TWI813994B - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

A liquid crystal alignment agent characterized by containing: (A) Tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the following formula (1) using a ratio of 10:90 to 90:10 At least one selected from a polyamic acid obtained by reacting a carboxylic dianhydride component and a diamine component containing a diamine represented by the following formula (2) and an imidized polymer of the polyamic acid Polymer, (B) A group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side chain acrylic polymer having liquid crystallinity within a specific temperature range At least one selected polymer, and an organic solvent.

Description

Liquid crystal alignment agents, liquid crystal alignment films, and liquid crystal display components

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

Conventionally, liquid crystal devices have been widely used in display parts of personal computers, mobile phones, video receivers, and the like. A liquid crystal device, for example, includes a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, and a switching pair. Thin film transistors (TFTs) that provide electrical signals to pixel electrodes, etc. Known driving methods for liquid crystal molecules include, for example, longitudinal electric field methods such as TN method and VA method, or transverse electric field methods such as IPS method and wide viewing angle switching (hereinafter, FFS) method (for example, Patent Document 1).

On the other hand, in recent years, because the economy of the production steps of liquid crystal display elements or organic EL elements has become an extremely important factor, recycling of element substrates has also begun to be sought. That is, a method is sought that can be used to easily remove the liquid crystal alignment film from the substrate and recycle the substrate when a defect is found during alignment inspection after the liquid crystal alignment film is formed from the liquid crystal alignment agent. steps. However, liquid crystal alignment films prepared from these conventionally proposed liquid crystal alignment agents are often made insoluble in organic solvents after post-baking, in order to reduce film loss, etc. In addition, the composition of the reproducible liquid crystal alignment agent that has been studied so far is difficult to achieve the desired purpose even if it is used as the composition of the liquid crystal alignment agent for lateral electric fields. Therefore, it is necessary to re-evaluate the actual liquid crystal alignment agent. Whether it has excellent reproducibility and whether the optimal composition can be achieved must be re-examined.

In addition, liquid crystal display elements are currently widely used in display devices. The liquid crystal alignment film, which is a component of a liquid crystal display element, is a film that requires uniform alignment of liquid crystals. Therefore, it must not only have uniform liquid crystal alignment, but also must have various other characteristics. For example, in the manufacturing process of a liquid crystal alignment film, it is generally necessary to use a cloth to perform an alignment treatment of wiping and rubbing the surface of the polymer film. However, if the friction resistance of the liquid crystal alignment film is insufficient, damage to the film, dust, and peeling of the film itself will often occur, resulting in a reduction in the display quality of the liquid crystal display element. In addition, the liquid crystal display element drives the liquid crystal by applying a voltage. Therefore, if the voltage retention rate (VHR) of the liquid crystal alignment film is too low, sufficient voltage will not be applied to the liquid crystal, resulting in display contrast degradation. In addition, due to the influence of the voltage that drives the liquid crystal, charges will be accumulated in the liquid crystal alignment film, or if the accumulated charges are removed for too long, afterimages or display afterimages will also occur.

There are currently various proposals that can satisfy the above requirements at the same time. For example, Patent Document 2 and others have proposed a method of manufacturing a liquid crystal alignment film with excellent friction resistance and less afterimages or afterimages. In addition, Patent Document 3 and others also propose a method of manufacturing a liquid crystal alignment film that has excellent liquid crystal alignment, alignment regulating force, friction resistance, high voltage retention, and can reduce charge accumulation. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2013-167782 [Patent Document 2] International Publication No. WO02/33481 [Patent Document 3] International Publication No. WO2004/053583

[Problem to be solved by the invention]

The present invention aims to provide a liquid crystal alignment agent that can produce a liquid crystal alignment film that satisfies various characteristics necessary for a liquid crystal alignment film and also has excellent reproducibility. [Methods to solve problems]

As a result of in-depth research to solve the above-mentioned problems, the inventors found that a polyamide obtained by using a tetracarboxylic acid containing a specific aromatic tetracarboxylic dianhydride and an aliphatic tetracarboxylic dianhydride and a diamine having a specific structure is used. When an imidized polymer of an amino acid and a polyamide acid is used, it can satisfy various characteristics necessary for a liquid crystal alignment film and also have an excellent reproducibility of the liquid crystal alignment film. Therefore, the present invention has been completed.

That is, the present invention was proposed based on the above results, and has the following main contents. 1. A liquid crystal alignment agent, characterized by containing: (A) A tetracarboxylic dianhydride component containing the following formula using tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the following formula (1) in a ratio of 10:90 to 90:10 (2) At least one polymer selected from the polyamic acid obtained by reacting the diamine component of the diamine represented and the imidized polymer of the polyamic acid, (B) Selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side chain acrylic polymer having liquid crystallinity within a specific temperature range at least 1 polymer, and organic solvents;

(In formula (1), i is 0 or 1, and A branched alkylene group of 20, a cyclic alkylene group having 3 to 12 carbon atoms, a sulfonyl group, a amide bond, or a group formed by a combination thereof, wherein the alkylene group having 1 to 20 carbon atoms , can be interrupted by bonds selected from ester bonds and ether bonds. The carbon atoms of phenyl and alkylene groups can be interrupted by halogen atoms, cyano groups, alkyl groups, haloalkyl groups, alkoxy groups and halogen atoms. The alkoxy group is substituted by one or more identical or different substituents selected from the group.

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

2. The liquid crystal alignment agent as described in 1, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component of component (A) is tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the aforementioned formula (1). Carboxylic dianhydride.

3. The liquid crystal alignment agent as described in 1 or 2, wherein 10 to 100 mol% of the diamine component of component (A) is the diamine of formula (2).

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

(In formula (YD-1), A ₁ is a heterocyclic ring containing nitrogen atoms with 3 to 15 carbon atoms, and Z ₁ is a hydrogen atom, or a hydrocarbon group with 1 to 20 carbon atoms that may have a substituent; Formula (YD-2) ), W ₁ is a hydrocarbon group with 1 to 10 carbon atoms, and A ₂ is a monovalent organic group with 3 to 15 carbon atoms in a heterocyclic ring containing nitrogen atoms, or is substituted by an aliphatic group with 1 to 6 carbon atoms. A disubstituted amino group. In the formula (YD-3), W ₂ is a divalent organic group with 6 to 15 carbon atoms and 1 to 2 benzene rings, and W ₃ is an alkylene group with 2 to 5 carbon atoms. Or a biphenyl group, Z ₂ is a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, or a benzene ring, a is an integer from 0 to 1. In formula (YD-4), A ₃ is an alkyl group with 3 to 15 carbon atoms. Heterocyclic ring containing nitrogen atoms. In the formula (YD-5), A ₄ is a heterocyclic ring containing nitrogen atoms with 3 to 15 carbon atoms, and W ₅ is an alkylene group with 2 to 5 carbon atoms).

5. The liquid crystal alignment agent as described in 4, wherein A ₁ , A ₂ , A 3 , and A are described in formulas (YD-1), (YD-2), (YD-4), and (YD- ₅ ) ₄ , consisting of pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyridine At least one selected from the group consisting of , indole, benzimidazole, quinoline and isoquinoline.

6. The liquid crystal alignment agent according to any one of 1 to 5, wherein Y ₁ in the formula (2) is a divalent organic compound having the structure of the following formulas (YD-6) to (YD-21). At least one type selected from the group formed by the base.

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

7. The liquid crystal alignment agent as described in 6, wherein Y ₁ in the formula (2) is selected from the group of divalent organic groups having the structures of the above formulas (YD-14) and (YD-18). At least 1 of them.

8. The liquid crystal alignment agent according to any one of 1 to 7, wherein the tetracarboxylic dianhydride represented by the aforementioned formula (1) is 3,3’,4,4’-biphenyl tetracarboxylic dianhydride.

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

10. A liquid crystal alignment film, characterized in that it is obtained by coating and sintering the liquid crystal alignment agent described in any one of 1 to 9.

11. A liquid crystal display element, characterized by having the liquid crystal alignment film described in 10. [Effects of the invention]

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can suppress charge accumulation caused by asymmetry of AC drive and also has excellent reproducibility. [Form of carrying out the invention]

The liquid crystal alignment agent of the present invention is characterized by containing: (A) A tetracarboxylic dianhydride component containing the following formula using tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the following formula (1) in a ratio of 10:90 to 90:10 (2) At least one polymer selected from the polyamic acid obtained by reacting the diamine component of the diamine represented and the imidized polymer of the polyamic acid, (B) Selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side chain acrylic polymer having liquid crystallinity within a specific temperature range at least 1 polymer, and organic solvents.

In formula (1), i is 0 or 1, and A branched alkylene group, a cyclic alkylene group having 3 to 12 carbon atoms, a sulfonyl group, an amide bond, or a group formed by a combination thereof, wherein the alkylene group having 1 to 20 carbon atoms, Can be interrupted by bonds selected from ester bonds and ether bonds. The carbon atoms of phenyl and alkylene groups can be interrupted by halogen atoms, cyano groups, alkyl groups, haloalkyl groups, alkoxy groups and haloalkyl groups. The oxygen group is substituted by one or more identical or different substituents selected from the oxygen group. In the formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amine group, an imine group, and a nitrogen-containing heterocycle, and B ₁ to B ₂ each represent independently A hydrogen atom, or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Each component will be described in detail below.

＜(A) Ingredient＞ The (A) component used in the liquid crystal alignment agent of the present invention is: a tetracarboxylic acid dianhydride represented by the above formula (1) and an aliphatic tetracarboxylic dianhydride containing a ratio of 10:90 to 90:10. A polyamic acid obtained by reacting an acid dianhydride component with a diamine component containing a diamine represented by the above formula (2) and at least one polymer selected from an imidized polymer of the polyamic acid .

＜Tetracarboxylic dianhydride ingredients＞ The tetracarboxylic dianhydride represented by the above formula (1) includes, for example, the compounds listed below, but is not limited thereto.

(In the formula, q represents an integer from 1 to 20).

From the viewpoint of the tetracarboxylic dianhydride represented by the formula (1) having a highly improved reproducibility effect, the tetracarboxylic dianhydride represented by the formula (1) is one in which i is 1, that is, a tetracarboxylic dianhydride having two or more benzene rings. Tetracarboxylic dianhydride is preferred. Among the above specific examples, (1-2) to (1-11) are preferred. From the viewpoint of containing both a biphenyl structure and a rigid structure, formula (1-5 ) represented by 3,3',4,4'-biphenyltetracarboxylic dianhydride is particularly preferred.

The specific aliphatic tetracarboxylic dianhydride used in the present invention is, for example, the tetracarboxylic dianhydride represented by the following formula (3).

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

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, and preferably a hydrogen atom or a methyl group.

Among the above, (X-1) to (X-20) are preferred in that they do not contain aromatic moieties, and (X-10) is particularly preferred in that thermal imidization is difficult to proceed.

The total amount of tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the formula (1) of the present invention is based on the total amount of the tetracarboxylic dianhydride component used in producing component (A). If it is too small, the effect of the present invention will not be obtained. Therefore, the total amount of tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by formula (1) is preferably 10 to 100 mol%, more preferably, based on 1 mole of total tetracarboxylic dianhydride. It is 50-100 mol%, especially preferably 80-100 mol%.

The content ratio of the tetracarboxylic dianhydride and the aliphatic tetracarboxylic dianhydride represented by the formula (1) is a ratio of 10:90 to 90:10, but is preferably 20:80 to 80:20, particularly preferably The ratio of 40:60 to 60:40, the best is 46:54 to 54:46, which is essentially the best in terms of equivalents.

The tetracarboxylic dianhydride and the aliphatic tetracarboxylic dianhydride represented by the formula (1) can be used individually, or a plurality of them can be used in combination. In this case, the tetracarboxylic acid represented by the formula (1) The total amount of dianhydride and aliphatic tetracarboxylic dianhydride is preferably the above-mentioned preferred amount.

The polyamide contained in the liquid crystal alignment agent of the present invention, in addition to the tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride represented by the formula (1), can also be the polyamide represented by the following formula (4). Carboxylic dianhydride.

In 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), etc.

<Diamine component> The diamine component used when producing the liquid crystal alignment agent of the present invention is a diamine containing the above formula (2). In the formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amine group, an imine group, and a nitrogen-containing heterocycle, and B ₁ to B ₂ each represent independently 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, cyclohexyl, and the like. Alkenyl groups, for example, those in which one or more CH-CH structures present in the above-mentioned alkyl groups are replaced by C=C structures, more specifically, for example, vinyl, allyl, 1-propenyl, iso Propenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl, etc. Alkynyl group, for example, one or more of the CH ₂ -CH ₂ structures present in the aforementioned alkyl group is replaced by a C≡C structure, more specifically, for example, ethynyl, 1-propynyl, 2-propynyl Alkynyl etc.

When the above-mentioned alkyl group, alkenyl group, and alkynyl group all have 1 to 10 carbon atoms, they may have a substituent, and may further form a ring structure through the substituent. Moreover, the meaning of forming a ring structure via a substituent means that the substituents are bonded to each other or to a part of the main skeleton to form a ring structure.

Examples of the substituent include, for example, a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organic oxygen group, an organic thio group, an organic silyl group, a hydroxyl group, an ester group, a thioester group, a phosphate ester group, and a hydroxyl group. Amino group, alkyl group, alkenyl group, alkynyl group, etc.

The halogen group as the substituent includes, for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Aryl groups as substituents include, for example, phenyl groups. The aryl group may be further substituted by other substituents mentioned above.

The organic oxygen group as a substituent may, for example, have a structure represented by O-R. The R may be the same or different, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, etc. are exemplified. Among these, R may be further substituted by the aforementioned substituents. Specific examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, and the like.

The organic sulfide group as a substituent is, for example, a structure represented by -S-R. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. Among these, R may be further substituted by the aforementioned substituents. Specific examples of the alkylthio group include methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, and octylthio.

The organosilane group as the substituent is, for example, a structure represented by -Si-(R) ₃ . The R may be the same or different, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, etc. are exemplified. Among these, R may be further substituted by the aforementioned substituents. Specific examples of alkylsilyl groups include trimethylsilyl, triethylsilyl, tripropylsilyl, tributylsilyl, tripentylsilyl, trihexylsilyl, and pentyldimethyl Silyl, hexyldimethylsilyl, etc.

The acyl group as a substituent is, for example, a structure represented by -C(O)-R. Examples of R include the aforementioned alkyl group, alkenyl group, aryl group, and the like. Among these, R may be further substituted by the aforementioned substituents. Specific examples of the acyl group include formyl, acetyl, propyl, butyl, isobutyl, pentyl, isopentyl, benzyl, and the like.

Ester group as a substituent, for example, -C(O)O-R, or The structure represented by -OC(O)-R. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. Among these, R may be further substituted by the aforementioned substituents.

The thioester group as a substituent has, for example, a structure represented by -C(S)O-R or -OC(S)-R. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, and aryl group. Among these, R may be further substituted by the aforementioned substituents.

The phosphate group as a substituent is, for example, a structure represented by -OP(O)-(OR) ₂ . The R may be the same or different, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, etc. are exemplified. Among these, R may be further substituted by the aforementioned substituents.

The amide group as a substituent, for example, -C(O)NH ₂ , or -C(O)NHR, -NHC(O)R, -C(O)N(R) ₂ , -NRC(O)R the structure represented. The R may be the same or different, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, etc. are exemplified. Among these, R may be further substituted by the aforementioned substituents.

The aryl group as a substituent is, for example, the same as the aryl group described above. The aryl group may be further substituted by other substituents mentioned above.

The alkyl group as a substituent is, for example, the same as the alkyl group described above. This alkyl group may be substituted by other substituents mentioned above.

The alkenyl group as a substituent is, for example, the same as the above-mentioned alkenyl group. This alkenyl group may be further substituted by other substituents mentioned above.

The alkynyl group as a substituent is, for example, the same as the alkynyl group described above. The alkynyl group may be substituted by other substituents mentioned above.

Generally speaking, when a giant structure is introduced, the reactivity or liquid crystal alignment of the amine group can be reduced. Therefore, B ₁ and B ₂ are, for example, hydrogen atoms or alkyl groups with 1 to 5 carbon atoms that may have substituents. Preferred are hydrogen atoms, methyl or ethyl groups.

The structure of Y ₁ in formula (2) is not particularly limited as long as it has at least one structure selected from the group consisting of an amine group, an imine group, and a nitrogen-containing heterocycle. . Therefore, specific examples include those having at least 1 selected from the group consisting of an amine group, an imine group, and a nitrogen-containing heterocycle represented by the following formulas (YD-1) to (YD-5). The structure of the species is a divalent organic radical.

In the formula (YD-1), A ₁ is a nitrogen atom-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 with 1 to 10 carbon atoms, and A ₂ is a monovalent organic group with 3 to 15 carbon atoms in a heterocyclic ring containing a nitrogen atom, or is substituted by a hydrocarbon group with 1 to 6 carbon atoms. A disubstituted amine group substituted by an aliphatic group.

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

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

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

A 1 , A 2 , A 3 of formula (YD-1), (YD- ₂ ), (YD-4), and (YD- _{5 )} , and a nitrogen-containing heterogeneous compound with a carbon number of 3 to 15 in A ₄ The ring, for example, is not particularly limited as long as it has a known structure. Among them, for example, pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyridine, , indole, benzimidazole, quinoline, isoquinoline, carbazole, etc., and piperazine, piperidine, indole, benzimidazole, imidazole, carbazole, and pyridine are preferred.

Furthermore, specific examples of Y ₂ in the formula (2) include, for example, a divalent organic group having a nitrogen atom represented by the following formulas (YD-6) to (YD-38). From the viewpoint of charge accumulation, formulas (YD-14) to (YD-21) are preferred, and (YD-14) and (YD-18) are particularly preferred.

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

In (Formula YD-24), (YD-25), (YD-28) and (YD-29), j is an integer from 0 to 3.

The proportion of the diamine represented by the formula (2) in the polyamic acid and the imidized polymer of the polyamic acid of the present invention is 10 to 100 mol% relative to 1 mole of the total diamine. Best, more preferably 30-100 mol%, particularly preferably 50-100 mol%.

The diamine represented by formula (2) in the polyamic acid and the imidized polymer of polyamic acid as component (A) of the present invention can be used alone or in combination. In this case, the total amount of the diamine represented by the formula (2) is preferably the above-mentioned preferred amount.

As the polyamide contained in the liquid crystal alignment agent of the present invention, in addition to the diamine represented by the above formula (2), the diamine represented by the following formula (5) can also be used. Y ₂ in the following formula (5) is a divalent organic group, and its structure is not particularly limited, and two or more types may be mixed and used. Moreover, the following specific examples include (Y-1) to (Y-49) and (Y-57) to (Y-75).

In the polyamic acid and the imidized polymer of polyamic acid as component (A) contained in the liquid crystal alignment agent of the present invention, if the proportion of the diamine represented by formula (5) is too high, the composition will be damaged. The possibility of inventive effect is not good. Therefore, the ratio of the diamine represented by the formula (5) is preferably 0 to 90 mol% based on 1 mol of the total diamine, more preferably 0 to 50 mol%, and particularly preferably 0 to 20 mol%. Ear%.

＜Production method of polyamide＞ The polyamide precursor of the polyimide used in the present invention can be synthesized according to the method shown below.

Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at -20 to 150°C, preferably between 0 to 70°C, for 30 minutes to 24 hours, preferably 1 to 12 hours Synthesized by hour reaction.

From the perspective of the solubility of monomers and polymers, organic solvents used in the above reactions include N,N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc. Preferably, one type of these may be used or two or more types may be mixed and used.

The concentration of the polymer is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is unlikely to occur and a high molecular weight body is easily obtained.

When the polyamide obtained by the above method is fully stirred and a poor solvent is injected into the reaction solution, the polymer can be precipitated and recovered. In addition, the purified polyamide powder can be obtained by precipitating several times, washing with a poor solvent, and drying at room temperature or under heating. The lean solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene, etc. Water, methanol, ethanol, 2-propanol, etc. Propanol is preferred.

＜Production method of polyimide＞ The polyimide used in the present invention can be produced by subjecting the aforementioned polyamide acid to an imidization reaction.

To produce polyimide from polyamic acid, a simple chemical imidization reaction is carried out by adding a catalyst to a solution of the aforementioned polyamide obtained by reacting a diamine component with a tetracarboxylic dianhydride. method. Chemical imidization can carry out the imidization reaction at a lower temperature, and the molecular weight of the polymer is not easily reduced during the imidization process, so it is preferable.

Chemical imidization is carried out by stirring the polymer to be imidized in an organic solvent in the presence of an alkaline catalyst and an acid anhydride. As the organic solvent, the solvent used in the aforementioned polymerization reaction can be used. Examples of the alkaline catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferred because it can maintain appropriate alkalinity during the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, acetic anhydride is preferred because it is easy to purify after completion of the reaction.

The temperature during the imidization reaction can be -20 to 140°C, preferably 0 to 100°C, and the reaction time is within 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mol times of the polyamide acid base, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times of the polyamide acid base, preferably 3~30 molar times. The imidization rate of the obtained 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 polyamide acid, the following method is used to recover the obtained imidized polymer and redissolve it in an organic solvent. , is preferred as the liquid crystal alignment agent of the present invention.

Pour the polyimide solution obtained in the above manner into a poor solvent with sufficient stirring to precipitate the polymer. After several precipitations, washing with a poor solvent, and drying at room temperature or under heating, the purified polymer powder can be obtained.

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

＜(B) Ingredient＞ The (B) component contained in the liquid crystal alignment agent of the present invention is composed of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side that has liquid crystallinity within a specific temperature range. At least one polymer selected from the group consisting of chain acrylic polymers.

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

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

Specific examples of the above alkyl group in R ₁₁ include, for example, methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl Key et al. From the viewpoint of being easily imidized by heating, R ₁₁ is preferably a hydrogen atom or a methyl group.

In formula (11), X ₁₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. In the polyimide precursor, X ₁₁ can be a mixture of two or more types. Specific examples of X ₁₁ include structures of the following formulas (X-1) to (X-44).

R ₈ to R ₁₁ in the above 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; R When ₈ to R ₁₁ have a huge structure, there is a possibility of reducing the alignment of the liquid crystal. Therefore, hydrogen atoms, methyl groups, and ethyl groups are preferred, and hydrogen atoms or methyl groups are particularly preferred.

In formula (11), X ₁₁ preferably contains a structure selected from (X-1) to (X-14) from the viewpoint of monomer availability.

The preferred ratio of the structures selected from the above formulas (X-1) to (X-14) is, for example, 20 mol% or more of the total X ₁₁ , more preferably 60 mol% or more, and particularly preferably 80 mol%. %above.

In formula (11), A ₁₁ and A ₁₂ each independently represent 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, or an alkenyl group having 2 to 10 carbon atoms which may have a substituent. An alkynyl group with 2 to 10 carbon atoms.

The specific examples or preferred examples of A ₁₁ and A ₁₂ are the same as B ₁ and B ₂ in the above-mentioned components (A-1) and (A-2).

In formula (11), Y ₁₁ is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of the structure of Y ₁₁ include the above-mentioned (Y-1) to (Y-49) and (Y-57) to (Y-75) or (YD) described in the section of component (A). -6)～(YD-38). Furthermore, examples include the following (Y-76) to (Y-97), and (YD-39) to (YD-52).

(In formula (YD-50), m and n are integers from 1 to 11 respectively, and m+n is an integer from 2 to 12).

The structure of Y ₁₁ is preferably at least one selected from the structures represented by the following formulas (15) and (16) from the viewpoint of liquid crystal alignment or pretilt angle of the obtained liquid crystal alignment film.

In formula (15), R ₁₂ is a single bond or a divalent organic group having 1 to 30 carbon atoms, R ₁₃ is a hydrogen atom, a halogen atom or a monovalent organic group having 1 to 30 carbon atoms, and a is 1 to 30 carbon atoms. When a is an integer of 4 and is 2 or more, R ₁₂ and R ₁₃ may be the same or different from each other. R ₁₄ in formula (16) is a single bond, -O-, -S-, -NR ₁₅ -, amide bond, ester bond, urea bond, or a divalent organic group with 1 to 40 carbon atoms, and R ₁₅ is a hydrogen atom or a methyl group.

Specific examples of Formula (15) and Formula (16) include, for example, the following structures. Because it has a highly linear structure, it can improve the alignment of liquid crystal when used as a liquid crystal alignment film. Therefore, Y ₁₁ is, for example, the aforementioned Y-7, Y-21, Y-22, Y-23, Y-25, Y -43, Y-44, Y-45, Y-46, Y-48, Y-63, Y-71, Y-72, Y-73, Y-74, Y-75 are better. In order to improve liquid crystal alignment, the proportion of the above structure is preferably 20 mol% or more of the total Y ₁₁ , more preferably 60 mol% or more, and particularly preferably 80 mol% or more.

From the viewpoint of increasing the pretilt angle of liquid crystal when used as a liquid crystal alignment film, the side chain of Y ₁₁ is preferably a structure having a long-chain alkyl group, an aromatic ring, an aliphatic ring, a cholesterol skeleton, or a combination thereof. These Y ₁₁ are, for example, Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, Y-86 , Y-87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96, Y-97 are preferred. When the pretilt angle is increased, the proportion of the above structure is preferably 1 to 30 mol% of the total Y ₁₁ , and more preferably 1 to 20 mol%.

Furthermore, when using a polyimide (precursor) having a photoalignable side chain as the polymer of component (B), it is preferable to use a polyimide (precursor) having the following photoreactive side chains. .

(R ¹⁶ represents -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ )-, -CON( Either CH ₃ )- or -N(CH ₃ )CO-, R ¹⁷ represents a cyclic, unsubstituted or alkylene group having 1 to 20 carbon atoms that may be substituted by a fluorine atom, where Any -CH ₂ - in the alkyl group can be substituted by -CF ₂ - or -C=C-. If any of the groups listed below are not adjacent to each other, they can also be substituted by these groups. ;-O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, carbocyclic, heterocyclic. R ¹⁸ represents -CH ₂ -, -O-, -COO-, -OCO- , -NHCO-, -NH-, -N(CH ₃ )-, -CON(CH ₃ )-, -N(CH ₃ )CO-, any one of carbocyclic rings, or heterocyclic rings, R ¹⁹ represents Vinyl phenyl group, -CR ²⁰ =CH ₂ group, -CR ²⁰ (OH)-CH ₃ group, carbocyclic ring, heterocyclic ring or a structure represented by a formula selected from the following group, R ²⁰ represents a hydrogen atom or a methyl group replaced by a fluorine atom).

When producing these polyimide precursors, it is a simple choice to use a diamine substituted with a side chain represented by the above formula (b).

In addition, a polyimide precursor having a photoalignment group in the main chain may also be used. In this case, it is a simple choice to use a diamine having a photo-alignment group-containing bond between amines as represented by the following formula (21).

(In formula (21), X ^{21 is a single bond or an alkylene group with 1 to 5 carbon atoms; X 22 is} -OCO-CH=CH- or -CH=CH-COO-; Alkylene group of 1 to 10 or divalent benzene ring, X ²⁴ is a single bond, -OCO-CH=CH- or -CH=CH-COO-, X ²⁵ is a single bond or an alkylene ring with 1 to 5 carbon atoms group. However, it has one or more cinnamoyl groups.

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

(In the formula, X is an independent single bond or ether (-O-), ester The bonding group selected from (-COO- or -OCO-) and amide (-CONH- or -NHCO-), Y is an independent single bond or an alkylene group with 1 to 5 carbon atoms, and Z is an independent carbon An alkylene group or phenylene group having a number of 1 to 10. The bonding position of the amine group on the benzene ring or the position of the bonding group relative to the central benzene ring is not particularly limited).

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

It is formed by using the diamine represented by the above formula (21) as a raw material and containing a polyamide precursor such as polyamide acid, polyamide ester, polyamide or polyamide. The liquid crystal alignment film can reduce changes in liquid crystal alignment performance caused by AC (alternating current) driving, such as reducing changes in liquid crystal alignment orientation. Therefore, the liquid crystal display element having the liquid crystal alignment film can stabilize the liquid crystal alignment performance of the liquid crystal alignment film due to AC driving, and will be less likely to produce afterimages caused by AC driving, that is, the afterimages caused by AC driving can be eliminated. The imaging characteristics achieve very good results. In addition, the liquid crystal alignment film formed using the diamine represented by the above formula (21) has excellent liquid crystal alignment performance itself and has no substantial alignment defects.

The polyamide precursor used in the present invention is obtained by reacting a diamine component with a tetracarboxylic acid derivative, such as polyamide acid or polyamide ester.

＜Production of polyimide precursor-polyamide acid＞ The manufacturing method of polyamic acid described in component (A-1) and component (A-2) shall prevail.

＜Production of polyimide precursor-polyamide ester＞ The polyamide ester of the polyimide precursor used in the present invention can be produced according to the following preparation method (1), (2) or (3).

(1) When made from polyamide Polyamide ester can be obtained by esterification of polyamide acid prepared according to the above method. Specifically, the polyamide and the esterification agent are processed in the presence of an organic solvent at -20°C to 150°C, preferably between 0°C and 50°C, for 30 minutes to 24 hours, preferably 1 to 150°C. It can be obtained after 4 hours of reaction.

The esterifying agent is preferably one that can be easily removed through purification, such as N,N-dimethylformamide dimethyl acetal and N,N-dimethylformamide diethyl acetal. , N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dineopentylbutyl acetal, N,N-dimethylformamide di-t- Butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene, 4-(4,6-dimethoxy-1,3,5-tri -2-yl)-4-methylmorpholinium chloride, etc. The amount of the esterification agent added is preferably 2 to 6 molar equivalents relative to 1 mole of the repeating unit of the polyamide acid.

Organic solvents, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N,N-dimethylformamide, N,N-dimethyl Acetamide, dimethylstyrene or 1,3-dimethyl-imidazolinone, etc. In addition, when the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formula [D -1]~solvent represented by formula [D-3].

These solvents may be used individually or in mixture. In addition, even if it is a solvent that does not dissolve the polyimide precursor, it can be mixed with the solvent as long as the generated polyimide precursor is not precipitated. In addition, the moisture in the solvent will hinder the polymerization reaction and cause the generated polyimide precursor to be hydrolyzed. Therefore, it is better to dehydrate and dry the solvent before use.

The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidinone, or γ-butyrolactone from the viewpoint of polymer solubility. These can be used alone or in combination of two or more types. The concentration during production is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is less likely to occur and a high molecular weight body is easily produced.

(2) Production by reaction of tetracarboxylic acid diester dichloride and diamine Polyamide ester can be prepared from tetracarboxylic acid diester dichloride and diamine.

Specifically, tetracarboxylic acid diester dichloride and diamine are processed in the presence of an alkali and an organic solvent at -20°C to 150°C, preferably between 0°C and 50°C, for 30 minutes to 24 hours. , preferably it can be obtained by reacting for 1 to 4 hours.

Among the aforementioned bases, pyridine, triethylamine, 4-dimethylaminopyridine, etc. can be used, but pyridine is preferably used because the reaction proceeds stably. The added amount of alkali is an amount that can be easily removed and from the viewpoint of easily obtaining a high molecular weight body, it is preferably 2 to 4 mol times relative to the tetracarboxylic acid diester dichloride.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of the solubility of the monomer and polymer. One or two of these can be used. Use a mixture of more than one species. The concentration of the polymer during production is preferably 1 to 30% by mass, and 5 to 20% by mass, from the viewpoint of making it difficult to precipitate the polymer and easily obtain a high molecular weight body. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used when producing the polyamide ester is preferably one that is dehydrated as much as possible, and one that is used in a nitrogen environment to prevent the mixing of outside air. .

(3) Manufactured from tetracarboxylic acid diester and diamine Polyamic acid ester can be produced by polycondensation reaction of tetracarboxylic acid diester and diamine.

Specifically, the tetracarboxylic acid diester and the diamine are processed 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 a reaction of 3 to 15 hours can be obtained.

Examples of the aforementioned condensing agent include triphenyl phosphite, dicyclohexylcarbodiamide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N ,N'-carbonyldiimidazole, dimethoxy-1,3,5-tri Methylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea tetrachloroborate, O-(benzotriazol-1-yl )-N,N,N',N'-tetramethylurea hexafluorophosphate, (2,3-dihydro-2-sulfoxy-3-benzoxazolyl)phosphonic acid diphenyl wait. The amount of the condensation agent added is preferably 2 to 3 mol times relative to the tetracarboxylic acid diester. Among the aforementioned bases, tertiary amines such as pyridine and triethylamine can be used. The added amount of alkali is an amount that can be easily removed and from the viewpoint of easily obtaining a high molecular weight body, 2 to 4 mol times relative to the diamine component is preferred.

Furthermore, in the above reaction, when Lewis acid is added as an additive, the reaction can proceed efficiently. As the Lewis acid, for example, lithium halides such as lithium chloride and lithium bromide are preferred. The amount of Lewis acid added is preferably 0 to 1.0 mol times relative to the diamine component.

Among the above three methods for producing polyamic acid esters, the method of using the above-mentioned (1) or the above-mentioned (2) is particularly preferable from the viewpoint of producing a high molecular weight polyamic acid ester.

The polymer can be precipitated when a poor solvent is injected into the polyamide ester solution prepared by the above method with sufficient stirring. After several precipitations, washing with a poor solvent, and drying at room temperature or under heating, the purified polyamic acid ester powder can be obtained. The lean solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene, and the like.

＜Polyimide＞ The polyamide imide used in the present invention can be obtained by subjecting the aforementioned polyamide ester or polyamide acid to imidization treatment. It is based on the manufacturing method of polyimide described in the items of component (A-1) and component (A-2).

＜Photosensitive side chain acrylic polymer with liquid crystallinity within a specific temperature range＞ One aspect of component (B) is a photosensitive side chain acrylic polymer having liquid crystallinity within a specific temperature range.

The side chain acrylic polymer can react with light in the wavelength range of 250 nm to 400 nm and has liquid crystallinity in the temperature range of 100°C to 300°C.

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

The side chain acrylic polymer preferably has a mesogenic group that can exhibit liquid crystallinity in a temperature range of 100°C to 300°C.

The side-chain acrylic polymer has photosensitive side chains bonded to the main chain, so it can sense light to cause cross-linking reactions, isomerization reactions, or photo-Friesrearrangement reactions. The structure of the photosensitive side chain is not particularly limited. Generally, a structure that can sense light and cause a cross-linking reaction or a photo-Friesrearrangement reaction is preferred, and one that can cause a cross-linking reaction is preferred. For the better. In this case, even when exposed to external pressure such as heat, the achieved alignment control capability can be stabilized for a long period of time. The structure of the photosensitive side chain acrylic polymer film that can induce liquid crystallinity is not particularly limited as long as it satisfies this characteristic. Generally, those with rigid original liquid crystalline components in the side chain structure are preferred. . In this case, when the side chain acrylic polymer is used as a liquid crystal alignment film, stable liquid crystal alignment can be obtained.

The structure of the acrylic polymer, for example, has a main chain and a side chain bonded to the main chain. The side chain has a biphenyl, terphenyl, phenylcyclohexyl, phenyl benzoate group, phenylbenzoate group, The structure of original liquid crystal components such as nitrile phenyl groups and photosensitive groups bonded to the front part that can sense light and cause cross-linking reactions or isomerization reactions, or have a main chain and a side bonded to the main chain. Chain, the side chain is formed from the original liquid crystal component and has a structure of phenyl benzoate group that can undergo photo-Frys rearrangement reaction.

More specific examples of the structure of a photosensitive side chain acrylic polymer having liquid crystallinity in a specific temperature range include hydrocarbons, (meth)acrylate, itaconate, fumarate, and maleic acid esters. Composed of at least one selected from the group consisting of radically polymerizable radicals such as acid ester, α-methylmethylene-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, etc. The structure of the main chain and the side chain formed by at least one of the following formulas (31) to (35) is preferred.

In the formula, Ar ₁ represents a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, naphthalene ring, pyrrole ring, furan ring, thiophene ring, and pyridine ring. Ar ₂ and Ar ₃ each independently represent a benzene ring. , naphthalene ring, pyrrole ring, furan ring, thiophene ring, pyridine ring, a divalent substituent obtained by removing two hydrogen atoms, one of q ¹ and q ² is 1, the other is 0, Ar ₄ and Ar ₅ each independently represents a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, naphthalene ring, pyrrole ring, furan ring, thiophene ring, or pyridine ring, and Y ₁ -Y ₂ represents CH=CH, CH=N , N=CH or C≡C, S ₁ to S ₃ each independently represents a single bond, a linear or branched alkylene group with 1 to 18 carbon atoms, a cyclic alkylene group with 5 to 8 carbon atoms, and an alkylene group with 5 to 8 carbon atoms. Phenyl or biphenyl, or represents a single bond, ether bond, ester bond, amide bond, urea bond, urethane bond, amine bond, carbonyl or the One or two or more types of bonds selected from a combination of these, or bonded to a linear or branched alkylene group having 1 to 18 carbon atoms through one or more types of linkages. , a structure derived from a cycloalkylene group, a phenylene group, a biphenylene group with 5 to 8 carbon atoms, or a combination of 2 or more and 10 or less selected parts, or the aforementioned substituent is formed through the aforementioned bond. Any structure obtained by connecting a plurality of them is acceptable; R ³¹ represents a hydrogen atom, a hydroxyl group, a mercapto group, an amine group, an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, and the number of carbon atoms Alkylamino groups with 1 to 8 carbon atoms or dialkylamine groups with 2 to 16 carbon atoms, benzene rings and/or naphthalene rings can be composed of halogen atoms, cyano groups, nitro groups, carboxyl groups and alkoxy groups with 2 to 11 carbon atoms. The carbonyl group is substituted by one or more identical or different substituents selected from the group. In this case, the alkyl group having 1 to 10 carbon atoms may be linear, branched, cyclic, or any combination of these structures, and may also be substituted by a halogen atom.

Component (B) in this case is a photosensitive side chain acrylic polymer that has liquid crystallinity within a specific temperature range and may contain liquid crystalline side chains.

The original liquid crystalline group with liquid crystalline side chains can be composed of biphenyl or phenyl benzoate alone to form the base of the original liquid crystalline structure, or the original liquid crystalline structure can be composed of benzoic acid or other side chains that form hydrogen bonds with each other. Any base can be formed. The proto-liquid crystalline group having side chains preferably has the following structure.

＜＜How to prepare photosensitive side chain polymer＞＞ The above-mentioned photosensitive side chain acrylic polymer with liquid crystallinity within a specific temperature range can be produced by polymerizing the above-mentioned photoreactive side chain monomer with photosensitive side chain and liquid crystalline side chain monomer. .

[Photoreactive side chain monomer] The photoreactive side chain monomer, when forming a polymer, is a monomer that can form a polymer having a photosensitive side chain at the side chain portion of the polymer.

The photoreactive group having a side chain is preferably a structure represented by the above formulas (31) to (35).

More specific examples of the photoreactive side chain monomer include hydrocarbons, (meth)acrylate, itaconate, fumarate, maleate, α-methylmethylene-γ- A polymerizable group consisting of at least one selected from the group consisting of radical polymerizable groups such as butyrolactone, styrene, vinyl, maleimide, norbornene, and the above formula (31)~ The structure of the photosensitive side chain formed by at least one of (35) is preferred.

[Liquid crystalline side chain monomer] Liquid crystalline side chain monomer means that the polymer produced from the monomer has liquid crystallinity, and the polymer can form a proto-liquid crystalline group at the side chain site.

More specific examples of the liquid crystalline side chain monomer include hydrocarbons, (meth)acrylic acid esters, itaconic acid esters, fumaric acid esters, maleic acid esters, and α-methylmethylene-γ-butanol. A polymerizable group consisting of at least one selected from the group consisting of free radical polymerizable groups such as lactone, styrene, vinyl, maleimide, norbornene, and the aforementioned "having a liquid crystalline side chain" The structure of at least one side chain of "original liquid crystalline group" is preferred.

One aspect of the side chain acrylic polymer of component (B) can be produced by polymerizing the above-mentioned photoreactive side chain monomer that can produce liquid crystallinity. Alternatively, a photoreactive side chain monomer that does not generate liquid crystallinity and a liquid crystalline side chain monomer may be copolymerized, or a photoreactive side chain monomer that generates liquid crystallinity may be copolymerized with a liquid crystalline side chain monomer. Can be obtained by copolymerization. In addition, as long as the ability to generate liquid crystallinity is not impaired, it can also be copolymerized with other monomers.

Other monomers include, for example, monomers that are easily available in industry and can undergo free radical polymerization.

Specific examples of other monomers include unsaturated carboxylic acids, acrylate compounds, methyl acrylate compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds, and vinyl compounds.

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

Acrylate compounds, such as methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthracene acrylate, anthryl methacrylate, phenyl acrylate, 2,2,2-trifluoroacrylate Ethyl ester, tert-butyl acrylate, cyclohexyl acrylate, isocamphenyl acrylate, 2-methoxyethyl acrylate, triethylene glycol methoxyacrylate, 2-ethoxyethyl acrylate, tetrakis acrylate Hydrogen furfuryl ester, 3-methoxybutylacrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, and 8-ethyl-8-tricyclodecyl acrylate, etc.

Methyl acrylate compounds, for example, methyl methacrylate, methyl ethylacrylate, methyl isopropyl acrylate, benzyl methyl acrylate, naphthyl methacrylate, anthryl methacrylate, anthracenyl methyl methacrylate Ester, methyl phenylacrylate, methyl 2,2,2-trifluoroethyl acrylate, tert-butyl methyl acrylate, methyl cyclohexylacrylate, methyl isobornyl acrylate, 2-methoxyethyl Methyl acrylate, methoxytriethylene glycol methyl acrylate, 2-ethoxyethyl methyl acrylate, tetrahydrofurfuryl methyl acrylate, 3-methoxybutyl methyl acrylate, 2-methyl-2 -Methyl adamantyl acrylate, methyl 2-propyl-2-adamantyl acrylate, methyl 8-methyl-8-tricyclodecanyl acrylate, and, 8-ethyl-8-tricyclodecanyl Methyl acrylate, etc. Glycidyl (meth)acrylate, (3-methyl-3-oxetanyl) methyl (meth)acrylate, and (3-ethyl-3-oxetanyl) may also be used A (meth)acrylate compound having a cyclic ether group such as meth(meth)acrylate.

Vinyl compounds include, for example, vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether.

Styrene compounds, such as styrene, methylstyrene, chlorostyrene, bromostyrene, etc.

Maleimide compounds include, for example, maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and the like.

The method for producing the side chain polymer of this embodiment is not particularly limited, and methods widely used in general industrial processes can be used. Specifically, it can be produced by cationic polymerization, radical polymerization, or anionic polymerization of a vinyl group of a liquid crystalline side chain monomer or a photoreactive side chain monomer. Among these, radical polymerization is particularly preferable from the viewpoint of easy reaction control.

As a polymerization initiator for radical polymerization, for example, a well-known radical polymerization initiator such as AIBN (azobisisobutyronitrile) or a well-known radical polymerization reagent such as reversible addition-fragmentation chain transfer (RAFT) polymerization reagent can be used. compound.

The radical polymerization method is not particularly limited, and emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, block polymerization, solution polymerization, etc. can be used.

The organic solvent used in the polymerization reaction of the photosensitive side chain acrylic polymer having liquid crystallinity within a specific temperature range is not particularly limited, for example, as long as it can dissolve the produced polymer. Specific examples are as listed below.

N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylhexanolide Amide, dimethylsterine, tetramethylurea, pyridine, dimethylsterine, hexamethylsterine, γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethylene Methyl amyl ketone, methyl nonanone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve (cellosolve) acetate, ethyl Cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl 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 Ester 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-methoxy Butyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutyl ester, amyl acetate, butyl butyl Acid ester, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, Ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl acetate, methyl pyruvate, ethyl pyruvate, 3-methoxy Methyl propionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid Propyl ester, 3-methoxybutyl propionate, glycol diether (glyme), 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethyl Propanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, etc.

These organic solvents may be used individually or in mixture. In addition, even if it is a solvent that does not dissolve the produced polymer, it can be mixed with the above-mentioned organic solvent as long as the produced polymer is not precipitated.

In addition, in radical polymerization, oxygen in the organic solvent hinders the polymerization reaction, so it is preferable to use an organic solvent that is as degassed as possible.

The polymerization temperature during radical polymerization can be selected from any temperature between 30°C and 150°C, and is preferably within the range of 50°C to 100°C. In addition, although the reaction can be carried out at any concentration, if the concentration is too low, it will be difficult to obtain a high molecular weight polymer. If the concentration is too high, the viscosity of the reaction solution will be excessively increased, making it difficult to stir evenly. , so the monomer concentration is preferably 1 mass% to 50 mass%, more preferably 5 mass% to 30 mass%. The reaction may be carried out at a high concentration in the initial stage, and then an organic solvent may be added.

In the above-mentioned free radical polymerization reaction, if the ratio of the free radical polymerization initiator relative to the monomer is too much, the molecular weight of the resulting polymer will be reduced; if it is too small, the molecular weight of the resulting polymer will be increased, so free radical initiation The proportion of the agent is preferably 0.1 mol% to 10 mol% relative to the monomers to be polymerized. In addition, various monomer components, solvents, initiators, etc. can also be added during polymerization.

[Recycling of photosensitive side-chain acrylic polymers with liquid crystallinity within a specific temperature range] In the reaction solution that can produce liquid-crystalline photosensitive side-chain polymers obtained by the above reaction, in order to recover the generated polymers, the reaction solution can be put into a poor solvent to precipitate the polymers. . Poor solvents used for precipitation, such as methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, water etc. The polymer precipitated by adding a poor solvent can be dried under normal pressure or reduced pressure at normal temperature or under heating after being filtered and recovered. In addition, when the polymer recovered by precipitation is dissolved in an organic solvent and reprecipitated for recovery from 2 to 10 times, the impurities in the polymer can be reduced. Examples of lean solvents in this case include alcohols, ketones, hydrocarbons, etc. It is more preferable to use three or more types of lean solvents selected from these because the efficiency of purification can be further improved.

The molecular weight of the photosensitive side-chain acrylic polymer having liquid crystallinity in a specific temperature range in one aspect of component (B) of the present invention is determined by considering the strength of the resulting coating film, workability during coating film formation, and coating In terms of film uniformity, the weight average molecular weight measured by GPC (Gel Permeation Chromatography) method is preferably 2,000 to 1,000,000, more preferably 5,000 to 100,000.

The content of component (A) and component (B) in the liquid crystal alignment agent of the present invention, relative to the mass ratio of the total amount of component (A) and component (B) is 5:95 to 95:5, and 10: 90～90:10 is better.

When component (A) and component (B) in the liquid crystal alignment agent of the present invention are polyimide (precursor), the imidization rate of component (B) can be adjusted arbitrarily according to the use or purpose. From the viewpoint of solubility or charge accumulation characteristics, the imidization rate of the specific polymer (A) component is preferably 0 to 55%, more preferably 0 to 20%. In addition, from the viewpoint of liquid crystal alignment, alignment regulation force, and voltage retention, the higher the imidization rate of the specific polymer (B) is, the better, preferably 40% to 95%, and more preferably 55%. ~90%.

＜Liquid crystal alignment agent＞ The liquid crystal alignment agent used in the present invention is in the form of a solution in which polymer components are dissolved in organic solvents. As for the molecular weight of the polymer, the weight average molecular weight is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and particularly preferably 10,000 to 100,000. Moreover, the number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and particularly preferably 5,000 to 50,000.

The concentration of the polymer of the liquid crystal alignment agent used in the present invention can be appropriately changed according to the thickness setting of the coating film to be formed. From the perspective of forming a uniform and defect-free coating film, it is preferably 1 mass % or more. From the viewpoint of solution storage stability, 10% by mass or less is preferred. A particularly optimal polymer concentration is 2 to 8% by mass.

The organic solvent contained in the liquid crystal alignment agent used in the present invention is not particularly limited as long as it can uniformly dissolve the polymer components. Specific examples thereof include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidine. Ketone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyltrisoxide, dimethyltrisine, γ-butyrolactone, 1,3-dimethyl-imidazolinone, 3-methoxy-N,N-dimethylpropanamide, etc. These may be used 1 type or in mixture of 2 or more types. In addition, even if the solvent alone cannot dissolve the polymer component uniformly, it can be mixed with the above-mentioned organic solvent as long as the polymer is not precipitated.

In addition, the organic solvent contained in the liquid crystal alignment agent, in addition to the above-mentioned solvents, can generally be used as a mixed solvent combined with a solvent that can improve the coating properties or improve the smoothness of the coating film surface when coating the liquid crystal alignment agent. The present invention These mixed solvents are also suitable for use in liquid crystal alignment agents. Specific examples of organic solvents that can be used in combination include the following, but they are not limited to these examples.

For example, ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol Alcohol, isoamyl alcohol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-Ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1 -Methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 2,6-dimethyl-4-heptanol, 1,2-ethanediol, 1,2-propane Diol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5 -Pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether , Dioxane, Diethylene glycol dimethyl ether, Diethylene glycol diethyl ether, Diethylene glycol dibutyl ether, 1,2-butoxyethane, Diethylene glycol dimethyl ether, Diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-Heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutylacetate, 1-methylpentylacetic acid Esters, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2-(methoxy Methoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, diethylene glycol Alcohol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol mono Diethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate , Ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethyl Glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol acetate Monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methylethyl 3-ethoxypropionate, 3-methoxy Ethyl propionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid propyl ester, 3-methoxypropionic acid butyl ester, methyl lactate, ethyl lactate, lactic acid n-propyl ester, n-butyl lactate, isoamyl lactate, solvents represented by the following formulas [D-1] to [D-3], etc.

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

Among the preferred solvent combinations, for example, N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and Propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentane Ketone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidinone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2 -Pyrrolidinone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl -4-Heptanol, N-methyl-2-pyrrolidinone, γ-butyrolactone and dipropylene glycol dimethyl ether, etc. The type and content of these solvents can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

In addition, from the viewpoint of improving the mechanical strength of the film, the following additives may be added to the liquid crystal alignment agent of the present invention.

These additives are preferably 0.1 to 30 parts by mass relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent. If it is less than 0.1 parts by mass, the effect cannot be expected. If it exceeds 30 parts by mass, liquid crystal alignment will be reduced, so it is more preferably 0.5 to 20 parts by mass.

In the liquid crystal alignment agent of the present invention, in addition to the above, polymers other than polymers and dielectric materials for the purpose of changing the electrical properties such as dielectric coefficient or conductivity of the liquid crystal alignment film can be added within the scope that does not impair the effects of the present invention. body or conductive substance, silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate, cross-linking compounds for the purpose of improving the film hardness or density when used as a liquid crystal alignment film, or to improve the sintering of the coating film An imidization accelerator, etc., can be used to effectively carry out the imidization reaction of polyamide acid.

＜Liquid crystal alignment film＞ ＜Manufacturing method of liquid crystal alignment film＞ The liquid crystal alignment film of the present invention is a film obtained by coating the above-mentioned liquid crystal alignment agent on a substrate, drying, and sintering. The substrate on which the liquid crystal alignment agent of the present invention is coated is not particularly limited as long as it is a highly transparent substrate. Plastic substrates such as glass substrates, silicon nitride substrates, acrylic substrates, and polycarbonate substrates can be used. etc., from the viewpoint of simplification of production, it is preferable to use a substrate on which ITO electrodes for driving liquid crystal are formed. In addition, if the reflective liquid crystal display element only has a single-sided substrate, it can also use opaque materials such as silicon wafers. In this case, the electrodes can also use materials that can reflect light such as aluminum.

The coating method of the liquid crystal alignment agent of the present invention includes, for example, spin coating method, printing method, inkjet method, etc. Any temperature and time can be selected for the drying and sintering steps after coating the liquid crystal alignment agent of the present invention. Generally, to fully remove the organic solvent contained, drying can be performed between 50°C and 120°C for 1 to 10 minutes, and then sintering between 150°C and 300°C for 5 to 120 minutes. The thickness of the coating film after sintering is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be reduced, so it is usually 5 to 300 nm, preferably 10 to 200 nm.

Methods for performing alignment treatment on the obtained liquid crystal alignment film include, for example, rubbing method, photo-alignment treatment method, etc. The rubbing treatment can be performed using existing rubbing equipment. At this time, the material of the friction cloth is, for example, cotton, nylon, rayon, etc. Generally speaking, the conditions for friction treatment are to use a rotation speed of 300 to 2000 rpm, a conveying speed of 5 to 100 mm/s, and an extrusion amount of 0.1 to 1.0 mm. Subsequently, pure water, alcohol, etc. are used to remove the residue generated by friction caused by ultrasonic cleaning.

Specific examples of the photo-alignment treatment method include, for example, using radiation directed in a specific direction to irradiate the surface of the coating film, and then heating it at a temperature of 150 to 250°C to impart alignment ability to the liquid crystal, depending on the situation. As the radiation, for example, ultraviolet rays and visible rays having a wavelength of 100 nm to 800 nm can be used. Among them, ultraviolet rays having a wavelength of 100 nm to 400 nm are preferred, and those having a wavelength of 200 nm to 400 nm are particularly preferred. In addition, for the purpose of improving liquid crystal alignment, the coated substrate can be irradiated with radiation while heating at 50 to 250°C. The irradiation dose of the aforementioned 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 in the above manner can stably align liquid crystal molecules in a specific direction.

In addition, it is more preferable that the extinction ratio of polarized ultraviolet light is higher because it can impart higher anisotropy. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10:1 or more, and more preferably 20:1 or more.

The film irradiated with polarized radiation obtained in the above manner can then be contacted with a solvent containing at least one selected from water and organic solvents.

The solvent used in the contact treatment is not particularly limited as long as it can dissolve decomposition products generated by light irradiation, for example. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve Cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate, etc. . These solvents can also be used in combination of 2 or more types.

From the viewpoint of broad applicability or safety, it is preferable to use at least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate. Water, 2-propanol, and mixed solvents of water and 2-propanol are particularly preferred.

In the present invention, the contact treatment between a film irradiated with polarized radiation and a solution containing an organic solvent is performed using a treatment method such as infiltration treatment or spray treatment that can bring the film into better and sufficient contact with the liquid. Among them, it is preferable to perform an infiltration treatment on the membrane in a solution containing an organic solvent for preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes. The contact treatment can be carried out at normal temperature or at elevated temperature, preferably between 10 and 80°C, more preferably between 20 and 50°C. In addition, if necessary, methods such as ultrasound can be used to improve contact.

After the above contact treatment, in order to remove the organic solvent in the used solution, it can be washed (Rinse) or dried, or both, with low boiling point solvents such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, etc. Both can be done at the same time.

In addition, the above-mentioned film that is contacted with a solvent can also be heated to above 150°C for the purpose of drying the solvent and realigning the molecular chains in the film.

The heating temperature is preferably, for example, 150 to 300°C. Although the higher the temperature can promote the realignment of molecular chains, if the temperature is too high, there will be concerns about the decomposition of the molecular chains. Therefore, the heating temperature is, for example, preferably 180 to 250°C, and particularly preferably 200 to 230°C.

If the heating time is too short, the effect of realignment of the molecular chains may not be obtained. If the heating time is too long, the molecular chains may be decomposed. Therefore, 10 seconds to 30 minutes is preferred, and 1 minute to 10 minutes is preferred. minutes is better.

In addition, the obtained liquid crystal alignment film can be easily dissolved in the reprocessing material, and is a film with excellent reproducibility.

Solvents used during re-production include the following solvents: glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether. Ethers; glycol esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, etc.; diethyl Diols such as glycol, propylene glycol, butanediol, hexanediol, etc.; Alcohols such as methanol, ethanol, 2-propanol, butanol, etc.; Acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2 - Ketones such as heptanone and γ-butyrolactone; methyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethoxyethyl acetate, ethyl glycolate, 2-hydroxy -Methyl 3-methylbutanoate, methyl 3-methoxypropionate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate , esters such as methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, N,N-dimethylformamide, N,N-dimethylethyl Amides such as amide and N-methyl-2-pyrrolidone.

For example, the recycled material preferably contains an alkaline component such as ethanolamine in the above-mentioned solvent and an anti-rust agent that does not cause the alkalinity to damage other components such as electrodes. Manufacturers that can provide these remanufactured materials include, for example, South Korea's Huimyung Industrial Co., Ltd., KPX Chemical, etc.

Reproduction means heating the above-mentioned reconstituted materials at room temperature or between 30°C and 100°C, and then immersing the substrate with the liquid crystal alignment film in it for 1 second to 1000 seconds, preferably 30 seconds. ~500 seconds, or use a spray method to spray the reconstituted material, and then wash the liquid with an alcohol solvent or pure water. In addition, the temperature of the reconstituted liquid during reprocessing is preferably low from the viewpoint of operating efficiency, etc., and is usually room temperature to 60°C, and more preferably room temperature to 40°C.

＜Liquid crystal display element＞ The liquid crystal display element of the present invention uses the liquid crystal alignment agent of the present invention and prepares a substrate with a liquid crystal alignment film according to the aforementioned manufacturing method of the liquid crystal alignment film, and then uses a known method to prepare a liquid crystal unit and uses it as a liquid crystal display element. By.

An example of a method for manufacturing a liquid crystal unit will be explained by taking a liquid crystal display element with a passive element matrix structure as an example. In addition, it may also be a liquid crystal display element having an active matrix structure in which switching elements such as TFT (Thin Film Transistor) are provided in each pixel portion constituting the image display.

First, a transparent glass substrate is prepared, a common electrode is provided on one side of the substrate, and a segment electrode is provided on the other side of the substrate. These electrodes can be used as ITO electrodes, for example, or can form patterns for desired image display. Secondly, an insulating film covering the common electrode and the segment electrode can be provided on each substrate. The insulating film is, for example, a film formed of SiO ₂ -TiO ₂ obtained by a sol-gel method.

Secondly, the liquid crystal alignment film of the present invention is formed on each substrate according to the above method.

Secondly, the substrate on one side and the substrate on the other side are overlapped so that the alignment film surfaces face each other, and a sealant is used around them to connect them. In the sealant, spacers are usually mixed in for the purpose of controlling the gap between the substrate and the like. In addition, it is also preferable to spread spacers to control the gap between the substrates in the inner part where the sealant is not provided. A part of the sealant is provided with openings that can be filled with liquid crystal from the outside.

Next, the liquid crystal material is injected into the space surrounded by the two substrates and the sealant through the opening provided in the sealant. Then, the opening is sealed using an adhesive. As the injection method, a vacuum injection method or a method utilizing capillary phenomena in the atmosphere can be used. Then, set up the polarizer. Specifically, a pair of polarizing plates is attached to the surface opposite to the liquid crystal layer of two substrates. Through the above steps, the liquid crystal display element of the present invention is produced.

In the present invention, a resin that is cured by ultraviolet irradiation or heating and has a reactive group such as an epoxy group, an acrylic group, a methacrylic group, a hydroxyl group, an allyl group, or an acetyl group can be used as the sealing agent. In particular, it is preferable to use a cured resin system having reactive groups of both epoxy groups and (meth)acrylyl groups.

In the sealant of the present invention, an inorganic filler may be added for the purpose of improving adhesion, moisture resistance, etc. The inorganic filler that can be used is not particularly limited. Specific examples include spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, nitride Silicon, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, Zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, etc., preferably spherical silicon dioxide, fused silicon dioxide, crystalline silicon dioxide, titanium oxide, titanium black, silicon nitride, nitrogen Boron, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, aluminum hydroxide, calcium silicate, aluminum silicate. The above-mentioned inorganic filler can be used in mixture of 2 or more types.

In this liquid crystal display element, since the liquid crystal alignment film is a liquid crystal alignment film obtained by using the manufacturing method of the liquid crystal alignment film of the present invention, it has excellent reproducibility and is suitable for use in large-screen and high-definition LCD televisions.

[Example]

In the following detailed description of the manufacturing method of the present invention, experimental methods for studying raw material compositions or addition ratios, results thereof, and examples of typical manufacturing methods will be described. In addition, the present invention is not limited to these Examples. Description of abbreviations used in this embodiment (organic solvent) NMP: N-methyl-2-pyrrolidinone GBL: gamma-butyrolactone BCS: butyl cellosolve Acid dianhydride (A): following formula (A) Acid dianhydride (B): following formula (B) Acid dianhydride (C): following formula (C) Acid dianhydride (D): following formula (D) Acid dianhydride (E): 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)

The following describes the measurement of viscosity, measurement of acyl imidization rate, evaluation of reproducibility, production of liquid crystal cells (cells), and methods of evaluating charge relaxation characteristics, etc.

[Measurement of viscosity] In the synthesis example, the viscosity of the polyamic acid ester and polyamic acid solution was measured using an E-type viscometer TV-25H (manufactured by Toki Industrial Co., Ltd.) at a temperature of 25°C with a sample volume of 1.1 mL and CORD-1 (1°34', R24).

[Measurement of acyl imidization rate] Add 20 mg of polyimide powder to an NMR sample tube (NMR standard sample tube ϕ5 manufactured by Kusano Scientific Co., Ltd.), and add 0.53% of deuterated dimethylsulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) ml, apply ultrasound to dissolve completely. This solution was measured for proton NMR at 500 MHz using an NMR meter (JNW-ECA500) manufactured by Japan Electronics Data Corporation. The imidization rate is measured by using protons derived from structures that have not changed before and after imidization as the reference proton method, and the integrated peak value of this proton is compared with the peak value of amide acid that appears around 9.5 to 10.0 ppm. The integrated value of the proton wave peak derived from the NH group is calculated according to the following formula.

Imination rate (%) = (1-α・x/y)×100 In the above formula, x is the accumulated value of the proton peak generated by the NH group of amide, y is the accumulated peak value of the reference proton, and α is relative to the state of polyamic acid (imidization rate of 0%). One NH proton of acyl acid is the ratio of the number of base protons.

[Evaluation of Reproducibility] The liquid crystal alignment agent of the present invention is coated on the Cr substrate using a spin coater. After drying on a hot plate at 60°C for 1 minute and 30 seconds, a sintering process was performed in a hot air circulation oven at 230°C for 20 minutes to form a coating film with a thickness of 100 nm. Subsequently, the prepared substrate was immersed in the reconstituted material heated to 55° C., developed for 300 seconds, and then washed with running water for 20 seconds using ultrapure water. Subsequently, the air jet treatment was performed, and the liquid crystal alignment film completely disappeared was marked as ○, and the liquid crystal alignment film still remained was marked as ×. The results obtained are recorded in Table 3.

[Production of liquid crystal unit] A liquid crystal cell having the composition of a wide viewing angle switching (Fringe Field Switching: also referred to as FFS) mode liquid crystal display element is produced.

First prepare the substrate with electrodes attached. The substrate is a glass substrate with a size of 30mm×50mm and a thickness of 0.7mm. An ITO electrode having a sticky pattern as the first layer constituting the counter electrode is formed on the substrate. The second layer on the counter electrode of the first layer is a SiN (silicon nitride) film formed by a CVD method. The SiN film of the second layer has a thickness of 500 nm and functions as an interlayer insulating film. On the SiN film of the second layer, a comb-shaped pixel electrode formed by patterning an ITO film as a third layer is arranged, and two pixels, namely the first pixel and the second pixel, are formed. of pixels. The size of each pixel is 10mm vertically and approximately 5mm horizontally. At this time, the counter electrode of the first layer and the pixel electrode of the third layer form electrical insulation through the SiN film of the second layer.

The pixel electrode of the third layer has a zigzag-like shape composed of a plurality of electrode elements arranged in a curved "U" shape at the center. The width of each electrode element in the short side direction is 3 μm, and the distance between electrode elements is 6 μm. The pixel electrode that forms each pixel is composed of a plurality of electrode elements arranged in a curved "U" shape at the center. Therefore, the shape of each pixel is not a rectangular shape, but is the same as the electrode element. The central part has a curved shape that approximates a bold "ㄑ" character. Therefore, each pixel is divided into upper and lower parts via the central bending part as a boundary, and has a first area located above the bending part and a second area located below the bending part.

When comparing the first region and the second region of each pixel, the difference is that the electrode elements constituting the pixel electrode of the pixel have different formation directions. That is, when the rubbing direction of the liquid crystal alignment film described below is used as a reference, the first area of the pixel is formed such that the electrode element of the pixel electrode is at an angle of +10° (clockwise direction), and the second area of the pixel is The electrode elements of the pixel electrodes are formed at an angle of -10° (clockwise direction). That is, the first region and the second region of each pixel have a rotational movement (in-plane opening and closing) of the liquid crystal in the substrate surface caused by the applied voltage between the pixel electrode and the counter electrode. The composition of the opposite direction.

Next, the obtained liquid crystal alignment agent was filtered with a 1.0 μm filter, and then coated using a spin coater on the prepared above-mentioned substrate with electrodes and a glass substrate with a 4 μm high columnar spacer with an ITO film formed on the inner surface. superior. After drying on a hot plate at 80°C for 5 minutes, a sintering process was performed in a hot air circulation oven at 230°C for 20 minutes to form a coating film with a thickness of 100 nm. The coating surface is subjected to alignment treatment such as rubbing or polarized ultraviolet irradiation to obtain a substrate with a liquid crystal alignment film. The above two substrates are used as a set, and a sealant is printed on the substrate. The other substrate is bonded so as to face the liquid crystal alignment film surface to form an alignment direction of 0°, and then the sealant is hardened to prepare an empty unit. Liquid crystal MLC-2041 (manufactured by Mock Co., Ltd.) was injected into the empty cell using a reduced pressure injection method, and the injection port was sealed to prepare an FFS driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110° C. for 1 hour and left overnight before being used for each evaluation.

[Evaluation of charge relaxation characteristics] Place the above-mentioned liquid crystal cell on a light source, measure the V-T characteristics (voltage-transmittance characteristics) at room temperature, and then measure the transmittance (Ta) of the liquid crystal cell when a ±1.5V/60Hz rectangular wave is applied. . Subsequently, the transmittance (Tb) of the liquid crystal unit was measured during driving for 30 minutes under an overlapping DC voltage of 1V. After the DC voltage was cut off, the liquid crystal cell was measured again using only a square wave of ±1.5V/60Hz and driven for 20 minutes. The transmittance (Tc) of the cell is calculated from the difference (ΔT) between the transmittance at each time (Tb, Tc) and the initial transmittance (Ta). The difference in transmittance. The earlier the residual voltage is relaxed, the less likely the burn-in phenomenon will occur. (Tb-Ta) If the voltage drops below 2% 5 minutes after DC voltage is applied, it will be marked as ○. If it exceeds 2%, it will be marked as ×. (Tc-Ta) If the DC voltage drops below 2% 5 minutes after the DC voltage is cut off, it will mark Those marked as ○ and above are marked as ×. The results obtained are recorded in Table 3.

(Comparative polymerization example 1) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.96g of (DA-3), add 25.7g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring the diamine solution, add 3.00g of acid dianhydride (C), and then add 11.2g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 0.77g of acid dianhydride (D), and then add NMP. 4.4g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, the mixture was stirred at 50° C. for 16 hours to obtain a polyamide solution (PAA-1). The viscosity of the polyamide solution at a temperature of 25°C is 358 cps.

(Comparative polymerization example 2) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.46g of (DA-2), add 22.3g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring the diamine solution, add 2.00g of acid dianhydride (C), and then add 6.3g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 1.51g of acid dianhydride (D), and then add NMP. 8.5g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, the mixture was stirred at 50° C. for 16 hours to obtain a polyamide solution (PAA-2). The viscosity of the polyamide solution at a temperature of 25°C is 333 cps.

(Polymerization example 1) Place a 100mL four-necked flask with a stirring device in a nitrogen atmosphere, and weigh (DA-6) 0.58g, (DA-4) 1.32g, (DA-5) 0.93g, and (DA-7) 3.01g , add 42.8g of NMP, feed nitrogen at 23°C, and stir to dissolve. While stirring the diamine solution, add 3.91g of acid dianhydride (E), further add 12.4g of NMP, and stir for 16 hours under a nitrogen atmosphere at 40°C to obtain a polyamic acid solution (PAA-3). The viscosity of the polyamide solution at a temperature of 25°C is 450 cps.

(Polymerization example 2) Place a 100mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 6.19g of (DA-9) and 2.14g of (DA-8), add 61.1g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring the diamine solution, add 5.71g of acid dianhydride (B), then add 18.5g of NMP, and stir for 16 hours under a nitrogen atmosphere at 50°C to obtain a polyamide solution (PAA-4). The viscosity of the polyamide solution at a temperature of 25°C is 351 cps.

(Polymerization example 3) Place a 1L four-necked flask with a stirring device in a nitrogen atmosphere, weigh 86.0g of (DA-4), 53.4g of (DA-7), and 76.5g of (DA-10). Add 1580g of NMP and mix at 23 ℃, nitrogen gas is sent into the medium, and stirred to dissolve. While stirring the diamine solution, 93.2g of acid dianhydride (E) was added, and then 168g of NMP was added, and the mixture was stirred for 3 hours in a nitrogen atmosphere at 40°C. Then add 28.2g of acid dianhydride (D), then add 160g of NMP, and stir for 4 hours in a nitrogen atmosphere at 23°C to obtain a polyamic acid solution (PAA-5). The viscosity of the polyamide solution at a temperature of 25°C is 200 mPa·s.

(Polymerization example 4) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.78g of (DA-4), add 24.4g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring, add 1.75g of acid dianhydride (B) to the diamine solution, and then add 4.3g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 1.41g of acid dianhydride (D), and then add NMP. 8.0g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, the mixture was stirred at 50° C. for 16 hours to obtain a polyamide solution (PAA-6). The viscosity of the polyamide solution at a temperature of 25°C is 240 cps.

(Polymerization Example 5) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.49g of (DA-2), add 22.3g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring, add 2.35g of acid dianhydride (A) to the diamine solution, and then add 8.3g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 1.80g of acid dianhydride (C), and then add NMP. 10.2g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, the mixture was stirred at 70° C. for 16 hours to obtain a polyamide solution (PAA-7). The viscosity of the polyamide solution at a temperature of 25°C is 380 cps.

(Polymerization Example 6) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.49g of (DA-2), add 22.3g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring, add 2.35g of acid dianhydride (A) to the diamine solution, and then add 8.3g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 1.41g of acid dianhydride (D), and then add NMP. 8.0g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, the mixture was stirred at 70° C. for 16 hours to obtain a polyamide solution (PAA-8). The viscosity of the polyamide solution at a temperature of 25°C is 321 cps.

(Polymerization Example 7) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.49g of (DA-2), add 22.3g of NMP, add nitrogen at 23°C, and stir. Let it dissolve. While stirring the diamine solution, add 1.41g of acid dianhydride (A), and then add 2.9g of NMP. After stirring for 2 hours at 23°C in a nitrogen atmosphere, add 1.41g of acid dianhydride (B), and then add NMP. 7.9g, stir for 2 hours at 23°C under nitrogen atmosphere. Subsequently, 1.00 g of acid dianhydride (C) was added, and then 5.7 g of NMP was added, and the mixture was stirred for 2 hours at 23° C. in a nitrogen atmosphere. Subsequently, the mixture was stirred at 70° C. for 16 hours to obtain a polyamide solution (PAA-9). The viscosity of the polyamide solution at a temperature of 25°C is 365 cps.

(Comparative example 1) In a 50 mL Erlenmeyer flask with a stirrer placed, filter out 6.73 g of the polyamic acid solution (PAA-3), 15.27 g of (PAA-1), and 1 wt% of (AD-1) obtained in the comparative synthesis example. Add 2.40g of NMP solution and 0.72g of NMP solution containing 10wt% of (AD-2). Add 2.88g of NMP and 12.00g of BCS and stir for 2 hours using a magnetic stirrer to obtain liquid crystal alignment agent (A-1).

(Comparative example 2) In a 50 mL Erlenmeyer flask with a stirrer placed, filter out 4.00 g of the polyamide solution (PAA-4), 12.80 g of (PAA-2), and an NMP solution containing 1 wt% of (AD-1) obtained in the comparative synthesis example. 2.40g, add NMP 8.80g and BCS 12.00g, stir for 2 hours using a magnetic stirrer, and obtain liquid crystal alignment agent (A-2).

(Comparative example 3) In a 3L Erlenmeyer flask equipped with a stirrer, filter 800g of the polyamic acid solution (PAA-5) obtained in (Polymerization Example 3), add 700g of NMP, 69.7g of acetic anhydride, and 18.0g of pyridine, and stir at room temperature. After 30 minutes, the reaction was carried out at 55°C for 3 hours. The reaction solution was added to 5600 g of methanol, and the resulting precipitate was filtered out. After washing the precipitate with methanol, it was dried under reduced pressure at a temperature of 60° C. to obtain polyimide powder. The polyimide powder had an imidization rate of 75%. In a 300mL Erlenmeyer flask equipped with a stirrer, filter 20.4g of the polyimide powder, add 150g of NMP, and stir at 50°C for 20 hours to dissolve to obtain a polyimide solution (SPI-1). In a 50mL Erlenmeyer flask with a stirrer placed, filter out 7.00g of the polyimide solution (SPI-1), 10.40g of (PAA-6), and 2.40g of NMP solution containing 1wt% of (AD-1) obtained above. , 0.72g of NMP solution containing (AD-2) 10wt%, add 7.48g of NMP and 12.00g of BCS, and stir for 2 hours using a magnetic stirrer to obtain liquid crystal alignment agent (A-3).

(Examples 1 to 3) In a 50 mL Erlenmeyer flask with a stirrer placed, filter out 7.00 g of the polyimide solution (SPI-1) obtained in (Comparative Example 3) and the polyimide solution (PAA-1) obtained in (Polymerization Examples 5 to 7). 7～9) 10.40g, filter out 2.40g of NMP solution containing (AD-1) 1wt% and 0.72g of NMP solution containing (AD-2) 10wt%, add 7.48g of NMP and 12.00g of BCS, and use a magnetic stirrer. Stir for 2 hours to obtain the liquid crystal alignment agent (B-1~3) shown in Table 1.

(Examples 4 to 6) In a 50 mL Erlenmeyer flask with a stirrer placed, filter out 4.00 g of the polyamic acid solution (PAA-4) obtained in (Polymerization Example 2) and the polyamic acid solution (PAA-4) obtained in (Polymerization Examples 5 to 7). 7～9) 12.80g, 2.40g of NMP solution containing (AD-1) 1wt%, add 4.80g of NMP and 12.00g of BCS, stir for 2 hours using a magnetic stirrer, and obtain the liquid crystal alignment agent (B- 4～6).

(Example 7) In a 50 mL Erlenmeyer flask with a stirrer placed, filter out 6.00 g of the polyamide solution (PAA-7), 11.20 g of (PAA-1), and an NMP solution containing 1 wt% of (AD-1) obtained in the comparative synthesis example. 2.40g, 0.72g of NMP solution containing (AD-2) 10wt%, add 7.68g of NMP and 12.00g of BCS, and stir for 2 hours using a magnetic stirrer to obtain liquid crystal alignment agent (B-7).

[Industrial applicability]

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can reduce the charge accumulation caused by the asymmetry of AC drive in the IPS drive mode or FFS drive mode liquid crystal display element, and can quickly alleviate the charge caused by the DC voltage. By using the accumulated residual charge, an IPS-driven or FFS-driven liquid crystal display element with excellent afterimage characteristics can be produced. Therefore, it is particularly suitable as a liquid crystal display element of an IPS drive system or an FFS drive system or a liquid crystal alignment film of an LCD television.

Claims (5)

A liquid crystal alignment agent, characterized by containing: (A) 3,3',4,4'-biphenyltetracarboxylic dianhydride and aliphatic tetracarboxylic acid dianhydride in a ratio of 10:90 to 90:10 At least one selected from a polyamic acid obtained by reacting a tetracarboxylic dianhydride component of an anhydride with a diamine component containing a diamine represented by the following formula (2) and an imidized polymer of the polyamic acid 1 type of polymer, (B) consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side chain having liquid crystallinity in a temperature range of 100°C to 300°C At least one polymer selected from the group consisting of type acrylic polymers, and an organic solvent;

(In the formula (2), Y ₁ is at least one type selected from the group of divalent organic groups having the structures of the following formulas (YD-14) and (YD-18), and B ₁ and B ₂ Each independently represents a hydrogen atom, or an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms which may have a substituent)

(In formula (YD-14), j is an integer from 1 to 3) and 10 to 100 mol% of the tetracarboxylic dianhydride component of component (A) is 3,3',4,4'- Biphenyl tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride. The liquid crystal alignment agent of claim 1, wherein 10 to 100 mol% of the diamine component of component (A) is the diamine of formula (2). Such as the liquid crystal alignment agent of claim 1, wherein the aforesaid aliphatic tetracarboxylic dianhydride is bicyclo[3.3.0]octane 2,4,6,8-tetracarboxylic acid 2,4:6,8 dianhydride. A liquid crystal alignment film, characterized in that it is obtained by coating and sintering the liquid crystal alignment agent in any one of claims 1 to 3. A liquid crystal display element, characterized by having the liquid crystal alignment film of claim 4.