TWI861217B - Laminated body and elliptical polarizing plate containing the same - Google Patents

Abstract

The purpose of the present invention is to provide a multilayer body that is not prone to produce interference spots due to reflections at the interfaces of the horizontally aligned liquid crystal curing film, the adhesive layer, and the vertically aligned liquid crystal curing film. The multilayer body of the present invention sequentially comprises a horizontally aligned liquid crystal curing film, an adhesive layer and a vertically aligned liquid crystal curing film, and the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film satisfy the relationship of formula (1): |((n2x＋n2y)/2)－((n3x＋n3y)/2)|≦0.03  (1) [In formula (1), n2x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the adhesive layer, n2y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n2x in the same plane as n2x, and n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertically aligned liquid crystal curing film. n3y represents the refractive index at wavelength λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x].

Description

Laminated body and elliptical polarizing plate containing the same

The present invention relates to a laminate comprising a horizontal alignment liquid crystal curing film, an adhesive layer and a vertical alignment liquid crystal curing film, and an elliptical polarizing plate comprising the laminate.

An elliptical polarizer is an optical component formed by laminating polarizers and phase difference plates, and is used, for example, in an organic EL (Electroluminescence) image display device or other device that displays images in a planar state to prevent light reflection at the electrodes constituting the device. A so-called λ/4 plate is usually used as a phase difference plate constituting the elliptical polarizer. As such a phase difference plate, a phase difference plate comprising a horizontally aligned liquid crystal cured film is known, and the horizontally aligned liquid crystal cured film is formed by polymerizing and curing a polymerizable liquid crystal compound in a state of being aligned in a horizontal direction relative to the plane of the phase difference plate. In addition, the elliptical polarizer is required to have an optical compensation function, which is used to make the elliptical polarizer exhibit the same optical performance when observed from an oblique direction as when observed from the front direction. Therefore, a phase difference plate having not only a horizontally aligned liquid crystal cured film but also a vertically aligned liquid crystal cured film is proposed. The vertically aligned liquid crystal cured film is formed by polymerizing and curing a polymerizable liquid crystal compound in a state of being aligned in a vertical direction relative to the plane of the phase difference plate (Patent Document 1). [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2015-163935

[The problem the invention is trying to solve]

In the previous elliptical polarizer including a horizontal alignment liquid crystal curing film and a vertical alignment liquid crystal curing film, the horizontal alignment liquid crystal curing film and the vertical alignment liquid crystal curing film are usually laminated via an adhesive layer. Such an elliptical polarizer is prone to interfacial reflection at the interface between the horizontal alignment liquid crystal curing film and the adhesive layer, and at the interface between the adhesive layer and the vertical alignment liquid crystal curing film, respectively. Sometimes, these interfacial reflections interfere with each other to generate interference spots. When the elliptical polarizer is used in a display such as an image display device, the interference spots may lead to reduced visibility.

The purpose of the present invention is to provide a multilayer body that is not prone to interference spots due to reflections at the interfaces of the horizontally aligned liquid crystal curing film, the adhesive layer, and the vertically aligned liquid crystal curing film. [Technical means for solving the problem]

In order to solve the above problems, the inventors and others conducted intensive research and completed the present invention. That is, the present invention includes the following forms. [1] A laminate comprising, in sequence, a horizontally aligned liquid crystal curing film, an adhesive layer, and a vertically aligned liquid crystal curing film, wherein the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film satisfy the relationship of formula (1): |((n2x+n2y)/2)-((n3x+n3y)/2)|≦0.03  (1) [In formula (1), n2x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the adhesive layer, n2y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n2x in the same plane as n2x, and n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertically aligned liquid crystal curing film. nm, n3y represents the refractive index at wavelength λ nm in a direction orthogonal to the direction of n3x in the same plane as n3x]. [2] The multilayer body described in [1] above, wherein the horizontally aligned liquid crystal cured film satisfies equations (2) and (3). Re(450)/Re(550)≦1.00            (2) 100 nm＜Re(550)＜160 nm      (3) [Wherein, Re(λ) represents the in-plane phase difference of the horizontal alignment liquid crystal cured film at a wavelength of λ nm] [3] The laminate described in [1] or [2] above, wherein the vertical alignment liquid crystal cured film satisfies equations (4) and (5): n3x≒n3y＜n3z                      (4) -150 nm＜Rth(550)＜-30 nm   (5) [Wherein, n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertical alignment liquid crystal cured film, and n3y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x. nm, n3z represents the refractive index of the vertically aligned liquid crystal cured film in the film thickness direction at a wavelength of λ nm, ≒ represents the difference in the refractive index of the two is less than 0.01, and in formula (5), Rth(550) represents the phase difference value of the vertically aligned liquid crystal cured film in the thickness direction at a wavelength of 550 nm] [4] The laminate described in any one of [1] to [3] above, wherein the thickness of the adhesive layer is greater than 0.1 μm and less than 2 μm. [5] An elliptical polarizing plate, which is formed by laminating the laminate described in any one of [1] to [4] above and a polarizing film. [Effect of the invention]

According to the present invention, a multilayer structure can be provided, which is less likely to generate interference spots due to reflections at the interfaces of the horizontal alignment liquid crystal curing film, the adhesive layer, and the vertical alignment liquid crystal curing film.

The laminate of the present invention sequentially comprises a horizontally aligned liquid crystal curing film, an adhesive layer, and a vertically aligned liquid crystal curing film. In the laminate of the present invention, the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film satisfy the relationship of formula (1). |((n2x＋n2y)/2)－((n3x＋n3y)/2)|≦0.03  (1) In formula (1), n2x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the adhesive layer, and n2y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n2x in the same plane as n2x. n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertically aligned liquid crystal cured film, and n3y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x.

Formula (1) means that the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film is less than 0.03, that is, the difference is small. In a laminate formed by sequentially laminating a horizontally aligned liquid crystal curing film, an adhesive layer, and a vertically aligned liquid crystal curing film, interface reflection is likely to occur at the interface between the horizontally aligned liquid crystal curing film and the adhesive layer, and at the interface between the adhesive layer and the vertically aligned liquid crystal curing film. The reason why the interface between each liquid crystal curing film and the adhesive layer constituting such a laminated body generates interfacial reflection is that the refractive index of each liquid crystal curing film is different from the refractive index of the adhesive layer. The interfacial reflection between the horizontally aligned liquid crystal curing film and the adhesive layer and the interfacial reflection between the vertically aligned liquid crystal curing film and the adhesive layer interfere with each other, which easily leads to the generation of interference spots. In the laminated body of the present invention, by making the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film satisfy the relationship of the above formula (1), the interfacial reflection between the adhesive layer and the vertically aligned liquid crystal curing film is not easily generated, thereby suppressing the generation of interference spots caused by the mutual interference of the interfacial reflection between the horizontally aligned liquid crystal curing film and the adhesive layer.

In order to suppress the generation of interference spots in the laminate including the horizontal alignment liquid crystal curing film, the adhesive layer and the vertical alignment liquid crystal curing film, it is also considered to reduce the difference in the in-plane refractive index between the horizontal alignment liquid crystal curing film and the adhesive layer constituting an interface. However, there are a late phase axis and a late phase axis in the plane of the horizontal alignment liquid crystal curing film, so reducing the difference in the in-plane refractive index of the adhesive layer and the in-plane refractive index of the horizontal alignment liquid crystal curing film can only suppress interference spots in the direction where the difference in the refractive index between the horizontal alignment liquid crystal curing film and the adhesive layer is small, and there is also a direction in the same plane where the difference in the refractive index between the adhesive layer and the horizontal alignment liquid crystal curing film is large, and it is still difficult to suppress interference spots in this direction. In contrast, a vertically aligned liquid crystal curing film generally has a larger refractive index in the direction of its film thickness (the direction perpendicular to the liquid crystal curing film surface). On the other hand, the refractive index within the surface of the vertically aligned liquid crystal curing film is basically the same. Therefore, by reducing the difference in the in-plane refractive index between the adhesive layer and the vertically aligned liquid crystal curing film, the generation of interference spots can be suppressed in the entire area within the surface of the laminate.

In the multilayer structure of the present invention, the difference (absolute value) between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal cured film [|((n2x+n2y)/2)-((n3x+n3y)/2)|] is 0.03 or less, preferably 0.025 or less, and more preferably 0.02 or less. The lower limit of the difference is not particularly limited, because the smaller the difference, the easier it is to exert the effect of suppressing interference fringes, so it is more ideal that the above-mentioned in-plane refractive index difference is 0.

By appropriately selecting the type of adhesive forming the adhesive layer, the type of polymerizable liquid crystal compound constituting the vertical alignment liquid crystal curing film, the composition of the polymerizable liquid crystal composition, etc., the in-plane refractive index of the adhesive layer and/or the in-plane refractive index of the vertical alignment liquid crystal curing film are adjusted respectively, and the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertical alignment liquid crystal curing film can be controlled. In particular, by adjusting the in-plane refractive index of the adhesive layer without light absorption anisotropy to be close to the in-plane refractive index of the vertical alignment liquid crystal curing film, the high optical properties required for the optical film can be ensured, and at the same time, the interface reflection generated at the interface between the adhesive layer and the vertical alignment liquid crystal curing film can be effectively suppressed.

It is preferred that the horizontally aligned liquid crystal cured film constituting the multilayer structure of the present invention satisfies equations (2) and (3). Re(450)/Re(550)≦1.00          (2) 100 nm＜Re(550)＜160 nm      (3) In equations (2) and (3), Re(λ) represents the in-plane phase difference value of the horizontally aligned liquid crystal cured film at a wavelength of λ nm.

When the horizontally aligned liquid crystal cured film satisfies formula (2), the horizontally aligned liquid crystal cured film exhibits so-called reverse wavelength dispersion, that is, the in-plane phase difference value at a short wavelength is smaller than the in-plane phase difference value at a long wavelength. When the reverse wavelength dispersion is exhibited, there is a tendency to easily exhibit consistent phase difference performance in a larger wavelength range of visible light, thereby easily improving the optical properties of the laminate. On the other hand, in order for the liquid crystal cured film exhibiting reverse wavelength dispersion to obtain this property, its refractive index is likely to become higher, and it is easy to produce a difference in refractive index with the adhesive layer, resulting in that the interference fringes are likely to become more prominent. However, even in this case, in the present invention, by controlling the difference between the refractive index of the vertically aligned liquid crystal curing film and the refractive index of the adhesive layer, the interface reflection generated at the interface between the vertically aligned liquid crystal curing film and the adhesive layer can be effectively suppressed, thereby obtaining the following multilayer body: it can ensure that the liquid crystal curing film exhibiting anti-wavelength dispersion can exhibit high optical properties and is not prone to generating interference spots.

Re(450)/Re(550) is preferably greater than 0.70, more preferably greater than 0.78, and preferably less than 0.95, more preferably less than 0.92, which can improve the anti-wavelength dispersion and further enhance the effect of improving the reflected hue in the front direction of the horizontally aligned liquid crystal cured film.

The above-mentioned in-plane phase difference value can be adjusted by the thickness d1 of the horizontal alignment liquid crystal cured film. The in-plane phase difference value of the horizontal alignment liquid crystal cured film is determined by the formula Re1(λ)＝(n1x(λ)－n1y(λ))×d1 [where n1x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the horizontal alignment liquid crystal cured film, n1y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n1x in the same plane as n1x, and d1 represents the film thickness of the horizontal alignment liquid crystal cured film]. Therefore, to obtain an ideal in-plane phase difference value (Re1(λ): in-plane phase difference value of the horizontal alignment liquid crystal cured film at a wavelength of λ (nm)), it is sufficient to adjust the three-dimensional refractive index and the film thickness d1.

If the horizontal alignment liquid crystal cured film satisfies formula (3), when the laminate (elliptical polarizer) including the horizontal alignment liquid crystal cured film is applied to an organic EL display device, the front reflection hue when displaying black is easily improved. The in-plane phase difference value is further preferably in the range of 130 nm ≤ ReA (550) ≤ 150 nm.

The vertical alignment liquid crystal cured film constituting the multilayer body of the present invention preferably satisfies formulas (4) and (5). n3x≒n3y＜n3z                      (4) -150 nm＜Rth(550)＜-30 nm   (5) In formula (4), n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertical alignment liquid crystal cured film, n3y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x, and n3z represents the refractive index at a wavelength of λ nm in the film thickness direction of the vertical alignment liquid crystal cured film, and ≒ represents the difference in refractive index between the two is less than 0.01. In formula (5), Rth(550) represents the phase difference value of the vertical alignment liquid crystal cured film in the thickness direction at a wavelength of 550 nm.

Formula (4) means that the refractive index (n3z) of the vertical alignment liquid crystal cured film at a wavelength of λ nm in the film thickness direction is greater than the refractive index (n3x and n3y) at a wavelength of λ nm in the plane of the vertical alignment liquid crystal cured film, and the difference between n3x and n3y is less than 0.01, and there is almost no difference in the refractive index in the plane of the vertical alignment liquid crystal cured film. The difference in the refractive index in the plane of the vertical alignment liquid crystal cured film may cause a local deviation between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertical alignment liquid crystal cured film. The vertical alignment liquid crystal cured film that satisfies formula (4) has no difference in the refractive index in the plane, or the difference in the refractive index in the plane is very small, so it is not easy to produce such a local deviation. Thus, by controlling the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertically aligned liquid crystal curing film so as to satisfy the relationship of the above formula (1), it is not easy to generate interface reflection between the adhesive layer and the vertically aligned liquid crystal curing film, and it is easy to further enhance the effect of suppressing the generation of interference spots in the entire area within the plane of the laminate.

If the vertically aligned liquid crystal cured film satisfies formula (5), the polymerizable liquid crystal compound constituting the vertically aligned liquid crystal cured film is aligned with a high degree of order in the vertical direction of the liquid crystal cured film, and when the laminate including the vertically aligned liquid crystal cured film is installed in an organic EL display device, there is a tendency to have an excellent effect of suppressing the oblique reflection hue change when displaying black. In order to further improve the optical properties of the laminate, the phase difference value Rth(550) of the vertically aligned liquid crystal cured film in the film thickness direction is preferably greater than -100 nm, more preferably greater than -90 nm, and more preferably less than -40 nm, and more preferably less than -50 nm.

The phase difference Rth(λ) in the thickness direction of the vertically aligned liquid crystal cured film can be adjusted by the thickness d3 of the vertically aligned liquid crystal cured film. The in-plane phase difference is determined by the following formula: Rth(λ)＝((n3x(λ)＋n3y(λ))/2－n3z(λ))×d3, (where n3x(λ), n3y(λ) and n3z(λ) are synonymous with the above) Therefore, to obtain the desired phase difference Rth(λ) in the thickness direction, it is only necessary to adjust the three-dimensional refractive index and the film thickness d3.

In the laminate of the present invention, the horizontal alignment liquid crystal curing film, the adhesive layer, and the vertical alignment liquid crystal curing film may be separated from other layers, but it is preferred that the adhesive layer and the vertical alignment liquid crystal curing film exist adjacent to each other. If the adhesive layer and the vertical alignment liquid crystal curing film exist adjacent to each other, they will not be affected by the in-plane refractive index from other layers, and the interference spots can be reduced by controlling the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertical alignment liquid crystal curing film. Furthermore, in order to suppress the interface reflection that may be generated due to the relationship with the adhesive layer or the horizontal alignment liquid crystal curing film, it is more preferable that the horizontal alignment liquid crystal curing film and the adhesive layer, and the adhesive layer and the vertical alignment liquid crystal curing film exist adjacent to each other. As the above-mentioned other layers, for example, there can be listed curing resin layers such as horizontal alignment film, vertical alignment film, protective layer, and hard coating layer.

In the present invention, the horizontal alignment liquid crystal cured film and the horizontal alignment liquid crystal cured film each comprise a cured product of a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound. The polymerizable liquid crystal compound is not particularly limited as long as it can form a liquid crystal cured film having the desired optical properties, and a polymerizable liquid crystal compound previously known in the field of phase difference film can be used.

A polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. As polymerizable liquid crystal compounds, the following two types can generally be listed: a polymer (cured product) obtained by polymerizing the polymerizable liquid crystal compound in a state where the polymerizable liquid crystal compound is aligned in a specific direction alone exhibits positive wavelength dispersion or exhibits reverse wavelength dispersion. In the present invention, only one type of polymerizable liquid crystal compound can be used, or the two types of polymerizable liquid crystal compounds can be used in combination. In addition, the polymerizable liquid crystal compound constituting the horizontally aligned liquid crystal cured film and the polymerizable liquid crystal compound constituting the vertically aligned liquid crystal cured film can be the same or different. In order to easily obtain a liquid crystal cured film that satisfies the above formula (2) and to easily improve the optical properties as a laminate, it is preferred that in the laminate of the present invention, the horizontally aligned liquid crystal cured film is a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound exhibiting reverse wavelength dispersion.

A polymerizable group refers to a group that can participate in a polymerization reaction. In the present invention, the polymerizable group possessed by the polymerizable liquid crystal compound that forms the liquid crystal cured film is preferably a photopolymerizable group. A photopolymerizable group refers to a polymerizable group that can participate in a polymerization reaction using reactive species generated by a photopolymerization initiator, such as an active free radical or an acid. Examples of photopolymerizable groups include vinyl, vinyloxy, 1-vinyl chloride, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide, and cyclobutylene oxide. Among them, acryloxy, methacryloxy, vinyloxy, ethylene oxide, and cyclobutylene oxide are preferred, and acryloxy is more preferred. The liquid crystal properties exhibited by the polymerizable liquid crystal compound can be thermotropic liquid crystal or hydrotropic liquid crystal, among which thermotropic liquid crystal is preferred because it can achieve fine film thickness control. In addition, the phase order structure in the thermotropic liquid crystal can be nematic liquid crystal, lamellar liquid crystal, or discotic liquid crystal. The polymerizable liquid crystal compound can be used alone or in combination of two or more.

A polymerizable liquid crystal compound having a so-called T-shaped or H-shaped molecular structure tends to exhibit inverse wavelength dispersion, and a polymerizable liquid crystal compound having a T-shaped molecular structure tends to exhibit stronger inverse wavelength dispersion.

As a polymerizable liquid crystal compound showing reverse wavelength dispersion, a compound having the following characteristics (A) to (D) is preferred. (A) A compound that can form a nematic phase or a lamellar phase. (B) Having π electrons in the long axis direction (a) of the polymerizable liquid crystal compound. (C) Having π electrons in the direction intersecting the long axis direction (a) [intersecting direction (b)]. (D) Let the total number of π electrons in the long axis direction (a) be N(πa), let the total number of molecular weights in the long axis direction be N(Aa), and define the π electron density in the long axis direction (a) of the polymerizable liquid crystal compound by the following formula (i): D(πa)=N(πa)/N(Aa)  (i) Let the total number of π electrons in the cross direction (b) be N(πb), let the total number of molecular weights in the cross direction (b) be N(Ab), and define the π electron density in the cross direction (b) of the polymerizable liquid crystal compound by the following formula (ii): D(πb)=N(πb)/N(Ab)  (ii) Then D(πa) and D(πb) have the relationship of formula (iii): 0≦[D(πa)/D(πb)]＜1  (iii) [That is, the π electron density in the cross direction (b) is greater than the π electron density in the long axis direction (a)]. As described above, polymerizable liquid crystal compounds having π electrons in the long axis and in the direction crossing the long axis are usually prone to form a T-shaped structure.

Among the above characteristics (A) to (D), the definitions of the long axis direction (a) and the number of π electrons N are as follows. · For example, if it is a compound having a rod-like structure, the long axis direction (a) is the long axis direction of the rod. · The number of π electrons N (πa) existing in the long axis direction (a) does not include the π electrons that disappear due to the polymerization reaction. · The number of π electrons N (πa) existing in the long axis direction (a) is the total number of π electrons on the long axis and the π electrons covalent therewith, for example, including the number of π electrons existing in the ring that is located in the long axis direction (a) and satisfies the Huckel rule. · The number of π electrons N (πb) existing in the cross direction (b) does not include the π electrons that disappear due to the polymerization reaction. The polymerizable liquid crystal compound satisfying the above has a liquid crystal original structure in the long axis direction. The liquid crystal phase (nematic phase, smectic phase) is manifested by the mesogen structure.

By heating the polymerizable liquid crystal compound satisfying the above (A) to (D) to above the phase transition temperature, a nematic phase or a lamellar phase can be formed. The nematic phase or the lamellar phase formed by the alignment of the polymerizable liquid crystal compound is usually aligned in a manner that the long axis directions of the polymerizable liquid crystal compound are parallel to each other, and the long axis direction becomes the alignment direction of the nematic phase or the lamellar phase. If such a polymerizable liquid crystal compound is made into a film and polymerized in the state of the nematic phase or the lamellar phase, a polymer film containing a polymer polymerized in a state of alignment in the long axis direction (a) can be formed. The polymer film absorbs ultraviolet light by π electrons in the long axis direction (a) and π electrons in the cross direction (b). Here, the absorption maximum wavelength of ultraviolet light absorbed by π electrons in the cross direction (b) is set to λbmax. λbmax is usually 300 nm to 400 nm. The density of π electrons satisfies the above formula (iii), and the density of π electrons in the cross direction (b) is greater than that in the long axis direction (a). Therefore, the absorption of the polymer film to linearly polarized ultraviolet light (wavelength λbmax) having a vibration plane in the cross direction (b) is greater than that to linearly polarized ultraviolet light (wavelength λbmax) having a vibration plane in the long axis direction (a). The ratio (absorbance of linearly polarized ultraviolet light in the cross direction (b)/absorbance in the long axis direction (a)) is, for example, greater than 1.0, preferably greater than 1.2, and is usually less than 30, for example, less than 10.

When polymerizable liquid crystal compounds having the above characteristics are polymerized in a unidirectional state, the birefringence of the polymers usually exhibits reverse wavelength dispersion. Specifically, for example, the compounds represented by the following formula (X) (hereinafter, also referred to as "polymerizable liquid crystal compounds (X)") can be cited.

In formula (X), Ar represents a divalent aromatic group which may have a substituent. Examples of the aromatic group here include the groups exemplified in (Ar-1) to (Ar-23) described later. In addition, Ar may have two or more aromatic groups. The aromatic group may contain at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other by a single bond, -CO-O-, -O- or other divalent bonding groups. ^G1 and ^G2 each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic alkyl group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic alkyl group may be substituted with an oxygen atom, a sulfur atom or a nitrogen atom. L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group. k and l are each independently an integer of 0 to 3, satisfying the relationship of 1≦k+1. Here, when 2≦k+1, B ¹ and B ² , G ¹ and G ² may be the same or different from each other. E ¹ and E ² are each independently an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms. Furthermore, the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and the _-CH2- contained in the alkanediyl group may be substituted with -O-, -S-, or -C(=O)-. ^P1 and ^P2 independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

^G1 and ^G2 are each independently preferably 1,4-phenylenediyl 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, 1,4-cyclohexanediyl 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 1,4-phenylenediyl substituted with a methyl group, unsubstituted 1,4-phenylenediyl, or unsubstituted 1,4-trans-cyclohexanediyl, and particularly preferably unsubstituted 1,4-phenylenediyl or unsubstituted 1,4-trans-cyclohexanediyl. Furthermore, it is preferred that at least one of a plurality of ^G1 and ^G2 is a divalent alicyclic hydrocarbon group, and it is more preferred that at least one of ^G1 and ^G2 bonded to ^L1 or ^L2 is a divalent alicyclic hydrocarbon group.

^L1 and ^L2 are each independently preferably a ^single bond, an alkylene group having 1 ^to 4 carbon atoms, -O-, -S-, -Ra1ORa2-, -Ra3COORa4-, ^-Ra5OCORa6- , ^-Ra7OC = ^OORa8- , -N=N-, ^-CRc = ^CRd- , or ^-C≡C- . Here, ^Ra1 to ^Ra8 are each independently a single bond, or an alkylene ^group having 1 to 4 carbon atoms, and ^Rc and ^Rd are alkyl groups having 1 to 4 carbon atoms or a hydrogen atom. ^L1 and ^L2 are each independently more preferably a single bond, ^{-ORa2-1- ,} _-CH2- , _-CH2CH2- , _-COORa4-1- , or ^{-OCORa6-1- .} Here, ^Ra2-1 , ^Ra4-1 , and ^Ra6-1 each independently represent a single bond, _-CH2- , or _-CH2CH2- . ^L1 and ^L2 each independently represent a single bond _{, -O-, -CH2CH2- ,} -COO-, _{-COOCH2CH2- ,} or _-OCO- .

^B1 and ^B2 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. ^B1 and ^B2 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 are each independently a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. ^B1 and ^B2 are each independently preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO-, or -OCOCH ₂ CH ₂ -.

To show anti-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. If k=2 and l=2, it will become a symmetric structure, so it is better.

Examples of the polymerizable group represented by ^P1 or ^P2 include epoxy, vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide, and cyclobutylene. Among them, acryloxy, methacryloxy, vinyl, and vinyloxy are preferred, and acryloxy and methacryloxy are more preferred.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-attracting group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and benzene ring and naphthalene ring are preferred. As the aromatic heterocyclic ring, there can be listed a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrrolidine ring, a pyrimidine ring, a triazole ring, a trilazole ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, a thiazole ring, a benzothiazole ring, a benzothiazole ring, and a phenanthroline ring. Among them, it is preferred to have a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is further preferred to have a benzothiazole ring. In addition, when Ar contains a nitrogen atom, the nitrogen atom preferably has π electrons.

In formula (X), the total number _Nπ of π electrons possessed by the group represented by Ar is usually 6 or more, preferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. Further, it is preferably 32 or less, more preferably 26 or less, and further preferably 24 or less.

As the aromatic group contained in Ar, for example, the following groups can be listed.

In formula (Ar-1) to formula (Ar-23), the * symbol represents a linking portion, and ^Z0 , ^Z1, and ^Z2 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 12 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-alkylaminesulfonyl group having 1 to 12 carbon atoms, or an N,N-dialkylaminesulfonyl group having 2 to 12 carbon atoms. In addition, ^Z0 , ^Z1, and ^Z2 may include a polymerizable group.

^Q1 and ^Q2 each independently represent ^-CR2'R3'- , ^-S- , -NH-, ^-NR2'- , -CO- or -O-, and R2 ^' and R3 ^' each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

^J1 and ^J2 each independently represent a carbon atom or a nitrogen atom.

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

^W1 and ^W2 each independently represent a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer of 0 to 6.

Examples of the aromatic alkyl group in Y ¹ , Y ² and Y ³ include aromatic alkyl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, anthracenyl, phenanthrenyl and biphenyl, preferably phenyl and naphthyl, and more preferably phenyl. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms, such as furanyl, pyrrolyl, thienyl, pyridyl, thiazolyl and benzothiazolyl, which contain at least one hetero atom such as a nitrogen atom, an oxygen atom or a sulfur atom, preferably furanyl, thienyl, pyridyl, thiazolyl and benzothiazolyl.

Y ¹ , Y ² and Y ³ may be independently substituted polycyclic aromatic alkyl groups or polycyclic aromatic heterocyclic groups. Polycyclic aromatic alkyl groups refer to condensed polycyclic aromatic alkyl groups or groups derived from aromatic rings. Polycyclic aromatic heterocyclic groups refer to condensed polycyclic aromatic heterocyclic groups or groups derived from aromatic rings.

^Z0 , ^Z1 and ^Z2 are each independently preferably 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. ^Z0 is further preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group. ^Z1 and ^Z2 are further preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group. Furthermore, ^Z0 , ^Z1 and ^Z2 may contain a polymerizable group.

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

Among formulae (Ar-1) to (Ar-23), formula (Ar-6) and formula (Ar-7) are preferred from the viewpoint of molecular stability.

In formulas (Ar-16) to (Ar-23), ^Y1 may also form an aromatic heterocyclic group together with the nitrogen atom and ^Z0 to which it is bonded. As the aromatic heterocyclic group, the aromatic heterocyclic rings that may be present as Ar are listed above, for example, pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrrolidine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidinyl ring, etc. The aromatic heterocyclic group may have a substituent. In addition, ^Y1 may also form the above-mentioned polycyclic aromatic alkyl group or polycyclic aromatic heterocyclic group which may be substituted together with the nitrogen atom and ^Z0 to which it is bonded. For example, a benzofuran ring, a benzothiazole ring, a benzoxazolyl ring, etc. can be listed.

In the present invention, as a polymerizable liquid crystal compound for forming a liquid crystal cured film, for example, a compound containing a group represented by the following formula (Y) (hereinafter, also referred to as "polymerizable liquid crystal compound (Y)") can be used. The polymerizable liquid crystal compound (Y) generally tends to exhibit positive wavelength dispersion. These polymerizable liquid crystal compounds can be used alone or in combination of two or more.

P11-B11-E11-B12-A11-B13- (Y) [In formula (Y), P11 represents a polymerizable group; A11 represents a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group; B11 represents -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -, -NR ¹⁶ -CO-, -CO-, -CS- or a single bond; R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; B12 and B13 each independently represent -C≡C-, -CH=CH-, -CH ₂ -CH ₂ -, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, -OC(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O)-NR ¹⁶ -, -NR ¹⁶ -C(=O)-, -OCH ₂ -, -OCF 2 -, -CH ₂ O-, -CF ₂ O-, -CH=CH-C(=O ₎ -O-, -OC(=O)-CH=CH-, -H, -C≡N or a single bond; E11 represents an alkanediyl group having 1 to 12 carbon atoms, the hydrogen atom contained in the alkanediyl group may be substituted by an alkoxy group having 1 to 5 carbon atoms, and the hydrogen atom contained in the alkoxy group may be substituted by a halogen atom; further, the -CH ₂ - constituting the alkanediyl group may be substituted by -O- or -CO-]

The number of carbon atoms in the aromatic alkyl group and the alicyclic alkyl group represented by A11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, and particularly preferably 5 or 6. The hydrogen atom contained in the divalent alicyclic alkyl group and the divalent aromatic alkyl group represented by A11 may be substituted by a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group or a nitro group, and the hydrogen atom contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted by a fluorine atom. Preferred as A11 are cyclohexane-1,4-diyl and 1,4-phenylene.

E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. -CH ₂ - constituting the alkanediyl group may be substituted with -O-. Specific examples include: methylene, ethylidene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl and dodecane-1,12-diyl; _{-CH2- CH2} -O- _CH2 - _CH2- , -CH2 _-CH2 - _O -CH2- _CH2 - _O - _CH2 - _CH2- and _-CH2 - _CH2 -O- _CH2 - _CH2 -O-CH2- _CH2 -O- _CH2 - _{CH2- ,} etc. As B11, -O-, -S-, -CO-O-, and -O-CO- are preferred, and -CO-O- is more preferred. As B12 and B13, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, and -OC(=O)-O- are respectively and independently preferred, and -O- or -OC(=O)-O- is more preferred.

As the polymerizable group represented by P11, in order to make the polymerization reactivity, especially the photopolymerization reactivity higher, it is preferably a free radical polymerizable group or a cationic polymerizable group. In order to make the operation easy and the liquid crystal compound itself easy to prepare, the polymerizable group is preferably a group represented by the following formula (P-11) to (P-15).

[In formulas (P-11) to (P-15), R ¹⁷ to R ²¹ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom]

As specific examples of the groups represented by formula (P-11) to formula (P-15), groups represented by the following formula (P-16) to formula (P-20) can be cited.

P11 is preferably a group represented by formula (P-14) to formula (P-20), and more preferably a vinyl group, a para-stilbene group, an epoxy group, or an oxacyclobutyl group. The group represented by P11-B11- is further preferably an acryloxy group or a methacryloxy group.

Examples of the polymerizable liquid crystal compound (Y) include compounds represented by formula (I), formula (II), formula (III), formula (IV), formula (V) or formula (VI). P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (I) P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (II) P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (III) P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (IV) P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (V) P11-B11-E11-B12-A11-B13-A12-F11 (VI) [wherein, A11, B11 to B13 and P11 are synonymous with the above, A12 to A14 are each independently synonymous with A11, B14 to B16 are each independently synonymous with B12, B17 is synonymous with B11, E12 is synonymous with E11, and P12 is synonymous with P11; F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxyl group, a hydroxymethyl group, a methyl group, a sulfonic group (-SO ₃ H), carboxyl, alkoxycarbonyl having 1 to 10 carbon atoms or halogen atoms, the -CH ₂ - constituting the alkyl and alkoxy groups may be substituted with -O-]

Specific examples of polymerizable liquid crystal compounds (Y) include compounds having polymerizable groups described in "3.8.6 Network (Completely Cross-linked Type)" and "6.5.1 Liquid Crystal Materials b. Polymerizable Nematic Liquid Crystal Materials" of Liquid Crystal Handbook (edited by Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2001), and polymerizable liquid crystals described in Japanese Patent Publication No. 2010-31223, Japanese Patent Publication No. 2010-270108, Japanese Patent Publication No. 2011-6360, and Japanese Patent Publication No. 2011-207765.

As specific examples of polymerizable liquid crystal compounds (Y), compounds represented by the following formulae (I-1) to (I-4), (II-1) to (II-4), (III-1) to (III-26), (IV-1) to (IV-26), (V-1) to (V-2), and (VI-1) to (VI-6) can be cited. In the following formulae, k1 and k2 each independently represent an integer of 2 to 12. Such polymerizable liquid crystal compounds (Y) are preferred because they are easy to synthesize or easy to obtain.

The polymerizable liquid crystal compounds (X) and (Y) can be used after being aligned horizontally or vertically.

Relative to 100 parts by mass of the solid content of the polymerizable liquid crystal composition, the content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and further preferably 90 to 95 parts by mass. If the content of the polymerizable liquid crystal compound is within the above range, it is beneficial to improve the alignment accuracy of the resulting liquid crystal cured film. Furthermore, when the polymerizable liquid crystal composition contains more than two polymerizable liquid crystal compounds, it is preferred that the total amount of all liquid crystal compounds contained in the polymerizable liquid crystal composition is within the above content range. In addition, in this specification, the solid content of the polymerizable liquid crystal composition refers to all components after removing volatile components such as organic solvents from the polymerizable liquid crystal composition.

In addition to the polymerizable liquid crystal compound, the polymerizable liquid crystal composition may further include additives such as a solvent, a polymerization initiator, a leveler, an antioxidant, a photosensitizer, and a reactive additive. These components may be used alone or in combination of two or more.

The polymerizable liquid crystal composition is usually applied to a substrate film or the like in a state of being dissolved in a solvent, so it is preferred to include a solvent. As the solvent, it is preferred to use a solvent that can dissolve the polymerizable liquid crystal compound, and it is preferred to use a solvent that is inactive in the polymerization reaction of the polymerizable liquid crystal compound. As the solvent, for example, alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropanol, 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; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl Ketone solvents such as isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aliphatic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone, etc. These solvents may be used alone or in combination of two or more. Among them, from the viewpoint of film coating, it is preferred to use at least one selected from alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide solvents and aromatic hydrocarbon solvents, and from the viewpoint of solubility of polymerizable liquid crystal compounds, it is more preferred to use at least one selected from ester solvents, ketone solvents, amide solvents and aromatic hydrocarbon solvents.

The content of the solvent in the polymerizable liquid crystal composition is preferably 50 to 98 parts by weight, and more preferably 70 to 95 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal composition. Therefore, it is preferred that the solid component accounts for 2 to 50 parts by weight of the polymerizable liquid crystal composition in 100 parts by weight. If the solid component is less than 50 parts by weight, the viscosity of the polymerizable liquid crystal composition will become lower, so the thickness of the film will become roughly uniform and will not easily produce uneven tendencies. The above solid component can be appropriately determined considering the thickness of the polymerizable liquid crystal cured film to be manufactured.

The polymerization initiator is a compound that can generate reactive species under the action of heat or light to initiate the polymerization reaction of the polymerizable liquid crystal compound. As reactive species, free radicals, cations, anions, etc. can be listed. Among them, from the perspective of easy control of the reaction, a photopolymerization initiator that generates free radicals by light irradiation is preferred.

Examples of the photopolymerization initiator include benzoin compounds, benzophenone compounds, benzoyl ketal compounds, oxime compounds, α-hydroxy ketone compounds, α-amino ketone compounds, tris(iodine) compounds, iodonium salts and coronium salts, and commercially available products may also be used. 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 Co., Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (all manufactured by Seiko Chemical Co., Ltd.), Kayacure BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow Chemical Co., Ltd.), Adeka Optomer SP-152, Adeka Optomer SP-170, Adeka Optomer N-1717, Adeka Optomer N-1919, Adeka Arkles NCI-831, Adeka Arkles NCI-930 (all manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (all manufactured by Nihon Siber Hegner Co., Ltd.) and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.). The photopolymerization initiator contained in the polymerizable liquid crystal composition is at least one, and multiple types can be used in combination. It can be appropriately selected according to the relationship with the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition.

The maximum absorption wavelength of the photopolymerization initiator is preferably 300 nm to 400 nm, more preferably 300 nm to 380 nm, so that the energy emitted from the light source can be fully utilized to achieve excellent productivity. Among them, α-acetophenone-based polymerization initiators and oxime-based photopolymerization initiators are preferred.

Examples of the α-acetophenone compound include 2-methyl-2-morpholinyl-1-(4-methylthiophenyl)propane-1-one, 2-dimethylamino-1-(4-morpholinylphenyl)-2-benzylbutane-1-one, and 2-dimethylamino-1-(4-morpholinylphenyl)-2-(4-methylphenylmethyl)butane-1-one. More preferred examples include 2-methyl-2-morpholinyl-1-(4-methylthiophenyl)propane-1-one and 2-dimethylamino-1-(4-morpholinylphenyl)-2-benzylbutane-1-one. Examples of commercially available α-acetophenone compounds include Irgacure 369, 379EG, and 907 (all manufactured by BASF Japan Co., Ltd.) and Seikuol BEE (manufactured by Seiko Chemical Industries, Ltd.).

Oxime ester photopolymerization initiators generate free radicals such as phenyl radicals and methyl radicals by being irradiated with light. The polymerizable liquid crystal compound is polymerized better by the free radicals, and the oxime ester photopolymerization initiators that generate methyl radicals are preferred because of the higher starting efficiency of the polymerization reaction. In addition, in order to make the polymerization reaction proceed more efficiently, it is preferred to use a photopolymerization initiator that can efficiently utilize ultraviolet rays with a wavelength of more than 350 nm. As a photopolymerization initiator that can efficiently utilize ultraviolet rays with a wavelength of more than 350 nm, trioxime compounds and carbazole compounds containing an oxime ester structure are preferred. From the perspective of sensitivity, carbazole compounds containing an oxime ester structure are more preferred. Examples of carbazole compounds containing an oxime ester structure include 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyl oxime)], ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime), etc. Examples of commercially available oxime ester-based photopolymerization initiators include IrgacureOXE-01, IrgacureOXE-02, and IrgacureOXE-03 (all manufactured by BASF Japan Co., Ltd.), Adeka Optomer N-1919, and Adeka Arkles NCI-831 (all manufactured by ADEKA Co., Ltd.), etc.

The content of the photopolymerization initiator is generally 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, and more preferably 1 to 15 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound. If it is within the above range, the reaction of the polymerizable group proceeds fully and the alignment of the polymerizable liquid crystal compound is not easily disturbed.

A leveling agent is an additive that has the function of adjusting the fluidity of a polymerizable liquid crystal composition to make the coating film obtained by coating the composition flatter. For example, polysilicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents can be listed. As a leveling agent, commercially available products can also be used, specifically DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all of which are manufactured by Toray Dow Corning Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22- 161A, KF6001 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all manufactured by Maitu Advanced Materials Japan Co., Ltd.), fluorinert (registered trademark) FC-72, fluorinert FC-40, fluorinert FC-43, fluorinert FC-3283 (all manufactured by Sumitomo 3M Co., Ltd.), MEGAFAC (registered trademark) R-08, MEGAFAC R-30, MEGAFAC R-90, MEGAFAC F-410, MEGAFAC F-411, MEGAFAC F-443, MEGAFAC F-445, MEGAFAC F-470, MEGAFAC F-477, MEGAFAC F-479, MEGAFAC F-482, MEGAFAC F-483, MEGAFAC F-556 (all manufactured by DIC Co., Ltd.), Eftop (trade name) EF301, Eftop EF303, Eftop EF351, Eftop EF352 (all manufactured by Mitsubishi Materials Corporation), Surflon (registered trademark) S-381, Surflon S-382, Surflon S-383, Surflon S-393, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all manufactured by AGC Seimi Chemical Corporation), trade names E1830, E5844 (manufactured by Daikin Fine Chemicals Laboratories), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all trade names: manufactured by BM Chemie Co., Ltd.), etc. Leveling agents may be used alone or in combination of two or more.

The content of the leveling agent is preferably 0.01 to 5 parts by weight, and more preferably 0.05 to 3 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, it is easy to align the polymerizable liquid crystal compound, and the obtained liquid crystal cured film tends to become smoother, so it is preferred.

By preparing an antioxidant, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. As an antioxidant, it can be a primary antioxidant selected from phenolic antioxidants, amine antioxidants, quinone antioxidants, and nitroso antioxidants, and it can also be a secondary antioxidant selected from phosphorus antioxidants and sulfur antioxidants. In order to polymerize the polymerizable liquid crystal compound without disturbing the alignment of the polymerizable liquid crystal compound, the content of the antioxidant is generally 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and further preferably 0.1 to 3 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound. The antioxidant can be used alone or in combination of two or more.

By using a photosensitizer, the photopolymerization initiator can be made highly sensitive. Examples of the photosensitizer include thiophene, 9-oxothiophene, ketones; anthracenes with substituents such as anthracene and alkyl ethers; phenathiophene; rubrene. The photosensitizer 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 further preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

As the reactive additive, it is preferred that the reactive additive has a carbon-carbon unsaturated bond and an active hydrogen reactive group in its molecule. In addition, the "active hydrogen reactive group" herein means a group reactive to a group having active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), an amine group (-NH ₂ ), and representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an amide group, an isocyanate group, a thioisocyanate group, a maleic anhydride group, and the like. The number of carbon-carbon unsaturated bonds or active hydrogen reactive groups possessed by the reactive additive is usually 1 to 20, and preferably 1 to 10, respectively.

It is preferred that the reactive additive contain at least two active hydrogen-reactive groups. In this case, the plurality of active hydrogen-reactive groups may be the same or different.

The carbon-carbon unsaturated bond of the reactive additive may be a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof, preferably a carbon-carbon double bond. The reactive additive preferably contains a carbon-carbon unsaturated bond in the form of a vinyl group and/or a (meth) acrylic group. Furthermore, the reactive additive preferably has an active hydrogen reactive group selected from at least one of the group consisting of an epoxy group, a glycidyl group, and an isocyanate group, and more preferably has an acrylic group and an isocyanate group.

Specific examples of reactive additives include compounds having a (meth)acrylic acid group and an epoxy group, such as methacryloyloxy glycidyl ether and acryloxy glycidyl ether; compounds having a (meth)acrylic acid group and an oxycyclobutane group, such as cyclohexane acrylate and cyclohexane methacrylate; compounds having a (meth)acrylic acid group and a lactone group, such as lactone acrylate and lactone methacrylate; compounds having a vinyl group and an oxazoline group, such as vinyl oxazoline and isopropenyl oxazoline; oligomers of compounds having a (meth)acrylic acid group and an isocyanate group, such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, or 2-isocyanatoethyl methacrylate, etc. In addition, compounds having a vinyl group or a vinyl group and anhydride such as methacrylic anhydride, acrylic anhydride, maleic anhydride or ethylene maleic anhydride can be cited. Among them, preferred are methacryloyloxy glycidyl ether, acryloxy glycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyl oxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate or oligomers thereof, and particularly preferred are isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate or oligomers thereof.

As the above-mentioned reactive additive, a commercial product can be used as it is or can be used after purification as necessary. As a commercial product, for example, Laromer (registered trademark) LR-9000 (manufactured by BASF Corporation) can be mentioned.

When the polymerizable liquid crystal composition contains a reactive additive, the content of the reactive additive is generally 0.01 to 10 parts by mass, preferably 0.1 to 7 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

The polymerizable liquid crystal compositions for forming the horizontal alignment liquid crystal cured film and the vertical alignment liquid crystal cured film can be obtained by stirring components such as a polymerizable liquid crystal compound, a solvent, and a polymerization initiator at a specified temperature.

The horizontally aligned liquid crystal curing film and the vertically aligned liquid crystal curing film can be manufactured, for example, by a method comprising the following steps: Forming a coating of a polymerizable liquid crystal composition comprising at least one polymerizable liquid crystal compound on a substrate or an alignment film described later, drying the coating, and aligning the polymerizable liquid crystal compound in the polymerizable liquid crystal composition; and Maintaining the alignment state, polymerizing the polymerizable liquid crystal compound to form a liquid crystal curing film.

The coating film of the polymerizable liquid crystal composition can be formed by coating the polymerizable liquid crystal composition on a substrate or an alignment film formed on the substrate as described below. As the substrate, for example, a glass substrate or a film substrate can be listed, but from the viewpoint of processability, a resin film substrate is preferred. As the resin constituting the film substrate, for example, polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; plastics such as polyphenylene sulfide and polyphenylene ether can be listed. Such resin can be made into a film by known means such as solvent casting method and melt extrusion method to make a substrate. The substrate surface may have a protective layer formed by acrylic resin, methacrylic resin, epoxy resin, cyclohexane resin, urethane resin, melamine resin, etc., and may also be subjected to surface treatment such as release treatment of polysilicone treatment, corona treatment, plasma treatment, etc.

As the substrate, a commercial product may be used. Examples of commercially available cellulose ester substrates include cellulose ester substrates manufactured by Fujitac Film Co., Ltd., and cellulose ester substrates manufactured by Konica Minolta Opto Co., Ltd., such as "KC8UX2M", "KC8UY", and "KC4UY". Examples of commercially available cyclic olefin resins include cyclic olefin resins such as "Topas (registered trademark)" manufactured by Ticona (Germany); cyclic olefin resins such as "ARTON (registered trademark)" manufactured by JSR Co., Ltd.; cyclic olefin resins such as "ZEONOR (registered trademark)" and "ZEONEX (registered trademark)" manufactured by Zeon Co., Ltd.; and cyclic olefin resins such as "APEL (registered trademark)" manufactured by Mitsui Chemicals Co., Ltd. Commercially available cyclic olefin resin substrates may also be used. Examples of commercially available cyclic olefin resin substrates include “S-SINA (registered trademark)” and “SCA40 (registered trademark)” manufactured by Sekisui Chemical Industries, Ltd.; “ZEONOR FILM (registered trademark)” manufactured by Optes Co., Ltd.; and “ARTON FILM (registered trademark)” manufactured by JSR Co., Ltd.

The substrate is preferably one that can be finally peeled off from the laminate of the present invention. To make the substrate have good peelability and handling properties and to achieve thinning of the laminate, the thickness of the substrate is usually 5 to 300 μm, preferably 10 to 150 μm.

As a method for applying the polymerizable liquid crystal composition on a substrate, there can be listed known methods such as spin coating, extrusion coating, gravure coating, die-nozzle coating, rod coating, applicator coating, and printing methods such as flexographic printing.

Then, the solvent is removed by drying, etc., thereby forming a dry coating. As drying methods, natural drying, ventilation drying, heating drying, and reduced pressure drying can be listed. At this time, by heating the coating obtained from the polymerizable liquid crystal composition, the solvent can be removed from the coating by drying, and the polymerizable liquid crystal compound can be aligned in an ideal direction (for example, horizontal or vertical direction) relative to the coating plane. The heating temperature of the coating can be appropriately determined according to the polymerizable liquid crystal compound used and the material of the substrate forming the coating, etc., but in order to make the polymerizable liquid crystal compound transition to the liquid crystal phase state, a temperature above the liquid crystal phase transition temperature is usually required. In order to remove the solvent contained in the polymerizable liquid crystal composition and make the polymerizable liquid crystal compound into an ideal alignment state, for example, it can be heated to a temperature above the liquid crystal phase transition temperature (smectic phase transition temperature or nematic phase transition temperature) of the polymerizable liquid crystal compound contained in the above-mentioned polymerizable liquid crystal composition. The heating temperature is preferably 3°C higher than the liquid crystal phase transition temperature of the polymerizable liquid crystal compound, and more preferably 5°C higher. The upper limit of the heating temperature is not particularly limited. In order to avoid damage to the coating or substrate caused by heating, it is preferably below 180°C, and more preferably below 150°C. Furthermore, the liquid crystal phase transition temperature can be measured, for example, using a polarizing microscope equipped with a temperature control stage, a differential scanning calorimeter (DSC), a thermogravimetric differential thermal analyzer (TG-DTA), etc. In addition, when two or more polymerizable liquid crystal compounds are used in combination, the above phase transition temperature means a temperature measured by the following method: all polymerizable liquid crystal compounds constituting the polymerizable liquid crystal composition are mixed in the same ratio as the composition in the polymerizable liquid crystal composition, and the mixture of polymerizable liquid crystal compounds obtained is used for measurement in the same manner as when one polymerizable liquid crystal compound is used. In addition, it is known that the liquid crystal phase transition temperature of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition is generally lower than the liquid crystal phase transition temperature of the polymerizable liquid crystal compound as a single body.

The heating time can be appropriately determined according to the heating temperature, the type of polymerizable liquid crystal compound used, the type of solvent, its boiling point and its amount, etc., and is usually 0.5 to 10 minutes, preferably 0.5 to 5 minutes.

The removal of the solvent from the coating can be performed simultaneously with the step of heating to a temperature above the liquid crystal phase transition temperature of the polymerizable liquid crystal compound, or can be performed separately. In order to improve productivity, it is preferably performed simultaneously. A preliminary drying step can also be provided before heating to a temperature above the liquid crystal phase transition temperature of the polymerizable liquid crystal compound. The preliminary drying step is used to properly remove the solvent in the coating without polymerizing the polymerizable liquid crystal compound contained in the coating obtained from the polymerizable liquid crystal composition. As the drying method in the preparatory drying step, natural drying, ventilation drying, heating drying and reduced pressure drying can be listed. The drying temperature (heating temperature) in the drying step can be appropriately determined according to the type of polymerizable liquid crystal compound used, the type of solvent, its boiling point and its amount, etc.

Then, in the obtained dry coating, the alignment state of the polymerizable liquid crystal compound is maintained, and the polymerizable liquid crystal compound is polymerized by light irradiation, thereby forming a polymer of the polymerizable liquid crystal compound in an ideal alignment state, that is, a liquid crystal cured film. As a polymerization method, photopolymerization is generally used. In photopolymerization, the light used to irradiate the dry coating is appropriately selected according to the type of photopolymerization initiator contained in the dry coating, the type of polymerizable liquid crystal compound (especially the type of polymerizable group possessed by the polymerizable liquid crystal compound) and its amount. As a specific example, one or more lights selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α rays, β rays and γ rays, or active energy rays such as active electron beams can be listed. Among them, ultraviolet light is preferred in terms of the ease of controlling the progress of the polymerization reaction and the ability to use a device widely used in the field for photopolymerization. It is preferred to preselect the types of polymerizable liquid crystal compounds and photopolymerization initiators contained in the polymerizable liquid crystal composition so that they can be photopolymerized by ultraviolet light. In addition, during polymerization, the polymerization temperature can be controlled by using appropriate cooling means to cool and dry the coating while irradiating the film with light. If such cooling means are used to polymerize the polymerizable liquid crystal compound at a lower temperature, a liquid crystal cured film can be properly formed even if the heat resistance of the substrate is relatively low. In addition, the polymerization reaction can be promoted by raising the polymerization temperature within a range that does not cause adverse effects (such as deformation of the substrate due to heat) due to heat during light irradiation. During photopolymerization, a patterned cured film can be obtained by masking or developing.

Examples of the light source of the active energy ray 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 Emitting Diode) 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 intensity of ultraviolet irradiation is usually 10 to 3,000 mW/cm ² . The intensity of ultraviolet irradiation is preferably within the wavelength region effective for activation of photopolymerization initiators. The irradiation time is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and further preferably 0.1 second to 1 minute. If the ultraviolet irradiation intensity is used once or multiple times, 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 .

The thickness of the liquid crystal cured film can be appropriately selected according to the type of the liquid crystal cured film, the display device to which it is applied, etc. It is preferably 0.1 to 5 μm, more preferably 0.2 to 4 μm, and even more preferably 0.2 to 3 μm.

A horizontally aligned liquid crystal curing film and/or a vertically aligned liquid crystal curing film may also be formed on the alignment film. The alignment film has an alignment limiting force that allows the polymerizable liquid crystal compound to align the liquid crystal in the desired direction. By forming a liquid crystal curing film using a horizontal alignment film having an alignment limiting force that allows the polymerizable liquid crystal compound to align in the horizontal direction, or a vertical alignment film having an alignment limiting force that allows the polymerizable liquid crystal compound to align in the vertical direction, the polymerizable liquid crystal compound can be aligned in the desired direction with high precision, and a liquid crystal curing film exhibiting excellent optical properties can be obtained when installed in a display device, etc. The alignment limiting force can be arbitrarily adjusted according to the type of alignment film, surface state, or friction conditions, and when the alignment film is formed with a photoalignable polymer, it can be arbitrarily adjusted by polarized light irradiation conditions, etc.

As the alignment film, the following is preferred: having solvent resistance so as not to be dissolved by coating the polymerizable liquid crystal composition, etc., and having heat resistance to the heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound. As the alignment film, there can be listed alignment films including alignment polymers, photo-alignment films, double-alignment films having a concave-convex pattern or a plurality of grooves on the surface, and stretching films extending in the alignment direction. From the perspective of the accuracy and quality of the alignment angle, the photo-alignment film is preferred.

As the alignment polymer, for example, polyamides and gelatins having amide bonds in the molecule, polyimides having imide bonds in the molecule and polyamides as hydrolyzates thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylates can be listed. Among them, polyvinyl alcohol is preferred. The alignment polymer can be used alone or in combination of two or more.

The alignment film containing the alignment polymer is usually obtained by the following method: applying a composition obtained by dissolving the alignment polymer in a solvent (hereinafter also referred to as "alignment polymer composition") to the surface of the substrate film or the like on which the alignment film is to be formed, and removing the solvent; or applying the alignment polymer composition to the substrate, removing the solvent, and rubbing (rubbing method). As the solvent, the same solvents as those exemplified above that can be used for the polymerizable liquid crystal composition can be listed.

The concentration of the alignment polymer in the alignment polymer composition may be within a range that allows the alignment polymer material to be completely dissolved in the solvent, and is preferably 0.1 to 20% relative to the solution in terms of solid content, and more preferably about 0.1 to 10%.

As the alignment polymer composition, a commercially available alignment film material may be used directly. Examples of commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

As a method for applying the aligning polymer composition on a surface of a substrate film or the like on which an alignment film is to be formed, the same methods as those exemplified for applying the polymerizable liquid crystal composition on a substrate film can be cited.

As methods for removing the solvent contained in the alignment polymer composition, there can be listed natural drying method, ventilation drying method, heat drying method and reduced pressure drying method.

In order to impart an alignment restriction force to the alignment film, a friction treatment (friction method) may be performed as needed. As a method of imparting an alignment restriction force by friction method, the following method may be cited: by applying an alignment polymer composition to a substrate and annealing it, a film of an alignment polymer is formed on the surface of the substrate, and the film is brought into contact with a friction roller that is rolled up with a friction cloth and rotates. During the friction treatment, if masking is performed, multiple regions (patterns) with different alignment directions may also be formed on the alignment film.

The photo-alignment film is usually obtained by the following method: a composition comprising a polymer and/or a monomer having a photoreactive group and a solvent (hereinafter also referred to as a "photo-alignment film forming composition") is applied to the surface of the substrate on which the alignment film is to be formed, and after removing the solvent, polarized light (preferably polarized UV (Ultraviolet)) is irradiated. The photo-alignment film is also advantageous in that the direction of the alignment restriction force can be arbitrarily controlled by selecting the polarization direction of the polarized light irradiated.

Photoreactive groups refer to groups that generate liquid crystal alignment energy by light irradiation. Specifically, groups that participate in the photoreactions that are the origin of liquid crystal alignment energy, such as alignment induction or isomerization reaction, dimerization reaction, photocrosslinking reaction or photodecomposition reaction of molecules generated by light irradiation can be listed. Among them, the gene that participates in dimerization reaction or photocrosslinking reaction has excellent alignment and is therefore preferred. As a photoreactive group, a group having an unsaturated bond, especially 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, polyene, stilbene, styrylpyridyl, styrylpyridinium, chalcone, and cinnamyl 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 azophenyl, azonaphthyl, aromatic heterocyclic azo, bisazo, formazan, and groups having an oxyazobenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone, coumarin, anthraquinone, and maleimide groups. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group.

Among them, photoreactive groups that participate in photodimerization reaction are preferred. From the perspective that the amount of polarized light irradiation required for photoalignment is relatively small and a photoalignment film having excellent thermal stability and temporal stability can be easily obtained, photoreactive groups are preferably cinnamyl groups and chalcone groups. In particular, when the liquid crystal cured film is formed of a polymerizable liquid crystal compound having a (meth)acryloyloxy group as a polymerizable group, if a polymer having a cinnamyl group with a cinnamic acid structure at the end of the polymer side chain is used as the polymer having the photoreactive group that forms the alignment film, the adhesion with the liquid crystal cured film can be improved.

The solvent contained in the photo-alignment film-forming composition may be the same solvents as those exemplified above for the polymerizable liquid crystal composition, and may be appropriately selected according to the solubility of the polymer or monomer having a photoreactive group.

The content of the polymer or monomer having a photoreactive group in the photo-alignment film-forming composition can be appropriately adjusted according to the type of the polymer or monomer and the thickness of the target photo-alignment film, but is preferably at least 0.2% by mass, and more preferably in the range of 0.3-10% by mass, relative to the mass of the photo-alignment film-forming composition. The photo-alignment film-forming composition may also include polymer materials such as polyvinyl alcohol and polyimide and photosensitizers within a range that does not significantly damage the properties of the photo-alignment film.

As a method for applying the photo-alignment film-forming composition on the surface where the alignment film is to be formed, the same method as the method for applying the alignment polymer composition can be cited. As a method for removing the solvent from the applied photo-alignment film-forming composition, for example, natural drying method, ventilation drying method, heat drying method and reduced pressure drying method can be cited.

The polarized light irradiation may be performed by directly irradiating the composition for forming a photo-alignment film coated on the substrate after removing the solvent with polarized UV light, or by irradiating the polarized light from the substrate side so that the polarized light is transmitted. In addition, the polarized light is preferably substantially parallel light. The wavelength of the polarized light irradiated is preferably in the wavelength region where the photoreactive group of the polymer or monomer having the photoreactive group can absorb the light energy. Specifically, UV (ultraviolet light) with a wavelength range of 250 to 400 nm is particularly preferred. As the light source used for the polarized light irradiation, there can be listed xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet lasers such as KrF and ArF, etc., and high-pressure mercury lamps, ultra-high-pressure mercury lamps and metal halide lamps are more preferred. Among them, high-pressure mercury lamps, ultra-high-pressure mercury lamps and metal halide lamps are preferred because the light intensity of ultraviolet light with a wavelength of 313 nm is relatively large. Polarized UV can be irradiated by irradiating light from the above light sources through an appropriate polarizing element. As the polarizing element, a polarizing filter, a prism polarizing prism such as a Glen-Thompson prism or a Glen-Taylor prism, or a wire-grid type polarizing element can be used.

Furthermore, if shielding is performed during irradiation, friction or polarized light irradiation, multiple regions (patterns) with different liquid crystal alignment directions can also be formed.

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

As a method for obtaining a groove alignment film, the following methods can be listed: after exposing the surface of a photosensitive polyimide film through an exposure mask having narrow slits in the shape of a pattern, developing and rinsing are performed to form a concave-convex pattern; a layer of a UV-curable resin before curing is formed on a plate-shaped master having grooves on the surface, and the formed resin layer is transferred to a substrate, etc. and then cured; and a film of a UV-curable resin before curing is formed by pressing a roller-shaped master having a plurality of grooves against the surface on which the alignment film is to be formed to form concave-convex, and then curing; etc.

The thickness of the alignment film (including the alignment film of the alignment polymer or the photo-alignment film) is usually in the range of 10 to 10000 nm, preferably in the range of 10 to 2500 nm, more preferably below 10 to 1000 nm, further preferably 10 to 500 nm, and particularly preferably 50 to 250 nm.

In the laminate of the present invention, as long as a layer having a refractive index that satisfies the formula (1) with respect to the in-plane refractive index of the vertically aligned liquid crystal curing film can be formed, the adhesive forming the adhesive layer between the horizontally aligned liquid crystal curing film and the vertically aligned liquid crystal curing film is not particularly limited. For example, a previously known adhesive in the field of optical films can be used.

In the present invention, in order to improve the optical properties, it is preferred to control the phase difference value of the vertical alignment liquid crystal cured film constituting the laminate within a specific range such as the above formula (5), and accordingly, the refractive index of the vertical alignment liquid crystal cured film also becomes a specific range. Therefore, when controlling the difference between the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertical alignment liquid crystal cured film such as satisfying formula (1), it is preferred to adjust the in-plane phase difference value of the adhesive layer to be close to the in-plane refractive index of the vertical alignment liquid crystal cured film.

As adhesives, for example, chemical reaction adhesives, dry curing adhesives, and pressure sensitive adhesives can be listed. As chemical reaction adhesives, for example, active energy ray curing adhesives can be listed. In one form of the present invention, the adhesive forming the adhesive layer is preferably an active energy ray curing adhesive.

Active energy ray-curable adhesives are adhesives that are cured by exposure to active energy rays. Active energy ray-curable adhesives can be classified according to their curing methods, such as cationic polymerizable adhesives containing cationic polymerizable compounds as curable compounds, free radical polymerizable adhesives containing free radical polymerizable compounds as curable compounds, and mixed curable adhesives containing both cationic polymerizable compounds and free radical polymerizable compounds. Specific examples of cationic polymerizable compounds include epoxy compounds having one or more epoxy groups in the molecule, oxycyclobutane compounds having one or more oxycyclobutane rings in the molecule, and vinyl compounds. Specific examples of free radical polymerizable compounds include (meth)acrylic acid compounds and vinyl compounds having one or more (meth)acryloyl groups in the molecule. The active energy ray-curable adhesive may contain one or more cationic polymerizable compounds and/or one or more free radical polymerizable compounds.

The cationic polymerizable compound as the main component of the cationic polymerizable adhesive refers to a compound or oligomer that is cured by cationic polymerization reaction by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, or heating, and examples thereof include epoxy compounds, cyclohexane compounds, vinyl compounds, etc. Among them, the preferred cationic polymerizable compound is an epoxy compound.

The epoxy compound is a compound having one or more, preferably two or more, epoxy groups in the molecule. The epoxy compound may be used alone or in combination of two or more. Examples of the epoxy compound include aliphatic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, aliphatic epoxy compounds, and the like.

Alicyclic epoxy compounds are compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule. Specifically, examples thereof include 3',4'-epoxycyclohexanecarboxylic acid 3,4-epoxycyclohexylmethyl ester, 3,4-epoxy-6-methylcyclohexanecarboxylic acid 3,4-epoxy-6-methylcyclohexanecarboxylic acid methyl ester, ethylenebis(3,4-epoxycyclohexanecarboxylate), bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, diethylene glycol bis(3,4-epoxycyclohexylmethyl ether) , ethylene glycol bis(3,4-epoxycyclohexyl methyl ether), 2,3,14,15-dicyclooxy-7,11,18,21-tetraoxatrispiro[5.2.2.5.2.2]heneicosane, 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane, 4-ethylenecyclohexene dioxide, limonene dioxide, bis(2,3-epoxycyclopentyl) ether, dicyclopentadiene dioxide.

Aromatic epoxy compounds are compounds having an aromatic ring and an epoxy group in the molecule. Specific examples thereof include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S, or oligomers thereof; novolac-type epoxy resins such as phenol-based novolac epoxy resins, cresol novolac epoxy resins, and hydroxybenzaldehyde phenol-based novolac epoxy resins; polyfunctional epoxy compounds such as glycidyl ether of 2,2',4,4'-tetrahydroxydiphenylmethane and glycidyl ether of 2,2',4,4'-tetrahydroxybenzophenone; and polyfunctional epoxy resins such as epoxidized polyvinyl phenol.

The hydrogenated epoxy compound may be a glycidyl ether of a polyol having an alicyclic ring, and the aromatic ring of an aromatic polyol is selectively hydrogenated under pressure in the presence of a catalyst to obtain a core hydrogenated polyhydroxy compound, and the core hydrogenated polyhydroxy compound is glycidyl etherified to obtain the glycidyl ether of the polyol having an alicyclic ring. Specific examples of aromatic polyols include bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac-type resins such as phenol novolac resins, cresol novolac resins, and hydroxybenzaldehyde phenol novolac resins; and polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. Glycidyl ethers can be obtained by reacting epichlorohydrin with alicyclic polyols obtained by hydrogenating the aromatic rings of aromatic polyols.

Aliphatic epoxy compounds are compounds that have at least one oxirane ring (three-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule. Examples include monofunctional epoxy compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; bifunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trifunctional or higher epoxy compounds such as trihydroxymethyl triglycidyl ether and neopentyltriol tetraglycidyl ether; and epoxy compounds having one oxirane ring directly bonded to an aliphatic cyclic ring and an oxirane ring bonded to an aliphatic carbon atom, such as 4-ethylenedioxycyclohexene and limonene dioxide.

Oxycyclobutane compounds, which are one type of cationically polymerizable compounds, are compounds containing one or more oxycyclobutane rings (oxycyclobutyl groups) in the molecule. Specifically, for example, 3-ethyl-3-hydroxymethylcyclohexyloxybutane (also called cyclohexyloxybutane alcohol), 2-ethylhexylcyclohexyloxybutane, 1,4-bis[{(3-ethylcyclohexyloxybutane-3-yl)methoxy}methyl]benzene (also called xylyldicyclohexyloxybutane), 3-ethyl-3[{(3-ethylcyclohexyloxybutane-3-yl)methoxy}methyl]cyclohexyloxybutane, 3-ethyl-3-(phenoxymethyl)cyclohexyloxybutane, 3-(cyclohexyloxy)methyl-3-ethylcyclohexyloxybutane. The cyclohexyloxybutane compound can be used as a main component of a cationically polymerizable compound, and can also be used in combination with an epoxy compound.

Examples of vinyl compounds that can become cationically polymerizable compounds include aliphatic or alicyclic vinyl ether compounds, and specific examples thereof include vinyl ethers of alkyl or alkenyl alcohols having 5 to 20 carbon atoms, such as n-pentyl vinyl ether, isopentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, and oleyl vinyl ether; vinyl ethers containing a hydroxyl group, such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, and 4-hydroxybutyl vinyl ether; vinyl ethers of monoalcohols having an aliphatic ring or an aromatic ring, such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, and benzyl vinyl ether; vinyl ethers of glycerol monovinyl ether, 1, Mono- to polyethylene ethers of polyvalent alcohols such as 4-butanediol monovinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol tetravinyl ether, trihydroxymethyl divinyl ether, trihydroxymethyl trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethylcyclohexane monovinyl ether, and 1,4-dihydroxymethylcyclohexane divinyl ether; polyalkylene glycol mono- to divinyl ethers such as diethylene glycol divinyl ether, triethylene glycol divinyl ether, and diethylene glycol monobutyl monovinyl ether; other vinyl ethers such as glycidyl vinyl ether and ethylene glycol vinyl ether methacrylate. The vinyl compound can be used as the main component of the cationically polymerizable compound, and can also be used in combination with an epoxy compound, or an epoxy compound and an oxycyclobutane compound.

By appropriately selecting the type, combination, and content of the cationically polymerizable compound as the main component, the in-plane refractive index of the adhesive layer formed by the active energy radiation curing adhesive containing the cationically polymerizable compound can be controlled within a desired range. For example, by including an aromatic epoxy compound or an alicyclic epoxy compound, the in-plane refractive index of the obtained adhesive layer tends to be higher. For example, by including an aliphatic epoxy compound, an oxycyclobutane compound, or an ethylene compound, the in-plane refractive index of the obtained adhesive layer tends to be lower. By appropriately combining such a compound having a tendency for the in-plane refractive index to become higher and a compound having a tendency for the in-plane refractive index to become lower, the in-plane refractive index of the obtained adhesive layer can be easily controlled within a desired range.

The content of the cationic polymerizable compound in the cationic polymerizable adhesive is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more, relative to 100% by mass of the total amount of the curable compound contained in the cationic polymerizable adhesive (including the case of a mixed curable adhesive). Furthermore, when the cationic polymerizable adhesive contains two or more cationic polymerizable compounds, it is preferred that the total amount thereof is within the above range.

When the active energy ray-curing adhesive contains a cationic polymerizable compound, it is preferred to contain a photo-cationic polymerization initiator. The photo-cationic polymerization initiator generates cationic species or Lewis acid by irradiating active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of the cationic curable compound. The photo-cationic polymerization initiator acts as a catalyst under the action of light, so even if it is mixed with a photo-cationic polymerizable compound, the storage stability and workability are still excellent. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic stibnium salts, aromatic diazonium salts, and iron-aromatic complexes.

An aromatic iodine salt is a compound having a diaryl iodine cation, and a typical example of the cation is diphenyl iodine cation. An aromatic siron salt is a compound having a triaryl siron cation, and a typical example of the cation is triphenyl siron cation, 4,4'-bis(diphenyl dihydrosulfide) diphenyl sulfide cation, etc. An aromatic diazonium salt is a compound having a diazonium cation, and a typical example of the cation is benzene diazonium cation. In addition, a typical example of the iron-arene complex is cyclopentadienyl iron (II) arene cation complex.

The cations and anions shown above form pairs to form photocationic polymerization initiators. Examples of anions constituting photocationic polymerization initiators include special phosphorus anions [(Rf) _n PF _{6 - n} ] ^- , hexafluorophosphate anions PF ₆ ^- , hexafluoroantimonate anions SbF ₆ ^- , pentafluorohydroxyantimonate anions SbF ₅ (OH) ^- , hexafluoroarsenate anions AsF ₆ ^- , tetrafluoroborate anions BF ₄ ^- , tetrakis(pentafluorophenyl)borate anions B(C ₆ F ₅ ) ₄ ^- , and the like. Among them, from the viewpoint of the curability of the cationic polymerizable compound and the safety of the obtained adhesive layer, the special phosphorus anion [(Rf) _n PF _6-n ] ^- and the hexafluorophosphate anion PF ₆ ^- are preferred.

Photocatalytic ion polymerization initiators can be used alone or in combination of two or more. Among them, aromatic stibnium salts also have ultraviolet absorption characteristics in the wavelength region around 300 nm, so they can provide a cured product with excellent curability, good mechanical strength and adhesion strength, so they are suitable for use.

The amount of the photopolymerization initiator in the cationic polymerizable adhesive (solid content) is usually 0.5 to 10 parts by mass, preferably 6 parts by mass or less, relative to 100 parts by mass of the cationic polymerizable compound. If the content of the photopolymerization initiator is within the above range, the cationic polymerizable compound can be fully cured.

A mixed adhesive can also be prepared by adding a radical polymerizable compound in addition to a cationically polymerizable compound. Sometimes, by using a radical polymerizable compound together, it is easy to adjust the in-plane refractive index of the adhesive layer.

The free radical polymerizable compound as the main component of the free radical polymerizable adhesive refers to a compound or oligomer that is cured by free radical polymerization reaction by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, or heating, and specifically includes compounds having ethylenic unsaturated bonds. As compounds having ethylenic unsaturated bonds, in addition to (meth)acrylic compounds having one or more (meth)acrylic groups in the molecule, vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone can also be listed. These can be used alone or in combination of two or more.

Examples of (meth)acrylic compounds include (meth)acrylic acid ester oligomers having at least two (meth)acrylic acid groups in the molecule, and other (meth)acrylic acid ester oligomers, which are obtained by reacting two or more of a (meth)acrylic acid ester monomer having at least one (meth)acryloxy group in the molecule, a (meth)acrylamide monomer, and a functional group-containing compound. The (meth)acrylic acid ester oligomer is preferably a (meth)acrylic acid ester oligomer having at least two (meth)acryloxy groups in the molecule.

When the active energy ray-curing adhesive contains a radical polymerizable compound, it is preferred to contain a photo radical polymerization initiator. The photo radical polymerization initiator initiates the polymerization reaction of the radical curable compound by irradiating active energy rays such as visible light, ultraviolet light, X-rays, or electron beams. The photo radical polymerization initiator may be used alone or in combination of two or more.

Specific examples of the photo-radical polymerization initiator include acetophenone-based initiators such as acetophenone, 3-methylacetophenone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-methyl-1-[4-(methylthio)phenyl-2-morpholinylpropane-1-one, and 2-hydroxy-2-methyl-1-phenylpropane-1-one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; 4-isopropyl 9-oxysulfonate; 9-Oxysulfuron It is an initiator; as well as phenanthene, anthraquinone, camphorquinone, benzaldehyde, and anthraquinone.

The amount of the photo-radical polymerization initiator in the radical polymerization type adhesive is generally 0.5 to 20 parts by mass, preferably 1 to 6 parts by mass, relative to 100 parts by mass of the radical polymerizable compound. If the amount of the photo-radical polymerization initiator is within the above range, the radical polymerizable compound can be sufficiently cured.

The active energy ray-curable adhesive may contain additives such as cyclohexane, polyol and other cationic polymerization accelerators, photosensitizers, ion scavengers, antioxidants, chain transfer agents, adhesion promoters, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, antistatic agents, leveling agents, and/or solvents as needed.

When an active energy ray-curing adhesive is used, the active energy ray-curing adhesive is cured by irradiating the active energy ray to obtain an adhesive layer. The light source of the active energy ray is not particularly limited, but preferably active energy ray having a luminescence distribution below a wavelength of 400 nm, and more preferably ultraviolet light. Specific examples of the light source include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

There is no particular limitation on the light irradiation intensity of the active energy ray-curable adhesive, and it is appropriately determined according to the composition of the active energy ray-curable adhesive. The irradiation intensity in the wavelength region effective for activating the polymerization initiator is usually 10 to 3,000 mW/cm ² . There is no particular limitation on the light irradiation time of the active energy ray-curable adhesive, and it can be appropriately selected according to the active energy ray-curable adhesive to be cured. It is usually 0.1 second to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating with such ultraviolet irradiation intensity once or multiple times, the cumulative light amount is usually 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 .

Examples of dry curing adhesives include polymers of monomers having protonic functional groups such as hydroxyl, carboxyl or amine groups and ethylenically unsaturated groups; or compositions containing urethane resins as main components and further containing crosslinking agents or curing compounds such as polyvalent aldehydes, epoxy compounds, epoxy resins, melamine compounds, zirconium oxide compounds, and zinc compounds. Examples of polymers of monomers having protonic functional groups such as hydroxyl, carboxyl or amine groups and ethylenically unsaturated groups include ethylene-maleic acid copolymers, itaconic acid copolymers, acrylic acid copolymers, acrylamide copolymers, saponified polyvinyl acetate, and polyvinyl alcohol resins.

Examples of polyvinyl alcohol resins include polyvinyl alcohol, partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetylacetyl-modified polyvinyl alcohol, hydroxymethyl-modified polyvinyl alcohol, and amino-modified polyvinyl alcohol. The content of polyvinyl alcohol resin in a water-based dry curing adhesive is generally 1 to 10 parts by mass, preferably 1 to 5 parts by mass, relative to 100 parts by mass of water.

As urethane resins, polyester-based ionic polymer urethane resins and the like can be cited. The polyester-based ionic polymer urethane resins herein refer to urethane resins having a polyester skeleton and into which a small amount of ionic components (hydrophilic components) are introduced. The ionic polymer urethane resins can be emulsified into an emulsion in water without using an emulsifier, and thus can be used as a water-based adhesive. When using polyester-based ionic polymer urethane resins, it is more effective to prepare a water-soluble epoxy compound as a crosslinking agent.

Examples of epoxy resins include polyamide epoxy resins, which are obtained by reacting polyalkylene polyamines such as diethylenetriamine or triethylenetetramine with dicarboxylic acids such as adipic acid to obtain polyamide polyamines, and then reacting the polyamide polyamines with epichlorohydrin. Examples of commercially available polyamide epoxy resins include "Sumirez Resin (registered trademark) 650" and "Sumirez Resin 675" (both manufactured by Sumika Chemtex Co., Ltd.), "WS-525" (manufactured by Japan PMC Co., Ltd.), and the like. When preparing epoxy resin, the addition amount is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass, relative to 100 parts by mass of polyvinyl alcohol resin.

The dry curing adhesive may contain a solvent. Examples of the solvent include water, a mixed solvent of water and a hydrophilic organic solvent (e.g., an alcohol solvent, an ether solvent, an ester solvent, etc.), and an organic solvent. Examples of adhesive components include adhesives containing polyvinyl alcohol resins or urethane resins.

When a dry curing adhesive is used, the adhesive layer can be obtained by drying and curing the coating of the dry curing adhesive. For example, the drying process can be performed by blowing hot air, and the temperature varies depending on the type of solvent, but is usually 30 to 200°C, preferably 35 to 150°C, more preferably 40 to 100°C, and further preferably in the range of 60 to 100°C. In addition, the drying time is usually about 10 seconds to 30 minutes.

Pressure-sensitive adhesives usually contain polymers and may contain solvents. Examples of polymers include acrylic polymers, polysilicone polymers, polyesters, polyurethanes, or polyethers. Among them, acrylic adhesives containing acrylic polymers are preferred because they have excellent optical transparency and are easy to improve adhesion and heat resistance.

The acrylic polymer is preferably a copolymer of a (meth)acrylate in which the alkyl group of the ester part is an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl or butyl, and a (meth)acrylic monomer having a functional group, such as (meth)acrylic acid or (meth)hydroxyethyl acrylate. The glass transition temperature of the acrylic polymer is preferably below 25°C, more preferably below 0°C. The mass average molecular weight of such an acrylic polymer is preferably above 100,000.

As the solvent, the solvents listed above that can be used in polymerizable liquid crystal compositions, etc. can be cited. The pressure-sensitive adhesive can also contain a light diffuser. The light diffuser is an additive that imparts light diffusion to the adhesive, and can be microparticles having a refractive index different from that of the polymer contained in the adhesive. As the light diffuser, microparticles containing inorganic compounds and microparticles containing organic compounds (polymers) can be cited. Most polymers contained in adhesives as active ingredients, including acrylic polymers, have a refractive index of about 1.4 to 1.6, so it is better to choose a light diffuser with a refractive index of 1.2 to 1.8. The difference in refractive index between the polymer contained as an active ingredient of the adhesive and the light diffuser is usually 0.01 or more, and preferably 0.01 to 0.2 from the viewpoint of brightness and display performance of the display device. The microparticles used as the light diffuser are preferably spherical and nearly monodisperse microparticles, and more preferably microparticles with an average particle size of 2 to 6 μm. The refractive index is measured by the usual minimum deviation angle method or Abbe refractometer.

Examples of microparticles containing inorganic compounds include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of microparticles containing organic compounds (polymers) include melamine particles (refractive index 1.57), polymethyl methacrylate particles (refractive index 1.49), methyl methacrylate/styrene copolymer resin particles (refractive index 1.50-1.59), polycarbonate particles (refractive index 1.55), polyethylene particles (refractive index 1.53), polystyrene particles (refractive index 1.6), polyvinyl chloride particles (refractive index 1.46), and polysilicone resin particles (refractive index 1.46). The content of the light diffuser is usually 3-30 parts by mass relative to 100 parts by mass of the polymer.

The thickness of the adhesive layer can be appropriately determined according to the type of adhesive constituting the adhesive layer, the desired adhesive strength, etc., and is usually 0.01 μm to 20 μm, preferably 0.05 μm to 0.1 μm, and particularly preferably 0.2 μm to 20 μm, and further preferably 10 μm to 5 μm, particularly preferably 2 μm to 2 μm, and particularly preferably 1.5 μm to 1.5 μm. Generally, there is a tendency that the thinner the thickness of the adhesive layer between the horizontal alignment liquid crystal curing film and the vertical alignment liquid crystal curing film, the easier it is for the interface reflection generated at the interface between the horizontal alignment liquid crystal curing film and the adhesive layer and the interface reflection generated at the interface between the vertical alignment liquid crystal curing film and the adhesive layer to interfere with each other, and the easier it is for interference spots to be generated. Even in such a case, the multilayer body of the present invention makes the difference between the in-plane refractive index of the vertical alignment liquid crystal curing film and the in-plane refractive index of the adhesive layer smaller, thereby suppressing the reflection generated at the interface between the vertical alignment liquid crystal curing film and the adhesive layer. Therefore, even if the thickness of the adhesive layer is thinned, the generation of interference spots can be effectively suppressed, which is advantageous. Therefore, in a preferred embodiment of the present invention, the thickness of the adhesive layer is preferably 0.1 μm to 2 μm, and more preferably 0.2 μm to 1.5 μm. If the thickness of the adhesive layer is within the above range, interference spots are less likely to be generated, and high adhesion can be ensured while achieving thinning of the laminate.

The laminate of the present invention can be manufactured, for example, by laminating (bonding) a horizontal alignment liquid crystal cured film and a vertical alignment liquid crystal cured film via the adhesive layer.

The present invention includes an elliptical polarizing plate including the multilayer body of the present invention and a polarizing film. The polarizing film is a film having a polarizing function, and examples thereof include a stretched film adsorbed with a pigment having anisotropy of absorption, a film coated with a pigment having anisotropy of absorption, etc. As a pigment having anisotropy of absorption, for example, a dichroic pigment can be cited.

A film including a stretched film adsorbed with a dye having absorption anisotropy as a polarizing element is usually produced by sandwiching the polarizing element with a transparent protective film via an adhesive on at least one side of the polarizing element. The polarizing element is produced by the following steps: uniaxially stretching a polyvinyl alcohol resin film; dyeing the polyvinyl alcohol resin film with a dichroic dye so that the dichroic dye is adsorbed; treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution; and washing with water after the treatment with the aqueous boric acid solution.

Polyvinyl alcohol resins are obtained by saponifying polyvinyl acetate resins. As polyvinyl acetate resins, in addition to polyvinyl acetate which is a single polymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith can be used. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of polyvinyl alcohol resin is usually about 85-100 mol%, preferably 98 mol% or more. Polyvinyl alcohol resin can also be modified, for example, polyvinyl formal and polyvinyl acetaldehyde modified with aldehydes can also be used. The polymerization degree of polyvinyl alcohol resin is usually about 1,000-10,000, preferably in the range of 1,500-5,000.

The polyvinyl alcohol resin is used as a film for a polarizing film. The method for forming the polyvinyl alcohol resin is not particularly limited, and the film can be formed by a known method. The film thickness of the polyvinyl alcohol film can be set to about 10 to 150 μm, for example.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before dyeing with a dichroic dye, can be performed simultaneously with dyeing, or can be performed after dyeing. When the uniaxial stretching is performed after dyeing, the uniaxial stretching can be performed before the boric acid treatment or during the boric acid treatment. In addition, the uniaxial stretching can be performed in these multiple stages. During the uniaxial stretching, the uniaxial stretching can be performed between rollers with different peripheral speeds, or can be performed using hot rollers. In addition, the uniaxial stretching can be dry stretching performed in the atmosphere, or can be wet stretching performed using a solvent to moisten the polyvinyl alcohol resin film. The stretching ratio is usually about 3 to 8 times.

The polyvinyl alcohol-based resin film is dyed with a dichroic dye by, for example, immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye.

As the dichroic pigment, iodine or dichroic organic dyes can be used specifically. As dichroic organic dyes, dichroic direct dyes containing disazo compounds such as C.I. DIRECT RED 39 and dichroic direct dyes containing trisazo, tetrakisazo and the like can be cited. The polyvinyl alcohol resin film is preferably immersed in water before dyeing.

When iodine is used as a dichroic pigment, a method of dyeing a polyvinyl alcohol-based resin film by immersing it in an aqueous solution containing iodine and potassium iodide is generally adopted. The content of iodine in the aqueous solution is generally about 0.01 to 1 mass part per 100 mass parts of water. In addition, the content of potassium iodide is generally about 0.5 to 20 mass parts per 100 mass parts of water. The temperature of the aqueous solution used for dyeing is generally about 20 to 40°C. In addition, the time of immersion in the aqueous solution (dyeing time) is generally about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as a dichroic pigment, a method of dyeing by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is generally adopted. The content of the dichroic organic dye in the aqueous solution is generally about 1×10 ^-4 to 10 parts by mass, preferably 1×10 ^-3 to 1 part by mass, and further preferably 1×10 ^-3 to 1×10 ^-2 parts by mass per 100 parts by mass of water. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The temperature of the dichroic dye aqueous solution used for dyeing is generally about 20 to 80°C. In addition, the time of immersion in the aqueous solution (dyeing time) is generally about 10 to 1,800 seconds.

The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The content of boric acid in the aqueous boric acid solution is usually about 2 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. When iodine is used as the dichroic dye, it is preferred that the aqueous boric acid solution contains potassium iodide, in which case the content of potassium iodide is usually about 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. The immersion time in the aqueous boric acid solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and further preferably 200 to 400 seconds. The temperature of the boric acid treatment is usually above 50°C, preferably 50-85°C, and further preferably 60-80°C.

The polyvinyl alcohol resin film treated with boric acid is usually washed with water. The washing treatment can be performed, for example, by immersing the polyvinyl alcohol resin film treated with boric acid in water. The temperature of the water in the washing treatment is usually about 5 to 40°C. The immersion time is usually about 1 to 120 seconds.

After washing, drying treatment is performed to obtain a polarizing element. Drying treatment can be performed, for example, using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually around 30 to 100°C, preferably 50 to 80°C. The time of the drying treatment is usually around 60 to 600 seconds, preferably 120 to 600 seconds. The moisture content of the polarizing element is reduced to a practical level by drying treatment. Its moisture content is usually around 5 to 20% by mass, preferably 8 to 15% by mass. If the moisture content is within the above range, a polarizing element with moderate flexibility and excellent thermal stability can be obtained.

In this way, the thickness of the polarizing element obtained by uniaxially stretching the polyvinyl alcohol-based resin film, dyeing with a dichroic dye, treating with boric acid, washing with water and drying is preferably 5 to 40 μm.

As the film coated with the dye having absorption anisotropy, there can be cited a film obtained by coating a composition of a dichroic dye having liquid crystal properties, or a composition containing a dichroic dye and polymerizable liquid crystal. The film preferably has a protective film on one or both sides thereof. As the protective film, there can be cited the same resin film as exemplified above as a substrate that can be used to manufacture a horizontal alignment liquid crystal cured film.

The film coated with the dye having absorption anisotropy is preferably thin, but if it is too thin, the strength tends to decrease and the processability tends to deteriorate. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm.

Specific examples of the film coated with the dye having absorption anisotropy include films described in Japanese Patent Application Laid-Open No. 2012-33249 and the like.

A polarizing film is obtained by laminating a transparent protective film on at least one side of the polarizing element obtained in this way via an adhesive. As the transparent protective film, the same transparent film as the resin film exemplified above as a substrate for manufacturing a horizontal alignment liquid crystal cured film can be preferably used.

The elliptical polarizing plate of the present invention is composed of the laminate and polarizing film of the present invention. For example, the laminate and polarizing film of the present invention are laminated via an adhesive layer to obtain the elliptical polarizing plate of the present invention. As the adhesive layer, an adhesive previously known in the field can be used, for example, the same adhesive as the adhesive that can be used for laminating the horizontal alignment liquid crystal curing film and the vertical alignment liquid crystal curing film as exemplified above.

In one aspect of the present invention, when laminating the laminate and the polarizing film, it is preferred that the lamination be performed in such a manner that the angle between the retardation axis (optical axis) of the horizontal alignment liquid crystal cured film constituting the laminate and the absorption axis of the polarizing film becomes 45±5°.

The elliptical polarizing plate of the present invention may have a structure similar to that of a conventional elliptical polarizing plate, or a polarizing film and a phase difference film. Examples of such a structure include an adhesive layer (sheet) for attaching the elliptical polarizing plate to a display element such as an organic EL, and a protective film for protecting the surface of the polarizing film or the phase difference film from damage or contamination.

The elliptical polarizing plate of the present invention can be used in various display devices. A display device refers to a device having a display element, including a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal display devices, organic electroluminescent (EL) display devices, inorganic electroluminescent (EL) display devices, touch panel display devices, electron emission display devices (such as field effect emission display devices (FED), surface electric field emission display devices (SED)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (such as grating valve imaging system (GLV) display devices, display devices with digital micromirror devices (DMD)) and piezoelectric ceramic displays. Liquid crystal display devices include any of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device. Such display devices may be display devices for displaying two-dimensional images, or may be stereoscopic display devices for displaying three-dimensional images. In particular, the elliptical polarizing plate of the present invention may be preferably used in organic electroluminescent (EL) display devices and inorganic electroluminescent (EL) display devices, and the multilayer of the present invention may be preferably used in liquid crystal display devices and touch panel display devices. Such display devices may exhibit good image display characteristics by having the multilayer of the present invention which is not prone to generating interference fringes. [Example]

Hereinafter, the present invention will be described in more detail by way of examples. In addition, "%" and "parts" in the examples mean mass % and mass parts, respectively, unless otherwise specified.

1. Preparation of adhesives (1) Preparation of active energy ray-curable adhesives According to the composition shown in Table 1 (the units in Table 1 are parts by mass), a cationic polymerizable compound (monomers (A-1) to (A-6)) and a cationic polymerization initiator were mixed and defoamed to prepare active energy ray-curable adhesives A to F. The monomers (A-1) to (A-6) of the cationic polymerizable compound were the components shown below, respectively, and the cationic polymerization initiator (B) was prepared into a 50 mass% propylene carbonate solution, and the solid content thereof is shown in Table 1.

<Cationically polymerizable compound (monomer)> A-1: 3',4'-epoxycyclohexylmethyl 3,4-Epoxyhexanecarboxylate (Trade name: CEL2021P, manufactured by Daicell) A-2: 1,6-Hexanediol diglycidyl ether (Trade name: EX-212L, manufactured by Nagase Chemicals) A-3: 4-Hydroxybutylvinyl ether (Trade name: HBVE, manufactured by Maruzen Petrochemicals) A-4: tert-butylphenyl glycidyl ether (Trade name: EX-146, manufactured by Nagase Chemicals) A-5: Bisphenol F type epoxy resin (Trade name: EXA-830CRP, manufactured by DIC) A-6: 2-Ethylhexyl glycidyl ether (Trade name: EX-121, manufactured by Nagase Chemicals)

<Cationic polymerization initiator> B: Cationic polymerization initiator (trade name: CPI-100P, manufactured by San-Apro Co., Ltd., 50 mass% solution)

[Table 1] Cationic polymerizable compounds (monomers) Cationic polymerization initiator Refractive index of hardened material n2 A-1 A-2 A-3 A-4 A-5 A-6 B Follow-up agent A 30 45 25 3 1.49 Follow-up agent B 55 30 15 3 1.51 Followed by Agent C 60 20 20 3 1.53 Follow-up agent D 25 10 65 3 1.56 Followed by E 55 45 3 1.46 Followed by agent F 30 70 3 1.59

(2) Refractive index measurement method The adhesives A to F prepared above were applied to one side of a cycloolefin polymer film (COP: ZF-14 manufactured by Japan Zeon Co., Ltd.) using a rod coater [manufactured by Daiichi Rika Co., Ltd.], and irradiated with ultraviolet light at a cumulative light dose of 600 mJ/ ^cm2 (UV-B) using an ultraviolet irradiation device [manufactured by Fusion UV Systems Co., Ltd.] to obtain a cured product. The thickness of the cured product was measured by a contact film thickness meter based on the difference in thickness from the cycloolefin polymer film, and the result was about 30 μm. The COP was peeled off from the cured product, and the refractive index n2 (589 nm) of the cured product was measured at 25°C using a multi-wavelength Abbe refractometer ["DR-M4" manufactured by Atago Co., Ltd.]. The results are shown in Table 1.

2. Preparation of a composition for forming a vertically aligned liquid crystal curing film (1) Preparation of a composition 1 for forming a vertically aligned liquid crystal curing film The components were mixed according to the composition described in Table 2, and the resulting solution was stirred at 80°C for 1 hour and then cooled to room temperature to prepare a composition 1 for forming a vertically aligned liquid crystal curing film. In addition, the components in Table 2 are the components shown below, and the mixing amount represents the mixing ratio of each component relative to the total amount of the prepared composition.

[Table 2] Vertically aligned liquid crystal cured film forming composition 1 Polymerizable liquid crystal compounds Polymerization initiator Leveling agent Reactive Additives Solvent Ingredient Name LC242 Irg907 BYK-361N LR-9000 PGMEA Quality% 19.2% 0.5% 0.1% 1.1% 79.1%

Irg907: Cationic polymerization initiator [Irgacure907 (manufactured by BASF Japan)] BYK-361N: Leveling agent (manufactured by BYK-Chemie Japan) LR-9000: Reactive additive [Laromer (registered trademark) LR-9000 (manufactured by BASF Japan)] PGMEA: Solvent (propylene glycol 1-monomethyl ether 2-acetate) LC242: Polymerizable liquid crystal compound [Polymerizable liquid crystal compound represented by the following formula (manufactured by BASF)]

(2) Preparation of the composition 1 for forming a horizontally aligned liquid crystal cured film and the composition 2 for forming a vertically aligned liquid crystal cured film The polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B shown below were mixed at a mass ratio of 90:10, and 1 part by mass of a leveling agent (F-556; manufactured by DIC Corporation) and 6 parts by mass of a polymerization initiator 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one ("Irgacure 369 (Irg369)", manufactured by BASF Japan Co., Ltd.) were added to the resulting mixture.

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 horizontal alignment liquid crystal cured film forming composition 1 and a vertical alignment liquid crystal cured film forming composition 2.

The polymerizable liquid crystal compound A was prepared according to the method described in Japanese Patent Application Laid-Open No. 2010-31223. The polymerizable liquid crystal compound B was prepared according to the method described in Japanese Patent Application Laid-Open No. 2009-173893. The molecular structures of each are shown below.

Polymerizable liquid crystal compound A

Polymerizable liquid crystal compound B

3. Preparation of composition for forming an alignment film (1) Preparation of composition 1 for forming a vertical alignment film To 1 part by weight (in terms of solid content) of a commercially available alignment polymer Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.), 99 parts by weight of 2-butoxyethanol was added to obtain a composition for forming a vertical alignment film. The solid content of SE-610 was calculated based on the concentration stated in the delivery specification.

(2) Preparation of composition 2 for forming a vertical alignment film The silane coupling agent "KBE-9103" manufactured by Shin-Etsu Chemical Co., Ltd. was dissolved in a mixed solvent of ethanol and water at a ratio of 9:1 (mass ratio) to obtain a composition for forming a vertical alignment film having a solid content of 0.5%.

(3) Preparation of a composition for forming a horizontal alignment film 5 parts by weight of a photo-alignment material having the following structure (weight average molecular weight: 30,000) and 95 parts by weight 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.

4. Production of polarizing film Use dry stretching to uniaxially stretch a 30 μm thick polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) to about 5 times, and then keep the tension state and immerse it in pure water at 40°C for 40 seconds. Then, immerse it in a dyeing aqueous solution with a mass ratio of iodine/potassium iodide/water of 0.044/5.7/100 at 28°C for 30 seconds for dyeing treatment. Next, immerse it in a boric acid aqueous solution with a mass ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70°C for 120 seconds. Then, after washing with pure water at 8°C for 15 seconds, the film was dried at 60°C for 50 seconds while maintaining a tension of 300 N, and then dried at 75°C for 20 seconds to obtain a polarizing element with a thickness of 12 μm and iodine adsorbed and aligned on a polyvinyl alcohol film. The obtained polarizing element was laminated with rollers in the following manner: a film obtained by saponification of triacetyl cellulose film (TAC; KC2UA; manufactured by Konica Minolta Co., Ltd., thickness: 25 μm) was laminated on one side as a transparent protective layer on the front surface, and a cycloolefin polymer film (COP: ZF-14 manufactured by Japan Zeon Co., Ltd.) with a phase difference value of almost 0 at a wavelength of 550 nm after corona treatment was laminated on the other side, and a water-based adhesive prepared in such a way that the thickness of the obtained adhesive layer became 50 nm was injected in between. The tension of the obtained laminate was maintained at 430 N/m, and dried at 60°C for 2 minutes, to obtain a polarizing film having TAC as a transparent protective film on one side and COP on the other side. Furthermore, the water-based adhesive was prepared by adding 3 parts by weight of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318 manufactured by Kuraray) and 1.5 parts by weight of water-soluble polyamide epoxy resin (Sumirez Resin 650 manufactured by Sumika Chemtex, a 30% solid content aqueous solution) to 100 parts by weight of water.

5. Preparation of a laminate comprising a substrate, a horizontal alignment film, and a horizontal alignment liquid crystal cured film (1) Preparation of a laminate comprising a substrate, a horizontal alignment film, and a horizontal alignment liquid crystal cured film After a corona treatment was performed on a COP film (ZF-14) manufactured by Japan Zeon Co., Ltd., the horizontal alignment film-forming composition prepared above was applied to the surface subjected to the corona treatment using a bar coater and dried at 80° C. for 1 minute. Subsequently, a polarized UV irradiation device (“SPOT CURE SP-9” manufactured by Ushio Electric Co., Ltd.) was used to perform polarized UV exposure at a wavelength of 313 nm, a cumulative light amount of 100 mJ/cm ² , and an axis angle of 45° to obtain a horizontal alignment film. The thickness of the horizontal alignment film was measured by an elliptometer and was found to be 100 nm.

Next, the horizontal alignment liquid crystal cured film forming composition 1 was coated on the horizontal alignment film using a bar coater, and after drying at 120°C for 1 minute, a high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by Niuwei Electric Co., Ltd.) was used to irradiate ultraviolet rays (under a nitrogen atmosphere, the cumulative light amount at a wavelength of 365 nm: 500 mJ/ ^cm2 ) to form a horizontal alignment liquid crystal cured film 1, thereby obtaining a laminate 1 including a substrate, a horizontal alignment film, and a horizontal alignment liquid crystal cured film 1. The film thickness of the horizontal alignment liquid crystal cured film 1 in the obtained laminate 1 was measured by an elliptical polarimeter and was 2.3 μm.

(2) Measurement of phase difference and three-dimensional refractive index of horizontally aligned liquid crystal cured film 1 After the laminate was bonded to glass with an adhesive, the COP as the substrate was peeled off, and then the in-plane phase difference Re(λ) of the horizontally aligned liquid crystal cured film 1 manufactured by the above method was measured by a measuring machine ("KOBRA-WPR", manufactured by Oji Instruments Co., Ltd.). The measurement results of the phase difference Re(λ) at each wavelength were Re(450) = 121 nm, Re(550) = 142 nm, Re(650) = 146 nm, and Re(450)/Re(550) = 0.85. Based on the average refractive index and phase difference of the horizontally aligned liquid crystal cured film 1 obtained using an elliptical polarimeter, the three-dimensional refractive index at 589 nm was calculated. The results are shown in Table 3.

6. Preparation of a laminate comprising a substrate, a vertical alignment film, and a vertical alignment liquid crystal cured film (1) Preparation of a laminate 2 comprising a substrate, a vertical alignment film, and a vertical alignment liquid crystal cured film 1 After subjecting a COP film (ZF-14) manufactured by Zeon Co., Ltd. of Japan to a corona treatment, a vertical alignment film forming composition 1 was applied to the surface subjected to the corona treatment using a rod coater and dried at 90° C. for 1 minute to form a vertical alignment film. The film thickness of the vertical alignment film obtained was measured using an elliptical polarimeter and was found to be 70 nm. In addition, the phase difference value of the vertical alignment film obtained was measured at a wavelength of 550 nm (measurement machine: KOBRA-WR manufactured by Oji Instruments Co., Ltd.) and was found to be R ₀ (550) = 0.7 nm. Furthermore, since the phase difference value of the COP at a wavelength of 550 nm is approximately 0, it has no effect on the phase difference value. Next, a vertical alignment liquid crystal cured film forming composition 1 was applied on the obtained vertical alignment film using a rod coater, dried at 90°C for 1 minute, and irradiated with ultraviolet light (under a nitrogen atmosphere, cumulative light quantity at a wavelength of 365 nm: 1000 mJ/ ^cm2 ) using a high-pressure mercury lamp (manufactured by Ushio Electric Co., Ltd.) to form a vertical alignment liquid crystal cured film 1, thereby obtaining a laminate 2 including a substrate, a vertical alignment film, and a vertical alignment liquid crystal cured film 1. The film thickness of the vertical alignment liquid crystal cured film 1 in the obtained laminate 2 was measured with an elliptical polarimeter and was 534 nm.

(2) Measurement of phase difference and three-dimensional refractive index of vertically aligned liquid crystal cured film 1 In order to measure the phase difference value of the vertically aligned liquid crystal cured film 1, a vertically aligned film and a vertically aligned liquid crystal cured film were manufactured on a COP film (ZF-14) manufactured by Japan Zeon Co., Ltd. according to the same procedure as above. The vertically aligned liquid crystal cured film was bonded to the glass via an adhesive (pressure-sensitive adhesive 15 μm manufactured by LINTEC). After confirming that the COP had no phase difference, the incident angle of light on the sample was changed by an elliptical polarimeter to measure the phase difference value. The phase difference values calculated from the obtained film thickness, average refractive index and the measurement results of the elliptical polarimeter are R ₀ (550) = 1.3 nm, R ₄₀ (550) = 21.9 nm, Rth (450) = -91 nm, Rth (550) = -84 nm, and Rth (450) / Rth (550) = 1.09. Based on the average refractive index and phase difference values obtained by the elliptical polarimeter, the three-dimensional refractive indices n3x, n3y and n3z at 589 nm are calculated. The results are shown in Table 3.

(3) Production of a laminate 3 comprising a substrate, a vertical alignment film, and a vertical alignment liquid crystal cured film 2 The vertical alignment film forming composition 2 was coated on the substrate subjected to the corona treatment in the same manner as the above method using a bar coater, and dried at 80°C for 1 minute to obtain a vertical alignment film. The film thickness of the obtained vertical alignment film was measured with an elliptical polarimeter and was 50 nm.

Next, the composition 2 for forming a vertically aligned liquid crystal cured film was coated on the obtained vertically aligned film by a rod coater, and after drying at 120°C for 1 minute, a high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by Ushio Electric Co., Ltd.) was used to irradiate ultraviolet rays (cumulative light quantity at a wavelength of 365 nm in a nitrogen atmosphere: 500 mJ/ ^cm2 ) to form a vertically aligned liquid crystal cured film 2, thereby obtaining a laminate 3 including a substrate, a vertically aligned film, and a vertically aligned liquid crystal cured film 2. The film thickness of the vertically aligned liquid crystal cured film 2 in the obtained laminate 3 was measured by an elliptical polarimeter and was 1.2 μm.

(4) Determination of phase difference and three-dimensional refractive index of vertically aligned liquid crystal cured film 2 In order to determine the phase difference of vertically aligned liquid crystal cured film 2, a vertically aligned film and a vertically aligned liquid crystal cured film were manufactured on a COP film (ZF-14) manufactured by Japan Zeon Co., Ltd. according to the same procedure as above. The vertically aligned liquid crystal cured film was bonded to the glass via an adhesive (pressure-sensitive adhesive 15 μm manufactured by LINTEC). After confirming that there was no phase difference in COP, the phase difference was measured by changing the incident angle of light on the sample using an elliptical polarimeter. The phase difference values calculated based on the obtained film thickness, average refractive index, and the measurement results of the elliptical polarimeter were Rth(450)=-63 nm, Rth(550)=-73 nm, and Rth(450)/Rth(550)=0.85. The three-dimensional refractive indexes n3x, n3y and n3z at 589 nm were calculated based on the average refractive index and phase difference values obtained using an elliptical polarimeter. The results are shown in Table 3.

7. Preparation of a laminate comprising a horizontally aligned liquid crystal curing film, an adhesive layer and a vertically aligned liquid crystal curing film (1) Example 1 (a) Preparation of a laminate (elliptical polarizing plate) After the cycloolefin film side of the polarizing film prepared above is bonded to the horizontally aligned liquid crystal curing film 1 side of a laminate 1 comprising a substrate, a horizontally aligned film and a horizontally aligned liquid crystal curing film 1 by means of an adhesive (pressure-sensitive adhesive 15 μm manufactured by LINTEC), the substrate and the horizontally aligned film are peeled off together. Next, after the vertical alignment liquid crystal cured film 1 side of the laminate 2 including the substrate, the vertical alignment film and the vertical alignment liquid crystal cured film 1 was subjected to a corona treatment, the adhesive A listed in Table 1 was applied, and the adhesive A application surface and the horizontal alignment liquid crystal cured film 1 side of the laminate 1 were laminated, and the adhesive A was cured by irradiating ultraviolet rays with a cumulative light amount of 400 mJ/ ^cm2 (UV-B) from the vertical alignment liquid crystal cured film 1 side using an ultraviolet irradiation device [manufactured by Fusion UV Systems Co., Ltd.]. Afterwards, by peeling off the substrate used to make the vertical alignment liquid crystal curing film 1 together with the vertical alignment film, a laminate (elliptical polarizing plate) having a laminate structure of polarizing film/adhesive/horizontally aligned liquid crystal curing film 1/adhesive layer/vertically aligned liquid crystal curing film 1 was obtained. Furthermore, the thickness of the adhesive layer measured by a contact-type film thickness meter was 1.4 μm.

(b) Evaluation of interference fringes The laminate (elliptical polarizing plate) prepared above was attached to an aluminum reflector via an acrylic adhesive (film thickness 25 μm) and visually observed by rotating 360° from an oblique direction under a 3-wavelength fluorescent lamp. Evaluation was performed based on the following criteria. The evaluation results are shown in Table 3. A: No interference fringes were observed B: Slight interference fringes were observed C: Interference fringes were observed

(2) Example 2 Except that the adhesive was changed to adhesive B, a multilayer body (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

(3) Example 3 Except that the adhesive was changed to adhesive C, a multilayer body (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

(4) Example 4 Except that the adhesive was changed to adhesive D and the laminate 2 was changed to laminate 3, a laminate (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

(5) Comparative Example 1 Except that the adhesive was changed to adhesive D, a multilayer body (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

(6) Comparative Example 2 Except that the adhesive was changed to Adhesive E, a multilayer body (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

(7) Comparative Example 3 Except that the adhesive was changed to adhesive F, a multilayer body (elliptical polarizing plate) was prepared in the same manner as in Example 1, and the interference fringes were evaluated. The results are shown in Table 3.

[Table 3] Adhesive Vertical alignment liquid crystal hardening film Horizontal alignment liquid crystal hardening film Adhesive layer Vertical alignment liquid crystal hardening film |(n1x＋n1y)/2 -(n2x＋n2y)/2| |(n2x＋n2y)/2 -(n3x＋n3y)/2| Interference fringes evaluation Three-dimensional refractive index In-plane phase difference Three-dimensional refractive index In-plane phase difference thickness Three-dimensional refractive index In-plane phase difference n1x n1y n1z Re1 n2x n2y n2z Re2 μm n3x n3y n3z Re3 Embodiment 1 Follow-up agent A 1 1.64 1.57 1.57 1.61 1.49 1.49 1.49 1.49 1.4 1.51 1.51 1.65 1.51 0.12 0.02 B Embodiment 2 Follow-up agent B 1 1.64 1.57 1.57 1.61 1.51 1.51 1.51 1.51 1.4 1.51 1.51 1.65 1.51 0.10 0.00 A Embodiment 3 Followed by Agent C 1 1.64 1.57 1.57 1.61 1.53 1.53 1.53 1.53 1.4 1.51 1.51 1.65 1.51 0.08 0.02 B Embodiment 4 Follow-up agent D 2 1.64 1.57 1.57 1.61 1.56 1.56 1.56 1.56 1.4 1.57 1.57 1.64 1.57 0.04 0.01 A Comparison Example 1 Follow-up agent D 1 1.64 1.57 1.57 1.61 1.56 1.56 1.56 1.56 1.4 1.51 1.51 1.65 1.51 0.04 0.05 C Comparison Example 2 Followed by E 1 1.64 1.57 1.57 1.61 1.46 1.46 1.46 1.46 1.4 1.51 1.51 1.65 1.51 0.15 0.05 C Comparison Example 3 Followed by agent F 1 1.64 1.57 1.57 1.61 1.59 1.59 1.59 1.59 1.4 1.51 1.51 1.65 1.51 0.01 0.08 C

According to the present invention, it was confirmed that the multilayer structure (Examples 1 to 4) in which the difference between the in-plane refractive index of the vertically aligned liquid crystal cured film and the in-plane refractive index of the adhesive layer was controlled could suppress the generation of interference fringes.

Claims (6)

A laminated body, which sequentially comprises a horizontal alignment liquid crystal curing film, an adhesive layer and a vertical alignment liquid crystal curing film, wherein the in-plane refractive index of the adhesive layer and the in-plane refractive index of the vertical alignment liquid crystal curing film satisfy the relationship of formula (1): |((n2x+n2y)/2)-((n3x+n3y)/2)|≦0.03 (1) [In formula (1), n2x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the adhesive layer, n2y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n2x in the same plane as n2x, n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index in the plane of the vertical alignment liquid crystal curing film, and n3y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x. Refractive index at nm]. The laminate of claim 1, wherein the horizontal alignment liquid crystal cured film satisfies equations (2) and (3): Re(450)/Re(550)≦1.00 (2) 100nm<Re(550)<160nm (3) [wherein Re(λ) represents the in-plane phase difference of the horizontal alignment liquid crystal cured film at a wavelength of λ nm]. A laminate as claimed in claim 1 or 2, wherein the vertically aligned liquid crystal cured film satisfies formula (4) and (5): n3x≒n3y<n3z (4) -150nm<Rth(550)<-30nm (5) [In formula (4), n3x represents the refractive index at a wavelength of λ nm in the direction of the maximum refractive index produced in the plane of the vertically aligned liquid crystal cured film, n3y represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of n3x in the same plane as n3x, n3z represents the refractive index at a wavelength of λ nm in the film thickness direction of the vertically aligned liquid crystal cured film, ≒ represents the difference in refractive index between the two is less than 0.01, and in formula (5), Rth(550) represents the phase difference value of the vertically aligned liquid crystal cured film in the thickness direction at a wavelength of 550nm]. For the laminated body of claim 1 or 2, the thickness of the adhesive layer is greater than 0.1μm and less than 2μm. For example, in the laminate of claim 3, the thickness of the adhesive layer is greater than 0.1μm and less than 2μm. An elliptical polarizing plate, which is formed by laminating a laminate as in any one of claims 1 to 5 and a polarizing film.