TWI858137B - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal display element, polymer and diamine - Google Patents

Abstract

A liquid crystal alignment agent is provided which can obtain a liquid crystal alignment film having a high ability to align liquid crystals even when overheated. A liquid crystal alignment agent comprises at least one polymer (P) selected from the group consisting of polyimide precursors and polyimides having a group represented by the following formula (1); (In the formula, _X1 represents an alkylene group having 1 to 14 carbon atoms, and one or two non-adjacent methylene groups in the alkylene group may be substituted by -O- or -COO-; _X2 represents a single bond, -OCO-, -COO-, or ^CONR2- ( ^R2 represents a hydrogen atom or a methyl group); Q represents a naphthylene group, and Y represents a group containing at least one cyclohexylene group; any hydrogen atom of the naphthylene group or cyclohexylene group may be substituted by at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom; R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a fluorinated alkyl group having 1 to 12 carbon atoms, a fluorinated alkoxy group having 1 to 12 carbon atoms, -CN, -F, -OH, _-CO2 H, -OCOR ³ , or -CO ₂ R ³ , R ³ represents a methyl group or an ethyl group; * represents a bonding site).

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained from the liquid crystal alignment agent, a liquid crystal display element having the liquid crystal alignment film, and novel diamines and polymers suitable for the same.

In the past, various driving methods with different electrode structures or physical properties of liquid crystal molecules used have been developed as liquid crystal display elements, such as TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type, IPS type (In-Plane Switching), FFS (Fringe Field Switching) type, etc. These liquid crystal display elements have a liquid crystal alignment film for aligning liquid crystal molecules. The materials of the liquid crystal alignment film include, for example, polyamic acid or polyamic acid ester, polyimide, polyamide, etc.

In the manufacturing process of VA type liquid crystal display elements, there is a step of applying voltage to liquid crystal molecules and irradiating ultraviolet rays at the same time. In such VA type liquid crystal display elements, it is known that a photopolymerizable compound is added to the liquid crystal composition in advance, and a liquid crystal alignment film such as a polyimide system is used to apply voltage to the liquid crystal cell and irradiate ultraviolet rays at the same time to accelerate the response speed of the liquid crystal (PSA (Polymer Sustained Alignment) type element, for example, refer to patent document 1 and non-patent document 1). As a liquid crystal alignment agent used in the PSA type element, a liquid crystal alignment agent with a specific ring structure in the side chain is proposed (refer to patent document 2). The specific ring structure makes the ability of the liquid crystal to align vertically high, and the VA type liquid crystal display element using the liquid crystal alignment agent has good display characteristics. [Prior art literature] [Patent literature]

[Patent document 1] Japanese Patent Publication No. 2003-307720 [Patent document 2] WO2006/070819 [Non-patent document]

[Non-patent document 1] K. Hanaoka, SID 04 DIGEST, P. 1200-1202

[The problem that the invention wants to solve]

However, in recent years, due to the thinning and enlargement of the substrates used, a temperature difference occurs between different parts of the same substrate during firing, and the overheated portion of the liquid crystal alignment film reduces the ability of the liquid crystal alignment, resulting in a problem that the resulting liquid crystal display element partially causes poor display. The present invention is made in view of the above-mentioned problem, and provides a liquid crystal alignment agent that can obtain a liquid crystal alignment film with a high ability to align the liquid crystal even if it is overheated, and a liquid crystal display element that is not prone to poor display. [Means for solving the problem]

As a result of intensive research to solve the above problems, the inventors found that the above characteristics can be obtained by including a polymer with a specific structure in the liquid crystal alignment agent, thereby completing the present invention.

The present invention is based on the above findings and has the following as its gist: A liquid crystal aligner comprising at least one polymer (P) selected from the group consisting of polyimide precursors and polyimides having a group represented by the following formula (1); (In the formula, _X1 represents an alkylene group having 1 to 14 carbon atoms, and one or two non-adjacent methylene groups in the alkylene group may be substituted by -O- or -COO-; _X2 represents a single bond, -OCO-, -COO-, or ^CONR2- ( ^R2 represents a hydrogen atom or a methyl group); Q represents a naphthylene group, and Y represents a group containing at least one cyclohexylene group; any hydrogen atom of the naphthylene group or cyclohexylene group may be substituted by at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom; R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a fluorinated alkyl group having 1 to 12 carbon atoms, a fluorinated alkoxy group having 1 to 12 carbon atoms, -CN, -F, -OH, _-CO2 H, -OCOR ³ , or -CO ₂ R ³ , R ³ represents a methyl group or an ethyl group; * represents a bonding site). [Effects of the invention]

According to the present invention, a liquid crystal alignment agent that can obtain a liquid crystal alignment film with high ability to align liquid crystals even when overheated, and a liquid crystal display element that is not prone to display defects and has high display quality are provided. The mechanism by which the liquid crystal alignment agent and liquid crystal display element having the above-mentioned excellent characteristics can be obtained by the present invention is not necessarily clear, but it is roughly inferred as follows. The cause of the reduction in vertical alignment ability when exposed to high temperatures can be considered to be thermal decomposition of side chains with vertical alignment ability, or burial in the film due to thermal movement of side chains. On the other hand, in the study of the inventors and others, it was found that in the case of a polymer containing a rigid structure, it will help to increase the glass transition temperature of the polymer or improve thermal stability. The polymer having the specific structure of the present invention has a rigid structure such as a naphthyl group, and thus has improved thermal stability, and it is estimated that a liquid crystal alignment film having a high ability to align liquid crystals can be obtained.

＜Polymer (P)＞

The liquid crystal alignment agent of the present invention contains at least one polymer (P) having a group represented by the above formula (1) and selected from the group consisting of polyimide precursors and polyimides.

In the above formula (1), _X1 preferably represents -O-, -COO-, -( _CH2 ) _c- (c is an integer of 1 to 10), _-CH2O- , -CO-O-, -( _CH2 ) _c -CO-O-(c is an integer of 1 to 10), -( _CH2 ) _c -O-CO-(c is an integer of 1 to 10), _-CH2O- ( _CH2 ) _c- (c is an integer of 1 to 10), _-CH2O- ( _CH2 ) _c- (O) _d- (c is an integer of 1 to 10, d is an integer of 0 or 1), -CO-O-( _CH2 ) _c- (O) _d- (c is an integer of 1 to 10, d is an integer of 0 or 1), -O-( _CH2 ) _c- (O) _d- -(c is an integer of 1 to 10, d is an integer of 0 or 1), -CO-O-(CH ₂ ) _c -O-CO-(c is an integer of 1 to 10), -CO-O-(CH ₂ ) _c -CO-O-(c is an integer of 1 to 10). X ₂ preferably represents a single bond. Y preferably represents a group represented by the following formula (Z). (In the formula, X ₃ represents a single bond, -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -COO-, -OCO- or -((CH ₂ ) _a1 -A ₁ ) _m1 -. A plurality of a1s each independently represents an integer of 1 to 15, a plurality of A _1s each independently represents an oxygen atom or -COO-, and m ₁ represents an integer of 1 to 2. Y ₁ represents a cyclohexyl group, and any hydrogen atom of the cyclohexyl group may be substituted by at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, and a fluorine atom. n represents an integer of 1 to 10). In the above formula (Z), _X3 preferably represents a single bond, and n represents an integer of 1 to 4, more preferably 2 to 4. R preferably represents an alkyl group having 1 to 9 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or a fluorinated alkoxy group having 1 to 10 carbon atoms.

The group represented by the formula (1) is preferably a group represented by the following formulas (1-1) to (1-12). (c is an integer from 1 to 10. d is an integer from 0 or 1. m is an integer from 1 to 2. n is an integer from 1 to 12).

<Specific diamine> The polymer (P) is, for example, a polymer obtained from a diamine component containing a diamine having a group represented by the above formula (1) (hereinafter also referred to as "specific diamine"). The specific diamine is preferably at least one diamine selected from the group consisting of diamines represented by the following formulas (2-1) and (2-2). (In the formula, _X11 , _X21a , and _X21b are synonymous with _X1 in the above formula (1); _Q1 , _Q2a , and _Q2b are synonymous with Q in the above formula (1); _X12 , _X22a , and _X22b are synonymous with _X2 in the above formula (1); _Y1 , _Y2a , and _Y2b are synonymous with Y in the above formula (1); and _R1 , _R2a , and _R2b are synonymous with R in the above formula (1). L represents a single bond, -O-, -C( _CH3 ) _2- , -NR- (R represents a hydrogen atom or a methyl group), -CO-, -NHCO-, -COO-, -( _CH2 ) _m- , -SO2-, _-O- ( _CH2 ) _m- O-, -OC( _CH3 ) _2- , -CO-(CH ₂ ) _m -, -NH-(CH ₂ ) _m -, -SO ₂ -(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -NHCO-, -COO-(CH ₂ ) _m -OCO- (m represents an integer of 1 to 8).

Specific examples of the specific diamine include at least one diamine selected from the group consisting of diamines in which the group " _-X11 - _Q1 - _X12 - _Y1 - _R1 " in formula (2-1) represents a group represented by the above formulas (1-1) to (1-12), and diamines in which the group "-X21- _{Q2a -X22a - Y2a} - _R2a " and the group " _-X22 - _Q2b - _X22b - _Y2b - _R2b " in formula (2-2) each independently represent a group represented by the above formulas (1-1) to (1-12). Specific examples of more preferred diamines include at least one diamine selected from the group " _-X11 - _Q1 - _X12 - _Y1 - _R1 " in formula (2-1), wherein the group "-X11-Q1-X12-Y1-R1" represents a group represented by the above formulas (1-1) to (1-12), and the two amino groups are bonded at the ortho-position and the para-position with respect to the group " _-X11 - _Q1 - _X12 - _Y1 - _R1 ". Particularly preferred is at least one diamine selected from the group consisting of diamines represented by the following formulas (d-1) to (d-12). (m represents 2. n represents 3, 5 or 7. c represents 1 to 6. d represents 0 or 1).

<Other diamines> As the diamine component used to produce the polymer (P), any other diamine other than the specified diamine may be used. Other diamines include p-phenylenediamine, m-phenylenediamine, 4-(2-(methylamino)ethyl)aniline, 3,5-diaminobenzoic acid and other diamines having a carboxyl group, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 1,2-bis(4-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,2-bis(4-aminophenoxy)ethane ...3-bis(4-aminophenoxy)benzene, 1,2-bis(4-aminophenoxy)ethane, 1,2-bis(4-aminophenoxy)ethane, 1,2-bis(4-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2-Bis(4-amino-2-methylphenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,5-bis(4-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 4-(2-(4-aminophenoxy)ethoxy)-3-fluoroaniline, bis(2-(4-aminophenoxy)ethyl)ether, 4-amino-4'-(2-(4-aminophenoxy)ethoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,2' -bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenethyl)urea, etc., diamines represented by the following formulas (a-1) to (a-6), preferably 2-(2,4-diaminophenoxy)ethyl methacrylate, 2,4-diamino-N,N-diallylaniline, etc., diamines having a photopolymerizable group at the end, diamines having free radical initiation functions of the following formulas (R1) to (R5), etc., 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl- 3,6-diaminocarbazole, diamines having a heterocyclic structure of the following formula (z-1) to (z-18), diamines having a diphenylamine skeleton of the following formula (Dp-1) to (Dp-3), diamines having a group "-N(D)-" (D represents a protective group that is replaced by a hydrogen atom by thermal detachment, preferably tert-butyloxycarbonyl) of the following formula (5-1) to (5-11), diamines having an oxazoline structure of the following formula (Ox-1) to (Ox-2), diamines having a side chain structure that exhibits vertical alignment of liquid crystals of the following formula (V2-1) to (V2-13), diamines containing organic siloxanes such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, etc.

(d1 represents an integer between 2 and 10). (n represents an integer from 2 to 10).

(Boc represents tert-butyloxycarbonyl).

(However, in the formula, ^Xv1 to ^Xv4 and ^Xp1 to ^Xp8 independently represent -( _CH2 ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON( _CH3 )-, -NH-, -O-, _-CH2O- , -CH2 _- OCO-, -COO-, or -OCO-, ^Xv5 represents -O-, _-CH2O- , -CH2 _- OCO-, -COO-, or -OCO-, ^Xv6 to ^Xv7 and ^Xs1 to ^Xs4 independently represent -O-, -COO-, or -OCO-. _Xa to _Xf represent a single bond, -O-, -NH-, -O-( _CH2 ) _m -O-, -C( _CH3 ) _2- , -CO-, -COO-, -CONH-, -( _CH2 ) _m -, _-SO2- , -OC( _CH3 ) _2- , -CO-( _CH2 ) _m- , _-NH- ( _{CH2 ) m-} , -NH-( _CH2 ) _m -NH-, -SO2-(CH2) _m- , -SO2-( _CH2 ) _{m-SO2-, -CONH-(CH2)m-, -CONH-(CH2)m-NHCO-, or -COO-(CH2)m - OCO- , Rv1 to Rv4 and R1a} ^{to R1h independently represent} _{-CnH2n +1} (n is an integer of 1 to 20) or _{-OCnH2n +1} (n is an integer of 2 to 20). m represents an integer of 1 to 8).

In addition, other diamines include aliphatic diamines such as m-xylylenediamine, alicyclic diamines such as 4,4-methylenebis(cyclohexylamine), and diamines described in International Publication No. 2016/125870.

The above-mentioned 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, diamines having photopolymerizable groups at the end, diamines represented by the above-mentioned formulas (R1) to (R5), and diamines represented by the above-mentioned formulas (z-1) to (z-18) can be used in one or more kinds when manufacturing polymer (P) from the viewpoint of improving the response speed of the liquid crystal display element obtained in the step (1-3B) or (1-3C) described later. The content of these diamines is preferably 5 to 70 mol% relative to the total diamine component, and is more preferably 5 to 60 mol%, particularly preferably 5 to 50 mol% from the viewpoint of improving the voltage retention rate of the obtained liquid crystal alignment film. Other diamines can be used in one kind or in combination of two or more kinds.

<Tetracarboxylic acid component> The tetracarboxylic acid component refers to a component containing at least one selected from tetracarboxylic acid and tetracarboxylic acid derivatives. Examples of tetracarboxylic acid derivatives include tetracarboxylic acid dihalides, tetracarboxylic acid dianhydrides, tetracarboxylic acid diester dichlorides, and tetracarboxylic acid diesters. The polyimide precursor of the polymer (P) can be obtained, for example, by subjecting a diamine component containing a diamine having a group represented by the above formula (1) to a polymerization reaction with a tetracarboxylic acid component. The tetracarboxylic acid component used to produce the polymer (P) includes aromatic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, or derivatives thereof. Here, the aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by dehydrating four carboxyl groups, including at least one carboxyl group bonded to an aromatic ring, within the molecule. Aliphatic tetracarboxylic dianhydride is an acid dianhydride obtained by dehydrating four carboxyl groups bonded to a chain hydrocarbon structure within the molecule. However, it is not necessary to be composed of only a chain hydrocarbon structure, and a part thereof may have an alicyclic structure or an aromatic ring structure. Alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by dehydrating four carboxyl groups, including at least one carboxyl group bonded to an alicyclic structure, within the molecule. However, these four carboxyl groups are not bonded to an aromatic ring. Furthermore, it is not necessary to be composed of only an alicyclic structure, and a part thereof may have a chain hydrocarbon structure or an aromatic ring structure. The above-mentioned tetracarboxylic acid component preferably includes tetracarboxylic dianhydride represented by the following formula (3).

(X represents any structure selected from the following (x-1) to (x-13)). (In the formula, ^R1 to ^R4 represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring, and each of them may be the same or different. ^R5 and ^R6 represent a hydrogen atom or a methyl group, and each of them may be the same or different. j and k each independently represent 0 or 1, and _A1 and _A2 each independently represent a single bond, an ether group, a carbonyl group, an ester group, a phenyl group, a sulfonyl group or an amide group. *1 represents the bonding site of the anhydride group on one side, and *2 represents the bonding site of the anhydride group on the other side).

Preferred specific examples of the above (x-12) and (x-13) include the following formulas (x-14) to (x-29). * represents a bonding site.

Preferred examples of the tetracarboxylic dianhydride or its derivative represented by the above formula (3) include tetracarboxylic dianhydride or its derivative represented by the formula (3) wherein X is the above formulas (x-1) to (x-7) and (x-11) to (x-13).

<Contents of polymer (P), diamine component and tetracarboxylic acid component> The content of the polymer (P) used in the present invention is preferably 1-10% by mass, more preferably 2-9% by mass, relative to the total mass of the liquid crystal alignment agent.

The content of the specific diamine is preferably 10-80 mol%, more preferably 20-70 mol%, and even more preferably 30-60 mol% relative to the total amount of the diamine component used to produce the polymer (P). The diamine component used to produce the polymer (P) can also be used alone or in combination of two or more, depending on the solubility of the polymer in the solvent or the coating property of the liquid crystal alignment agent, the liquid crystal alignment property when used as a liquid crystal alignment film, the voltage retention rate, the stored charge, and other properties.

The content of the tetracarboxylic dianhydride represented by formula (3) is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more relative to the total amount of the diamine component used to produce the polymer (P). The tetracarboxylic acid component used to produce the polymer (P) can also be used alone or in combination of two or more, depending on the solubility of the polymer in the solvent or the coating property of the liquid crystal alignment agent, the liquid crystal alignment property when used as a liquid crystal alignment film, the voltage retention rate, the stored charge, and other properties.

<Polymer> The present invention also includes a polymer obtained from a diamine component containing at least one diamine represented by the above formula (2-1) or (2-2). Such a polymer may include a polyimide precursor, polyimide, polyamide, polyurea, etc. The above polymer is preferably at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor.

<Production of polyimide precursor (polyamic acid)> The polyimide precursor used in the present invention may be polyamic acid or polyamic acid ester, etc. The polyamic acid of the polyimide precursor used in the present invention can be produced, for example, by the following method. Specifically, it can be synthesized by reacting a diamine component and a tetracarboxylic acid component in the presence of an organic solvent at -20 to 150°C, preferably 0 to 80°C, for 30 minutes to 24 hours, preferably 1 to 12 hours.

The reaction of the diamine component and the tetracarboxylic acid component is usually carried out in an organic solvent. The organic solvent used at this time is not particularly limited as long as it can dissolve the generated polyimide precursor. The following series lists specific examples of organic solvents used in the reaction, but are not limited to these examples. For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide or 1,3-dimethyl-2-imidazolidinone can be listed. In addition, when the solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or organic solvents represented by the following formulas [D-1] to [D-3] can be used. In formula [D-1], ^D1 represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], ^D2 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], ^D3 represents an alkyl group having 1 to 4 carbon atoms. These organic solvents may be used alone or in combination. Furthermore, even a solvent that does not dissolve the polyimide precursor may be mixed with the above-mentioned solvent and used within a range in which the generated polyimide precursor does not precipitate.

The concentration of the polyamine polymer in the reaction system is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of not easily causing polymer precipitation and easily obtaining a high molecular weight polymer.

The polyamine obtained as described above can be recovered by injecting a poor solvent while stirring the reaction solution to precipitate the polymer. Alternatively, the purified polyamine powder can be obtained by performing precipitation several times, washing with a poor solvent, and drying at room temperature or by heating. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellulose, acetone, toluene, and the like.

<Production of polyimide precursor (polyamic acid ester)> The polyamic acid ester used as the polyimide precursor in the present invention can be produced, for example, by the production method (1), (2) or (3) shown below.

(1) Production from polyamine Polyamine esters can be produced by esterifying the polyamine produced as described above. Specifically, they can be produced by reacting polyamine with an esterifying agent in the presence of an organic solvent at -20 to 150°C, preferably 0 to 50°C, for 30 minutes to 24 hours, preferably 1 to 4 hours.

The esterifying agent is preferably one that can be easily removed by purification, and examples thereof include N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl acetal, N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dineopentylbutyl acetal, N,N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene, and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The amount of the esterifying agent added is preferably 2 to 6 molar equivalents relative to 1 mole of the repeating unit of polyamine.

Examples of organic solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, or 1,3-dimethyl-2-imidazolidinone. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or organic solvents represented by the above formulas [D-1] to [D-3] can be used.

These organic solvents can be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyimide precursor, it can be mixed with the above solvents to the extent that the generated polyimide precursor will not precipitate. In addition, the water in the organic solvent will hinder the polymerization reaction and become the cause of the hydrolysis of the generated polyimide precursor, so it is better to use the organic solvent after dehydration. The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in terms of the solubility of the polymer. These can be used alone or in combination of two or more. The concentration during production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of not easily causing the precipitation of the polymer and easily obtaining a high molecular weight product.

(2) Production by reaction of tetracarboxylic acid diester dichloride and diamine Polyamide can be produced by reaction of tetracarboxylic acid diester dichloride and diamine. Specifically, it can be produced by reacting tetracarboxylic acid diester dichloride and diamine in the presence of alkali and organic solvent at -20~150℃, preferably 0~50℃, for 30 minutes to 24 hours, preferably 1~4 hours.

The above-mentioned base can be pyridine, triethylamine, 4-dimethylaminopyridine, etc., and pyridine is preferred because the reaction proceeds mildly. The amount of base added is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and easy to obtain a high molecular weight body.

The above organic solvent is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in terms of solubility of monomers and polymers. One or more of these can be used alone or in combination. The polymer concentration during production is preferably 1-30% by mass, more preferably 5-20% by mass, from the viewpoint of not easily causing polymer precipitation and easily obtaining a high molecular weight body. In addition, in order to prevent hydrolysis of tetracarboxylic acid diester dichloride, the organic solvent used in the production of polyamide ester is preferably dehydrated as much as possible, preferably in a nitrogen environment, to prevent external air from mixing.

(3) Production from tetracarboxylic acid diester and diamine Polyamide ester can be produced by polycondensing tetracarboxylic acid diester and diamine. Specifically, it can be produced by reacting tetracarboxylic acid diester and diamine in the presence of a condensing agent, an alkali, and an organic solvent at 0-150°C, preferably 0-100°C, for 30 minutes to 24 hours, preferably 3-15 hours.

The condensation agent may include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N,N'-carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, O-(benzotriazole-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate, O-(benzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonic acid diphenyl ester, etc. The amount of the condensation agent added is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester.

The above-mentioned alkali can use tertiary amines such as pyridine and triethylamine. The amount of the alkali added is preferably 2 to 4 times the molar amount relative to the diamine component from the viewpoint of easy removal and easy acquisition of a high molecular weight body. In addition, in the above-mentioned reaction, by adding Lewis acid as an additive, the reaction is efficiently carried out. The Lewis acid is preferably lithium halides such as lithium chloride and lithium bromide. The amount of Lewis acid added is preferably 0 to 1.0 times the molar amount relative to the diamine component.

Among the three methods for producing polyamic acid esters, the method (1) or (2) is particularly preferred because it can produce polyamic acid esters with high molecular weight. The polyamic acid ester solution obtained as described above can be injected into a poor solvent while being fully stirred to precipitate the polymer. After several precipitations, the solution is washed with a poor solvent and then dried at room temperature or by heating to obtain a purified polyamic acid ester powder. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellulose, acetone, toluene, and the like.

<Production of polyimide> The polyimide used in the present invention can be produced by imidizing the above-mentioned polyamide acid.

Imidization can be carried out by stirring the polyamide to be imidized in an organic solvent in the presence of an alkaline catalyst and an acid anhydride. The organic solvent used in the above-mentioned polymerization reaction can be used as the organic solvent. Examples of alkaline catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it has a moderate alkalinity that allows the reaction to proceed. In addition, examples of acid anhydrides include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. Among them, acetic anhydride is preferred because it is easy to purify after the reaction. Furthermore, the imidization rate referred to in this specification refers to the proportion of imide groups in the total amount of imide groups and carboxyl groups (or their derivatives) from tetracarboxylic dianhydride or its derivatives. In polyimide, the imidization rate does not necessarily have to be 100%, and can be adjusted arbitrarily according to the use or purpose. The imidization rate of the polyimide used in the present invention is preferably 20-100%, and more preferably 50-99%.

The temperature for the imidization reaction is -20 to 140°C, preferably 0 to 100°C, and the reaction time is 0.5 to 100 hours, preferably 1 to 80 hours. The amount of the alkaline catalyst is 0.5 to 30 mole times of the amide acid, preferably 2 to 20 mole times, and the amount of the acid anhydride is 1 to 50 mole times of the amide acid, preferably 3 to 30 mole times. The imidization rate of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature, and the reaction time.

The solution of polyamic acid ester or polyamic acid after the imidization reaction contains residual catalysts, etc., so it is better to recover the imidized polymer by the means described below, redissolve it with an organic solvent, and use it as the (A) component of the liquid crystal alignment agent of the present invention. The solution of polyimide obtained as described above can be injected into a poor solvent while being fully stirred to precipitate the polymer. After several precipitations, after washing with a poor solvent, a refined polyimide powder can be obtained at room temperature or by heating and drying. The above-mentioned poor solvent is not particularly limited, and methanol, acetone, hexane, butyl cellulose, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, etc. can be listed.

<Other ingredients> The liquid crystal alignment agent of the present invention may also contain ingredients other than the polymer (P) as needed. Ingredients other than the polymer (P) include, for example, polymers other than the polymer (P), crosslinking compounds, functional silane compounds, surfactants, compounds with photopolymerizable groups, organic solvents, etc.

Polymers other than polymer (P) can be used for the purpose of improving the solution properties of the liquid crystal alignment agent or the electrical properties of the liquid crystal alignment film, or imparting photo-alignment to the liquid crystal alignment film. Examples of the polymer include polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, polyester, polyamide, polyurea, cellulose derivatives, polyacetal, polystyrene derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylate, and the like.

When a polymer other than the polymer (P) is added to the liquid crystal alignment agent, its blending ratio is preferably 70 parts by mass or less, more preferably 0.1 to 60 parts by mass, and even more preferably 0.1 to 40 parts by mass, relative to 100 parts by mass of all polymer components in the composition.

The crosslinking compound can be used for the purpose of improving the strength of the liquid crystal alignment film. The crosslinking compound can be listed as a compound having an epoxy group, an isocyanate group, an oxycyclobutane group, or a cyclocarbonate group as described in paragraphs [0109] to [0113] of the international publication WO2016/047771, or a compound having at least one group selected from the group consisting of a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group, and can also be listed as a compound having a blocked isocyanate group.

The blocked isocyanate compound is available as a commercial product, and preferably, for example, Coronate AP stable M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate MS-50 (all manufactured by Nippon Polyurethane Industries, Ltd.), TAKENATE B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (all manufactured by Mitsui Chemicals, Inc.) and the like can be used.

Specific examples of preferred crosslinking compounds include compounds represented by the following formulas (CL-1) to (CL-11).

The above is an example of the crosslinking compound, but the invention is not limited thereto. The crosslinking compound used in the liquid crystal alignment agent of the present invention may be one kind or a combination of two or more kinds.

In the liquid crystal alignment agent of the present invention, the content of other crosslinking compounds is 0.1-150 parts by mass, or 0.1-100 parts by mass, or 1-50 parts by mass relative to 100 parts by mass of the total polymer components.

Functional silane compounds can be used to improve the adhesion between the liquid crystal alignment film and the base substrate. Specific examples include the silane compounds described in paragraph [0019] of International Publication No. 2014/119682. The content of the functional silane compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, relative to 100 parts by mass of the total polymer component.

Surfactants can be used for the purpose of improving the uniformity of the film thickness or the surface smoothness of the liquid crystal alignment film. Examples of surfactants include fluorine-based surfactants, polysilicone-based surfactants, and non-ionic surfactants. Specific examples of these include the surfactants described in paragraph [0117] of International Publication WO2016/047771. The amount of the surfactant used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, relative to 100 parts by mass of all polymer components contained in the liquid crystal alignment agent.

Examples of the compound having a photopolymerizable group include compounds having one or more polymerizable unsaturated groups such as acrylate groups or methacrylate groups in the molecule, for example, compounds represented by the following formulas (M-1) to (M-7).

Furthermore, in the liquid crystal alignment agent of the present invention, as a compound that promotes charge movement in the liquid crystal alignment film and promotes charge deficiency in the device, a nitrogen-containing heterocyclic amine compound represented by formula [M1] to formula [M156] disclosed in paragraphs [0194] to [0200] of International Publication WO2011/132751 (published on October 27, 2011) may be added, preferably 3-picoline amine and 4-picoline amine. The amine compound may also be directly added to the liquid crystal alignment agent, but it is preferably added after being made into a solution with a concentration of 0.1 to 10% by weight, preferably 1 to 7% by weight. The solvent is not particularly limited as long as it can dissolve the specific polymer (P).

When the liquid crystal alignment agent of the present invention contains polyamic acid or polyamic acid ester, an imidization accelerator may be added for the purpose of efficiently promoting imidization by heating during the calcination of the coating film.

<Organic solvent> The liquid crystal alignment agent of the present invention can also be prepared as a liquid composition in which the polymer (P) and other components used as needed are dispersed or dissolved in a suitable organic solvent.

Examples of the organic solvent used include lactone solvents such as γ-valerolactone and γ-butyrolactone; γ-butyrolactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 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, N-cyclohexyl-2-pyrrolidone and other lactam solvents; N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N,N-dimethyllactamide and other amide solvents; 4-hydroxy-4-methyl-2-pentanone, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl methoxy propionate, ethyl propionate Ethoxylates, ethylene glycol monomethyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl celoxylate), ethylene glycol monobutyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monobutyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol Monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), isoamyl propionate, isoamyl isobutyrate, diisopropyl ether, diisoamyl ether; carbonate solvents such as ethyl carbonate and propylene carbonate; 1-hexanol, cyclohexanol, 1,2-ethylene glycol, diisobutyl carbinol (2,6-dimethyl-4-heptanol), propylene glycol diacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, etc. These can be used alone or in combination of two or more.

Preferable solvent combinations include 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-methyl-2-pyrrolidone, γ-butyrolactone, and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, and propylene glycol monobutyl ether and diisobutyl ether. Ketone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl carbinol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N-methyl-2-pyrrolidone and 3-ethoxy Ethyl propionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl 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 propylene glycol diacetate, γ-butyrolactone and 4-hydroxy-4-methyl N-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl 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 N,N-dimethyl lactamide and diisobutyl ketone, etc. The type and content of such solvents are appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

The solid component concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the organic solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 1~10 mass%. The range of the particularly optimal solid component concentration varies depending on the method used when applying the liquid crystal alignment agent to the substrate. For example, when the rotator method is used, the solid component concentration is particularly preferably in the range of 1.5~4.5 mass%. When the printing method is used, it is particularly preferred to make the solid component concentration in the range of 3~9 mass%, thereby making the solution viscosity in the range of 12~50mPa･s. When the inkjet method is used, the solid content concentration is preferably in the range of 1 to 5 mass %, thereby making the solution viscosity in the range of 3 to 15 mPa･s.

<Liquid crystal alignment film and liquid crystal display element> The liquid crystal alignment film of the present invention is formed by a liquid crystal alignment agent prepared as described above. In addition, the liquid crystal display element of the present invention has a liquid crystal alignment film formed by using the above-mentioned liquid crystal alignment agent. The driving mode of the liquid crystal display element is not particularly limited. From the perspective of obtaining the effect of the present invention, the preferred driving mode is TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.).

A liquid crystal display element can be manufactured, for example, by the steps including the following steps (1-1) to (1-3).

[Step (1-1): Formation of coating] First, a liquid crystal alignment agent is coated on a substrate, and then the coated surface is heated to form a coating on the substrate. First, two substrates with patterned transparent conductive films are formed as a pair, and the liquid crystal alignment agent is preferably coated on each transparent conductive film forming surface by lithography, rotary coating, roller coating or inkjet printing.

The substrate may be a transparent substrate made of glass such as float glass and sodium glass, or plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, poly(aliphatic cycloolefin), etc. The transparent conductive film disposed on one side of the substrate may be a NESA film (registered trademark of PPG, USA) containing tin oxide (SnO ₂ ), an ITO film containing indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc.

After applying the liquid crystal alignment agent, it is preferred to perform preliminary heating (pre-baking) for the purpose of preventing the applied liquid crystal alignment agent from dripping. The pre-baking temperature is preferably 30~200°C, more preferably 40~150°C, and particularly preferably 40~100°C. Thereafter, a firing (post-baking) step is performed for the purpose of completely removing the solvent and, when the liquid crystal alignment agent contains polyamine acid or polyamine ester, causing the imidization of the polyamine acid or polyamine ester. The firing temperature (post-baking temperature) at this time is preferably 80~300°C, more preferably 120~250°C. The post-baking time is preferably 5~200 minutes, more preferably 10~100 minutes. The thickness of the film formed in this way is preferably 1 to 1000 nm, more preferably 5 to 500 nm.

[Step (1-2): Treatment for imparting alignment ability] When manufacturing TN type and STN type liquid crystal display elements, the coating formed in the above step (1-1) is treated to impart liquid crystal alignment ability. The treatment for imparting alignment ability includes rubbing the coating in a certain direction with a roller wound with a cloth containing fibers such as nylon, rayon, cotton, etc. On the other hand, when manufacturing VA type liquid crystal display elements, the coating formed in the above step (1-1) can be used directly as a liquid crystal alignment film, or the coating can be treated to impart alignment ability.

The liquid crystal alignment film suitable for VA type liquid crystal display elements can also be suitable for use in PSA (Polymer Sustained Alignment) type liquid crystal display elements. The manufacturing method of the liquid crystal display element using the liquid crystal alignment agent of the present invention can be listed as follows: for example, the liquid crystal alignment agent is applied on a pair of substrates having a conductive film to form a coating film, and the coating films are arranged oppositely with a layer of liquid crystal molecules interposed therebetween to form a liquid crystal cell, and a voltage is applied between the conductive films of the pair of substrates, and the liquid crystal cell is irradiated with light.

[Step (1-3): Construction of liquid crystal cell] (1-3A) Prepare two substrates with liquid crystal alignment films formed as described above, and manufacture liquid crystal cells by arranging liquid crystals between the two opposing substrates. To manufacture liquid crystal cells, for example, the following two methods can be listed. The first method is to arrange two substrates opposing each other with their respective liquid crystal alignment films separated by a gap (cell gap), and to bond the peripheries of the two substrates together using a sealant, and to inject liquid crystal into the liquid crystal gap divided by the substrate surface and the sealant, and then to manufacture liquid crystal cells by sealing the injection hole. The second method is a technique called ODF (One Drop Fill) method. A UV-curable sealant is applied at a specific location on one of the two substrates on which a liquid crystal alignment film is formed, and then liquid crystal is dripped at several specific locations on the surface of the liquid crystal alignment film. Then, the other substrate is bonded in such a way that the liquid crystal alignment films face each other, and liquid crystal is applied to the entire surface of the substrate. Then, ultraviolet light is irradiated to the entire surface of the substrate to cure the sealant, thereby manufacturing a liquid crystal cell. Regardless of the method used, it is more desirable to further heat the liquid crystal cell manufactured as described above to a temperature at which the liquid crystal used is isotropic, and then slowly cool it to room temperature to remove the flow alignment when the liquid crystal is filled.

The sealant may be, for example, epoxy resin containing aluminum oxide balls as a hardener and a spacer. Examples of the liquid crystal include nematic liquid crystal and lamellar liquid crystal, among which nematic liquid crystal is particularly preferred.

(1-3B) When manufacturing a PSA type liquid crystal display element, the liquid crystal cell is constructed in the same manner as in the above (1-3A) except that the above-mentioned compound having a photopolymerizable group is injected or dripped together with the liquid crystal. At this time, the content of the compound having a photopolymerizable group is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the liquid crystal component. After the liquid crystal cell is manufactured, an AC or DC voltage is applied to the liquid crystal cell while heating or irradiating it with ultraviolet light to polymerize the polymerizable compound. In this way, the orientation of the liquid crystal molecules can be controlled. Thereafter, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of a pair of substrates. The voltage applied here can be, for example, a DC or AC voltage of 5 to 50 V. Furthermore, the irradiated light is preferably ultraviolet light having a wavelength of 300 to 400 nm. The light source of the irradiated light may be, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, etc. The irradiation dose is preferably 1,000 J/m ² or more and less than 200,000 J/m ² , and more preferably 1,000 to 100,000 J/m ² .

(1-3C) When a liquid crystal alignment agent containing a compound having a photopolymerizable group is used to form a coating on a substrate, a liquid crystal cell can be constructed in the same manner as in (1-3A) above, and then the liquid crystal cell is irradiated with light while a voltage is applied between conductive films on a pair of substrates to produce a method for producing a liquid crystal display element. At this time, the content of the compound having a photopolymerizable group is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, relative to 100 parts by mass of all polymer components. According to this method, the advantages of the PSA mode can be achieved with a small amount of light irradiation. The conditions of the applied voltage or the irradiated light can be applied to the description of (1-3B) above.

Then, a liquid crystal display element can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell. The polarizing plate attached to the outer surface of the liquid crystal cell can be a polarizing plate sandwiched between a polarizing film called "H film" that stretches polyvinyl alcohol and absorbs iodine and a cellulose acetate protective film, or a polarizing plate formed by the H film itself. [Example]

The present invention is described in more detail with reference to the following examples, but the present invention is not limited thereto. The meanings of the abbreviations of the compounds used in the examples are as follows. (Tetracarboxylic dianhydride) BODA: bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride. CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride. (Diamine) m-PDA: 1,3-phenylenediamine (Solvent) NMP: N-methyl-2-pyrrolidone BCS: Butyl celecoxib THF: Tetrahydrofuran

<Determination of molecular weight of polyimide> Measurement apparatus: Gel permeation chromatography (GPC) (SSC-7200) manufactured by Senshu Scientific Co., Ltd., Column: Column (KD-803, KD-805) manufactured by Shodex Co., Ltd., Column temperature: 50°C, Solvent: N,N'-dimethylformamide (containing additives of lithium bromide monohydrate (LiBr･H ₂ O) 30mmol/L, phosphoric acid･anhydrous crystals (o-phosphoric acid) 30mmol/L, tetrahydrofuran (THF) 10ml/L), Flow rate: 1.0ml/min, Standard sample for calibration curve preparation: TSK manufactured by Tosoh Corporation Standard polyethylene oxide (molecular weight approximately 9000,000, 150,000, 100,000, 30,000) and polyethylene glycol manufactured by Polymer Laboratories (molecular weight approximately 12,000, 4,000, 1,000).

<Determination of chemical imidization rate> Put 20 mg of polyimide powder into an NMR sample tube (NMR sample tube standard φ5 manufactured by Kusano Scientific Co., Ltd.), add 1.0 ml of dimethyl sulfoxide (DMSO-d6, 0.05% TMS mixture), and apply ultrasound to completely dissolve. The solution is measured by 500 MHz proton NMR using an NMR analyzer (JNW-ECA500) manufactured by JEOL Datum Co., Ltd. The imidization rate is determined by using the proton from the structure that does not change before and after imidization as the reference proton, and the peak integral value of the proton from the NH group of the amide appearing around 9.5~10.0 ppm is used to obtain the following formula. Furthermore, in the formula, x is the peak integral value of the proton from the NH group of the acylamidin, y is the peak integral value of the reference proton, and α is the ratio of the number of reference protons to the number of protons of the NH group of the acylamidin in the case of polyacylamidin (acylamidinization rate 0%). Chemical acylamidinization rate (%) = (1-α･x/y) × 100

DA-S1 is a novel compound, and the synthesis method is described in detail below. The product described in the following monomer synthesis example 1 was identified by 1H-NMR analysis. The analysis conditions are as follows. Apparatus: Varian NMR System 400 NB (400 MHz) Measurement solvent: CDCl3 Standard substance: Tetramethylsilane (TMS) (δ0.0 ppm for 1H)

＜Synthesis of Monomer Synthesis Example DA-S1＞

Synthesis of compound 3 (mixture of 3a, 3b) Add magnesium (15.39 g, 63.3 mmol, 1.5 eq.) to a 4-necked flask, vacuum dry with a vacuum pump for 1 hour, then add THF (100 g) with a syringe and stir at room temperature. Then, slowly drip and add a solution of compound 1 (100 g, 42.2 mmol) in THF (300 g) at a rate that allows for steady reflux. Then, cool the reaction solution to 0°C and drip a solution of compound 2 (105.60 g, 42.2 mmol, 1.0 eq.) in THF (200 g). After the dripping is complete, return the temperature of the reaction solution to room temperature and stir at room temperature for 3 hours. After that, toluene (1L) was added to dilute the reaction solution, and the reaction solution was cooled to 0°C again, and 10% acetic acid solution (500g) was slowly added dropwise. Then, the aqueous layer was removed by liquid separation, and the organic layer was washed with saturated saline (1L), saturated sodium bicarbonate solution (1L), and saturated saline (1L), respectively, and the organic layer was dried with anhydrous magnesium sulfate. After that, it was filtered and distilled off with an evaporator to obtain 172g of crude crystals of compound 3. The obtained crude crystals were directly used in the next reaction.

Synthesis of Compound 4 A mixture of crude crystals of Compound 3 (172 g, 422 mmol) and p-toluenesulfonic acid monohydrate (4.82 g, 25.3 mmol, 0.06 eq.) in dehydrated toluene (MS4A dehydrated product, 2 L) was reacted for 2 hours under reflux while removing water. After the reaction was completed, about half of the toluene was distilled off with an evaporator, and the solution was stirred at room temperature to precipitate solids. The obtained solid was filtered to obtain crystals of Compound 4 (yield 150 g, yield 91%).

Synthesis of compound 5 (mixture of 5a and 5b) A mixture of compound 4 (108 g, 276 mmol), 5% palladium-carbon powder (containing water, 11 g, 10 wt%), ethyl acetate (1 L), and ethanol (1 L) was stirred at room temperature in the presence of hydrogen. After the reaction was completed, toluene (2 L) was added to dissolve the crystals, and the reaction mixture was filtered through diatomaceous earth, and the diatomaceous earth was washed with 1 L of toluene. After the filtrate was concentrated under reduced pressure, the target compound 5 (yield 103.3 g, yield 95%) was obtained.

Synthesis of Compound 6 At 0°C, under nitrogen substitution, BBr ₃ (1.0M-CH ₂ Cl ₂ , 243mL, 1.01 mol) was added dropwise to a solution of 5 (95.4g, 243mmol) in dichloromethane (800mL). After the addition, the mixture was stirred at 0°C for 2 hours. After the reaction was completed, the reaction solution was added to distilled water in small amounts. The mixture was extracted with ethyl acetate (1L), and the extract was washed twice with 500mL of distilled water. The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure. The crude product was recrystallized with ethanol, filtered, and washed with ethanol to obtain the target compound 6 (yield 18.6g, yield 21%).

Synthesis of Compound 8 In a mixture of Compound 6 (10.0 g, 26.4 mmol), potassium carbonate (11.0 g, 79.2 mmol, 3 eq.), and toluene (50 g), a solution of Compound 7 (5.35 g, 26.4 mmol) in toluene (20 g) was added dropwise under reflux. After the addition, the mixture was stirred under reflux overnight. After the reaction was completed, the reaction solution was cooled to about 60°C, ethyl acetate (500 g) was added, and the mixture was washed with distilled water three times. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The obtained crude product was recrystallized with an acetonitrile/ethanol (2:1) solution, filtered, and the filtered crystals were washed with ethanol to obtain crude crystals of Compound 8. The crude crystals were purified by column chromatography (SiO ₂ , CHCl ₃ ) to obtain crystals of compound 8 (yield 7.1 g, yield 49%).

Synthesis of DA-S1 A mixture of compound 8 (12.2 g, 22.4 mmol), 5% palladium carbon powder (water content 1.22 g, 10 wt%), and dioxane (120 g) was stirred at 60°C for 4 hours in the presence of hydrogen. After the reaction was completed, nitrogen substitution was performed and the mixture was filtered through diatomaceous earth at 60°C. The filtrate was distilled off the solvent under reduced pressure to obtain a crude product. The crude product was recrystallized with 2-propanol/ethyl acetate (2:1) to obtain the target compound DA-S1 (yield 8.0 g, yield 74%). 1H NMR (CDCl3, δppm): 7.725(1H, d), 7.577(2H, m), 7.272(2H, m), 7.102(1H, s), 6.791(1H, d), 6.207(1H, d), 6.117(1H, dd), 3.621(4H, broad) , 2.553(1H, m), 2.067-0.863 (31H, m).

<Synthesis Example 1> BODA (1.50 g, 6.00 mmol), m-PDA (0.78 g, 7.20 mmol) and DA-S1 (2.33 g, 4.80 mmol) were dissolved in NMP (18.4 g), reacted at 60°C for 3 hours, and then CBDA (1.15 g, 5.88 mmol) and NMP (4.60 g) were added, and reacted at 40°C for 6 hours to obtain a polyamine solution. NMP was added to the polyamine solution (23.0 g) and diluted to 6.5% by mass, and then acetic anhydride (4.87 g) and pyridine (1.51 g) as an imidization catalyst were added, and reacted at 80°C for 2.5 hours. The reaction solution was poured into methanol (270 g), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 60°C to obtain polyimide powder. The chemical imidization rate of the polyimide was 82%, Mn was 14100, and Mw was 51800. NMP (24.3 g) was added to the obtained polyimide powder (2.7 g), and stirred at 70°C for 12 hours to dissolve it. BCS (18.0 g) was added to the solution, and stirred at room temperature for 2 hours to obtain liquid crystal alignment agent SPI-1.

<Synthesis Example 2> BODA (2.75 g, 11.0 mmol), m-PDA (1.43 g, 13.2 mmol) and DA-S2 (3.83 g, 8.80 mmol) were dissolved in NMP (32.0 g), reacted at 60°C for 3 hours, and then CBDA (2.11 g, 10.8 mmol) and NMP (8.50 g) were added, and reacted at 40°C for 6 hours to obtain a polyamine solution. NMP was added to the polyamine solution (44.6 g) and diluted to 6.5% by mass, and then acetic anhydride (9.86 g) and pyridine (3.06 g) as an imidization catalyst were added, and reacted at 80°C for 2.5 hours. The reaction solution was added to methanol (526 g), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 60°C to obtain a polyimide powder. The chemical imidization rate of the polyimide was 78%, Mn was 13700, and Mw was 47400. NMP (24.3 g) was added to the obtained polyimide powder (2.7 g), and it was stirred at 70°C for 12 hours to dissolve. BCS (18.0 g) was added to the solution, and it was stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent SPI-2.

<Synthesis Example 3> BODA (2.75 g, 11.0 mmol), m-PDA (1.43 g, 13.2 mmol) and DA-S3 (3.35 g, 8.80 mmol) were dissolved in NMP (30.1 g), reacted at 60°C for 3 hours, and then CBDA (2.11 g, 10.8 mmol) and NMP (8.50 g) were added, and reacted at 40°C for 6 hours to obtain a polyamine solution. NMP was added to the polyamine solution (42 g) to dilute to 6.5% by mass, and then acetic anhydride (9.74 g) and pyridine (3.02 g) were added as an imidization catalyst, and reacted at 80°C for 2.5 hours. The reaction solution was poured into methanol (497 g), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 60°C to obtain a polyimide powder. The chemical imidization rate of the polyimide was 70%, Mn was 15400, and Mw was 51200. NMP (24.3 g) was added to the obtained polyimide powder (2.7 g), and it was stirred at 70°C for 12 hours to dissolve. BCS (18.0 g) was added to the solution, and it was stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent SPI-3.

<Example 1> The liquid crystal alignment agent SPI-1 obtained in Synthesis Example 1 was used to prepare a liquid crystal cell in the order shown below. The liquid crystal alignment agent SPI-1 obtained in Synthesis Example 1 was rotationally coated on a glass substrate with an ITO electrode and a substrate with an ITO electrode pattern with a line/space of 500μm, dried on a heating plate at 80°C for 90 seconds, and then calcined in a hot air circulation oven at 230°C for 30 minutes, or calcined for 90 minutes under severe conditions, to form a liquid crystal alignment film with a film thickness of 100nm. 4μm spacer beads were scattered on one side of the liquid crystal alignment film, and a thermosetting sealant (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was further printed. Next, the other substrate with the liquid crystal alignment film formed on the side thereof as the inner side is bonded to the previous substrate, and the sealant is cured to produce an empty cell. Liquid crystal MLC-3023 (trade name manufactured by Merck & Co., Ltd.) containing a polymerizable compound for PSA is injected into the empty cell by a reduced pressure injection method to produce a liquid crystal cell. Afterwards, the obtained liquid crystal cell is subjected to PSA treatment and the pre-tilt angle is measured.

[PSA treatment] Under the condition of applying a DC voltage of 15V, irradiate UV 10J/ ^cm2 from the outside of the liquid crystal cell through a cutoff filter below 325nm. The UV irradiance is a UV-MO3A made by ORC connected to a UV-35 light receiver. Afterwards, in order to deactivate the unreacted polymerizable compound remaining in the liquid crystal cell, irradiate UV (UV lamp: FLR40SUV32/A-1) for 30 minutes using a UV-FL irradiation device made by Toshiba Lighting & Technology without applying voltage. [Pre-tilt angle measurement] Use an LCD analyzer (LCA-LUV42A made by Meiling Technica) to measure the pre-tilt angle of the cell produced above.

<Comparative Examples 1 and 2> Except that SPI-2 and SPI-3 were used to replace the liquid crystal alignment agent SPI-1, the respective liquid crystal cells were prepared in the same manner as in Example 1. After PSA treatment, the pre-tilt angle was measured. The respective results are shown in Table 2.

As shown in Table 2, it was confirmed that the difference in pre-tilt angle between the severe condition and the standard condition was large in Comparative Examples 1 and 2 using the liquid crystal alignment agents SPI-2 and SPI-3 containing the vertical alignment side-chain diamine without the naphthylene group, while the difference in pre-tilt angle between the severe condition and the standard condition was extremely small in Example 1 using the liquid crystal alignment agent SPI-1 containing the vertical alignment side-chain diamine DA-S1 containing the naphthylene group. It can be seen from this that the liquid crystal alignment agent containing the vertical alignment side-chain diamine containing the naphthylene group can obtain a liquid crystal alignment film with a high ability to align the liquid crystal even if it is overheated.

Furthermore, the entire contents of the specification, patent application scope, and abstract of Japanese Patent Application No. 2019-173214 filed on September 24, 2019 are cited here and incorporated as a disclosure of the specification of the present invention.

Claims (15)

A liquid crystal alignment agent comprises at least one polymer (P) selected from the group consisting of polyimide precursors and polyimides having a group represented by the following formula (1): *-X ₁ -QX ₂ -YR (1) (wherein X ₁ represents an alkylene group having 1 to 14 carbon atoms, wherein one or two non-adjacent methylene groups in the alkylene group may be substituted by -O- or -COO-; X ₂ represents a single bond, -OCO-, -COO-, or CONR ² -(R ² represents a hydrogen atom or a methyl group); Q represents a naphthyl group, and Y represents a group containing at least one cyclohexyl group; any hydrogen atom of the aforementioned naphthyl group or cyclohexyl group may be substituted by at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, and a fluorine atom; R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a fluorinated alkyl group having 1 to 12 carbon atoms, a fluorinated alkoxy group having 1 to 12 carbon atoms, -CN, -F, -OH, -CO ₂ H, -OCOR ³ , or -CO ₂ R ³ , and R ³ represents a methyl group or an ethyl group; * represents a bonding site). The liquid crystal alignment agent of claim 1, wherein the aforementioned polymer (P) is a polymer obtained from a diamine component containing a diamine having a group represented by the aforementioned formula (1). The liquid crystal alignment agent of claim 2, wherein the diamine having a group represented by the aforementioned formula (1) is at least one diamine selected from the group consisting of diamines represented by the following formulas (2-1) and (2-2);

(wherein, _X11 , _X21a , and _X21b are synonymous with _X1 in the above formula (1); _Q1 , _Q2a , and _Q2b are synonymous with Q in the above formula (1); _X12 , _X22a , and _X22b are synonymous with _X2 in the above formula (1); _Y1 , _Y2a , and _Y2b are synonymous with Y in the above formula (1); _R1 , _R2a , and _R2b are synonymous with R in the above formula (1); L represents a single bond, -O-, -C( _CH3 ) _2- , -NR- (R represents a hydrogen atom or a methyl group), -CO-, -NHCO-, -COO-, _- ( _CH2 ) _m- , -SO2-, -O-( _CH2 ) _m -O-, -OC( _CH3 ) _2- , -CO-(CH ₂ ) _m -, -NH-(CH ₂ ) _m -, -SO ₂ -(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -NHCO-, or -COO-(CH ₂ ) _m -OCO-; m represents an integer of 1 to 8). The liquid crystal alignment agent of any one of claims 1 to 3, wherein in formula (1), Y represents a group represented by the following formula (Z);

(wherein, X ₃ represents a single bond, -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -COO-, -OCO- or -((CH ₂ ) _a1 -A ₁ ) _m1 -; wherein a1s each independently represent an integer of 1 to 15, _A1s each independently represent an oxygen atom or -COO-, _m1 represents an integer of 1 to 2; Y ₁ represents a cyclohexyl group, and any hydrogen atom of the cyclohexyl group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, and a fluorine atom; and n represents an integer of 1 to 10). The liquid crystal alignment agent of claim 2 or 3, wherein the diamine having a group represented by the aforementioned formula (1) is at least one diamine selected from the group consisting of diamines represented by the following formulas (d-1) to (d-12);

(m represents 2; n represents 3, 5 or 7; c represents 1 to 6; d represents 0 or 1). The liquid crystal alignment agent of claim 2 or 3, wherein the aforementioned polymer (P) is at least one polymer selected from the group consisting of a polyimide precursor obtained by polymerizing a diamine component containing a diamine having a group represented by the aforementioned formula (1) and a tetracarboxylic acid component, and a polyimide obtained by imidizing the polyimide precursor. The liquid crystal alignment agent of claim 6, wherein the tetracarboxylic acid component comprises tetracarboxylic dianhydride represented by the following formula (3);

X represents any structure selected from the following (x-1) to (x-13);

(wherein, ^R1 to ^R4 independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring; ^R5 and ^R6 independently represent a hydrogen atom or a methyl group; j and k independently represent 0 or 1; _A1 and _A2 independently represent a single bond, an ether group, a carbonyl group, an ester group, a phenylene group, a sulfonyl group or an amide group; *1 represents the bonding site of the anhydride group on one side, and *2 represents the bonding site of the anhydride group on the other side). In the liquid crystal alignment agent of claim 2 or 3, the diamine having a group represented by the aforementioned formula (1) accounts for 10 to 80 mol% of the total diamine component (100 mol%). A liquid crystal alignment agent as claimed in any one of claims 1 to 3, wherein the content of the aforementioned polymer (P) is 1 to 10% by mass relative to the total mass of the liquid crystal alignment agent. A liquid crystal alignment film, characterized in that it is formed using a liquid crystal alignment agent as described in any one of claims 1 to 9. A liquid crystal display element characterized by having a liquid crystal alignment film as claimed in claim 10. A method for manufacturing a liquid crystal display element, wherein a liquid crystal alignment agent as described in any one of claims 1 to 9 is applied on a pair of substrates having a conductive film to form a coating film, and the coating films are arranged oppositely with a layer of liquid crystal molecules interposed therebetween to form a liquid crystal cell, and light is irradiated on the liquid crystal cell while a voltage is applied between the conductive films of the pair of substrates. A diamine represented by the following formula (2-1) or (2-2);

(The definitions of each symbol are the same as those in claim 3). A polymer obtained from a diamine component comprising at least one diamine as defined in claim 13. The polymer of claim 14 is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor.