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

Abstract

This invention provides a liquid crystal alignment film with high tilt display capability, a liquid crystal display element having the same, and a liquid crystal alignment agent imparted thereto. This invention provides a liquid crystal alignment agent containing a polymer having a photoaligning group, an oxazoline backbone, and a carboxyl group, represented by the following formula (pa-1) (where A represents a phenyl group, R1 is a single bond, oxygen atom, etc., R2 is a divalent aromatic group, R3 is a single bond, oxygen atom, etc., R4 is a straight-chain 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, D represents an oxygen atom, sulfur atom, or -NR d-, a is an integer from 0 to 3, and * represents the bond position. Thermal crosslinking groups A and B are selected by a crosslinking reaction of thermal crosslinking groups A and B through heat). This polymer is used as component (A).

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained therefrom, and a liquid crystal display element having the obtained liquid crystal alignment film. More specifically, it relates to a liquid crystal alignment agent that imparts good liquid crystal alignment properties, excellent pretilt angle display capability, and a liquid crystal alignment film with high reliability, and a liquid crystal display element with excellent display quality. Prior Technology

[0002] 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 by coating a polyimide-based liquid crystal alignment agent, composed of a solution of polyamide (also known as polyamide), polyamide ester, or polyimide as a polyimide precursor, onto a substrate and forming a film. Furthermore, when the liquid crystal is aligned parallel or tilted relative to the substrate surface, a surface stretching process by friction is performed after film formation.

[0003] On the other hand, when the liquid crystal is aligned perpendicularly to the substrate (referred to as the vertical alignment (VA) method), a liquid crystal alignment film is obtained by introducing hydrophobic groups such as long-chain alkyl or cyclic groups or combinations of cyclic and alkyl groups (e.g., see Patent Document 1), steroid backbones (e.g., see Patent Document 2), etc., into the side chains of polyimide. In this case, when a voltage is applied between the substrates and the liquid crystal molecules tilt in a direction parallel to the substrate, it is necessary to tilt the liquid crystal molecules from the substrate normal direction toward a direction inward of the substrate plane. As a means to achieve this, for example, methods have been proposed such as providing protrusions on the substrate, providing slits in the display electrode, pre-tilting the liquid crystal molecules slightly from the substrate normal direction toward a direction inward of the substrate plane by friction (pre-tilting), and further, pre-tilting the liquid crystal by 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 with ultraviolet light (e.g., see Patent Document 3), etc.

[0004] In recent years, methods have been proposed for forming protrusions or slits in liquid crystal alignment control using the VA method, and for utilizing anisotropic photochemical reactions caused by polarized ultraviolet irradiation as an alternative to PSA technology (photoalignment method). That is, it is known that by irradiating a photoreactive, vertically aligned polyimide film with polarized ultraviolet light, alignment adjustment capability and pretilt angle manifestation are imparted, and the tilt direction of liquid crystal molecules when voltage is applied can be uniformly controlled (see Patent Document 4).

[0005] VA-type liquid crystal display elements are used in TVs and automotive displays due to their high contrast and wide viewing angle. TV-grade liquid crystal display elements sometimes use backlights that generate a lot of heat to achieve high brightness, while automotive-grade liquid crystal display elements, such as those used in car navigation systems or dashboards, are often used or placed in high-temperature environments for extended periods. Under such harsh conditions, as the pretilt angle gradually changes, it can cause problems such as failing to achieve the initial display characteristics or producing uneven display. Furthermore, the voltage holding characteristics and charge accumulation characteristics during liquid crystal driving are also affected by the liquid crystal alignment film. A low voltage holding rate results in reduced contrast, while a large charge accumulation to DC voltage can cause burn-in on the display. [Previous Technical Documents] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 3-179323 [Patent Document 2] Japanese Patent Application Publication No. 4-281427 [Patent Document 3] Japanese Patent No. 4504626 [Patent Document 4] Japanese Patent No. 4995267 Summary of the Invention

[0007] [The problem that the invention aims to solve]

[0008] The present invention is made in view of the above-mentioned facts, and its objective is to provide a liquid crystal alignment film that exhibits minimal change in pretilt angle even after prolonged driving, excellent display reliability, high voltage retention characteristics, and reduces charge accumulation, a liquid crystal display element having the same, and a liquid crystal alignment agent thereof. [Methods used to solve problems]

[0009] The inventors discovered that, as follows <x>The invention is of essential importance. <x>A liquid crystal alignment agent comprising a polymer having a photoaligning group represented by the following formula (pa-1), an oxazoline skeleton, and a carboxyl group as component (A).

[0010]

[0011] In the formula, A represents a group selected from fluorine, chlorine, and cyano groups, or a pyrimidin-2,5-diyl, pyridine-2,5-diyl, thiophene-2,5-diyl, furan-2,5-diyl, 1,4- or 2,6-naphthyl, or phenyl group substituted with an alkoxy group having 1 to 5 carbon atoms, a straight-chain or branched alkyl residue (which may be substituted with one or more halogen atoms, depending on the case). R1 ​​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 condensed cyclic group. R3 is a single bond, an oxygen atom, -COO-, or -OCO-. R4 is a straight-chain or branched alkyl group having 1 to 40 carbon atoms, or a monovalent organogroup having 3 to 40 carbon atoms including an alicyclic group. D represents an oxygen atom, a sulfur atom, or -NR. d- (here, R d represents a hydrogen atom or an alkyl group having 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 systems independently have the above definitions. X and Y systems are independently hydrogen atoms, fluorine atoms, chlorine atoms, cyano groups, or alkyl groups having 1 to 3 carbon atoms. * indicates the bond position. [Effects of the Invention]

[0012] The present invention provides liquid crystal alignment films and liquid crystal alignment agents with good liquid crystal alignment properties and excellent pretilt angle display capabilities. Furthermore, the liquid crystal display element manufactured by the method of the present invention has excellent display characteristics. Implementation

[0013] The liquid crystal alignment agent of the present invention contains a polymer having a photoalignment group represented by the above formula (pa-1), an oxazoline skeleton and a carboxyl group.

[0014] The polymer of component (A) contained in the liquid crystal alignment agent of the present invention has high light sensitivity, and therefore can exhibit alignment control capability even under low exposure polarized ultraviolet irradiation. Furthermore, the polymer of component (A) contains a carboxyl group and an oxazoline skeleton, allowing for cross-linking reactions of the polymer containing component (A) even with a short sintering time for the liquid crystal alignment agent. Consequently, when the photoalignment sites exhibit anisotropy through photoreaction, this anisotropy is easily retained (memorized) in the liquid crystal alignment film, thus improving the liquid crystal alignment and exhibiting the pretilt angle of the liquid crystal.

[0015] The constituent elements of this invention are described in detail below.

[0016] <(A) Ingredients: Specific Polymers> [Photoalignment group represented by formula (pa-1)] In this invention, the site within the molecule having the photoalignment group represented by the above formula (pa-1) can, for example, be represented by the following formula (a-1). Furthermore, this site can be derived from the structure of 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).

[0017]

[0018] In formula (pa-1), A represents a pyrimidin-2,5-diyl, pyridin-2,5-diyl, thiophene-2,5-diyl, furan-2,5-diyl, 1,4- or 2,6-naphthyl or phenyl group, substituted by a fluorine atom, chlorine atom, or cyano group, or by an alkoxy group having 1 to 5 carbon atoms, a straight-chain or branched-chain alkyl residue (which may be substituted by one or more halogen atoms, depending on the case). R1 ​​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 condensed cyclic group. R3 is a single bond, an oxygen atom, -COO- or -OCO-. 4 represents a straight-chain or branched alkyl group with 1 to 40 carbon atoms, or a monovalent organogroup 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 alkyl group with 1 to 3 carbon atoms). a is an integer from 0 to 3. When a is 2 or more, the plurality of R1 and R2 systems independently have the above definitions. X and Y systems are independently hydrogen atoms, fluorine atoms, chlorine atoms, cyano groups, or alkyl groups with 1 to 3 carbon atoms. * indicates the bond position.

[0019] In the above formula (a-1) or (a-1-m), Sa represents a spacer group, and Ia represents a spacer group arbitrarily bonded to the main chain of a specific polymer. S a can be represented, for example, by the structure of the following formula (Sp).

[0020]

[0021] In formula (Sp), The bonds to the left of W1 represent the bonds to Mb. The bond to the right of W3 represents the bond to Ia. W1, W2, and W3 represent, independently, single bonds, divalent heterocycles, -(CH2)n- (where n represents 1~20), -OCH2-, -CH2O-, -COO-, -OCO-, -CH=CH-, -CF=CF-, -CF2O-, -OCF2-, -CF2CF2-, or -C≡C-, but any non-orthogonal CH2 group among these substituents can independently undergo -O-, -CO-, -CO-O-, -O-CO-, or -Si(CH3)2-O-Si(CH3) 2-, -NR-, -NR-CO-, -CO-NR-, -NR-CO-O-, -OCO-NR-, -NR-CO-NR-, -CH=CH-, -C≡C- or -O-CO-O- (where R independently represents hydrogen or a straight-chain or branched alkyl group having 1 to 5 carbon atoms) substitution, A1 and A2 are respectively independently selected from single bond, divalent hydrocarbon group, divalent aromatic group, divalent alicyclic group and divalent heterocyclic group, and each group is unsubstituted or one or more hydrogen atoms may be substituted by fluorine atom, chlorine atom, cyano, methyl or methoxy atom.

[0022] In formula (a-1-m), Ma represents a polymerizable group. Examples of such polymerizable groups include free radical polymerizable groups of (meth)acrylates, fumarates, maleates, α-methylene-γ-butyrolactone, styrene, vinyl groups, maleimide, norcamphene, (meth)acrylamide and their derivatives, and siloxanes. Preferred are (meth)acrylates, α-methylene-γ-butyrolactone, styrene, vinyl groups, maleimide, and acrylamide. r is an integer satisfying 1 ≤ r ≤ 3. Mb is selected from single bond, heterocyclic group with (r+1) valence, straight-chain or branched hydrocarbon group with 1 to 10 carbon atoms with (r+1) valence, aromatic group with (r+1) valence, and alicyclic group with (r+1) valence. Each group is unsubstituted or one or more hydrogen atoms may be substituted by fluorine, chlorine, cyano, methyl or methoxy atoms.

[0023] Aromatic groups in A1, A2, and Mb can include, for example, aromatic hydrocarbons with 6-18 carbon atoms, such as benzene rings, biphenyl structures, and naphthalene rings. Some or all of the hydrogen atoms in the aforementioned benzene rings, biphenyl structures, and naphthalene rings can also be substituted with fluorine atoms. Alicyclic groups in A1, A2, and Mb can include, for example, alicyclic hydrocarbons with 6-12 carbon atoms, such as cyclohexane rings and bicyclohexane structures. Heterocyclic groups in A1, A2, and Mb can include nitrogen-containing heterocycles such as pyridine rings, piperidine rings, and piperazine rings. The hydrocarbon groups in A1 and A2 can be listed as straight-chain or branched hydrocarbon groups with 1 to 10 carbon atoms, preferably straight-chain or branched alkyl groups with 1 to 8 carbon atoms; more preferably methylene, ethyl, n-propyl, n-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl.

[0024] From the perspective of exhibiting good vertical alignment control and stable pretilt angle, the basis represented by (pa-1) above is preferably represented by (pa-1-a) below. Furthermore, this part can exemplify structures derived from monomers represented by the following formula (pa-1-ma), but is not limited to this.

[0025]

[0026] In formula (pa-1-a) or (pa-1-ma), Ma, Mb, and Sa are the same as defined above. Z represents either an oxygen atom or a sulfur atom. The Xa and Xb series 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. R1 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. R 3 is a single bond, an oxygen atom, -COO-, or -OCO-. R 4 is a straight-chain or branched alkyl group with 1 to 40 carbon atoms, or a monovalent organic group with 3 to 40 carbon atoms containing 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. When a is an integer from 0 to 3, and a is 2 or more, the complex R1 and R2 systems each independently have the above definitions. When b is an integer from 0 to 4, and b is 2 or more, the complex R5 systems each independently have the above definitions.

[0027] Sa is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably an alkyl group having 1 to 4 carbon atoms.

[0028] R2 is a divalent aromatic group, such as 1,4-epoxyphenyl, 2-fluoro-1,4-epoxyphenyl, 3-fluoro-1,4-epoxyphenyl, 2,3,5,6-tetrafluoro-1,4-epoxyphenyl, and epoxynaphthyl.

[0029] R2 is a divalent alicyclic group, such as trans-1,4-extincyclohexyl, trans-trans-1,4-extinbiscyclohexyl, etc.

[0030] R2 is a divalent heterocyclic group, such as pyridine-1,4-diyl, pyridine-2,5-diyl, furan-2,5-diyl, piperazine-1,4-diyl, piperidine-1,4-diyl, etc.

[0031] R2 is preferably 1,4-epenylphenyl, trans-1,4-epenylcyclohexyl, or trans-trans-1,4-epenylbiscyclohexyl.

[0032] R4 is a straight-chain or branched alkyl group having 1 to 40 carbon atoms, for example, straight-chain or branched alkyl groups having 1 to 20 carbon atoms, wherein some or all of the hydrogen atoms in the alkyl group may be substituted with fluorine atoms. Examples of this 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-pentadecanyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecanyl, n-eicosyl, 4,4,4-trifluorobutyl, 4,4,5,5,5-pentafluoropentyl, 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.

[0033] R4 is a monovalent organic group containing an alicyclic group with 3 to 40 carbon atoms, such as cholesterol, dihydrocholestanyl, adamantyl, or groups represented by the following formulas (Alc-1) or (Alc-2) (where R7 is a hydrogen atom, a fluorine atom, or an alkyl group with 1 to 20 carbon atoms, and some or all of the hydrogen atoms in the alkyl group with 1 to 20 carbon atoms may be substituted by fluorine atoms, and * indicates the bonding position).

[0034]

[0035] The monomer represented by the above formula (pa-1-ma) can be represented by compounds represented by formulas (paa-1-ma1) to (paa-1-ma18), but is not limited to these. Furthermore, in the formula, "E" indicates the E-body and "t" indicates that the cyclohexyl group is in the trans form.

[0036]

[0037]

[0038] [Oxazoline skeleton] To introduce the oxazoline skeleton into the polymer of component (A), it is only necessary to copolymerize the monomers having the oxazoline skeleton. Monomers having an oxazoline skeleton, for example, can be represented by compounds represented by the following formula (1-ma). In formula (1-ma), Ma, Mb, Sa, and r are defined as above, and I ox represents a monovalent group with an oxazoline skeleton.

[0039] As for the I ox, it is preferably a group with an oxazoline skeleton at the end, and more preferably an oxazoline-2-yl group that can be substituted by an alkyl group having 1 to 5 carbon atoms. Specifically, monomers represented by the following formulas (1-ma1) to (1-ma7) can be listed.

[0040]

[0041]

[0042] Such a monomer can be manufactured using nitrile compounds such as p-hydroxybenzonitrile and aminoethanol analogs such as 2-amino-2-methyl-1-propanol as starting materials, by the method described in the monomer synthesis examples below.

[0043] [carboxyl] To introduce carboxyl groups into the polymer of component (A), it is sufficient to copolymerize monomers containing carboxyl groups.

[0044] Monomers containing a carboxyl group include, for example, 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.

[0045] Furthermore, in this invention, when obtaining a specific polymer, in addition to the monomers with photoalignment groups, monomers with oxazoline skeletons, and monomers with carboxyl groups represented by the above formula (a-1-m), other monomers that can be copolymerized with these monomers can be used in combination.

[0046] Other specific examples of such monomers include acrylate compounds, methacrylate compounds, (meth)acrylate amine compounds, vinyl compounds, styrene compounds, maleimide compounds, acrylonitrile, maleic anhydride, and monomers having nitrogen-containing aromatic heterocyclic groups and polymerizable groups.

[0047] Examples of the aforementioned acrylate compounds include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthracene acrylate, anthraceneyl methyl acrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isocamphene acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofuran methyl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantane acrylate, 2-propyl-2-adamantane acrylate, 8-methyl-8-tricyclo[5.2.1.0<2,6>]decyl acrylate, and 8-ethyl-8-tricyclo[5.2.1.0<2,6>]decyl acrylate, etc.

[0048] Examples of the aforementioned methacrylate compounds include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthracene methacrylate, anthraceneyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isocamphenyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofuran methyl methacrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantane methacrylate, 2-propyl-2-adamantane methacrylate, 8-methyl-8-tricyclo[5.2.1.0<2,6>]decyl methacrylate, and 8-ethyl-8-tricyclo[5.2.1.0<2,6>]decyl methacrylate, etc.

[0049] The aforementioned (meth)acrylic acid amine compounds include, for example, acrylamide, methacrylic acid, N-methacrylic acid, N,N-dimethylacrylic acid, N,N-diethylacrylic acid, N-methoxymethyl (meth)acrylic acid, N-butoxymethyl (meth)acrylic acid, etc.

[0050] The aforementioned vinyl compounds include, for example, methyl vinyl ether, benzyl vinyl ether, vinyl naphthalene, vinyl carbazole, allyl glycidyl ether, and 3-vinyl-7-oxabicyclo[4.1.0]heptane. The aforementioned styrene compounds include, for example, styrene, methylstyrene, chlorostyrene, and bromostyrene. The aforementioned maleimine compounds include, for example, maleimine, N-methylmaleimine, N-phenylmaleimine, and N-cyclohexylmaleimine.

[0051] The nitrogen-containing aromatic heterocycle may be an aromatic hydrocarbon ring containing at least one, preferably one to four, aromatic hydrocarbon rings selected from the following formulas [Na] to [Nb] (where Z2 is a straight-chain or branched alkyl group having 1 to 5 carbon atoms).

[0052]

[0053] Specifically, examples include oxazole rings, thiazole rings, pyridine rings, pyrimidine rings, quinoline rings, isoquinoline rings, thiadiazole rings, pyrazine rings, triazine rings, pyrazine rings, phenoline rings, quinoxaline rings, benzothiazole rings, oxadiazole rings, and acridine rings. Furthermore, substituents containing heteroatoms may also be present on the carbon atoms of these nitrogen-containing aromatic heterocycles. Among these, pyridine rings are an example.

[0054] Monomers containing nitrogen-containing aromatic heterocyclic groups and polymerizable groups include, for example, 2-(2-pyridylcarbonyloxy)ethyl methacrylate, 2-(3-pyridylcarbonyloxy)ethyl methacrylate, and 2-(4-pyridylcarbonyloxy)ethyl methacrylate.

[0055] The other monomers used in this invention can be used alone or in combination of two or more monomers.

[0056] The photoreactive site represented by the above formula (pa-1) contained in the polymer of component (A) of the liquid crystal alignment agent of the present invention can be used alone or in combination of two or more sites.

[0057] The photoreactive portion represented by the above formula (pa-1) is preferably contained in proportions of 5-95 mol%, 10-60 mol%, or 15-50 mol% of all repeating units of the polymer of component (A).

[0058] The amount of the site containing the oxazoline skeleton introduced is preferably 5-50 mol%, 20-45 mol%, or 25-40 mol% of all repeating units of the polymer of component (A).

[0059] The amount of carboxyl group introduced is preferably 5-55 mol%, 20-50 mol%, or 25-45 mol% of all repeating units of the polymer of component (A).

[0060] The content of the structure derived from the other monomers mentioned above is preferably 0-40 mol%, 0-30 mol%, or 0-20 mol% of all repeating units of the polymer of component (A).

[0061] <Manufacturing Methods for Specific Polymers> The specific polymer of component (A) contained in the liquid crystal alignment agent of the present invention can be copolymerized with monomers having photoalignment groups represented by the above formula (pa-1), monomers having an oxazoline skeleton, monomers having carboxyl groups, and other monomers as desired.

[0062] The method for manufacturing the specific polymer of component (A) in this invention is not particularly limited, and commonly used industrial methods can be employed. Specifically, it can be manufactured by cationic polymerization, free radical polymerization, or anionic polymerization utilizing vinyl monomers. Among these, free radical polymerization is particularly preferred from the viewpoint of ease of reaction control. The polymerization initiator for free radical polymerization can be a known compound such as a free radical polymerization initiator or a reversible addition-crack chain transfer (RAFT) polymerization reagent.

[0063] Free radical thermal polymerization initiators are compounds that generate free radicals by heating them to temperatures above their decomposition temperature. Such free radical thermal polymerization initiators include, for example, 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, diisopropylphenyl peroxide, dilauryl peroxide, etc.), peroxy ketals (dibutylperoxycyclohexane, etc.), alkyl peroxy esters (peroxyneodecanoate-tert-butyl ester, peroxytrimethylacetic acid-tert-butyl ester, peroxy2-ethylcyclohexanoate-tert-pentyl ester, etc.), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), and azo compounds (azobisisobutyronitrile, and 2,2'-bis(2-hydroxyethyl)azobisisobutyronitrile, etc.).

[0064] Such free radical thermal polymerization initiators can be used alone or in combination of two or more.

[0065] Free radical photopolymerization initiators are not particularly limited to compounds that initiate free radical polymerization upon light irradiation. Examples of such free radical photopolymerization initiators include well-known compounds such as benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthine, thioxanthone, and isopropylxanthine. These compounds can be used alone or in combination of two or more. Free radical polymerization is not particularly limited and can use emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization, solution polymerization, etc.

[0066] (A) The solvent used in the polymerization reaction of a specific polymer of a component is not particularly limited as long as it can dissolve the resulting polymer. Specific examples can be listed in the section on <Solvents> below, such as N-alkyl-2-pyrrolidones, dialkyl imidazolinones, lactones, carbonates, ketones, compounds represented by formula (Sv-1) and compounds represented by formula (Sv-2), tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, dimethyl sulfoxide, etc. These solvents can be used alone or in combination. Furthermore, even solvents that do not dissolve the generated polymer can be mixed with the above solvents to a extent that the generated polymer will not precipitate. Furthermore, in free radical polymerization, oxygen in the solvent can hinder the polymerization reaction; therefore, it is preferable to use organic solvents that have been degassed to the extent possible.

[0067] The polymerization temperature for free radical polymerization can be selected from any temperature in the range of 30 to 150°C, preferably in the range of 50 to 100°C. Furthermore, 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 is initially carried out at a high concentration, after which an organic solvent can be added. In the above-mentioned free radical polymerization reaction, when the ratio of free radical polymerization initiator to monomer is relatively high, the molecular weight of the resulting polymer decreases; when it is relatively low, the molecular weight of the resulting polymer increases. Therefore, the ratio of free radical initiator to monomer is preferably 0.1~10 mol%. Furthermore, various monomer components, solvents, initiators, etc., can also be added during polymerization.

[0068] Polymer recycling When recovering the polymer generated from the reaction solution obtained through the above reaction, the reaction solution can be simply added to a poor solvent to precipitate the polymer. Poor solvents for precipitation include methanol, acetone, hexane, heptane, butylceroxoxene, heptane, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer precipitated in the poor solvent can be filtered and recovered, then dried at room temperature or under normal or reduced pressure. Furthermore, if the polymer recovered after precipitation is redissolved in an organic solvent and the reprecipitation recovery operation is repeated 2 to 10 times, impurities in the polymer can be reduced. Poor solvents in this case include, for example, alcohols, ketones, and hydrocarbons. Using three or more poor solvents selected from these sources further improves the purification efficiency, which is preferable.

[0069] (A) The molecular weight of the specific polymer of the component, when taking into account the strength of the resulting coating, the workability during coating formation and the uniformity of the coating, the weight average molecular weight determined by GPC (Gel Permeation Chromatography) is preferably 2,000 to 1,000,000, more preferably 5,000 to 100,000.

[0070] <(B) Ingredients> The liquid crystal alignment agent of the present invention may contain a polymer selected from polyimide and its precursors as component (B). By using a polymer containing component (B), further improvements in electrical properties such as increased voltage retention or suppression of residual charge accumulation can be achieved.

[0071] (B) The component is a polymer selected from polyimide and its precursors, preferably a polymer having at least one of the following groups: having at least one group selected from vertically aligned groups and tert-butoxycarbonyl groups, or being chemically imidized.

[0072] The polymer of component (B) is polyimide and its precursor (hereinafter also referred to as the polyimide component), and its surface energy is close to that of the polymer of component (A). Acrylic acid, like component (A), is generally low in polarity and has low surface energy. On the other hand, polyimide is highly polar and has high surface energy. However, when the difference in surface energy between these two components is too large, they cannot readily mix, resulting in aggregation. This leads to uneven films, collapse, or inhomogeneity, potentially causing a narrowing of the process margin. Therefore, by making the polyimide component less polar, the surface energy can be controlled to a value that is higher than that of the acrylic acid component, but with a smaller difference. Methods to reduce the polarity of the polyimide component include chemical imidization followed by mixing with component (A), or introducing side chains.

[0073] Examples of such polymers include polymers obtained by polymerizing a known tetracarboxylic acid derivative such as tetracarboxylic acid dianhydride with a known diamine and then subjecting it to chemical acetylation; polyacetylation precursors obtained using diamines with side chains and then subjecting them to acetylation; and polyacetylation precursors obtained using diamines with tert-butoxycarbonyl groups and then subjecting them to acetylation. Through such side chain or chemical acetylation, the surface energy can be made close to that of the acrylic polymer in component (A). Therefore, when a liquid crystal alignment agent is coated and fired to form a hardened film, aggregation or other issues can be avoided, resulting in a flat hardened film. Diamines having side chains include those represented by formulas (2), (3), (4), and (5) as described in paragraphs

[0023] to

[0039] of International Patent Application Publication No. WO2016 / 125870, and those represented by formulas [A-1] to [A-32] as specific examples. Diamines having a tert-butoxycarbonyl group include those represented by the structures of formulas [A-1], [A-2], and [A-3] as described in paragraphs

[0011] to

[0034] of International Patent Application Publication No. WO2017 / 119461, and those exemplified as specific examples.

[0074] When the liquid crystal alignment agent of the present invention contains polymer of component (B), the content ratio of polymer of component (A) to polymer of component (B) is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 60:40.

[0075] <(C) Ingredients> The liquid crystal alignment agent used in this invention may also contain a crosslinking agent as component (C).

[0076] (C) Crosslinking agents may include epoxy compounds, compounds having two or more amine groups, hydroxymethyl compounds, isocyanate compounds, phenolic plastic compounds, low molecular weight compounds such as block isocyanate compounds, polymers of N-alkoxymethylacrylamide, polymers of compounds having epoxy groups, polymers of compounds having isocyanate groups, etc.

[0077] Specific examples of the aforementioned 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, glycerol diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N',-tetraglycidyl-m-phenylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, etc.

[0078] Examples of compounds having two or more amine groups include alicyclic diamines, aromatic diamines, aromatic-aliphatic diamines, and aliphatic diamines.

[0079] Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, and isophorone diamine.

[0080] 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.

[0081] Examples of aromatic-aliphatic diamines include 3-aminophenylmethylamine, 4-aminophenylmethylamine, 3-amino-N-methylphenylmethylamine, 4-amino-N-methylphenylmethylamine, 3-aminophenylethylamine, 4-aminophenylethylamine, 3-amino-N-methylphenylethylamine, 4-amino-N-methylphenylethylamine, 3-(3-aminopropyl)aniline, 4-(3-aminopropyl)aniline, 3-(3-methylaminopropyl)aniline, 4-(3-methylaminopropyl)aniline, 3-(4-aminophenylmethylphenylethyl)aniline, and so on. (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, (6-amino-2-naphthyl)methylamine, (6-amino-3-naphthyl)methylamine, 2-(6-amino-2-naphthyl)ethylamine, 2-(6-amino-3-naphthyl)ethylamine, etc.

[0082] 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-methylnonane.

[0083] Specific examples of hydroxymethyl compounds include compounds such as alkoxymethylated urea, alkoxymethylated benzoguanamine, and alkoxymethylated melamine.

[0084] Specific examples of alkoxymethylated ureas include 1,3,4,6-tetra(methoxymethyl)ethynurea, 1,3,4,6-tetra(butoxymethyl)ethynurea, 1,3,4,6-tetra(hydroxymethyl)ethynurea, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-tetra(butoxymethyl)urea, 1,1,3,3-tetra(methoxymethyl)urea, 1,3-bis(hydroxymethyl)-4,5-dihydroxy-2-imidazolinone, and 1,3-bis(methoxymethyl)-4,5-dimethoxy-2-imidazolinone, etc. Commercially available products include compounds such as acetylenoid compounds manufactured by Daicel-Allnex (trade names: Cymel 1170, Powderlink 1174), methylated urea resin (trade name: UFR 65), butylated urea resin (trade names: UFR 300, U-VAN10S60, U-VAN10R, U-VAN11HV), and urea / formaldehyde resins manufactured by DIC (high condensation type, trade names: Amidir J-300S, same as P-955, same as N), etc.

[0085] Specific examples of alkoxymethylated benzoguanidines include tetramethoxymethylbenzoguanidine. Commercially available products include those manufactured by Daicel-Allnex (trade name: Cymel 1123) and those manufactured by Sanwa Chemical (trade names: Nikalac BX-4000, BX-37, BL-60, BX-55H).

[0086] Specific examples of alkoxymethylated melamine include hexamethoxymethyl melamine. Commercially available examples include methoxymethyl melamine compounds manufactured by Daicel-Allnex (trade names: Cymel 300, 301, 303, 350), butoxymethyl melamine compounds (trade names: Mycoat 506, 508), methoxymethyl melamine compounds manufactured by Sanwa Chemical (trade names: Nikalac MW-30, MW-22, MW-11, MS-001, MX-002, MX-730, MX-750, MX-035), and butoxymethyl melamine compounds (trade names: Nikalac MX-45, MX-410, MX-302), etc.

[0087] Alternatively, it can be a compound obtained by condensation of melamine compounds, urea compounds, acetylenide compounds, and benzoguanidine compounds in which the hydrogen atoms of such amino groups are substituted with hydroxymethyl or alkoxymethyl groups. For example, the high molecular weight compound made from melamine compounds and benzoguanidine compounds described in U.S. Patent No. 6,323,310 can be cited. Commercially available products of the aforementioned melamine compounds include, for example, Cymel (registered trademark) 303 (manufactured by Daicel-Allnex, Inc.), and commercially available products of the aforementioned benzoguanidine compounds include, for example, Cymel (registered trademark) 1123 (manufactured by Daicel-Allnex, Inc.), etc.

[0088] Specific examples of isocyanate compounds include, for example, VESTANAT B1358 / 100, VESTAGON BF 1540 (and above, isocyanate-modified polyisocyanate, manufactured by Evonik Japan), Takenate (registered trademark) B-882N, and B-7075 (and above, isocyanate-modified polyisocyanate, manufactured by Mitsui Chemicals).

[0089] Specific examples of phenolic plastic compounds can be listed below, but phenolic plastic compounds are not limited to the examples listed below.

[0090]

[0091] Specific examples of compounds having two or more hydroxyalkylamino groups at the molecule's end include, for example, the following compounds or Primid QM-1260, SF-4510 (all manufactured by EMS-GRILTECH).

[0092]

[0093] Block isocyanate compounds, such as Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate MS-50 (and above, manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (and above, manufactured by Mitsui Chemicals Corporation), etc.

[0094] Furthermore, the aforementioned N-alkoxymethylacrylamide polymers may include, for example, polymers manufactured using acrylamide compounds or methacrylamide compounds that have been substituted with hydroxymethyl or alkoxymethyl groups, such as N-hydroxymethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide.

[0095] Specific examples of such polymers include, for instance, poly(N-butoxymethacrylamide), copolymers of N-butoxymethacrylamide and styrene, copolymers of N-hydroxymethylmethacrylamide and methyl methacrylate, copolymers of N-ethoxymethylmethacrylamide and benzyl methacrylate, and copolymers of N-butoxymethacrylamide, 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.

[0096] Polymers containing epoxy groups, such as polymers made using glycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate, and other epoxy compounds.

[0097] Specific examples of such polymers include, for instance, poly(3,4-epoxycyclohexyl methacrylate), poly(glycidyl methacrylate), copolymers of glycidyl methacrylate and methyl methacrylate, copolymers of 3,4-epoxycyclohexyl methacrylate and methyl methacrylate, and copolymers of glycidyl methacrylate and styrene. 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.

[0098] The polymers containing the aforementioned isocyanate groups include, for example, compounds containing isocyanate groups such as ethyl 2-isocyanate methacrylate (Karenz MOI [registered trademark], manufactured by Showa Denko), ethyl 2-isocyanate acrylate (Karenz AOI [registered trademark], manufactured by Showa Denko), or polymers containing block isocyanate groups such as ethyl 2-(O-[1'-methylpropylamino]carboxyamino) methacrylate (Karenz MOI-BM [registered trademark], manufactured by Showa Denko), ethyl 2-[(3,5-dimethylpyrazolyl)carbonylamino] methacrylate (Karenz MOI-BP [registered trademark], manufactured by Showa Denko).

[0099] Specific examples of such polymers include, for instance, poly(ethyl 2-isocyanate acrylate), poly(ethyl 2-(O-[1'-methylpropylamino]carboxyamino) methacrylate), copolymers of ethyl 2-isocyanate methacrylate and styrene, and copolymers of ethyl 2-[(3,5-dimethylpyrazolyl)carbonylamino] 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.

[0100] These crosslinking agents can be used alone or in combination of two or more.

[0101] When the liquid crystal alignment agent used in this invention contains crosslinking agent of component (C), the content of crosslinking agent is preferably 1 to 100 parts by mass, and more preferably 1 to 80 parts by mass, relative to 100 parts by mass of resin of component (A).

[0102] Modulation of liquid crystal alignment agents The liquid crystal alignment agent used in this invention is preferably formulated as a coating solution, making it suitable for the formation of a liquid crystal alignment film. That is, the liquid crystal alignment agent of this invention is preferably formulated as a solution obtained by dissolving the resin component used to form the resin film in an organic solvent. Here, the resin component refers to the specific polymer of component (A) as described and the polymer of component (B) as needed. In this case, the total content of the specific polymer of component (A) and the polymer of component (B), relative to the total liquid crystal alignment agent, is preferably 0.5-20% by mass, more preferably 1-20% by mass, even more preferably 1-15% by mass, and particularly preferably 1-10% by mass.

[0103] Solvent The solvent contained in the liquid crystal alignment agent used in this invention is not particularly limited, as long as it can dissolve component (A), and, depending on the requirements, components (B) and (C). The liquid crystal alignment agent may contain one solvent or a mixture of two or more. Furthermore, even if the solvent is not one that dissolves component (A) or component (B), it can be used in combination with a solvent that dissolves component (A) or component (B). In this case, if the surface energy of the solvent that does not dissolve component (A) or component (B) is lower than that of the solvent that dissolves component (A) or component (B), the liquid crystal alignment agent can have good coating properties on the substrate, which is preferable.

[0104] 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-dimethylpropionic acid, 3-ethoxy-N,N-dimethylpropionic acid, 3-butoxy-N,N-dimethylpropionic acid, dialkylimidazolinones such as 1,3-dimethyl-2-imidazolinone; lactones such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; and carbonates such as ethyl carbonate and propylene carbonate. Ketones such as methanol, ethanol, propanol, isopropanol, 3-methyl-3-methoxybutanol, ethylpentyl ketone, methyl nonyl ketone, methyl ethyl ketone, isopentylmethyl ketone, methyl isopropyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, 4-hydroxy-4-methyl-2-pentanone, compounds represented by the following formula (Sv-1) and 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, isopentyl butyrate, diisobutylmethanol, diisopentyl ether, etc.

[0105]

[0106] In formulas (Sv-1) to (Sv-2), Y1 and Y2 are independently hydrogen atoms or monovalent hydrocarbon groups with 1 to 6 carbon atoms, X1 is an oxygen atom or -COO-, X2 is a single bond or carbonyl group, and R1 is an alkyldiyl group with 2 to 4 carbon atoms. n1 is an integer from 1 to 3. When n1 is 2 or 3, the multiple R1s can be the same or different. Z1 is a divalent hydrocarbon group with 1 to 6 carbon atoms, and Y3 and Y4 are independently hydrogen atoms or monovalent hydrocarbon groups with 1 to 6 carbon atoms.

[0107] In formula (Sv-1), the hydrocarbon groups of Y1 and Y2 with 1 to 6 carbon atoms and a monovalent valence can be, for example, chain hydrocarbon groups with 1 to 6 carbon atoms and a monovalent alicyclic hydrocarbon group with 1 to 6 carbon atoms and a monovalent aromatic hydrocarbon group with 1 to 6 carbon atoms. Chain hydrocarbon groups with 1 to 6 carbon atoms and a monovalent valence can be, for example, alkyl groups with 1 to 6 carbon atoms. The alkidine group of R1 can be straight-chain or branched.

[0108] In formula (Sv-2), Z1 is a divalent hydrocarbon group with 1 to 6 carbon atoms, such as alkyl diols with 1 to 6 carbon atoms. The hydrocarbon groups with 1 to 6 carbon atoms in Y3 and Y4, exhibiting a monovalent valence, can be categorized as chain hydrocarbon groups with 1 to 6 carbon atoms, alicyclic hydrocarbon groups with 1 to 6 carbon atoms, and aromatic hydrocarbon groups with 1 to 6 carbon atoms. Chain hydrocarbon groups with 1 to 6 carbon atoms, exhibiting a monovalent valence, can be categorized as alkyl groups with 1 to 6 carbon atoms.

[0109] Specific examples of solvents 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 ceroxox), 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, 3-ethoxybutyl acetate, etc. Specific examples of solvents represented by (Sv-2) include methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate, butyl lactate, isoamyl lactate, ethyl-3-ethoxy propionate, methyl-3-methoxy propionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, etc.

[0110] The aforementioned solvents preferably have a boiling point of 80-200°C. More preferably, they have a boiling point of 80-180°C. Examples of preferred solvents include N,N-dimethylformamide, tetramethylurea, 3-methoxy-N,N-dimethylpropionic acid, 1-propanol, isopropanol, 3-methyl-3-methoxybutanol, ethylpentyl ketone, methyl ethyl ketone, isopentylmethyl 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, isopentyl butyrate, diisobutylmethanol, diisopentyl ether, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. Ethers, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol monobutyl ether (butyl ceroxox), 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-ethoxy propionate, methyl-3-methoxy propionate, ethyl 3-methoxypropionate, etc. The boiling point is within this range, especially when the liquid crystal alignment agent containing the aforementioned solvent is coated on the plastic substrate described later.

[0111] <Other Ingredients> The liquid crystal alignment agent used in this invention may also contain other components besides the above-mentioned component (A), component (B), and component (C) as needed. Such other components may include crosslinking catalysts, compounds that improve the uniformity of film thickness or surface smoothness when coating the liquid crystal alignment agent, compounds that improve the adhesion between the liquid crystal alignment film and the substrate, etc., but are not limited to these.

[0112] Crosslinking Catalyst To promote the reaction between the oxazoline skeleton and the carboxyl group, a crosslinking catalyst may also be added to the liquid crystal alignment agent used in this invention. Examples of such crosslinking catalysts include 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-perfluorooctanesulfonic acid, perfluoro(2-ethoxyethane)sulfonic acid, pentafluoroethanesulfonic acid, nonafluorobutane-1-sulfonic acid, dodecylbenzenesulfonic acid, and other sulfonic acids or their hydrates or salts. Compounds that produce acids upon heating include, for example, 1,2-bis(toluenesulfonoxy)ethane, 1,3-bis(toluenesulfonoxy)propane, 1,4-bis(toluenesulfonoxy)butane, p-nitrobenzene toluenesulfonate, o-nitrobenzene toluenesulfonate, pyridinium salt of p-toluenesulfonate, morpholinium salt of p-toluenesulfonate, ethyl p-toluenesulfonate, propyl p-toluenesulfonate, butyl p-toluenesulfonate, isobutyl p-toluenesulfonate, methyl p-toluenesulfonate, phenethyl p-toluenesulfonate, cyanomethyl p-toluenesulfonate, 2,2,2-trifluoroethyl p-toluenesulfonate, 2-hydroxybutyl p-toluenesulfonate, and N-ethyl-p-toluenesulfonamide.

[0113] [Compounds that improve film thickness uniformity or surface smoothness] Compounds that can improve the uniformity of film thickness or surface smoothness include fluorinated surfactants, polysiloxane surfactants, and nonionic surfactants. Specifically, examples include Eftop (registered trademark) 301, EF303, EF352 (manufactured by Mitsubishi Materials Electronics & Chemicals Co., Ltd.), Megaface (registered trademark) F171, F173, R-30 (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by 3M Corporation), Asahiguard (registered trademark) AG710 (manufactured by AGC Corporation), and Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC SEIMI CHEMICAL Corporation). The proportion of these surfactants used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the resin component contained in the polymer composition.

[0114] [Compounds that improve the 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 compounds containing functional silanes, as shown below. Examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureopropyltrimethoxysilane, 3-ureopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-3-triethoxysilylpropyltriethylenetetramine, N... Compounds containing amino groups, such as 3-trimethoxysilylpropyltriethylenetetramine, 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, and N-phenyl-3-aminopropyltriethoxysilane. When using a compound that improves adhesion to the substrate, the amount of the compound used is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, relative to 100 parts by mass of the resin component contained in the polymer composition.

[0115] In one embodiment, photosensitizers may be used as additives to enhance the photoreactivity of the photoalignment group. Specific examples include aromatic 2-hydroxy ketones (benzophenone), coumarins, ketocoumarins, carbonyl dicoumarins, acetophenone, anthraquinones, xanthine ketones, thioxanthones, and acetophenone ketals.

[0116] <Liquid crystal alignment film and liquid crystal display element> The liquid crystal alignment agent of this invention, after being coated and fired on a substrate, can be aligned by means of rubbing or light irradiation, or in some applications such as vertical alignment, it can be used without alignment treatment to become a liquid crystal alignment film. As a substrate, for example, transparent substrates made of glass such as float glass and soda glass; plastics such as polyethylene terephthalate, polybutylene terephthalate, polypropylene, polystyrene, polyether ether, polycarbonate, poly(alicyclic olefins), polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF), polyether ether (PES), polyamide, polyimide, acrylic, and triacetyl cellulose can be used. As a transparent conductive film disposed on one side of a substrate, NESA film (a registered trademark of PPG Industries, Inc.) made of tin oxide (SnO 2) or ITO film made of indium oxide-tin oxide (In 2O 3-SnO 2) can be used.

[0117] <Coating Formation Steps> The coating method for the liquid crystal alignment agent of the present invention is not particularly limited, and may include screen printing, flexographic printing, offset printing, inkjet printing, dip coating, roll coating, slot coating, spin coating, etc., which may be used depending on the purpose. After being coated onto a substrate by such methods, the solvent is evaporated by heating means such as a heating plate to form a coating film.

[0118] The firing process after coating the liquid crystal alignment agent can be carried out at any temperature from 40 to 300°C, preferably from 40 to 250°C, and more preferably from 40 to 230°C. The thickness of the coating film formed on the substrate is preferably 5~1,000 nm, more preferably 10~500 nm or 10~300 nm. The firing can be carried out by a heating plate, a hot air circulating furnace, an infrared furnace, etc. Friction treatment can be performed using materials such as nylon cloth, cotton cloth, etc.

[0119] <Light Irradiation Steps> In one embodiment, an alignment process caused by light irradiation can be performed. For example, it may include the step of coating the liquid crystal alignment agent onto a substrate to form a coating film, and the step of irradiating the coating film with light in a state where the coating film is not in contact with the liquid crystal layer or in a state where it is in contact with the liquid crystal layer.

[0120] The light irradiated during the alignment treatment caused by light irradiation can be, for example, ultraviolet light or visible light with wavelengths of 150-800 nm. Among these, ultraviolet light with wavelengths of 300-400 nm is preferred. The irradiating light can be polarized or unpolarized. As polarized light, linearly polarized light is preferred.

[0121] When irradiating with polarized light, the substrate surface can be irradiated vertically, obliquely, or in combination. When irradiating with non-polarized light, it is preferable to irradiate the substrate surface obliquely. The light irradiation is preferably 0.1 mJ / cm² or higher but not more than 1,000 mJ / cm², more preferably 1 to 500 mJ / cm², and even more preferably 2 to 200 mJ / cm².

[0122] The liquid crystal display element of the present invention can be manufactured by conventional methods, and the manufacturing method is not particularly limited. Preferably, a spacer is disposed between the substrates to make the thickness of the liquid crystal sandwiched between the substrates uniform, with the aforementioned pair of substrates facing each other with an appropriate gap. The spacer can be a conventionally known spacer material, such as a distributed spacer or a spacer formed from a photosensitive spacer forming component. Alternatively, an unevenness formed on a layer composed of a liquid crystal curing agent can be used as a spacer.

[0123] <LCD clamping steps> To sandwich liquid crystals between substrates to form a liquid crystal cell, the following two methods can be listed as examples. The first method can be to arrange a pair of substrates facing each other with a gap (cell gap) between them, with each liquid crystal alignment film facing each other, and to bond the periphery of the pair of substrates together with a sealant. After injecting liquid crystal into the cell gap separated by the substrate surface and a suitable sealant, the injection hole is sealed to manufacture a liquid crystal cell.

[0124] The second method can be exemplified by applying a UV-curable sealant to a specific location on one of the two substrates on which the liquid crystal alignment film is formed, and then dropping liquid crystal onto several specific locations on the surface of the liquid crystal alignment film. The other substrate is then bonded together with the liquid crystal alignment film facing each other, and the liquid crystal is uniformly spread across the entire surface of the substrate. Finally, the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby manufacturing a liquid crystal cell (ODF (One Drop Fill) method).

[0125] As a liquid crystal, depending on the application, fluorine-based liquid crystals or cyano-based liquid crystals with positive or negative dielectric anisotropy, or liquid crystal compounds or liquid crystal compositions polymerized by at least one of heating and light irradiation (hereinafter also referred to as polymerizable liquid crystals or curable liquid crystal compositions) may be used. 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 the roll-to-roll method is used, the manufacturing steps of the liquid crystal display element can be simplified, and manufacturing costs can be reduced. Then, by attaching polarizing plates to the two outer sides of the aforementioned liquid crystal cell, a liquid crystal display element can be obtained.

[0126] Polarizing plates used on the outside of liquid crystal cells can include polarizing plates that sandwich a polarizing film called an "H film" that extends and aligns polyvinyl alcohol on one side and absorbs iodine on the other, with a cellulose acetate protective film, or polarizing plates composed of the H film itself. As described above, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention exhibits good liquid crystal alignment properties, excellent pretilt angle display capability, and high reliability. Furthermore, the liquid crystal display element manufactured by the method of the present invention possesses excellent display characteristics. [Example]

[0127] The present invention is illustrated by the following examples, but the invention is not limited to these examples. The abbreviations of the compounds and the methods for determining their properties are as described below. Boc represents tert-butoxycarbonyl.

[0128] <Methacrylic acid monomer> (Photoalignment monomer) MA-1 was synthesized using the method described in patent document (WO2017 / 115790).

[0129]

[0130] (Monomers containing carboxyl groups) MAA: Methacrylic acid

[0131]

[0132] (Monomers containing the oxazoline skeleton)

[0133]

[0134] <Tetracarboxylic dianhydride monomer> A1~A8: Compounds represented by the following formulas [A1]~[A8] respectively.

[0135]

[0136] <Side-chain diamine monomer> B1~B14: Compounds represented by the following formulas [B1]~[B14] respectively.

[0137]

[0138] <Other diamine monomers> C1~C20: Compounds represented by the following formulas [C1]~[C20] respectively.

[0139]

[0140] (Cross-linking agent component) D1~D3: Compounds represented by the following formulas [D1]~[D3] respectively.

[0141]

[0142] (Polymerization initiator) AIBN: Azobisisobutyronitrile (solvent) NMP: N-methyl-2-pyrrolidone BCS: Dingji Sailuosu THF: Tetrahydrofuran

[0143] <Molecular weight determination> The molecular weight of the polymers in the synthesis examples was determined using a Senshu Scientific gel permeation chromatography (GPC) apparatus (SSC-7200) and Shodex columns (KD-803, KD-805), as follows. Column temperature: 50℃; precipitate: DMF (as an additive, lithium bromide hydrate (LiBr·H₂O) 30 mmol / L, anhydrous phosphoric acid (o-phosphoric acid) 30 mmol / L, THF 10 mL / L); flow rate: 1.0 mL / min The standard samples used to prepare the calibration curve were: TSK standard polyethylene oxide (molecular weight approximately 900,000, 150,000, 100,000, and 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weight approximately 12,000, 4,000, and 1,000) manufactured by Polymer Laboratories.

[0144] <Determination of aceiminization rate> The nitrile imidization rate in the synthesis example was determined as follows. 20 mg of polynitrile powder was placed in an NMR sample tube (a φ5 standard NMR sampling tube manufactured by Kusano Scientific Co., Ltd.), and 1.0 mL of dimethyl sulfoxide (DMSO-d6, 0.05% TMS mixture) was added. The solution was dissolved completely by ultrasound. The solution was then measured at 500 MHz using a NMR spectrometer (JNW-ECA500) manufactured by NEC Datum Co., Ltd. The nitrile imidization rate was determined using the protons from the unchanged structure before and after nitrile imidization as reference protons. The peak integral value of this proton was compared with the peak integral value of the protons from the NH group of acetic acid appearing around 9.5–10.0 ppm, and the result was obtained by the following formula. Furthermore, in the following formula, x is the proton peak integral value derived from the NH group of acetic acid, y is the peak integral value of the reference proton, and α is the ratio of the number of reference protons to one proton of the NH group of acetic acid in the case of polyacetic acid (aceimide content 0%).

[0145] <Synthesis of Monomers> MB-1 is a novel compound not disclosed in the literature, and its synthesis method is described in detail in the following monomer synthesis example 1.

[0146] <Determination by 1H-NMR> Apparatus: Fourier transform superconducting nuclear magnetic resonance (FT-NMR) device "AVANCE III" (manufactured by BRUKER) 500MHz. Solvent: Dimethyl sulfoxide (DMSO-d6). Standard substance: Tetramethylsilane (TMS).

[0147] (Single Synthesis Example 1: Synthesis of [MB-1])

[0148]

[0149] (Synthesis of [MB-1-1]) [MB-1-1] was obtained from 4-hydroxybenzonitrile using the same method as described in the literature (Organic Letters, 14(23), 5900-5903; 2012).

[0150] (The synthesis of [MB-1-2]) In a 2000 mL four-necked flask, 428 g of 1,2-dichlorobenzene, 42.8 g of MB-1-1 (262 mmol), 70.1 g of 2-amino-2-methyl-1-propanol, and 17.9 g of zinc chloride were added. The mixture was heated at 150 °C under nitrogen for 24 hours until the reactants disappeared. After the reaction was complete, the reaction solution was returned to room temperature, and 428 g of chloroform, 642 g of pure water, and 31.5 g of ethylenediamine were added. The mixture was then separated. The organic phase was washed twice with 500 g of pure water and recovered. The recovered organic phase was concentrated under reduced pressure to a final weight of 532 g. Hexane (1470 g) was added to induce crystallization. The crystals were filtered, separated, and dried to obtain white crystals of [MB-1-2] (yield: 50.6 g, 82%).

[0151] (Synthesis of [MB-1]) In a 1000 mL four-necked flask, tetrahydrofuran (300 g), MB-1-2 (30.0 g, 128 mmol), triethylamine (25.9 g), and 2,6-di-tert-butyl-p-cresol (84.6 mg) were added. Chloride methacrylate (14.7 g) was then added dropwise under nitrogen and ice-cold conditions. After addition, the reaction was allowed to proceed overnight at room temperature until the reactants disappeared. After the reaction was complete, the reaction solution was added to pure water (1800 g) to induce crystallization. The crude crystals were recovered by filtration. The crude crystals were dissolved in ethyl acetate and dehydrated using magnesium sulfate. The ethyl acetate solution was then concentrated under reduced pressure to an internal weight of 86.7 g. Hexane (270 g) was added to induce crystallization, which was then separated by filtration and dried to obtain white crystals of [MB-1] (yield: 22.9 g, 59%). 1H-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)

[0152] Synthesis of Polymethyl methacrylate (Synthesis example 1) MA-1 (3.04 g, 6.00 mmol), MB-1 (1.52 g, 5.00 mmol), and MAA (0.77 g, 9.00 mmol) were dissolved in NMP (31.1 g), degassed using a diaphragm pump, and then AIBN (0.16 g, 0.97 mmol) as a polymerization initiator was added, followed by further degassed. The mixture was then reacted at 60 °C for 13 hours under nitrogen to obtain a polymer solution. Next, NMP (5.0g) and BCS (6.0g) were added to the polymer solution (4.0g), and a polymethacrylate solution (MP1) was obtained by stirring at room temperature. The polymer has a number average molecular weight of 32,000 and a weight average molecular weight of 121,000.

[0153] (Synthesis example 2) According to the composition shown in Table 1, a polymethacrylate solution (MP2) was synthesized using the same method as in Polymer Synthesis Example 1.

[0154]

[0155] Synthesis of Polyamides (Synthesis example 3) B1 (2.28 g, 6.00 mmol), C2 (1.22 g, 8.00 mmol), C7 (1.45 g, 6.00 mmol), and A1 (2.23 g, 11.4 mmol) were dissolved in NMP (27.2 g) and reacted at 60 °C for 5 hours. Then, A2 (1.00 g, 4.00 mmol), A4 (0.87 g, 4.00 mmol), and NMP (9.1 g) were added, and the mixture was reacted at 40 °C for 10 hours to obtain a polyacrylic acid solution (PAA-1A) with a solid content of 20% by mass. NMP (20.0g) and BCS (20.0g) were added to the obtained polyacrylic acid solution (10.0g), and the mixture was stirred at room temperature for 2 hours to obtain a polyacrylic acid solution (PAA-1) with a solid content concentration of 4.0% by mass.

[0156] (Synthesis Examples 4~21) Using the same method as in Synthesis Example 3, polyamide solutions (PAA-2A) to (PAA-19A) with a solid component concentration of 20% by mass and polyamide solutions (PAA-2) to (PAA-19) with a solid component concentration of 4.0% by mass were synthesized with the composition shown in Table 2.

[0157]

[0158] Synthesis of Polyimide (Synthesis Example 22) NMP was added to 15 g of polyamide solution (PAA-1A) and diluted to a solid content concentration of 6.5% by mass. Acetic anhydride (2.6 g) and pyridine (0.81 g) were then added as amide catalysts, and the reaction was carried out at 75 °C for 2.5 hours. The reaction solution was then added to 210 mL of methanol, and the precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at 100 °C to obtain polyamide powder (E). The amide content of this polyamide was 75%, with a number average molecular weight of 12,400 and a weight average molecular weight of 42,500. NMP (14.7 g) was added to the obtained polyimide powder (E) (2.0 g), and the mixture was stirred at 70 °C for 20 hours to dissolve it. NMP (13.3 g) and BCS (20.0 g) were then added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a polyimide solution (SPI-1).

[0159] (Synthesis Examples 23~40) The polyamide solutions (PAA-2A) to (PAA-19A) obtained in Synthesis Examples 4 to 21 were used to replace the polyamide solution (PAA-1A), and the polyimide solutions (SPI-2) to (SPI-19) were otherwise synthesized in the same manner as in Synthesis Example 22.

[0160] <Modulation of Liquid Crystal Alignment Agents> (Example 1) D3 (0.04 g) was added to the polymethacrylate solution (MP1) (10.0 g) obtained in Synthesis Example 1, and liquid crystal alignment agent (PM1) was obtained by stirring at room temperature.

[0161] (Example 2) The polymethyl methacrylate solution (MP1) (3.0 g) obtained in Synthesis Example 1 was added to the polyamide solution (PAA-1) (7.0 g) obtained in Synthesis Example 3, and D3 (0.04 g) was further added to obtain the liquid crystal alignment agent (PM2) by stirring at room temperature.

[0162] (Examples 3-20) As shown in Table 3, (PAA-2) to (PAA-19) were used to replace the polyacrylic acid solution (PAA-1), and otherwise the same procedure as in Example 2 was followed to obtain liquid crystal alignment agents (PM3) to (PM20).

[0163] (Example 21) The polyimide solution (SPI-1) (7.0 g) obtained in Synthesis Example 22 was added to the polymethacrylate solution (MP1) (3.0 g) obtained in Synthesis Example 1, and D3 (0.04 g) was further added to obtain the liquid crystal alignment agent (PM21) by stirring at room temperature.

[0164] (Examples 22-39) As shown in Table 3, (SPI-2) to (SPI-19) were used to replace the polyimide solution (SPI-1), and otherwise the same procedure as in Example 21 was followed to obtain liquid crystal alignment agents (PM22) to (PM39).

[0165] (Examples 40-41) As shown in Table 3, (D1) to (D2) were used to replace the crosslinking agent component (D3), and otherwise the same procedure as in Example 2 was followed to obtain liquid crystal alignment agents (PM40) to (PM41).

[0166] (Comparative Example 1) D3 (0.04 g) was added to the polymethacrylate solution (MP2) (10.0 g) obtained in Synthesis Example 2, and liquid crystal alignment agent (RPM1) was obtained by stirring at room temperature.

[0167] (Comparative Example 2) The polymethyl methacrylate solution (MP2) (3.0 g) obtained in Synthesis Example 2 was added to the polyamide solution (PAA-1) (7.0 g) obtained in Synthesis Example 3, and D3 (0.04 g) was further added to obtain the liquid crystal alignment agent (RPM2) by stirring at room temperature.

[0168] (Comparative Example 3) The polyimide solution (SPI-1) (7.0 g) obtained in Synthesis Example 22 was added to the polymethacrylate solution (MP2) (3.0 g) obtained in Synthesis Example 2, and D3 (0.04 g) was further added to obtain the liquid crystal alignment agent (RPM3) by stirring at room temperature.

[0169]

[0170] <Fabrication of Liquid Crystal Display Components> The liquid crystal alignment agents (PM1) to (PM41) obtained in the examples and the liquid crystal alignment agents (RPM1) to (RPM3) obtained in the comparative examples were filtered under pressure using membrane filters with a pore size of 1 μm. The obtained solution was spin-coated onto the ITO surface of a glass substrate with a transparent electrode made of ITO film. After drying on a heating plate at 70°C for 90 seconds, it was fired on a heating plate at 200°C for 30 minutes to form a liquid crystal alignment film with a thickness of 100 nm. Next, the coated surface is irradiated with linearly polarized ultraviolet light of 313 nm wavelength at an intensity of 4.3 mW / cm², at an angle of 40° from the substrate normal, at a concentration of 50 mJ / cm², to obtain a substrate with a liquid crystal alignment film. The linearly polarized ultraviolet light is generated by passing ultraviolet light from a high-pressure mercury lamp through a bandpass filter with a wavelength of 313 nm, and then modulated by passing it through a polarizing plate with a wavelength of 313 nm. Two substrates were prepared. 4μm bead spacers were dispersed on the liquid crystal alignment film of one substrate, and then a sealant (Mitsui Chemicals, XN-1500T) was applied. Next, the other substrate was bonded together with the liquid crystal alignment films facing each other at 180°. The sealant was then heat-cured at 120°C for 90 minutes to create a void cell. Liquid crystal (Merck, MLC-3022) was implanted into the void cell using a reduced-pressure implantation method to obtain a liquid crystal display element.

[0171] <Evaluation> (liquid crystal alignment) The liquid crystal display elements obtained above were subjected to homogenization phase treatment at 120°C for 1 hour, and then the cell structure was observed using a polarizing microscope. A good result was characterized by the absence of misalignment such as light leakage or abnormal regions, or by uniform liquid crystal driving when a voltage was applied to the liquid crystal cell. The evaluation results are shown in Table 4.

[0172] (Pre-tilt angle) The pretilt angle of the liquid crystal cell in the fabricated liquid crystal display element was measured using the AxoScan from Axo Metrix, employing the Mueller matrix method. A larger value subtracted from 90° indicates a higher tilt display capability. The evaluation results are shown in Table 4.

[0173]

[0174] As shown in Table 4, the liquid crystal alignment film obtained by copolymerizing a polymethacrylate solution containing photoreactive monomers, carboxyl-containing monomers, and monomers containing an oxazoline backbone, or a liquid crystal alignment agent containing a polymethacrylate solution and a polyamide or polyimide solution, exhibits higher tilt display capability compared to the liquid crystal alignment film of the comparative example. Specifically, this 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]

[0175] The liquid crystal alignment agent of the present invention and the liquid crystal display element using the liquid crystal alignment film obtained therefrom are suitable for use in durable liquid crystal display elements such as those for automotive applications.< / x> < / x>

Claims

1. A liquid crystal alignment agent comprising a pyrimidin-2,5-diyl, pyridin-2,5-diyl, thiophene-2,5-diyl, furan-2,5-diyl, 1,4- or 2,6-naphthyl or phenyl group having the following formula (pa-1) (where A represents a group selected from fluorine, chlorine, or cyano, or substituted by an alkoxy group having 1 to 5 carbon atoms, a straight-chain or branched alkyl residue (which may be substituted by one or more halogen atoms, depending on the case), R1 being a single bond, an oxygen atom, -COO- or -OCO-, and R2 being a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent aromatic group. The condensed cyclic group has R3 as a single bond, oxygen atom, -COO- or -OCO-, R4 as a straight-chain or branched alkyl group with 1 to 40 carbon atoms, or a monovalent organogroup with 3 to 40 carbon atoms including an alicyclic group, D represents an oxygen atom, sulfur atom, or -NRd- (here, Rd represents a hydrogen atom or an alkyl group with 1 to 3 carbon atoms), a is an integer from 0 to 3, when a is 2 or more, the plurality of R1 and R2 systems independently have the above definitions; X and Y systems are independently hydrogen atoms, fluorine atoms, chlorine atoms, cyano groups, or alkyl groups with 1 to 3 carbon atoms; * indicates the bond position) represents the photoalignment group, the following formula (1-ma) (In the formula, Ma represents a free radical polymerizable group selected from (meth)acrylate, fumarate, maleate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, norcamphene, (meth)acrylamide and its derivatives, and a polymerizable group of siloxane; Mb is a group selected from single bond, heterocyclic group with (r+1) valence, linear or branched hydrocarbon group with (r+1) valence of 1 to 10 carbon atoms, aromatic group with (r+1) valence, and alicyclic group with (r+1) valence, each group being unsubstituted or having one or more hydrogen atoms that can be substituted by fluorine, chlorine, cyano, methyl or methoxy; Sa is an alkyl group with 1 to 8 carbon atoms; r is an integer satisfying 1 ≦ r ≦ 3; Iox represents a monovalent group with an oxazoline skeleton) and a copolymer of monomers with an oxazoline skeleton and a carboxyl group, as component (A); 1.。 2. The liquid crystal alignment agent of claim 1 further comprises a polymer selected from polyimide and its precursors as component (B).

3. The liquid crystal alignment agent as claimed in claim 1, wherein component (B) is a polymer having a tert-butoxycarbonyl group.

4. The liquid crystal alignment agent as claimed in claim 1, wherein component (B) is a polymer that has been chemically imidized.

5. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 4.

6. A method for manufacturing a liquid crystal alignment film, comprising the steps of coating a liquid crystal alignment agent as described in any one of claims 1 to 4 onto a substrate to form a coating film, and the steps of irradiating the coating film with light in a state where the coating film is not in contact with the liquid crystal layer or in a state where it is in contact with the liquid crystal layer.

7. A liquid crystal display element comprising a liquid crystal alignment film as claimed in claim 5.