JP7734084B2 - Photoalignable polymer, binder composition, binder layer, optical laminate, method for manufacturing optical laminate, and image display device - Google Patents

Description

The present invention relates to a photoalignable polymer, a binder composition, a binder layer, an optical laminate, a method for manufacturing an optical laminate, and an image display device.

Optical films such as optical compensation sheets and retardation films are used in various image display devices in order to eliminate image coloration and widen the viewing angle.
Stretched birefringent films have been used as optical films, but in recent years, optically anisotropic layers formed using liquid crystal compounds have been proposed as an alternative to stretched birefringent films.

When forming such an optically anisotropic layer, a photo-alignment film obtained by performing a photo-alignment treatment is sometimes used to align the liquid crystal compound.
For example, in the examples of Patent Document 1, a method for forming an optically anisotropic layer using a photoalignment polymer KH2 represented by the following formula is disclosed: This photoalignment polymer contains a cleavage group that decomposes under the action of an acid to generate a polar group.

International Publication No. 2018/216812

The inventors have studied the photoalignable polymer described in Patent Document 1 and have found that the alignment properties (hereinafter also referred to as "liquid crystal alignment properties") of an optically anisotropic layer formed above a layer (hereinafter also referred to as "lower layer") formed using this photoalignable polymer may be poor depending on the type of liquid crystal compound. In particular, they have found that there is room for improvement in the alignment properties of discotic liquid crystal compounds.

Therefore, an objective of the present invention is to provide a photoalignable polymer, binder composition, binder layer, optical laminate, method for manufacturing an optical laminate, and image display device that can improve liquid crystal alignment.

As a result of intensive research to achieve the above-mentioned object, the inventors discovered that the use of a photo-alignable polymer having a specific repeating unit containing a photo-alignable group and a repeating unit containing an acid-cleavable group results in good liquid crystal alignment, and thus completed the present invention.
That is, the present inventors have found that the above object can be achieved by the following configuration.

[1] A photoalignable polymer having a repeating unit represented by the formula (1) described below and a repeating unit represented by the formula (2) described below.
[2] The photoalignable polymer according to [1], wherein the repeating unit represented by the formula (1) described later is a repeating unit represented by any one of the formulas (3) to (5) described later.
[3] The photoalignable polymer according to [1] or [2], further comprising a repeating unit having a crosslinkable group.
[4] The photoalignable polymer according to [3], wherein the repeating unit having a crosslinkable group is a repeating unit represented by formula (C) described below.
[5] The photoalignable polymer according to [3] or [4], wherein the crosslinkable group represents a group represented by any one of formulas (C1) to (C4) described below.
[6] The photoalignable polymer according to any one of [1] to [5], wherein the content of the repeating unit represented by formula (1) is 5 to 80 mass %.
[7] The photoalignable polymer according to any one of [1] to [6], having a weight average molecular weight of 10,000 to 500,000.
[8] A binder composition comprising the photoalignable polymer according to any one of [1] to [7], a binder, and a photoacid generator.
[9] A binder layer formed using the binder composition according to [8], the surface of which has an orientation control ability.
[10] The binder layer according to [9],
an optically anisotropic layer disposed on the binder layer.
[11] A step of generating an acid from a photoacid generator on a coating film obtained using the binder composition according to [8], and then subjecting the coating film to a photoalignment treatment to form a binder layer;
and applying a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound onto the binder layer to form an optically anisotropic layer.
[12] An image display device having the binder layer according to [9] or the optical laminate according to [10].

The present invention provides a photoalignable polymer, binder composition, binder layer, optical laminate, method for manufacturing an optical laminate, and image display device that can improve liquid crystal alignment.

The present invention will be described in detail below.
The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.
In addition, in this specification, for each component, a substance corresponding to the component may be used alone or in combination of two or more. Here, when two or more substances for each component are used in combination, the content of the component refers to the total content of the substances used in combination, unless otherwise specified.
In addition, in this specification, "(meth)acrylic" is a notation representing "acrylic" or "methacrylic".
Furthermore, the bonding direction of a divalent group (for example, -O-CO-) represented in this specification is not particularly limited. For example, when ^L2 is -O-CO- in the bond of " ^L1 - ^L2 - ^L3 ", if the position bonding to the ^L1 side is *1 and the position bonding to the ^L3 side is *2, ^L2 may be *1-O-CO-*2 or *1-CO-O-*2.

[Photo-oriented polymer]
The photoalignable polymer of the present invention is a copolymer having a repeating unit represented by formula (1) described below and a repeating unit represented by formula (2) described below.

In the present invention, as described above, by blending a photoalignable polymer having a repeating unit represented by formula (1) described later and a repeating unit represented by formula (2) described later, the liquid crystal alignment property becomes good.
Although the details of this are not clear, the present inventors speculate as follows.
In other words, unlike the photo-alignable polymer KH2 described in Patent Document 1 mentioned above, the photo-alignable polymer of the present invention has a structure in which a photo-alignable group is incorporated into the main chain skeleton, as represented by formula (1) described below.
Therefore, when the photoalignable polymer of the present invention is unevenly distributed on the outermost surface of the lower layer (the interface side with the upper layer) due to the presence of the "group containing a fluorine atom or a silicon atom" (Y in formulas (B1) and (B2) described below) possessed by the acid-cleavable group in formula (2) described below, the photoalignable groups are prevented from being randomly arranged, and as a result, unexpected alignment control forces are prevented from acting on the upper layer, which is thought to result in good liquid crystal alignment properties.
The repeating units contained in the photoalignable polymer of the present invention will be described in detail below.

[Repeating unit represented by formula (1)]
The photoalignable polymer of the present invention has a repeating unit represented by the following formula (1).

In the above formula (1), n represents 1 or 2, and m represents an integer of 1 to 10. However, n and m do not simultaneously represent 1. That is, the sum of n and m represents an integer of 3 to 12.
Here, m is preferably an integer of 2 to 6, more preferably an integer of 2 to 4, even more preferably 2 or 3, and particularly preferably 2.

In the above formula (1), R ¹ represents a hydrogen atom or a substituent, provided that when n represents 2 or m represents an integer of 2 or greater, multiple R ^1s may be the same or different.
Here, the type of the substituent represented by one embodiment of R ¹ is not particularly limited, and examples thereof include known substituents.
Examples of the substituent include a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a cyano group, a carboxy group, an alkoxycarbonyl group, and a hydroxyl group.
Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with fluorine and chlorine atoms being preferred.
The alkyl group is, for example, preferably a linear alkyl group having 1 to 18 carbon atoms, or a branched or cyclic alkyl group having 3 to 18 carbon atoms, more preferably a linear alkyl group having 1 to 4 carbon atoms, and further preferably a methyl group or an ethyl group.
The alkoxy group is, for example, preferably an alkoxy group having 1 to 18 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms, and further preferably a methoxy group or an ethoxy group.
Examples of the aryl group include aryl groups having 6 to 12 carbon atoms, such as a phenyl group, an α-methylphenyl group, and a naphthyl group, with a phenyl group being preferred.
Examples of the aryloxy group include a phenoxy group, a naphthoxy group, an imidazoyloxy group, a benzimidazoyloxy group, a pyridin-4-yloxy group, a pyrimidinyloxy group, a quinazolinyloxy group, a purinyloxy group, and a thiophen-3-yloxy group.
Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
^R1 and ^R2 are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom or a methyl group.

In the above formula (1), X ¹ represents —O—, —S—, or —NR ³ —, and R ³ represents a hydrogen atom or a substituent, provided that when n represents 2 or m represents an integer of 2 or greater, multiple X ^1s may be the same or different.
Here, examples of the substituent represented by one embodiment of ^R3 include the groups exemplified as the substituent represented by one embodiment of ^R1 . Furthermore, ^R3 is preferably a hydrogen atom or an alkyl group.
X ¹ is preferably —O— or —NR ³ —, more preferably —O— or —NH—, and further preferably —O—.

In the formula (1), L ¹ represents a linking group having a valence of (n+1), provided that when m represents an integer of 2 or greater, multiple L ^1s may be the same or different.
Here, the (n+1)-valent linking group is preferably an (n+1)-valent hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, in which some of the carbon atoms constituting the hydrocarbon group may be substituted with heteroatoms, and more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may contain an oxygen atom or a nitrogen atom.

The number of carbon atoms contained in the (n+1)-valent linking group is not particularly limited, and is preferably 1 to 24, and more preferably 1 to 10.
The (n+1)-valent linking group is preferably a divalent linking group or a trivalent linking group.

Examples of the divalent linking group that is a preferred embodiment of ^L1 include an optionally substituted divalent hydrocarbon group, an optionally substituted divalent heterocyclic group, -O-, -S-, -N(Q)-, -CO-, or a combination thereof, where Q represents a hydrogen atom or a substituent.
Examples of the divalent hydrocarbon group include divalent aliphatic hydrocarbon groups such as alkylene groups having 1 to 10 carbon atoms, alkenylene groups having 1 to 10 carbon atoms, and alkynylene groups having 1 to 10 carbon atoms, and divalent aromatic hydrocarbon groups such as arylene groups.
Examples of the divalent heterocyclic group include a divalent aromatic heterocyclic group, and specific examples thereof include a pyridylene group (pyridine-diyl group), a pyridazine-diyl group, an imidazole-diyl group, a thienylene group (thiophene-diyl group), and a quinolylene group (quinoline-diyl group).
Examples of groups combining these include groups combining at least two or more selected from the group consisting of the above-mentioned divalent hydrocarbon groups, divalent heterocyclic groups, -O-, -S-, -N(Q)-, and -CO-. Examples include -O-divalent hydrocarbon group-, -divalent hydrocarbon group -O-, and -divalent hydrocarbon group -N(Q)-.
^L2 is preferably a divalent linking group formed by combining at least two or more groups selected from the group consisting of a linear alkylene group having 1 to 10 carbon atoms which may have a substituent, a branched alkylene group having 3 to 10 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, an arylene group having 6 to 12 carbon atoms which may have a substituent, -O-, and -N(Q)-, and more preferably a divalent linking group formed by combining at least two or more groups selected from the group consisting of a linear alkylene group having 1 to 10 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, -O-, and -NH-.
[0049] Note that examples of the substituent which the above-mentioned divalent hydrocarbon group (including an alkylene group) and divalent heterocyclic group may have, as well as the substituent represented by one embodiment of Q, include the groups exemplified as the substituent represented by one embodiment of ^R1 above.

Furthermore, examples of the trivalent linking group that is a preferred embodiment of ^L1 include linking groups formed by removing one hydrogen atom from a nitrogen atom of a dialkylamine and two hydrogen atoms from an alkyl group, and among these, -N(C ₂ H ₄ -)(C ₂ H ₄ -) is preferred.

In the above formula (1), P represents a photoalignable group.
Here, the photo-alignable group refers to a group having a photo-alignment function that induces rearrangement or an anisotropic chemical reaction when irradiated with anisotropic light (e.g., plane polarized light), and a photo-alignable group that undergoes at least one of dimerization and isomerization due to the action of light is preferred, as it has excellent alignment uniformity and good thermal and chemical stability.

Suitable examples of photo-alignable groups that dimerize under the action of light include groups having a skeleton of at least one derivative selected from the group consisting of cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, maleimide derivatives, and benzophenone derivatives.
On the other hand, suitable examples of the photo-alignable group that isomerizes under the action of light include groups having a skeleton of at least one compound selected from the group consisting of azobenzene compounds, stilbene compounds, spiropyran compounds, cinnamic acid compounds, and hydrazono-β-ketoester compounds.

The photoalignable group is preferably a group having a skeleton of at least one derivative selected from the group consisting of cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, and maleimide derivatives, or a group having a skeleton of at least one compound selected from the group consisting of azobenzene compounds, stilbene compounds, and spiropyran compounds, with groups having a cinnamic acid derivative skeleton or a coumarin derivative skeleton being more preferred.

As the repeating unit represented by formula (1) above, a repeating unit represented by any of the following formulas (3) to (5) is preferred, and a repeating unit represented by formula (5) below is more preferred, because this results in better liquid crystal alignment properties. Note that the definitions of ^R1 and ^X1 in formulas (3) to (5) below are the same as the definitions of ^R1 and ^X1 in formula (1) above. Furthermore, multiple ^R1s may be the same or different, and multiple ^X1s may be the same or different.

In the above formulas (3) to (5), L ³ and L ⁴ each independently represent a single bond or a divalent linking group.
Here, examples of the divalent linking group represented by one embodiment of ^L3 and ^L4 include the same as those exemplified as the divalent linking group represented by a preferred embodiment of ^L1 in the above formula (1).

In the above formulas (3) to (5), R ^A1 , R ^A2 , R ^A3 and R ^A4 each independently represent a hydrogen atom or a substituent.
Here, examples of the substituent represented by one embodiment of R ^A1 , R ^A2 , R ^A3 and R ^A4 include the groups exemplified as the substituent represented by one embodiment of R ^1. Among them, an alkoxy group is preferable, and a methoxy group is more preferable.

Specific examples of the repeating unit represented by any one of the above formulas (1) or (3) to (5) include the following.

The content of the repeating unit represented by formula (1) in the photoalignment polymer of the present invention is not particularly limited, but in order to improve liquid crystal alignment, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to all repeating units of the photoalignment polymer. The upper limit of the content is preferably 80% by mass or less, more preferably 65% by mass or less, and even more preferably 50% by mass or less.

[Repeating unit represented by formula (2)]
The photoalignable polymer of the present invention has a repeating unit represented by the following formula (2).

In the above formula (2), R ² represents a hydrogen atom or a substituent.
Here, examples of the substituent represented by one embodiment of ^R2 include the groups exemplified as the substituent represented by one embodiment of ^R1 above.
^R2 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group.

In the above formula (2), X ² represents —O—, —S—, or —NR ³ —, and R ³ represents a hydrogen atom or a substituent.
Here, examples of the substituent represented by one embodiment of ^R3 include the groups exemplified as the substituent represented by one embodiment of ^R1 . Furthermore, ^R3 is preferably a hydrogen atom or an alkyl group.
X ² is preferably —O— or —NR ³ —, more preferably —O— or —NH—, and further preferably —O—.

In the above formula (2), ^L2 represents a single bond or a divalent linking group.
Here, examples of the divalent linking group represented by one embodiment of ^L2 include the same groups as those exemplified as the divalent linking group represented by the preferred embodiment of ^L1 in the above formula (1).

In the above formula (2), A represents an acid-cleavable group represented by the following formula (B1) or (B2), which decomposes under the action of an acid to generate a polar group. In the following formulas (B1) and (B2), * represents a bonding position.
Here, the acid-cleavable group represented by the following formula (B1) or (B2) is cleaved by the action of an acid, resulting in the elimination of a group containing a fluorine atom or a silicon atom (i.e., Y in the following formulas (B1) and (B2)) and the generation of a polar group.

In the above formulas (B1) and (B2), L ^b1 and L ^b2 each independently represent a single bond or a divalent linking group.
Here, examples of the divalent linking group represented by one embodiment of L ^b1 and L ^b2 include the same as those exemplified as the divalent linking group represented by the preferred embodiment of L ¹ in the above formula (1). Among them, -O-divalent hydrocarbon group- is preferred, and -O-straight-chain alkylene group having 1 to 10 carbon atoms- is more preferred.

In the present invention, L ^b1 and L ^b2 are preferably divalent linking groups because this improves the coatability of the composition for forming the upper layer (optically anisotropic layer) (hereinafter also abbreviated as "upper layer coatability").

In the above formulas (B1) and (B2), Y represents a group containing a fluorine atom or a silicon atom. However, the two Ys in the above formula (B1) may be the same or different.

The total number of fluorine atoms and silicon atoms contained in the group containing a fluorine atom or a silicon atom is not particularly limited, and is preferably 1 to 30, more preferably 5 to 25, and even more preferably 10 to 20, for reasons of improving the liquid crystal alignment properties.
The group containing a fluorine atom or a silicon atom is preferably a so-called organic group (a group containing a carbon atom). The number of carbon atoms contained in the group containing a fluorine atom or a silicon atom is not particularly limited, and is preferably 1 to 30, more preferably 3 to 20, and even more preferably 5 to 10, for the reason that the liquid crystal alignment property becomes better.
Examples of the group containing a fluorine atom or a silicon atom include an alkyl group containing a fluorine atom and a group containing a polydialkylsiloxane chain.

As the alkyl group containing a fluorine atom, a group represented by the following formula (F) is preferred because it provides better liquid crystal alignment properties: In the following formula (F), * represents a bonding position.
Formula (F) *-L ^b3 -Cf
Here, L ^b3 represents a single bond or a divalent linking group. Examples of the divalent linking group represented by one embodiment of L ^b3 include the same groups as those exemplified as the divalent linking groups represented by the preferred embodiment of L ¹ in the above formula (1).
Furthermore, Cf represents a fluorine atom-containing alkyl group, which is an alkyl group containing a fluorine atom, and is preferably a perfluoroalkyl group.
The number of carbon atoms in the fluorine atom-containing alkyl group is not particularly limited, and is preferably 1 to 30, more preferably 3 to 20, and even more preferably 5 to 10, for the reason that the liquid crystal alignment property becomes better.
The number of fluorine atoms contained in the fluorine atom-containing alkyl group is not particularly limited, but is preferably 1 to 30, more preferably 5 to 25, for the reason that the liquid crystal alignment property becomes better.

In the formulas (B1) and (B2), R ^b1 and R ^b2 each independently represent a hydrogen atom or a substituent, provided that the two R ^b2 in the formula (B2) may be the same or different and may be bonded to each other to form a ring.
Here, examples of the substituent represented by one embodiment of R ^b1 and R ^b2 include the groups exemplified as the substituent represented by one embodiment of R ¹ above.
The substituent represented by one embodiment of R ^b1 is preferably an alkyl group, more preferably a methyl group or an ethyl group.
The substituent represented by one embodiment of R ^b2 is preferably an alkyl group (e.g., a methyl group, an ethyl group), or a ring formed by two R ^b2s bonding to each other (e.g., a cyclopentane ring, a cyclohexane ring).

In the present invention, A in the above formula (2) is preferably an acid-cleavable group represented by the above formula (B1) because this results in better liquid crystal alignment properties.

Specific examples of the repeating unit represented by the above formula (2) include the following: In the following specific examples, "Me" represents a methyl group.

The content of the repeating unit represented by the above formula (2) in the photoalignment polymer of the present invention is not particularly limited, but in order to improve liquid crystal alignment properties, it is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, of all repeating units in the photoalignment polymer. The upper limit of the content is preferably 75% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[Repeating unit having a crosslinkable group]
The photoalignable polymer may further have a repeating unit having a crosslinkable group.
The type of crosslinkable group is not particularly limited, and examples thereof include known crosslinkable groups. Among these, a cationically polymerizable group or a radically polymerizable group is preferred in terms of excellent adhesion to an upper layer disposed on the binder layer.

Examples of cationically polymerizable groups include epoxy groups, epoxycyclohexyl groups, and oxetanyl groups.

Examples of radically polymerizable groups include acryloyl groups, methacryloyl groups, vinyl groups, styryl groups, and allyl groups.

The structure of the main chain of the repeating unit having a crosslinkable group is not particularly limited, and examples thereof include known structures. For example, a skeleton selected from the group consisting of (meth)acrylic, styrene, siloxane, cycloolefin, methylpentene, amide, and aromatic ester skeletons is preferred.
Among these, a skeleton selected from the group consisting of a (meth)acrylic, a siloxane, and a cycloolefin skeleton is more preferred, and a (meth)acrylic skeleton is even more preferred.

As the repeating unit having a crosslinkable group, a repeating unit represented by the following formula (C) is preferred because it provides better liquid crystal alignment properties.

In the above formula (C), R ^C1 represents a hydrogen atom or a substituent.
Here, examples of the substituent represented by one embodiment of R ^C1 include the groups exemplified as the substituent represented by one embodiment of R ¹ above.
R ^C1 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group.

In the above formula (C), L ^C1 represents a single bond or a divalent linking group.
Here, examples of the divalent linking group represented by one embodiment of L ^C1 include the same groups as those exemplified as the divalent linking group represented by the preferred embodiment of L ¹ in the above formula (1).
For reasons that result in better liquid crystal alignment, L ^C1 is preferably a divalent linking group combining at least two groups selected from the group consisting of an optionally substituted linear alkylene group having 1 to 10 carbon atoms, an optionally substituted branched alkylene group having 3 to 10 carbon atoms, an optionally substituted cyclic alkylene group having 3 to 10 carbon atoms, an optionally substituted arylene group having 6 to 12 carbon atoms, -O-, -CO-, and -N(Q)-, and more preferably a divalent linking group combining at least two groups selected from the group consisting of an optionally substituted linear alkylene group having 1 to 10 carbon atoms, an optionally substituted branched alkylene group having 3 to 10 carbon atoms, an optionally substituted cyclic alkylene group having 3 to 10 carbon atoms, -O-, -CO-, and -NH-. Q represents a hydrogen atom or a substituent.
Note that examples of the substituent that the above-mentioned alkylene group or arylene group may have, and the substituent represented by one embodiment of Q, include the groups exemplified as the substituent represented by one embodiment of ^R1 above.

In the above formula (C), L ^C2 represents a (t+1)-valent linking group.
Here, the (t+1)-valent linking group is preferably a (t+1)-valent hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, in which some of the carbon atoms constituting the hydrocarbon group may be substituted with a heteroatom, for the reason that better liquid crystal alignment properties are obtained, and more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may contain an oxygen atom or a nitrogen atom.

The number of carbon atoms contained in the (t+1)-valent linking group is not particularly limited, and is preferably 1 to 24, more preferably 1 to 10, for the reason that the liquid crystal alignment property becomes better.
The (t+1)-valent linking group is preferably a divalent linking group. Suitable examples of the divalent linking group include the same as those exemplified as the divalent linking groups represented by the suitable embodiments of ^L1 in the above formula (1).

In the above formula (C), Z represents a crosslinkable group.
Here, examples of the crosslinkable group include the above-mentioned cationically polymerizable group and radically polymerizable group.

In the present invention, the crosslinkable group preferably represents a group represented by any one of the following formulae (C1) to (C4), because this improves the liquid crystal alignment property.

In the above formulas (C1) to (C4), * represents a bonding position.
In addition, in the above formula (C3), R ^C2 represents a hydrogen atom, a methyl group, or an ethyl group.
In addition, in the above formula (C4), R ^C3 represents a hydrogen atom or a methyl group.

In the above formula (C), t represents an integer of 1 or greater. Among these, integers of 1 to 5 are preferred, integers of 1 to 3 are more preferred, and 1 or 2 is even more preferred, as these result in better liquid crystal alignment properties.

Specific examples of repeating units having a crosslinkable group include the following.

The content of repeating units having crosslinkable groups in the photoalignment polymer of the present invention is not particularly limited, but is preferably 10% by mass or more, and more preferably 20% by mass or more, of all repeating units in the photoalignment polymer, because this improves liquid crystal alignment. The upper limit is not particularly limited, and is preferably 60% by mass or less, and more preferably 50% by mass or less.

Examples of monomers (radical polymerizable monomers) that form repeating units other than those listed above include acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylamide compounds, acrylonitrile, maleic anhydride, styrene compounds, and vinyl compounds.

The method for synthesizing the photoalignable polymer of the present invention is not particularly limited. For example, the polymer can be synthesized by mixing monomers that form the repeating units represented by the above-mentioned formulas (1) and (2) and monomers that form other repeating units, such as repeating units having a crosslinkable group, and polymerizing the mixture in an organic solvent using a radical polymerization initiator.

The weight average molecular weight (Mw) of the photoalignable polymer of the present invention is not particularly limited, but is preferably 10,000 to 500,000, more preferably 10,000 to 300,000, and even more preferably 30,000 to 150,000, because this improves the liquid crystal alignment property.
Here, the weight average molecular weight and number average molecular weight in the present invention are values measured by gel permeation chromatography (GPC) under the conditions shown below.
Solvent (eluent): THF (tetrahydrofuran)
・Device name: TOSOH HLC-8320GPC
Column: Three TOSOH TSKgel Super HZM-H (4.6 mm x 15 cm) connected together Column temperature: 40°C
Sample concentration: 0.1% by mass
・Flow rate: 1.0ml/min
Calibration curve: TOSOH TSK standard polystyrene calibration curve using 7 samples with Mw = 2,800,000 to 1,050 (Mw/Mn = 1.03 to 1.06)

[Binder composition]
The binder composition of the present invention is a composition containing the photoalignable polymer of the present invention, a binder, and a photoacid generator.
The content of the photoalignable polymer contained in the binder composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the binder described below.
The content of the photoacid generator contained in the binder composition of the present invention is preferably 0.5 to 50 parts by mass, more preferably 2.5 to 25 parts by mass, per 100 parts by mass of the binder described below.

〔binder〕
The type of binder contained in the binder composition of the present invention is not particularly limited, and may be a resin that simply dries and solidifies, such as one that is composed only of a resin that is not polymerizable itself (hereinafter also referred to as a "resin binder"), or may be a polymerizable compound.

<Resin binder>
Examples of the resin binder include epoxy resin, diallyl phthalate resin, silicone resin, phenol resin, unsaturated polyester resin, polyimide resin, polyurethane resin, melamine resin, urea resin, ionomer resin, ethylene ethyl acrylate resin, acrylonitrile acrylate styrene copolymer resin, acrylonitrile styrene resin, acrylonitrile chlorinated polyethylene styrene copolymer resin, ethylene vinyl acetate resin, ethylene vinyl alcohol copolymer resin, acrylonitrile butadiene styrene copolymer resin, vinyl chloride resin, chlorinated polyethylene resin, polyvinylidene chloride resin, cellulose acetate resin, fluororesin, polyoxymethylene resin, polyamide resin, polyarylate, Examples of the resin include acrylate resin, thermoplastic polyurethane elastomer, polyether ether ketone resin, polyether sulfone resin, polyethylene, polypropylene, polycarbonate resin, polystyrene, polystyrene-maleic acid copolymer resin, polystyrene-acrylic acid copolymer resin, polyphenylene ether resin, polyphenylene sulfide resin, polybutadiene resin, polybutylene terephthalate resin, acrylic resin, methacrylic resin, methylpentene resin, polylactic acid, polybutylene succinate resin, butyral resin, formal resin, polyvinyl alcohol, polyvinylpyrrolidone, ethyl cellulose, carboxymethyl cellulose, gelatin, and copolymer resins thereof.

<Polymerizable compound>
Examples of the polymerizable compound include epoxy-based monomers, (meth)acrylic-based monomers, and oxetanyl-based monomers, with epoxy-based monomers and (meth)acrylic-based monomers being preferred.
Furthermore, a polymerizable liquid crystal compound may be used as the polymerizable compound.

Examples of epoxy group-containing monomers that are epoxy-based monomers include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, brominated bisphenol A-type epoxy resins, bisphenol S-type epoxy resins, diphenyl ether-type epoxy resins, hydroquinone-type epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, fluorene-type epoxy resins, phenol novolac-type epoxy resins, ortho-cresol novolac-type epoxy resins, trishydroxyphenylmethane-type epoxy resins, trifunctional epoxy resins, tetraphenylolethane-type epoxy resins, dicyclopentadienephenol-type epoxy resins, hydrogenated bisphenol A-type epoxy resins, bisphenol A-nucleus-containing polyol-type epoxy resins, polypropylene glycol-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, glyoxal-type epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins.

(Meth)acrylic monomers, such as acrylate and methacrylate monomers, include trifunctional monomers such as trimethylolpropane triacrylate, trimethylolpropane PO (propylene oxide)-modified triacrylate, trimethylolpropane EO (ethylene oxide)-modified triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate. Also, examples of tetrafunctional or higher monomers include pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol hexamethacrylate.

The polymerizable liquid crystal compound is not particularly limited, and examples thereof include compounds that can be aligned in any of homeotropic alignment, homogeneous alignment, hybrid alignment, and cholesteric alignment.
Generally, liquid crystal compounds can be classified into rod-shaped and discotic types based on their shape. Furthermore, each type can be divided into low-molecular-weight and high-molecular-weight types. High-molecular-weight compounds generally refer to those with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). While any liquid crystal compound can be used in the present invention, rod-shaped or discotic liquid crystal compounds (discotic liquid crystal compounds) are preferred. Furthermore, liquid crystal compounds that are monomers or have a relatively low molecular weight with a degree of polymerization of less than 100 are preferred.
Examples of the polymerizable group contained in the polymerizable liquid crystal compound include an acryloyl group, a methacryloyl group, an epoxy group, and a vinyl group.
By polymerizing such a polymerizable liquid crystal compound, the alignment of the liquid crystal compound can be fixed. After the liquid crystal compound is fixed by polymerization, it is no longer necessary for the liquid crystal compound to exhibit liquid crystallinity.

Preferred examples of rod-shaped liquid crystal compounds include those described in claim 1 of JP-A-11-513019 or paragraphs [0026] to [0098] of JP-A-2005-289980. Preferred examples of discotic liquid crystal compounds include those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038.

As the polymerizable liquid crystal compound, a liquid crystal compound with reverse wavelength dispersion can be used.
Here, in this specification, the liquid crystal compound having "reverse wavelength dispersion" refers to a compound in which, when the in-plane retardation (Re) value of a retardation film produced using the compound is measured at a specific wavelength (visible light range), the Re value becomes equal to or higher as the measured wavelength increases.

The reverse wavelength dispersion liquid crystal compound is not particularly limited as long as it can form a reverse wavelength dispersion film as described above, and examples thereof include compounds represented by the general formula (I) described in JP-A-2008-297210 (particularly, the compounds described in paragraphs [0034] to [0039]), compounds represented by the general formula (1) described in JP-A-2010-084032 (particularly, the compounds described in paragraphs [0067] to [0073]), and compounds represented by the general formula (1) described in JP-A-2016-081035 (particularly, the compounds described in paragraphs [0043] to [0055]).
Further, JP-A-2011-006360, paragraphs [0027] to [0100], JP-A-2011-006361, paragraphs [0028] to [0125], JP-A-2012-207765, paragraphs [0034] to [0298], JP-A-2012-077055, paragraphs [0016] to [0345], WO12/141245, paragraphs [0017] to [0072], WO12/147904, paragraphs [0021] to [0088], and WO14/147904, paragraphs [0028] to [0115] of the compounds described in.

[Photoacid generator]
The binder composition of the present invention contains a photoacid generator.
The photoacid generator is not particularly limited, and is preferably a compound that responds to actinic rays with a wavelength of 300 nm or more, preferably 300 to 450 nm, and generates an acid. Furthermore, even if a photoacid generator is not directly sensitive to actinic rays with a wavelength of 300 nm or more, it can be preferably used in combination with a sensitizer, as long as it responds to actinic rays with a wavelength of 300 nm or more and generates an acid when used in combination with a sensitizer.
As the photoacid generator, a photoacid generator that generates an acid with a pKa of 4 or less is preferred, a photoacid generator that generates an acid with a pKa of 3 or less is more preferred, and a photoacid generator that generates an acid with a pKa of 2 or less is even more preferred. In the present invention, pKa basically refers to the pKa in water at 25°C. For those that cannot be measured in water, the pKa refers to the pKa measured after changing to a solvent suitable for measurement. Specifically, pKa values listed in a chemistry handbook or the like can be used as a reference. As acids with a pKa of 3 or less, sulfonic acid or phosphonic acid is preferred, and sulfonic acid is more preferred.

Examples of photoacid generators include onium salt compounds, trichloromethyl-s-triazines, sulfonium salts, iodonium salts, quaternary ammonium salts, diazomethane compounds, imide sulfonate compounds, and oxime sulfonate compounds. Of these, onium salt compounds, imide sulfonate compounds, and oxime sulfonate compounds are preferred, with onium salt compounds and oxime sulfonate compounds being more preferred. Photoacid generators can be used alone or in combination of two or more types.

The binder composition of the present invention may contain components other than the above-mentioned photoalignable polymer, binder, and photoacid generator.

[Polymerization initiator]
When a polymerizable compound is used as the binder, the binder composition of the present invention preferably contains a polymerization initiator.
The polymerization initiator is not particularly limited, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator depending on the type of polymerization reaction.
The polymerization initiator is preferably a photopolymerization initiator that can initiate a polymerization reaction by irradiation with ultraviolet light.
Examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, acridine and phenazine compounds, oxadiazole compounds, and acylphosphine oxide compounds.

〔solvent〕
The binder composition of the present invention preferably contains a solvent from the viewpoint of workability in forming the binder layer.
Examples of the solvent include ketones (e.g., acetone, 2-butanone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone), ethers (e.g., dioxane and tetrahydrofuran), aliphatic hydrocarbons (e.g., hexane), alicyclic hydrocarbons (e.g., cyclohexane), aromatic hydrocarbons (e.g., toluene, xylene, and trimethylbenzene), halogenated carbons (e.g., dichloromethane, dichloroethane, dichlorobenzene, and chlorotoluene), esters (e.g., methyl acetate, ethyl acetate, and butyl acetate), water, alcohols (e.g., ethanol, isopropanol, butanol, and cyclohexanol), cellosolves (e.g., methyl cellosolve and ethyl cellosolve), cellosolve acetates, sulfoxides (e.g., dimethyl sulfoxide), and amides (e.g., dimethylformamide and dimethylacetamide).
The solvents may be used alone or in combination of two or more.

[Binder layer]
The binder layer of the present invention is formed using the binder composition of the present invention described above, and is a layer whose surface has an alignment control ability. More specifically, the binder layer is formed by generating an acid from a photoacid generator in a coating film of the binder composition, and then performing a photoalignment treatment.
In other words, the method for forming the binder layer preferably includes a step (step 1) of generating an acid from a photoacid generator in a coating film obtained using the binder composition, and then subjecting the coating film to a photoalignment treatment to form a binder layer.
The term "having an alignment control ability" means having a function of aligning the liquid crystal compound disposed on the binder layer in a predetermined direction.
When the binder composition contains a polymerizable compound, in the above step 1, it is preferable to subject the coating film obtained using the above binder composition to a curing treatment, then to a treatment for generating an acid from a photoacid generator in the coating film (hereinafter, also simply referred to as an "acid generating treatment"), and then to a photoalignment treatment to form a binder layer.
As will be described later, the curing treatment and the acid generating treatment may be carried out simultaneously.
The method for carrying out the above-mentioned hardening treatment will be described in detail below.

The method for forming a coating film of the binder composition is not particularly limited, and examples thereof include a method in which the binder composition is applied onto a support and, if necessary, subjected to a drying treatment.
The support will be described in detail below.
An alignment layer may be disposed on the support.
The method for applying the binder composition is not particularly limited, and examples of the application method include spin coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and die coating.

Next, the coating film of the binder composition is subjected to a curing treatment and a treatment for generating an acid from the photoacid generator in the coating film (hereinafter also referred to as "acid generating treatment").
The curing treatment may be a light irradiation treatment or a heat treatment.
The conditions for the curing treatment are not particularly limited, but for polymerization by light irradiation, ultraviolet light is preferably used. The irradiation dose is preferably 10 mJ/cm ² to 50 J/cm ² , more preferably 20 mJ/cm ² to 5 J/cm ² , even more preferably 30 mJ/cm ² to 3 J/cm ² , and particularly preferably 50 to 1000 mJ/cm ^2. In order to promote the polymerization reaction, the treatment may be carried out under heating conditions.

The treatment of generating an acid from a photoacid generator in a coating film is a treatment of generating an acid by irradiating the binder composition with light to which the photoacid generator contained in the binder composition is sensitive. By carrying out this treatment, cleavage at the cleavable group proceeds, and a group containing a fluorine atom or a silicon atom is eliminated.
The light irradiation treatment carried out in the above treatment may be any treatment to which the photoacid generator is photosensitive, and examples thereof include a method of irradiating with ultraviolet light. Lamps that emit ultraviolet light, such as high-pressure mercury lamps and metal halide lamps, can be used as the light source. The irradiation dose is preferably 10 mJ/cm ² to 50 J/cm ² , more preferably 20 mJ/cm ² to 5 J/cm ² , even more preferably 30 mJ/cm ² to 3 J/cm ² , and particularly preferably 50 to 1000 mJ/cm ² .

The above-mentioned curing treatment and acid generation treatment may be carried out after the curing treatment, or may be carried out simultaneously. In particular, when the photoacid generator and polymerization initiator in the binder composition are sensitive to light of the same wavelength, carrying out the treatments simultaneously is preferable from the standpoint of productivity.

The method of photoalignment treatment performed on the coating film of the binder composition formed above (including the cured film of the binder composition that has been subjected to a curing treatment) is not particularly limited, and known methods can be used.
Examples of photo-alignment treatments include a method in which a coating film of the binder composition (including a cured film of the binder composition that has been cured) is irradiated with polarized light or unpolarized light from an oblique direction relative to the coating film surface.

In the photo-alignment treatment, the polarized light to be irradiated is not particularly limited, and examples thereof include linearly polarized light, circularly polarized light, and elliptically polarized light, with linearly polarized light being preferred.
Furthermore, the "oblique direction" in which unpolarized light is irradiated is not particularly limited as long as it is a direction inclined at a polar angle θ (0<θ<90°) with respect to the normal direction of the coating film surface, and can be appropriately selected depending on the purpose, but θ is preferably 20 to 80°.

The wavelength of the polarized or unpolarized light is not particularly limited as long as it is light to which the photo-alignable group is sensitive, and examples thereof include ultraviolet light, near ultraviolet light, and visible light, with near ultraviolet light of 250 to 450 nm being preferred.
Examples of light sources for irradiating polarized or non-polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps. The wavelength range of the ultraviolet or visible light obtained from such light sources can be limited by using an interference filter or color filter. Furthermore, linearly polarized light can be obtained by using a polarizing filter or polarizing prism on the light from these light sources.

The integrated amount of polarized or unpolarized light is not particularly limited, but is preferably 1 to 300 mJ/cm ² , and more preferably 5 to 100 mJ/cm ² .
The illuminance of polarized or unpolarized light is not particularly limited, but is preferably 0.1 to 300 mW/cm ² , more preferably 1 to 100 mW/cm ² .

Note that, although the above describes an embodiment in which the curing treatment and acid generation treatment are performed before the photo-alignment treatment, the present invention is not limited to this embodiment, and the curing treatment and acid generation treatment may be performed simultaneously during the photo-alignment treatment.

The thickness of the binder layer is not particularly limited, but is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm, as this improves liquid crystal alignment.

[Optical laminate]
The optical laminate of the present invention has the binder layer of the present invention and an optically anisotropic layer provided on the binder layer.
One preferred embodiment of the optical laminate of the present invention is one in which the optically anisotropic layer provided on the binder layer is formed using a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, and the binder layer and the optically anisotropic layer are laminated adjacent to each other.
The optical layered body of the present invention preferably has a support that supports the binder layer.
Preferred embodiments of the optical layered body of the present invention will be described in detail below.

[Support]
Examples of the support include a glass substrate and a polymer film.
Examples of materials for polymer films include cellulose-based polymers; acrylic polymers having acrylic ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene-based polymers; polycarbonate-based polymers; polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate; styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; polyolefin-based polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers; vinyl chloride-based polymers; amide-based polymers such as nylon and aromatic polyamides; imide-based polymers; sulfone-based polymers; polyethersulfone-based polymers; polyetheretherketone-based polymers; polyphenylene sulfide-based polymers; vinylidene chloride-based polymers; vinyl alcohol-based polymers; vinyl butyral-based polymers; arylate-based polymers; polyoxymethylene-based polymers; epoxy-based polymers; or polymers containing mixtures of these polymers.

The thickness of the support is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm. It is preferable that the support be peelable.

[Binder layer]
The binder layer is the binder layer of the present invention described above.

[Optical Anisotropic Layer]
The optically anisotropic layer is preferably formed using a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound.
Here, examples of the polymerizable liquid crystal composition for forming the optically anisotropic layer include compositions containing the polymerizable liquid crystal compound, polymerization initiator, solvent, and the like described as optional components in the binder composition of the present invention.

The thickness of the optically anisotropic layer is not particularly limited, but is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

[Method of manufacturing optical laminate]
The method for producing the optical laminate of the present invention is a method for producing a preferred embodiment of the optical laminate of the present invention described above, and includes a step (step 1) of generating an acid from a photoacid generator in a coating film obtained using the binder composition, and then subjecting the coating film to a photoalignment treatment to form a binder layer, and a step (step 2) of applying a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound onto the binder layer to form an optically anisotropic layer.

[Step 1]
Step 1 is a step of generating an acid from a photoacid generator in a coating film obtained using the binder composition, and then subjecting the coating film to a photoalignment treatment to form a binder layer.
The procedure for step 1 is as described above.

[Step 2]
Step 2 is a step of applying a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound onto the binder layer to form an optically anisotropic layer.
The method for applying the polymerizable liquid crystal composition is not particularly limited, and examples thereof include the application methods exemplified in step 1.

The optically anisotropic layer can be formed by subjecting a coating of the polymerizable liquid crystal composition to a heat treatment and then subjecting it to a curing treatment. The heat treatment can align the polymerizable liquid crystal compound.
In the above, the heating treatment and the hardening treatment are carried out separately, but the hardening treatment may be carried out under heating conditions.
In addition, depending on the type of polymerizable liquid crystal compound, when alignment can be achieved without carrying out heat treatment, heat treatment may not be carried out.
After heating the coating film, the coating film may be cooled, if necessary, before the curing treatment described below.

The conditions for the heat treatment are not particularly limited, as long as the temperature is such that the polymerizable liquid crystal compound is oriented. The heating temperature is generally preferably 30 to 100°C, more preferably 50 to 80°C. The heating time is preferably 0.5 to 20 minutes, more preferably 1 to 5 minutes.

The method of curing treatment is not particularly limited, and examples thereof include light irradiation treatment and heat treatment, with light irradiation treatment being preferred. As the light for the light irradiation treatment, ultraviolet light is preferred.
The conditions for light irradiation are not particularly limited, and the irradiation dose is preferably 10 mJ/cm ² to 50 J/cm ² , more preferably 20 mJ/cm ² to 5 J/cm ² , and even more preferably 30 mJ/cm ² to 3 J/cm ² .
In order to promote the polymerization reaction, the reaction may be carried out under heating conditions.

[Image display device]
The image display device of the present invention is an image display device having the optically anisotropic layer of the present invention or the optical laminate of the present invention.
The display element used in the image display device of the present invention is not particularly limited, and examples thereof include a liquid crystal cell, an organic electroluminescence (hereinafter abbreviated as "EL") display panel, and a plasma display panel.
Among these, a liquid crystal cell or an organic EL display panel is preferred, and a liquid crystal cell is more preferred. That is, the image display device of the present invention is preferably a liquid crystal display device using a liquid crystal cell as a display element, or an organic EL display device using an organic EL display panel as a display element.

[Liquid crystal display device]
A liquid crystal display device, which is one example of the image display device of the present invention, is a liquid crystal display device having the above-mentioned optically anisotropic layer of the present invention or the optical laminate of the present invention, and a liquid crystal cell.
The liquid crystal cell used in the liquid crystal display device is preferably in VA (Vertical Alignment) mode, OCB (Opticaly Compensated Bend) mode, IPS (In-Plane-Switching) mode, FFS (Fringe-Field-Switching) mode, or TN (Twisted Nematic) mode, but is not limited to these.

[Organic EL display device]
A preferred example of an organic EL display device, which is an example of the image display device of the present invention, is one having, from the viewing side, a polarizer, the optically anisotropic layer of the present invention or the optical laminate of the present invention, and an organic EL display panel in this order.

<Polarizer>
The polarizer is not particularly limited as long as it is a member that has the function of converting light into a specific linearly polarized light, and conventionally known absorptive polarizers and reflective polarizers can be used.
Examples of absorption-type polarizers include iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers include coated polarizers and stretched polarizers, both of which are applicable.
Furthermore, examples of methods for obtaining a polarizer by stretching and dyeing a laminated film in the state of forming a polyvinyl alcohol layer on a substrate include the methods described in Japanese Patent Nos. 5,048,120, 5,143,918, 4,691,205, 4,751,481, and 4,751,486.
Examples of reflective polarizers include polarizers in which thin films with different birefringence are stacked, wire grid polarizers, and polarizers in which a cholesteric liquid crystal having a selective reflection region is combined with a quarter-wave plate.
Among these, polarizers containing polyvinyl alcohol resins (polymers containing -CH ₂ -CHOH- as a repeating unit, in particular at least one selected from the group consisting of polyvinyl alcohol and ethylene-vinyl alcohol copolymers) are preferred because of their superior adhesion.

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

<Organic EL display panel>
An organic EL display panel is a component 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, an anode and a cathode, and may have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, etc. in addition to the light-emitting layer, and each of these layers may have other functions. Various materials can be used to form each layer.

The present invention will be explained in more detail below with reference to the following examples. The materials, amounts used, ratios, processing details, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[Monomer synthesis]

4 g of p-hydroxycinnamic acid, 9.5 g of hydroxyethyl methacrylate, and 18.4 g of triphenylphosphine were weighed into a 100 mL three-necked flask, and 10 mL of tetrahydrofuran (THF) was added to completely dissolve the mixture. While stirring at 0°C, 16.4 g of diisopropyl azodicarboxylate (DIAD) was added dropwise over 30 minutes.
After the dropwise addition was completed, the mixture was heated at room temperature for 4 hours, diluted with 100 mL of ethyl acetate, and washed with saturated saline solution. The obtained organic layer was dried over anhydrous magnesium sulfate, and the obtained solution was concentrated and subjected to silica gel column chromatography to obtain 4.0 g of monomer mA-1 represented by the above formula mA-1 as a pale yellow liquid (yield: 43%).

Example 1 (Synthesis of Photo-Orientable Polymer P-1)
A flask equipped with a condenser, a thermometer, and a stirrer, 1.0 part by mass of monomer mA-1, 1.0 part by mass of monomer mB-1 represented by the following formula mB-1, 1.0 part by mass of monomer mC-1a represented by the following formula mC-1a, 0.06 parts by mass of 2,2'-azobis (isobutyronitrile) as a polymerization initiator, and 6 parts by mass of toluene as a solvent were charged, and nitrogen was flowed into the flask at 30 mL / min, and the reaction was carried out for 7 hours by water bath heating at 70 ° C. After completion of the reaction, the mixture was allowed to cool to room temperature, and the resulting polymer solution was poured into a large excess of methanol to precipitate the polymer, and the recovered precipitate was filtered off, washed with a large amount of methanol, and then vacuum dried at 40 ° C. for 2 hours to obtain a photo-aligned polymer P-1a represented by the following formula P-1a.
Next, 1.5 parts by mass of dimethylacetamide and 0.5 parts by mass of triethylamine were added to 1.0 part by mass of the photoalignable polymer P-1a, and the mixture was reacted for 2 hours by heating in a water bath at 60° C. After completion of the reaction, the mixture was allowed to cool to room temperature, and the resulting polymer solution was poured into a large excess of methanol to precipitate the polymer. The recovered precipitate was filtered, washed with a large amount of methanol, and then vacuum-dried at 40° C. for 10 hours to obtain a photoalignable polymer P-1 represented by the following formula P-1.
The alphabets in the following formula P-1 indicate the content (% by mass) of each repeating unit relative to the total amount of repeating units, and a, b, and c were 26%, 37%, and 37% by mass, respectively. The weight-average molecular weight was 200,000.

[Example 1 (Preparation of Optical Laminate (1A)]
An optically anisotropic layer-forming composition (1A-a) containing a discotic liquid crystal compound having the following composition was applied to a cellulose acylate film TG40 (manufactured by Fujifilm Corporation, thickness 40 μm) using a Giesser coater to form a composition layer. Then, while holding both ends of the film, a cooling plate (9°C) was placed on the side of the film on which the coating film was formed so as to be 5 mm away from the film, and a heater (110°C) was placed on the side opposite the side on which the coating film was formed so as to be 5 mm away from the film, and the film was dried for 90 seconds.
The resulting film was then heated in hot air at 116°C for 1 minute, and irradiated with ultraviolet light at a dose of 150 mJ/ ^cm2 using a 365 nm UV-LED while purging with nitrogen to an atmosphere with an oxygen concentration of 100 ppm by volume or less. The resulting coating film was then annealed in hot air at 115°C for 25 seconds.
Next, at room temperature, the film was irradiated with UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at 7.9 mJ/cm ² (wavelength: 313 nm) through a wire grid polarizer to form an optically anisotropic layer (1A-a) having alignment control ability on its surface, which corresponds to the lower layer (binder layer).
The film thickness of the optically anisotropic layer (1A-a) thus formed was 1.0 μm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the thickness direction retardation Rth at a wavelength of 550 nm was 40 nm. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface.

----------------------------------------------------------------------------------
Optically anisotropic layer-forming composition (1A-a)
----------------------------------------------------------------------------------
8 parts by mass of discotic liquid crystal compound 1 below; 2 parts by mass of discotic liquid crystal compound 2 below; 90 parts by mass of discotic liquid crystal compound 3 below; 12 parts by mass of polymerizable monomer 1 below; 3 parts by mass of polymerization initiator S-1 (oxime type) below; 3 parts by mass of photoacid generator D-1 below; 0.6 parts by mass of photoalignable polymer P-1 above; 0.2 parts by mass of triisopropylamine
o-Xylene 634 parts by mass -----------------------------------------------------------------

Discotic liquid crystal compound 1

Discotic liquid crystal compound 2

Discotic liquid crystal compound 3

Polymerizable Monomer 1

Polymerization initiator S-1

Photoacid generator D-1

Next, on the optically anisotropic layer (1A-a) prepared above, a composition for forming an optically anisotropic layer (1A-b) containing a discotic liquid crystal compound of the following composition was applied using a Giesser coater, and heated for 120 seconds with hot air at 95° C. Subsequently, the obtained composition layer was irradiated with UV (100 mJ/cm ² ) at 95° C. to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1A-b) corresponding to the upper layer.
The optically anisotropic layer (1A-b) had a thickness of 1.5 μm and a Δnd of 153 nm at a wavelength of 550 nm. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface.
When the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and −90° clockwise), the in-plane slow axis direction of the optically anisotropic layer (1b) was −14° when viewed from the optically anisotropic layer (1A-b) side.

----------------------------------------------------------------------------------
Optically anisotropic layer-forming composition (1A-b)
----------------------------------------------------------------------------------
80 parts by mass of the above discotic liquid crystal compound 1; 20 parts by mass of the above discotic liquid crystal compound 2; 1.8 parts by mass of the alignment film interface aligning agent 1 below; 10 parts by mass of the above polymerizable monomer 1; 5 parts by mass of the above polymerization initiator S-1 (oxime type); 0.1 parts by mass of the below fluorine-containing compound A; 0.2 parts by mass of the below fluorine-containing compound B; 0.1 parts by mass of the below fluorine-containing compound C; 2.1 parts by mass of the below antifoaming agent 1; 419 parts by mass of methyl ethyl ketone

Alignment film interface alignment agent 1

Fluorine-containing compound A (in the following formula, a and b represent the content (% by mass) of each repeating unit relative to all repeating units, a represents 90% by mass and b represents 10% by mass).

Fluorine-containing compound B (the value in each repeating unit represents the content relative to all repeating units)

Fluorine-containing compound C (the numerical value for each repeating unit represents the content relative to all repeating units)

Antifoaming agent 1

By the above procedure, an optical laminate (1A) was produced in which an optically anisotropic layer (1A-a) and an optically anisotropic layer (1A-b) were directly laminated on a long cellulose acylate film.

[Example 2]
Photoalignment polymer P-2 represented by formula P-2 below was synthesized in the same manner as photoalignment polymer P-1 synthesized in Example 1, except that monomer mA-2 represented by formula mA-2 below was used instead of monomer mA-1. The alphabets in each repeating unit in formula P-2 below represent the content (% by mass) of each repeating unit relative to the total repeating units, with a, b, and c being 26% by mass, 37% by mass, and 37% by mass, respectively. The weight-average molecular weight was 200,000.
Further, an optical laminate (2A) was produced in the same manner as in Example 1, except that the photoalignable polymer P-2 was used instead of the photoalignable polymer P-1.

[Example 3]
Photoalignment polymer P-3 represented by formula P-3 below was synthesized in the same manner as photoalignment polymer P-1 synthesized in Example 1, except that monomer mC-2a represented by formula mC-2a below was used instead of monomer mC-1a. The alphabets in each repeating unit in formula P-3 below represent the content (% by mass) of each repeating unit relative to all repeating units, with a, b, and c being 26% by mass, 37% by mass, and 37% by mass, respectively. The weight-average molecular weight was 150,000.
Further, an optical laminate (3A) was produced in the same manner as in Example 1, except that the photoalignable polymer P-3 was used instead of the photoalignable polymer P-1.

[Example 4]
Photoalignment polymer P-4 represented by formula P-4 below was synthesized in the same manner as photoalignment polymer P-1 synthesized in Example 1, except that monomer mB-2 represented by formula mB-2 below was used instead of monomer mB-1. The alphabets in each repeating unit in formula P-4 below represent the content (% by mass) of each repeating unit relative to the total repeating units, with a, b, and c being 26% by mass, 45% by mass, and 29% by mass, respectively. The weight-average molecular weight was 100,000.
Further, an optical laminate (4A) was produced in the same manner as in Example 1, except that the photoalignable polymer P-4 was used instead of the photoalignable polymer P-1.

[Example 5]
Photoalignment polymer P-5 represented by formula P-5 below was synthesized in the same manner as photoalignment polymer P-4 synthesized in Example 4, except that the blending amount of the monomer was changed and the content of the repeating unit of the synthesized photoalignment polymer was changed as follows. Note that the alphabet written in each repeating unit in formula P-4 below represents the content (% by mass) of each repeating unit relative to the total repeating units, with a, b, and c being 4% by mass, 37% by mass, and 59% by mass, respectively. The weight average molecular weight was 100,000.
Further, an optical laminate (5A) was produced in the same manner as in Example 1, except that the photoalignable polymer P-5 was used instead of the photoalignable polymer P-1.

[Comparative Example 1]
Photoalignment polymer H-1 represented by the following formula H-1 was synthesized in the same manner as photoalignment polymer P-1 synthesized in Example 1. The alphabets in each repeating unit in the following formula H-1 represent the content (% by mass) of each repeating unit relative to the total repeating units, with a, b, and c being 37% by mass, 26% by mass, and 37% by mass, respectively. The weight-average molecular weight was 80,000.
Further, an optical laminate (H1A) was produced in the same manner as in Example 1, except that the photoalignable polymer H-1 was used instead of the photoalignable polymer P-1.

[Comparative Example 2]
Photoalignment polymer H-2 represented by the following formula H-2 was synthesized in the same manner as photoalignment polymer P-1 synthesized in Example 1. The alphabets in each repeating unit in the following formula H-2 represent the content (% by mass) of each repeating unit relative to the total repeating units, with a, b, and c being 40% by mass, 24% by mass, and 36% by mass, respectively. The weight-average molecular weight was 50,000.
Further, an optical laminate (H2A) was produced in the same manner as in Example 1, except that the photoalignable polymer H-2 was used instead of the photoalignable polymer P-1.

[evaluation]
[Liquid crystal alignment]
Two polarizing plates were placed in a crossed Nicol configuration, and the prepared optical laminate was placed between them, and the degree of light leakage and the surface condition were observed with a polarizing microscope. The results are shown in Table 1 below.
AA: The liquid crystal directors are uniformly aligned, resulting in excellent display performance.
A: There is no disturbance in the liquid crystal director, and the surface state is stable.
B: The liquid crystal director is partially disordered, and the surface state is stable.
C: The liquid crystal director is significantly disordered, the surface state is unstable, and the display performance is very poor.
Here, the stable surface state refers to a state in which there are no defects such as unevenness or poor alignment when the optical laminate is placed between two polarizing plates arranged in a crossed Nicol state and observed.
The liquid crystal director refers to a vector in the direction in which the major axes of liquid crystal molecules are aligned (main alignment axis).
In Table 1 below, the liquid crystal alignment properties are evaluated not only for the upper layer but also for the lower layer, but the evaluation of the lower layer was carried out using a sample in which an optically anisotropic layer corresponding to the lower layer (binder layer) was formed on a support.

[Upper layer coating properties]
The surface energy of the prepared binder layer (lower layer) was measured by the method described below, and the coatability of the upper layer was evaluated according to the following criteria. The results are shown in Table 1. The measurements were performed using binder layers (lower layers) prepared at the annealing temperatures shown in Table 1.
<Method for measuring surface energy>
The surface energy of the binder layer-forming composition and the surface energy of the binder layer after heating (measured at 110°C, 120°C, and 135°C, respectively) following irradiation with a 365 nm UV-LED were measured. The surface energy was measured using a contact angle meter ["CA-X" type contact angle meter, manufactured by Kyowa Interface Science Co., Ltd.]. The specific measurement method is as follows.
The measurement object was spin-coated onto a quartz substrate. If a solvent was contained, it was dried to form a film. Next, using a contact angle meter, a 1.0 mm diameter droplet was created on the tip of a needle using pure water as the liquid in a dry state (20°C/65% RH), and this was brought into contact with the surface of the spin-coated film to form a droplet on the film. The contact angle was measured as the angle between the tangent to the liquid surface and the film surface at the point where the film and liquid come into contact, and the angle on the side containing the liquid. In addition, the contact angle was measured using methylene iodide instead of water, and the surface free energy defined below was calculated.
Here, the surface free energy ( ^γsv : unit, mN/m) is defined as the value γsv (=γsd + γsh) expressed as the sum of γsd and γsh calculated from the contact angles _θH2O and _{θCH2I2 of pure water H2O and methylene iodide CH2I2 , respectively} , experimentally determined on an antireflection film with reference to ^{D. K.} _Owens : ^J. Appl. ^Polym . ^Sci ., 13, 1741 (1969):
a. 1+cosθ _H2O =2√γs ^d (√γ _H2O ^d /γ _H2O ^v )+2√γs ^h (√γ _H2O ^h /γ _H2O ^v )
b. 1+cosθ _CH2I2 =2√γs ^d (√γ _CH2I2 ^d /γ _CH2I2 ^v )+2√γs ^h (√γ _CH2I2 ^h /γ _CH2I2 ^v )
γ _H2O ^d =21.8, γ _H2O ^h =51.0, γ _H2O ^v =72.8
γ _CH2I2 ^d = 49.5, γ _CH2I2 ^h = 1.3, γ _CH2I2 ^v = 50.8
<Evaluation criteria>
A: The difference in surface energy is 20 mN/m or more. B: The difference in surface energy is 10 N/m or more but less than 20 mN/m. C: The difference in surface energy is less than 10 N/m.

The results shown in Table 1 above indicate that when a photoalignable polymer not having the repeating unit represented by formula (1) was used, the liquid crystal alignment property of the upper layer was poor (Comparative Examples 1 and 2). Furthermore, in Comparative Example 2, it was found that when the lower layer (binder layer) was formed at 115°C, the coatability of the upper layer was poor.
On the other hand, when a photoalignable polymer having a repeating unit represented by the above formula (1) is used, it was found that the liquid crystal alignment property of the upper layer is good and the coatability of the upper layer is also good (Examples 1 to 5).
Furthermore, a comparison between Example 1 and Example 2 revealed that when the repeating unit represented by the above formula (1) is a repeating unit represented by the above formula (5), the liquid crystal alignment property becomes better.
Furthermore, comparison of Example 1 with Examples 4 and 5 revealed that when A in the above formula (2) is an acid-cleavable group represented by the above formula (B1), the liquid crystal alignment property becomes better.

Claims (11)

The polymer has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2),
A photoalignable polymer , wherein the repeating unit represented by the formula (1) is a repeating unit represented by any one of the following formulas (3) to (5) :

In the formulas (1) and (2),
n represents 1 or 2, and m represents an integer of 1 to 10, provided that n and m do not represent 1 at the same time.
^R1 and ^R2 each independently represent a hydrogen atom or a substituent, provided that when n represents 2 or m represents an integer of 2 or greater, multiple ^R1s may be the same or different.
^X1 and ^X2 each independently represent -O-, -S-, or ^-NR3- , where ^R3 represents a hydrogen atom or a substituent, provided that when n represents 2 or m represents an integer of 2 or greater, multiple ^X1s may be the same or different.
L ¹ represents a linking group having a valence of (n+1), provided that when m represents an integer of 2 or greater, multiple L ^1s may be the same or different.
^L2 represents a single bond or a divalent linking group.
P represents a photoalignable group.
A represents an acid-cleavable group represented by the following formula (B1) or (B2), which is decomposed by the action of an acid to generate a polar group.

In the formulas (B1) and (B2),
* indicates the bond position.
L ^b1 and L ^b2 each independently represent a single bond or a divalent linking group.
Y represents a group containing a fluorine atom or a silicon atom, provided that the two Ys in the formula (B1) may be the same or different.
R ^b1 and R ^b2 each independently represent a hydrogen atom or a substituent, provided that the two R ^b2 in formula (B2) may be the same or different and may be bonded to each other to form a ring.

In the formulas (3) to (5),
R ¹ represents a hydrogen atom or a substituent, provided that multiple R ^1s may be the same or different.
X ¹ represents —O—, —S—, or —NR ³ —, and R ³ represents a hydrogen atom or a substituent, provided that multiple X ^1s may be the same or different.
L3 and L4 ^{each independently} represent a single bond or a divalent linking group.
R ^A1 , R ^A2 , R ^A3 and R ^A4 each independently represent a hydrogen atom or a substituent. The photoalignable polymer according to claim 1 , further comprising a repeating unit having a crosslinkable group. The photoalignable polymer according to claim 2 , wherein the repeating unit having a crosslinkable group is a repeating unit represented by the following formula (C):

In the formula (C),
R ^C1 represents a hydrogen atom or a substituent.
L ^C1 represents a single bond or a divalent linking group.
L ^C2 represents a (t+1)-valent linking group.
Z represents a crosslinkable group.
t represents an integer of 1 or more, and when t is an integer of 2 or more, multiple Zs may be the same or different. The photoalignable polymer according to claim 2 or 3 , wherein the crosslinkable group is a group represented by any one of the following formulas (C1) to (C4):

In the formulae (C1) to (C4), * represents a bonding position.
In the formula (C3), R ^C2 represents a hydrogen atom, a methyl group, or an ethyl group.
In the formula (C4), R ^C3 represents a hydrogen atom or a methyl group. 5. The photoalignable polymer according to claim 1 , wherein the content of the repeating unit represented by formula (1) is 5 to 80% by mass. The photoalignable polymer according to any one of claims 1 to 5 , which has a weight average molecular weight of 10,000 to 500,000. A binder composition comprising the photoalignable polymer according to any one of claims 1 to 6 , a binder, and a photoacid generator. A binder layer formed using the binder composition according to claim 7 , the surface of which has an orientation control ability. The binder layer according to claim 8 ;
an optically anisotropic layer disposed on the binder layer. a step of generating an acid from the photoacid generator on a coating film obtained by using the binder composition according to claim 7 , and then subjecting the coating film to a photoalignment treatment to form a binder layer;
and applying a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound onto the binder layer to form an optically anisotropic layer. An image display device comprising the binder layer according to claim 8 or the optical laminate according to claim 9 .