JPWO2019003682A1 - Photo-alignment copolymer, photo-alignment film, optical laminate, and image display device - Google Patents

Abstract

Provided are a photo-alignment copolymer capable of producing a photo-alignment film excellent in liquid crystal alignment, and a photo-alignment film, an optical laminate, and an image display device manufactured using the same. The photo-alignable copolymer has a repeating unit A represented by the following formula (1) containing a photo-alignable group and a repeating unit B represented by the following formula (2) containing a cross-linkable group. The photo-alignment film is formed using a photo-alignment film composition containing a photo-alignment copolymer. The optical laminate has a photo-alignment film and an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound. The image display device has an optical laminate.

Description

  The present invention relates to a photo-alignable copolymer, a photo-alignment film, an optical laminate, and an image display device.

Optical films such as an optical compensation sheet and a retardation film are used in various image display devices from the viewpoint of eliminating coloration of an image and expanding a viewing angle.
Although a stretched birefringent film has been used as an optical film, it has recently been proposed to use an optically anisotropic layer using a liquid crystal compound instead of the stretched birefringent film.

  It is known that such an optically anisotropic layer is provided with an alignment film on a support on which the optically anisotropic layer is formed in order to align the liquid crystal compound. A photo-alignment film that has been subjected to a photo-alignment process instead of the process is known.

  For example, Patent Document 1 discloses an embodiment in which a polymer layer containing a compound containing a repeating unit having 2 to 3 photo-alignable groups is used as an alignment layer ([Claim 1] and [Claim 7]). [Claim 8]).

  Patent Document 2 discloses a liquid crystal alignment layer formed from a thermosetting film forming composition containing an acrylic copolymer having a photodimerization site such as a cinnamoyl group and a crosslinking agent ([Claims]). 1] [Claim 3] [Claim 11] <0028>).

JP-T-2003-505561 International Publication No. 2010/150748

  The present inventors have studied the polymers having a photo-alignment group described in Patent Documents 1 and 2, and the like. Depending on the type of the monomer, a photo-alignment film formed using the obtained polymer or copolymer may be used. It has been clarified that there is a case where the orientation of the liquid crystal compound of the above (hereinafter also abbreviated as “liquid crystal orientation”) may be poor.

  Accordingly, the present invention provides a photo-alignment copolymer capable of producing a photo-alignment film having excellent liquid crystal alignment, and a photo-alignment film, an optical laminate, and an image display device manufactured using the same. That is the task.

The present inventors have conducted intensive studies to achieve the above object, and as a result, produced by using a copolymer having a repeating unit containing two or more specific photo-alignment groups and a repeating unit containing a crosslinking group. It has been found that the liquid crystal alignment of the photo-alignment film to be obtained is good, and the present invention has been completed.
That is, the present inventors have found that the above-described objects can be achieved by the following configurations.

  [1] A photo-alignable copolymer having a repeating unit A represented by the formula (1) containing a photo-alignable group and a repeating unit B represented by the formula (2) containing a cross-linkable group.

[2] L ¹ in the formula (1) and L ² in the formula (2) each independently represent a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, The photo-alignable copolymer according to [1], which is a divalent linking group obtained by combining at least two or more groups selected from the group consisting of an arylene group, an ether group, a carbonyl group, and an imino group.

[3] The photo-alignable copolymer according to [1] or [2], wherein A in the formula (1) is a trivalent to hexavalent linking group.
[4] A in the formula (1) is an m-valent hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, and a part of carbon atoms constituting the hydrocarbon group is a hetero atom. The photo-alignable copolymer according to [1] or [2], which is a hydrocarbon group optionally substituted with an atom.
[5] The photo-alignable copolymer according to any one of [1] to [4], wherein A in the formula (1) is a linking group containing an alicyclic hydrocarbon group.

[6] The photo alignment according to any one of [1] to [5], wherein X in the formula (2) is a crosslinkable group represented by any of the formulas (3) to (5) described below. Copolymer.
[7] The photo-alignable copolymer according to [6], wherein X in the formula (2) is a crosslinkable group represented by the formula (3) or (4).

[8] In the formula (1), R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a halogen atom, a linear, branched or branched group having 1 to 20 carbon atoms. Cyclic alkyl group, linear halogenated alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, aryloxy group having 6 to 20 carbon atoms, cyano group , An amino group, and a photo-alignable copolymer according to any one of [1] to [7], which is a substituent selected from the group consisting of a group represented by formula (7) described below.
[9] The photo-alignment according to any one of [1] to [8], wherein at least R ⁴ of R ² , R ³ , R ⁴ , R ⁵ and R ^{6 in} the formula (1) represents a substituent. Copolymer.
[10] The photo-alignable copolymer according to any one of [1] to [9], wherein R ⁴ in the formula (1) is an electron-donating substituent.

[11] The photo-alignable copolymer according to any one of [1] to [10], wherein the content X of the repeating unit A and the content Y of the repeating unit B satisfy the following formula (8).
0.4 ≦ X / (X + Y) ≦ 0.8 (8)
[12] The photo-alignable copolymer according to [11], wherein the content X of the repeating unit A and the content Y of the repeating unit B satisfy the following formula (9).
0.45 ≦ X / (X + Y) ≦ 0.65 (9)

[13] A photo-alignment film formed using the photo-alignment film composition containing the photo-alignment copolymer according to any one of [1] to [12].
[14] An optical laminate having the photo-alignment film according to [13] and an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound.
[15] An image display device comprising the optical laminate according to [14].

  According to the present invention, there are provided a photo-alignment copolymer capable of producing a photo-alignment film having excellent liquid crystal alignment properties, and a photo-alignment film, an optical laminate, and an image display device manufactured using the same. be able to.

Hereinafter, the present invention will be described in detail.
The description of the components described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In addition, in this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.

[Photo-alignable copolymer]
The photoalignable copolymer of the present invention has a repeating unit A represented by the formula (1) containing a photoalignable group and a repeating unit B represented by the formula (2) containing a crosslinkable group. It is a photo-alignable copolymer.

In the above formula (1), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents a single bond or a divalent linking group, A represents an m-valent linking group, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent. Among R ² , R ³ , R ⁴ , R ⁵ and R ⁶ , two adjacent groups may be bonded to each other to form a ring. m represents an integer of 3 or more, and n represents an integer of m-1. A plurality of R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different, respectively.
In the above formula (2), R ⁷ represents a hydrogen atom or a methyl group, L ² represents a divalent linking group, and X represents a crosslinkable group.

A photo-alignment film produced using a copolymer having a repeating unit A represented by the formula (1) containing a photo-alignable group and a repeating unit B represented by the formula (2) containing a cross-linkable group is: Since the cinnamoyl group is a photo-alignment group that generates liquid crystal alignment ability by absorbing light, the liquid crystal alignment is improved.
Although this is not clear in detail, the present inventors speculate as follows.
In other words, since the repeating unit A contains a plurality of photo-alignment groups, after the photo-alignment film is formed, the site that interacts with the liquid crystal compound by increasing the concentration of the photo-alignment groups per unit area is increased. It is considered that the increase in the number and the inclusion of the crosslinkable group in the repeating unit B promoted the fixation of the alignment, and as a result, the liquid crystal alignment of the formed optical alignment film was improved.

The divalent linking group represented by L ¹ in the above formula (1) and L ² in the above formula (2) will be described.

  As the divalent linking group, the photo-alignable group easily interacts with the liquid crystal compound, and the liquid crystal alignment of the formed photo-alignment film is more improved. , A branched or cyclic alkylene group, an arylene group having 6 to 12 carbon atoms, an ether group (-O-), a carbonyl group (-C (= O)-), and an imino group (-NH-). It is preferably a divalent linking group obtained by combining at least two or more groups selected from the group.

As for the linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, specific examples of the linear alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group and a pentylene group. Hexylene group, decylene group and the like.
In addition, specific examples of the branched alkylene group include a dimethylmethylene group, a methylethylene group, a 2,2-dimethylpropylene group, and a 2-ethyl-2-methylpropylene group.
Further, as the cyclic alkylene group, specifically, for example, a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cyclooctylene group, a cyclodecylene group, an adamantane-diyl group, a norbornane-diyl group And exo-tetrahydrodicyclopentadiene-diyl group, among which a cyclohexylene group is preferable.

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

  Among these divalent linking groups, an ester bond (—C (＝ O) O—) combining a carbonyl group and an ether group, and a linking group combining a phenylene group and an ether group are more preferable. More preferably, it is -C (= O) O-.

Next, the m-valent linking group represented by A in the following formula (1) will be described.

  In the present invention, m represents an integer of 3 or more, preferably an integer of 3 to 6, more preferably an integer of 3 to 5, and still more preferably 3 or 4.

  In the present invention, A in the above formula (1) represents a substituent because the photo-alignment group easily interacts with the liquid crystal compound and the liquid crystal alignment of the photo-alignment film to be produced becomes better. A m-valent hydrocarbon group having 1 to 24 carbon atoms which may have a hydrocarbon group in which a part of carbon atoms constituting the hydrocarbon group may be substituted with a hetero atom (hereinafter, referred to as a hydrocarbon group) Abbreviated as “m-valent hydrocarbon group A”).

Specific examples of the m-valent hydrocarbon group A include groups represented by the following formulas (a1) to (a4). In the following formulas (a1) ~ (a4), ^{* L} represents a bonding position with ^{L 1} in the formula (1), an oxygen atom previous * is a carbonyl group in the formula (1) Shows the bonding position to the constituent carbon atom.

Examples of the substituent that the m-valent hydrocarbon group A may have include alkylene group, arylene group, and a substituent that the imino group may have, for example, alkyl group, alkoxy group, halogen atom, And a hydroxyl group.
As the alkyl group, for example, a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms is preferable, and an alkyl group having 1 to 8 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group) Group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, cyclohexyl group and the like), more preferably an alkyl group having 1 to 4 carbon atoms, and a methyl group or an ethyl group. Is particularly preferred.
As the alkoxy group, for example, an alkoxy group having 1 to 18 carbon atoms is preferable, and an alkoxy group having 1 to 8 carbon atoms (e.g., methoxy group, ethoxy group, n-butoxy group, methoxyethoxy group and the like) is more preferable. It is more preferably an alkoxy group of the formulas 1 to 4, 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 and an iodine atom, and among them, a fluorine atom and a chlorine atom are preferable.

  In the present invention, the m-valent hydrocarbon group A is an alicyclic group because the photo-alignment group easily interacts with the liquid crystal compound and the liquid crystal alignment of the formed photo-alignment film becomes better. It is preferably a linking group containing a hydrocarbon group, and more preferably a group represented by the above formula (a2).

Next, hydrogen atoms or substituents represented by R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in the following formula (1) will be described.

As R ² , R ³ , R ⁴ , R ⁵ and R ^{6 in the} above formula (1), the photo-alignment group easily interacts with the liquid crystal compound, and the liquid crystal alignment of the photo-alignment film to be produced is A hydrogen atom; or a halogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or a linear halogenation having 1 to 20 carbon atoms, for better reasons. From an alkyl group, 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 a group represented by the following formula (7) A substituent selected from the group consisting of:

In the above formula (7), * represents a bonding position to the benzene ring in the formula (1), and R ⁹ represents a monovalent organic group.

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

As for the linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, the linear alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, specifically, for example, a methyl group, Examples include an ethyl group and an n-propyl group.
As the branched alkyl group, an alkyl group having 3 to 6 carbon atoms is preferable, and specific examples include an isopropyl group and a tert-butyl group.
As the cyclic alkyl group, an alkyl group having 3 to 6 carbon atoms is preferable, and specific examples include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group.

  As the straight-chain halogenated alkyl group having 1 to 20 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms is preferable, and specifically, for example, a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group And a perfluorobutyl group, among which a trifluoromethyl group is preferred.

  As the alkoxy group having 1 to 20 carbon atoms, an alkoxy group having 1 to 8 carbon atoms is preferable, and specific examples include a methoxy group, an ethoxy group, an n-butoxy group, and a methoxyethoxy group. A methoxy group or an ethoxy group is preferred.

  As the aryl group having 6 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms is preferable, and specific examples include a phenyl group, an α-methylphenyl group, and a naphthyl group. preferable.

  As the aryloxy group having 6 to 20 carbon atoms, an aryloxy group having 6 to 12 carbon atoms is preferable, and specific examples include a phenyloxy group and a 2-naphthyloxy group. Is preferred.

Examples of the amino group include a primary amino group (—NH ₂ ); a secondary amino group such as a methylamino group; a dimethylamino group, a diethylamino group, a dibenzylamino group, a nitrogen-containing heterocyclic compound (eg, pyrrolidine) , Piperidine, piperazine, etc.); and tertiary amino groups such as groups having a nitrogen atom as a bond.

In the group represented by the above formula (7), examples of the monovalent organic group represented by R ⁹ in the above formula (7) include a linear or cyclic alkyl group having 1 to 20 carbon atoms. Can be
As the linear alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, and specific examples include, for example, a methyl group, an ethyl group, and an n-propyl group. preferable.
As the cyclic alkyl group, an alkyl group having 3 to 6 carbon atoms is preferable, and specific examples include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group. Among them, a cyclohexyl group is preferable.
The monovalent organic group represented by R ⁹ in the above formula (7) may be a combination of a plurality of the above-described linear alkyl groups and cyclic alkyl groups directly or via a single bond. Good.

In the present invention, R ² and R ^{3 in the} above formula (1) are used because the photo-alignment group easily interacts with the liquid crystal compound and the liquid crystal alignment of the formed photo-alignment film becomes better. , R ⁴ , R ⁵ and R ⁶ , it is preferable that at least R ⁴ represents the substituent described above, and furthermore, the rigidity of the obtained photo-alignable copolymer is improved, and More preferably, R ² , R ³ , R ⁵ and R ⁶ all represent a hydrogen atom, because the heat resistance of the film is further improved.

In the present invention, R ^{4 in the} above formula (1) is preferably an electron-donating substituent because the reaction efficiency is improved when the obtained photo-alignment film is irradiated with light.
Here, the electron-donating substituent (electron-donating group) refers to a substituent having a Hammett value (Hammett substituent constant σp) of 0 or less. For example, among the above-described substituents, an alkyl group, Examples thereof include a halogenated alkyl group and an alkoxy group. Among them, a cyclic alkyl group (for example, a cyclohexyl group) and an alkoxy group (for example, a methoxy group) ) Is preferable.

Specific examples of the repeating unit A represented by the formula (1) containing a photo-alignment group include the following repeating units A-1 to A-76. In the following formula, Me represents a methyl group, Et represents an ethyl group, and ⁱ Pr represents an isopropyl group.

Next, regarding the repeating unit B represented by the formula (2) containing a crosslinkable group, the crosslinkable group represented by X in the following formula (2) will be described.

In the present invention, the crosslinkable group is preferably a so-called self-crosslinkable group in which crosslinking progresses between functional groups without adding a crosslinking agent, and specifically, the following formulas (3) to (5) Is more preferably a crosslinkable group represented by any one of the following, and further more preferably a crosslinkable group represented by the following formula (3) or (4). In the following formulas (3) to (5), * represents a bonding position with L ² in the formula (2), R ⁸ represents any one of hydrogen atom, methyl group and ethyl group.

Specific examples of the repeating unit B represented by the formula (2) containing a photo-alignable group include the following repeating units B-1 to B-3.

The photo-alignable copolymer of the present invention has the above-described content X of the repeating unit A because the rigidity of the obtained photo-alignable copolymer is improved and the heat resistance of the produced photo-alignment film is improved. And the content Y of the above-described repeating unit B preferably satisfies the following formula (8), and the photo-alignment group easily interacts with the liquid crystal compound, and the photo-alignment film produced It is more preferable that the following formula (9) is satisfied from the reason that the liquid crystal alignment property becomes better.
0.4 ≦ X / (X + Y) ≦ 0.8 (8)
0.45 ≦ X / (X + Y) ≦ 0.65 (9)

As long as the effects of the present invention are not impaired, the photo-alignable copolymer of the present invention may have other repeating units in addition to the above-described repeating units A and B.
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 vinyl compounds.

  The method for synthesizing the photo-alignable copolymer of the present invention is not particularly limited. For example, a monomer forming the above-described repeating unit A, a monomer forming the above-described repeating unit B, and forming any other repeating unit The monomers can be synthesized by mixing the monomers to be polymerized and polymerizing in an organic solvent using a radical polymerization initiator.

The weight average molecular weight (Mw) of the photo-alignable copolymer of the present invention is from 10,000 to 10,000 because the rigidity of the obtained photo-alignable copolymer is improved and the heat resistance of the photo-alignment film to be produced is improved. 500,000 is preferable, and 30,000 to 200,000 is more preferable because the orientation becomes better.
Here, the weight average molecular weight and the number average molecular weight in the present invention are values measured by a gel permeation chromatography (GPC) method under the following conditions.
-Solvent (eluent): THF (tetrahydrofuran)
-Equipment name: TOSOH HLC-8320GPC
-Column: Connect and use three TOSOH TSKgel Super HZM-H (4.6 mm x 15 cm)-Column temperature: 40 ° C
-Sample concentration: 0.1% by mass
・ Flow rate: 1.0 ml / min
-Calibration curve: TOSOH standard polystyrene TSK standard calibration curve using 7 samples from Mw = 2800000 to 1050 (Mw / Mn = 1.03 to 1.06)

[Photo-alignment film]
The photo-alignment film of the present invention is a composition for a photo-alignment film containing the above-described photo-alignment copolymer of the present invention (hereinafter, also formally referred to as “the composition for a photo-alignment film of the present invention”). It is a photo-alignment film formed by using.
The thickness of the photo-alignment film is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably from 10 to 1,000 nm, more preferably from 10 to 700 nm.

  The content of the photo-alignable copolymer of the present invention in the composition for a photo-alignment film of the present invention is not particularly limited. It is preferably at least 1 part by mass, more preferably 0.5 to 10 parts by mass.

The composition for a photo-alignment film of the present invention preferably contains an organic solvent from the viewpoint of workability for producing the photo-alignment film.
Specific examples of the organic solvent include ketones (eg, acetone, 2-butanone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, etc.), ethers (eg, dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (Such as hexane), alicyclic hydrocarbons (such as cyclohexane), aromatic hydrocarbons (such as toluene, xylene and trimethylbenzene), and halogenated carbons (such as dichloromethane, dichloroethane and dichloroethane). Chlorobenzene, chlorotoluene, etc.), esters (eg, methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (eg, ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (eg, methyl cellosolve, ethyl) Rosolve, cellosolve acetates, sulfoxides (e.g., dimethylsulfoxide, etc.), amides (e.g., dimethylformamide, dimethylacetamide, etc.), and the like. These may be used alone, or two or more kinds may be used. You may use together.

  The composition for a photo-alignment film of the present invention may contain components other than those described above, and examples thereof include a crosslinking catalyst, an adhesion improver, a leveling agent, a surfactant, and a plasticizer.

(Production method of photo-alignment film)
The photo-alignment film of the present invention can be manufactured by a conventionally known manufacturing method except that the above-described photo-alignment film composition of the present invention is used. For example, the photo-alignment film composition of the present invention described above is supported. It can be produced by a production method having a coating step of applying to the body surface and a light irradiation step of irradiating polarized light or non-polarized light from an oblique direction to the coated film surface with respect to the coating film of the composition for a photoalignment film. it can.
The support will be described later in the optical laminate of the present invention.

<Coating process>
The application method in the application step is not particularly limited, and can be appropriately selected depending on the purpose. Examples thereof include spin coating, die coating, gravure coating, flexographic printing, and inkjet printing.

<Light irradiation step>
In the light irradiation step, the polarized light applied to the coating film of the composition for a photoalignment film is not particularly limited, and examples thereof include linearly polarized light, circularly polarized light, and elliptically polarized light. Among them, linearly polarized light is preferable.
The “oblique direction” for irradiating non-polarized light 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. Can be selected as appropriate, but it is preferable that θ is from 20 to 80 °.

The wavelength in the polarized or unpolarized light is not particularly limited as long as the coating of the composition for a photoalignment film can be provided with the ability to control the alignment of liquid crystal molecules, but, for example, ultraviolet light, near ultraviolet light, and visible light. And the like. Among them, near ultraviolet rays having a wavelength of 250 nm to 450 nm are particularly preferable.
Examples of the light source for irradiating polarized or non-polarized light include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. By using an interference filter, a color filter, or the like for ultraviolet light or visible light obtained from such a light source, the wavelength range to be irradiated can be limited. In addition, linearly polarized light can be obtained by using a polarizing filter or a polarizing prism for light from these light sources.

The integrated amount of polarized or non-polarized light is not particularly limited and is not particularly limited, as long as the coating of the composition for a photoalignment film can be provided with the ability to control the alignment of liquid crystal molecules. / Cm ² is preferable, and 5 to 100 mJ / cm ² is more preferable.
The illuminance of polarized light or non-polarized light is not particularly limited as long as the ability to control the alignment of liquid crystal molecules can be imparted to the coating film of the composition for a photoalignment film, but is preferably 0.1 to 300 mW / cm ^2. Preferably, it is 1 to 100 mW / cm ² .

[Optical laminate]
The optical laminate of the present invention is an optical laminate having the above-described photo-alignment film of the present invention and an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound.
Further, the optical laminate of the present invention preferably further has a support, and specifically, preferably has a support, a photo-alignment film, and an optically anisotropic layer in this order. .

(Optical anisotropic layer)
The optically anisotropic layer included in the optical laminate of the present invention is not particularly limited as long as it is an optically anisotropic layer containing a liquid crystal compound, and a conventionally known optically anisotropic layer may be appropriately employed and used. it can.
Such an optically anisotropic layer is a layer obtained by curing a composition containing a liquid crystal compound having a polymerizable group (hereinafter, also referred to as “composition for forming an optically anisotropic layer”). It is preferable that it has a single-layer structure or a structure in which a plurality of layers are laminated (laminated body).
Hereinafter, the liquid crystalline compound and the optional additive contained in the composition for forming an optically anisotropic layer will be described.

<Liquid crystal compound>
The liquid crystal compound contained in the composition for forming an optically anisotropic layer is a liquid crystal compound having a polymerizable group.
In general, liquid crystal compounds can be classified into rod-shaped types and disc-shaped types based on their shapes. Furthermore, there are low molecular and high molecular types, respectively. A polymer generally refers to a polymer having a degree of polymerization of 100 or more (polymer physics / phase transition dynamics, Masao Doi, page 2, Iwanami Shoten, 1992).
In the present invention, any liquid crystal compound can be used, but a rod-shaped liquid crystal compound or a discotic liquid crystal compound is preferably used, and a rod-shaped liquid crystal compound is more preferably used.

  In the present invention, a liquid crystal compound having a polymerizable group is used for fixing the above liquid crystal compound, but it is more preferable that the liquid crystal compound has two or more polymerizable groups in one molecule. When the liquid crystal compound is a mixture of two or more types, it is preferable that at least one type of the liquid crystal compound has two or more polymerizable groups in one molecule. After the liquid crystal compound is fixed by polymerization, it is no longer necessary to exhibit liquid crystal properties.

  The type of the polymerizable group is not particularly limited, and a functional group capable of performing an addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group and the like are preferable, and a (meth) acryloyl group is more preferable. In addition, the (meth) acryloyl group is a notation meaning a methacryloyl group or an acryloyl group.

  As the rod-like liquid crystal compound, for example, those described in claims 1 of Japanese Patent Application Laid-Open No. 11-513019 and paragraphs <0026> to <0098> of JP-A-2005-289980 can be preferably used. As the tick liquid crystalline compound, for example, those described in paragraphs <0020> to <0067> of JP-A-2007-108732 and paragraphs <0013> to <0108> of JP-A-2010-244038 are preferably used. But not limited to these.

<Additives>
The composition for forming an optically anisotropic layer may contain components other than the above-mentioned liquid crystalline compound.
For example, the composition for forming an optically anisotropic layer may contain a polymerization initiator. The polymerization initiator used is selected according to the type of the polymerization reaction, and includes, for example, a thermal polymerization initiator and a photopolymerization initiator. For example, 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 ketone, and the like. Can be
The amount of the polymerization initiator to be used is preferably from 0.01 to 20% by mass, more preferably from 0.5 to 5% by mass, based on the total solid content of the composition.

In addition, the composition for forming an optically anisotropic layer may contain a polymerizable monomer from the viewpoint of uniformity of the coating film and strength of the film.
Examples of the polymerizable monomer include radically polymerizable and cationically polymerizable compounds. Preferably, it is a polyfunctional radical polymerizable monomer, which is copolymerizable with the above-mentioned polymerizable group-containing liquid crystalline compound. For example, those described in paragraphs <0018> to <0020> in JP-A-2002-296423 are exemplified.
The content of the polymerizable monomer is preferably from 1 to 50% by mass, more preferably from 2 to 30% by mass, based on the total mass of the liquid crystal compound.

Further, the composition for forming an optically anisotropic layer may contain a surfactant from the viewpoint of uniformity of the coating film and strength of the film.
Examples of the surfactant include conventionally known compounds, and a fluorine compound is particularly preferable. Specifically, for example, compounds described in paragraphs <0028> to <0056> in JP-A-2001-330725 and compounds described in paragraphs <0069> to <0126> in JP-A-2005-062673 Is mentioned.

  Further, the composition for forming an optically anisotropic layer may contain an organic solvent. Examples of the organic solvent include the same ones as described in the composition for a photo-alignment film of the present invention described above.

Further, the composition for forming an optically anisotropic layer includes a vertical alignment agent such as a polarizer interface side vertical alignment agent, and a vertical alignment accelerator such as an air interface side vertical alignment agent, and a polarizer interface side horizontal alignment agent, and air Various alignment agents such as a horizontal alignment accelerator such as an interface side horizontal alignment agent may be included.
Further, in addition to the above components, the composition for forming an optically anisotropic layer may contain an adhesion improver, a plasticizer, a polymer, and the like.

The method for forming an optically anisotropic layer using the composition for forming an optically anisotropic layer having such a component is not particularly limited. For example, an optically anisotropic layer may be formed on the optical alignment film of the present invention described above. It can be formed by applying a composition for formation to form a coating film and subjecting the obtained coating film to a curing treatment (irradiation with ultraviolet light (light irradiation treatment) or heat treatment).
The application of the composition for forming an optically anisotropic layer can be performed by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method).

  In the present invention, the thickness of the optically anisotropic layer is not particularly limited, but is preferably from 0.1 to 10 μm, more preferably from 0.5 to 5 μm.

(Support)
As described above, the optical laminate of the present invention may have a support as a substrate for forming an optically anisotropic layer.
Examples of such a support include, for example, a polarizer and a polymer film, and a combination thereof, for example, a laminate of a polarizer and a polymer film, a laminate of a polymer film, a polarizer, and a polymer film. It may be a body or the like.
Further, the support may be a temporary support that can be peeled off after forming the optically anisotropic layer (hereinafter, may be simply referred to as “temporary support”). Specifically, a polymer film that functions as a temporary support may be peeled from the optical laminate to provide an optically anisotropic layer. For example, an optical laminate including an optically anisotropic layer and a temporary support is prepared, and the optically anisotropic layer side of the optical laminate is bonded to a support including a polarizer with an adhesive or an adhesive, By peeling off the temporary support contained in the optically anisotropic layer, a laminate of a support containing a polarizer and the optically anisotropic layer may be provided.

<Polarizer>
In the present invention, when the optical laminate of the present invention is used for an image display device, it is preferable to use at least a polarizer as a support.
The polarizer is not particularly limited as long as it has a function of converting light into specific linearly polarized light, and a conventionally known absorption polarizer and reflection polarizer can be used.
As the absorption polarizer, an iodine-based polarizer, a dye-based polarizer using a dichroic dye, a polyene-based polarizer, and the like are used. Iodine-based polarizers and dye-based polarizers include coating polarizers and stretched polarizers, both of which can be applied.Polarized light produced by adsorbing iodine or a dichroic dye on polyvinyl alcohol and stretching. Children are preferred.
Further, as a method of obtaining a polarizer by stretching and dyeing in a state of a laminated film having a polyvinyl alcohol layer formed on a substrate, Japanese Patent Nos. 5048120, 5143918, 4691205, and Japanese Patent No. 4751481 and Japanese Patent No. 4751486 can be cited, and known techniques relating to these polarizers can also be preferably used.
As the reflective polarizer, a polarizer in which thin films having different birefringence are stacked, a wire grid polarizer, a polarizer in which a cholesteric liquid crystal having a selective reflection region and a quarter-wave plate are used, and the like are used.
Among them, from the viewpoint of handleability, a polymer containing a polyvinyl alcohol resin (—CH ₂ —CHOH— as a repeating unit is intended. In particular, at least one selected from the group consisting of polyvinyl alcohol and an ethylene-vinyl alcohol copolymer is intended. (Preferably one).

In the embodiment in which the optical laminate of the present invention includes a peelable support, the polarizing plate can be manufactured, for example, as follows.
The support is peeled from the above-described optical laminate, and the layer including the optically anisotropic layer is laminated on the support including the polarizer. Alternatively, the above-described optical laminate is laminated on a support including a polarizer, and thereafter, the removable support included in the optical laminate is separated. At the time of lamination, both layers may be adhered with an adhesive or the like. There is no particular limitation on the adhesive, but as described in JP-A-2004-245925, a curable adhesive of an epoxy compound containing no aromatic ring in the molecule, and 360 to 360 described in JP-A-2008-174667. An active energy ray-curable adhesive containing a photopolymerization initiator having a molar extinction coefficient of 400 or more at a wavelength of 450 nm and an ultraviolet curable compound as essential components, and a (meth) acrylic compound described in JP-A-2008-174667. (A) a (meth) acrylic compound having two or more (meth) acryloyl groups in a molecule in a total amount of 100 parts by mass, and (b) a hydroxyl group in a molecule, and having only one polymerizable double bond. (Meth) acrylic compound and (c) phenol ethylene oxide modified acrylate or nonylphenol ethylene oxide modified acrylic Such as an active energy ray-curable adhesive containing a chromatography bets and the like.

  The thickness of the polarizer is not particularly limited, but is preferably 1 to 60 μm, more preferably 1 to 30 μm, and further preferably 2 to 20 μm.

<Polymer film>
The polymer film is not particularly limited, and a commonly used polymer film (for example, a polarizer protective film or the like) can be used.
Specific examples of the polymer constituting the polymer film include, for example, a cellulose-based polymer; an acrylic polymer having an acrylate polymer such as a polymethyl methacrylate and a lactone ring-containing polymer; a thermoplastic norbornene-based polymer; Polymers: 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 copolymer; Vinyl chloride Amide polymers such as nylon and aromatic polyamide; imide polymers; sulfone polymers; polyethersulfone polymers; polyetheretherketone Polymers; polyphenylene sulfide polymers; vinylidene chloride polymer; vinyl alcohol-based polymer, vinyl butyral-based polymers; arylate polymers; polyoxymethylene polymers, epoxy-based polymers; or polymers obtained by mixing these polymers.

Among these, a cellulosic polymer represented by triacetyl cellulose (hereinafter, also referred to as “cellulose acylate”) can be preferably used.
It is also preferable to use an acrylic polymer from the viewpoint of processability and optical performance.
Examples of the acrylic polymer include polymethyl methacrylate and lactone ring-containing polymers described in paragraphs <0017> to <0107> of JP-A-2009-98605.

  The thickness of the polymer film used for the polarizer protective film or the like is not particularly limited, but is preferably 40 μm or less because the thickness of the optical laminate can be reduced. The lower limit is not particularly limited, but is usually 5 μm or more.

In the embodiment in which the polymer film is used as the support that does not peel off from the optical laminate, the glass transition temperature of the support is preferably 100 ° C. or lower because the advantage of using the composition for a photo-alignment film of the present invention becomes high. .
Here, in this specification, 20 mg of a sample of the support was put into a measuring pan by a differential scanning calorimeter (X-DSC7000 (manufactured by IT Measurement Control Co., Ltd.)), and the sample was subjected to a speed measurement in a nitrogen trap. After the temperature was raised from 30 ° C. to 120 ° C. at 10 ° C./min and held for 15 minutes, it was cooled to −30 ° C. at −20 ° C./min. Thereafter, the temperature is raised again from 30 ° C. to 250 ° C., and a temperature at which the baseline starts to change from a low temperature side is defined as a glass transition temperature Tg.

  In the present invention, the thickness of the support is not particularly limited, but is preferably from 1 to 100 μm, more preferably from 5 to 50 μm, and still more preferably from 5 to 20 μm. In the case where the support has both a polarizer and a polymer film, the thickness of the support refers to the total thickness of these.

  In an embodiment in which a polymer film is used as a support that can be separated from the optical laminate, a cellulose-based polymer or a polyester-based polymer can be preferably used. The thickness of the polymer film is not particularly limited, but is preferably 5 μm to 100 μm, and more preferably 20 μm to 90 μm, for reasons such as handling during production.

[Image display device]
The image display device of the present invention is an image display device having 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 includes, for example, a liquid crystal cell, an organic electroluminescence (hereinafter abbreviated as “EL”) display panel, a plasma display panel, and the like.
Among these, a liquid crystal cell and an organic EL display panel are preferable, and a liquid crystal cell is more preferable. 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, an organic EL display device using an organic EL display panel as a display element, and a liquid crystal display device is preferred. More preferred.

(Liquid crystal display)
A liquid crystal display device as an example of the image display device of the present invention is a liquid crystal display device including the above-described optical laminate of the present invention and a liquid crystal cell.
In the present invention, among the polarizing plates provided on both sides of the liquid crystal cell, it is preferable to use the optical laminate of the present invention as the front polarizing plate.
Hereinafter, the liquid crystal cell constituting the liquid crystal display device will be described in detail.

<Liquid crystal cell>
The liquid crystal cell used in the liquid crystal display device is preferably a VA (Virtually Alignment) mode, an OCB (Optically Compensated Bend) mode, an IPS (In-Plane-Switching) mode, or a TN (Twisted Nematic). However, the present invention is not limited to this.
In a TN mode liquid crystal cell, rod-shaped liquid crystal molecules (rod-shaped liquid crystal compound) are substantially horizontally aligned when no voltage is applied, and further twist-aligned at 60 to 120 °. TN mode liquid crystal cells are most frequently used as color TFT liquid crystal display devices, and are described in many documents.
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied. The VA mode liquid crystal cell includes (1) a VA mode liquid crystal cell in a narrow sense in which rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when voltage is applied. 176625), (2) a liquid crystal cell (SID97, Digest of tech. Papers (Multi-domain Vertical Alignment) mode) in which the VA mode is multi-domain for enlargement of the viewing angle (in the MVA (Multi-domain Vertical Alignment) mode). 28) (1997) 845), and (3) a mode in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied, and twisted multi-domain alignment is performed when a voltage is applied (n-ASM mode (Axially symmetric aligned microcell)). Liquid Crystal Cell (Preprints 58 59 (1998)) and (4) SURVIVAL (Super Ranged Viewing by Vertical Alignment) mode liquid crystal cell (published at LCD (liquid crystal display) International 98). Further, any of a PVA (Patterned Vertical Alignment) type, a photo alignment type (Optical Alignment), and a PSA (Polymer-Sustained Alignment) may be used. Details of these modes are described in JP-A-2006-215326 and JP-T-2008-538819.
In the IPS mode liquid crystal cell, rod-like liquid crystal molecules are oriented substantially parallel to the substrate, and the liquid crystal molecules respond planarly when an electric field parallel to the substrate surface is applied. In the IPS mode, black is displayed when no electric field is applied, and the absorption axes of the pair of upper and lower polarizing plates are orthogonal to each other. Japanese Patent Application Laid-Open Nos. H10-54982, H11-202323, and H9-292522 disclose a method of using an optical compensation sheet to reduce the leakage light at the time of black display in an oblique direction and improve the viewing angle. And JP-A-11-133408, JP-A-11-305217, and JP-A-10-307291.

  Hereinafter, the present invention will be described in more detail based on examples. Materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed 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 following examples.

[Synthesis of Monomer mA-8]

<Synthesis of Intermediate 1>
In a 500 mL three-necked flask, 10 g of glycidyl methacrylate, 16.30 g of 4-methoxycinnamic acid, 2.64 g of tetraphenylphosphonium chloride, 15.5 mg of butylhydroxytoluene (BHT), and 100 mL of dimethylacetamide (DMAc) were mixed. The mixture was stirred at a temperature of 80 ° C. for 10 hours. After allowing to cool to room temperature (23 ° C.), 200 mL of ethyl acetate and 200 mL of water were added, and the organic phase was separated and washed with 200 L of 1N hydrochloric acid, 200 L of saturated aqueous sodium bicarbonate, and 200 L of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 12.39 g of intermediate 1 (yield: 50%).
<Synthesis of Monomer mA-8>
In a 500 mL three-necked flask, 12 g of Intermediate 1, 7.58 g of triethylamine, 1.37 g of dimethylaminopyridine, and 120 mL of dimethylacetamide were mixed, and cooled to an internal temperature of 5 ° C. To this, 7.37 g of 4-methoxycinnamic acid chloride was added in portions so that the internal temperature would be 10 ° C or lower. The mixture was further stirred at an internal temperature of 40 to 45 ° C for 3 hours. After cooling the reaction solution to room temperature, 240 mL of ethyl acetate and 240 mL of water were added, and the organic phase was separated and washed with 240 mL of 1N hydrochloric acid, 240 mL of saturated aqueous sodium hydrogen carbonate, and 240 mL of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 16.2 g (yield 90%) of the monomer mA-8 which forms the above-mentioned repeating unit A-8.

[Synthesis of Monomer mA-1, etc.]
In the synthesis of monomer mA-8, except that cinnamic acid chloride was changed to the corresponding cinnamic acid chloride derivative, in the same manner as monomer mA-8, monomers mA-1, mA-2, mA-5, mA-6, mA-10 and mA-27 were synthesized respectively.
The following monomers mA-1 and the like respectively correspond to the monomers forming the above-mentioned repeating unit A-1 and the like.

[Synthesis of Monomer mA-32 etc.]
In the synthesis of monomer mA-8, 3,4-epoxycyclohexylmethyl methacrylate (Cyclomer M100, manufactured by Daicel) was used instead of glycidyl methacrylate, and cinnamic acid chloride was changed to the corresponding cinnamic acid chloride derivative. Synthesized monomers mA-32, mA-33 and mA-34 shown below in the same manner as for monomer mA-8.
The following monomers mA-32 and the like correspond to the monomers forming the above-described repeating unit A-32 and the like, respectively.

[Synthesis of Monomer mA-44]

<Synthesis of Intermediate 2>
25 g of phloroglucinol, 40.12 g of triethylamine, and 250 mL of tetrahydrofuran (THF) were mixed in a 1 L three-necked flask, and cooled to an internal temperature of 5 ° C. To this, 77.96 g of 4-methoxycinnamic acid chloride was added in portions so that the internal temperature would be 10 ° C or lower. The mixture was further stirred at an internal temperature of 40 to 45 ° C for 3 hours. After the reaction solution was cooled to room temperature, 250 mL of ethyl acetate and 250 mL of water were added, and the organic phase was separated and washed with 240 mL of 1N hydrochloric acid, 240 mL of saturated aqueous sodium hydrogen carbonate, and 240 mL of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 55.20 g of intermediate 2 (yield: 62%).
<Monomer mA-44>
In a 1 L three-necked flask, 20 g of Intermediate 2, 6.80 g of triethylamine, 1.09 g of dimethylaminopyridine (DMAP), 15.0 mg of butylhydroxytoluene (BHT), and 250 mL of dimethylacetamide (DMAc) were mixed. Cooled to a temperature of 5 ° C. Thereto, 7.02 g of methacrylic acid chloride was dividedly added so that the internal temperature would be 10 ° C. or lower. The mixture was further stirred at an internal temperature of 40 to 45 ° C for 3 hours. After cooling the reaction solution to room temperature, 300 mL of ethyl acetate and 300 mL of water were added, and the organic phase was separated and washed with 300 mL of 1N hydrochloric acid, 300 mL of saturated aqueous sodium hydrogen carbonate, and 300 mL of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 20.0 g (yield: 87%) of a monomer mA-44 forming the above-mentioned repeating unit A-44.

[Synthesis of Monomer mA-50]
In the synthesis of monomer mA-44, except that tetrahydroxybenzene was used instead of phloroglucinol, the following monomer mA-50 forming repeating unit A-50 described above was synthesized in the same manner as monomer mA-44. did.

[Synthesis of Monomer mA-71]

<Synthesis of Intermediate 3>
120 g of 3-cyclohexene-1-methanol, 0.72 g of methyltrioxorhenium, 1.44 g of pyrazole, and 600 mL of dichloromethane were mixed in a 3 L three-necked flask, and cooled to an internal temperature of 5 ° C. There, 134.40 g of 35% aqueous hydrogen peroxide was added dropwise so that the internal temperature would be 10 ° C. or lower. Further, the mixture was stirred at an internal temperature of 5 ° C. or lower for 4 hours. After adding a saturated sodium thiosulfate aqueous solution to the reaction solution so that the internal temperature becomes 10 ° C. or lower, 500 mL of water was added, and the organic phase was further washed twice with 500 mL of water and 500 mL of a saturated aqueous sodium chloride solution. . The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 76.05 g of intermediate 3 (yield: 55.5%).
<Synthesis of Intermediate 4>
In a 2 L three-necked flask, 74 g of Intermediate 3, 144.0 g of triethylamine, and 760 mL of dichloromethane were mixed, and cooled to an internal temperature of 5 ° C. Thereto, 64.4 g of acrylic acid chloride was dividedly added so that the internal temperature was 10 ° C. or lower, and the mixture was added dropwise over 3 hours. Thereafter, the mixture was stirred at 10 ° C or less for 2 hours, 50 mL of water was added so that the internal temperature would be 10 ° C or less, and the organic phase was separated and washed with 300 mL of saturated aqueous sodium bicarbonate and 300 mL of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 85.93 g of intermediate 4 (yield: 82%).
<Synthesis of Monomer mA-71>
In the synthesis of monomer mA-32, monomer mA-71 forming repeat unit A-71 described above was obtained in the same manner as monomer mA-32 described above, except that intermediate 4 was used.

[Synthesis of Monomer mA-74]

<Synthesis of 4-hydroxystyrene>
A 1 L three-necked flask was mixed with 100 g of 4-vinylphenyl acetate and 400 mL of ethyl acetate, and cooled to an internal temperature of 5 ° C. Sodium methoxide (40.0 g) was added in portions so that the internal temperature was 10 ° C. or lower, and then the mixture was stirred at room temperature for 3 hours. 400 mL of water was added to the reaction solution, and the organic phase was separated and washed in order of 300 mL of 1N hydrochloric acid, 300 mL of water, and 300 mL of saturated saline. The organic phase was dried over magnesium sulfate, and the solvent was distilled off to obtain 50.0 g (yield 67%) of 4-hydroxystyrene.
<Synthesis of Intermediate 6>
In a 1 L three-necked flask, 20 g of 4-hydroxystyrene, 27.74 g of Intermediate 3, 56.76 g of triphenylphosphine, and 400 mL of tetrahydrofuran were mixed, and cooled to an internal temperature of 5 ° C. 37.69 g of diethyl azodicarboxylate was added dropwise at a temperature of 10 ° C. or lower, and the mixture was heated to room temperature and stirred for 1 hour. The reaction solution was concentrated, and the concentrate was purified by column chromatography to obtain 25.32 g of intermediate 6 (66% yield).
<Synthesis of Monomer mA-74>
In the synthesis of monomer mA-32, except that intermediate 6 was used, monomer mA-74 forming repeating unit A-74 described above was obtained in the same manner.

[Monomer mB-1]
Commercially available glycidyl methacrylate (Tokyo Kasei Reagent) was used as the following monomer mB-1 for forming the above repeating unit B-1.

[Monomer mB-2]
Cyclomer M100 (manufactured by Daicel Corporation) was used as the following monomer mB-2 which forms the above-mentioned repeating unit B-2.

[Monomer mB-3]
OXE-30 (manufactured by Osaka Organic Chemical Industry) was used as the following monomer mB-3 forming the above-mentioned repeating unit B-3.

[Monomer mB-4]
As the following monomer mB-4 forming the above-mentioned repeating unit B-4, a synthetic product obtained by a condensation reaction between commercially available 2-hydroxyethyl methacrylate and commercially available methacrylic chloride was used.

[Synthesis of Monomer mC-1]
The following monomer mC-1 was synthesized by the method described in JP-T-2003-505561.

[Synthesis of Monomer mC-2]

<Synthesis of 4-acetoxybenzaldehyde>
A 1 L three-necked flask was mixed with 18.9 g of 4-hydroxybenzaldehyde, 36.7 g of pyridine, 1.89 g of dimethylaminopyridine, and 500 mL of dichloromethane, and cooled to an internal temperature of 5 ° C. 25.0 g of acetic chloride was added dropwise at a temperature of 10 ° C. or lower, and the mixture was heated to room temperature and stirred for 1 hour. After concentrating the reaction solution, 300 mL of ethyl acetate and 300 mL of water were added, and the organic phase was separated and washed with 300 mL of a saturated ammonium chloride aqueous solution, 300 mL of water, and 300 mL of saturated saline in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 25.6 g (yield 71%) of 4-acetoxybenzaldehyde.
<Synthesis of Intermediate 7>
In a 500 mL three-necked flask, 20.0 g of 4-acetoxybenzaldehyde, 22.4 g of malonic acid, 1.83 g of piperidine, and 250 mL of pyridine were mixed, heated to an internal temperature of 85 ° C., and heated and stirred for 5 hours. 300 mL of 5N hydrochloric acid was added to the reaction solution, and the precipitate was separated by filtration to obtain 21.1 g of intermediate 7 (89% yield).
<Synthesis of Intermediate 8>
In a 500 mL three-necked flask, 20.0 g of Intermediate 7, 100 mL of dichloromethane, and 1 drop of dimethylformamide were mixed, and cooled to an internal temperature of 5 ° C. Subsequently, 20.0 g of oxalyl chloride was added while maintaining the internal temperature at 10 ° C. or lower. After completion of the dropwise addition, the water bath was removed, and the temperature was raised to room temperature, followed by stirring at room temperature for 3 hours. Thereafter, the solvent was distilled off to obtain 21.78 g of intermediate 8 (yield: 99%).
<Synthesis of Monomer mC-2>
10 g of 2-hydroxyethyl methacrylate, 7.58 g of triethylamine, 1.37 g of dimethylaminopyridine, and 120 mL of dimethylacetamide were mixed in a 500 mL three-necked flask, and cooled to an internal temperature of 5 ° C. To this, 20.7 g of Intermediate 8 was added in portions so that the internal temperature would be 10 ° C. or lower. The mixture was further stirred at an internal temperature of 40 to 45 ° C for 3 hours. After the reaction solution was cooled to room temperature, 240 mL of ethyl acetate and 240 mL of water were added, and the organic phase was separated and washed with 240 mL of 1N hydrochloric acid, 240 mL of saturated aqueous sodium hydrogen carbonate, and 240 mL of water in this order. The organic phase was dried over magnesium sulfate and the solvent was distilled off. The concentrate was purified by column chromatography to obtain 20.2 g (yield: 83%) of monomer mC-2.

Here, the above-mentioned monomers mC-1 and mC-2 correspond to monomers forming the following repeating units C-1 and C-2, respectively.

[Example 1]
A flask equipped with a condenser, a thermometer, and a stirrer was charged with 5 parts by mass of 2-butanone as a solvent, and refluxed by heating in a water bath while flowing nitrogen at 5 mL / min into the flask. Here, 6 parts by mass of monomer mA-1, 4 parts by mass of monomer mB-2, 1 part by mass of 2,2′-azobis (isobutyronitrile) as a polymerization initiator, and 5 parts by mass of 2-butanone as a solvent The resulting solution was added dropwise over 3 hours, and the mixture was further stirred for 3 hours while maintaining the reflux state. After the completion of the reaction, the mixture was allowed to cool to room temperature, and diluted with 30 parts by mass of 2-butanone to obtain a polymer solution of about 20% by mass. The obtained polymer solution was poured into a large excess of methanol to precipitate the polymer, and the collected precipitate was separated by filtration, washed with a large amount of methanol, and then blow-dried at 50 ° C. for 12 hours, whereby Polymer P-1 having a photo-alignable group was obtained.

[Examples 2 to 20 and Comparative Examples 1 to 3]
Example 1 was repeated except that the above-mentioned monomers were used as the monomers forming the repeating units shown in Table 1 below, and the amounts of the monomers were changed so as to satisfy “X / (X + Y)” shown in Table 1 below. Was synthesized in the same manner as the polymer P-1 synthesized in the above.

(Preparation of composition for photo-alignment film)
1 part by mass of the polymer P-1 synthesized in Example 1 and 0.05 part by mass of a thermal acid generator represented by the following structural formula were added to 100 parts by mass of tetrahydrofuran, and the composition for a photo-alignment film was added. Was prepared.
In the same manner, for each of the polymers synthesized in Examples 2 to 20 and Comparative Examples 1 to 3, a composition for a photo-alignment film was prepared by adding 1 part by mass to 100 parts by mass of tetrahydrofuran.

(Preparation of polarizer)
According to Example 1 of JP-A-2001-141926, a polarizer having a film thickness of 8 μm was produced by adsorbing iodine on a stretched polyvinyl alcohol film.

(Preparation of optical laminate)
The composition for each optical alignment film prepared above was applied to one surface of the produced polarizer by spin coating.
After coating, the solvent was removed by drying on a hot plate at 80 ° C. for 5 minutes to form a photoisomerizable composition layer having a thickness of 0.2 μm.
A photo-alignment film was formed by irradiating the obtained photoisomerizable composition layer with polarized ultraviolet rays (irradiation amount shown in Table 2 below, using an ultra-high pressure mercury lamp).
Next, a nematic liquid crystal compound (ZLI-4792, manufactured by Merck) was applied on the photo-alignment film by a spin coating method to form a composition layer.
After the formed composition layer was once heated to 90 ° C. on a hot plate, it was cooled to 60 ° C. to stabilize the orientation.
Thereafter, the orientation was fixed by UV irradiation (500 mJ / cm ² , using an ultra-high pressure mercury lamp) under a nitrogen atmosphere (oxygen concentration 100 ppm) at a temperature of 60 ° C. to form an optically anisotropic layer having a thickness of 2.0 μm. The optical laminated body was produced.

(Liquid crystal orientation)
The prepared optical laminate was observed using a polarizing microscope while being shifted from the extinction position twice. As a result, evaluation was made based on the following criteria. The results are shown in Table 2 below.
AA: The liquid crystal director is uniformly aligned and oriented, and the display performance is excellent. A: There is no disturbance of the liquid crystal director and the surface condition is stable. B: The disturbance of the liquid crystal director is negligible and the surface condition is stable. C: Disturbance of liquid crystal director is partial, and surface condition is stable. D: Liquid crystal director is significantly disturbed, surface condition is not stable, and display performance is extremely poor. The term “surface state” means a state where there is no defect such as unevenness or poor orientation when an optical laminate is placed between two polarizing plates arranged in a crossed Nicols state and observed.
In this specification, a liquid crystal director is intended to mean a vector in a direction (major axis) in which the major axis of liquid crystal molecules is oriented.

〔Heat-resistant〕
Before applying the nematic liquid crystal compound to the prepared photo-alignment film, after aging at 40 ° C. and 60% relative humidity for 2 hours, an optical laminate was produced in the same manner as the above-mentioned optical laminate, and the above-described optical laminate was produced. The orientation was observed and evaluated according to the following criteria. The results are shown in Table 2 below.
A: There is no disturbance of the liquid crystal director and the surface condition is stable. B: The disturbance of the liquid crystal director is very slight and the surface condition is stable. C: The disturbance of the liquid crystal director is partial and the surface condition is small. Poor D: The liquid crystal director was greatly disturbed, the surface state was not stable, and the display performance was very poor.

From the results shown in Tables 1 and 2, even if the polymer has a repeating unit A containing two photo-alignable groups, the photo-alignment film using a polymer having no repeating unit containing a cross-linkable group, It was found that both the orientation and the heat resistance were inferior (Comparative Example 1).
In addition, the photo-alignment film using a copolymer having a repeating unit containing a photo-alignment group that does not correspond to the above formula (1) and a repeating unit B containing a cross-linkable group has either a liquid crystal alignment property or a heat resistance. (Comparative Example 2).
Similarly, a copolymer having a repeating unit containing a photo-alignment group not corresponding to the above formula (1) and a repeating unit B containing a crosslinkable group, wherein the content of the repeating unit B is larger than that in Comparative Example 2. As in Comparative Example 2, when the irradiation amount at the time of forming the photo-alignment film was 15 mJ / cm ² , both the liquid crystal alignment property and the heat resistance were poor. / Cm ² , it was found that the liquid crystal alignment was improved (Comparative Example 3).

On the other hand, a photo-alignment film using a copolymer having a repeating unit A represented by the formula (1) containing a photo-alignable group and a repeating unit B represented by the formula (2) containing a cross-linkable group is: In each case, it was found that the liquid crystal alignment and the heat resistance were good (Examples 1 to 20).
In particular, from the results of Examples 2 to 4, it was found that when R ⁴ in the above formula (1) was an electron-donating substituent, the liquid crystal alignment was improved.
Further, from the results of Examples 5, 14, and 16, it was found that when A in the above formula (1) was a linking group containing an alicyclic hydrocarbon group, the liquid crystal alignment was more favorable. .
Also, from the results of Examples 9 to 11, when the content X of the repeating unit A and the content Y of the repeating unit B are in the range of 0.45 to 0.65, the liquid crystal alignment is more favorable. It turned out to be.
Further, from the results of Example 11, a copolymer having a repeating unit A represented by the formula (1) containing a photo-alignable group and a repeating unit B represented by the formula (2) containing a crosslinkable group is shown. It was found that the photo-alignment film using No. 3 can exhibit good liquid crystal alignment even when the irradiation amount during the formation of the photo-alignment film is 10 mJ / cm ² or less.

Claims (15)

A photo-alignable copolymer having a repeating unit A represented by the formula (1) containing a photo-alignable group and a repeating unit B represented by the formula (2) containing a cross-linkable group.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents a single bond or a divalent linking group, A represents an m-valent linking group, and R ² and R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent. Among R ² , R ³ , R ⁴ , R ⁵ and R ⁶ , two adjacent groups may be bonded to each other to form a ring. m represents an integer of 3 or more, and n represents an integer of m-1. A plurality of R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different, respectively.
In the formula (2), R ⁷ represents a hydrogen atom or a methyl group, L ² represents a divalent linking group, and X represents a crosslinkable group. L ¹ in the above formula (1) and L ² in the above formula (2) each independently represent a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms or a C ⁶ to C 12 alkylene group. The photo-alignable copolymer according to claim 1, which is a divalent linking group obtained by combining at least two or more groups selected from the group consisting of an arylene group, an ether group, a carbonyl group, and an imino group.   3. The photo-alignable copolymer according to claim 1, wherein A in the formula (1) is a trivalent to hexavalent linking group. 4.   A in the formula (1) is an m-valent hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, and a part of carbon atoms constituting the hydrocarbon group is a hetero atom. The photo-alignable copolymer according to claim 1 or 2, which is a hydrocarbon group optionally substituted with:   The photo-alignment copolymer according to any one of claims 1 to 4, wherein A in the formula (1) is a linking group containing an alicyclic hydrocarbon group. The photo-alignment copolymer according to any one of claims 1 to 5, wherein X in the formula (2) is a crosslinkable group represented by any of the following formulas (3) to (5). Coalescing.

In the formula (3) to (5), * represents a bonding position with L ² in the formula (2), R ⁸ represents any one of hydrogen atom, methyl group and ethyl group.   The photo-alignable copolymer according to claim 6, wherein X in the formula (2) is a crosslinkable group represented by the formula (3) or (4). In the formula (1), R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom, a halogen atom, a straight-chain, branched or cyclic group having 1 to 20 carbon atoms. An alkyl group, 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, The photo-alignable copolymer according to any one of claims 1 to 7, which is a substituent selected from the group consisting of an amino group and a group represented by the following formula (7).

In the formula (7), * represents a bonding position to the benzene ring in the formula (1), and R ⁹ represents a monovalent organic group. 9. The photo-alignment element according to claim 1, wherein at least R ⁴ of R ² , R ³ , R ⁴ , R ^5, and R ^{6 in} the formula (1) represents a substituent. Polymer. The photo-alignable copolymer according to any one of claims 1 to 9, wherein R ⁴ in the formula (1) is an electron-donating substituent. The photoalignable copolymer according to any one of claims 1 to 10, wherein the content X of the repeating unit A and the content Y of the repeating unit B satisfy the following formula (8).
0.4 ≦ X / (X + Y) ≦ 0.8 (8) The photo-oriented copolymer according to claim 11, wherein the content X of the repeating unit A and the content Y of the repeating unit B satisfy the following formula (9).
0.45 ≦ X / (X + Y) ≦ 0.65 (9)   A photo-alignment film formed using the photo-alignment film composition containing the photo-alignment copolymer according to claim 1.   An optical laminate comprising: the optical alignment film according to claim 13; and an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystalline compound.   An image display device comprising the optical laminate according to claim 14.