KR20190058569A - A liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element - Google Patents

Abstract

(A) a tetracarboxylic acid dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic acid dianhydride in a ratio of 10:90 to 90:10 and a tetracarboxylic acid dianhydride represented by the following formula (2) (B) a polyimide precursor, an imidized polymer of the polyimide precursor, and a polyimide precursor having a predetermined temperature and a temperature lower than the predetermined temperature Wherein the liquid crystal aligning agent contains at least one polymer selected from the group consisting of photosensitive side-chain acrylic polymers which exhibit liquid crystallinity in the range of from 1 to 20, and an organic solvent.
[Chemical Formula 1]

Description

A liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element

TECHNICAL FIELD The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display device using the same, which are used in a liquid crystal display element.

Background Art [0002] Conventionally, a liquid crystal device has been widely used as a display portion of a personal computer, a cellular phone, a television receiver, and the like. The liquid crystal device includes, for example, a liquid crystal layer sandwiched between an element substrate and a 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 orientation of liquid crystal molecules in the liquid crystal layer, And a thin film transistor (TFT) for switching an electric signal supplied to the electrode. As a method of driving the liquid crystal molecules, a TN system or a VA system or a transverse electric field system such as an IPS system or a fringe field switching (FFS) system is known (see, for example, Patent Document 1).

On the other hand, since the liquid crystal display element and the organic EL element are economically important in the production process in recent years, recycling of the element substrate is required. That is, in the case where defects are generated by performing inspection such as orientation after forming a liquid crystal alignment film from a liquid crystal aligning agent, it is required that the liquid crystal alignment film is removed from the substrate and the rework process for recovering the substrate can be performed easily have. However, the liquid crystal alignment film obtained from the conventionally proposed liquid crystal aligning agent is intended to be insolubilized in an organic solvent or the like after post-baking to reduce film loss. In addition, even if the composition of the liquid crystal aligning agent whose reworkability has been studied up to now is applied to the composition of the liquid crystal aligning agent for the transverse electric field as it is, it can not always be said that the desired purpose is achieved. In the liquid crystal aligning agent It was necessary to actually evaluate the goodness or the badness of the reworkability and to review the composition of the optimum composition.

In addition, liquid crystal display devices are widely used as display devices at present. A liquid crystal alignment film which is a constituent member of a liquid crystal display element is a film for uniformly laminating liquid crystals, but it requires various characteristics as well as orientation uniformity of the liquid crystal. For example, in the production process of a liquid crystal alignment film, it is common to carry out an orientation treatment such as rubbing in which the surface of the polymer film is rubbed with a cloth. However, if the rubbing resistance of the liquid crystal alignment film is insufficient, the film is scratched to cause scratches and dust, or the film itself is peeled off, and the display quality of the liquid crystal display element is lowered. The liquid crystal display element is driven by applying a voltage to the liquid crystal. Therefore, when the voltage maintaining ratio (VHR) of the liquid crystal alignment film is low, a sufficient voltage is not applied to the liquid crystal, and the display contrast is lowered. Further, if it takes time for electric charges to accumulate in the liquid crystal alignment film due to the voltage for driving the liquid crystal or to lose the accumulated electric charge, a phenomenon such as afterimage or display burn-in occurs.

Various proposals have been made to satisfy at the same time some of the above-mentioned demand characteristics. For example, as a method for obtaining a liquid crystal alignment film excellent in rubbing resistance and having less after-image or burn-in, a proposal has been made as in Patent Document 2. Patent Document 3 proposes a method for obtaining a liquid crystal alignment film having excellent liquid crystal aligning property, alignment regulating ability, rubbing resistance, high voltage holding ratio and further reduced charge accumulation.

Japanese Laid-Open Patent Publication No. 2013-167782 International Publication No. WO 02/33481 pamphlet International Publication No. WO 2004/053583 Pamphlet

An object of the present invention is to provide a liquid crystal aligning agent capable of satisfying various properties required for a liquid crystal alignment film and obtaining a liquid crystal alignment film having excellent workability.

DISCLOSURE OF THE INVENTION The inventors of the present invention have made intensive investigations to solve the above problems. As a result, they have found that a polyamic acid obtained from a tetracarboxylic acid containing a specific aromatic tetracarboxylic acid dianhydride and an aliphatic tetracarboxylic acid dianhydride and a diamine having a specific structure, It has been found that by using an imidized polymer of amic acid, it is possible to obtain a liquid crystal alignment film having satisfactory various properties required for a liquid crystal alignment film and also having excellent workability, thereby completing the present invention.

Thus, the present invention is based on the above-described findings, and has the following points.

1. A thermosetting resin composition comprising: (A) a tetracarboxylic acid dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic acid dianhydride in a ratio of 10:90 to 90:10 and a tetracarboxylic acid dianhydride represented by the following formula 2), and at least one kind of polymer selected from the imidized polymers of the polyamic acid and the polyamic acid obtained by using the diamine component,

(B) at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor and a photosensitive side chain acrylic polymer which exhibits liquid crystallinity at a predetermined temperature range, and And a liquid crystal alignment agent.

[Chemical Formula 1]

(1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl, an ester bond, phenylene, a straight chain alkylene having 1 to 20 carbon atoms, A branched alkylene group having 3 to 12 carbon atoms, a cyclic alkylene group having 3 to 12 carbon atoms, a sulfonyl group, an amide bond, or a combination thereof, wherein the alkylene group having 1 to 20 carbon atoms is selected from an ester bond and an ether bond And the carbon atoms of phenylene and alkylene may be substituted with one or more of the same or different substituents selected from a halogen atom, a cyano group, an alkyl group, a haloalkyl group, an alkoxy group and a haloalkoxy group do.

In formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, B ₁ and B ₂ each independently represent a hydrogen atom , Or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.)

2. A tetracarboxylic acid dianhydride represented by the formula (1), wherein 10 to 100 mol% of the tetracarboxylic acid dianhydride component of the component (A) is the tetracarboxylic acid dianhydride and the aliphatic tetracarboxylic acid dianhydride. Wherein the liquid crystal aligning agent is a liquid crystal aligning agent.

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

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

(2)

(In the formula (YD-1), A ₁ is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms, and Z ₁ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. -2), W ₁ is a hydrocarbon group having 1 to 10 carbon atoms, A ₂ is a monovalent organic group having 3 to 15 carbon atoms and a nitrogen-containing heterocyclic group, or a di W ₂ is a divalent organic group having 6 to 15 carbon atoms and 1 to 2 benzene rings and W ₃ is an alkylene or biphenyl group having 2 to 5 carbon atoms. and alkylene is, Z ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a benzene ring, a is an integer from 0 to 1. for expression in (YD-4), a ₃ is a nitrogen atom having a carbon number of 3-15 is a heterocyclic ring. in the formula (YD-5), a ₄ is a heterocyclic ring containing the nitrogen atom of a carbon number of 3 ~ 15, W ₅ are burnt Be an alkylene of 2-5.)

5. A ₁ , A ₂ , A ₃ , and A ₄ described in the formulas (YD-1), (YD-2), (YD-4) The liquid crystal aligning agent according to 4, wherein the liquid crystal aligning agent is at least one selected from the group consisting of azoles, azides, pyrazoles, oxazoles, thiazoles, piperidines, piperazines, pyridines, pyrazines, indoles, benzimidazoles, quinolines and isoquinolines.

6. The organic electroluminescent device according to any one of items 1 to 5, wherein Y ₁ in the formula (2) is at least one kind selected from the group consisting of divalent organic groups having the structures of the following formulas (YD-6) to (YD-21) Wherein the liquid crystal aligning agent is a liquid crystal aligning agent.

(3)

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

7. The organic electroluminescent device according to item 6, wherein Y ₁ in the formula (2) is at least one selected from the group consisting of divalent organic groups having the structures of the formulas (YD-14) and (YD-18) ≪ / RTI >

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

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

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

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

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention can suppress charge accumulation due to asymmetry of AC driving and has excellent reworkability.

The liquid crystal aligning agent of the present invention comprises (A) a tetracarboxylic acid dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic acid dianhydride at a ratio of 10:90 to 90:10 At least one polymer selected from polyamic acid obtained by using an anhydride component and a diamine component containing a diamine represented by the following formula (2) and an imidized polymer of the polyamic acid, (B) a polyimide precursor, a polyimide precursor thereof And at least one polymer selected from the group consisting of photosensitive side chain type acrylic polymers which exhibit liquid crystallinity in a predetermined temperature range, and an organic solvent.

[Chemical Formula 4]

In formula (1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl, an ester bond, phenylene, a straight chain alkylene having 1 to 20 carbon atoms, A branched alkylene group, a cyclic alkylene group having 3 to 12 carbon atoms, a sulfonyl group, an amide group, or a combination thereof, wherein the alkylene group having 1 to 20 carbon atoms is selected from an ester bond and an ether bond And the carbon atoms of the phenylene and the alkylene may be substituted with one or a plurality of the same or different substituents selected from a halogen atom, a cyano group, an alkyl group, a haloalkyl group, an alkoxy group and a haloalkoxy group .

In formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, B ₁ to B ₂ each independently represent a hydrogen atom , Or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Hereinafter, each constituent requirement will be described in detail.

≪ Component (A) >

The component (A) used in the liquid crystal aligning agent of the present invention is a tetracarboxylic acid dianhydride represented by the formula (1) and an aliphatic tetracarboxylic acid dianhydride at a ratio of 10:90 to 90:10. At least one kind of polymer selected from polyamic acid obtained by using a bicarboxylic acid dianhydride component and a diamine component containing a diamine represented by the formula (2) and an imidized polymer of the polyamic acid.

≪ Tetracarboxylic acid dianhydride component >

The tetracarboxylic acid dianhydride represented by the above formula (1) includes, but is not limited to, the following compounds.

[Chemical Formula 5]

(Wherein q represents an integer of 1 to 20)

Among tetracarboxylic acid dianhydrides represented by the formula (1), tetracarboxylic acid dianhydride having i in the formula (1), that is, a tetracarboxylic acid dianhydride having two or more benzene rings in the formula (1) (1-2) to (1-11) are preferable among the above specific examples, and in view of having a biphenyl structure and a rigid structure, the tetracarboxylic acid dianhydride having a structure represented by the formula 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride represented by the following formula (I-1-5) is particularly preferable.

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

[Chemical Formula 6]

In the formula, X ₁ is any _{one of the} following (X-1) to (X-28).

(7)

[Chemical Formula 8]

[Chemical Formula 9]

In the formula (X-1), R ₃ to R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, more preferably a hydrogen atom or a methyl group.

(X-1) to (X-20) do not contain an aromatic moiety, and (X-10) is most preferable in view of difficulty in thermal imidation.

When the total amount of the tetracarboxylic acid dianhydride and the aliphatic acid dianhydride represented by the formula (1) in the total amount of the tetracarboxylic acid dianhydride components used in the production of the component (A) of the present invention is too small, The effect is not obtained. Therefore, the total amount of the tetracarboxylic acid dianhydride and the aliphatic acid dianhydride represented by the formula (1) is preferably from 10 to 100 mol%, more preferably from 50 to 100 mol%, based on 1 mol of the total tetracarboxylic acid dianhydride. 100 mol%, and more preferably 80 to 100 mol%.

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

The tetracarboxylic acid dianhydride and the aliphatic tetracarboxylic acid dianhydride represented by the formula (1) may be used alone or in combination of two or more. In this case, the tetracarboxylic acid dianhydride represented by the formula (1) The dianhydride and the aliphatic tetracarboxylic acid dianhydride preferably use the above-mentioned preferable amount as a total.

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

[Chemical formula 10]

In the formula (4), X is a tetravalent organic group and its structure is not particularly limited. Specific examples include structures of the following formulas (X-31) to (X-36).

(11)

≪ Diamine component >

The diamine component used in the production of the liquid crystal aligning agent of the present invention contains the diamine of the above formula (2). In formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, B ₁ to B ₂ each independently represent a hydrogen atom , Or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, t-butyl, hexyl, octyl, decyl, cyclopentyl and cyclohexyl. Examples of the alkenyl group include those obtained by substituting one or more CH-CH structures present in the alkyl group with a C = C structure, and more specifically, a vinyl group, allyl group, 1-propenyl group, A phenyl group, a 2-butenyl group, a 1,3-butadienyl group, a 2-pentenyl group, a 2-hexenyl group, a cyclopropenyl group, a cyclopentenyl group and a cyclohexenyl group. As the alkynyl group, those having at least one CH ₂ -CH ₂ structure present in the above alkyl group substituted with a C≡C structure can be mentioned, and more specifically, an ethynyl group, 1-propynyl group, 2-propynyl group And the like.

The above alkyl group, alkenyl group and alkynyl group may have a substituent group when the total number of carbon atoms is 1 to 10, and may further form a cyclic structure by a substituent. The formation of a ring structure by a substituent means that a substituent group or a substituent group and a part of the parent (skeleton) bond to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organoxy group, an organotio group, an organosilyl group, an acyl group, an ester group, a thioester 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.

As the aryl group as a substituent, a phenyl group can be mentioned. These aryl groups may be further substituted with other substituents described above.

The organoxy group as a substituent may represent a structure represented by O-R. These R may be the same or different and may be exemplified by the alkyl, alkenyl, alkynyl, and aryl groups described above. These R may be further substituted with the aforementioned substituents. Specific examples of the alkyloxy group include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group.

The organotio group which is a substituent may represent a structure represented by -S-R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be 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.

The organosilyl group as a substituent may represent a structure represented by -Si- (R) ₃ . These R may be the same or different and may be exemplified by the alkyl, alkenyl, alkynyl, and aryl groups described above. These R may be further substituted with the aforementioned substituents. Specific examples of the alkylsilyl group include trimethylsilyl, triethylsilyl, tripropylsilyl, tributylsilyl, tripentylsilyl, trihexylsilyl, pentyldimethylsilyl, hexyldimethylsilyl and the like. .

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

The ester group as a substituent may represent a structure represented by -C (O) O-R or -OC (O) -R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be further substituted with the aforementioned substituents.

The thioester group which is a substituent may represent a structure represented by -C (S) O-R or -OC (S) -R. As R, examples of the alkyl group, alkenyl group, alkynyl group, aryl group and the like can be mentioned. These R may be further substituted with the aforementioned substituents.

The phosphoric acid ester group which is a substituent may represent a structure represented by -OP (O) - (OR) ₂ . These R may be the same or different and may be exemplified by the alkyl, alkenyl, alkynyl, and aryl groups described above. These R may be further substituted with the aforementioned substituents.

Examples of the amide group as the substituent include a group represented by -C (O) NH ₂ or a group represented by -C (O) NHR, -NHC (O) R, -C (O) N (R) ₂ or -NRC Lt; / RTI > These R may be the same or different and may be exemplified by the alkyl, alkenyl, alkynyl, and aryl groups described above. These R may be further substituted with the aforementioned substituents.

Examples of the aryl group as the substituent include the same aryl groups as those described above. These aryl groups may be further substituted with other substituents described above.

Examples of the alkyl group as the substituent include the same alkyl groups mentioned above. These alkyl groups may be further substituted with other substituents described above.

Examples of the alkenyl group as the substituent include the same alkenyl groups as those described above. This alkenyl group may be further substituted with another substituent as described above.

Examples of the alkynyl group as the substituent include the same alkynyl groups as mentioned above. These alkynyl groups may be further substituted with other substituents described above.

In general, when introducing a bulky structure, there is a possibility that the reactivity or the liquid crystal orientation of the amino group may be lowered. Therefore, as B ₁ and B ₂ , a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent is more preferable And a hydrogen atom, a methyl group or an ethyl group is particularly preferable.

The structure of Y _{1 in} the formula (2) is not particularly limited as long as it has at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring. Examples of the divalent group having at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocycle represented by the following formulas (YD-1) to (YD-5) Organic groups.

[Chemical Formula 12]

In formula (YD-1), A ₁ is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms, and Z ₁ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent.

In the formula (YD-2), W ₁ is a hydrocarbon group having 1 to 10 carbon atoms, A ₂ is a monovalent organic group having 3 to 15 carbon atoms and a heterocyclic group having a nitrogen atom, or an aliphatic group having 1 to 6 carbon atoms Substituted disubstituted amino group.

In formula (YD-3), W ₂ is a divalent organic group having 6 to 15 carbon atoms and 1 to 2 benzene rings, W ₃ is alkylene or biphenylene having 2 to 5 carbon atoms, Z ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a benzene ring, and a is an integer of 0 to 1.

In the formula (YD-4), A ₃ is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms.

In the formula (YD-5), A ₄ is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms, and W ₅ is alkylene having 2 to 5 carbon atoms.

A ₁ , A ₂ , A ₃ and A _{4 in} the formulas (YD-1), (YD-2), (YD-4) and Is not particularly limited as far as it is a known structure. Among them, pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyrazine, indole, benzoimidazole, quinoline, isoquinoline, More preferred are piperazine, piperidine, indole, benzimidazole, imidazole, carbazole, and pyridine.

Specific examples of Y _{2 in} the formula (2) include divalent organic groups having nitrogen atoms represented by the following formulas (YD-6) to (YD-38), and charge accumulation (YD-14) to (YD-21) are more preferable, and (YD-14) and (YD-18) are particularly preferable.

[Chemical Formula 13]

In the formulas (YD-14) and (YD-21), j is an integer of 0 to 3. In the formula (YD-17), h is an integer of 1 to 3.

[Chemical Formula 14]

In the formulas (YD-24), (YD-25), (YD-28) and (YD-29), j is an integer of 0 to 3.

[Chemical Formula 15]

The proportion of the diamine represented by the formula (2) in the imidized polymer of the polyamic acid and the polyamic acid of the present invention is preferably 10 to 100 mol%, more preferably 30 to 100 mol% Mol%, more preferably 50 to 100 mol%.

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

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 formula (2). Y ₂ in the following formula (5) is a divalent organic group and its structure is not particularly limited, and two or more kinds of them may be mixed. Examples of (Y-1) to (Y-49) and (Y-57) to (Y-75) are shown below.

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

If the proportion of the diamine represented by the formula (5) in the imidized polymer of the polyamic acid and the polyamic acid as the component (A) contained in the liquid crystal aligning agent of the present invention is large, the effect of the present invention may be impaired , Which is undesirable. 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%, relative to 1 mol of the whole diamine.

<Production method of polyamic acid>

Polyamic acid, which is a polyimide precursor used in the present invention, can be synthesized by the following method.

Specifically, the reaction is carried out by reacting tetracarboxylic acid dianhydride and diamine in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 70 ° C, for 30 minutes to 24 hours, preferably 1 to 12 hours can do.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the solubility of the monomer and the polymer. Or more may be mixed and used.

The concentration of the polymer is preferably from 1 to 30 mass%, more preferably from 5 to 20 mass%, from the viewpoint that the precipitation of the polymer does not occur well and the high molecular weight material is easily obtained.

The polyamic acid thus obtained can be recovered by precipitating the polymer by injecting the reaction solution into a poor solvent while stirring well. It is also possible to obtain a purified polyamic acid powder by conducting precipitation several times, washing with a poor solvent, and then drying at room temperature or by heating. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone and toluene. Water, methanol, ethanol and 2-propanol are preferred.

<Production method of polyimide>

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

When a polyimide is produced from polyamic acid, chemical imidization by adding a catalyst to a solution of the polyamic acid obtained by the reaction of the diamine component and the tetracarboxylic acid dianhydride is simple. The chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not lowered in the process of imidization.

The chemical imidization can be carried out by stirring the 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 described above may be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferred since it has a basicity suitable for proceeding the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Of these, use of acetic anhydride is preferable since the purification after completion of the reaction is facilitated.

The temperature at which the imidization reaction is carried out is -20 to 140 占 폚, preferably 0 to 100 占 폚, and the reaction time is 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times by mole, preferably 2 to 20 times by mole, of the polyamic acid group, and the amount of the acid anhydride is 1 to 50 times by mole, preferably 3 to 30 times by mole of the polyamic acid group. The imidization rate of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

Since the added catalyst remains in the solution after the imidization reaction of the polyamic acid, the imidized polymer thus obtained is recovered by the means described below and redissolved in an organic solvent to obtain the liquid crystal aligning agent of the present invention desirable.

The solution of the polyimide obtained as described above can be precipitated by pouring into a poor solvent while stirring well. After the precipitation is carried out several times, it is washed with a poor solvent and then heated or dried at room temperature to obtain a purified polymer powder.

Examples of the poor solvent include, but are not limited to, methanol, 2-propanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, , 2-propanol, acetone, and the like.

&Lt; Component (B) &gt;

The component (B) contained in the liquid crystal aligning agent of the present invention is selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side chain type acrylic polymer which exhibits liquid crystallinity within a predetermined temperature range At least one kind of polymer.

<Polyimide precursor>

The polyimide precursor is a polyimide precursor having a structural unit represented by the following formula (11).

(23)

In formula (11), X ₁₁ is independently a tetravalent organic group and Y ₁₁ is independently a divalent organic group. R ₁₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; A ₁₁ to A ₁₂ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, And an alkynyl group having 2 to 10 carbon atoms.

Specific examples of the alkyl group for R ₁₁ include a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s- . From the viewpoint of easy imidization by heating, R ₁₁ is preferably a hydrogen atom or a methyl group.

In the formula (11), X ₁₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and the structure thereof is not particularly limited. In the polyimide precursor, two or more kinds of X ₁₁ may be mixed. Specific examples of X _{11 include structures} of the following formulas (X-1) to (X-44).

&Lt; EMI ID =

(25)

(26)

(27)

R ₈ to R ₁₁ in the formula (X-1) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group, or a phenyl group. When R ₈ to R ₁₁ are bulky structures, a hydrogen atom, a methyl group and an ethyl group are more preferable, and a hydrogen atom or a methyl group is particularly preferable because of the possibility of lowering the liquid crystal alignability.

In the formula (11), it is preferable that X ₁₁ contains a structure selected from (X-1) to (X-14) from the standpoint of availability of the monomer.

The preferred ratio of the structure is selected from the formula (X-1) ~ (X -14) is, X _11, and at least 20 mole%, more preferably at least 60 mol%, more preferably at least 80 mol% to be.

In formula (11), A ₁₁ and A ₁₂ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, And an alkynyl group having 2 to 10 carbon atoms.

Specific examples and preferable examples of these A ₁₁ and A ₁₂ are the same as B ₁ and B _{2 in the} above-mentioned component (A-1) and component (A-2).

In the formula (11), Y ₁₁ is a divalent organic group derived from a diamine, and its structure is not particularly limited. The one side Y represents a specific example of the structure of _11, described in the section of the component (A) (Y-1) ~ (Y -49) and (Y-57) ~ (Y -75) or (YD-6 ) To (YD-38). In addition to these, the following (Y-76) to (Y-97) and (YD-39) to (YD-52) can be mentioned.

(28)

[Chemical Formula 29]

(30)

(31)

(32)

(33)

(34)

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

It is more preferable that the structure of Y ₁₁ is at least one selected from the structures represented by the following formulas (15) and (16) from the viewpoint of liquid crystal alignability and pretilt angle of the obtained liquid crystal alignment film.

(35)

R ₁₃ is a hydrogen atom, a halogen atom or a monovalent organic group having 1 to 30 carbon atoms, a is an integer of 1 to 4, R ₁₂ is a single bond or a divalent organic group having 1 to 30 carbon atoms, , R ₁₂ and R ₁₃ may be the same or different from each other, and R ₁₄ in formula (16) may be a single bond, -O-, -S-, -NR ₁₅ -, amide bond, An ester bond, a urea bond or a divalent organic group having 1 to 40 carbon atoms, and R ₁₅ is a hydrogen atom or a methyl group.

Specific examples of the formulas (15) and (16) include the following structures. Y ₁₁ , Y-21, Y-22, Y-23, Y-25, Y-43, and Y-31 can be used as the liquid crystal alignment layer, More preferred are Y-44, Y-45, Y-46, Y-48, Y-63, Y-71, Y-72, Y-73, Y-74 and Y-75. The proportion of the above structure capable of enhancing liquid crystal alignability is preferably 20% by mole or more, more preferably 60% by mole or more, and even more preferably 80% by mole or more of the total of Y ₁₁ .

When it is desired to increase the pretilt angle of the liquid crystal when used as a liquid crystal alignment film, it is preferable that Y ₁₁ has a long chain alkyl group, aromatic ring, aliphatic ring, steroid skeleton, or a combination thereof in the side chain. Examples of Y ₁₁ include Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y- -87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96 and Y-97. When the pretilt angle is intended to be increased, the proportion of the above structure is preferably 1 to 30 mol%, more preferably 1 to 20 mol% of the entire Y ₁₁ .

When a polyimide (precursor) having photo-orientable side chains is used as the polymer of the component (B), it is preferable to use a polyimide (precursor) having the photoreactive side chains described below.

(36)

(R ¹⁶ is -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N (CH ₃ ) CH ₃ ) -, -N (CH ₃ ) CO-, R ¹⁷ represents an alkylene of 1 to 20 carbon atoms which is substituted by a ring, an unsubstituted or fluorine atom, -CH ₂ - of -O- may be substituted with -CF ₂ - or -C = C-, and in the case where any of the groups shown below are not adjacent to each other, these groups may be substituted by -O-, -COO -, -OCO-, -NHCO-, -CONH-, -NH-, a carbon ring, a heterocyclic ring, R ¹⁸ is -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -NH _{-, -N (CH 3) -} , -CON (CH 3) -, -N (CH 3) CO-, represents any of a carbon ring or a heterocyclic ring, R ¹⁹ is a vinyl group, -CR ²⁰ = CH ₂ group, -CR ²⁰ (OH) -CH ₃ group, a carbon ring, represents a structure represented by the formula is selected from the heterocyclic group or the following, R ²⁰ is can be substituted with a hydrogen atom or a fluorine atom Also represents a methyl group that is.)

(37)

(38)

[Chemical Formula 39]

(40)

(41)

(42)

(43)

(44)

[Chemical Formula 45]

(46)

In the case of producing such a polyimide precursor, it is convenient to use, as a diamine, a diamine substituted with a side chain represented by the above formula (b).

Also, a polyimide precursor having a photo-orientable group in its main chain may be used. In this case, it is convenient to use a diamine having a bond including a photo-orienting group between an amine and an amine as shown by the following formula (21).

(47)

(Wherein X ²¹ is a single bond or an alkylene group of 1 to 5 carbon atoms, X ²² is -OCO-CH = CH- or -CH = CH-COO-, X ²³ is a single bond, ~ 10 alkylene group or a divalent group of a benzene ring, X ²⁴ is a single bond, -OCO-CH = CH- or -CH = CH-COO-, X ²⁵ is a single bond or alkylene group of 1 to 5 carbon atoms. However, it has at least one new namoyl group.)

Examples of the diamine represented by the formula (21) include the following diamines.

(48)

(Wherein X is independently a single bond or a bonding group selected from an ether (-O-), an ester (-COO- or -OCO-) and an amide (-CONH- or -NHCO-) Or an alkylene group having 1 to 5 carbon atoms and Z is independently an alkylene group or a phenylene group having 1 to 10 carbon atoms The bonding position of the amino group on the benzene ring or the position of the bonding group to the benzene ring in the center is not particularly limited .)

Specific examples of the diamine represented by the formula (21) include the following diamines.

(49)

(50)

A liquid crystal alignment film formed using a polyimide precursor such as a polyamic acid or a polyamic acid ester having a diamine as a raw material and a liquid crystal aligning agent containing polyimide or polyamide as represented by the above formula (21) The change in the liquid crystal alignment performance due to the driving, for example, the change in the alignment direction of the liquid crystal, is reduced. Therefore, the liquid crystal display element having this liquid crystal alignment film has the effect of preventing the afterimage due to the AC drive, that is, the afterimage characteristic due to the AC drive, to be very good, since the liquid crystal alignment performance of the liquid crystal alignment film by the AC drive is stable. . Further, the liquid crystal alignment film formed using the diamine represented by the above formula (21) has excellent liquid crystal alignment performance itself, and can be substantially free from alignment defects.

The polyimide precursor used in the present invention is obtained from the reaction of a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acid and polyamic acid ester.

&Lt; Preparation of polyimide precursor-polyamic acid &gt;

(A-1) and the component (A-2).

&Lt; Preparation of polyimide precursor-polyamic acid ester &gt;

The polyamic acid ester which is a polyimide precursor used in the present invention can be produced by the following production method (1), (2) or (3).

(1) Production from polyamic acid

The polyamic acid ester can be produced by esterifying the polyamic acid prepared as described above. Concretely, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably 1 to 4 hours .

The esterifying agent is preferably one which can be easily removed by purification. Examples of the esterifying agent include N, N-dimethylformamide dimethylacetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide dineopentylbutyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazine, , 1-propyl-3-p-tolyltriazine, and 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents relative to 1 mol of the repeating unit of the polyamic acid.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or gamma -butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide , Dimethyl sulfoxide or 1,3-dimethyl-imidazolidinone. When the solubility of the polyimide precursor in the solvent is high, it is preferable to use methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, The solvent represented by [D-3] can be used.

These solvents may be used alone or in combination. In addition, even if the solvent does not dissolve the polyimide precursor, the solvent may be mixed with the polyimide precursor to the extent that the resulting polyimide precursor does not precipitate. In addition, the moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the resulting polyimide precursor. Therefore, it is preferable that the solvent is dehydrated and dried.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or? -Butyrolactone from the solubility of the polymer, May be used. The concentration at the time of production is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer does not occur well and high molecular weight substances are easily obtained.

(2) When produced by the reaction of a tetracarboxylic acid diester dichloride with a diamine

Polyamic acid esters can be prepared from tetracarboxylic acid diester dichloride and diamines.

Specifically, the tetracarboxylic acid diester dichloride and diamine are reacted in the presence of a base and an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C for 30 minutes to 24 hours, For 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable for the reaction to proceed mildly. The addition amount of the base is preferably 2 to 4 times the amount of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or? -Butyrolactone from the viewpoint of the solubility of the monomer and the polymer, and they may be used alone or in combination of two or more. The concentration of the polymer at the time of production is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer does not occur well and high molecular weight substances are easily obtained. In order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable that the solvent used in the production of the polyamic acid ester is dehydrated as much as possible, and it is preferable that the solvent .

(3) In the case of production from a tetracarboxylic acid diester and a diamine

The polyamic acid ester can be produced by polycondensation of a tetracarboxylic acid diester and a diamine.

Specifically, the tetracarboxylic acid diester and diamine are reacted in the presence of a condensing agent, a base and an organic solvent at 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C for 30 minutes to 24 hours, preferably 3 To &lt; / RTI &gt; 15 hours.

Examples of the condensing agent include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3- dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy- N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) 1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate and (2,3-dihydro-2-thioxo-3-benzoxazolyl) . The amount of the condensing agent to be added is preferably 2 to 3 times the mole of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base to be added is preferably 2 to 4 times the amount of the diamine component in view of easy removal and high molecular weight.

In addition, in the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably from 0 to 1.0 times the amount of the diamine component.

Among the above-mentioned three methods for producing a polyamic acid ester, the production method of the above (1) or (2) is particularly preferable because a polyamic acid ester having a high molecular weight can be obtained.

The solution of the polyamic acid ester obtained as described above can be precipitated by injecting it into a poor solvent while stirring well. After several times of precipitation and washing with a poor solvent, the purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Polyimide>

The polyimide used in the present invention can be prepared by imidizing the above-mentioned polyamic acid ester or polyamic acid. (A-1) and the component (A-2).

&Lt; Photosensitive side chain acrylic polymer which exhibits liquid crystallinity in a predetermined temperature range &gt;

One of the aspects of the component (B) is a photosensitive side chain type acrylic polymer which exhibits liquid crystallinity in a predetermined temperature range.

It is preferable that the side chain type acrylic polymer reacts with light in a wavelength range of 250 nm to 400 nm and exhibits liquid crystallinity in a temperature range of 100 ° C to 300 ° C.

The side chain acrylic polymer preferably has a photosensitive side chain reacting with light in a wavelength range of 250 nm to 400 nm.

The side chain acrylic polymer preferably has a mesogen group because it exhibits liquid crystallinity in a temperature range of 100 占 폚 to 300 占 폚.

The side chain type acrylic polymer has a side chain having photosensitivity to the main chain, and may react with light to cause a crosslinking reaction, an isomerization reaction, or a light free electric potential. The structure of the side chain having photosensitivity is not particularly limited, but a structure that causes a crosslinking reaction or a light-free potential in response to light is preferable, and it is more preferable to cause a crosslinking reaction. In this case, even when exposed to external stress such as heat, the realized orientation control ability can be stably maintained for a long period of time. The structure of the photosensitive side chain type acrylic polymer film capable of exhibiting liquid crystallinity is not particularly limited as long as it satisfies such characteristics, but it is preferable that the structure has a mesogen component which is rigid in the side chain structure. In this case, when the side chain type acrylic polymer is used as the liquid crystal alignment film, stable liquid crystal alignment can be obtained.

The structure of the acrylic polymer is, for example, a structure having a main chain and a side chain bonded to the main chain, and the side chain thereof has a mesogen component such as a biphenyl group, a terphenyl group, a phenylcyclohexyl group, a phenylbenzoate group, A structure having a main chain and a side chain bonded to the main chain and having a side chain in addition to a mesogen component and having a main chain and a side chain bonded to the main chain, Or a structure having a phenylbenzoate group that undergoes a dislocation reaction.

More specific examples of the structure of the photosensitive side chain type acrylic polymer which exhibits liquid crystallinity within a predetermined temperature range include hydrocarbons, (meth) acrylates, itaconates, fumarates, maleates, a-methylene- A main chain composed of at least one kind selected from the group consisting of a radical polymerizable group such as lactone, styrene, vinyl, maleimide and norbornene, and a side chain comprising at least one of the following formulas (31) to (35) Is preferable.

(51)

Wherein, Ar ₁ is a benzene ring, a naphthalene ring, pyrrole ring, furan ring, thiophene ring, represents a divalent substituent removal of two hydrogen atom from a pyridine ring, Ar ₂ and Ar ₃ are each independently a benzene ring, Naphthalene ring, pyrrole ring, furan ring, thiophene ring, and bivalent substituent group in which two hydrogen atoms have been removed from the pyridine ring, q ¹ and q ² are one in one and the other is 0, and Ar ₄ and Ar ₅ are Y ₁ -Y ₂ represents a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, a naphthalene ring, a pyrrole ring, a furan ring, a thiophene ring and a pyridine ring, Each of S ₁ to S ₃ independently represents a single bond, a linear or branched alkylene having 1 to 18 carbon atoms, a cycloalkylene having 5 to 8 carbon atoms, phenylene or Biphenylene, Or a combination of two or more kinds selected from the group consisting of a single bond, an ether bond, an ester bond, an amide bond, a urea bond, a urethane bond, an amino bond, A linking group of 2 or more and 10 or less selected from linear or branched alkylene having 1 to 18 carbon atoms, cycloalkylene having 5 to 8 carbon atoms, phenylene, biphenylene, The substituent may be a structure in which a plurality of substituents are connected through the bonds,

R ³¹ represents a hydrogen atom, a hydroxyl group, a mercapto group, an amino group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylamino group having 1 to 8 carbon atoms, And the benzene ring and / or the naphthalene ring may be substituted by the same or different one or more substituents selected from a halogen atom, a cyano group, a nitro group, a carboxyl group, and an alkoxycarbonyl group having 2 to 11 carbon atoms, do. At this time, the alkyl group having 1 to 10 carbon atoms may be linear, branched or cyclic, and may be a combination thereof or may be substituted with a halogen atom.

The photosensitive side chain type acrylic polymer which exhibits liquid crystallinity at a predetermined temperature range as the component (B) of the present invention may contain liquid crystalline side chains.

As the mesogen group of the liquid crystalline side chain, biphenyl or phenyl benzoate alone may contribute to a mesogen structure, and side chains such as benzoic acid may form a mesogen structure by hydrogen bonding. The mesogen group of the side chain is preferably the following structure.

(52)

<< Preparation of Photosensitive Side Chain Polymer >>

The photosensitive side chain type acrylic polymer which exhibits liquid crystallinity in the above-mentioned predetermined temperature range can be obtained by polymerizing a photoreactive side chain monomer having the above photosensitive side chain and a liquid crystal side chain monomer.

[Photoreactive side chain monomer]

The photoreactive side chain monomer refers to a monomer capable of forming a polymer having a photosensitive side chain at a side chain portion of the polymer when the polymer is formed.

As the photoreactive group of the side chain, the structure represented by the above formulas (31) to (35) is preferable.

More specific examples of the photoreactive side chain monomer include hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate,? -Methylene-? -Butyrolactone, styrene, vinyl, maleimide, norbornene , And a photosensitive side chain comprising at least one of the above-mentioned formulas (31) to (35).

[Liquid crystalline side chain monomer]

The liquid crystalline side chain monomer refers to a monomer in which the polymer derived from the monomer exhibits liquid crystallinity and the polymer can form a mesogen group at a side chain site.

More specific examples of the liquid crystalline side chain monomers include hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate,? -Methylene-? -Butyrolactone, styrene, vinyl, maleimide, norbornene , And a side chain having at least one of the above-mentioned &quot; mesogenic group of liquid crystalline side chains &quot;.

The side chain type acrylic polymer which is an embodiment of the component (B) can be obtained by a polymerization reaction of a photoreactive side chain monomer which exhibits the liquid crystallinity described above. In addition, copolymerization of a photoreactive side chain monomer and a liquid crystal side chain monomer that do not exhibit liquid crystallinity and copolymerization of a photoreactive side chain monomer and a liquid crystal side chain monomer that exhibit liquid crystallinity can be obtained. Further, it can be copolymerized with other monomers within a range that does not inhibit the liquid crystalline property.

Other monomers include, for example, industrially available monomers capable of radical polymerization.

Specific examples of other monomers include unsaturated carboxylic acids, acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds and vinyl compounds.

Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

Examples of the acrylic acid ester compound include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthryl methyl acrylate, phenyl acrylate, 2,2 , 2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxy triethylene glycol acrylate, 2- ethoxy ethyl acrylate , 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate And 8-ethyl-8-tricyclodecyl acrylate.

Examples of the methacrylic acid ester compound include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthrylmethyl methacrylate Butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-methoxyethyl methacrylate, 2-methoxyethyl methacrylate, 2-methoxyethyl methacrylate, Methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2- methoxyethyl methacrylate, 2-methoxybutyl methacrylate, 2- Methyl-8-tricyclodecyl methacrylate, and 8-ethyl-8-tricyclodecyl methacrylate. Cyclic ethers such as glycidyl (meth) acrylate, (3-methyl-3-oxetanyl) methyl (meth) acrylate and (3-ethyl-3-oxetanyl) methyl (Meth) acrylate compound having a group can also be used.

Examples of the vinyl compound include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether.

Examples of the styrene compound include styrene, methylstyrene, chlorostyrene, and bromostyrene.

Examples of the maleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

The method for producing the side chain type polymer of the present embodiment is not particularly limited, and a general method which is industrially handled can be used. Specifically, it can be produced by cation polymerization, radical polymerization or anionic polymerization using a vinyl group of a liquid crystal side chain monomer or a photoreactive side chain monomer. Of these, radical polymerization is particularly preferable from the viewpoint that reaction control is easy and the like.

As the polymerization initiator for radical polymerization, known radical polymerization initiators such as AIBN (azobisisobutyronitrile) and known compounds such as reversible addition-cleavable chain transfer (RAFT) polymerization reagents can be used.

The radical polymerization method is not particularly limited, and an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a precipitation polymerization method, a bulk polymerization method, a solution polymerization method and the like can be used.

The organic solvent used in the polymerization reaction of the photosensitive side chain type acrylic polymer which exhibits liquid crystallinity within a predetermined temperature range is not particularly limited as long as the resulting polymer dissolves. Specific examples thereof are given below.

N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, But are not limited to, pyridine, dimethyl sulfone, hexamethyl sulfoxide,? -Butyrolactone, isopropyl alcohol, methoxymethyl pentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, Ketones, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol mono Butyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate Diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol Monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, N-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene, diethylene glycol, propylene Carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propyl acetate Methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid, Propyl propionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy- Propane amide, 3-butoxy-N, N-dimethylpropanamide and the like.

These organic solvents may be used alone or in combination. Further, even a solvent which does not dissolve the produced polymer may be mixed with the above-described organic solvent within the range in which the produced polymer is not precipitated.

Further, in the radical polymerization, oxygen in the organic solvent causes the polymerization reaction to be inhibited. Therefore, it is preferable to use an organic solvent which has been degassed to the extent possible.

The polymerization temperature in the radical polymerization can be selected from any of 30 ° C to 150 ° C, preferably 50 ° C to 100 ° C. If the concentration is excessively low, it becomes difficult to obtain a polymer having a high molecular weight. If the concentration is too high, the viscosity of the reaction liquid becomes excessively high and it becomes difficult to carry out uniform stirring. , Preferably 1% by mass to 50% by mass, and more preferably 5% by mass to 30% by mass. The reaction is carried out at a high concentration in the initial stage, and then an organic solvent can be added.

In the above-mentioned radical polymerization reaction, when the ratio of the radical polymerization initiator is larger than that of the monomer, the molecular weight of the obtained polymer becomes smaller and, if it is smaller, the molecular weight of the obtained polymer becomes larger. To 10 mol%. In the polymerization, various monomer components, solvents, initiators, etc. may be added.

[Recovery of photosensitive side chain type acrylic polymer which exhibits liquid crystallinity in a predetermined temperature range]

In the case of recovering the resulting polymer from the reaction solution of the photosensitive side chain type polymer capable of exhibiting liquid crystallinity obtained by the above-described reaction, the reaction solution may be put into a poor solvent to precipitate the polymer . Examples of the poor solvent used in the precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, . The polymer precipitated by charging into a poor solvent can be recovered by filtration and then dried at room temperature or under reduced pressure or under normal pressure. In addition, when the polymer precipitated and recovered is redissolved in an organic solvent and the operation of reprecipitation and recovery is repeated 2 to 10 times, impurities in the polymer can be reduced. As the poor solvent at this time, for example, alcohols, ketones, hydrocarbons and the like can be mentioned, and when three or more poor solvents selected from these are used, the purification efficiency is further improved, which is preferable.

The molecular weight of the photosensitive side chain type acrylic polymer which exhibits liquid crystallinity within a predetermined temperature range, which is one embodiment of the component (B) of the present invention, is preferably from 1 to 10 parts by weight, The weight average molecular weight measured by Gel Permeation Chromatography (GPC) is preferably from 2,000 to 1,000,000, more preferably from 5,000 to 100,000.

The content of the component (A) and the component (B) in the liquid crystal aligning agent of the present invention is 5:95 to 95: 5 in the total amount of the component (A) and 10:90 to 90 : &Lt; / RTI &gt;

The imidization ratio of the component (A) in the liquid crystal aligning agent of the present invention and the component (B) in the case where the component (B) is a polyimide (precursor) can be arbitrarily adjusted depending on the application and purpose. However, From the viewpoint of the accumulation property, the imidization rate of the specific polymer (A) is preferably 0 to 55%, more preferably 0 to 20%. The imidization ratio of the specific polymer (B) is preferably high, preferably from 40% to 95%, more preferably from 55% to 90%, from the viewpoint of the orientation of the liquid crystal, the alignment regulating force and the voltage holding ratio.

<Liquid Crystal Aligner>

The liquid crystal aligning agent used in the present invention has a form of a solution in which a polymer component is dissolved in an organic solvent. The weight average molecular weight of the polymer is preferably from 2,000 to 500,000, more preferably from 5,000 to 300,000, and still more preferably from 10,000 to 100,000. 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 concentration of the polymer of the liquid crystal aligning agent used in the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed, but is preferably 1% by mass or more from the viewpoint of forming a uniform and defect- From the viewpoint of storage stability, it is preferable that the content is 10% by mass or less. A particularly preferable concentration of the polymer is 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 the polymer component dissolves uniformly. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl- Pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, gamma -butyrolactone, 1,3-dimethyl-imidazolidinone, 3- Methoxy-N, N-dimethylpropanamide, and the like. These may be used alone or in combination of two or more. Further, even if the solvent can not dissolve the polymer component solely, it may be mixed with the organic solvent as long as the solvent does not precipitate the polymer.

As the organic solvent contained in the liquid crystal aligning agent, a mixed solvent in which a solvent for improving the coating property and the surface smoothness of the coating film when the liquid crystal aligning agent is applied is generally used in addition to the above-mentioned solvent, In the liquid crystal aligning agent of the invention, such a mixed solvent is suitably used. Specific examples of the organic solvent used in combination include, but are not limited to, the following examples.

Butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, Butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl- Butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1, 2-butanediol, 1-butanediol, 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- Diethyleneglycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3 Heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutyl acetate, 1- Ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoacetate, ethylene glycol monoacetate, (Ethylene glycol monohexyl 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- (Buutk Ethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, Ethylene glycol monoacetate, 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, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, Ethoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, 3-methoxypropionate, 3-methoxypropionate, 3-ethoxypropionate, D-1] to [D-1] to [D-1] to [D-1] to [D-3] D-3], and the like.

(53)

Of the formula ^[D-1], D 1 represents an alkyl group having a carbon number of 1 to 3, wherein ^[D-2], D 2 represents an alkyl group having a carbon number of 1 to 3, formula ^[D-3], D 3 Represents an alkyl group having 1 to 4 carbon atoms.

Among them, preferable combinations of solvents include N-methyl-2-pyrrolidone,? -Butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and? -Butyrolactone, and propylene glycol mono Propyleneglycol monobutyl ether, N-methyl-2-pyrrolidone and? -Butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene Propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone and? -Butyrolactone, Butyrolactone, propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and? -Butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, N- Methyl-2-pyrrolidone,? -Butyrolactone and dipropylene glycol dimethyl ether, and the like. The kind and content of the solvent are appropriately selected according to the application device of the liquid crystal aligning agent, application conditions, application environment, and the like.

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

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(55)

These additives are preferably 0.1 to 30 parts by mass based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. If the amount is less than 0.1 part by mass, the effect can not be expected. If it exceeds 30 parts by mass, the orientation property of the liquid crystal is lowered. Therefore, the amount is more preferably 0.5 to 20 parts by mass.

The liquid crystal aligning agent of the present invention may contain other than the polymer described in the present invention or a dielectric or conductive material for changing electric characteristics such as 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, and a crosslinkable compound for improving the hardness and denseness of the film when the film is used as a liquid crystal alignment film. Furthermore, when the coating film is fired, imidization of the polyamic acid is efficiently An imidization accelerator for the purpose of promoting the reaction may be added.

&Lt; Liquid crystal alignment film &

&Lt; Production method of liquid crystal alignment film &

The liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal aligning agent to a substrate, followed by drying and firing. 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. A plastic substrate such as a glass substrate, a silicon nitride substrate, an acrylic substrate or a polycarbonate substrate can be used. It is preferable from the viewpoint of simplification of the process. In a reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used only for a substrate on one side. In this case, a material for reflecting light such as aluminum can also be used as the electrode in this case.

Examples of the application method of the liquid crystal aligning agent of the present invention include a spin coating method, a printing method, and an ink jet method. The drying and firing steps after the application of the liquid crystal aligning agent of the present invention can be carried out at arbitrary temperature and time. Usually, the organic solvent is dried at 50 to 120 ° C for 1 to 10 minutes to remove the contained organic solvent, and then baked at 150 to 300 ° C for 5 to 120 minutes. The thickness of the coated film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may deteriorate. Therefore, it is 5 to 300 nm, preferably 10 to 200 nm.

Examples of a method for aligning the obtained liquid crystal alignment film include a rubbing method and an optical alignment treatment method.

The rubbing treatment can be carried out using an existing rubbing apparatus. The material of the rubbing cloth in this case is cotton, nylon, rayon, and the like. Conditions for the rubbing treatment are generally a condition of a rotational speed of 300 to 2000 rpm, a feed rate of 5 to 100 mm / s, and an indentation amount of 0.1 to 1.0 mm. Thereafter, the residue generated by rubbing is removed by ultrasonic cleaning using pure water, alcohol, or the like.

As a specific example of the photo-alignment treatment method, there is a method in which the surface of the above-mentioned coating film is irradiated with radiation deflected in a predetermined direction and, if necessary, a heat treatment is performed at a temperature of 150 to 250 ° C to give a liquid crystal aligning ability . As the radiation, ultraviolet rays and visible rays having a wavelength of 100 nm to 800 nm can be used. Of these, ultraviolet rays having a wavelength of 100 nm to 400 nm are preferable, and those having a wavelength of 200 nm to 400 nm are particularly preferable. In addition, in order to improve the liquid crystal alignment property, the coating film substrate may be irradiated with radiation while heating at 50 to 250 ° C. The irradiation dose of the radiation is preferably 1 to 10,000 mJ / cm 2, and particularly preferably 100 to 5,000 mJ / cm 2. The liquid crystal alignment film produced as described above can stably orient liquid crystal molecules in a certain direction.

The higher the extinction ratio of the polarized ultraviolet ray is, the higher the anisotropy can be given. Specifically, the extinction ratio of ultraviolet rays polarized in a straight line is preferably 10: 1 or more, more preferably 20: 1 or more.

In the above, the film irradiated with the polarized radiation may be subsequently subjected to a contact treatment with a solvent containing at least one species selected from water and an organic solvent.

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

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

In the present invention, the contact treatment of a film irradiated with polarized radiation and a solution containing an organic solvent is carried out by a treatment in which the film and the liquid preferably sufficiently come into contact, such as an immersion treatment, a spray (spray) treatment or the like. Among them, a method of immersing the film in a solution containing an organic solvent, preferably for 10 seconds to 1 hour, more preferably for 1 to 30 minutes, is preferable. The contact treatment may be carried out at room temperature, but is preferably carried out at 10 to 80 캜, more preferably at 20 to 50 캜. It is also possible to implement means for increasing the contact of ultrasonic waves or the like as necessary.

After rinsing with a low-boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone or the like, drying, or both, for the purpose of removing the organic solvent in the used solution, .

The film subjected to the contact treatment with a solvent in the above may be heated at 150 DEG C or higher for drying the solvent and re-orienting the molecular chains in the film.

The heating temperature is preferably 150 to 300 占 폚. The higher the temperature is, the more the molecular chain is reoriented. However, if the temperature is too high, the molecular chain may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 占 폚, and particularly preferably 200 to 230 占 폚.

If the heating time is too short, the effect of reorientation of the molecular chains may not be obtained. If the heating time is too long, the molecular chains may be decomposed. Therefore, the heating time is preferably 10 seconds to 30 minutes, more preferably 1 minute to 10 minutes Do.

In addition, the obtained liquid crystal alignment film can be easily dissolved in the recycled material, resulting in a film excellent in reworkability.

Examples of the solvent to be used in the rework 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? -Butyrolactone, methyl 2-hydroxypropionate, Ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydro Methyl 3-methylbutanoate, methyl 3-methoxypropionate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, Ethyl and butyl lactate; and amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone.

As the rework material, it is preferable that the solvent contains a basic component such as ethanolamine and an antirusting agent so that the alkali does not damage other members such as electrodes. Manufacturers of such rework materials include Korea Myung Myung Industrial Co., Ltd. and KPX Chemicals.

The rework is obtained by heating the above-mentioned riser material at room temperature or at 30 to 100 캜, immersing the substrate having the liquid crystal alignment film thereon for 1 second to 1000 seconds, preferably 30 seconds to 500 seconds Or by spraying the rework material in the form of a shower, removing the liquid, and washing it with an alcoholic solvent or pure water. The temperature of the rework solution at the time of reworking is preferably low at a temperature from the viewpoint of working efficiency and the like, and is usually from room temperature to 60 deg. C, more preferably from room temperature to 40 deg.

<Liquid crystal display element>

The liquid crystal display element of the present invention can be obtained by obtaining a substrate having a liquid crystal alignment film adhered thereto from the liquid crystal aligning agent of the present invention by the above production method of the liquid crystal alignment film and then producing a liquid crystal cell by a known method, It is.

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

First, a transparent glass substrate is prepared, a common electrode is formed on one substrate, and a segment electrode is formed on the other substrate. These electrodes can be, for example, ITO electrodes and are patterned so as to perform desired image display. Next, an insulating film is formed on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ -TiO ₂ formed by a sol-gel method.

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

Next, the other substrate is superimposed on one of the substrates so that the orientation film surfaces of the other substrates face each other, and the periphery is bonded with a sealant. For the sealing agent, a spacer is usually mixed in order to control the substrate gap. It is also preferable that a spacer for controlling the gap between the substrates be dispersed in the portion in the surface where the sealant is not formed. In the part of the sealant, an opening capable of filling the liquid crystal from the outside is formed.

Next, the liquid crystal material is injected into the spaces surrounded by the two substrates and the sealant through the openings formed in the sealant. Thereafter, this opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method using capillary phenomenon in the atmosphere may be used. Next, the polarizing plate is installed. More specifically, a pair of polarizers is attached to a surface of the two substrates opposite to the liquid crystal layer. Through the above steps, the liquid crystal display element of the present invention is obtained.

In the present invention, as the sealant, a resin which is cured by ultraviolet irradiation or heating having reactive groups such as epoxy group, acryloyl group, methacryloyl group, hydroxyl group, allyl group and acetyl group is used . In particular, it is preferable to use a cured resin system having both reactive groups of an epoxy group and a (meth) acryloyl group.

The sealing agent of the present invention may be blended with an inorganic filler for the purpose of improving adhesiveness and moisture resistance. The inorganic filler that can be used is not particularly limited, but specific examples include spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, barium sulfate , Calcium carbonate, 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, Preferred examples of the inorganic filler include inorganic fillers such as spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, , And aluminum silicate. These inorganic fillers may be used by mixing two or more kinds.

Since this liquid crystal display element uses a 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, it has excellent reworkability and can be suitably used for a liquid crystal television of a large screen and high precision.

Example

Hereinafter, the details of the production method of the present invention will be described with reference to experimental methods and results of examining the composition of raw materials and blending ratios, and examples of typical production methods. The present invention is not limited to these examples.

Explanation of the abbreviations used in this embodiment

(Organic solvent)

NMP: N-methyl-2-pyrrolidone

GBL:? -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)

Acid dianhydride (E): The following formula (E)

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)

DA-6: The following formula (DA-6)

DA-7: The following formula (DA-7)

DA-8: The following formula (DA-8)

DA-9: The following formula (DA-9)

DA-10: The following formula (DA-10)

AD-1: The following formula (AD-1)

AD-2: The following formula (AD-2)

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(57)

Hereinafter, methods of measurement of viscosity, measurement of imidization rate, evaluation of reworkability, manufacture of liquid crystal cell, and evaluation of charge relaxation property are described

[Measurement of viscosity]

In the synthesis examples, the viscosity of the polyamic acid ester and the polyamic acid solution was 1.1 ml of a sample amount, CORD-1 (1 ° 34 ', R24), and 25 ° C of the temperature, using an E-type viscometer TV-25H Lt; 0 &gt; C.

[Measurement of imidization rate]

(DMSO-d6, 0.05% TMS (tetramethylsilane) mixed product) was added to an NMR sample tube (NMR sampling tube standard 5 manufactured by Kusano Scientific Co., Ltd.) and 20 mg of polyimide powder was added to ultrasonic wave To complete dissolution. This solution was subjected to proton NMR measurement at 500 MHz using an NMR meter (JNW-ECA500) manufactured by Nippon DATUM Co., A proton originating from a structure which does not change before and after imidation is defined as a reference proton and the peak integrated value of the proton and the proton peak integrated value derived from the NH group of the amide acid appearing in the vicinity of 9.5 to 10.0 ppm By using the following formula.

Imidization ratio (%) = (1 -? X / y) x 100

In the above formula, x is the proton peak integrated value derived from the NH group of the amide acid, y is the peak integrated value of the reference proton, and? Is the NH of the amide acid in the case of the polyamic acid (imidation rate is 0% The ratio of the number of reference protons to one protopertone.

[Evaluation of reworkability]

The liquid crystal aligning agent of the present invention was applied to a Cr substrate by spin coating. Dried on a hot plate at 60 DEG C for 1 minute and 30 seconds, and then fired in a hot air circulating oven at 230 DEG C for 20 minutes to form a coating film having a film thickness of 100 nm. Subsequently, the substrate was immersed for 300 seconds in a lithographic printing plate material heated to 55 占 폚, developed, and then washed with ultrapure water for 20 seconds. Thereafter, the liquid crystal alignment film was completely blown by air blowing, and the case where the liquid crystal alignment film completely disappeared was indicated by x. The obtained results are shown in Table 3.

[Production of liquid crystal cell]

Thereby manufacturing a liquid crystal cell having a structure of Fringe Field Switching (FFS) mode liquid crystal display element.

First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm x 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a beta-pattern constituting the counter electrode as the first layer is formed. On the first layer counter electrode, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The thickness of the second-layer SiN film is 500 nm and functions as an interlayer insulating film. On the second-layer SiN film, a comb-like pixel electrode formed by patterning an ITO film as a third layer is disposed, and two pixels, i.e., a first pixel and a second pixel, are formed. The size of each pixel is 10 mm in length and 5 mm in width. At this time, the first layer counter electrode and the third layer pixel electrode are electrically insulated by the action of the second layer SiN film.

The third-layer pixel electrode has a comb-like shape formed by arranging a plurality of elongated electrode elements bent at a central portion. The width of each electrode element in the short direction is 3 占 퐉, and the interval between the electrode elements is 6 占 퐉. Since the pixel electrode forming each pixel is constituted by arranging a plurality of electrode elements bent at the center portion in the shape of a letter, the shape of each pixel is not a rectangular shape, Like shape. Each pixel is divided into upper and lower portions with the central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

When the first region and the second region of each pixel are compared with each other, the electrode elements of the pixel electrodes constituting the first region and the second region are different from each other. In other words, when the rubbing direction of a liquid crystal alignment film to be described later is taken as a reference, the electrode elements of the pixel electrodes are formed so as to form an angle of +10 degrees (clockwise rotation) in the first region of the pixel, The element is formed so as to form an angle (clockwise rotation) of -10 degrees. That is, in the first region and the second region of each pixel, the direction of the rotation operation (inflation / switching) of the liquid crystal caused by the application of the voltage between the pixel electrode and the counter electrode is opposite to each other Consists of.

Next, after filtering the resultant liquid crystal aligning agent with a filter of 1.0 占 퐉, a glass substrate having a prepared substrate on which the electrode was adhered and a columnar spacer having a height of 4 占 퐉 in which an ITO film was formed on the back surface was applied by spin coating Respectively. Dried on a hot plate at 80 DEG C for 5 minutes and then fired in a hot air circulating oven at 230 DEG C for 20 minutes to form a coating film having a thickness of 100 nm. This coating film was subjected to orientation treatment such as rubbing or polarized ultraviolet irradiation to obtain a substrate having a liquid crystal alignment film attached thereto. The two substrates were set as one set, a sealing agent was printed on the substrate, and another substrate was bonded to the liquid crystal alignment film so that the alignment direction was 0 ° as viewed from the face of the liquid crystal alignment film, To prepare empty cells. A liquid crystal MLC-2041 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 DEG C for 1 hour, left for one night, and used for evaluation.

[Charge relaxation property evaluation]

The liquid crystal cell was placed on a light source and the V-T characteristic (voltage-transmittance characteristic) at room temperature was measured. Then, the transmittance (Ta) of the liquid crystal cell in a state of applying a square wave of ± 1.5 V / 60 Hz was measured. Thereafter, the transmittance (Tb) of the liquid crystal cell was measured while the direct current 1 V was superposed and driven for 30 minutes, the DC voltage was cut off, and the liquid crystal cell was driven for 20 minutes only with a square wave of ± 1.5 V / 60 Hz The difference in transmittance caused by the voltage remaining in the liquid crystal display element was calculated from the transmittance (Tb, Tc) at each time and the difference (? T) between the initial transmittance (Ta). It is believed that as the residual voltage relaxes more quickly, burn-in is less likely to occur. (Tb - Ta) is 2% or less in 5 minutes after the start of the application of the direct current voltage, and X (Tc - Ta) is 2% or less in 5 minutes after the DC voltage is cut. The obtained results are shown in Table 3.

(Comparative Polymerization Example 1)

2.55 g of (DA-1) and 0.96 g of (DA-3) were added, and 25.7 g of NMP was added. While nitrogen was being supplied, the mixture was stirred at 23 ° C Lt; / RTI &gt; While stirring the diamine solution, 3.00 g of the acid dianhydride (C) was added, and further 11.2 g of NMP was added. After stirring at 23 ° C for 2 hours under a nitrogen atmosphere, 0.77 g of the acid dianhydride (D) , 4.4 g of NMP was further added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 50 DEG C for 16 hours to obtain a polyamic acid solution (PAA-1). The viscosity of this polyamic acid solution at 25 캜 was 358 cps.

(Comparative Polymerization Example 2)

A 50 ml four-necked flask equipped with a stirrer was charged with 2.55 g of (DA-1) and 0.46 g of (DA-2), and 22.3 g of NMP was added. Lt; / RTI &gt; While stirring the diamine solution, 2.00 g of the acid dianhydride (C) was added, and further 6.3 g of NMP was added. After stirring for 2 hours at 23 deg. C in a nitrogen atmosphere, 1.51 g of the acid dianhydride (D) 8.5 g of NMP was further added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 50 DEG C for 16 hours to obtain a polyamic acid solution (PAA-2). The viscosity of this polyamic acid solution at a temperature of 25 캜 was 333 cps.

(Polymerization Example 1)

A 100 ml four-necked flask equipped with a stirrer was charged with 0.58 g of (DA-6), 1.32 g of (DA-4), 0.93 g of (DA-5) g, 42.8 g of NMP was added, and the mixture was stirred at 23 DEG C while nitrogen was being supplied. While this diamine solution was stirred, 3.91 g of the acid dianhydride (E) was added, and further 12.4 g of NMP was added. The mixture was stirred at 40 占 폚 for 16 hours under a nitrogen atmosphere to obtain a polyamic acid solution (PAA-3) . The viscosity of this polyamic acid solution at 25 캜 was 450 cps.

(Polymerization Example 2)

6.19 g of (DA-9) and 2.14 g of (DA-8) were added and 61.1 g of NMP was added. While nitrogen was being supplied, the mixture was stirred at 23 ° C Lt; / RTI &gt; While stirring the diamine solution, 5.71 g of the acid dianhydride (B) was added, and further 18.5 g of NMP was added. The mixture was stirred at 50 占 폚 for 16 hours under a nitrogen atmosphere to obtain a polyamic acid solution (PAA-4). The viscosity of the polyamic acid solution at 25 캜 was 351 cps.

(Polymerization Example 3)

86.0 g of (DA-4), 53.4 g of (DA-7) and 76.5 g of (DA-10) were taken in a 1 l four-necked flask equipped with a stirrer and 1580 g of NMP was added , And dissolved with stirring at 23 DEG C while nitrogen was being supplied. While this diamine solution was stirred, 93.2 g of the acid dianhydride (E) was added, and further 168 g of NMP was added, and the mixture was stirred at 40 占 폚 for 3 hours under a nitrogen atmosphere. 28.2 g of the acid dianhydride (D) was further added, 160 g of NMP was further added, and the mixture was stirred at 23 캜 for 4 hours under a nitrogen atmosphere to obtain a solution of polyamic acid (PAA-5). The viscosity of this polyamic acid solution at 25 캜 was 200 mPa..

(Polymerization Example 4)

2.55 g of (DA-1) and 0.78 g of (DA-4) were added, and 24.4 g of NMP was added. While nitrogen was being supplied, the mixture was stirred at 23 ° C Lt; / RTI &gt; While stirring the diamine solution, 1.75 g of the acid dianhydride (B) was added, and further 4.3 g of NMP was added. After stirring at 23 占 폚 for 2 hours under a nitrogen atmosphere, 1.41 g of the acid dianhydride (D) , 8.0 g of NMP was further added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 50 DEG C for 16 hours to obtain a polyamic acid solution (PAA-6). The viscosity of this polyamic acid solution at a temperature of 25 캜 was 240 cps.

(Polymerization Example 5)

A 50 ml four-necked flask equipped with a stirrer was charged with nitrogen gas, and 2.55 g of (DA-1) and 0.49 g of (DA-2) were added and 22.3 g of NMP was added. Lt; / RTI &gt; While stirring the diamine solution, 2.35 g of the acid dianhydride (A) was added, and further 8.3 g of NMP was added. After stirring at 23 占 폚 for 2 hours under a nitrogen atmosphere, 1.80 g of the acid dianhydride (C) 10.2 g of NMP was further added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 70 DEG C for 16 hours to obtain a polyamic acid solution (PAA-7). The viscosity of this polyamic acid solution at a temperature of 25 캜 was 380 cps.

(Polymerization Example 6)

A 50 ml four-necked flask equipped with a stirrer was charged with nitrogen gas, and 2.55 g of (DA-1) and 0.49 g of (DA-2) were added and 22.3 g of NMP was added. Lt; / RTI &gt; While stirring the diamine solution, 2.35 g of the acid dianhydride (A) was added, and further 8.3 g of NMP was added. After stirring at 23 占 폚 for 2 hours under a nitrogen atmosphere, 1.41 g of the acid dianhydride (D) , 8.0 g of NMP was further added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 70 DEG C for 16 hours to obtain a polyamic acid solution (PAA-8). The viscosity of this polyamic acid solution at 25 캜 was 321 cps.

(Polymerization Example 7)

A 50 ml four-necked flask equipped with a stirrer was charged with nitrogen gas, and 2.55 g of (DA-1) and 0.49 g of (DA-2) were added and 22.3 g of NMP was added. Lt; / RTI &gt; While stirring the diamine solution, 1.41 g of the acid dianhydride (A) was added, and further 2.9 of NMP was added. After stirring for 2 hours at 23 占 폚 in a nitrogen atmosphere, 1.41 g of the acid dianhydride (B) , Further 7.9 g of NMP was added, and the mixture was stirred at 23 占 폚 for 2 hours under a nitrogen atmosphere. Thereafter, 1.00 g of the acid dianhydride (C) was added, and further 5.7 g of NMP was added. The mixture was stirred at 23 캜 for 2 hours under a nitrogen atmosphere. Thereafter, the mixture was stirred at 70 DEG C for 16 hours to obtain a polyamic acid solution (PAA-9). The viscosity of the polyamic acid solution at 25 캜 was 365 cps.

(Comparative Example 1)

6.73 g of the polyamic acid solution (PAA-3) obtained in the comparative synthesis example, 15.27 g of (PAA-1) and 2.40 g of the NMP solution containing 1 wt% of (AD-1) were added to a 50 ml Erlenmeyer flask containing the stirrer, 0.72 g of an NMP solution containing 10 wt% of (AD-2), 2.88 g of NMP and 12.00 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-1 ).

(Comparative Example 2)

4.00 g of the polyamic acid solution (PAA-4) obtained in the comparative synthesis example, 12.80 g of (PAA-2) and 2.40 g of the NMP solution containing 1 wt% of (AD-1) were placed in a 50 ml Erlenmeyer flask containing a stirrer. g, 8.80 g of NMP and 12.00 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-2).

(Comparative Example 3)

800 g of a solution of polyamic acid (PAA-5) obtained in (Polymerization Example 3) was added to a 3 L Erlenmeyer flask, 700 g of NMP, 69.7 g of acetic anhydride and 18.0 g of pyridine were added, For 30 minutes, and then reacted at 55 DEG C for 3 hours. The reaction solution was poured into 5600 g of methanol, and the resulting precipitate was separated by filtration. This precipitate was washed with methanol, and then dried under reduced pressure at a temperature of 60 ° C to obtain a polyimide powder. The imidization ratio of this polyimide powder was 75%.

20.4 g of this polyimide powder was dispensed into a 300 ml Erlenmeyer flask containing a stirrer and 150 g of NMP was added and dissolved by stirring at 50 DEG C for 20 hours to obtain a polyimide solution (SPI-1).

7.00 g of the polyimide solution (SPI-1) obtained above, 10.40 g of (PAA-6), 2.40 g of an NMP solution containing 1 wt% of (AD-1) 0.72 g of an NMP solution containing 10 wt% of the liquid crystal aligning agent (AD-2) was collected, 7.48 g of NMP and 12.00 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-3) .

(Examples 1 to 3)

7.00 g of the polyimide solution (SPI-1) obtained in (Comparative Example 3) and 10.40 g of the polyamic acid solution (PAA-7 to 9) obtained in (Polymerization Examples 5 to 7) were added to a 50 ml Erlenmeyer flask containing a stirrer. 2.40 g of an NMP solution containing 1 wt% of AD-1 and 0.72 g of an NMP solution containing 10 wt% of (AD-2) were collected, 7.48 g of NMP and 12.00 g of BCS were added And the mixture was stirred with a magnetic stirrer for 2 hours to obtain liquid crystal aligning agents (B-1 to 3) as shown in Table 1.

(Examples 4 to 6)

4.00 g of the polyamic acid solution (PAA-4) obtained in (Polymerization Example 2) and 12.80 g of the polyamic acid solution (PAA-7 to 9) obtained in Polymerization Examples 5 to 7 were added to a 50 ml Erlenmeyer flask containing the stirrer , 2.40 g of an NMP solution containing 1 wt% of (AD-1) was collected, 4.80 g of NMP and 12.00 g of BCS were added and stirred with a magnetic stirrer for 2 hours, (B-4-6) were obtained.

(Example 7)

6.00 g of the polyamic acid solution (PAA-7) obtained in the comparative synthesis example, 11.20 g of (PAA-1) and 2.40 g of the NMP solution containing 1 wt% of (AD-1) were placed in a 50 ml Erlenmeyer flask containing a stirrer. and 0.72 g of an NMP solution containing 10 wt% of (AD-2), 7.68 g of NMP and 12.00 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent B- ).

Industrial availability

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention can suppress the accumulation of charges due to the asymmetry of the AC drive in the IPS drive method or the FFS drive type liquid crystal display device and also reduce the residual charge accumulated by the DC voltage The IPS driving method and the FFS driving method liquid crystal display device having excellent afterimage characteristics can be obtained. Therefore, it is particularly useful as a liquid crystal display element of an IPS driving method, an FFS driving method, or a liquid crystal alignment film of a liquid crystal television.

Claims (11)

(A) a tetracarboxylic acid dianhydride represented by the following formula (1) and an aliphatic tetracarboxylic acid dianhydride in a ratio of 10:90 to 90:10 and a tetracarboxylic acid dianhydride represented by the following formula (2) At least one kind of polymer selected from the group consisting of a polyamic acid obtained by using a diamine component containing a diamine and a imidized polymer of the polyamic acid,
(B) at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor and a photosensitive side chain acrylic polymer which exhibits liquid crystallinity at a predetermined temperature range, and And a liquid crystal alignment agent.

(1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl, an ester bond, phenylene, a straight chain alkylene having 1 to 20 carbon atoms, A branched alkylene group having 3 to 12 carbon atoms, a cyclic alkylene group having 3 to 12 carbon atoms, a sulfonyl group, an amide bond, or a combination thereof, wherein the alkylene group having 1 to 20 carbon atoms is selected from an ester bond and an ether bond And the carbon atoms of phenylene and alkylene may be substituted with one or more of the same or different substituents selected from a halogen atom, a cyano group, an alkyl group, a haloalkyl group, an alkoxy group and a haloalkoxy group do.
In formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group and a nitrogen-containing heterocyclic ring, B ₁ and B ₂ each independently represent a hydrogen atom , Or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.) The method according to claim 1,
Characterized in that 10 to 100 mol% of the tetracarboxylic acid dianhydride component of the component (A) is a tetracarboxylic acid dianhydride represented by the formula (1) and an aliphatic tetracarboxylic acid dianhydride. . 3. The method according to claim 1 or 2,
A liquid crystal aligning agent characterized in that 10 to 100 mol% of the diamine component of the component (A) is a diamine of the formula (2). 4. The method according to any one of claims 1 to 3,
Wherein Y ₁ in the formula (2) is at least one selected from the structures of the following formulas (YD-1) to (YD-5).

(In the formula (YD-1), A ₁ is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms, and Z ₁ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. -2), W ₁ is a hydrocarbon group having 1 to 10 carbon atoms, A ₂ is a monovalent organic group having 3 to 15 carbon atoms and a nitrogen-containing heterocyclic group, or a di W ₂ is a divalent organic group having 6 to 15 carbon atoms and 1 to 2 benzene rings and W ₃ is an alkylene or biphenyl group having 2 to 5 carbon atoms. and alkylene is, Z ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a benzene ring, a is an integer from 0 to 1. for expression in (YD-4), a ₃ is a nitrogen atom having a carbon number of 3-15 is a heterocyclic ring. in the formula (YD-5), a ₄ is a heterocyclic ring containing the nitrogen atom of a carbon number of 3 ~ 15, W ₅ are burnt Be an alkylene of 2-5.) 5. The method of claim 4,
A ₁ , A ₂ , A ₃ and A ₄ described in the formulas (YD-1), (YD-2), (YD-4) and (YD- Wherein the liquid crystal aligning agent is at least one kind selected from the group consisting of pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyrazine, indole, benzimidazole, quinoline and isoquinoline. 6. The method according to any one of claims 1 to 5,
, Wherein Y ₁ in the formula (2) is at least one kind selected from the group consisting of divalent organic groups having structures of the following formulas (YD-6) to (YD-21).

(In the formula (YD-17), h is an integer of 1 to 3, and in the formulas (YD-14) and (YD-21), j is an integer of 1 to 3.) The method according to claim 6,
A liquid crystal aligning agent characterized in that Y ₁ in the formula (2) is at least one selected from the group consisting of divalent organic groups having the structures of the formulas (YD-14) and (YD-18). 8. The method according to any one of claims 1 to 7,
Wherein the tetracarboxylic acid dianhydride represented by the formula (1) is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride. 9. The method according to any one of claims 1 to 8,
Wherein the aliphatic tetracarboxylic acid dianhydride is bicyclo [3.3.0] octane 2,4,6,8-tetracarboxylic acid 2,4: 6,82 anhydride. A liquid crystal alignment film obtained by applying and firing the liquid crystal aligning agent according to any one of claims 1 to 9. 11. A liquid crystal display element comprising the liquid crystal alignment film according to claim 10.