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

Abstract

The present invention provides a liquid crystal display element which is excellent in terms of reliability without being decreased in the voltage holding ratio even if irradiated with heat or ultraviolet rays, and which has a small accumulated charge, thereby being excellent in terms of afterimage phenomenon.　Provided is a liquid crystal aligning agent which contains the following component (A) and component (B). Component (A): A silane compound which has a blocked isocyanate skeleton. Component (B): At least one polymer that is selected from among polyimide precursors and polyimides, which are obtained by reacting a tetracarboxylic acid component with a diamine component that includes a diamine represented by formula [1a]. (In the formula, the definition of each symbol is as defined in the description.)

Description

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

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

[0002] The MVA (Multi-Domain Vertical Alignment) mode is known as a liquid crystal display element that provides a wide viewing angle and has superior viewing angle characteristics compared to TN (Twisted Nematic) mode liquid crystal display elements. The MVA mode uses liquid crystal with negative dielectric anisotropy, a liquid crystal alignment film that vertically aligns the liquid crystal, and alignment control structures that control the alignment direction of the liquid crystal. When a voltage is applied, the liquid crystal tilts vertically along the alignment control structures. However, in the MVA mode, protrusions of the alignment control structures are formed within the pixels, resulting in a lower aperture ratio compared to TN modes and other displays, resulting in reduced light transmittance from the backlight. To address this issue and further increase the liquid crystal response speed while maintaining high light transmittance, PSA (Polymer Sustained Alignment) mode liquid crystal display elements have been proposed (see Patent Documents 1 and 2). These PSA (Polymer Sustained Alignment) mode liquid crystal display elements are obtained by using a polymer to control the alignment direction of the liquid crystal during driving. In this method, a liquid crystal composition is used, which is a mixture of liquid crystal and a polymerizable compound (also called a monomer) that polymerizes when exposed to heat or ultraviolet light. A voltage is applied between the substrates to tilt the liquid crystal molecules, and the monomer is polymerized by exposure to heat or ultraviolet light to form a polymer. This results in a liquid crystal layer that has a predetermined tilt angle (also called a pretilt angle) even without applying a voltage, and a liquid crystal display element with high light transmittance and a fast liquid crystal response speed can be obtained.

[0003] Japanese Patent Application Publication No. 2003-307720 Japanese Patent Application Publication No. 2003-149647

[0004] PSA-type liquid crystal display elements require heat and ultraviolet irradiation to control the alignment of the liquid crystals, so the liquid crystal alignment film used must be more reliable than the conventional MVA-type. Therefore, the electrical characteristics of the liquid crystal alignment film, i.e., the voltage holding ratio, must not only have good initial characteristics but also be resistant to degradation even after exposure to heat and ultraviolet rays. A significant decrease in the voltage holding ratio increases the likelihood of line burn-in, a display defect in the liquid crystal display element, making it difficult to obtain a reliable liquid crystal display element. Furthermore, to suppress the afterimage phenomenon in liquid crystal display elements, a small accumulated charge (also known as residual DC voltage) is required. Therefore, the accumulated charge must be small not only in terms of initial characteristics but also after exposure to heat and ultraviolet rays.

[0005] Therefore, an object of the present invention is to provide a liquid crystal display element that has excellent reliability, does not decrease in voltage holding ratio even when exposed to heat or ultraviolet light, has small accumulated charge, and is excellent in preventing image retention. In particular, the present invention aims to provide these effects for PSA-type liquid crystal display elements. Another object of the present invention is to provide a liquid crystal alignment film for use in the liquid crystal display element, and a liquid crystal aligning agent for producing the liquid crystal alignment film.

[0006] The present inventors have conducted extensive research to achieve the above object, and as a result have completed the present invention having the following gist.

[0007] That is, the liquid crystal aligning agent contains the following components (A) and (B): Component (A): a silane compound (also referred to as a specific compound) having a blocked isocyanate skeleton. Component (B): at least one polymer (also referred to as a specific polymer) selected from a polyimide precursor and a polyimide obtained by reacting a diamine component containing a diamine of the following formula [1a] (also referred to as a specific diamine) with a tetracarboxylic acid component. (X represents the following formula [1-1] or formula [1-2]. Each Xm independently represents an integer of 1 to 4. Xp represents an integer of 0 or 1. When there are multiple Xs, the multiple Xs may be the same or different.) (X １ is a single bond, -(CH ２ ) ａ-(a is an integer of 1 to 15), -O-, -CH ２ O-, -CONH-, -NHCO-, -CON(CH ３ ) -, -N(CH ３ ) represents CO—, —COO—, or —OCO—. X ２ is a single bond or -(CH ２ ) ｂ - (where b is an integer of 1 to 15). ３ is a single bond, -(CH ２ ) ｃ -(c is an integer of 1 to 15), -O-, -OCH ２ represents -, -COO- or -OCO-. ４ represents a divalent cyclic group selected from a benzene ring, a cyclohexane ring, and a heterocycle, or a divalent organic group having 17 to 51 carbon atoms and a steroid skeleton, and any hydrogen atom on the cyclic group may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ５ represents a divalent cyclic group selected from a benzene ring, a cyclohexane ring, and a heterocycle, and any hydrogen atom on these cyclic groups may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ５ If there are multiple X ５ may be the same or different. Xn represents an integer of 0 to 4. X ６ represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluorine-containing alkoxy group having 1 to 18 carbon atoms. * represents a bond.) (X ７ represents a single bond, —O—, —CH ２ O-, -CONH-, -NHCO-, -CON(CH ３ ) -, -N(CH ３ ) represents CO—, —COO—, or —OCO—. X ８indicates an alkyl group having 8 to 22 carbon atoms or a fluorine-containing alkyl group having 6 to 18 carbon atoms. * indicates a bond.

[0008] According to the present invention, a liquid crystal display element with excellent reliability and reduced image retention can be obtained. Therefore, the liquid crystal display element of the present invention can be used in liquid crystal displays and other devices for display purposes. The mechanism by which the present invention provides a liquid crystal display element with the above-described excellent properties is not entirely clear, but is generally presumed to be as follows: When the specific compound is heated to the thermal desorption temperature of the blocking agent, the blocking agent is desorbed, generating an isocyanate group. The generated isocyanate group reacts with an amino group or a carboxylic acid in the specific polymer to enhance the stability of the liquid crystal alignment film, thereby suppressing a decrease in voltage retention rate and an increase in accumulated charge due to exposure to heat or ultraviolet light. Furthermore, the blocked isocyanate group in the specific compound is an isocyanate group protected by a blocking agent and is inactivated by protection by the blocking agent. Therefore, no isocyanate group is generated in an unheated state, for example, at room temperature of 25°C, resulting in excellent storage stability of the liquid crystal alignment agent. The specific diamine has a cyclic structure such as a benzene ring or a cyclohexane ring, or a long-chain alkyl group. In particular, the structure of formula [1-1] in which X in the above formula [1a] is a cyclic structure that is stable against heat and light such as ultraviolet light, etc. Therefore, a liquid crystal alignment film obtained from a liquid crystal aligning agent containing a specific polymer obtained using the cyclic structure can enhance the effect of suppressing a decrease in voltage holding ratio and an increase in accumulated charge due to irradiation with heat and ultraviolet light.

[0009] <Specific Compound> The specific compound is obtained by an addition reaction between a silane having an isocyanate group and a blocking agent, and the isocyanate group of the specific compound is protected with the blocking agent. Examples of silane compounds having an isocyanate group include 3-(trimethoxysilyl)propyl isocyanate and 3-(triethoxysilyl)propyl isocyanate. Examples of blocking agents include alcohol-type blocking agents, lactam-type blocking agents, nitrogen-containing heterocyclic-type blocking agents, amine-type blocking agents, phenol-type blocking agents, oxime-type blocking agents, and imide-type blocking agents. Examples of alcohol-type blocking agents include methanol, ethanol, propanol, butanol, benzyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl lactate, and ethyl lactate. Of these, methanol, ethanol, and propanol are preferred. Examples of lactam-type blocking agents include ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam. Of these, ε-caprolactam is preferred.

[0010] Examples of nitrogen-containing heterocyclic blocking agents include imidazole, 2-ethylimidazole, pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole. Among these, imidazole, 2-ethylimidazole, and 3,5-dimethylpyrazole are preferred. Examples of amine-type blocking agents include aniline, butylamine, and dibutylamine. Examples of phenol-type blocking agents include phenol, cresol, 3,5-xylenol, 2,5-xylenol, and chlorophenol. Examples of oxime-type blocking agents include 2-butanone oxime, methyl ethyl ketoxime, formaldoxime, acetaldoxime, and acetoxime. Examples of imide-type blocking agents include succinimide and maleimide. It is preferable to use an alcohol-type blocking agent, a lactam-type blocking agent, or a nitrogen-containing heterocyclic blocking agent as the blocking agent. The thermal desorption temperature of the blocking agent is preferably 80 to 250°C. More preferably, the temperature is 100 to 200°C.

[0011] The specific compound may be one obtained by an addition reaction between a silane having an isocyanate group and a blocking agent, or a commercially available product. Specific examples of commercially available products include X-12-1195, X-12-1293, and X-12-1308ES (manufactured by Shin-Etsu Chemical Co., Ltd.), and these are preferably used as the specific compound in the present application. The specific compound may be used alone or in combination of two or more types in order to adjust the thermal desorption temperature of the blocking agent.

[0012] <Specific Polymer> The specific polymer is a polyimide precursor or polyimide (collectively referred to as a polyimide polymer) obtained by reacting a diamine component containing a specific diamine with a tetracarboxylic acid. The polyimide precursor is preferably a polyamic acid or polyamic acid ester having a structure of the following formula [A]: (R ａ represents a tetravalent organic group. ｂ represents a divalent organic group. １ and A ２ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and 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 may be the same or different. n represents a positive integer.

[0013] The polyimide has a structure of the following formula [A-4] and can be obtained by ring-closing (hereinafter also referred to as "imidization") a polyamic acid of a polyimide precursor. In this case, if the ring-closure rate of the amic acid group (hereinafter also referred to as "imidization rate") is less than 100%, the polyimide contains at least one of the structures of the following formulas [A-1] to [A-3] in addition to the structure of formula [A-4]. (R ａ , R ｂ , A １ ~A ４ has the same meaning as defined in the above formula [A].

[0014] The diamine component is a diamine having two primary or secondary amino groups in the molecule, and the tetracarboxylic acid component includes a tetracarboxylic acid compound, a tetracarboxylic acid dianhydride, a tetracarboxylic acid dihalide compound, a tetracarboxylic acid dialkyl ester compound, and a tetracarboxylic acid dialkyl ester dihalide compound.

[0015] The polyimide polymer can be obtained relatively easily by using a tetracarboxylic dianhydride of the following formula [B] or a derivative thereof and a diamine of the following formula [C] as raw materials. From this viewpoint, a polyamic acid having a repeating unit structure of the following formula [D] or a polyimide obtained by imidizing the polyamic acid is preferred. (R ａ and R ｂ has the same meaning as defined in the above formula [A]. (R ａ and R ｂ is the same as defined in the above formula [A]. n represents a positive integer.) In addition, by a conventional synthesis method, a polymer having a repeating unit structure of the above formula [D] can be prepared by adding A of the formula [A]. １ and A ２ and A in formula [A] ３ and A ４ It is also possible to introduce an alkyl group having 1 to 5 carbon atoms or an acetyl group.

[0016] The specific diamine is a diamine of the above formula [1a]. In formula [1a], Xm, Xp, and X are as defined above, but among them, the following are preferred. Each Xm is preferably independently an integer of 1 or 2. Xp is preferably an integer of 1.

[0017] X is a structure of the above formula [1-1] or formula [1-2], and when there are a plurality of X, the plurality of X may be the same or different. １ ~X ６ and Xn are as defined above, but among them, the following are preferred: X １ From the viewpoint of availability of raw materials and ease of synthesis, ２ ) ａ-(a is an integer of 1 to 15), -O-, -CH ２ Preferred are —O— and —COO—. More preferred are single bonds, —(CH ２ ) ａ -(a is an integer of 1 to 10), -O-, -CH ２ X is -O- or -COO-. ２ is a single bond or -(CH ２ ) ｂ - (b is an integer of 1 to 10) is preferred. ３ From the viewpoint of ease of synthesis, a single bond, -(CH ２ ) ｃ -(c is an integer of 1 to 15), -O-, -CH ２ Preferred are —O—, —COO—, and —OCO—. More preferred are single bonds, —(CH ２ ) ｃ -(c is an integer of 1 to 10), -O-, -CH ２ X is -O- or -COO-. ４ From the viewpoint of ease of synthesis, X is preferably a divalent organic group having a benzene ring, a cyclohexane ring, or a steroid skeleton and having 17 to 51 carbon atoms. ５ is preferably a divalent cyclic group selected from a benzene ring and a cyclohexane ring. ６ is preferably an alkyl group having 1 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluorine-containing alkoxy group having 1 to 10 carbon atoms. More preferred are alkyl groups having 1 to 12 carbon atoms or alkoxy groups having 1 to 12 carbon atoms. Particularly preferred are alkyl groups having 1 to 9 carbon atoms or alkoxy groups having 1 to 9 carbon atoms. From the viewpoints of availability of raw materials and ease of synthesis, Xn is preferably an integer from 0 to 3. More preferred is an integer from 0 to 2.

[0018] In formula [1-2], X ７ and X ８ are as defined above, but among them, the following are preferred: ７ is a single bond, -O-, -CH ２ O-, -CONH-, -CON(CH ３)- or -COO- is preferred. A single bond, -O-, -CONH- or -COO- is more preferred. X ８ is preferably an alkyl group having 8 to 18 carbon atoms.

[0019] Specific examples of the specific diamine in which X is formula [1-1] include diamine compounds of formulas [2-1] to [2-6] and formulas [2-9] to [2-31] described on pages 15 to 19 of International Publication WO2013 / 125595 (published on August 29, 2013). ２ and R in formula [2-4] to formula [2-6] ４ represents an alkyl group having 1 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluorine-containing alkoxy group having 1 to 18 carbon atoms. ４ represents a linear or branched alkyl group having 3 to 18 carbon atoms. ３ is -O-, -CH ２ It represents —O—, —COO— or —OCO—.

[0020] Among these, preferred specific diamines are the diamine compounds of formulas [2-1] to [2-6], [2-9] to [2-13], or [2-22] to [2-31] described in International Publication WO2013 / 125595. More preferred are the diamines of formulas [1a-32] to [1a-41] below. (R １ Each represents an alkyl group having 3 to 12 carbon atoms. (R ２ Each represents an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomer of 1,4-cyclohexylene is the trans isomer.)

[0021] The most preferred are diamines of the above formula [1a-35] to formula [1a-37], formula [1a-40] or formula [1a-41]. Specific examples of the specific diamine in which X is formula [1-2] include diamine compounds of formula [DA1] to formula [DA5] described on page 23 of International Publication WO2013 / 125595 (published on August 29, 2013). In the description of International Publication WO2013 / 125595, A in formula [DA1] to formula [DA5] is １ represents an alkyl group having 8 to 22 carbon atoms or a fluorine-containing alkyl group having 6 to 18 carbon atoms. Among these, diamines represented by the following formulas [1b-1] to [1b-5] are preferred.

[0022] From the viewpoint of optimally achieving the effects of the present invention, the proportion of the specific diamine used is preferably 25 to 100 mol % relative to the total diamine component. It is more preferably 25 to 80 mol %, and particularly preferably 25 to 60 mol %. Furthermore, the specific diamine can be used alone or in combination of two or more types depending on the properties.

[0023] In the polyimide polymer, diamines other than the specific diamines can be used as the diamine component. Specific examples include the other diamine compounds described in paragraphs

[0044] to

[0051] of WO 2013 / 125595 and the diamines of the following formulas [DA-1] to [DA-103]. Furthermore, the other diamines can be used alone or in combination of two or more depending on the properties.

[0024]

[0025] As the tetracarboxylic acid component for producing the polyimide polymer, it is preferable to use a tetracarboxylic acid dianhydride represented by the following formula [2], or a tetracarboxylic acid derivative thereof, such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide (collectively referred to as a specific tetracarboxylic acid component). (Z represents any one of the structures of the following formulas [2a] to [2l].)

[0026] (Z Ａ ~Z Ｄ each independently represents a hydrogen atom, a methyl group, a chlorine atom or a benzene ring. Ｅ and Z Ｆ each independently represents a hydrogen atom or a methyl group.) Among these, from the viewpoint of ease of synthesis and ease of polymerization reactivity when producing a polymer, Z is preferably formula [2a], formula [2c], formula [2d], formula [2e], formula [2f], formula [2g], formula [2k] or formula [2l]. More preferred 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].

[0027] The proportion of the specific tetracarboxylic acid component used is preferably 1 mol % or more, based on the total tetracarboxylic acid components. More preferably, it is 5 mol % or more. Particularly preferably, it is 10 mol % or more. The polyimide-based polymer can use tetracarboxylic acid components other than the specific tetracarboxylic acid component. Examples of the other tetracarboxylic acid component include the tetracarboxylic acid compounds, tetracarboxylic acid dianhydrides, dicarboxylic acid dihalide compounds, dicarboxylic acid dialkyl ester compounds, and dialkyl ester dihalide compounds shown below. Specific examples include the other tetracarboxylic acid components described in paragraph

[0057] of WO 2015 / 012368, and the tetracarboxylic acid dianhydrides and derivatives thereof represented by the following formulas [CA-1] to [CA-26]. Furthermore, the specific tetracarboxylic acid component and the other tetracarboxylic acid components can be used alone or in combination of two or more depending on the respective properties.

[0028]

[0029] The method for synthesizing the polyimide polymer is not particularly limited. Typically, the polyimide polymer is obtained by reacting a diamine component with a tetracarboxylic acid component. Specific examples include the method described in paragraph

[0059] of WO 2015 / 012368.

[0030] Polyamic acid esters can be synthesized by known methods, such as reacting a 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 with a dihalide. The solvent used in the reaction between the diamine component and the tetracarboxylic acid component is not particularly limited as long as it dissolves the resulting polyimide precursor. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-imidazolidinone. Furthermore, if the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D1] to [D3] can be used. (D １ and D ２ represents an alkyl group having 1 to 3 carbon atoms. ３ represents an alkyl group having 1 to 4 carbon atoms.)

[0031] These may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above-mentioned solvent to the extent that it does not precipitate. Furthermore, since moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried.

[0032] In the polymerization reaction of the polyimide precursor, the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2 when the total number of moles of the diamine components is taken as 1.0. When the total number of moles of the tetracarboxylic acid components is less than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is smaller than the number of moles of the diamine components, the polymer will have an amino group structure at its terminal. When the total number of moles of the tetracarboxylic acid components is greater than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is greater than the number of moles of the diamine components, the polymer will have a carboxylic anhydride or dicarboxylic acid structure at its terminal. Polyimides are obtained by ring-closing a polyimide precursor, and the imidization rate does not necessarily need to be 100% and can be adjusted as desired depending on the application and purpose. From the viewpoint of solubility in solvents, a ratio of 30 to 90% is preferred. A ratio of 40 to 90% is even more preferred.

[0033] The polyimide polymer may be converted into a terminal-capping polymer using a terminal-capping agent. The terminal-capping polymer has 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 a liquid crystal display element. The method for obtaining the terminal-capping polymer is not particularly limited. Specific examples include the methods described in paragraphs

[0046] and

[0047] of WO 2023 / 074568.

[0034] From the viewpoints 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, more preferably 10,000 to 150,000, in terms of polyethylene glycol oxide (Mw) measured by Gel Permeation Chromatography (GPC).

[0035] <Liquid Crystal Alignment Agent> The liquid crystal alignment agent is a solution for forming a liquid crystal alignment film, and is a solution containing a specific compound, a specific polymer, and a solvent. In this case, two or more types of specific compound and two or more types of specific polymer can be used. The proportion of the specific compound used is preferably 0.1 to 30 parts by mass relative to 100 parts by mass of the specific polymer. More preferably, it is 0.5 to 25 parts by mass. Particularly preferably, it is 1 to 15 parts by mass. The polymer component does not have to be entirely the specific polymer, and may contain a polyimide-based polymer that does not use a specific diamine as a diamine component, or a polymer other than a polyimide-based polymer. In this case, the proportion of the polymer used is preferably 10 to 200 parts by mass relative to 100 parts by mass of the specific polymer. More preferably, it is 10 to 100 parts by mass.

[0036] The content of the solvent in the liquid crystal aligning agent can be appropriately selected from the viewpoint of the application method of the liquid crystal aligning agent and obtaining a desired film thickness. In particular, from the viewpoint of forming a uniform liquid crystal alignment film by application, the content of the solvent in the liquid crystal aligning agent is preferably 50 to 99.9% by mass, more preferably 60 to 99% by mass, and particularly preferably 65 to 99% by mass.

[0037] The solvent used for the liquid crystal aligning agent is not particularly limited as long as it is a solvent that can dissolve the specific polymer. Among them, the following solvents (hereinafter also referred to as "Solvent A") are preferably used. 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-dimethylpropanamide, 3-methyl ... Examples of good solvents 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, these are also 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, and γ-butyrolactone are preferred. These may be used alone or in combination of two or more.

[0038] When the specific polymer has high solubility in the solvent, the following solvent (hereinafter also referred to as "Solvent B") can be used.For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (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) (oxy)-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).Among these, diisobutyl carbinol, 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 are preferably used. These may be used alone or in combination of two or more.

[0039] In the present invention, from the viewpoint of the coating properties of the liquid crystal alignment film, it is preferable to use a solvent that is a combination of Solvent A and Solvent B. Specific examples include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 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-diphenyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolact ...methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-buty 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, ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N -Ethyl-2-pyrrolidone, 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-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone,N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether Methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2-pi rolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol pyrene glycol monomethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol diethyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone, and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide, and diisobutyl ketone,Examples of the combination include N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate, γ-butyrolactone, ethylene glycol monobutyl ether acetate, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate, and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate, and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate, and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone, and propylene glycol monomethyl ether, cyclopentanone, and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone, and propylene glycol monomethyl ether, and combinations of these are preferred.

[0040] When the solvent A type and the solvent B type are used in combination, the solvent B type is preferably 1 to 99 mass % of the total solvent contained in the liquid crystal aligning agent, more preferably 10 to 99 mass %, and most preferably 20 to 95 mass %.

[0041] In order to increase the film strength of the liquid crystal alignment film, the liquid crystal aligning agent preferably contains a compound having at least one structure selected from an epoxy group, an isocyanate group, an oxetanyl group, an oxazoline group, a cyclocarbonate group, a blocked isocyanate group, a hydroxy group, a hydroxyalkyl group, a lower alkoxyalkyl group, and a polymerizable unsaturated group (hereinafter also collectively referred to as a "crosslinkable compound"). In this case, the compound must contain two or more of these groups.

[0042] Specific examples of the crosslinkable compound having an epoxy group or an isocyanate group 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, dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, bisphenol A type epoxy resins such as Epicoat 828 (manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins such as Epicoat 807 (manufactured by Mitsubishi Chemical Corporation), YX-8000 (manufactured by Mitsubishi Chemical Corporation), ), biphenyl skeleton-containing epoxy resins such as YX6954BH30 (manufactured by Mitsubishi Chemical Corporation), phenol novolac epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o, m, p-) cresol novolac epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), compounds in which a tertiary nitrogen atom is bonded to an aromatic carbon atom such as 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 ,3-bis(N,N-diglycidylaminomethyl)benzene, 1,4-bis(N,N-diglycidylaminomethyl)benzene, 1,3,5-tris(N,N-diglycidylaminomethyl)cyclohexane, 1,3,5-tris(N,N-diglycidylaminomethyl)benzene and other compounds in which a tertiary nitrogen atom is bonded to an aliphatic carbon atom; isocyanurate compounds such as triglycidyl isocyanurate such as TEPIC (manufactured by Nissan Chemical Industries, Ltd.); and those described in paragraph

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

[0051] to

[0054] of WO2017 / 170483.

[0043] Specific examples of the crosslinkable compound 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.

[0044] Specific examples of the crosslinkable compound 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 EPOCROS (manufactured by Nippon Shokubai Co., Ltd.), and those described in paragraph

[0115] of Japanese Patent Publication No. 2007-286597.

[0045] 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

[0032] of WO2011 / 155577.

[0046] Specific examples of crosslinkable compounds having a blocked isocyanate group include Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, and Millionate MS-50 (manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, and B-882N (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.

[0047] Specific examples of crosslinkable compounds having a hydroxy group, a hydroxyalkyl group, and a lower alkoxyalkyl group include N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide, 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.

[0048] Specific examples of the crosslinkable compound having a polymerizable unsaturated group include glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-, 1,3-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.

[0049] The proportion of the crosslinkable compound used in the liquid crystal aligning agent is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of all polymer components. From the viewpoint of promoting the crosslinking reaction and achieving the desired effect, the proportion is more preferably 0.1 to 50 parts by mass, and particularly preferably 1 to 30 parts by mass.

[0050] The liquid crystal aligning agent may be a compound that improves the uniformity of the 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 improve the uniformity of the thickness and surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples include the surfactants described in paragraph

[0122] of WO 2014 / 171493. The amount of the surfactant used is preferably 0.01 to 2 parts by mass relative to 100 parts by mass of all polymer components. A range of 0.01 to 1 part by mass is more preferred.

[0051] Specific examples of compounds that improve the adhesion between a liquid crystal alignment film and a substrate include the compounds described in paragraph

[0123] of WO2014 / 171493. The proportion of the compound used is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of all polymer components. In addition to the compounds other than those mentioned above, the liquid crystal alignment agent may contain a dielectric or conductive substance added thereto for the purpose of changing the electrical properties, such as the dielectric constant and conductivity, of the liquid crystal alignment film.

[0052] <Liquid Crystal Alignment Film / Liquid Crystal Display Element> The liquid crystal alignment agent can be applied to a substrate, baked, and then subjected to an alignment treatment as needed to form an alignment film. The substrate used to form the liquid crystal alignment film is not particularly limited as long as it is a highly transparent substrate, and in addition to a glass substrate, plastic substrates such as an acrylic substrate, a polycarbonate substrate, and a PET (polyethylene terephthalate) substrate, as well as films thereof, can be used. Furthermore, from the viewpoint of simplifying the process, it is preferable to use a substrate on which an ITO electrode, an IZO (Indium Zinc Oxide) electrode, an IGZO (Indium Gallium Zinc Oxide) electrode, an organic conductive film, or the like for driving the liquid crystal is formed. Furthermore, when a reflective liquid crystal display element is formed, a substrate on which a silicon wafer, a metal such as aluminum, or a dielectric multilayer film is formed can be used as the substrate on only one side.

[0053] The method for applying the liquid crystal alignment agent is not particularly limited, but industrially, a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, a screen printing method, an offset printing method, a flexographic printing method, an inkjet method, etc. are used depending on the purpose.

[0054] After applying the liquid crystal alignment agent to the substrate, the solvent can be evaporated at a temperature of 30 to 300°C, preferably 30 to 250°C, using a heating means such as a hot plate, a hot air circulation oven, or an IR (infrared) oven, depending on the type of substrate and the solvent used in the liquid crystal alignment agent, to form a liquid crystal alignment film. When a plastic substrate is used, treatment is preferably performed at a temperature of 30 to 150°C. The thickness of the liquid crystal alignment film is preferably 5 to 500 nm, since a too-thick film is disadvantageous in terms of power consumption of the liquid crystal display element, while a too-thin film may reduce the reliability of the element. A thickness of 10 to 300 nm is more preferable, and a thickness of 10 to 250 nm is particularly preferable. The liquid crystal alignment film may be subjected to alignment treatments such as rubbing in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or photoalignment in which the surface of the liquid crystal alignment film is irradiated with polarized radiation in a certain direction. The liquid crystal alignment film of the present invention can achieve the desired characteristics without alignment treatment.

[0055] The liquid crystal of the liquid crystal composition used in the liquid crystal display element can be a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal. From the viewpoint of low-voltage operation, a liquid crystal having a large dielectric constant anisotropy and a large refractive index anisotropy is preferable. Furthermore, two or more types of liquid crystals can be mixed and used depending on the physical properties of the phase transition temperature, dielectric constant anisotropy, and refractive index anisotropy. In the present invention, it is preferable to use a nematic liquid crystal having a negative dielectric constant anisotropy. Specific examples include dicyanobenzene-based liquid crystals, pyridazine-based liquid crystals, Schiff-base-based liquid crystals, azoxy-based liquid crystals, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, and terphenyl-based liquid crystals. In the case of a PSA-type liquid crystal display element, it is preferable to use an alkenyl-based liquid crystal having either an alkenyl group or a fluoroalkenyl group in combination.

[0056] In the case of a PSA-type liquid crystal display element, a liquid crystal composition containing liquid crystal and a polymerizable compound is used. The polymerizable compound is one having a radically polymerizable moiety such as an acryloyl group, a methacryloyl group, or a vinyl group. In particular, from the viewpoint of the reactivity of the polymerizable compound, it is preferable that the polymerizable compound has two or more acryloyl groups or methacryloyl groups. Furthermore, from the viewpoint of stabilizing the alignment of the liquid crystal, it is preferable that the polymerizable compound has two or more cyclohexane rings or benzene rings. Specific examples include polymerizable compounds of the following formulas [L-1] to [L-3].

[0057] The proportion of the polymerizable compound used is preferably 0.01 to 5 parts by mass per 100 parts by mass of the liquid crystal. A more preferred range is 0.1 to 1 part by mass. A particularly preferred range is 0.1 to 0.5 parts by mass. The method for injecting the liquid crystal composition is not particularly limited, but examples include the following method. That is, when glass substrates are used as the substrates, a pair of substrates on which a liquid crystal alignment film has been formed is prepared, and a sealant is applied to four edges of one substrate, excluding a portion, and then the other substrate is attached with the liquid crystal alignment film facing inward to produce an empty cell. The liquid crystal composition is then injected under reduced pressure from the area where the sealant has not been applied to obtain a liquid crystal composition-injected cell. Furthermore, when plastic substrates or films are used as the substrates, a pair of substrates on which a liquid crystal alignment film has been formed is prepared, and the liquid crystal composition is dropped onto one substrate by an ODF (One Drop Filling) method, an inkjet method, or the like, and then the other substrate is attached to obtain a liquid crystal composition-injected cell. The resulting liquid crystal composition-injected cell can be heated to a temperature at which the liquid crystal becomes isotropic, thereby removing the flow alignment that occurs upon injection of the liquid crystal composition. As the sealing agent, an epoxy resin containing a curing agent and spacers such as aluminum oxide spheres can be used.

[0058] In a PSA liquid crystal display element, the liquid crystal composition-injected cell obtained above is irradiated with heat or ultraviolet light while applying an AC or DC voltage, thereby polymerizing the polymerizable compound and controlling the alignment of the liquid crystal. The applied voltage is preferably an AC or DC voltage of 5 to 50 V, more preferably 5 to 30 V, and particularly preferably 5 to 20 V.

[0059] The treatment for the polymerization reaction of the polymerizable compound is preferably ultraviolet irradiation. Specific examples include irradiation with ultraviolet rays containing wavelengths of 150 to 800 nm and visible light. Irradiation with ultraviolet rays containing wavelengths of 300 to 400 nm is more preferred. Examples of light sources for ultraviolet irradiation include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. To irradiate ultraviolet rays at a preferred wavelength, a filter diffraction grating or the like can also be used in combination with the light source. The ultraviolet irradiation dose is 0.1 to 60 J / cm. ２ More preferably, it is 0.1 to 40 J / cm ２ Particularly preferred is 1 to 40 J / cm ２ After the above treatment, ultraviolet light or visible light can be irradiated to the liquid crystal composition-injected cell without applying a voltage, in order to eliminate any unreacted polymerizable compound in the liquid crystal layer. The gap of the liquid crystal layer of the liquid crystal display element of the present invention is preferably 1 to 20 μm, more preferably 1 to 10 μm, and particularly preferably 1 to 6 μm. If the gap is too small, the contrast of the liquid crystal display element will decrease, and if it is too large, the driving voltage of the element will increase.

[0060] The present invention will be described in more detail below with reference to examples, but is not limited to these. The abbreviations used in the examples and comparative examples and the methods for measuring the various physical properties are as follows.

[0061] <Specific diamine> A1: Diamine of the following formula [A1] <Other diamines> B1: Diamine of the following formula [B1]

[0062] <Tetracarboxylic acid dianhydrides> C1 to C2: Tetracarboxylic acid dianhydrides of the following formulae [C1] to [C2] <Specific Compounds> XS1 (alcohol-type blocking agent): X-12-1195 (manufactured by Shin-Etsu Chemical Co., Ltd.) (blocked isocyanate silane coupling agent) XS2 (lactam-type blocking agent): X-12-1293 (manufactured by Shin-Etsu Chemical Co., Ltd.) (blocked isocyanate silane coupling agent) XS3 (nitrogen-containing heterocyclic-type blocking agent): X-12-1308ES (manufactured by Shin-Etsu Chemical Co., Ltd.) (blocked isocyanate silane coupling agent)

[0063] <Silane coupling agent> S1: 3-glycidoxypropyltriethoxysilane S2: 3-aminopropyltriethoxysilane S3: 3-(tert-butoxycarbonylamino)propyltriethoxysilane <Solvent> NMP: N-methyl-2-pyrrolidone BCS: ethylene glycol monobutyl ether

[0064] "Molecular Weight Measurement" The number average molecular weight (hereinafter also referred to as "Mn") and weight average molecular weight (hereinafter also referred to as "Mw") of the polyimide polymer were measured using the following apparatus and conditions. Room temperature gel permeation chromatography (GPC) apparatus: GPC-101 (manufactured by Resonac Corporation) Column: GPC KD-803 and KD-805 (manufactured by Resonac Corporation) in series Column temperature: 50°C Eluent: N,N-dimethylformamide (containing lithium bromide monohydrate (LiBr.H) as an additive) ２ o-Phosphoric acid (o-Phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) 10 ml / L) Flow rate: 1.0 mL / min Standard sample for creating a calibration curve: EasiVial PEG / PEO polyethylene glycol oxide PL2080-0201 (molecular weight: about 1,500, about 4,000, about 13,000, about 30,000, about 70,000, about 130,000, about 500,000, about 1,000,000, about 1,500,000) (GL Sciences) "Synthesis of polyimide polymer"

[0065] Synthesis Example 1: C2 (5.00 g, 20.0 mmol), A1 (5.22 g, 12.0 mmol), B1 (5.55 g, 28.0 mmol), and NMP (63.1 g) were added to a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 60°C for 3 hours while introducing nitrogen. The mixture was then cooled to 25°C, and C1 (3.76 g, 19.2 mmol) and NMP (15.1 g) were added. The mixture was stirred at 40°C for 18 hours to obtain a polyamic acid solution (A) with a resin solids concentration of 20 wt%. The Mn of this polyamic acid was 8,900 and the Mw was 25,000.

[0066] "Production of Liquid Crystal Alignment Agent" In the following Examples 1 to 3 and Comparative Examples 1 to 4, examples of production of liquid crystal alignment agents will be described. These liquid crystal alignment agents will be used for evaluation of liquid crystal display elements. The specifications of the liquid crystal alignment agents are shown in Table 1.

[0067]

[0068] "Preparation of Liquid Crystal Cell (Liquid Crystal Display Element)" The liquid crystal alignment agent obtained by the methods of the Examples and Comparative Examples was pressure-filtered through a membrane filter with a pore size of 1 μm and spin-coated onto the ITO surface of a substrate (40 mm long x 30 mm wide, 0.7 mm thick) with an ITO electrode that had been washed with pure water and IPA (isopropyl alcohol). The resulting solution was then heated on a hot plate at 70°C for 90 seconds and then at 230°C for 20 minutes in an infrared heating furnace-type clean oven to obtain an ITO substrate with a 100 nm-thick liquid crystal alignment film. Two ITO substrates with liquid crystal alignment films were prepared using the method described above. 4 μm spacers were applied to the liquid crystal alignment film surface of one substrate, and a sealant (XN-1500T) (manufactured by Kyoritsu Chemical Industry Co., Ltd.) was applied to the liquid crystal alignment film surface on all four sides of the other substrate. The liquid crystal alignment film surfaces of these substrates were then bonded together so that they faced each other. The bonded substrates were then pressure-bonded and heated at 150°C for 90 minutes to produce an empty cell. Liquid crystal (NA-1494RM1) (liquid crystal containing a polymerizable compound for PSA) (manufactured by DIC Corporation) was injected into this empty cell by a reduced pressure injection method. Thereafter, the injection port was sealed, and a heat treatment was carried out at 120°C for 30 minutes to obtain a liquid crystal cell before UV irradiation. Thereafter, the voltage holding ratio was measured by the following method. While applying an AC voltage of 15 V to the liquid crystal cell before UV irradiation for which the voltage holding ratio was measured, a metal halide lamp with an illuminance of 60 mW was used to cut off wavelengths of 325 nm or less, and a 365 nm equivalent of 10 J / cm ２ The liquid crystal cells were irradiated with ultraviolet light for 30 minutes without applying a voltage, using a UV-FL device (UV lamp: FLR40SUV32 / A-1) (manufactured by Toshiba Lighting & Technology Corporation) to deactivate any unreacted polymerizable compound remaining in the liquid crystal. This resulted in liquid crystal cells irradiated with ultraviolet light. The liquid crystal cells in the Examples and Comparative Examples had a faster response speed after ultraviolet light irradiation than before ultraviolet light irradiation, confirming that the alignment direction of the liquid crystals was controlled. Furthermore, in all liquid crystal cells, observation with a polarizing microscope (ECLIPSE E600WPOL) (manufactured by Nikon Corporation) confirmed that the liquid crystals were uniformly aligned.

[0069] "Evaluation of voltage holding ratio" The voltage holding ratio of the liquid crystal cell was measured before and after the ultraviolet irradiation, and the smaller the change in value after ultraviolet irradiation compared to the value before ultraviolet irradiation, the better the evaluation. Specifically, using a voltage holding ratio measuring device (VHR-1) (manufactured by Toyo Corporation), a voltage of 1 V was applied for 60 μs at a temperature of 60° C., the voltage after 1,667 ms was measured, and the extent to which the voltage was held was calculated as the voltage holding ratio. The results of the voltage holding ratio evaluation are shown in Table 2.

[0070] "Evaluation of Residual DC Voltage" The residual DC voltage of the liquid crystal cell after UV irradiation was measured, and the smaller this value, the better the evaluation. Specifically, at 25°C, a DC voltage was applied from 0 V to 2.0 V in 0.1 V increments. The flicker amplitude level at each voltage was measured using a photoelectric flicker amplitude level converter, and a calibration curve between the applied voltage and the flicker amplitude level was created. The liquid crystal cell was then discharged for 5 minutes, and an AC voltage of V50 (the voltage at which the brightness is halved) and a DC voltage of 2.0 V were applied for 48 hours. The flicker amplitude level was then measured immediately after the DC voltage alone was set to 0 V, and the previously prepared calibration curve was confirmed to estimate the residual DC voltage. This method of estimating the residual DC voltage is also known as the flicker reference method. The results of the residual DC voltage evaluation are shown in Table 2.

[0071] Example 1: XS1 (0.20 g), NMP (15.0 g), and BCS (25.0 g) were added to 10.0 g of a polyamic acid solution (A) with a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (1). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, confirming that it was a homogeneous solution. Using the obtained liquid crystal aligning agent (1), evaluations of voltage holding ratio and residual DC voltage were performed. Example 2: XS2 (0.20 g), NMP (15.0 g), and BCS (25.0 g) were added to 10.0 g of a polyamic acid solution (A) with a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (2). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, confirming that it was a homogeneous solution. The obtained liquid crystal alignment agent (2) was used to carry out the "evaluation of voltage holding ratio" and "evaluation of residual DC voltage."

[0072] Example 3 XS3 (0.20 g), NMP (15.0 g) and BCS (25.0 g) were added to a polyamic acid solution (A) (10.0 g) having a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (3). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the solution was homogeneous. Using the obtained liquid crystal aligning agent (3), "evaluation of voltage holding ratio" and "evaluation of residual DC voltage" were performed.

[0073] Comparative Example 1: NMP (15.0 g) and BCS (25.0 g) were added to 10.0 g of a polyamic acid solution (A) having a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (4). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, and was confirmed to be a homogeneous solution. Using the obtained liquid crystal aligning agent (4), "evaluation of voltage holding ratio" and "evaluation of residual DC voltage" were performed. Comparative Example 2: S1 (0.20 g), NMP (15.0 g), and BCS (25.0 g) were added to 10.0 g of a polyamic acid solution (A) having a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (5). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, and was confirmed to be a homogeneous solution. The obtained liquid crystal alignment agent (5) was used to carry out the "evaluation of voltage holding ratio" and "evaluation of residual DC voltage."

[0074] Comparative Example 3: To 10.0 g of a polyamic acid solution (A) having a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, S2 (0.20 g), NMP (15.0 g), and BCS (25.0 g) were added, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (6). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, and was confirmed to be a homogeneous solution. Using the obtained liquid crystal aligning agent (6), "evaluation of voltage holding ratio" and "evaluation of residual DC voltage" were performed. Comparative Example 4: To 10.0 g of a polyamic acid solution (A) having a resin solids concentration of 20% by weight obtained by the synthesis method of Synthesis Example 1, S3 (0.20 g), NMP (15.0 g), and BCS (25.0 g) were added, and the mixture was stirred at 25°C for 5 hours to obtain a liquid crystal aligning agent (7). This liquid crystal aligning agent showed no abnormalities such as turbidity or precipitation, and was confirmed to be a homogeneous solution. The obtained liquid crystal alignment agent (7) was used to carry out the "evaluation of voltage holding ratio" and "evaluation of residual DC voltage."

[0075] As can be seen from the above results, the liquid crystal cells of the Examples showed a suppressed decrease in voltage holding ratio due to UV irradiation and a lower residual DC voltage than the liquid crystal cells of the Comparative Examples. Specifically, the comparison is between Examples using the specific compound and Comparative Examples not using the specific compound or Comparative Examples using a silane coupling agent other than the specific compound, i.e., Examples 1 to 3 and Comparative Examples 1 to 4.

[0076] By using a liquid crystal aligning agent containing the specific compound of the present invention and a polyimide polymer having a specific structure, a liquid crystal display element can be obtained in which the voltage holding ratio does not decrease and the accumulated charge does not increase even when exposed to heat or ultraviolet light. This is particularly useful for PSA-type liquid crystal display elements. Therefore, the liquid crystal display element of the present invention has excellent reliability and reduced image retention, and is useful for liquid crystal displays and other display purposes.

[0077] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-087946 filed on May 30, 2024 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A liquid crystal aligning agent comprising the following components (A) and (B): Component (A): a silane compound having a blocked isocyanate skeleton, Component (B): at least one polymer selected from a polyimide precursor and a polyimide obtained by reacting a diamine component containing a diamine of the following formula [1a] with a tetracarboxylic acid component: (X represents the following formula [1-1] or formula [1-2]. Each Xm independently represents an integer of 1 to 4. Xp represents an integer of 0 or 1. When there are multiple Xs, the multiple Xs may be the same or different.) (X １ is a single bond, -(CH ２ ) ａ -(a is an integer of 1 to 15), -O-, -CH ２ O-, -CONH-, -NHCO-, -CON(CH ３ ) -, -N(CH ３ ) represents CO—, —COO—, or —OCO—. X ２ is a single bond or -(CH ２ ) ｂ - (where b is an integer of 1 to 15). ３ is a single bond, -(CH ２ ) ｃ -(c is an integer of 1 to 15), -O-, -OCH ２ represents -, -COO- or -OCO-. ４ represents a divalent cyclic group selected from a benzene ring, a cyclohexane ring, and a heterocycle, or a divalent organic group having 17 to 51 carbon atoms and a steroid skeleton, and any hydrogen atom on the cyclic group may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ５ represents a divalent cyclic group selected from a benzene ring, a cyclohexane ring, and a heterocycle, and any hydrogen atom on these cyclic groups may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ５ If there are multiple X ５ may be the same or different. Xn represents an integer of 0 to 4. X ６ represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluorine-containing alkoxy group having 1 to 18 carbon atoms. * represents a bond.) (X ７ represents a single bond, —O—, —CH ２ O-, -CONH-, -NHCO-, -CON(CH ３ ) -, -N(CH ３ ) represents CO—, —COO—, or —OCO—. X ８ indicates an alkyl group having 8 to 22 carbon atoms or a fluorine-containing alkyl group having 6 to 18 carbon atoms. * indicates a bond.

2. The liquid crystal aligning agent according to claim 1, wherein the component (A) is a silane compound having a blocked isocyanate skeleton protected with at least one selected from the group consisting of an alcohol-type blocking agent, a nitrogen-containing heterocyclic-type blocking agent, and a lactam-type blocking agent.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein X in the formula [1a], which is the diamine of the component (B), is the formula [1-1].

4. The liquid crystal aligning agent according to claim 1 or 2, wherein the tetracarboxylic acid component of the component (B) contains a tetracarboxylic acid dianhydride of the following formula [2] or a derivative thereof: (Z represents any one of the structures of the following formulas [2a] to [2l].) (Z Ａ ~Z Ｄ each independently represents a hydrogen atom, a methyl group, a chlorine atom or a benzene ring. Ｅ and Z Ｆ each independently represents a hydrogen atom or a methyl group.

5. The liquid crystal aligning agent according to claim 1 or 2, wherein the proportion of component (A) used is 0.1 to 30 parts by mass per 100 parts by mass of component (B).

6. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to claim 1 or 2.

7. A liquid crystal display device having the liquid crystal alignment film according to claim 6.

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