WO2014077248A1 - Photoreactive composition, and photoalignment film and optical anisotropic film using same - Google Patents

Abstract

Provided is a photoreactive composition suited to the production of an optical anisotropic film having controlled molecular orientation for a phase difference film, polarization diffraction element, or the like. A photoreactive composition containing a copolymer having repeating units derived from a monomer represented by formula (1) and repeating units derived from a monomer represented by formula (2).

Description

Photoreactive composition, photo-alignment film using the same, and optically anisotropic film

The present invention relates to a photoreactive composition suitable for production of an optical element having controlled molecular orientation such as a retardation film or a liquid crystal alignment film, and an optical anisotropic film using the same.

So far, in Patent Document 1 and Patent Document 2, in the side chain type liquid crystal polymer that induces birefringence by light irradiation or light irradiation and heating and cooling, it is produced by a process including an operation of light irradiation or light irradiation and heat treatment. A retardation film and a manufacturing method thereof are proposed, and Patent Document 3 proposes a liquid crystal alignment film imparted with a liquid crystal alignment ability by light irradiation and a manufacturing method thereof.

In these materials proposed in Patent Documents 1 to 3, anisotropy can be imparted by an axially selective photocrosslinking reaction of polymer side chains when irradiated with linearly polarized ultraviolet light after being applied to a substrate and formed into a film. Furthermore, when such a film is heated, since the material itself has liquid crystallinity, the unreacted side chain is aligned along the side chain that has been photocrosslinked selectively, or perpendicular to the direction of the photocrosslinked side chain. The entire film can be molecularly oriented because it is oriented in the direction. Such a film can be used as a retardation film because it exhibits birefringence due to molecular orientation, and when liquid crystal molecules are brought into contact with the film surface, it exhibits the ability to align liquid crystal molecules. It also functions as a membrane.

Thus, these materials can be used in various applications due to the property of molecular orientation by light irradiation and heating. However, the materials proposed in these methods cannot be said to have sufficient photoreactivity, and a longer irradiation time is required. Furthermore, the temperature in the heat treatment after the light irradiation is not preferable because a considerable time is required at a high temperature exceeding 150 ° C. Further, as disclosed in Patent Document 1, a material capable of improving photoreactivity and inducing molecular orientation by irradiation with linearly polarized ultraviolet rays for a short time has been proposed, but the temperature in the heat treatment after light irradiation is 150. A considerable time is required at a high temperature exceeding 0 ° C., which is not preferable.

When the heat treatment after the light irradiation requires a high temperature for a long time, it is generally difficult to apply to a film having a plastic material having a low heat resistance as a base material. Furthermore, when these optical material films are obtained, a film is usually formed from a solution in which the material is dissolved in an organic solvent. However, in the materials disclosed in the above-mentioned prior art, in general, due to solubility problems, The use of the low-boiling solvent used has been made difficult.

Japanese Unexamined Patent Publication No. 2002-202409 Japanese Unexamined Patent Publication No. 2003-307618 Japanese Unexamined Patent Publication No. 2002-90750 Japanese Unexamined Patent Publication No. 2007-304215

In the present invention, since a heat treatment temperature necessary for developing a retardation can be lowered, a plastic material having low heat resistance can be used as a base material, and a solvent necessary for forming a retardation layer. An object of the present invention is to provide a photoreactive composition that can also use a low-boiling solvent, and a photoalignment film having a retardation obtained therefrom.

The present inventor conducted research to achieve the above-mentioned problems, and found that a benzoic acid ester compound having a specific structure in a polymer having a repeating unit derived from a monomer composed of a cinnamic acid compound having a specific structure. It has been found that the above object can be achieved by using a photoreactive composition containing a polymer into which a repeating unit derived from a monomer is introduced, and the present invention has been achieved.

Thus, the present invention has the features described below.
1. A light comprising a copolymer having a repeating unit derived from a monomer represented by the following formula (1) and a repeating unit derived from a monomer represented by the following formula (2): Reactive composition.

(X ₁ and X ₂ are each independently —O—, —O—CO—, —CO—O—, —NH—CO—, or —CO—NH—.
X ₃ is —O—CO— or —CO—O—. Y is a group selected from the group consisting of a benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, benzophenone, and phenylbenzoate, and each ring is an alkyl group, an alkoxy group, a halogen atom, a nitro group, or It may be substituted with a cyano group.
R ₁ and R ₂ are each independently a hydrogen atom or a methyl group.
p1 and p2 are each independently an integer of 2 to 12.
W is a group selected from the group consisting of a benzene ring, a naphthalene ring, and a biphenyl ring, and each ring may be substituted with an alkyl group, an alkoxy group, a halogen atom, a nitro group, or a cyano group.
Z ₁ to Z ₄ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a nitro group, or a cyano group. )

2. The molar ratio of (repeat unit derived from the monomer represented by the above formula (1)) / (repeat unit derived from the monomer represented by the above formula (2)) was 10/90 to 80/20. 2. The photoreactive composition according to 1 above.
3. The monomer represented by the above formula (1) is a cinnamic acid compound represented by the following formula (3), and the monomer represented by the above formula (2) is benzoic acid represented by the following formula (4). 3. The photoreactive composition according to 1 or 2 above, which is an ester compound.

(R ₁ and p ₁ are respectively synonymous with those defined in the above formula (1).
X ₄ is a single bond, —O—CO—, or —CO—O—.
m is 0 or 1, and when m is 0, X ₄ is a single bond. )

(R ₂ , p 2 _, X _3, and Z ₁ to Z ₄ are respectively synonymous with those defined in the above formula (2).
R ₃ is a hydrogen atom, an alkyl group, or an alkoxy group.
m ₁ is 1 or 2. )
4). 4. The photoreactive composition according to any one of 1 to 3 above, wherein the copolymer has a number average molecular weight of 1,000 to 100,000.
5. 5. The photoreactive composition according to any one of the above 1 to 4, further comprising an organic solvent.
6). 6. The photoreactive composition according to 5 above, wherein the organic solvent is a low boiling point solvent having a boiling point of 60 to 170 ° C.
7). 7. The photoreactive composition according to 5 or 6 above, wherein the content of the organic solvent is 60 to 99.5% by mass with respect to the total amount of the photoreactive composition.
8). 8. An optically anisotropic film obtained by irradiating a film of the photoreactive composition according to any one of 1 to 7 above with light containing a linearly polarized component, followed by heat treatment to impart liquid crystal alignment ability.
9. 9. The optically anisotropic film as described in 8 above, which is heat-treated at a temperature of 70 to 120 ° C.
10. 10. The optically anisotropic film as described in 8 or 9 above, having a thickness of 20 to 5000 nm.

According to the photoreactive composition of the present invention, the temperature in the heat treatment performed subsequent to the light irradiation treatment necessary for expressing the phase difference can be controlled, and this temperature can be greatly reduced. As a result, the plastic material having low heat resistance However, it can be used as a base material, and a solvent having a low boiling point can be used as a solvent necessary for forming the retardation layer.
As a result, by using such a photoreactive composition, a retardation film having excellent characteristics formed on a plastic film having low heat resistance, which has been difficult in the past, and orientation of molecules such as a polarization diffraction element at low temperature It is possible to manufacture an optical element or a liquid crystal alignment film in which control is performed.

In the photoreactive composition of the present invention, a copolymer having a repeating unit derived from the monomer represented by the above formula (1) and a repeating unit derived from the monomer represented by the above formula (2). Contains a polymer.
In the above formula (1) and formula (2), X ₁ , X ₂ , Y, Z ₁ to Z ₄ , R ₁ , R ₂ , W, p1, and p2 are as defined above. In particular, X ₁ and X ₂ are each preferably —O—, —O—CO—, —CO—O—, and Y is a benzene ring, naphthalene ring, biphenyl ring, furan ring, respectively. And phenyl benzoate, Z ₁ to Z ₄ are preferably a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and W is preferably a benzene ring or a biphenyl ring. In addition, p1 and p2 are preferably 4 to 10.

In the present invention, preferable specific examples of the monomer represented by the above formula (1) include monomers having the following structure.

In the present invention, preferred specific examples of the monomer represented by the formula (2) include monomers having the following structure.

A repeating unit derived from the monomer represented by the above formula (1) and a repeating unit derived from the monomer represented by the above formula (2), which are contained in the photoreactive composition of the present invention. The copolymer having is represented by the following formula (5).

In the above formula (5), X ₁ , X ₂ , X ₃ , Y, Z ₁ to Z ₄ , R ₁ , R ₂ , W, p1, and p2 each include the above formula (1). ) And the definition in the formula (2).
The ratio of n / m is the ratio of (repeating unit derived from the monomer represented by the above formula (1)) / (repeating unit derived from the monomer represented by the above formula (2)). . In the present invention, the molar ratio of n / m is preferably 10/90 to 80/20, and particularly preferably 20/80 to 50/50. When the ratio of n / m is excessively large, in the heat treatment after the light irradiation, it is necessary to heat at a high temperature for a long time, and it becomes difficult to apply to a film based on a plastic material having low heat resistance, On the other hand, if it is too small, the photoreactivity is not sufficient, and molecular orientation cannot be induced, which is not preferable.

The copolymer having a repeating unit derived from the monomer represented by the above formula (1) and a repeating unit derived from the monomer represented by the above formula (2) preferably has a number average molecular weight. 1000 to 100,000, and preferably 5000 to 30,000. If this number average molecular weight is smaller than the above range, molecular orientation cannot be induced, and if it is larger than the above range, the production becomes extremely difficult and the solubility in a low boiling point solvent decreases. It is not preferable.

A repeating unit derived from the monomer represented by the above formula (1) and a repeating unit derived from the monomer represented by the above formula (2), which are contained in the photoreactive composition of the present invention. The copolymer having a crosslinkable monomer for improving heat resistance to such an extent that liquid crystallinity is not impaired, a photosensitive monomer that does not impair liquid crystallinity, or liquid crystalline Monomers and the like for adjusting the expression temperature can be copolymerized.
Examples of the cross-linkable monomer include the following phenoplast type and epoxy group-containing compounds.

Although the specific example of the said phenoplast type monomer is shown below, it is not limited to this structure.

Specific examples of the epoxy group-containing compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1 , 6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′ , N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N ′,-tetraglycidyl Such as 4,4'-diaminodiphenylmethane and the like.

When the heat resistance is improved to such an extent that the liquid crystal properties are not impaired, the amount used is preferably 0.1 to 30 parts by mass, more preferably 100 parts by mass of the resin component contained in the liquid crystal aligning agent. Is 0.5 to 20 parts by mass. If the amount used is less than 0.1 parts by mass, the effect of improving heat resistance cannot be expected, and if it exceeds 30 parts by mass, the liquid crystallinity may be impaired.

Specific examples of the photosensitive monomer include polymerizable compounds having the following structure or a derivative thereof in the side chain.

The amount used is the sum of the repeating unit derived from the monomer represented by the formula (1) and the repeating unit derived from the monomer represented by the formula (2) / the photosensitive monomer. ) Is preferably 95/5 to 50/50, more preferably 95/5 to 80/20. If the ratio is less than 95/5, the effect of improving the photosensitivity cannot be expected, and if it exceeds 50/50, the liquid crystallinity may be impaired.

Specific examples of the monomer for adjusting the liquid crystalline expression temperature include a polymerizable compound having a structure that becomes a liquid crystal mesogen structure alone, such as biphenyl and phenylbenzoate as shown below. And polymerizable compounds having a structure such that a liquid crystal mesogen structure is formed by hydrogen bonding of side chains such as benzoic acid.

The amount used is (total of repeating units derived from the monomer represented by the above formula (1) and repeating units derived from the monomer represented by the above formula (2)) / single photosensitive amount Body) is preferably 95/5 to 20/80, more preferably 95/5 to 50/50. If the ratio is less than 95/5, the effect of adjusting the liquid crystal expression temperature cannot be expected, and if it exceeds 30/70, the sensitivity of the photoreaction may be impaired.

Furthermore, a copolymer having a repeating unit derived from the monomer represented by the above formula (1) and a repeating unit derived from the monomer represented by the above formula (2) is copolymerized. Examples of the monomer include industrially available monomers capable of radical polymerization reaction.
Specific examples of these monomers include unsaturated carboxylic acid, acrylic ester compound, methacrylic ester compound, maleimide compound, acrylonitrile, maleic anhydride, styrene compound, vinyl compound and the like.

Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid (acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid), itaconic acid, maleic acid, and fumaric acid. .
Specific examples of the (meth) acrylic acid ester compound include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, benzyl (meth) acrylate, naphthyl (meth) acrylate, anthryl (meth) acrylate, anne Tolylmethyl (meth) acrylate, phenyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 2-methoxy Ethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 3-methoxybutyl (meth) acrylate 2-methyl-2-adamantyl (meth) acrylate, 2-propyl-2-adamantyl (meth) acrylate, 8-methyl-8-tricyclodecyl (meth) acrylate, 8-ethyl-8-tricyclodecyl ( (Meth) acrylates having a cyclic ether group such as (meth) acrylate, glycidyl (meth) acrylate, (3-methyl-3-oxetanyl) methyl (meth) acrylate, (3-ethyl-3-oxetanyl) methyl (meth) acrylate Is mentioned.

Specific examples of the vinyl compound include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, propyl vinyl ether and the like.
Specific examples of the styrene compound include styrene, methylstyrene, chlorostyrene, and bromostyrene.
Specific examples of the maleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide and the like.

About the manufacturing method of the copolymer which has a repeating unit derived from the monomer represented by the said Formula (1) of this invention, and a repeating unit derived from the monomer represented by the said Formula (2), It is not particularly limited, and a general-purpose method that is handled industrially can be used. Specifically, it can be produced by cationic polymerization, radical polymerization, or anionic polymerization. Of these, radical polymerization is particularly preferred from the viewpoint of ease of reaction control.
As the polymerization initiator for radical polymerization, known radical thermal polymerization initiators, radical photopolymerization initiators, known reversible addition-fragmentation chain transfer (RAFT) polymerization reagents, and the like can be used.
The amount of the polymerization initiator used is preferably 0.1 to 10 mol% with respect to the monomer (1 mol) represented by the above formula (1).

The above-mentioned radical thermal polymerization initiator is a compound that generates radicals by heating to a decomposition temperature or higher. Specific examples of such radical thermal polymerization initiators include ketone peroxides (such as methyl ethyl ketone peroxide and cyclohexanone peroxide), diacyl peroxides (such as acetyl peroxide and benzoyl peroxide), hydroperoxides (peroxides). Hydrogen oxide, tert-butyl hydride peroxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxyketals (dibutyl peroxide) Cyclohexane etc.), alkyl peresters (peroxyneodecanoic acid-tert-butyl ester, peroxypivalic acid-tert-butyl ester, peroxy 2-ethyl Chlorohexanoic acid-tert-amyl ester), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), azo compounds (azobisisobutyronitrile, 2,2'-di (2-hydroxyethyl) And azobisisobutyronitrile). A radical thermal polymerization initiator can be used individually by 1 type, and can also be used in combination of 2 or more type.

The radical photopolymerization initiator is a compound that initiates radical polymerization by light irradiation. Specific examples of such radical photopolymerization initiators include benzophenone, Michler's ketone, 4,4′-bis (diethylamino) benzophenone, xanthone, thioxanthone, isopropyl xanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4′-isopropylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, isopropyl benzoin ether, isobutyl benzoin ether, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 4,4′-di (t-butylperoxycarbonyl) ) Benzophenone, 3,4,4′-tri (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2- (4′-methoxystyryl) -4,6-bis (trichloro) Methyl) -s-triazine, 2- (3 ′, 4′-dimethoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2 ′, 4′-dimethoxystyryl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- (2'-methoxystyryl) -4,6-bis (trichloromethyl)- -Triazine, 2- (4'-pentyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 4- [pN, N-di (ethoxycarbonylmethyl)]-2,6-di (Trichloromethyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (2′-chlorophenyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (4′-methoxyphenyl) ) -S-triazine, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzthiazole, 2-mercaptobenzothiazole, 3,3′-carbonylbis (7-diethylaminocoumarin), 2- (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2-chlorophenyl) Enyl) -4,4 ′, 5,5′-tetrakis (4-ethoxycarbonylphenyl) -1,2′-biimidazole, 2,2′-bis (2,4-dichlorophenyl) -4,4 ′, 5 , 5′-tetraphenyl-1,2′-biimidazole, 2,2′bis (2,4-dibromophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2,4,6-trichlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 3- (2-methyl-2-dimethylaminopropionyl) ) Carbazole, 3,6-bis (2-methyl-2-morpholinopropionyl) -9-n-dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, bis (5-2,4-cyclopentadien-1-yl) -bis (2,6-Diff Oro-3- (1H-pyrrol-1-yl) -phenyl) titanium, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra ( t-hexylperoxycarbonyl) benzophenone, 3,3′-di (methoxycarbonyl) -4,4′-di (t-butylperoxycarbonyl) benzophenone, 3,4′-di (methoxycarbonyl) -4,3′- Di (t-butylperoxycarbonyl) benzophenone, 4,4′-di (methoxycarbonyl) -3,3′-di (t-butylperoxycarbonyl) benzophenone, 2- (3-methyl-3H-benzothiazole-2- Ylidene) -1-naphthalen-2-yl-ethanone or 2- (3-methyl-1,3-benzothiazole-2 (3H) -ylidene) -1 (2-benzoyl) ethanone, and the like.
These compounds may be used alone or in combination of two or more.

The radical polymerization method using the above-described radical thermal polymerization initiator is not particularly limited, and known emulsion polymerization method, suspension polymerization method, dispersion polymerization method, precipitation polymerization method, bulk polymerization method, solution polymerization method, etc. This method can be used.

The photoreactive composition of the present invention includes a copolymer having a repeating unit derived from the monomer represented by the formula (1) and a repeating unit derived from the monomer represented by the formula (2). In addition to the polymer, it preferably contains an organic solvent that dissolves the copolymer. A thin film can be easily formed from the photoreactive composition of the present invention by adding a polymer solution containing such an organic solvent.
The content of the organic solvent in the photoreactive composition of the present invention is preferably 99.7 to 60% by mass, particularly preferably 99.5 to 70% by mass. By setting it as this content, it can be set as the solution of a preferable viscosity for forming a thin film easily from the photoreactive composition of this invention.

The organic solvent contained in the photoreactive composition of the present invention is not particularly limited as long as it is an organic solvent that dissolves the resin component. Specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, Tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethyl Propanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme 4-hydroxy-4-methyl-2-pentanone, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene Glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, Jeechile Glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene , Propyl ether, dihexyl ether, 1-hexanol, n- Xanthone, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, 3-methoxypropionic acid Methyl, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether -Acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, Examples thereof include lactic acid isoamyl ester. These may be used alone or in combination.

In particular, when the photo-alignment film obtained from the photoreactive composition of the present invention is used as a liquid crystal alignment film, when firing at a low temperature, if there is a large amount of residual solvent after firing, the orientation of the liquid crystal and the adhesion to the substrate will be Since the liquid crystal cell may deteriorate and the electrical characteristics of the liquid crystal cell may deteriorate, it is preferable to use an organic solvent having a low boiling point or a high vapor pressure. Specific examples of such organic solvents include ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, isopropyl Alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, Ethylene glycol monobutyl ether, propylene glycol, propylene glycol Monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl Ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxy Butanol, di Sopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1-hexanol, n-hexane, n-pentane, n-octane, Diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, Ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol- 1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, and lactate isoamyl ester are preferred.

The photoreactive composition of the present invention can further contain a photosensitizer as an additive. As these photosensitizers, colorless sensitizers and triplet sensitizers are preferable.
Examples of the photosensitizer include aromatic nitro compounds, coumarins (7-diethylamino-4-methylcoumarin, 7-hydroxy4-methylcoumarin), ketocoumarins, carbonyl biscoumarins, aromatic 2-hydroxyketones, and amino-substituted compounds. Aromatic 2-hydroxy ketones (2-hydroxybenzophenone, mono- or di-p- (dimethylamino) -2-hydroxybenzophenone), acetophenone, anthraquinone, xanthone, thioxanthone, benzanthrone, thiazoline (2-benzoylmethylene-3 -Methyl-β-naphthothiazoline, 2- (β-naphthoylmethylene) -3-methylbenzothiazoline, 2- (α-naphthoylmethylene) -3-methylbenzothiazoline, 2- (4-biphenoylmethylene)- 3-methylbenzothiazo 2- (β-naphthoylmethylene) -3-methyl-β-naphthothiazoline, 2- (4-biphenoylmethylene) -3-methyl-β-naphthothiazoline, 2- (p-fluorobenzoylmethylene)- 3-methyl-β-naphthothiazoline), oxazoline (2-benzoylmethylene-3-methyl-β-naphthoxazoline, 2- (β-naphthoylmethylene) -3-methylbenzoxazoline, 2- (α-naphthoylmethylene) ) -3-methylbenzoxazoline, 2- (4-biphenoylmethylene) -3-methylbenzoxazoline, 2- (β-naphthoylmethylene) -3-methyl-β-naphthoxazoline, 2- (4-biphenoyl) Methylene) -3-methyl-β-naphthoxazoline, 2- (p-fluorobenzoylmethylene) -3-methyl-β-na Toxazoline), benzothiazole, nitroaniline (m- or p-nitroaniline, 2,4,6-trinitroaniline) or nitroacenaphthene (5-nitroacenaphthene), (2-[(m-hydroxy-p -Methoxy) styryl] benzothiazole, benzoin alkyl ether, N-alkylated phthalone, acetophenone ketal (2,2-dimethoxyphenylethanone), naphthalene, anthracene (2-naphthalenemethanol, 2-naphthalenecarboxylic acid, 9-anthracenemethanol 9-anthracenecarboxylic acid), benzopyran, azoindolizine, melocoumarin and the like.
Of these, aromatic 2-hydroxyketone (benzophenone), coumarin, ketocoumarin, carbonylbiscoumarin, acetophenone, anthraquinone, xanthone, thioxanthone, and acetophenone ketal are preferable.

In addition to the above, the photoreactive composition of the present invention includes a dielectric material for the purpose of changing electrical characteristics such as dielectric constant and conductivity of the liquid crystal alignment film as long as the effects of the present invention are not impaired. In addition, a crosslinkable compound may be added for the purpose of increasing the hardness and density of the film when formed into a liquid crystal alignment film.
Furthermore, in order to improve film thickness uniformity and surface smoothness, a surfactant such as a fluorine-based surfactant, a silicone-based surfactant, and a nonionic surfactant may be added.
More specifically, for example, F-Top 301, EF303, EF352 (manufactured by Tochem Products), MegaFuck F171, F173, R-30 (manufactured by DIC), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Examples include Guard AG710 (manufactured by Asahi Glass Co., Ltd.), Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC Seimi Chemical Co., Ltd.).
The surfactant is preferably contained in an amount of 0.01 to 2 parts by weight, more preferably 0.01 to 1 part by weight, based on 100 parts by weight of the copolymer contained in the photoreactive composition of the present invention. Is done.

Specific examples of the compound that improves the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds. For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Examples thereof include propyltrimethoxysilane and N-bis (oxyethylene) -3-aminopropyltriethoxysilane.

As described above, an optically anisotropic film having excellent characteristics can be obtained from the photoreactive composition of the present invention. However, the production of the optically anisotropic film is preferably carried out as follows. .
The photoreactive composition of the present invention is applied to a substrate to form a coating film. The coating film is usually formed by a spin coating method, a printing method, an ink jet method, a bar coating method, a gravure coating method, or the like.
The drying is usually performed at 40 to 150 ° C. for 1 to 15 minutes, preferably at 50 to 110 ° C. for 1 to 5 minutes.
The thickness of the coating film is usually 0.02 to 5.0 μm, preferably 0.02 to 2.0 μm.

In the present invention, the substrate for forming the coating film of the photoreactive composition is not particularly limited as long as it is a highly transparent substrate, and a plate-like to film-like one is used.
As the material of the base material, ceramics such as glass, silicon nitride, and silicon wafer, plastics such as acrylic resin, polycarbonate resin, triacetyl cellulose resin, polyethylene terephthalate resin, and cycloolefin resin can be used. Especially, in this invention, as mentioned above, it has the characteristics which can use plastics with small heat resistance as a base material.

The coating film of the photoreactive composition can then be oriented and imparted with anisotropy by irradiation treatment with polarized ultraviolet rays. As the polarized ultraviolet rays, those having a wavelength of preferably 200 to 400 nm, particularly preferably 254 to 365 nm are used. The irradiation amount is preferably 1 to 10000 mJ, particularly preferably 1 to 500 mJ. The irradiation with polarized ultraviolet rays may be performed while heating the coating film preferably at 10 to 150 ° C., particularly preferably at 20 to 120 ° C.

The coating film of the photoreactive composition formed on the substrate is then subjected to heat treatment. The heat treatment is preferably performed at 50 to 150 ° C. for 1 to 30 minutes, particularly preferably at 70 to 120 ° C. for 1 to 15 minutes. At this time, the upper limit of the heating temperature is selected depending on the substrate to be used, and the lower limit is selected depending on the liquid crystalline expression temperature of the polymer.
As described above, a thin film of a photoreactive composition can be produced on a substrate.
The film thickness of the thin film of the photoreactive composition is preferably 20 to 5000 nm, and more preferably 20 to 2000 nm.

Hereinafter, the present invention will be specifically described with reference to examples of the present invention, but the present invention is not construed as being limited thereto.

<Synthesis Example 1>
A compound represented by the following formula (1) was synthesized by a synthesis method described in a patent document (WO2011-084546).

<Synthesis Example 2>
Compound (A) was obtained by the synthesis method described in the patent document (Japanese Patent Laid-Open No. 9-118717). After dissolving 10.0 g of this compound (A), DMAP (4-dimethylaminopyridine) (0.3 g) and methoxyphenol (4.1 g) in 100 ml of dichloromethane at room temperature, DCC (N, N′-dicyclohexylcarbodiimide) (7.9 g) was added and reacted at room temperature to obtain 11.4 g (yield 85%) of a compound represented by the following formula (2).

<Synthesis Example 3>
Suspend 2-9.2 g of 4- (6-acryloyloxy-1-hexyloxy) benzoic acid, 17.0 g of 4-hydroxybiphenyl, 0.6 g of DMAP, and a small amount of dibutylhydroxytoluene (BHT) in 200 mL of methylene chloride at room temperature. I let you. Thereafter, a methylene chloride solution (100 ml of methylene chloride) in which 24.0 g (116 mmol) of DCC was dissolved was added to this suspension and reacted at room temperature, whereby 39.6 g of a compound represented by the following formula (3) (yield) 89%).

<Synthesis Example 4>
Methacrylic acid ester (1.5 g) represented by the above formula (1) and methacrylic acid ester (1.24 g) represented by the above formula (2) in tetrahydrofuran (25 ml) at a ratio (molar ratio) of 60:40. And then added with azobisisobutyronitrile (AIBN) as a reaction initiator (2.0 mol% with respect to the total of the methacrylic acid esters of the formula (1) and the formula (2)) and polymerized (polymerization temperature). To obtain a polymer 1.
The molecular weight of this polymer 1 was Mn: 41000, and this polymer 1 exhibited liquid crystallinity in the temperature range of 77 to 152 ° C.

<Synthesis Example 5>
Polymer 2 was obtained by performing the same operation as in Synthesis Example 4 except that the ratio of Formula (1) and Formula (2) in Synthesis Example 4 was 40:60. The molecular weight of this polymer 2 was Mn: 27000, and this polymer 2 exhibited liquid crystallinity in the temperature range of 53 to 132 ° C.

<Synthesis Example 6>
Polymer 3 was obtained by performing the same operation as in Synthesis Example 4 except that the ratio of Formula (1) and Formula (2) in Synthesis Example 4 was 20:80. The molecular weight of this polymer 3 was Mn: 43000, and this polymer 3 exhibited liquid crystallinity in the temperature range of 43 to 119 ° C.

<Synthesis Example 7>
The same operation as the synthesis example 4 is performed except that the formula (2) of the synthesis example 4 is changed to the formula (3) and the ratio of the formula (1) and the formula (3) is set to 30:70. As a result, a polymer 4 was obtained. The molecular weight of this polymer 4 was Mn: 11000, and this polymer 4 exhibited liquid crystallinity in the temperature range of 80 to 135 ° C.

<Synthesis Example 8>
A methacrylic acid ester (1.0 g) represented by the above formula (1) is dissolved in tetrahydrofuran (9.1 ml), and azobisisobutyronitrile (AIBN) is added as a reaction initiator (methacrylic acid of the formula (1)). Polymer 5 was obtained by polymerization (polymerization temperature 50 ° C.) by polymerization (1.5 mol% with respect to the acid ester). The molecular weight of this polymer 5 was Mn: 31000, and this polymer 5 exhibited liquid crystallinity in the temperature range of 147 to 199 ° C.

<Preparation of oriented film with anisotropy introduced>
<Example 1>
The polymer 1 (0.3 g) obtained in Synthesis Example 4 is dissolved in tetrahydrofuran (14.7 ml) and spin-coated on a glass substrate with a thickness of about 190 nm, whereby a side chain polymer film is formed on the substrate. Formed. After measuring the ultraviolet absorption spectrum using this substrate, the side chain type polymer film was irradiated with ultraviolet rays having a wavelength of 300 nm or less cut and converted into linearly polarized light using a Grand Taylor prism.
The side-chain polymer film on the substrate thus obtained was used to measure the ultraviolet absorption spectrum, and the side-chain polymer film was measured in a direction perpendicular to the UV absorbance in the direction parallel to the polarization direction of the irradiated polarized UV light. ΔA, which is the difference from the ultraviolet absorbance, was evaluated.
ΔA reaches a maximum of 0.15 at 314 nm when irradiated with polarized ultraviolet rays at a wavelength of 365 nm in an amount of 70 mJ. On the other hand, irradiated with polarized ultraviolet rays (measured at a wavelength of 365 nm) with 300 nm or less cut so that ΔA is 0.035 (23% difference from the maximum value), and then the substrate is heated to 100 ° C. It heated and the side chain type polymer film was kept as a liquid crystal alignment layer for 5 minutes. Then, it cooled to room temperature and obtained the board | substrate which has the side chain type polymer film (film thickness 190nm) by which the anisotropy was introduce | transduced in the film | membrane. In that case, ΔA was greatly amplified, the degree of orientation was 0.45, and the birefringence at that time was 0.11.

<Example 2>
Polymer 2 (0.3 g) obtained in Synthesis Example 5 was used, except that the irradiation amount of polarized ultraviolet rays was 5 mJ (the irradiation amount at which ΔA was 25% of the maximum value of ΔA), and the heating temperature was 95 ° C. In the same manner as in Example 1, irradiation with polarized ultraviolet rays and subsequent heat treatment were performed. As a result, ΔA before and after the heat treatment was greatly amplified, the degree of orientation was 0.58 at 314 nm, and the birefringence at that time was 0.12.

<Example 3>
Polymer 3 (0.3 g) obtained in Synthesis Example 6 was used, the amount of irradiation with polarized ultraviolet rays was 8 mJ (the amount of irradiation with which ΔA was 33% of the maximum value of ΔA), and the heating temperature was 85 ° C. In the same manner as in Example 1, irradiation with polarized ultraviolet rays and subsequent heat treatment were performed. As a result, ΔA before and after the heat treatment was greatly amplified, the degree of orientation was 0.48 at 314 nm, and the birefringence at that time was 0.16.

<Example 4>
Polymer 1 (0.3 g) obtained in Synthesis Example 4 was dissolved in a mixed solvent of propylene glycol monomethyl ether and cyclohexanone (volume ratio 7: 3, 2.7 ml), and a thickness of about 800 nm was formed on the acrylic film. The side chain type polymer film was formed on the film by coating with (1). The film on which this polymer film was formed was irradiated with 20 mJ of ultraviolet rays converted to linearly polarized light of 313 nm using a Grand Taylor prism. Thereafter, this substrate was heated to 100 ° C. in a hot air circulating oven, and the side chain type polymer film was held as it was for 10 minutes as a liquid crystal alignment layer. Then, it cooled to room temperature and obtained the film which has a side chain type polymer film (film thickness of 800 nm) in which anisotropy was introduced in the film. The birefringence of this film was 0.08.

<Example 5>
Polymer 2 (0.3 g) obtained in Synthesis Example 5 was dissolved in a mixed solvent of propylene glycol monomethyl ether and cyclohexanone (volume ratio 7: 3, 2.7 ml), and irradiated with 10 mJ of ultraviolet rays converted to linearly polarized light. Except for the above, a film having a side chain polymer film having anisotropy introduced therein was obtained in the same manner as in Example 4. The birefringence of this film was 0.074.

<Example 6>
Polymer 4 (0.3 g) obtained in Synthesis Example 7 was dissolved in a mixed solvent of propylene glycol monomethyl ether acetate and cyclohexanone (volume ratio 7: 3, 2.7 ml) and irradiated with 7 mJ of ultraviolet light converted to linearly polarized light. Except for the above, a film having a side chain polymer film having anisotropy introduced therein was obtained in the same manner as in Example 4. The birefringence of this film was 0.056.

<Comparative Example 1>
The polymer 5 (0.3 g) obtained in Synthesis Example 8 is dissolved in tetrahydrofuran (14.7 ml), and spin-coated on a glass substrate with a thickness of about 150 nm, whereby a side chain polymer film is formed on the substrate. In the film, irradiation with polarized ultraviolet light and subsequent heat treatment were performed in the same manner as in Example 1 except that the amount of irradiation with polarized ultraviolet light was 5 mJ (the amount of irradiation with which ΔA was 10% of the maximum value of ΔA). A substrate having a side chain polymer film with anisotropy introduced therein was obtained. At this time, ΔA before and after the heat treatment did not change from 0.07 to 0.07, and amplification of ΔA was not confirmed. At that time, the birefringence was 0.01.

<Comparative Example 2>
Polymer 5 (0.3 g) obtained in Synthesis Example 8 was dissolved in a mixed solvent of propylene glycol monomethyl ether and diethylene glycol monomethyl ether (volume ratio 7: 3, 2.7 ml), and the thickness of about 800 nm was formed on the acrylic film. By coating, a side chain type polymer film was formed on the film. The film on which this polymer film was formed was irradiated with 5 mJ of ultraviolet rays converted to 313 nm linearly polarized light using a Grand Taylor prism. Thereafter, this substrate was heated to 100 ° C. in a hot air circulating oven, and the side chain type polymer film was held as it was for 10 minutes as a liquid crystal alignment layer. Then, it cooled to room temperature and obtained the film which has a side chain type polymer film into which anisotropy was introduced in the film. The birefringence of this film was 0.01.

[Production of liquid crystal cell]
<Example 7>
Polymer 1 (0.3 g) obtained in Synthesis Example 4 was dissolved in a mixed solvent of propylene glycol monomethyl ether and cyclohexanone (volume ratio 3: 7, 4.7 ml) to obtain a liquid crystal aligning agent (A). The liquid crystal aligning agent (A) was applied to a glass substrate by a spin coating method, and then dried on a hot plate at 50 ° C. for 5 minutes to obtain a polymer film having a thickness of 80 nm. This polymer film was irradiated with 4 mJ of ultraviolet rays converted to 313 nm linearly polarized light using a Grand Taylor prism. Thereafter, this substrate was heated to 100 ° C. on a hot plate, and the side chain polymer film was kept as a liquid crystal phase for 10 minutes. Then, it cooled to room temperature and obtained the board | substrate which has the liquid crystal aligning film into which the anisotropic was introduce | transduced in the film | membrane.
An anti-parallel liquid crystal cell sandwiching liquid crystal MLC-2003 (manufactured by Merck Japan Co., Ltd.) was obtained using the two substrates with a liquid crystal alignment film that had been subjected to the alignment treatment.
When the obtained liquid crystal cell was observed under crossed Nicols, uniform liquid crystal alignment without alignment failure was observed.
In addition, two ITO (Indium Tin Oxide) substrates with a liquid crystal alignment film introduced with such anisotropy were produced, and a liquid crystal MLC-2003 (C60) was sandwiched between them to obtain a liquid crystal cell Was further sandwiched between a pair of linear polarizing plates to produce a TN (Twisted Nematic) type liquid crystal display element having a liquid crystal thickness of 6 μm.
In this TN type liquid crystal display element, it was confirmed that the liquid crystal was driven by applying a voltage to the ITO electrode.
In addition, it was confirmed that the liquid crystal display element had no alignment defect over the entire surface, and a uniform change in the alignment of liquid crystal due to voltage application was confirmed.
That is, a liquid crystal display element could be manufactured using the liquid crystal alignment film obtained above. The evaluation results are summarized in Table 1.

<Example 8>
Polymer 2 (0.3 g) obtained in Synthesis Example 5 was used, except that the irradiation amount of polarized ultraviolet rays was 5 mJ (the irradiation amount at which ΔA was 25% of the maximum value of ΔA), and the heating temperature was 95 ° C. Produced a liquid crystal cell in the same manner as in Example 7. The results are summarized in Table 1.

<Example 9>
Polymer 3 (0.3 g) obtained in Synthesis Example 6 was used, the amount of irradiation with polarized ultraviolet rays was 8 mJ (the amount of irradiation with which ΔA was 33% of the maximum value of ΔA), and the heating temperature was 85 ° C. Produced a liquid crystal cell in the same manner as in Example 7. The results are summarized in Table 1.

<Comparative Example 3>
Polymer 5 (0.3 g) obtained in Synthesis Example 8 was dissolved in tetrahydrofuran (14.7 ml), and a polymer film was formed on the substrate by spin coating on a glass substrate with a thickness of about 80 nm. In addition, a liquid crystal cell was produced in the same manner as in Example 7 except that the irradiation amount of polarized ultraviolet rays was changed to 5 mJ.
When the obtained antiparallel cell was observed under crossed Nicols, the liquid crystal was non-aligned, and uniform liquid crystal alignment was not obtained. The results are summarized in Table 1.

Since the photo-alignment film and retardation film formed from the photoreactive composition of the present invention can be formed on a plastic having low heat resistance, it is widely used as an optical element or liquid crystal alignment film with controlled molecular orientation. It can be used and has high industrial utility.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2012-250558 filed on November 14, 2012 are incorporated herein as the disclosure of the specification of the present invention. Is.

Claims (10)

1. A light comprising a copolymer having a repeating unit derived from a monomer represented by the following formula (1) and a repeating unit derived from a monomer represented by the following formula (2): Reactive composition.
   

   

   (X ₁ and X ₂ are each independently —O—, —O—CO—, —CO—O—, —NH—CO—, or —CO—NH—.
   X ₃ is —O—CO— or —CO—O—. Y is a group selected from the group consisting of a benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring, benzophenone, and phenylbenzoate, and each ring is an alkyl group, an alkoxy group, a halogen atom, a nitro group, or It may be substituted with a cyano group.
   R ₁ and R ₂ are each independently a hydrogen atom or a methyl group.
   p1 and p2 are each independently an integer of 2 to 12.
   W is a group selected from the group consisting of a benzene ring, a naphthalene ring, and a biphenyl ring, and each ring may be substituted with an alkyl group, an alkoxy group, a halogen atom, a nitro group, or a cyano group.
   Z ₁ to Z ₄ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a nitro group, or a cyano group. )
2. The molar ratio of (repeat unit derived from the monomer represented by the above formula (1)) / (repeat unit derived from the monomer represented by the above formula (2)) was 10/90 to 80/20. The photoreactive composition according to claim 1.
3. The monomer represented by the above formula (1) is a cinnamic acid compound represented by the following formula (3), and the monomer represented by the above formula (2) is benzoic acid represented by the following formula (4). The photoreactive composition according to claim 1, which is an ester compound.
   

   

   (R ₁ and p ₁ are respectively synonymous with those defined in the above formula (1).
   X ₄ is a single bond, —O—CO—, or —CO—O—.
   m is 0 or 1, and when m is 0, X ₄ is a single bond. )
   

   

   (R ₂ , p 2 _, X _3, and Z ₁ to Z ₄ are respectively synonymous with those defined in the above formula (2).
   R ₃ is a hydrogen atom, an alkyl group, or an alkoxy group.
   m ₁ is 1 or 2. )
4. The photoreactive composition according to any one of claims 1 to 3, wherein the copolymer has a number average molecular weight of 1,000 to 100,000.
5. The photoreactive composition according to any one of claims 1 to 4, further comprising an organic solvent.
6. 6. The photoreactive composition according to claim 5, wherein the organic solvent is a low boiling point solvent having a boiling point of 60 to 170 ° C.
7. The photoreactive composition according to claim 5 or 6, wherein the content of the organic solvent is 60 to 99.5% by mass relative to the total amount of the photoreactive composition.
8. An optically anisotropic film obtained by irradiating the coating of the photoreactive composition according to any one of claims 1 to 7 with light containing a linearly polarized component and then heat-treating to impart liquid crystal alignment ability.
9. The optically anisotropic film according to claim 8, which is heat-treated at a temperature of 70 to 120 ° C.
10. The optically anisotropic film according to claim 8 or 9, wherein the film thickness is 20 to 5000 nm.