CN111033331A

CN111033331A - Phase difference plate with optical compensation function for flexible display

Info

Publication number: CN111033331A
Application number: CN201880053707.5A
Authority: CN
Inventors: 葛西辰昌; 幡中伸行
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2017-08-21
Filing date: 2018-08-08
Publication date: 2020-04-17
Anticipated expiration: 2038-08-08
Also published as: CN111033331B; TW201921000A; TWI780207B; JP2019035952A; KR20200036928A; WO2019039287A1

Abstract

The invention provides a method for manufacturing a flexible phase difference plate with an optical compensation function, which does not generate defects such as wrinkles and cracks even if being bent and does not reflect external light in a colored state when being folded. In the manufacturing method of the present invention, a retardation plate with an optical compensation function for use in a flexible display is manufactured by a method of forming a horizontal alignment film through coating, drying, and alignment treatment steps, then forming a horizontal alignment liquid crystal cured film through coating, drying, and ultraviolet irradiation steps, further forming a vertical alignment film through coating and drying steps, forming a vertical alignment liquid crystal cured film through coating, drying, and ultraviolet irradiation steps, and sequentially forming a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film.

Description

Phase difference plate with optical compensation function for flexible display

Technical Field

The present invention relates to a phase difference plate with an optical compensation function for a flexible display.

Background

Flat panel displays such as organic EL image display devices generally have a flat image display surface. The image display surface of the flat panel display maintains a flat state regardless of whether an image is displayed or not.

Such flat panel displays often use a phase difference plate. For example, in an organic EL image display device, a circularly polarizing plate in which a phase difference plate and a polarizing plate are combined is used in order to prevent light reflection from occurring at an electrode constituting the image display device.

Among such retardation plates, a retardation plate exhibiting reverse wavelength dispersibility is preferable in terms of exhibiting equivalent retardation performance over a wide wavelength range of visible light. As a retardation plate exhibiting reverse wavelength dispersibility, a retardation plate formed of a horizontally aligned liquid crystal cured film obtained by polymerizing and curing a polymerizable liquid crystal compound exhibiting reverse wavelength dispersibility in a state of being aligned in the horizontal direction is known.

Further, a retardation plate with an optical compensation function is also required to have a function of compensating for the same optical performance as that of the retardation plate with an optical compensation function when viewed from the front direction, and as such a retardation plate with an optical compensation function, a retardation plate having a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film obtained by polymerizing and curing a polymerizable liquid crystal compound in a vertically aligned state is proposed in patent document 1 [ japanese patent application laid-open No. 2015-163935 ]. The document also discloses the following subject matter: the horizontally oriented liquid crystal cured film and the vertically oriented liquid crystal cured film are laminated only through the orientation film or through the protective layer. This document only discloses that the retardation plate with the optical compensation function described in this document can be used for a flat panel display.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2015-163935

Disclosure of Invention

Problems to be solved by the invention

On the other hand, as a display, a foldable so-called flexible display has also been developed. In a flexible display, the retardation plate with optical compensation will also be folded together with the display.

However, if a defect such as a wrinkle or a crack occurs when the flexible display is folded, the defect portion such as a wrinkle or a crack may be a defect when the flexible display is unfolded again to display an image, and the displayed image may be damaged. When the image is folded while being displayed, since the angle of elevation of the folded portion (the angle formed by the plane of the film and the direction in which the observer views the screen) is substantially very small, the optical performance cannot be sufficiently compensated, and there is also a problem that external light is reflected in a colored state.

Therefore, an object of the present invention is to develop a flexible retardation plate with an optical compensation function that does not cause defects such as wrinkles and cracks even when it is folded and does not reflect external light in a colored state even when it is folded.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention.

That is, the present invention includes the following embodiments.

[ 1] A method for manufacturing a retardation plate with an optical compensation function,

forming a horizontal alignment film through coating, drying and alignment treatment processes,

forming a horizontally aligned liquid crystal cured film through the steps of coating, drying and ultraviolet irradiation,

further forming a vertical alignment film through a coating and drying process,

forming a vertically aligned liquid crystal cured film through the steps of coating, drying and ultraviolet irradiation,

thus, a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film are formed in this order.

[ 2] A method for producing a retardation plate with an optical compensation function according to the above [ 1], wherein a horizontally oriented film, a horizontally oriented liquid crystal cured film, a vertically oriented film, and a vertically oriented liquid crystal cured film are sequentially formed to have a film thickness of 1.0 μm or less.

[ 3 ] the method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 2] above, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film formed from the photo-alignment film are formed in this order.

The method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 3 ] above, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film formed from a photoalignment film containing a cinnamoyl group are formed in this order.

[ 5 ] the method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [4 ] above, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having a film thickness of 1.0 μm or less, and a vertical alignment liquid crystal cured film are formed in this order.

[ 6 ] the method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 5 ] above, wherein the horizontal alignment film, the horizontal alignment liquid crystal cured film, the vertical alignment film containing an Si element, and the vertical alignment liquid crystal cured film are formed in this order.

[ 7 ] the method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 6 ] above, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having an Si/C element of 0.03 to 1.00, and a vertical alignment liquid crystal cured film are formed in this order.

The method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 7 ] above, which comprises forming a horizontally oriented liquid crystal cured film, a vertically oriented film, and a vertically oriented liquid crystal cured film in this order, wherein the horizontally oriented liquid crystal cured film satisfies the following relationship (1).

ReA(450)/ReA(550)＜1.00···(1)

In the formula, ReA (λ) represents an in-plane phase difference value at a wavelength λ nm of the horizontally aligned liquid crystal cured film. The in-plane phase difference value ReA (λ) is defined as follows.

ReA(λ)＝(nxA(λ)-nyA(λ))×dA

Wherein nxA (λ) represents a main refractive index at a wavelength λ (nm) in a film plane of the horizontally aligned liquid crystal cured film, nyA (λ) represents a refractive index at a wavelength λ (nm) in a direction orthogonal to nxA (λ) in the same plane, and dA represents a thickness of the horizontally aligned liquid crystal cured film.

The method for producing a retardation plate with an optical compensation function according to any one of [ 1] to [ 8 ] above, which comprises forming a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film in this order, wherein the vertical alignment liquid crystal cured film satisfies the following relationship (2).

RthC(450)/RthC(550)＜1.00···(2)

In the formula, rth (λ) represents a phase difference value in the thickness direction at a wavelength λ nm of the vertically aligned liquid crystal cured film. The phase difference value RthC (λ) is defined as follows.

RthC(λ)＝((nxC(λ)+nyC(λ))/2-nzC(λ))×dC

Wherein nxC (lambda) represents a main refractive index at a wavelength lambda (nm) in the film plane of the vertically aligned liquid crystal cured film,

nyC (lambda) represents a refractive index at a wavelength lambda (nm) in a direction orthogonal to nxC (lambda) in the same plane,

nzC (λ) represents a refractive index at a wavelength λ (nm) in the thickness direction of the vertically aligned liquid crystal cured film,

dC denotes the thickness of the vertically aligned liquid crystal cured film.

When nxC (λ) is nyC (λ), nxC (λ) may be a refractive index in any direction in the film plane.

The present invention also includes the following embodiments.

[ 10 ] A method for manufacturing a retardation plate with an optical compensation function,

forming a vertical alignment film through a coating and drying process,

further forming a horizontal alignment film by coating, drying and aligning,

thus, a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film are formed in this order.

The method for producing a retardation plate with an optical compensation function according to the above [ 10 ], wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film having a film thickness of 1.0 μm or less, and a horizontal alignment liquid crystal cured film are sequentially formed.

The method for producing a retardation plate with an optical compensation function according to the above [ 10 ] or [ 11 ], wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film formed from a photo-alignment film, and a horizontal alignment liquid crystal cured film are formed in this order.

The method for manufacturing a retardation plate with an optical compensation function according to any one of [ 10 ] to [ 12 ] above, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film formed from a photoalignment film containing a cinnamoyl group, and a horizontal alignment liquid crystal cured film are formed in this order.

The method for producing a retardation plate with an optical compensation function according to any one of [ 10 ] to [ 13 ] above, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film are formed in this order to have a film thickness of 1.0 μm or less.

The method for producing a retardation plate with an optical compensation function according to any one of [ 10 ] to [ 14 ] above, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film containing an Si element are formed in this order.

The method for producing a retardation plate with an optical compensation function according to any one of [ 10 ] to [ 15 ] above, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having an Si/C element of 0.03 to 1.00, and a vertical alignment liquid crystal cured film are formed in this order.

The method for producing a retardation plate with an optical compensation function according to any one of [ 10 ] to [ 16 ] above, wherein the retardation plate with an optical compensation function is produced by sequentially forming a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film, wherein the horizontal alignment liquid crystal cured film satisfies the following relationship (3).

ReA(450)/ReA(550)＜1.00···(3)

ReA(λ)＝(nxA(λ)-nyA(λ))×dA

The method for producing a retardation plate with an optical compensation function according to any one of the above [ 1] to [ 17 ], which comprises forming a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film in this order, wherein the vertical alignment liquid crystal cured film satisfies the following relationship (4).

RthC(450)/RthC(550)＜1.00···(4)

RthC(λ)＝((nxC(λ)+nyC(λ))/2-nzC(λ))×dC

dC denotes the thickness of the vertically aligned liquid crystal cured film.

The retardation plate with an optical compensation function can be obtained by the manufacturing method of the present invention, and the elliptically polarizing plate with an optical compensation function can be manufactured by laminating a polarizing plate on the retardation plate.

The elliptically polarizing plate with an optical compensation function is preferably used by being incorporated into, for example, an organic EL display device.

ADVANTAGEOUS EFFECTS OF INVENTION

The phase difference plate with the optical compensation function can inhibit the defects such as wrinkles and cracks generated during bending.

Detailed Description

[ horizontally aligned liquid Crystal cured film ]

The horizontally aligned liquid crystal cured film is a film having refractive index anisotropy in the film plane, and is formed of a polymer containing a polymerizable liquid crystal compound. From the viewpoint of enabling the design of the film thickness and the wavelength dispersion characteristics of the horizontally aligned liquid crystal cured film as desired, it is preferable to form the horizontally aligned liquid crystal cured film by applying a polymerizable liquid crystal composition onto the horizontally aligned film and polymerizing the composition containing the polymerizable liquid crystal compound in an aligned state by heating and/or light irradiation.

The three-dimensional refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film may have biaxiality, but preferably has monoaxiality. The horizontally aligned liquid crystal cured film may be a horizontally aligned liquid crystal cured film formed of a polymer of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound in a state of being aligned in a horizontal direction with respect to the plane of the horizontally aligned liquid crystal cured film; it may be a hybrid alignment liquid crystal cured film or an obliquely alignment liquid crystal cured film. The refractive indices nx, ny, and nz in 3 directions of a refractive index ellipsoid formed by the orientation of the polymerizable liquid crystal may have a relationship of nx > ny ≈ nz (referred to as a positive a plate), or nx < ny ≈ nz (referred to as a negative a plate). nx represents a main refractive index in a direction parallel to the plane of the horizontally aligned liquid crystal cured film in a refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film. ny represents a refractive index in a direction parallel to the plane of the horizontally aligned liquid crystal cured film and orthogonal to the nx direction in a refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film. nz represents a refractive index in a direction perpendicular to the plane of the horizontally aligned liquid crystal cured film in a refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film.

The horizontally aligned liquid crystal cured film may use either a rod-like polymerizable liquid crystal or a discotic polymerizable liquid crystal, but a rod-like polymerizable liquid crystal is preferable. When the rod-like polymerizable liquid crystal is formed into a horizontally aligned liquid crystal cured film, the horizontally aligned liquid crystal cured film becomes a positive a plate.

When the horizontally aligned liquid crystal cured film has optical anisotropy in the plane of the film, Re1(550), which is the in-plane retardation value with respect to light having a wavelength of 550nm, preferably satisfies the optical properties represented by the following formula (21). Further, the horizontally aligned liquid crystal cured film preferably satisfies the optical properties shown in expressions (22) and (23) as well as the in-plane retardation value against light having a wavelength of 450nm, i.e., Re1(450), the in-plane retardation value against light having a wavelength of 550nm, i.e., Re1(550), and the in-plane retardation value against light having a wavelength of 650nm, i.e., Re1 (650). The horizontally aligned liquid crystal cured film more preferably satisfies optical properties represented by the following formula (21), the following formula (22), and the following formula (23).

120nm≤ReA(550)≤170nm...(21)

[ in the formula, ReA (550) represents an in-plane retardation value (in-plane retardation) of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 550 nm. ]

ReA(450)/ReA(550)≤1.0...(22)

1.00≤ReA(650)/ReA(550)...(23)

[ in the formula, ReA (450) represents an in-plane phase difference value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 450nm, ReA (550) represents an in-plane phase difference value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 550nm, and ReA (650) represents an in-plane phase difference value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 650nm, respectively. ]

When the in-plane retardation value ReA (550) of the horizontally aligned liquid crystal cured film exceeds the range of formula (21), the following problems occur: the display front surface using the elliptically polarizing plate with an optical compensation function (which includes the retardation plate with an optical compensation function) turns red or blue in color. A further preferable range of the in-plane retardation value is 130 nm. ltoreq. ReA (550). ltoreq.160 nm. When "ReA (450)/ReA (550)" of the horizontally aligned liquid crystal cured film exceeds 1.0, the ellipticity of the elliptically polarizing plate having the horizontally aligned liquid crystal cured film on the short wavelength side is deteriorated. If the ellipticity of the elliptically polarizing plate on the short wavelength side becomes poor and less than 1.0, the following tendency is present: when viewed from the front, the function as an elliptical polarizing plate is impaired at the short wavelength side. The "ReA (450)/ReA (550)" is preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and further preferably 0.79 to 0.85.

The in-plane retardation value of the horizontally aligned liquid crystal cured film can be adjusted by the thickness of the horizontally aligned liquid crystal cured film. Since the in-plane retardation value is determined by the following formula (24), the three-dimensional refractive index and the film thickness dA may be adjusted to obtain a desired in-plane retardation value (ReA (. lamda.): the in-plane retardation value of the horizontally aligned liquid crystal cured film at the wavelength (. lamda.)). The three-dimensional refractive index depends on the molecular structure and alignment state of the polymerizable liquid crystal compound described later.

ReA(λ)＝(nxA(λ)-nyA(λ))×dA (24)

[ in the formula, the refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film has a relationship of nxA (λ) > nyA (λ) ≈ nzA (λ), and nxA (λ) represents a main refractive index with respect to light having a wavelength λ (nm) in a direction parallel to the plane of the horizontally aligned liquid crystal cured film. nyA (λ) represents a refractive index of light having a relative wavelength λ (nm) in a direction parallel to the plane of the horizontally aligned liquid crystal cured film and orthogonal to the direction of nxA (λ) in a refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film. dA represents the thickness of the horizontally aligned liquid crystal cured film. ]

The horizontally aligned liquid crystal cured film is preferably a polymer of a composition containing the polymerizable liquid crystal compound in an aligned state as described above. The polymerizable liquid crystal compound forming the horizontally aligned liquid crystal cured film 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, an acid, or the like generated from a photopolymerization initiator. 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 epoxyethyl group, and an oxetanyl group. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, epoxyethyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase-sequence structure may be a nematic liquid crystal or a smectic liquid crystal.

In the present invention, the polymerizable liquid crystal compound is preferably a compound represented by the following formula (I) from the viewpoint of exhibiting reverse wavelength dispersibility and satisfying the relationships of the above formulae (21) and (22) or the below-described formulae (31) and (32),

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 cyclic structure, and the number of pi electrons of the cyclic structure is [4n +2] according to the houcker rule. Here, n represents an integer. When a ring structure is formed by including a heteroatom such as-N ═ S-or the like, the case where the non-covalent bond electron pair included in the heteroatom satisfies the huckel rule and has aromaticity is included. In the divalent aromatic group, preferably contains at least 1 or more of nitrogen atom, oxygen atom, sulfur atom.

G¹And G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group.

Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with 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, a cyano group, or a nitro group, and 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, in the case of 2. ltoreq. k + l, B¹And B²、G¹And G²Each may be the same or different from each other.

E¹And E²Each independently represents an alkanediyl (alkanediyl) group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted by a halogen atom, and a-CH group contained in the alkanediyl group₂-may be replaced by-O-, -S-, -Si-. P¹And P²Independently of each other, represents a polymerizable group or a hydrogen atom, and at least 1 is a polymerizable group.

G¹And G²Each independently preferably being a 1, 4-phenylene group (phenylene group) which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1, 4-phenylene group which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms1, 4-cyclohexanediyl substituted by at least 1 substituent of the group (a), more preferably 1, 4-phenylene substituted by methyl, unsubstituted 1, 4-phenylene, or unsubstituted 1, 4-trans-cyclohexanediyl, and particularly preferably unsubstituted 1, 4-phenylene or unsubstituted 1, 4-trans-cyclohexanediyl. In addition, it is preferable that a plurality of G's exist¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group, and further, it is more preferable to use 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 is¹And 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 is 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, preferably k + l ≦ 4, more preferably k ≦ 2 and l ≦ 2. When k is 2 and l is 2, a symmetrical structure is obtained, and therefore, it is more preferable.

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 epoxyethyl group, and an oxetanyl group. Among these, acryloyloxy, methacryloyloxy, vinyloxy, epoxyethyl and oxetanyl groups are preferable, and acryloyloxy group 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 a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a 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 these, 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, further 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.

In the formulae (Ar-1) to (Ar-22), symbol represents a connecting part, Z⁰、Z¹And Z²Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an 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 Y³Of (5)Examples of the hydrocarbon group include 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, with a phenyl group and a naphthyl group being preferred, and a phenyl group being more preferred. 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.

Y¹And Y²Each 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 represents 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, particularly preferred are-S-, -O-, -NH-.

Among the formulae (Ar-1) to (Ar-22), the formulae (Ar-6) and (Ar-7) are preferred 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 group 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, Y¹Can be bonded withNitrogen atom and Z⁰Together form 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 compound represented by the formula (I) can be produced, for example, by the method described in jp 2010-31223 a.

The polymerizable liquid crystal compounds may be used alone or in combination of two or more. When two or more compounds are used in combination, the content of the compound represented by the above formula (I) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and still more preferably 80 parts by mass or more, based on 100 parts by mass of the polymerizable liquid crystal compound.

The composition for forming a horizontally aligned liquid crystal cured film (hereinafter also referred to as a polymerizable liquid crystal composition) used for forming a horizontally aligned liquid crystal cured film may further contain a solvent, a photopolymerization initiator, a polymerization inhibitor, a photosensitizer, a leveling agent, and an adhesion improving agent. These additives may be used alone or in combination of two or more.

The content of the polymerizable liquid crystal compound is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, and more preferably 90 to 98 parts by mass, based on 100 parts by mass of the solid content of the polymerizable liquid crystal composition. When the content is within the above range, the alignment property of the horizontally aligned liquid crystal cured film tends to be improved. Here, the solid content means the total amount of the components after the solvent is removed from the composition.

The solvent is preferably a solvent capable of dissolving the polymerizable liquid crystal compound, and is preferably a solvent inactive to the polymerization reaction of the polymerizable liquid crystal compound. Examples of the solvent include water, alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, 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; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran, anisole and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP) and 1, 3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more. However, the compound represented by the formula (I) generally has a large conjugated system and thus has low solubility in a solvent, and among the above-exemplified solvents, an alcohol solvent, an ester solvent, a ketone solvent, a chlorine-containing solvent, an ether-based solvent, an amide-based solvent, and an aromatic hydrocarbon solvent are preferably used, and an ester solvent, a ketone solvent, a chlorine-containing solvent, an ether-based solvent, and an amide-based solvent are more preferably used.

The content of the solvent is preferably 50 to 98 parts by mass, and more preferably 70 to 95 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal composition. Therefore, the solid content is preferably 2 to 50 parts by mass per 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 horizontally aligned liquid crystal cured film becomes substantially uniform, and unevenness tends to be less likely to occur in the horizontally aligned liquid crystal cured film. The solid content may be appropriately determined in consideration of the thickness of the horizontally aligned liquid crystal cured film to be produced.

The polymerization initiator is a compound which generates a reactive substance by the participation of heat or light and can initiate a polymerization reaction of a polymerizable liquid crystal or the like. Examples of the reactive substance include active substances such as radicals, cations, and anions. Among them, a photopolymerization initiator which reacts by light irradiation is preferable from the viewpoint of easiness of control of the reaction.

Examples of the photo radical polymerization initiator include benzoin compounds, benzophenone compounds, benzil ketal compounds, α -hydroxyketone compounds, α -aminoketone compounds, triazine compounds, and examples of the photo cation polymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and iron-arene complexes.

Specifically, Irgacure (registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure2959, Irgacure 754, Irgacure 379EG (available from BASF Japan K.K.), SEIKOL BZ, SEIKOL Z, SEIKOL BEE (available from Seiko Chemical Co., Ltd.), Kayakure BP100 (available from Nippon Chemical Co., Ltd.), Kayakure I-6992 (available from DOW Co., Ltd.), ADEKA Optomer SP-152, ADEKA Optomer SP-170, ADEKA Optomen-1717, ADEKA Optomer N-1919, ADEKA ARKLS NCI-831, ADEKA ARKLSNCI-930 (available from Ugacure) and SAVEK.K. (available from Hexak Chemical Co., Ltd.), and the like drugs registered in the series of Hegacure 104, and the like, CPI series (SAN-APRO Co., Ltd.), TAZ, BBI, DTS (Midori chemical Co., Ltd.), RHODORSIL (registered trademark) (Rhodia) and the like. The photopolymerization initiator may be used alone or in combination of two or more. Among these, from the viewpoint of easy control of the reaction, a photo radical polymerization initiator which generates radicals by light irradiation is preferable.

The photopolymerization initiator preferably has a maximum absorption wavelength in the range of 300nm to 400nm, more preferably in the range of 300nm to 380nm, from the viewpoint of making it possible to sufficiently utilize energy emitted from a light source and to achieve excellent productivity, and α -acetophenone-based polymerization initiator and oxime-based photopolymerization initiator are preferable from the same viewpoint.

α -acetophenone polymerization initiator includes, for example, 2-methyl-2-morpholino-1- (4-methylthiophenyl) -1-propanone, 2-dimethylamino-1- (4-morpholinophenyl) -2-benzyl-1-butanone, 2-dimethylamino-1- (4-morpholinophenyl) -2- (4-methylphenylmethyl) -1-butanone, etc., more preferably 2-methyl-2-morpholino-1- (4-methylthiophenyl) -1-propanone, 2-dimethylamino-1- (4-morpholinophenyl) -2-benzyl-1-butanone, and α -acetophenone compounds are commercially available as Irgacure 369, 379EG, 907 (the same is available from BASF Japan, Inc.) and SEUIKOL BEE (available from Seiko chemical Co., Ltd.).

The oxime-based photopolymerization initiator generates radicals by irradiation with light. The radical enables the polymerizable liquid crystal compound to be favorably polymerized in the deep portion of the horizontally aligned liquid crystal cured film. In addition, from the viewpoint of more efficiently performing the polymerization reaction in the deep portion of the horizontally aligned liquid crystal cured film, 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 utilizing ultraviolet rays having a wavelength of 350nm or more, a triazine compound and an oxime ester type carbazole compound are preferable, and an oxime ester type carbazole compound is more preferable from the viewpoint of sensitivity. Examples of the oxime ester type carbazole compound include 1, 2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime) ], O-acetyl-1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -1- (ethanone oxime), and the like. Commercially available products of oxime ester type carbazole compounds include Irgacure OXE-01, Irgacure OXE-02, Irgacure OXE-03 (manufactured by BASF Japan K.K., supra), ADEKA Optomer N-1919, and ADEKA ARKLS NCI-831 (manufactured by ADEKA K.K., supra).

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, per 100 parts by mass of the polymerizable liquid crystal compound. When the amount 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 adding a polymerization inhibitor, and examples of the polymerization inhibitor include hydroquinone and hydroquinone having a substituent such as an alkyl ether, catechol having a substituent such as an alkyl ether such as butylcatechol, radical scavengers such as pyrogallol, 2, 6, 6-tetramethyl-1-piperidinyloxy radical, thiophenols, β -naphthylamine and β -naphthols, and 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 per 100 parts by mass of the polymerizable liquid crystal compound, and two or more of the polymerization inhibitors can be used alone or in combination.

Further, the use of a photosensitizer can increase the sensitivity of the photopolymerization initiator. Examples of the photosensitizer include xanthones such as xanthone and thioxanthone; anthracene and anthracene having a substituent such as alkyl ether; phenothiazine; rubrene. The photosensitizers may be used alone or in combination of two or more. 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, per 100 parts by mass of the polymerizable liquid crystal compound.

The leveling agent is an additive having a function of adjusting the fluidity of the polymerizable liquid crystal composition to make a layer obtained by applying the composition more flat, 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 manufactured by Tolydo corning Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001, KBM-1003, KBM-303, KBM-402, KBE-403, KBM-1403, KBM-502, KBM-503, KBE-502, KBE-503, KBM-5103, KBM-602, KBM-603, KBM-903, KBE-9103, KBM-573, KBM-585, KBM-575, KBM-802, TSTSKBM-430803, TSTSBE 4420, TSF 44410, TSBE 44F 4420, TSBE-4445, TSF 44410, TSF 4420, TSBE-44F 4452, TSF 44410, TSF 4420, TSBE-4452, KBM-44410, KBE-4452, KBM-4420, KBE-102, KBM-102, TSF 4420, TSBE, TSF4460 (all manufactured by Mitsubishi Material contract Co., Ltd.), Fluorinert (registered trademark) FC-72, Fluorinert FC-40, Fluorinert FC-43, Fluorinert FC-3283 (all manufactured by Sumitomo 3M Co., Ltd.), MEGAFAC (registered trademark) R-08, MEGAFAC R-30, MEGAFAC R-90, MEGAFAC F-410, MEGAFAC F-411, MEGAFAC F-443, MEGAFAC F-445, MEGAFACF-470, MEGAFAC F-477, MEGAFAC F-479, MEGAFAC F-482, MEGAFAC F-483 (all manufactured by Mitsubishi Co., Ltd.), TOP EF301, EFTOP 303, EFTOP EF351, TOP EFEF 352 (all manufactured by Mitsubishi Material electronics florization Co., Ltd.), registration SENZ-393, registered trademark S-383, registered trademark 3M, MEGAFAC FAC F-443, MEGAFAC FAC F-445, MEGAFAC F-470, MEGAFAC F-477, MEGAFAC F-479, MEGAFAC F-482, MEGAC F-352 (all manufactured by Mitsubishi Katsubishi electronic florization (, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all of which are manufactured by AGC, QINGMEI chemical Co., Ltd.), trade name E1830, trade name E5844 (manufactured by Dajin Seiki Kagaku K.K.), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all of which are manufactured by BM Chemie). The leveling agent may be used alone or in combination of two or more.

The content of the leveling agent is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the obtained horizontally aligned liquid crystal cured film tends to be smoother, and therefore, the content is preferable.

The polymerizable liquid crystal composition can be obtained by stirring a polymerizable liquid crystal compound and components other than the polymerizable liquid crystal compound such as an additive at a predetermined temperature.

The horizontally aligned liquid crystal cured film can be obtained by: the polymerizable liquid crystal composition containing the polymerizable liquid crystal compound in an aligned state is cured by heating and/or active energy rays after the solvent is removed by applying the polymerizable liquid crystal composition onto a horizontal alignment film described later.

Examples of a method for applying the polymerizable liquid crystal composition to the horizontal alignment film (hereinafter, may be referred to as "application method a") 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, there may be mentioned a method of coating using a coater such as a dip coater, a bar coater or a spin coater. Among them, when the coating is continuously performed in a Roll-to-Roll (Roll to Roll) manner, a coating method by a microgravure method, an ink jet method, a slit coating method, or a die coating method is preferable.

Examples of the method for removing the solvent (hereinafter, may be referred to as solvent removal method a) include natural drying, air drying, heat drying, drying under reduced pressure, and a combination thereof. 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 active energy ray to be irradiated may be appropriately selected depending on the type of the polymerizable liquid crystal compound (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 included), and the amounts thereof.

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, and a metal halide lamp.

The ultraviolet irradiation intensity is usually 10-3,000 mW/cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photo cation polymerization initiator or the photo radical polymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and still more preferably 0.1 second to 1 minute.

When the ultraviolet irradiation intensity is applied for 1 or more times, the cumulative light amount is 10 to 3,000mJ/cm²Preferably 50 to 2,000mJ/cm²More preferably 100 to 1,000mJ/cm². When the cumulative light amount is less than the lower limit, curing of the polymerizable liquid crystal compound may be insufficient, and good transferability may not be obtained. Conversely, when the cumulative light amount is not less than the upper limit, the liquid crystal cured film may contain an optical compensation film having a horizontal alignmentThe retardation plate is colored.

From the viewpoint of making the functional film thin, the thickness of the horizontally oriented liquid crystal cured film is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 2.5 μm or less. The lower limit of the film thickness of the horizontally oriented liquid crystal cured film is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably 1.0 μm or more. The thickness of the horizontally aligned liquid crystal cured film can be measured using an ellipsometer or a contact film thickness meter.

[ horizontal alignment film ]

The alignment film is a film having an alignment controlling force for aligning the polymerizable liquid crystal compound of the liquid crystal cured film in a predetermined direction. Examples of the alignment treatment necessary for developing the alignment control force include rubbing treatment, photo-alignment treatment, and light irradiation treatment. Various orientations such as vertical orientation, horizontal orientation, hybrid orientation, and oblique orientation can be controlled by the type of alignment film, rubbing conditions, and light irradiation conditions. Wherein the horizontal alignment film is an alignment film having an alignment controlling force for aligning the polymerizable liquid crystal compound of the liquid crystal cured film in a horizontal direction. Therefore, by using the horizontally aligned film, a horizontally aligned liquid crystal film can be formed.

The alignment film preferably has solvent resistance that does not dissolve due to application of the polymerizable liquid crystal composition or the like, and heat resistance to heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound.

Examples of the horizontal alignment film exhibiting an alignment controlling force for aligning the horizontal alignment liquid crystal cured film in the horizontal direction include a rubbing alignment film, a photo alignment film, and a groove alignment film having a concave-convex pattern and a plurality of grooves on the surface thereof. When the present invention is applied to a long roll film, for example, the optical alignment film is preferable in that the alignment direction can be easily controlled.

In general, a rubbing alignment film is formed by applying a composition containing an alignment polymer and a solvent (hereinafter, also referred to as a composition for forming a rubbing alignment film) to a substrate or the like, removing the solvent to form a coating film, and rubbing the coating film to impart an alignment controlling force.

Examples of the orientation polymer include polyamide having an amide bond, gelatin, polyimide having an imide bond, and a hydrolysate thereof, i.e., polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazol, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylate. These alignment polymers may be used alone or in combination of two or more.

The concentration of the alignment polymer in the composition for forming a rubbing alignment film may be in a range where the alignment polymer is completely dissolved in the solvent. The content of the oriented polymer is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the composition.

The composition for forming a rubbing alignment film is commercially available. Examples of commercially available products include suniver (registered trademark, manufactured by nippon chemical industry, japan), OPTMER (registered trademark, manufactured by JSR).

The solvent may be, for example, a solvent exemplified in the item of the horizontally aligned liquid crystal cured film. The method of applying the composition for forming a rubbing alignment film to a substrate or the like includes the above-described application method a, and the method of removing a solvent includes the above-described solvent removal method a.

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

The photoalignment film may be generally obtained by: a composition containing a polymer or monomer having a photoreactive group and a solvent (also referred to as a composition for forming a photo alignment film) is applied to a substrate or the like, and after removing the solvent, polarized light (preferably polarized UV light) is irradiated. The direction of the 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 generates an alignment ability by light irradiation. Specifically, there may be mentioned groups which participate in photoreaction originating from the orientation ability, such as orientation-inducing reaction, isomerization reaction, photodimerization reaction, photocrosslinking reaction, or photolysis reaction of molecules by light irradiation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferable, and a group having 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) is particularly preferable.

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, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

From the viewpoint of excellent orientation, a group participating in a photodimerization reaction or a photocrosslinking reaction is preferable. 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, easy obtainment of a photo alignment film having excellent 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 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 parts by mass or more, and more preferably in the range of 0.3 to 10 parts by mass, based on 100 parts by mass of the composition for forming a photo alignment film.

The solvent may be, for example, a solvent exemplified in the item of the horizontally aligned liquid crystal cured film. The method of applying the composition for forming a photo-alignment film to a substrate or the like includes the above-described application method a, and the method of removing a solvent includes the above-described solvent removal method a.

For example, the polarized light may be irradiated directly to a product obtained by removing a solvent from a composition for forming a photo-alignment film applied to a substrate or the like. Preferably, the polarized light is substantially parallel light. The wavelength of the irradiated polarized light is preferably a wavelength of a wavelength region in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet) light having a wavelength of 250 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 passing light 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 rubbing or polarized light irradiation is performed, a plurality of regions (patterns) having different liquid crystal alignment directions can 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.

Examples of a method for obtaining a groove alignment film include: a method of forming a concave-convex pattern by exposing the surface of a photosensitive polyimide film through an exposure mask having a slit with 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 formed resin layer to a base material or the like, and then curing the resin layer; and a method of pressing a roll-shaped original plate having a plurality of grooves against a film of a UV-curable resin before curing, which is formed on a base material or the like, to form irregularities, and then curing; and so on.

The composition for forming a horizontally oriented film, such as the composition for forming a rubbed alignment film and the composition for forming a photo-alignment film, may further contain an additive, etc. exemplified in the section of the horizontally oriented liquid crystal cured film, in addition to the solvent.

From the viewpoint of making the retardation plate with an optical compensation function thinner, the film thickness of the horizontal alignment film is preferably 1 μm or less, more preferably 0.5 μm or less, and still more preferably 0.3 μm or less. The thickness of the horizontal alignment film is preferably 1nm or more, more preferably 5nm or more, still more preferably 10nm or more, and particularly preferably 30nm or more. The film thickness of the horizontal alignment film can be measured using an ellipsometer or a contact film thickness meter.

[ Vertically aligned liquid Crystal cured film ]

The horizontally aligned liquid crystal cured film is a film having refractive index anisotropy in a direction perpendicular to a film plane, and is formed of a polymer containing a polymerizable liquid crystal compound. From the viewpoint of enabling the design of the film thickness and the wavelength dispersion characteristic of the vertical alignment liquid crystal cured film as desired, it is preferable to form the vertical alignment liquid crystal cured film by applying a polymerizable liquid crystal composition onto the vertical alignment film and polymerizing the polymerizable liquid crystal composition containing the polymerizable liquid crystal compound in an aligned state by heating and/or light irradiation.

The three-dimensional refractive index ellipsoid formed by the homeotropically aligned liquid crystal cured film may have biaxiality, but preferably has uniaxiality. The vertically aligned liquid crystal cured film may be a vertically aligned liquid crystal cured film formed of a polymer of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound in a state of being aligned in a vertical direction with respect to the plane of the liquid crystal cured film; it may be a hybrid alignment liquid crystal cured film or an obliquely alignment liquid crystal cured film. The refractive indices nx, ny, and nz in the 3 directions of the refractive index ellipsoid formed by the orientation of the polymerizable liquid crystal may have a relationship of nz > nx ≈ ny (referred to as a positive C plate) or nz < nx ≈ ny (referred to as a negative C plate). nx represents a main refractive index in a direction parallel to the plane of the vertically aligned liquid crystal cured film in a refractive index ellipsoid formed by the vertically aligned liquid crystal cured film. ny represents a refractive index in a direction parallel to the plane of the vertically aligned liquid crystal cured film and orthogonal to the nx direction in a refractive index ellipsoid formed by the vertically aligned liquid crystal cured film. When nx is ny, nx may be oriented in any direction in the plane of the homeotropically aligned liquid crystal cured film. nz represents a refractive index in a direction perpendicular to the plane of the homeotropically aligned liquid crystal cured film in a refractive index ellipsoid formed by the homeotropically aligned liquid crystal cured film.

The vertical alignment liquid crystal cured film may use either a rod-like polymerizable liquid crystal or a discotic polymerizable liquid crystal, but a rod-like polymerizable liquid crystal is preferable. When the rod-like polymerizable liquid crystal is formed into a vertically aligned liquid crystal cured film, the vertically aligned liquid crystal cured film becomes a positive C-plate.

When the vertically aligned liquid crystal cured film is a positive C plate, the vertically aligned liquid crystal cured film preferably satisfies the optical characteristics expressed by the following formula (31) with respect to rth (λ), which is a phase difference value in the thickness direction of light having a wavelength of λ nm. Further, it is also preferable that the optical properties shown by the following formulas (32) and (33) are satisfied. The vertically aligned liquid crystal cured film more preferably satisfies the optical properties represented by the following formula (31), the following formula (32), and the following formula (33).

-100nm≤RthC(550)≤-50nm...(31)

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

RthC(450)/RthC(550)≤1.0...(32)

1.00≤RthC(650)/RthC(550)...(33)

(wherein RthC (450) represents a phase difference value in a thickness direction with respect to light having a wavelength of 450nm, RthC (550) represents a phase difference value in a thickness direction with respect to light having a wavelength of 550nm, and RthC (650) represents a phase difference value in a thickness direction with respect to light having a wavelength of 650nm, respectively.)

When the retardation value RthC (550) in the thickness direction of the vertically aligned liquid crystal cured film exceeds the range of formula (31), the following problems occur: the oblique color of a display using an elliptically polarizing plate with an optical compensation function (including a retardation plate with an optical compensation function) turns red or blue. As a more preferable range of the retardation value in the thickness direction, -95 nm. ltoreq. RthC (550). ltoreq.55 nm, as a further preferable range, -90 nm. ltoreq. RthC (550). ltoreq.60 nm. When "RthC (450)/RthC (550)" of the vertically aligned liquid crystal cured film exceeds 1.0, the ellipticity of the elliptically polarizing plate having the vertically aligned liquid crystal cured film when viewed from an oblique direction on the short wavelength side is deteriorated. If the ellipticity of the elliptically polarizing plate on the short wavelength side becomes poor and less than 1.0, the following tendency is present: the function as an elliptical polarizing plate is impaired at the short wavelength side. The "RthC (450)/RthC (550)" is preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and further preferably 0.79 to 0.85.

The phase difference value in the thickness direction of the vertically aligned liquid crystal cured film can be adjusted by the thickness of the vertically aligned liquid crystal cured film. Since the retardation value in the thickness direction is determined by the following formula (34), the three-dimensional refractive index and the film thickness dC may be adjusted to obtain a desired retardation value in the thickness direction (RthC (λ): the retardation value in the thickness direction of the vertically aligned liquid crystal cured film at the wavelength λ (nm)). The three-dimensional refractive index depends on the molecular structure and alignment properties of the polymerizable liquid crystal compound described later.

RthC(λ)＝[(nxC(λ)+nyC(λ))/2-nzC(λ)]×dC (34)

(wherein in a refractive index ellipsoid formed by the vertically aligned liquid crystal cured film, there is a relationship of nzC (λ) > nxC (λ) ≈ nyC (λ), and in the formula, nzC (λ) represents a refractive index with respect to light of a wavelength λ (nm) in a direction perpendicular to a plane of the vertically aligned liquid crystal cured film in the refractive index ellipsoid formed by the vertically aligned liquid crystal cured film. nxC (λ) represents a maximum refractive index with respect to light of a wavelength λ (nm) in a direction parallel to the plane of the vertically aligned liquid crystal cured film in the refractive index ellipsoid formed by the vertically aligned liquid crystal cured film. nyC (λ) represents a refractive index with respect to light of a wavelength λ (nm) in a direction parallel to the plane of the vertically aligned liquid crystal cured film and orthogonal to the direction of the above nxC. nxC (λ) ═ nyC (λ), nxC (λ) represents a refractive index in any direction parallel to the plane of the vertically aligned liquid crystal cured film. Here, dC represents the thickness of the vertically aligned liquid crystal cured film. )

The vertically aligned liquid crystal cured film is preferably a polymer of a polymerizable liquid crystal composition containing the polymerizable liquid crystal compound in a vertically aligned state as described above. The polymerizable liquid crystal compound forming the vertically aligned liquid crystal cured film 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, an acid, or the like generated from a photopolymerization initiator. 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 epoxyethyl group, and an oxetanyl group. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, epoxyethyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase-sequence structure may be a nematic liquid crystal or a smectic liquid crystal.

The polymerizable liquid crystal compound used for forming the homeotropically aligned liquid crystal cured film is preferably a compound represented by the above formula (I). By using the compound represented by the formula (I), the inverse wavelength dispersibility can be exhibited, and the relationship of the above (31) and (32) can be satisfied.

The polymerizable liquid crystal compounds used for the vertically aligned liquid crystal cured film may be used alone or in combination of two or more. When two or more kinds are used in combination, the content of the compound represented by the above formula (I) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and further preferably 80 parts by mass or more, based on 100 parts by mass of the polymerizable liquid crystal compound.

The composition for forming a vertically aligned liquid crystal cured film (hereinafter also referred to as a polymerizable liquid crystal composition) used for the vertically aligned liquid crystal cured film may further contain a solvent, a photopolymerization initiator, a polymerization inhibitor, a photosensitizer, a leveling agent, and an adhesion improving agent. These additives may be used alone or in combination of two or more.

The content of the polymerizable liquid crystal compound is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, and more preferably 90 to 98 parts by mass, based on 100 parts by mass of the solid content of the polymerizable liquid crystal composition. When the content is within the above range, the alignment property of the vertically aligned liquid crystal cured film tends to be improved. Here, the solid content means the total amount of the components after the solvent is removed from the composition.

The solvent is preferably a solvent capable of dissolving the polymerizable liquid crystal compound, and is preferably a solvent inactive to the polymerization reaction of the polymerizable liquid crystal compound. As the solvent, the same solvent as that used in the composition for forming a horizontally aligned liquid crystal cured film can be used.

The content of the solvent is preferably 50 to 98 parts by mass, and more preferably 70 to 95 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal composition. Therefore, the solid content is preferably 2 to 50 parts by mass per 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 vertically aligned liquid crystal cured film becomes substantially uniform, and unevenness tends not to be easily generated in the vertically aligned liquid crystal cured film. The solid content may be appropriately determined in consideration of the thickness of the cured film of the vertically aligned liquid crystal to be produced.

The polymerization initiator is a compound which generates a reactive substance by the participation of heat or light and can initiate a polymerization reaction of a polymerizable liquid crystal or the like. Examples of the reactive substance include active substances such as radicals, cations, and anions. Among them, a photopolymerization initiator which reacts by light irradiation is preferable from the viewpoint of easiness of control of the reaction. The photopolymerization initiator used may be the same as the photopolymerization initiator used in the composition for forming a horizontally aligned liquid crystal cured film.

The polymerization reaction of the polymerizable liquid crystal compound can be controlled by adding the polymerization inhibitor. As the polymerization inhibitor, the same polymerization inhibitor as used for the composition for forming a horizontally aligned liquid crystal cured film can be used. In order to polymerize the polymerizable liquid crystal compound without disturbing the orientation of the polymerizable liquid crystal compound, 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, relative to 100 parts by mass of the polymerizable liquid crystal compound. The polymerization inhibitor may be used alone or in combination of two or more.

Further, the use of a photosensitizer can increase the sensitivity of the photopolymerization initiator. As the photosensitizer, the same one as used in the composition for forming a horizontally aligned liquid crystal cured film can be used. 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, per 100 parts by mass of the polymerizable liquid crystal compound.

The leveling agent is an additive having a function of adjusting the fluidity of the polymerizable liquid crystal composition to make a layer obtained by applying the composition more flat, and the same leveling agent as that used for the composition for forming a horizontally aligned liquid crystal cured film can be used.

The content of the leveling agent is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the obtained cured film of the vertically aligned liquid crystal tends to be smoother, and therefore, the content is preferable.

The polymerizable liquid crystal composition used for forming the vertically aligned liquid crystal cured film can be obtained by stirring or the like at a predetermined temperature a polymerizable liquid crystal compound and components other than the polymerizable liquid crystal compound such as an additive.

The vertically aligned liquid crystal cured film can be obtained by: the polymerizable liquid crystal composition is applied to a vertical alignment film described later, the solvent is removed, and the polymerizable liquid crystal composition containing the polymerizable liquid crystal compound in an aligned state is cured by heating and/or active energy rays.

The method of applying the polymerizable liquid crystal composition to the vertical alignment film may be the same as that used for forming the horizontally aligned liquid crystal cured film.

The method for removing the solvent may be the same as that for forming the horizontally aligned liquid crystal cured film.

As the light source of the active energy ray, the same light source as that used in forming the horizontally aligned liquid crystal cured film can be used.

When the ultraviolet irradiation intensity is applied for 1 or more times, the cumulative light amount is 10 to 3,000mJ/cm²Preferably 50 to 2,000mJ/cm²More preferably 100 to 1,000mJ/cm². When the cumulative light amount is less than the lower limit, 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 upper limit, the retardation plate with the optical compensation function including the vertical alignment liquid crystal cured film may be colored.

From the viewpoint of making the functional film thin, the thickness of the vertically aligned liquid crystal cured film is preferably 3 μm or less, more preferably 2 μm or less, and still more preferably 1.5 μm or less. The lower limit of the film thickness of the vertically aligned liquid crystal cured film is preferably 0.1 μm or more, more preferably 0.3 μm or more, and still more preferably 0.5 μm or more. The thickness of the vertically aligned liquid crystal cured film can be measured using an ellipsometer or a contact film thickness meter.

[ vertical alignment film ]

The alignment film is a film having an alignment controlling force for aligning the polymerizable liquid crystal compound of the liquid crystal cured film in a predetermined direction. Various orientations such as vertical orientation, horizontal orientation, hybrid orientation, and oblique orientation can be controlled by the type of alignment film, rubbing conditions, and light irradiation conditions. The vertical alignment film is an alignment film having an alignment controlling force for aligning the polymerizable liquid crystal compound of the liquid crystal cured film in a vertical direction. Therefore, by using the homeotropic alignment film, a homeotropic alignment liquid crystal film can be formed.

As the vertical alignment film, a material in which the surface tension of the surface of the substrate or the like is reduced is preferably used. Examples of such a material include the above-mentioned oriented polymer, for example, polyimide, polyamide, a fluorine-based polymer such as polyamic acid and perfluoroalkyl group which are hydrolysates thereof, a silane compound, and a polysiloxane compound obtained by a condensation reaction thereof. The vertical alignment film can be obtained by: a composition containing such a material and a solvent, for example, a solvent exemplified in the case of a homeotropic alignment liquid crystal film (hereinafter, also referred to as a composition for forming a homeotropic alignment film) is applied to a substrate or the like, and after removing the solvent, the applied film is heated or the like.

In the case where a silane compound is used for the vertical alignment film, the vertical alignment film is preferably a film formed of a compound containing an Si element and a C element among constituent elements, and a silane compound can be suitably used, from the viewpoint of easily reducing the surface tension and easily improving the adhesion to a layer adjacent to the vertical alignment film. In the present invention, when the vertical alignment film is disposed between the horizontally-aligned liquid crystal cured film and the vertically-aligned liquid crystal cured film, the vertical alignment film, the horizontally-aligned liquid crystal cured film, and the vertically-aligned liquid crystal cured film exhibit high adhesion, and peeling at the interface between the layers can be effectively suppressed or prevented in the retardation plate with an optical compensation function.

As the silane compound, the above-mentioned silicone-based silane coupling agent and the like can be preferably used, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethyl-butylidene) propylamine, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, silane-modified silane-based silane-modified silane-, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane and the like.

The silane compound may be either of a silicone monomer type or a silicone oligomer (polymer) type. When the silicone oligomer is shown as a (monomer) - (monomer) copolymer, there may be mentioned: a copolymer containing a mercaptopropyl group such as a 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, a 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, a 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and a 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, methacryloxypropyl-containing copolymers such as 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 3-acryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetraethoxysilane copolymer, acryloxypropyl-containing copolymers such as 3-acryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 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; and 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. The silane compound may be used alone or in combination of two or more. Further, a silane coupling agent or the like which is also used as a leveling agent in some cases may be used.

Among these, silane compounds having an alkyl group at the molecular terminal are preferable, and silane compounds having an alkyl group having 3 to 30 carbon atoms are more preferable.

The vertical alignment film is preferably a film formed of a compound containing an Si element, a C element, and an O element as constituent elements, from the viewpoint of easier improvement of adhesion, coating properties of the composition for forming a vertical alignment liquid crystal cured film, and from the viewpoint of difficulty in dissolving a layer disposed in a lower layer in a method for producing a retardation film with an optical compensation function described later. The number of carbon atoms of a substituent (preferably an alkyl group or an alkoxy group) including a C atom bonded to an Si atom in the silane compound forming the vertical alignment film is preferably 1 to 30, more preferably 2 to 25, and still more preferably 3 to 20. That is, the ratio of the Si element to the C element (Si/C, molar ratio) is preferably 0.03 to 1.00, more preferably 0.04 to 0.50, and still more preferably 0.05 to 0.33. When the Si/C ratio is not less than the lower limit, the coating property of the composition for forming a vertically aligned liquid crystal cured film is improved, and when the Si/C ratio is not more than the upper limit, the adhesion to the adjacent layer can be improved.

The solvent may be, for example, a solvent exemplified in the item of the horizontally aligned liquid crystal cured film. The method for applying the composition for forming a vertically aligned film includes the above-mentioned application method a, and the method for removing the solvent includes the above-mentioned solvent removal method a.

The composition for forming a vertically aligned film may contain, in addition to the solvent, the additives exemplified in the section of the horizontally aligned liquid crystal cured film, and the like.

From the viewpoint of making the retardation plate with an optical compensation function thinner and exhibiting an alignment control force, the film thickness of the vertical alignment film is preferably 1 μm or less, more preferably 0.3 μm or less, and still more preferably 0.1 μm or less. The thickness of the vertical alignment film is preferably 1nm or more, more preferably 5nm or more, still more preferably 10nm or more, and particularly preferably 30nm or more. The film thickness of the vertical alignment film can be measured using an ellipsometer or a contact film thickness meter.

[ substrate ]

The substrate is a material used when the alignment film-forming composition or the liquid crystal cured film-forming composition is applied, and may be a design in which a film applied to the substrate is transferred by peeling the substrate, or a design in which the film cannot be transferred by imparting adhesion to the substrate, and from the viewpoint of making the film thin, a design in which the film can be transferred to a transferred object or the substrate can be peeled is preferable. Examples of such a substrate include a glass substrate and a film substrate, and the film substrate is preferably a film substrate from the viewpoint of processability, and more preferably a long roll film from the viewpoint of continuous production. Examples of the resin constituting the film base include polyolefins such as polyethylene, polypropylene, and norbornene polymers; a cycloolefin resin; polyvinyl alcohol; polyethylene terephthalate; polymethacrylates; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfones; polyether sulfone; a polyether ketone; polyphenylene sulfide and polyphenylene oxide. The surface of the substrate may be subjected to a mold release treatment such as a silicone treatment. Examples of commercially available cellulose ester substrates include "FUJITACFELM" (manufactured by Fuji Photo Film Co., Ltd.); "KC 8UX 2M", "KC 8 UY" and "KC 4 UY" (manufactured by Konica Minolto Opto Co., Ltd.). Such a resin can be formed into a film by a known means such as a solvent casting method or a melt extrusion method to prepare a substrate.

Examples of commercially available cycloolefin resins include "Topas" (registered trademark) (manufactured by Ticona corporation, germany), "ARTON" (registered trademark) (manufactured by JSR corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (manufactured by Japan ZEON corporation), and "Apel" (registered trademark) (manufactured by mitsui chemical corporation). Commercially available cycloolefin resin substrates can also be used. Examples of commercially available cycloolefin resin substrates include "Escena" (registered trademark), "SCA 40" (registered trademark) (manufactured by waterlogging chemical industries co., ltd.), "zeonofilm" (registered trademark) (manufactured by OPTES corporation) and "ARTONFILM" (registered trademark) (manufactured by JSR corporation).

The substrate is preferably thick enough to allow easy lamination of a horizontally oriented liquid crystal cured film, a horizontally oriented film, a vertically oriented liquid crystal cured film, and a vertically oriented film, and easy peeling. The thickness of the base material is usually 5 to 300. mu.m, preferably 20 to 200. mu.m.

[ phase difference plate with optical compensation function ]

The retardation plate with an optical compensation function of the present invention preferably includes a horizontally oriented liquid crystal cured film, a horizontally oriented film or a vertically oriented film, and a vertically oriented liquid crystal cured film in this order, and satisfies the requirements (1) to (4) described below.

The interlayer distance between the horizontally-oriented liquid crystal cured film and the vertically-oriented liquid crystal cured film is 5 [ mu ] m or less. 1.1

The liquid crystal display device includes a horizontally oriented film or a vertically oriented film between a horizontally oriented liquid crystal cured film and a vertically oriented liquid crystal cured film. DEG- (2)

Satisfies the following relation

ReA(450)/ReA(550)＜1.00···(3)。

Here, the ReA (λ) represents an in-plane phase difference value at a wavelength λ nm of the horizontally aligned liquid crystal cured film.

The definition of the phase difference value is as follows.

ReA(λ)＝(nxA-nyA)×dA

Where nxA represents the main refractive index in the film plane of the horizontally aligned liquid crystal cured film, nyA represents the refractive index in the direction perpendicular to nxA in the same plane, and dA represents the thickness of the horizontally aligned liquid crystal cured film.

Satisfies the following relation

RthC(450)/RthC(550)＜1.00···(4)。

Here, RthC (λ) represents a phase difference value in the thickness direction at a wavelength λ nm of the vertically aligned liquid crystal cured film. The definition of the phase difference value is as follows.

RthC(λ)＝((nxC+nyC)/2-nzC)×dC

Here, nxC represents the main refractive index in the film plane of the vertically aligned liquid crystal cured film, nyC represents the refractive index in the direction perpendicular to nxC in the same plane, nzC represents the refractive index in the thickness direction of the vertically aligned liquid crystal cured film, and dC represents the thickness of the vertically aligned liquid crystal cured film.

When nxC is nyC, nxC may have a refractive index in any direction within the film surface.

The interlayer distance between the horizontally oriented liquid crystal cured film and the vertically oriented liquid crystal cured film is preferably 5 μm or less, more preferably 1 μm or less, still more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less as in the formula (1). The thickness of the horizontal alignment film is preferably 1nm or more, more preferably 5nm or more, still more preferably 10nm or more, and particularly preferably 30nm or more.

The retardation plate with an optical compensation function preferably satisfies the following relational expression (5). In order to reduce the amount of light leakage in the vicinity of a wavelength of 550nm in an oblique direction when an elliptically polarizing plate with an optical compensation function using a retardation plate with an optical compensation function is applied to a display, it is preferable that the values of | R0(550) -R40(550) | be smaller. The value of | R0(550) -R40(550) | is preferably less than 10nm, more preferably 5nm or less, further preferably 4nm or less, and particularly preferably 3nm or less.

|R0(550)-R40(550)|＜10nm···(5)

Here, R0(λ) represents an in-plane retardation value of the retardation plate with an optical compensation function including a horizontally-oriented liquid crystal cured film and a vertically-oriented liquid crystal cured film. R40 represents an apparent phase difference value when the phase difference plate with an optical compensation function including a horizontally oriented liquid crystal cured film and a vertically oriented liquid crystal cured film is rotated by 40 ° about a direction (fast axis direction) orthogonal to the principal refractive index direction in the film plane in the same plane.

The retardation plate with an optical compensation function preferably satisfies the following relational expression (6). In order to reduce the amount of light leakage in the vicinity of a wavelength of 450nm in an oblique direction when an elliptically polarizing plate with an optical compensation function using a retardation plate with an optical compensation function is used for a display, the smaller the value of | R0(450) -R40(450) |, the better. The value of | R0(450) -R40(450) | is preferably less than 10nm, more preferably 5nm or less, further preferably 4nm or less, and particularly preferably 3nm or less.

|R0(450)-R40(450)|＜10nm···(6)

Wherein R0(λ) represents an in-plane retardation value of the retardation plate with an optical compensation function including a horizontally-oriented liquid crystal cured film and a vertically-oriented liquid crystal cured film. R40 represents an apparent phase difference value when the phase difference plate with an optical compensation function including a horizontally oriented liquid crystal cured film and a vertically oriented liquid crystal cured film is rotated by 40 ° about a direction (fast axis direction) orthogonal to the principal refractive index direction in the film plane in the same plane.

The difference between the values shown in relational expressions (5) and (6) preferably satisfies relational expression (7) below.

|{R0(450)-R40(450)}-{R0(550)-R40(550)}|＜3nm···(7)

When the relational expression (7) is satisfied, when the optically compensating elliptical polarizing plate using the retardation plate with the optically compensating function is applied to a display, the reflection color in the front and oblique directions is close to black, and therefore the value of (7) is preferably 3nm or less, more preferably 2nm or less, and still more preferably 1nm or less.

When the average refractive index difference between the layers (i.e., the difference between the average refractive index of each layer constituting the retardation plate with an optical compensation function of the present invention and the average refractive index of the other layer adjacent to the layer) is large, light leakage may occur due to the influence of interface reflection occurring between the layers. The difference in average refractive index between the layers at a wavelength of 550nm is preferably 0.20 or less, more preferably 0.15 or less, still more preferably 0.10 or less, and particularly preferably 0.05 or less. Within this range, the occurrence of light leakage due to interface reflection can be suppressed.

Specific examples of the difference in average refractive index between the layers include:

(1) the difference between the average refractive index of the horizontally oriented liquid crystal cured film and the average refractive index of the vertically oriented liquid crystal cured film;

(2) in the case where a horizontal alignment film is included between the horizontally-aligned liquid crystal cured film and the vertically-aligned liquid crystal cured film,

(2-a) the difference between the average refractive index of the horizontally aligned liquid crystal cured film and the average refractive index of the horizontally aligned film,

(2-b) the difference between the average refractive index of the horizontal alignment film and the average refractive index of the vertical alignment liquid crystal cured film;

(3) in the case where a vertical alignment film is included between the horizontally-aligned liquid crystal cured film and the vertically-aligned liquid crystal cured film,

(3-a) the difference between the average refractive index of the horizontally aligned liquid crystal cured film and the average refractive index of the vertically aligned film,

(3-b) the difference between the average refractive index of the vertically aligned film and the average refractive index of the vertically aligned liquid crystal cured film;

and so on.

The retardation plate with an optical compensation function of the present invention may include layers other than the horizontally-oriented liquid crystal cured film, the horizontally-oriented film, the vertically-oriented liquid crystal cured film, and the vertically-oriented film, and specific examples thereof include other oriented liquid crystal cured films, other oriented films, protective layers, and the like. Examples of the other alignment liquid crystal cured film include the vertical alignment liquid crystal cured film and the horizontal alignment liquid crystal cured film described above, and examples of the other alignment film include the alignment film described above.

The protective layer is preferably formed from a composition for forming a protective layer, which generally contains: water-soluble polymers, that is, acrylic oligomers or polymers formed from polyfunctional acrylates (methacrylates), urethane acrylates, polyester acrylates, epoxy acrylates, and the like, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinyl pyrrolidone, starches, methyl cellulose, carboxymethyl cellulose, sodium alginate, and the like; and a solvent.

The solvent contained in the composition for forming a protective layer includes the same solvents as those exemplified above, and among them, at least one solvent selected from the group consisting of water, alcohol solvents, and ether solvents is preferable in terms of not dissolving the layer for forming a protective layer. Examples of the alcohol solvent include methanol, ethanol, butanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether. Examples of the ether solvent include ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. Among them, ethanol, isopropanol, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are preferable.

The thickness of the protective layer is 0.1 to 10 μm, and more preferably 0.1 to 3 μm.

[ method for producing retardation plate with optical compensation function ]

The method for producing the retardation plate with an optical compensation function of the present invention is not particularly limited as long as it is a method capable of sequentially laminating a horizontally oriented liquid crystal cured film, a horizontally oriented film or a vertically oriented film, and a vertically oriented liquid crystal cured film, and it is preferable that: a method in which a horizontally oriented film is laminated on a substrate, a horizontally oriented liquid crystal cured film is laminated on the horizontally oriented film, a vertically oriented film is further laminated on the horizontally oriented liquid crystal cured film, and a vertically oriented liquid crystal cured film is laminated on the vertically oriented film (hereinafter referred to as a production method a); alternatively, a method in which a vertically oriented film is laminated on a substrate, a vertically oriented liquid crystal cured film is laminated on the substrate, a horizontally oriented film is further laminated on the vertically oriented liquid crystal cured film, and a horizontally oriented liquid crystal cured film is laminated on the horizontally oriented film (hereinafter, referred to as production method B). The method of forming the layers described above can be used for the method of laminating the horizontally oriented liquid crystal cured film, the horizontally oriented film, the vertically oriented liquid crystal cured film, and the vertically oriented film.

When a retardation plate with an optical compensation function is manufactured by the manufacturing method a or the manufacturing method B, alignment failure or alignment defect may occur due to alignment of the liquid crystal cured film disposed in the lower layer. That is, in the case of the manufacturing method a, since the vertically aligned liquid crystal cured film is laminated after the horizontally aligned liquid crystal cured film is laminated on the lower layer, when the vertically aligned liquid crystal cured film is formed, an alignment defect or an alignment defect may be generated by the influence of the horizontally aligned liquid crystal cured film on the lower layer; in the case of the manufacturing method B, similarly, since the vertically aligned liquid crystal cured film is laminated on the lower layer and then the horizontally aligned liquid crystal cured film is laminated, when the horizontally aligned liquid crystal cured film is formed, alignment failure or alignment defect may occur due to the influence of the vertically aligned liquid crystal cured film on the lower layer. Therefore, depending on the kind of solvent of the composition (composition for forming a horizontally-oriented film, composition for forming a horizontally-oriented liquid crystal cured film, composition for forming a vertically-oriented liquid crystal cured film) used for forming each layer to be laminated, there are also cases where: the lower layer is dissolved to cause a change in optical characteristics, defective alignment, and the like. Therefore, it is necessary to select the materials, solvents, solid content concentrations, coating methods, film thicknesses, and the like contained in the composition used for forming each layer to be laminated as appropriate.

[ elliptical polarizing plate with optical compensation function ]

The retardation plate with the optical compensation function of the present invention can be transferred by being attached to a transfer object and peeling off the base material, or can be laminated via an adhesive or the like in a state of the substrate, whereby the functions of the retardation plate with the optical compensation function, that is, the optical properties thereof can be imparted to the transfer object, and an optical laminate to which the optical properties of the retardation plate with the optical compensation function are imparted can be manufactured. Among them, when laminated with a polarizing plate, an elliptical polarizing plate with an optical compensation function can be produced. In the embodiment of the present invention, it is preferable that the slow axis (optical axis) of the horizontally aligned liquid crystal cured film and the absorption axis of the polarizing plate are laminated so as to be substantially 45 °. The optical film of the present invention can be laminated so that the slow axis (optical axis) and the absorption axis of the polarizing plate are substantially 45 °, thereby obtaining a function as a circularly polarizing plate. The angle is substantially 45 °, and is usually in the range of 45 ± 5 °.

[ transferred body ]

Examples of the transferred object include: optical films having a single-layer structure, such as a polarizing plate, a retardation plate, a brightness enhancement film, an antiglare film, an antireflection film, a diffusion film, and a light-condensing film; the optical film having a multilayer structure includes, for example, a retardation plate and an elliptically polarizing plate, and among these, a retardation plate, a polarizing plate and an elliptically polarizing plate can be preferably used. The optical laminate of the present invention is useful for an image display device, for example, 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)), an electronic paper (a display device using an 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), or the like), a piezoelectric ceramic display, or the like, and is particularly suitably used for an organic EL display device, a touch panel display device, or the like.

[ polarizing plate ]

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

The stretched film having the dye having absorption anisotropy adsorbed thereon is 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 the substrate with water after the treatment with the aqueous boric acid solution. The polarizer obtained in this 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 the dichroic organic dye include a dichroic direct dye composed of a bisazo compound such as c.i. direct red 39, and a dichroic direct dye composed of a compound such as trisazo or tetraazo. As described above, 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 is preferably 5 μm to 40 μm.

[ Binders ]

Examples of the adhesive include pressure-sensitive adhesives, dry curing adhesives, and chemical reaction adhesives. Examples of the chemical reaction type adhesive include an active energy ray-curable 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, heat resistance and the like, and are less likely to cause floating, peeling and the like under heating or humidifying conditions.

The acrylic polymer is preferably a copolymer of a (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, 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 tackiness or the like on a transfer-receiving body even when removed after being attached to the transfer-receiving body, 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, etc., 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 of the display device when viewed from the front or when viewed from an oblique direction can be maintained, and the display image is less likely to be smeared or blurred.

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 urethane polymer 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, preferably 1 to 5 parts by mass, per 100 parts by mass of water.

Examples of the polyurethane resin include polyester type ionomer polyurethane resins.

The polyester type ionomer urethane resin herein refers to a urethane resin having a polyester skeleton and a small amount of ionic components (hydrophilic components) 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 polyamide polyamine (polyalkylene polyamine) (which is obtained by reacting polyalkylene polyamine such as diethylenetriamine or triethylenetetramine) with dicarboxylic acid such as adipic acid, and the like. Commercially available products of the polyamide-epoxy resin include "subminzrein (registered trademark) 650" and "subminzrein 675" (sumika chemtex co., ltd.), "WS-525" (manufactured by japan PMC corporation), and the like. When the epoxy resin is blended, the amount of the epoxy resin 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. When the adhesive layer formed of the dry curing adhesive is too thick, appearance defects tend to occur.

The active energy ray-curable adhesive may contain a solvent. The active energy ray-curable adhesive is an adhesive which 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 radical 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 that are cured by irradiation with an electron beam without containing such a polymerization initiator.

Among them, a radical polymerizable active energy ray-curable adhesive containing an acrylic curing component and a photo radical polymerization initiator, and a cation polymerizable active energy ray-curable adhesive containing an epoxy compound and a photo 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 photo radical polymerization initiator and the photo cation polymerization initiator include the above-mentioned photo radical polymerization initiator and photo cation polymerization initiator. 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, per 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 control agent, a plasticizer, an antifoaming agent, and the like.

In the present specification, the active energy ray is defined as an energy ray that can decompose a compound capable of generating an active species to generate an active species, and examples of such active energy rays include visible light, ultraviolet ray, infrared ray, X-ray, α ray, β ray, γ ray, electron beam, and the like, and ultraviolet ray and electron beam are preferable, and the irradiation condition of the preferable ultraviolet ray is the same as the polymerization of the polymerizable liquid crystal compound.

Examples

The present invention will be described more specifically with reference to examples. In the examples, "%" and "part(s)" refer to mass% and part(s) by mass, unless otherwise specified. In the following examples, the film thickness was measured using an ellipsometer M-220 manufactured by Nikon corporation or a contact type film thickness meter (MH-15M, Counter TC101, MS-5C manufactured by Nikon corporation). Further, the retardation value in the thickness direction Rth (λ), the in-plane retardation value Re (λ), and the apparent retardation value R40(λ) measured from the 40 ° direction were measured and calculated using KOBRA-WPR, a product of prince measuring instruments, or an ellipsometer M-220, a product of japan spectrography. The Si/C ratio can be calculated by elemental analysis of the vertical alignment film or measurement of surface constituent elements by X-ray photoelectron spectroscopy; alternatively, when the structural formula of the compound used for forming the vertical alignment film is completely known, the structural formula can be calculated. Further, AGF-B10 manufactured by Chunshi Motor Co., Ltd was used as the corona treatment device. The corona treatment may be suitably carried out when the composition is applied to a substrate. The corona treatment was carried out 1 time at an output of 0.3kW and a treatment speed of 3 m/min using the corona treatment apparatus.

[ example 1]

[ preparation of composition for Forming horizontally oriented film ]

As a component, 5 parts (weight average molecular weight: 30000) of a photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) were mixed, and the resulting mixture was stirred at 80 ℃ for 1 hour, thereby obtaining a composition for forming a horizontally aligned film.

[ preparation of composition for Forming vertically aligned film ]

A silane coupling agent "KBE-9103" manufactured by shin-Etsu chemical Co., Ltd was dissolved in a mixed solvent obtained by mixing ethanol and water at a ratio of 9: 1 (mass ratio), to obtain a composition for forming a vertically aligned film having a solid content of 0.5%.

[ production of composition for Forming horizontally oriented liquid Crystal cured film and composition for Forming vertically oriented liquid Crystal cured film ]

To a mixture obtained by mixing a polymerizable liquid crystal compound A and a polymerizable liquid crystal compound B shown below in a mass ratio of 90: 10, 1.0 part of a leveling agent (F-556; manufactured by DIC Co., Ltd.) and 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) -1-butanone ("Irgacure 369(Irg 369)", manufactured by BASF JAPAN Co., Ltd.) as a polymerization initiator were added.

Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80 ℃ for 1 hour to obtain a composition for forming a horizontally aligned liquid crystal cured film and a composition for forming a vertically aligned liquid crystal cured film.

The polymerizable liquid crystal compound a is produced by the method described in japanese patent application laid-open No. 2010-31223. The polymerizable liquid crystal compound B is produced by the method described in Japanese patent laid-open No. 2009-173893. The respective molecular structures are shown below.

[ polymerizable liquid Crystal Compound A ]

[ polymerizable liquid Crystal Compound B ]

[ 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 mass 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 mass ratio of 12/5/100 at 56.5 ℃ to be subjected to boric acid treatment (boric acid treatment step). The polyvinyl alcohol film subjected to the boric acid treatment step was washed with pure water at 8 ℃ and then dried at 65 ℃ to obtain a polarizer (thickness after stretching: 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 this drawing was 5.3 times. The obtained polarizing plate was bonded to a saponified triacetyl cellulose film (KC 4UYTAC 40 μm, manufactured by Konica Minolto) with a nip roll via an aqueous 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 aqueous adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (manufactured by Kuraray, "Kuraray PovalKL 318") and 1.5 parts of water-soluble polyamide epoxy Resin (manufactured by sumtex, "Sumirez Resin 650", an aqueous solution having a solid content of 30%) to 100 parts of water.

The optical characteristics of the obtained polarizing plate were measured. The measurement was carried out using a spectrophotometer ("V7100", manufactured by japanese spectrophotometer) with the polarizer surface of the polarizing plate obtained above as an incident surface. The absorption axis of the polarizing plate was aligned with the stretching direction of polyvinyl alcohol, and the obtained polarizing plate had a visibility-corrected monomer transmittance of 42.1%, a visibility-corrected polarization degree of 99.996%, a monomer hue a of-1.1, and a monomer hue b of 3.7.

[ production of a laminate comprising a substrate, a horizontally oriented film, and a horizontally oriented cured liquid crystal film ]

After corona treatment was performed on a COP film (ZF-14-50) manufactured by ZEON corporation, a composition for forming a horizontally oriented film was applied by a bar coater, dried at 80 ℃ for 1 minute, and the cumulative light amount at a wavelength of 313nm by using a polarized UV light irradiation apparatus ("SPOT CURE SP-9", manufactured by Ushio Motor Co., Ltd.): 100mJ/cm²Under the conditions of (1), polarized UV exposure was performed at an axis angle of 45 °. The thickness of the obtained horizontal alignment film was measured by an ellipsometer and found to be 100 nm.

Next, the composition for forming a horizontally oriented liquid crystal cured film was applied onto the horizontally oriented film BY a bar coater, dried at 120 ℃ for 1 minute, and then irradiated with ultraviolet rays (cumulative light amount at a wavelength of 365nm under nitrogen atmosphere: 500 mJ/cm) BY a high-pressure mercury lamp ("Unicure VB-15201 BY-A", manufactured BY Ushio Motor Co., Ltd.)²) Thus, a horizontally oriented liquid crystal cured film was formed, and a laminate including the substrate, the horizontally oriented film, and the horizontally oriented liquid crystal cured film was obtained. The thickness of the horizontally aligned liquid crystal cured film was measured by an ellipsometer and found to be 2.3 μm.

[ Re measurement of horizontally oriented liquid Crystal cured film ]

The in-plane retardation value ReA (λ) of the horizontally aligned liquid crystal cured film produced by the above method was measured by a measuring instrument ("KOBRA-WPR", manufactured by wanson instruments corporation) after being bonded to glass via an adhesive and then the COP as a substrate was peeled off. The phase difference value ReA (λ) at each wavelength was measured to obtain the results: ReA (450) ═ 121nm, ReA (550) ═ 142nm, ReA (650) ═ 146nm, and ReA (450)/ReA (550) ═ 0.85.

[ production of a laminate comprising a substrate, a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film ]

After corona treatment was performed on the laminate comprising the substrate, the horizontal alignment film, and the horizontal alignment liquid crystal cured film produced by the above method, the composition for forming a vertical alignment film was applied by a bar coater and dried at 80 ℃ for 1 minute, to obtain a vertical alignment film. The thickness of the obtained vertical alignment film was measured by an ellipsometer and found to be 50 nm.

Further, the composition for forming a vertically aligned liquid crystal cured film was applied onto the vertically aligned film BY a bar coater, dried at 120 ℃ for 1 minute, and then irradiated with ultraviolet rays (cumulative amount of light at a wavelength of 365nm under nitrogen atmosphere: 500 mJ/cm) BY a high-pressure mercury lamp ("Unicure VB-15201 BY-A", manufactured BY Ushio Motor Co., Ltd.)²) Thus, a vertically aligned liquid crystal cured film was formed, and a laminate including a substrate, a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film was obtained. The thickness of the cured film of the vertically aligned liquid crystal was measured by an ellipsometer and found to be 1.2. mu.m. In addition, the interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was 50 nm. The ratio of the constituent elements of the vertical alignment film was 0.33.

[ Rth measurement of vertically aligned liquid Crystal cured film ]

In order to measure Rth of the vertically aligned liquid crystal cured film, a vertically aligned film and a vertically aligned liquid crystal cured film were produced on a COP film (ZF-14-50) manufactured by ZEON corporation, japan, by the same procedure as described above, the vertically aligned liquid crystal cured film was bonded to glass via an adhesive (pressure sensitive adhesive 15 μm manufactured by linetec), and after confirming that there was no phase difference in the COP, the phase difference was measured by changing the incident angle of light to the sample with an ellipsometer. The average refractive indices at wavelengths λ of 450nm and 550nm were measured by a refractometer (manufactured by Atago, Inc.'s "multiwavelength Abbe refractometer DR-M4"). The ReC calculated from the film thickness, the average refractive index, and the measurement result of the ellipsometer obtained were: RthC (450) — 63nm, RthC (550) — 73nm, and RthC (450)/RthC (550) — 0.85.

[ measurement of R0 and R40 in a laminate (retardation plate with optical compensation function) including a horizontally oriented liquid crystal cured film, a vertically oriented film, and a vertically oriented liquid crystal cured film ]

After a sample for measurement was prepared by bonding a laminate comprising the substrate, the horizontal alignment film, the horizontal alignment liquid crystal cured film, the vertical alignment film, and the vertical alignment liquid crystal cured film produced by the above method to glass via an adhesive (15 μm, a pressure-sensitive adhesive manufactured by linetec corporation), and peeling off COP, the retardation value R0(λ) in the front direction of the retardation plate with the optical compensation function and the retardation value R40(λ) when the retardation plate was tilted by 40 ° around the fast axis of the horizontal alignment liquid crystal cured film were measured with KOBRA-WPR after confirming that there was no retardation in the horizontal alignment film and the vertical alignment film. From the obtained values of R0(λ) and R40(λ), R0(550) -R40(550) |, | R0(450) -R40(450) |, and | { R0(450) -R40(450) } - { R0(550) -R40(550) } |, are calculated, and the obtained results are shown in Table 1.

[ difference in-plane average refractive index of each layer ]

The above-described method was used to coat each layer on glass, and the average refractive index of each layer was calculated using a refractometer (manufactured by agago, "multiwavelength abbe refractometer DR-M4") or ellipsometry, and it was confirmed that the difference between the in-plane average refractive indices of each layer was 0.2 or less.

[ bending test ]

On the coating film surface side of the laminate comprising the substrate, the horizontal alignment film, the horizontal alignment liquid crystal cured film, the vertical alignment film, and the vertical alignment liquid crystal cured film produced by the above method, a glass plate having a thickness of 0.7mm was placed, the laminate was bent 180 degrees so as to lie on the glass plate, then light of a fluorescent lamp was transmitted through a magnifying glass of 10 times, and the bent portion was observed to confirm the presence or absence of wrinkles and cracks. The results are shown in Table 1.

[ confirmation of reflected hue at curved part ]

After the corona treatment was applied to the coating surface side of the laminate comprising the substrate, the horizontal alignment film, the horizontal alignment liquid crystal cured film, the vertical alignment film, and the vertical alignment liquid crystal cured film produced by the above method, the laminate was bonded to the polarizing plate produced by the above method via an adhesive so that the angle formed between the absorption axis of the polarizing plate and the slow axis of the horizontal alignment film became 45 °, and the substrate was peeled off to produce an elliptically polarizing plate having an optical compensation function. Thereafter, the film was bonded to an aluminum foil via an adhesive, and the film was bent 180 ° so as to have a radius of 1cm on the polarizing plate side, and the reflected color at the bent portion was visually observed. The results are shown in Table 1.

(examples 2 and 3)

A retardation plate with an optical compensation function was produced in the same manner as in example 1, except that the film thickness of the vertical alignment film was changed as shown in table 1, and the retardation value measurement, the bending property test, and the reflected color confirmation at the bent portion were performed. The results are shown in Table 1.

(example 4)

A retardation plate with an optical compensation function was produced in the same manner as in example 1 except that 0.5 wt% of polyimide ("sunver SE-610", manufactured by nippon chemical industries co., ltd.), 72.3 wt% of N-methyl-2-pyrrolidone, 18.1 wt% of 2-butoxyethanol, 9.1 wt% of ethylcyclohexane, and 0.01 wt% of DPHA (manufactured by shinkamura chemical) were mixed to prepare a composition B for forming a vertically aligned film, and this composition B for forming a vertically aligned film was used, and a retardation value measurement, a bending property test, and a reflected hue confirmation at a bent portion were performed. The results are shown in Table 1. The film thickness of the vertical alignment film was measured by an ellipsometer and found to be 0.2. mu.m. It was found that the interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was 0.2. mu.m. In addition, it was confirmed that: when the composition for forming a vertically aligned liquid crystal cured film is applied, the vertically aligned film is eroded by a solvent, and alignment defects and poor alignment locally occur.

(example 5)

A retardation plate having an optical compensation function was produced in the same manner as in example 1, and retardation value measurement, a bending property test, and confirmation of a reflection hue at a bent portion were performed, except that the substrate was changed to a polyethylene terephthalate film subjected to a mold release treatment (SP-PLR 382050 manufactured by Lintec corporation, hereinafter abbreviated as "separator"), and the lamination order was changed to the order of a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film. The results are shown in Table 1. The thickness of the horizontal alignment film was measured by an ellipsometer and found to be 0.2. mu.m. It was found that the interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was 0.2. mu.m.

(examples 6 and 7)

A retardation plate with an optical compensation function was produced in the same manner as in example 1 except that the film thickness of the vertically aligned liquid crystal cured film was changed to change the values of RthC (450) and RthC (550) as shown in table 1, and retardation value measurement, a bending property test, and confirmation of the reflection hue at the bent portion were performed. The results are shown in Table 1.

(example 8)

A retardation plate with an optical compensation function was produced in the same manner as described in example 1 except that the composition for forming a vertically aligned liquid crystal cured film was changed to the composition (B) for forming a vertically aligned liquid crystal cured film described below, and the drying temperature after application of the composition (B) for forming a vertically aligned liquid crystal cured film was changed from 120 ℃ to 80 ℃, and the retardation value measurement, the bending property test, and the confirmation of the reflection hue at the bent portion were performed. The results are shown in Table 1.

(preparation of composition (B) for Forming vertically aligned liquid Crystal cured film)

For the liquid crystal compound LC242 described below: 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 composition (B) for forming a vertically aligned liquid crystal cured film. The name of the obtained liquid crystal composition was designated as "composition V".

Liquid crystal compound LC 242: paliocolor LC242(BASF company registered trademark)

Comparative example 1

After a laminate of a horizontal alignment film and a horizontal alignment liquid crystal cured film was produced by the method described in example 1, a laminate of a vertical alignment film and a vertical alignment liquid crystal cured film (manufactured by Lintec corporation) was prepared on a COP separately by the same method as in example. The obtained laminates were bonded to each other with an adhesive (pressure-sensitive adhesive 15 μm manufactured by Lintec Co., Ltd.), and subjected to a phase difference value measurement, a bending property test and confirmation of a reflection hue at a bent portion. The results are shown in Table 1.

[ Table 1]

Bend reflection hue the case where black was noted as ○ and the case where distinct coloring was observed was noted as x.

The bending test was carried out, and the test was evaluated as ○ when no failure occurred and as X when failure such as wrinkles or cracks occurred.

By applying the manufacturing method of the present invention, a retardation plate with an optical compensation function is obtained which can suppress defects such as wrinkles and cracks generated at the time of bending.

Claims

1. A method for manufacturing a phase difference plate having an optical compensation function,

further forming a vertical alignment film through a coating and drying process,

2. The method of manufacturing a retardation plate with an optical compensation function according to claim 1, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film having a film thickness of 1.0 μm or less are formed in this order.

3. The method for producing a retardation plate with an optical compensation function according to any one of claims 1 to 2, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film formed from the photo-alignment film are formed in this order.

4. The method for manufacturing a retardation plate with an optical compensation function according to any one of claims 1 to 3, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film formed from a photoalignment film containing a cinnamoyl group are formed in this order.

5. The method for producing a retardation plate with an optical compensation function according to any one of claims 1 to 4, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having a film thickness of 1.0 μm or less, and a vertical alignment liquid crystal cured film are formed in this order.

6. The method of manufacturing a retardation plate with an optical compensation function according to any one of claims 1 to 5, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film containing an Si element, and a vertical alignment liquid crystal cured film are formed in this order.

7. The method for producing a retardation plate with an optical compensation function according to any one of claims 1 to 6, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having an Si/C element of 0.03 to 1.00, and a vertical alignment liquid crystal cured film are formed in this order.

8. The method for producing a retardation plate with an optical compensation function according to any one of claims 1 to 7, which comprises forming a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film in this order, wherein the horizontal alignment liquid crystal cured film satisfies the following relationship (1):

ReA(450)/ReA(550)＜1.00…(1)

wherein ReA (λ) represents an in-plane retardation value at a wavelength λ nm of the horizontally aligned liquid crystal cured film, and the definition of the in-plane retardation value ReA (λ) is as follows,

ReA(λ)＝(nxA(λ)-nyA(λ))×dA

9. The method for producing a retardation plate with an optical compensation function according to any one of claims 1 to 8, which comprises forming a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film, and a vertical alignment liquid crystal cured film in this order, wherein the vertical alignment liquid crystal cured film satisfies the following relationship (2):

RthC(450)/RthC(550)＜1.00…(2)

wherein RthC (λ) represents a retardation value in the thickness direction at a wavelength λ nm of the vertically aligned liquid crystal cured film, and the retardation value RthC (λ) is defined as follows,

RthC(λ)＝((nxC(λ)+nyC(λ))/2-nzC(λ))×dC

dC denotes the thickness of the vertically aligned liquid crystal cured film.

10. A method for manufacturing a phase difference plate having an optical compensation function,

forming a vertical alignment film through a coating and drying process,

further forming a horizontal alignment film by coating, drying and aligning,

11. The method of manufacturing a retardation plate with an optical compensation function according to claim 10, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film having a film thickness of 1.0 μm or less, and a horizontal alignment liquid crystal cured film are formed in this order.

12. The method of manufacturing a retardation plate with an optical compensation function according to claim 10 or 11, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film formed of a photo-alignment film, and a horizontal alignment liquid crystal cured film are formed in this order.

13. The method for manufacturing a phase difference plate with an optical compensation function according to any one of claims 10 to 12, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film formed from a photoalignment film containing a cinnamoyl group, and a horizontal alignment liquid crystal cured film are formed in this order.

14. The method for producing a retardation plate with an optical compensation function according to any one of claims 10 to 13, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film are formed in this order to have a film thickness of 1.0 μm or less.

15. The method for producing a retardation plate with an optical compensation function according to any one of claims 10 to 14, wherein a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film containing an Si element are formed in this order.

16. The method for producing a retardation plate with an optical compensation function according to any one of claims 10 to 15, wherein a horizontal alignment film, a horizontal alignment liquid crystal cured film, a vertical alignment film having an Si/C element of 0.03 to 1.00, and a vertical alignment liquid crystal cured film are formed in this order.

17. The method for producing a retardation plate with an optical compensation function according to any one of claims 10 to 16, which comprises forming a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film in this order, wherein the horizontal alignment liquid crystal cured film satisfies the following relationship (3):

ReA(450)/ReA(550)＜1.00…(3)

ReA(λ)＝(nxA(λ)-nyA(λ))×dA

18. The method for producing a retardation plate with an optical compensation function according to any one of claims 10 to 17, which comprises forming a vertical alignment film, a vertical alignment liquid crystal cured film, a horizontal alignment film, and a horizontal alignment liquid crystal cured film in this order, wherein the vertical alignment liquid crystal cured film satisfies the following relationship (4):

RthC(450)/RthC(550)＜1.00…(4)

RthC(λ)＝((nxC(λ)+nyC(λ))/2-nzC(λ))×dC

dC denotes the thickness of the vertically aligned liquid crystal cured film.