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

Abstract

A liquid crystal aligning agent which contains the components (A) and (B) described below.　(A): A polyimide which is obtained by imidizing a polyimide precursor that is obtained by a reaction between a tetracarboxylic acid component and a diamine component containing at least one diamine selected from among compounds of formula (1) and formula (2). In the formulae, A1 represents a single bond, a methylene group, an ether bond, an ester bond, an amide bond, a cyclohexylene group or an alkylene group having from 2 to 20 carbon atoms; an arbitrary –CH2 moiety of the alkylene group may be substituted by an ether group, an ester group, an amide group, a cyclohexylene group, a phenylene group, a urea group, an amino group or a carbamate group; an arbitrary hydrogen atom in the amide group, the urea group and the amino group may be substituted by a methyl group or a tert-butoxycarbonyl group; A2 represents a fluorine atom or an alkyl group or alkoxy group having from 1 to 5 carbon atoms; an arbitrary hydrogen atom in the alkyl group or the alkoxy group may be substituted by a fluorine atom, while an arbitrary carbon atom therein may be substituted by an amino group that is protected by a tert-butoxycarbonyl group; each of the plurality of a's independently represents an integer from 0 to 4; if a plurality of A2 moieties are present, the A2 moieties may be the same as or different from each other; each of b and c independently represents an integer from 0 to 2; and if b is 0, c is 1 or 2 and A1 is an alkylene group.　(B): An organic solvent which contains butyl cellosolve and butyl cellosolve acetate.

Description

[Technical field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. [Background technology]

[0002] As a liquid crystal alignment film, so-called polyimide-based liquid crystal alignment films are widely used, which are formed by applying and baking a liquid crystal alignment agent whose main component is a polyimide precursor such as polyamic acid (also called polyamide acid) or a solution of a soluble polyimide.

[0003] In recent years, as the screen size and resolution of liquid crystal display elements have become larger, the substrates used and the unevenness of the substrate steps have become larger. Under such circumstances, a uniform liquid crystal alignment film is required even for large substrates with large unevenness.

[0004] In the process of producing a liquid crystal alignment film, when a liquid crystal alignment agent containing polyamic acid or a solvent-soluble polyimide (also called a resin) is applied to a substrate, this is generally done industrially by flexographic printing or inkjet coating. In this case, if the coating properties of the liquid crystal alignment agent are poor, repellency or pinholes will occur, and these will become display defects when the liquid crystal display element is made. In response to this, in addition to N-methyl-2-pyrrolidone, γ-butyrolactone, and other solvents with excellent resin solubility (also called good solvents), ethylene glycol monobutyl ether, and other solvents with low resin solubility (also called poor solvents), are mixed into the liquid crystal alignment agent solvent in order to improve the coating properties of the liquid crystal alignment agent (see, for example, Patent Document 1).

[0005] However, poor solvents have poor ability to dissolve polyamic acid and solvent-soluble polyimide, so that mixing in large quantities causes the problem of resin precipitation. In addition, in liquid crystal display elements for mobile applications, such as smartphones and mobile phones, which have been used in recent years, in order to secure as much display surface as possible, the sealant used to bond between the substrates of the liquid crystal display element is located in the vicinity of the edge of the liquid crystal alignment film. Therefore, when the coating property of the edge of the liquid crystal alignment film is reduced, that is, when the edge of the liquid crystal alignment film is not straight or when the edge is raised, the adhesive effect between the liquid crystal alignment film and the sealant is reduced, which causes a problem of deteriorating the display characteristics and reliability of the liquid crystal display element.

[0006] Meanwhile, the inkjet method has been attracting attention as a method for forming liquid crystal alignment films without using flexographic printing plates. The inkjet method is a method in which fine droplets are dropped onto a substrate and a film is formed by the liquid wetting and spreading. Not only does it not use printing plates, but it also allows the printing pattern to be freely set, simplifying the manufacturing process of liquid crystal display elements. Another advantage is that it does not require film formation on a dummy substrate, which is necessary with flexographic printing, so there is less waste of coating liquid. It is expected that the inkjet method will reduce the cost of liquid crystal panels and improve production efficiency.

[0007] However, although the inkjet method has the merits of reducing the cost of liquid crystal panels and improving production efficiency, the liquid crystal alignment film formed by the inkjet method generally has a trade-off between the uniformity of the film thickness within the coating surface and the film formation accuracy of the coating periphery. That is, materials with high in-plane uniformity usually have low dimensional stability in the coating periphery, and there is a problem that the film protrudes from the set dimensions.

[0008] In view of this, a composition containing a specific poor solvent, such as dipropylene glycol dimethyl ether, has been proposed as a composition with excellent film-coating properties for forming a polyimide film (see Patent Document 2).

[0009] Furthermore, Patent Document 3 describes that a liquid crystal alignment film containing a solvent-soluble polyimide containing a specific diamine can obtain extremely high reliability even for negative liquid crystals that are very susceptible to contamination, and Patent Document 4 discloses that by using a liquid crystal alignment agent containing a solvent-soluble polyimide with a high imidization rate containing a specific diamine, it is possible to obtain a liquid crystal alignment film having a low pretilt angle of 1 degree or less, excellent voltage holding ratio, and liquid crystal alignment properties. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2-37324 [Patent Document 2] JP 2018-83943 A [Patent Document 3] WO2015 / 199149 [Patent Document 4] WO2019 / 082975 Summary of the Invention [Problem to be solved by the invention]

[0011] When a composition containing ethylene glycol monobutyl ether, a poor solvent, added to N-methyl-2-pyrrolidone and γ-butyrolactone disclosed in Patent Document 1 in order to improve the coating property of a liquid crystal alignment agent is used in an inkjet method, when standby shots in which liquid is periodically sprayed to prevent nozzle clogging are performed over a long period of time, the liquid consisting of the polyimide solution adheres to the surface of the inkjet head, and problems are likely to occur, particularly when the composition contains a polyimide with a high imidization rate.

[0012] In view of the above circumstances, the present invention aims to provide a liquid crystal aligning agent that has excellent bonding properties between liquids and good coating properties, and can be used stably for a long period of time even in an inkjet method, as well as a liquid crystal alignment film and a liquid crystal display element produced therefrom. [Means for solving the problem]

[0013] As a result of intensive research, the present inventors have found that, for example, by introducing butyl cellosolve acetate as a poor solvent into N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), and ethylene glycol monobutyl ether (butyl cellosolve; BCS), good coating properties and good dimensional stability of the coated peripheral area can be obtained, and the inkjet method can be used stably for a long period of time, thereby completing the present invention. Furthermore, the present inventors have found that the properties of such a solvent are particularly effective when dissolving a specific polyimide, thereby completing the present invention.

[0014] The liquid crystal aligning agent of the present invention for achieving the above object is Contains the following (A) and (B). (A): A polyimide obtained by imidizing a polyimide precursor, which is a reaction product between a diamine component containing at least one diamine selected from the following formulae [1] and [2] and a tetracarboxylic acid component. [ka] In the formula, A1 is a single bond, a methylene group, an ether bond, an ester bond, an amide bond, a cyclohexylene group, or an alkylene group having 2 to 20 carbon atoms. However, any -CH2- in the alkylene group may be substituted with an ether group, an ester group, an amide group, a cyclohexylene group, a phenylene group, a urea group, an amino group, or a carbamate group, and any hydrogen atom in the amide group, the urea group, or the amino group may be substituted with a methyl group or a tert-butoxycarbonyl group. A2 is a fluorine atom, or an alkyl group or alkoxy group having 1 to 5 carbon atoms, and any hydrogen atom in the alkyl group or the alkoxy group may be substituted with a fluorine atom, and any carbon atom may be substituted with an amino group protected with a tert-butoxycarbonyl group. Each of the multiple a's is independently an integer of 0 to 4, and when there are multiple A2's, A2's may be the same or different. b and c each independently represent an integer of 0 to 2, and when b is 0, c is 1 or 2, and A1 is an alkylene group. (B): An organic solvent containing butyl cellosolve and butyl cellosolve acetate. Effect of the Invention

[0015] According to the present invention, it is possible to provide a liquid crystal alignment agent which has good coating properties, good dimensional stability around the application periphery, and can be stably used for a long period of time even in an inkjet method, as well as a liquid crystal alignment film and a liquid crystal display element produced therefrom. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will now be described in more detail. The liquid crystal aligning agent of the present invention contains the following (A) and (B). (A): A polyimide obtained by imidizing a polyimide precursor, which is a reaction product between a diamine component containing at least one diamine selected from the above formulae [1] and [2] and a tetracarboxylic acid component. (B): An organic solvent containing butyl cellosolve and butyl cellosolve acetate.

[0017] The diamine used in the present invention includes at least one selected from the above formula [1] or [2]. In the above formula [1], A2 is preferably a methyl group. In the above formula [2], from the viewpoint of improving liquid crystal alignment, A1 is preferably a single bond, a methylene group, an ether bond, an ester bond, or an alkylene group having 2 to 10 carbon atoms (with the proviso that at least one -CH2- of the alkylene group is substituted with an ether group or an ester group). In the above formula [2], A2 is preferably a methyl group. a is preferably an integer of 0 to 1. b is preferably 1. c is preferably an integer of 1 to 2. More preferred specific structures of the diamine represented by the above formula [1] and the diamine represented by the formula [2] include any of the structures of the following formulas [d1-1] to [d1-2] and [d2-1] to [d2-28].

[0018] [ka] (In formula [d1-1], R represents a fluorine atom, or an alkyl or alkoxy group having 1 to 5 carbon atoms, and any hydrogen atom of the alkyl or alkoxy group may be substituted with a fluorine atom. In formula [d1-2], Boc represents a tert-butoxycarbonyl group.)

[0019] [ka] (In formula [d2-8], R and R' each independently represent a fluorine atom, or an alkyl or alkoxy group having 1 to 5 carbon atoms, and any hydrogen atom of the alkyl or alkoxy group may be substituted with a fluorine atom.)

[0020] [ka]

[0021] [ka] (In the formula, Boc represents a tert-butoxycarbonyl group. When multiple m's are present in formula [d2-17], the multiple m's may be the same or different.)

[0022] [ka]

[0023] As the diamine represented by the above formula [1] and the diamine represented by the above formula [2], the following structures can be given as more preferred specific structures.

[0024] [ka]

[0025] The content of the diamines represented by the above formula [1] and the above formula [2] is preferably 50 mol % or more, and more preferably 70 mol % or more, per mol of the total diamine components.

[0026] In the present invention, the diamine constituting the polyimide (A) may include a diamine described below in addition to the diamine selected from the diamines represented by the formulas [1] and [2] above.

[0027] The diamines selected from the above formulas [1] and [2] may be used in combination of two or more, or three or more. Among them, it is preferable to use two or more kinds of diamines selected from the above formula [2].

[0028] <Diamines with specific side chain structures> The diamine having a specific side chain structure exhibits vertical alignment properties and has at least one side chain structure selected from the group represented by the following formulas [S1] to [S3]. Hereinafter, examples of the second diamine having such a specific side chain structure, that is, the diamine having the specific side chain structure represented by the formulas [S1] to [S3], will be described in order.

[0029] [a]: A diamine having a specific side chain structure represented by the following formula [S1] [ka] In the above formula [S1], X 1 and X 2 are each independently a single bond, -(CH2) a -(a represents an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -COO-, -OCO- or -((CH2) a1 -A1) m1 In these, a1 represents an integer of 1 to 15, A1 represents an oxygen atom or -COO-, and m1 represents an integer of 1 to 2. When m1 is 2, a1 and A1 each independently have the above definition.

[0030] Among them, X is the most popular in terms of availability of raw materials and ease of synthesis.1 and X 2 are each independently a single bond, -(CH2) a -(a is an integer of 1 to 15), -O-, -CH2O- or -COO- is preferred, and a single bond, -(CH2) a - (wherein a is an integer of 1 to 10), -O-, -CH2O- or -COO- is more preferred.

[0031] In addition, in the above formula [S1], G 1 and G 2 each independently represents a divalent cyclic group selected from the group consisting of a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group may be substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. m and n each independently represent an integer of 0 to 3, and the sum of m and n is 1 to 6, and preferably 1 to 4.

[0032] In addition, in the above formula [S1], R 1 R represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. 1 Any hydrogen atom forming the group may be substituted with a fluorine atom. Examples of the divalent aromatic group having 6 to 12 carbon atoms include a phenylene group, a biphenyl structure, and a naphthylene group. Examples of the divalent alicyclic group having 3 to 8 carbon atoms include a cyclopropylene group and a cyclohexylene group.

[0033] Therefore, preferred specific examples of the above formula [S1] include the following formulae [S1-x1] to [S1-x7]. [ka]

[0034] In the above formula [S1-x1] to [S1-x7], R 1 is the same as in the above formula [S1]. p is -(CH2)a A1 represents an oxygen atom or -COO-* (the bond marked with "*" is (CH2)). a2 A2 represents an oxygen atom or *-COO- (the bond marked with "*" is (CH2) a2 a3 represents an integer of 0 or 1, and a1 and a2 each independently represent an integer of 2 to 10. Cy represents a 1,4-cyclohexylene group or a 1,4-phenylene group.

[0035] [b]: Diamine having a specific side chain structure represented by the following formula [S2] [ka] In the above formula [S2], X 3 represents a single bond, -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CHO-, -COO- or -OCO-. Among them, from the viewpoint of the liquid crystal alignment property of the liquid crystal alignment agent, X 3 is preferably -CONH-, -NHCO-, -O-, -CHO-, -COO- or -OCO-.

[0036] In addition, in the above formula [S2], R 2 R represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms. 2 Any hydrogen atom forming R may be substituted with a fluorine atom. 2 is preferably an alkyl group having 3 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms. Preferred examples of the formula [S2] include X 3 is any one of -O-, -CHO-, -COO-, or -OCO-, and R 2 is preferably an alkyl group having 3 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms, and R 2 is more preferably an alkyl group having 3 to 20 carbon atoms, and R 2Any hydrogen atom forming the formula (I) may be substituted with a fluorine atom.

[0037] [c]: Diamine having a specific side chain structure represented by the following formula [S3] [ka] In the above formula [S3], X 4 represents -CONH-, -NHCO-, -O-, -CHO-, -COO- or -OCO-. 3 represents a structure having a steroid skeleton. The steroid skeleton here has a skeleton represented by the following formula (st) in which three six-membered rings and one five-membered ring are bonded. The ring in the steroid skeleton may have a double bond. [ka]

[0038] An example of the above formula [S3] is the following formula [S3-x], where Me represents a methyl group.

[0039] [ka]

[0040] In the formula [S3-x], X represents the formula [X1], [X2] or [X3]. Col represents any one of the formulas [Col1] to [Col3], and G represents any one of the formulas [G1] to [G4]. * represents a bond.

[0041] In the above formula [S3-x], preferred examples of combinations of X, Col, and G include the following combinations: [X1], [Col1], and [G1], [X1], [Col1], and [G2], [X1], [Col2], and [G1], [X1], [Col2], and [G2], [X1], [Col3], and [G2], [X1], [Col3], and [G1], [X2], [Col1], and [G2], [X2], [Col2], and [G2], [X2], [Col2], and [G1], [X2], [Col3], and [G2], [X2], [Col1], and [G1], [X3], [Col2], and [G1], [X3], [Col2], and [G2], [X3], [Col2], and [G3].

[0042] Specific examples of the above formula [S3] include a structure obtained by removing a hydroxyl group (hydroxy group) from a steroid compound described in paragraph

[0024] of JP-A-4-281427, a structure obtained by removing an acid chloride group from a steroid compound described in paragraph

[0030] of the same publication, a structure obtained by removing an amino group from a steroid compound described in paragraph

[0038] of the same publication, a structure obtained by removing a halogen atom from a steroid compound described in paragraph

[0042] of the same publication, and structures described in paragraphs

[0018] to

[0022] of JP-A-8-146421.

[0043] A representative example of the steroid skeleton is cholesterol (the combination of [Col1] and [G2] in the above formula [S3-x]), but a steroid skeleton that does not contain cholesterol can also be used. That is, an example of a diamine having a steroid skeleton is cholestanyl 3,5-diaminobenzoate, but it is also possible to use a diamine component that does not contain a diamine having a cholesterol skeleton. In addition, as a diamine having a specific side chain structure, one that does not contain an amide bond at the linking position between the diamine and the side chain can also be used. In this embodiment, a liquid crystal alignment agent that can obtain a liquid crystal alignment film or liquid crystal display element that can ensure a high voltage retention rate for a long period of time can be provided, even if a diamine component that does not contain a diamine having a cholesterol skeleton is used.

[0044] The diamines having side chain structures represented by the above formulae [S1] to [S3] are represented by the structures of the following formulae [1-S1] to [1-S3], respectively.

[0045] [ka] In the above formula [1-S1], X 1 , X 2 , G 1 , G 2 , R 1 , m and n are the same as those in the above formula [S1]. In the above formula [1-S2], X 3 and R 2 is the same as in the above formula [S2]. In the above formula [1-S3], X 4 and R 3 is the same as in the above formula [S3].

[0046] (Diamine with specific two-side chain structure that exhibits vertical alignment) The diamine having a specific two-side chain structure that exhibits vertical alignment properties is represented, for example, by the following formula [N1].

[0047] [ka]

[0048] In the above formula [N1], X is a single bond, -O-, -C(CH3)2-, -NH-, -CO-, -NHCO-, -COO-, -(CH2) m It represents a divalent organic group consisting of -, -SO2-, or any combination thereof. Among them, X is a single bond, -O-, -NH-, or -O-(CH2) m -O- is preferred. An example of "any combination thereof" is -O-(CH2) m -O-, -OC(CH3)2-, -CO-(CH2) m -, -NH-(CH2) m -, -SO2-(CH2) m -, -CONH-(CH2) m -, -CONH-(CH2) m-NHCO-, -COO-(CH2) m -OCO-, -NH-(CH2) m -NH-, -SO2-(CH2) m m represents an integer of 1 to 8. In the above formula [N1], two Ys each independently represent a monovalent group selected from the side chain structures represented by the above formulas [S1] to [S3].

[0049] In addition, in the above formula [N1], Y may be in the meta position or the ortho position relative to the position of X, but is preferably in the ortho position. That is, the above formula [N1] is preferably the following formula [1'].

[0050] [ka]

[0051] In the above formula [N1], the positions of the two amino groups (-NH2) may be any positions on the benzene ring, but the positions represented by the following formulas [1]-a1 to [1]-a3 are preferred, and the following formula [1]-a1 is more preferred. In the following formulas, X is the same as in the above formula [N1]. Note that the following formulas [1]-a1 to [1]-a3 explain the positions of the two amino groups, and the notation of Y represented in the above formula [N1] is omitted.

[0052] [ka]

[0053] Therefore, based on the above formulas [1'] and [1]-a1 to [1]-a3, the above formula [N1] is preferably any structure selected from the group consisting of the following formulas [1]-a1-1 to [1]-a3-2, and more preferably the structure represented by the following formula [1]-a1-1, in which X and Y are the same as in formula [N1].

[0054] [ka]

[0055] Examples of the above formulae [S1] to [S3] include the following formulae [S]-1 to [S]-20. Of these, examples of the above formula [S1] are preferably the following formulae [S]-1 to [S]-4, [S]-8 or [S]-10. In the following formulae, * represents the bonding position with the phenyl group in the above formulae [1], [1'] and [1]-a1 to [1]-a3. In [S]-1 to [S]-20, n is an integer from 1 to 20, and m is an integer from 1 to 6.

[0056] [ka]

[0057] [ka]

[0058] <Other diamines: diamines having photoreactive side chains> The diamine component of the present embodiment may contain a diamine having a photoreactive side chain as the other diamine. When the diamine component contains a diamine having a photoreactive side chain, the photoreactive side chain can be introduced into the specific polymer or other polymers. Specific examples of diamines having a photoreactive side chain include, but are not limited to, those described in paragraphs

[0124] to

[0132] of Republished Patent Publication No. 2016 / 140328.

[0059] These diamines having photoreactive side chains can be used alone or in combination of two or more. Whether to use alone or in combination of two or more, and when used in combination of two or more, the ratio, etc., may be appropriately adjusted depending on the liquid crystal alignment property, pretilt angle, voltage retention property, stored charge property, etc., when used as a liquid crystal alignment film, and the response speed of the liquid crystal when used as a liquid crystal display element.

[0060] In the present embodiment, when the diamine component contains a photoreactive side chain diamine, the photoreactive side chain diamine preferably accounts for 10 to 70 mol %, and more preferably 10 to 60 mol %, of the entire diamine component.

[0061] <Other diamines: diamines other than those mentioned above> The other diamines that may be contained in the diamine component for obtaining the specific polymer are not limited to the above-mentioned diamines having a photoreactive side chain. When producing a polyimide precursor and / or a polyimide, diamines other than the above-mentioned diamines can be used in combination as a diamine component. Specifically, in addition to the diamines listed below, those described in paragraph

[0135] of the republished patent publication WO2016 / 140328 can be mentioned.

[0062] Diamines with photo-alignable groups such as 4,4'-diaminoazobenzene or diaminotolane; 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylmethylamine, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; 4,4'-diamino-3,3'-dihydroxybiphenyl, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid , 3,5-diaminobenzoic acid, and diamines having a carboxyl group such as diamines represented by the following formulae (3b-1) to (3b-4); 4-(2-(methylamino)ethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; 2-(2,4-diaminophenoxy)ethyl methacrylate, 2,4-diamino-N,N-di Allylaniline; 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, diamines having a siloxane bond such as diamines represented by the following formula (Ds-1); diamines represented by the following formulas (Ox-1) to (Ox-2), 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacrylamide, 1,4-bis(4-aminophenyl)-piperazine ... Lysine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, diamines having a heterocyclic structure such as diamines represented by the following formulas (z-1) to (z-18); meta-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), and the like.

[0063] [ka] (In (3b-1) above, A 1represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, m1 and m2 each independently represent an integer of 0 to 4, and m1+m2 represents an integer of 1 to 4. In formula (3b-2), m3 and m4 each independently represent an integer of 1 to 5. In formula (3b-3), A 2 represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 represents an integer of 1 to 5. 3 and A 4 each independently represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, and m6 represents an integer of 1 to 4.

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] The above other diamines can be used alone or in combination of two or more depending on the properties, such as liquid crystal alignment property, pretilt angle, voltage holding property, and stored charge, when formed into a liquid crystal alignment film.

[0068] When the liquid crystal alignment film of the present invention is used in an IPS or FFS liquid crystal display element, it is preferable that the diamine constituting the polyimide (A) in the present invention does not have a side chain group having 6 or more carbon atoms. Examples of the diamine having a side chain group having 6 or more carbon atoms include the diamine having the above-mentioned specific side chain structure and the diamine having the above-mentioned two-side chain type specific side chain structure that exhibits vertical alignment.

[0069] <Polyimide> The polyimide of the present invention is obtained by imidizing a polyimide precursor, which is a reaction product between the above diamine and a tetracarboxylic acid component.

[0070] <Tetracarboxylic acid component> As the tetracarboxylic acid component for obtaining the polyimide of the present invention, a tetracarboxylic dianhydride represented by the following formula [3] or a derivative thereof (tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide) (collectively referred to as specific tetracarboxylic acid) can be used.

[0071] [ka] In formula [3], X1 is selected from any one of the following formulae (B-1) to (B-20). It is particularly preferable that X1 is any one of (B-1), (B-2), and (B-3).

[0072] [ka]

[0073] [ka] (In the formula, j and k are integers of 0 or 1, and A1 and A2 each independently represent a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or an amide group. In the above formula (B-20), two A2 may be the same or different. In the formula, * represents a bond.)

[0074] Specific examples of the specific tetracarboxylic acid include, in addition to those listed below, 2,3,3',4-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride.

[0075] [ka]

[0076] The specific tetracarboxylic acid is preferably 50 to 100 mol % in 100 mol % of all the tetracarboxylic acid components, more preferably 70 to 100 mol %, and even more preferably 80 to 100 mol %.

[0077] The specific tetracarboxylic acid may be used alone or in combination of two or more depending on the properties such as the solubility of the specific polymer in a solvent, the coatability of the liquid crystal alignment agent, the alignment of the liquid crystal when formed into a liquid crystal alignment film, the voltage holding rate, and the stored charge.

[0078] The tetracarboxylic acid component for obtaining the polyimide of the present invention may contain a tetracarboxylic acid other than the above-mentioned specific tetracarboxylic acids (hereinafter, also referred to as other tetracarboxylic acids). Examples of other tetracarboxylic acids include the following tetracarboxylic acid compounds, tetracarboxylic dianhydrides, tetracarboxylic acid dihalide compounds, tetracarboxylic acid dialkyl ester compounds, and tetracarboxylic acid dialkyl ester dihalide compounds.

[0079] That is, examples of other tetracarboxylic acids include 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride, bis(3,4-dicarboxyphenyl)diphenylsilane dianhydride, 2,3,4,5-pyridinetetracarboxylic dianhydride, 2,6-bis(3,4-dicarboxyphenyl)pyridine dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, and 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride. Other tetracarboxylic acids can be used alone or in combination depending on the solubility of the specific polymer in a solvent, the coatability of the liquid crystal alignment agent, and properties such as liquid crystal alignment, voltage holding rate, and stored charge when used as a liquid crystal alignment film.

[0080] <Polyimide manufacturing method> The polyimide of the present invention can be obtained by a method of reacting the diamine component and the tetracarboxylic acid component described above. For example, the method includes a method of reacting a diamine component consisting of one or more diamines with at least one tetracarboxylic acid component selected from the group consisting of tetracarboxylic dianhydrides and derivatives of the tetracarboxylic acid to obtain a polyamic acid. Specifically, a method of polycondensing a primary or secondary diamine with a tetracarboxylic dianhydride to obtain a polyamic acid is used.

[0081] To obtain a polyamic acid alkyl ester, a method of polycondensing a tetracarboxylic acid in which a carboxylic acid group has been dialkyl esterified with a primary or secondary diamine, a method of polycondensing a tetracarboxylic acid dihalide in which a carboxylic acid group has been halogenated with a primary or secondary diamine, or a method of converting a carboxy group of a polyamic acid into an ester is used.To obtain a polyimide, a method of ring-closing the above-mentioned polyamic acid or polyamic acid alkyl ester to obtain a polyimide is used.

[0082] The reaction between the diamine component and the tetracarboxylic acid component is usually carried out in a solvent. The solvent used at that time is not particularly limited as long as the generated polyimide precursor dissolves. Examples of the solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. In addition, when the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D-1] to [D-3] can be used.

[0083] [ka]

[0084] In formula [D-1], D 1 represents an alkyl group having 1 to 3 carbon atoms. 2 represents an alkyl group having 1 to 3 carbon atoms. 3 represents an alkyl group having 1 to 4 carbon atoms.

[0085] These solvents can be used alone or in combination of two or more. Even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above-mentioned solvent as long as the generated polyimide precursor does not precipitate. In addition, since moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried.

[0086] When the diamine component and the tetracarboxylic acid component are reacted in a solvent, any of the following methods may be used: 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 added as is or after being dispersed or dissolved in the solvent; 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 added alternately; etc. When a plurality of diamine components or tetracarboxylic acid components are used for the reaction, they may be reacted in a premixed state, or may be reacted individually in sequence, or low molecular weight substances that have been reacted individually may be mixed and reacted to form a polymer.

[0087] The temperature at which the diamine component and the tetracarboxylic acid component are polycondensed can be selected from any temperature between -20 and 150°C, but is 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 polymer with a high molecular weight, and if the concentration is too high, the viscosity of the reaction liquid becomes too high, making it difficult to stir uniformly. Therefore, the concentration 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 early stages, and then a solvent can be added.

[0088] In the polymerization reaction of the polyimide precursor, the ratio of the total number of moles of the diamine component to the total number of moles of the tetracarboxylic acid component is preferably 0.8 to 1.2. As in the case of a normal polycondensation reaction, the closer this molar ratio is to 1.0, the higher the molecular weight of the resulting polyimide precursor will be.

[0089] The polyimide is obtained by ring-closing the polyimide precursor, and the ring-closing rate of the amic acid group (also called the imidization rate) in this polyimide does not necessarily need to be 100%, and can be arbitrarily adjusted according to the application or purpose. The imidization rate of the polyimide, which is the specific polymer used in the present invention, is preferably 20 to 100%, more preferably 50 to 99%, and even more preferably 70 to 95%, from the viewpoint of reducing the occurrence rate of display defects. Methods for imidizing the polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is heated as it is, and catalytic imidization, in which a catalyst is added to a solution of the polyimide precursor.

[0090] The temperature for thermally imidizing the polyimide precursor in a solution is 100 to 400° C., preferably 120 to 250° C., and it is preferable to carry out the imidization while removing water generated by the imidization reaction from the system. Catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring the mixture at −20 to 250° C., preferably 0 to 180° C.

[0091] The amount of the basic catalyst is 0.5 to 30 times by mol, preferably 2 to 20 times by mol, the amount of the acid anhydride is 1 to 50 times by mol, preferably 3 to 3 ...

[0092] When recovering the polyimide produced from the polyimide reaction solution, the reaction solution may be poured into a solvent to cause precipitation. Examples of the solvent used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring into the solvent can be recovered by filtration, and then dried at normal pressure or reduced pressure, or at room temperature or by heating. In addition, the polymer precipitated and recovered can be redissolved in a solvent and the reprecipitation and recovery operation can be repeated 2 to 10 times to reduce impurities in the polymer. Examples of the solvent used in this case include alcohols, ketones, and hydrocarbons. It is preferable to use three or more types of solvents selected from these because the efficiency of purification is further improved.

[0093] <Terminal Modifier> In synthesizing the polyimide precursor or polyimide of the present invention, a terminal-modified polymer may be synthesized using a suitable terminal modifier together with the above-mentioned tetracarboxylic acid derivative component and diamine component. The terminal-modified polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion property between the sealant and the liquid crystal alignment film. Examples of the terminals of the polyimide precursor or polyimide in the present invention include an amino group, a carboxyl group, an acid anhydride group, an isocyanate group, a thioisocyanate group, or derivatives thereof. The amino group, the carboxyl group, the acid anhydride group, the isocyanate group, and the thioisocyanate group can be obtained by a normal condensation reaction, and the above-mentioned derivatives can be obtained by modifying the terminals, for example, with the following terminal modifiers.

[0094] Examples of the terminal modifier include acid monoanhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, compounds represented by the following formulas (m-1) to (m-6), 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, and 4-ethynylphthalic anhydride;

[0095] [ka]

[0096] Examples of the isocyanate include diester dicarbonate compounds such as di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds such as acryloyl chloride, methacryloyl chloride and nicotinic acid chloride; monoamine compounds such as aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine and n-octylamine; monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate and naphthyl isocyanate; and thioisocyanate compounds such as ethyl isothiocyanate and allyl isothiocyanate.

[0097] The proportion of the terminal modifier used is preferably 0.01 to 20 parts by mol, and more preferably 0.01 to 10 parts by mol, relative to 100 parts by mol of the total of the diamine components used.

[0098] <Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention contains the above polyimide (referred to as a specific polymer), but may contain two or more polymers with different structures. In addition to the polymer, it may contain other polymers. Examples of the polymer include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc. When the liquid crystal alignment agent of the present invention contains other polymers, the ratio of the specific polymer to the total polymer components is preferably 5% by mass or more, for example, 5 to 95% by mass.

[0099] Of the above other polymers, from the viewpoint of enhancing liquid crystal alignment, a polyamic acid not containing an imide ring structure or a polyamic acid ester not containing an imide ring structure (hereinafter also referred to as a polyimide precursor (pa)) is preferable.

[0100] Examples of the tetracarboxylic acid derivative component for obtaining the polyimide precursor (pa) include acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, or derivatives thereof. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aromatic tetracarboxylic acid dianhydrides include the tetracarboxylic acid dianhydrides or derivatives thereof exemplified in the above specific polymer. Among them, the compound represented by the above formula [3] or a derivative thereof is preferable as the tetracarboxylic acid derivative component. As the tetracarboxylic acid derivative component, one type of tetracarboxylic acid dianhydride or its derivative may be used alone, or two or more types may be used in combination.

[0101] The tetracarboxylic acid derivative component for obtaining the polyimide precursor (pa) is preferably a tetracarboxylic acid dianhydride represented by formula [3] in which X1 is selected from the above formulas (B-1) to (B-8) and (B-13) to (B-20), or a derivative thereof.

[0102] The proportion of the tetracarboxylic dianhydride represented by the above formula [3] or a derivative thereof used is preferably 1 to 100 mol %, more preferably 5 to 100 mol %, and even more preferably 10 to 100 mol %, based on 1 mol of the total tetracarboxylic acid derivative components used in the synthesis of the polyimide precursor (pa).

[0103] The diamine component for obtaining the polyimide precursor (pa) may be any of the diamine components exemplified in the specific polymer. Among them, it is preferable to include at least one diamine selected from the group consisting of a diamine having at least one group selected from the group consisting of a urea bond, an amide bond, a carboxy group, and a hydroxy group in the molecule (hereinafter also referred to as diamine (b1)), and a diamine having a nitrogen-containing structure (excluding urea bond, amide bond, and imide bond) selected from the group consisting of a secondary amino group, a tertiary amino group, and a heterocycle (hereinafter also referred to as diamine (b2)). The diamine component may be a single diamine or a combination of two or more diamines. In the above, the total amount of the diamines (b1) and (b2) used is preferably 10 to 100 mol%, more preferably 10 to 90 mol%, and even more preferably 20 to 80 mol% based on the total amount of the diamine components for producing the polyimide precursor (pa).

[0104] The polyimide precursor (pa) may be composed of one or more polyimide precursors. More preferred specific embodiments of the polyimide precursor (pa) include at least one polymer (hereinafter also referred to as copolymer) selected from the group consisting of a polyimide precursor which is a reaction product between a diamine component containing the above diamine (b1) and the above diamine (b2) and a tetracarboxylic acid derivative component, at least one polyimide precursor (pa-p1) selected from the group consisting of a polyimide precursor which is a reaction product between a diamine component containing the above diamine (b1) and a tetracarboxylic acid derivative component, and at least one polyimide precursor (pa-p2) selected from the group consisting of a diamine component containing the above diamine (b2) and a tetracarboxylic acid derivative component (hereinafter also referred to as polymer blend). The above copolymers or polymer blends may be used alone or in combination.

[0105] In the above copolymer, the amount of diamine (b1) used is preferably 30 to 100 mol %, more preferably 40 to 100 mol %, and further preferably 50 to 100 mol %, based on the total amount of diamine components used to produce the polyimide precursor (pa). In the above copolymer, the amount of diamine (b2) used is preferably 30 to 100 mol %, more preferably 40 to 100 mol %, and further preferably 50 to 100 mol %, based on the total amount of diamine components used to produce the polyimide precursor (pa). In the above polymer blend, the diamine (b1) and the diamine (b2) are preferably used in an amount of 20 to 100 mol % based on the total amount of the diamine components for producing the polyimide precursor (pa-p1) and the polyimide precursor (pa-p2), respectively. The diamine (b1) is more preferably used in an amount of 20 to 90 mol %, and even more preferably 20 to 80 mol %, based on the total amount of the diamine components for producing the polyimide precursor (pa-p1). The diamine (b2) is more preferably used in an amount of 20 to 80 mol %, and even more preferably 30 to 80 mol %, based on the total amount of the diamine components for producing the polyimide precursor (pa-p2).

[0106] Specific examples of the diamine (b1) include diamines represented by the above formulae [d2-10] to [d2-16], 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diamino-3,3'-dihydroxybiphenyl, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, or 3,5-diaminobenzoic acid, or diamines represented by the above formulae (3b-1) to (3b-4).

[0107] Specific examples of the diamine (b2) include the diamines represented by the above formulae [d2-23] to [d2-28], 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylmethylamine, and the diamines represented by the above formulae (z-1) to (z-18).

[0108] The mass ratio of the content of the polyimide precursor (pa-p1) to the content of the polyimide precursor (pa-p2) is preferably 5 / 95 to 95 / 5, and more preferably 10 / 90 to 90 / 10.

[0109] From the viewpoint of reducing afterimages caused by residual DC, the content ratio of the polyimide which is the specific polymer and the polyimide precursor (pa) may be 5 / 95 to 95 / 5, 20 / 80 to 90 / 10, or 20 / 80 to 80 / 20 in terms of the mass ratio of [polyimide which is the specific polymer] / [polyimide precursor (pa)].

[0110] The liquid crystal aligning agent generally takes the form of a coating liquid in order to form a uniform thin film. The liquid crystal aligning agent of the present invention is also preferably a coating liquid containing the above-mentioned polymer component and an organic solvent that dissolves the polymer component. In this case, the concentration of the polymer in the liquid crystal aligning agent can be appropriately changed depending on the thickness of the coating film to be formed. In order to form a uniform and defect-free coating film, the concentration is preferably 1% by mass or more, and in order to ensure the storage stability of the solution, the concentration is preferably 10% by mass or less. A particularly preferred concentration of the polymer is 2 to 8% by mass.

[0111] The organic solvent contained in the liquid crystal alignment agent contains butyl cellosolve and butyl cellosolve acetate (B), and also contains other organic solvents in which the polymer components are uniformly dissolved. The liquid crystal aligning agent of the present invention contains butyl cellosolve and butyl cellosolve acetate as poor solvents, and therefore has excellent bonding between liquids and good coating properties, and can be stably used for a long period of time even in the inkjet method.

[0112] The content of butyl cellosolve is preferably 5 to 20 mass% based on the total organic solvents contained in the liquid crystal alignment agent, and the content of butyl cellosolve acetate is preferably 5 to 20 mass% based on the total organic solvents contained in the liquid crystal alignment agent. The total amount of butyl cellosolve and butyl cellosolve acetate is preferably 10 mass% or more based on the total organic solvents contained in the liquid crystal alignment agent, more preferably 12 mass% or more, and even more preferably 15 mass% or more.

[0113] The other organic solvent is not particularly limited as long as it dissolves the polymer component. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, and the like. Pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, methyl ethyl ketone, cyclohexanone, cyclopentanone (these are collectively referred to as "solvent (C1)").);diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-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 monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxy (2-ethoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, 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, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone) (these are also collectively referred to as "solvent (C2)").As the solvent (C1), it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-dimethyllactamide, or 1,3-dimethyl-2-imidazolidinone. The content of the solvent (C1) is preferably 60 to 90 mass %, more preferably 60 to 88 mass %, and particularly preferably 60 to 85 mass %, based on the total organic solvent contained in the liquid crystal alignment agent. Among them, the solvent (C2) is preferably diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone or diisobutyl ketone. The content of the solvent (C2) is preferably 1 to 20 mass%, more preferably 5 to 20 mass%, based on the total organic solvent contained in the liquid crystal alignment agent. When the liquid crystal alignment agent contains the solvent (C1) and the solvent (C2), the total content of the solvent (C1) and the solvent (C2) is preferably 60 to 90 mass %, more preferably 60 to 88 mass %, and particularly preferably 60 to 85 mass %, based on the total organic solvents contained in the liquid crystal alignment agent.

[0114] In addition to the above-mentioned solvents, the organic solvent contained in the liquid crystal alignment agent of the present invention may also be a solvent that improves the coating property when applying the liquid crystal alignment agent and the surface smoothness of the coating film. Specific examples of such organic solvents include those described in paragraph

[0177] of the republished patent publication WO2016 / 140328.

[0115] The liquid crystal alignment agent of the present invention may additionally contain components other than the polymer component and the organic solvent. Examples of such additional components include an adhesion aid for improving the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, a crosslinking agent for increasing the strength of the liquid crystal alignment film, and a dielectric or conductive material for adjusting the dielectric constant or electrical resistance of the liquid crystal alignment film. Specific examples of these additional components are described in paragraphs

[0104] on page 53 to

[0105] on page 60 of International Publication WO 2015 / 060357.

[0116] Examples of the poor solvent and crosslinkable compound disclosed in

[0116] In addition to the above, the liquid crystal alignment agent of the present invention may contain a polymer other than the specific polymer described in the present invention, a dielectric for changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, a silane coupling agent for improving the adhesion between the liquid crystal alignment film and the substrate, a crosslinking compound for increasing the hardness and denseness of the film when made into a liquid crystal alignment film, and an imidization accelerator for efficiently proceeding with imidization by heating the polyimide precursor when baking the coating film.

[0117] Compounds that improve the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds. Specific examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxy ... Lentriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,Examples of the silane derivative include 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and those described in paragraph

[0180] of the republished patent publication WO2016 / 140328. The content is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

[0118] In order to further increase the film strength of the liquid crystal alignment film, a crosslinking compound such as a compound having two or more of at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a hydroxyalkylamide group (hereinafter also referred to as a compound having two or more specific crosslinking groups), or a phenolic compound such as 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane or tetra(methoxymethyl)bisphenol may be added. The amount of these crosslinking compounds is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of the total amount of the polymer contained in the liquid crystal alignment agent. Examples of the compound having two or more specific crosslinking groups include the following compounds.

[0119] [ka]

[0120] <Liquid crystal alignment film> The liquid crystal alignment film of the present invention is obtained from the liquid crystal alignment agent. By using the liquid crystal alignment agent of the present invention, it is possible to provide a liquid crystal alignment film and a liquid crystal display element that are particularly suitable for the IPS mode and FFS mode in which liquid crystal molecules aligned horizontally to the substrate are made to respond to an electric field, and that have excellent voltage retention, rapid relaxation of accumulated charges, and excellent afterimage characteristics. As an example of a method for obtaining a liquid crystal alignment film, the liquid crystal alignment agent of the present invention is applied to a substrate, and then dried and baked as necessary to obtain a cured film, which can be used as a liquid crystal alignment film as it is. In addition, this cured film can be rubbed, irradiated with polarized light or light of a specific wavelength, or the like, or treated with an ion beam, or irradiated with UV light while applying a voltage to a liquid crystal display element after filling with liquid crystal as an alignment film for PSA.

[0121] The substrate to which the liquid crystal alignment agent is applied is not particularly limited as long as it is a highly transparent substrate, and in addition to glass substrates and silicon nitride substrates, plastic substrates such as acrylic substrates and polycarbonate substrates can also be used. In this case, it is preferable to use a substrate on which an ITO electrode for driving the liquid crystal is formed in terms of simplifying the process. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a light-reflecting material such as aluminum can also be used for the electrode.

[0122] The method of applying the liquid crystal alignment agent is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, inkjet printing, etc. are generally used. Other application methods include a dip method, a roll coater method, a slit coater method, a spinner method, a spray method, etc., and these may be used depending on the purpose. After the liquid crystal alignment agent is applied to the substrate, the solvent is evaporated and baked by a heating means such as a hot plate, a heat circulation type oven, an IR (infrared) type oven, etc. The drying and baking process after the liquid crystal alignment agent is applied can be selected at any temperature and time. Although the drying process is not necessarily required, it is preferable to perform a drying process when the time from application to baking is not constant for each substrate, or when baking is not performed immediately after application. This drying is sufficient as long as the solvent is removed to an extent that the coating film shape is not deformed by transportation of the substrate, etc., and the drying means are not particularly limited. For example, a method of drying for 0.5 to 30 minutes, preferably 1 to 5 minutes, on a hot plate at a temperature of 40 to 150 ° C., preferably 60 to 100 ° C., can be mentioned.

[0123] When the liquid crystal alignment agent of the present invention is used, particularly when it is applied by an inkjet method, by containing butyl cellosolve and butyl cellosolve acetate as poor solvents, adhesion of the liquid consisting of the polyimide solution to the surface of the inkjet head is suppressed even if standby shots are performed for a long period of time, so that stable ejection is possible without precipitation on the head.

[0124] The baking temperature of the coating film formed by applying the liquid crystal alignment agent is not limited, and is, for example, 100 to 350° C., preferably 120 to 300° C., and more preferably 150 to 250° C. The baking time is 5 to 240 minutes, preferably 10 to 90 minutes, and more preferably 20 to 90 minutes. Heating can be performed by a commonly known method, for example, a hot plate, a hot air circulation oven, an infrared oven, or the like.

[0125] The thickness of the liquid crystal alignment film after baking is preferably 5 to 300 nm, more preferably 10 to 200 nm, since if it is too thin, the reliability of the liquid crystal display element may decrease. The liquid crystal alignment film of the present invention is particularly useful as a liquid crystal alignment film for IPS mode or FFS mode liquid crystal display elements.

[0126] <Liquid crystal display element and its manufacturing method> The liquid crystal display element can be produced by forming a liquid crystal alignment film on the substrate by the above method, and then producing a liquid crystal cell by a known method. A specific example of the liquid crystal display element is a horizontal alignment type liquid crystal display element having a liquid crystal cell having two substrates arranged to face each other, a liquid crystal layer provided between the substrates, and the above liquid crystal alignment film formed by a liquid crystal alignment agent provided between the substrates and the liquid crystal layer. Specifically, after applying a liquid crystal alignment agent to the two substrates and baking it, it is subjected to an alignment treatment such as rubbing treatment or photoalignment treatment, and can be used as a liquid crystal alignment film without alignment treatment for vertical alignment applications. The two substrates are arranged so that the liquid crystal alignment films face each other, and a liquid crystal layer made of liquid crystal is sandwiched between the two substrates, that is, the liquid crystal layer is provided in contact with the liquid crystal alignment film, producing a liquid crystal cell.

[0127] The substrate of the liquid crystal display element is not particularly limited as long as it is a highly transparent substrate, but is usually a substrate on which a transparent electrode for driving liquid crystal is formed. Specific examples include the same substrates as those described for the liquid crystal alignment film. A transparent glass substrate is prepared, and a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes, and are patterned to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a SiO2-TiO2 film formed by a sol-gel method.

[0128] Moreover, in highly functional elements such as TFT type elements, elements such as transistors are formed between electrodes for driving liquid crystal and a substrate.

[0129] In the case of a transmissive liquid crystal display element, the above-mentioned substrates are generally used, but in the case of a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used for only one of the substrates. In that case, a light-reflecting material such as aluminum can be used for the electrodes formed on the substrate.

[0130] The liquid crystal material constituting the liquid crystal layer of the liquid crystal display element is not particularly limited, and liquid crystal materials used in conventional horizontal alignment methods, for example, positive type liquid crystal such as MLC-3019 manufactured by Merck Co., Ltd., or negative type liquid crystal such as MLC-7026-100 manufactured by the same company, can be used. In addition, in the PSA mode, for example, liquid crystal containing a polymerizable compound represented by the following formula can be used.

[0131] [ka]

[0132] A method of sandwiching a liquid crystal layer between two substrates can include known methods. For example, a method of preparing a pair of substrates on which a liquid crystal alignment film is formed, dispersing spacers such as beads on the liquid crystal alignment film of one substrate, attaching the other substrate so that the surface on which the liquid crystal alignment film is formed faces inward, and injecting liquid crystal under reduced pressure to seal the substrate can be exemplified. A liquid crystal cell can also be produced by a method of preparing a pair of substrates on which a liquid crystal alignment film is formed, dispersing spacers such as beads on the liquid crystal alignment film of one substrate, dripping liquid crystal thereon, and then attaching the other substrate so that the surface on which the liquid crystal alignment film is formed faces inward to seal the substrate. The thickness of the spacer is preferably 1 to 30 μm, more preferably 2 to 10 μm.

[0133] The process of producing a liquid crystal cell by applying ultraviolet light while applying a voltage to the liquid crystal alignment film and the liquid crystal layer can be, for example, a method in which a voltage is applied between electrodes placed on a substrate to apply an electric field to the liquid crystal alignment film and the liquid crystal layer, and ultraviolet light is irradiated while maintaining this electric field. Here, the voltage applied between the electrodes is, for example, 5 to 30 Vp-p, preferably 5 to 20 Vp-p. The irradiation dose of ultraviolet light is, for example, 1 to 60 J / cm. 2 , preferably 40 J / cm 2 A smaller amount of ultraviolet irradiation is preferable because it can suppress a decrease in reliability caused by damage to the members constituting the liquid crystal display element, and it can also improve manufacturing efficiency by reducing the ultraviolet irradiation time.

[0134] As described above, when the liquid crystal alignment film and the liquid crystal layer are irradiated with ultraviolet light while applying a voltage, the polymerizable compound reacts to form a polymer, and the polymer memorizes the tilt direction of the liquid crystal molecules, thereby increasing the response speed of the resulting liquid crystal display element. Also, when the liquid crystal alignment film and the liquid crystal layer are irradiated with ultraviolet light while applying a voltage, the photoreactive side chains of at least one polymer selected from a polyimide precursor having a side chain that vertically aligns liquid crystals and a photoreactive side chain, and a polyimide obtained by imidizing this polyimide precursor, react with each other, or the photoreactive side chain of the polymer reacts with the polymerizable compound, thereby increasing the response speed of the resulting liquid crystal display element.

[0135] Next, polarizing plates are provided. Specifically, it is preferable to attach a pair of polarizing plates to the surfaces of the two substrates opposite to the liquid crystal layer.

[0136] In addition, the liquid crystal alignment film and liquid crystal display element of the present invention are not limited to the above configuration and manufacturing method as long as the liquid crystal alignment agent of the present invention is used, and may be manufactured by other known methods. The process from the liquid crystal alignment agent to obtaining a liquid crystal display element is disclosed, for example, in paragraphs

[0074] on page 17 to

[0082] on page 19 of JP2015-135393A.

[0137] When the polymer has a photoreactive side chain, the polymerizable compound is polymerized and the photoreactive side chains are reacted with each other or with the polymerizable compound, thereby more efficiently fixing the alignment of the liquid crystal and providing a liquid crystal display element with excellent response speed. EXAMPLES

[0138] 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 compounds and the measuring methods of each property are as follows.

[0139] (Diamine) [ka]

[0140] (Tetracarboxylic acid dianhydride) [ka]

[0141] (Terminal Modifier) Boc2O: Di-tert-butyl dicarbonate

[0142] (Additives) [ka]

[0143] s-1: 3-glycidoxypropyltriethoxysilane (Organic solvent) NMP: N-methyl-2-pyrrolidone GBL: gamma-butyrolactone BCS: Ethylene glycol monobutyl ether BCA: Ethylene glycol monobutyl ether acetate DME: Dipropylene glycol dimethyl ether PB: Propylene glycol monobutyl ether

[0144] <Measurement of imidization rate> 20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, φ5 (Kusano Scientific Co., Ltd.)), deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 ml) was added, and the mixture was sonicated to completely dissolve. This solution was measured by 500 MHz proton NMR using an NMR measurement device (JNW-ECA500) (JEOL Datum Co., Ltd.). The imidization rate was calculated by the following formula using the proton peak integrated value of this proton and the proton peak integrated value of the proton peak derived from the NH group of the amic acid that appears around 9.5 to 10.0 ppm. Imidization rate (%) = (1-α·x / y) × 100 In the above formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the peak of the reference proton, and α is the ratio of the number of reference protons to one NH group proton of the amic acid in the case of polyamic acid (imidization rate 0%).

[0145] [Polymer synthesis] <Synthesis Example 1> In a four-neck flask equipped with a stirrer and a nitrogen inlet tube, 10.3 g (42.5 mmol) of DA-1, 7.8 g (14.0 mmol) of DA-3, and 4.78 g (14.0 mmol) of DA-4 were weighed out, and NMP was added so that the solid content concentration was 15% by mass, and stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 10.2 g (45.5 mmol) of CA-1 was added, and NMP was further added so that the solid content concentration was 18% by mass. After stirring at 40°C for 1 hour, 3.57 g (18.2 mmol) of CA-2 was added at room temperature, and NMP was further added so that the solid content concentration was 18% by mass. This polymerization solution was stirred for 3 hours to obtain a polyamic acid solution (PA-I). 100.0 g of the polyamic acid solution (PA-I) obtained above was placed in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and 4.06 g (18.6 mmol) of a terminal modifier, BocO, was added. After stirring at 40°C for 15 hours, a terminal-modified polyamic acid solution (PAboc-I) was obtained. 100.0 g of the above-obtained terminal-modified polyamic acid solution (PAboc-I) was taken in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added so that the solid content concentration was 12 mass%, and the mixture was stirred for 30 minutes. 10.54 g of acetic anhydride and 2.72 g of pyridine were added to the obtained polyamic acid solution, and the mixture was stirred at room temperature for 30 minutes, and then heated and stirred at 55 ° C for 2 hours and 15 minutes to perform chemical imidization. The obtained reaction solution was poured into methanol in an amount 3.5 times the reaction solution mass while stirring, and the precipitate was filtered and then washed three times with methanol. The obtained resin powder was vacuum dried at 80 ° C for 12 hours to obtain a powder of polyimide (SPI1-1). The imidization rate of this polyimide resin powder was 75%. NMP was added to the obtained polyimide (SPI1-1) so that the solid content concentration was 15 mass %, and the mixture was stirred at 70° C. for 15 hours to obtain a solution of polyimide (SPI1-1) with a solid content concentration of 15 mass %.

[0146] <Synthesis Example 2> In a four-neck flask equipped with a stirrer and a nitrogen inlet tube, 4.18 g (10.5 mmol) of DA-2, 2.92 g (5.2 mmol) of DA-3, and 5.63 g (19.3 mmol) of DA-5 were weighed out, and NMP was added so that the solid content concentration was 19% by mass, and stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 4.51 g (22.7 mmol) of CA-5 was added, and NMP was further added so that the solid content concentration was 20% by mass. After stirring at 50°C for 1 hour, 2.31 g (11.8 mmol) of CA-2 was added at room temperature, and NMP was further added so that the solid content concentration was 20% by mass. This polymerization solution was stirred for 3 hours to obtain a polyamic acid solution (PA-II). 50.0 g of the polyamic acid solution (PA-II) obtained above was placed in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and 0.30 g (1.37 mmol) of a terminal modifier, BocO, was added. After stirring at 40°C for 15 hours, a terminal-modified polyamic acid solution (PAboc-II) was obtained. 50.0 g of the above-obtained terminal-modified polyamic acid solution (PAboc-II) was taken in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added so that the solid content concentration was 12 mass%, and the mixture was stirred for 30 minutes. 6.40 g of acetic anhydride and 2.12 g of pyridine were added to the obtained polyamic acid solution, and the mixture was stirred at room temperature for 30 minutes, and then heated and stirred at 60 ° C for 4 hours to perform chemical imidization. The obtained reaction solution was poured into methanol in an amount 3.5 times the mass of the reaction solution while stirring, and the precipitate was filtered and then washed three times with methanol. The obtained resin powder was vacuum dried at 80 ° C for 12 hours to obtain a powder of polyimide (SPI1-2). The imidization rate of this polyimide resin powder was 95%. NMP was added to the obtained polyimide (SPI1-2) so that the solid content concentration was 15 mass %, and the mixture was stirred at 70° C. for 15 hours to obtain a solution of polyimide (SPI1-2) with a solid content concentration of 15 mass %.

[0147] <Synthesis Example 3> 20.2g (47.9mmol) of DA-9 and 6.35g (32.0mmol) of DA-7 were weighed into a four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added so that the solid content concentration was 9% by mass, and the mixture was stirred and dissolved while feeding nitrogen. 15.3g (78.0mmol) of CA-2 was added while stirring this diamine solution, and NMP was further added so that the solid content concentration was 12% by mass. This polymerization solution was stirred for 5 hours to obtain a polyamic acid solution (PAA2-1).

[0148] <Synthesis Example 4> 14.3g (47.9mmol) of DA-10 and 4.81g (32.0mmol) of DA-11 were weighed into a four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added so that the solid content concentration was 15% by mass, and the mixture was stirred and dissolved while feeding nitrogen. 6.67g (34.0mmol) of CA-2 was added while stirring this diamine solution, and NMP was further added so that the solid content concentration was 15% by mass. After stirring at room temperature for 2 hours, 10.0g (40.0mmol) of CA-4 was added, and NMP was further added so that the solid content concentration was 15% by mass. This polymerization solution was stirred at 50°C for 12 hours to obtain a polyamic acid solution (PAA2-2).

[0149] <Synthesis Example 5> 29.3g (148mmol) of DA-7, 46.8g (111mmol) of DA-9, and 12.0g (111mmol) of DA-12 were weighed into a four-neck flask equipped with a stirrer and a nitrogen inlet tube, and 451g of NMP and 194g of GBL were added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution under water cooling, 55.1g (281mmol) of CA-2 and GBL were added so that the solid content concentration was 14.5% by mass, and the mixture was stirred for 2 hours under water cooling in a nitrogen atmosphere. Furthermore, 16.1g (74.0mmol) of CA-3 was added, and GBL was further added so that the solid content concentration was 15%, and the mixture was stirred for 15 hours at 50°C under a nitrogen atmosphere to obtain a polyamic acid solution (PAA2-3) with a solid content concentration of 15% and NMP / GBL=50 / 50 (mass ratio).

[0150] <Synthesis Example 6> 7.45g (26.0mmol) of DA-8 was weighed out in a four-neck flask equipped with a stirrer and a nitrogen inlet tube, 60.2g of NMP was added so that the solid content concentration was 11% by mass, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution under water cooling, 5.16g (23.6mmol) of CA-3 and NMP were added so that the solid content concentration was 12%, and this polymerization solution was stirred at 50°C for 15 hours to obtain a polyamic acid solution (PAA2-4).

[0151] <Synthesis Example 7> 7.97g (40.0mmol) of DA-6 was weighed out in a four-neck flask equipped with a stirrer and a nitrogen inlet tube, and 55.6g of NMP and 59.1g of GBL were added and stirred while feeding nitrogen to dissolve. While stirring this diamine solution under water cooling, 6.37g (32.5mmol) of CA-2 was added, and 31.3g of NMP was further added, and stirred for 3 hours under water cooling while feeding nitrogen. Next, 1.98g (10.0mmol) of DA-7 and 13.9g of GBL were added and stirred to dissolve, and then 3.00g (10.0mmol) of CA-6 and 13.9g of GBL were added and stirred for 3 hours under water cooling while feeding nitrogen to obtain a polyamic acid solution (PAA2-5) with a solid content concentration of 10% and NMP / GBL=50 / 50 (mass ratio).

[0152] <Synthesis Example 8> In a four-neck flask equipped with a stirrer and a nitrogen inlet tube, 16.4 g (82.5 mmol) of DA-7 and 16.4 g (82.5 mmol) of DA-6 were weighed out, and 240.5 g of NMP was added and stirred while feeding nitrogen to dissolve. While stirring this diamine solution under water cooling, 20.6 g (82.5 mmol) of CA-4 and NMP were added so that the solid content concentration was 15.0 mass%, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 5 hours. Further, 22.4 g (76.2 mmol) of CA-7 was added, and NMP was further added so that the solid content concentration was 15%, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 15 hours to obtain a polyamic acid solution (PAA2-6) with a solid content of 15%.

[0153] [Preparation of liquid crystal alignment agent] <Example 1> The solution of polyimide (SPI1-1) obtained in Synthesis Example 1, the polyamic acid solution (PAA2-1) obtained in Synthesis Example 3, and the polyamic acid solution (PAA2-2) obtained in Synthesis Example 4 were diluted with NMP, GBL, BCS, and BCA, and compound c-1 was added so that it was 3 parts by mass relative to 100 parts by mass of all polymers, and further compound s-1 was added so that it was 1 part by mass relative to 100 parts by mass of all polymers, and stirred at room temperature. Next, the obtained solution was filtered with a filter having a pore size of 0.5 μm to obtain a liquid crystal alignment agent (1) having a polymer component ratio of (SPI1-1):(PAA2-1):(PAA2-2)=30:40:30 (solid content equivalent mass ratio), a solvent composition ratio of NMP:GBL:BCS:BCA=30:45.9:5:15 (mass ratio), and a polymer solid content concentration of 4.1% by mass. The liquid crystal alignment agent did not show any abnormalities such as turbidity or precipitation, and was confirmed to be a homogeneous solution.

[0154] <Examples 2 to 8 and Comparative Examples 1 to 7> According to the ratio of polymer and solvent shown in Table 1 below, liquid crystal aligning agents (2) to (15) were obtained in the same manner as in Example 1 using the solutions obtained in Synthesis Examples 1 to 8.

[0155] [Table 1]

[0156] [Printability evaluation] The liquid crystal alignment agents (1) to (15) obtained above were filtered through a filter having a pore size of 1.0 μm, and then filled into an inkjet printer (IP-1212NC1180L, manufactured by Ishii Hyoku Co., Ltd.) and various evaluations were carried out.

[0157] 1. Evaluation of initial application properties The coating was applied to a glass substrate on which chromium had been evaporated at a scan speed of 500 mm / sec, a meniscus value of -4500 Pa, and a coating area of ​​65 mm (perpendicular to the scan direction) x 75 mm (parallel to the scan direction), and left at 23°C for 35 seconds. The coating was then dried on a hot plate at 90°C for 2 minutes, and then baked in a hot air circulating oven at 230°C for 20 minutes to obtain a substrate with a polyimide film of 600 Å thickness. Note that the scan pitch during coating was set to a value specific to each liquid crystal alignment agent so that the film thickness would be the same. The obtained substrate with the film was then visually observed and observed under an optical microscope (Nikon, ECLIPSE L300ND). If a uniform film was formed, it was evaluated as "good", and if unevenness or streaks were observed, it was evaluated as "poor".

[0158] 2. Evaluation of ejection stability A standby shot was carried out over a long period of time, and the liquid leakage, deposition, and coating properties on the head surface were evaluated. The standby shot is a process in which the liquid is sprayed periodically to prevent nozzle clogging.

[0159] (1) Fluid leakage from the head surface Standby shots were performed for 15 hours with an interval of 1 minute and a discharge time of 3 seconds, after which the head surface was visually observed and evaluated as "good" if there was no leakage of liquid from the head nozzles, and "poor" if liquid was attached to the head surface. (2) Spreadability Thereafter, a substrate with a polyimide film having a thickness of 600 Å was obtained in the same manner as in the evaluation of the initial coatability described above, and was observed visually and under an optical microscope. If a uniform film was formed, it was evaluated as "good," and if streaks were observed, it was evaluated as "poor." (3) Deposits on the head surface Furthermore, the head surface was wiped with a cloth (As One, Aspure Wiper AS-909), and then the cloth surface was observed visually and under an optical microscope. The results were evaluated as follows: if no precipitates were observed, it was deemed "good", and if precipitates were observed, it was deemed "poor".

[0160] The results of the evaluation of each of the liquid crystal aligning agents in Examples 1 to 8 and Comparative Examples 1 to 7, carried out as described above, are shown in Table 2 below. [Table 2]

[0161] In the evaluation of the initial coatability of the liquid crystal alignment agents of Comparative Examples 2 and 5, scaly unevenness occurred due to insufficient bonding between the liquids, and the result was "poor." In addition, in the evaluation of the ejection stability of the liquid crystal alignment agents of Comparative Examples 1, 3, 4, and 6, liquid leakage and precipitation were observed on the head after a long standby shot, and streaks along the scanning direction were observed, and the result was "poor." In addition, liquid leakage was observed for the liquid crystal alignment agent of Comparative Example 7, but no precipitation was observed, and no streaks or unevenness were confirmed. On the other hand, the liquid crystal alignment agents of the Examples did not show any streaks or unevenness either in the initial state or after the long-term standby shot, and no liquid leakage or precipitate was observed on the head surface.

[0162] For the liquid crystal alignment agents of Example 3 and Comparative Examples 4, 5, and 6, the polyimide film on the substrate obtained in the above-mentioned evaluation of initial coating properties was measured in the vertical and horizontal directions. Furthermore, 65 mm was subtracted from the measured values ​​in the vertical direction and 75 mm in the horizontal direction, respectively, and the average value was calculated as the wetting and spreading of the liquid from the coating area. In other words, the smaller this value, the better the dimensional stability. The evaluation results are shown in Table 3 below.

[0163] [Table 3]

[0164] Example 3, like Comparative Examples 4 to 6, showed little spreading and good dimensional stability.

[0165] Incidentally, the liquid crystal aligning agents of Examples 1 to 8 made it possible to prepare liquid crystal display elements free of alignment defects by a known method.

Claims

1. A liquid crystal aligning agent comprising the following (A) and (B): (A): A polyimide obtained by imidizing a polyimide precursor, which is a reaction product between a diamine component containing at least one diamine selected from the formula [2] and a tetracarboxylic acid component. 【Chemistry 1】 In the formula, A １ is a single bond, a methylene group, an ester bond, an amide bond, a cyclohexylene group, or an alkylene group having 2 to 20 carbon atoms. ２ - may be substituted with an ether group, an ester group, an amide group, a cyclohexylene group, a phenylene group, a urea group, an amino group, or a carbamate group, and any hydrogen atom of the amide group, the urea group, or the amino group may be substituted with a methyl group or a tert-butoxycarbonyl group. ２ is a fluorine atom, or an alkyl or alkoxy group having 1 to 5 carbon atoms, and any hydrogen atom of the alkyl or alkoxy group may be substituted with a fluorine atom, and any carbon atom may be substituted with an amino group protected with a tert-butoxycarbonyl group. ２ If there are multiple, A ２ may be the same or different. b and c are each independently an integer of 0 to 2, and when b is 0, c is 1 or 2; １ is an alkylene group. (B): An organic solvent containing butyl cellosolve and butyl cellosolve acetate.

2. In the above [2], A １ represents a single bond, an alkylene group having 2 to 10 carbon atoms (provided that at least one —CH ２ - is substituted with an ether group or an ester group; ２ is CH ３ 2. The liquid crystal aligning agent according to claim 1, wherein a is an integer of 0 to 1, b is 1, and c is an integer of 1 to 2.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the tetracarboxylic acid component (A) is represented by the following formula [3]: 【Chemistry 2】 In the formula, X １ is any one of the following formulas (B-1) to (B-18). 【Chemistry 3】

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the content of the diamine represented by the formula [2] is 50 mol% or more relative to 1 mol of the total diamine components.

5. X in the above formula [3] １ The liquid crystal aligning agent according to claim 3, wherein the compound is any one of (B-1), (B-2) and (B-3).

6. The content of butyl cellosolve is 5 to 20 mass% based on the total organic solvent, and the content of butyl cellosolve acetate is 5 to 20 mass% based on the total organic solvent. The liquid crystal alignment agent according to any one of claims 1 to 5.

7. The organic solvent further comprises any one of solvents (C1) selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-dimethyllactamide, and 1,3-dimethyl-2-imidazolidinone. The liquid crystal alignment agent according to any one of claims 1 to 6.

8. The liquid crystal aligning agent according to claim 7, wherein the solvent (C1) is contained in an amount of 60 to 90 mass % based on the total organic solvent contained in the liquid crystal aligning agent.

9. The organic solvent further comprises any one of solvents (C2) selected from diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone or diisobutyl ketone. The liquid crystal alignment agent according to any one of claims 1 to 8.

10. The liquid crystal alignment agent according to any one of claims 1 to 9, further comprising a crosslinkable compound and / or a functional silane-containing compound.

11. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 10.

12. A liquid crystal display device comprising the liquid crystal alignment film according to claim 11.

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