CN108508519B - Optical film and method for producing same - Google Patents

Abstract

The present invention addresses the problem of providing a novel optical film in which the optical refractive index is controlled in three dimensions over the entire visible light range and all viewing directions, and a method for manufacturing the same. An optical film which has a first retardation layer and a second retardation layer and satisfies the relationships of the following formulae (1) and (2). (1) Nz (450) is more than or equal to 0.4 and less than or equal to 0.6, and Nz (550) is more than or equal to 0.4 and less than or equal to 0.6. In the formula, Nz (450) represents an Nz coefficient of the optical film with respect to light having a wavelength λ of 450nm, and Nz (550) represents an Nz coefficient of the optical film with respect to light having a wavelength λ of 550 nm.

Description

Optical film and method for producing same

Technical Field

The present invention relates to an optical film and a method for manufacturing the same.

Background

In a Flat Panel Display (FPD), an optical film such as a polarizing plate or a retardation plate can be used. For example, patent document 1 discloses a reverse wavelength dispersive retardation film oriented in the horizontal direction, and patent document 2 discloses a reverse wavelength dispersive retardation film oriented in the vertical direction.

Documents of the prior art

Patent literature

Patent document 1: japanese Kokai publication No. 2010-537955

Patent document 2: japanese laid-open patent publication No. 2015-57646

Disclosure of Invention

Problems to be solved by the invention

In recent years, with the development of flat panel displays, it has been increasingly required that clear black display be displayed regardless of the orientation from which the display is viewed. Therefore, the following problems become more apparent: it is not sufficient to perform only the wavelength dispersion control in the horizontal direction or the vertical direction.

Means for solving the problems

The present invention includes the following inventions.

[ 1 ] an optical film which has a first retardation layer and a second retardation layer and satisfies the relationships of the following formulae (1) and (2).

0.4≤Nz(450)≤0.6 (1)

0.4≤Nz(550)≤0.6 (2)

In the formula, Nz (450) represents an Nz coefficient of the optical film with respect to light having a wavelength λ of 450nm, Nz (550) represents an Nz coefficient of the optical film with respect to light having a wavelength λ of 550nm, and Nz coefficient Nz (λ) of the optical film with respect to light having a wavelength λ (nm) is represented by the following formula:

Nz(λ)＝(nx(λ)-nz(λ))/(nx(λ)-ny(λ))

nx (λ) represents: in the refractive index ellipsoid formed by the optical film, the principal refractive index for light of wavelength λ (nm) in the direction parallel to the film plane. ny (λ) represents: in the refractive index ellipsoid formed by the optical film, the refractive index for light of wavelength λ (nm) in the direction parallel to the film plane and orthogonal to the direction of nx (λ) is given.

nz (λ) represents: in the refractive index ellipsoid formed by the optical film, the refractive index for light of wavelength λ (nm) in the direction perpendicular to the film plane. Angle (c)

[ 2 ] the optical film according to the above [ 1 ], wherein the first retardation layer,

in a refractive index ellipsoid formed by the first retardation layer, a relationship of nx1(λ) > ny1(λ) ≈ nz1(λ) in a range of a wavelength λ of 400 to 700nm,

[ in the formula, nx1(λ) represents: in the index ellipsoid formed by the first retardation layer, the principal refractive index for light of wavelength λ (nm) in the direction parallel to the film plane. ny1(λ) denotes: in the index ellipsoid formed by the first retardation layer, the refractive index for light of the wavelength λ (nm) in the direction parallel to the film plane and orthogonal to the direction of the aforementioned nx1(λ) is used. nz1(λ) denotes: in the refractive index ellipsoid formed by the first retardation layer, the refractive index for light of wavelength λ (nm) in the direction perpendicular to the film plane. Angle (c)

The first retardation layer satisfies the following expressions (3) and (4).

Re1(450)/Re1(550)≤1.00 (3)

1.00≤Re1(650)/Re1(550) (4)

In the expressions, Re1(450) represents an in-plane phase difference value with respect to light having a wavelength λ of 450nm in the first retardation layer, Re1(550) represents an in-plane phase difference value with respect to light having a wavelength λ of 550nm in the first retardation layer, Re1(650) represents an in-plane phase difference value with respect to light having a wavelength λ of 650nm in the first retardation layer, and an in-plane phase difference value Re1(λ) with respect to light having a wavelength λ nm in the first retardation layer is expressed by the following expression:

Re1(λ)＝(nx1(λ)-ny1(λ))×d1

Where d1 denotes the thickness of the first retardation layer. Angle (c)

[ 3 ] the optical film according to the above [ 1 ] or the above [ 2 ], wherein for the second retardation layer,

in a refractive index ellipsoid formed by the second phase difference layer, a relation of nz2 (lambda) > nx2 (lambda) ≈ ny2 (lambda) in a range of a wavelength lambda of 400 to 700nm,

[ in the formula, nz2(λ): in the refractive index ellipsoid formed by the second phase difference layer, the refractive index for light of wavelength λ (nm) in the direction perpendicular to the film plane. nx2(λ) denotes: in the refractive index ellipsoid formed by the second phase difference layer, the maximum refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane. ny2(λ) denotes: in the index ellipsoid formed by the second phase difference layer, the refractive index for light having a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of the nx2(λ) is set. Where nx2(λ) ═ ny2(λ), nx2(λ) represents a refractive index in an arbitrary direction parallel to the film plane. Angle (c)

The second phase difference layer satisfies the following equations (5) and (6).

Rth2(450)/Rth2(550)≤1.00 (5)

1.00≤Rth2(650)/Rth2(550) (6)

In the formula, Rth2(450) represents a phase difference value for light having a wavelength λ of 450nm in the thickness direction, Rth2(550) represents a phase difference value for light having a wavelength λ of 550nm in the thickness direction of the second retardation layer, Rth2(650) represents a phase difference value for light having a wavelength of 650nm in the thickness direction of the second retardation layer, and Rth2(λ) for light having a wavelength λ (nm) in the thickness direction of the second retardation layer is represented by the following formula:

Rth2(λ)＝[(nx2(λ)+ny2(λ))/2-nz2(λ)]×d2

Wherein, in the index ellipsoid formed by the second phase difference layer, nz2(λ) represents a main refractive index in a direction perpendicular to the film plane at the wavelength λ (nm) ((nx2(λ) + ny2(λ))/2) represents an average refractive index of the film plane at the wavelength λ (nm). d2 denotes the thickness of the second retardation layer. Angle (c)

The optical film according to any one of [ 1 ] to [ 3 ] above, wherein the first retardation layer further satisfies the relationship of the following formula (7).

120nm≤Re1(550)≤170nm (7)

In the formula, Re1(550) represents an in-plane retardation value of the first retardation layer with respect to light having a wavelength λ of 550 nm. Angle (c)

The optical film according to any one of [ 1 ] to [ 4 ] above, wherein the second retardation layer further has optical characteristics represented by formula (8).

-100nm≤Rth2(550)≤-50nm (8)

In the formula, Rth2(550) represents a phase difference value for light having a wavelength λ of 550nm in the thickness direction of the second retardation layer. Angle (c)

The optical film according to any one of [ 1 ] to [ 5 ] above, wherein the second retardation layer is a film formed of an overcoat layer formed by polymerizing polymerizable liquid crystals in an aligned state.

The optical film according to any one of [ 1 ] to [ 6 ] above, wherein the first retardation layer is a film formed of an overcoat layer formed by polymerizing polymerizable liquid crystals in an aligned state.

The optical film according to any one of [ 1 ] to [ 7 ] above, wherein the second retardation layer is 5 μm or less.

The optical film according to any one of [ 1 ] to [ 8 ] above, wherein the first retardation layer is 5 μm or less.

The optical film according to any one of [ 1 ] to [ 9 ] above, wherein the first retardation layer and the second retardation layer are coating layers formed by polymerizing mainly the same polymerizable liquid crystal compound.

An elliptically polarizing plate with an optical compensation function, which comprises the optical film according to any of [ 1 ] to [ 10 ] above and a polarizing plate.

An elliptical polarizing plate with an optical compensation function according to the above [ 11 ], wherein an absorption axis of the polarizing plate and a slow axis of the first retardation layer have a relationship of 45 ± 5 ° or 135 ± 5 ° within a film surface, and the absorption axis of the polarizing plate and the slow axis of the first retardation layer and the slow axis of the second retardation layer are orthogonal to each other in a direction perpendicular to the film surface.

[ 13 ] the elliptically polarizing plate with an optical compensation function according to [ 11 ] or [ 12 ] above, which is an optical laminate comprising a polarizing plate, an adhesive layer, a first retardation layer, an adhesive layer, and a second retardation layer formed in this order.

[ 14 ] the elliptically polarizing plate with an optical compensation function according to [ 11 ] or [ 12 ] above, which is an optical laminate comprising a polarizing plate, an adhesive layer, a second retardation layer, an adhesive layer, and a first retardation layer formed in this order.

An organic EL display device having the elliptically polarizing plate with optical compensation function according to any of [ 11 ] to [ 14 ].

The method for manufacturing an elliptically polarizing plate with an optical compensation function according to any of [ 11 ] to [ 14 ] above, which comprises all the following steps.

(step 1-A) a step of forming a first retardation layer by applying a polymerizable liquid crystal compound onto a substrate having a horizontal alignment film formed thereon and then polymerizing the compound in a horizontally aligned state;

(step 1-B) a step of forming a second phase difference layer by applying a polymerizable liquid crystal compound onto a substrate having a vertical alignment film formed thereon and then polymerizing the compound in a vertically aligned state; and

(step 2) a step of transferring the liquid crystal polymer of the first retardation layer and the liquid crystal polymer of the second retardation layer from the base material via an adhesive to laminate the two layers to the polarizing plate.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides a novel optical film in which the refractive index of light is controlled in three dimensions over the entire range of visible light and all viewing directions, and a method for manufacturing the same. Further, a liquid crystal display device and an organic EL display device capable of performing clear display by using the optical film are provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention.

The optical film of the present invention is formed of a first retardation layer and a second retardation layer. The first retardation layer and the second retardation layer may be formed by stretching or shrinking a polymer film, but from the viewpoint of reduction in thickness, a film formed from a coating layer formed by coating a polymerizable liquid crystal (hereinafter, also referred to as a polymerizable liquid crystal compound) and polymerizing the liquid crystal in an aligned state is preferable.

In view of the reduction in thickness and the optional design of wavelength dispersion characteristics, the first retardation layer and the second retardation layer are preferably formed by applying a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as "composition for forming a retardation layer") onto a transparent substrate to form a layer, and heating and cooling the layer to form a polymer in an oriented state of the polymerizable liquid crystal compound. As described later, the composition for forming a retardation layer may further include a solvent, a photopolymerization initiator, a photosensitizing agent, a polymerization inhibitor, a leveling agent (leveling agent), an adhesion improving agent, and the like.

The first retardation layer is preferably a liquid crystal cured film obtained by curing a polymerizable liquid crystal compound in a state of being aligned in a direction horizontal to the substrate surface, and the second retardation layer is preferably a liquid crystal cured film obtained by curing a polymerizable liquid crystal compound in a state of being aligned in a direction perpendicular to the substrate surface.

The in-plane retardation value Re1(550) with respect to light having a wavelength of 550nm preferably satisfies the optical characteristics expressed by the following formula (7) in the first retardation layer. Further, it is also preferable that the first retardation layer satisfies optical properties shown by expressions (3) and (4) with respect to the in-plane retardation value Re1(450) for light having a wavelength of 450nm, the in-plane retardation value Re1(550) for light having a wavelength of 550nm, and the in-plane retardation value Re1(650) for light having a wavelength of 650 nm. The first retardation layer preferably satisfies optical properties represented by the following formulas (7), (3) and (4).

120nm≤Re1(550)≤170nm…(7)

(wherein Re1(550) represents an in-plane retardation value (in-plane retardation) of the first retardation layer with respect to light having a wavelength of 550 nm.)

Re1(450)/Re1(550)≤1.0…(3)

1.00≤Re1(650)/Re1(550)…(4)

(wherein Re1(450) represents an in-plane phase difference value with respect to light having a wavelength of 450nm of the first retardation layer, Re1(550) represents an in-plane phase difference value with respect to light having a wavelength of 550nm of the first retardation layer, and Re1(650) represents an in-plane phase difference value with respect to light having a wavelength of 650nm of the first retardation layer, respectively.)

When the in-plane retardation Re1(550) of the first retardation layer exceeds the range of formula (7), the following problem occurs: when an elliptical polarizing plate with an optical compensation function described later is produced by combining the optical film of the present invention with a polarizing plate and the polarizing plate is attached to a mirror in this state, the front color turns red or blue. Further preferred ranges of in-plane phase difference values are: re1(550) is not less than 130nm and not more than 160 nm. When "Re 1(450)/Re1 (550)" of the first retardation layer is larger than 1.0, light leakage on the short wavelength side in the elliptically polarizing plate having the retardation layer increases. Preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and still more preferably 0.79 to 0.85.

The in-plane retardation value of the first retardation layer can be adjusted by the thickness of the retardation layer. Since the in-plane phase difference value is determined by the following formula (a), the three-dimensional refractive index and the film thickness d1 may be adjusted to obtain a desired in-plane phase difference value (Re1(λ): the in-plane phase difference value of the first retardation layer at the wavelength λ (nm)). The thickness of the retardation layer is preferably 0.5 to 5 μm, more preferably 1 to 3 μm. The thickness of the retardation layer can be measured by an interferometric film thickness meter, a laser microscope, or a stylus film thickness meter. The three-dimensional refractive index depends on the molecular structure and alignment state of the polymerizable liquid crystal compound described later.

Re1(λ)＝(nx1(λ)-ny1(λ))×d1 (A)

(wherein, in the index ellipsoid formed in the first phase difference layer, there is a relationship of nx1(λ) > ny1(λ) ≈ nz1(λ), nx1(λ) denotes a main refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane. ny1(λ) denotes a refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of nx1(λ) in the index ellipsoid formed in the first phase difference layer. d1 denotes a thickness of the first phase difference layer. in addition, by "ny 1(λ) ≈ nz1(λ)", it is meant that ny1(λ) is substantially the same as nz1(λ), for example, it denotes that a difference in numerical value is within 0.01.)

The second phase difference layer preferably satisfies the optical characteristics expressed by the following expression (8) in terms of the phase difference value Rth2(λ) for light having a wavelength λ nm in the thickness direction. Further, it is preferable that the optical properties shown by the following formulas (5) and (6) are satisfied. The second phase difference layer more preferably satisfies optical characteristics represented by the following formula (8), the following formula (5), and the following formula (6).

-100nm≤Rth2(550)≤-50nm…(8)

(wherein Rth2(550) represents a phase difference value with respect to light having a wavelength of 550nm in the thickness direction.)

Rth2(450)/Rth2(550)≤1.0…(5)

1.00≤Rth2(650)/Rth2(550)…(6)

(wherein Rth2(450) represents a phase difference value with respect to light having a wavelength of 450nm in the thickness direction, Rth2(550) represents the same meaning as described above, and Rth2(650) represents a phase difference value with respect to light having a wavelength of 650nm in the thickness direction, respectively.)

When the retardation value Rth2(550) in the thickness direction of the second retardation layer exceeds the range of formula (8), the following problem occurs: when an elliptical polarizing plate with an optical compensation function described later is produced by combining the optical film of the present invention with a polarizing plate and is attached to a mirror in this state, the oblique color tone becomes red or blue. More preferable ranges of the phase difference value in the thickness direction are: rth2(550) is more than or equal to-95 nm and less than or equal to-55 nm; further preferred ranges are: rth2(550) is less than or equal to minus 90nm and less than or equal to minus 60 nm. When "Rth 2(450)/Rth2 (550)" of the second retardation layer is larger than 1.0, light leakage on the short wavelength side in the elliptically polarizing plate having the retardation layer increases. Preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and still more preferably 0.79 to 0.85.

The phase difference value in the thickness direction of the second phase difference layer can be adjusted by the thickness of the phase difference layer. Since the retardation value in the thickness direction is determined by the following formula (B), the three-dimensional refractive index and the film thickness d2 may be adjusted to obtain a desired retardation value in the thickness direction (Rth2(λ): the retardation value in the thickness direction of the second retardation layer at the wavelength λ (nm)). The thickness of the retardation layer is preferably 0.2 to 5 μm, more preferably 0.5 to 2 μm. The thickness of the retardation layer can be measured by an interferometric film thickness meter, a laser microscope, or a stylus film thickness meter. The three-dimensional refractive index depends on the molecular structure and orientation of the polymerizable liquid crystal compound described later.

Rth2(λ)＝[(nx2(λ)+ny2(λ))/2-nz2(λ)]×d2 (B)

(wherein, in a refractive index ellipsoid formed by the second phase difference layer, there is a relationship of nz2(λ) > nx2(λ) ≈ ny2(λ), wherein nz2(λ) denotes a refractive index for light of a wavelength λ (nm) in a direction perpendicular to the film plane in the refractive index ellipsoid formed by the second phase difference layer nx2(λ) denotes a maximum refractive index for light of a wavelength λ (nm) in the refractive index ellipsoid formed by the second phase difference layer in a direction parallel to the film plane, ny2(λ) denotes a refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of the aforementioned nx2(λ) in which nx2(λ) ═ ny2(λ), nx2(λ) denotes a refractive index in an arbitrary direction parallel to the film plane, and d2 denotes a thickness of the second phase difference layer. here, in addition, by "nx 2(λ) ≈ ny2(λ)", it is meant that nx2(λ) is substantially the same as ny2(λ), and for example, it indicates: the difference between the values is within 0.01)

The optical film of the present invention has a first retardation layer and a second retardation layer, and satisfies the relationships of the following formulae (1) and (2).

0.40≤Nz(450)≤0.60 (1)

0.40≤Nz(550)≤0.60 (2)

(wherein Nz (λ) is an Nz coefficient showing a three-dimensional refractive index relationship for light of a wavelength λ (nm), which is represented by Nz (λ) ═ (nx (λ) -Nz (λ))/(nx (λ) -ny (λ)). nx (λ)) represents, in a refractive index ellipsoid formed by the optical film, a principal refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane

That is, the optical film of the present invention has a three-dimensional refractive index relationship of nx (λ) > nz (λ) > ny (λ), and by making the optical film have the relationship of the formula (1) and the formula (2), it is possible to impart display characteristics excellent in color tone when mounted on a display. With respect to Nz (. lamda.), further preferred are 0.45. ltoreq. Nz (450). ltoreq.0.55, 0.45. ltoreq. Nz (550). ltoreq.0.55, respectively. Here, Nz (450) denotes an Nz coefficient at a wavelength λ of 450nm, and Nz (550) denotes an Nz coefficient at a wavelength λ of 550nm, respectively.

The Nz coefficient (Nz coefficient: Nz (λ)) (which embodies the relationship of nx (λ), ny (λ), Nz (λ) at each wavelength λ (nm) of the optical film) is calculated by the following formula.

Nz(λ)＝(nx(λ)-nz(λ))/(nx(λ)-ny(λ))

When the front retardation value and the thickness direction retardation value of the first retardation layer and the second retardation layer are known, the Nz coefficient of the optical film can be calculated by the following formula (C).

Nz(λ)＝(Rth1(λ)+Rth2(λ))/(Re1(λ)+Re2(λ))+0.5(C)

(wherein Re1(λ) is a front phase difference value of the first retardation layer at a wavelength λ (nm), Re2(λ) is a front phase difference value of the second retardation layer at a wavelength λ (nm), Rth1(λ) is a phase difference value at a wavelength λ (nm) in a thickness direction of the first retardation layer, Rth2(λ) is a phase difference value at a wavelength λ (nm) in a thickness direction of the second retardation layer.)

[ polymerizable liquid Crystal ]

The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group, particularly a photopolymerizable functional group.

The photopolymerizable functional group means a group that can participate in a polymerization reaction by an active radical generated from a photopolymerization initiator, an acid, or the like. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxetanyl group, and the like. Among them, acryloyloxy, methacryloyloxy, vinyloxy, oxetanyl and oxetanyl are preferable, and acryloyloxy is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferable because the film thickness can be strictly controlled. The phase-ordered structure in the thermotropic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal.

In the present invention, the polymerizable liquid crystal compound is particularly preferably a structure represented by the following formula (I) in view of exhibiting the above-described inverse wavelength dispersibility.

[ chemical formula 1]

In the formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group as used herein means a group having a planar and cyclic structure, and [4n +2] having a number of pi electrons in the cyclic structure according to the houcker rule. Here, n represents an integer. When a ring structure is formed by including a heteroatom such as — N ═ or — S —, the following are also included: including non-covalent bond electron pairs on these heteroatoms, and which satisfy the Huckel rule, and have aromaticity. The divalent aromatic group preferably contains at least 1 or more of a nitrogen atom, an oxygen atom, and a sulfur atom.

G¹And G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Wherein the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be replaced by a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, cyanogenA group which is substituted with a nitro group, the carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom or a nitrogen atom.

L¹、L²、B¹And B²Each independently is a single bond or a divalent linking group.

k. l each independently represents an integer of 0 to 3, and satisfies the relationship of 1. ltoreq. k + l. Here, when 2. ltoreq. k + l, B ¹And B²、G¹And G²May be the same or different from each other.

E¹And E²Each independently represents an alkanediyl (alkanediyl) having 1 to 17 carbon atoms in which a hydrogen atom contained in the alkanediyl group may be substituted by a halogen atom, and which contains-CH₂-can be replaced by-O-, -S-, -Si-. P is¹And P²Independently of each other, a polymerizable group or a hydrogen atom, and at least 1 is a polymerizable group.

G¹And G²Each independently is preferably a 1, 4-phenylene group (phenylenediyl group) which may be substituted with at least 1 substituent selected from a halogen atom and an alkyl group having 1 to 4 carbon atoms, a 1, 4-cyclohexanediyl group which may be substituted with at least 1 substituent selected from a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a 1, 4-phenylene group which may be substituted with a methyl group, an unsubstituted 1, 4-phenylene group, or an unsubstituted 1, 4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1, 4-phenylene group or an unsubstituted 1, 4-trans-cyclohexanediyl group.

In addition, it is preferable that a plurality of G's are present¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group, and is more preferably bonded to L¹Or L²Bonded G¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group.

L¹And L²Independently of each other, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R- ^a1OR^a2-、-R^a3COOR^a4-、-R^a5OCOR^a6-、-R^a7OC＝OOR^a8-、-N＝N-、-CR^c＝CR^d-, or-C.ident.C-. Here, R^a1～R^a8Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, R^cAnd R^dRepresents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L is a radical of an alcohol¹And L²Each independently more preferably a single bond, -OR^a2-1-、-CH₂-、-CH₂CH₂-、-COOR^a4-1-, or-OCOR^a6-1-. Here, R^a2-1、R^a4-1、R^a6-1Each independently represents a single bond, -CH₂-、-CH₂CH₂-any of the above. L is¹And L²Further preferably a single bond, -O-, -CH₂CH₂-、-COO-、-COOCH₂CH₂-, or-OCO-.

B¹And B²Independently of each other, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R-^a9OR^a10-、-R^a11COOR^a12-、-R^a13OCOR^a14-, or-R^a15OC＝OOR^a16-. Here, R^a9～R^a16Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. B is¹And B²Each independently more preferably a single bond, -OR^a10-1-、-CH₂-、-CH₂CH₂-、-COOR^{a12 -1}-, or-OCOR^a14-1-. Here, R^a10-1、R^a12-1、R^a14-1Each independently represents a single bond, -CH₂-、-CH₂CH₂-any of the above. B is¹And B²Further preferably a single bond, -O-, -CH₂CH₂-、-COO-、-COOCH₂CH₂-, -OCO-, or-OCOCH₂CH₂-。

From the viewpoint of exhibiting reverse wavelength dispersibility, k and l are preferably in the range of 2 ≦ k + l ≦ 6, more preferably k + l ═ 4, and still more preferably k ═ 2 and l ═ 2.

E¹And E²Each independently is preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

As P¹Or P²Examples of the polymerizable group include an epoxy group, a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxetanyl group, and an oxetanyl group.

Among them, acryloyloxy, methacryloyloxy, vinyloxy, oxetanyl and oxetanyl are preferable, and acryloyloxy is more preferable.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include benzene ring, naphthalene ring, anthracene ring, etc., and benzene ring and naphthalene ring are preferable. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferable, and a benzothiazolyl group is more preferable. When Ar contains a nitrogen atom, the nitrogen atom preferably has pi electrons.

In the formula (I), the total number N of pi electrons contained in the 2-valent aromatic group represented by Ar_πPreferably 8 or more, more preferably 10 or more, still more preferably 14 or more, and particularly preferably 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

Examples of the aromatic group represented by Ar include the following groups.

[ chemical formula 2]

In the formulae (Ar-1) to (Ar-22), symbol denotes a linker, Z⁰、Z¹And Z²Each independently represents a hydrogen atom, a halogen atom, or a carbon atom having 1 to 12 carbon atomsThe alkyl group, cyano group, nitro group, alkylsulfinyl group having 1 to 12 carbon atoms, alkylsulfonyl group having 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, alkylthio group having 1 to 12 carbon atoms, N-alkylamino group having 1 to 12 carbon atoms, N-dialkylamino group having 2 to 12 carbon atoms, N-alkylsulfamoyl group having 1 to 12 carbon atoms, or N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q¹And Q²Each independently represents-CR^2’R^3’-、-S-、-NH-、-NR^2’-, -CO-or-O-, R^2’And R^3’Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J¹And J²Each independently represents a carbon atom or a nitrogen atom.

Y¹、Y²And Y³Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

W¹And W²Each independently represents a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer of 0 to 6.

As Y¹、Y²And Y³The aromatic hydrocarbon group in (1) includes aromatic hydrocarbon groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, preferably a phenyl group and a naphthyl group, and more preferably a phenyl group. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least 1 hetero atom (nitrogen atom, oxygen atom, sulfur atom, etc.) such as furyl group, pyrrolyl group, thienyl group, pyridyl group, thiazolyl group, benzothiazolyl group and the like, and preferably furyl group, thienyl group, pyridyl group, thiazolyl group and benzothiazolyl group.

Y¹、Y²And Y³Each independently may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. The polycyclic aromatic hydrocarbon group means a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group means a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z⁰、Z¹And Z²Each independently preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, Z⁰More preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, Z¹And Z²More preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a cyano group.

Q¹And Q²preferably-NH-, -S-, -NR^2’-、-O-，R^2’Preferably a hydrogen atom. Among them, -S-, -O-, -NH-are particularly preferred.

Among the formulae (Ar-1) to (Ar-22), the formulae (Ar-6) and (Ar-7) are preferable from the viewpoint of molecular stability.

In the formulae (Ar-16) to (Ar-22), Y¹Nitrogen atom and Z which may be bonded thereto⁰Together form an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include those described above as the aromatic heterocyclic ring that Ar may have, and examples thereof include a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. The aromatic heterocyclic group may have a substituent. In addition, Y ¹Nitrogen atom and Z which may be bonded thereto⁰Together with the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

The total content of the polymerizable liquid crystal compound in 100 parts by mass of the solid components of the composition for forming a retardation layer is usually 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 80 to 94 parts by mass, and still more preferably 80 to 90 parts by mass. When the total content is within the above range, the alignment property of the polymerizable liquid crystal compound in the obtained retardation layer tends to be improved. The solid component herein refers to the total amount of components obtained by removing the solvent from the composition.

[ solvent ]

The solvent is preferably a solvent capable of dissolving the polymerizable liquid crystal compound, and is preferably a solvent inert to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of the solvent include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1, 3-dimethyl-2-imidazolidinone. These solvents may be used alone in 1 kind, or in combination of 2 or more kinds. Among them, alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide solvents, and aromatic hydrocarbon solvents are preferable.

The content of the solvent in 100 parts by mass of the composition is preferably 50 to 98 parts by mass, and more preferably 70 to 95 parts by mass. Therefore, the content of the solid content is preferably 2 to 50 parts by mass in 100 parts by mass of the composition. When the solid content of the composition is 50 parts by mass or less, the viscosity of the composition decreases, and therefore, the thickness of the retardation layer becomes substantially uniform, and unevenness is less likely to occur in the retardation layer. The solid component can be appropriately determined in consideration of the thickness of the retardation layer to be produced.

< polymerization initiator >

The polymerization initiator is a compound which generates reactive species by the action of heat or light and initiates a polymerization reaction such as a polymerizable liquid crystal. Examples of the reactive species include active species such as radicals, cations, and anions. Among them, from the viewpoint of easy control of the reaction, a photopolymerization initiator which generates radicals by light irradiation is preferable.

Examples of the photopolymerization initiator include benzoin compounds, benzophenone compounds, benzil ketal compounds, α -hydroxyketone compounds, α -aminoketone compounds, triazine compounds, iodonium salts, and sulfonium salts. Specifically, Irgacure (イルガキュア, registered trademark) 907, Irgacure184, Irgacure651, Irgacure819, Irgacure250, Irgacure369, Irgacure379, Irgacure127, Irgacure2959, Irgacure754, Irgacure379EG (manufactured by BASF Japan K.K.), SEIKUOL BZ, SEIKUOL Z, SEIKUBEOL E (manufactured by Seiko Chemicals Co., Ltd.), kayakure (カヤキュアー) BP100 (manufactured by Nippon Chemical Co., Ltd.), kayasu UVI-6992 (manufactured by DOW Chemical Company), ADEKA OPMER SP-152, ADEKA OPMER SP-170, ADEKA OPMER N-1717, ADTOMER N-9, ADEKA OPMER SP-ADEKA ARKLS NCI-54 (manufactured by Co., Ltd.), and SANDWARE Co., Ltd., and IRWARE CO-A, TAZ (manufactured by Japan), and the aforementioned SeIkura Chemical Company Lgacure 191104, and the aforementioned Company, and the product of TAIkura Sporober 191104, the aforementioned.

The composition for forming a retardation layer contains at least 1 kind of photopolymerization initiator, preferably 1 or 2 kinds of photopolymerization initiator.

The photopolymerization initiator preferably has a maximum absorption wavelength of 300nm to 400nm, more preferably 300nm to 380nm, and particularly preferably an α -acetophenone polymerization initiator or an oxime photopolymerization initiator, in order to make full use of energy emitted from a light source and to achieve excellent productivity.

Examples of the α -acetophenone compound include 2-methyl-2-morpholino (morpholino) -1- (4-methylsulfanylphenyl) propan-1-one, 2-dimethylamino-1- (4-morpholinophenyl) -2-benzylbutan-1-one, and 2-dimethylamino-1- (4-morpholinophenyl) -2- (4-methylphenylmethyl) butan-1-one, more preferably, 2-methyl-2-morpholino-1- (4-methylsulfanylphenyl) propan-1-one and 2-dimethylamino-1- (4-morpholinophenyl) -2-benzylbutan-1-one are mentioned. Commercially available products of the α -acetophenone compound include Irgacure369, 379EG, 907 (manufactured by BASF Japan, inc.) and SEIKUOL BEE (manufactured by SEIKUOL chemical corporation).

The oxime-based photopolymerization initiator generates a methyl radical when irradiated with light. The methyl radical acts to appropriately polymerize the polymerizable liquid crystal compound in the deep portion of the retardation layer. In addition, from the viewpoint of more efficiently carrying out the polymerization reaction in the deep portion of the retardation layer, it is preferable to use a photopolymerization initiator capable of efficiently using ultraviolet rays having a wavelength of 350nm or more. As the photopolymerization initiator capable of efficiently using ultraviolet rays having a wavelength of 350nm or more, triazine compounds and oxime ester type carbazole compounds are preferable, and oxime ester type carbazole compounds are more preferable from the viewpoint of sensitivity. Examples of the oxime ester type carbazole compound include 1, 2-octanedione-1- [4- (phenylsulfanyl) -2- (O-benzoyloxime) ] (1,2-octanedione,1- [4- (phenylthio) -2- (O-benzoyloxime) ], 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetyloxime) (ethanone,1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -1- (O-acetoxyoxime)), and the like. Commercially available products of the oxime ester type carbazole compounds include IrgacureOXE-01, IrgacureOXE-02, IrgacureOXE-03 (manufactured by BASF Japan K.K., Ltd.), ADEKA OPTOMER N-1919, and ADEKA ARKLS NCI-831 (manufactured by ADEKA, Ltd.).

The amount of the photopolymerization initiator added is usually 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, and more preferably 1 to 15 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the amount of the photopolymerization initiator added is within the above range, the reaction of the polymerizable group proceeds sufficiently, and the alignment of the polymerizable liquid crystal compound is not easily disturbed.

The polymerization reaction of the polymerizable liquid crystal compound can be controlled by blending a polymerization inhibitor. Examples of the polymerization inhibitor include hydroquinone and hydroquinone having a substituent such as an alkyl ether group; catechol and other catechol-containing substituents such as alkyl ether groups; pyrogallols; radical scavengers such as 2,2,6, 6-tetramethylpiperidine-1-oxyl radical; thiophenols; beta-naphthylamines and beta-naphthols. The content of the polymerization inhibitor is usually 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound, in order to polymerize the polymerizable liquid crystal compound without disturbing the alignment of the polymerizable liquid crystal compound.

Further, by using a sensitizer, the photopolymerization initiator can be made highly sensitive. Examples of the photosensitizing agent include xanthones such as xanthone and thioxanthone; anthracene and anthracene having a substituent such as an alkyl ether group; phenothiazine; rubrene. The content of the photosensitizer is usually 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound.

[ leveling agent ]

The leveling agent is an additive having a function of adjusting the fluidity of the composition and flattening a film obtained by coating the composition, and examples thereof include silicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents such as silane coupling agents. Specifically, there may be mentioned DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all of which are made by Dow Corning Toray Co., Ltd.), Ltd. system), KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001, KBM-1003, KBE-1003, KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KBM-1403, KBM-502, KBM-503, KBE-502, KBE-503, TSKBM-5103, KBM-602, KBM-603, KBM-903, KBE-9103, KBM-846, KBM-575, TSKBM-802, TSKBM-430803, TSKBM-44803, TSBE-4480, TSBE-4445, KBM-4480, KBM-410, KBM-401, KBM-410, KBE-401, TSF 4480, TSBE-4420, TSBE-400, TSF-4480, TSBE-102, KBM-441, KBM-400, KBM-4445, KBM-410, KBM-80, KBM-102, KBM-150, KBM-K4, KBM-K-410, KBM-K, KBM-K-150, KBM-K-400, KBM-K-150, KBM-K-400, KBM-K, KBM-K, KBM-K, KBM-3, KBM-K, KBM-400, KBM-K, KBM-3, KBM-K, KBM-400, KBM-K, KBM-3, KBM-K, KBM-K, KBM, TSF4452, TSF4460 (both of which are manufactured by Momentive Performance Materials Japan LLC), fluorinert (フロリナート) (registered trademark) FC-72, fluorinert FC-40, fluorinert FC-43, fluorinert FC-3283 (both of which are manufactured by Sumitomo 3M Co., Ltd.), MEGAFACE (メガファック) (registered trademark) R-08, MEGAFACE R-30, MEGAFACE R-90, MEGAFACE F-410, MEGAFACE F-411, MEGAFACE F-443, MEGAFACE F-445, MEGAFACE F-470, MEGAFACE F-477, MEGAFACE F-479, MEGAFACE F-482, MEGAFACE F-483 (both of which are manufactured by DIC Co., Ltd.), EFTOP (trade name) EF301, EFEF 303, EFTOP EF351, EFTOP EF352 (both of which are manufactured by Mitsubishi Materials plastics Co., Lloy. Co., Ltd.), and registered trademark S-381, S-382, Surflon S-383, Surflon S-393, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all of which are AGC Seimi Chemical Co., Ltd., manufactured by Ltd.), trade name E1830, trade name E5844(Daikin Fine Chemical Laboratory Co., manufactured by Ltd.), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all of which are trade names manufactured by BM Chemie).

The content of the leveling agent in the retardation layer forming composition is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound tends to be easily horizontally aligned, and the resulting retardation layer tends to be smoother, which is preferable. The composition for forming a retardation layer may contain 2 or more leveling agents.

[ base Material ]

The substrate includes a glass substrate and a film substrate, and the film substrate is preferable from the viewpoint of workability, and a long rolled film is more preferable from the viewpoint of continuous production. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene polymers; a cycloolefin resin; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; a polyacrylate; cellulose esters such as triacetylcellulose, diacetylcellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfones; polyether sulfone; a polyether ketone; polyphenylene sulfide and polyphenylene oxide.

Examples of commercially available cellulose ester substrates include "Fujitac Film" (manufactured by Fuji Photo Film co., ltd.); "KC 8UX 2M", "KC 8 UY" and "KC 4 UY" (manufactured by Konica Minolta Opto Co., Ltd.).

Examples of commercially available cycloolefin resins include "Topas" (registered trademark) (manufactured by Ticona corporation, germany), "ARTON" (registered trademark) (manufactured by JSR corporation), "ZEONOR (ゼオノア)" (registered trademark), "ZEONEX (ゼオネックス)" (registered trademark) (manufactured by japan ZEON corporation), and "APEL" (registered trademark) (manufactured by mitsui chemical co). Such a cycloolefin resin can be formed into a film as a base material by a known means such as a solvent casting method or a melt extrusion method. Commercially available cycloolefin resin substrates can also be used. Examples of commercially available cycloolefin resin base materials include "ESCENA" (registered trademark), "SCA 40" (registered trademark) (manufactured by waterlogging chemical industries co., ltd.), "ZEONOR FILM" (registered trademark) (manufactured by OPTES co., ltd.), and "ARTON FILM" (registered trademark) (manufactured by JSR co., ltd.).

The thickness of the base material is preferably small in terms of quality to the extent that practical handling becomes possible, but if it is too thin, the strength tends to decrease, and the workability tends to be poor. The thickness of the substrate is usually 5 to 300. mu.m, preferably 20 to 200. mu.m. Further, by peeling the substrate and transferring only the polymer in a state in which the polymerizable liquid crystal compound is aligned, an effect of further thinning can be obtained.

[ alignment film ]

Preferably, an alignment film is formed on the surface of the substrate to which the composition for forming a retardation layer is to be applied. The alignment film is a film having an alignment controlling force for aligning the polymerizable liquid crystal compound in a desired direction.

The alignment film is preferably one having solvent resistance (not being dissolved by coating of the composition for forming a retardation layer or the like) and heat resistance (being resistant to heat treatment for removing the solvent or aligning a polymerizable liquid crystal compound described later).

Such an alignment film facilitates alignment of the polymerizable liquid crystal compound. Various orientations such as vertical orientation, horizontal orientation, hybrid (hybrid) orientation, and tilt orientation can be controlled by the type of alignment film, rubbing conditions, and light irradiation conditions.

As the alignment film forming the first retardation layer, an alignment film exhibiting an alignment controlling force in the horizontal direction may be applied. Examples of such a horizontal alignment film include a rubbing alignment film, a photo-alignment film, and a groove alignment film having a concave-convex pattern or a plurality of grooves on the surface thereof. When applied to a long roll film, the photo-alignment film is preferred in that the alignment direction can be easily controlled.

In the rubbing alignment film, an alignment polymer can be used. Examples of the orientation polymer include polyamide having an amide bond, gelatins, polyimide having an imide bond, and a hydrolysate thereof, polyamide acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazoles, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylates. More than 2 kinds of alignment polymers may be combined.

In general, a rubbing alignment film can be provided with an alignment control force by applying a composition obtained by dissolving an alignment polymer in a solvent (hereinafter, also referred to as an alignment polymer composition) to a base material, removing the solvent to form a coating film, and rubbing the coating film.

The concentration of the alignment polymer in the alignment polymer composition may be within a range in which the alignment polymer can be completely dissolved in the solvent. The content of the oriented polymer in the oriented polymer composition is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass.

Oriented polymer compositions are commercially available. Examples of the commercially available oriented polymer composition include suniver (registered trademark, manufactured by nippon chemical industry corporation), OPTMER (registered trademark, manufactured by JSR corporation), and the like.

The method of applying the alignment polymer composition to the substrate may be the same as the method of applying the composition for forming a phase difference layer to the substrate, which will be described later. Examples of the method for removing the solvent contained in the oriented polymer composition include a natural drying method, a forced air drying method, a heat drying method, and a reduced pressure drying method.

As a method of the rubbing treatment, for example, a method of bringing a rotating rubbing roll wound with a rubbing cloth into contact with the coating film is given. When the rubbing treatment is performed, a plurality of regions (patterns) having different alignment directions may be formed on the alignment film by masking (masking).

The photo alignment film can be obtained by applying a photo alignment film-forming composition containing a polymer or monomer having a photoreactive group and a solvent to a substrate, removing the solvent, and then irradiating polarized light (preferably polarized UV light). In the photo alignment film, the direction of alignment control force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

The photoreactive group refers to a group that can be aligned by light irradiation. Specifically, there may be mentioned groups participating in a photoreaction that is a source of an alignment ability, such as an alignment induction reaction, an isomerization reaction, a photodimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction of molecules that occurs upon light irradiation. The photoreactive group is preferably a group having an unsaturated bond, particularly a double bond, and particularly preferably at least one selected from the group consisting of a carbon-carbon double bond (C ═ C bond), a carbon-nitrogen double bond (C ═ N bond), a nitrogen-nitrogen double bond (N ═ N bond), and a carbon-oxygen double bond (C ═ O bond).

Examples of the photoreactive group having a C ═ C bond include a vinyl group, a polyene group, a stilbene group, a stilbenazolyl group, a stilbenazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C ═ N bond include groups having a structure such as an aromatic schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N ═ N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, a formazan (formazan) group, and a group having an azoxybenzene structure. Examples of the photoreactive group having a C ═ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and haloalkyl groups.

From the viewpoint of excellent orientation, a group participating in a photodimerization reaction or a photocrosslinking reaction is preferred. Among them, a photoreactive group participating in a photodimerization reaction is preferable, and cinnamoyl group and chalcone group are preferable in terms of a small amount of polarized light irradiation required for alignment and easy obtainment of a photo alignment film excellent in thermal stability and temporal stability. The polymer having a photoreactive group is particularly preferably a polymer having a cinnamoyl group in which a terminal portion of a side chain of the polymer has a cinnamic acid structure or a cinnamate structure.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo alignment film may be adjusted according to the kind of the polymer or monomer and the thickness of the target photo alignment film, and is preferably at least 0.2 mass% or more, and more preferably in the range of 0.3 to 10 mass%.

The method of applying the composition for forming a photo-alignment film to a substrate may be the same as the method of applying the composition for forming a phase difference layer to a substrate, which will be described later. The method of removing the solvent from the applied composition for forming a photo-alignment film may be the same as the method of removing the solvent from the alignment polymer composition.

The irradiation with polarized light may be performed by directly irradiating polarized light to a product obtained by removing a solvent from the composition for forming a photo-alignment film applied to the substrate, or by irradiating polarized light from the substrate side and transmitting the polarized light through the substrate. The polarized light is preferably substantially parallel light. The wavelength of the polarized light to be irradiated is preferably a wavelength in a wavelength region where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet) light having a wavelength of 250nm to 400nm is particularly preferable. Examples of the light source for irradiating the polarized light include a xenon lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and ultraviolet laser such as KrF and ArF. Among them, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, and a metal halide lamp are preferable because the emission intensity of ultraviolet rays having a wavelength of 313nm is large. Polarized UV light can be irradiated by transmitting light emitted from the light source through an appropriate polarizer. Examples of the polarizing element include a polarizing filter, a polarizing prism such as glan-thompson and glan-taylor, and a wire grid. Among them, a wire grid type polarizing element is preferable from the viewpoint of increasing the area and the resistance to heat.

In addition, when the polarized light is irradiated, a plurality of regions (patterns) having different liquid crystal alignment directions may be formed by masking.

A groove (groove) alignment film is a film having a concave-convex pattern or a plurality of grooves (grooves) on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at equal intervals, liquid crystal molecules are aligned in a direction along the grooves.

As a method for obtaining a groove alignment film, the following methods can be mentioned: a method of forming a concave-convex pattern by exposing the surface of a photosensitive polyimide film through an exposure mask having a slit in a pattern shape, and then performing development and rinsing; a method of forming a layer of a UV curable resin before curing on a plate-like original plate having grooves on the surface thereof, transferring the resin layer to a base material, and curing the resin layer; and a method in which a roll-shaped original plate having a plurality of grooves is pressed against a film of a UV curable resin before curing, which is formed on a base material, to form irregularities, and then the irregularities are cured; and so on.

The thickness of the alignment film for forming the first retardation layer is usually in the range of 10 to 10000nm, preferably 10 to 1000nm, and more preferably 50 to 500 nm.

As an alignment film for forming the second retardation layer, an alignment film having an alignment controlling force in a vertical direction (hereinafter, also referred to as a vertical alignment film) can be used. As the vertical alignment film, a material that reduces the surface tension of the substrate surface is preferably used. Examples of such materials include the aforementioned alignment polymers, fluorine-based polymers such as perfluoroalkyl groups, polyimide compounds, silane compounds, and polysiloxane compounds obtained by condensation reaction thereof. From the viewpoint of easiness of lowering the surface tension, a silane compound is preferable.

Examples of the silane compound include the organosilicon compounds such as the aforementioned silane coupling agents, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and the like, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane and the like. More than 2 kinds of silane compounds may be used.

The silane compound may be a silane compound of an organosilicon monomer type or a silane compound of an organosilicon oligomer (polymer) type. When the silicone oligomer is represented as a (monomer) - (monomer) copolymer, the following may be mentioned, for example.

Copolymers containing a mercaptopropyl group such as 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer;

mercaptomethyl group-containing copolymers such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer;

3-methacryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer, A methacryloxypropyl-containing copolymer;

3-acryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer, A copolymer containing acryloyloxypropyl groups;

vinyl group-containing copolymers such as vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;

Amino group-containing copolymers such as 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxysilane-tetraethoxysilane copolymer.

Among these, silane compounds having an alkyl group at the molecular terminal are preferable, and silane compounds having an alkyl group having 6 to 20 carbon atoms are more preferable. These silane compounds are often liquid and therefore can be applied to the substrate either directly or after being dissolved in a solvent. In addition, the binder may be dissolved in a solvent together with various polymers and applied to a substrate.

The method of applying the vertical alignment film to the substrate may be the same as the method of applying the composition for forming a phase difference layer to the substrate, which will be described later. The method of removing the solvent from the applied composition for forming a photo-alignment film may be the same as the method of removing the solvent from the alignment polymer composition.

The thickness of the alignment film for forming the second phase difference layer is usually in the range of 10 to 10000nm, preferably in the range of 50 to 5000nm, and more preferably in the range of 100 to 500 nm.

Method for producing retardation layer

< coating of composition for Forming phase Difference layer >

The retardation layer can be formed by applying the composition for forming a retardation layer on the substrate or the alignment film. Examples of a method for applying the composition for forming a phase difference layer to a substrate include an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, a slit coating method, a micro gravure coating method, a die coating method, and an ink jet method. Further, a method of coating using a coater such as a dip coater, a bar coater, or a spin coater, and the like can be mentioned. Among them, when the coating is continuously performed by a Roll-to-Roll (Roll) method, a coating method using a micro gravure method, an ink jet method, a slit coating method, or a die coating method is preferable, and when the coating is performed on a monolithic substrate such as glass, a spin coating method having high uniformity is preferable.

< drying of composition for Forming phase Difference layer >

Examples of the drying method for removing the solvent contained in the phase difference layer forming composition include natural drying, air drying, heat drying, reduced pressure drying, and a method of combining these. Among them, natural drying or heat drying is preferable. The drying temperature is preferably in the range of 0 to 200 ℃, more preferably in the range of 20 to 150 ℃, and still more preferably in the range of 50 to 130 ℃. The drying time is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes. The composition for forming a photo-alignment film and the alignment polymer composition may be dried in the same manner.

< polymerization of polymerizable liquid Crystal Compound >

As a method of polymerizing the polymerizable liquid crystal compound, photopolymerization is preferable. Photopolymerization can be carried out by irradiating a laminate obtained by applying a composition for forming a retardation layer containing a polymerizable liquid crystal compound onto a substrate or an alignment film with active energy rays. The active energy ray to be irradiated may be appropriately selected depending on the type of the polymerizable liquid crystal compound contained in the dry film (particularly, the type of the photopolymerizable functional group of the polymerizable liquid crystal compound), the type of the photopolymerization initiator when the photopolymerization initiator is contained, and the amounts thereof. Specifically, the light may be at least one light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α -rays, β -rays, and γ -rays. Among them, ultraviolet light is preferable in terms of easy control of the progress of the polymerization reaction and the use of a photopolymerization device widely used in the art, and it is preferable to select the type of the polymerizable liquid crystal compound so that photopolymerization can be performed by ultraviolet light.

Examples of the light source of the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light in a wavelength range of 380 to 440nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, and the like.

The intensity of ultraviolet irradiation is usually 10mW/cm²～3,000mW/cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the cationic polymerization initiator or the radical polymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 0.1 secondAbout 5 minutes, more preferably about 0.1 second to about 3 minutes, and still more preferably about 0.1 second to about 1 minute. When the ultraviolet irradiation intensity is applied for 1 or more times, the cumulative light amount is 10mJ/cm²～3,000mJ/cm²Preferably 50mJ/cm²～2,000mJ/cm²More preferably 100mJ/cm²～1,000mJ/cm². When the cumulative light amount is less than the above range, the curing of the polymerizable liquid crystal compound may be insufficient, and good transferability may not be obtained. On the other hand, when the accumulated light amount is not less than the above range, the optical film including the retardation layer may be colored.

[ polarizing plate ]

The elliptically polarizing plate of the present invention is configured to include a polarizing plate and the optical film of the present invention, and the elliptically polarizing plate of the present invention can be obtained by, for example, laminating the polarizing plate and the optical film of the present invention via an adhesive agent, an adhesive layer, or the like.

In one embodiment of the present invention, when the polarizing plate and the optical film of the present invention are laminated, the slow axis (optical axis) of the first retardation layer and the absorption axis of the polarizing plate are preferably laminated so as to be substantially 45 °. The optical film of the present invention is laminated so that the slow axis (optical axis) and the absorption axis of the polarizing plate are substantially 45 °, and thus functions as a circular polarizing plate. The angle is substantially 45 °, and is usually in the range of 45 ± 5 °.

The polarizing plate is formed of a polarizer having a polarizing function. Examples of the polarizer include a stretched film in which a dye having absorption anisotropy is adsorbed, and a film in which a dye having absorption anisotropy is applied and oriented. Examples of the dye having absorption anisotropy include a dichroic dye.

The stretched film having the dye having absorption anisotropy adsorbed thereon can be usually produced through the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing a polyvinyl alcohol resin film with a dichroic dye to thereby adsorb the dichroic dye; treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the boric acid aqueous solution. The polarizer obtained in the above manner is bonded to a transparent protective film, whereby a polarizing plate can be obtained. Examples of the dichroic dye include iodine and a dichroic organic dye. Examples of dichroic organic dyes include: dichroic direct dyes containing disazo compounds such as c.i. direct red (DIRECT RED)39, dichroic direct dyes containing trisazo compounds, tetraazo compounds, and the like. The thickness of the polarizer obtained by uniaxially stretching the polyvinyl alcohol resin film, dyeing with a dichroic dye, boric acid treatment, washing with water, and drying as described above is preferably 5 to 40 μm.

[ Binder ]

Examples of the adhesive used for bonding the optical film of the present invention to the polarizing plate or bonding the optical film of the present invention to the display device include a pressure-sensitive adhesive, a dry curing adhesive, and a chemical reaction adhesive. Examples of the chemically reactive adhesive include an active energy ray-curable adhesive. The adhesive layer between the polarizing plate and the optical film of the present invention is preferably an adhesive layer formed of a pressure-sensitive adhesive, a dry curing adhesive, or an active energy ray curing adhesive, and the adhesive material between the optical film of the present invention and the display device is preferably a pressure-sensitive adhesive or an active energy ray curing adhesive.

Pressure sensitive adhesives typically comprise a polymer and may also comprise a solvent.

Examples of the polymer include an acrylic polymer, a silicone polymer, a polyester, a polyurethane, and a polyether. Among these, acrylic adhesives containing an acrylic polymer are preferable because they are excellent in optical transparency, have appropriate wettability and cohesive force, are excellent in adhesion, are excellent in weather resistance and heat resistance, and are less likely to cause floating, peeling, and the like under heating or humidifying conditions.

The acrylic polymer is preferably a copolymer of (meth) acrylate in which the alkyl group of the ester moiety is an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a butyl group (hereinafter, acrylate and methacrylate may be collectively referred to as (meth) acrylate, and acrylic acid and methacrylic acid may be collectively referred to as (meth) acrylic acid) and a (meth) acrylic monomer having a functional group such as (meth) acrylic acid or hydroxyethyl (meth) acrylate.

A pressure-sensitive adhesive containing such a copolymer is preferable because it has excellent adhesion, does not cause a residue of adhesive or the like on a display device even when removed after being attached to the display device, and can be removed relatively easily. The glass transition temperature of the acrylic polymer is preferably 25 ℃ or lower, more preferably 0 ℃ or lower. The mass average molecular weight of such an acrylic polymer is preferably 10 ten thousand or more.

Examples of the solvent include the solvents listed above as solvents. The pressure sensitive adhesive may contain a light diffuser. The light diffusing agent is an additive for imparting light diffusibility to the binder, and may be fine particles having a refractive index different from the refractive index of the polymer contained in the binder. Examples of the light diffusing agent include fine particles made of an inorganic compound and fine particles made of an organic compound (polymer). Since most of polymers including acrylic polymers and containing a binder as an active ingredient have a refractive index of about 1.4 to 1.6, it is preferable to select them as appropriate from light diffusing agents having a refractive index of 1.2 to 1.8. The difference in refractive index between the polymer contained as the active ingredient in the binder and the light diffusing agent is usually 0.01 or more, and preferably 0.01 to 0.2 from the viewpoint of brightness and display of the display device. The fine particles used as the light diffusing agent are preferably spherical and nearly monodisperse fine particles, and more preferably fine particles having an average particle diameter of 2 to 6 μm. The refractive index can be measured using a conventional minimum deviation angle method or abbe refractometer.

Examples of the fine particles made of an inorganic compound include alumina (refractive index 1.76) and silica (refractive index 1.45). Examples of the fine particles made of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate/styrene copolymer resin beads (refractive index 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), and silicone resin beads (refractive index 1.46). The content of the light diffusing agent is usually 3 to 30 parts by mass with respect to 100 parts by mass of the polymer.

The thickness of the pressure-sensitive adhesive is not particularly limited since it can be determined depending on the adhesive force thereof, and is usually 1 μm to 40 μm. The thickness is preferably 3 to 25 μm, more preferably 5 to 20 μm, from the viewpoint of processability, durability, and the like. By setting the thickness of the adhesive layer formed of the adhesive to 5 μm to 20 μm, the brightness can be maintained when the display device is viewed from the front or when the display device is viewed from an oblique direction, and the display image is less likely to be blurred or smeared.

[ Dry curing adhesive ]

The dry curing adhesive may contain a solvent.

Examples of the dry curing adhesive include a composition containing a polymer of a monomer having a protic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group, or a polyurethane resin as a main component, and further containing a crosslinking agent or a curable compound such as a polyaldehyde, an epoxy compound, an epoxy resin, a melamine compound, a zirconium oxide compound, or a zinc compound. Examples of the polymer of the monomer having a protic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group include an ethylene-maleic acid copolymer, an itaconic acid copolymer, an acrylic acid copolymer, an acrylamide copolymer, a saponified product of polyvinyl acetate, and a polyvinyl alcohol resin.

Examples of the polyvinyl alcohol resin include polyvinyl alcohol, partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, hydroxymethyl-modified polyvinyl alcohol, and amino-modified polyvinyl alcohol. The content of the polyvinyl alcohol resin in the aqueous binder is usually 1 to 10 parts by mass, and preferably 1 to 5 parts by mass, with respect to 100 parts by mass of water.

Examples of the polyurethane resin include polyester-based ionomer polyurethane resins.

The polyester type ionomer urethane resin here means a urethane resin having a polyester skeleton and a small amount of ionic component (hydrophilic component) introduced therein. The ionomer type polyurethane resin is emulsified in water without using an emulsifier to form an emulsion, and thus can be used as an aqueous adhesive. When a polyester type ionomer urethane resin is used, it is effective to incorporate a water-soluble epoxy compound as a crosslinking agent.

Examples of the epoxy resin include polyamide epoxy resins obtained by reacting epichlorohydrin with a polyamide polyamine (polyalkylene polyamine) (which is obtained by reacting a polyalkylene polyamine (polyalkylene polyamine) such as diethylenetriamine or triethylenetetramine, or the like, with a dicarboxylic acid such as adipic acid, or the like). Commercially available products of the polyamide-epoxy resin include "SUMIREZRESIN (registered trademark) 650" and "SUMIREZRESIN 675" (Sumika Chemtex Co., Ltd.) and "WS-525" (manufactured by Nippon PMC Co., Ltd.). When the epoxy resin is blended, the amount thereof is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass, based on 100 parts by mass of the polyvinyl alcohol resin.

The thickness of the adhesive layer formed of the dry curing adhesive is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 0.5. mu.m. If the adhesive layer formed of the dry curing adhesive is too thick, for example, appearance defects are likely to occur in an elliptically polarizing plate formed of a polarizing plate and the optical film of the present invention.

[ active energy ray-curable adhesive agent ]

The active energy ray-curable adhesive may contain a solvent. The active energy ray-curable adhesive is an adhesive that is cured by irradiation with an active energy ray.

Examples of the active energy ray-curable adhesive include cationically polymerizable adhesives containing an epoxy compound and a cationic polymerization initiator; a radically polymerizable adhesive containing an acrylic curing component and a radical polymerization initiator; an adhesive containing both a cationically polymerizable curing component such as an epoxy compound and a radically polymerizable curing component such as an acrylic compound, and further containing a cationic polymerization initiator and a radical polymerization initiator; and adhesives which are cured by irradiation of electron beams without containing such polymerization initiators.

Among them, a radical polymerizable active energy ray-curable adhesive containing an acrylic curing component and a radical polymerization initiator, and a cation polymerizable active energy ray-curable adhesive containing an epoxy compound and a cation polymerization initiator are preferable. Examples of the acrylic curing component include (meth) acrylic esters such as methyl (meth) acrylate and hydroxyethyl (meth) acrylate, and (meth) acrylic acid. The active energy ray-curable adhesive containing an epoxy compound may further contain a compound other than the epoxy compound. Examples of the compound other than the epoxy compound include an oxetane compound and an acrylic compound.

Examples of the radical polymerization initiator include the above photopolymerization initiators. Examples of commercially available products of the cationic polymerization initiator include "KAYARAD" (registered trademark) series (manufactured by Nippon chemical Co., Ltd.), "CYRACURE UVI" series (manufactured by Dow chemical Co., Ltd.), "CPI" series (manufactured by San-Apro Co., Ltd.), "TAZ", "BBI" and "DTS" (manufactured by Midori Kagaku Co., Ltd., "Ltd.)," ADEKA OPTOMER "series (manufactured by ADEKA Co., Ltd.)," RHODOORSIL "(registered trademark) (manufactured by Rhodia) and the like. The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, with respect to 100 parts by mass of the active energy ray-curable adhesive.

The active energy ray-curable adhesive may further contain an ion scavenger, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, and the like.

In the present specification, the active energy ray is defined as: an energy ray capable of decomposing a compound capable of generating an active species to generate an active species. Examples of such active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, α -rays, β -rays, γ -rays, and electron beams, and ultraviolet rays and electron beams are preferable. The preferable irradiation conditions of ultraviolet rays are the same as those for the polymerization of the polymerizable liquid crystal compound.

[ display device ]

In the present invention, a display device including the optical film of the present invention can be provided as one embodiment. In addition, the display device may include the elliptically polarizing plate according to the above embodiment.

The display device is a device having a display mechanism, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic Electroluminescence (EL) display device, an inorganic Electroluminescence (EL) display device, a touch panel display device, an electron emission display device (a field emission display device (FED, etc.), a surface field emission display device (SED)), electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection display device (a Grating Light Valve (GLV) display device, a display device having a Digital Micromirror Device (DMD), and a piezoelectric ceramic display device.

The liquid crystal display device includes any of a transmission type liquid crystal display device, a semi-transmission type liquid crystal display device, a reflection type liquid crystal display device, a direct-view type liquid crystal display device, a projection type liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images or may be stereoscopic display devices that display three-dimensional images. In particular, as a display device having the optical film and the polarizing plate of the present invention, an organic EL display device and a touch panel display device are preferable.

[ examples ]

The present invention will be described more specifically with reference to examples. In the examples, "%" and "part" are% by mass and part by mass unless otherwise specified. The polymer film, the apparatus and the measurement method used in the following examples are as follows.

ZF-14 manufactured by ZEON Japan was used as a cycloolefin polymer (COP) film.

As the corona treatment device, AGF-B10 manufactured by Chunshi Motor Co., Ltd was used.

The corona treatment was performed 1 time under the conditions of an output of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus.

SPOT CURE SP-9 with a polarizer unit manufactured by USHIO INC was used as a polarized UV light irradiation device.

As a high-pressure mercury lamp, Unicure VB-15201BY-A manufactured BY USHIO INC.

The phase difference value Re (λ) in the in-plane direction was measured using KOBRA-WPR manufactured by prince measuring machine co.

The retardation value Rth (λ) in the thickness direction and the film thickness were measured by using an Ellipsometer (Ellipsometer) M-220 manufactured by Nippon spectral Co.

[ preparation of composition for alignment film to form first retardation layer ]

An alignment film composition for forming a first retardation layer was obtained by mixing 5 parts (weight average molecular weight: 30000) of a photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) as components, and stirring the resulting mixture at 80 ℃ for 1 hour.

[ preparation of composition for alignment film for Forming second phase Difference layer ]

A silane coupling agent KBE-9103 manufactured by shin-Etsu chemical Co., Ltd was dissolved in a solvent prepared by dissolving a silane coupling agent KBE-9103 prepared by 9: 1 (weight ratio) of ethanol and water to obtain an alignment layer composition for forming a second phase difference layer having a solid content of 1%.

[ preparation of compositions for Forming first and second phase Difference layers (compositions I to IV) ]

To a mixture of the polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B described below, 0.1 part of a leveling agent (F-556; manufactured by DIC Co., Ltd.) and 6 parts of a polymerization initiator 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure369(Irg 369); manufactured by BASF Japan) were added.

Further, N-methyl-2-pyrrolidone (NMP) was added as a solvent so that the solid content concentration became 13%, and the mixture was stirred at 80 ℃ for 1 hour to obtain first and second phase difference layer forming compositions. The mixture ratio of the polymerizable liquid crystal compound a and the polymerizable liquid crystal compound B was added as shown in table 1 in accordance with the target wavelength dispersion value α, and the name of each composition was defined as shown in table 1.

[ Table 1]

The ratio of the polymerizable liquid crystal compounds a and B is a ratio to the total amount of the polymerizable liquid crystal compounds.

The polymerizable liquid crystal compound a is produced by the method described in jp 2010-31223 a. The polymerizable liquid crystal compound B is produced by the method described in jp 2009-173893 a. The respective molecular structures are shown below.

Polymerizable liquid Crystal Compound A

Polymerizable liquid crystal compound B

[ preparation of liquid Crystal composition for Forming first and second phase Difference layers (composition V) ]

To a liquid crystal compound LC242 described below: to paliocolor lc242 (registered trademark of BASF corporation), 0.1 part of leveling agent F-556 and 3 parts of polymerization initiator Irg369 were added, and cyclopentanone was added so that the solid content concentration became 13%, to obtain a liquid crystal composition for forming the first and second phase difference layers. The name of the obtained liquid crystal composition was denoted as "composition V".

Liquid crystal compound LC 242: paliocolorlc242(BASF company registered trademark)

(example 1)

[ production of first retardation layer ]

The composition for an alignment film for forming a first retardation layer was applied onto a COP film (ZF-14-50) manufactured by ZEON corporation, Japan, using a bar coater, dried at 80 ℃ for 1 minute, and the cumulative quantity of light at a wavelength of 313nm was 100mJ/cm using a polarized UV light irradiation apparatus (SPOT CURE SP-9; manufactured by USHIO INC.)²Under conditions of (a) polarized UV light exposure is carried out at an axial angle of 45 °. The film thickness of the resulting alignment film for forming the first retardation layer was measured with an ellipsometer, and the result was 100 nm.

Next, the composition I was applied to the alignment film for forming a first retardation layer BY using a bar coater, dried at 120 ℃ for 1 minute, and then irradiated with ultraviolet light (cumulative light amount at a wavelength of 365 nm: 500mJ/cm under a nitrogen atmosphere: 500 mJ/cm) from the side on which the composition for forming a retardation layer was applied BY using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured BY USHIO INC.)²) Thereby, the first retardation layer is formed. The film thickness of the obtained first retardation layer was measured with an ellipsometer, and as a result, it was 2.3 μm.

[ production of second retardation layer ]

The alignment film composition for forming the second phase difference layer was applied to a COP film (ZF-14-50) manufactured by ZEON corporation, japan, using a bar coater, and dried at 120 ℃ for 1 minute to obtain an alignment film for forming the second phase difference layer. The thickness of the second retardation layer-forming alignment film was measured with an ellipsometer, and the result was 200 nm.

Next, the composition I was applied to the alignment film for forming a second retardation layer by using a bar coater, and the coating was carried out at 120 ℃ for 1 minuteThe bell was dried, and then ultraviolet rays were irradiated from the side coated with the phase difference layer composition using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured BY USHIO INC., Ltd.) (cumulative light amount at a wavelength of 365nm under a nitrogen atmosphere: 500mJ/cm²) Thereby, the second phase difference layer is formed. The film thickness of the obtained second phase difference layer was measured with an ellipsometer, and as a result, it was 1.2 μm.

[ Re measurement of first retardation layer and second retardation layer ]

The in-plane retardation values (Re1(λ) and Re2(λ)) of the first retardation layer and the second retardation layer produced by the above method were measured at wavelengths λ of 450nm, 550nm and 650nm by a measuring instrument (KOBRA-WR, manufactured by prince measuring machine) after confirming that no retardation was present in the cycloolefin polymer film as the base material. The results obtained are shown in table 2.

[ Rth measurement of first and second retardation layers ]

In the retardation values (Rth1(λ) and Rth2(λ)) in the thickness direction of the first retardation layer and the second retardation layer manufactured by the above method, after confirming that no retardation exists in the cycloolefin polymer film as the base material, the measurement was performed by changing the incident angle of light incident on the sample by an ellipsometer. Further, the average refractive index at wavelengths λ of 450nm and 550nm was measured using a refractometer (ATAGO co., ltd, "multi-wavelength abbe refractometer DR-M4"). The film thickness, average refractive index, and Rth1(λ) and Rth2(λ) at wavelengths λ of 450nm and 550nm calculated from the measurement results of the ellipsometer are shown in table 2.

[ calculation of Nz (λ) ]

Nz (λ) of the optical film in which the first retardation layer and the second retardation layer are laminated is calculated according to formula (C). The calculated results are shown in table 2.

The refractive indices nx1(λ), ny1(λ), and nz1(λ) of the obtained first retardation layer satisfy nx1(λ) > ny1(λ) ≈ nz1(λ) over the entire wavelength λ of 400 to 700 nm. The refractive indices nx2(λ), ny2(λ), and nz2(λ) of the second phase difference layer satisfy nz2(λ) > nx2(λ) ≈ ny2(λ) over the entire wavelength λ of 400 to 700 nm.

[ production of polarizing plate ]

A polyvinyl alcohol film having an average polymerization degree of about 2,400, a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ℃ and then immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.02/2/100 at 30 ℃ to carry out iodine dyeing (iodine dyeing step). The polyvinyl alcohol film subjected to the iodine dyeing step was immersed in an aqueous solution of potassium iodide/boric acid/water at a weight ratio of 12/5/100 at 56.5 ℃ to carry out a boric acid treatment (boric acid treatment step). The polyvinyl alcohol film after the boric acid treatment step was washed with pure water at 8 ℃ and then dried at 65 ℃ to obtain a polarizing plate (thickness after stretching was 27 μm) in which iodine was adsorbed and oriented in polyvinyl alcohol. In this case, stretching is performed in the iodine dyeing step and the boric acid treatment step. The total draw ratio in the drawing was 5.3 times. The obtained polarizer and a saponified triacetyl cellulose film (KC 4UYTAC manufactured by Konica Minolta, 40 μm) were bonded to each other with a nip roll (nip roll) through a water-based adhesive. The resulting laminate was dried at 60 ℃ for 2 minutes while maintaining the tension of 430N/m, to obtain a polarizing plate having a triacetyl cellulose film as a protective film on one surface. The water-based adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (Kuraray POVAL KL318 manufactured by ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumika Chemtex co., sumrezresin 650 manufactured by ltd., an aqueous solution having a solid content concentration of 30%) to 100 parts of water.

The optical properties of the obtained polarizing plate were measured. The polarizing plate obtained above was measured with a spectrophotometer (V7100, manufactured by hitachi spectrophotometers) with the polarizer surface as the incidence surface. The visibility-modifying monomer transmittance was 42.1%, the visibility-modifying polarization degree was 99.996%, the monomer hue a was-1.1, and the monomer hue b was 3.7.

[ production of elliptically polarizing plate ]

First, the surface of the first retardation layer was subjected to corona treatment, and then the polarizing plate produced by the above method was bonded via an adhesive (pressure-sensitive adhesive manufactured by Lintec Corporation, 5 μm), and then the substrate was peeled off to form a laminate of the polarizing plate and the first retardation layer.

Next, the surface of the second retardation layer was subjected to corona treatment, and then the first retardation layer and the second retardation layer in the laminate of the polarizing plate and the first retardation layer were bonded via an adhesive (pressure-sensitive adhesive manufactured by Lintec Corporation, 5 μm). Then, the substrate was peeled off to obtain an elliptically polarizing plate.

[ confirmation of changes in the front tone and the oblique tone ]

The obtained elliptically polarizing plate was attached to a mirror via an adhesive, and then visually observed from the front at a position 50cm away from the mirror, to confirm the color tone. Further, the oblique color tone was confirmed by visual observation from a position 50cm away from the direction having an elevation angle of 60 ° and an azimuth angle of 0 to 360 °. The results of the confirmation are shown in table 2.

Note that the front tone and the oblique tone are as follows.

Excellent: clear black, o: black, Δ: red or blue black, x: red or blue

(examples 2 to 30, comparative examples 1 to 12)

An optical film and an elliptically polarizing plate were produced in the same manner as in example 1, except that the composition I was changed to the composition II, the composition III, the composition IV, or the composition V, respectively, according to the descriptions in table 2. The measurement results of each are shown in table 2.

The refractive indices nx1(λ), ny1(λ), and nz1(λ) of the first retardation layers obtained in examples 2 to 30 satisfy nx1(λ) > ny1(λ) ≈ nz1(λ) over the entire wavelength λ of 400 to 700 nm. The refractive indices nx2(λ), ny2(λ), and nz2(λ) of the second phase difference layer satisfy nz2(λ) > nx2(λ) ≈ ny2(λ) over the entire wavelength λ of 400 to 700 nm.

(example 31)

An optical film and an elliptically polarizing plate were produced in the same manner as in example 1, except that the composition I was changed as described in table 2, and the order of laminating the first retardation layer and the second retardation layer in the method for producing an elliptically polarizing plate was changed to the order of laminating the polarizing plate and the second retardation layer first and then laminating the laminate of the polarizing plate and the second retardation layer and the first retardation layer. The measurement results are shown in table 2.

The refractive indices nx1(λ), ny1(λ), and nz1(λ) of the first retardation layer obtained in example 31 satisfy nx1(λ) > ny1(λ) ≈ nz1(λ) over the entire wavelength λ of 400 to 700 nm. The refractive indices nx2(λ), ny2(λ), and nz2(λ) of the second phase difference layer satisfy nz2(λ) > nx2(λ) ≈ ny2(λ) over the entire wavelength λ of 400 to 700 nm.

[ Table 2]

The elliptically polarizing plate having the first retardation layer and the second retardation layer described in the examples had black both in the front color tone and in the oblique color tone, and had excellent antireflection properties.

Claims (12)

1. An optical film having a first retardation layer and a second retardation layer and satisfying the relationships of the following formulae (1) and (2),

0.4≤Nz(450)≤0.6 (1)

0.4≤Nz(550)≤0.6 (2)

wherein Nz (450) represents an Nz coefficient of the optical film with respect to light having a wavelength of 450nm, Nz (550) represents an Nz coefficient of the optical film with respect to light having a wavelength of 550nm,

the Nz coefficient Nz (λ) of the optical film for light of a wavelength λ (nm) is represented by the following formula:

Nz(λ)＝(nx(λ)-nz(λ))/(nx(λ)-ny(λ))

nx (λ) represents: in a refractive index ellipsoid formed by an optical film, a main refractive index for light of a wavelength λ (nm) in a direction parallel to a film plane,

ny (λ) represents: in a refractive index ellipsoid formed by the optical film, a refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of the nx (λ),

nz (λ) represents: in a refractive index ellipsoid formed by an optical film, a refractive index for light of a wavelength λ (nm) in a direction perpendicular to a film plane,

the first retardation layer also satisfies the following expression (7),

120nm≤Re1(550)≤170nm (7)

wherein Re1(550) represents an in-plane retardation value of the first retardation layer with respect to light having a wavelength λ of 550nm,

the second phase difference layer also has optical characteristics shown in formula (8),

-100nm≤Rth2(550)≤-50nm (8)

wherein Rth2(550) represents a phase difference value in the thickness direction of the second retardation layer with respect to light having a wavelength λ of 550nm,

the first retardation layer is a liquid crystal cured film obtained by curing a polymerizable liquid crystal compound in a state of being oriented in a direction horizontal to the substrate surface, the second retardation layer is a liquid crystal cured film obtained by curing a polymerizable liquid crystal compound in a state of being oriented in a direction perpendicular to the substrate surface,

the first retardation layer has a relationship of nx1(λ) > ny1(λ) ≈ nz1(λ) in a refractive index ellipsoid formed by the first retardation layer in a range of a wavelength λ of 400 to 700nm,

in the formula, nx1(λ) represents: in the refractive index ellipsoid formed by the first retardation layer, the main refractive index for light of wavelength λ (nm) in the direction parallel to the film plane,

ny1(λ) denotes: in a refractive index ellipsoid formed by the first retardation layer, a refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of nx1(λ),

nz1(λ) denotes: a refractive index for light of a wavelength λ (nm) in a direction perpendicular to the film plane in a refractive index ellipsoid formed by the first retardation layer;

and the first retardation layer satisfies the following expressions (3) and (4),

0.75≤Re1(450)/Re1(550)≤0.92 (3)

1.00≤Re1(650)/Re1(550) (4)

in the formula, Re1(450) represents an in-plane phase difference value of the first retardation layer with respect to light having a wavelength λ of 450nm, Re1(550) represents an in-plane phase difference value of the first retardation layer with respect to light having a wavelength λ of 550nm, Re1(650) represents an in-plane phase difference value of the first retardation layer with respect to light having a wavelength λ of 650nm, respectively,

the in-plane retardation Re1(λ) of the first retardation layer with respect to light having a wavelength λ nm is represented by the following formula:

Re1(λ)＝(nx1(λ)-ny1(λ))×d1

where d1 denotes the thickness of the first retardation layer,

the second phase difference layer has a relationship of nz2(λ) > nx2(λ) ≈ ny2(λ) in a refractive index ellipsoid formed by the second phase difference layer in a range of a wavelength λ of 400 to 700nm,

in the formula, nz2(λ) represents: in the index ellipsoid formed in the second phase difference layer, the refractive index for light of wavelength λ (nm) in the direction perpendicular to the film plane,

nx2(λ) represents: in the index ellipsoid formed in the second phase difference layer, the maximum refractive index for light of wavelength λ (nm) in the direction parallel to the film plane,

ny2(λ) denotes: in a refractive index ellipsoid formed by the second phase difference layer, a refractive index for light of a wavelength λ (nm) in a direction parallel to the film plane and orthogonal to the direction of nx2(λ),

where nx2(λ) ═ ny2(λ), nx2(λ) represents a refractive index in an arbitrary direction parallel to the film plane;

and the second phase difference layer satisfies the following expressions (5) and (6),

0.75≤Rth2(450)/Rth2(550)≤0.92 (5)

1.00≤Rth2(650)/Rth2(550) (6)

in the formula, Rth2(450) represents a phase difference value for light having a wavelength λ of 450nm in the thickness direction, Rth2(550) represents a phase difference value for light having a wavelength λ of 550nm in the thickness direction of the second retardation layer, Rth2(650) represents a phase difference value for light having a wavelength of 650nm in the thickness direction of the second retardation layer, respectively,

a retardation value Rth2(λ) for light of a wavelength λ (nm) in the thickness direction of the second retardation layer is represented by the following formula:

Rth2(λ)＝[(nx2(λ)+ny2(λ))/2-nz2(λ)]×d2

wherein, in a refractive index ellipsoid formed by the second phase difference layer, nz2(λ) represents a main refractive index in a direction perpendicular to the film plane at a wavelength λ (nm) ((nx2(λ) + ny2(λ))/2) represents an average refractive index of the film plane at the wavelength λ (nm), and d2 represents a thickness of the second phase difference layer.

2. The optical film according to claim 1, wherein the second retardation layer is a film formed of a coating layer formed by polymerizing polymerizable liquid crystal in an aligned state.

3. The optical film according to claim 1 or 2, wherein the first retardation layer is a film formed of a coating layer formed by polymerizing polymerizable liquid crystal in an aligned state.

4. The optical film according to claim 1 or 2, wherein the second retardation layer is 5 μm or less.

5. The optical film according to claim 1 or 2, wherein the first retardation layer is 5 μm or less.

6. The optical film according to claim 1 or 2, wherein the first retardation layer and the second retardation layer are coating layers formed by polymerizing mainly the same polymerizable liquid crystal compound.

7. An elliptically polarizing plate with an optical compensation function, which comprises the optical film according to any one of claims 1 to 6 and a polarizing plate.

8. The elliptically polarizing plate with optical compensation function according to claim 7, wherein the absorption axis of the polarizing plate and the slow axis of the first retardation layer have a relationship of 45 ± 5 ° or 135 ± 5 ° within the film surface, and the absorption axis of the polarizing plate and the slow axis of the first retardation layer and the slow axis of the second retardation layer are orthogonal to each other in the direction perpendicular to the film surface.

9. The elliptically polarizing plate with optical compensation function according to claim 7 or 8, which is an optical laminate comprising a polarizing plate, an adhesive layer, a first retardation layer, an adhesive layer, and a second retardation layer formed in this order.

10. The elliptically polarizing plate with optical compensation function according to claim 7 or 8, which is an optical laminate comprising a polarizing plate, an adhesive layer, a second retardation layer, an adhesive layer, and a first retardation layer formed in this order.

11. An organic EL display device comprising the elliptically polarizing plate with optical compensation function according to any of claims 8 to 10.

12. The method for manufacturing an elliptically polarizing plate with optical compensation function according to any of claims 7 to 10, which comprises all the following steps:

(step 1-A) a step of forming a first retardation layer by applying a polymerizable liquid crystal compound onto a substrate having a horizontal alignment film formed thereon and then polymerizing the compound in a horizontally aligned state;

(step 1-B) a step of forming a second phase difference layer by applying a polymerizable liquid crystal compound onto a substrate having a vertical alignment film formed thereon and then polymerizing the compound in a vertically aligned state; and

(step 2) a step of transferring and laminating the liquid crystal polymer of the first retardation layer and the liquid crystal polymer of the second retardation layer from the base material to the polarizing plate via an adhesive.