阅读说明：本技术 有机el显示装置用相位差片、有机el显示装置及相位差片的制造方法 (Phase difference plate for organic EL display device, and method for manufacturing phase difference plate ) 是由 森岛慎一 于 2018-06-20 设计创作，主要内容包括：本发明的课题在于提供一种耐光性优异的有机EL显示装置用相位差片、有机EL显示装置及相位差片的制造方法。本发明的有机EL显示装置用相位差片具有使用含有共聚物的组合物而形成的相位差层,该共聚物具有包含光取向性基团的重复单元A和包含可以显现逆波长色散性的双折射的部位的重复单元B这两者,光取向性基团包含C＝C或C＝N的双键结构。(The invention provides a phase difference plate for an organic EL display device with excellent light resistance, the organic EL display device and a manufacturing method of the phase difference plate. The retardation plate for an organic EL display device has a retardation layer formed using a composition containing a copolymer having both a repeating unit A containing a photo-alignment group and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion, wherein the photo-alignment group has a double bond structure of C-C or C-N.)

1. A phase difference plate for an organic EL display device, comprising:

a retardation layer formed using a composition containing a copolymer having both a repeating unit A containing a photo-alignment group and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion,

the photo-alignment group has a double bond structure of C ═ C or C ═ N.

2. The phase difference plate for an organic EL display device according to claim 1,

the photo-alignment group is a cinnamate group or a chalcone group.

3. The phase difference plate for an organic EL display device according to claim 1 or 2,

the site capable of developing birefringence of reverse wavelength dispersion is any aromatic ring selected from the group represented by the following formulas (Ar-1) to (Ar-5),

[ chemical formula No. 1]

Wherein in the formulae (Ar-1) to (Ar-5), a bonding position with another structure contained in the repeating unit B is represented,

and, Q¹Represents a group of N or CH,

and, Q²represents-S-, -O-or-N (R)⁵)-，R⁵Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,

and, Y¹An optionally substituted aromatic hydrocarbon group having 6 to 12 carbon atoms or an aromatic heterocyclic group having 3 to 12 carbon atoms,

and, Z¹、Z²And Z³Independently represent a hydrogen atom, a C1-valent aliphatic hydrocarbon group, a C3-20 1-valent alicyclic hydrocarbon group, a C6-20 1-valent aromatic hydrocarbon group, a halogen atom, a cyano group, a nitro group, -OR⁶、-NR⁷R⁸or-SR⁹，R⁶～R⁹Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Z¹And Z²May be bonded to each other to form an aromatic ring,

and, A³And A⁴Each independently represents a group selected from-O-, -N (R)¹⁰) Radicals of-S-and-CO-, R¹⁰Represents a hydrogen atom or a substituent group,

and X represents a hydrogen atom or a non-metal atom of group 14 to 16 to which a substituent may be bonded,

and, D⁵And D⁶Each independently represents a single bond, -CO-O-, -C (═ S) O-, -CR¹R²-、-CR¹R²-CR³R⁴-、-O-CR¹R²-、-CR¹R²-O-CR³R⁴-、-CO-O-CR¹R²-、-O-CO-CR¹R²-、-CR¹R²-O-CO-CR³R⁴-、-CR¹R²-CO-O-CR³R⁴-、-NR¹-CR²R³-or-CO-NR¹-，R¹、R²、R³And R⁴Each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms,

and, SP³And SP⁴Each independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or-CH constituting a linear or branched alkylene group having 1 to 12 carbon atoms₂1 or more of-a 2-valent linking group substituted with-O-, -S-, -NH-, -N (Q) -or-CO-, Q represents a substituent,

and, L³And L⁴Each independently represents an organic group having a valence of 1,

ax represents an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from an aromatic hydrocarbon ring and an aromatic hetero ring,

and Ay represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may have a substituent, or an organic group having 2 to 30 carbon atoms which has at least one aromatic ring selected from an aromatic hydrocarbon ring and an aromatic hetero ring,

in addition, the aromatic ring in Ax and Ay may have a substituent, or Ax and Ay may be bonded to form a ring,

and, Q³Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent.

4. The phase difference plate for an organic EL display device according to any one of claims 1 to 3,

the copolymer is an acrylic or methacrylic copolymer.

5. The phase difference plate for an organic EL display device according to any one of claims 1 to 4,

the phase difference layer satisfies the following formula (I),

Re(450)≤Re(550)≤Re(650) (I)

wherein, in the formula (I), Re (450) represents an in-plane retardation value measured at a wavelength of 450nm, Re (550) represents an in-plane retardation value measured at a wavelength of 550nm, and Re (650) represents an in-plane retardation value measured at a wavelength of 650 nm.

6. The phase difference plate for an organic EL display device according to any one of claims 1 to 5,

the retardation layer has an in-plane retardation value of 100 to 180nm as measured at a wavelength of 550 nm.

7. The phase difference plate for an organic EL display device according to any one of claims 1 to 6,

the retardation layer exhibits a retardation value in the thickness direction measured at a wavelength of 550nm of-10 to 10 nm.

8. The phase difference plate for an organic EL display device according to any one of claims 1 to 7,

the retardation layer satisfies a refractive index relationship represented by the following formula (II),

nx＞nz＞ny (II)

in formula (II), nx is a refractive index in a direction in which an in-plane refractive index is largest, ny is a refractive index in a direction in which the in-plane refractive index is smallest, and nz is a refractive index in a thickness direction perpendicular to nx and ny.

9. The phase difference plate for an organic EL display device according to any one of claims 1 to 8,

the phase difference layer satisfies the following formula (III),

0.4＜(nx―nz)/(nx―ny)＜0.6 (III)

in formula (III), nx is a refractive index in a direction in which an in-plane refractive index is largest, ny is a refractive index in a direction in which the in-plane refractive index is smallest, and nz is a refractive index in a thickness direction perpendicular to nx and ny.

10. The phase difference plate for an organic EL display device according to any one of claims 1 to 9,

the phase difference layer is of a single-layer structure.

11. An organic EL display device comprising the phase difference plate for an organic EL display device according to any one of claims 1 to 10 and an organic EL light-emitting element.

12. A method for producing a retardation plate for an organic EL display device according to any one of claims 1 to 10,

the method for manufacturing the phase difference sheet comprises the following steps:

a coating step of coating a composition containing a copolymer having both of the following components on a transparent support to form a coating film: a repeating unit a including a photo-alignment group having a double bond structure of C ═ C or C ═ N; and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion;

an irradiation step of irradiating polarized ultraviolet rays from a direction perpendicular to the coating film; and

and a heating step of performing a heating treatment on the coating film after the irradiation step to form a retardation layer.

Technical Field

The present invention relates to a phase difference plate for an organic EL display device, and a method for manufacturing the phase difference plate.

Background

In an image display device such as an organic Electroluminescence (EL) display device, it is known that a circularly polarizing plate is used as an antireflection film in order to reduce reflection of external light on a display surface.

As such a circularly polarizing plate, for example, as described in patent document 1, a combination of an 1/4 wave plate (λ/4 plate) and a polarizer is known.

Disclosure of Invention

Technical problem to be solved by the invention

In recent years, there has been a demand for further improvement in optical characteristics required for antireflection films, and control of a three-dimensional refractive index distribution defined by an Nz coefficient has also become very important. Among them, a retardation plate satisfying 0 < Nz < 1 is considered to be suitable for use as an antireflection film for an organic EL display device. For example, it is considered that in a retardation film satisfying Nz of 0.5, the retardation value is substantially constant regardless of the angle of view, and the use of such a retardation film can significantly improve the angle of view characteristics of the antireflection film.

Under such circumstances, the present inventors have found that, as a result of applying the retardation sheet described in japanese patent application laid-open No. 2016-080942 as an antireflection film for an organic EL display device, the light resistance of the retardation sheet to which the retardation sheet is applied is sometimes poor depending on the type of the rod-like liquid crystalline compound and the type of the functional group (photo-alignment group) of the polymer compound.

Accordingly, an object of the present invention is to provide a retardation plate for an organic EL display device having excellent light resistance, an organic EL display device, and a method for manufacturing the retardation plate.

Means for solving the technical problem

As a result of intensive studies to achieve the above object, the present inventors have found that the light resistance of a retardation layer formed by using a copolymer each having a repeating unit a containing a specific photo-alignment group and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion is improved, and have completed the present invention.

That is, it has been found that the above-mentioned problems can be achieved by the following configuration.

[1] A retardation plate for an organic EL display device, which has a retardation layer formed using a composition containing a copolymer having both a repeating unit A containing a photo-alignment group and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion,

the photo-alignment group has a double bond structure of C ═ C or C ═ N.

[2] The retardation plate for organic EL displays according to [1], wherein the photo-alignment group is a cinnamate group or a chalcone group.

[3] The retardation plate for an organic EL display device according to [1] or [2], wherein the portion capable of developing birefringence of reverse wavelength dispersion is any aromatic ring selected from the group consisting of groups represented by the following formulae (Ar-1) to (Ar-5).

[4] The retardation plate for organic EL display device according to any one of [1] to [3], wherein the copolymer is an acrylic or methacrylic copolymer.

[5] The phase difference plate for an organic EL display device according to any one of [1] to [4], wherein the phase difference layer satisfies the following formula (I).

Re(450)≤Re(550)≤Re(650)(I)

Wherein, in the formula (I), Re (450) represents an in-plane retardation value measured at a wavelength of 450nm, Re (550) represents an in-plane retardation value measured at a wavelength of 550nm, and Re (650) represents an in-plane retardation value measured at a wavelength of 650 nm.

[6] The retardation plate for organic EL display device according to any one of [1] to [5], wherein the retardation layer is a layer exhibiting an in-plane retardation value of 100 to 180nm as measured at a wavelength of 550 nm.

[7] The retardation plate for organic EL display device according to any one of [1] to [6], wherein the retardation layer exhibits a retardation value in the thickness direction measured at a wavelength of 550nm of-10 to 10 nm.

[8] The phase difference plate for an organic EL display device according to any one of [1] to [7], wherein the phase difference layer satisfies a refractive index relationship represented by the following formula (II).

nx＞nz＞ny II)

In formula (II), nx is a refractive index in a direction in which an in-plane refractive index is largest, ny is a refractive index in a direction in which the in-plane refractive index is smallest, and nz is a refractive index in a thickness direction perpendicular to nx and ny.

[9] The phase difference plate for an organic EL display device according to any one of [1] to [8], wherein the phase difference layer satisfies the following formula (III).

0.4＜(nx―nz)/(nx―ny)＜0.6(III)

In formula (III), nx is a refractive index in a direction in which an in-plane refractive index is largest, ny is a refractive index in a direction in which the in-plane refractive index is smallest, and nz is a refractive index in a thickness direction perpendicular to nx and ny.

[10] The phase difference plate for an organic EL display device according to any one of [1] to [9], wherein the phase difference layer has a single-layer structure.

[11] An organic EL display device comprising the phase difference plate for organic EL display device described in any one of [1] to [10] and an organic EL light-emitting element.

[12] A method for producing a retardation plate for an organic EL display device according to any one of [1] to [10], the method comprising:

a coating step of coating a composition containing a copolymer having both of the following components on a transparent support to form a coating film: a repeating unit a including a photo-alignment group having a double bond structure of C ═ C or C ═ N; and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion;

an irradiation step of irradiating polarized ultraviolet rays from a direction perpendicular to the coating film;

and a heating step of performing a heating treatment on the coating film after the irradiation step to form a retardation layer.

Effects of the invention

According to the present invention, a retardation plate for an organic EL display device having excellent light resistance, an organic EL display device, and a method for manufacturing the retardation plate can be provided.

Detailed Description

The present invention will be described in detail below.

The following description of the constituent elements may be made in accordance with a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

In the present specification, the numerical range expressed by the term "to" refers to a range including numerical values before and after the term "to" as a lower limit value and an upper limit value.

Also, in the present specification, the bonding direction of the labeled divalent group (e.g., -O-CO-) is not particularly limited, for example, D in the following formula (3)¹In the case of-O-CO-, the bond to G is set to 1 at the position bonded to the Ar side¹The position of the side is set to 2, then D¹May be 1-O-CO-2 or 1-CO-O-2.

[ retardation film for organic EL display device ]

The retardation sheet for an organic EL display device of the present invention (hereinafter, also simply referred to as "the retardation sheet of the present invention") has a retardation layer formed using a composition (hereinafter, also simply referred to as "specific composition") containing a copolymer (hereinafter, also simply referred to as "specific copolymer") having both a repeating unit a including a photo-alignment group and a repeating unit B including a site capable of developing birefringence of reverse wavelength dispersion.

The photo-alignment group contained in the repeating unit a has a double bond structure of C ═ C or C ═ N.

Here, "a repeating unit including a site capable of developing birefringence of reverse wavelength dispersion" means a repeating unit capable of developing birefringence of reverse wavelength dispersion when used as a polymer, and "reverse wavelength dispersion" means a property in which the absolute value of in-plane retardation increases as the wavelength becomes longer.

In the present invention, as described above, the light resistance is improved because the retardation layer is formed using the specific composition containing the specific copolymer having both the repeating unit a including the photo-alignment group having the double bond structure containing C ═ C or C ═ N and the repeating unit B including the portion capable of developing birefringence of reverse wavelength dispersion.

Although details thereof are not clear, the present inventors presume as follows.

That is, since the same polymer has a specific photo-alignment group and a site capable of developing birefringence of reverse wavelength dispersion, the photo-alignment group or a photoreactive material thereof can absorb a wavelength shorter than the emission spectrum of the organic EL light emitting element, and thus even when used for an antireflection film of an organic EL display device having a strong emission intensity from the organic EL light emitting element, deterioration due to light irradiation can be suppressed, a desired alignment state can be maintained, and durability can be improved.

[ specific composition ]

As described above, the retardation layer of the retardation plate of the present invention is formed using a specific composition containing a specific copolymer having both a repeating unit a containing a photo-alignment group having a double bond structure containing C ═ C or C ═ N and a repeating unit B containing a site capable of developing birefringence of reverse wavelength dispersion.

< specific copolymer >

(repeating unit A)

The repeating unit a of the specific copolymer is a repeating unit containing a photo-alignment group having a double bond structure of C ═ C or C ═ N, and examples thereof include a repeating unit represented by the following formula (1) or (2).

[ chemical formula No. 1]

In the formulae (1) and (2), R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, L represents a linking group having a valence of 2, and P represents a photo-alignment group having a double bond structure containing C ═ C or C ═ N.

In the formulae (1) and (2), R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, etc.), and among them, a hydrogen atom or a methyl group is preferred.

The double bond structure of C ═ C or C ═ N represented by P in the above formulae (1) and (2) is preferably trans, not cis, and more preferably trans C ═ C.

Specific examples of the photo-alignment group having such a double bond structure include a cinnamate group, a chalcone group, and a maleimide group, and among them, a cinnamate group and a chalcone group are preferable, and a cinnamate group is more preferable, because of high sensitivity to polarized ultraviolet rays and further improvement in light resistance of the resulting retardation plate.

In the present invention, the photo-alignment group having a double bond structure containing C ═ C or C ═ N represented by P in the above formulae (1) and (2) may have a substituent as long as the photo-alignment property is not lost. Specific examples of the substituent include a hydroxyl group, a carboxyl group, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear halogenated alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a cyano group, an amino group and the like. Even if the proton is dissociated, the carboxyl group may be in a salt state together with a counter ion (for example, an alkali metal ion).

Examples of the halogen atom as the substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and among them, a fluorine atom and a chlorine atom are preferable.

The linear, branched or cyclic alkyl group having 1 to 20 carbon atoms as a substituent is preferably an alkyl group having 1 to 6 carbon atoms as the linear alkyl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group and the like.

The branched alkyl group is preferably an alkyl group having 3 to 6 carbon atoms, and specific examples thereof include an isopropyl group, a tert-butyl group and the like.

The cyclic alkyl group is preferably an alkyl group having 3 to 6 carbon atoms, and specific examples thereof include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group.

The linear halogenated alkyl group having 1 to 20 carbon atoms as the substituent is preferably a fluoroalkyl group having 1 to 4 carbon atoms, and specific examples thereof include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group and the like, and among them, a trifluoromethyl group is preferable.

The alkoxy group having 1 to 20 carbon atoms as a substituent is preferably an alkoxy group having 1 to 8 carbon atoms, and specific examples thereof include a methoxy group, an ethoxy group, an n-butoxy group, a methoxyethoxy group and the like, and among them, a methoxy group or an ethoxy group is preferable.

The aryl group having 6 to 20 carbon atoms as a substituent is preferably an aryl group having 6 to 12 carbon atoms, and specific examples thereof include a phenyl group, an α -methylphenyl group, a naphthyl group and the like, and among them, a phenyl group is preferable.

The aryloxy group having 6 to 20 carbon atoms as a substituent is preferably an aryloxy group having 6 to 12 carbon atoms, and specific examples thereof include a phenoxy group, a 2-naphthoxy group and the like, and among them, a phenoxy group is preferable.

Examples of the substituted amino group include: primary amino group (-NH)₂) (ii) a Secondary amino groups such as methylamino; and tertiary amino groups such as dimethylamino, diethylamino, dibenzylamino, and groups having a nitrogen atom of a nitrogen-containing heterocyclic compound (e.g., pyrrolidine, piperidine, and piperazine) as a connecting bond.

Examples of the 2-valent linking group represented by L in the formulae (1) and (2) include 2-valent linking groups formed by combining at least 2 or more groups selected from the group consisting of a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms which may have a substituent, an arylene group having 6 to 12 carbon atoms which may have a substituent, an ether group (-O-), a carbonyl group (-C (═ O) -), and an imino group (-NH-) which may have a substituent.

Examples of the substituent which may have an alkylene group, an arylene group, and an imino group include an alkyl group, an alkoxy group, a halogen atom, and a hydroxyl group.

The alkyl group is preferably a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms (for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclohexyl, etc.), still more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group or an ethyl group.

The alkoxy group is preferably an alkoxy group having 1 to 18 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms (e.g., methoxy group, ethoxy group, n-butoxy group, methoxyethoxy group, etc.), even more preferably an alkoxy group having 1 to 4 carbon atoms, and particularly preferably a methoxy group or an ethoxy group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and among them, a fluorine atom and a chlorine atom are preferable.

The linear alkylene group having 1 to 10 carbon atoms may be, for example, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, or a decylene group.

Specific examples of the branched alkylene group include dimethylmethylene, methylethylene, 2-dimethylpropylene, and 2-ethyl-2-methylpropylene.

Specific examples of the cyclic alkylene group include cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cyclooctylene, cyclodecylene, adamantane-diyl, norbornane-diyl, exo-tetrahydrodicyclopentadiene-diyl, and the like, and among them, cyclohexylene is preferable.

Specific examples of the arylene group having 6 to 12 carbon atoms include phenylene, xylylene, biphenylene, naphthylene, and 2, 2' -methylenebisphenyl, and among them, phenylene is preferable.

In the present invention, L in the above formulas (1) and (2) is preferably a linking group having a valence of 2 which contains at least an arylene group having 6 to 12 carbon atoms which may have a substituent, and more preferably a linking group having a valence of 2 which contains at least a linear alkylene group having 1 to 10 carbon atoms which may have a substituent and an arylene group having 6 to 12 carbon atoms which may have a substituent.

In the present invention, L in the above formulae (1) and (2) is preferably a 2-valent linking group containing a mesogenic group.

Here, as the mesogenic group, a group represented by the following (MG-I) can be suitably mentioned.

MG-I：

-(Q¹¹-Z¹¹)_k-(Q¹²-Z¹²)_l-Q¹⁵-(Z¹³-Q¹³)_m-(Q¹⁴-Z¹⁴)_n-

In the above formula, Q¹¹、Q¹²、Q¹³、Q¹⁴And Q¹⁵Each independently represents 1, 4-phenylene (hereinafter, also referred to as "benzene ring"), a heterocyclic group in which 1 or 2 or more CH groups of 1, 4-phenylene are substituted with N, 1, 4-cyclohexylene (hereinafter, also referred to as "cyclohexane ring"), 1 CH group of 1, 4-cyclohexylene₂Basic or non-adjacent 2 CH₂Heterocyclyl which may be substituted by O and/or S, 1, 4-cyclohexenylene or naphthalene-2, 6-diyl. These groups may have a substituent. Among them, Q is preferred from the viewpoint of cost and the like¹⁵Is a benzene ring, Q¹¹、Q¹²、Q¹³And Q¹⁴Each independently a benzene ring or a cyclohexane ring.

And, in the above formula, Z¹¹、Z¹²、Z¹³And Z¹⁴Each independently represents-COO-, -OCO-, -COOCH₂CH₂-、-CH₂CH₂OCO-、-CH₂CH₂-、-OCH₂-、-CH₂O-、-CH＝CH-、-C≡C-、-CH＝CH-COO-、-OCO-CH＝CH-、-NH＝CH₂-、-CH₂＝NH-、-SCO-、-OCS-Or a single bond. Among them, preferred are-COO-, -OCO-, -COOCH from the viewpoint of cost and the like₂CH₂-、-CH₂CH₂OCO-。

In the formula, k, l, m and n are each independently an integer of 0 to 2.

In the present invention, the repeating unit a including a photo-alignment group having a double bond structure of C ═ C or C ═ N is preferably a repeating unit represented by the above formula (1) among the repeating units represented by the above formulae (1) and (2), and more preferably a repeating unit represented by the following formula (1a) or (1b) including a cinnamate group as a photo-alignment group.

[ chemical formula No. 2]

In the above formulae (1a) and (1b), R and L are the same as the substituents described in the above formula (1).

R in the above formula (1a)¹¹～R¹⁵And R in the above formula (1b)¹⁶Each independently represents a hydrogen atom or a substituent. At R¹¹、R¹²、R¹³、R¹⁴And R¹⁵In (2), adjacent groups may be bonded to form a ring. And, in R¹¹、R¹²、R¹³、R¹⁴And R¹⁵In (2), R is para¹³Substituents are preferred. Examples of the substituent include a hydroxyl group, a carboxyl group, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear halogenated alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a cyano group, an amino group, and the like.

And, in the above formula (1b), R¹⁶Represents a 1-valent organic group, and a represents an integer of 0 to 5. When a is 2 or more, a plurality of R¹⁶May be the same or different, respectively. In addition, as R¹⁶The 1-valent organic group of (a),examples thereof include a chain or cyclic alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms which may have a substituent.

Specific examples of the repeating unit represented by the above formula (1) include repeating units represented by the following formulae (A-1) to (A-7).

[ chemical formula No. 3]

The content of the repeating unit A is preferably 5 to 40% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 25% by mass, based on 100% by mass of all the repeating units of the specific copolymer.

In the present invention, the content of each repeating unit contained in the specific copolymer is calculated from the charged amount (mass) of each monomer used for obtaining each repeating unit.

(repeating unit B)

The repeating unit B of the specific copolymer is a repeating unit containing a site capable of developing birefringence of reverse wavelength dispersion, and examples thereof include a repeating unit represented by the following formula (3).

[ chemical formula No. 4]

In the formula (3), R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In the above formula (3), D¹、D²、D³And D⁴Each independently represents a single bond, -O-CO-, -C (═ S) O-, -CR¹R²-、-CR¹R²-CR³R⁴-、-O-CR¹R²-、-CR¹R²-O-CR³R⁴-、-CO-O-CR¹R²-、-O-CO-CR¹R²-、-CR¹R²-O-CO-CR³R⁴-、-CR¹R²-CO-O-CR³R⁴-、-NR¹-CR²R³-or-CO-NR¹-。R¹、R²、R³And R⁴Each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

In the above formula (3), G is¹And G²Each independently represents a C5-8 alicyclic hydrocarbon group with a valence of 2, -CH constituting the alicyclic hydrocarbon group₂More than 1 of-may be substituted by-O-, -S-or-NH-.

In the above formula (3), A¹And A²Each independently represents an aromatic ring having 6 or more carbon atoms or a cycloalkane ring having 6 or more carbon atoms.

And, in the above formula (3), SP¹And SP²Each independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or-CH constituting a linear or branched alkylene group having 1 to 12 carbon atoms₂1 or more of-2-valent linking groups substituted with-O-, -S-, -NH-, -N (Q) -or-CO-, Q represents a substituent.

In formula (3), RL represents a single bond or a 2-valent linking group.

In the formula (3), T represents a terminal group.

In the formula (3), R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, etc.), and among them, a hydrogen atom or a methyl group is preferred.

In the above formula (3), as G¹And G²The alicyclic hydrocarbon group having a valence of 2 and having 5 to 8 carbon atoms is preferably a 5-or 6-membered ring. The alicyclic hydrocarbon group may be saturated or unsaturated, but is preferably a saturated alicyclic hydrocarbon group. As a group G¹And G²The alicyclic hydrocarbon group having a valence of 2 can be described, for example, in paragraph 0078 of Japanese patent application laid-open No. 2012-021068, the contents of which are incorporated herein by reference.

In the above formula (3), A is¹And A²An aromatic ring having 6 or more carbon atoms,examples thereof include aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, phenanthroline ring, etc.; an aromatic heterocycle such as furan ring, pyrrole ring, thiophene ring, pyridine ring, thiazole ring, or benzothiazole ring. Among them, a benzene ring (e.g., 1, 4-phenyl group) is preferable.

In the above formula (3), A is¹And A²Examples of the cycloalkane ring having 6 or more carbon atoms include cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclododecane ring, and cyclododecane ring. Among them, a cyclohexane ring (e.g., 1, 4-cyclohexylene and the like) is preferable, and trans-1, 4-cyclohexylene is more preferable.

In the above formula (3), SP is defined as¹And SP²Examples of the straight or branched alkylene group having 1 to 12 carbon atoms include methylene, ethylene, propylene, butylene, and the like.

In the formula (3), the linking group having a valence of 2 represented by RL is, for example, the linking group represented by D in the formula (3)¹Similarly, examples thereof include-O-CO-, -C (═ S) O-, -CR¹R²-、-CR¹R²-CR³R⁴-、-O-CR¹R²-、-CR¹R²-O-CR³R⁴-、-CO-O-CR¹R²-、-O-CO-CR¹R²-、-CR¹R²-O-CO-CR³R⁴-、-CR¹R²-CO-O-CR³R⁴-、-NR¹-CR²R³-and-CO-NR¹-and the like. In addition, R¹、R²、R³And R⁴Each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

In the formula (3), examples of the terminal group represented by T include a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an oxycarbonyl group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an acylamino group having 1 to 10 carbon atoms, an alkoxycarbonylamino group having 1 to 10 carbon atoms, a sulfonylamino group having 1 to 10 carbon atoms, a sulfamoyl group having 1 to 10 carbon atoms, a carbamoyl group having 1 to 10 carbon atoms, a sulfinyl group having 1 to 10 carbon atoms, and a ureido group having 1 to 10 carbon atoms. Among them, preferred are C1-10 alkyl groups and C1-10 alkoxy groups, more preferred are C1-10 alkyl groups, and even more preferred are C1-4 alkyl groups (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, etc.).

In the formula (3), Ar represents any aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-5). In the following formulae (Ar-1) to (Ar-5), D is the same as D in the above formula (3)¹Or D²The bonding position of (2).

[ chemical formula No. 5]

Here, in the above formula (Ar-1), Q¹Represents N or CH, Q²represents-S-, -O-or-N (R)⁵)-，R⁵Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Y¹Represents an optionally substituted aromatic hydrocarbon group having 6 to 12 carbon atoms or an aromatic heterocyclic group having 3 to 12 carbon atoms.

As R⁵Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl groups.

As Y¹The aromatic hydrocarbon group having 6 to 12 carbon atoms includes, for example, an aryl group such as a phenyl group, a 2, 6-diethylphenyl group, or a naphthyl group.

As Y¹Examples of the aromatic heterocyclic group having 3 to 12 carbon atoms include heteroaryl groups such as thienyl, thiazolyl, furyl and pyridyl.

And as Y¹Examples of the substituent which may be present include an alkyl group, an alkoxy group, and a halogen atom.

The alkyl group is preferably a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms (for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclohexyl, etc.), still more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group or an ethyl group.

The alkoxy group is preferably an alkoxy group having 1 to 18 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms (e.g., methoxy group, ethoxy group, n-butoxy group, methoxyethoxy group, etc.), even more preferably an alkoxy group having 1 to 4 carbon atoms, and particularly preferably a methoxy group or an ethoxy group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and among them, a fluorine atom and a chlorine atom are preferable.

And, in the above formulae (Ar-1) to (Ar-5), Z¹、Z²And Z³Independently represent a hydrogen atom, a C1-valent aliphatic hydrocarbon group, a C3-20 1-valent alicyclic hydrocarbon group, a C6-20 1-valent aromatic hydrocarbon group, a halogen atom, a cyano group, a nitro group, -OR⁶、-NR⁷R⁸or-SR⁹，R⁶～R⁹Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Z¹And Z²May be bonded to each other to form an aromatic ring.

The 1-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 15 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and specifically more preferably a methyl group, an ethyl group, an isopropyl group, a tert-amyl group (1, 1-dimethylpropyl group), a tert-butyl group, a 1, 1-dimethyl-3, 3-dimethyl-butyl group, and particularly preferably a methyl group, an ethyl group, or a tert-butyl group.

Examples of the 1-valent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic saturated hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, methylcyclohexyl, and ethylcyclohexyl; monocyclic acyclic radicals such as cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclodecenyl, cyclopentadienyl, cyclohexadienyl, cyclooctadienyl and cyclodecadienylA saturated hydrocarbon group; bicyclo [2.2.1]Heptyl, bicyclo [2.2.2]Octyl, tricyclo [5.2.1.0^2，6]Decyl, tricyclo [3.3.1.1^3，7]Decyl, tetracyclic [6.2.1.1^3，6.0^2，7]Polycyclic saturated hydrocarbon groups such as dodecyl group and adamantyl group; and the like.

Specific examples of the 1-valent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a 2, 6-diethylphenyl group, a naphthyl group, and a biphenyl group, and preferably an aryl group having 6 to 12 carbon atoms (particularly a phenyl group).

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like, and among them, a fluorine atom, a chlorine atom and a bromine atom are preferable.

On the other hand, as R⁶～R⁸Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl groups.

And, in the above formulae (Ar-2) and (Ar-3), A³And A⁴Each independently represents a group selected from-O-, -N (R)¹⁰) A radical of the group consisting of-S-and-CO-, R¹⁰Represents a hydrogen atom or a substituent.

As R¹⁰Examples of the substituent include Y in the formula (Ar-1)¹May have the same substituent.

In the formula (Ar-2), X represents a hydrogen atom or a non-metal atom of groups 14 to 16 to which a substituent may be bonded.

Examples of the group 14 to 16 non-metal atom represented by X include an oxygen atom, a sulfur atom, a substituted nitrogen atom, and a substituted carbon atom, and specific examples of the substituent include an alkyl group, an alkoxy group, an alkyl-substituted alkoxy group, a cyclic alkyl group, an aryl group (e.g., phenyl group, naphthyl group, etc.), a cyano group, an amino group, a nitro group, an alkylcarbonyl group, a sulfo group, a hydroxyl group, and the like.

And, in the above formula (Ar-3), D⁵And D⁶Each independently represents a single bond, -CO-O-, -O-CO-, -C (═ S) O--CR¹R²-、-CR¹R²-CR³R⁴-、-O-CR¹R²-、-CR¹R²-O-CR³R⁴-、-CO-O-CR¹R²-、-O-CO-CR¹R²-、-CR¹R²-O-CO-CR³R⁴-、-CR¹R²-CO-O-CR³R⁴-、-NR¹-CR²R³-or-CO-NR¹-。R¹、R²、R³And R⁴Each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

And, in the above formula (Ar-3), SP³And SP⁴Each independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or-CH constituting a linear or branched alkylene group having 1 to 12 carbon atoms₂1 or more of-2-valent linking groups substituted with-O-, -S-, -NH-, -N (Q) -or-CO-, Q represents a substituent. Examples of the substituent include Y in the above formula (Ar-1)¹May have the same substituent.

And, in the above formula (Ar-3), L³And L⁴Each independently represents a 1-valent organic group, and may be a radical-polymerizable or cation-polymerizable group.

Here, the 1-valent organic group includes an alkyl group, an aryl group, a heteroaryl group, and the like. The alkyl group may be linear, branched or cyclic, but is preferably linear. The number of carbon atoms of the alkyl group is preferably 1 to 30, more preferably 1 to 20, and still more preferably 1 to 10. Also, the aryl group may be monocyclic or polycyclic, but is preferably monocyclic. The number of carbon atoms of the aryl group is preferably 6 to 25, more preferably 6 to 10. Also, heteroaryl groups may be monocyclic or polycyclic. The number of hetero atoms constituting the heteroaryl group is preferably 1 to 3. The hetero atom constituting the heteroaryl group is preferably a nitrogen atom, a sulfur atom and an oxygen atom. The number of carbon atoms of the heteroaryl group is preferably 6 to 18, more preferably 6 to 12. The alkyl group, aryl group and heteroaryl group may be unsubstituted or may have a substituent. The substituent may be the same as that in the above formula (Ar-1)Y of (A) is¹May have the same substituent.

On the other hand, as the radical polymerizable group, a conventionally known radical polymerizable group can be used, and as a suitable radical polymerizable group, an acryloyl group or a methacryloyl group can be mentioned. In this case, it is known that the polymerization rate of an acryloyl group is generally high, and from the viewpoint of improving productivity, an acryloyl group is preferable, but a methacryloyl group can be used as a polymerizable group in the same manner.

As the cationically polymerizable group, a conventionally known cationically polymerizable group can be used, and specific examples thereof include an alicyclic ether group, a cyclic acetal group, a cyclic lactone group, a cyclic thioether group, a spiroorthoester group, and an ethyleneoxy group. Among them, alicyclic ether groups or ethyleneoxy groups are suitable, and epoxy groups, oxetane groups or ethyleneoxy groups are particularly preferred.

Examples of particularly preferable polymerizable groups include the following polymerizable groups.

[ chemical formula No. 6]

In the formulae (Ar-4) to (Ar-5), Ax represents an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocyclic ring.

In the formulae (Ar-4) to (Ar-5), Ay represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may have a substituent, or an organic group having 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocyclic ring.

Here, the aromatic ring in Ax and Ay may have a substituent, or Ax and Ay may be bonded to each other to form a ring.

And, Q³Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent.

Ax and Ay are Ax and Ay described in paragraphs [0039] to [0095] of International publication No. 2014/010325.

And as Q³Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups, and the substituent may include a group similar to Y in the formula (Ar-1)¹May have the same substituent.

In the present invention, specific examples of the repeating unit represented by the above formula (3) include repeating units represented by the following formulae (B-1) to (B-4).

[ chemical formula No. 7]

The content of the repeating unit B is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, and still more preferably 70 to 90% by mass, based on 100% by mass of all the repeating units of the specific copolymer.

In the present invention, the specific copolymer having the repeating unit a and the repeating unit B is preferably an acrylic copolymer or a methacrylic copolymer because liquid crystallinity is easily imparted and retardation is easily developed by heat treatment after irradiation with polarized ultraviolet light.

Specific examples of the specific copolymer include copolymers P-1 to P-15 shown below.

[ chemical formula No. 8]

[ chemical formula No. 9]

[ chemical formula No. 10]

[ chemical formula No. 11]

[ chemical formula No. 12]

The specific copolymer may have other repeating units in addition to the repeating unit a and the repeating unit B as long as the effect of the present invention is not impaired.

Examples of the monomer (radical polymerizable monomer) forming such another repeating unit include an acrylate compound, a methacrylate compound, a maleimide compound, an acrylamide compound, acrylonitrile, maleic anhydride, a styrene compound, and a vinyl compound.

The method for synthesizing the specific copolymer is not particularly limited, and for example, the specific copolymer can be synthesized by mixing a monomer forming the repeating unit a, a monomer forming the repeating unit B, and a monomer forming an arbitrary other repeating unit, and polymerizing the mixture in an organic solvent using a radical polymerization initiator.

The weight average molecular weight (Mw) of the specific copolymer is preferably 100000 or less, more preferably 50000 or less, and still more preferably 3000 to 30000.

Here, the weight average molecular weight in the present invention is a value measured by a Gel Permeation Chromatography (GPC) method under the conditions shown below.

Solvent (eluent): THF (tetrahydrofuran)

Device name: TOSOH HLC-8320GPC

Column: TOSOH TSKgel Super 3 HZM-H (4.6 mm. times.15 cm) were ligated and used

Column temperature: 40 deg.C

Sample concentration: 0.1% by mass

Flow rate: 1.0ml/min

Calibration curve: TSK standard polystyrene manufactured by TOSOH uses a calibration curve based on 7 samples up to Mw of 2800000-1050 (Mw/Mn of 1.03-1.06)

< polymerizable Compound >

The specific composition used for forming the retardation layer may contain a polymerizable compound in addition to the specific copolymer.

The polymerizable group of the polymerizable compound is not particularly limited, and examples thereof include an acryloyl group, a methacryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, it is preferable to have an acryloyl group or a methacryloyl group.

The polymerizable compound is preferably another polymerizable compound having 2 to 4 polymerizable groups, and more preferably another polymerizable compound having 2 polymerizable groups, because the light resistance of the retardation layer to be formed is further improved.

Examples of such other polymerizable compounds include compounds represented by the formulae (M1), (M2) and (M3) described in paragraphs [0030] to [0033] of Japanese patent application laid-open No. 2014-077068, and more specifically, specific examples described in paragraphs [0046] to [0055] of Japanese patent application laid-open No. 2014-077068.

< polymerization initiator >

When the specific composition used for forming the retardation layer contains the polymerizable compound, it preferably contains a polymerization initiator.

The polymerization initiator used is preferably a photopolymerization initiator capable of initiating a polymerization reaction by Ultraviolet (UV) irradiation.

Examples of the photopolymerization initiator include an α -carbonyl compound (described in U.S. Pat. Nos. 2367661 and 2367670), an acyloin ether (described in U.S. Pat. No. 2448828), an α -hydrocarbon-substituted aromatic acyloin compound (described in U.S. Pat. No. 2722512), a polynuclear quinone compound (described in U.S. Pat. Nos. 3046127 and 2951758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (described in U.S. Pat. No. 3549367), an acridine and phenazine compound (described in Japanese patent application laid-open No. Sho 60-105667 and U.S. Pat. No. 4239850), an oxadiazole compound (described in U.S. Pat. No. Sho 4212970), an acylphosphine oxide compound (described in Japanese patent application laid-Sho 63-040799, Japanese patent application laid-open No. Hei 5-029234, Japanese patent application laid-open No. Hei 10-095788, a pharmaceutically acceptable carrier, a, Japanese patent laid-open No. 10-029997).

< solvent >

The specific composition used for forming the retardation layer preferably contains a solvent from the viewpoint of workability for forming the retardation layer and the like.

Specific examples of the solvent include ketones (e.g., acetone, 2-butanone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (e.g., dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (e.g., hexane, etc.), alicyclic hydrocarbons (e.g., cyclohexane, etc.), aromatic hydrocarbons (e.g., toluene, xylene, trimethylbenzene, etc.), halogenated carbons (e.g., dichloromethane, dichloroethane, dichlorobenzene, chlorotoluene, etc.), esters (e.g., methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (e.g., ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (e.g., methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (e.g., dimethyl sulfoxide, etc.), amides (e.g., dimethylformamide, dimethylacetamide, etc.), and 1 of these can be used alone, more than 2 kinds may be used in combination.

The retardation plate of the present invention has a retardation layer formed using the above-mentioned specific composition. The method for forming the retardation layer will be described in detail in the method for producing the retardation plate of the present invention.

In the present invention, the content of the specific copolymer in the retardation layer is preferably 50 to 99% by mass, more preferably 60 to 97% by mass, and still more preferably 70 to 95% by mass. Further, the specific copolymer may be used alone in 1 kind, or may be used in combination of 2 or more kinds. When 2 or more kinds are used in combination, the total amount thereof preferably satisfies the above content.

In the present invention, the thickness of the retardation layer is not particularly limited, but is preferably 10 μm or less, and more preferably 5 μm or less. The lower limit of the thickness is not particularly limited, but is usually 10nm or more, preferably 50nm or more.

The retardation layer preferably has a single-layer structure.

In the present invention, the retardation layer preferably satisfies the following formula (I) because the black viewing angle is good.

Re(450)≤Re(550)≤Re(650)(I)

Wherein, in the above formula (I), Re (450) represents an in-plane retardation value measured at a wavelength of 450nm, Re (550) represents an in-plane retardation value measured at a wavelength of 550nm, and Re (650) represents an in-plane retardation value measured at a wavelength of 650 nm. In the present specification, when a measurement wavelength for which no retardation value is specified is used, the measurement wavelength is 550 nm.

The in-plane retardation value and the retardation value in the thickness direction are values measured using a measurement wavelength light using AxoScan OPMF-1(OptoScience, inc.).

Specifically, the average refractive index ((Nx + Ny + Nz)/3) and the film thickness (d (. mu.m)) were input to Axoscan OPMF-1 and calculated

Slow axis direction (°)

Re(λ)＝R0(λ)

Rth(λ)＝((nx+ny)/2―nz)×d。

R0 (. lamda.) is a numerical value calculated by Axoscan OPMF-1 and indicates Re (. lamda.).

In the present invention, Re (550) of the retardation layer is preferably 100 to 180nm, more preferably 120 to 150nm, for the reason that linearly polarized light having a wavelength of 550nm, which is high in human visual sensitivity, is accurately converted into circularly polarized light.

In the present invention, the Rth (550) of the retardation layer is preferably-10 to 10nm, more preferably-5 to 5nm, from the viewpoint of a good black tone in an oblique direction.

In the present invention, the retardation layer preferably satisfies the refractive index relationship represented by the following formula (II) because 120 to 150nm of Re (550) and-5 to 5nm of Rth (550) are simultaneously realized.

nx＞nz＞ny(II)

In the formula (II) and the formula (III) described later, nx is a refractive index in a direction (slow axis) in which an in-plane refractive index is maximum, ny is a refractive index in a direction (fast axis) in which the in-plane refractive index is minimum, and nz is a refractive index in a thickness direction perpendicular to nx and ny.

The refractive indices nx, ny, nz were measured using an abbe refractometer (NAR-4T, ATAGO co., ltd) and a sodium lamp (λ 589nm) as a light source. When the wavelength dependency is measured, the wavelength dependency can be measured by combining a multi-wavelength abbe refractometer DR-M2(ATAGO co., ltd.) with an interference filter.

In the present invention, the retardation layer preferably satisfies the following formula (III) because 120 to 150nm of Re (550) and-5 to 5nm of Rth (550) are simultaneously realized.

0.4＜(nx―nz)/(nx―ny)＜0.6(III)

[ transparent support ]

The retardation plate of the present invention may have a transparent support for supporting the retardation layer.

Here, "transparent" in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

Examples of such a transparent support include a glass substrate and a polymer film.

Examples of the material of the polymer film include cellulose-based polymers; acrylic polymers having acrylate polymers such as polymethyl methacrylate and polymers containing a lactone ring; a thermoplastic norbornene-based polymer; a polycarbonate-series polymer; polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin); polyolefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers; a vinyl chloride polymer; amide polymers such as nylon and aromatic polyamide; imide amide-based polymer-based polymers; a sulfone-based polymer; a polyether sulfone-based polymer; a polyether ether ketone polymer; polyphenylene sulfide-based polymer; a vinylidene chloride polymer; a vinyl alcohol polymer; a vinyl butyral polymer; an aryl ester polymer; a polyoxymethylene polymer; an epoxy polymer; or a polymer in which these polymers are mixed.

The thickness of the transparent support is not particularly limited, but is preferably 5 to 200. mu.m, more preferably 10 to 100. mu.m, and still more preferably 20 to 90 μm.

[ method for producing phase difference plate ]

The method for producing the retardation film of the present invention comprises: a coating step of coating a specific composition containing the specific copolymer on the transparent support to form a coating film; an irradiation step of irradiating polarized ultraviolet rays from a direction perpendicular to the coating film; and a heating step of performing a heating treatment on the coating film after the irradiation step to form a retardation layer.

[ coating procedure ]

The coating method in the coating step is not particularly limited, and examples thereof include a spin coating method, an air knife coating method, a curtain coating method, a roll coating method, a wire bar coating method, a gravure coating method, and a die coating method.

The coating amount is preferably adjusted so that a retardation layer having a desired thickness can be produced.

[ irradiation procedure ]

The irradiation step is a step of irradiating polarized ultraviolet rays onto the coating film formed in the coating step from a direction perpendicular to the coating film.

Examples of the method of irradiating ultraviolet rays with polarized light include: a method using a polarizing plate (e.g., an iodine polarizing plate, a dichroic polarizing plate, a wire grid type polarizing plate, etc.); a method using a prism-type element (e.g., a Glan-Thomson prism, etc.) and a reflective polarizer using the Brewster's angle; a method of using light emitted from a laser light source having polarized light; and the like.

The light source used for the ultraviolet irradiation is not particularly limited as long as it is a light source generating ultraviolet rays, and for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

The light irradiation amount is preferably 300 to 30000mJ/cm²More preferably 500 to 15000mJ/cm²。

By adjusting the amount of light irradiation, the alignment state of the photo-alignment groups in the repeating unit a of the specific copolymer can be changed, and the Nz coefficient of the retardation layer, i.e., (nx-Nz)/(nx-n y), can be adjusted.

[ heating procedure ]

The heating step is a step of performing a heating treatment on the coating film after the irradiation step to form a retardation layer.

In the present invention, the heating temperature in the heating step is preferably 50 ℃ or higher, more preferably 100 to 200 ℃, and further preferably 120 to 180 ℃.

The heating time is preferably 30 seconds to 10 minutes, more preferably 1 minute to 10 minutes, and still more preferably 2 minutes to 8 minutes.

[ organic EL display device ]

The organic EL display device of the present invention includes the retardation plate of the present invention and an organic EL light-emitting element.

As such an organic EL display device, a polarizer, the retardation plate of the present invention, and an organic EL display panel may be preferably provided in this order from the viewing side.

[ polarizer ]

The polarizer is not particularly limited as long as it has a function of converting light into specific linearly polarized light, and conventionally known absorption polarizers and reflection polarizers can be used.

As the absorption polarizer, an iodine polarizer, a dye polarizer using a dichroic dye, a polyene polarizer, or the like is used. Among the iodine-based polarizer and the dye-based polarizer, there are a coating-type polarizer and a stretching-type polarizer, and any of them can be used, but a polarizer prepared by adsorbing iodine or a dichroic dye to polyvinyl alcohol and stretching it is preferable.

As a method for obtaining a polarizer by stretching and dyeing a laminated film of a polyvinyl alcohol layer formed on a substrate, there can be mentioned japanese patent No. 5048120, japanese patent No. 5143918, japanese patent No. 4691205, japanese patent No. 4751481, and japanese patent No. 4751486, and known techniques relating to these polarizers can also be preferably used.

As the reflective polarizer, a polarizer in which films having different birefringence are laminated, a wire grid polarizer, a polarizer in which a cholesteric liquid crystal having a selective reflection region and an 1/4 wave plate are combined, or the like is used.

Among them, from the viewpoint of more excellent adhesion, the adhesive composition preferably contains a polyvinyl alcohol resin (containing-C H)₂-CHOH-as a polymer of repeating units. In particular, at least 1) of polarizers selected from the group consisting of polyvinyl alcohol and ethylene-vinyl alcohol copolymer.

The thickness of the polarizer is not particularly limited, but is preferably 3 μm to 60 μm, more preferably 5 μm to 30 μm, and still more preferably 5 μm to 15 μm.

[ organic EL display Panel ]

The organic EL display panel is a member in which a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer are formed between a pair of electrodes of an anode and a cathode, and may include a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, and the like in addition to the light-emitting layer, and each of these layers may have other functions. Various materials can be used for forming each layer.