CN109791330B

CN109791330B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: CN109791330B
Application number: CN201780060320.8A
Authority: CN
Inventors: 金尔润
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2016-09-29
Filing date: 2017-09-28
Publication date: 2022-05-31
Anticipated expiration: 2037-09-28
Also published as: WO2018062437A1; JP7089228B2; CN109791330A; KR102465496B1; TW201827576A; KR20190055196A; JPWO2018062437A1; TWI754675B

Abstract

A liquid crystal aligning agent, comprising: at least 1 polymer selected from polyamic acid and imidized polymer of the polyamic acid, and organic solvent, wherein the polyamic acid is prepared by mixing the following components in a ratio of 10: 90-90: the ratio of 10 is obtained by including tetracarboxylic dianhydride represented by the following formula (1), tetracarboxylic acid of aliphatic tetracarboxylic dianhydride and diamine including diamine represented by the following formula (2).

Description

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

Technical Field

The present invention relates to a liquid crystal aligning agent and a liquid crystal alignment film for a liquid crystal display element, and a liquid crystal display element using the same.

Background

Liquid crystal devices have been widely used as display units of personal computers, mobile phones, television receivers, and the like. The liquid crystal device includes, for example: a liquid crystal layer interposed between the element substrate and the color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling alignment of liquid crystal molecules in the liquid crystal layer, a Thin Film Transistor (TFT) for converting an electric signal supplied to the pixel electrode, and the like. As a driving method of liquid crystal molecules, a longitudinal electric field method such as a TN method and a VA method; a lateral electric field system such as an IPS system or a boundary electric field switching (hereinafter, referred to as FFS) system (for example, patent document 1).

In recent years, however, the liquid crystal display element and the organic EL element are also economically important in the production process, and therefore, the recycling of the element substrate is required. That is, when defects occur due to the inspection of alignment properties or the like after the formation of the liquid crystal alignment film by the liquid crystal alignment agent, it is required to easily perform a reworking step of removing the liquid crystal alignment film from the substrate and recovering the substrate. However, the liquid crystal alignment film obtained from the liquid crystal aligning agent proposed in the related art is intended to reduce film loss by not dissolving in an organic solvent or the like after post-baking. Even if the liquid crystal aligning agent composition, which has been studied for reworkability, is used as it is for the liquid crystal aligning agent for a transverse electric field, the desired object cannot be achieved, and it is necessary to actually evaluate whether the liquid crystal aligning agent has excellent reworkability again and to investigate the optimum composition configuration again.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2013-167782

Disclosure of Invention

Problems to be solved by the invention

The invention aims to provide a liquid crystal aligning agent which can obtain a liquid crystal aligning film with excellent reprocessing performance.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that a liquid crystal alignment film having excellent reworkability can be obtained by using a polyamic acid obtained from a tetracarboxylic acid containing a specific aromatic tetracarboxylic dianhydride and an aliphatic tetracarboxylic dianhydride and a diamine having a specific structure, and an imidized polymer of the polyamic acid, and have completed the present invention.

The present invention is based on the above findings, and has the following gist.

1. A liquid crystal aligning agent, comprising: at least 1 polymer selected from polyamic acid and imidized polymer of the polyamic acid, and organic solvent, wherein the polyamic acid is prepared by mixing 10: 90-90: the ratio of 10 is obtained by including a tetracarboxylic dianhydride component of a tetracarboxylic dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic dianhydride, and a diamine component of a diamine represented by the following formula (2).

(in the formula (1), i is 0 or 1, X is a single bond, ether bond, carbonyl, ester bond, phenylene, C1-20 linear alkylene, C2-20 branched alkylene, C3-12 cyclic alkylene, sulfonyl, amido bond or a group formed by combination of the above, wherein the C1-20 alkylene is optionally interrupted by a bond selected from ester bond and ether bond, and the carbon atoms of the phenylene and the alkylene are optionally substituted by 1 or more same or different substituents selected from halogen atom, cyano group, alkyl group, halogenated alkyl group, alkoxy group and halogenated alkoxy group.

In the formula (2), Y₁Is a 2-valent organic group having at least 1 structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, or is a 2-valent organic group selected from the group consisting of an amino group, an imino group and an nitrogen-containing heterocyclic ring substituted on the nitrogen atom with a thermally releasable group, B₁、B₂Each independently represents a hydrogen atom, or an optionally substituted alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms. )

2. The liquid crystal aligning agent according to 1, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component is a tetracarboxylic dianhydride represented by the formula (1) or an aliphatic tetracarboxylic dianhydride.

3. The liquid crystal aligning agent according to 1 or 2, wherein 10 to 100 mol% of the diamine component is a diamine of the formula (2).

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein Y in the formula (2)₁Is at least 1 selected from the following structures of formulas (YD-1) to (YD-5).

(in the formula (YD-1), A₁Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms, Z₁Is a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms. In the formula (YD-2), W₁Is a C1-10 hydrocarbon group, A₂Is a C3-15 organic group having a nitrogen atom-containing heterocycle, or a disubstituted amino group substituted with a C1-6 aliphatic group. In formula (YD-3)，W₂A C6-15 and a 2-valent organic group having 1-2 benzene rings, W₃Is alkylene or biphenylene having 2 to 5 carbon atoms, Z₂Is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a benzene ring or a thermally releasable group, and a is an integer of 0 to 1. In the formula (YD-4), A₃Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms. In the formula (YD-5), A₄Is a C3-15 nitrogen atom-containing heterocycle, W₅Is an alkylene group having 2 to 5 carbon atoms. )

5. The liquid crystal aligning agent according to claim 4, wherein A is represented by the formulae (YD-1), (YD-2), (YD-4) and (YD-5)₁、A₂、A₃And A₄Is at least 1 selected from the group consisting of pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyrazine, indole, benzimidazole, quinoline, and isoquinoline.

6. The liquid crystal aligning agent according to any one of claims 1 to 5, wherein Y in the formula (2)₁Is at least 1 selected from the group consisting of 2-valent organic groups having the following structures of formulae (YD-6) to (YD-21).

(in the formula (YD-17), h is an integer of 1-3, and in the formulae (YD-14) and (YD-21), j is an integer of 1-3.)

7. The liquid crystal aligning agent according to claim 6, wherein Y in the formula (2)₁Is at least 1 selected from the group consisting of 2-valent organic groups having the structures of the above-described formulae (YD-14) and (YD-18).

8. The liquid crystal aligning agent according to any one of claims 1 to 7, wherein the tetracarboxylic dianhydride represented by the formula (1) is 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride.

9. The liquid crystal aligning agent according to any one of claims 1 to 8, wherein the aliphatic tetracarboxylic dianhydride is bicyclo [3.3.0] octane 2,4,6,8-tetracarboxylic acid 2,4:6,8-dianhydride (bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid-2,4:6, 8-dianhydide).

10. A liquid crystal alignment film obtained by applying the liquid crystal alignment agent of any one of 1 to 9 and firing the same.

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

ADVANTAGEOUS EFFECTS OF INVENTION

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention has excellent reworkability.

Detailed Description

The liquid crystal aligning agent of the present invention is characterized by containing: at least 1 polymer selected from polyamic acid and imide polymer of the polyamic acid, and organic solvent, wherein the polyamic acid is obtained by using tetracarboxylic acid component containing tetracarboxylic dianhydride represented by the following formula (1) and aliphatic tetracarboxylic acid dianhydride, and diamine component containing diamine represented by the following formula (2).

In the formula (1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl group, an ester bond, a phenylene, a linear alkylene with 1-20 carbon atoms, a branched alkylene with 2-20 carbon atoms, a cyclic alkylene with 3-12 carbon atoms, a sulfonyl group, an amido bond or a group formed by combining the two, wherein the alkylene with 1-20 carbon atoms is optionally interrupted by a bond selected from the ester bond and the ether bond, and the carbon atoms of the phenylene and the alkylene are optionally substituted by 1 or more same or different substituents selected from a halogen atom, a cyano group, an alkyl group, a halogenated alkyl group, an alkoxy group and a halogenated alkoxy group.

In the formula (2), Y₁Is a 2-valent organic group having at least 1 structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, or is a 2-valent organic group selected from the group consisting of an amino group, an imino group and an nitrogen-containing heterocyclic ring substituted on the nitrogen atom with a thermally releasable group, B₁、B₂Each independently represents a hydrogen atom, or an optionally substituted alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms.

Hereinafter, each of the constituent features will be described in detail.

< tetracarboxylic dianhydride component >

Examples of the tetracarboxylic dianhydride represented by the formula (1) include, but are not limited to, the following compounds.

(wherein q represents an integer of 1 to 20.)

Among the tetracarboxylic dianhydrides represented by the formula (1), the tetracarboxylic dianhydride in which i is 1 in the formula (1), that is, the tetracarboxylic dianhydride having 2 or more benzene rings is preferable from the viewpoint of an excellent effect of improving the reworkability, and among the specific examples, (1-2) to (1-11) are preferable, and from the viewpoint of containing a biphenyl structure and having a rigid structure, the 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride represented by the formula (1-5) is particularly preferable.

Specific examples of the aliphatic tetracarboxylic dianhydride used in the present invention include tetracarboxylic dianhydrides represented by the following formula (3).

In the formula, X₁Is any one of the following (X-1) to (X-28).

In the formula (X-1), R₃～R₆Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a phenyl group, and more preferably a hydrogen atom or a methyl group.

Among the above, (X-1) to (X-20) are preferable from the viewpoint of not containing an aromatic moiety, and (X-10) is most preferable from the viewpoint of being particularly less likely to cause thermal imidization.

If the total amount of the tetracarboxylic dianhydride represented by formula (1) and the aliphatic acid dianhydride is too small in the total tetracarboxylic dianhydride component used for producing component (a) of the present invention, the effects of the present invention cannot be obtained. Therefore, the total amount of the tetracarboxylic dianhydride and the aliphatic acid dianhydride represented by the formula (1) is preferably 10 to 100 mol%, more preferably 50 to 100 mol%, and still more preferably 80 to 100 mol% based on 1 mol of the total tetracarboxylic dianhydride.

The content ratio of the tetracarboxylic dianhydride and the aliphatic acid dianhydride represented by the formula (1) is 10: 90-90: 10, preferably 20: 80-80: 20. more preferably 40: 60-60: 40, particularly preferably 46: 54-54: 46, most preferably substantially equal amounts.

The tetracarboxylic dianhydride represented by the formula (1) and the aliphatic tetracarboxylic dianhydride may be used individually or in combination in plural, and in this case, the tetracarboxylic dianhydride represented by the formula (1) and the aliphatic tetracarboxylic dianhydride are preferably used in the above-described preferred amounts in total.

The polyamic acid contained in the liquid crystal aligning agent of the present invention may be a tetracarboxylic dianhydride represented by the following formula (4) in addition to the tetracarboxylic dianhydride and the aliphatic tetracarboxylic dianhydride represented by the formula (1).

In the formula (4), X is a 4-valent organic group, and the structure thereof is not particularly limited. Specific examples thereof include those represented by the following formulae (X-31) to (X-36).

< diamine component >

The diamine component used for the production of the liquid crystal aligning agent of the present invention contains the diamine of the formula (2). In the formula (2), Y₁Is a 2-valent organic group having at least 1 structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring,or a 2-valent organic radical selected from amino, imino and azacyclo substituted on the nitrogen atom by a thermally dissociable group, B₁、B₂Each independently represents a hydrogen atom, or an optionally substituted alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms.

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the alkenyl group include those obtained by substituting 1 or more CH — CH structures present in the above-mentioned alkyl group with a C ═ C structure, and more specifically, vinyl, allyl, 1-propenyl, isopropenyl, 2-butenyl, 1, 3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl and the like. Examples of the alkynyl group include 1 or more CH groups present in the above-mentioned alkyl group₂-CH₂Examples of the group having a structure substituted by a C.ident.C structure include ethynyl, 1-propynyl and 2-propynyl.

The alkyl group, alkenyl group and alkynyl group may have a substituent as long as the carbon number of the whole group is 1 to 10, and may form a ring structure via the substituent. The term "form a ring structure by a substituent" means that substituents are bonded to each other or a part of a parent skeleton to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a mercapto group, a nitro group, an aryl group, an organooxy group, an organothio group, an organosilyl group, an acyl group, an ester group, a thioester group, a phosphate group, an amide group, an alkyl group, an alkenyl group, and an alkynyl group.

Examples of the halogen group as a substituent include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the aryl group as a substituent include a phenyl group. The aryl group is optionally further substituted with other substituents as described above.

As the organic oxy group as a substituent, a structure represented by O-R can be shown. The R groups may be the same or different, and may be, for example, alkyl, alkenyl, alkynyl, aryl, or the like. These R are optionally further substituted with the aforementioned substituents. Specific examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, and the like.

As the organic thio group as a substituent, a structure represented by-S-R can be illustrated. Examples of the R include the alkyl group, alkenyl group, alkynyl group, and aryl group. These R are optionally further substituted with the aforementioned substituents. Specific examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

As the organosilyl group as a substituent, -Si- (R)₃The structure shown. The R groups may be the same or different, and may be, for example, alkyl, alkenyl, alkynyl, aryl, or the like. These R are optionally further substituted with the aforementioned substituents. Specific examples of the alkylsilyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a tripentylsilyl group, a trihexylsilyl group, a pentyldimethylsilyl group, and a hexyldimethylsilyl group.

The acyl group as a substituent may have a structure represented by-C (O) -R. Examples of the R include the alkyl group, the alkenyl group, and the aryl group. These R are optionally further substituted with the aforementioned substituents. Specific examples of the acyl group include formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, benzoyl and the like.

The ester group as a substituent may have a structure represented by-C (O) O-R or-OC (O) R. Examples of the R include the alkyl group, alkenyl group, alkynyl group, and aryl group. These R are optionally further substituted with the aforementioned substituents.

The thioester group as a substituent may have a structure represented by-C (S) O-R or-OC (S) -R. Examples of the R include the alkyl group, alkenyl group, alkynyl group, and aryl group. These R are optionally further substituted with the aforementioned substituents.

As the phosphate group as a substituent, there may be mentioned-OP (O) - (OR)₂The structure shown. R may be the sameThe alkyl group, alkenyl group, alkynyl group, aryl group, and the like may be exemplified. These R are optionally further substituted with the aforementioned substituents.

As the amide group as a substituent, there may be mentioned-C (O) NH₂or-C (O) NHR, -NHC (O) R, -C (O) N (R)₂-NRC (O) R. The R groups may be the same or different, and may be, for example, alkyl, alkenyl, alkynyl, aryl, or the like. These R are optionally further substituted with the aforementioned substituents.

Examples of the aryl group as a substituent include the same ones as those of the above-mentioned aryl group. The aryl group is optionally further substituted with other substituents as described above.

Examples of the alkyl group as a substituent include the same ones as those of the above alkyl group. The alkyl group is optionally further substituted with other substituents as described above.

Examples of the alkenyl group as the substituent include the same ones as those described above. The alkenyl group is optionally further substituted with the other substituents described above.

Examples of the alkynyl group as a substituent include the same ones as those described above. The alkynyl group is optionally further substituted with other substituents as described above.

In general, when a bulky structure is introduced, the reactivity of amino groups and the liquid crystal alignment properties may be lowered, and therefore, B is a structure₁And B₂More preferred is a hydrogen atom or an optionally substituted alkyl group having 1 to 5 carbon atoms, and particularly preferred is a hydrogen atom, a methyl group or an ethyl group.

As Y in formula (2)₁The structure of (b) is not particularly limited as long as it has at least 1 structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocycle, or at least 1 structure selected from an amino group, an imino group and a nitrogen-containing heterocycle substituted with a thermally dissociable group on a nitrogen atom. Specific examples thereof include 2-valent organic groups having at least 1 structure selected from the group consisting of amino groups, imino groups, and nitrogen-containing heterocycles, represented by the following formulae (YD-1) to (YD-5).

In the formula (YD-1), A₁Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms, Z₁Is a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms.

In the formula (YD-2), W₁Is a C1-10 hydrocarbon group, A₂Is a C3-15 organic group having a nitrogen atom-containing heterocycle, or a disubstituted amino group substituted with a C1-6 aliphatic group.

In the formula (YD-3), W₂A C6-15 and a 2-valent organic group having 1-2 benzene rings, W₃Is alkylene or biphenylene having 2 to 5 carbon atoms, Z₂Is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a benzene ring or a thermally releasable group, and a is an integer of 0 to 1.

In the formula (YD-4), A₃Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms.

In the formula (YD-5), A₄Is a C3-15 nitrogen atom-containing heterocycle, W₅Is an alkylene group having 2 to 5 carbon atoms. )

A as formulae (YD-1), (YD-2), (YD-4) and (YD-5)₁、A₂、A₃And A₄The nitrogen-containing heterocycle of 3 to 15 carbon atoms is not particularly limited as long as it has a known structure. Among them, pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyrazine, indole, benzimidazole, quinoline, isoquinoline, carbazole are mentioned, and piperazine, piperidine, indole, benzimidazole, imidazole, carbazole and pyridine are more preferable.

The thermally releasable group may be a substituent which is not released at room temperature but is released at the time of firing of the alignment film and is substituted with a hydrogen atom, and specific examples thereof include a tert-butoxycarbonyl group and a 9-fluorenylmethoxycarbonyl group.

Further, as Y in the formula (2)₂Specific examples of (A) include 2-valent organic groups having a nitrogen atom represented by the following formulae (YD-6) to (YD-52), and more preferably formulae (YD-14) to (YD-21), particularly preferably formula (YD-14) to (YD-21), in order to suppress charge accumulation due to AC driveSelecting (YD-14) and (YD-18).

In the formulae (YD-14) and (YD-21), j is an integer of 0 to 3.

In the formulae (YD-24), (YD-25), (YD-28) and (YD-29), j is an integer of 0 to 3. In the formula (YD-17), h is an integer of 1 to 3.

(in the formula (YD-50), m and n are integers of 1-11 and m + n is an integer of 2-12.)

The ratio of the diamine represented by formula (2) in the polyamic acid and the imidized polymer of polyamic acid according to the present invention is preferably 10 to 100 mol%, more preferably 30 to 100 mol%, and further preferably 50 to 100 mol% with respect to 1 mol of all the diamines.

The diamine represented by the formula (2) in the polyamic acid and the imidized polymer of the polyamic acid as the component (a) of the present invention may be used alone or in combination of two or more, and in this case, it is preferable to use the above-mentioned preferable amount of the total of the diamines represented by the formula (2).

The polyamic acid contained in the liquid crystal aligning agent of the present invention may be a diamine represented by the following formula (5) in addition to the diamine represented by the above formula (2). Y in the following formula (5)₂The organic group is a 2-valent organic group, and the structure thereof is not particularly limited, and 2 or more kinds thereof may be mixed. Specific examples thereof include the following (Y-1) to (Y-49) and (Y-57) to (Y-97).

H₂N-Y₂-NH₂ (5)

The ratio of the diamine represented by the formula (5) in the polyamic acid and the imidized polymer of the polyamic acid as the component (a) contained in the liquid crystal aligning agent of the present invention is not preferable because the effect of the present invention may be impaired. Therefore, the proportion of the diamine represented by the formula (5) is preferably 0 to 90 mol%, more preferably 0 to 50 mol%, and still more preferably 0 to 20 mol% based on 1 mol of the total diamines.

< method for producing Polyamic acid >

The polyamic acid used as the polyimide precursor in the present invention can be synthesized by the following method.

Specifically, the tetracarboxylic acid dianhydride and the diamine can be synthesized by reacting at-20 to 150 ℃, preferably 0 to 70 ℃ for 30 minutes to 24 hours, preferably 1 to 12 hours in the presence of an organic solvent.

The organic solvent used in the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ -butyrolactone, or the like, and 1 or 2 or more thereof may be used in combination, from the viewpoint of solubility of the monomer and the polymer.

The concentration of the polymer is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that the polymer is less likely to precipitate and a high molecular weight product is easily obtained.

The polyamic acid obtained in the above-described manner can be recovered by precipitating a polymer by pouring the reaction solution into a poor solvent while sufficiently stirring the reaction solution. Further, the polyamic acid is precipitated several times, washed with a poor solvent, and dried at room temperature or heated to obtain a purified polyamic acid powder. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene, and the like, and water, methanol, ethanol, 2-propanol, and the like are preferable.

< method for producing polyimide >

The polyimide used in the present invention can be produced by imidizing the polyamic acid.

In the case of producing a polyimide from a polyamic acid, chemical imidization by adding a catalyst to a solution of the polyamic acid obtained by reacting a diamine component with a tetracarboxylic dianhydride is simple. Chemical imidization is preferred because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is less likely to decrease during the imidization.

Chemical imidization can be carried out by stirring a polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, a solvent used in the polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferable because it has a suitable basicity for advancing the reaction. The acid anhydride may be acetic anhydride, trimellitic anhydride, pyromellitic anhydride, or the like, and among these, acetic anhydride is preferable because purification after completion of the reaction is easy.

The temperature for the imidization is-20 to 140 ℃, preferably 0 to 100 ℃, and the reaction time may be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times by mol, preferably 2 to 20 times by mol, and the amount of the acid anhydride is 1 to 50 times by mol, preferably 3 to 30 times by mol, based on the amount of the polyamic acid group. The imidization rate of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature and the reaction time.

Since the added catalyst and the like remain in the solution after the imidization reaction of the polyamic acid, it is preferable to recover the obtained imidized polymer by the following means and redissolve it with an organic solvent to prepare the liquid crystal aligning agent of the present invention.

The solution of polyimide obtained as described above can be injected into a poor solvent with sufficient stirring to precipitate a polymer. Precipitation was performed several times and washed with a poor solvent, followed by drying at normal temperature or drying by heating, whereby a purified polymer powder could be obtained.

The poor solvent is not particularly limited, and examples thereof include methanol, 2-propanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene, and methanol, ethanol, 2-propanol, and acetone are preferable.

< liquid Crystal alignment agent >

The liquid crystal aligning agent used in the present invention is in the form of a solution in which a polymer component is dissolved in an organic solvent. The molecular weight of the polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000 in terms of weight average molecular weight. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.

The polymer concentration of the liquid crystal aligning agent used in the present invention may be appropriately changed depending on the setting of the thickness of a coating film to be formed, and is preferably 1 mass% or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10 mass% or less from the viewpoint of the storage stability of a solution. The concentration of the polymer is particularly preferably 2 to 8 mass%.

The organic solvent contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as it is a solvent that uniformly dissolves the polymer component. Specific examples thereof include N, N-dimethylformamide, N-diethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ -butyrolactone, 1, 3-dimethylimidazolidinone, and 3-methoxy-N, N-dimethylpropionamide. These may be used in 1 kind or in combination of 2 or more kinds. The solvent which cannot uniformly dissolve the polymer component alone may be mixed with the organic solvent as long as the polymer does not precipitate.

In addition, a mixed solvent in which a solvent that improves coatability or surface smoothness of a coating film at the time of coating the liquid crystal aligning agent is used in combination with the above-mentioned solvent is generally used as the organic solvent contained in the liquid crystal aligning agent, and such a mixed solvent is also preferably used in the liquid crystal aligning agent of the present invention. Specific examples of the organic solvent used in combination are given below, but the organic solvent is not limited to these examples.

Examples thereof include ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, t-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentanol, t-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 2, 6-dimethyl-4-heptanol, isobutanol, 2-methyl-1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-pentanol, 3-methyl-1-butanol, 2-methyl-1-heptanol, 2-6-dimethyl-4-heptanol, 2-butanol, 2-methyl-hexanol, 2-methyl-2-methyl-1-2-pentanol, 2-methyl-2-hexanol, 2-methyl-2-methyl-1-pentanol, 2-methyl-2-methyl-ethyl-1-hexanol, 2-methyl-butanol, 2-methyl-ethyl-butanol, 2-methyl-2-butanol, 2-ethyl-pentanol, 2-methyl-ethyl-2, 2-methyl-2-ethyl-methyl-2-hexanol, 2-methyl-2, 2-ethyl-2, 2-methyl-2, 2-methyl-ethyl-pentanol, 2-methyl-ethyl-1-2, 2-ethyl-2, 2-ethyl-2-pentanol, 2-methyl-2, 2-methyl-ethyl-2-ethyl-2, 2-ethyl-methyl-ethyl-2, 2-methyl-2, 2-methyl-2-methyl-ethyl-methyl-ethyl-methyl-pentanol, 2-hexanol, 2-methyl-2, 2-methyl-ethyl alcohol, 2-ethyl alcohol, 2, 1, 2-ethanediol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2-ethyl-1, 3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, 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, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 2, 6-dimethyl-4-heptanone, 4, 6-dimethyl-2-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monobutyl ether, 1- (butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol methyl ether, and mixtures thereof, Tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, 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, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, propyl 3-methoxypropionate, propyl acetate, methyl acetate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, ethyl acetate, Butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and solvents represented by the following formulae [ D-1] to [ D-3 ].

Formula [ D-1]]In (D)¹Represents an alkyl group having 1 to 3 carbon atoms of the formula [ D-2 ]]In (D)²Represents an alkyl group having 1 to 3 carbon atoms, formula [ D-3]]In (D)³Represents an alkyl group having 1 to 4 carbon atoms.

Among them, preferable combinations of solvents include: n-methyl-2-pyrrolidone, gamma-butyrolactone, and ethylene glycol monobutyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone and propylene glycol monobutyl ether; n-ethyl-2-pyrrolidone and propylene glycol monobutyl ether; n-methyl-2-pyrrolidone, γ -butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and 2, 6-dimethyl-4-heptanone; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether; n-methyl-2-pyrrolidone, gamma-butyrolactone, propylene glycol monobutyl ether, and 2, 6-dimethyl-4-heptanol; n-methyl-2-pyrrolidone, gamma-butyrolactone and dipropylene glycol dimethyl ether. The kind and content of such a solvent are appropriately selected depending on the coating apparatus, coating conditions, coating environment, and the like of the liquid crystal aligning agent.

In addition, the following additives may be added to the liquid crystal aligning agent of the present invention in order to improve the mechanical strength of the film.

The additive is preferably 0.1 to 30 parts by mass per 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. When the amount is less than 0.1 part by mass, no effect is expected, and when the amount is more than 30 parts by mass, the liquid crystal alignment property is lowered, and therefore, the amount is more preferably 0.5 to 20 parts by mass.

In addition to the above, the liquid crystal aligning agent of the present invention may be added within a range not to impair the effects of the present invention: a polymer other than a polymer; a dielectric or conductive substance for changing electric characteristics such as a 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 crosslinkable compound for improving film hardness and density when the liquid crystal alignment film is produced; and an imidization accelerator for efficiently promoting imidization of polyamic acid during baking of the coating film.

< liquid Crystal alignment film >

< method for producing liquid Crystal alignment film >

The liquid crystal alignment film of the present invention is obtained by coating the liquid crystal alignment agent on a substrate, drying the coating, and baking the coating. The substrate to which the liquid crystal aligning agent of the present invention is applied is not particularly limited as long as it is a substrate having high transparency, and a plastic substrate such as a glass substrate, a silicon nitride substrate, an acrylic substrate, or a polycarbonate substrate can be used. In the reflective liquid crystal display element, an opaque material such as a silicon wafer may be used as long as it is a single-sided substrate, and a material that reflects light such as aluminum may be used for the electrodes in this case.

Examples of the method for applying the liquid crystal aligning agent of the present invention include spin coating, printing, and ink jet. The drying and firing steps after the application of the liquid crystal aligning agent of the present invention can be carried out at any temperature and for any time. In order to sufficiently remove the organic solvent contained therein, the organic solvent is usually dried at 50 to 120 ℃ for 1 to 10 minutes and then fired at 150 to 300 ℃ for 5 to 120 minutes. The thickness of the coating film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, and therefore, it is 5 to 300nm, preferably 10 to 200 nm.

Examples of the method for aligning the liquid crystal alignment film include a brush rubbing method and a photo-alignment treatment method. The brushing treatment can be performed by using an existing brushing apparatus. Examples of the material of the brush polishing cloth in this case include cotton, nylon, rayon, and the like. The conditions for the brushing treatment are generally 300 to 2000rpm in rotation speed, 5 to 100mm/s in feed speed, and 0.1 to 1.0mm in pressing amount. Subsequently, the residue generated by the brushing is removed by ultrasonic cleaning using pure water, alcohol, or the like.

Specific examples of the photo-alignment treatment method include the following methods: and (c) irradiating the surface of the coating film with a radiation beam polarized in a predetermined direction, and optionally heating the coating film at a temperature of 150 to 250 ℃ to impart an alignment ability to the liquid crystal. As the radiation, a radiation having a wavelength of 100nm to 800nm can be usedUltraviolet and visible light. Among these, ultraviolet rays having a wavelength of 100nm to 400nm are preferable, and ultraviolet rays having a wavelength of 200nm to 400nm are particularly preferable. In addition, in order to improve the liquid crystal alignment, the coated substrate may be irradiated with radiation while being heated at 50 to 250 ℃. The irradiation amount of the radiation is preferably 1 to 10,000mJ/cm²Particularly preferably 100 to 5,000mJ/cm². The liquid crystal alignment film prepared as described above can stably align liquid crystal molecules in a certain direction.

The higher the extinction ratio of polarized ultraviolet rays, the higher the anisotropy can be imparted, and therefore, this is preferable. Specifically, the extinction ratio of the linearly polarized ultraviolet rays is preferably 10:1 or more, more preferably 20:1 or more.

The film irradiated with polarized radiation as described above may be subsequently subjected to a contact treatment with a solvent containing at least 1 selected from water and organic solvents.

The solvent used in the contact treatment is not particularly limited as long as it dissolves a decomposition product generated by light irradiation. Specific examples thereof include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. These solvents may be used in combination of 2 or more.

From the viewpoint of versatility and safety, at least 1 selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate is more preferable. Particularly preferred are water, 2-propanol, and a mixed solvent of water and 2-propanol.

In the present invention, the contact treatment of the film irradiated with the polarized radiation and the solution containing the organic solvent is performed by a treatment which can preferably bring the film into sufficient contact with the liquid, such as a dipping treatment or a spraying (spray) treatment. Among them, a method of immersing the film in a solution containing an organic solvent for preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferable. The contact treatment may be carried out at normal temperature or under heating, and is preferably carried out at 10 to 80 ℃ and more preferably at 20 to 50 ℃. Further, means for improving the contact such as ultrasonic waves may be applied as necessary.

After the contact treatment, either or both of rinsing (rinsing) 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 to remove the organic solvent in the solution used.

Further, the film subjected to the contact treatment with the solvent may be heated at 150 ℃ or higher for drying the solvent and reorienting the molecular chains in the film.

The heating temperature is preferably 150 to 300 ℃. The higher the temperature, the more the reorientation of the molecular chain is promoted, but if the temperature is too high, the decomposition of the molecular chain may be accompanied. Therefore, the heating temperature is more preferably 180 to 250 ℃, and particularly preferably 200 to 230 ℃.

If the heating time is too short, the effect of reorienting the molecular chains may not be obtained, and if it is too long, the molecular chains may be decomposed, and therefore, it is preferably 10 seconds to 30 minutes, more preferably 1 minute to 10 minutes.

The obtained liquid crystal alignment film is easily dissolved in a reworkable material and has excellent reworkability.

Examples of the solvent used for the reprocessing include: glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether; glycol esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, and propylene glycol propyl ether acetate; glycols such as diethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; alcohols such as methanol, ethanol, 2-propanol, and butanol; ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and γ -butyrolactone; esters such as methyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl glycolate, methyl 2-hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, and butyl lactate; amides such as N, N-dimethylformamide, N-dimethylacetamide and N-methyl-2-pyrrolidone.

As the reworking material, it is preferable that the solvent contains an alkaline component such as ethanolamine and a rust inhibitor so that the alkalinity does not damage other members such as electrodes. The manufacturer for providing such reworked materials includes Korea Hui Ming Industrial Co., Ltd., KPX chemical, etc.

The reprocessing is performed by the following steps: the reworked material mentioned above is immersed in the substrate with the liquid crystal alignment film at room temperature or after heating to 30 to 100 ℃ for 1 to 1000 seconds, preferably 30 to 500 seconds; or the reworked material is sprayed in a shower type, and then the liquid is removed and washed with an alcohol solvent or pure water. From the viewpoint of work efficiency, the temperature of the reprocessing liquid at the time of reprocessing is preferably low, and is usually room temperature to 60 ℃, and more preferably room temperature to 40 ℃.

< liquid Crystal display element >

The liquid crystal display element of the present invention is obtained as follows: after a substrate with a liquid crystal alignment film is obtained from the liquid crystal alignment agent of the present invention by the above-described method for producing a liquid crystal alignment film, a liquid crystal cell is prepared by a known method, and a liquid crystal display element is produced using the liquid crystal cell.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Note that the liquid crystal display element may be an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting image display.

First, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and segment electrodes are provided on the other substrate. These electrodes may be formed as ITO electrodes, for example, and patterned so that desired image display can be performed. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film may be made of, for example, SiO formed by a sol-gel method₂-TiO₂The film formed.

Next, the liquid crystal alignment film of the present invention is formed on each substrate by the above-described method.

Next, one substrate was stacked on the other substrate so that the alignment film surfaces thereof were opposed to each other, and the periphery was bonded with a sealant. In the sealant, a spacer is usually mixed in advance in order to control a substrate gap. In addition, it is preferable that spacers for controlling the substrate gap are dispersed in advance in the surface portion where the sealing agent is not provided. An opening capable of being filled with liquid crystal from the outside is provided in advance in a part of the sealant.

Next, a liquid crystal material was injected into the space surrounded by the 2 substrates and the sealant through the opening provided in the sealant. Then, the opening is sealed with an adhesive. The injection may be performed by a vacuum injection method or a method using a capillary phenomenon in the atmosphere. Next, a polarizing plate was disposed. Specifically, a pair of polarizing plates was attached to the surface of the 2-sheet substrate opposite to the liquid crystal layer. The liquid crystal display element of the present invention is obtained through the above steps.

In the present invention, as the sealing agent, for example, a resin having a reactive group such as an epoxy group, an acryloyl group, a methacryloyl group, a hydroxyl group, an allyl group, or an acetyl group, which is cured by ultraviolet irradiation or heating, can be used. In particular, a curable resin system having both an epoxy group and a (meth) acryloyl group is preferably used.

The sealant of the present invention may contain an inorganic filler for the purpose of improving adhesiveness and moisture resistance. The inorganic filler that can be used is not particularly limited, and specific examples thereof include spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, and asbestos, and preferably spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, aluminum hydroxide, calcium silicate, and aluminum silicate. The inorganic filler may be used in a mixture of 2 or more.

Since the liquid crystal display element uses the liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film of the present invention as a liquid crystal alignment film, the liquid crystal display element has excellent reworkability and can be suitably used for a large-screen and high-definition liquid crystal television or the like.

Examples

The details of the production method of the present invention will be described below by referring to experimental methods for investigating the raw material composition and the compounding ratio, results thereof, and examples of typical production methods. The present invention is not limited to these examples.

Description of abbreviations used in the present embodiment

(organic solvent)

NMP: n-methyl-2-pyrrolidone

GBL: gamma-butyrolactone

BCS: butyl cellosolve

Acid dianhydride (a): the following formula (A)

Acid dianhydride (B): the following formula (B)

Acid dianhydride (C): the following formula (C)

Acid dianhydride (D): the following formula (D)

DA-1: the following formula (DA-1)

DA-2: the following formula (DA-2)

DA-3: the following formula (DA-3)

DA-4: the following formula (DA-4)

DA-5: the following formula (DA-5)

The following description will be made of methods for measuring viscosity, imidization ratio, reworkability, production of liquid crystal cell, and charge relaxation property.

[ measurement of viscosity ]

In the synthesis examples, the viscosities of the polyamic acid ester and the polyamic acid solution were measured using an E-type viscometer TV-25H (manufactured by Toyobo Co., Ltd.) under conditions of a sample volume of 1.1mL, CORD-1(1 ℃ 34', R24), and a temperature of 25 ℃.

[ evaluation of reworkability ]

The liquid crystal aligning agent of the present invention is coated on an ITO substrate by a spin coating method. After drying on a hot plate at 60 ℃ for 1 minute and 30 seconds, the film was baked in a hot air circulating oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100 nm. Then, the prepared substrate was immersed in a reworked material (HM-R20) heated to 55 ℃ for 300 seconds and developed, and then washed with running water with ultrapure water for 20 seconds. Then, air blowing was performed to make the cell large when the liquid crystal alignment film completely disappeared and small when there was a residue. The results obtained for the cases where the predetermined temperatures of the reworked liquid were 35 ℃ and 55 ℃ are shown in table 3.

Comparative polymerization example 1

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.96g of (DA-4) were added to the mixture, and NMP25.7g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 3.00g of acid dianhydride (C) and further 11.2g of NMP11 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, and then 0.77g of acid dianhydride (D) and further 4.4g of NMP4 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 50 ℃ for 16 hours to obtain a polyamic acid solution (PAA-1). The polyamic acid solution had a viscosity of 358cps at a temperature of 25 ℃.

Comparative polymerization example 2

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.46g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. To this diamine solution, while stirring, 2.00g of acid dianhydride (C) and 6.3g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, 1.51g of acid dianhydride (D) and 8.5g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 50 ℃ for 16 hours to obtain a polyamic acid solution (PAA-2). The polyamic acid solution had a viscosity of 333cps at a temperature of 25 ℃.

Comparative polymerization example 3

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.46g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while sending nitrogen. To this diamine solution, 4.5g of acid dianhydride (a) was added while stirring, and further 20.5g of nmp was added, followed by stirring at 23 ℃ for 2 hours and then at 50 ℃ for 16 hours under a nitrogen atmosphere, to obtain a polyamic acid solution (PAA-3). The polyamic acid solution has a viscosity of 350cps at a temperature of 25 ℃.

Comparative polymerization example 4

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.49g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 3.00g of acid dianhydride (C) and further 12.0g of NMP12 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, and then 0.72g of acid dianhydride (D) and further 4.1g of NMP4 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 50 ℃ for 16 hours to obtain a polyamic acid solution (PAA-4). The polyamic acid solution had a viscosity of 333cps at a temperature of 25 ℃.

Polymerization example 1

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.78g of (DA-5) were taken, 24.4g of NMP24 were added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 1.75g of acid dianhydride (B) was added, and further 4.3g of nmp was added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, and then 1.41g of acid dianhydride (D) was added, further 8.0g of nmp was added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 50 ℃ for 16 hours to obtain a polyamic acid solution (PAA-5). The polyamic acid solution has a viscosity of 240cps at a temperature of 25 ℃.

(polymerization example 2)

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.49g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. To this diamine solution, 2.35g of acid dianhydride (a) and further 8.3g of nmpj were added while stirring, and then stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, 1.80g of acid dianhydride (C) and further 10.2g of nmp were added, and stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-6). The polyamic acid solution has a viscosity of 380cps at a temperature of 25 ℃.

(polymerization example 3)

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.63g of (DA-3) were taken, 23.4g of NMP23 was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 2.35g of acid dianhydride (a) and further 8.0g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, then 1.80g of acid dianhydride (C) and further 10.2g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-7). The polyamic acid solution has a viscosity of 350cps at a temperature of 25 ℃.

Polymerization example 4

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.95g of (DA-4) were added to the mixture, and NMP25.7g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 2.35g of acid dianhydride (a) was added, 7.5g of nmp was further added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, 1.80g of acid dianhydride (C) was then added, 10.2g of nmp was further added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-8). The polyamic acid solution has a viscosity of 365cps at a temperature of 25 ℃.

Polymerization example 5

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.78g of (DA-5) were taken, 24.4g of NMP24 were added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 2.35g of acid dianhydride (A) and further 7.8g of NMP7 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, then 1.80g of acid dianhydride (C) and further 10.2g of NMP10 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-9). The polyamic acid solution has a viscosity of 389cps at a temperature of 25 ℃.

Polymerization example 6

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.49g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 2.35g of acid dianhydride (a) and further 8.3g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, and then 1.41g of acid dianhydride (D) and further 8.0g of nmp were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-10). The polyamic acid solution had a viscosity of 321cps at a temperature of 25 ℃.

Polymerization example 7

A50 mL four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, 2.55g of (DA-1) and 0.49g of (DA-2) were taken, and NMP22.3g was added thereto, and the mixture was dissolved at 23 ℃ with stirring while feeding nitrogen. While stirring this diamine solution, 1.41g of acid dianhydride (A) and 2.9g of NMP2 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere, and then 1.41g of acid dianhydride (B) and 7.9g of NMP7 were added, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, 1.00g of acid dianhydride (C) and further 1.7 g of NMP were added thereto, and the mixture was stirred at 23 ℃ for 2 hours under a nitrogen atmosphere. Then, the mixture was stirred at 70 ℃ for 16 hours to obtain a polyamic acid solution (PAA-11). The polyamic acid solution has a viscosity of 365cps at a temperature of 25 ℃.

Comparative examples 1 to 4

15.0g of the polyamic acid solution obtained in comparative synthesis example was taken out from a 50mL Erlenmeyer flask containing a stirrer, and NMP11.25g and BCS11.25g were added thereto, followed by stirring with a magnetic stirrer for 2 hours to obtain liquid crystal alignment agents (A-1) to (A-4) in Table 1.

[ Table 1]

Comparative polymerization example	Comparative examples
		PAA-1	A-1
PAA-2	A-2
		PAA-3	A-3
PAA-4	A-4

(examples 1 to 7)

15.0g of the polyamide solution obtained in the synthesis example was taken out from a 50mL conical flask containing a stirrer, and NMP11.25g and BCS11.25g were added thereto and stirred with a magnetic stirrer for 2 hours to obtain liquid crystal alignment agents (B-1) to (B-7) in Table 2.

[ Table 2]

Polymerization examples	Examples
		PAA-5	B-1
PAA-6	B-2
		PAA-7	B-3
PAA-8	B-4
		PAA-9	B-5
PAA-10	B-6
		PAA-11	B-7

[ Table 3]

		55℃	35℃
				Comparative example 1	A-1	×	×
Comparative example 2	A-2	×	×
				Comparative example 3	A-3	×	×
Comparative example 4	A-4	×	×
				Example 1	B-1	○	×
Example 2	B-2	○	○
				Example 3	B-3	○	○
Example 4	B-4	○	○
				Example 5	B-5	○	○
Example 6	B-6	○	○
				Example 7	B-7	○	○

Industrial applicability

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention reduces charge accumulation due to asymmetry of ac drive in liquid crystal display elements of IPS drive system and FFS drive system, and quickly alleviates residual charge accumulated by dc voltage, so that liquid crystal display elements of IPS drive system and FFS drive system having excellent image sticking characteristics can be obtained. Therefore, the liquid crystal alignment film is particularly useful as a liquid crystal display element of an IPS driving method or an FFS driving method, or a liquid crystal alignment film of a liquid crystal television.

Claims

1. A liquid crystal aligning agent, comprising: at least 1 polymer selected from polyamic acid and imidized polymer of the polyamic acid, and organic solvent, wherein the polyamic acid is prepared by mixing the following components in a ratio of 10: 90-90: 10 in a molar ratio of a tetracarboxylic dianhydride component comprising a tetracarboxylic dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic dianhydride, and a diamine component comprising a diamine represented by the following formula (2),

in the formula (1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl group, an ester bond, a phenylene group, a linear alkylene group with 1 to 20 carbon atoms, a branched alkylene group with 2 to 20 carbon atoms, a cyclic alkylene group with 3 to 12 carbon atoms, a sulfonyl group, an amide bond or a group formed by combining the two, wherein the alkylene group with 1 to 20 carbon atoms is optionally interrupted by a bond selected from the ester bond and the ether bond, and the carbon atoms of the phenylene group and the alkylene group are optionally substituted by 1 or more same or different substituents selected from a halogen atom, a cyano group, an alkyl group, a halogenated alkyl group, an alkoxy group and a halogenated alkoxy group,

in the formula (2), Y₁Is at least 1 selected from the group consisting of 2-valent organic groups having structures of the formulae (YD-14) and (YD-18), B₁、B₂Independently represents a hydrogen atom, or an optionally substituted alkyl, alkenyl or alkynyl group having 1 to 10 carbon atoms, wherein j in the formula (YD-14) is an integer of 1 to 3,

10 to 100 mol% of the tetracarboxylic dianhydride component is the tetracarboxylic dianhydride represented by the formula (1) and the aliphatic tetracarboxylic dianhydride,

the tetracarboxylic dianhydride represented by the formula (1) is 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride.

2. The liquid crystal aligning agent according to claim 1, wherein 10 to 100 mol% of the diamine component is a diamine of the formula (2).

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the aliphatic tetracarboxylic dianhydride is bicyclo [3.3.0] octane 2,4,6,8-tetracarboxylic acid 2,4:6,8 dianhydride.

4. A liquid crystal alignment film obtained by applying the liquid crystal aligning agent according to any one of claims 1 to 3 and firing the applied liquid crystal aligning agent.

5. A liquid crystal display element comprising the liquid crystal alignment film according to claim 4.