JP7491660B2 - Retardation plate with optical compensation function - Google Patents

Description

The present invention relates to a retardation plate with optical compensation function.

An elliptical polarizing plate is an optical component in which a polarizing plate and a retardation plate are laminated together, and is used, for example, in organic EL image display devices that display images in a flat state, to prevent light reflection from the electrodes that make up the device. In this elliptical polarizing plate, a so-called λ/4 plate is used as the retardation plate.

A retardation plate that exhibits reverse wavelength dispersion is suitable for use in such an elliptical polarizing plate, since it exhibits equivalent retardation performance over a wide wavelength range of visible light. A known retardation plate that exhibits reverse wavelength dispersion is one that is made only of a horizontally aligned liquid crystal cured film obtained by polymerizing and curing a polymerizable liquid crystal compound that exhibits reverse wavelength dispersion while aligning it in the horizontal direction.

Also, there is a demand for an elliptical polarizing plate with an optical compensation function that has a compensation function to provide the same optical performance when viewed from an oblique direction as when viewed from the front direction. Patent Document 1 [JP Patent Publication No. 2015-163935] proposes an optical compensation retardation plate for use in such an elliptical polarizing plate with an optical compensation function, which further includes a vertically aligned liquid crystal cured film obtained by polymerizing and curing a polymerizable liquid crystal compound in a vertically aligned state, together with a horizontally aligned liquid crystal cured film with reverse wavelength dispersion. The vertically aligned liquid crystal cured film specifically disclosed in this document does not exhibit reverse wavelength dispersion, but exhibits normal positive wavelength dispersion, and exhibits a sufficient compensation function in an image display device that displays images in a normal flat state.

JP 2015-163935 A

However, when such conventional elliptical polarizing plates with optical compensation functions are applied to foldable, so-called flexible displays, when the display is folded while still displaying an image, the elevation angle (the angle between the film plane and the direction in which the viewer views the screen) at the folded portion is effectively very small, and it has been found that the optical performance is not adequately compensated, causing external light to be reflected in a colored state and causing defects such as wrinkles when folded.

The object of the present invention is therefore to develop a retardation plate with optical compensation function for use in an elliptical polarizing plate with optical compensation function that can be applied to a flexible display and does not cause defects such as wrinkles even when folded with an image displayed, sufficiently compensates for optical performance, and does not reflect external light in a colored state.

The present inventors conducted extensive research to solve the above problems and have now completed the present invention.
That is, the present invention includes the following.

[1] A horizontally aligned liquid crystal cured film in which a composition containing a polymerizable liquid crystal compound is cured in a state in which the composition is aligned in the horizontal direction relative to the film plane;
and a vertically aligned liquid crystal cured film obtained by curing a composition containing a polymerizable liquid crystal compound in a state where the composition is aligned in a direction vertical to the in-plane of the film, the retardation plate having an optical compensation function satisfying the following relations (1) to (4).
The interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is 5 μm or less. ... (1)
A horizontal alignment film or a vertical alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film.
ReA(450)/ReA(550)<1.00...(3)
[In the formula, ReA(λ) represents an in-plane retardation value of a horizontally aligned liquid crystal cured film at a wavelength of λ nm.]
The in-plane retardation value ReA(λ) is defined as follows.
ReA(λ)=(nxA(λ)-nyA(λ))×dA
Here, nxA(λ) is the principal refractive index in the film plane of the horizontally aligned liquid crystal cured film, and the principal refractive index for light of wavelength λ (nm) is
nyA(λ) is the refractive index in a direction perpendicular to nxA(λ) in the same plane, and is the refractive index for light of wavelength λ (nm),
dA indicates the thickness of the horizontally aligned liquid crystal film.
RthC(450)/RthC(550)<1.00 (4)
In the formula, RthC(λ) represents a retardation value in the thickness direction of the vertically aligned liquid crystal cured film at a wavelength of λ nm. The retardation value RthC(λ) is defined as follows.
RthC(λ)=((nxC(λ)+nyC(λ))/2-nzC(λ))×dC
Here, nxC(λ) is the principal refractive index in the film plane of the vertically aligned liquid crystal cured film, and the principal refractive index for light of wavelength λ (nm) is expressed as follows:
nyC(λ) is the refractive index in a direction perpendicular to nxC(λ) in the same plane, and is the refractive index for light of wavelength λ (nm).
nzC(λ) is the refractive index in the thickness direction of the vertically aligned liquid crystal cured film, and is the refractive index for light of wavelength λ (nm),
dC indicates the film thickness of the vertically aligned liquid crystal film.
In addition, in the formula (4), when nxC=nyC, nxC can be the refractive index in any direction within the film plane.

[2] The retardation plate with optical compensation function according to [1]1 above, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (5).
|R0(550)-R40(550)|<10 nm ... (5)
Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm).
R40(λ) is an apparent retardation value when a retardation plate with optical compensation function, which includes a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, is rotated 40° around a direction (fast axis direction) perpendicular to the principal refractive index direction in the same plane as the film plane, and indicates a retardation value for light of wavelength λ (nm).

[3] The retardation plate with optical compensation function according to [1] or [2] above, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (6).
|R0(450)-R40(450)|<10 nm ... (6)
[Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm). Also, R40(λ) is the apparent retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film when rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane, and indicates the retardation value for light of wavelength λ (nm).]

[4] The retardation plate with optical compensation function according to any one of [1] to [3] above, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (7):
|{R0(450)-R40(450)}-{R0(550)-R40(550)}|<3 nm ... (7)
[Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm). Also, R40(λ) is the apparent retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film when rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane, and indicates the retardation value for light of wavelength λ (nm).]

[5] A retardation plate with optical compensation function according to any one of [1] to [4] above, in which the average refractive index difference at a wavelength of 550 nm of the horizontally aligned liquid crystal cured film, the vertically aligned liquid crystal cured film, and the horizontally aligned film or the vertically aligned film is 0.20 or less.

[6] A retardation plate with optical compensation function according to any one of [1] to [5] above, in which a horizontal alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, and the horizontal alignment film is a photo-alignment film.

[7] A retardation plate with optical compensation function according to any one of [1] to [6] above, in which a horizontal alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, and the horizontal alignment film includes a cinnamoyl group.

[8] A retardation plate with optical compensation function according to any one of [1] to [7] above, in which a vertical alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, and the film thickness of the vertical alignment film is 30 nm or more and 1 μm or less.

[9] A retardation plate with optical compensation function according to any one of [1] to [8] above, in which a vertical alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, and the vertical alignment film is a film made of a compound containing Si, C and O as constituent elements.

[10] An elliptical polarizing plate in which the retardation plate with optical compensation function described in any one of [1] to [9] above and a polarizing plate are laminated.

[11] An organic EL display device including the elliptically polarizing plate described in [10] above.

An elliptical polarizing plate with optical compensation function that uses the retardation plate with optical compensation function of the present invention exhibits less change in reflective hue when applied to a flexible display and folded.

[Horizontal alignment liquid crystal cured film]
The horizontally aligned liquid crystal cured film is a film having a refractive index anisotropy in the film plane, and is made of a polymer containing a polymerizable liquid crystal compound. The horizontally aligned liquid crystal cured film is preferably formed by applying a polymerizable liquid crystal composition onto the horizontally aligned film, and polymerizing the composition containing the polymerizable liquid crystal compound in the aligned state by heating and/or light irradiation, in terms of being able to arbitrarily design the thinning and wavelength dispersion characteristics of the horizontally aligned liquid crystal cured film.

The three-dimensional refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film may have biaxiality, but preferably has uniaxiality. The horizontally aligned liquid crystal cured film may be a horizontally aligned liquid crystal cured film made of a polymer of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound in a state of being aligned in the horizontal direction relative to the plane of the horizontally aligned liquid crystal cured film, or may be a hybrid aligned liquid crystal cured film or an inclined aligned liquid crystal cured film. The refractive indexes nx, ny, and nz in three directions in the 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 the principal refractive index in the direction parallel to the plane of the horizontally aligned liquid crystal cured film in the refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film. ny represents the refractive index in the direction parallel to the plane of the horizontally aligned liquid crystal cured film and perpendicular to the direction of nx in the refractive index ellipsoid formed by the horizontally aligned liquid crystal cured film. nz represents the refractive index in the direction perpendicular to the plane of the horizontally aligned liquid crystal cured film in the index ellipsoid formed by the horizontally aligned liquid crystal cured film.

The horizontally aligned liquid crystal cured film can be made of either rod-shaped or disk-shaped polymerizable liquid crystal, but rod-shaped polymerizable liquid crystal is preferred. When rod-shaped polymerizable liquid crystal forms the 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, it is preferable that the in-plane retardation value Re1 (550) for light with a wavelength of 550 nm satisfies the optical characteristics shown in the following formula (21). In addition, it is also preferable that the horizontally aligned liquid crystal cured film has an in-plane retardation value Re1 (450) for light with a wavelength of 450 nm, an in-plane retardation value Re1 (550) for light with a wavelength of 550 nm, and an in-plane retardation value Re1 (650) for light with a wavelength of 650 nm satisfies the optical characteristics shown in the formulas (22) and (23). It is more preferable that the horizontally aligned liquid crystal cured film satisfies the optical characteristics shown in the following formulas (21), (22), and (23).
120 nm≦ReA(550)≦170 nm ... (21)
[In the formula, ReA(550) represents the in-plane phase difference 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 the in-plane retardation value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 450 nm, ReA(550) represents the in-plane retardation value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 550 nm, and ReA(650) represents the in-plane retardation value of the horizontally aligned liquid crystal cured film with respect to light having a wavelength of 650 nm.]

If the in-plane retardation value ReA(550) of the horizontally aligned liquid crystal cured film exceeds the range of formula (21), the hue of the front of the display to which the optically compensated elliptical polarizer including the optically compensated retardation plate is applied may become red or blue. A more preferable range of the in-plane retardation value is 130 nm≦ReA(550)≦160 nm. If the "ReA(450)/ReA(550)" of the horizontally aligned liquid crystal cured film exceeds 1.0, the ellipticity of the elliptical polarizer having the horizontally aligned liquid crystal cured film on the short wavelength side deteriorates. If the ellipticity of the elliptical polarizer on the short wavelength side deteriorates and becomes smaller than 1.0, the function of the elliptical polarizer when viewed from the front on the short wavelength side tends to be impaired. This "ReA(450)/ReA(550)" is preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and even more 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 can be adjusted to obtain a desired in-plane retardation value (ReA(λ): the in-plane retardation value of the horizontally aligned liquid crystal cured film at a wavelength λ (nm)). The three-dimensional refractive index depends on the molecular structure and the alignment state of the polymerizable liquid crystal compound described later.
ReA(λ)=(nxA(λ)-nyA(λ))×dA (24)
[In the formula, the 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 the principal refractive index in a direction parallel to the plane of the horizontally aligned liquid crystal cured film for light of wavelength λ (nm). nyA(λ) represents the refractive index in a direction parallel to the plane of the horizontally aligned liquid crystal cured film and perpendicular to the direction of nxA(λ) for light of wavelength λ (nm) in the 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 a 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 refers to a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase order structure may be a nematic liquid crystal or a smectic liquid crystal.

In the present invention, the polymerizable liquid crystal compound satisfies the following formula (I) in order to satisfy the relationship of the above formulas (21) and (22) or the relationship of the below-described formulas (31) and (32) that exhibit reverse wavelength dispersion.

で表される化合物が好ましい。

Preferred is a compound represented by the following formula:

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group referred to here is a group having a planar ring structure, and the number of π electrons of the ring structure is [4n+2] according to the Huckel rule. Here, n represents an integer. When a ring structure is formed by including heteroatoms such as -N= or -S-, the non-covalent bond electron pairs on these heteroatoms also satisfy the Huckel rule and have aromaticity. It is preferable that the divalent aromatic group contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom.

G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group.
Here, a hydrogen atom contained in the divalent aromatic group or 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 a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.

L ¹ , L ² _, B ¹ and B ² each independently represent a single bond or a divalent linking group.

k and l each independently represent an integer of 0 to 3, and satisfy the relationship 1≦k+l, where, when 2≦k+l, B ¹ and B ² , G ¹ and G ² may be the same as or different from each other.

^E1 and ^E2 each independently represent an alkanediyl group having 1 to 17 carbon atoms, in which a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and _-CH2- contained in the alkanediyl group may be substituted with -O-, -S- or -Si-. ^P1 and ^P2 each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group. At least one of the multiple G ^1s and G ^2s is preferably a divalent alicyclic hydrocarbon group, and more preferably at least one of G ^1s and G ^2s bonded to L ¹ or L ² is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, -CR ^c =CR ^d -, or C≡C-. Here, R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 -. Here, R ^a2-1 , R ^a4-1 and R ^a6-1 each independently represent a single bond, -CH ₂ - or -CH 2 CH _{2 -} , and L ¹ and L ² each independently preferably represent a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ - or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or R ^a15 OC═OOR ^a16 -. Here, R ^a9 to R ^a16 are each independently a single bond, or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 and R ^a14-1 each independently represent a single bond, -CH ₂ - or -CH ₂ CH ₂ -. B ¹ and B ² each independently represent more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO- or OCOCH ₂ CH ₂ -.

From the viewpoint of expressing reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. k=2 and l=2 are even more preferable because they result in a symmetrical structure.

E ¹ and E ² each independently preferably represent an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by ^P1 or ^P2 include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle 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 the like, and the benzene ring and the naphthalene ring are preferable. Examples of the aromatic heterocycle 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, it is preferable that Ar has a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is more preferable that Ar has a benzothiazole group. In addition, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (I), the total number _Nπ of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. In addition, it is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Examples of aromatic groups represented by Ar include the following:

In formulae (Ar-1) to (Ar-22), the mark * represents a linking portion, and Z ⁰ , Z ¹ and Z ² each independently represent 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.

Q ¹ and Q ² each independently represent -CR ^{2 '} R ^{3 '} -, -S-, -NH-, -NR ^{2 '} -, -CO- or O-, and R ^{2 '} and R ^{3 '} each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom; m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group in ^Y1 , ^Y2 , and ^Y3 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, of which a phenyl group and a naphthyl group are preferred, and a phenyl group is more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, of which a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferred.

^Y1 and ^Y2 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each preferably independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms, Z ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

^Q1 and ^Q2 are preferably -NH-, -S-, ^-NR2'- or -O-, and R2 ^' is preferably a hydrogen atom. Among these, -S-, -O- or -NH- is particularly preferred.

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

In formulae (Ar-16) to (Ar-22), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ^0. Examples of the aromatic heterocyclic group include those described above as aromatic heterocyclic rings that Ar may have, such as 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. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ may be, together with the nitrogen atom to which it is bonded and Z ⁰ , the above-mentioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted. Examples include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring. The compound represented by formula (I) can be produced, for example, according to the method described in JP-A-2010-31223.

The polymerizable liquid crystal compounds can be used alone or in combination of two or more. When two or more types are used in combination, the content of the compound represented by formula (I) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, per 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 to form 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 improver. These additives may be used alone or in combination of two or more kinds.

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, relative to 100 parts by mass of the solid content of the polymerizable liquid crystal composition. If the content is within the above range, the alignment of the horizontally aligned liquid crystal cured film tends to be high. Here, the solid content refers to the total amount of components excluding the solvent from the composition.

The solvent is preferably one that can dissolve the polymerizable liquid crystal compound, and is preferably one that is inactive in the polymerization reaction of the polymerizable liquid crystal compound. Examples of the solvent include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 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; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP), and 1,3-dimethyl-2-imidazolidinone. These solvents can be used alone or in combination of two or more. However, since the compound represented by formula (I) generally has a relatively large conjugated system, it has low solubility in a solvent, and among the solvents exemplified above, it is preferable to use alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, ether solvents, amide solvents, and aromatic hydrocarbon solvents, and it is more preferable to use ester solvents, ketone solvents, chlorine-containing solvents, ether solvents, and amide solvents.

The content of the solvent is preferably 50 to 98 parts by weight, more preferably 70 to 95 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal composition. Therefore, the solid content per 100 parts by weight of the composition is preferably 2 to 50 parts by weight. If the solid content of the composition is 50 parts by weight or less, the viscosity of the composition is low, so that the thickness of the horizontally aligned liquid crystal cured film becomes approximately uniform, and unevenness tends to be less likely to occur in the horizontally aligned liquid crystal cured film. The above solid content can be appropriately determined taking into consideration the thickness of the horizontally aligned liquid crystal cured film to be produced.

A polymerization initiator is a compound that generates reactive species by the contribution of heat or light and can initiate a polymerization reaction of polymerizable liquid crystals and the like. Examples of reactive species include active species such as radicals, cations, and anions. Among them, photopolymerization initiators, in which the reaction proceeds by irradiation with light, are preferred from the viewpoint of ease of reaction control.

Examples of the photopolymerization initiator include a photoradical polymerization initiator, a photocationic polymerization initiator, etc. Examples of the photoradical polymerization initiator include a benzoin compound, a benzophenone compound, a benzyl ketal compound, an α-hydroxyketone compound, an α-aminoketone compound, a triazine compound, etc. Examples of the photocationic polymerization initiator include an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt, or an aromatic sulfonium salt, an iron-arene complex, etc.
Specifically, Irgacure (registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure 2959, Irgacure 754, Irgacure 379EG (all manufactured by BASF Japan Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (all manufactured by Seiko Chemical Co., Ltd.), Kayacure BP100 (manufactured by Nippon Kayaku Co., Ltd.), ADEKA Co., Ltd.), Kayacure UVI-6992 (Dow Chemical Co., Ltd.), ADEKA Optomer SP-152, ADEKA Optomer SP-170, ADEKA Optomer N-1717, ADEKA Optomer N-1919, ADEKA Arcles NCI-831, ADEKA Arcles NCI-930 (all manufactured by ADEKA Corporation), TAZ-A, TAZ-PP (all manufactured by Nippon SiberHegner Co., Ltd.) and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.), Kayarad (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), Cyracure UVI series (manufactured by Dow Chemical Co., Ltd.), CPI series (manufactured by San-Apro Co., Ltd.), TAZ, BBI and DTS (all manufactured by Midori Kagaku Co., Ltd.), RHODORSIL (registered trademark) (manufactured by Rhodia Co., Ltd.), etc. The photopolymerization initiator can be used alone or in combination of two or more kinds. Among these, photoradical polymerization initiators that generate radicals upon irradiation with light are preferred from the viewpoint of ease of reaction control.

From the viewpoint of being able to fully utilize the energy emitted from the light source and being excellent in productivity, it is preferable for the photopolymerization initiator to have a maximum absorption wavelength in the range of 300 nm to 400 nm, and more preferably in the range of 300 nm to 380 nm. From the same viewpoint, α-acetophenone-based polymerization initiators and oxime-based photopolymerization initiators are also preferable.

Examples of α-acetophenone-based polymerization initiators include 2-methyl-2-morpholino-1-(4-methylsulfanylphenyl)propan-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutan-1-one, and 2-dimethylamino-1-(4-morpholinophenyl)-2-(4-methylphenylmethyl)butan-1-one, and more preferably 2-methyl-2-morpholino-1-(4-methylsulfanylphenyl)propan-1-one and 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutan-1-one. Commercially available α-acetophenone compounds include Irgacure 369, 379EG, and 907 (all manufactured by BASF Japan Ltd.) and Seikuol BEE (manufactured by Seiko Chemical Co., Ltd.).

Oxime-based photopolymerization initiators generate radicals when irradiated with light. These radicals allow the polymerization of the polymerizable liquid crystal compound to proceed favorably in the depths of the horizontally aligned liquid crystal cured film. In addition, from the viewpoint of more efficiently progressing the polymerization reaction in the depths of the horizontally aligned liquid crystal cured film, it is preferable to use a photopolymerization initiator that can efficiently utilize ultraviolet light with a wavelength of 350 nm or more. As photopolymerization initiators that can efficiently utilize ultraviolet light with a wavelength of 350 nm or more, triazine compounds and oxime ester type carbazole compounds are preferred, and from the viewpoint of sensitivity, oxime ester type carbazole compounds are more preferred. Examples of oxime ester type carbazole compounds include 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), and the like. Commercially available oxime ester carbazole compounds include Irgacure OXE-01, Irgacure OXE-02, Irgacure OXE-03 (all manufactured by BASF Japan Ltd.), Adeka Optomer N-1919, Adeka Arcles NCI-831 (all manufactured by ADEKA Corporation), etc.

The amount of 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. Within the above range, the reaction of the polymerizable group proceeds sufficiently, and the orientation of the polymerizable liquid crystal compound is unlikely to be disturbed.

By adding a polymerization inhibitor, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. Examples of the polymerization inhibitor include hydroquinones having a substituent such as hydroquinone and alkyl ether; catechols having a substituent such as alkyl ether, such as butylcatechol; radical scavengers such as pyrogallols and 2,2,6,6-tetramethyl-1-piperidinyloxy radical; thiophenols; β-naphthylamines and β-naphthols. 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 inhibitors can be used alone or in combination of two or more kinds.

Furthermore, the photopolymerization initiator can be made highly sensitive by using a photosensitizer. Examples of photosensitizers include xanthones such as xanthone and thioxanthone; anthracenes having a substituent such as anthracene and alkyl ether; phenothiazine; and rubrene. Photosensitizers can 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, relative to 100 parts by mass of the polymerizable liquid crystal compound.

A leveling agent is an additive that has the function of adjusting the fluidity of a polymerizable liquid crystal composition and making the layer obtained by applying the composition flatter. Examples include silicone-based leveling agents such as silane coupling agents, polyacrylate-based leveling agents, and perfluoroalkyl-based leveling agents. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all manufactured by Dow Corning Toray Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001, KBM-1003, KBE-1003, KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KBM-1403, KBM-502, KBM- 503, KBE-502, KBE-503, KBM-5103, KBM-602, KBM-603, KBM-903, KBE-903, KBE-9103, KBM-573, KBM-575, KBE-585, KBM-802, KBM-802, KBM-803, KBE-846, KBE-9007 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all manufactured by Momentive Performance Materials, Inc.) Japan LLC), Fluorinert (registered trademark) FC-72, FC-40, FC-43, FC-3283 (all manufactured by Sumitomo 3M Limited), Megafac (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-477, F-479, F-482, F-483 (all manufactured by DIC Corporation), F-top (trade name) EF301, EF303, Examples of the leveling agents include EF351, EF352 (all manufactured by Mitsubishi Materials Electronics Co., Ltd.), Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, and SA-100 (all manufactured by AGC Seimi Chemical Co., Ltd.), trade names E1830 and E5844 (manufactured by Daikin Fine Chemical Research Institute Co., Ltd.), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all trade names manufactured by BM Chemie Co., Ltd.). The leveling agents can be used alone or in combination of two or more kinds.

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, relative to 100 parts by mass of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, the obtained horizontally aligned liquid crystal cured film tends to be smoother, which is preferable.

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

The horizontally aligned liquid crystal cured film can be obtained by applying the polymerizable liquid crystal composition onto a horizontal alignment film described later, then removing the solvent, and curing the polymerizable liquid crystal composition containing the aligned polymerizable liquid crystal compound by heating and/or active energy rays.

Methods for applying the polymerizable liquid crystal composition onto the horizontal alignment film (hereinafter sometimes referred to as application method A) include, for example, extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, slit coating, microgravure, die coating, and inkjet methods. Other examples include methods of applying using a coater such as a dip coater, bar coater, or spin coater. Among these, when applying continuously in a roll-to-roll format, the application methods of the microgravure, inkjet, slit coating, and die coating are preferred.

Methods for removing the solvent (hereinafter sometimes referred to as solvent removal method A) include, for example, natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations of these. Of these, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, and even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 20 minutes, and more preferably 30 seconds to 10 minutes.

The active energy rays to be irradiated are appropriately selected according to the type of polymerizable liquid crystal compound (particularly the type of photopolymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator if a photopolymerization initiator is included, and the amount of each. Specifically, one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays can be mentioned. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization devices that are widely used in this field can be used, and it is preferable to select the type of polymerizable liquid crystal compound so that it can be photopolymerized by ultraviolet light.

Examples of light sources for the active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The ultraviolet irradiation intensity is usually 10 to 3,000 mW/ ^cm2 . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute.
When irradiated once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ/cm ² , preferably 50 to 2,000 mJ/cm ² , and more preferably 100 to 1,000 mJ/cm ² . If the cumulative light amount is below the lower limit, the polymerizable liquid crystal compound may not be cured sufficiently, and good transferability may not be obtained. Conversely, if the cumulative light amount is above the upper limit, the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film may become colored.

From the viewpoint of thinning the functional film, the thickness of the horizontally aligned liquid crystal cured film is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 2.5 μm or less. The lower limit of the thickness of the horizontally aligned liquid crystal cured film is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even 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 control force that aligns the polymerizable liquid crystal compound of the liquid crystal cured film in a predetermined direction. In addition, various alignments such as vertical alignment, horizontal alignment, hybrid alignment, and tilt alignment can be controlled depending on the type of alignment film, rubbing conditions, and light irradiation conditions. Among these, the horizontal alignment film is an alignment film having an alignment control force that aligns the polymerizable liquid crystal compound of the liquid crystal cured film in the horizontal direction. Therefore, by using the horizontal alignment film, a horizontally aligned liquid crystal film can be formed.

The alignment film is preferably solvent-resistant so that it does not dissolve the polymerizable liquid crystal composition when applied, and is also heat-resistant to remove the solvent and during heat treatment to align the polymerizable liquid crystal compound.

Examples of horizontal alignment films that exhibit an alignment control force that aligns the horizontally aligned liquid crystal cured film in the horizontal direction include rubbed alignment films, photo-aligned films, and groove alignment films that have an uneven pattern or multiple grooves on the surface. For example, when applied to a long rolled film, a photo-aligned film is preferred because the alignment direction can be easily controlled.

A rubbed alignment film is usually formed by applying a composition containing an alignment polymer and a solvent (hereinafter also referred to as a rubbed alignment film forming composition) onto a substrate or the like, removing the solvent to form a coating film, and rubbing the coating film to impart an alignment control force.

Examples of oriented polymers include polyamides and gelatins having amide bonds, polyimides having imide bonds and their hydrolyzates such as polyamic acids, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic acid esters. These oriented polymers can be used alone or in combination of two or more.

The concentration of the alignment polymer in the composition for forming the rubbing alignment film may be within a range in which the alignment polymer is completely dissolved in the solvent. The content of the alignment 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.

Compositions for forming rubbing alignment films are available on the market. Commercially available products include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

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

One example of a rubbing method is to bring the coating film into contact with a rotating rubbing roll wrapped with a rubbing cloth. If masking is used during the rubbing process, multiple regions (patterns) with different orientation directions can be formed on the alignment film.

Photo-alignment films are usually obtained by applying a composition (also called a photo-alignment film-forming composition) containing a polymer or monomer having a photoreactive group and a solvent onto a substrate or the like, removing the solvent, and then irradiating the substrate with polarized light (preferably polarized UV). The direction of the alignment control force of the photo-alignment film can be freely controlled by selecting the polarization direction of the polarized light to be irradiated.

The photoreactive group refers to a group that generates an alignment ability when irradiated with light. Specific examples include groups involved in photoreactions that are the source of alignment ability, such as molecular alignment-inducing reactions, isomerization reactions, photodimerization reactions, photocrosslinking reactions, or photodecomposition reactions, which are generated by irradiation with light. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferred, 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 preferred.

Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

Groups involved in photodimerization reactions or photocrosslinking reactions are preferred because of their excellent alignment properties. Among these, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl groups and chalcone groups are preferred because they require a relatively small amount of polarized light irradiation for alignment and are easy to obtain a photoalignment film that is excellent in thermal stability and stability over time. As polymers having photoreactive groups, those having cinnamoyl groups such that the terminals of the polymer side chains have a cinnamic acid structure or a cinnamic acid ester structure are particularly preferred.

The content of the polymer or monomer having a photoreactive group can be adjusted depending on the type of polymer or monomer and the desired thickness of the photoalignment film, and is preferably at least 0.2 parts by mass or more per 100 parts by mass of the composition for forming a photoalignment film, and more preferably in the range of 0.3 to 10 parts by mass.

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

To irradiate the polarized light, for example, the polarized light may be directly irradiated onto the composition for forming a photo-aligned film coated on a substrate or the like, from which the solvent has been removed. In addition, the polarized light is preferably substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) in the wavelength range of 250 to 400 nm is particularly preferred. Examples of light sources for irradiating the polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferred because they have a high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV can be irradiated by irradiating the light from the light source through an appropriate polarizing element. Examples of polarizing elements include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grids. Among these, wire-grid type polarizing elements are preferred from the viewpoints of large area and heat resistance.

When rubbing or polarized light irradiation is performed, masking can be used to form multiple regions (patterns) with different liquid crystal alignment directions.

A groove alignment film is a film that has a concave-convex pattern or multiple grooves on the film surface. When a polymerizable liquid crystal compound is applied to a film that has multiple equally spaced linear grooves, the liquid crystal molecules are oriented in the direction along the grooves.

Methods for obtaining a groove alignment film include a method in which the surface of a photosensitive polyimide film is exposed through an exposure mask having slits in a pattern shape, followed by development and rinsing to form an uneven pattern; a method in which a layer of uncured UV-cured resin is formed on a plate-shaped master having grooves on its surface, and the formed resin layer is transferred to a substrate or the like and then cured; and a method in which a roll-shaped master having multiple grooves is pressed against a film of uncured UV-cured resin formed on a substrate or the like to form unevenness, and then cured.

The compositions for forming horizontal alignment films, such as the composition for forming a rubbing alignment film and the composition for forming a photo-alignment film, can contain, in addition to a solvent, additives exemplified in the section on horizontal alignment liquid crystal cured films.

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

[Vertical alignment liquid crystal cured film]
The horizontally aligned liquid crystal cured film is a film having a refractive index anisotropy in a direction perpendicular to the film plane, and is made of a polymer containing a polymerizable liquid crystal compound. The vertically aligned liquid crystal cured film is preferably formed by applying a polymerizable liquid crystal composition onto the vertically aligned film and polymerizing the polymerizable liquid crystal composition containing the polymerizable liquid crystal compound in an aligned state by heating and/or light irradiation, in terms of being able to arbitrarily design the thinning and wavelength dispersion characteristics of the vertically aligned liquid crystal cured film.

The three-dimensional refractive index ellipsoid formed by the vertically 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 made of a polymer of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound in a state of being aligned in a direction perpendicular to the plane of the liquid crystal cured film, or may be a hybrid aligned liquid crystal cured film or an inclined aligned liquid crystal cured film. The refractive indexes nx, ny, and nz in three directions in 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 the principal refractive index 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. ny represents the refractive index in a direction parallel to the plane of the vertically aligned liquid crystal cured film and perpendicular to the direction of nx in the refractive index ellipsoid formed by the vertically aligned liquid crystal cured film. In addition, when nx=ny, nx can take any direction in the plane of the vertically aligned liquid crystal cured film. nz represents the refractive index in the direction perpendicular to the plane of the vertically aligned liquid crystal cured film in the index ellipsoid formed by the vertically aligned liquid crystal cured film.

The vertically aligned liquid crystal cured film can be made of either rod-shaped or disk-shaped polymerizable liquid crystal, but rod-shaped polymerizable liquid crystal is preferred. When rod-shaped polymerizable liquid crystal forms the 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 has a thickness direction retardation value RthC(λ) for light having a wavelength of λ nm that satisfies the optical characteristics shown in the following formula (31). It is also preferable that the vertically aligned liquid crystal cured film satisfies the optical characteristics shown in the following formulas (32) and (33). It is more preferable that the vertically aligned liquid crystal cured film satisfies the optical characteristics shown in the following formulas (31), (32), and (33).
−100 nm≦RthC(550)≦−50 nm (31)
(In the formula, RthC(550) represents a retardation value in the thickness direction for light having a wavelength of 550 nm.
)
RthC(450)/RthC(550)≦1.0 (32)
1.00≦RthC(650)/RthC(550) (33)
(In the formula, RthC(450) represents a retardation value in the thickness direction for light having a wavelength of 450 nm, RthC(550) represents a retardation value in the thickness direction for light having a wavelength of 550 nm, and RthC(650) represents a retardation value in the thickness direction for light having a wavelength of 650 nm.)

If the thickness-direction retardation value RthC(550) of the vertically aligned liquid crystal cured film exceeds the range of formula (31), the display using an elliptical polarizer with optical compensation function including a retardation plate with optical compensation function may have a problem of reddish or bluish hue in the oblique direction. A more preferable range of the thickness-direction retardation value is -95 nm ≦ RthC(550) ≦ -55 nm, and an even more preferable range is -90 nm ≦ RthC(550) ≦ -60 nm. If the "RthC(450)/RthC(550)" of the vertically aligned liquid crystal cured film exceeds 1.0, the ellipticity of the elliptical polarizer having the vertically aligned liquid crystal cured film when viewed obliquely on the short wavelength side deteriorates. If the ellipticity of the elliptical polarizer deteriorates on the short wavelength side and becomes smaller than 1.0, the function of the elliptical polarizer on the short wavelength side tends to be impaired. "RthC(450)/RthC(550)" is preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and even more preferably 0.79 to 0.85.

The thickness retardation value of the vertically aligned liquid crystal cured film can be adjusted by the thickness of the vertically aligned liquid crystal cured film. Since the thickness retardation value is determined by the following formula (34), the three-dimensional refractive index and film thickness dC can be adjusted to obtain a desired thickness retardation value (RthC(λ): thickness retardation value of the vertically aligned liquid crystal cured film at wavelength λ (nm)). The three-dimensional refractive index depends on the molecular structure and orientation of the polymerizable liquid crystal compound described later.
RthC(λ)=[(nxC(λ)+nyC(λ))/2−nzC(λ)]×dC (34)
(In the formula, the relationship of nzC(λ)>nxC(λ)≈nyC(λ) is satisfied in the index ellipsoid formed by the vertically aligned liquid crystal cured film, where nzC(λ) represents the refractive index in a direction perpendicular to the plane of the vertically aligned liquid crystal cured film for light of wavelength λ (nm) in the index ellipsoid formed by the vertically aligned liquid crystal cured film. nxC(λ) represents the maximum refractive index in a direction parallel to the plane of the vertically aligned liquid crystal cured film for light of wavelength λ (nm) in the index ellipsoid formed by the vertically aligned liquid crystal cured film. nyC(λ) represents the refractive index in a direction parallel to the plane of the vertically aligned liquid crystal cured film and perpendicular to the direction of nxC for light of wavelength λ (nm) in the index ellipsoid formed by the vertically aligned liquid crystal cured film. However, when nxC(λ)=nyC(λ), nxC(λ) represents the 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 a 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 refers to a group that can participate in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase order structure may be a nematic liquid crystal or a smectic liquid crystal.

The polymerizable liquid crystal compound used to form the vertically aligned liquid crystal cured film is preferably a compound represented by the above formula (I). By using the compound represented by formula (I), reverse wavelength dispersion is exhibited, and the relationship between (31) and (32) can be satisfied.

The polymerizable liquid crystal compound used in the vertically aligned liquid crystal cured film can be used alone or in combination of two or more. When two or more types are used in combination, the content of the compound represented by formula (I) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, per 100 parts by mass of the polymerizable liquid crystal compound.

The composition for forming the vertically aligned liquid crystal cured film (hereinafter also referred to as the 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 improver. These additives may be used alone or in combination of two or more kinds.

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. If the content is within the above range, the alignment of the vertically aligned liquid crystal cured film tends to be high. Here, the solid content refers to the total amount of components excluding the solvent from the composition.

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

The content of the solvent is preferably 50 to 98 parts by weight, more preferably 70 to 95 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal composition. Therefore, the solid content per 100 parts by weight of the composition is preferably 2 to 50 parts by weight. If the solid content of the composition is 50 parts by weight or less, the viscosity of the composition is low, so that the thickness of the vertically aligned liquid crystal cured film becomes approximately uniform, and unevenness tends to be less likely to occur in the vertically aligned liquid crystal cured film. The above solid content can be appropriately determined taking into consideration the thickness of the vertically aligned liquid crystal cured film to be produced.

A polymerization initiator is a compound that generates reactive species by the contribution of heat or light and can initiate a polymerization reaction of polymerizable liquid crystals and the like. Examples of reactive species include active species such as radicals, cations, and anions. Among them, photopolymerization initiators in which the reaction proceeds by irradiation with light are preferred from the viewpoint of ease of reaction control. As the photopolymerization initiator, the same initiators as those used in the composition for forming a horizontally aligned liquid crystal cured film can be used.

The amount of 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. Within the above range, the reaction of the polymerizable group proceeds sufficiently, and the orientation of the polymerizable liquid crystal compound is unlikely to be disturbed.

By adding a polymerization inhibitor, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. As the polymerization inhibitor, the same one as that used in 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 alignment 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 can be used alone or in combination of two or more kinds.

Furthermore, the photopolymerization initiator can be made highly sensitive by using a photosensitizer. The photosensitizer may be the same as that used in the composition for forming a horizontally aligned liquid crystal cured film. 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, relative to 100 parts by mass of the polymerizable liquid crystal compound.

A leveling agent is an additive that adjusts the fluidity of a polymerizable liquid crystal composition and makes the layer obtained by applying the composition flatter. The same leveling agent as that used in 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, relative to 100 parts by mass of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, the obtained vertically aligned liquid crystal cured film tends to be smoother, which is preferable.

The polymerizable liquid crystal composition used to form the vertically aligned liquid crystal cured film can be obtained by stirring the polymerizable liquid crystal compound and components other than the polymerizable liquid crystal compound, such as additives, at a predetermined temperature.

The vertically aligned liquid crystal cured film can be obtained by applying the polymerizable liquid crystal composition onto a vertical alignment film described later, then removing the solvent, and curing the polymerizable liquid crystal composition containing the aligned polymerizable liquid crystal compound by heating and/or active energy rays.

The method for applying the polymerizable liquid crystal composition onto the vertical alignment film can be the same as that used for forming the horizontal alignment liquid crystal cured film.

The method for removing the solvent can be the same as that used to form the horizontally aligned liquid crystal cured film.

The active energy rays to be irradiated are appropriately selected according to the type of polymerizable liquid crystal compound (particularly the type of photopolymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator if a photopolymerization initiator is included, and the amount of each. Specifically, one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays can be mentioned. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization devices that are widely used in this field can be used, and it is preferable to select the type of polymerizable liquid crystal compound so that it can be photopolymerized by ultraviolet light.

The light source of the active energy rays can be the same as that used when forming the horizontally aligned liquid crystal cured film.

The ultraviolet irradiation intensity is usually 10 to 3,000 mW/ ^cm2 . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute.
When irradiated once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ/cm ² , preferably 50 to 2,000 mJ/cm ² , and more preferably 100 to 1,000 mJ/cm ² . If the cumulative light amount is below the lower limit, the polymerizable liquid crystal compound may not be cured sufficiently, and good transferability may not be obtained. On the other hand, if the cumulative light amount is above the upper limit, the retardation plate with optical compensation function including the vertically aligned liquid crystal cured film may be colored.

From the viewpoint of thinning the functional film, the thickness of the vertically aligned liquid crystal cured film is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 1.5 μm or less. The lower limit of the thickness of the vertically aligned liquid crystal cured film is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even 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 control force that aligns the polymerizable liquid crystal compound of the liquid crystal cured film in a predetermined direction. In addition, various alignments such as vertical alignment, horizontal alignment, hybrid alignment, and tilt alignment can be controlled depending on the type of alignment film, rubbing conditions, and light irradiation conditions. Among these, the vertical alignment film is an alignment film having an alignment control force that aligns the polymerizable liquid crystal compound of the liquid crystal cured film in the vertical direction. Therefore, by using the vertical alignment film, a vertically aligned liquid crystal film can be formed.

As the vertical alignment film, it is preferable to apply a material that reduces the surface tension of the surface of the substrate or the like. Such materials include the above-mentioned alignment polymers, such as polyimide, polyamide, their hydrolyzates such as polyamic acid, fluorine-based polymers such as perfluoroalkyl, silane compounds, and polysiloxane compounds obtained by condensation reactions of these. The vertical alignment film can be obtained by applying a composition containing such a material and a solvent, such as the solvent exemplified in the section on vertical alignment liquid crystal film (hereinafter also referred to as a composition for forming a vertical alignment film), onto the substrate or the like, removing the solvent, and then subjecting the applied film to heating or the like.

When a silane compound is used for the vertical alignment film, the vertical alignment film is preferably a film made of a compound containing Si and C as constituent elements, and a silane compound can be suitably used, from the viewpoint of easily reducing the surface tension and easily increasing the adhesion with the layer adjacent to the vertical alignment film. In the present invention, when the vertical alignment film is disposed between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, high adhesion is exhibited between the vertical alignment film and the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film, and peeling at the interface between each layer in the retardation plate with optical compensation function can be effectively suppressed or prevented.

As the silane compound, silicone-based compounds such as the above-mentioned silane coupling agents can be suitably used, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 3-glycidoxypropyltrimethoxysilane, Examples include 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane.

The silane compound may be of the silicone monomer type or of the silicone oligomer (polymer) type. When the silicone oligomer is expressed in the form of a (monomer)-(monomer) copolymer, copolymers containing a mercaptopropyl group, such as 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer, copolymers containing a mercaptomethyl group, such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer, copolymers containing a mercaptomethyl group, such as 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, methacryloyloxypropyl group-containing copolymers such as 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxy ...methoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyl copolymers containing acryloyloxypropyl groups, such as triethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinyl group-containing copolymers such as vinyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer; amino group-containing copolymers such as 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-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 compounds can be used alone or in combination of two or more. Silane coupling agents, which may also be used as leveling agents, can also be used.

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

From the viewpoint of improving adhesion, the applicability of the composition for forming a vertically aligned liquid crystal cured film, and the viewpoint of preventing the layer disposed below from dissolving in the manufacturing method of a retardation plate with optical compensation function described later, the vertically aligned film is preferably a film made of a compound containing Si, C, and O as constituent elements. In addition, the number of carbon atoms of the substituent containing a C atom, preferably an alkyl group or an alkoxy group, which is bonded to the Si atom of the silane compound forming the vertically aligned film, is preferably 1 to 30, more preferably 2 to 25, and even 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 even more preferably 0.05 to 0.33. When the Si/C ratio is equal to or greater than the lower limit, the applicability of the composition for forming a vertically aligned liquid crystal cured film is improved, and when the Si/C ratio is equal to or less than the upper limit, the adhesion to the adjacent layer can be improved.

The solvent may be, for example, the solvents exemplified in the section on horizontally aligned liquid crystal cured film. The method for applying the composition for forming the vertically aligned film may be the application method A described above, and the method for removing the solvent may be the solvent removal method A described above.

The composition for forming the vertical alignment film may contain, in addition to the solvent, additives exemplified in the section on the horizontal alignment liquid crystal cured film.

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

〔Base material〕
The substrate is used when applying the composition for forming an alignment film or the composition for forming a liquid crystal cured film, and may be designed to transfer the film applied on the substrate by peeling off the substrate, or may be designed to be unable to transfer the film by providing adhesion to the substrate, but is preferably designed to transfer the film to a transferee and peel off the substrate from the viewpoint of thinning. Examples of the substrate as described above include glass substrates and film substrates, and film substrates are preferred from the viewpoint of processability, and long rolled films are more preferred from the viewpoint of continuous production. Examples of resins constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; plastics such as polyphenylene sulfide and polyphenylene oxide. The substrate surface may be subjected to a release treatment such as silicone treatment. Examples of commercially available cellulose ester substrates include "FUJITAC FILM" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by Konica Minolta Opto, Inc.). Such resins can be formed into a film by known means such as a solvent casting method or a melt extrusion method to form a substrate.

Commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Commercially available cyclic olefin resin substrates can also be used. Commercially available cyclic olefin resin substrates include "S-Cina" (registered trademark), "SCA40" (registered trademark) (all manufactured by Sekisui Chemical Co., Ltd.), "ZEONOR Film" (registered trademark) (manufactured by Optes Co., Ltd.), and "Arton Film" (registered trademark) (manufactured by JSR Corporation).

The substrate preferably has a thickness that allows easy lamination of the horizontal alignment liquid crystal cured film, horizontal alignment film, vertical alignment liquid crystal cured film, and vertical alignment film, and allows easy peeling. The thickness of such a substrate is usually 5 to 300 μm, and preferably 20 to 200 μm.

[Retardation plate with optical compensation function]
The retardation plate with optical compensation function of the present invention comprises a horizontal alignment liquid crystal cured film, a horizontal alignment film or a vertical alignment film, and a vertical alignment liquid crystal cured film in this order, and satisfies the following requirements (1) to (4).
The interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is 5 μm or less. ... (1)
A horizontal alignment film or a vertical alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film... (2)
The following relationship is satisfied: ReA(450)/ReA(550)<1.00
Satisfy the following: ... (3)
Here, ReA(λ) represents an in-plane retardation value of a horizontally aligned liquid crystal cured film at a wavelength of λ nm.
The phase difference value definition is as follows:
ReA(λ)=(nxA-nyA)×dA
Here, nxA is the principal refractive index in the film plane of the horizontally aligned liquid crystal cured film, nyA is the refractive index in the direction perpendicular to nxA in the same plane, and dA is the film thickness of the horizontally aligned liquid crystal cured film.
The following relationship: RthC(450)/RthC(550)<1.00
Satisfy the following: ... (4)
Here, RthC(λ) represents a retardation value in the thickness direction of the vertically aligned liquid crystal cured film at a wavelength of λ nm. The retardation value is defined as follows.
RthC(λ)=((nxC+nyC)/2-nzC)×dC
Here, nxC is the principal refractive index in the film plane of the vertically aligned liquid crystal cured film, nyC is the refractive index in the direction perpendicular to nxC in the same plane, nzC is the refractive index in the thickness direction of the vertically aligned liquid crystal cured film, and dC is the film thickness of the vertically aligned liquid crystal cured film.

When nxC=nyC, nxC can be the refractive index in any direction within the film plane.
The interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is 5 μm or less as shown in formula (1), but is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. The thickness of the horizontally aligned film is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and particularly preferably 30 nm or more.

It is preferable that the retardation plate with optical compensation function satisfies the following relational expression (5). The smaller the value of |R0(550)-R40(550)|, the better, because the amount of light leakage at an oblique wavelength of around 550 nm is reduced when an elliptical polarizing plate with optical compensation function using the retardation plate with optical compensation function is applied to a display. The value of |R0(550)-R40(550)| is preferably less than 10 nm, more preferably 5 nm or less, even more preferably 3 nm or less, and particularly preferably 2 nm or less.
|R0(550)-R40(550)|<10 nm ... (5)
Here, R0(λ) represents the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and R40 represents the apparent retardation value when the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane.

It is preferable that the retardation plate with optical compensation function satisfies the following relational expression (6). The smaller the value of |R0(450)-R40(450)|, the better, because the amount of light leakage at an oblique wavelength of around 450 nm is reduced when an elliptical polarizing plate with optical compensation function using the retardation plate with optical compensation function is applied to a display. The value of |R0(450)-R40(450)| is preferably less than 10 nm, more preferably 5 nm or less, even more preferably 3 nm or less, and particularly preferably 2 nm or less.
|R0(450)-R40(450)|<10 nm ... (6)
Here, R0(λ) represents the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and R40 represents the apparent retardation value when the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane.

Furthermore, it is preferable that the difference between the values represented by the relational expressions (5) and (6) satisfies the following relational expression (7).
|{R0(450)-R40(450)}-{R0(550)-R40(550)}|<3 nm ... (7)
When the relational expression (7) is satisfied, the hue of the reflection in the front and oblique directions becomes close to black when an elliptical polarizing plate with optical compensation function using a retardation plate with optical compensation function is applied to a display. Therefore, the value of (7) is preferably 3 nm or less, more preferably 2 nm or less, and even more preferably 1 nm or less.

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

Specifically, the difference in the average refractive index of each layer is
(1) The difference between the average refractive index of a cured film of a horizontally aligned liquid crystal and the average refractive index of a cured film of a vertically aligned liquid crystal,
(2) In the case where a horizontal alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment 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) When a vertical alignment film is included between the horizontal alignment liquid crystal cured film and the vertical alignment 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 vertical alignment film and the average refractive index of the cured film of the vertical alignment liquid crystal,
etc.

The retardation plate with optical compensation function of the present invention can include layers other than the horizontal alignment liquid crystal cured film, the horizontal alignment film, the vertical alignment liquid crystal cured film, and the vertical alignment film, and specific examples thereof include other alignment liquid crystal cured films, other alignment films, protective layers, etc. Examples of other alignment liquid crystal cured films include the vertical alignment liquid crystal cured film and the horizontal alignment liquid crystal cured film exemplified above, and examples of other alignment films include the alignment films exemplified above.

The protective layer is preferably formed from a protective layer-forming composition that contains a water-soluble polymer, such as an acrylic oligomer or polymer made of a multifunctional acrylate (methacrylate), urethane acrylate, polyester acrylate, or epoxy acrylate, polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinylpyrrolidone, starches, methyl cellulose, carboxymethyl cellulose, or sodium alginate, and a solvent.

The solvent contained in the composition for forming the protective layer may be the same as the solvent exemplified above. Among them, at least one solvent selected from the group consisting of water, alcohol solvents, and ether solvents is preferred in that it does not dissolve the layer that forms the protective layer. Examples of the alcohol solvent include methanol, ethanol, butanol, ethylene glycol, isopropyl alcohol, 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, isopropyl alcohol, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate are preferred.

The thickness of the protective layer is preferably 0.1 μm to 10 μm, and more preferably 0.1 μm to 3 μm.
[Method of manufacturing a retardation plate with optical compensation function]

The method for manufacturing the retardation plate with optical compensation function of the present invention is not particularly limited as long as it is a method that can laminate the horizontal alignment film, the horizontal alignment film or the vertical alignment film, and the vertical alignment liquid crystal cured film in this order, but a method of laminating a horizontal alignment film on a substrate, then laminating a horizontal alignment liquid crystal cured film, further laminating a vertical alignment film, and then laminating a vertical alignment liquid crystal cured film (hereinafter referred to as manufacturing method A), or a method of laminating a vertical alignment film on a substrate, then laminating a vertical alignment liquid crystal cured film, further laminating a horizontal alignment film, and then laminating a horizontal alignment liquid crystal cured film (hereinafter referred to as manufacturing method B) is preferable. The lamination method of the horizontal alignment liquid crystal cured film, the horizontal alignment film, the vertical alignment liquid crystal cured film, and the vertical alignment film can use the formation method of each layer described above.

When a retardation plate with optical compensation function is manufactured by manufacturing method A or manufacturing method B, alignment defects or alignment defects may occur due to the orientation of the liquid crystal cured film arranged in the lower layer. That is, in the case of manufacturing method A, a horizontally aligned liquid crystal cured film is laminated on the lower layer, and then a vertically aligned liquid crystal cured film is laminated, so that alignment defects or alignment defects may occur due to the influence of the horizontally aligned liquid crystal cured film in the lower layer when forming the vertically aligned liquid crystal cured film. In the case of manufacturing method B, a vertically aligned liquid crystal cured film is laminated on the lower layer for the same purpose, and then a horizontally aligned liquid crystal cured film is laminated, so that alignment defects or alignment defects may occur due to the influence of the vertically aligned liquid crystal cured film in the lower layer when forming the horizontally aligned liquid crystal cured film. For this reason, depending on the type of solvent of the composition (composition for forming a horizontally aligned film, composition for forming a horizontally aligned liquid crystal cured film, composition for forming a vertically aligned film, composition for forming a vertically aligned liquid crystal cured film) used to form each layer to be laminated, the lower layer may be dissolved, causing changes in optical properties, alignment defects, alignment defects, etc. Therefore, the materials, solvents, solid content concentration, coating method, film thickness, etc. contained in the composition used to form each layer to be laminated must be appropriately selected.

[Elliptical polarizing plate with optical compensation function]
The retardation plate with optical compensation function of the present invention can be attached to a transferee and transferred by peeling off the substrate, or laminated with the substrate through an adhesive or the like, thereby imparting the function of the retardation plate with optical compensation function, i.e., its optical properties, to the transferee, and an optical laminate imparted with the optical properties of the retardation plate with optical compensation function can be produced. Among these, when laminated with a polarizing plate, it is possible to produce an elliptical polarizing plate with optical compensation function. In an embodiment of the present invention, it is preferable to laminate the retardation plate so that the slow axis (optical axis) of the horizontally aligned liquid crystal cured film and the absorption axis of the polarizing plate are substantially 45°. By laminating the retardation plate so that the slow axis (optical axis) of the optical film of the present invention and the absorption axis of the polarizing plate are substantially 45°, the function as a circular polarizing plate can be obtained. Note that substantially 45° is usually in the range of 45±5°.

[Transfer recipient]
Examples of the transfer target include single-layer optical films, such as polarizing plates, retardation plates, brightness-enhancing films, anti-glare films, anti-reflection films, diffusion films, and light-collecting films, and multilayer optical films, such as retardation plates and elliptical polarizing plates, among which retardation plates, retardation plates, polarizing plates, and elliptical polarizing plates can be preferably used. The optical laminate of the present invention can be used in image display devices, such as liquid crystal display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, electron emission display devices (field emission display devices (FEDs, etc.), surface field emission display devices (SEDs)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (grating light valve (GLV) display devices, display devices having digital micromirror devices (DMDs), etc.), and piezoelectric ceramic displays, and can be particularly preferably used in organic EL display devices and touch panel display devices.

[Polarizer]
The polarizing plate is made of a polarizer having a polarizing function. Examples of the polarizer include a stretched film having a dye with anisotropic absorption adsorbed thereon, and a film having a dye with anisotropic absorption coated and oriented thereon. Examples of the dye with anisotropic absorption include a dichroic dye.

A stretched film having a dye with anisotropic absorption is usually manufactured through a process of uniaxially stretching a polyvinyl alcohol resin film, a process of dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye, a process of treating the polyvinyl alcohol resin film with the dichroic dye adsorbed thereon with an aqueous boric acid solution, and a process of washing with water after the treatment with the aqueous boric acid solution. A polarizing plate is obtained by laminating the polarizer thus obtained and a transparent protective film. Examples of dichroic dyes include iodine and dichroic organic dyes. Examples of dichroic organic dyes include dichroic direct dyes made of disazo compounds such as C.I. DIRECT RED 39, and dichroic direct dyes made of compounds such as trisazo and tetrakisazo. As described above, the thickness of the polarizer obtained by uniaxially stretching a polyvinyl alcohol resin film, dyeing with a dichroic dye, treating with boric acid, washing with water, and drying is preferably 5 μm to 40 μm.

[Adhesive]
Examples of the adhesive include pressure-sensitive adhesives, drying-hardening adhesives, and chemically reactive adhesives. Examples of the chemically reactive adhesive include active energy ray-curing adhesives.

Pressure-sensitive adhesives usually contain a polymer and may contain a solvent. Examples of polymers include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and the like. Among them, acrylic adhesives containing acrylic polymers are preferred because they have excellent optical transparency, moderate wettability and cohesive strength, excellent adhesion, and high weather resistance and heat resistance, and are less likely to lift or peel under conditions of heating or humidity.

As the acrylic polymer, a copolymer of a (meth)acrylate in which the alkyl group in the ester portion 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, is preferred.

Pressure-sensitive adhesives containing such copolymers are preferred because they have excellent adhesive properties and can be removed relatively easily after application to a substrate without leaving any adhesive residue on the substrate. The glass transition temperature of the acrylic polymer is preferably 25°C or lower, more preferably 0°C or lower. The mass average molecular weight of such an acrylic polymer is preferably 100,000 or higher.

Examples of the solvent include the solvents listed above. The pressure-sensitive adhesive may contain a light diffusing agent. The light diffusing agent is an additive that imparts light diffusibility to the adhesive, and may be fine particles having a refractive index different from that of the polymer contained in the adhesive. Examples of the light diffusing agent include fine particles made of inorganic compounds and fine particles made of organic compounds (polymers). Many of the polymers contained as active ingredients in adhesives, including acrylic polymers, have a refractive index of about 1.4 to 1.6, so it is preferable to appropriately select a light diffusing agent from among those having a refractive index of 1.2 to 1.8. The difference in refractive index between the polymer contained as an active ingredient in the adhesive and the light diffusing agent is usually 0.01 or more, and from the viewpoint of the brightness and displayability of the display device, it is preferable that it is 0.01 to 0.2. The fine particles used as the light diffusing agent are preferably spherical fine particles, and more preferably fine particles close to monodispersion, and more preferably fine particles having an average particle size of 2 to 6 μm. The refractive index is measured by a general minimum deviation method or Abbe refractometer.

Examples of inorganic compound particles include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of organic compound (polymer) particles include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate/styrene copolymer resin beads (refractive index 1.50-1.59), 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 3-30 parts by mass per 100 parts by mass of the polymer.

The thickness of the pressure-sensitive adhesive is not particularly limited as it is determined according to its adhesion strength, but is usually 1 μm to 40 μm. From the standpoint of processability, durability, etc., the thickness is preferably 3 μm to 25 μm, and more preferably 5 μm to 20 μm. By making the thickness of the adhesive layer formed from the adhesive 5 μm to 20 μm, it is possible to maintain brightness when the display device is viewed from the front or at an angle, and to reduce the occurrence of bleeding or blurring of the displayed image.

The dry-setting adhesive may contain a solvent. Examples of the dry-setting adhesive include a polymer of a monomer having a protonic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group, or a composition containing a urethane polymer as the main component and further containing a crosslinking agent or a curing compound such as a polyaldehyde, an epoxy compound, an epoxy resin, a melamine compound, a zirconia compound, or a zinc compound. Examples of the polymer of a monomer having a protonic 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 polyvinyl alcohol resins include polyvinyl alcohol, partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. The content of polyvinyl alcohol resin in the water-based pressure-sensitive adhesive is usually 1 to 10 parts by mass, and preferably 1 to 5 parts by mass, per 100 parts by mass of water.

The urethane resin may be a polyester ionomer type urethane resin.
The polyester ionomer urethane resin referred to here is a urethane resin having a polyester skeleton, into which a small amount of ionic component (hydrophilic component) is introduced. The ionomer urethane resin can be emulsified in water without using an emulsifier to form an emulsion, and can be used as a water-based adhesive. When using a polyester ionomer urethane resin, it is effective to add a water-soluble epoxy compound as a crosslinking agent.

Epoxy resins include polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines obtained by reacting polyalkylene polyamines such as diethylenetriamine or triethylenetetramine with dicarboxylic acids such as adipic acid. Commercially available products of such polyamide epoxy resins include "Sumirez Resin (registered trademark) 650" and "Sumirez Resin 675" (both manufactured by Sumika Chemtex Corporation) and "WS-525" (manufactured by Nippon PMC Corporation). When epoxy resins are blended, the amount added is usually 1 to 100 parts by mass, and preferably 1 to 50 parts by mass, per 100 parts by mass of polyvinyl alcohol resin.

The thickness of the adhesive layer formed from the dry-solidifying adhesive is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 0.5 μm. If the adhesive layer formed from the dry-solidifying adhesive is too thick, it is likely to result in poor appearance.

The active energy ray curable adhesive may contain a solvent. The active energy ray curable adhesive is an adhesive that cures when irradiated with active energy rays. Examples of active energy ray curable adhesives include cationic polymerizable adhesives that contain an epoxy compound and a cationic polymerization initiator, radical polymerizable adhesives that contain an acrylic curing component and a radical polymerization initiator, adhesives that contain both a cationic polymerizable curing component such as an epoxy compound and a radical polymerizable curing component such as an acrylic compound, and further contain a cationic polymerization initiator and a radical polymerization initiator, and adhesives that do not contain these polymerization initiators and are cured by irradiation with an electron beam.

Among them, a radically polymerizable active energy ray curable adhesive containing an acrylic curing component and a photoradical polymerization initiator, and a cationic polymerizable active energy ray curable adhesive containing an epoxy compound and a photocationic polymerization initiator are preferred. Examples of the acrylic curing component include (meth)acrylates such as methyl (meth)acrylate and hydroxyethyl (meth)acrylate, and (meth)acrylic acid. An 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.

The photoradical polymerization initiator and photocationic polymerization initiator include the above-mentioned photoradical polymerization initiator and photocationic polymerization initiator. The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 to 20 parts by mass, and 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 trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow control agent, a plasticizer, and an antifoaming agent.

In this specification, active energy rays are defined as energy rays that can decompose a compound that generates active species to generate active species. Examples of such active energy rays include visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, γ-rays, and electron beams, with ultraviolet light and electron beams being preferred. The preferred conditions for ultraviolet light irradiation are the same as those for the polymerization of the polymerizable liquid crystal compound described above.

The present invention will be described in more detail below with reference to examples. In the examples, "%" and "parts" mean mass % and mass parts unless otherwise specified. In the following examples, the film thickness was measured using an ellipsometer M-220 manufactured by JASCO Corporation, or a contact film thickness meter (Nikon MH-15M, Counter TC101, MS-5C). The retardation value Rth (λ) in the thickness direction, the in-plane retardation value Re (λ), and the apparent retardation value R40 (λ) measured from the 40° direction were measured and calculated using a KOBRA-WPR manufactured by Oji Scientific Instruments Co., Ltd., or an ellipsometer M-220 manufactured by JASCO Corporation. The Si/C ratio can be calculated from elemental analysis of the vertical alignment film, measurement of surface constituent elements using X-ray photoelectric spectroscopy, or calculated from the structural formula when all the structural formulas of the compounds used to form the vertical alignment film are known. The corona treatment device used was AGF-B10 manufactured by Kasuga Electric Co., Ltd. Corona treatment can be carried out as appropriate when applying the composition to a substrate. It was carried out once using the corona treatment device described above, with an output of 0.3 kW and a treatment speed of 3 m/min.

[Example 1]
[Preparation of composition for forming horizontal alignment film]
5 parts of a photo-alignment material (weight average molecular weight: 30,000) having the following structure and 95 parts of cyclopentanone (solvent) were mixed as components, and the resulting mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a horizontal alignment film.

[Preparation of composition for forming vertical alignment film]
A silane coupling agent "KBE-9103" manufactured by Shin-Etsu Chemical Co., Ltd. was dissolved in a mixed solvent of ethanol and water in a ratio of 9:1 (mass ratio) to obtain a composition for forming a vertical alignment film with a solid content of 0.5%.

[Preparation of a composition for forming a horizontally aligned liquid crystal cured film and a composition for forming a vertically aligned liquid crystal cured film]
To a mixture of polymerizable liquid crystal compound A and 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 Corporation) and 6 parts of a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one ("Irgacure 369 (Irg369)", manufactured by BASF Japan Ltd.) were added.

Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80°C 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.

Polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Polymerizable liquid crystal compound B was produced in accordance with the method described in JP-A-2009-173893. The molecular structures of each compound are shown below.

[Polymerizable liquid crystal compound A]

[Polymerizable liquid crystal compound B]

[Manufacture of Polarizing Plate]
A polyvinyl alcohol film having an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more, and a thickness of 75 μm was immersed in pure water at 30° C., and then immersed in an aqueous solution having a mass ratio of iodine/potassium iodide/water of 0.02/2/100 at 30° C. to perform iodine dyeing (iodine dyeing step). The polyvinyl alcohol film that had undergone the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide/boric acid/water of 12/5/100 at 56.5° C. to perform boric acid treatment (boric acid treatment step). The polyvinyl alcohol film that had undergone the boric acid treatment step was washed with pure water at 8° C., and then dried at 65° C. to obtain a polarizer (thickness 27 μm after stretching) in which iodine was adsorbed and aligned in the polyvinyl alcohol. At this time, stretching was performed in the iodine dyeing step and the boric acid treatment step. The total stretching ratio in such stretching was 5.3 times. The obtained polarizer and a saponified triacetyl cellulose film (KC4UYTAC 40 μm, manufactured by Konica Minolta) were bonded together by nip rolls via a water-based adhesive. The resulting laminate was dried at 60° C. for 2 minutes while maintaining the tension at 430 N/m to obtain a polarizing plate having a triacetyl cellulose film as a protective film on one side. The water-based adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (Kuraray, “Kuraray Poval KL318”) and 1.5 parts of water-soluble polyamide epoxy resin (Sumika Chemtex, “Sumirez Resin 650”, an aqueous solution with a solid content of 30%) to 100 parts of water.

The optical properties of the obtained polarizing plate were measured. The measurements were performed using a spectrophotometer ("V7100", manufactured by JASCO Corporation) with the polarizer surface of the polarizing plate obtained above as the incident surface. The absorption axis of the polarizing plate was aligned with the stretching direction of the polyvinyl alcohol, and the luminous efficiency-corrected single transmittance of the obtained polarizing plate was 42.1%, the luminous efficiency-corrected polarization degree was 99.996%, the single hue a was -1.1, and the single hue b was 3.7.

[Production of a laminate consisting of a substrate, a horizontal alignment film, and a horizontal alignment liquid crystal cured film]
After performing corona treatment on a COP film (ZF-14-50) manufactured by Zeon Corporation, the composition for forming a horizontal alignment film was applied with a bar coater, dried at 80°C for 1 minute, and exposed to polarized UV light at a wavelength of 313 nm and an axial angle of 45° with an integrated light amount of 100 mJ/ ^cm2 using a polarized UV irradiation device ("SPOT CURE SP-9", manufactured by Ushio Inc.). The thickness of the obtained horizontal alignment film was measured with an ellipsometer and found to be 100 nm.

Next, a composition for forming a horizontally aligned liquid crystal cured film was applied to the horizontal alignment film using a bar coater, and dried at 120°C for 1 minute. After that, a high-pressure mercury lamp ("Unicur VB-15201BY-A", manufactured by Ushio Inc.) was used to irradiate with ultraviolet light (under a nitrogen atmosphere, integrated light amount at a wavelength of 365 nm: 500 mJ/cm ² ) to form a horizontally aligned liquid crystal cured film, thereby obtaining a laminate consisting of the substrate, the horizontal alignment film, and the horizontally aligned liquid crystal cured film. The thickness of the horizontally aligned liquid crystal cured film was measured with an ellipsometer to be 2.3 μm.

[Re measurement of horizontally aligned 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 device ("KOBRA-WPR", manufactured by Oji Scientific Instruments Co., Ltd.) after bonding to glass via an adhesive and peeling off the COP substrate. The results of measuring the retardation value ReA(λ) at each wavelength were ReA(450)=121 nm, ReA(550)=142 nm, ReA(650)=146 nm, and ReA(450)/ReA(550)=0.85.

[Production of a laminate consisting of 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 carrying out corona treatment on the laminate consisting of the substrate, the horizontal alignment film, and the horizontal alignment liquid crystal cured film produced by the above-mentioned method, the composition for forming the vertical alignment film was applied with a bar coater and dried for 1 minute at 80° C. to obtain a vertical alignment film. The thickness of the obtained vertical alignment film was measured with an ellipsometer and found to be 50 nm.

Further, a composition for forming a vertically aligned liquid crystal cured film was applied to the vertically aligned film using a bar coater, and dried at 120°C for 1 minute. Then, a high-pressure mercury lamp ("Unicur VB-15201BY-A", manufactured by Ushio Inc.) was used to irradiate with ultraviolet light (under a nitrogen atmosphere, integrated light quantity at a wavelength of 365 nm: 500 mJ/cm ² ) to form a vertically aligned liquid crystal cured film, thereby obtaining a laminate consisting of a substrate, a horizontally aligned film, a horizontally aligned liquid crystal cured film, a vertically aligned film, and a vertically aligned liquid crystal cured film. The thickness of the vertically aligned liquid crystal cured film was measured with an ellipsometer to be 1.2 μm. The interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was 50 nm. The constituent element ratio of the vertically aligned film was Si/C=0.33.

[Measurement of Rth of Cured Film of Vertically Aligned Liquid Crystal]
In order to measure the 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 in the same manner as above, and the vertically aligned liquid crystal cured film was attached to glass via an adhesive (Lintec Corporation pressure-sensitive adhesive 15 μm), and after confirming that there was no phase difference in the COP, the phase difference value was measured by changing the angle of incidence of light on the sample using an ellipsometer. In addition, the average refractive index at wavelengths λ of 450 nm and 550 nm was measured using a refractometer (manufactured by Atago Co., Ltd., "multi-wavelength Abbe refractometer DR-M4"). The obtained film thickness, average refractive index, and Re calculated from the measurement results of the ellipsometer were RthC (450) = -63 nm, RthC (550) = -73 nm, and RthC (450) / RthC (550) = 0.85, respectively.
[Measurement of R0 and R40 of a laminate (retardation plate with optical compensation function) consisting of a horizontally aligned liquid crystal cured film, a vertically aligned film, and a vertically aligned liquid crystal cured film]

The laminate consisting of the substrate, horizontal alignment film, horizontal alignment liquid crystal cured film, vertical alignment film, and vertical alignment liquid crystal cured film manufactured by the above method was attached to glass via an adhesive (15 μm pressure-sensitive adhesive manufactured by Lintec Corporation), and the COP was peeled off to prepare a measurement sample. After confirming that there was no phase difference in the horizontal alignment film and the vertical alignment film, the phase difference value R0 (λ) in the front direction of the optical compensation retardation plate and the phase difference value R40 (λ) when tilted 40° around the fast axis of the horizontal alignment liquid crystal cured film were measured using KOBRA-WPR. The results of calculating |R0(550)-R40(550)|, |R0(450)-R40(450)|, and |{R0(450)-R40(450)}-{R0(550)-R40(550)}| from the obtained R0(λ) and R40(λ) values are shown in Table 1.

[Difference in in-plane average refractive index of each layer]
Each layer was coated on glass according to the above method, and the average refractive index of each layer was calculated using a refractometer (manufactured by Atago Co., Ltd., "Multi-wavelength Abbe Refractometer DR-M4") or an ellipsometer, and it was confirmed that the difference in the in-plane average refractive index of each layer was 0.2 or less.

[Flexibility test]
A 0.7 mm thick glass plate was placed on the coating surface side of the laminate consisting of the substrate, horizontal alignment film, horizontal alignment liquid crystal cured film, vertical alignment film, and vertical alignment liquid crystal cured film prepared by the above method, and the laminate was bent 180 degrees so as to bend on the glass plate, and then the bent part was observed by transmitting the light of a fluorescent lamp using a 10x magnifying glass to confirm the presence or absence of wrinkles. The results are shown in Table 1.

[Check the reflective hue of the bent part]
After carrying out corona treatment on the coating surface side of the laminate consisting of the substrate, horizontal alignment film, horizontal alignment liquid crystal cured film, vertical alignment film, and vertical alignment liquid crystal cured film prepared by the above method, it was attached to a polarizing plate via an adhesive so that the angle between the absorption axis of the polarizing plate and the slow axis of the horizontal alignment film was 45°, and the substrate was peeled off to prepare an elliptical polarizing plate with optical compensation function. Then, it was attached to aluminum foil via an adhesive, bent 180° to the polarizing plate side with a radius of 1 cm, and the reflection hue of the bent part was visually observed. The results are shown in Table 1. The polarizing plate used in this test was prepared as follows.

(Examples 2 and 3)
A retardation plate with optical compensation function was prepared in the same manner as in Example 1, except that the thickness of the vertical alignment film was changed as shown in Table 1, and the retardation value was measured, a bending test was performed, and the reflection hue of the bending part was confirmed. The results are shown in Table 1.

Example 4
0.5% by weight of polyimide ("Sunever SE-610", manufactured by Nissan Chemical Industries, Ltd.), 72.3% by weight of N-methyl-2-pyrrolidone, 18.1% by weight of 2-butoxyethanol, 9.1% by weight of ethylcyclohexane, and 0.01% by weight of DPHA (manufactured by Shin-Nakamura Chemical Co., Ltd.) were mixed to prepare a composition B for forming a vertical alignment film. Except for using this composition B for forming a vertical alignment film, a retardation plate with an optical compensation function was prepared in the same manner as in Example 1, and retardation value measurement, bending test, and confirmation of reflection hue of the bending part were carried out. The results are shown in Table 1. The thickness of the vertical alignment film was measured with an ellipsometer and found to be 0.2 μm. From this, the interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was 0.2 μm. It was also confirmed that the vertical alignment film was invaded by the solvent during application of the composition for forming a vertically aligned liquid crystal cured film, causing partial alignment defects and alignment defects.

Example 5
A retardation plate with optical compensation function was produced in the same manner as in Example 1, except that the substrate was changed to a polyethylene terephthalate film (SP-PLR382050, manufactured by Lintec Corporation, hereinafter abbreviated as "separator") that had been subjected to a release treatment, and the stacking order was changed to a vertical alignment film, a vertically aligned liquid crystal cured film, a horizontal alignment film, and a horizontally aligned liquid crystal cured film, and the retardation value was measured, a bending test was performed, and the reflection hue of the bending portion was confirmed. The results are shown in Table 1. The thickness of the horizontal alignment film was measured with an ellipsometer and found to be 0.2 μm. From this, the interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film was found to be 0.2 μm. In addition,

(Comparative Example 1)
Except for changing the composition for forming a vertically aligned liquid crystal cured film to the composition for forming a vertically aligned liquid crystal cured film (B) described below, and changing the drying temperature after applying the composition for forming a vertically aligned liquid crystal cured film (B) from 120° C. to 80° C., a retardation plate with an optical compensation function was produced in the same manner as in Example 1, and the retardation value was measured, a bending test was performed, and the reflection hue of the bending part was confirmed. The results are shown in Table 1.

(Preparation of composition (B) for forming vertically aligned liquid crystal cured film)
To the liquid crystal compound LC242 described below: Paliocolor LC242 (registered trademark of BASF Corporation), 0.1 parts of leveling agent F-556 and 3 parts of polymerization initiator Irg369 were added, and cyclopentanone was added so that the solid content concentration became 13%, to obtain a composition (B) for forming a vertically aligned liquid crystal cured film. The obtained liquid crystal composition is called "composition V".
Liquid crystal compound LC242: Paliocolor LC242 (registered trademark of BASF Corporation)

(Comparative Example 2)
After producing a laminate of a horizontal alignment film and a horizontal alignment liquid crystal cured film 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 separately prepared on a COP by the same method as in Example. The obtained laminates were bonded together using an adhesive (15 μm pressure-sensitive adhesive manufactured by Lintec Corporation) to produce a retardation plate with optical compensation function. Retardation value measurement, bending test, and confirmation of reflection hue of the bending part were performed. The results are shown in Table 1.

It was found that the elliptical polarizing plate with optical compensation function, which uses the retardation plate with optical compensation function of Examples 1 to 5, exhibits less change in reflective hue at the bent portion when applied to a flexible display and bent.

Claims (8)

a horizontally aligned liquid crystal cured film in which a composition containing a polymerizable liquid crystal compound is cured in a state in which the composition is aligned in a horizontal direction relative to the film plane;
and a vertically aligned liquid crystal cured film obtained by curing a composition containing a polymerizable liquid crystal compound in a state where the composition is aligned in a vertical direction relative to the in-plane of the film,
The polymerizable liquid crystal compound includes a compound represented by the following formula (I):
A retardation plate with optical compensation function that satisfies the following relationships (1) to (4):
The interlayer distance between the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film is 0.5 μm or less. ... (1)
A vertical alignment film is included between a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, the horizontally aligned liquid crystal cured film, the vertically aligned film, and the vertically aligned liquid crystal cured film are adjacent to each other in this order, the vertical alignment film is a film made of a compound containing Si, C, and O as constituent elements, and the ratio of Si to C (Si/C, molar ratio) is 0.03 to 1.00 .
ReA(450)/ReA(550)<1.00...(3)
In the formula, ReA(λ) represents an in-plane retardation value at a wavelength of λ nm of the horizontally aligned liquid crystal cured film. The in-plane retardation value ReA(λ) is defined as follows.
ReA(λ)=(nxA(λ)-nyA(λ))×dA
Here, nxA(λ) is the principal refractive index in the film plane of the horizontally aligned liquid crystal cured film and is the principal refractive index for light of wavelength λ (nm), nyA(λ) is the refractive index in the direction perpendicular to nxA(λ) in the same plane and is the refractive index for light of wavelength λ (nm), and dA is the film thickness of the horizontally aligned liquid crystal cured film.
0.75≦RthC(450)/RthC(550)≦0.92 (4)
In the formula, RthC(λ) represents a retardation value in the thickness direction of the vertically aligned liquid crystal cured film at a wavelength of λ nm. The retardation value RthC(λ) is defined as follows.
RthC(λ)=((nxC(λ)+nyC(λ))/2-nzC(λ))×dC
Here, nxC(λ) is the principal refractive index in the film plane of the vertically aligned liquid crystal cured film and is the principal refractive index for light of wavelength λ (nm), nyC(λ) is the refractive index in the direction perpendicular to nxC(λ) in the same plane and is the refractive index for light of wavelength λ (nm), nzC(λ) is the refractive index in the thickness direction of the vertically aligned liquid crystal cured film and is the refractive index for light of wavelength λ (nm), and dC is the film thickness of the vertically aligned liquid crystal cured film.]

[In formula (I), Ar represents a divalent aromatic group which may have a substituent, and the divalent aromatic group contains at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom ;
L ¹ , L ² , B ¹ and B ² each independently represent a single bond or a divalent linking group;
k and l each independently represent an integer of 0 to 3, satisfying the relationship of 1≦k+l, and when 2≦k+l, B ¹ and B ² , and G ¹ and G ² may be the same as or different from each other,
^E1 and ^E2 each independently represent an alkanediyl group having 1 to 17 carbon atoms, a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and _-CH2- contained in the alkanediyl group may be substituted with -O-, -S- or -Si-;
^P1 and ^P2 each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group;
G ¹ and G ² each independently represent a 1,4-phenylenediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms.] 2. The retardation plate with optical compensation function according to claim 1, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (5):
|R0(550)-R40(550)|<10 nm ... (5)
[Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm). Also, R40(λ) is the apparent retardation value when rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane in the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the retardation value for light of wavelength λ (nm).] 3. The retardation plate with optical compensation function according to claim 1, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (6):
|R0(450)-R40(450)|<10 nm ... (6)
[Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm). Also, R40(λ) is the apparent retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film when rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane, and indicates the retardation value for light of wavelength λ (nm).] 4. The retardation plate with optical compensation function according to claim 1, which is a laminate including a horizontally aligned liquid crystal cured film and a vertically aligned liquid crystal cured film, and satisfies the following relationship (7):
|{R0(450)-R40(450)}-{R0(550)-R40(550)}|<3 nm ... (7)
[Here, R0(λ) is the in-plane retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film, and indicates the in-plane retardation value for light of wavelength λ (nm). Also, R40(λ) is the apparent retardation value of the retardation plate with optical compensation function including the horizontally aligned liquid crystal cured film and the vertically aligned liquid crystal cured film when rotated 40° around the direction (fast axis direction) perpendicular to the main refractive index direction in the same plane as the film plane, and indicates the retardation value for light of wavelength λ (nm).] 5. The retardation plate with optical compensation function according to claim 1, wherein the average refractive index difference at a wavelength of 550 nm among the horizontally aligned liquid crystal cured film, the vertically aligned liquid crystal cured film, and the vertically aligned film is 0.20 or less. 6. The retardation plate with optical compensation function according to claim 1 , wherein the thickness of the vertical alignment film between the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film is 30 nm or more and 0.3 μm or less. 7. An elliptically polarizing plate comprising the retardation plate with optical compensation function according to claim 1 and a polarizing plate laminated together. An organic electroluminescence display device comprising the elliptically polarizing plate according to claim 7 .