JP7501371B2 - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal display element and novel monomer - Google Patents

Description

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained thereby, and a liquid crystal display element having the obtained liquid crystal alignment film. More specifically, the present invention relates to a liquid crystal alignment agent capable of providing a liquid crystal alignment film having good liquid crystal alignment properties, excellent pretilt angle expression ability, and high reliability, and a liquid crystal display element having excellent display quality.

In liquid crystal display elements, the role of the liquid crystal alignment film is to align the liquid crystal in a certain direction. Currently, the main liquid crystal alignment films used industrially are produced by applying a polyimide-based liquid crystal alignment agent made of a polyimide precursor such as polyamide acid (also called polyamic acid), polyamic acid ester, or a polyimide solution to a substrate and forming a film.
Furthermore, when the liquid crystal is to be aligned parallel or inclined to the substrate surface, a surface stretching treatment by rubbing is further carried out after the film formation.

On the other hand, when the liquid crystal is aligned perpendicular to the substrate (called the vertical alignment (VA) method), a liquid crystal alignment film is used in which hydrophobic groups such as long-chain alkyl, cyclic groups, or combinations of cyclic groups and alkyl groups (see, for example, Patent Document 1), or steroid skeletons (see, for example, Patent Document 2) are introduced into the side chains of polyimide. In this case, when a voltage is applied between the substrates to tilt the liquid crystal molecules in a direction parallel to the substrate, it is necessary to make the liquid crystal molecules tilt from the substrate normal direction toward one direction in the substrate plane. As a means for this, for example, a method of providing protrusions on the substrate, a method of providing slits in the display electrode, a method of slightly tilting the liquid crystal molecules from the substrate normal direction toward one direction in the substrate plane by rubbing (pretilting), and a method of adding a photopolymerizable compound to the liquid crystal composition in advance, using it together with a vertical alignment film such as polyimide, and applying a voltage to the liquid crystal cell while irradiating ultraviolet light to pretilt the liquid crystal (see, for example, Patent Document 3) have been proposed.

In recent years, a method (photoalignment method) that utilizes anisotropic photochemical reactions caused by irradiation with polarized ultraviolet light, etc., has been proposed as an alternative to the formation of protrusions and slits in the VA method of liquid crystal alignment control and to PSA technology. That is, it is known that the tilt direction of liquid crystal molecules when a voltage is applied can be uniformly controlled by irradiating a photoreactive vertical alignment polyimide film with polarized ultraviolet light to impart alignment control ability and pretilt angle expression ability (see Patent Document 4).

VA-type liquid crystal display elements are used in TVs and in-vehicle displays because of their high contrast and wide viewing angle. Liquid crystal display elements for TVs use backlights that generate a large amount of heat to obtain high brightness, and liquid crystal display elements used for in-vehicle applications, such as car navigation systems and meter panels, may be used or left in high-temperature environments for long periods of time. If the pretilt angle gradually changes under such harsh conditions, problems such as the initial display characteristics being no longer obtained and uneven display may occur. Furthermore, the voltage retention characteristics and charge accumulation characteristics when the liquid crystal is driven are also affected by the liquid crystal alignment film, and if the voltage retention rate is low, the contrast of the display screen decreases, and if the charge accumulation relative to the DC voltage is large, the display screen may burn in. In particular, in order to increase the transmittance, it is necessary to impart a relatively large tilt angle, such as a tilt of 2° or more from the vertical, but there has been no material that can impart such a large tilt angle by photo-alignment treatment and stably maintain the imparted tilt angle.

Japanese Patent Application Laid-Open No. 3-179323 Japanese Patent Application Laid-Open No. 4-281427 Japanese Patent No. 4504626 Japanese Patent No. 4995267

The present invention has been made in consideration of the above circumstances, and its object is to provide a liquid crystal alignment film which has little change in pretilt angle even after long-term operation, resulting in excellent display reliability, has high voltage retention characteristics, and can reduce charge accumulation, a liquid crystal display element having the same, and a liquid crystal alignment agent which provides the same.

The present inventors have discovered the invention having the following gist <X>.
<X> Component (A) represented by the following formula (pa-1) (in the formula, A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene, 1,4- or 2,6-naphthylene, or phenylene optionally substituted with a group selected from fluorine, chlorine, or cyano, or with an alkoxy group having 1 to 5 carbon atoms, or a linear or branched alkyl residue (which is optionally substituted with one cyano group or one or more halogen atoms); R ₁ represents a single bond, an oxygen atom, -COO-, or -OCO-; R ₂ represents a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent fused ring group; R ₃ represents -COO- or -OCO-; A liquid crystal aligning agent comprising a polymer having a photoalignable group represented by the formula (I) and a solvent, wherein ₄ is a linear or branched alkyl group having 1 to 40 carbon atoms or a monovalent organic group having 3 to 40 carbon atoms containing an alicyclic group, D is an oxygen atom, a sulfur atom or -NR _d - (wherein R _d is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), a is an integer of 0 to 3, and * is a bonding position.

The present invention provides a liquid crystal alignment film and a liquid crystal alignment agent that have good liquid crystal alignment properties, excellent pretilt angle expression ability, and excellent display reliability with little change in pretilt angle even after long-term operation. Furthermore, the liquid crystal display element manufactured by the method of the present invention has excellent display characteristics.

The liquid crystal alignment agent of the present invention is characterized by containing, as component (A), a polymer having a photoalignable group represented by the following formula (pa-1) and a solvent.

In the formula, A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene, 1,4- or 2,6-naphthylene or phenylene, which is optionally substituted with a group selected from fluorine, chlorine, cyano, or with an alkoxy group having 1 to 5 carbon atoms, a linear or branched alkyl residue, which is optionally substituted with one cyano group or one or more halogen atoms; R ₁ represents a single bond, an oxygen atom, -COO- or -OCO-; R ₂ represents a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group or a divalent fused ring group; R ₃ represents -COO- or -OCO-; R ₄ represents a monovalent organic group having 3 to 40 carbon atoms, including a linear or branched alkyl group or an alicyclic group having 1 to 40 carbon atoms; D represents an oxygen atom, a sulfur atom or -NR _d - (wherein R _d represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), a is an integer of 0 to 3, and * represents the bonding position.

The liquid crystal aligning agent may be such that the component (A) is a polymer further having a thermal crosslinkable group A and satisfies at least one of the following requirements Z1 and Z2.
Z1: The polymer which is the component (A) further has a thermally crosslinkable group B.
Z2: The component (B) further contains a compound having two or more thermally crosslinkable groups B in the molecule.
The thermally crosslinkable group A and the thermally crosslinkable group B are each independently an organic group selected from the group consisting of a carboxyl group, an amino group, an alkoxymethylamide group, a hydroxymethylamide group, a hydroxyl group, an epoxy moiety-containing group, an oxetanyl group, a thiiranyl group, an isocyanate group, and a blocked isocyanate group, and are selected so that the thermally crosslinkable group A and the thermally crosslinkable group B undergo a crosslinking reaction by heat, however, the thermally crosslinkable group A and the thermally crosslinkable group B may be the same as each other.

Here, "two or more within a molecule" refers to cases where the molecule contains two or more groups of the same type, such as two or more epoxy groups, as well as cases where the molecule contains two or more groups of different types, such as a combination of an epoxy group and a thiirane group. "Two or more within a molecule" preferably refers to cases where the molecule contains two or more groups of the same type.

The polymer, which is the component (A) contained in the liquid crystal aligning agent of the present invention, has high sensitivity to light, and therefore can exhibit alignment control ability even when irradiated with polarized ultraviolet light with a low exposure dose.
In addition, when the polymer, which is component (A), contains a thermal crosslinkable group A and further contains a thermal crosslinkable group B in the component, a crosslinking reaction involving the polymer, which is component (A), is possible even if the baking time of the liquid crystal alignment agent is short. As a result, when the photo-alignable portion exhibits anisotropy due to a photoreaction, the anisotropy tends to remain (memory) in the liquid crystal alignment film, so that it is possible to enhance the liquid crystal alignment and exhibit a pretilt angle of the liquid crystal.

In addition, the photoalignable group, the thermally crosslinkable group A, and the thermally crosslinkable group B represented by the above formula (pa-1) can all be side chains in a polymer, and therefore can also be referred to as "side chains" as necessary.
Each of the constituent elements of the present invention will be described in detail below.

<Component (A): Specific Polymer>
[Photoalignment group represented by formula (pa-1)]
In the present invention, the moiety having photoalignment property represented by the above formula (pa-1) in the molecule can be represented by, for example, the following formula (a-1). In addition, the moiety can be a structure derived from a monomer represented by the following formula (a-1-m), but is not limited thereto. In the formula, Ia is a monovalent organic group represented by the following formula (pa-1).

In formula (pa-1), A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene, 1,4- or 2,6-naphthylene or phenylene, which is optionally substituted with a group selected from fluorine, chlorine or cyano, or with an alkoxy group having 1 to 5 carbon atoms, a linear or branched alkyl residue (which is optionally substituted with one cyano group or one or more halogen atoms); R ₁ represents a single bond, an oxygen atom, -COO- or -OCO-; R ₂ represents a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group or a divalent fused ring group; R ₃ represents -COO- or -OCO-; R ₄ represents a monovalent organic group having 3 to 40 carbon atoms containing a linear or branched alkyl group or an alicyclic group having 1 to 40 carbon atoms; D represents an oxygen atom, a sulfur atom or -NR _d- (wherein R _d represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), a is an integer of 0 to 3, and * represents the bonding position.

In the above formula (a-1) or (a-1-m), S _a represents a spacer unit, and the bonding group to the left of S _a indicates that it is bonded to the main chain of the specific polymer, optionally via a spacer.
S _a can be represented, for example, by the structure of the following formula (Sp).

In formula (Sp),
The left bond of _W1 represents a bond to _Mb ;
the right bond of _W3 represents a bond to _Ia ;
W ₁ , W ₂ and W ₃ each independently represent a single bond, a divalent heterocycle, -(CH ₂ ) _n - (wherein n is 1 to 20), -OCH ₂ -, -CH ₂ O-, -COO-, -OCO-, -CH═CH-, -CF═CF-, -CF ₂ O-, -OCF ₂ -, -CF ₂ CF ₂ - or -C≡C-, provided that one or more non-adjacent CH ₂ groups in these substituents are independently -O-, -CO-, -CO-O-, -O-CO-, -Si(CH ₃ ) ₂ -O-Si(CH ₃ ) ₂ may be substituted by —, —NR—, —NR—CO—, —CO—NR—, —NR—CO—O—, —OCO—NR—, —NR—CO—NR—, —CH═CH—, —C≡C— or —O—CO—O— (wherein R independently represents hydrogen or a linear or branched alkyl group having 1 to 5 carbon atoms);
_A1 and _A2 each independently represent a group selected from a single bond, a divalent alkyl group, a divalent aromatic group, a divalent alicyclic group, or a divalent heterocyclic group, and each of these groups may be unsubstituted or one or more hydrogen atoms may be substituted with a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group.

In formula (a-1-m), M _a represents a polymerizable group. Examples of the polymerizable group include radical polymerizable groups of (meth)acrylate, fumarate, maleate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, (meth)acrylamide and derivatives thereof, and siloxane. Preferred are (meth)acrylate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, and acrylamide.
r is an integer satisfying 1≦r≦3.
_Mb is a group selected from a single bond, a (r+1)-valent heterocycle, a linear or branched alkyl group having 1 to 10 carbon atoms, a (r+1)-valent aromatic group, and a (r+1)-valent alicyclic group, each of which is unsubstituted or in which one or more hydrogen atoms are substituted with a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group.

Examples of the aromatic groups in A ₁ , A ₂ and M _b include aromatic hydrocarbons having 6 to 18 carbon atoms, such as benzene, biphenyl and naphthalene. Examples of the alicyclic groups in A ₁ , A ₂ and M _b include alicyclic hydrocarbons having 6 to 12 carbon atoms, such as cyclohexane and bicyclohexane. Examples of the heterocycles in A ₁ , A ₂ and M _b include nitrogen-containing heterocycles, such as pyridine, piperidine and piperazine. Examples of the alkyl groups in A ₁ and A ₂ include linear or branched alkyl groups having 1 to 10 carbon atoms.

From the viewpoint of being able to realize good vertical alignment control ability and a stable pretilt angle, it is preferable that the group represented by (pa-1) above is a group represented by the following (pa-1-a). In addition, the moiety can be, but is not limited to, a structure derived from a monomer represented by the following formula (pa-1-ma).

In the formula (pa-1-a) or (pa-1-ma), M _a , M _b , and S _a are defined as above.
Furthermore, Z is an oxygen atom or a sulfur atom.
_Xa and _Xb each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms.
R ₁ is a single bond, an oxygen atom, —COO— or —OCO—.
_R2 is a divalent aromatic group, a divalent alicyclic group, or a divalent heterocyclic group.
_R3 is -COO- or -OCO-.
_R4 is a monovalent organic group having 3 to 40 carbon atoms which contains a linear or branched alkyl group having 1 to 40 carbon atoms or an alicyclic group.
_R5 is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine atom or a cyano group, preferably a methyl group, a methoxy group or a fluorine atom.
a is an integer from 0 to 3, and b is an integer from 0 to 4.

In formula (pa-1-a) or (pa-1-ma), the linear or branched alkylene group having 1 to 10 carbon atoms for _Sa is preferably a linear or branched alkylene group having 1 to 8 carbon atoms, and for example, a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a t-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, or an n-octylene group is preferable.
Examples of the divalent aromatic group for S _a include a 1,4-phenylene group, a 2-fluoro-1,4-phenylene group, a 3-fluoro-1,4-phenylene group, and a 2,3,5,6-tetrafluoro-1,4-phenylene group.

In formula (pa-1-a) or (pa-1-ma), examples of the divalent alicyclic group for _Sa include trans-1,4-cyclohexylene and trans-trans-1,4-bicyclohexylene.
Examples of the divalent heterocyclic group for S _a include a 1,4-pyridylene group, a 2,5-pyridylene group, a 1,4-furanylene group, a 1,4-piperazine group, and a 1,4-piperidine group.
S _a is preferably an alkylene group having 1 to 8 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, and even more preferably an alkylene group having 1 to 4 carbon atoms.

Examples of the divalent aromatic group for _R2 include a 1,4-phenylene group, a 2-fluoro-1,4-phenylene group, a 3-fluoro-1,4-phenylene group, a 2,3,5,6-tetrafluoro-1,4-phenylene group, and a naphthylene group.
Examples of the divalent alicyclic group of _R2 include trans 1,4-cyclohexylene and trans-trans-1,4-bicyclohexylene.
Examples of the divalent heterocyclic group for _R2 include a 1,4-pyridylene group, a 2,5-pyridylene group, a 1,4-furanylene group, a 1,4-piperazine group, and a 1,4-piperidine group.
_R2 may be a 1,4-phenylene group, trans 1,4-cyclohexylene, or trans-trans-1,4-bicyclohexylene.

The linear or branched alkyl group having 1 to 40 carbon atoms for R ₄ may be, for example, a linear or branched alkyl group having 1 to 20 carbon atoms, in which some or all of the hydrogen atoms may be substituted with fluorine atoms. Examples of such alkyl groups include, for example, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-lauryl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an n-eicosyl group, and 4,4,4 -trifluorobutyl group, 4,4,5,5,5-pentafluoropentyl, 4,4,5,5,6,6,6-heptafluorohexyl group, 3,3,4,4,5,5,5-heptafluoropentyl group, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 2-(perfluorobutyl)ethyl group, 2-(perfluorooctyl)ethyl group, and 2-(perfluorodecyl)ethyl group.

Examples of the monovalent organic group having 3 to 40 carbon atoms and containing an alicyclic group for _R4 include a cholestenyl group, a cholestanylic group, an adamantyl group, and a group represented by the following formula (Alc-1) or (Alc-2) (wherein _R7 is a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 20 carbon atoms which may be substituted with a fluorine atom, and * indicates a bonding position).

As the monomer represented by the above formula (pa-1-ma), for example, the following formula (MA) (wherein S _b represents a linear or branched alkyl group having 1 to 10 carbon atoms, R ₆ is a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkyl group having 1 to 10 carbon atoms substituted with a halogen, R ₇ is a single bond, an oxygen atom, -COO- or -OCO-, R ₈ is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group or a divalent condensed cyclic group, R ₉ is -COO- or -OCO-, R ₁₀ is a linear or branched alkyl group having 1 to 10 carbon atoms in which the hydrogen atom of the alkyl group may be substituted with fluorine, and b represents an integer of 0 to 3.) is preferably a polymerizable monomer having a photoalignment group.

Examples of monomers represented by the above formula (paa-1-ma) include, but are not limited to, structures represented by formulas (paa-1-ma1) to (paa-1-ma38). In the formulas, "E" represents an E-form, and "t" represents a trans-type cyclohexyl group. In addition, n and m in formulas (paa-1-ma1) to (paa-1-ma38) represent 1 to 10.

These monomers can be produced by combining known reactions, specifically, by the method described in the "Monomer Synthesis Examples" below.

[Thermal crosslinkable group A and thermal crosslinkable group B]
The thermally crosslinkable group A and the thermally crosslinkable group B are each independently an organic group selected from the group consisting of a carboxyl group, an amino group, an alkoxymethylamide group, a hydroxymethylamide group, a hydroxyl group, an epoxy moiety-containing group, an oxetanyl group, a thiiranyl group, an isocyanate group, and a blocked isocyanate group, and are selected so that the thermally crosslinkable group A and the thermally crosslinkable group B undergo a crosslinking reaction by heat, however, the thermally crosslinkable group A and the thermally crosslinkable group B may be the same as each other.

Such combinations of thermally crosslinkable groups A and B include a combination in which one is a carboxyl group and the other is an epoxy group, an oxetanyl group, or a thiiranyl group, a combination in which one is a hydroxyl group and the other is a blocked isocyanate group, a combination in which one is a phenolic hydroxyl group and the other is an epoxy group, an oxetanyl group, or a thiiranyl group, a combination in which one is a carboxyl group and the other is a blocked isocyanate group, a combination in which one is an amino group and the other is a blocked isocyanate group, a combination in which both are N-alkoxymethylamide, etc. More preferred combinations are a carboxyl group and an epoxy group, a hydroxyl group and a blocked isocyanate group, etc.

To introduce such a thermally crosslinkable group A into the polymer, which is component (A), a monomer having a thermally crosslinkable group A may be copolymerized. In addition, when the liquid crystal aligning agent of the present invention satisfies requirement Z1, both a monomer having a thermally crosslinkable group A and a monomer having a thermally crosslinkable group B may be copolymerized when producing the polymer, which is component (A).

Examples of monomers having a thermal crosslinkable group include monomers having a carboxyl group, such as acrylic acid, methacrylic acid, crotonic acid, mono-(2-(acryloyloxy)ethyl)phthalate, mono-(2-(methacryloyloxy)ethyl)phthalate, N-(carboxyphenyl)maleimide, N-(carboxyphenyl)methacrylamide, and N-(carboxyphenyl)acrylamide;

Monomers having a hydroxy group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2,3-dihydroxypropyl acrylate, 2,3-dihydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, caprolactone 2-(acryloyloxy)ethyl ester, caprolactone 2-(methacryloyloxy)ethyl ester, poly(ethylene glycol) ethyl ether acrylate, poly(ethylene glycol) ethyl ether methacrylate, 5-acryloyloxy-6-hydroxynorbornene-2-carboxylic-6-lactone, and 5-methacryloyloxy-6-hydroxynorbornene-2-carboxylic-6-lactone;

Monomers having a phenolic hydroxy group, such as hydroxystyrene, N-(hydroxyphenyl)methacrylamide, N-(hydroxyphenyl)acrylamide, N-(hydroxyphenyl)maleimide, and N-(hydroxyphenyl)maleimide;

Monomers having an amino group, such as aminoethyl acrylate, aminoethyl methacrylate, aminopropyl acrylate, and aminopropyl methacrylate;

(Meth)acrylamide compounds substituted with hydroxymethyl groups or alkoxymethyl groups, such as N-hydroxymethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide;

Allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, 2-methyl glycidyl methacrylate, α-ethyl glycidyl acrylate, α-n-propyl glycidyl acrylate, α-n-butyl glycidyl acrylate, 3,4-epoxybutyl acrylate, 3,4-epoxybutyl methacrylate, 6,7-epoxyheptyl acrylate, 6,7-epoxyheptyl methacrylate, α-ethyl acrylate-6,7-epoxyheptyl, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, 3,4-epoxycyclohexylmethyl methacrylate, 3-ethenyl-7-oxabicyclo[4.1.0]heptane, 1,2-epoxy-5-hexene, 1,7-octadiene monoepoxide, and other monomers having an epoxy moiety-containing group;

3-(acryloyloxymethyl)oxetane, 3-(acryloyloxymethyl)-2-methyloxetane, 3-(acryloyloxymethyl)-3-ethyloxetane, 3-(acryloyloxymethyl)-2-trifluoromethyloxetane, 3-(acryloyloxymethyl)-2-pentafluoroethyloxetane, 3-(acryloyloxymethyl)-2-phenyloxetane, 3-(acryloyloxymethyl)-2,2-difluorooxetane, 3-(acryloyloxymethyl)-2,2,4-trifluorooxetane, 3-(acryloyloxymethyl)-2,2,4,4-tetrafluorooxetane, 3-(2-acryloyloxyethyl)oxetane acrylic acid esters such as 3-(methacryloyloxyethyl)oxetane, 3-(2-acryloyloxyethyl)-2-ethyloxetane, 3-(2-acryloyloxyethyl)-3-ethyloxetane, 3-(2-acryloyloxyethyl)-2-trifluoromethyloxetane, 3-(2-acryloyloxyethyl)-2-pentafluoroethyloxetane, 3-(2-acryloyloxyethyl)-2-phenyloxetane, 3-(2-acryloyloxyethyl)-2,2-difluorooxetane, 3-(2-acryloyloxyethyl)-2,2,4-trifluorooxetane, and 3-(2-acryloyloxyethyl)-2,2,4,4-tetrafluorooxetane; dimethyl)oxetane, 3-(methacryloyloxymethyl)-2-methyloxetane, 3-(methacryloyloxymethyl)-3-ethyloxetane, 3-(methacryloyloxymethyl)-2-trifluoromethyloxetane, 3-(methacryloyloxymethyl)-2-pentafluoroethyloxetane, 3-(methacryloyloxymethyl)-2-phenyloxetane, 3-(methacryloyloxymethyl)-2,2-difluorooxetane, 3-(methacryloyloxymethyl)-2,2,4-trifluorooxetane, 3-(methacryloyloxymethyl)-2,2,4,4-tetrafluorooxetane, 3-(2-methacryloyloxyethyl)oxetane monomers having an oxetanyl group, such as oxetane, 3-(2-methacryloyloxyethyl)-2-ethyloxetane, 3-(2-methacryloyloxyethyl)-3-ethyloxetane, 3-(2-methacryloyloxyethyl)-2-trifluoromethyloxetane, 3-(2-methacryloyloxyethyl)-2-pentafluoroethyloxetane, 3-(2-methacryloyloxyethyl)-2-phenyloxetane, 3-(2-methacryloyloxyethyl)-2,2-difluorooxetane, 3-(2-methacryloyloxyethyl)-2,2,4-trifluorooxetane, and 3-(2-methacryloyloxyethyl)-2,2,4,4-tetrafluorooxetane;

2,3-epithiopropyl acrylate or methacrylate, and monomers having a thiiranyl group such as 2- or 3- or 4-(β-epithiopropylthiomethyl)styrene, 2- or 3- or 4-(β-epithiopropyloxymethyl)styrene, 2- or 3- or 4-(β-epithiopropylthio)styrene, and 2- or 3- or 4-(β-epithiopropyloxy)styrene;

Monomers having a blocked isocyanate group such as 2-(0-(1'-methylpropylideneamino)carboxyamino)ethyl acrylate, 2-(3,5-dimethylpyrazolyl)carbonylamino)ethyl acrylate, 2-(0-(1'-methylpropylideneamino)carboxyamino)ethyl methacrylate, and 2-(3,5-dimethylpyrazolyl)carbonylamino)ethyl methacrylate; etc. Note that (meth)acrylamide refers to both acrylamide and methacrylamide.

In addition, in the present invention, when obtaining the specific copolymer, in addition to the monomer having a photoalignable group represented by the above formula (a-1-m) and the monomer having a thermal crosslinkable group A and, if necessary, a thermal crosslinkable group B, other monomers copolymerizable with these monomers can be used in combination.

Specific examples of such other monomers include acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds, vinyl compounds, acrylamide compounds such as N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and acrylamide, and monomers having a nitrogen-containing aromatic heterocyclic group and a polymerizable group.

Examples of acrylic acid ester compounds include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthryl methyl acrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, and 8-ethyl-8-tricyclodecyl acrylate.

Examples of methacrylic acid ester compounds include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthryl methyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-propyl-2-adamantyl methacrylate, 8-methyl-8-tricyclodecyl methacrylate, and 8-ethyl-8-tricyclodecyl methacrylate.

Examples of the (meth)acrylic acid amide compounds include acrylamide, methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, etc.

Examples of the vinyl compounds include methyl vinyl ether, benzyl vinyl ether, vinyl naphthalene, vinyl carbazole, allyl glycidyl ether, and 3-ethenyl-7-oxabicyclo[4.1.0]heptane.

Examples of the styrene compounds include styrene, methylstyrene, chlorostyrene, and bromostyrene.

Examples of the maleimide compounds include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

The nitrogen-containing aromatic heterocycle is preferably an aromatic cyclic hydrocarbon having at least one, preferably 1 to 4, structures selected from the group consisting of the following formulas [Na] to [Nb] (wherein _Z2 is a linear or branched alkyl group having 1 to 5 carbon atoms):

Specific examples include an oxazole ring, a thiazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, a 1-pyrazoline ring, an isoquinoline ring, a thiadiazole ring, a pyridazine ring, a triazine ring, a pyrazine ring, a phenanthroline ring, a quinoxaline ring, a benzothiazole ring, an oxadiazole ring, and an acridine ring. Furthermore, the carbon atoms of these nitrogen-containing aromatic heterocycles may have a substituent containing a heteroatom. Among these, an example is a pyridine ring.

Examples of monomers having a nitrogen-containing aromatic heterocyclic group and a polymerizable group include 2-(2-pyridylcarbonyloxy)ethyl (meth)acrylate, 2-(3-pyridylcarbonyloxy)ethyl (meth)acrylate, 2-(4-pyridylcarbonyloxy)ethyl (meth)acrylate, etc.

The other monomers used in the present invention may be used alone or in combination of two or more monomers.

The photoreactive moiety represented by the above formula (pa-1) to be contained in the polymer, which is component (A) of the liquid crystal alignment agent of the present invention, may be used alone or in combination of two or more types.

It is preferable that the photoreactive moiety represented by the above formula (pa-1) is contained in a proportion of 5 to 100 mol%, 10 to 60 mol%, or 15 to 50 mol% of the total repeating units of the polymer component (A).

When the polymer of the present invention contains a thermally crosslinkable group, the portion having the thermally crosslinkable group may be a thermally crosslinkable group A alone, or a combination of two or more portions containing a thermally crosslinkable group A and a thermally crosslinkable group B may be used.

When a site having a thermally crosslinkable group is introduced, the amount introduced is preferably 5 to 95 mol%, 10 to 70 mol%, or 15 to 50 mol% of the total repeating units of the polymer that is component (A).

It is preferable that the content of the structures derived from the above-mentioned other monomers is 0 to 60 mol%, 0 to 40 mol%, or 0 to 20 mol% of the total repeating units of the polymer component (A).

<Method of Producing Specific Polymer>
The specific polymer of the component (A) contained in the liquid crystal aligning agent of the present invention is obtained by copolymerizing a monomer having a photoalignable group represented by the above formula (pa-1), optionally a monomer having the above thermal crosslinkable group A, and optionally a monomer having the above thermal crosslinkable group B. In addition, it can be copolymerized with the other monomers described above.

The method for producing the specific polymer of the component (A) in the present invention is not particularly limited, and a general-purpose method that is used industrially can be used. Specifically, the specific polymer can be produced by cationic polymerization, radical polymerization, or anionic polymerization using the vinyl group of the monomer. Among these, radical polymerization is particularly preferred from the viewpoint of ease of reaction control.
As the polymerization initiator for radical polymerization, known compounds such as radical polymerization initiators and reversible addition-fragmentation chain transfer (RAFT) polymerization agents can be used.

A radical thermal polymerization initiator is a compound that generates radicals when heated above its decomposition temperature. Examples of such radical thermal polymerization initiators include ketone peroxides (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), diacyl peroxides (acetyl peroxide, benzoyl peroxide, etc.), hydroperoxides (hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxy ketals (dibutylperoxycyclohexane, etc.), alkyl peresters (peroxyneodecanoic acid-tert-butyl ester, peroxypivalic acid-tert-butyl ester, peroxy 2-ethylcyclohexanoic acid-tert-amyl ester, etc.), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), and azo compounds (azobisisobutyronitrile, 2,2'-di(2-hydroxyethyl)azobisisobutyronitrile, etc.).

Such radical thermal polymerization initiators can be used alone or in combination of two or more.

The radical photopolymerization initiator is not particularly limited as long as it is a compound that initiates radical polymerization by irradiation with light. Examples of such radical photopolymerization initiators include known compounds such as benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, thioxanthone, and isopropylxanthone. These compounds may be used alone or in combination of two or more.
The radical polymerization method is not particularly limited, and an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a precipitation polymerization method, a bulk polymerization method, a solution polymerization method, etc. can be used.

The solvent used in the polymerization reaction of the specific polymer of component (A) is not particularly limited as long as the generated polymer dissolves in the solvent. Specific examples include the solvents described in the section <Solvent> below, such as N-alkyl-2-pyrrolidones, dialkylimidazolidinones, lactones, carbonates, ketones, the compounds represented by formula (Sv-1) and formula (Sv-2), tetrahydrofuran, 1,4-dioxane, dimethyl sulfone, and dimethyl sulfoxide.
These solvents may be used alone or in combination. Furthermore, even if a solvent does not dissolve the polymer to be produced, it may be mixed with the above-mentioned solvent to the extent that the polymer to be produced does not precipitate.
In addition, since oxygen in a solvent in radical polymerization can inhibit the polymerization reaction, it is preferable to use an organic solvent that has been degassed to the greatest extent possible.

The polymerization temperature during radical polymerization can be selected from any temperature between 30 and 150° C., but is preferably in the range of 50 to 100° C. The reaction can be carried out at any concentration, but the monomer concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stage, and then an organic solvent can be added.
In the above-mentioned radical polymerization reaction, if the ratio of the radical polymerization initiator is high relative to the monomer, the molecular weight of the resulting polymer will be small, and if the ratio is low, the molecular weight of the resulting polymer will be large, so the ratio of the radical initiator is preferably 0.1 to 10 mol% relative to the monomer to be polymerized. In addition, various monomer components, solvents, initiators, etc. can also be added during polymerization.

[Polymer Recovery]
When recovering the polymer generated from the reaction solution obtained by the above-mentioned reaction, the reaction solution may be poured into a poor solvent to precipitate the polymer. Examples of poor solvents used for precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer precipitated by pouring into the poor solvent can be recovered by filtration, and then dried at room temperature or by heating under normal or reduced pressure. In addition, the polymer precipitated and recovered can be redissolved in an organic solvent and the reprecipitation and recovery operation can be repeated two to ten times to reduce impurities in the polymer. Examples of poor solvents in this case include alcohols, ketones, and hydrocarbons. It is preferable to use three or more poor solvents selected from these because the efficiency of purification is further improved.

The molecular weight of the specific polymer of component (A) is preferably a weight average molecular weight of 2,000 to 1,000,000, more preferably 5,000 to 100,000, measured by GPC (Gel Permeation Chromatography), taking into consideration the strength of the resulting coating film, the workability during coating film formation, and the uniformity of the coating film.

<Component (B)>
When the liquid crystal aligning agent used in the present invention satisfies the requirement Z2, it contains a crosslinking agent as the component (B). As the component (B), a crosslinking agent having two or more thermal crosslinkable groups B can be mentioned.

Examples of the crosslinking agent, which is component (B), include low molecular weight compounds such as epoxy compounds, compounds having two or more amino groups, methylol compounds, isocyanate compounds, phenoplast compounds, and blocked isocyanate compounds, as well as polymers such as polymers of N-alkoxymethylacrylamide, polymers of compounds having epoxy groups, and polymers of compounds having isocyanate groups.

Specific examples of the above-mentioned epoxy compounds 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-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

Examples of compounds having two or more amino groups include diamines such as alicyclic diamines, aromatic diamines, aromatic-aliphatic diamines, and aliphatic diamines.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, isophoronediamine, etc.

Examples of aromatic diamines include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,5-diaminotoluene, 1,4-diamino-2-methoxybenzene, 2,5-diamino-p-xylene, and 1,3-diamino-4-chlorobenzene.

Examples of aromatic-aliphatic diamines include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, 4-amino-N-methylbenzylamine, 3-aminophenethylamine, 4-aminophenethylamine, 3-amino-N-methylphenethylamine, 4-amino-N-methylphenethylamine, 3-(3-aminopropyl)aniline, 4-(3-aminopropyl)aniline, 3-(3-methylaminopropyl)aniline, 4-(3-methylaminopropyl)aniline, 3-(4-aminopropyl)aniline, 4 ... Examples of such amines include 4-(4-aminobutyl)aniline, 4-(4-aminobutyl)aniline, 3-(4-methylaminobutyl)aniline, 4-(4-methylaminobutyl)aniline, 3-(5-aminopentyl)aniline, 4-(5-aminopentyl)aniline, 3-(5-methylaminopentyl)aniline, 4-(5-methylaminopentyl)aniline, 2-(6-aminonaphthyl)methylamine, 3-(6-aminonaphthyl)methylamine, 2-(6-aminonaphthyl)ethylamine, and 3-(6-aminonaphthyl)ethylamine.

Examples of aliphatic diamines include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-dimethylhexane, 1,7-diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, and 1,9-diamino-5-methylheptane.

Specific examples of methylol compounds include compounds such as alkoxymethylated glycoluril, alkoxymethylated benzoguanamine, and alkoxymethylated melamine.

Specific examples of alkoxymethylated glycoluril include 1,3,4,6-tetrakis(methoxymethyl)glycoluril, 1,3,4,6-tetrakis(butoxymethyl)glycoluril, 1,3,4,6-tetrakis(hydroxymethyl)glycoluril, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-tetrakis(butoxymethyl)urea, 1,1,3,3-tetrakis(methoxymethyl)urea, 1,3-bis(hydroxymethyl)-4,5-dihydroxy-2-imidazolinone, and 1,3-bis(methoxymethyl)-4,5-dimethoxy-2-imidazolinone. Commercially available products include glycoluril compounds manufactured by Mitsui Cytec Co., Ltd. (product names: Cymel (registered trademark) 1170, Powderlink (registered trademark) 1174), methylated urea resins (product names: UFR (registered trademark) 65), butylated urea resins (product names: UFR (registered trademark) 300, U-VAN10S60, U-VAN10R, U-VAN11HV), and urea/formaldehyde resins (high condensation type, product names: Beckamin (registered trademark) J-300S, P-955, and N) manufactured by DIC Corporation.

Specific examples of alkoxymethylated benzoguanamine include tetramethoxymethylbenzoguanamine, etc. Commercially available products include those manufactured by Mitsui Cytec Co., Ltd. (product name: Cymel (registered trademark) 1123) and those manufactured by Sanwa Chemical Co., Ltd. (product names: Nikalac (registered trademark) BX-4000, BX-37, BL-60, and BX-55H).

Specific examples of alkoxymethylated melamine include hexamethoxymethylmelamine. Commercially available products include methoxymethyl type melamine compounds manufactured by Mitsui Cytec Co., Ltd. (product names: Cymel (registered trademark) 300, 301, 303, and 350), butoxymethyl type melamine compounds (product names: Mycoat (registered trademark) 506 and 508), methoxymethyl type melamine compounds manufactured by Sanwa Chemical Co., Ltd. (product names: Nikalac (registered trademark) MW-30, MW-22, MW-11, MS-001, MX-002, MX-730, MX-750, and MX-035), and butoxymethyl type melamine compounds (product names: Nikalac (registered trademark) MX-45, MX-410, and MX-302).

It may also be a compound obtained by condensing a melamine compound, a urea compound, a glycoluril compound, and a benzoguanamine compound in which the hydrogen atom of the amino group is substituted with a methylol group or an alkoxymethyl group. For example, a high molecular weight compound produced from a melamine compound and a benzoguanamine compound described in U.S. Pat. No. 6,323,310 may be mentioned. Commercially available products of the melamine compound include the product name: Cymel (registered trademark) 303 (manufactured by Mitsui Cytec Co., Ltd.), and commercially available products of the benzoguanamine compound include the product name: Cymel (registered trademark) 1123 (manufactured by Mitsui Cytec Co., Ltd.).

Specific examples of isocyanate compounds include VESTANAT B1358/100, VESTAGON BF 1540 (both are isocyanurate-type modified polyisocyanates, manufactured by Degussa Japan Co., Ltd.), Takenate (registered trademark) B-882N, Takenate B-7075 (both are isocyanurate-type modified polyisocyanates, manufactured by Mitsui Chemicals, Inc.), etc.

Specific examples of phenoplast compounds include the following compounds, but phenoplast compounds are not limited to the following compound examples.

Specific examples of compounds having two or more hydroxyalkylamide groups at the molecular end include the following compounds, Primid XL-552, and Primid SF-4510.

Examples of blocked isocyanate compounds include Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate MS-50 (all manufactured by Nippon Polyurethane Industry Co., Ltd.), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (all manufactured by Mitsui Chemicals, Inc.), etc.

Furthermore, examples of the above-mentioned N-alkoxymethylacrylamide polymers include polymers produced using acrylamide compounds or methacrylamide compounds substituted with hydroxymethyl groups or alkoxymethyl groups, such as N-hydroxymethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide.

Specific examples of such polymers include poly(N-butoxymethylacrylamide), a copolymer of N-butoxymethylacrylamide and styrene, a copolymer of N-hydroxymethylmethacrylamide and methyl methacrylate, a copolymer of N-ethoxymethylmethacrylamide and benzyl methacrylate, and a copolymer of N-butoxymethylacrylamide, benzyl methacrylate, and 2-hydroxypropyl methacrylate. The weight average molecular weight of such polymers is 1,000 to 200,000, more preferably 3,000 to 150,000, and even more preferably 3,000 to 50,000.

Examples of polymers of compounds having epoxy groups include polymers produced using compounds having epoxy groups such as glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, and 3,4-epoxycyclohexylmethyl methacrylate.

Specific examples of such polymers include poly(3,4-epoxycyclohexylmethyl methacrylate), poly(glycidyl methacrylate), a copolymer of glycidyl methacrylate and methyl methacrylate, a copolymer of 3,4-epoxycyclohexylmethyl methacrylate and methyl methacrylate, a copolymer of glycidyl methacrylate and styrene, etc. The weight average molecular weight of such polymers is 1,000 to 200,000, more preferably 3,000 to 150,000, and even more preferably 3,000 to 50,000.

Examples of polymers of compounds having an isocyanate group as described above include polymers produced using compounds having an isocyanate group such as 2-isocyanatoethyl methacrylate (Karenz MOI [registered trademark], manufactured by Showa Denko K.K.) and 2-isocyanatoethyl acrylate (Karenz AOI [registered trademark], manufactured by Showa Denko K.K.), or compounds having a blocked isocyanate group such as 2-(0-[1'-methylpropylideneamino]carboxyamino)ethyl methacrylate (Karenz MOI-BM [registered trademark], manufactured by Showa Denko K.K.) and 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate (Karenz MOI-BP [registered trademark], manufactured by Showa Denko K.K.).

Specific examples of such polymers include poly(2-isocyanatoethyl acrylate), poly(2-(0-[1'-methylpropylideneamino]carboxyamino)ethyl methacrylate), a copolymer of 2-isocyanatoethyl methacrylate and styrene, and a copolymer of 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate and methyl methacrylate. The weight average molecular weight of such polymers is 1,000 to 200,000, more preferably 3,000 to 150,000, and even more preferably 3,000 to 50,000.

These crosslinking agents can be used alone or in combination of two or more.

When the liquid crystal alignment agent used in the present invention contains a crosslinking agent (B), the content is preferably 1 to 100 parts by mass based on 100 parts by mass of the resin (A), and more preferably 1 to 80 parts by mass.

[Preparation of liquid crystal alignment agent]
The liquid crystal alignment agent used in the present invention is preferably prepared as a coating liquid suitable for forming a liquid crystal alignment film. That is, the liquid crystal alignment agent of the present invention is preferably prepared as a solution in which a resin component for forming a resin coating is dissolved in an organic solvent. Here, the resin components are the specific polymer of component (A) and the polymer of component (B) already explained. In this case, the total content of the specific polymer of component (A) and the polymer of component (B) is preferably 0.5 to 20% by mass, more preferably 1 to 20% by mass, even more preferably 1 to 15% by mass, and particularly preferably 1 to 10% by mass, based on the entire liquid crystal alignment agent.

<Component (C)>
The liquid crystal alignment agent of the present invention can contain, as component (C), a polymer selected from polyimides and their precursors, which has at least one group selected from a vertical alignment group and a tertiary-butoxycarbonyl group, or is chemically imidized.

By containing the polymer component (C), the liquid crystal alignment agent of the present invention can further improve electrical properties such as increased voltage retention rate and suppression of residual charge accumulation.

The polymer of component (C) is a polyimide and its precursor (hereinafter also referred to as the polyimide component), and has a surface energy close to that of the polymer of component (A). Acrylic components such as component (A) are basically low in polarity and low in surface energy. On the other hand, polyimide components have high polarity and high surface energy. However, if the difference in surface energy between these two components is too large, they may not be compatible and may aggregate, resulting in an uneven film, or the process margin may be narrowed due to repelling or unevenness. Therefore, by lowering the polarity of the polyimide component, the surface energy can be controlled to a value that is higher than that of the acrylic component, but with a small difference. Methods for lowering the polarity of the polyimide component include mixing it with component (A) after chemical imidization, and introducing a side chain.

Examples of such polymers include polymers obtained by polymerizing a tetracarboxylic acid derivative such as a known tetracarboxylic acid dianhydride with a known diamine and then chemically imidizing the polymer, polyimide precursors obtained by using diamines having side chains, polyimides obtained by imidizing the polyimide precursors, polyimide precursors obtained by using diamines having tertiary butoxycarbonyloxy groups, polyimides obtained by imidizing the polyimide precursors, and the like. By using such side chains or chemical imidization, the surface energy can be made closer to that of the acrylic polymer, which is the component (A), so that when a liquid crystal alignment agent is applied and baked to form a cured film, no aggregation or the like occurs, and a flat cured film can be obtained. Examples of diamines having side chains include diamines represented by formulas (2), (3), (4), and (5) described in paragraphs [0023] to [0039] of International Patent Application Publication WO2016/125870, and specific examples thereof represented by formulas [A-1] to [A-32]. Examples of diamines having a tertiary-butoxycarbonyloxy group include diamines having structures of formulas [A-1], [A-2], and [A-3] described in paragraphs [0011] to [0034] of International Patent Application Publication WO2017/119461, and diamines exemplified as specific examples thereof.

When the liquid crystal aligning agent of the present invention contains a polymer as component (C), the content ratio of component (A):component (C) is preferably a mass ratio of 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 60:40.

<Solvent>
The solvent contained in the liquid crystal alignment agent used in the present invention is not particularly limited as long as it is a solvent that dissolves the (A) component, the (B) component if necessary, and the (C) component if necessary. The solvent contained in the liquid crystal alignment agent may be one type, or two or more types may be mixed and used. In addition, even if the solvent does not dissolve the (A) component or the (B) component, it can be used in combination with a solvent that dissolves the (A) component or the (B) component. In this case, it is preferable that the surface energy of the solvent that does not dissolve the (A) component or the (B) component is lower than the solvent that dissolves the (A) component or the (B) component, because the liquid crystal alignment agent can be applied to the substrate with good properties.

Specific examples include water, N-alkyl-2-pyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, dialkylimidazolidinones such as 1,3-dimethyl-2-imidazolidinone, lactones such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone, carbonates such as ethylene carbonate and propylene carbonate, methanol, ethanol, propanol, isopropanol, 3-methyl-3-methanol, Examples of the ketones include xybutanol, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, isoamyl methyl ketone, methyl isopropyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, and 4-hydroxy-4-methyl-2-pentanone; the compounds represented by the following formula (Sv-1) and the compounds represented by the following formula (Sv-2); 4-methyl-2-pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, 2-methylcyclohexyl acetate, butyl butyrate, isoamyl butyrate, diisobutyl carbinol, and diisopentyl ether.

In formulas (Sv-1) to (Sv-2), Y ₁ and Y ₂ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, X ₁ is an oxygen atom or -COO-, X2 is a single bond or a carbonyl group, and R ₁ is an alkanediyl group having 2 to 4 carbon atoms. n ₁ is an integer of 1 to 3. When n ₁ is 2 or 3, multiple R _1s may be the same or different. Z ₁ is a divalent hydrocarbon group having 1 to 6 carbon atoms, and Y ₃ and Y ₄ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms.

In formula (Sv-1), examples of the monovalent hydrocarbon group having 1 to 6 carbon atoms for _Y1 and _Y2 include a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, a monovalent alicyclic hydrocarbon group having 1 to 6 carbon atoms, and a monovalent aromatic hydrocarbon group having 1 to 6 carbon atoms. Examples of the monovalent chain hydrocarbon group having 1 to 6 carbon atoms include an alkyl group having 1 to 6 carbon atoms. The alkanediyl group for _R1 may be linear or branched.

In formula (Sv-2), examples of the divalent hydrocarbon group having 1 to 6 carbon atoms for Z ₁ include an alkanediyl group having 1 to 6 carbon atoms.
Examples of the monovalent hydrocarbon group having 1 to 6 carbon atoms for _Y3 and _Y4 include a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, a monovalent alicyclic hydrocarbon group having 1 to 6 carbon atoms, and a monovalent aromatic hydrocarbon group having 1 to 6 carbon atoms. Examples of the monovalent chain hydrocarbon group having 1 to 6 carbon atoms include an alkyl group having 1 to 6 carbon atoms.

Specific examples of the solvent represented by formula (Sv-1) include, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, ethylene glycol monoacetate, ethylene glycol diacetate, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, propylene glycol diacetate, ethylene glycol, 1,4-butanediol, 3-methoxybutyl acetate, and 3-ethoxybutyl acetate;
Specific examples of the solvent represented by (Sv-2) include methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate, butyl lactate, isoamyl lactate, ethyl-3-ethoxypropionate, methyl-3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, and butyl 3-methoxypropionate.

The solvent preferably has a boiling point of 80 to 200° C., more preferably 80 to 180° C., and examples of preferred solvents include N,N-dimethylformamide, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, propanol, isopropanol, 3-methyl-3-methoxybutanol, ethyl amyl ketone, methyl ethyl ketone, isoamyl methyl ketone, methyl isopropyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, 4-hydroxy-4-methyl-2-pentanone, 4-methyl-2-pentyl acetate, 2-ethylbutyl acetate, cyclohexyl acetate, 2-methylcyclohexyl acetate, butyl butyrate, and butyl ether. Examples of the lactate include isoamyl lactate, diisobutyl carbinol, diisopentyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol monoacetate, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, 3-methoxybutyl acetate, methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate, butyl lactate, isoamyl lactate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, and ethyl 3-methoxypropionate.
The boiling point being in this range is particularly preferred when the liquid crystal aligning agent containing the solvent is applied onto a plastic substrate, which will be described later.

<Other Ingredients>
The liquid crystal aligning agent used in the present invention may contain other components other than the above-mentioned (A) component, if necessary (B) component, and if necessary (C) component. Examples of such other components include, but are not limited to, a crosslinking catalyst, a compound that improves the film thickness uniformity and surface smoothness when the liquid crystal aligning agent is applied, a compound that improves the adhesion between the liquid crystal alignment film and the substrate, and the like.

<Crosslinking catalyst>
A crosslinking catalyst may be added to the liquid crystal aligning agent used in the present invention for the purpose of promoting the reaction between the thermally crosslinkable group A and the thermally crosslinkable group B. Examples of such crosslinking catalysts include sulfonic acids such as p-toluenesulfonic acid, camphorsulfonic acid, trifluoromethanesulfonic acid, p-phenolsulfonic acid, 2-naphthalenesulfonic acid, mesitylenesulfonic acid, p-xylene-2-sulfonic acid, m-xylene-2-sulfonic acid, 4-ethylbenzenesulfonic acid, 1H,1H,2H,2H-perfluorooctane sulfonic acid, perfluoro(2-ethoxyethane)sulfonic acid, pentafluoroethanesulfonic acid, nonafluorobutane-1-sulfonic acid, and dodecylbenzenesulfonic acid, or hydrates or salts thereof. Examples of the compound that generates an acid when heated include bis(tosyloxy)ethane, bis(tosyloxy)propane, bis(tosyloxy)butane, p-nitrobenzyl tosylate, o-nitrobenzyl tosylate, 1,2,3-phenylene tris(methylsulfonate), p-toluenesulfonic acid pyridinium salt, p-toluenesulfonic acid morphonium salt, p-toluenesulfonic acid ethyl ester, p-toluenesulfonic acid propyl ester, p-toluenesulfonic acid butyl ester, p-toluenesulfonic acid isobutyl ester, p-toluenesulfonic acid methyl ester, p-toluenesulfonic acid phenethyl ester, cyanomethyl p-toluenesulfonate, 2,2,2-trifluoroethyl p-toluenesulfonate, 2-hydroxybutyl p-toluenesulfonate, and N-ethyl-p-toluenesulfonamide.

[Compounds that improve film thickness uniformity and surface smoothness]
Compounds that improve the uniformity of the film thickness and the surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
Specific examples include EFTOP (registered trademark) 301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), MEGAFAC (registered trademark) F171, F173, R-30 (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), ASAHIGUARD (registered trademark) AG710 (manufactured by Asahi Glass Co., Ltd.), SURFLOON (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC Seimi Chemical Co., Ltd.), and the like.
The proportion of these surfactants used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of the resin component contained in the polymer composition.

[Compound for improving adhesion between liquid crystal alignment film and substrate]
Specific examples of compounds that improve 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-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine , 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, and N-bis(oxyethylene)-3-aminopropyltriethoxysilane, and other amino-based silane-containing compounds.

When a compound that improves adhesion to the substrate is used, the amount used is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the resin component contained in the polymer composition.

In some embodiments, a photosensitizer can be used as an additive to improve the photoreactivity of the photoalignment group. Specific examples include aromatic 2-hydroxyketones (benzophenones), coumarins, ketocoumarins, carbonyl biscoumarins, acetophenones, anthraquinones, xanthones, thioxanthones, and acetophenone ketals.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal alignment agent of the present invention can be applied to a substrate, baked, and then subjected to an alignment treatment such as rubbing or light irradiation to form a liquid crystal alignment film, or in some vertical alignment applications, no alignment treatment can be performed. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; polyethylene terephthalate, polybutylene terephthalate, polypropylene, polystyrene, polyethersulfone, polycarbonate, poly(alicyclic olefin), polyvinyl chloride, polyvinylidene chloride, polyetheretherketone (PEEK) resin film, polysulfone (PSF), polyethersulfone (PES), polyamide, polyimide, acrylic, triacetyl cellulose, or other plastics can be used.
The transparent conductive film provided on one side of the substrate may be a NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), or the like.

<Coating film formation process>
The method of applying the liquid crystal alignment agent of the present invention is not particularly limited, and may be screen printing, flexographic printing, offset printing, inkjet, dip coating, roll coating, slit coating, spin coating, etc., which may be used depending on the purpose. After applying the agent to a substrate by these methods, the solvent is evaporated by a heating means such as a hot plate to form a coating film.

The baking after coating the liquid crystal alignment agent can be carried out at any temperature between 40 and 300°C, preferably between 40 and 250°C, and more preferably between 40 and 230°C.
The thickness of the coating film formed on the substrate is preferably 5 to 1,000 nm, more preferably 10 to 500 nm or 10 to 300 nm. This baking can be carried out using a hot plate, a hot air circulating oven, an infrared oven, or the like.
For the rubbing treatment, a rayon cloth, a nylon cloth, a cotton cloth, or the like can be used.

<Light irradiation process>
In one embodiment, an alignment treatment by light irradiation may be performed, and may include, for example, a step of applying the above-mentioned liquid crystal alignment agent onto a substrate to form a coating film, and a step of irradiating the coating film with light while the coating film is not in contact with the liquid crystal layer or while the coating film is in contact with the liquid crystal layer.

Examples of light to be irradiated in the alignment treatment by photoirradiation include ultraviolet light containing light with a wavelength of 150 to 800 nm, visible light, etc. Of these, ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. The irradiated light may be polarized or unpolarized. As the polarized light, it is preferable to use light containing linearly polarized light.

When the light used is polarized light, the light may be irradiated from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When the light used is non-polarized light, the light is preferably irradiated from an oblique direction relative to the substrate surface.
The amount of light irradiation is preferably 0.1 mJ/cm ² or more and less than 1,000 mJ/cm ² , more preferably 1 to 500 mJ/cm ² , and even more preferably 2 to 200 mJ/cm ² .

The liquid crystal display element of the present invention can be produced by a normal method, and the production method is not particularly limited. The pair of substrates face each other with an appropriate gap between them, and it is preferable to place a spacer between the substrates in order to make the thickness of the liquid crystal sandwiched between the substrates uniform. As the spacer, a known spacer material such as a conventional dispersed spacer or a spacer formed from a photosensitive spacer forming composition can be used, and it is also possible to use unevenness formed in a layer made of a liquid crystal cured product as a spacer.

<Liquid crystal clamping process>
There are two methods for constructing a liquid crystal cell by sandwiching liquid crystal between substrates, for example: In the first method, a pair of substrates are arranged opposite each other with a gap (cell gap) between them so that the liquid crystal alignment films face each other, the peripheries of the pair of substrates are bonded together using a sealant, liquid crystal is injected and filled on the substrate surfaces and in the cell gap defined by a suitable sealant, and then the injection hole is sealed to produce a liquid crystal cell.

A second method is to manufacture a liquid crystal cell by applying, for example, an ultraviolet light-curable sealant to a predetermined location on one of the two substrates on which a liquid crystal alignment film has been formed, and then dripping liquid crystal onto several predetermined locations on the liquid crystal alignment film surface, and then bonding the other substrate so that the liquid crystal alignment film faces the other substrate and spreading the liquid crystal over the entire surface of the substrate, and then irradiating the entire surface of the substrate with ultraviolet light to cure the sealant (ODF (One Drop Fill) method).

As the liquid crystal, a fluorine-based liquid crystal or a cyano-based liquid crystal having positive or negative dielectric anisotropy may be used depending on the application, or a liquid crystal compound or liquid crystal composition that is polymerized by at least one of heating and light irradiation (hereinafter also referred to as a polymerizable liquid crystal or a curable liquid crystal composition).
In one embodiment, the step of forming a coating film of the liquid crystal alignment agent may be performed by a roll-to-roll process, which simplifies the manufacturing process of the liquid crystal display element and reduces the manufacturing cost.
Then, polarizing plates are attached to both outer surfaces of the liquid crystal cell to obtain a liquid crystal display element.

Examples of polarizing plates used on the outside of a liquid crystal cell include a polarizing plate in which a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine is sandwiched between cellulose acetate protective films, or a polarizing plate made of an H film itself.
The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention as described above has good liquid crystal alignment properties, is excellent in pretilt angle expression ability, and has high reliability. Moreover, the liquid crystal display element produced by the method of the present invention has excellent display characteristics.

The abbreviations used in the examples are as follows.
<Methacrylic monomer>
(Photo-alignable monomer)

MA-1 to MA-7 are novel compounds not yet disclosed in the literature, and their synthesis methods are described in detail in the following Monomer Synthesis Examples 1 to 7.
MA-8 was synthesized by the synthesis method described in patent document (WO-2017115790).
MA-9 was synthesized by the synthesis method described in patent document (WO-2017115790).

The abbreviations for the organic solvents used in the examples are as follows.
NMP: N-methyl-2-pyrrolidone.
BCS: Butyl cellosolve.
THF: tetrahydrofuran.
DMAc: N,N-dimethylacetamide.
PhMe: toluene.
_CHCl2 : methylene chloride.
MeCN: acetonitrile.

< ^1H NMR Measurement>
Apparatus: Fourier transform type superconducting nuclear magnetic resonance apparatus (FT-NMR) "AVANCE III" (manufactured by BRUKER) 500 MHz.
Solvent: deuterated chloroform (CDCl ₃ ) or deuterated N,N-dimethylsulfoxide ([D ₆ ]-DMSO).
Standard substance: tetramethylsilane (TMS).

(Polar Monomer)
MAA: methacrylic acid

(Crosslinking Monomer)
GMA: glycidyl methacrylate

(Isocyanate Monomer)
MOI-BP: 2-[(3,5-dimethyl-1-pyrazolyl)carbonylamino]ethyl methacrylate

<Tetracarboxylic acid dianhydride monomer>
A1: Tetracarboxylic dianhydride represented by the following formula [A1] A2: Tetracarboxylic dianhydride represented by the following formula [A2] A3: Tetracarboxylic dianhydride represented by the following formula [A3] A4: Tetracarboxylic dianhydride represented by the following formula [A4] A5: Tetracarboxylic dianhydride represented by the following formula [A5] A6: Tetracarboxylic dianhydride represented by the following formula [A6] A7: Tetracarboxylic dianhydride represented by the following formula [A7] A8: Tetracarboxylic dianhydride represented by the following formula [A8]

<Side Chain Diamine Monomer>
B1: Side chain diamine monomer represented by the following formula [B1] B2: Side chain diamine monomer represented by the following formula [B2] B3: Side chain diamine monomer represented by the following formula [B3] B4: Side chain diamine monomer represented by the following formula [B4] B5: Side chain diamine monomer represented by the following formula [B5] B6: Side chain diamine monomer represented by the following formula [B6] B7: Side chain diamine monomer represented by the following formula [B7] B8: Side chain diamine monomer represented by the following formula [B8] B9: Side chain diamine monomer represented by the following formula [B9] B10: Side chain diamine monomer represented by the following formula [B10] B11: Side chain diamine monomer represented by the following formula [B11] B12: Side chain diamine monomer represented by the following formula [B12] B13: Side chain diamine monomer represented by the following formula [B13] B14: Side chain diamine monomer represented by the following formula [B14]

<Other diamine monomers>
C1: Other diamine monomer represented by the following formula [C1] C2: Other diamine monomer represented by the following formula [C2] C3: Other diamine monomer represented by the following formula [C3] C4: Other diamine monomer represented by the following formula [C4] C5: Other diamine monomer represented by the following formula [C5] C6: Other diamine monomer represented by the following formula [C6] C7: Other diamine monomer represented by the following formula [C7] C8: Other diamine monomer represented by the following formula [C8] C9: Other diamine monomer represented by the following formula [C9] C10: Other diamine monomer represented by the following formula [C10] C11: Other diamine monomer represented by the following formula [ C11] other diamine monomers C12: other diamine monomers represented by the following formula [C12] C13: other diamine monomers represented by the following formula [C13] C14: other diamine monomers represented by the following formula [C14] C15: other diamine monomers represented by the following formula [C15] C16: other diamine monomers represented by the following formula [C16] C17: other diamine monomers represented by the following formula [C17] C18: other diamine monomers represented by the following formula [C18] C19: other diamine monomers represented by the following formula [C19] C20: other diamine monomers represented by the following formula [C20]

(Crosslinking Agent Component)
D1: Crosslinking agent component represented by the following formula [D1] D2: Crosslinking agent component represented by the following formula [D2] D3: Crosslinking agent component represented by the following formula [D3]

The abbreviations of the reagents used in this example are as follows:
(Polymerization initiator)
AIBN: Azobisisobutyronitrile (solvent)
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve THF: Tetrahydrofuran DMF: N,N-dimethylformamide

(Molecular Weight Measurement)
The molecular weight of the polymer in the synthesis examples was measured as follows using a room temperature gel permeation chromatography (GPC) apparatus (SSC-7200) manufactured by Senshu Scientific Co., Ltd. and columns (KD-803, KD-805) manufactured by Shodex Co., Ltd.
Column temperature: 50°C, eluent: DMF (additives: lithium bromide hydrate (LiBr.H ₂ O) 30 mmol/L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, THF 10 ml/L), flow rate: 1.0 ml/min. Standard samples for creating calibration curves: TSK standard polyethylene oxide (molecular weights approximately 9000,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weights approximately 12,000, 4,000, 1,000) manufactured by Polymer Laboratory.

(Imidization rate measurement)
The imidization rate in the synthesis example was measured as follows. 20 mg of polyimide powder was placed in an NMR sample tube (Kusano Scientific NMR Sampling Tube Standard φ5), 1.0 ml of deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS mixture) was added, and ultrasonic waves were applied to completely dissolve the powder. This solution was measured for proton NMR at 500 MHz using a JEOL Datum NMR analyzer (JNW-ECA500). The imidization rate was calculated by the following formula, using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integrated value of this proton and the proton peak integrated value derived from the NH group of the amic acid that appears around 9.5 to 10.0 ppm. In the following formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the peak of the reference proton, and α is the ratio of the number of the reference protons to one proton of the NH group of the amic acid in the case of polyamic acid (imidization rate 0%).
Imidization rate (%)=(1−α·x/y)×100

(Monomer Synthesis Example 1)
Synthesis of [MA-1]:

A 2L four-neck flask was charged with trans-4-(4-bromophenyl)cyclohexanol (190.0 g, 740 mmol), tert-butyl acrylate (114.2 g, 890 mmol), tripropylamine (264.9 g, 1850 mmol), and PhMe (950 g). After nitrogen replacement, palladium (II) acetate (3.3 g, 15 mmol) and tri(o-tolyl)phosphine (9.0 g, 30 mmol) were charged and stirred at 100°C. After the reaction was completed, the reaction solution was poured into a 0.5N aqueous hydrochloric acid solution (500 g), extracted, and the organic layer was washed with pure water (1000 g) and concentrated. Hexane (1000 g) was added to the obtained crude product, and the mixture was repulped and washed at 0°C to obtain 169.8 g of [MA-1-1].

[MA-1-1] (50.0 g, 137 mmol), 4,4,4-trifluorobutyric acid (26.4 g, 186 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (48.9 g, 254 mmol), 4-dimethylaminopyridine (2.1 g, 17 mmol), and THF (500 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (2500 g) and the precipitate was filtered off. Ethyl acetate (1500 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (1500 g) and concentrated. Hexane (300 g) was added to the obtained crude product and repulp washed at room temperature to obtain 58.5 g of [MA-1-2].

[MA-1-2] (58.5 g, 137 mmol) and formic acid (590 g) were charged into a 1 L four-neck flask and stirred at 50°C. After the reaction was completed, the reaction solution was poured into pure water (3000 g) and the precipitate was filtered off. Acetonitrile (500 g) was added to the obtained crude product and repulped at room temperature to obtain 46.9 g of [MA-1-3].

[MA-1-3] (46.9 g, 127 mmol), 2-hydroxyethyl methacrylate (18.1 g, 139 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (36.4 g, 190 mmol), 4-dimethylaminopyridine (1.5 g, 13 mmol), and THF (470 g) were charged into a 1 L four-neck flask and stirred at room temperature. After completion of the reaction, the reaction solution was concentrated, ethyl acetate (500 g) was poured into the resulting residue, and the organic layer was washed with pure water (1500 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate/hexane (volume ratio 1:3) solution, and further, hexane (400 g) was added to the obtained crude product and repulp washed at room temperature to obtain 55.2 g of [MA-1] (white solid). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the target [MA-1].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ 7.62-7.65 (m,3H), 7.30-7.31 (d,2H), 6.59-6.62 (d,1H), 6.04 (s,1H), 5.70 (s,1H), 4.73-4.78 (m,1H), 4.40-4.42 (m,2H), 4.36-4.37 (m,2H), 2.52-2.60 (m,5H), 1.99-2.02 (d,2H), 1.88 (s,3H), 1.81-1.84 (d,2H), 1.56-1.62 (m,2H), 1.47-1.53 (m,2H).

(Monomer Synthesis Example 2)
Synthesis of [MA-2]:

4-Bromo-4'-hydroxybiphenyl (99.6 g, 400 mmol), tert-butyl acrylate (102.5 g, 800 mmol), tripropylamine (143.3 g, 1000 mmol), and DMAc (500 g) were charged into a 2 L four-neck flask, and after nitrogen replacement, palladium (II) acetate (3.6 g, 16 mmol) and tri(o-tolyl)phosphine (9.7 g, 32 mmol) were charged and stirred at 100 ° C. After the reaction was completed, the reaction solution was poured into a 0.5 N-hydrochloric acid aqueous solution (1000 g), extracted with ethyl acetate (2500 g), and the organic layer was washed with pure water (2000 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate / hexane (volume ratio 1:3), and further, hexane (500 g) was added to the obtained crude product and repulp washed at room temperature, obtaining 112.9 g of [MA-2-1].

[MA-2-1] (32.8 g, 110 mmol), 4,4,4-trifluorobutyric acid (17.3 g, 122 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (31.9 g, 166 mmol), 4-dimethylaminopyridine (1.4 g, 11 mmol), and THF (330 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (2000 g) and the precipitate was filtered off. Ethyl acetate (600 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (1500 g) and concentrated. Hexane (200 g) was added to the obtained crude product and repulp washed at room temperature to obtain 43.8 g of [MA-2-2].

[MA-2-2] (43.8 g, 104 mmol) and formic acid (440 g) were charged into a 2 L four-neck flask and stirred at 50°C. After the reaction was completed, the reaction solution was poured into pure water (2500 g) and the precipitate was filtered off. Acetonitrile (400 g) was added to the obtained crude product and repulped at room temperature to obtain 35.9 g of [MA-2-3].

[MA-2-3] (35.9 g, 99 mmol), 2-hydroxyethyl methacrylate (14.1 g, 109 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (28.4 g, 148 mmol), 4-dimethylaminopyridine (1.2 g, 10 mmol), and THF (360 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (2000 g) and the precipitate was filtered off. Ethyl acetate (1500 g) was added to the obtained crude product to completely dissolve it, and then the organic layer was washed with pure water (3000 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate/hexane (volume ratio 1:2) solution, and further, hexane (200 g) was added to the obtained crude product and repulp washed at room temperature to obtain 40.9 g of [MA-2] (white solid). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the desired [MA-2].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ 7.83-7.84 (d,2H), 7.78-7.80 (d,2H), 7.71-7.75 (m,3H), 7.24-7.26 (d,2H), 6.71-6.74 (d,1H), 6.06 (s,1H), 5.71 (s,1H), 4.43-4.45 (m,2H), 4.38-4.39 (m,2H), 2.90-2.93 (t,2H), 2.67-2.73 (m,2H), 1.89 (s,3H).

(Monomer Synthesis Example 3)
Synthesis of [MA-3]:

A 1L four-neck flask was charged with tert-butyl 4-hydroxybenzoate (24.3 g, 125 mmol), 4,4,4-trifluorobutyric acid (19.5 g, 138 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (36.0 g, 188 mmol), 4-dimethylaminopyridine (1.5 g, 13 mmol), and THF (240 g), and stirred at room temperature. After completion of the reaction, the reaction system was poured into ethyl acetate (300 g), and the organic layer was washed with pure water (900 g) and concentrated. Hexane (400 g) was added to the obtained crude product, and the mixture was repulped and washed at 0°C to obtain 35.9 g of [MA-3-1].

[MA-3-1] (35.9 g, 113 mmol) and formic acid (360 g) were charged into a 1 L four-neck flask and stirred at 50° C. After the reaction was completed, the reaction solution was poured into pure water (2000 g), and the precipitate was filtered off and dried to obtain 27.8 g of [MA-3-2].

[MA-3-2] (27.8 g, 106 mmol), trans-p-tert-butyl coumarate (32.6 g, 148 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (30.4 g, 159 mmol), 4-dimethylaminopyridine (1.3 g, 11 mmol), and THF (280 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (2500 g) and the precipitate was filtered off. Ethyl acetate (2500 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (3000 g) and concentrated. Isopropyl alcohol (80 g) was added to the obtained crude product and recrystallized to obtain 16.9 g of [MA-3-3].

[MA-3-3] (16.9 g, 36 mmol) and formic acid (170 g) were placed in a 1 L four-neck flask and stirred at 50°C. After the reaction was completed, the reaction solution was poured into pure water (2000 g) and the precipitate was filtered off. Acetonitrile (400 g) was added to the obtained crude product and heated to 60°C to dissolve, after which the insoluble matter was removed and the product was concentrated. Furthermore, ethyl acetate (40 g) and hexane (400 g) were added to the crude product and repulped and washed at room temperature to obtain 8.1 g of [MA-3-4].

[MA-3-4] (7.8 g, 19 mmol), oxalyl chloride (2.7 g, 21 mmol), DMF (several drops), and THF (60 g) were charged into a 200 mL four-neck flask, and the mixture was reacted at 0 ° C for 2 h. Subsequently, the obtained acid chloride was dropped in an ice bath into a reaction solution charged with 2-hydroxyethyl methacrylate (2.7 g, 21 mmol), pyridine (2.1 g, 27 mmol), and THF (23 g), and the mixture was stirred at 50 ° C. After the reaction was completed, the reaction system was poured into ethyl acetate (500 g), and the organic layer was washed with pure water (1500 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate / hexane (volume ratio 1:5) solution, and further, hexane (50 g) was added to the obtained crude product, and the mixture was heated to 50 ° C. to dissolve it, and then the insoluble matter was removed and concentrated. Next, methanol (60 g) was added to the crude product, and the product was recrystallized at −20° C. to obtain 1.3 g of [MA-3] (white solid). The results of ¹ H-NMR of the target product are shown below. From these results, it was confirmed that the obtained solid was the target [MA-3].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ 8.21-8.22 (d,2H), 7.85-7.87 (d,2H), 7.70-7.74 (d,1H), 7.36-7.41 (m,4H), 6.68-6.71 (d,1H), 6.05 (s,1H), 5.71 (s,1H), 4.43-4.44 (m,2H), 4.37-4.39 (m,2H), 2.93-2.96 (t,2H), 2.67-2.74 (m,2H), 1.89 (s,3H).

(Monomer Synthesis Example 4)
Synthesis of [MA-4]:

[MA-1-1] (20.0 g, 66 mmol), 3,3,3-trifluoropropionic acid (9.5 g, 74 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (19.4 g, 101 mmol), 4-dimethylaminopyridine (0.8 g, 7 mmol), and THF (200 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (1000 g) and the precipitate was filtered off. Ethyl acetate (300 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (1500 g) and concentrated. Ethyl acetate (100 g) and hexane (500 g) were added to the obtained crude product, and the product was repulped and washed at 0°C to obtain 23.9 g of [MA-4-1].

[MA-4-1] (23.9 g, 58 mmol) and formic acid (240 g) were charged into a 1 L four-neck flask and stirred at 50°C. After completion of the reaction, the reaction solution was poured into pure water (1000 g) and the precipitate was filtered off. Ethyl acetate (1000 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (1500 g) and concentrated. Hexane (40 g) was added to the obtained crude product and repulp washed at 0°C to obtain 19.6 g of [MA-4-2].

[MA-4-2] (19.6 g, 55 mmol), 2-hydroxyethyl methacrylate (7.9 g, 61 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (15.8 g, 83 mmol), 4-dimethylaminopyridine (0.7 g, 6 mmol), and THF (200 g) were charged into a 500 mL four-neck flask and stirred at room temperature. After completion of the reaction, the reaction solution was poured into ethyl acetate (600 g), and the organic layer was washed with pure water (1500 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate/hexane (volume ratio 1:3) solution, and hexane (200 g) was added to the obtained crude product and repulp washed at room temperature to obtain 23.6 g of [MA-4] (white solid). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the target [MA-4].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ 7.62-7.65 (m,3H), 7.30-7.31 (d,2H), 6.59-6.62 (d,1H), 6.04 (s,1H), 5.70 (s,1H), 4.80-4.84 (m,1H), 4.40-4.42 (m,2H), 4.36-4.38 (m,2H), 3.64-3.70 (m,2H) 2.56-2.61 (m,1H), 2.01-2.04 (d,2H), 1.88 (s,3H), 1.82-1.85 (d,2H), 1.58-1.66 (m,2H), 1.50-1.55 (m,2H).

(Monomer Synthesis Example 5)
Synthesis of [MA-5]:

[MA-1-1] (20.0 g, 66 mmol), trifluoroacetic acid (8.4 g, 74 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (19.4 g, 101 mmol), 4-dimethylaminopyridine (0.8 g, 7 mmol), and THF (200 g) were charged into a 1 L four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into pure water (1000 g) and the precipitate was filtered off. Ethyl acetate (300 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (900 g) and concentrated. The obtained crude product was treated with an ethyl acetate/hexane (volume ratio 1:4) solution and subjected to origin cut with silica gel to obtain 20.7 g of [MA-5-1].

[MA-5-1] (20.7 g, 52 mmol) and formic acid (210 g) were placed in a 1 L four-neck flask and stirred at 50°C. After completion of the reaction, the reaction solution was poured into pure water (1000 g) and the precipitate was filtered off. Methanol (600 g) was added to the obtained crude product to completely dissolve it, and then the product was concentrated. Ethyl acetate (500 g) was added to the obtained crude product, and the product was repulped and washed at room temperature to obtain 16.5 g of [MA-5-2].

[MA-5-2] (16.5 g, 48 mmol), 2-hydroxyethyl methacrylate (6.9 g, 53 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (15.7 g, 82 mmol), 4-dimethylaminopyridine (0.88 g, 7 mmol), and THF (170 g) were charged into a 500 mL four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into ethyl acetate (600 g), and the organic layer was washed with pure water (1500 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate/hexane (volume ratio 1:3) solution, and hexane (150 g) was added to the obtained crude product and repulp washed at room temperature to obtain 13.3 g of [MA-5] (white solid). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the target [MA-5].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ 7.63-7.66 (m,3H), 7.30-7.32 (d,2H), 6.60-6.63 (d,1H), 6.04 (s,1H), 5.70 (s,1H), 5.04-5.05 (m,1H), 4.40-4.42 (m,2H), 4.36-4.38 (m,2H), 2.62-2.63 (m,1H), 2.12-2.14 (d,2H), 1.88 (s,3H), 1.86-1.87 (d,2H), 1.61-1.68 (m,4H).

(Monomer Synthesis Example 6)
Synthesis of [MA-6]:

A 1L four-neck flask was charged with trans-4-hydroxycyclohexanecarboxylic acid (48.9 g, 339 mmol), triethylamine (34.6 g, 342 mmol), and THF (391 g), and chloromethyl methyl ether (28.7 g, 356 mmol) was added dropwise under ice-cooled conditions in a nitrogen atmosphere. After the addition, the mixture was allowed to react for 3 hours at room temperature to remove the raw materials. After the reaction was completed, the precipitate was removed by filtration, and the solvent was removed by concentration under reduced pressure. The resulting oily compound was diluted with ethyl acetate (490 g), and the ethyl acetate solution was washed three times with pure water (250 g). The ethyl acetate solution was then dehydrated with magnesium sulfate and concentrated under reduced pressure to obtain 49.6 g of [MA-6-1].

[MA-6-1] (25.3 g, 134 mmol), 4,4,4-trifluorobutyric acid (20.0 g, 141 mmol), 4-dimethylaminopyridine (1.64 g, 13.4 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (31.0 g, 162 mmol), and THF (126 g) were charged into a 1 L four-neck flask and reacted at room temperature for 15 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate (500 g), and the ethyl acetate solution was washed four times with pure water (250 g). The organic phase was concentrated under reduced pressure to obtain 41.8 g of [MA-6-2].

A 1 L four-neck flask was charged with [MA-6-2] (41.8 g, 134 mmol), 4 mol/L hydrochloric acid aqueous solution (82.0 mL), and acetonitrile (204 g), and the mixture was allowed to react for 4 hours under heating conditions at 45°C. After the reaction was completed, the acetonitrile was removed by vacuum concentration, and pure water (480 g) was added to precipitate crystals. The precipitated crystals were collected by filtration, and the crystals were slurry-washed with a mixed solution of toluene (80.0 g)/hexane (120 g). The slurry solution was filtered, and the obtained crystals were dried to obtain 15.8 g of [MA-6-3].

[MA-6-3] (15.8 g, 58 mmol), trans-p-tert-butyl coumarate (15.7 g, 71 mmol), 4-dimethylaminopyridine (0.7 g, 5 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (13.4 g, 70 mmol), and CHCl ₂ (160 g) were charged into a 500 mL four-neck flask and reacted for 5 hours under room temperature conditions. After the reaction was completed, the reaction solution was diluted with methylene chloride (320 g), and the methylene chloride solution was washed with pure water (300 g) three times to wash the organic phase. The organic phase was dehydrated with magnesium sulfate and concentrated under reduced pressure to obtain a crude product. The crude product was slurry washed with hexane (300 g), filtered, and dried to obtain 23.8 g of [MA-6-4].

A 500 mL four-neck flask was charged with [MA-6-4] (23.8 g, 51 mmol) and formic acid (240 g) and reacted for 5 hours under heating conditions at 60°C. After the reaction was completed, the reaction solution was poured into pure water (720 g) to precipitate crystals, which were then filtered and washed with pure water to obtain a crude product. The crude product was recrystallized in a mixed solvent of tetrahydrofuran (48 g)/acetonitrile (192 g), filtered and dried to obtain 14.2 g of [MA-6-5].

[MA-6-5] (14.2 g, 34.3 mmol), 2-hydroxyethyl methacrylate (5.4 g, 418 mmol), 4-dimethylaminopyridine (0.4 g, 3 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (9.3 g, 49 mmol), and THF (127 g) were charged into a 500 mL four-neck flask and reacted for about 1 day under room temperature conditions. After the reaction was completed, the tetrahydrofuran solution was recovered by decantation, and the tetrahydrofuran was removed by vacuum concentration. The concentrate was diluted with ethyl acetate (500 g), and the ethyl acetate solution was washed three times with pure water (200 g), and then dehydrated with magnesium sulfate. The ethyl acetate solution was concentrated under reduced pressure, and the concentrate was purified using an ethyl acetate/hexane (volume ratio 1:6 → 1:5) solution and a silica gel column to obtain 12.8 g of [MA-6-5] (white crystals). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the desired [MA-6].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ7.80 (d,2H), 7.69 (d,1H), 7.18 (d,2H), 6.66 (d,1H), 6.05 (s,1H), 5.70 (s,1H), 4.68-4.74 (m,1H), 4.42-4.43 (m,2H), 4.29-4.38 (m,2H), 2.64-2.69 (m,1H), 2.52-2.63 (m,4H), 2.09-2.12 (m,2H), 1.96-1.99 (m,2H), 1.88 (s,3H), 1.58-1.66 (m,2H), 1.44-1.52 (m,2H).

(Monomer Synthesis Example 7)
Synthesis of [MA-7]:

[MA-1-1] (20.0 g, 66 mmol), butyric acid (6.4 g, 73 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (19.0 g, 99 mmol), 4-dimethylaminopyridine (0.8 g, 7 mmol), and THF (200 g) were charged into a 500 mL four-neck flask and stirred at room temperature. After the reaction was completed, the reaction solution was poured into ethyl acetate (1000 g), and the organic layer was washed with pure water (1500 g) and concentrated. Hexane (100 g) was added to the obtained crude product, and the mixture was repulped and washed at 0°C to obtain 20.1 g of [MA-7-1].

A 500 mL four-neck flask was charged with [MA-7-1] (20.1 g, 54 mmol) and formic acid (200 g) and stirred at 50°C. After completion of the reaction, the reaction solution was poured into pure water (1000 g) and the precipitate was filtered off. Ethyl acetate (800 g) was added to the obtained crude product to completely dissolve it, and the organic layer was washed with pure water (1000 g) and concentrated. Ethyl acetate (50 g) was added to the obtained crude product and repulp washed at 0°C to obtain 16.2 g of [MA-7-2].

[MA-7-2] (16.2 g, 51 mmol), 2-hydroxyethyl methacrylate (7.3 g, 56 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (14.7 g, 77 mmol), 4-dimethylaminopyridine (0.62 g, 5 mmol), and THF (160 g) were charged into a 500 mL four-neck flask and stirred at room temperature. After completion of the reaction, the reaction solution was poured into ethyl acetate (1000 g), and the organic layer was washed with pure water (1500 g) and concentrated. The obtained crude product was subjected to origin cut with silica gel using an ethyl acetate/hexane (volume ratio 1:5) solution, and hexane (300 g) was added to the obtained crude product and repulp washed at 0 ° C. to obtain 18.4 g of [MA-7] (white solid). The results of ¹ H-NMR of the target product are shown below. From this result, it was confirmed that the obtained solid was the target [MA-7].
^1H NMR (500 MHz, [ _D6 ]-DMSO): δ7.62-7.65 (m,3H), 7.29-7.31 (d,2H), 6.59-6.62 (d,1H), 6.04 (s,1H), 5.70 (s,1H), 4.70-4.73 (m,1H), 4.40-4.42 (m,2H), 4.36-4.38 (m,2H), 2.55-2.58 (m,1H), 2.24-2.27 (t,2H), 1.98-2.00 (d,2H), 1.88 (s,3H), 1.81-1.83 (d,2H), 1.56-1.61 (m,4H), 1.46-1.54 (m,2H), 0.87-0.90 (t,3H)

<Methacrylate Polymer Synthesis Example 1>
MA-1 (3.86 g, 8.00 mmol), GMA (0.56 g, 4.00 mmol) and MAA (0.69 g, 8.00 mmol) were dissolved in NMP (29.9 g) and degassed with a diaphragm pump, and then AIBN (0.16 g, 0.5 mmol) was added as a polymerization initiator and degassed again. After that, the mixture was reacted at 60° C. for 13 hours to obtain a polymer solution.
Next, NMP (5.0 g) and BCS (6.0 g) were added to this polymer solution (4.0 g) and stirred at room temperature to obtain a methacrylate polymer solution (MP1).
The number average molecular weight of this polymer was 34,000 and the weight average molecular weight was 120,000.

<Methacrylate Polymer Synthesis Example 2>
MA-1 (3.86 g, 8.00 mmol) and MAA (1.03 g, 12.00 mmol) were dissolved in NMP (28.7 g), and the solution was degassed with a diaphragm pump. Then, AIBN (0.16 g, 0.5 mmol) was added as a polymerization initiator, and the solution was degassed again. After that, the solution was reacted at 60° C. for 13 hours to obtain a polymer solution.
Next, NMP (5.0 g) and BCS (6.0 g) were added to this polymer solution (4.0 g) and stirred at room temperature to obtain a methacrylate polymer solution (MP2).
The number average molecular weight of this polymer was 44,000 and the weight average molecular weight was 140,000.

<Methacrylate Polymer Synthesis Example 3>
MA-1 (3.86 g, 8.00 mmol) and MOI-BP (3.02 g, 12.00 mmol) were dissolved in NMP (36.7 g), and the solution was degassed with a diaphragm pump, after which AIBN (0.16 g, 0.5 mmol) was added as a polymerization initiator, and the solution was degassed again. Thereafter, the solution was reacted at 60° C. for 13 hours to obtain a polymer solution.
Next, NMP (5.0 g) and BCS (6.0 g) were added to this polymer solution (4.0 g) and stirred at room temperature to obtain a methacrylate polymer solution (MP3).
The number average molecular weight of this polymer was 45,000 and the weight average molecular weight was 145,000.

<Methacrylate Polymer Synthesis Examples 4 to 13>
Methacrylate polymer solutions (MP4) to (MP13) were synthesized using the compositions shown in Table 1 in the same manner as in Methacrylate Polymer Synthesis Examples 1 to 3.

<Polyamic Acid Polymer Synthesis Example 1>
B1 (1.14 g, 3.00 mmol), C2 (0.61 g, 4.00 mmol), C7 (0.73 g, 3.00 mmol) and A1 (1.12 g, 6.00 mmol) were dissolved in NMP (13.6 g) and reacted at 60° C. for 5 hours, after which A2 (0.50 g, 2.00 mmol) and A4 (0.44 g, 2.00 mmol) and NMP (4.6 g) were added and reacted at 40° C. for 10 hours to obtain a polyamic acid polymer solution (MP14).

<Polyamic Acid Polymer Synthesis Examples 2 to 17>
Polyamic acid polymer solutions (MP15) to (MP30) were synthesized using the compositions shown in Table 2 in the same manner as in Polyamic Acid Polymer Synthesis Example 1.

<Polyimide Polymer Synthesis Example 1>
Polyamic acid polymer solution (MP14) (50 g) was diluted to 6.5 mass% with NMP, and then acetic anhydride (8.8 g) and pyridine (2.7 g) were added as imidization catalysts and reacted at 75° C. for 2.5 hours. This reaction solution was poured into methanol (700 ml), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain polyimide polymer powder (E). The imidization rate of this polyimide polymer was 71%, the number average molecular weight was 13,000, and the weight average molecular weight was 42,000.

NMP (44.0 g) was added to the obtained polyimide powder (E) (6.0 g) and dissolved by stirring at 70 ° C for 20 hours. NMP (10.0 g) and BCS (40.0 g) were added to this solution and stirred at room temperature for 5 hours to obtain a polyimide polymer solution (MP31).

<Polyimide Polymer Synthesis Examples 2 to 17>
Using the polyamic acid polymer solutions obtained in Polyamic Acid Polymer Synthesis Examples 2 to 17, polyimide polymer solutions (MP32) to (MP47) were synthesized in the same manner as in Polyimide Polymer Synthesis Example 1.

Example 1
To the methacrylate polymer solution (MP1) (4.0 g) obtained in Methacrylate Polymer Synthesis Example 1, a crosslinking agent (D3) (0.06 g) was added and stirred at room temperature to obtain a liquid crystal alignment agent (PM1).

(Examples 2 and 3)
The methacrylate polymer solutions (MP2) to (MP3) obtained in Methacrylate Polymer Synthesis Examples 2 and 3 were subjected to the same method as in Example 1 to obtain liquid crystal alignment agents (PM2) and (PM3).

Example 4
To the methacrylate polymer solution (MP1) (3.0 g) obtained in Methacrylate Polymer Synthesis Example 1, a solution (7.0 g) obtained by adding NMP and BCS to the polyamic acid polymer solution (MP14) obtained in Polyamic Acid Polymer Synthesis Example 1 to give a polyamic acid polymer:NMP:BCS=4:56:40 (mass ratio) was added, and further a crosslinking agent (D3) (0.06 g) was added and stirred at room temperature to obtain a liquid crystal alignment treatment agent (PM4).

(Examples 5 to 20)
The same operation as in Example 4 was carried out using the methacrylate polymer solution (MP1), the polyamic acid polymer solutions (MP15) to (MP30), and the crosslinking agent (D3) to obtain liquid crystal alignment treatment agents (PM5) to (PM20). The compositions of the liquid crystal alignment treatment agents (PM5) to (PM20) are shown in Table 3.

(Example 21)
The polyimide polymer solution (MP31) (7.0 g) obtained in Polyimide Polymer Synthesis Example 1 was added to the methacrylate polymer solution (MP1) (3.0 g) obtained in Methacrylate Polymer Synthesis Example 1, and further the crosslinking agent (D3) (0.06 g) was added thereto, and the mixture was stirred at room temperature to obtain a liquid crystal alignment treatment agent (PM21).

(Examples 22 to 48)
The same operation as in Example 21 was carried out using methacrylate polymer solutions (MP1) to (MP10), polyimide polymer solutions (MP31) to (MP47), and crosslinking agents (D1) to (D3) to obtain liquid crystal alignment treatment agents (PM22) to (PM48). The compositions of the liquid crystal alignment treatment agents (PM22) to (PM48) are shown in Table 3.

(Comparative Example 1)
To the polymer solution (MP11) (4.0 g) obtained in Methacrylate Polymer Synthesis Example 11, the crosslinking agent (D3) (0.06 g) was added and stirred at room temperature to obtain a liquid crystal alignment agent (RPM1).

(Comparative Example 2 and Comparative Example 3)
Using the polymer solutions obtained in Methacrylate Polymer Synthesis Examples 12 and 13, liquid crystal alignment treatment agents (RPM2) and (RPM3) were obtained in the same manner as in Comparative Example 1.

(Comparative Example 4)
To the methacrylate polymer solution (MP11) (3.0 g) obtained in Methacrylate Polymer Synthesis Example 11, a solution (7.0 g) obtained by adding NMP and BCS to the polyamic acid polymer solution (MP14) obtained in Polyamic Acid Polymer Synthesis Example 1 to give a polyamic acid polymer:NMP:BCS=4:56:40 (mass ratio) was added, and further a crosslinking agent (D3) (0.06 g) was added and stirred at room temperature to obtain a liquid crystal alignment treatment agent (RPM4).

(Comparative Example 5 and Comparative Example 6)
Using the methacrylate polymer solutions obtained in Methacrylate Polymer Synthesis Examples 12 and 13, liquid crystal alignment agents (RPM5) and (RPM6) were obtained in the same manner as in Comparative Example 4.
(Comparative Example 7)
The polyimide polymer solution (MP31) (7.0 g) obtained in Polyimide Polymer Synthesis Example 1 was added to the methacrylate polymer solution (MP11) (3.0 g) obtained in Methacrylate Polymer Synthesis Example 11, and further the crosslinking agent (D3) (0.06 g) was added thereto, and the mixture was stirred at room temperature to obtain a liquid crystal alignment treatment agent (RPM7).

(Comparative Example 8 and Comparative Example 9)
Using the methacrylate polymer solutions obtained in Methacrylate Polymer Synthesis Examples 12 and 13, liquid crystal alignment agents (RPM8) and (RPM9) were obtained in the same manner as in Comparative Example 7.

<Preparation of Liquid Crystal Display Element>
The liquid crystal alignment treatment agents (PM1) to (PM48) obtained in the examples and the liquid crystal alignment treatment agents (RPM1) to (RPM9) obtained in the comparative examples were pressure filtered through a membrane filter having a pore size of 1 μm.
The obtained solution was spin-coated on the ITO surface of a glass substrate with a transparent electrode made of an ITO film, dried on a hot plate at 70°C for 90 seconds, and then baked on a hot plate at 200°C for 30 minutes to form a liquid crystal alignment film with a thickness of 100 nm.
Next, the coating surface was irradiated with 313 nm linearly polarized ultraviolet light with an irradiation intensity of 4.3 mW/ ^cm2 at an angle of 40° from the substrate normal direction at 50 mJ/ ^cm2 through a polarizing plate to obtain a substrate with a liquid crystal alignment film. The linearly polarized ultraviolet light was prepared by passing ultraviolet light from a high-pressure mercury lamp through a 313 nm bandpass filter and then through a 313 nm polarizing plate.
Two of the above substrates were prepared, and 4 μm bead spacers were dispersed on the liquid crystal alignment film of one of the substrates, after which a sealant (Mitsui Chemicals, XN-1500T) was applied. Next, the other substrate was attached so that the liquid crystal alignment film faces each other and the alignment direction was 180°, and then the sealant was thermally cured at 120°C for 90 minutes to prepare an empty cell. Liquid crystal (Merck, MLC-3022) was injected into this empty cell by the reduced pressure injection method to obtain a liquid crystal display element.

<Evaluation>
(Liquid crystal alignment)
The liquid crystal display element obtained above was subjected to isotropic phase treatment at 120° C. for 1 hour, and then the cell was observed using a polarizing microscope. The liquid crystal display element was evaluated as being good if there was no alignment defect such as light leakage or domain generation, or if uniform liquid crystal driving was obtained when voltage was applied to the liquid crystal cell. The evaluation results are shown in Table 4.

(Pretilt angle)
The pretilt angle of the liquid crystal cell of the liquid crystal display element prepared above was measured by the Mueller matrix method using AxoScan manufactured by Axo Metrix, Inc. The evaluation results are shown in Table 4.

(Evaluation of Tilt Angle Change)
After measuring the pretilt angle, AC 15 Vp-p was applied to the liquid crystal cell, and the tilt angle was measured again after 36 hours to calculate how much the tilt angle had changed. The evaluation results are shown in Table 4.

As can be seen from the results in Table 4, by comparing Examples 1 to 46 with Comparative Examples 1 to 9, a polymethacrylate solution containing a photo-aligning monomer not having -COO- or -OCO- in R ₃ in formula (pa-1) or a blend of the polymethacrylate solution with a polyamic acid or a polyimide solution had low stability of tilt angle (large change in tilt angle), whereas a polymethacrylate solution containing a photo-aligning monomer having -COO- or -OCO- in R ₃ in formula (pa-1) or a blend of the polymethacrylate solution with a polyamic acid or a polyimide solution had high stability of tilt angle (small change in tilt angle) to obtain a liquid crystal alignment film.

The liquid crystal alignment agent of the present invention and the liquid crystal display element using the liquid crystal alignment film obtained therefrom can be suitably used as a liquid crystal display element that requires durability, such as for in-vehicle use.

Claims (7)

The component (A) is represented by the following formula (pa-1):
in which A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furanylene, 1,4- or 2,6-naphthylene or phenylene, optionally substituted by a group selected from fluorine, chlorine, cyano or by an alkoxy group having 1 to 5 carbon atoms, a linear or branched alkyl residue, which is optionally substituted by one cyano group or one or more halogen atoms,
X and Y each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, or an alkyl group having 1 to 3 carbon atoms;
R ₁ is a single bond, an oxygen atom, -COO- or -OCO-;
_R2 is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent fused ring group;
_R3 is -COO- or -OCO-;
_R4 is a monovalent organic group having 3 to 40 carbon atoms, which contains a linear or branched alkyl group or an alicyclic group having 1 to 40 carbon atoms;
D represents an oxygen atom, a sulfur atom, or -NR _d - (wherein R _d represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms);
a is an integer of 1 to 3, and * represents the bonding position.
A liquid crystal aligning agent comprising: a polymer having a photoalignment group represented by the formula:
The above liquid crystal aligning agent further comprising, as a component (C), a polymer selected from polyimides and precursors thereof, the polymer having a tertiary-butoxycarbonyl group .

The liquid crystal aligning agent according to claim 1, wherein the component (A) is a polymer further having a thermal crosslinkable group A and satisfies at least one of the following requirements Z1 and Z2:
Z1: The polymer which is the component (A) further has a thermally crosslinkable group B.
Z2: The component (B) further contains a compound having two or more thermally crosslinkable groups B in the molecule.
The thermally crosslinkable group A and the thermally crosslinkable group B are each independently an organic group selected from the group consisting of a carboxyl group, an amino group, an alkoxymethylamide group, a hydroxymethylamide group, a hydroxyl group, an epoxy moiety-containing group, an oxetanyl group, a thiiranyl group, an isocyanate group, and a blocked isocyanate group, and are selected so that the thermally crosslinkable group A and the thermally crosslinkable group B undergo a crosslinking reaction by heat, however, the thermally crosslinkable group A and the thermally crosslinkable group B may be the same as each other. The polymer having a photo-aligning group represented by the formula (pa-1) is represented by the following formula (MA) (wherein S _b represents a linear or branched alkyl group having 1 to 10 carbon atoms, R ₆ is a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkyl group having 1 to 10 carbon atoms substituted with a halogen, R ₇ is a single bond, an oxygen atom, -COO- or -OCO-, R ₈ is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group or a divalent condensed cyclic group, R ₉ is -COO- or -OCO-, R ₁₀ is a linear or branched alkyl group having 1 to 10 carbon atoms in which the hydrogen atom of the alkyl group may be substituted with fluorine, and b represents an integer of 1 to 3.) The liquid crystal alignment agent according to claim 1 or 2 , which is derived from a polymerizable monomer having a photo-aligning group represented by the following formula (MA).

The liquid crystal aligning agent according to claim 3 , wherein the polymerizable monomer is represented by any one selected from the group consisting of formulas (MA-1) to (MA-7):

A liquid crystal alignment film formed by using the liquid crystal aligning agent according to any one of claims 1 to 4 . A method for producing a liquid crystal alignment film, comprising: a step of applying the liquid crystal alignment agent according to any one of claims 1 to 4 onto a substrate to form a coating film; and a step of irradiating the coating film with light in a state where the coating film is not in contact with a liquid crystal layer or in a state where the coating film is in contact with a liquid crystal layer. A liquid crystal display device comprising the liquid crystal alignment film according to claim 5 or the liquid crystal alignment film obtained by the method according to claim 6 .