TW202336218A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment film having high tilt expression capability, a liquid crystal display having the liquid crystal alignment film, and a liquid crystal alignment agent for providing the liquid crystal alignment film. The present invention provides a liquid crystal alignment agent containing as a component (A) a polymer that has a photo-aligning group, an oxazoline skeleton, and a carboxy group and is represented by formula (pa-1). (In the formula, A represents a phenylene group or the like, R1 is a single bond or an oxygen atom or the like, R2 is a divalent aromatic group or the like, R3 is a single bond or an oxygen atom or the like, R4 is a C3-40 univalent organic group including a C1-40 straight-chain or branched alkyl group or an alicyclic group, D represents an oxygen atom, a sulfur atom, or -NRd0, a is an integer of 0 to 3, and * represents a bond position. A thermally crosslinkable group A and a thermally crosslinkable group B are selected so that the thermally crosslinkable group A and the thermally crosslinkable group B undergo a crosslinking reaction due to heat.).

Description

Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained thereby, and a liquid crystal display element provided with the obtained liquid crystal alignment film. More specifically, the invention relates to a liquid crystal alignment agent that can provide liquid crystal with good alignment properties, excellent pretilt angle expression ability, and obtain a highly reliable liquid crystal alignment film, and a liquid crystal display element with excellent display quality.

In liquid crystal display elements, the liquid crystal alignment film plays the role of aligning liquid crystals in a certain direction. Currently, the main liquid crystal alignment films used in industry are made of polyamide (also known as polyamide), polyamide ester, or polyimide as the precursor of polyamide. The polyimide-based liquid crystal alignment agent composed of a solution is coated on a substrate and formed into a film. In addition, when the liquid crystal is aligned in parallel or obliquely with respect to the substrate surface, surface stretching treatment by rubbing is further performed after film formation.

On the other hand, when aligning liquid crystal vertically with respect to a substrate (called a vertical alignment (VA) method), a combination of a long-chain alkyl group, a cyclic group, or a cyclic group and an alkyl group is used (for example, see Patent Document 1 ), steroid skeleton (for example, refer to Patent Document 2), a liquid crystal alignment film in which a hydrophobic group such as a polyamide imide is introduced into the side chain of polyimide. At this time, when a voltage is applied between the substrates and the liquid crystal molecules are tilted in a direction parallel to the substrates, the liquid crystal molecules must be tilted from the normal direction of the substrates toward a direction in the plane of the substrates. As means for this purpose, methods have been proposed, such as providing protrusions on the substrate, providing slits in the display electrodes, and inclining the liquid crystal molecules slightly in advance from the normal direction of the substrate toward a direction in the substrate plane. (pre-tilt) method, furthermore, by adding a photopolymerizable compound to the liquid crystal composition in advance, and using it together with a vertical alignment film such as polyimide, to apply voltage to the liquid crystal cell while irradiating ultraviolet rays to pretilt the liquid crystal. methods (for example, refer to Patent Document 3), etc.

In recent years, VA methods have also been proposed to form protrusions or slits in liquid crystal alignment control, and as an alternative to PSA technology, methods that utilize anisotropic photochemical reactions caused by polarized ultraviolet irradiation (photoalignment method) have been proposed. That is, it is known that by irradiating a polyimide film with photoreactive vertical alignment with polarized ultraviolet light to impart alignment adjustment capabilities and pretilt angle display properties, it is known that the tilt direction of liquid crystal molecules can be uniformly controlled when a voltage is applied. (Refer to Patent Document 4).

VA type liquid crystal display elements are used in TV or car displays due to their characteristics of high contrast and wide viewing angle. Liquid crystal display elements for TVs may use a backlight that generates a large amount of heat to obtain high brightness, or liquid crystal display elements for automotive applications such as car navigation systems or dashboards may be used or placed in high-temperature environments for long periods of time. . Under such harsh conditions, when the pretilt angle slowly changes, it will cause the initial display characteristics to be lost, or uneven display problems will occur. Furthermore, the voltage retention characteristics or charge accumulation characteristics when driving liquid crystal are also affected by the liquid crystal alignment film. When the voltage retention rate is low, the contrast of the display screen will be reduced. When the charge accumulation on the DC voltage is large, the phenomenon of display screen burn-in will occur. . [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 3-179323 [Patent Document 2] Japanese Patent Application Laid-Open No. 4-281427 [Patent Document 3] Japanese Patent No. 4504626 [Patent Document 4] Japanese Patent No. 4995267

[Problem to be solved by the invention]

The present invention was made in view of the above circumstances, and its object is to provide a liquid crystal alignment film that has little change in pretilt angle even after driving for a long time, has excellent display reliability, has high voltage holding characteristics, and can reduce charge accumulation. A liquid crystal display element having the same, and a liquid crystal alignment agent provided therewith. [Means used to solve problems]

The present inventors discovered an invention based on the following <X>. <X> A liquid crystal alignment agent containing a polymer having a photo-alignment group represented by the following formula (pa-1), an oxazoline skeleton, and a carboxyl group as the component (A).

In the formula, A represents a group selected from a fluorine atom, a chlorine atom, and a cyano group, as appropriate, or an alkoxy group having 1 to 5 carbon atoms, or a linear or branched chain alkyl residue (which may be 1 cyano group or more than 1 halogen atom substituted) substituted pyrimidine-2,5-diyl, pyridine-2,5-diyl, thiophene-2,5-diyl, furan-2,5-diyl , 1,4- or 2,6-naphthylene or phenyl, R ₁ is a single bond, oxygen atom, -COO- or -OCO-, R ₂ is a divalent aromatic group or a divalent alicyclic group Formula base, divalent heterocyclic group or divalent condensed cyclic group, R ₃ is a single bond, oxygen atom, -COO- or -OCO-, R ₄ is a linear or branched chain with 1 to 40 carbon atoms. an alkyl group or a monovalent organic group with 3 to 40 carbon atoms containing an alicyclic group, D represents an oxygen atom, a sulfur atom or -NR _d - (here, R _d represents a hydrogen atom or an alkane with 1 to 3 carbon atoms base), a is an integer from 0 to 3, and when a is 2 or more, the plurality of R ₁ and R ₂ independently have the above definitions. X and Y are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms. *Indicates bonding position. [Effects of the invention]

Through the present invention, a liquid crystal alignment film and a liquid crystal alignment agent with good liquid crystal alignment properties and excellent pretilt angle display capability can be provided. In addition, 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 contains a polymer having a photo-alignment group represented by the above formula (pa-1), an oxazoline skeleton and a carboxyl group.

The polymer of component (A) contained in the liquid crystal alignment agent of the present invention has high sensitivity to light, so it can exhibit alignment control capabilities even under low-exposure polarized ultraviolet irradiation. In addition, since the polymer of component (A) contains a carboxyl group and further contains an oxazoline skeleton in the component, even if the firing time of the liquid crystal alignment agent is short, the polymer containing component (A) can be exchanged. linked reaction. In this way, when the photoalignment portion exhibits anisotropy through photoreaction, the anisotropy is likely to remain (memory) in the liquid crystal alignment film, thereby improving the liquid crystal alignment and exhibiting the pretilt angle of the liquid crystal.

Each component of the present invention is described in detail below.

<(A) component: specific polymer> [Photo-alignment group represented by formula (pa-1)] In the present invention, the portion having the photo-alignment group represented by the above formula (pa-1) in the molecule can be, for example, It is represented by the following formula (a-1). In addition, examples of the moiety include structures derived from the monomer represented by the following formula (a-1-m), but are not limited thereto. In the formula, I _a is a monovalent organic group represented by the following formula (pa-1).

In the formula (pa-1), A represents a group selected from a fluorine atom, a chlorine atom, a cyano group, or an alkoxy group having 1 to 5 carbon atoms, or a linear or branched chain alkyl residue. (It is substituted by 1 cyano group or more than 1 halogen atom as appropriate) Substituted pyrimidine-2,5-diyl, pyridine-2,5-diyl, thiophene-2,5-diyl, furan-2 , 5-diyl, 1,4- or 2,6-naphthyl or phenyl, R ₁ is a single bond, oxygen atom, -COO- or -OCO-, R ₂ is a divalent aromatic group, Divalent alicyclic group, divalent heterocyclic group or divalent condensed cyclic group, R ₃ is a single bond, oxygen atom, -COO- or -OCO-, R ₄ is a carbon number of 1 to 40 A linear or branched chain alkyl group or a monovalent organic group with 3 to 40 carbon atoms containing an alicyclic group, D represents an oxygen atom, a sulfur atom or -NR _d - (here, R _d represents a hydrogen atom or carbon number (alkyl group of 1 to 3), a is an integer from 0 to 3, and when a is 2 or more, the plurality of R ₁ and R ₂ independently have the above definitions. X and Y are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms. *Indicates bonding position.

In the above formula (a-1) or (a-1-m), _Sa represents a spacer, and I _a represents a main chain optionally bonded to a specific polymer via a spacer. S _a can be represented by the structure of the following formula (Sp), for example.

In the formula (Sp), the bond on the left side of W ₁ represents the bond to M _b , the bond on the right side of W ₃ represents the bond to I _a , and W ₁ , W ₂ and W ₃ independently represent single Bond, divalent heterocycle, -(CH ₂ ) _n -(where n represents 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-, but one or more of the non-adjacent CH ₂ groups in these substituents are independent The ground can pass through -O-, -CO-, -CO-O-, -O-CO-, -Si(CH ₃ ) ₂ -O-Si(CH ₃ ) ₂ -, -NR-, -NR-CO- , -CO-NR-, -NR-CO-O-, -OCO-NR-, -NR-CO-NR-, -CH=CH-, -C≡C- or -O-CO-O-(Formula Among them, R independently represents hydrogen or a linear or branched chain alkyl group with 1 to 5 carbon atoms) substitution, and A ₁ and A ₂ are each independently selected from a single bond, a divalent hydrocarbon group, and a divalent aromatic group. A group of a family group, a divalent alicyclic group, and a divalent heterocyclic group, each of which is unsubstituted or has more than one hydrogen atom that can be replaced by a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group. base substitution.

In formula (a-1-m), M _a represents a polymerizable group. Examples of the polymerizable group include (meth)acrylate, fumarate, maleate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, and norbornene. , free radical polymerizable groups of (meth)acrylamide and its derivatives, and siloxane. Preferred are (meth)acrylate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, and acrylamide. r is an integer satisfying 1≦r≦3. M _b is selected from the group consisting of single bonds, (r+1)-valent heterocyclic groups, (r+1)-valent linear or branched hydrocarbon groups with 1 to 10 carbon atoms, and (r+1)-valent aromatic groups. group, and the group of an alicyclic group with a valence of (r+1), each of the groups is unsubstituted or one or more hydrogen atoms may be substituted by a fluorine atom, a chlorine atom, a cyano group, a methyl group or a methoxy group.

The aromatic groups in A ₁ , A ₂ , and M _b include, for example, aromatic hydrocarbons having 6 to 18 carbon atoms in benzene rings, biphenyl structures, and naphthalene rings. Among the above benzene rings, biphenyl structures, and naphthalene rings, Some or all of the hydrogen atoms may also be replaced by fluorine atoms. Examples of the alicyclic group in A ₁ , A ₂ , and M _b include alicyclic hydrocarbons having 6 to 12 carbon atoms such as a cyclohexane ring or a bicyclohexane structure. Examples of the heterocyclic group in A ₁ , A ₂ , and M _b include nitrogen-containing heterocyclic rings such as pyridine ring, piperidine ring, and piperazine ring. The hydrocarbon group in A ₁ and A ₂ can include a linear or branched hydrocarbon group with 1 to 10 carbon atoms, preferably a linear or branched alkylene group with 1 to 8 carbon atoms; more preferably, it is methylene. Base, ethylene, n-propylene, n-butylene, t-butylene, n-pentylene, n-hexylene, n-heptyl, n-octyl.

From the viewpoint of exhibiting good vertical alignment control capability and stable pretilt angle, the base represented by (pa-1) above is preferably the base represented by (pa-1-a) below. In addition, examples of the moiety include structures derived from the monomer represented by the following formula (pa-1-ma), but are not limited thereto.

In formula (pa-1-a) or (pa-1-ma), M _a , M _b , and S _a have the same definitions as above. Z is an oxygen atom or a sulfur atom. X _a and X _b are each independently 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, oxygen atom, -COO- or -OCO-. R ₂ is a divalent aromatic group, a divalent alicyclic group, or a divalent heterocyclic group. R ₃ is a single bond, oxygen atom, -COO- or -OCO-. R ₄ is a linear or branched chain alkyl group having 1 to 40 carbon atoms or a monovalent organic group having 3 to 40 carbon atoms including an alicyclic group. R ₅ 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 when a is 2 or more, the plurality of R ₁ and R ₂ independently have the above definitions. b is an integer from 0 to 4, and when b is 2 or more, a plurality of R ₅ independently have the above definitions.

S _a is preferably an alkylene group having 1 to 8 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, still more preferably an alkylene group having 1 to 4 carbon atoms.

Examples of the divalent aromatic group of R ₂ include 1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, and 2,3,5 , 6-tetrafluoro-1,4-phenylene, naphthylene, etc.

Examples of the divalent alicyclic group of R ₂ include trans-1,4-cyclohexylene, trans-trans-1,4-bicyclohexylene, and the like.

Examples of the divalent heterocyclic group of R ₂ include pyridine-1,4-diyl, pyridine-2,5-diyl, furan-2,5-diyl, and piperazine-1,4-diyl. , piperidine-1,4-diyl, etc.

R ₂ is preferably 1,4-phenylene, trans-1,4-cyclohexylene, or trans-trans-1,4-bicyclohexylene.

Examples of R ₄ include straight-chain or branched-chain alkyl groups having 1 to 40 carbon atoms. Examples of R 4 include straight-chain or branched-chain alkyl groups having 1 to 20 carbon atoms. Some or all of the hydrogen atoms in the alkyl group may also be Fluorine atom substitution. Examples of the alkyl group include methyl, ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n- Nonyl, n-decyl, n-lauryl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n- Heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, 4,4,4-trifluorobutyl, 4,4,5,5,5-pentafluoropentyl base, 4,4,5,5,6,6,6-heptafluorohexyl, 3,3,4,4,5,5,5-heptafluoropentyl, 2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl, 2-(perfluorobutyl)ethyl, 2-(perfluorooctyl)ethyl, 2-(perfluorodecyl)ethyl, etc.

Examples of R ₄ as a monovalent organic group having 3 to 40 carbon atoms including an alicyclic group include cholesterol group, dihydrocholestanyl group (cholestanyl), adamantyl group, the following formula (Alc-1) or (Alc- 2) (In the formula, R ₇ is a hydrogen atom, a fluorine atom or an alkyl group with 1 to 20 carbon atoms. Some or all of the hydrogen atoms in the alkyl group with 1 to 20 carbon atoms can be substituted by fluorine atoms. * represents a bond. position) represents the basis, etc.

Examples of the monomer represented by the above formula (pa-1-ma) include compounds represented by formulas (paa-1-ma1) to (paa-1-ma18), but are not limited thereto. Furthermore, in the formula, "E" represents the E body, and "t" represents the trans form of the cyclohexyl group.

[Oxazoline Skeleton] To introduce an oxazoline skeleton into the polymer of component (A), monomers having an oxazoline skeleton may be copolymerized. Examples of the monomer having an oxazoline skeleton include compounds represented by the following formula (1-ma). In formula (1-ma), Ma _{, Mb} , _Sa , and r are as defined above, and _Iox represents a univalent group having an oxazoline skeleton.

As I _ox , a group having an oxazoline skeleton at the terminal is preferred, and an oxazoline-2-group optionally substituted with an alkyl group having 1 to 5 carbon atoms is more preferred. Specifically, monomers represented by the following formulas (1-ma1) to (1-ma7) can be cited.

Such monomers can be prepared by using nitrile compounds such as p-hydroxybenzonitrile and aminoethanol analogs such as 2-amino-2-methyl-1-propanol as starting materials. Produced by the method described in the synthesis examples.

[carboxyl] To introduce a carboxyl group into the polymer of component (A), monomers having a carboxyl group may be copolymerized.

Examples of monomers having carboxyl groups include acrylic acid, methacrylic acid, crotonic acid, mono-(2-(acryloxy)ethyl) phthalate, and mono-(2-(methacryloxy)ethyl). ethyl) phthalate, N-(carboxyphenyl)maleimide, N-(carboxyphenyl)methacrylamide, and N-(carboxyphenyl)acrylamide, etc. .

Furthermore, in the present invention, when obtaining a specific polymer, in addition to the monomer having a photoalignment group, the monomer having an oxazoline skeleton, and the monomer having a carboxyl group represented by the above formula (a-1-m), Other monomers copolymerizable with these monomers may be used in combination.

Specific examples of such other monomers include acrylate compounds, methacrylate compounds, (meth)acrylic acid amide compounds, vinyl compounds, styrene compounds, maleimide compounds, acrylonitrile, and maleic acid amide compounds. Acid anhydride, monomer having nitrogen-containing aromatic heterocyclic group and polymerizable group.

Examples of the acrylate compound include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthracene acrylate, anthracenyl methyl acrylate, phenyl acrylate, and 2,2,2 acrylate. -Trifluoroethyl, tert-butyl acrylate, cyclohexyl acrylate, isocamphenyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, Tetrahydrofuran methyl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricycloacrylate [5.2 .1.0＜2,6＞]decyl ester, and acrylic acid 8-ethyl-8-tricyclo[5.2.1.0＜2,6＞]decyl ester, etc.

Examples of the methacrylate compound include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, cetyl methacrylate, stearyl methacrylate, and benzyl methacrylate. Ester, naphthyl methacrylate, anthracene methacrylate, anthracenyl methyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl methacrylate, Cyclohexyl methacrylate, isocamphenyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, methyl Tetrahydrofuran methyl acrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-propyl-2-adamantyl methacrylate, 8-methyl methacrylate 8-tricyclo[5.2.1.0<2,6>]decyl ester, and 8-ethyl-8-tricyclo[5.2.1.0<2,6>]decyl methacrylate, etc.

Examples of the (meth)acrylamide compound include acrylamide, methacrylamide, N-methacrylamide, N,N-dimethylacrylamide, and N,N-diethylpropylene. amide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, etc.

Examples of the aforementioned vinyl compounds include methyl vinyl ether, benzyl vinyl ether, vinyl naphthalene, vinyl carbazole, allyl glycidyl ether, and 3-vinyl-7-oxabicyclo [4.1 .0]Heptane etc. Examples of the styrene compound include styrene, methylstyrene, chlorostyrene, bromostyrene, and the like. Examples of the maleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

The nitrogen-containing aromatic heterocycle may contain at least 1, preferably 1 to 4, selected from the following formulas [Na]~[Nb] (in the formula, Z ₂ is a straight chain or straight chain with 1 to 5 carbon atoms) Aromatic hydrocarbon rings with a structure composed of branched alkyl groups.

Specific examples include an oxazole ring, a thiazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a thiadiazole ring, a pyridazine ring, a triazine ring, a pyrazine ring, a phenanthroline ring, and a quinoline ring. Oxoline ring, benzothiazole ring, oxadiazole ring, acridine ring, etc. Furthermore, the carbon atoms of these nitrogen-containing aromatic heterocycles may also have substituents containing heteroatoms. Among these, a pyridine ring is exemplified.

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

The above-mentioned 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 formula (pa-1) contained in the polymer of component (A) of the liquid crystal alignment agent of the present invention may be used alone or in combination of two or more species.

The photoreactive moiety represented by the above formula (pa-1) is preferably contained in a proportion of 5 to 95 mol%, 10 to 60 mol%, or 15 to 50 mol% of all repeating units of the polymer of component (A).

The introduction amount of the moiety having an oxazoline skeleton is preferably 5 to 50 mol%, 20 to 45 mol%, or 25 to 40 mol% of all repeating units of the polymer of component (A).

The introduction amount of the moiety having a carboxyl group is preferably 5 to 55 mol%, 20 to 50 mol%, or 25 to 45 mol% of the total repeating units of the polymer of component (A).

The content of the structure derived from the above-mentioned other monomers is preferably 0 to 40 mol%, 0 to 30 mol%, or 0 to 20 mol% of all repeating units of the polymer of component (A).

＜Production method of specific polymer＞ The specific polymer of component (A) contained in the liquid crystal alignment agent of the present invention can be combined with a monomer having a photo-alignment group represented by the above formula (pa-1), a monomer having an oxazoline skeleton, a monomer having a carboxyl group The monomers and, if desired, other monomers described above are copolymerized.

The method for producing the specific polymer of component (A) in the present invention is not particularly limited, and a common method used in industry can be used. Specifically, it can be produced by cationic polymerization, radical polymerization, or anionic polymerization using vinyl groups of monomers. Among these, radical polymerization is particularly preferred from the viewpoint of easy reaction control. As a polymerization initiator for radical polymerization, a known compound such as a radical polymerization initiator or a reversible addition-fragmentation chain transfer (RAFT) polymerization reagent can be used.

A free radical thermal polymerization initiator is a compound that generates free radicals by heating to a temperature above the decomposition temperature. Examples of such radical thermal polymerization initiators include ketone peroxides (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), diyl peroxides (acetyl peroxide compounds, benzyl peroxide, etc.), hydroperoxides (hydroperoxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc.), dialkyl peroxides (dihydroperoxide -tert-Butyl peroxide, dicumyl peroxide, dilauryl peroxide, etc.), peroxy ketals (dibutylperoxycyclohexane, etc.), alkyl peroxides Oxyacid esters (peroxyneodecanoic acid-tert-butyl ester, peroxytrimethylacetic acid-tert-butyl ester, peroxy 2-ethylcyclohexanoic acid-tert-pentyl ester, etc.), Sulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), azo compounds (azobisisobutyronitrile, and 2,2'-bis(2-hydroxyethyl)azobisisobutyronitrile wait).

Such a radical thermal polymerization initiator may be used individually by 1 type, or may be used in combination of 2 or more types.

The radical photopolymerization initiator is not particularly limited as long as it is a compound that starts radical polymerization by light irradiation. Examples of such radical photopolymerization initiators include benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, Well-known compounds such as thioxanthone and isopropylxanthinone. These compounds can be used individually or in mixture of 2 or more types. The radical polymerization method is not particularly limited, and emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, block polymerization, solution polymerization, etc. can be used.

The solvent used for the polymerization reaction of the specific polymer of component (A) is not particularly limited as long as it can dissolve the produced polymer. Specific examples include solvents described in the <solvent> section described below, such as N-alkyl-2-pyrrolidinones, dialkyl imidazolinones, lactones, carbonates, ketones, formula (Sv Compounds represented by -1) and compounds represented by formula (Sv-2), tetrahydrofuran, 1,4-dioxane, dimethylsulfone, dimethylsulfoxide, etc. These solvents can be used individually or in mixture. Furthermore, even if it is a solvent which does not dissolve the produced|generated polymer, it can also be mixed with the said solvent and used in the range which does not precipitate the produced|generated polymer. In addition, in radical polymerization, oxygen in the solvent may hinder the polymerization reaction, so it is preferable to use an organic solvent that has been degassed to the extent possible.

The polymerization temperature during free radical polymerization can be selected from any temperature ranging from 30 to 150°C, preferably from 50 to 100°C. In addition, the reaction can be carried out at any concentration, but the monomer concentration is preferably 1 to 50 mass%, and more preferably 5 to 30 mass%. The reaction is initially carried out at a high concentration, and an organic solvent can be added later. In the above-mentioned free radical polymerization reaction, when the ratio of the free radical polymerization initiator to the monomer is larger, the molecular weight of the resulting polymer becomes smaller, and when it is smaller, the molecular weight of the resulting polymer becomes larger, so the radical initiator The ratio is preferably 0.1 to 10 mol% relative to the monomer to be polymerized. In addition, various monomer components, solvents, initiators, etc. may be added during polymerization.

[Polymer recycling] When recovering the polymer produced from the reaction solution obtained by the above reaction, the reaction solution may be put into a poor solvent to precipitate the polymer. Poor solvents used for precipitation include methanol, acetone, hexane, heptane, butylcellulose, heptane, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, water, etc. The polymer put into the poor solvent and precipitated can be filtered and recovered, and then dried under normal pressure or reduced pressure, at normal temperature or by heating. In addition, if the polymer recovered through precipitation is redissolved in an organic solvent, and the re-precipitation recovery operation is repeated 2 to 10 times, the impurities in the polymer can be reduced. Examples of poor solvents in this case include alcohols, ketones, hydrocarbons, etc. It is preferable to use three or more types of poor solvents selected from these because the purification efficiency will be further improved.

(A) The molecular weight of the specific polymer of the component, when considering the strength of the resulting coating film, the workability during coating film formation, and the uniformity of the coating film, the weight average molecular weight measured by the GPC (Gel Permeation Chromatography) method is relatively The best value is 2,000~1,000,000, and the better value is 5,000~100,000.

＜(B)Component＞ The liquid crystal alignment agent of the present invention may contain a polymer selected from polyimide and its precursors as component (B). By containing the polymer of component (B), it is possible to further improve the electrical characteristics such as increasing the voltage holding ratio and suppressing the accumulation of residual charges.

The component (B) is a polymer selected from polyimide and its precursors, preferably at least one of the following polymers: having at least one group selected from a vertical alignment group and a tert-butoxycarbonyl group, or Chemically imidized.

The polymer of component (B) is polyimide and its precursor (hereinafter also referred to as polyimide component), and is a component with a surface energy close to that of the polymer of component (A). Acrylic components such as component (A) basically have low polarity and low surface energy. On the other hand, the polyimide component has high polarity and high surface energy. However, when the difference in surface energy of the two components is too large, they cannot dissolve smoothly and agglomeration occurs, resulting in a film with unevenness, or collapse or unevenness, so there is a problem of narrowing the process margin. The danger. Therefore, by making the polarity of the polyimide component low, the surface energy can be controlled to a value that is higher than that of the acrylic component, but the difference is small. As a method of reducing the polarity of the polyimide component, there is a method of chemically imidizing it and then mixing it with the component (A), or a method of introducing a side chain.

Examples of such polymers include polymers obtained by polymerizing known tetracarboxylic acid derivatives such as tetracarboxylic dianhydride and known diamines and then chemically imidizing them, and polymers obtained by using diamines having side chains. Polyimide precursor, polyimide obtained by imidizing it, polyimide precursor obtained by using a diamine having a tert-butoxycarbonyl group, and polyimide obtained by imidizing it imine etc. By imidizing such side chains or chemicals, the surface energy can be brought close to that of the acrylic polymer of component (A). Therefore, when the liquid crystal alignment agent is applied and fired to form a cured film, aggregation, etc., can be avoided and the cured film can be formed. Flat hardened film. 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 No. WO2016/125870, and Specific examples thereof include diamines represented by formulas [A-1] to [A-32]. Diamines having a tert-butoxycarbonyl group include those having the formulas [A-1], [A-2], [A- 3] and the diamines illustrated as specific examples thereof.

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

＜(C)Component＞ The liquid crystal alignment agent used in the present invention may also contain a cross-linking agent as component (C).

Examples of the cross-linking agent of component (C) include epoxy compounds, compounds having two or more amine groups, hydroxymethyl compounds, isocyanate compounds, phenolic plastic compounds, block isocyanate compounds and other low molecular compounds, and N-alkanes Polymers such as polymers of oxymethacrylamide, polymers of compounds with epoxy groups, polymers of compounds with isocyanate groups, etc.

Specific examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and neopentyl glycol. Alcohol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 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 alkane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, etc.

Examples of compounds having two or more amine 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, and 4,4' -Diamino-3,3'-dimethyldicyclohexylamine, isophorone diamine, 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, etc.

Examples of aromatic-aliphatic diamines include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, and 4-amino-N -Methylbenzylamine, 3-aminophenylethylamine, 4-aminophenylethylamine, 3-amino-N-methylphenylethylamine, 4-amino-N-methylbenzene Ethylamine, 3-(3-aminopropyl)aniline, 4-(3-aminopropyl)aniline, 3-(3-methylaminopropyl)aniline, 4-(3-methylamine methylpropyl)aniline, 3-(4-aminobutyl)aniline, 4-(4-aminobutyl)aniline, 3-(4-methylaminobutyl)aniline, 4-(4-methyl methylaminobutyl)aniline, 3-(5-aminopentyl)aniline, 4-(5-aminopentyl)aniline, 3-(5-methylaminopentyl)aniline, 4-(5 -Methylaminopentyl)aniline, (6-amino-2-naphthyl)methylamine, (6-amino-3-naphthyl)methylamine, 2-(6-amino-2- Naphthyl)ethylamine, 2-(6-amino-3-naphthyl)ethylamine, etc.

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 alkane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, etc. .

Specific examples of the methylol compound include compounds such as alkoxymethylated urea, alkoxymethylated benzoguanamine, and alkoxymethylated melamine.

Specific examples of alkoxymethylated ureas include 1,3,4,6-quaternary (methoxymethyl)acetylene urea and 1,3,4,6-quaternary (butoxymethyl)acetylene. Urea, 1,3,4,6-(hydroxymethyl)acetylene urea, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-(butoxymethyl)urea, 1 ,1,3,3-bis(methoxymethyl)urea, 1,3-bis(hydroxymethyl)-4,5-dihydroxy-2-imidazolinone, and 1,3-bis(methoxymethyl) (Methyl)-4,5-dimethoxy-2-imidazolinone, etc. Examples of commercially available products include compounds such as acetylene urea compounds (trade names: Cymel (registered trademark) 1170, Powderlink (registered trademark) 1174) manufactured by Daicel-Allnex Co., Ltd., and methylated urea resin (trade name: UFR (registered trademark) )65), butylated urea resin (trade name: UFR (registered trademark) 300, U-VAN10S60, U-VAN10R, U-VAN11HV), DIC Co., Ltd. urea/formaldehyde resin (high condensation type, trade name : Amidir (registered trademark) J-300S, same as P-955, same as N), etc.

Specific examples of the alkoxymethylated benzoguanamine include tetramethoxymethylbenzoguanamine. Examples of commercially available products include Daicel-Allnex Co., Ltd. (trade name: Cymel (registered trademark) 1123), Sanwa Chemical Co., Ltd. (trade name: Nikalac (registered trademark)) BX-4000, the same BX-37, the same BL-60, same as BX-55H), etc.

Specific examples of alkoxymethylated melamine include hexamethoxymethylmelamine. Examples of commercially available products include methoxymethyl melamine compounds (trade names: Cymel (registered trademark) 300, Cymel 301, Cymel 303, Cymel 350) manufactured by Daicel-Allnex Co., Ltd., and butoxymethyl melamine compounds ( Trade name: Mycoat (registered trademark) 506, same as 508), methoxymethyl melamine compound manufactured by Sanwa Chemical (trade name: Nikalac (registered trademark) MW-30, same as MW-22, same as MW-11, same as MW-11) MS-001, same as MX-002, same as MX-730, same as MX-750, same as MX-035), butoxymethyl melamine compound (trade name: Nikalac (registered trademark) MX-45, same as MX-410 , the same as MX-302), etc.

Alternatively, the compound may be a compound obtained by condensing a melamine compound, a urea compound, an acetylene urea compound, and a benzoguanamine compound in which the hydrogen atom of the amino group is substituted with a hydroxymethyl group or an alkoxymethyl group. For example, a high molecular weight compound produced from a melamine compound and a benzoguanamine compound described in US Pat. No. 6,323,310 can be cited. Examples of commercially available products of the aforementioned melamine compound include trade name: Cymel (registered trademark) 303 (manufactured by Daicel-Allnex Co., Ltd.), etc. Examples of commercially available products of the aforementioned benzoguanamine compound include trade name: Cymel (registered trademark) )1123 (Daicel-Allnex (stock) system), etc.

Specific examples of the isocyanate compound include VESTANAT B1358/100, VESTAGON BF 1540 (the above, isocyanate-type modified polyisocyanate, manufactured by Evonik Japan Co., Ltd.), Takenate (registered trademark) B-882N, and the same B-7075 (above, isocycyanurate-type modified polyisocyanate, manufactured by Mitsui Chemicals Co., Ltd.), etc.

Specific examples of the novolac plastic compound include the following compounds, but the novolac plastic compound is not limited to the following compound examples.

Specific examples of the compound having two or more hydroxyalkylamide groups at the molecular terminal include the following compounds and Primid QM-1260 and SF-4510 (the above, manufactured by EMS-GRILTECH).

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

Furthermore, examples of the polymer of N-alkoxymethacrylamide include N-hydroxymethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, Acrylamide compounds or methyl groups substituted by hydroxymethyl or alkoxymethyl, such as N-ethoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, etc. Polymer made from acrylamide compounds.

Specific examples of such polymers include poly(N-butoxymethacrylamide), copolymers of N-butoxymethacrylamide and styrene, and N-hydroxymethylmethacrylamide. Copolymers of amide and methyl methacrylate, copolymers of N-ethoxymethylmethacrylamide and benzyl methacrylate, and N-butoxymethacrylamide and methacrylic acid Copolymer of benzyl ester and 2-hydroxypropyl methacrylate, etc. The weight average molecular weight of such a polymer is 1,000~200,000, more preferably 3,000~150,000, still more preferably 3,000~50,000.

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

Specific examples of such polymers include poly(3,4-epoxycyclohexylmethyl methacrylate), poly(glycidyl methacrylate), glycidyl methacrylate, and methyl methacrylate. Copolymers of esters, copolymers of 3,4-epoxycyclohexylmethyl methacrylate and methyl methacrylate, copolymers of glycidyl methacrylate and styrene, etc. The weight average molecular weight of such a polymer is 1,000~200,000, more preferably 3,000~150,000, still more preferably 3,000~50,000.

Examples of the polymer of the compound having an isocyanate group include 2-isocyanatoethyl methacrylate (Karenz MOI [registered trademark], manufactured by Showa Denko Co., Ltd.) and 2-isocyanatoethyl acrylate. (Karenz AOI [registered trademark], Showa Denko Co., Ltd.) and other compounds having an isocyanate group, or 2-(O-[1'-methylpropyleneamino]carboxylamino)ethyl methacrylate (Karenz MOI-BM [registered trademark], manufactured by Showa Denko Co., Ltd.), 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate (Karenz MOI-BP [registered trademark] ], Showa Denko Co., Ltd.) and other compounds with blocked isocyanate groups made of polymers.

Specific examples of such polymers include poly(2-isocyanatoethyl acrylate) and poly(2-(methacrylate)(O-[1'-methylpropyleneamine]carboxylamino) Ethyl ester), copolymer of 2-isocyanatoethyl methacrylate and styrene, 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate and methacrylic acid Methyl ester copolymer, etc. The weight average molecular weight of such a polymer is 1,000~200,000, more preferably 3,000~150,000, still more preferably 3,000~50,000.

These cross-linking agents can be used alone or in combination of two or more.

When the liquid crystal alignment agent used in the present invention contains the cross-linking agent of component (C), the content is preferably 1 to 100 parts by mass, and more preferably 1 to 80 parts by mass relative to 100 parts by mass of the resin of component (A). 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 so as to be suitable for the formation of a liquid crystal alignment film. That is, the liquid crystal alignment agent of the present invention is preferably prepared as a solution in which the resin component for forming the resin film is dissolved in an organic solvent. Here, the resin component refers to the specific polymer of component (A) already described and the polymer of component (B) if necessary. At this time, the total content of the specific polymer of component (A) and the polymer content of component (B) is preferably 0.5 to 20 mass %, more preferably 1, based on the entire liquid crystal alignment agent. ~20% by mass, more preferably 1~15% by mass, particularly preferably 1~10% by mass.

＜Solvent＞ The solvent contained in the liquid crystal alignment agent used in the present invention is not particularly limited as long as it can dissolve component (A), component (B) and component (C) 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. Moreover, even if it is not a solvent that dissolves component (A) or (B), it can be used in combination with a solvent that dissolves component (A) or (B). At this time, if the surface energy of the solvent that does not dissolve component (A) or (B) is lower than that of the solvent that dissolves component (A) or (B), the coating property of the liquid crystal alignment agent to the substrate can be improved, so Better.

Specific examples include water, N-alkyl-2-pyrrolidinones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, and N,N-dimethylformamide. Amine, N,N-dimethylacetamide, N-methylcaprolactam, tetramethylurea, 3-methoxy-N,N-dimethylpropionamide, 3-ethoxy- Dialkyl imidazolinones such as N,N-dimethylpropylamide, 3-butoxy-N,N-dimethylpropylamide, 1,3-dimethyl-2-imidazolinone, etc. , Lactones such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, etc., carbonates such as ethyl carbonate, propylene carbonate, etc., methanol, ethanol, propanol, isopropyl alcohol, 3 -Methyl-3-methoxybutanol, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, isopentyl methyl ketone, methyl isopropyl ketone, diisobutyl ketone, Ketones such as cyclohexanone, cyclopentanone, methyl isobutyl ketone, 4-hydroxy-4-methyl-2-pentanone, compounds represented by the following formula (Sv-1) and the following formula (Sv -2) Compounds represented by 4-methyl-2-pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, 2-methylcyclohexyl acetate, butyric acid Butyl ester, isoamyl butyrate, diisobutylmethanol, diisoamyl ether, etc.

In the formulas (Sv-1) ~ (Sv-2), Y ₁ and Y ₂ are independently hydrogen atoms or monovalent hydrocarbon groups with 1 to 6 carbon atoms, X ₁ is an oxygen atom or -COO-, and X ₂ is a single bond or a carbonyl group, and R ₁ is an alkanediyl group with 2 to 4 carbon atoms. n ₁ is an integer from 1 to 3. When n ₁ is 2 or 3, the plurality of R ₁ 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 the formula (Sv-1), the monovalent hydrocarbon groups of Y ₁ and Y ₂ having 1 to 6 carbon atoms include, for example, monovalent chain hydrocarbon groups with 1 to 6 carbon atoms and monovalent hydrocarbon groups with 1 to 6 carbon atoms. Alicyclic hydrocarbon groups and monovalent aromatic hydrocarbon groups with 1 to 6 carbon atoms, etc. Examples of monovalent chain hydrocarbon groups having 1 to 6 carbon atoms include alkyl groups having 1 to 6 carbon atoms. The alkanediyl group of R ₁ may be linear or branched.

In the formula (Sv-2), examples of the divalent hydrocarbon group having 1 to 6 carbon atoms in Z ₁ include an alkanediyl group having 1 to 6 carbon atoms. Examples of the monovalent hydrocarbon groups of Y ₃ and Y ₄ having 1 to 6 carbon atoms include monovalent chain hydrocarbon groups with 1 to 6 carbon atoms, monovalent alicyclic hydrocarbon groups with 1 to 6 carbon atoms, and monovalent hydrocarbon groups with 1 to 6 carbon atoms. 6-valent aromatic hydrocarbon groups, etc. Examples of monovalent chain hydrocarbon groups having 1 to 6 carbon atoms include alkyl groups having 1 to 6 carbon atoms.

Specific examples of the solvent represented by formula (Sv-1) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, and ethylene glycol-i-propyl. Ether, ethylene glycol monobutyl ether (butyl cellulose), ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, ethylene glycol monoacetate, ethylene glycol diacetate, ethylene glycol Alcohol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether 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, 3-ethoxybutyl acetate, etc.; Specific examples of the solvent represented by (Sv-2) include methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate, butyl lactate, isopentyl lactate, and ethyl-3-propionate. Ethoxyester, methyl-3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate , 3-methoxybutylpropionate, etc.

The aforementioned solvent preferably has a boiling point of 80 to 200°C. More preferably, it is 80~180°C. Preferable solvents include N,N-dimethylformamide, tetramethylurea, 3-methoxy-N,N-dimethylpropylamide, and 1-propylamide. Alcohol, isopropyl alcohol, 3-methyl-3-methoxybutanol, ethyl amyl ketone, methyl ethyl ketone, isopentyl 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, acetic acid Cyclohexyl ester, 2-methylcyclohexyl acetate, butyl butyrate, isoamyl butyrate, diisobutylmethanol, diisoamyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol monobutyl ether (butyl cellulose), ethylene glycol dimethyl ether, ethylene glycol monoethyl ether Acid ester, 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 acetic acid Esters, 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-ethoxy propionate, methyl-3-methoxy propionate, ethyl 3-methoxypropionate, etc. The boiling point is within this range, which is particularly preferred when the liquid crystal alignment agent containing the aforementioned solvent is coated on a plastic substrate described later.

＜Other ingredients＞ The liquid crystal alignment agent used in the present invention may also contain other components other than the above-mentioned component (A) and, if necessary, component (B) and component (C). Examples of such other components include cross-linking catalysts, compounds that improve film thickness uniformity or surface smoothness when applying the liquid crystal alignment agent, compounds that improve the adhesion between the liquid crystal alignment film and the substrate, etc., but are not limited thereto. .

＜Cross-linking catalyst＞ For the purpose of promoting the reaction between the oxazoline skeleton and the carboxyl group, a cross-linking catalyst can also be added to the liquid crystal alignment agent used in the present invention. Examples of such cross-linking catalysts include p-toluenesulfonic acid, camphorsulfonic acid, trifluoromethanesulfonic acid, p-phenolsulfonic acid, 2-naphthalenesulfonic acid, mesitylenesulfonic acid, and 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, penta Sulfonic acids such as fluoroethanesulfonic acid, nonafluorobutane-1-sulfonic acid, dodecylbenzenesulfonic acid, or their hydrates or salts, etc. Examples of compounds that generate acids by heat include 1,2-bis(toluenesulfonyloxy)ethane, 1,3-bis(toluenesulfonyloxy)propane, and 1,4-bis(toluenesulfonyloxy)propane. Oxy)butane, p-nitrobenzyl toluenesulfonate, o-nitrobenzyl toluenesulfonate, p-pyridinium toluenesulfonate, p-morpholinium toluenesulfonate, p-toluene Ethyl sulfonate, p-propyl toluenesulfonate, p-butyl toluenesulfonate, p-isobutyl toluenesulfonate, p-methyl toluenesulfonate, p-phenylethyl toluenesulfonate, p-toluene Cyanomethyl sulfonate, 2,2,2-trifluoroethyl p-toluenesulfonate, 2-hydroxybutyl p-toluenesulfonate, N-ethyl-p-toluenesulfonamide, etc.

[Compounds that improve film thickness uniformity or surface smoothness] Examples of compounds that improve film thickness uniformity or surface smoothness include fluorine-based surfactants, polysiloxane-based surfactants, and nonionic surfactants. Specific examples include Eftop (registered trademark) 301, EF303, EF352 (manufactured by Mitsubishi Materials Electronics Corporation), Megaface (registered trademark) F171, F173, R-30 (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by Mitsubishi Materials Electronics Corporation), 3M Company), Asahiguard (registered trademark) AG710 (manufactured by AGC Company), Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC SEIMI CHEMICAL Company), etc. The usage ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass relative to 100 parts by mass of the resin component contained in the polymer composition.

[Compounds that improve the adhesion between the liquid crystal alignment film and the substrate] Specific examples of compounds that improve the adhesion between the liquid crystal alignment film and the substrate include the following compounds containing functional silane. Examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N -(2-Aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureido Propyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyl Triethoxysilane, N-3-triethoxysilylpropyltriethylenetetramine, N-3-trimethoxysilylpropyltriethylenetetramine, 10-trimethoxysilyl-1,4 ,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, acetic acid 9-Triethoxysilyl-3,6-diazanonyl ester, N-benzyl-3-aminopropyltrimethoxysilane, N-phenylmethyl-3-aminopropyltriethyl Oxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane and other compounds containing amino silane. When a compound that improves adhesion to the substrate is used, the usage amount is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass relative to 100 parts by mass of the resin component contained in the polymer composition. .

In one embodiment, in order to improve the photoreactivity of the photoalignment group, a photosensitizer can also be used as an additive. Specific examples include aromatic 2-hydroxyketone (benzophenone), coumarin, ketocoumarin, carbonyl dicoumarin, acetophenone, anthraquinone, xanthinone, thioxanthone, and phenethyl ketal etc.

<Liquid crystal alignment film and liquid crystal display element> After the liquid crystal alignment agent of the present invention is coated on a substrate and fired, it can be aligned by rubbing treatment or light irradiation, or it can be used in some vertical alignment applications without any Alignment treatment to become a liquid crystal alignment film. As the substrate, for example, glass made of float glass, soda glass, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polystyrene, polyether styrene, polycarbonate, Poly(alicyclic olefin), polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polystyrene (PSF), polyether styrene (PES), polyamide, polyimide, Transparent substrate made of plastics such as acrylic and triacetyl cellulose. As the transparent conductive film provided on one side of the substrate, NESA film (registered trademark of U.S. PPG Company) made of tin oxide (SnO ₂ ) or indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) can be used. ITO film, etc.

＜Coating film formation steps＞ The coating method of the liquid crystal alignment agent of the present invention is not particularly limited. It can be screen printing, flexographic printing, lithography, inkjet, dip coating, roller coating, slit coating, spin coating, etc., and can be used according to the purpose. And so on. After coating on the substrate by these methods, the solvent is evaporated by heating means such as a hot plate to form a coating film.

The firing after coating the liquid crystal alignment agent can be performed at any temperature from 40 to 300°C, preferably 40°C to 250°C, and more preferably 40°C to 230°C. The film thickness of the coating film formed on the substrate is preferably 5~1,000nm, more preferably 10~500nm or 10~300nm. This firing can be performed using a heating plate, hot air circulation furnace, infrared furnace, etc. For friction treatment, nylon cloth, nylon cloth, cotton cloth, etc. can be used.

＜Light irradiation step＞ In one embodiment, alignment treatment caused by light irradiation can be performed, which can include, for example, the step of applying the above-mentioned liquid crystal alignment agent on the substrate to form a coating film, and in a state where the coating film is not in contact with the liquid crystal layer or with the liquid crystal layer. The step of irradiating the aforementioned coating film with light while the liquid crystal layer is in contact with the liquid crystal layer.

Examples of the light irradiated in the alignment process by light irradiation include ultraviolet rays and visible rays containing light with a wavelength of 150 to 800 nm. Among these, ultraviolet rays containing light with a wavelength of 300 to 400 nm are preferred. The irradiation light may be polarized light or non-polarized light. As the polarized light, light including linearly polarized light is preferably used.

When the light used is polarized light, the light irradiation can be carried out in a vertical direction to the substrate surface, or in an oblique direction, or in a combination of these. When irradiating non-polarized light, it is best to irradiate the substrate surface in an oblique direction. 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 still more preferably 2 to 200 mJ/cm ² .

The liquid crystal display element of the present invention can be manufactured by a common method, and the manufacturing method is not particularly limited. It is preferable that the pair of substrates face each other with an appropriate gap so that the thickness of the liquid crystal sandwiched between the substrates becomes uniform, and a spacer is disposed between the substrates. As the spacer, known spacer materials such as conventional spread-type spacers and spacers formed from a photosensitive spacer-forming composition can be used. In addition, a layer formed of a liquid crystal cured material can also be used. The concave and convex parts serve as spacers.

＜LCD clamping steps＞ To sandwich a liquid crystal between substrates to form a liquid crystal cell, the following two methods can be cited, for example. The first method includes arranging a pair of substrates facing each other across a gap (cell gap) so that the liquid crystal alignment films face each other, bonding the peripheral portions of the pair of substrates using a sealant, and attaching the substrates to each other via the substrates. A method of manufacturing a liquid crystal cell by injecting filling liquid crystal into the cell gap separated by the surface and an appropriate sealant, and then sealing the injection hole.

The second method may be to apply a UV-curable sealant on a specific location on one of the two substrates on which the liquid crystal alignment film is formed, and further drop it on several specific locations on the surface of the liquid crystal alignment film. After the liquid crystal is produced, the liquid crystal alignment film is attached to the other substrate in a facing manner, and the liquid crystal is evenly spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant to create a liquid crystal cell. method (ODF (One Drop Fill) method).

As the liquid crystal, fluorine-based liquid crystal or cyano-based liquid crystal having positive or negative dielectric anisotropy, or a liquid crystal compound or liquid crystal composition polymerized by at least one of heating and light irradiation can be used depending on the application. substance (hereinafter also referred to as polymerizable liquid crystal or curable liquid crystal composition). In one embodiment, the aforementioned step of forming a coating film of the liquid crystal alignment agent can be performed by a roll-to-roll method. If it is carried out by the roll-to-roll method, the manufacturing steps of the liquid crystal display element can be simplified and the manufacturing cost can be reduced. Then, by attaching polarizing plates to both outer surfaces of the liquid crystal cell, a liquid crystal display element can be obtained.

Examples of the polarizing plate used outside the liquid crystal cell include a polarizing film called an "H film" that absorbs iodine while stretching and aligning polyvinyl alcohol, sandwiched between a cellulose acetate protective film, or a polarizing plate made of Polarizing plates composed of H film itself, etc. As mentioned above, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention has good liquid crystal alignment properties, excellent pretilt angle display ability, and can obtain high reliability. In addition, the liquid crystal display element manufactured by the method of the present invention has excellent display characteristics. [Example]

The following examples are given to illustrate the present invention in detail, but the present invention is not limited to these examples. The abbreviations of the compounds and the methods for measuring each characteristic are as follows. Boc represents tert-butoxycarbonyl.

＜Methacrylic acid monomer＞ (Photo-alignment monomer) MA-1 is synthesized according to the synthesis method described in the patent document (WO2017/115790).

(monomer containing carboxyl group) MAA: methacrylic acid

(Monomer containing oxazoline skeleton)

＜Tetracarboxylic dianhydride monomer＞ A1~A8: Compounds represented by the following formulas [A1]~[A8] respectively

＜Side chain diamine monomer＞ B1~B14: Compounds represented by the following formulas [B1]~[B14] respectively

＜Other diamine monomers＞ C1~C20: Compounds represented by the following formulas [C1]~[C20] respectively

(Crosslinking agent ingredient) D1~D3: Compounds represented by the following formulas [D1]~[D3] respectively

(polymerization initiator) AIBN: Azobisisobutyronitrile (solvent) NMP: N-methyl-2-pyrrolidone BCS: Dinkycellosu THF: Tetrahydrofuran

＜Measurement of molecular weight＞ The molecular weight of the polymer in the synthesis example was measured using a normal temperature gel permeation chromatography (GPC) device (SSC-7200 manufactured by Senshu Scientific Co., Ltd., and a column (KD-803, KD-805) manufactured by Shodex Co., Ltd.) as follows. General measurement. Column temperature: 50°C, eluent: DMF (as an additive, lithium bromide-hydrate (LiBr･H ₂ O) is 30mmol/L, phosphoric acid･anhydrous crystal (o-phosphoric acid) is 30mmol/L, THF (10ml/L), flow rate: 1.0mL/min. Standard samples used to prepare the calibration curve: TSK standard polyethylene oxide manufactured by Tosoh Corporation (molecular weight approximately 900,000, 150,000, 100,000, 30,000), and polyethylene manufactured by Polymer Laboratories. Diols (molecular weight approximately 12,000, 4,000, 1,000).

<Measurement of acyl imidization rate> The acyl imidization rate in the synthesis examples was measured as follows. Place 20 mg of polyimide powder into an NMR sample tube (NMR standard sampling tube φ5 manufactured by Kusano Scientific Co., Ltd.), add 1.0 mL of deuterated dimethylsterine (DMSO-d ₆ , 0.05% TMS mixture), and apply ultrasonic waves Allow to dissolve completely. This solution was measured for proton NMR at 500 MHz using an NMR meter (JNW-ECA500) manufactured by JEOL Datum Corporation. The rate of imidization is determined by using the proton derived from the structure that does not change before and after the imidization as the reference proton, and using the peak integrated value of the proton and the NH group derived from the amide acid that appears around 9.5~10.0ppm. The integrated value of the proton wave peak is obtained by the following formula. Furthermore, in the following formula, x is the proton peak integrated value derived from the NH group of amide acid, y is the peak integrated value of the reference proton, and α is the polyamide acid (imidation rate: 0%) In this case, the ratio of the number of reference protons to one proton of the NH group of amide acid.

＜Synthesis of Monomer＞ MB-1 is a novel compound that has not been disclosed in the literature, and its synthesis method is detailed in the following Monomer Synthesis Example 1.

<Measurement of ¹ H-NMR> Equipment: Fourier transform superconducting nuclear magnetic resonance device (FT-NMR) "AVANCE III" (manufactured by BRUKER Corporation) 500 MHz. Solvent: deuterated dimethylsulfoxide (DMSO-d ₆ ). Standard material: tetramethylsilane (TMS).

(Monomer synthesis example 1: synthesis of [MB-1])

(Synthesis of [MB-1-1]) Using 4-hydroxybenzonitrile as raw material, [MB-1-1] was obtained by the same method as the literature (Organic Letters, 14(23), 5900-5903; 2012).

(Synthesis of [MB-1-2]) Into a 2000mL 4-mouth eggplant-shaped flask, add 1,2-dichlorobenzene (428g), MB-1-1 (42.8g, 262mmоl), 2-amino-2-methyl-1-propanol (70.1 g), and zinc chloride (17.9g), react under heating conditions of 150°C in a nitrogen environment for 24 hours to make the raw materials disappear. After the reaction, the reaction solution was returned to room temperature, chloroform (428g), pure water (642g), and ethylenediamine (31.5g) were added, and liquid separation was performed. Next, the organic phase was washed twice with pure water (500 g), and then the organic phase was recovered. The recovered organic phase was concentrated under reduced pressure to an internal weight of 532g, hexane (1470g) was added to precipitate the crystals, separated by filtration and dried to obtain white crystals of [MB-1-2] (yield: 50.6g, product rate: 82%).

(Synthesis of [MB-1]) In a 1000 mL 4-mouth eggplant-shaped flask, add tetrahydrofuran (300g), MB-1-2 (30.0g, 128mmоl), triethylamine (25.9g), and 2, 6-Di-tert-butyl-p-cresol (84.6 mg), and methacrylic acid chloride (14.7 g) were dropped under ice-cooling conditions in a nitrogen environment. After dropping, react at room temperature overnight to make the raw materials disappear. After the reaction, the reaction solution was poured into pure water (1800 g) to precipitate crystals, and the crude crystals were recovered by filtration. The crude crystal was dissolved in ethyl acetate and dehydrated using magnesium sulfate. Next, the ethyl acetate solution was concentrated under reduced pressure so that the internal weight became 86.7g. Hexane (270g) was added to precipitate the crystals, which were separated by filtration and dried to obtain white crystals of [MB-1] (yield: 22.9g, Yield: 59%). ¹ H-NMR (500 MHz, DMSO-d ₆ ): δ (ppm) = 7.76-7.79 (m, 2H), 7.01-7.04 (m, 2H), 6.03 (s, 1H), 5.70 (s, H) , 4.43-4.45 (m, 2H), 4.06-4.32(m, 2H), 4.06(s, 2H), 1.88(s, 3H), 1.26(s, 6H)

＜Synthesis of polymethacrylate＞ (Synthesis example 1) MA-1 (3.04g, 6.00mmol), MB-1 (1.52g, 5.00mmol) and MAA (0.77g, 9.00mmol) were dissolved in NMP (31.1g), degassed with a diaphragm pump, and then added as The polymerization initiator AIBN (0.16g, 0.97mmol) was degassed again. Thereafter, the reaction was carried out at 60° C. for 13 hours in a nitrogen environment to obtain a polymer solution. Next, NMP (5.0g) and BCS (6.0g) were added to the polymer solution (4.0g) and stirred at room temperature to obtain a polymethacrylate solution (MP1). The polymer has a number average molecular weight of 32,000 and a weight average molecular weight of 121,000.

(Synthesis example 2) According to the composition shown in Table 1, the polymethacrylate solution (MP2) was synthesized using the same method as polymer synthesis example 1.

＜Synthesis of polyamide＞ (Synthesis example 3) Dissolve B1 (2.28g, 6.00mmol), C2 (1.22g, 8.00mmol), C7 (1.45g, 6.00mmol) and A1 (2.23g, 11.4mmol) in NMP (27.2g) and react at 60°C 5 Hours later, A2 (1.00g, 4.00mmol) and A4 (0.87g, 4.00mmol) and NMP (9.1g) were added, and the polyamide solution with a solid content concentration of 20 mass% was obtained by reacting at 40°C for 10 hours ( PAA-1A). NMP (20.0g) and BCS (20.0g) were added to the obtained polyamic acid solution (10.0g), and stirred at room temperature for 2 hours to obtain a polyamic acid solution (PAA) with a solid content concentration of 4.0% by mass. -1).

(Synthesis Examples 4~21) With the composition shown in Table 2, using the same method as Synthesis Example 3, polyamide solutions (PAA-2A) to (PAA-19A) with a solid content concentration of 20 mass% and polyamide solutions with a solid content concentration of 4.0 mass% were synthesized. Amino acid solution (PAA-2)~(PAA-19).

＜Synthesis of polyimide＞ (Synthesis Example 22) NMP was added to the polyamide solution (PAA-1A) (15g), and after diluting to a solid content concentration of 6.5% by mass, acetic anhydride (2.6g) and pyridine (0.81g) were added as imidization catalysts. React at 75°C for 2.5 hours. The reaction solution was poured into methanol (210 mL), and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain polyimide powder (E). The polyimide has an imidization rate of 75%, a number average molecular weight of 12,400, and a weight average molecular weight of 42,500. NMP (14.7g) was added to the obtained polyimide powder (E) (2.0g), and the mixture was stirred at 70° C. for 20 hours to dissolve. NMP (13.3g) and BCS (20.0g) were added to this solution, and a polyimide solution (SPI-1) was obtained by stirring at room temperature for 5 hours.

(Synthesis Examples 23~40) The polyamic acid solutions (PAA-2A) to (PAA-19A) obtained in Synthetic Examples 4 to 21 were used instead of the polyamic acid solution (PAA-1A), except that the method was the same as Synthetic Example 22. Synthesis of polyimide solutions (SPI-2)~(SPI-19).

＜Preparation of liquid crystal alignment agent＞ (Example 1) D3 (0.04g) was added to the polymethacrylate solution (MP1) (10.0g) obtained in Synthesis Example 1, and the liquid crystal alignment agent (PM1) was obtained by stirring at room temperature.

(Example 2) To the polymethacrylate solution (MP1) (3.0g) obtained in Synthesis Example 1, the polyamide solution (PAA-1) (7.0g) obtained in Synthesis Example 3 was added, and D3 (0.04g) was further added. , the liquid crystal alignment agent (PM2) was obtained by stirring at room temperature.

(Examples 3~20) As shown in Table 3, (PAA-2) ~ (PAA-19) were used to replace the polyamide solution (PAA-1). Otherwise, the same procedure as Example 2 was performed to obtain a liquid crystal alignment agent. (PM3)~(PM20).

(Example 21) The polyimide solution (SPI-1) (7.0g) obtained in Synthesis Example 22 was added to the polymethacrylate solution (MP1) (3.0g) obtained in Synthesis Example 1, and D3 (0.04g) was further added. , the liquid crystal alignment agent (PM21) was obtained by stirring at room temperature.

(Examples 22~39) As shown in Table 3, (SPI-2) ~ (SPI-19) were used to replace the polyimide solution (SPI-1). Otherwise, the same procedure as in Example 21 was performed to obtain a liquid crystal alignment agent. (PM22)~(PM39).

(Examples 40~41) As shown in Table 3, (D1) ~ (D2) are used to replace the cross-linking agent component (D3). Otherwise, the same procedure as in Example 2 is performed to obtain liquid crystal alignment agents (PM40) ~ (PM41) .

(Comparative example 1) D3 (0.04g) was added to the polymethacrylate solution (MP2) (10.0g) obtained in Synthesis Example 2 and stirred at room temperature to obtain a liquid crystal alignment agent (RPM1).

(Comparative example 2) The polyamide solution (PAA-1) (7.0g) obtained in Synthesis Example 3 was added to the polymethacrylate solution (MP2) (3.0g) obtained in Synthesis Example 2, and D3 (0.04g) was further added. , the liquid crystal alignment agent (RPM2) was obtained by stirring at room temperature.

(Comparative example 3) The polyimide solution (SPI-1) (7.0g) obtained in Synthesis Example 22 was added to the polymethacrylate solution (MP2) (3.0g) obtained in Synthesis Example 2, and D3 (0.04g) was further added. , the liquid crystal alignment agent (RPM3) was obtained by stirring at room temperature.

<Preparation of liquid crystal display element> The liquid crystal alignment agents (PM1) ~ (PM41) obtained in the examples and the liquid crystal alignment agents (RPM1) ~ (RPM3) obtained in the comparative examples were pressurized through membrane filters with a pore diameter of 1 μm. Filter. The obtained solution was spin-coated on the ITO surface of a glass substrate with a transparent electrode composed of an ITO film, dried on a hot plate at 70°C for 90 seconds, and then fired on a hot plate at 200°C for 30 minutes to form a thick film. 100nm liquid crystal alignment film. Then, on the coating surface, with a polarizing plate in the middle, linearly polarized ultraviolet rays with a wavelength of 313 nm and an irradiation intensity of 4.3 mW/cm ² were irradiated to 50 mJ/cm ² at an angle of 40° from the normal direction of the substrate to obtain Liquid crystal alignment film substrate. Linearly polarized ultraviolet light is modulated by passing through a polarizing plate with a wavelength of 313nm after the ultraviolet light of a high-pressure mercury lamp passes through a band-pass filter with a wavelength of 313nm. Two of the above-mentioned substrates were prepared, and a 4 μm bead spacer was spread on the liquid crystal alignment film of one substrate, and then a sealant (XN-1500T manufactured by Mitsui Chemicals Co., Ltd.) was applied. Next, the other substrate is bonded so that the liquid crystal alignment film surface faces and the alignment direction becomes 180°, and then the sealant is thermally cured at 120° C. for 90 minutes to create an empty unit cell. Liquid crystal (MLC-3022, manufactured by Merck & Co., Ltd.) was injected into the empty unit cell by a 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 homogeneous phase treatment at 120° C. for 1 hour, and then the unit cell was observed with a polarizing microscope. It is considered good when there is no poor alignment such as light leakage or occurrence of abnormal areas, or when uniform liquid crystal driving is achieved when a voltage is 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 produced above was measured by the Mueller matrix method using AxoScan manufactured by Axo Metrix Company. It can be said that the larger the value of the inclination angle subtracted from 90° is, the higher the inclination display capability is. The evaluation results are shown in Table 4.

It can be seen from the results in Table 4 that the polymethacrylate solution obtained by copolymerizing the photoreactive monomer, the carboxyl group-containing monomer, and the oxazoline skeleton-containing monomer, or the polymethacrylate The liquid crystal alignment film obtained by using the liquid crystal alignment agent of the solution and the polyamide acid or polyimide solution has higher tilt display ability than the liquid crystal alignment film of the comparative example. Specifically, it is a comparison between Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 21 and Comparative Example 3. [Industrial applicability]

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 in liquid crystal display elements requiring durability such as for vehicle use.

Claims (7)

A liquid crystal alignment agent containing the following formula (pa-1) (in the formula, A represents a group selected from a fluorine atom, a chlorine atom, a cyano group, or an alkoxy group having 1 to 5 carbon atoms, Pyrimidine-2,5-diyl, pyridine-2,5-diyl substituted by a linear or branched chain alkyl residue (which is substituted by 1 cyano group or more than 1 halogen atom as appropriate), Thiophene-2,5-diyl, furan-2,5-diyl, 1,4- or 2,6-naphthylene or phenyl, R ₁ is a single bond, oxygen atom, -COO- or -OCO -, R ₂ is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group or a divalent condensed cyclic group, R ₃ is a single bond, an oxygen atom, -COO- or - OCO-, R ₄ is a linear or branched alkyl group with 1 to 40 carbon atoms or a monovalent organic group with 3 to 40 carbon atoms including an alicyclic group, and D represents an oxygen atom, a sulfur atom or -NR _d - (Here, R _d represents a hydrogen atom or an alkyl group with 1 to 3 carbon atoms), a is an integer from 0 to 3, and when a is 2 or more, the plurality of R ₁ and R ₂ independently have the above definitions; X and Y are independently a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group with 1 to 3 carbon atoms; * indicates the bonding position), a polymer represented by a photoalignment group, an oxazoline skeleton and a carboxyl group , as component (A); . The liquid crystal alignment agent of claim 1 further contains a polymer selected from polyimide and its precursors as component (B). The liquid crystal alignment agent of claim 1, wherein component (B) is a polymer having a tert-butoxycarbonyl group. The liquid crystal alignment agent of claim 1, wherein component (B) is a chemically imidized polymer. A liquid crystal alignment film formed by using the liquid crystal alignment agent in any one of claims 1 to 4. A method for manufacturing a liquid crystal alignment film, which includes the step of applying the liquid crystal alignment agent as claimed in any one of claim 1 to claim 4 on a substrate to form a coating film, and a step in which the coating film is not in contact with the liquid crystal layer The step of irradiating the aforementioned coating film with light while in contact with the liquid crystal layer. A liquid crystal display element provided with the liquid crystal alignment film of claim 5.