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

Abstract

A purpose of the present invention is to provide, in a liquid crystal display element obtained by photoalignment processing utilizing a photolysis reaction of a polyimide, a liquid crystal alignment film capable of suppressing generation of a decomposition product of the polyimide by photolysis even if the temperature of a baking process during manufacture of the liquid crystal alignment film is low. Specifically, a purpose of the present invention is to facilitate reduction of energy consumption from the viewpoint of ESG and SDGs. Furthermore, a purpose of the present invention is to provide a liquid crystal alignment agent for producing the liquid crystal alignment film, and a liquid crystal display element including the liquid crystal alignment film.　Provided is a liquid crystal alignment agent containing at least one type of polymer selected from polyimides and polyimide precursors having the structure represented by formula (1). (In the formula, the meaning of each symbol is as defined in the description.)

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device using the same

[0001] The present invention relates to a liquid crystal alignment agent used in the manufacture of a liquid crystal display device, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display device using the liquid crystal alignment film.

[0002] Currently, many polyimide-based organic films with excellent durability are used in industrially utilized resin coatings. In particular, this polyimide-based organic film is also used as a liquid crystal alignment film for liquid crystal display devices. The polyimide-based organic film is formed from a resin composition containing a polyamic acid or polyimide as a polyimide precursor. That is, a resin composition containing a polyamic acid or polyimide is applied to a substrate and formed through a firing process. In horizontally electric field-driven liquid crystal display devices such as the IPS (In Plane Switching) driving method and the FFS (Fringe Field Switching) driving method, in order to horizontally align the liquid crystal, an alignment process such as a rubbing process in which the fired liquid crystal alignment film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or an optical alignment process is performed.

[0003] In recent years, with the increase in size and high definition of liquid crystal display devices, problems such as scratches and dust generation on the liquid crystal alignment film generated by the rubbing process, and further low in-plane uniformity of the liquid crystal alignment have become issues. In contrast, an optical alignment process that regulates the liquid crystal alignment by irradiating polarized radiation (light) has begun to be adopted. For this optical alignment process, those utilizing a photo-isomerization reaction, a photocrosslinking reaction, and a photodecomposition reaction have been proposed (for example, see Patent Documents 1 to Patent Documents 3).

[0004] Japanese Patent Application Laid-Open No. 9-297313, Japanese Patent Application Laid-Open No. 2004-206091, International Publication WO2017 / 047596

[0005] When producing a liquid crystal alignment film using a liquid crystal aligning agent containing polyamic acid or polyimide, the baking process requires particularly high temperatures during the process of manufacturing a liquid crystal display device. However, in recent years, from the perspectives of ESG and SDGs, reduction of energy consumption, that is, lowering the temperature of the baking process, has been demanded. Regarding the photo-alignment treatment using a photodecomposition reaction, a treatment using the photodecomposition of polyimide is known. However, in this treatment, there is a problem that decomposition products of polyimide generated by photodecomposition mix into the liquid crystal, and display defects (hereinafter, also referred to as "bright dots") of the liquid crystal display device are likely to occur. Therefore, an object of the present invention is to provide a liquid crystal alignment film capable of suppressing the occurrence of bright dots caused by decomposition products of polyimide generated by photodecomposition in a liquid crystal display device obtained by a photo-alignment treatment using a photodecomposition reaction of polyimide, even when the baking during the production of the liquid crystal alignment film is at a low temperature. In particular, it is an object to be able to reduce energy consumption from the perspectives of ESG and SDGs. Furthermore, an object is to provide a liquid crystal aligning agent for producing the liquid crystal alignment film, and a liquid crystal display device having the liquid crystal alignment film.

[0006] As a result of intensive studies to achieve the above object, the present inventor has completed the present invention having the following gist. That is, it is a liquid crystal aligning agent containing at least one polymer (hereinafter, also referred to as "specific polymer") selected from a polyimide precursor and polyimide having a structure of the following formula [1] (hereinafter, also referred to as "specific structure").

[0007]

[0008] (X １ and X ３ are each independently a single bond, -O-, -COO-, -OCO-, -NR ａ -, -NR ａ CO- or -CONR ａ -, R ａ represents a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, or a protecting group that is eliminated by heating and replaced with a hydrogen atom. X ２ represents an alkylene group having 1 to 6 carbon atoms. X ａ are each independently -COOR ｂ represents, Rｂ represents a linear or branched alkyl group having 1 to 4 carbon atoms. m1 and m2 independently represent 0 or 1, and either m1 or m2 represents 1. n1 and n2 independently represent 0 or 1. * represents a bond.

[0009] According to the present invention, even when the firing process for fabricating the liquid crystal alignment film is performed at a low temperature, it is possible to provide a liquid crystal alignment film that can suppress bright spots caused by polyimide decomposition products generated by photodecomposition in a liquid crystal display element obtained by photoalignment treatment utilizing the photodecomposition reaction of polyimide. As a result, the liquid crystal display element of the present invention has excellent display quality and can be used in smartphones, tablet devices, and other devices as a transverse electric field driven element such as an IPS drive system or an FFS drive system.

[0010] The mechanism by which the present invention yields a liquid crystal display element with the aforementioned excellent characteristics is not entirely clear, but it is presumed to be approximately as follows: The structure of the specific structure, formula [1], has X in its side chain portion. ａ This results in lower crystallinity of specific structures and lower crystallinity of specific polymers. Therefore, the crystallinity of polyimide decomposition products generated during photo-alignment treatment is reduced, making them less likely to become bright spots in liquid crystal display elements.

[0011] This is a schematic cross-sectional view showing an example of a transverse electric field type liquid crystal display element of the present invention. This is a schematic cross-sectional view showing another example of a transverse electric field type liquid crystal display element of the present invention.

[0012] <Specific Structure> The specific structure is the structure of formula [1] above. In formula [1], X １ , X ２ , X ３ , X ａ m1 and m2 are as defined above, but among them, the following are preferred: X １ and X ３ These are single bonds, -O-, -COO-, -OCO-, -NR ａ CO- or -CONR ａ - is preferred, and -O- is more preferred. In that case, -NR ａ CO- or -CONR ａ - Rａ The hydrogen atom, tert-butoxycarbonyl group, or 9-fluorenylmethyloxycarbonyl group are preferred. ２ An alkylene group having 2 to 4 carbon atoms is preferred. ａ Ha-COOR ｂ And in that case, R ｂ A methyl group or a tert-butyl group is preferred. It is preferable that both m1 and m2 are 1, or that one is 1 and the other is 0. It is preferable that both n1 and n2 are 0, or that one is 1 and the other is 0, and it is more preferable that both are 0, i.e., the following structure [1-a]. (In the above formula, X １ , X ２ , X ３ , X ａ (where m1 and m2 have the same meaning as those defined in formula [1] above, and m1 and m2 are 0.)

[0013] <Specific Polymer> The specific polymer is a polyimide precursor or polyimide containing a specific structure (hereinafter collectively referred to as "polyimide polymer"), and is preferably obtained by reacting a diamine component with a tetracarboxylic acid component. The polyimide precursor is preferably a polyamic acid or polyamic acid ester having the structure of the following formula [A].

[0014] (R ａ R indicates a tetravalent organic group. ｂ This indicates a divalent organic group. A １ and A ２ A represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and these may be the same or different. ３ and A ４ ) represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an acetyl group, and these may be the same or different. n represents a positive integer. ) Polyimide has the structure of the following formula [A-4] and can be obtained by cyclizing (hereinafter also referred to as "imidization") a polyimide precursor polyamic acid. In this case, if the cyclization rate of the amidic acid group (hereinafter also referred to as "imidization rate") is less than 100%, in addition to the structure of formula [A-4], it includes at least one of the following structures [A-1] to [A-3].

[0015]

[0016] (R ａ and R ｂ (This has the same meaning as defined in formula [A] above.) The diamine component is a diamine having two primary or secondary amino groups in its molecule, and the tetracarboxylic acid component includes tetracarboxylic acid compounds, tetracarboxylic acid dianhydrides, tetracarboxylic acid dihalide compounds, tetracarboxylic acid dialkyl ester compounds, or tetracarboxylic acid dialkyl ester dihalide compounds.

[0017] Polyimide polymers are preferred because they can be obtained relatively easily using a tetracarboxylic dianhydride of formula [B] and a diamine of formula [C] as raw materials, and are composed of a polyamic acid having a repeating structural formula of formula [D] or a polyimide obtained by imidizing the polyamic acid.

[0018] (R ａ and R ｂ This has the same meaning as defined in formula [A] above.

[0019] (R ａ and R ｂ This has the same meaning as defined in formula [A] above.

[0020] Furthermore, using conventional synthesis methods, the polymer of formula [D] contains A of formula [A]. １ and A ２ A C1-C8 alkyl group, and A of formula [A] ３ and A ４ A C1-C5 alkyl group or acetyl group can also be introduced.

[0021] To introduce a specific structure into a polyimide polymer, it is preferable to use a diamine having the specific structure as part of the raw material. In particular, it is preferable to use the diamine of the following formula [1a] (hereinafter also referred to as "specific diamine").

[0022] X １ , X ２ , X ３ , X ａDetails and preferred types of m1, m2, n1 and n2 are the same as in formula [1] above. １ Each of these independently represents a hydrogen atom or a monovalent organic group. Of these, a hydrogen atom or an alkyl group having 1 to 3 carbon atoms is preferred. A hydrogen atom is more preferred.

[0023] -NHR in equation [1a] １ X of the benzene ring １ or X ３ It is preferable that the bond is in the para position. Specific examples of diamines include those shown in formulas [1a-1] to [1a-5] below, and it is preferable to use these in the present invention.

[0024]

[0025] From the viewpoint of suitably obtaining the effects of the present invention, the proportion of the specific diamine used is preferably 10 to 100 mol% relative to the total diamine component of the raw material of the specific polymer. More preferably, it is 20 to 80 mol%. Particularly preferred is 20 to 70 mol%. In addition, one type or two or more types of specific diamines can be used in combination depending on the characteristics. Other diamines besides the specific diamines can be used as other diamines. Specific examples include the other diamine compounds described in paragraphs

[0044] to

[0051] of WO2013 / 125595, the diamines of formulas (Y-1) to (Y-167) described in paragraphs

[0062] to

[0080] of WO2018 / 117239, and the diamines of formulas [DA-1a] to [DA-42a] below.

[0026] (In formula [DA-1a], m represents an integer from 1 to 6, and n represents 1 or 2. In formula [DA-2a], m and n each independently represent an integer from 1 to 6. In formulas [DA-3a] to [DA-7a], m and l each independently represent an integer from 0 to 6, and n each represents an integer from 1 to 6. In formulas [DA-6a] and [DA-7a], R ａ Each of these independently represents a hydrogen atom, a tert-butoxycarbonyl group, or a 9-fluorenylmethyloxycarbonyl group.

[0027] (In formulas [DA-8a] to [DA-11a], m and l each independently represent an integer from 0 to 6, and n each represents an integer from 1 to 6. In formulas [DA-10a] and [DA-11a], R ａ Each of these independently represents a hydrogen atom, a tert-butoxycarbonyl group, or a 9-fluorenylmethyloxycarbonyl group. In formulas [DA-12a] and [DA-13a], m represents an integer from 1 to 6.

[0028] (In formulas [DA-14a] and [DA-15a], m and l each independently represent an integer from 0 to 6, and n each represents 1 or 2.)

[0029] (In formula [DA-18a], m represents an integer from 1 to 6. In formulas [DA-19a] and [DA-20a], m and n each independently represent an integer from 1 to 6. In formula [DA-21a], m represents an integer from 1 to 6. In formula [DA-22a], m and n each independently represent an integer from 1 to 6. In formula [DA-24a], m represents an integer from 0 to 6. In formula [DA-25a], l represents 1 or 2. In formulas [DA-25a] and [DA-26a], m and n each independently represent an integer from 1 to 6. In formulas [DA-18a] to [DA-26a], Boc represents a tert-butoxycarbonyl group.)

[0030] (In formula [DA-27a], m and n each independently represent an integer from 0 to 6. In formula [DA-28a], m represents an integer from 0 to 6. In formula [DA-31a], m represents an integer from 1 to 6. In formula [DA-32a], m and n each independently represent an integer from 1 to 6.)

[0031] (In formula [DA-39a], R ａ represents a hydrogen atom or a methyl group. In formula [DA-41a], n and l each independently represent an integer from 0 to 3, satisfying 1 ≤ m + n ≤ 4, m represents 0 or 1, and X １ ha- (CH ２ ) ａ - ( ａ represents an integer from 1 to 15. ), -CONH-, -NHCO-, -CO-N(CH ３)-, -NH-, -O-, -CH ２ O-, -CH ２ Indicates -OCO-, -COO-, or -OCO-. １ l, n, X represents a fluorine atom, a fluorine atom-containing alkyl group having 1 to 10 carbon atoms, a fluorine atom-containing alkoxy group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkoxyalkyl group having 2 to 10 carbon atoms, and l, n, X １ and R １ If there are two of them, each has the above definition independently. In formula [DA-42a], X ２ is -O-, -CH ２ O-, -CH ２ (This represents -OCO-, -COO-, or -OCO-, where n is an integer from 3 to 20.) More specifically, the diamines of the following formulas [DA-1] to [DA-103] can be used as other diamines.

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042] Other diamines can be used individually or in mixtures of two or more types, depending on their specific properties.

[0043] For producing polyimide polymers, it is preferable to use the tetracarboxylic acid component of the following formula [2], or its tetracarboxylic acid derivatives: tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide (hereinafter collectively referred to as "specific tetracarboxylic acid component").

[0044] (Z represents one of the structures selected from the group consisting of equations [2a] to [2l] below.)

[0045] (Z Ａ ~Z Ｄ Each of these independently represents a hydrogen atom, a methyl group, a chlorine atom, or a benzene ring. Ｅ and Z Ｆ Each of these independently represents either a hydrogen atom or a methyl group.

[0046] In particular, Z is preferably formula [2a], formula [2c], formula [2d], formula [2e], formula [2f], formula [2g], formula [2k], or formula [2l] from the viewpoint of ease of synthesis and ease of polymerization reaction when producing polymers. More preferably are formula [2a], formula [2e], formula [2f], formula [2g], formula [2k], or formula [2l]. Particularly preferred are formula [2a], formula [2e], formula [2f], formula [2g], or formula [2l].

[0047] The proportion of the specific tetracarboxylic acid component used is preferably 1 mol% or more relative to the total tetracarboxylic acid component. More preferably, it is 5 mol% or more. Particularly preferably, it is 10 mol% or more.

[0048] Polyimide polymers can use tetracarboxylic acid components other than the specified tetracarboxylic acid component. Examples of other tetracarboxylic acid components include the tetracarboxylic acid compounds, tetracarboxylic acid dianhydrides, dicarboxylic acid dihalide compounds, dialkyl dicarboxylic acid ester compounds, or dialkyl ester dihalide compounds listed below. Specific examples include the other tetracarboxylic acid components described in paragraph

[0057] of WO2015 / 012368, and the tetracarboxylic acid dianhydrides of formulas [CA-1] to [CA-26] and their derivatives. Furthermore, the specified tetracarboxylic acid component and the other tetracarboxylic acid components can be used individually or in combination of two or more, depending on their respective properties.

[0049]

[0050]

[0051] The method for synthesizing polyimide polymers is not particularly limited. They are usually obtained by reacting a diamine component with a tetracarboxylic acid component. Specific examples include the method described in paragraphs

[0059] and

[0059] of WO2015 / 012368. Known methods for synthesizing polyamic acid esters include, for example, reacting the polyamic acid of a polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component with an esterifying agent, reacting the tetracarboxylic acid diester with a diamine, or reacting the tetracarboxylic acid diester dihalide with the tetracarboxylic acid dihalide. The solvent used in the reaction between the diamine component and the tetracarboxylic acid component is not particularly limited as long as the resulting polyimide precursor is soluble. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or 1,3-dimethylimidazolidinone. Furthermore, if the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents of the following formulas [D1] to [D3] can be used.

[0052] (D １ and D ２ This represents an alkyl group having 1 to 3 carbon atoms. ３ ) indicates an alkyl group having 1 to 4 carbon atoms. These may be used individually or in combination. Furthermore, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above solvent as long as precipitation does not occur. Also, since water in the solvent inhibits the polymerization reaction and can cause hydrolysis of the polyimide precursor, it is preferable to use a dehydrated and dried solvent. For the polymerization reaction of the polyimide precursor, the total number of moles of tetracarboxylic acid components is preferably 0.8 to 1.2 when the total number of moles of diamine components is 1.0. If the total number of moles of tetracarboxylic acid components is less than 1.0, that is, if the total number of moles of tetracarboxylic acid components is less than the number of moles of diamine components, the polymer ends will have an amino group structure, and if it is greater than 1.0, that is, if the total number of moles of tetracarboxylic acid components is greater than the number of moles of diamine components, the polymer ends will have a carboxylic acid anhydride or dicarboxylic acid structure. Polyimide is obtained by ring-closing the polyimide precursor, and its imidization rate does not necessarily have to be 100%, and can be prepared arbitrarily depending on the application and purpose. In particular, from the viewpoint of solubility in the solvent, 30 to 90% is preferred. More preferably, 40 to 90%. The polyimide polymer may also be a end-sealed polymer using an end-sealing agent. End-sealed polymers have the effect of increasing the film hardness of the liquid crystal alignment film and improving the adhesion between the liquid crystal alignment film and the sealant in liquid crystal display elements. Furthermore, the method for obtaining the end-sealed polymer is not particularly limited. Specific examples include the method described in paragraphs

[0046] and

[0047] of WO2023 / 074568. From the viewpoint of the strength of the liquid crystal alignment film obtained therefrom, workability during film formation, and coating properties, the molecular weight of the polyimide polymer is preferably 5,000 to 1,000,000 in terms of Mw (weight-average molecular weight) in terms of polyethylene glycol oxide, measured by the GPC (Gel Permeation Chromatography) method. A more preferable range is 10,000 to 150,000.

[0053] <Liquid Crystal Alignment Agent> A liquid crystal alignment agent is a solution for forming a liquid crystal alignment film, and is a solution containing a polymer component including a specific polymer and a solvent. In this case, two or more types of specific polymers can be used. Not all of the polymer components are specific polymers; polyimide polymers that do not use specific diamines or polymers other than polyimide polymers may be mixed in. Specifically, examples include polysiloxane, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly(styrene-maleic anhydride) copolymer, poly(isobutylene-maleic anhydride) copolymer, poly(vinyl ether-maleic anhydride) copolymer, poly(styrene-phenylmaleimide) derivative, or poly(meth)acrylate. Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, SMA2000, SMA3000 (manufactured by Cray Valley Co., Ltd.), and GSM301 (manufactured by Gifu Cerator Co., Ltd.). A specific example of a poly(isobutylene-maleic anhydride) copolymer is Isoban-600 (manufactured by Kuraray Co., Ltd.). A specific example of a poly(vinyl ether-maleic anhydride) copolymer is Gantrez AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by Ashland Corporation).

[0054] In the present invention, when a specific polymer and other polymers are used as polymer components, the other polymer is preferably a polyimide polymer that does not use a specific diamine (hereinafter also referred to as "other polyimide polymer") from the viewpoint of the electrical properties of the liquid crystal display element (suppression of DC-derived afterimages). The tetracarboxylic acid component used in this case can be the tetracarboxylic acid component mentioned above. Specifically, this includes acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, or derivatives thereof. More specifically, it is preferable to use a tetracarboxylic acid dianhydride or derivative thereof having at least one substructure selected from a benzene ring, cyclobutane ring, cyclopentane ring, and cyclohexane ring. The usage ratio of these tetracarboxylic acid components is preferably 10 mol% or more, more preferably 20 mol% or more, and most preferably 50 mol% or more, relative to 1 mole of the total tetracarboxylic acid components used in the other polyimide polymer. Furthermore, these tetracarboxylic acid components can be used one type or a mixture of two or more types depending on the characteristics.

[0055] Furthermore, the diamine component can be any of the aforementioned diamine components. In particular, examples include the specific diamine, a diamine having a urea bond, a diamine having an amide bond, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(3-amino-4-methylphenyl)propane, 4,4'-diaminobenzophenone, a diamine having the specific nitrogen atom-containing structure, a diamine having a carboxyl group, a semi-aromatic diamine having a primary amino group and a secondary amino group, or 4-(2-aminoethyl)aniline. The proportion of these diamine components used is preferably 10 mol% or more, relative to 1 mole of all diamine components used in other polyimide polymers. More preferably, it is 20 mol% or more. Furthermore, it is preferably 90 mol% or less, relative to 1 mole of all diamine components used in other polyimide polymers. More preferably, it is 80 mol% or less. In addition, these diamine components can be used individually or in mixtures of two or more types, depending on their respective properties.

[0056] When a specific polymer and other polymers are used as polymer components, the proportion of the other polymer used is preferably 90 parts by mass or less, relative to 100 parts by mass of the total polymers contained in the liquid crystal alignment agent. More preferably, it is 10 to 90 parts by mass. Most preferably, it is 20 to 80 parts by mass.

[0057] The solvent content in the liquid crystal alignment agent can be appropriately selected from the viewpoint of the coating method of the liquid crystal alignment agent and the desired film thickness. In particular, from the viewpoint of forming a uniform liquid crystal alignment film by coating, the solvent content in the liquid crystal alignment agent is preferably 50 to 99.9% by mass. More preferably, it is 60 to 99% by mass. Particularly preferred is 65 to 99% by mass.

[0058] The solvent used in the liquid crystal alignment agent is not particularly limited as long as it is a solvent that dissolves the specific polymer. In particular, the following solvents (hereinafter also referred to as "solvent A") are preferred. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropaneamide Examples include 3-butoxy-N,N-dimethylpropanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (hereinafter collectively referred to as "good solvents"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, or γ-butyrolactone are particularly favored. These may be used individually or in combination of two or more.

[0059] If the specific polymer has high solubility in a solvent, the following solvents (hereinafter also referred to as "solvents of type B") can be used.For example, diisopropyl ether, diisobutyl ether, diisobutylcarbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxyethoxy) Examples include xy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, ethylene glycol monoethyl ether, n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, or diisobutyl ketone (2,6-dimethyl-4-heptanone).In particular, it is preferable to use diisobutylcarbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone. These may be used individually or in combination of two or more.

[0060] In the present invention, from the viewpoint of coating properties of the liquid crystal alignment film, it is preferable to use a solvent that combines solvent A and solvent B. Specific examples include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-di Methyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyllactamide and ethylene glycol monobutyl ether, N,N-dimethyllactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone N-methyl-2-pyrrolidone and diethylene glycol monoethyl ether and butyl cellosolve acetate, N-methyl-2-pyrrolidone and diethylene glycol monomethyl ether and butyl cellosolve acetate, N,N-dimethyllactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone,N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4- Methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2- Roridone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutylcarbinol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and dipro Pyrene glycol monomethyl ether, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone and γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone and N,N-dimethyllactamide and diisobutyl ketone,Examples include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether and ethylene glycol monobutyl ether acetate, γ-butyrolactone and ethylene glycol monobutyl ether acetate and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone and 4-methyl-2-pentyl acetate and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and cyclohexyl acetate and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone and propylene glycol monomethyl ether, cyclopentanone and propylene glycol monomethyl ether, or N-methyl-2-pyrrolidone and cyclohexanone and propylene glycol monomethyl ether, and combinations of these are preferred.

[0061] When solvent A and solvent B are used in combination, solvent B is preferably 1 to 99% by mass of the total solvent contained in the liquid crystal alignment agent. More preferably, 10 to 99% by mass is preferred. Most preferably, 20 to 95% by mass is preferred.

[0062] The liquid crystal alignment agent can be a compound that promotes the imidation of a specific polymer. Specifically, compounds having a basic site (e.g., a primary amino group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring, an indole ring), or a guanidino group, etc.) (excluding the crosslinking compounds and adhesion aids described below), or compounds that generate the basic site during firing are preferred. More specifically, formulas [B-1] to [B-17] below are examples, and it is preferable to use these. The proportion of the liquid crystal alignment agent used is preferably 0.1 to 20 parts by mass, more preferably 1 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, per 100 parts by mass of all polymer components.

[0063] (D represents an organic group that is eliminated by heating, preferably a tert-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group. If there are multiple D groups, they may be the same or different from one another.)

[0064] In order to increase the film strength of the liquid crystal alignment film, it is preferable to introduce a compound having at least one structure selected from epoxy groups, isocyanate groups, oxetanyl groups, oxazoline groups, cyclocarbonate groups, hydroxyl groups, hydroxyalkyl groups, lower alkoxyalkyl groups, and polymerizable unsaturated groups (hereinafter collectively referred to as "crosslinkable compounds"). In this case, the compound must contain two or more of these groups.

[0065] Specific examples of crosslinkable compounds having epoxy groups or isocyanate groups include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, dibromo neopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, bisphenol A type epoxy resins such as Epicote 828 (manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins such as Epicote 807 (manufactured by Mitsubishi Chemical Corporation), and YX-8000 (manufactured by Mitsubishi Chemical Corporation). Compounds in which a tertiary nitrogen atom is bonded to an aromatic carbon atom, such as hydrogenated bisphenol A epoxy resins like YX6954BH30 (manufactured by Mitsubishi Chemical Corporation), biphenyl skeleton-containing epoxy resins like EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o,m,p-) cresol novolac epoxy resins like EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), tetrakis(glycidyloxymethyl)methane, N,N,N',N'-tetraglycidyl-1,4-phenylenediamine, N,N,N',N'-tetraglycidyl-2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis[4-(N,N-diglycidyl-4-aminophenoxy)phenyl]propane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane;N,N,N',N'-tetraglycidyl-1,2-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,3-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,4-diaminocyclohexane, bis(N,N-diglycidyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-2-methyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-3-methyl-4-aminocyclohexyl)methane, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,4-bis(N,N-diglycidylaminomethyl)cyclohexane, 1 Examples include compounds in which a tertiary nitrogen atom is bonded to an aliphatic carbon atom, such as 3-bis(N,N-diglycidylaminomethyl)benzene, 1,4-bis(N,N-diglycidylaminomethyl)benzene, 1,3,5-tris(N,N-diglycidylaminomethyl)cyclohexane, and 1,3,5-tris(N,N-diglycidylaminomethyl)benzene; isocyanurate compounds such as triglycidyl isocyanurate (manufactured by Nissan Chemical Corporation); and those described in paragraph

[0037] of Japanese Patent Publication No. 10-338880 and paragraphs

[0051] to

[0054] of WO2017 / 170483.

[0066] Specific examples of crosslinkable compounds having an oxetanyl group include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene (Aronoxetane OXT-121 (XDO)), bis[2-(3-oxetanyl)butyl]ether (Aronoxetane OXT-221 (DOX)), 1,4-bis[(3-ethyloxetan-3-yl)methoxy]benzene (HQOX), 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene (RSOX), 1,2-bis[(3-ethyloxetan-3-yl)methoxy]benzene (CTOX), and those described in paragraphs

[0170] to

[0175] of WO2011 / 132751.

[0067] Specific examples of crosslinkable compounds having an oxazoline group include compounds such as 2,2'-bis(2-oxazoline) and 2,2'-bis(4-methyl-2-oxazoline), polymers and oligomers having an oxazoline group such as Epocross (manufactured by Nippon Shokubai Co., Ltd.), and those described in paragraph

[0115] of Japanese Patent Publication No. 2007-286597. Specific examples of crosslinkable compounds having a cyclocarbonate group include N,N,N',N'-tetra[(2-oxo-1,3-dioxolan-4-yl)methyl]-4,4'-diaminodiphenylmethane, N,N'-di[(2-oxo-1,3-dioxolan-4-yl)methyl]-1,3-phenylenediamine, and those described in paragraphs

[0025] to

[0030] and paragraph

[0032] of WO2011 / 155577. Specific examples of crosslinkable compounds having a blocked isocyanate group include Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate MS-50 (all manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (all manufactured by Mitsui Chemicals, Inc.), and those described in paragraphs

[0046] to

[0047] of Japanese Patent Publication No. 2014-224978 and paragraphs

[0119] to

[0120] of WO2015 / 141598.

[0068] Specific examples of crosslinkable compounds having a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group include N,N,N',N'-tetrakis(2-hydroxyethyl)adipoamide, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethoxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)-1,1,1,3,3,3-hexafluoropropane, and those described in paragraph

[0058] of Japanese Patent Publication No. 2016-118753, paragraph

[0055] of Japanese Patent Publication No. 2016-200798, and paragraphs

[0017] to

[0029] of WO2010 / 074269. Specific examples of crosslinkable compounds having polymerizable unsaturated groups include glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-,1,3-compound mixture), glycerin tris(meth)acrylate, glycerol 1,3-diglycerolate di(meth)acrylate, pentaerythritol tri(meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, pentaethylene glycol mono(meth)acrylate, and hexaethylene glycol mono(meth)acrylate.

[0069] The amount of crosslinkable compound used in the liquid crystal alignment agent is preferably 0.1 to 100 parts by mass per 100 parts by mass of all polymer components. More preferably, from the viewpoint of allowing the crosslinking reaction to proceed and the desired effect to be achieved, it is 0.1 to 50 parts by mass. Particularly preferred is 1 to 30 parts by mass.

[0070] The liquid crystal alignment agent can also be a compound that enhances the uniformity of the film thickness and surface smoothness of the liquid crystal alignment film, or a compound that improves the adhesion between the liquid crystal alignment film and the substrate. Examples of compounds that enhance the uniformity of the film thickness and surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, silicone-based surfactants, or nonionic surfactants. Specific examples include the surfactant described in paragraph

[0122] of WO2014 / 171493. The preferred usage ratio is 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of all polymer components. Specific examples of compounds that improve the adhesion between the liquid crystal alignment film and the substrate include the compound described in paragraph

[0123] of WO2014 / 171493. The preferred usage ratio is 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of all polymer components.

[0071] In addition to the compounds mentioned above, the liquid crystal alignment agent may also include dielectric or conductive materials intended to alter the electrical properties of the liquid crystal alignment film, such as its dielectric constant and conductivity.

[0072] <Liquid crystal alignment film / Liquid crystal display element> A liquid crystal display element can be manufactured, for example, by a method including the following steps (1) to (3), a method including steps (1) to (4), a method including steps (1) to (3), (3b) and (4), a method including steps (1) to (2) and (4), a method including steps (1) to (3), (4) and (5), or a method including steps (1) to (3), (4) and (6).

[0073] <Step (1): Step of applying liquid crystal alignment agent to at least one of the first and second substrates> Step (1) is a step of applying a liquid crystal alignment agent to a substrate. A specific example is as follows: That is, a liquid crystal alignment agent is applied to one surface of a substrate on which a patterned transparent conductive film is provided, by an application method such as a roll coater, spin coat, printing, or inkjet. The substrate is not particularly limited as long as it is a highly transparent substrate, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used along with glass substrates and silicon nitride substrates. In addition, in reflective liquid crystal display elements, an opaque substrate such as a silicon wafer can be used on only one side of the substrate, and in this case, light-reflecting materials such as aluminum can be used for the electrodes.

[0074] When manufacturing IPS-driven or FFS-driven liquid crystal display elements, a substrate is used that has electrodes made of a comb-shaped patterned transparent conductive film or metal film, and a counter substrate is used that does not have electrodes. The transparent conductive film is formed by known methods using indium tin oxide (ITO), indium zinc oxide (IZO), or mixtures thereof. Methods for applying the liquid crystal alignment agent to the substrate include screen printing, offset printing, flexographic printing, inkjet printing, or spray printing. Among these, the inkjet printing method is preferred in the present invention.

[0075] <Step (2): Step of firing the coated liquid crystal alignment agent> Step (2) is a step of firing the liquid crystal alignment agent coated on the substrate to form a liquid crystal alignment film. Specifically, it is as follows: That is, after coating the substrate with liquid crystal alignment agent in step (1), the solvent is evaporated or the polyamic acid or polyamic acid ester is thermally imidized by firing using a heating means such as a hot plate, a heat circulation oven or an IR (infrared) oven (hereinafter this process is also called the "firing step"). The temperature and time of the firing step can be arbitrarily selected, and the firing step may be repeated multiple times. The temperature of the firing step is preferably 30 to 230°C. More preferably 30 to 200°C. If the residual solvent in the liquid crystal alignment film is to be reduced, it may be 40 to 150°C or 40 to 120°C. The firing time is not particularly limited, but examples include 1 to 10 minutes or 1 to 5 minutes. When performing thermal imidation of polyimide precursors such as polyamic acid or polyamic acid esters, an additional firing (hereinafter referred to as the "main firing process") may be performed after the firing process. The temperature at this time is preferably 150 to 230°C. More preferably 150 to 200°C. Particularly preferred is 160 to 200°C. Most preferably 160 to 190°C. The firing time for the main firing process is not particularly limited, but examples include 5 to 40 minutes or 5 to 30 minutes. Note that the main firing process may not be performed in step (2), and the main firing process or step (3b) may be performed after step (3) below. The film thickness of the liquid crystal alignment film after firing is preferably 5 to 300 nm, more preferably 10 to 200 nm, because if it is too thick, it will be disadvantageous in terms of the power consumption of the liquid crystal display element, and if it is too thin, the reliability of the element may decrease.

[0076] <Step (3): Step of applying alignment treatment to the liquid crystal alignment film obtained in Step (2)> Step (3) is a step of applying alignment treatment to the liquid crystal alignment film obtained in Step (2). In lateral electric field driven liquid crystal display elements such as IPS drive system and FFS drive system, as described above, in order to align the liquid crystal horizontally, the liquid crystal alignment film is subjected to alignment treatment such as rubbing treatment or optical alignment treatment. In the present invention, optical alignment treatment is preferred. On the other hand, in vertical electric field driven liquid crystal display elements such as VA (Vertical Alignment) drive system and PSA (Polymer Sustained Alignment) drive system, alignment treatment is not required.

[0077] Rubbing is a process in which a liquid crystal alignment film is rubbed in a specific direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton. Photo-alignment is a method in which the surface of the liquid crystal alignment film is irradiated with radiation polarized in a specific direction to regulate the alignment of the liquid crystals (hereinafter also referred to as "imparting liquid crystal alignment properties or liquid crystal alignment ability"). The radiation can be ultraviolet light or visible light having a wavelength of 100 to 800 nm. Of these, ultraviolet light with a wavelength of 100 to 400 nm is preferred. More preferably, ultraviolet light with a wavelength of 200 to 400 nm is preferred. The radiation dose is 1 to 10,000 mJ / cm². ２ This is preferable. More preferably, 100 to 1,000 mJ / cm². ２ A particularly preferred range is 100 to 500 mJ / cm². ２ Furthermore, if the radiation is polarized, it may be linearly polarized or partially polarized. Also, if the radiation is linearly polarized or partially polarized, the irradiation may be performed perpendicular to the liquid crystal alignment film surface, at an angle, or a combination of both. When irradiating with unpolarized radiation, it is preferable that the irradiation direction be at an angle to the liquid crystal alignment film surface. When irradiating with radiation, it is preferable to irradiate the substrate with the liquid crystal alignment film while heating it at 50 to 250°C in order to improve the stability of the liquid crystal alignment. This makes it possible to stably align the liquid crystal in a certain direction.

[0078] <Step (3b): Heat treatment step> The liquid crystal alignment film irradiated with the radiation plug in step (3) can be subjected to heat treatment. The temperature at this time is preferably 50 to 250°C. More preferably 120 to 230°C. The time is preferably 1 to 30 minutes.

[0079] <Step (4): Step of manufacturing a liquid crystal cell (liquid crystal display element) by arranging a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the oriented liquid crystal alignment film> Step (4) is a step of manufacturing a liquid crystal cell by arranging a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the oriented liquid crystal alignment film. The following is an example of a case in which a liquid crystal alignment film is formed on each of the first and second substrates. In the first method, first, two substrates are placed facing each other with a gap (hereinafter also called "cell gap") between them so that their respective liquid crystal alignment films face each other. Next, the peripheral parts of the two substrates are bonded together using a sealant, and a liquid crystal composition is injected and filled into the cell gap partitioned by the substrate surface and the sealant, and after contact with the liquid crystal alignment film surface, the injection hole is sealed. The second method is a method called the ODF (One Drop Filling) method. In the first and second methods, a UV-curable resin composition (hereinafter also referred to as "sealant") is applied to a predetermined location on one of two substrates on which a liquid crystal alignment film is formed, and then liquid crystal composition is dropped onto several predetermined locations on the surface of the liquid crystal alignment film. After that, the other substrate is bonded together so that the liquid crystal alignment films face each other, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant. In both the first and second methods, it is desirable to heat the liquid crystal composition to a temperature at which it forms an isotropic phase, and then slowly cool it to room temperature to remove the flow orientation during the filling of the liquid crystal composition. When the rubbing process is performed, the two substrates are arranged facing each other so that the rubbing directions of each liquid crystal alignment film are at a predetermined angle to each other, for example, orthogonal or antiparallel.

[0080] The sealant can be an epoxy resin containing a curing agent and aluminum oxide spheres as spacers. There are no particular restrictions on the liquid crystal composition; any composition containing at least one liquid crystal compound (liquid crystal molecule) can be used, and various liquid crystal compositions with positive or negative dielectric anisotropy can be used. In the following, a liquid crystal composition with positive dielectric anisotropy will also be called a positive-type liquid crystal, and a liquid crystal composition with negative dielectric anisotropy will also be called a negative-type liquid crystal. The liquid crystal composition may contain a liquid crystal compound having a fluorine atom, a hydroxyl group, an amino group, a fluorine atom-containing group (e.g., a trifluoromethyl group), a cyano group, an alkyl group, an alkoxy group, an alkenyl group, an isothiocyanate group, a heterocycle, a cycloalkane, a cycloalkene, a steroid skeleton, a benzene ring, or a naphthalene ring, and may also contain a compound having two or more rigid parts (mesogenic skeletons) that exhibit liquid crystallinity within the molecule (e.g., a bimesogenic compound in which two rigid biphenyl or terphenyl structures are linked by an alkylene group). The liquid crystal composition may be a liquid crystal composition exhibiting a nematic phase, a liquid crystal composition exhibiting a smectic phase, or a liquid crystal composition exhibiting a cholesteric phase. Furthermore, the liquid crystal composition may contain additives from the viewpoint of improving liquid crystal orientation. Examples of additives include photopolymerizable monomers such as compounds having polymerizable groups; optically active compounds (for example, S-811 manufactured by Merck KGaA); antioxidants; ultraviolet absorbers; dyes; defoamers; polymerization initiators; or polymerization inhibitors.

[0081] Positive-type liquid crystals include Merck's ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, or MLC-7081; and DIC's PA-1492. Negative-type liquid crystals include Merck's MLC-6608, MLC-6609, MLC-6610, or MLC-7026-100. Liquid crystals containing polymerizable compounds include Merck's MLC-3023.

[0082] The liquid crystal alignment agent can also be used in liquid crystal display elements (PSA type liquid crystal display elements) manufactured by a process (hereinafter referred to as "step (5)") in which a liquid crystal composition containing a polymerizable compound that polymerizes by at least one of active energy rays and heat is placed between the pair of substrates, and the polymerizable compound is polymerized by irradiation with active energy rays and heating while a voltage is applied between the electrodes. The liquid crystal alignment agent can also be used in liquid crystal display elements (SC-PVA type liquid crystal display elements) manufactured by a process (hereinafter referred to as "step (6)") in which a liquid crystal alignment film containing a polymerizable group that polymerizes by at least one of active energy rays and heat is placed between the pair of substrates, and a voltage is applied between the electrodes. The liquid crystal cell obtained as described above can have a polarizing plate bonded to its outer surface if necessary. Examples of polarizing plates that are bonded to the outer surface of liquid crystal cells include polarizing plates in which a polarizing film called an "H film," which is made by stretching and oriented polyvinyl alcohol while absorbing iodine, is sandwiched between cellulose acetate protective films, or polarizing plates made of an H film.

[0083] An IPS substrate, which is a comb-tooth electrode substrate used in an IPS drive system, has a substrate, a plurality of linear electrodes formed on the substrate and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the substrate so as to cover the linear electrodes. An FFS substrate, which is a comb-tooth electrode substrate used in an FFS system, has a substrate, a surface electrode formed on the substrate, an insulating film formed on the surface electrode, a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the insulating film so as to cover the linear electrodes.

[0084] Figure 1 is a schematic cross-sectional view showing an example of a transverse electric field type liquid crystal display element of the present invention, and is an example of an IPS-driven liquid crystal display element. In the transverse electric field type liquid crystal display element 1 illustrated in Figure 1, liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2c and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 has a substrate 2a, a plurality of linear electrodes 2b formed on the substrate 2a and arranged in a comb-tooth shape, and a liquid crystal alignment film 2c formed on the substrate 2a so as to cover the linear electrodes 2b. The counter substrate 4 has a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2c is, for example, the liquid crystal alignment film of the present invention. Similarly, the liquid crystal alignment film 4a is also the liquid crystal alignment film of the present invention. In this transverse electric field type liquid crystal display element 1, when a voltage is applied to the linear electrodes 2b, an electric field is generated between the linear electrodes 2b as shown by the electric field lines L.

[0085] Figure 2 is a schematic cross-sectional view showing another example of a transverse electric field driven liquid crystal display element, and is an example of an FFS driven liquid crystal display element. In the transverse electric field driven liquid crystal display element 1 illustrated in Figure 2, liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2h and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 has a substrate 2d, a surface electrode 2e formed on the substrate 2d, an insulating film 2f formed on the surface electrode 2e, a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb-tooth pattern, and a liquid crystal alignment film 2h formed on the insulating film 2f so as to cover the linear electrodes 2g. The counter substrate 4 has a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2h is, for example, the liquid crystal alignment film of the present invention. Similarly, the liquid crystal alignment film 4a is the liquid crystal alignment film of the present invention. In this transverse electric field driven liquid crystal display element 1, when a voltage is applied to the surface electrode 2e and the linear electrode 2g, an electric field is generated between the surface electrode 2e and the linear electrode 2g, as shown by the electric field lines L.

[0086] The liquid crystal display element of the present invention can be effectively applied to various devices. For example, it can be used in display devices such as clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, or information displays. The liquid crystal alignment film of the present invention can be applied to applications other than those described above. For example, it can be used as a liquid crystal alignment film for phase difference films, a liquid crystal alignment film for scanning antennas or liquid crystal array antennas, or a liquid crystal alignment film for transmission-scattering type liquid crystal dimming elements. Furthermore, it can be used in applications other than liquid crystal alignment films, such as protective films (e.g., protective films for color filters), spacer films, interlayer insulating films, anti-reflective films, wiring coating films, anti-static films, and motor insulating films (e.g., gate insulating films for flexible displays).

[0087] The present invention will be further described in detail below with reference to examples, but it is not limited to these. The abbreviations used in the examples and comparative examples, and the methods for measuring each physical property are as follows.

[0088] <Solvents> NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Ethylene glycol monobutyl ether <Specific diamines> DA-1 to DA-3, DA-7 and DA-8: Diamines of the following formulas [DA-1] to [DA-3], [DA-7] and [DA-8]

[0089] (tBu indicates a tert-butyl group.) <Other Diamines> DA-4 to DA-6: Diamines of the following formulas [DA-4] to [DA-6]

[0090]

[0091] <Specific Acid Dianhydrides> CA-1: Tetracarboxylic acid dianhydride of the following formula [CA-1]

[0092]

[0093] <Compounds that promote imidation> F-1: Compound of the following formula [F-1]

[0094] (Fmoc represents a 9-fluorenylmethyloxycarbonyl group. Boc represents a tert-butoxycarbonyl group.)

[0095] "Viscosity Measurement" Viscosity was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C, a sample volume of 1.1 mL, and a cone rotor TE-1 (1°34', R24).

[0096] "Synthesis of Specific Diamines" The specific diamines of formulas [DA-1] to [DA-3], [DA-7], and [DA-8] are novel compounds not published in the literature. Their synthesis methods are shown in Examples 1 to 3, Example 12, and Example 13. The structures of each compound and each specific diamine are as follows: １ Identified by 1H-NMR analysis. Instrument: Fourier transform superconducting nuclear magnetic resonance spectrometer (FT-NMR) "AVANCE III" (BRUKER) 500 MHz, Solvent: Deuterated dimethyl sulfoxide (DMSO-d ６ (Standard substance: tetramethylsilane)

[0097] <Example 1> Synthesis of a specific diamine of formula [DA-1]

[0098]

[0099] In a 1,000 mL round-necked flask, add Methyl 2-hydroxy-5-nitrobenzoate (24.8 g, 126.0 mmol), 1,2-Bis(tosyloxy)ethane (22.2 g, 60.0 mmol), and dimethylacetamide (DMAc) (200 g) and dissolve, then add potassium carbonate (K ２ CO ３ (24.9 g, 180.0 mmol) was added and the mixture was stirred at 100°C for 3 hours. After cooling the reaction mixture to 23°C, it was poured into pure water (870 g) and the precipitated crystals were filtered off. The obtained crystals were washed with pure water and methanol in that order and dried under reduced pressure to obtain compound [1-1] (yield: 20.6 g, 48.9 mmol, yield: 82%).

[0100] Next, compound [1-1] (19.6 g, 46.6 mmol) and tetrahydrofuran (THF) (390 g) were added to a 1,000 mL four-necked round-bottom flask and the mixture was purged with nitrogen. Then, carbon-supported palladium (5% by mass Pd carbon powder (50% hydrated), K type, manufactured by N.E. Chemcat) (1.96 g) was added and the mixture was purged with nitrogen again. A hydrogen tedlar bag was attached, and the mixture was stirred at 23°C for 21 hours. After the reaction was complete, the catalyst was filtered, and the filtrate was concentrated to 40 g. Isopropyl alcohol (IPA) (120 g) was added, and the mixture was stirred at 23°C for 30 minutes. The precipitated crystals were filtered under reduced pressure, washed with IPA, and then dried under reduced pressure at 40°C to obtain the specific diamine of formula [DA-1] (yield: 14.2 g, 39.4 mmol, yield 84%, white crystals). １ H-NMR (500MHz, DMSO-d ６ ): δ (ppm) = 6.88-6.94 (4H, m), 6.70-6.74 (2H, m), 4.94 (4H, s), 4.12 (4H, s), 3.72 (6H, s).

[0101] <Example 2> Synthesis of a specific diamine of formula [DA-2]

[0102]

[0103] In a 1,000 mL round-necked flask, methyl 2-hydroxy-5-nitrobenzoate (20.0 g, 101.5 mmol), 2-(4-nitropenoxy)ethyl methanesulfonate (26.5 g, 101.5 mmol), and DMAc (265 g) were added and dissolved. Then potassium carbonate (35.1 g, 253.4 mmol) was added, and the mixture was stirred at 100°C for 3 hours. After cooling the reaction mixture to 23°C, the precipitated salt was filtered off. The filtrate was poured into methanol (600 g) and pure water (700 g), and the precipitated crystals were filtered off. The obtained crystals were washed with pure water and methanol in that order, dried under reduced pressure, and compound [2-1] was obtained (yield: 29.9 g, 82.5 mmol, yield: 81%). Next, compound [2-1] (20.0 g, 55.2 mmol) and THF (200 g) were added to a 1,000 mL four-necked round-bottom flask, and the mixture was purged with nitrogen. Then, carbon-supported palladium (5% by mass Pd carbon powder (50% hydrated), K type, manufactured by N.E. Chemcat) (2.00 g) was added, the mixture was purged with nitrogen again, a hydrogen tedlar bag was attached, and the mixture was stirred at 23°C for 21 hours. After the reaction was complete, the catalyst was filtered, and the filtrate was concentrated to 40 g. IPA (120 g) was added, and the mixture was stirred at 23°C for 30 minutes. The precipitated crystals were filtered under reduced pressure, washed with IPA, and then dried under reduced pressure at 40°C to obtain the specific diamine of formula [DA-2] (yield: 14.9 g, 49.3 mmol, yield 89%, white crystals). １ H-NMR (500MHz, DMSO-d ６ ): δ (ppm) = 6.88-6.89 (2H, m), 6.66-6.70 (3H, m), 6.49-6.52 (2H, m), 4.94 (2H, s), 4.61 (2H, s), 4.05-4.15 (4H, m), 3.72 (3H, s).

[0104] <Example 3> Synthesis of a specific diamine of formula [DA-3]

[0105]

[0106] In a 1,000 mL four-necked eggplant flask, the above compound [1-1] (15.0 g, 35.8 mmol), methanol (105 g) and DMAc (105 g) were added and dissolved. Then, 2N aqueous sodium hydroxide solution (2N NaOH aq) (105 g) was added, and the mixture was stirred at 60 °C for 1 hour. After the reaction solution was cooled to 23 °C, the precipitated salt was filtered off and washed with methanol. The obtained salt was dissolved in pure water (500 g), neutralized by adding concentrated hydrochloric acid (7.50 g), and the precipitated crystals were filtered off. The obtained crystals were washed with pure water and methanol in that order and dried under reduced pressure to obtain compound [3-1] (yield: 8.80 g, 22.4 mmol, yield: 63%). Next, in a 500 mL four-necked flask, compound [3-1] (8.80 g, 22.4 mmol), 4,4'-dimethylaminopyridine (DMAP) (0.54 g, 4.5 mmol) and THF (88.0 g) were added and dissolved, and the mixture was heated to 60 °C. A solution prepared by dissolving di-tert-butyl dicarbonate (Boc ２ O) (21.4 g, 98.6 mmol) in THF (20.0 g) was slowly added dropwise using a dropping funnel. After the addition was complete, the mixture was stirred at 60 °C for 2 hours. The obtained reaction solution was concentrated to 70 g, IPA (88.0 g) was added, and the mixture was stirred at 23 °C for 30 minutes to precipitate crystals. The obtained crystals were filtered off, washed with IPA, and dried under reduced pressure at 40 °C to obtain compound [3-2] (yield: 7.40 g, 14.6 mmol, yield: 66%).

[0107] Next, in a 500 mL four-necked flask, compound [3-2] (7.40 g, 14.7 mmol) and THF (110 g) were added and the flask was purged with nitrogen. Then, palladium on carbon (5 mass% Pd carbon powder (50% water-containing product), type K, manufactured by N.E. Chemcat Corporation) (0.74 g) was added, and the flask was purged with nitrogen again. A hydrogen Tedlar bag was attached, and the mixture was stirred at 23 °C for 19 hours. After the reaction was completed, the catalyst was filtered off, and the filtrate was concentrated until it reached 15 g. IPA (60.0 g) was added, and the mixture was stirred at 23 °C for 30 minutes. The precipitated crystals were filtered under reduced pressure, washed with IPA, and dried under reduced pressure at 40 °C to obtain the specific diamine of formula [DA-3] (yield: 5.40 g, 12.1 mmol, yield 83%, white crystals). １ H-NMR (500 MHz, DMSO-d ６): δ(ppm) = 6.85 (2H, d), 6.78 (2H, d), 6.66 (2H, dd), 4.86 (4H, s), 4.11 (4H, s), 1.45 (18H, s). <Example 12> Synthesis of specific diamine of formula [DA-7] In a 2,000 mL round-necked flask, 4-Hydroxy-4'-nitrobiphenyl (50.0 g, 232.3 mmol) was dissolved in DMAc (300 g), and Ethylene Carbonate (43.0 g, 487.9 mmol) and sodium carbonate (12.3 g, 116.1 mmol) were added. The mixture was heated and stirred at 100°C for 18 hours. After cooling to 23°C, pure water (900 g) was added to crystallize, and the crystals were filtered off. The obtained crystals were washed with a cake of pure water and an ethanol / heptane = 1 / 5 mixed solution, and dried under reduced pressure at 60°C to obtain compound [7-1] (yield 58.2 g, 221.8 mmol, yield: 97%). In a 1,000 mL round-necked flask, compound [7-1] (50.0 g, 192.9 mmol), THF (250 g), and triethylamine (TEA, 29.3 g, 289.3 mmol) were added. After cooling to 0°C, ethanolazole chloride (EsCl) (32.2 g, 250.7 mmol) was slowly added dropwise. After the addition was complete, the mixture was stirred at 23°C for 2 hours until the starting material disappeared. Next, water (1250 g) was added and crystallization was performed, and the crystals were filtered off. The obtained crystals were washed with pure water and methanol, and dried under reduced pressure at 60°C to obtain compound [7-2] (yield 65.2 g, 185.6 mmol, yield: 96.2%). In a 1,000 mL round-necked flask, compound [7-2] (20.0 g, 56.9 mmol), Methyl 2-hydroxy-5-nitrobenzoate (12.4 g, 62.7 mmol), potassium carbonate (11.8 g, 85.5 mmol), and DMAc (120 g) were added, and the mixture was heated and stirred at 80°C for 16 hours. The resulting salt was then removed by filtration, and pure water (553 g) was added to the filtrate to induce crystallization. The obtained crystals were filtered off, the cake was washed with pure water and methanol, and the crude product was dried under reduced pressure at 60°C. DMF (404 g) and activated carbon (2.0 g) were added to the crude product, and the mixture was stirred at 60°C for 1 hour. The activated carbon was removed using a membrane filter, and the filtrate was drained into pure water (808 g). The obtained crystals were filtered off, the cake was washed with pure water and methanol, and dried under reduced pressure at 60°C to obtain compound [7-3] (yield 18.7 g, 42.7 mmol, yield: 75%).Compound [7-3] (17.7 g, 40.4 mmol) and DMF (265.8 g) were added to a 1,000 mL four-necked round-bottom flask and nitrogen was purged. Then, carbon-supported palladium (5% by mass Pd carbon powder (50% hydrated), K type, manufactured by N.E. Chemcat) (3.5 g) was added and nitrogen was purged again. A hydrogen Tedlar bag was attached, and the mixture was heated and stirred at 50°C for 26 hours. After filtering the catalyst, it was concentrated to approximately 60 g, and IPA (89 g) was added and stirred at 23°C for 30 minutes. The precipitated crystals were filtered under reduced pressure and washed with IPA, then dried under reduced pressure at 40°C to obtain the specific diamine of formula [DA-7] (yield: 14.6 g, 38.6 mmol, yield 95%, blackish-gray crystals). １ H-NMR (500MHz, DMSO-d ６ ): δ(ppm) = 7.43–7.46 (2H,m), 7.27–7.30 (2H,m), 6.96–6.98 (2H,m), 6.93 (1H,d), 6.89 (1H,d), 6.74 (1H,dd), 6.60–6.63 (2H,m), 5.10 (2H,s), 4.95 (2H,s), 4.19–4.33 (4H,m), 3.72 (3H,s). <Example 13> Synthesis of a specific diamine of formula [DA-8] In a 1,000 mL round-necked flask, 1-Bromo-4-chlorobutane (29.6 g, 172.5 mmol), potassium carbonate (29.8 g, 215.7 mmol), and DMF (140 g) were added and heated and stirred at 40°C. Next, 4-Nitrophenol (20.0 g, 143.7 mmol) was dissolved in DMF (60 g) and added dropwise over 1 hour, stirring for 2 hours. After cooling to 23°C, ethyl acetate (600 g) and pure water (300 g) were added, and the organic layer was extracted and washed twice with pure water (200 g). The organic layer was extracted and fully concentrated, then dried using an oil pump until it weighed approximately 33 g. Heptane (163 g) was added to the oily crude mixture and stirred in an ice bath at -10°C to gradually solidify it. After further stirring while loosening the solidified crystals, the crystals were filtered off. Subsequently, the cake was washed with heptane cooled to 0°C, and the resulting crystals were dried under reduced pressure at 60°C to obtain compound [8-1] (yield 30.5 g, 132.8 mmol, yield: 92%). Compound [8-1] (28.3 g, 123.3 mmol), Methyl 2-hydroxy-5-nitrobenzoate (22.1 g, 112.1 mmol), potassium carbonate (23.4 g, 168.1 mmol), potassium iodide (1.9 g, 12.3 mmol), and DMAc (133 g) were added to a 1,000 L round-necked flask, and the mixture was heated and stirred at 80°C for 19 hours. Then, pure water (553 g) was added to induce crystallization. The obtained crystals were filtered off, the cake was washed with pure water and methanol, and the crude product was dried under reduced pressure at 60°C. To the obtained crude material, acetonitrile (60 g) was added and dissolved at 60°C. Insoluble matter was removed by hot filtration, and the filtrate was stirred at 23°C to crystallize. Methanol (80 g) was added and crystallization was further carried out. After filtering off the crystals, the cake was washed with acetonitrile and methanol, and the compound [8-2] was obtained by vacuum drying at 60°C (yield 31.2 g, 80.1 mmol, yield: 71%). Compound [8-2] (31.2 g, 80.1 mmol) and THF (250 g) were added to a 1,000 mL four-necked round-bottom flask and nitrogen was purged. Then, carbon-supported palladium (5% by mass Pd carbon powder (50% hydrated) K type, manufactured by N.E. Chemcat) (3.1 g) was added and nitrogen was purged again. A hydrogen Tedlar bag was attached, and the mixture was stirred at 23°C for 19 hours.After filtering the catalyst, it was concentrated to approximately 30 g, and heptane (60 g) was added. The mixture was stirred at 23°C for 60 minutes. The precipitated crystals were filtered under reduced pressure, washed with ethyl acetate / heptane = 1 / 3, and then dried under reduced pressure at 40°C to obtain the specific diamine of formula [DA-8] (yield: 25.2 g, 76.2 mmol, yield 95%, pinkish-white crystals). １ H-NMR (500MHz, DMSO-d ６ ): δ (ppm) = 6.89 (1H, d), 6.84 (1H, d), 6.72 (1H, dd), 6.63-6.65 (2H, m), 6.48-6.50 (2H, m), 4.87 (2H, s), 4.56 (2H, s), 3.90 (4H, dt), 3.73 (3H, s), 1.81-1.75 (4H, m).

[0108] "Synthesis of Polyimide Polymers" <Example 4> DA-4 (0.54 g, 5.00 mmol), DA-1 (1.80 g, 5.00 mmol), and NMP (23.7 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Then, under ice cooling, CA-1 (2.11 g, 9.40 mmol) and NMP (8.95 g) were added, and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-1) with a solid content of 12% by mass (viscosity: 349 mPa·s).

[0109] <Example 5> DA-4 (0.54 g, 5.00 mmol), DA-2 (1.51 g, 5.00 mmol), and NMP (20.8 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Then, under ice cooling, CA-1 (2.11 g, 9.40 mmol) and NMP (9.75 g) were added, and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-2) with a solid content of 12% by mass (viscosity: 362 mPa·s).

[0110] <Example 6> DA-4 (0.43 g, 4.00 mmol), DA-3 (1.78 g, 4.00 mmol), and NMP (22.4 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Then, under ice cooling, CA-1 (1.70 g, 7.60 mmol) and NMP (6.35 g) were added, and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-3) with a solid content of 12% by mass (viscosity: 269 mPa·s). <Example 14> DA-4 (0.54 g, 5.00 mmol), DA-7 (1.89 g, 5.00 mmol), and NMP (24.6 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Subsequently, under ice cooling, CA-1 (2.08 g, 9.30 mmol) and NMP (8.53 g) were added and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-6) with a solid content of 12% by mass (viscosity: 223 mPa·s). <Example 15> DA-4 (0.54 g, 5.00 mmol), DA-8 (1.65 g, 5.00 mmol), and NMP (22.2 g) were added to a 50 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Subsequently, CA-1 (2.10 g, 9.40 mmol) and NMP (9.36 g) were added under ice cooling and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-7) with a solid content of 12% by mass (viscosity: 396 mPa·s).

[0111] <Comparative Example 1> DA-4 (0.81 g, 7.50 mmol), DA-5 (1.83 g, 7.50 mmol), and NMP (30.4 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Then, under ice cooling, CA-1 (3.19 g, 14.2 mmol) and NMP (12.4 g) were added, and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-4) with a solid content of 12% by mass (viscosity: 462 mPa·s).

[0112] <Comparative Example 2> DA-4 (0.70 g, 6.50 mmol), DA-6 (1.77 g, 6.50 mmol), and NMP (25.0 g) were added to a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at room temperature while supplying nitrogen. Then, under ice cooling, CA-1 (2.77 g, 12.4 mmol) and NMP (13.4 g) were added, and the mixture was stirred at 40°C for 12 hours to obtain a polyamic acid solution (PAA-5) with a solid content of 12% by mass (viscosity: 289 mPa·s). The specifications of the polyimide polymer are shown in Table 1. In Table 1, the numbers in parentheses indicate the amount (moles) used of the tetracarboxylic acid component and the diamine component.

[0113]

[0114] "Manufacturing of Liquid Crystal Alignment Agents" Examples 7 to 11, 16, 17, Comparative Example 3, and Comparative Example 4 below describe examples of liquid crystal alignment agents. These liquid crystal alignment agents are used for evaluating liquid crystal display elements. The specifications of the liquid crystal alignment agents are shown in Table 2.

[0115] "Evaluation of Liquid Crystal Alignment" First, a liquid crystal cell using an FFS drive system was fabricated using the liquid crystal alignment agent obtained by the methods of the examples and comparative examples. A rectangular glass substrate measuring 30 mm x 35 mm with a thickness of 0.7 mm was used as the substrate. An ITO electrode with a solid pattern, forming a common electrode, was formed on the substrate as the first layer. A SiN (silicon nitride) film deposited by CVD (chemical vapor deposition) was formed on the first layer common electrode as the second layer. The thickness of the second SiN film was 300 nm, which was sufficient to function as an interlayer insulating film. On the second SiN film, a comb-shaped pixel electrode formed by patterning the ITO film was arranged as the third layer, forming two pixels, the first and second pixels, with each pixel measuring 10 mm vertically and 5 mm horizontally. This electrode-equipped substrate had a structure in which the first layer common electrode and the third layer pixel electrode were insulated by the second layer SiN film. The third layer of pixel electrodes had a comb-like shape, with the central portion bent at an internal angle of 160°, and multiple electrode lines with a width of 3 μm arranged parallel to each other at intervals of 6 μm. Each pixel was formed by multiple electrode lines and had a first region and a second region separated by a line connecting the bends.

[0116] Next, the liquid crystal alignment agent was filtered through a filter with a pore size of 1.0 μm, and then spin-coated onto the electrode substrate (hereinafter also referred to as the "electrode substrate") and a glass substrate (hereinafter also referred to as the "opposing substrate") having a columnar spacer with a height of 4 μm on which an ITO electrode was deposited on the back surface. After that, the substrates were dried on an 80°C hot plate for 2 minutes, and then baked in an infrared heating furnace at 180°C for 30 minutes to obtain an electrode substrate and an opposing substrate with a liquid crystal alignment film thickness of 100 nm. The liquid crystal alignment film surface of both substrates was irradiated with 254 nm polarized ultraviolet light via a 240 nm low-cut filter and polarizer at the irradiation doses listed in Table 3 (optimal irradiation doses for each liquid crystal alignment agent), and then baked in an infrared heating furnace at 180°C for 30 minutes to obtain an electrode substrate and an opposing substrate with an alignment-treated liquid crystal alignment film. As a result, the liquid crystal alignment film on the electrode substrate is oriented so that the direction dividing the inner angle of the pixel bending portion is perpendicular to the orientation direction of the liquid crystal, and the liquid crystal alignment film on the opposing substrate is oriented so that the orientation direction of the liquid crystal on the electrode substrate matches the orientation direction of the liquid crystal on the opposing substrate when creating the liquid crystal cell.

[0117] A pair of electrode substrates with liquid crystal alignment films and opposing substrates, which had undergone the above alignment treatment, were prepared. A thermosetting sealant (XN-1500T, manufactured by Mitsui Chemicals, Inc.) was printed around the liquid crystal alignment film surface of one substrate, leaving a liquid crystal injection port. Next, the other substrate was placed with its liquid crystal alignment film surface facing inward, and the two substrates were bonded together so that the orientation direction of each liquid crystal alignment film was 0°. After bonding, the bonded substrates were pressed together and heated in a 150°C hot air circulating oven for 60 minutes to cure the sealant and create an empty cell. Positive-type liquid crystal (MLC-3019, manufactured by Merck, Inc.) was injected into this empty cell by a reduced-pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell (hereinafter also referred to as "liquid crystal cell"). The obtained liquid crystal cell was heated at 120°C for 1 hour, and then left overnight at 23°C to evaluate its liquid crystal alignment properties. Specifically, the orientation of the liquid crystal was observed using a polarizing microscope (ECLIPSE E600 POL, manufactured by Nikon). The evaluation was as follows: samples where liquid crystal orientation was confirmed and there was no flow orientation were classified as "good," while samples where liquid crystal orientation could not be confirmed or where flow orientation was present were classified as "poor."

[0118] "Evaluation of Bright Spots" This evaluation assesses the generation of bright spots caused by polyimide decomposition products generated by photodegradation. Specifically, the presence or absence of bright spots in the liquid crystal cell obtained in the "Evaluation of Liquid Crystal Alignment" was checked using the polarizing microscope described above, and then the liquid crystal cell was heated at 120°C for 168 hours. After that, with the pixel electrode and common electrode of the liquid crystal cell short-circuited, it was left at 23°C for 24 hours, and then the presence or absence of bright spots in the same location as before heating was checked using a polarizing microscope. At this time, cells without bright spots were classified as "good," and those with bright spots were classified as "poor." The evaluation conditions and results for "Evaluation of Liquid Crystal Alignment" and "Evaluation of Bright Spots" are shown in Table 3.

[0119] <Example 7> A polyamic acid solution (PAA-1) obtained by the method of Example 4, NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (1) (solid content: NMP: GBL: BCS = 6:44:30:20 mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (1) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0120] <Example 8> A polyamic acid solution (PAA-1) obtained by the method of Example 4, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (2) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (2) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0121] <Example 9> A polyamic acid solution (PAA-2) obtained by the method of Example 5, NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (3) (solid content: NMP: GBL: BCS = 6:44:30:20 mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (3) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0122] <Example 10> A polyamic acid solution (PAA-2) obtained by the method of Example 5, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (4) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (4) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0123] <Example 11> A polyamic acid solution (PAA-3) obtained by the method of Example 6, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (5) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (5) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots". <Example 16> A polyamic acid solution (PAA-6) obtained by the method of Example 7, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (8) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (8) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots". <Example 17> A polyamic acid solution (PAA-7) obtained by the method of Example 8, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (9) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (9) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0124] <Comparative Example 3> A polyamic acid solution (PAA-4) obtained by the method of Comparative Example 1, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (6) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (6) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0125] <Comparative Example 4> A polyamic acid solution (PAA-5) obtained by the method of Comparative Example 2, F-1 (F-1 mixing ratio: 10 parts by mass per 100 parts by mass of polyimide polymer), NMP, GBL, and BCS were added to a sample tube containing a stirring bar, and the mixture was stirred at 25°C for 30 minutes to obtain a liquid crystal alignment agent (7) (solid content: NMP:GBL:BCS = 6:44:30:20 by mass ratio). No abnormalities such as turbidity or precipitate formation were observed in this liquid crystal alignment agent, and it was confirmed to be a homogeneous solution. Furthermore, the obtained liquid crystal alignment agent (7) was used to perform "evaluation of liquid crystal alignment" and "evaluation of bright spots".

[0126] *1: Indicates the amount (in parts by mass) of the compound that promotes imidation introduced relative to 100 parts by mass of the polyimide polymer.

[0127]

[0128] As can be seen from the results above, no bright spots were observed in the liquid crystal cells using the liquid crystal alignment film obtained from the liquid crystal alignment agent of the embodiment of the present invention. In particular, the effect was obtained despite the low firing temperature of 180°C. Specifically, this is a comparison between the embodiment using the specific diamine and the comparative example without it, i.e., a comparison between Example 8 and Example 10 and Comparative Example 3 and Comparative Example 4, under the same conditions.

[0129] By using a liquid crystal alignment agent containing a polyimide polymer obtained from a specific diamine of the present invention, a liquid crystal display element obtained by photo-alignment treatment utilizing the photodecomposition reaction of polyimide can be made capable of suppressing bright spots caused by polyimide decomposition products generated by photodecomposition. In particular, since this effect can be obtained even at low firing temperatures, it is excellent from the viewpoint of ESG and SDGs. For this reason, the liquid crystal display element of the present invention is suitably used in transverse electric field driven elements such as IPS drive systems and FFS drive systems, and is useful in smartphones and tablet terminals.

[0130] 1: Transverse field liquid crystal display element, 2: Comb-tooth electrode substrate, 2a: Substrate, 2b: Linear electrode, 2c: Liquid crystal alignment film, 2d: Substrate, 2e: Surface electrode, 2f: Insulating film, 2g: Linear electrode, 2h: Liquid crystal alignment film, 3: Liquid crystal, 4: Opposing substrate, 4a: Liquid crystal alignment film, 4b: Substrate, L: Electric field lines

[0131] Furthermore, the entire contents of the specification, claims, abstract, and drawings of Japanese Patent Application No. 2024-160026, filed on September 17, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A liquid crystal aligning agent containing at least one polymer selected from a polyimide precursor and a polyimide having the structure of the following formula [1]. (X １ and X ３ each independently represents a single bond, -O-, -COO-, -OCO-, -NR ａ -, -NR ａ CO- or -CONR ａ -, R ａ represents a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, or a protecting group that is eliminated by heating and replaced by a hydrogen atom. X ２ represents an alkylene group having 1 to 6 carbon atoms. X ａ each independently represents -COOR ｂ , R ｂ represents a linear or branched alkyl group having 1 to 4 carbon atoms. m1 and m2 each independently represent 0 or 1, and either m1 or m2 represents 1. n1 and n2 each independently represent 0 or 1. * represents a bond.) 2. The liquid crystal alignment agent according to claim 1, wherein the polymer is at least one selected from a polyimide precursor and a polyimide, which use a diamine having the structure of formula [1] as part of the raw materials.

3. The liquid crystal alignment agent according to claim 2, wherein the diamine is the following formula [1a]. (X １ , X ２ , X ３ , X ａ m1, m2, n1, and n2 have the same meaning as those defined in formula [1] above. １ Each of these independently represents either a hydrogen atom or a monovalent organic group.

4. The liquid crystal alignment agent according to claim 3, wherein the diamine is at least one selected from the following formulas [1a-1] to [1a-5].

5. The liquid crystal alignment agent according to claim 2 or 3, wherein the proportion of the diamine used is 20 to 70 mol% of the total diamine component of the raw materials for the polymer.

6. The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the polymer is at least one selected from a polyimide precursor and a polyimide using the tetracarboxylic acid of the following formula [2] as part of the raw materials. (Z represents one of the structures selected from the group consisting of equations [2a] to [2l] below.) (Z Ａ ~Z Ｄ Each of these independently represents a hydrogen atom, a methyl group, a chlorine atom, or a benzene ring. Ｅ and Z Ｆ Each of these independently represents either a hydrogen atom or a methyl group.

7. The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the liquid crystal alignment agent contains a compound that promotes the imidization of the polymer.

8. The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the liquid crystal alignment agent further contains other polymers other than the polymer.

9. A liquid crystal alignment film obtained from a liquid crystal alignment agent according to any one of claims 1 to 4.

10. A liquid crystal display element comprising the liquid crystal alignment film according to claim 9.

11. A method for manufacturing a liquid crystal display element, comprising the following steps (1) to (4). Step (1): Applying a liquid crystal alignment agent according to any one of claims 1 to 4 to at least one of a first substrate and a second substrate. Step (2): Firing the applied liquid crystal alignment agent to obtain a film. Step (3): Performing an alignment treatment on the film obtained in step (2). Step (4): Arranging a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the aligned film to produce a liquid crystal cell.

12. The method for manufacturing a liquid crystal display element according to claim 11, wherein the firing temperature in step (2) is 150 to 200°C.

13. The method for manufacturing a liquid crystal display element according to claim 11, wherein the orientation treatment is a photo-alignment treatment.

14. A method for manufacturing a liquid crystal display element according to claim 13, further comprising step (3b) of performing a heat treatment between step (3) and step (4).

15. The method for manufacturing a liquid crystal display element according to claim 14, wherein the liquid crystal display element uses an IPS drive system or an FFS drive system.

16. A diamine represented by any of the following formulas [1a-1] to [1a-5].

17. A polyimide precursor or polyimide using the diamine described in claim 16 as part of the raw material.

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