, the solvent A contained in the composition A has an SP value that differs from the SP value of the base material within the range of 4.0 to 10.0 MPa ^1/2 .
When the solvent A used in this production method has the above SP value, an optical film excellent in both liquid crystal orientation and wet heat durability can be produced.
If the difference between the SP value of the base material and the SP value of solvent A is too small, the base material dissolves or swells with the solvent, and the components of the base material diffuse into the alignment film, thereby affecting the alignment control force of the alignment film. As a result, the orientation of the liquid crystal compound contained in the optically anisotropic layer decreases, and if the difference between the SP value of the substrate and the SP value of the solvent A is too large, the interface between the substrate and the alignment film It is presumed that the mixture of the base material component and the alignment film component was insufficient and the adhesiveness was not sufficient, and peeling was likely to occur at the interface after the wet heat durability test.

Solvent A is not particularly limited as long as the SP value satisfies the above relationship, and known organic solvents can be used.
Solvent A may be used singly or in combination of two or more.
As described above, when solvent A contains two or more solvents, the SP value of solvent A is the sum of the values obtained by multiplying the SP value of each solvent by the mass-based content of each solvent. Therefore, as long as the above "SP value of solvent A" satisfies the above relationship, composition A contains at least one solvent having an SP value that differs from the SP value of the substrate by less than 4.0 MPa ^1/2 and/or one or more solvents with SP values that differ from the SP value of the substrate by more than 10.0 MPa ^1/2 .

Examples of the organic solvent contained as solvent A in composition A include ketone compounds (e.g., acetone, 2-butanone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, and cyclopentanone), ether compounds (e.g., , dioxane, tetrahydrofuran, alkylene glycol monoalkyl ether, and alkylene glycol dialkyl ether, etc.), aliphatic hydrocarbons (e.g., hexane, etc.), alicyclic hydrocarbons (e.g., cyclohexane, etc.), aromatic hydrocarbons (e.g., toluene, xylene, trimethylbenzene, etc.), halogenated hydrocarbons (e.g., dichloromethane, chloroform (trichloromethane), dichloroethane, dichlorobenzene, and chlorotoluene, etc.), ester compounds (e.g., methyl acetate, ethyl acetate, acetic acid butyl and alkylene glycol monoalkyl ether esters, etc.), alcohol compounds (e.g., ethanol, isopropanol, butanol, cyclohexanol, etc.), sulfoxide compounds (e.g., dimethyl sulfoxide, etc.), and amide compounds (e.g., dimethylformamide , dimethylacetamide, and N-methyl-2-pyrrolidone).
Among them, the solvent A is preferably a ketone compound, an ether compound, a halogenated hydrocarbon, an ester compound, or an alcohol compound, such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, tetrahydrofuran, butyl acetate, ethylene. Glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, dichloromethane or chloroform are more preferred.

The difference between the SP value of the base material and the SP value of the solvent A is preferably 4.0 to 9.0 MPa ^1/2 , more preferably 4.0 to 6.0 MPa ^1/2 , in terms of more excellent effects of the present invention. more preferred.

The content of solvent A (in the case of two or more, the total content) is not particularly limited, but is preferably 80 to 96% by mass, more preferably 85 to 94% by mass, based on the total mass of composition A.

(Additive)
Composition A may contain additives other than the above components. Additives include cross-linking agents, low-molecular-weight compounds, polymerization initiators, surfactants, UV (ultraviolet) absorbers, reaction sensitizers, and leveling agents.

-Crosslinking agent-
Composition A preferably contains a cross-linking agent. By forming an alignment film using composition A containing a cross-linking agent, dissolution or swelling due to the solvent contained in the optically anisotropic layer composition can be suppressed, and mechanical strength can be imparted to the alignment film.
Cross-linking agents include monomers capable of chain polymerization and polyaddition type compositions.

Chain polymerizable monomers include (meth)acrylate compounds, epoxy compounds, and oxetane compounds. A polyfunctional monomer is preferable from the viewpoint of increasing the film strength. Further, the photo-orientable polymer described above may be modified with a copolymerizable functional group so as to be copolymerizable with these cross-linking agents.

When the composition A contains a cross-linking agent, a cross-linking accelerator that accelerates the cross-linking reaction or a cross-linking initiator that initiates the cross-linking reaction may be added to the composition A as necessary during the cross-linking reaction. When the composition A contains a cross-linking agent, the composition A should contain at least one of a cross-linking accelerator and a cross-linking initiator from the viewpoint of increasing the productivity of the optical film by obtaining a stable and uniform photo-alignment film. is preferred.
In particular, when a monomer capable of chain polymerization is used as the cross-linking agent, it is preferable to use various polymerization initiators together as the cross-linking initiator. Examples of such crosslinking initiators include photoradical generators and thermal radical generators when the chain-polymerizable monomer is a (meth)acrylate compound, and when the chain-polymerizable monomer is an epoxy compound or an oxetane compound. In some cases, photocation generators, thermal cation generators and thermal anion generators are included. Moreover, when using a photo-radical generator and a photo-cation generator, you may use a sensitizer together.

The amount of the cross-linking agent to be added is preferably 25 to 70% by mass, more preferably 40 to 60% by mass, based on the total solid content of the alignment film composition.
The solid content is a material that constitutes the alignment film, and means all components of the alignment film composition except the solvent. It shall be treated as a solid content.

-Low molecular compound-
Composition A may contain a low-molecular-weight compound. Examples of low-molecular-weight compounds include compounds having a molecular weight smaller than that of the alignment agent. Among them, a low-molecular-weight compound having a cinnamate group is preferable in terms of improving the alignment of the alignment film.
The molecular weight of the low molecular weight compound is preferably 200-500, more preferably 200-400.

Examples of low-molecular-weight compounds having a cinnamate group include compounds represented by the following formula (B1).

Here, in formula (B1), a represents an integer of 0 to 5, R ¹ represents a hydrogen atom or a monovalent organic group, and R ² represents a monovalent organic group. When a is 2 or more, a plurality of R ¹ may be the same or different.
The monovalent organic group for R ¹ is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, and still more preferably a methoxy group and an ethoxy group.
As the monovalent organic group for R ² , a chain alkyl group having 1 to 20 carbon atoms is preferable, and a branched alkyl group having 1 to 10 carbon atoms is more preferable.
In addition, a is preferably 1, and R ¹ is preferably at the para position.

Examples of the compound represented by the formula (B1) include octyl cinnamate, ethyl-4-isopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate, methyl-2,4-diisopropyl cinnamate, propyl-p -methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, 2-ethylhexyl-p-methoxycinnamate, 2-ethoxyethyl-p-methoxycinnamate, 2-hexyldecanyl-p- Methoxycinnamate and cyclohexyl-p-methoxycinnamate.

The content of the low-molecular compound is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of solvent A.

<Procedure of step 1>
Step 1 is a step of applying composition A onto a substrate to form a coating film for forming an alignment film.
The coating method in step 1 is not particularly limited, and a method capable of coating the coating film of composition A to a desired thickness can be appropriately selected from known coating methods. Application methods include, for example, spin coating, die coating, wire bar coating (bar coating), gravure coating, flexographic printing, and inkjet printing.

A drying step for drying the coating film of composition A formed on the substrate may be provided between step 1 and step 2.
The drying method in the drying step is not particularly limited as long as it is a method of drying the coating film to remove the solvent A, and a known drying method can be applied. mentioned.
When the composition A contains a cross-linking agent, it is preferable to carry out a drying step in order to promote the cross-linking reaction between the alignment agent and the cross-linking agent.

[Step 2]
Step 2 is a step of applying an orientation treatment to the coating film formed in Step 1 to form an orientation film. The alignment film formed in step 2 has an alignment regulating force that aligns the liquid crystal compound contained in the optically anisotropic layer.
The alignment treatment performed in step 2 is not particularly limited as long as it is a method of imparting an alignment function to the alignment agent contained in the coating film. selected.

Among them, it is preferable to perform a photo-alignment treatment of irradiating polarized light to the coating film of the composition A containing the above photo-alignment material (more preferably a polymer having a photo-alignment group) as an alignment agent.
In the photo-alignment treatment, the polarized light to be irradiated is not particularly limited, and examples thereof include linearly polarized light, circularly polarized light, and elliptically polarized light, with linearly polarized light being preferred.
Moreover, the “oblique direction” in which non-polarized light is irradiated is a direction inclined at a polar angle θ (0<θ<90°) with respect to the normal line direction of the coating film surface. The direction of irradiation with unpolarized light can be appropriately selected according to the purpose, but the polar angle θ is preferably 20 to 80°.

Irradiation light includes, for example, ultraviolet rays, near-ultraviolet rays, and visible rays, and near-ultraviolet rays within the wavelength range of 250 to 450 nm are preferred.
Examples of light sources for irradiation light include xenon lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, and metal halide lamps. By using an interference filter and/or a color filter for ultraviolet light or visible light obtained from such a light source, the wavelength range of the irradiated light can be restricted. Also, by using a polarizing filter and/or a polarizing prism for the light from these light sources, linearly polarized light can be obtained.

The integrated ^light intensity of the irradiation light is not particularly limited as long as it is an amount capable of imparting an alignment regulating force to the alignment agent ^.
The illuminance of the irradiation light is preferably 0.1 to 300 mW/cm ² , more preferably 1 to 100 mW/cm ² .

<Characteristics of Alignment Film>
The thickness of the alignment film formed in steps 1 and 2 is not particularly limited as long as the alignment function is exhibited, but it is preferably 0.05 to 3 μm, more preferably 0.1 to 1 μm, and more preferably 0.1 to 0.1 μm. 5 μm is more preferred, and 0.1 to 0.3 μm is particularly preferred. Within this range, an excellent orientation regulating force can be exhibited, and the effect of suppressing foreign matter defects is high.

[Step 3]
Step 3 is a step of applying a composition containing a liquid crystal compound having a polymerizable group onto the alignment film formed in step 2 to form a composition layer. By carrying out this step, a composition layer to be subjected to an orientation treatment, which will be described later, is formed.
First, the materials used in this process will be described in detail, and then the procedure of the process will be described in detail.

<Composition for optically anisotropic layer>
The composition for an optically anisotropic layer (hereinafter also referred to as "composition B") used in step 3 contains a liquid crystal compound having a polymerizable group (hereinafter simply referred to as "liquid crystal compound"). Composition B contains, in addition to the liquid crystal compound, a chiral agent, a solvent, and other components used as necessary (e.g., polymerization initiators, polymerizable monomers, surfactants, polymers, leveling agents, etc.). ) may be included.

(Liquid crystal compound having a polymerizable group)
Composition B used in step 3 contains a liquid crystal compound having a polymerizable group.
The type of liquid crystal compound is not particularly limited. Liquid crystal compounds can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (discotic liquid crystal compound) according to their shape. In addition, liquid crystal compounds can be classified into a low-molecular-weight type and a high-molecular-weight type. A polymer refers to a polymer having a degree of polymerization of 100 or more (polymer physics, phase transition dynamics, by Masao Doi, page 2, Iwanami Shoten, 1992).
Although any liquid crystal compound can be used in this production method, a rod-like liquid crystal compound or a discotic liquid crystal compound is preferably used, and a rod-like liquid crystal compound is more preferably used. Two or more rod-like liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a discotic liquid crystal compound may be used.
As the rod-like liquid crystal compound, for example, the liquid crystal compounds described in JP-A-11-513019 or paragraphs 0026 to 0098 of JP-A-2005-289980 can be preferably used.
As the discotic liquid crystal compound, for example, the liquid crystal compounds described in paragraphs 0020 to 0067 of JP-A-2007-108732 or paragraphs 0013 to 0108 of JP-A-2010-244038 can be preferably used.

The type of polymerizable group possessed by the liquid crystal compound is not particularly limited, and is preferably a functional group capable of an addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, a (meth)acryloyl group, and a vinyl group. , a styryl group, or an allyl group are more preferred.

The optically anisotropic layer formed in steps 3 to 5 of this production method is formed by fixing a liquid crystal compound having a polymerizable group (a rod-like liquid crystal compound or a discotic liquid crystal compound having a polymerizable group) by polymerization or the like. It is a formed layer and no longer needs to exhibit liquid crystallinity after the optically anisotropic layer is formed.

The content of the liquid crystal compound in composition B is not particularly limited, but is preferably 60% by mass or more, more preferably 70% by mass, based on the total mass of the solid content of composition B in terms of easy control of the alignment state of the liquid crystal compound. The above is more preferable. Although the upper limit is not particularly limited, it is preferably 99% by mass or less, more preferably 97% by mass or less.
In addition, the solid content of the composition B means all the components contained in the composition B other than the solvent.

(chiral agent)
Composition B may contain a chiral agent, and preferably contains a chiral agent in that the liquid crystal compound can be easily twisted and oriented.
Chiral agents may be liquid crystalline or non-liquid crystalline. Chiral agents often contain an asymmetric carbon atom, but may be an axially or planarly chiral compound that does not contain an asymmetric carbon atom.
Moreover, the chiral agent may be a photosensitive chiral agent whose helical inductive force changes upon irradiation with light, or may be a chiral agent whose helical inductive force does not change upon irradiation with light.
The helical twisting power (HTP) of the chiral agent is a factor that indicates the helical orientation ability represented by the following formula (X).
Formula (X) HTP = 1/(Length of helical pitch (unit: μm) × Concentration of chiral agent with respect to liquid crystal compound (% by mass)) [μm ⁻¹ ]
The length of the helical pitch means the length of the pitch P (= helical period) of the helical structure of the cholesteric liquid crystal phase, and can be measured by the method described on page 196 of Liquid Crystal Handbook (published by Maruzen Co., Ltd.).

Photosensitive chiral agents include so-called photoreactive chiral agents. A photoreactive chiral agent is a compound that has a chiral site and a photoreactive site that undergoes a structural change upon irradiation with light, and that, for example, greatly changes the torsional force of a liquid crystal compound in accordance with the amount of irradiation.
Examples of photoreactive sites that undergo structural changes due to light irradiation include photochromic compounds (Kingo Uchida, Masahiro Irie, Kagaku Kogyo, vol.64, 640p, 1999, Kingo Uchida, Masahiro Irie, Fine Chemicals, vol.28(9), 15p , 1999). Further, the structural change means decomposition, addition reaction, isomerization, racemization, [2+2] photocyclization, dimerization reaction, etc. caused by light irradiation to the photoreactive site, and the structural change is irreversible. There may be. Moreover, as a chiral site, for example, Hiroyuki Nohira, Kagaku Sosetsu, No. 22 Liquid Crystal Chemistry, 73p:1994.

Examples of the photosensitive chiral agent include photoreactive chiral agents described in paragraphs 0044 to 0047 of JP-A-2001-159709, optically active compounds described in paragraphs 0019-0043 of JP-A-2002-179669, Optically active compounds described in paragraphs 0020 to 0044 of JP-A-2002-179633, optically active compounds described in paragraphs 0016-0040 of JP-A-2002-179670, paragraphs 0017-0050 of JP-A-2002-179668 optically active compounds described in, optically active compounds described in paragraphs 0018 to 0044 of JP-A-2002-180051, optically active isosorbide derivatives described in paragraphs 0016-0055 of JP-A-2002-338575, JP-A-2002-080478 The photoreactive optically active compounds described in paragraphs 0023 to 0032 of JP-A-2002-200353, the photoreactive chiral agents described in paragraphs 0019 to 0029 of JP-A-2002-080851, and the paragraphs 0022-0049 of JP-A-2002-179681. The optically active compound described in, the optically active compound described in paragraphs 0015 to 0044 of JP-A-2002-302487, the optically active polyester described in paragraphs 0015-0050 of JP-A-2002-338668, JP-A-2003-055315 Binaphthol derivatives described in paragraphs 0019 to 0041 of the publication, optically active fulgide compounds described in paragraphs 0008 to 0043 of JP-A-2003-073381, optical activity described in paragraphs 0015-0057 of JP-A-2003-306490 Isosorbide derivatives, optically active isosorbide derivatives described in paragraphs 0015 to 0041 of JP-A-2003-306491, optically active isosorbide derivatives described in paragraphs 0015-0049 of JP-A-2003-313187, JP-A-2003-313188 Optically active isomannide derivatives described in paragraphs 0015 to 0057 of JP-A-2003-313189, optically active isosorbide derivatives described in paragraphs 0015-0049 of JP-A-2003-313292, optically active described in paragraphs 0015-0052 of JP-A-2003-313292 Examples include polyester/amide, optically active compounds described in paragraphs 0012 to 0053 of WO2018/194157, and optically active compounds described in paragraphs 0020 to 0049 of JP-A-2002-179682.

The chiral agent preferably has any partial structure selected from a binaphthyl partial structure, an isosorbide partial structure (a partial structure derived from isosorbide), and an isomannide partial structure (a partial structure derived from isomannide). The binaphthyl partial structure, the isosorbide partial structure, and the isomannide partial structure each intend the following structures.
The part where the solid line and the dashed line in the binaphthyl partial structure are parallel represents a single bond or a double bond. In the structures shown below, * represents a bonding position.

As the chiral agent, a compound represented by formula (C) is preferred.
Formula (C) RLR
Each R independently represents a group having at least one moiety selected from the group consisting of a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety and a stilbene moiety.
L is a divalent linking group formed by removing two hydrogen atoms from the binaphthyl partial structure, a divalent linking group consisting of the isosorbide partial structure, or a divalent linking group consisting of the isomannide partial structure. represents In addition, * represents a binding position.

The chiral agent contained in the composition B may be of one type or a combination of two or more types.
The content of the chiral agent in composition B can be appropriately set according to the properties of the optically anisotropic layer to be formed (for example, retardation and wavelength dispersion). Since the twist angle of the liquid crystal compound in the optically anisotropic layer greatly depends on the type and concentration of the chiral agent added, a desired twist angle can be obtained by adjusting these factors.

The content of the chiral agent in composition B (the total content when two or more chiral agents are used) is, for example, 5.0% by mass or less, and 4.0% by mass with respect to the total mass of the liquid crystal compound. The following is preferable, 2.0% by mass or less is more preferable, and 1.0% by mass or less is even more preferable. Although the lower limit is not particularly limited, it is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more.

(other ingredients)
Composition B may contain components other than the liquid crystal compound and the chiral agent.
For example, composition B may contain a polymerization initiator. When the composition B contains a polymerization initiator, polymerization of the liquid crystal compound having a polymerizable group proceeds more efficiently in the composition layer formed in step 3.
Polymerization initiators include known polymerization initiators, including photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred.
Although the content of the polymerization initiator in composition B is not particularly limited, it is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the solid content of composition B.

Composition B may contain a polymerizable monomer different from the liquid crystal compound. Polymerizable monomers include radically polymerizable compounds and cationically polymerizable compounds, and polyfunctional radically polymerizable monomers are preferred. Examples of polymerizable monomers include polymerizable monomers described in paragraphs 0018 to 0020 of JP-A-2002-296423.
Although the content of the polymerizable monomer in composition B is not particularly limited, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, based on the total mass of the liquid crystal compound.

Composition B may contain a surfactant. Surfactants include conventionally known compounds, and fluorine-based compounds are preferred. Examples of surfactants include compounds described in paragraphs 0028 to 0056 of JP-A-2001-330725 and compounds described in paragraphs 0069-0126 of JP-A-2005-062673.

Composition B may contain a polymer. Polymers include cellulose esters. Cellulose esters include compounds described in paragraph 0178 of JP-A-2000-155216.
Although the content of the polymer in composition B is not particularly limited, it is preferably 0.1 to 10% by mass, more preferably 0.1 to 8% by mass, based on the total mass of the liquid crystal compound.

The composition layer may contain a leveling agent.
Although the leveling agent is not particularly limited, a fluorine-based leveling agent or a silicon-based leveling agent is preferable, and a fluorine-based leveling agent is more preferable.
The fluorine-based leveling agent is a leveling agent having a fluorine atom, and preferably has a fluoroaliphatic group.
The fluorine-based leveling agent preferably has a repeating unit represented by the following formula (1).

In formula (1), R ¹ represents a hydrogen atom, a halogen atom, or a methyl group.
L ¹ represents a single bond or a divalent linking group. The divalent linking group is not particularly limited, and examples thereof include divalent hydrocarbon groups (e.g., alkylene groups having 1 to 10 carbon atoms, alkenylene groups having 1 to 10 carbon atoms, and alkynylene groups having 1 to 10 carbon atoms. and divalent aromatic hydrocarbon groups such as arylene groups), divalent heterocyclic groups, -O-, -S-, -NH-, -CO-, Alternatively, a group combining these (e.g., -CO-O-, -O-divalent hydrocarbon group -, -(O-divalent hydrocarbon group) _m -O- (m is an integer of 1 or more ), and —O—CO-divalent hydrocarbon group—, etc.).
n represents an integer of 1 to 18, preferably an integer of 4 to 12, more preferably an integer of 6 to 8.
X is a hydrogen atom or a fluorine atom.

As the repeating unit represented by formula (1), a repeating unit represented by the following formula (2) is preferable.

In formula (2), the definitions of R ¹ , n and X are the same as the definitions of the groups in formula (1) above.
Y represents an oxygen atom, a sulfur atom or -N(R ² )-. R ² represents a hydrogen atom or an optionally substituted alkyl group having 1 to 8 carbon atoms.
m represents an integer of 1-6, preferably an integer of 1-3.

The fluorine-based leveling agent may have only one type of repeating unit represented by formula (1), or may have two or more types.
The content of the repeating unit represented by formula (1) in the fluorine-based leveling agent is not particularly limited, and since the distribution of the leveling agent described later is likely to be formed, with respect to all repeating units of the fluorine-based leveling agent, 20 to 100% by mass is preferred, and 30 to 95% by mass is more preferred.
When the fluorine-based leveling agent has two or more types of repeating units represented by formula (1), the total content is preferably within the above range.

The fluorine-based leveling agent may have repeating units other than the repeating unit represented by formula (1).
Other repeating units may include, for example, repeating units having a hydrophilic group (eg, poly(oxyalkylene) group, hydroxy group, etc.).
The fluorine-based leveling agent may have a repeating unit represented by formula (3).

^R3 represents a hydrogen atom, a halogen atom, or a methyl group.
^L2 represents a single bond or a divalent linking group. The definition of the divalent linking group is as described above.
^L3 represents an alkylene group. The alkylene group preferably has 2 to 3 carbon atoms.
p represents an integer of 4-20, preferably an integer of 5-15.
^R4 represents a hydrogen atom or a substituent. Examples of substituents include an alkyl group, an alkoxy group, a halogen atom, an aryl group, a cyano group, a hydroxy group, an amino group, or a group combining these (eg, -alkylene group -OH).

The fluorine-based leveling agent may have only one type of repeating unit represented by formula (3), or may have two or more types.
The content of the repeating unit represented by formula (3) in the fluorine-based leveling agent is not particularly limited, but is preferably 2 to 70% by mass, more preferably 5 to 60% by mass, based on the total repeating units of the fluorine-based leveling agent. is more preferred.
When the fluorine-based leveling agent has two or more types of repeating units represented by formula (3), the total content is preferably within the above range.

Although the weight average molecular weight of the fluorine-based leveling agent is not particularly limited, it is preferably from 3,000 to 30,000, more preferably from 5,000 to 25,000.

As the silicon-based leveling agent, a leveling agent containing a plurality of dialkylsilyloxy units as repeating units is preferred.

The content of the leveling agent in the composition is not particularly limited, but is preferably 0.010 to 5.0% by mass, more preferably 0.020 to 2.0% by mass, based on the total mass of the solid content of the composition. .

Composition B may contain, in addition to the components described above, an additive (alignment control agent) that promotes horizontal or vertical alignment of the liquid crystal compound so as to bring the liquid crystal compound into a horizontal or vertical alignment state.

<Procedure of step 3>
In step 3, the procedure of applying the composition B to form a composition layer is not particularly limited, and a method of applying the composition B on the alignment film and optionally performing a drying treatment (hereinafter referred to as Also simply referred to as a “coating method”).

The coating method in step 3 is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating.
In step 3, if necessary, a drying treatment for drying the composition layer formed by coating may be performed. Removal of the solvent from the composition layer can be facilitated by performing the drying treatment.

The thickness of the composition layer formed in step 3 is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, even more preferably 0.5 to 10 μm.

[Step 4]
Step 4 is a step of subjecting the composition layer formed in step 3 to orientation treatment to twist-align the liquid crystal compound in the composition layer with the thickness direction as the helical axis. By carrying out this step, the liquid crystal compound in the composition layer is twisted along the helical axis extending along the thickness direction of the composition layer, resulting in a predetermined alignment state.

As the heat treatment conditions, optimum conditions are selected according to the liquid crystal compound used.
The heating temperature is often 10 to 250°C, preferably 40 to 150°C, more preferably 50 to 130°C.
The heating time is often 0.1 to 60 minutes, preferably 0.2 to 5 minutes.

The alignment state of the liquid crystal compound aligned in step 4 and fixed in step 5 will be described in detail later.

[Step 5]
Step 5 is a step of curing the composition layer after step 4 to fix the alignment state of the liquid crystal compound to form an optically anisotropic layer. By carrying out this step, the alignment state of the liquid crystal compound in the composition layer is fixed, and an optically anisotropic layer is formed in which the liquid crystal compound is aligned at a predetermined twist angle with the thickness direction as the helical axis.
An optical film having a substrate, an oriented film, and an optically anisotropic layer can be obtained by performing Steps 1 to 5 above.

The curing treatment method is not particularly limited, and includes photocuring treatment and heat curing treatment. Among them, light irradiation treatment is preferable, and ultraviolet irradiation treatment is more preferable.
A light source such as an ultraviolet lamp is used for ultraviolet irradiation.
Although the irradiation amount of light (for example, ultraviolet rays) is not particularly limited, it is preferably about 100 to 800 mJ/cm ² .
The atmosphere for the light irradiation is not particularly limited, and the light irradiation may be carried out in the air, or the light irradiation may be carried out in an inert atmosphere.

When the photocuring treatment is performed as the curing treatment, the temperature conditions for the photocuring treatment are not particularly limited as long as the orientation state of the liquid crystal compound oriented in step 4 is maintained. When the heat treatment is performed in step 4, the temperature difference between the heat treatment in step 4 and the photo-curing treatment in step 5 is preferably within 100°C, more preferably within 80°C.
The temperature during the heat treatment in step 4 and the temperature during the photo-curing treatment in step 5 are preferably the same, or the temperature during the photo-curing treatment is preferably lower.

In the optically anisotropic layer obtained by carrying out step 5, the alignment state of the liquid crystal compound is fixed.
The "fixed" state is the most typical and preferable mode in which the orientation of the liquid crystal compound is maintained. Specifically, the layer has no fluidity in the temperature range of usually 0 to 50° C., and -30 to 70° C. under more severe conditions, and can be oriented by an external field or force. It is more preferable to be in a state in which the fixed alignment form can be stably maintained without causing any change.
In the optically anisotropic layer, the final composition in the layer does not need to exhibit liquid crystallinity.

<Characteristics of Optically Anisotropic Layer>
The optically anisotropic layer is a layer in which the orientation state of the liquid crystal compound twisted along the helical axis extending along the thickness direction is fixed.
The twisted orientation of the liquid crystal compound in the optically anisotropic layer may be a left-handed twisted orientation or a right-handed twisted orientation. In other words, the direction of the twisted alignment of the liquid crystal compound may be either left-handed (counterclockwise twisted) or right-handed (clockwise twisted).

The twist alignment of the liquid crystal compound means that the liquid crystal compound present from one surface (principal surface) to the other surface (principal surface) of the optically anisotropic layer with the thickness direction of the optically anisotropic layer as the axis. intended to twist. Therefore, the twist angle with the thickness direction of the liquid crystal compound in the optically anisotropic layer as the helical axis (hereinafter also simply referred to as "twist angle") is, from one surface of the optically anisotropic layer to the other surface, It means the angle at which the molecular axis of the liquid crystal compound (major axis in the case of a rod-like liquid crystal compound) rotates within the plane.

In the optically anisotropic layer, the twist angle with the thickness direction of the liquid crystal compound as the helical axis is more than 0° and 180° or less. When the twist angle of the liquid crystal compound in the optically anisotropic layer is within the above range, an optical film having more excellent wet heat durability can be obtained.
In the optical film, when the liquid crystal compound in the optically anisotropic layer is in a homogeneous alignment state with a twist angle of 0°, the optically anisotropic layer expands and contracts greatly in one direction with respect to the substrate in a high humidity and heat environment, resulting in , it is speculated that cracks or delamination tend to occur. On the other hand, in an optical film having a twist angle of the liquid crystal compound within the above range and a predetermined alignment film between the substrate and the optically anisotropic layer, the stretching direction of the optically anisotropic layer is biased. It is presumed that cracking and peeling can be suppressed in a high humidity and heat environment.

The absolute value of the twist angle of the liquid crystal compound in the optically anisotropic layer is preferably 3 to 90°, more preferably 20 to 60°, in that the optically anisotropic layer can be suitably applied to a circularly polarizing plate.
When the twist angle of the liquid crystal compound in the optically anisotropic layer is within the above range and the Re(550) of the substrate is 67.5 to 127.5 nm (more preferably 82.5 to 112.5 nm) , is preferable in terms of better antireflection performance.

The optical properties of the optically anisotropic layer to be formed are not particularly limited, and optimal values are selected according to the application.
Where d is the thickness of the optically anisotropic layer and Δn is the refractive index anisotropy of the optically anisotropic layer measured at a wavelength of 550 nm, the optically anisotropic layer can be suitably applied to a circularly polarizing plate. and d (Δnd) is preferably 317 to 377 nm, more preferably 327 to 367 nm, even more preferably 337 to 357 nm.
Here, the refractive index anisotropy Δn means the refractive index anisotropy of the optically anisotropic layer (the difference between the refractive index on the in-plane slow axis and the refractive index on the in-plane fast axis).
The product Δnd of the refractive index anisotropy Δn and the thickness d of the optically anisotropic layer is within the above range, and the Re(550) of the substrate is 67.5 to 127.5 nm (more preferably 82.5 ~112.5 nm) is preferred in terms of better antireflection performance.

The alignment state (twist angle, etc.) and optical properties (slow axis, etc.) of the liquid crystal compound in the optically anisotropic layer were measured using Axoscan (polarimeter device) from Axometrics and the company's device analysis software (Multi-Layer Analysis). can be measured using

Although the thickness of the optically anisotropic layer is not particularly limited, it is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, even more preferably 0.2 to 6.0 μm.

[Optical film]
Hereinafter, as one embodiment of the optical film obtained by the present production method, an optical film (hereinafter also referred to as "specific optical film") that satisfies the requirements described later will be described with reference to the drawings.
FIG. 1 shows an example of the configuration of the specific optical film. The specific optical film 10 shown in FIG. 1 has a substrate 20, an alignment film 30, and an optically anisotropic layer 40 in this order. The first surface 12 is the surface (principal surface) of the specific optical film 10 on the optically anisotropic layer 40 side, and the second surface 14 is the surface (principal surface) of the specific optical film 10 on the substrate 20 side. .
The alignment film 30 contains an alignment agent, and in the optically anisotropic layer 40, the liquid crystal compound having a polymerizable group has a twist angle of more than 0° and less than or equal to 180° with the thickness direction of the optically anisotropic layer 40 as the helical axis. is fixed in an orientation state twisted at .
Preferred aspects of the substrate 20, the alignment film 30 and the optically anisotropic layer 40 are as already explained.

Furthermore, the specific optical film satisfies requirements 1 and 2 below.
Requirement 1: In the specific optical film, analyze the components in the thickness direction of the specific optical film by time-of-flight secondary ion mass spectrometry while irradiating the ion beam from the first surface to the second surface of the specific optical film. In the profile in the thickness direction of the secondary ion intensity derived from the alignment agent obtained by Assuming that the closest position is position A and the position closest to the second surface is position B, the distance d1 between position A and position B is 100 nm or more.
Requirement 2: In the above profile, if the position C is closer to the second surface than the position B and exhibits a secondary ion intensity that is 20% of the maximum value of the secondary ion intensity derived from the alignment agent, then the position B The distance d2 and the distance d1 between and the position C satisfy the following formula (I).
0.3≤d2/d1≤0.82 (I)
A specific optical film that satisfies the requirements 1 and 2 is excellent in both liquid crystal orientation and wet heat durability.

The above requirements will be described in detail with reference to the drawings. It should be noted that the figures shown below are shown in a form different in scale from actual data so that the contents of the invention can be easily understood.
FIG. 2 shows an example of a profile obtained by analyzing components in the depth direction in each layer with TOF-SIMS while performing ion sputtering from the first surface to the second surface of the specific optical film. In the present specification, the depth direction is intended to mean the direction toward the second surface (surface on the substrate side) with reference to the first surface (surface on the side of the optically anisotropic layer) of the specific optical film. do.
In the profile in the depth direction shown in FIG. 2, the horizontal axis (in FIG. 2, the axis extending in the horizontal direction of the paper surface) represents the depth relative to the first surface of the specific optical film, and the vertical axis (in FIG. 2, the axis extending in the vertical direction of the paper surface) represents the secondary ion intensity derived from the alignment agent.
The TOF-SIMS method is specifically described in "Selection of Surface Analysis Techniques, Secondary Ion Mass Spectrometry" edited by The Surface Science Society of Japan, published by Maruzen Co., Ltd. (published in 1999).

The profile in FIG. 2 shows the depth in each layer by TOF-SIMS while ion sputtering from the first surface 12 to the second surface 14 of the specific optical film 10 placed on the substrate 20 shown in FIG. It corresponds to the result of analyzing the component in the horizontal direction. The position of 0 on the horizontal axis in FIG. 2 corresponds to the first surface 12 of the specific optical film 10 , and the position of E on the horizontal axis corresponds to the second surface 14 . That is, 0 to E on the horizontal axis correspond to the first surface 12 to the second surface 14 of the specific optical film 10 .
In addition, the specific optical film 10 shown in FIG. 1 corresponds to an example of the optical film manufactured by this manufacturing method.

When analyzing the components in the depth direction of a specific optical film with TOF-SIMS while irradiating an ion beam, after performing the component analysis in the surface depth region of 1 to 2 nm, further in the depth direction from 1 nm to several hundred nm A series of operations for digging in and performing component analysis for the next surface depth region of 1 to 2 nm is repeated.

The profile in the depth direction shown in FIG. 2 shows the result of the secondary ion intensity derived from the alignment agent.
In this specification, the “secondary ion intensity derived from the alignment agent” obtained from the profile in the depth direction detected by analyzing the component in the depth direction of the specific optical film by TOF-SIMS means the alignment agent is intended to be the intensity of fragment ions derived from

As shown in FIG. 2, when the ion beam is irradiated from the first surface to the second surface of the specific optical film and the TOF-SIMS method is used to analyze the component in the depth direction of the specific optical film, from a predetermined position, A secondary ion intensity derived from the alignment agent is observed, and the intensity gradually increases as the ion beam is irradiated in the depth direction. When the ion beam is irradiated further in the depth direction, the secondary ion intensity derived from the alignment agent reaches a maximum value and then gradually decreases.
In the profile shown in FIG. 2, the range in which the secondary ion strength derived from the alignment agent is high corresponds to the arrangement and thickness of the alignment film containing the alignment agent.

Next, in the profile obtained above, a baseline is drawn to determine the standard of secondary ion intensity. Specifically, as shown in FIG. 2, a baseline BL indicated by a thick dashed line is drawn, and the position of the vertical axis that intersects with the baseline BL is the position where the secondary ion intensity is 0, and this base coming BL is used as a reference. , determines the magnitude of the secondary ionic strength derived from the alignment agent.
In addition, as a method of drawing the baseline BL, a depth position corresponding to 1/10 of the thickness of the entire specific optical film from the first surface to the second surface of the specific optical film is set as the reference position SP1, and the specific When the depth position corresponding to 9/10 of the thickness of the entire optical film is defined as the reference position SP2, the average value of the secondary ion intensity derived from the alignment agent located between the reference position SP1 and the reference position SP2 is obtained. , subtract the baseline BL at its mean value. That is, the average value of the secondary ion intensity derived from the alignment agent in the region between the reference position SP1 and the reference position SP2 is calculated, and a straight line indicating the average value is drawn along the horizontal axis, and this straight line is used as the baseline. Let it be BL.

Next, in the profile obtained above, the maximum secondary ion strength derived from the alignment agent is defined as _Smax , and the secondary ion strength at 80% of _Smax is defined as _S80 . Let position A be the position closest to the first surface 12, and position B be the position closest to the second surface, among the positions showing the secondary ion intensity _S80 in the above profile.
At this time, in the specific optical film, the distance d1 between position A and position B in the profile is 100 nm or more (requirement 1).

Next, the secondary ion strength at 20% of the maximum value _{Smax of} the secondary ion strength derived from the alignment agent is defined as _S20 . Position C is a position close to the 2nd surface.
At this time, in the specific optical film, the distance d2 between the position B and the position C in the profile and the distance d1 satisfy the following formula (I) (requirement 2).
0.3≤d2/d1≤0.82 (I)
By satisfying the requirements as described above, it is possible to obtain an optical film having excellent liquid crystal orientation in the optically anisotropic layer and excellent wet heat durability.

The distribution state of the alignment agent as described above can be realized, for example, by the procedure of the above optical film manufacturing method. More specifically, in the manufacturing method having steps 1 to 5 above, a composition A containing a solvent and an alignment agent having an SP value such that the difference from the SP value of the base material is within a predetermined range is prepared. By using, adjusting the thickness of the coating film of composition A, and further adjusting the drying conditions of the coating film, in the optical film produced, both at the boundary between the substrate and the alignment film A region in which the components are appropriately mixed can be formed, and the distribution state of the alignment agent can be realized.

The above distance d1 is preferably 150 nm or more in that the effects of the present invention are more excellent. Although the upper limit of the distance d1 is not particularly limited, it is preferably 3000 nm or less, more preferably 500 nm or less, in terms of reducing the load for drying the coating film.
Moreover, the above distances d1 and d2 preferably satisfy the following formula (II), and more preferably satisfy the following formula (III), from the viewpoint that the effects of the present invention are more excellent.
0.40≦d2/d1≦0.80 (II)
0.65≦d2/d1≦0.80 (III)

[Optical laminate]
The optical film can be combined with various members. For example, the optical film may be combined with other optical members to form an optical laminate.
Other optical members included in the optical laminate are not particularly limited, and examples thereof include polarizers, A plates (positive A plate and negative A plate), and C plates (positive C plate and negative C plate).
The above optical layered body can be produced, for example, by bonding an optical film and another optical member together using various adhesives. Examples of adhesives include ultraviolet curable resins, thermosetting resins, and pressure sensitive adhesives.

[Optical film with polarizer]
FIG. 3 shows an example of a specific configuration of the optical layered body.
A polarizer-equipped optical film 50 shown in FIG. 3 is an example of the above-described optical layered body. and a polarizer 52 laminated on the optically anisotropic layer 40 side.
In this specification, the term "optical film with a polarizer" means an optical laminate having at least the optical film according to the present invention and a polarizer. An optical film with a polarizer can be used as a polarizing plate in various display devices.

The polarizer 52 used in the polarizer-equipped optical film 50 may be a member having a function of converting natural light into specific linearly polarized light, and examples thereof include an absorption polarizer.
The type of the polarizer 52 is not particularly limited, and known polarizers can be used. Examples thereof include iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are often produced by allowing polyvinyl alcohol to adsorb iodine or a dichroic dye and stretching the resultant.
A protective film (not shown) may be arranged on one side or both sides of the polarizer 52 .

In the optical film 50 with polarizer, the positional relationship when laminating the optical film 10 and the polarizer 52 is not particularly limited. The absolute value of the angle formed by the axis and the slow axis (in-plane slow axis) of the substrate 20 is preferably 0±10° or 90±10°, and preferably 0±5° or 90±5°. It is more preferable to have

In addition, regarding the alignment state of the liquid crystal compound in the optically anisotropic layer 40 of the optical film 50 with polarizer, the alignment axis (in-plane slow axis) of the liquid crystal compound on the surface on the polarizer side and the slow phase axis of the substrate 20 The absolute value of the angle formed with the axis is preferably 90±20°, more preferably 90±10°, from the viewpoint of better antireflection performance.
The absolute value of the twist angle of the liquid crystal compound in the optically anisotropic layer 40 of the optical film 50 with polarizer is preferably within the preferred range described above.
The absolute value of the angle formed by the alignment axis of the liquid crystal compound on the surface of the optically anisotropic layer 40 on the polarizer 52 side and the absorption axis of the polarizer 52 is 0°±20° in terms of better antireflection performance. Alternatively, 90°±20° is preferable, and 0°±10° or 90°±10° is more preferable.

In the optically anisotropic layer 40, the direction in which the liquid crystal compound is twisted along the thickness direction is not particularly limited. Optical anisotropy is obtained when the direction of twisting counterclockwise from the 30 side surface (second surface) toward the polarizer 52 side surface (first surface) of the optically anisotropic layer 40 is taken as a positive value. The direction of rotation of the liquid crystal compound in layer 40 may be positive (counterclockwise) or negative (clockwise).

FIG. 4 shows another example of a more specific configuration of the optical layered body.
The optical film 60 with a polarizer shown in FIG. 4 is another example of the above optical laminate, and includes a specific optical film 10 having a substrate 20, an alignment film 30 and an optically anisotropic layer 40 in this order, and a specific optical and a polarizer 62 laminated on the substrate 20 side of the film 10 .

In the optical film 60 with polarizer, the positional relationship when laminating the optical film 10 and the polarizer 62 is not particularly limited. is preferably 0±10° or 90±10°, more preferably 0±5° or 90±5°.
Depending on the application of the optical film 60 with polarizer, the angle formed by the slow axis of the substrate and the absorption axis of the polarizer is preferably 5 to 25°.

In the polarizer-equipped optical film 60, the absolute value of the angle formed by the alignment axis of the liquid crystal compound on the alignment film 30 side surface of the optically anisotropic layer 40 and the slow axis of the substrate 20 is the antireflection -10° to 10° is preferred, and -5° to 5° is more preferred, from the viewpoint of better performance.
The absolute value of the twist angle of the liquid crystal compound in the optically anisotropic layer 40 of the optical film 60 with polarizer is preferably within the preferred range described above.

The direction in which the liquid crystal compound in the optically anisotropic layer 40 of the optical film 60 with polarizer is twisted along the thickness direction is not particularly limited, and the optical film 60 with polarizer is observed from the optically anisotropic layer 40 side. At this time, the direction of twisting counterclockwise from the surface (second surface) of the optically anisotropic layer 40 on the alignment film 30 side toward the first surface 12 of the optically anisotropic layer 40 opposite to the alignment film 30 is a positive value, the rotation direction of the liquid crystal compound in the optically anisotropic layer 40 may be positive (counterclockwise) or negative (clockwise).

The method for producing the optical film with a polarizer is not particularly limited, and includes known methods. For example, there is a method of laminating the optical film obtained by this production method and a polarizer to obtain an optical film with a polarizer.

The optical film with a polarizer may further have a positive C plate having a retardation (Rth(550)) in the thickness direction at a wavelength of 550 nm of -150 to -50 nm. By further laminating a positive C plate on the optical film with a polarizer, an optical laminate can be obtained that can further suppress light leakage and coloring in the oblique direction of the display device.
Rth(550) of the positive C plate is, for example, −150 to −50 nm, preferably −130 to −60 nm, more preferably −120 to −70 nm.

Although the material constituting the positive C plate is not particularly limited, it is preferably formed from a composition containing a liquid crystal compound. Forming from a composition for an optically anisotropic layer containing a polymerizable liquid crystal compound is preferable from the viewpoint of increasing the durability over time and the degree of alignment order. Such a positive C plate can typically be obtained by vertically aligning a rod-shaped polymerizable liquid crystal compound contained in the composition for an optically anisotropic layer and fixing the alignment state by polymerization. Moreover, it can also be formed from a composition containing a side-chain type polymer liquid crystal compound as the liquid crystal compound.

Although the thickness of the positive C plate is not particularly limited, it is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, from the viewpoint of thinning. In addition, although the positive C plate alone may be provided by transfer or coating, other functional layers may be provided together with the positive C plate as required. Such functional layers include protective films, hard coat layers and cushion layers.

The optical film with a polarizer can be preferably used as a circularly polarizing plate.
The circularly polarizing plate having the above structure is used for antireflection applications in image display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), and cathode ray tube displays (CRTs). It is preferably used and can improve the contrast ratio of display light.
For example, there is a mode in which the above circularly polarizing plate is used on the light extraction surface side of the organic EL display device. In this case, the external light is linearly polarized by the polarizing film and then circularly polarized by passing through the optically anisotropic layer. When this light is reflected by the metal electrode, the circularly polarized state is reversed, and when it passes through the optically anisotropic layer again, it becomes linearly polarized light tilted 90° from the time of incidence, reaches the polarizing film and is absorbed. As a result, the influence of outside light can be suppressed.

Among others, the circularly polarizing plate is preferably applied to an organic EL display device. In other words, the above circularly polarizing plate is preferably arranged on an organic EL panel of an organic EL display device and applied for antireflection purposes.
An organic EL panel is a member in which a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer are formed between a pair of electrodes of an anode and a cathode. , an electron-transporting layer, a protective layer, and the like, and each of these layers may have other functions. Various materials can be used to form each layer.

In addition, the optical film with a polarizer has the absorption axis of the polarizer, the arrangement of the slow axis of the substrate and the absorption axis of the polarizer, and the alignment state (for example, twist angle) of the liquid crystal compound in the optically anisotropic layer. etc.) and by controlling the wavelength dispersion, it can be used as various optical compensation films.

[Another aspect of the optical layered body]
The optical laminate having the optical film is not limited to the optical film with a polarizer shown in FIGS. 3 and 4 above.
Another embodiment of the optical laminate having the optical film is selected from the group consisting of the optical film, an A plate (positive A plate and negative A plate), and a C plate (positive C plate and negative C plate). A laminate having at least one Among them, the C plate is preferable because it can be easily applied to various uses (for example, a circularly polarizing plate) to be described later.

In addition, in this specification, the A plate and the C plate are defined as follows.
There are two types of A plates, a positive A plate (positive A plate) and a negative A plate (negative A plate). ) is nx, the refractive index in the direction orthogonal to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, the positive A plate satisfies the relationship of formula (A1). and the negative A plate satisfies the relationship of formula (A2). A positive A plate shows a positive Rth value, and a negative A plate shows a negative Rth value.
Formula (A1) nx>ny≈nz
Formula (A2) ny<nx≈nz
Note that the above "≈" includes not only the case where both are completely the same, but also the case where both are substantially the same. “Substantially the same” means, for example, that (ny−nz)×d (where d is the thickness of the film) is −10 to 10 nm, preferably −5 to 5 nm, and “ny≈nz”. and (nx−nz)×d of −10 to 10 nm, preferably −5 to 5 nm is also included in “nx≈nz”.
There are two types of C plates, a positive C plate (positive C plate) and a negative C plate (negative C plate), the positive C plate satisfies the relationship of formula (C1), and the negative C plate It satisfies the relationship of formula (C2). A positive C plate shows a negative Rth value, and a negative C plate shows a positive Rth value.
Formula (C1) nz>nx≈ny
Formula (C2) nz<nx≈ny
Note that the above "≈" includes not only the case where both are completely the same, but also the case where both are substantially the same. "Substantially the same" means, for example, that (nx - ny) x d (where d is the thickness of the film) is 0 to 10 nm, preferably 0 to 5 nm. be
Although the range of the absolute value of the retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, it is preferably 5 to 300 nm, more preferably 10 to 200 nm.

The method for producing the optical layered body is not particularly limited, and includes known methods. For example, there is a method of obtaining an optical laminate by laminating the optical film obtained by this production method and another optical member (for example, a C plate). As the lamination method, another optical member prepared separately may be attached to the optical film obtained by this production method, or another optical member may be formed on the optical film obtained by this production method. may be applied to form other optical members.

The optical film can be applied to various optical laminates without being limited to the above embodiments. Examples thereof include polarizing plates with optical compensation layers for liquid crystal display devices, polarized sunglasses, brightness enhancement plates, decorative films, viewing angle limiting films, and light control films. The optical properties and average slow axis direction of the optical film can be changed variously according to the application without departing from the gist of the present invention.

[Image display device]
The optical film produced by this production method and the above optical layered body can be suitably used for an image display device. For example, by appropriately cutting the optical film with a polarizer and mounting it on a display device, an image display device with excellent display quality can be obtained. In particular, by disposing the optical film with polarizer between the liquid crystal display panel and the polarizer to function as an optical compensation film, it is possible to improve the viewing angle characteristics of the liquid crystal display device. Further, the optical film produced by this production method can be provided in an organic EL display device and used as an antireflection film for preventing internal reflected light.

Although the method for producing an optical film, the optical film, and the optical laminate of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. may be performed.

EXAMPLES The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. Materials, usage amounts, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

[Example 1]
[Preparation of base material]
Pellets of a thermoplastic norbornene polymer (manufactured by Nippon Zeon Co., Ltd., trade name “ZEONOR1420R”) were dried at 90° C. for 5 hours. The dried pellets were fed into the extruder and melted in the extruder. The melted pellets were passed through a polymer pipe and a polymer filter and extruded into a sheet from a T-die onto a casting drum. The sheet of extruded melt was cooled and wound up to give a roll of unstretched substrate with a width of 1490 mm.

The unstretched base material obtained above was pulled out from the rolls, supplied to a longitudinal stretching machine, and stretched so that the direction of the slow axis of the base material was 0° with respect to the conveying direction. After trimming both ends of the stretched film in the width direction, the trimmed film was wound up to obtain a long roll of substrate 1 having a width of 1350 mm. The Re(550) of the substrate 1 thus obtained was 100 nm, and the thickness of the substrate 1 was 35 μm.
In each example, the thickness of the optical member including the substrate 1 was measured using a scanning electron microscope (SEM).

[Formation of photo-alignment film]
<Synthesis of polymer A2>
100.0 parts by weight of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500 parts by weight of methyl isobutyl ketone, and 10 parts of triethylamine were added to a reaction vessel equipped with a stirrer, thermometer, dropping funnel and reflux condenser. 0 parts by mass were charged and mixed at room temperature. Then, 100 parts by mass of deionized water was added dropwise from the dropping funnel over 30 minutes, and the mixture was reacted at 80° C. for 6 hours while being mixed under reflux. After completion of the reaction, the organic phase was taken out and washed with a 0.2% by mass aqueous ammonium nitrate solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure to remove the epoxy-containing polyorganosiloxane. Obtained as a viscous transparent liquid.
When this epoxy-containing polyorganosiloxane was subjected to ¹ H-NMR (nuclear magnetic resonance) analysis, a peak based on the oxiranyl group was obtained in the vicinity of the chemical shift (δ) = 3.2 ppm in accordance with the theoretical intensity. It was confirmed that no side reaction of the epoxy group occurred. This epoxy-containing polyorganosiloxane had a weight average molecular weight Mw of 2,200 and an epoxy equivalent of 186 g/mol.
Next, 10.1 parts by mass of the epoxy-containing polyorganosiloxane obtained above, acrylic group-containing carboxylic acid (Toagosei Co., Ltd., trade name "Aronix M-5300", acrylic acid ω-carboxypolycaprolactone (polymerization degree n ≈ 2)) 0.5 parts by mass, 20 parts by mass of butyl acetate, 1.5 parts by mass of the cinnamic acid derivative obtained by the method of Synthesis Example 1 of JP-A-2015-26050, and 0.3 parts of tetrabutylammonium bromide Parts by weight were charged and stirred at 90° C. for 12 hours. After completion of the reaction, the reaction solution was diluted with the same amount (mass) of butyl acetate and washed with water three times. The operation of concentrating this solution and diluting it with butyl acetate was repeated twice to finally obtain a solution containing a polyorganosiloxane having a photo-orientation group (polymer A2 below). The weight average molecular weight Mw of this polymer A2 was 9,000. Further, as a result of ¹ H-NMR analysis, the component having a cinnamate group in polymer A2 was 23.7% by mass.

<Synthesis of polymer A3>
Polymer A3 was obtained in the same manner as for polymer A2, except that the amounts of acrylic group-containing carboxylic acid and cinnamic acid derivative added in the method for synthesizing polymer A2 were changed. The weight average molecular weight Mw of this polymer A3 was 10,000. Further, as a result of ¹ H-NMR analysis, the component having a cinnamate group in polymer A3 was 47.9% by mass.

<Synthesis of polymer A4>
7 parts by weight of 2,2′-azobis(2,4-dimethylvaleronitrile), 3 parts by weight of α-methylstyrene dimer, and 220 parts by weight of diethylene glycol methyl ethyl ether were placed in a flask equipped with a condenser and a stirrer. I planted it. Subsequently, 100 parts by mass of epoxycyclohexylmethyl methacrylate (manufactured by Daicel Co., Ltd., trade name “Cychromer M100”) was charged into the flask, and the inside of the flask was replaced with nitrogen. Thereafter, the mixture was gently heated and stirred to raise the temperature of the solution to 70° C. and maintained at this temperature for 5 hours to obtain a polymer solution containing the polymer. The resulting polymer solution was dropped into hexane to reprecipitate the polymer, and the precipitate was collected by filtration and dried to obtain a white powder of epoxy-containing polymethacrylate. The Mw of the resulting epoxy-containing polymethacrylate was 11,000.
Subsequently, 5.1 parts by mass of the epoxy-containing polymethacrylate obtained above, an acrylic group-containing carboxylic acid (Toagosei Co., Ltd., trade name "Aronix M-5300", acrylic acid ω-carboxy polycaprolactone (polymerization degree n ≈ 2 )) 8.4 parts by mass, 32 parts by mass of methyl isobutyl ketone, and 0.3 parts by mass of tetrabutylammonium bromide were charged and stirred at 90° C. for 12 hours. After completion of the reaction, reprecipitation was performed with methanol, the precipitate was dissolved in ethyl acetate to obtain a solution, and washed with water three times. The operation of concentrating this solution and diluting it with ethyl acetate was repeated twice to finally obtain a white powder of a polymethacrylate copolymer having acrylate groups and epoxy groups in side chains. The weight average molecular weight Mw of this polymethacrylate copolymer was 8,000.

<Preparation of polymer A5>
Polymer A5 (polymer mixture) was obtained by mixing 5 parts by mass of polymer A3 and 5 parts by mass of polymer A4.

<Preparation of composition for photo-alignment film>
A composition 1 for photo-alignment film having the following composition was prepared.

──────────────────────────────────
Composition of Composition 1 for Photo-Alignment Film────────────────────────────────────
100 parts by weight of polymer A5 having photo-orientable group Nomcoat TAB (manufactured by Nisshin OilliO Co., Ltd.) 15.2 parts by weight Cross-linking agent (Epolead GT401, manufactured by Daicel Corporation) 122 parts by weight Thermal acid generator D1 10. 0 parts by mass diisopropylethylamine 0.5 parts by mass diisobutyl ketone (DiBK) 1100 parts by mass ―――――――――――――――――――――――――――――――― ―

・Numcort TAB (2-ethylhexyl-p-methoxycinnamate)

・Thermal acid generator D1

<Formation of photo-alignment film 1>
The obtained composition 1 for photo-alignment film was continuously applied to one surface of the substrate 1 prepared above with a bar coater. After coating, the coating was dried in a heating zone at 120° C. for 1 minute to remove the solvent and form a coating film having a thickness of 0.25 μm (Step 1).
Subsequently, while winding the base material with the coating film on a mirror-finished backup roll, the coating film is irradiated with polarized ultraviolet rays (accumulated light amount 10 mJ/cm ² , using an ultra-high-pressure mercury lamp), thereby irradiating the coating film. An alignment treatment was performed to form a long photo-alignment film 1 having an alignment regulating force (step 2). At this time, the direction of the polarization axis of the polarized ultraviolet rays was set so that the alignment direction of the liquid crystal was 30°.

[Formation of optically anisotropic layer]
<Preparation of composition for optically anisotropic layer>
An optically anisotropic layer composition (optical anisotropic layer composition (A)) having the following composition was prepared. The optically anisotropic layer composition (A) contains the following rod-like liquid crystal compounds (A) to (C) as polymerizable liquid crystal compounds.

―――――――――――――――――――――――――――――――――――――
Composition of Composition (A) for Optically Anisotropic Layer ――――――――――――――――――――――――――――――――――――
- 80 parts by mass of the following rod-shaped liquid crystal compound (A) - 10 parts by mass of the following rod-shaped liquid crystal compound (B) - 10 parts by mass of the following rod-shaped liquid crystal compound (C) - Ethylene oxide-modified trimethylolpropane triacrylate (V#360, Osaka Organic Chemical Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, Ciba Japan Co., Ltd.) 3 parts by mass Chiral agent (A) below 0.22 parts by mass Polymer (A) below 0.08 parts by mass Methyl isobutyl ketone 117 parts by mass Ethyl propionate 39 parts by mass ――――――――――――――――――――――――――――――― ――――――

Rod-shaped liquid crystal compound (A) (corresponding to a mixture of the following liquid crystal compounds)

Rod-shaped liquid crystal compound (B)

Rod-shaped liquid crystal compound (C)

Chiral agent (A)

Polymer (A) (Wherein, the numerical value described for each repeating unit represents the content (% by mass) of each repeating unit with respect to all repeating units.)

<Formation of optically anisotropic layer 1>
The optically anisotropic layer composition (A) was applied to the surface of the elongated photo-alignment film 1 formed above using a Gieser coating machine to form a composition layer (uncured). (Step 3).
Next, the laminated film on which the composition layer was formed was subjected to an alignment treatment by heating at 90° C. for 80 seconds to twist-align the polymerizable liquid crystal compound contained in the composition layer (step 4).
After that, the composition layer is subjected to a curing treatment by irradiating light (irradiation amount: 500 mJ/cm ² ) from a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 55° C. in a nitrogen atmosphere. An optical film was obtained by fixing the alignment state of the liquid crystal compound and forming an optically anisotropic layer.
The thickness of the formed optically anisotropic layer was 2.1 μm.

[Example 2]
The stretching of the substrate before stretching was performed using a tenter stretching machine so that the direction of the slow axis of the substrate was 90 ° with respect to the conveying direction. A roll of substrate 2 was made according to the method described in .
Next, except that the direction of the polarization axis of the polarized ultraviolet rays irradiated to the coating film of the composition for a photo-alignment film was adjusted so that the orientation direction of the liquid crystal was 103 °, Example 1 A long photo-alignment film 2 was formed on one surface of the substrate 2 according to the method described in 1. [Formation of photo-alignment film]. The direction of the orientation axis of the obtained photo-alignment film 2 was 103°.
Furthermore, an optically anisotropic layer composition ( B) was prepared. The procedure described in [Formation of optically anisotropic layer] of Example 1 was performed except that the obtained optically anisotropic layer composition (B) was used in place of the optically anisotropic layer composition (A). According to the method, an optically anisotropic layer was formed on the surface of the elongated photo-alignment film 2 to obtain an optical film of Example 2.

[Examples 3 to 8, Comparative Examples 1 to 3]
For a photo-alignment film having the same composition as the photo-alignment film composition 1 of Example 1 except that 1100 parts by mass of each solvent described in Table 1 described later is included instead of 1100 parts by mass of diisobutyl ketone (DiBK) Compositions 2-10 were prepared respectively. Instead of the photo-alignment film composition 1, except that the obtained photo-alignment film compositions 2 to 10 were used, according to the method described in Example 2, obtained on one surface of the substrate 3 Long photo-alignment films 3 to 8 and C1 to C3 are formed, and then the optically anisotropic layer composition (B) is applied to the surface of the formed long photo-alignment film. An optical layer was formed to obtain optical films of Examples 3 to 8 and Comparative Examples 1 to 3, respectively.

[Example 9]
Adjusting the thickness of the thermoplastic norbornene polymer sheet formed by extruding from the T die onto the casting drum, and when stretching the substrate before stretching, the direction of the slow axis of the substrate is with respect to the conveying direction A roll of Substrate 3 was produced according to the method described in [Preparation of Substrate] in Example 1, except that diagonal stretching was carried out using a tenter stretching machine so that the angle was 10°. Next, according to the method described in Example 2, a long photo-alignment film 9 was formed on one surface of the substrate 3 thus obtained. The direction of the orientation axis of the obtained photo-alignment film 9 was 10°.
Optically anisotropic layer composition (C) having the same composition as the optically anisotropic layer composition (A) of Example 1 except that the content of the chiral agent (A) is 0.30 parts by mass. was prepared. Using the obtained composition (C) for an optically anisotropic layer instead of the composition (B) for an optically anisotropic layer, and forming an optically anisotropic layer having a thickness of 0.25 μm. An optically anisotropic layer was formed on the surface of the elongated photo-alignment film 9 according to the method described in Example 2, except that the coating amount of the optically anisotropic layer composition was changed as in Then, an optical film of Example 9 was obtained.

[Example 10]
Adjusting the thickness of the thermoplastic norbornene polymer sheet formed by extruding from the T die onto the casting drum, and when stretching the substrate before stretching, the direction of the slow axis of the substrate is with respect to the conveying direction A roll of Substrate 4 was produced according to the method described in [Preparation of Substrate] in Example 1, except that diagonal stretching was performed using a tenter stretching machine so that the roll was -10°. Next, according to the method described in Example 2, a long photo-alignment film 10 was formed on one surface of the substrate 4 thus obtained. The orientation axis of the obtained photo-alignment film 10 was -10°.
For the optically anisotropic layer of Example 1, except that the chiral agent (B) described below was used instead of the chiral agent (A), and the content of the chiral agent (B) was 0.30 parts by mass. An optically anisotropic layer composition (D) having the same composition as the composition (A) was prepared. Using the obtained composition (D) for an optically anisotropic layer instead of the composition (B) for an optically anisotropic layer, and forming an optically anisotropic layer having a thickness of 0.25 μm. An optically anisotropic layer was formed on the surface of the elongated photo-alignment film 10 according to the method described in Example 2, except that the coating amount of the optically anisotropic layer composition was changed as in Then, an optical film of Example 10 was obtained.

Chiral agent B

[Example 11]
Optically anisotropic layer composition (E) having the same composition as the optically anisotropic layer composition (C) of Example 9 except that the content of the chiral agent (A) is 0.04 parts by mass. was prepared. The optically anisotropic layer composition (E) was used instead of the optically anisotropic layer composition (C). An optically anisotropic layer was formed on the surface of the photo-alignment film 9, and an optical film of Example 11 was obtained.

[Comparative Example 4]
Adjusting the thickness of the thermoplastic norbornene polymer sheet formed by extruding from the T die onto the casting drum, and when stretching the base material before stretching using a tenter stretching machine, the direction of the slow axis is conveyed The stretching ratio and stretching direction of the substrate before stretching were adjusted so as to obtain a substrate having an Re (550) of 140 nm at 90° to the direction, except that the [ Production of Substrate], a roll of the substrate 5 having a thickness of 40 μm was produced.
Next, the direction of the polarization axis of the polarized ultraviolet rays irradiated to the coating film of the composition for photo-alignment film is such that the angle formed by the longitudinal direction of the substrate with the coating film and the polarization axis of the polarized ultraviolet rays is 22.5°. A long photo-alignment film C4 was formed on one surface of the substrate 5 according to the method described in [Formation of photo-alignment film] in Example 1, except that the conditions were set as follows. The direction of the orientation axis of the obtained photo-alignment film C4 was 22.5°.
Furthermore, an optically anisotropic layer composition (F) was prepared which had the same composition as the optically anisotropic layer composition (A) of Example 1 except that it did not contain the chiral agent (A). [Formation of optically anisotropic layer] of Example 1, except that the obtained composition (F) for an optically anisotropic layer is used instead of the composition (A) for an optically anisotropic layer. An optically anisotropic layer was formed on the surface of the elongated photo-alignment film C4 according to the method of No. 2, and an optical film of Comparative Example 4 was obtained.

[Comparative Example 5]
Adjusting the thickness of the thermoplastic norbornene polymer sheet formed by extruding from the T die onto the casting drum, and when stretching the base material before stretching using a tenter stretching machine, the direction of the slow axis is conveyed Example 1, except that the stretch ratio and stretching direction of the substrate before stretching were adjusted so that a substrate having an Re(550) of 275 nm was obtained at 22.5° to the direction. A roll of the substrate 6 having a thickness of 80 μm was produced according to the method described in [Production of the substrate].
Next, the direction of the polarization axis of the polarized ultraviolet rays irradiated to the coating film of the composition for photo-alignment film is adjusted so that the angle formed by the longitudinal direction of the substrate with the coating film and the polarization axis of the polarized ultraviolet rays is 90°. A long photo-alignment film C5 was formed on one surface of the substrate 6 according to the method described in [Formation of photo-alignment film] in Example 1, except for the setting. The direction of the orientation axis of the obtained photo-alignment film C5 was 90°.
Further, the optically anisotropic layer composition (F) used in Comparative Example 4 was used in place of the optically anisotropic layer composition (A) of Example 1 [optically anisotropic layer composition]. Formation], an optically anisotropic layer was formed on the surface of the elongated photo-alignment film C5, and an optical film of Comparative Example 5 was obtained.

[Comparative Example 6]
Adjusting the thickness of the thermoplastic norbornene polymer sheet formed by extruding from the T die onto the casting drum, and when stretching the base material before stretching using a tenter stretching machine, birefringence in the in-plane direction The stretching ratio and the stretching direction of the substrate before stretching were adjusted so as to obtain a substrate having no Re (550) of 0 nm and no slow axis. A roll of the substrate 7 having a thickness of 40 μm was produced according to the method described in [Fabrication of the substrate].
Next, the direction of the polarization axis of the polarized ultraviolet rays irradiated to the coating film of the composition for photo-alignment film is adjusted so that the angle formed by the longitudinal direction of the substrate with the coating film and the polarization axis of the polarized ultraviolet rays is 45°. A long photo-alignment film C6 was formed on one surface of the substrate 7 according to the method described in [Formation of photo-alignment film] in Example 1, except for the setting. The direction of the orientation axis of the obtained photo-alignment film C6 was 45°.
Further, the optically anisotropic layer composition (F) used in Comparative Example 4 was used in place of the optically anisotropic layer composition (A) of Example 1 [optically anisotropic layer composition]. Formation], an optically anisotropic layer was formed on the surface of the elongated photo-alignment film C6, and an optical film of Comparative Example 6 was obtained.

[Comparative Example 7]
[Formation of optically anisotropic layer]
An optically anisotropic layer composition (G) having the following composition was prepared. The optically anisotropic layer composition (G) contains the following liquid crystal compounds L-3 and L-4 as polymerizable liquid crystal compounds.

―――――――――――――――――――――――――――――――――――――
Composition of Composition (G) for Optically Anisotropic Layer ――――――――――――――――――――――――――――――――――――
・The following liquid crystal compound L-3 42.00 parts by mass ・The following liquid crystal compound L-4 42.00 parts by mass ・The following polymerizable compound A-1 16.00 parts by mass ・The following polymerization initiator S-1 (oxime type) 0 .50 parts by mass Leveling agent (Compound G-1 below) 0.20 parts by mass Hisolve MTEM (manufactured by Toho Chemical Industry Co., Ltd.) 2.00 parts by mass NK Ester A-200 (Shin-Nakamura Chemical Industry Co., Ltd.) ) 1.00 parts by mass Methyl ethyl ketone 305.9 parts by mass Cyclopentanone 118.9 parts by mass―――――――――――――――――――――――――――― ――――――――――
The group adjacent to the acryloyloxy group in the following liquid crystal compounds L-3 and L-4 represents a propylene group (a group in which a methyl group is substituted with an ethylene group), and the following liquid crystal compounds L-3 and L-4 are Represents a mixture of regioisomers that differ in the position of the methyl group.

Liquid crystal compound L-3

Liquid crystal compound L-4

Polymerizable compound A-1

Polymerization initiator S-1

Compound G-1

The optically anisotropic layer composition (G) was applied to the surface of the elongated photo-alignment film C6 formed in Comparative Example 6 using a die coater to form a composition layer (uncured). (Step 3).
Next, the laminate film having the composition layer formed thereon was heated at 110° C. for orientation treatment, and then cooled to 75° C. to stabilize the orientation (step 4).
After that, the composition layer is subjected to a curing treatment of irradiating ultraviolet rays (irradiation amount: 500 mJ/cm ² ) using an ultra-high pressure mercury lamp at 75° C. in a nitrogen atmosphere (oxygen concentration 100 ppm). An optical film of Comparative Example 7 was obtained by fixing the alignment state of the liquid crystal compound and forming an optically anisotropic layer. The thickness of the formed optically anisotropic layer was 2.3 μm.

[Measurement and Evaluation of Optical Film]
The optical films obtained in Examples 1-11 and Comparative Examples 1-7 were subjected to the following measurements and evaluations. The measurement results and evaluation results are shown in Table 1 below.

<Measurement of Δnd>
For each optical film, the product (Δnd) of the refractive index anisotropy Δn of the optically anisotropic layer measured at a wavelength of 550 nm and the thickness d of the optically anisotropic layer was measured by AxoScan (polarimeter device) of Axometrics, and Measurement was performed using the company's device analysis software (Multi-Layer Analysis).

<Measurement of twist angle and orientation axis>
The twist angle with the thickness direction of the liquid crystal compound in the optically anisotropic layer of each optical film as the helical axis (the twist angle in the alignment direction of the liquid crystal compound), and the liquid crystal compound on the substrate-side surface of the optically anisotropic layer The angle of the orientation axis of (hereinafter also referred to as "substrate-side orientation axis") was measured using AxoScan (polarimeter device) from Axometrics and the company's device analysis software.
Regarding the angle of the orientation axis on the substrate side, the longitudinal direction of the optical film is taken as a reference (0°), and the direction of counterclockwise rotation when the optical film is observed from the surface of the optically anisotropic layer is positive. was taken as the value of

<Measurement of distances d1 and d2>
According to the method described above, the optically anisotropic layer of each optical film is irradiated with an ion beam while using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) to measure the components of each optical film in the thickness direction. analyzed along. From the profile in the thickness direction of the secondary ion intensity derived from the alignment agent obtained by the analysis, the distances d1 and d2 were obtained according to the method described above, and the ratio d2/d1 was calculated.
The measuring apparatus and measuring conditions used for measuring the distances d1 and d2 are shown below.

(Measuring device and measurement conditions)
・Equipment: TOF-SIMSV (manufactured by ION-TOF)
・Depth direction analysis: Ar ion sputtering combined ・Measuring range: Raster scan of 128 points each in one direction and its orthogonal direction ・Polarity: positive, negative

<Evaluation of liquid crystal orientation>
A laminate in which each optical film was placed between two polarizing plates arranged in crossed Nicols was observed using a polarizing microscope. Based on the observed optical defects such as unevenness and/or poor orientation, the orientation of the liquid crystal compound contained in the optically anisotropic layer was evaluated according to the following criteria. Evaluations A and B are practically acceptable levels.

(Evaluation criteria)
"A": No optical defect is observed.
"B": Slight optical defects were observed.
"C": Many optical defects were observed.

<Evaluation of Adhesion>
The optically anisotropic layer of each optical film was subjected to a cross-cut test (crosscut tape peeling test) according to JIS D0202-1988. In each optical film, the optically anisotropic layer was cut in a grid pattern to form 100 squares. Of the 100 squares formed, cellophane tape ("CT24", manufactured by Nichiban Co., Ltd.) was attached and peeled off, and the number of squares that had been peeled off was counted and evaluated according to the following criteria. Evaluations S, A and B are practically acceptable levels.

(Evaluation criteria)
"S": 0 squares to peel off "A": 1 to 30 squares to peel off "B": 31 to 50 squares to peel off "C": Number of squares to peel off 51 or more

<Evaluation of wet heat durability (crack resistance)>
Each optical film was cut into a size of 100 mm × 100 mm to prepare a sample, and an adhesive (sheet adhesive "SK2057" manufactured by Soken Kagaku Co., Ltd.) was attached to the surface of the obtained sample on the optically anisotropic layer side. After that, the sample was attached to a glass plate via an adhesive. Four sets of laminates of samples and glass plates were produced for each optical film. The resulting laminate was stored for 1 hour at a temperature of −35° C. and then stored at a temperature of 70° C. for 1 hour using Hitachi’s environmental test equipment “ES207LH” for 50 cycles. went on a cycle. The appearance of four sets of laminates after the cycle test was observed under a microscope, and wet heat durability was evaluated according to the following criteria. It is practically necessary for the evaluation of wet heat durability to be A or B, and A evaluation is preferable.

(Evaluation criteria)
"A": No cracks were observed in any of the optically anisotropic layers.
"B": Cracks were observed only in one set of optically anisotropic layers.
"C": Cracks were observed in two or more sets of optically anisotropic layers.

<Shaft variation>
For the optical films obtained in Examples 1 to 8 and Comparative Examples 1 to 4, a circularly polarizing plate was obtained by bonding a polarizer to the surface of each optical film on the optically anisotropic layer side using a pressure-sensitive adhesive. , and the optical films obtained in Examples 9 to 11 and Comparative Examples 5 to 7 were circularly shaped by bonding a polarizer to the surface of each optical film on the substrate side using a pressure-sensitive adhesive. A polarizing plate was produced. At this time, the optical film and the circularly polarizing plate were bonded together so that the longitudinal direction of the optical film and the absorption axis of the circularly polarizing plate were parallel to each other.
The circularly polarizing plate was peeled off from a display device (GALAXY (registered trademark) S4 manufactured by SAMSUNG) equipped with an organic EL panel. Next, the circularly polarizing plate obtained above was attached to an organic EL display device using a pressure-sensitive adhesive such that the polarizer was arranged on the outside (on the side opposite to the organic EL panel).
For each optical film, 20 organic EL display devices with circularly polarizing plates were produced. The produced organic EL display device was set to black display and observed from the direction directly facing the organic EL panel under bright light, and from the observed individual differences in color of the 20 organic EL display devices, the following criteria The axial variation of the optical film was evaluated according to. Evaluations A and B are practically acceptable levels.

(Evaluation criteria)
"A": Individual differences in color are not visible at all, or are slightly visible.
"B": Individual differences in color are slightly visible, but the reflected light is small, and there is no problem in use.
"C": Individual differences in color were visually recognized, reflected light was large, and unacceptable.

<Curl>
The curl value of each optical film was measured according to the measurement method (ANSI/ASC PH1.29-1985, Method-A) specified by the American National Standards Institute. Specifically, after cutting each optical film into a size of 35 mm in the width direction and 2 mm in the length direction, the obtained sample is placed on a curl plate. The curled plate with the sample was conditioned for 6 hours in an environment with a temperature of 25° C. and a relative humidity of 80%. The curl value read after humidity conditioning was used as the measured value. The curl value is expressed by the radius of curvature (cm), and the smaller the radius of curvature, the lower the transportability of the film.
From the measured curl value, the curl of each optical film was evaluated based on the following criteria. Evaluations 1 to 3 are levels with no problem in practical use.

(Evaluation criteria)
"1": (absolute value of curl value) ≥ 30 cm
"2": 30 cm > (absolute value of curl value) ≥ 20 cm
"3": 20 cm > (absolute value of curl value) ≥ 10 cm
"4": 10 cm> (absolute value of curl value)

Table 1 shows the characteristics of the base material, the alignment film, the optically anisotropic layer and the optical film produced in each example and each comparative example, as well as the measurement results and evaluation results of the optical films.

In Table 1, the "solvent" column of "alignment film" indicates the type of solvent contained in each composition described in the "alignment film composition" column. In this column, "DiBK" stands for diisobutyl ketone, "MiBK" stands for methyl isobutyl ketone, "THF" stands for tetrahydrofuran, "MEK" stands for methyl ethyl ketone, and "PGMEA" stands for propylene glycol monomethyl ether acetate. , “NMP” stands for N-methyl-2-pyrrolidone.
In Table 1, the "ΔSP" column represents the difference (unit: MPa ^1/2 ) between the SP value of the substrate and the SP value of the solvent contained in the alignment film composition.
In Table 1, the "twisting direction" column of the "optically anisotropic layer" indicates that the orientation axis of the liquid crystalline compound rotates along the thickness direction from the substrate-side surface of the optically anisotropic layer toward the other surface. This is the direction in which the optical film is observed from the side of the optically anisotropic layer. That is, "counterclockwise" in this column means that the direction of rotation of the alignment axis of the liquid crystal compound is counterclockwise.

As shown in Table 1, it was confirmed that the optical film produced by the production method according to the present invention is excellent in liquid crystal orientation, adhesion and wet heat durability.

10 Specified optical film (optical film)
REFERENCE SIGNS LIST 12 first surface 14 second surface 20 substrate 30 alignment film 40 optically anisotropic layer 50, 60 optical film with polarizer (optical laminate)
52, 62 Polarizer

Claims (10)

Step 1 of applying an alignment film composition containing an alignment agent and a solvent onto a substrate to form a coating film;
a step 2 of subjecting the coating film to an orientation treatment to form an orientation film having an orientation regulating force;
Step 3 of applying a composition containing a liquid crystal compound having a polymerizable group on the alignment film to form a composition layer;
A step 4 of subjecting the composition layer to an orientation treatment to twist-align the liquid crystal compound with the thickness direction of the composition layer as a helical axis;
a step 5 of curing the composition layer to fix the alignment state of the liquid crystal compound to form an optically anisotropic layer;
the twist angle with respect to the thickness direction of the liquid crystal compound in the optically anisotropic layer as the helical axis is more than 0° and 180° or less;
A method for producing an optical film, wherein the difference between the SP value of the substrate and the SP value of the solvent is 4.0 to 10.0 MPa ^1/2 . 2. The method for producing an optical film according to claim 1, wherein the base material contains a polymer having an alicyclic structure. 3. The method for producing an optical film according to claim 1, wherein the aligning agent comprises a photo-aligning agent. The substrate has an in-plane retardation of 67.5 to 127.5 nm at a wavelength of 550 nm,
the product Δnd of the refractive index anisotropy Δn of the optically anisotropic layer and the thickness d of the optically anisotropic layer is 317 to 377 nm;
The twist angle with respect to the thickness direction of the liquid crystal compound in the optically anisotropic layer is 20 to 60°.
A method for producing an optical film according to any one of claims 1 to 3. An optical film having a substrate, an alignment film and an optically anisotropic layer in this order,
The alignment film contains an alignment agent,
In the optically anisotropic layer, the liquid crystal compound having a polymerizable group is fixed in a twisted orientation state with a twist angle of more than 0° and 180° or less with the thickness direction of the optically anisotropic layer as a helical axis. cage,
An optical film that satisfies requirements 1 and 2 below.
Requirement 1: With the surface of the optical film on the optically anisotropic layer side as the first surface and the surface of the optical film on the substrate side as the second surface, the first surface of the optical film to the second surface of the optical film. The secondary ion intensity in the thickness direction derived from the alignment agent obtained by analyzing the component in the thickness direction of the optical film by time-of-flight secondary ion mass spectrometry while irradiating the surface with an ion beam. In the profile, among the positions where the secondary ion intensity is 80% of the maximum value of the secondary ion intensity derived from the alignment agent, the position closest to the first surface is position A, and the position A is closest to the second surface. Assuming that the position is position B, the distance d1 between the position A and the position B is 100 nm or more.
Requirement 2: In the profile, let position C be a position that is closer to the second surface than position B and exhibits a secondary ion intensity that is 20% of the maximum secondary ion intensity derived from the alignment agent. , the distance d2 between the position B and the position C, and the distance d1 satisfy the following formula (I).
0.3≤d2/d1≤0.82 (I) The optical film according to claim 5, wherein the base material contains a polymer having an alicyclic structure. 7. The optical film as claimed in claim 5 or 6, wherein the alignment agent comprises a photo-alignment agent. The substrate has an in-plane retardation of 67.5 to 127.5 nm at a wavelength of 550 nm,
the product Δnd of the refractive index anisotropy Δn of the optically anisotropic layer and the thickness d of the optically anisotropic layer is 240 to 320 nm;
The twist angle with the thickness direction of the liquid crystal compound in the optically anisotropic layer as the helical axis is 20 to 60.
The optical film according to any one of claims 5-7. An optical laminate comprising the optical film according to any one of claims 5 to 8 and a polarizer. 10. The optical laminate according to claim 9, wherein the angle between the absorption axis of the polarizer and the slow axis of the base material of the optical film is 0±5° or 90±5°.

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