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

Abstract

The invention relates to a liquid crystal aligning agent, a liquid crystal alignment film and a liquid crystal display element using the same. Provided is a liquid crystal aligning agent with which it is possible to obtain a liquid crystal alignment film having both good liquid crystal alignment properties and charge accumulation mitigation characteristics. The liquid crystal aligning agent is characterized by containing at least one polymer (P1) selected from the group consisting of a terminal-terminated first polyimide precursor and an imidized polymer thereof, said first polyimide precursor being obtained by subjecting a diamine component and a tetracarboxylic acid component to a polymerization reaction and reacting with a terminal-blocking agent. The diamine component contains at least one type of diamine selected from the group consisting of diamines containing a partial skeleton represented by formulae (ND-1) to (ND-4) and diamines represented by (ND-5). R1, R21 and R22 each independently represent a hydrogen atom or a methyl group, and R51 and R52 each independently represent a hydrogen atom or a methyl group. And Sp3 and Sp4 each represents a divalent organic group. And A5 represents a single bond or a divalent organic group. # imgabs0 #

Description

[0001] This application is a divisional application of a Chinese patent application filed on November 12, 2019, with application number 201980075282.2 and invention name “Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element using the same”. Technical Field

[0002] The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element using the same. Background Art

[0003] At present, the liquid crystal alignment film used in the liquid crystal display element is mostly a polyimide film. The liquid crystal alignment film of the polyimide film is made by the following method: a solution of a polyamic acid as a precursor of a polyimide or a solution of a solvent-soluble polyimide is applied to a substrate and calcined to obtain a film subjected to an orientation treatment such as a brushing treatment. The polyamic acid and the solvent-soluble polyimide are usually manufactured by a polycondensation reaction of a tetracarboxylic acid derivative such as a tetracarboxylic dianhydride and a diamine compound.

[0004] In order to improve the liquid crystal orientation of the liquid crystal alignment film obtained from polyamic acid or polyimide and improve the characteristic of eliminating the afterimage generated by the application of voltage, it has been proposed to cap the terminals of polyamic acid or polyimide.

[0005] For example, Patent Document 1 states that in order to shorten the afterimage elimination time in a liquid crystal display element, the following liquid crystal aligning agent is used, characterized in that it contains an end-capped polymer (1) selected from end-capped polyamic acids and the like and an end-uncapped polymer (2) selected from end-uncapped polyamic acids and the like, and the proportion of the end-capped polymer (1) in the liquid crystal aligning agent in the total polymer is 5 to 60 weight %.

[0006] Patent Document 2 discloses that a varnish for a photo-alignment film containing a first polyamic acid compound having a terminal skeleton without a primary amino group is used in order to prevent DC image sticking from occurring in a liquid crystal display element.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 4336922

[0010] Patent Document 2: Japanese Patent Application Publication No. 2017-90781 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] In recent years, the performance of liquid crystal display elements has been improved, the area has been increased, and the power saving of display devices has been promoted. In addition, liquid crystal display elements are used in various environments, and the characteristics required of liquid crystal alignment films have become stricter. In particular, with the advancement of the use of liquid crystal display elements, the problem of charge accumulation in the liquid crystal alignment film and the difficulty in ensuring good liquid crystal orientation have become prominent.

[0013] If the charge is accumulated in the liquid crystal alignment film, even a short-time drive is likely to produce residual images. In addition, if good liquid crystal orientation cannot be ensured, light leakage and poor orientation become likely to occur. Therefore, although there is a strong demand for good charge accumulation mitigation characteristics and liquid crystal orientation, there is a situation in which the requirements of both cannot be fully met in the previously proposed technologies.

[0014] This invention was made in view of the above-mentioned situation, and an object of this invention is to provide the liquid crystal aligning agent which can obtain the liquid crystal aligning film which has both favorable liquid crystal orientation and charge accumulation relaxation property.

[0015] Solutions for solving problems

[0016] The present inventors have conducted intensive studies and found that a liquid crystal aligning agent containing a specific polyimide polymer having its terminals blocked using a specific diamine can achieve the above-mentioned object.

[0017] The present invention is based on this knowledge, and its technical means include a liquid crystal aligning agent having the following gist.

[0018] A liquid crystal aligning agent, characterized in that it contains at least one polymer (P1) selected from the group consisting of a first polyimide precursor and an imidized polymer thereof, the end of which is obtained by polymerizing a diamine component and a tetracarboxylic acid component and reacting with a terminal capping agent, wherein the diamine component contains at least one diamine selected from the group consisting of a diamine containing a partial skeleton represented by any of the following formulas (ND-1) to (ND-4) and a diamine represented by (ND-5).

[0019]

[0020] R 1 , R 21 , R 22 Each independently represents a hydrogen atom or a methyl group, R 51 , R 52 Each independently represents a hydrogen atom or a methyl group. p3 , S p4 Each independently represents a divalent organic group. 5 It represents a single bond or a divalent organic group.

[0021] Effects of the Invention

[0022] The liquid crystal aligning agent of this invention can obtain the liquid crystal aligning film which has both favorable liquid crystal orientation and charge accumulation relaxation characteristic. DETAILED DESCRIPTION

[0023] <Polymer (P1)>

[0024] The liquid crystal aligning agent of the present invention contains at least one polymer (P1) selected from the group consisting of a first polyimide precursor and an imidized polymer thereof, the end of which is obtained by polymerizing a diamine component and a tetracarboxylic acid component and reacting with a terminal capping agent, wherein the diamine component contains at least one diamine selected from the group consisting of a diamine having a partial skeleton represented by any of the above formulas (ND-1) to (ND-4) and a diamine represented by (ND-5).

[0025] Hereinafter, each component serving as a raw material of the polymer (P1) will be described.

[0026] (Specific diamine)

[0027] The specific diamine is at least one diamine selected from the group consisting of diamines having partial skeletons represented by the following formulae (ND-1) to (ND-4) and diamines represented by any of (ND-5).

[0028]

[0029] In the above formula, R 1 , R 21 , R 22 Each independently represents a hydrogen atom or a methyl group. 51 , R 52 Each independently represents a hydrogen atom or a methyl group. p3 , S p4 A represents a divalent organic group. 5 It represents a single bond or a divalent organic group.

[0030] As S p3 , S p4 Preferred examples of the above-mentioned divalent organic group include, for example, phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a -CH 2 - a group substituted by a group selected from -O-, -CO-, -CO-O-, -O-CO-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group), pyrrolidine, piperidine and piperazine.

[0031] As the above S p3, S p4 Examples of the divalent chain hydrocarbon group include ethylene, propanediyl, butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonanediyl, and decanediyl.

[0032] As A 5 Preferred examples of the above-mentioned divalent organic group include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or a -CH 2 - a group substituted by -O-, -CO-, -CO-O-, -O-CO-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), etc.

[0033] As the above A 5 Specific examples of the divalent chain hydrocarbon group in include, in addition to the methylene group, the above-mentioned Sp 3 、Sp 4 The divalent chain hydrocarbon group exemplified in .

[0034] Preferred examples of the diamine having a partial skeleton represented by the formula (ND-1) include the following formula (ND-1-1) or (ND-1-2).

[0035]

[0036] In the above formula, R 1 , R 2 represents a hydrogen atom or a methyl group. 11 , R 22 Each independently represents a single bond, or *1-R 3 -Ph-*2.R 3 represents a single bond, selected from -O-, -COO-, -OCO-, -(CH 2 ) l -、-O(CH 2 ) m O-, -CONH-, and -NHCO- are divalent organic groups (l, m represent integers of 1 to 5). It should be noted that *1 represents a site bonded to a benzene ring in formula (ND-1-1) or (ND-1-2), and *2 represents a site bonded to an amino group in formula (ND-1-1) or (ND-1-2). Ph represents a phenylene group. n represents 1 to 3.

[0037] In the above formulas (ND-1-1) and (ND-1-2), the substitution position of the pyrrole ring is preferably the 2-position and the 5-position from the viewpoint of easy synthesis.

[0038] Specific examples of the diamine represented by the above formula (ND-1-1) and (ND-1-2) include diamines represented by any of the following formulas (n1-1) to (n1-14).

[0039]

[0040] As an example of the diamine which has a partial skeleton represented by Formula (ND-2), the diamine represented by the following formula (ND-2-1) - (ND-2-3) is mentioned.

[0041]

[0042] In the above formula, for R 21 , R 22 In particular, including preferred specific examples, each of the above formula (ND-2) and R 21 , R 22 Same meaning. 24 represents a single bond or the structure of the following formula (Ar), and n represents an integer of 1 to 3. * represents a connecting bond. Furthermore, any hydrogen atom of the benzene ring may be substituted by a monovalent organic group such as an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom).

[0043]

[0044] In the above formula (Ar), R 5 represents a single bond, selected from -O-, -COO-, -OCO-, -(CH 2 ) l -、-O(CH 2 ) m O-, -CONR-, and -NRCO- are divalent organic groups, and k is an integer of 1 to 5. It should be noted that R represents hydrogen or a monovalent organic group, and l and m represent integers of 1 to 5. *1 and *2 represent a connecting bond, and * 1 It bonds to the benzene ring in the formula (ND-2-1) to the formula (ND-2-3).

[0045] Examples of the monovalent organic group in R of the above formula (Ar) include alkyl groups having 1 to 3 carbon atoms.

[0046] Preferred specific examples of the diamines represented by the above formulae (ND-2-1) to (ND-2-3) include diamines represented by the following formulae (n2-1) to (n2-6).

[0047]

[0048] Specific examples of the diamine having a partial skeleton represented by the above formula (ND-3) or (ND-4) include diamines represented by the following formula (ND-3-1) or (ND-4-1).

[0049]

[0050] Preferred specific examples of the diamine represented by the above formula (ND-3-1) include diamines represented by the following formulas (n3-1) to (n3-7).

[0051]

[0052] Preferred specific examples of the diamine represented by the above formula (ND-4-1) include diamines represented by the following formulas (n4-1) to (n4-6).

[0053]

[0054] Preferred specific examples of the diamine represented by the above formula (ND-5) include diamines represented by the following formulas (n5-1) to (n5-8).

[0055]

[0056] The content of the specific diamine is preferably 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 50 mol% or more, based on the entire diamine component.

[0057] The specific diamine can be used alone or in combination depending on the solubility of the polymer (P1) in a solvent, the coating properties of a liquid crystal aligning agent, the orientation of liquid crystals when formed into a liquid crystal aligning film, the voltage holding ratio, the charge storage and other properties.

[0058] As a diamine component for obtaining the polymer (P1), a diamine other than the above-mentioned specific diamine (hereinafter also referred to as other diamine) may be contained. As other diamines, diamines represented by the following general formula (2) can be mentioned.

[0059]

[0060] In the above formula (2), A 1 and A 2 Each is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. 1 and A 2 Preferably, a hydrogen atom or a methyl group is used. 1 The structure is as follows: Formula (Y-1) to Formula (Y-68).

[0061]

[0062]

[0063]

[0064]

[0065] (Boc in the above formula represents a tert-butoxycarbonyl group. * represents a connecting bond.)

[0066] In addition, as other diamines, diamines having a thiophene or furan structure described in International Publication No. WO2018 / 092759 can be cited, preferably a diamine represented by the following formula (sf); 2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, diaminoorganosiloxane such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, aliphatic diamines such as meta-xylylenediamine, alicyclic diamines such as 4,4-methylenebis(cyclohexylamine), etc. Other diamines can also be used alone or in combination of two or more.

[0067]

[0068] In the above formula (sf), Y 1 represents a sulfur atom or an oxygen atom, R 2 Each independently represents a single bond or *1-R 5 -Ph-*2, R 5 represents a single bond, selected from -O-, -COO-, -OCO-, -(CH 2 ) l -、-O(CH 2 ) m O-, -CONH-, and -NHCO- are divalent organic groups (l and m are integers of 1 to 5.) It should be noted that *1 represents the site bonded to the benzene ring in formula (sf), and *2 represents the site bonded to the amino group in formula (sf). Ph represents a phenylene group. n is 1 to 3.)

[0069] (Tetracarboxylic acid component)

[0070] As the tetracarboxylic acid component for obtaining the polymer (P1), tetracarboxylic dianhydride or a derivative thereof (tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide) represented by the following formula (1) can be used (these are collectively referred to as the first tetracarboxylic acid component).

[0071]

[0072] In the above formula, X represents a tetravalent organic group. Examples thereof include at least one selected from the group consisting of the following formulae (X-1) to (X-14).

[0073]

[0074] (x and y each independently represent a single bond, methylene, ethylene, propylene, ether (-O-), carbonyl (-CO-), ester (-COO-), phenylene, sulfonyl (-SO 2 -) or amide (-CONH-). 1 ~Z 4 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group. j and k each independently represent an integer of 0 or 1. m represents an integer of 0 to 5. * represents a connecting bond. )

[0075] Preferred examples of the above formula (X-1) include structures represented by the following formulae (X1-1) to (X1-4).

[0076]

[0077] Preferred examples of the above formula (X-13) include the following formulas (X13-1) to (X13-4).

[0078]

[0079] The content of the first tetracarboxylic acid component is preferably 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 50 mol% or more, based on the total tetracarboxylic acid components.

[0080] The first tetracarboxylic acid component can be used alone or in combination depending on properties such as solubility of the polymer (P1) in a solvent, coating properties of a liquid crystal aligning agent, alignment of liquid crystals when formed into a liquid crystal aligning film, voltage retention, and charge storage.

[0081] The tetracarboxylic acid component for obtaining the polymer (P1) of the present invention may be other tetracarboxylic acid components other than the first tetracarboxylic acid component. Other tetracarboxylic acid components include tetracarboxylic dianhydride, tetracarboxylic acid dihalide derived from the tetracarboxylic dianhydride, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide described below.

[0082] Specific examples thereof include 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)phthalic anhydride, bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride, bis(3,4-dicarboxyphenyl)diphenylsilane dianhydride, and 2,6-bis(3,4-dicarboxyphenyl)pyridine dianhydride.

[0083] Other tetracarboxylic acid components may be used alone or in combination of two or more.

[0084] (Terminal Capping Agent)

[0085] In the present invention, the terminal capping agent refers to a compound that can react with unreacted acid terminals and / or amine terminals of a polyimide precursor or an imidized polymer thereof to cap them.

[0086] The end-capping agent is not particularly limited as long as it is a compound that can cap the acid end and / or the amine end, and is preferably a monoamine or an acid anhydride. The monoamine can cap the acid end of the polyimide precursor or its imidized polymer, and the acid anhydride can cap the amine end of the polyimide precursor or its imidized polymer.

[0087] Preferred examples of the monoamine include aniline, 2-aminophenol, 3-aminophenol, 2-amino-m-cresol, 2-amino-p-cresol, 3-amino-o-cresol, 4-amino-o-cresol, 4-amino-m-cresol, 5-amino-o-cresol, 6-amino-m-cresol, 4-amino-2,3-xylenol, 4-amino-3,5-xylenol, 6-amino-2,4-xylenol, 2-amino-4-ethylphenol, 3-amino-4-ethylphenol, and 2-amino-4-tert-butylbenzene. Phenol, 2-amino-4-phenylphenol, 4-amino-2,6-diphenylphenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, 2-amino-m-toluic acid, 3-amino-o-toluic acid, 3-amino-p-toluic acid, 4-amino-m-toluic acid, 6-amino-o-toluic acid, 6-amino-m-toluic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid, 4-aminotoluene-3-sulfonic acid, etc. Two or more of these may be used.

[0088] The acid anhydride preferably has an acid anhydride of a cyclic structure or an acid anhydride having a crosslinking group. Examples of the acid anhydride include phthalic anhydride, maleic anhydride, nadic anhydride, cyclohexane dicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, and compounds shown in the following formulas (m-1) to (m-6). Two or more of these may be used.

[0089]

[0090] <Polymer (P2)>

[0091] The liquid crystal aligning agent of the present invention may contain at least one polymer (P2) selected from the group consisting of a second polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component and an imidized polymer thereof, while containing a polymer (P1). In this case, for example, the polymer (P1) may have a function of excellent charge accumulation mitigation characteristics, and the polymer (P2) may have a function of excellent liquid crystal orientation, which is preferred in this respect.

[0092] For the polyimide precursor of polymer (P2) or its imidized polymer, the terminal may be capped, in which case, the diamine component of polymer (P2) includes diamines other than the above-mentioned specific diamines. If a specific example is given, in addition to other diamines exemplified in polymer (P1), in order to vertically align the liquid crystal, oriented diamines such as the diamines described in International Publication WO2018-159733 and the specific diamines (1) described in International Publication WO2016-104365 can also be used, and in order to improve the response speed of the liquid crystal, the specific diamines (4) described in International Publication WO2016-104365 and the diamines with polymerization initiation function described in Japanese Patent Application No. 2018-081225 can also be used.

[0093] When the terminal of the polymer (P2) is not capped, as the diamine component for obtaining the polymer (P2), in addition to the diamines exemplified above, the diamine component for obtaining the polymer (P1) can be used.

[0094] The diamine component for obtaining the polymer (P2) may contain at least one diamine selected from the following formula (3), formula (4), and formula (5) from the viewpoint of improving the liquid crystal orientation.

[0095]

[0096] In the above formula, A 1 , A 4 Each independently represents a single bond, a divalent organic group, A 2 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphoric acid group, or a monovalent organic group having 1 to 20 carbon atoms, and A 3 represents a divalent organic group. a is an integer of 1 to 4, and when a is 2 or more, A 2 The structures of are optionally the same or different. b and c are each independently an integer of 1 or 2. d is an integer of 0 or 1.

[0097] As the above A 1 , A 4 The divalent organic group in the formula (a) represents a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a -CH 2- is selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR 1 -CO-NR 2 -(R 1 , R 2 Each independently represents a hydrogen atom or a methyl group. ), -NR- (R represents a methyl group), pyrrolidine, piperidine, and a group (h1) formed by replacing a group in piperazine. It should be noted that part or all of the hydrogen atoms in the above-mentioned chain hydrocarbon group and group (h1) may be replaced by an alkyl group having 1 to 3 carbon atoms such as a methyl group, a fluorine atom, a chlorine atom, or other halogen atom.

[0098] As the above A 3 The divalent organic group in the formula (a) represents a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or a -CH 2 - is selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR 1 -CO-NR 2 -(R 1 , R 2 Each independently represents a hydrogen atom or a methyl group. ), -NR- (R represents a methyl group), pyrrolidine, piperidine, and a group (h2) formed by replacing the group in piperazine. It should be noted that the above A 3 A part or all of the hydrogen atoms in the chain hydrocarbon group and the group (h2) may be substituted with an alkyl group having 1 to 3 carbon atoms such as a methyl group, or a halogen atom such as a fluorine atom or a chlorine atom.

[0099] Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include alkanediyl groups such as methanediyl, ethanediyl, n-propanediyl, isopropanediyl, n-butanediyl, isobutanediyl, sec-butanediyl, and tert-butanediyl.

[0100] Alkenediyl such as ethylenediyl, propylenediyl and butenediyl; Alkynediyl such as ethynediyl, propynediyl and butynediyl; and the like.

[0101] As A 2 The monovalent organic group having 1 to 20 carbon atoms in the above-mentioned A can be exemplified. 3A divalent chain hydrocarbon group having 1 to 20 carbon atoms, a group (h2), or a group in which a part or all of the hydrogen atoms in the divalent chain hydrocarbon group having 1 to 20 carbon atoms and the group (h2) are substituted with an alkyl group having 1 to 3 carbon atoms such as a methyl group, or a halogen atom such as a fluorine atom or a chlorine atom, and a group in which one hydrogen atom is added to the groups exemplified, etc.

[0102] Preferred specific examples of at least one diamine selected from the above formula (3), the following formula (4) and the following formula (5) include at least one diamine selected from the group consisting of the following formulas (DA-3-1), (DA-4-1) to (DA-4-23), and (DA-5-1) to (DA-5-3).

[0103]

[0104]

[0105] From the viewpoint of improving the liquid crystal orientation, the total amount of at least one diamine selected from the above formula (3), formula (4) and formula (5) is preferably 10 mol% or more of the entire diamine component for obtaining the polymer (P2).

[0106] From the viewpoint of improving the functional separation between the polymer (P1) and the polymer (P2), the diamine component for obtaining the polymer (P1) and / or the polymer (P2) preferably contains a diamine represented by the following formula (6).

[0107]

[0108] In the above formula, Y 6 A represents a divalent organic group having a structure represented by the following formula (7). 6 Each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. 6 A hydrogen atom or a methyl group is preferred.

[0109]

[0110] (D is tert-butoxycarbonyl.)

[0111] Examples of the divalent organic group including the structure represented by the above formula (7) include groups represented by the following formula (J-1) or formula (J-2).

[0112]

[0113] In the above formula, R 5 represents a single bond, -(CH 2 ) n-(n is an integer from 1 to 20), or -(CH 2 ) n -Any-CH 2 - are each substituted by -O-, -COO-, -OCO-, -NR-, -NRCO-, -CONR-, -NRCONR-, -NRCOO-, or -OCOO- under non-adjacent conditions. R represents a hydrogen atom or a monovalent organic group. 6 , R 7 Each independently represents -H, -NHD, -N(D) 2 , a group having -NHD, or a group having -N(D) 2 The group R 8 Indicates -NHD, -N(D) 2 , a group having -NHD, or a group having -N(D) 2 D represents a tert-butyloxycarbonyl group. 5 , R 6 and R 7 At least one of the has a tert-butoxycarbonyl group in the group.

[0114] More preferred specific examples of the divalent organic group represented by the above formula (J-1) or (J-2) are divalent organic groups represented by the following formulas (J-1-a) to (J-1-d) and (J-2-1). In addition, Boc represents a tert-butoxycarbonyl group.

[0115]

[0116] As the tetracarboxylic acid component for obtaining the polymer (P2), the tetracarboxylic acid component for obtaining the polymer (P1) can be used. Specifically, from the viewpoint of improving the liquid crystal orientation, the above-mentioned first tetracarboxylic acid component can be used. It is further preferred that the above-mentioned first tetracarboxylic acid component of more than 10 mol% of the overall tetracarboxylic acid component used in the polymer (P2) is preferably used.

[0117] <Method for producing polymer (P1)>

[0118] The polymer (P1) is selected from the group consisting of a first polyimide precursor having its terminal blocked and an imidized polymer thereof, and is obtained by (condensation) polymerization of a diamine component containing at least one diamine selected from specific diamines and a tetracarboxylic acid component, and reacting with a terminal blocking agent.

[0119] Here, the polyimide precursor refers to a polyamic acid or a polyamic acid alkyl ester. In the liquid crystal aligning agent of the present invention, the polymer (P1) is preferably a polyimide precursor having a terminal blocked, and particularly preferably a polyamic acid having a terminal blocked.

[0120] In an embodiment of the present invention, the polymer (P1) is preferably obtained by subjecting a diamine component containing at least one diamine selected from specific diamines to a polymerization reaction with a tetracarboxylic acid component to obtain a polyimide precursor or an imidized polymer thereof, and further reacting the polyimide precursor or the imidized polymer thereof with a terminal capping agent to obtain the polymer (P1).

[0121] The polymer (P1) can also be obtained by supplying a terminal blocking agent when polymerizing a diamine component containing at least one diamine selected from specific diamines and a tetracarboxylic acid component or during polymerization.

[0122] The reaction of the diamine component and the tetracarboxylic acid component is usually carried out in a solvent. The solvent used at this time is not particularly limited as long as it is a solvent in which the generated polyimide precursor will dissolve. Specific examples of the solvent used in the reaction are given below, but are not limited to these examples.

[0123] For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, dimethyl sulfoxide, or 1,3-dimethyl-imidazolidinone can be mentioned. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, etc. can be used.

[0124] These 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-mentioned solvent within the range that the generated polyimide precursor does not precipitate. In addition, the moisture in the solvent becomes the cause of hindering the polymerization reaction and then hydrolyzing the generated polyimide precursor, so the solvent is preferably a dehydrated solvent.

[0125] When the diamine component and the tetracarboxylic acid component are reacted in a solvent, the following methods can be cited: a method in which a solution in which the diamine component is dispersed or dissolved in a solvent is stirred, and the tetracarboxylic acid component is directly added, or dispersed or dissolved in a solvent and added; a method in which the diamine component is added to a solution in which the tetracarboxylic acid component is dispersed or dissolved in a solvent; a method in which the diamine component and the tetracarboxylic acid component are alternately added to the reaction system, and any of these methods can be used. In addition, when a plurality of diamine components or tetracarboxylic acid components are used for the reaction, the reaction can be carried out in a premixed state, the reaction can be carried out separately and sequentially, or the low molecular weight bodies obtained by the separate reactions can be mixed and reacted to form a polymer.

[0126] The temperature for polycondensing the diamine component and the tetracarboxylic acid component can be selected from any temperature of -20 to 150°C, preferably in the range of -5 to 100°C. The reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high to achieve uniform stirring. Therefore, the concentration of the polymer is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the initial stage and a solvent can be added thereafter.

[0127] In the polymerization reaction to obtain the polyimide precursor, the total molar ratio of the tetracarboxylic acid component to the total molar ratio of the diamine component is preferably 0.8 to 1.2. As in a normal polycondensation reaction, the closer this molar ratio is to 1.0, the greater the molecular weight of the generated polyimide precursor.

[0128] The imidized polymer is a polyimide obtained by ring-closing a polyimide precursor. In the polyimide, the ring-closure ratio of the amic acid group (also referred to as the imidization ratio) is not necessarily 100% and can be arbitrarily adjusted according to the application and purpose.

[0129] Examples of a method for imidating a polyimide precursor include thermal imidization in which a solution of a polyimide precursor is directly heated, and catalytic imidization in which a catalyst is added to a solution of a polyimide precursor.

[0130] The temperature when the polyimide precursor is thermally imidized in the solution is preferably 100 to 400° C., more preferably 120 to 250° C., and the method is preferably carried out while removing water generated by the imidization reaction to the outside of the system. The catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to the solution of the polyimide precursor and stirring at -20 to 250° C., preferably 0 to 180° C.

[0131] The amount of the basic catalyst is preferably 0.5 to 30 times, more preferably 2 to 20 times, the amount of the amic acid group, and the amount of the acid anhydride is preferably 1 to 50 times, more preferably 3 to 30 times, the amount of the amic acid group.

[0132] Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it has a basicity that is appropriate for the reaction to proceed.

[0133] As anhydrides, acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. can be cited. When acetic anhydride is used in particular, purification after the reaction is completed becomes easy, so it is preferred. The imidization rate based on catalytic imidization can be controlled by adjusting the catalyst amount, reaction temperature, and reaction time.

[0134] When the generated polyimide precursor or its imidized polymer is recovered from the reaction solution, the reaction solution can be put into a solvent to precipitate it. As the solvent used in the precipitation, methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water, etc. can be cited. The polymer put into the solvent and precipitated can be filtered and recovered, and then dried at room temperature or heated under normal pressure or reduced pressure. In addition, if the operation of redissolving the returned polymer in the solvent and reprecipitating and recovering is repeated 2 to 10 times, the impurities in the polymer can be reduced. As the solvent at this time, for example, alcohols, ketones, hydrocarbons, etc. can be cited. When using 3 or more solvents selected from these, the efficiency of purification is further improved, so it is preferred.

[0135] When the polyimide precursor in the present invention is a polyamic acid alkyl ester, examples of a specific method for producing the polyimide precursor include methods described in paragraphs

[0054] to

[0062] of International Publication No. WO2011-115077.

[0136] Next, in order to cap the acid terminal or amine terminal of the polyimide precursor or its imidized polymer, a terminal capping agent may be added to the polyimide precursor or its imidized polymer to react at any stage during or after the production process.

[0137] The amount of the terminal capping agent used is not particularly limited, but is preferably 0.001 to 0.8 equivalents, more preferably 0.01 to 0.2 equivalents, relative to 1 equivalent of the amino group in the diamine component participating in the polymerization reaction of the polyimide precursor or its imidized polymer.

[0138] Moreover, it is preferably 0.001 to 0.8 equivalents, more preferably 0.01 to 0.2 equivalents, based on 1 equivalent of the carboxyl group (or its derivative structure) in the tetracarboxylic acid component participating in the polymerization reaction of the polyimide precursor or its imidized polymer.

[0139] The reaction temperature when sealing the terminal is preferably -50 to 150° C., more preferably -30 to 100° C. The reaction time is usually 0.1 to 100 hours.

[0140] <Method for producing polymer (P2)>

[0141] The polymer (P2) is selected from the group consisting of a second polyimide precursor and an imidized polymer thereof, and is obtained by reacting a diamine component with a tetracarboxylic acid component. The reaction of the diamine component with the tetracarboxylic acid component is the same as described in the above-mentioned method for producing the polymer (P1).

[0142] When the polymer (P2) is selected from the group consisting of polyimide precursors and imidized polymers thereof whose terminals are blocked, the polyimide precursor or the imidized polymer thereof can be reacted with a terminal blocking agent selected from the following formulas (R-1) to (R-2) at any stage during or after the production, or at both stages.

[0143]

[0144] (R 2 and R 2 ' represents a monovalent organic group. n is an integer of 1 to 2.)

[0145] As R 2 and R 2 Specific examples of ' include methyl, 9-fluorenylmethyl, 2,2,2-trichloroethyl, 2-trimethylsilylethyl, 1,1-dimethylpropargyl, 1-methyl-1-phenylethyl, 1-methyl-1-(4-biphenylyl)ethyl, 1,1-dimethyl-2-haloethyl, 1,1-dimethyl-2-cyanoethyl, tert-butyl, cyclobutyl, 1-methylcyclobutyl, 1-adamantyl, vinyl, allyl, cinnamyl, 8-quinolyl, N-hydroxypiperidinyl, benzyl, p-nitrobenzyl, 3,4-dimethoxy-6-nitrobenzyl, and 2,4-dichlorobenzyl. Among them, from the perspective of the relationship with the sintering temperature in the liquid crystal display element manufacturing process, more preferred are tert-butyl, 2,2,2-trichloroethyl, 2-trimethylsilylethyl, 1,1-dimethylpropargyl, 1-methyl-1-(4-biphenylyl)ethyl, 1,1-dimethyl-2-haloethyl, 1,1-dimethyl-2-cyanoethyl, tert-butyl, cyclobutyl, 1-methylcyclobutyl, vinyl, allyl, cinnamyl, and N-hydroxypiperidinyl, and particularly preferred are 1,1-dimethyl-2-haloethyl, 1,1-dimethyl-2-cyanoethyl and tert-butyl.

[0146] <Liquid Crystal Alignment Agent>

[0147] The liquid crystal aligning agent of this invention contains a polymer (P1) and a polymer (P2) as needed. Content of the polymer (P1) in a liquid crystal aligning agent is preferably 2-10 mass %, more preferably 3-8 mass % in a liquid crystal aligning agent.

[0148] When the liquid crystal aligning agent contains a polymer (P2), the content of the polymer (P1) is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, further preferably 60 parts by mass or more, and most preferably 70 parts by mass or more, relative to 100 parts by mass of the total amount of the polymer (P1) and the polymer (P2).

[0149] The liquid crystal aligning agent of the present invention may also contain other polymers in addition to polymer (P1) and polymer (P2). As polymers other than these, cellulose polymers, acrylic polymers, methacrylic polymers, polystyrene, polyamide, polysiloxane, etc. can also be listed. The content of other polymers other than these is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass relative to a total of 100 parts by mass of polymer (P1) and polymer (P2).

[0150] Moreover, a liquid crystal aligning agent usually contains an organic solvent, and content of the organic solvent is preferably 70-99.9 mass % with respect to the liquid crystal aligning agent. This content can be appropriately changed according to the coating method of the liquid crystal aligning agent and the film thickness of the target liquid crystal aligning film.

[0151] The organic solvent used in the liquid crystal alignment agent is preferably a solvent (also referred to as a good solvent) that dissolves the polymer (P1) and the polymer (P2). For example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, etc. are listed. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide or γ-butyrolactone is preferred.

[0152] The good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass of the whole solvent contained in the liquid crystal aligning agent, more preferably 20 to 90% by mass, particularly preferably 30 to 80% by mass.

[0153] The liquid crystal aligning agent of the present invention can use a solvent (also referred to as a poor solvent) which improves the coating properties and surface smoothness of the liquid crystal aligning film when the liquid crystal aligning agent is applied. Specific examples thereof will be given below.

[0154] For example, diisopropyl ether, diisobutyl ether, diisobutyl carbitol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, 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 monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2 -(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isopentyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), and the like.

[0155] Among them, preferred combinations of solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diethyl Glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, 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 2,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, etc. These poor solvents are preferably 1 to 80% by mass of the total solvent contained in the liquid crystal aligning agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of such solvents can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal aligning agent.

[0156] The liquid crystal alignment agent of the present invention may also contain a dielectric for the purpose of changing the electrical properties of the liquid crystal alignment film, such as the dielectric constant and conductivity; a silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate; a cross-linking compound for the purpose of improving the hardness and density of the film when the liquid crystal alignment film is made; and an imidization accelerator for the purpose of efficiently performing the imidization of the polyimide precursor based on heating when the coating film is fired.

[0157] Examples of compounds that improve the adhesion between the liquid crystal alignment film and the substrate include compounds containing functional silanes and epoxy-containing compounds, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane. 3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilane 9-Triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyl trimethoxysilane, N-benzyl-3-aminopropyl triethoxysilane, N-phenyl-3-aminopropyl trimethoxysilane, N-phenyl-3-aminopropyl triethoxysilane, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether Water glyceryl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N',-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or N,N,N',N',-tetraglycidyl-4,4'-diaminodiphenylmethane, etc.

[0158] Moreover, in order to improve the mechanical strength of a liquid crystal aligning film, the liquid crystal aligning agent of this invention can contain the following additives (CL-1) - (CL-15).

[0159]

[0160] It is preferable that it is 0.1-30 mass parts with respect to 100 mass parts of the polymer components contained in the liquid crystal aligning agent, and it is more preferable that it is 0.5-20 mass parts.

[0161] <Method for producing liquid crystal alignment film>

[0162] The liquid crystal alignment film is obtained as follows: the above-mentioned liquid crystal alignment agent is formed into a coating on the substrate by coating, etc., and preferably dried, and then fired. As a substrate, a substrate with high transparency is preferred, and as its material, glass, ceramics such as silicon nitride, acrylic resin, plastics such as polycarbonate, etc. can be used. As a substrate, if a substrate with an ITO (Indium Tin Oxide) electrode for driving liquid crystal is used, it is preferred from the perspective of simplifying the process. In addition, in a reflective liquid crystal display element, an opaque object such as a silicon wafer can also be used as a substrate on one side, and its electrode can also use a material that reflects light such as aluminum.

[0163] The method of forming a coating on a substrate with a liquid crystal aligning agent may be screen printing, offset printing, flexographic printing, inkjet method, etc. In addition, dipping method, roll coater method, slit coater method, spin coater method, spray method, etc. may be used depending on the purpose.

[0164] After forming a coating of the liquid crystal alignment agent on the substrate, it is preferred that the coating be dried by heating means such as a hot plate, a heat circulation oven, an IR (infrared) oven, etc., at preferably 30 to 120° C., more preferably 50 to 120° C., for preferably 1 minute to 10 minutes, more preferably 1 minute to 5 minutes, to evaporate the solvent.

[0165] When the imide precursor in the polymer is thermally imidized, the coating obtained from the liquid crystal aligning agent is then subjected to a calcination treatment by the same heating means as the above-mentioned drying treatment, preferably at 120 to 250° C., more preferably at 150 to 230° C. The calcination treatment time varies depending on the calcination temperature, but is preferably 5 minutes to 1 hour, more preferably 5 minutes to 40 minutes.

[0166] The thickness of the coating after the calcining treatment is not particularly limited. If it is too thin, the reliability of the liquid crystal display element may decrease, and if it is too thick, the resistance of the obtained liquid crystal alignment film increases. Therefore, it is preferably 5 to 300 nm, more preferably 10 to 200 nm.

[0167] After the calcination treatment, the obtained coating is subjected to an orientation treatment. Examples of the method for the orientation treatment include a brushing method and a photo-orientation method.

[0168] As a specific example of photo-orientation treatment, the surface of the above-mentioned coating is irradiated with radiation polarized in a certain direction. As the radiation, ultraviolet rays or visible light with a wavelength of 100 to 800 nm can be used. Among them, ultraviolet rays with a wavelength of 100 to 400 nm are preferred, and ultraviolet rays with a wavelength of 200 to 400 nm are more preferred. In order to improve the orientation of the liquid crystal, the substrate coated with the liquid crystal orientation film can be heated at 50 to 250°C while irradiating with ultraviolet rays. In addition, the irradiation amount of the above-mentioned radiation is preferably 1 to 10,000 mJ / cm 2 Among them, 100 to 5,000 mJ / cm is preferred. 2 The liquid crystal alignment film produced in this way can make the liquid crystal molecules stably align along a certain direction.

[0169] A high extinction ratio of polarized ultraviolet light is preferred because it can impart higher anisotropy. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10:1 or more, more preferably 20:1 or more.

[0170] The coating film subjected to the alignment treatment may be further subjected to at least one treatment selected from the group consisting of a heat treatment and a contact treatment with a solvent.

[0171] The heat treatment after the orientation treatment can be carried out by the same heating means as the above-mentioned drying treatment and calcining treatment, preferably at 180 to 250°C, more preferably at 180 to 230°C. When the temperature of the heat treatment is carried out within the above-mentioned range, the contrast of the liquid crystal display element obtained by the obtained liquid crystal alignment film can be improved. The time of the heat treatment varies depending on the heating temperature, preferably 5 minutes to 1 hour, more preferably 5 to 40 minutes.

[0172] As a solvent used for the said contact process with a solvent, it will not be specifically limited as long as it is a solvent which dissolves impurities etc. adhering to a liquid crystal alignment film.

[0173] As specific examples, water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, 3-methoxy methyl propionate, 3-ethoxy ethyl propionate, propyl acetate, butyl acetate, cyclohexyl acetate, etc. can be listed. Among them, from the aspect of versatility and safety of the solvent, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferred. Water, 1-methoxy-2-propanol or ethyl lactate are more preferred. These solvents can be one or more than two.

[0174] As the above-mentioned contact treatment, immersion treatment and spray treatment (also referred to as spray treatment) can be listed. The treatment time in these treatments is preferably 10 seconds to 1 hour, and in particular, a method of immersion treatment for 1 to 30 minutes can be listed. In addition, the temperature during the contact treatment can be room temperature or heating, preferably 10 to 80°C, and 20 to 50°C can be listed. During the contact treatment, ultrasonic treatment can be further performed as needed.

[0175] After the above contact treatment, rinsing (also referred to as flushing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or the like, and drying may be performed. At this time, either flushing or drying may be performed, or both may be performed. The drying temperature is preferably 50 to 150° C., and 80 to 120° C. may be mentioned. In addition, the drying time is preferably 10 seconds to 30 minutes, and preferably 1 to 10 minutes.

[0176] After the contact treatment with the solvent, the heat treatment after the alignment treatment may be performed. By adopting such a mode, a liquid crystal alignment film having excellent liquid crystal alignment properties can be obtained.

[0177] <Liquid Crystal Display Element>

[0178] The liquid crystal alignment film of the present invention can be applied to various driving modes such as TN mode, STN mode, IPS mode, FFS mode, VA mode, MVA mode, PSA mode, etc., and is suitable as a liquid crystal alignment film for liquid crystal display elements of lateral electric field modes such as IPS mode and FFS mode, and is particularly useful for liquid crystal display elements of FFS mode. The liquid crystal display element of the present invention is obtained as follows: after obtaining a substrate with a liquid crystal alignment film obtained from the above-mentioned liquid crystal alignment agent, a liquid crystal cell is prepared by a known method, and the element is prepared using the liquid crystal cell.

[0179] As an example of a method for producing a liquid crystal cell, a liquid crystal display element of a passive matrix structure is described as an example. It should be noted that a liquid crystal display element of an active matrix structure in which a switching element such as a TFT is provided in each pixel portion constituting image display may also be used.

[0180] Specifically, transparent glass substrates are prepared, a common electrode is provided on one substrate, and segment electrodes are provided on the other substrate. These electrodes can be, for example, ITO electrodes, and patterned so as to achieve the desired image representation. Next, an insulating film is provided on each substrate in a manner covering the common electrode and the segment electrodes. The insulating film can be, for example, a SiO2 film formed by a sol-gel method. 2 -TiO 2Film. Then, under the above conditions, a liquid crystal alignment film is formed on each substrate, and the other substrate is overlapped on one substrate in a manner that the liquid crystal alignment film surfaces face each other, and the periphery is bonded with a sealant. In order to control the gap between the substrates, it is usually preferred to pre-mix a spacer in the sealant. In addition, it is preferred to pre-spread a spacer for controlling the gap between the substrates in the surface where the sealant is not provided. It is preferred to pre-set an opening portion in a portion of the sealant that can be filled with liquid crystal from the outside.

[0181] Thereafter, by being arranged at the opening of the sealant, the liquid crystal material is injected into the space surrounded by 2 substrates and the sealant. Then, the opening is sealed with an adhesive. The injection can include a vacuum injection method, a method utilizing a capillary phenomenon in the atmosphere, and an ODF (drop injection, One Drop Fill) method. As the liquid crystal material, materials having positive or negative dielectric anisotropy can be used. In the present invention, from the viewpoint of liquid crystal orientation, preferably a liquid crystal having negative dielectric anisotropy can be appropriately used according to the purpose.

[0182] After the liquid crystal material is injected into the liquid crystal cell, a polarizing plate is placed. Specifically, it is preferred that a pair of polarizing plates be attached to the opposite side of the liquid crystal layer of the two substrates.

[0183] Example

[0184] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto. The abbreviations of the compounds and the methods for measuring the properties are as follows.

[0185] NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone

[0186] BCS: Butyl Cellosolve

[0187]

[0188]

[0189] [Viscosity]

[0190] The viscosity was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL, a conical rotor TE-1 (1°34', R24), and a temperature of 25°C.

[0191] [Molecular weight]

[0192] The number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated as polyethylene oxide equivalent values ​​by measuring using a GPC (normal temperature gel permeation chromatography) apparatus.

[0193] GPC apparatus: Shodex (GPC-101), column: Shodex (KD803, KD805 in series), column temperature: 50°C, eluent: N,N-dimethylformamide (containing lithium bromide monohydrate (LiBr·H 2 O) 30mmol / L, phosphoric acid anhydrous crystals (orthophosphoric acid) 30mmol / L, tetrahydrofuran (THF) 10ml / L. ), flow rate: 1.0ml / min

[0194] Standard samples for preparing the calibration curve: TSK standard polyethylene oxide manufactured by Tosoh Corporation (weight average molecular weight (Mw) of about 900,000, 150,000, 100,000, 30,000), and polyethylene glycol manufactured by Polymer Laboratories Ltd. (peak top molecular weight (Mp) of about 12,000, 4,000, 1,000). In order to avoid peak overlap, two samples, a sample in which four types of 900,000, 100,000, 12,000, and 1,000 were mixed, and a sample in which three types of 150,000, 30,000, and 4,000 were mixed, were measured separately.

[0195] [Fabrication of Liquid Crystal Cell]

[0196] A liquid crystal cell having a structure of a fringe field switching (FFS) mode liquid crystal display element was produced.

[0197] First, prepare a substrate with electrodes. The substrate is a glass substrate with a size of 30mm×50mm and a thickness of 0.7mm. An ITO electrode with a solid pattern is formed on the substrate as the first layer constituting the counter electrode. A SiN (silicon nitride) film formed by a CVD method is formed as the second layer. The thickness of the second layer SiN film is 500nm, and it acts as an interlayer insulating film. On the second layer SiN film, as the third layer, a comb-shaped pixel electrode formed by patterning the ITO film is arranged to form two pixels, the first pixel and the second pixel. The size of each pixel is 10mm in the vertical direction and about 5mm in the horizontal direction. At this time, the first layer counter electrode and the third layer pixel electrode are electrically insulated by the action of the second layer SiN film.

[0198] The pixel electrode of the third layer has a comb-like shape formed by arranging a plurality of electrode elements whose central portion is bent into a "く" shape with an internal angle of 160°. The width of each electrode element in the short side direction is 3μm, and the interval between the electrode elements is 6μm. The pixel electrode forming each pixel is composed of a plurality of electrode elements whose central portion is bent in a "く" shape. Therefore, the shape of each pixel is not a rectangular shape, but a thick "く"-like shape bent in the central portion like the electrode elements. Moreover, each pixel is divided into upper and lower parts with the bent portion in the center as the boundary, with a first area on the upper side of the bent portion and a second area on the lower side.

[0199] Next, the liquid crystal alignment agent was filtered with a filter having a pore size of 1.0 μm, and then applied by spin coating on the prepared substrate with electrodes and a glass substrate with a columnar spacer having a height of 4 μm formed on the back with an ITO film. After drying on a hot plate at 80°C for 2 minutes, it was calcined in a hot air circulation oven at 230°C for 30 minutes to form a coating with a film thickness of 100 nm. The coating surface was irradiated with ultraviolet rays with a wavelength of 254 nm with a linear polarization having an extinction ratio of 10:1 or more by means of a polarizing plate. The substrate was further calcined in a hot air circulation oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film. It should be noted that the liquid crystal alignment film formed on the substrate with electrodes is oriented in a manner that the direction of dividing the inner angle of the pixel bending portion into equal parts is orthogonal to the orientation direction of the liquid crystal, and the liquid crystal alignment film formed on the second glass substrate is oriented in a manner that the orientation direction of the liquid crystal on the first substrate is consistent with the orientation direction of the liquid crystal on the second substrate when the liquid crystal unit is made. The above two substrates were set as a set, a sealant was printed on the substrate, and another substrate was laminated in a manner that the liquid crystal alignment film faces were opposite and the alignment direction was 0°, and then the sealant was cured to produce an empty cell. Liquid crystal MLC-3019 (Merck) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS driven liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110°C for 1 hour, left overnight, and used for each evaluation.

[0200] [Evaluation of image sticking caused by long-term AC drive]

[0201] A liquid crystal cell having the same structure as that used in the above-mentioned image sticking evaluation was prepared.

[0202] Using this liquid crystal cell, an AC voltage of ±5 V was applied at a frequency of 60 Hz for 120 hours in a constant temperature environment of 60° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left at room temperature for one day.

[0203] After placement, a liquid crystal unit is set between two polarizing plates arranged in a manner that the polarization axes are orthogonal, and the backlight is turned on without applying voltage. The configuration angle of the liquid crystal unit is adjusted to minimize the brightness of the transmitted light. Then, the rotation angle when the liquid crystal unit is rotated from the angle at which the second area of ​​the first pixel becomes the darkest to the angle at which the first area becomes the darkest is calculated as angle Δ. Similarly, in the second pixel, the second area is compared with the first area and the same angle Δ is calculated.

[0204] <Synthesis Example 1> (Polyamic acid with uncapped ends)

[0205] In a 3L four-necked flask equipped with a stirrer and a nitrogen inlet tube, 17.30 g (159.98 mmol) of diamine DA-1, 58.63 g (240.0 mmol) of diamine DA-2, 76.89 g (240.0 mmol) of diamine DA-3, and 54.63 g (159.99 mmol) of diamine DA-4 were weighed, and 2458.13 g of NMP was added, and stirred while nitrogen was supplied to dissolve. While stirring the diamine solution, 171.27 g (764.02 mmol) of tetracarboxylic dianhydride TA-1 was added, and NMP was further added so that the solid content concentration became 12% by mass, and stirred at 40° C. for 20 hours to obtain a polyamic acid solution (PAA-1).

[0206] The viscosity of the polyamic acid solution was 426 mPa·s. The molecular weights of the polyamic acid were Mn=12,380 and Mw=33,250.

[0207] <Synthesis Example 2> (Polyamic acid with uncapped ends)

[0208] In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 5.29 g (26.98 mmol) of tetracarboxylic dianhydride TA-2 was weighed, 80.13 g of NMP was added, and the mixture was stirred and dissolved while nitrogen was supplied. While stirring the carboxylic dianhydride solution, 2.96 g (14.86 mmol) of diamine DA-5, 2.28 g (5.41 mmol) of diamine DA-6, and 1.61 g (5.43 mmol) of diamine DA-7 were added, and NMP was further added so that the solid content concentration became 12% by mass, and the mixture was stirred at 40° C. for 20 hours to obtain a polyamic acid solution (PAA-2).

[0209] The viscosity of the polyamic acid solution was 437 mPa·s. The molecular weights of the polyamic acid were Mn=16,331 and Mw=35,853.

[0210] <Synthesis Example 3> (Polyamic acid whose terminal is not blocked)

[0211] In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 2.98 g (14.96 mmol) of diamine DA-5, 2.11 g (5.00 mmol) of diamine DA-6, and 1.49 g (4.99 mmol) of diamine DA-7 were weighed, and 74.16 g of NMP was added, and stirred while nitrogen was supplied to dissolve. 4.64 g (23.66 mmol) of tetracarboxylic dianhydride TA-2 was added while stirring the diamine solution, and NMP was further added so that the solid content concentration became 12% by mass, and stirred at 40° C. for 20 hours to obtain a polyamic acid solution (PAA-3).

[0212] The viscosity of the polyamic acid solution was 443 mPa·s. The molecular weights of the polyamic acid were Mn=12,155 and Mw=35,725.

[0213] [Table 1]

[0214]

[0215] <Synthesis Example 4> (Terminal-capped polyamic acid)

[0216] 20.0 g of polyamic acid (PAA-2) was weighed in a 50 mL conical flask, and 0.035 g (0.38 mmol, 0.04 equivalents relative to 1 equivalent of amino groups in the diamine participating in the polymerization reaction) of terminal capping agent MA-1 was added, and stirred at 40° C. for 20 hours to obtain a polyamic acid solution (PAA-4). The acid terminals in the polyamic acid solution (PAA-4) were capped.

[0217] <Synthesis Examples 5 to 8> (Terminal-capped polyamic acid)

[0218] Using the polyamic acid solutions and terminal capping agents shown in Table 2 below, the same procedures as in Synthesis Example 4 were carried out to obtain polyamic acid solutions (PAA-5) to (PAA-8) shown in Table 2 below. The acid terminals in the polyamic acid solution (PAA-5) were capped, and the amine terminals in the polyamic acid solutions (PAA-6) to (PAA-8) were capped.

[0219] [Table 2]

[0220]

[0221] (Liquid crystal aligning agent having a mixing ratio (mass ratio) of component 1:component 2 of 5:5)

[0222] <Example 1>

[0223] 2.29 g of a 12% by mass polyamic acid solution (PAA-4) (component 1) and 2.29 g of a 12% by mass polyamic acid solution (PAA-1) (component 2) were taken into a 50 ml conical flask, 2.41 g of NMP and 3.00 g of BCS were added, and mixed at 25° C. for 2 hours to obtain a liquid crystal aligning agent (A1). No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed to be a uniform solution.

[0224] <Examples 4, 7, 10, 13>

[0225] Liquid crystal aligning agents (A4), (A7), (A10), and (A13) were obtained in the same manner as in Example 1, except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4).

[0226] <Comparative Examples 1 and 4>

[0227] Liquid crystal aligning agents (B1) and (B4) were obtained in the same manner as in Example 1, except that polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4).

[0228] (Liquid crystal aligning agent having a mixing ratio (mass ratio) of component 1:component 2 of 6:4)

[0229] <Example 2>

[0230] 2.75 g of a 12% by mass polyamic acid solution (PAA-4) (component 1) and 1.83 g of a 12% by mass polyamic acid solution (PAA-1) (component 2) were taken into a 50 ml conical flask, 2.41 g of NMP and 3.00 g of BCS were added, and mixed at 25° C. for 2 hours to obtain a liquid crystal aligning agent (A2). No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed to be a uniform solution.

[0231] <Examples 5, 8, 11, 14>

[0232] Liquid crystal aligning agents (A5), (A8), (A11), and (A14) were obtained in the same manner as in Example 2, except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4).

[0233] <Comparative Examples 2 and 5>

[0234] Liquid crystal aligning agents (B2) and (B5) were obtained in the same manner as in Example 2, except that the polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4).

[0235] (Liquid crystal aligning agent having a mixing ratio (mass ratio) of component 1:component 2 of 7:3)

[0236] <Example 3>

[0237] 3.21 g of a 12% by mass polyamic acid solution (PAA-4) (component 1) and 1.38 g of a 12% by mass polyamic acid solution (PAA-1) (component 2) were taken into a 50 ml conical flask, 2.41 g of NMP and 3.00 g of BCS were added, and mixed at 25° C. for 2 hours to obtain a liquid crystal aligning agent (A3). No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed to be a uniform solution.

[0238] <Examples 6, 9, 12, 15>

[0239] Liquid crystal aligning agents (A6), (A9), (A12), and (A15) were obtained in the same manner as in Example 3, except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4).

[0240] <Comparative Examples 3 and 6>

[0241] Liquid crystal aligning agents (B3) and (B6) were obtained in the same manner as in Example 3, except that the polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4).

[0242] [Table 3]

[0243]

[0244] (Results of image sticking evaluation caused by long-term AC drive)

[0245] <Example 16>

[0246] The liquid crystal aligning agent (A1) obtained in Example 1 was filtered with a filter having a pore size of 1.0 μm, and then applied by spin coating on the prepared substrate with electrodes and a glass substrate with a columnar spacer having a height of 4 μm formed on the back of an ITO film. After drying on a hot plate at 80°C for 2 minutes, it was calcined in a hot air circulation oven at 230°C for 30 minutes to form a coating film with a thickness of 100 nm. The coating surface was exposed to a polarizing plate at 0.3 J / cm 2 The substrate was irradiated with ultraviolet rays having a wavelength of 254 nm and a linear polarization with an extinction ratio of 26:1. The substrate was baked in a hot air circulation oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film.

[0247] The above two substrates were set as a group, and a sealant was printed on the substrate. After another substrate was attached in a manner that the liquid crystal alignment film faces were opposite and the alignment direction was 0°, the sealant was cured to make an empty unit. Liquid crystal MLC-3019 (Merck) was injected into the empty unit by a reduced pressure injection method, and the injection port was sealed to obtain an FFS driven liquid crystal unit. Thereafter, the obtained liquid crystal unit was heated at 110°C for 1 hour, left overnight, and the residual image caused by long-term AC drive was evaluated. The value of the angle Δ of the liquid crystal unit after long-term AC drive was 0.26 degrees.

[0248] <Examples 17 to 21, Comparative Examples 7 to 9>

[0249] Instead of the liquid crystal aligning agent (A1), the liquid crystal aligning agents A2 to A5 and B1 to B3 shown in Table 3 were used, respectively. The FFS-driven liquid crystal cells were prepared in the same manner as in Example 16, and the image sticking evaluation caused by long-term AC driving was performed. The values ​​of the angle Δ of the liquid crystal cells after each long-term AC driving are shown in Table 4.

[0250] [Table 4]

[0251]

[0252] <Examples 22 to 30, Comparative Examples 10 to 12>

[0253] Instead of the liquid crystal aligning agent (A1), the liquid crystal aligning agents A7 to A15 and B4 to B6 shown in Table 4 were used, respectively. The FFS-driven liquid crystal cells were prepared in the same manner as in Example 16, and the image sticking evaluation caused by long-term AC driving was performed. The values ​​of the angle Δ of each liquid crystal cell after long-term AC driving are shown in Table 5.

[0254] [Table 5]

[0255]

[0256] In Table 4, Comparative Example 7 is compared with Examples 16 and 19, Comparative Example 8 is compared with Examples 17 and 20, and Comparative Example 9 is compared with Examples 18 and 21. It can be seen that when the polyamic acid modified with a monoamine at the acid end is mixed, the afterimage caused by AC driving tends to decrease.

[0257] In addition, in Table 5, Comparative Example 10 is compared with Examples 22, 25, and 28, Comparative Example 11 is compared with Examples 23, 26, and 29, and Comparative Example 12 is compared with Examples 24, 26, and 30, respectively, and it is confirmed that when the polyamic acid formed by modifying the amine end with carboxylic anhydride is mixed, the afterimage caused by long-term AC drive tends to decrease.

[0258] When the difference between the Δ values ​​of the comparative example and the example with the same mixing ratio is taken, there is a tendency that the difference between the Δ value of the comparative example and the Δ value of the example becomes larger as the mixing ratio of the component 1 increases. This shows that the present method is particularly useful when the ratio of the component 1 is to be increased.

[0259] Industrial Applicability

[0260] The liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention has a high yield rate in the manufacture of liquid crystal panels, and can reduce the image sticking caused by AC driving in the liquid crystal display elements of IPS driving mode and FFS driving mode, and can obtain the liquid crystal display elements of IPS driving mode and FFS driving mode with excellent image sticking characteristics. Therefore, it is used in liquid crystal display elements requiring particularly high display quality.

[0261] It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-214005 filed on November 14, 2018 are cited herein and incorporated as a disclosure of the specification of the present invention.

Claims

1. A liquid crystal alignment agent, characterized in that: The present invention comprises at least one polymer (P1) selected from the group consisting of a first polyimide precursor and an imidized polymer thereof, the first polyimide precursor being obtained by polymerizing a diamine component and a tetracarboxylic acid component and reacting with a terminal capping agent, wherein the diamine component comprises at least one diamine selected from the group consisting of a diamine having a partial skeleton represented by the following formula (ND-2) and a diamine represented by the following formula (ND-5), R 21 , R 22 each independently represents a hydrogen atom or a methyl group, R 51 , R 52 Each independently represents a hydrogen atom, and A5 represents a single bond or a divalent organic group.

2. The liquid crystal alignment agent according to claim 1, wherein The diamine component includes the diamine represented by (ND-5).

3. The liquid crystal aligning agent according to claim 1 or 2, wherein: The tetracarboxylic acid component includes tetracarboxylic dianhydride represented by the following formula (1): X represents a tetravalent organic group selected from the following formulae (X-1) to (X-14), x and y each independently represent a single bond, methylene, ethylene, propylene, ether, carbonyl, ester, phenylene, sulfonyl or amide, and Z 1 ~Z 4 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group, j and k are integers of 0 or 1, m is an integer of 0 to 5, and * represents a connecting bond.

4. The liquid crystal alignment agent according to claim 3, wherein: The content of the tetracarboxylic dianhydride represented by the formula (1) is 5 mol% or more of the entire tetracarboxylic acid component. 5 . The liquid crystal aligning agent according to claim 1 , wherein The content of at least one diamine selected from the group consisting of a diamine containing a partial skeleton represented by the above formula (ND-2) and a diamine represented by the above formula (ND-5) is 5 mol% or more of the entire diamine component.

6. The liquid crystal aligning agent according to any one of claims 1 and 3 to 5, wherein The diamine component contains at least two diamines selected from the group consisting of a diamine containing a partial skeleton represented by the formula (ND-2) and a diamine represented by the formula (ND-5).

7. The liquid crystal aligning agent according to any one of claims 1 to 6, wherein The present invention further contains at least one polymer (P2) selected from the group consisting of a second polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component and an imidized polymer thereof, and different from the polymer (P1).

8. The liquid crystal alignment agent according to claim 7, wherein: The diamine component as a raw material of the polymer (P2) contains at least one diamine selected from the group consisting of the following formula (3), the following formula (4) and the following formula (5), A1 and A4 each independently represent a single bond or a divalent organic group, A2 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphate group, or a monovalent organic group having 1 to 20 carbon atoms, A3 represents a divalent organic group, a is an integer of 1 to 4, when a is 2 or more, the structure of A2 may be the same or different, b and c each independently represent an integer of 1 to 2, and d is an integer of 0 or 1. 9 . The liquid crystal aligning agent according to claim 7 , wherein The diamine component as a raw material of the polymer (P2) contains at least one diamine selected from the group consisting of the following formulas (DA-3-1), (DA-4-1) to (DA-4-23), and (DA-5-1) to (DA-5-3), 10 . The liquid crystal aligning agent according to claim 1 , wherein The end-capping agent is an acid anhydride or a monoamine.

11. The liquid crystal aligning agent according to any one of claims 7 to 10, wherein The content of the polymer (P1) is 30 parts by mass or more based on 100 parts by mass of the total amount of the polymer (P1) and the polymer (P2). 12 . A liquid crystal aligning film obtained by irradiating a film obtained by applying the liquid crystal aligning agent according to claim 1 and baking the film with polarized ultraviolet rays. 13 . A liquid crystal display element comprising the liquid crystal aligning film according to claim 12 .

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