TWI869641B - 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-1) a polyamide obtained by using a tetracarboxylic dianhydride component containing a tetracarboxylic dianhydride represented by the following formula (1) and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from an imidized polymer of the polyamide; (A-2) a polyamide obtained by using a tetracarboxylic dianhydride component containing an aliphatic tetracarboxylic dianhydride and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from an imidized polymer of the polyamide; (B) at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side-chain acrylic polymer having liquid crystallinity within a specific temperature range, and organic solvents.

Description

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

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

Liquid crystal devices have been widely used in display areas of personal computers, portable phones, video receivers, and the like. Liquid crystal devices, for example, have a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and a thin film transistor (TFT) for switching on and off the supply of an electric signal to the pixel electrode. The known driving methods of liquid crystal molecules include longitudinal electric field methods such as the TN method and the VA method, and transverse electric field methods such as the IPS method and the wide viewing angle switch (hereinafter, FFS) method (for example, Patent Document 1).

On the other hand, in recent years, since the economic efficiency of the production process of liquid crystal display elements or organic EL elements has become an extremely important factor, the recycling of element substrates has also begun to be sought. That is, after the liquid crystal alignment film is formed by the liquid crystal alignment agent, when a defect is found during the inspection of the alignment, the liquid crystal alignment film can be easily removed from the substrate and the substrate can be recycled for reuse. However, the liquid crystal alignment film produced by the liquid crystal alignment agents proposed in the past is mostly made insoluble in organic solvents after post-baking in order to reduce film loss. Furthermore, the composition of the reproducible liquid crystal alignment agents studied so far is difficult to achieve the desired purpose even when used as the composition of the liquid crystal alignment agents for the lateral electric field. Therefore, it is necessary to re-evaluate whether the liquid crystal alignment agents have excellent reproducibility and to further study whether the composition of the optimal composition can be achieved.

Furthermore, liquid crystal display elements have been widely used in display devices. The liquid crystal alignment film, which is a component of the liquid crystal display element, is a film that allows the liquid crystal to form a uniform arrangement. Therefore, it not only requires uniformity of liquid crystal alignment, but also must have various other properties. For example, in the production process of the liquid crystal alignment film, it is generally necessary to use a cloth to wipe and rub the surface of the polymer film for alignment treatment. However, if the friction resistance of the liquid crystal alignment film is insufficient, the film may be damaged or dust may occur, and the film itself may peel off, resulting in a decrease in the display quality of the liquid crystal display element. Furthermore, the liquid crystal display element is a liquid crystal driven by applying a voltage. Therefore, if the voltage holding ratio (VHR) of the liquid crystal alignment film is too low, sufficient voltage cannot be applied, which will cause degradation of the display contrast. In addition, due to the influence of the voltage driving the liquid crystal, charges are accumulated in the liquid crystal alignment film. If the time to eliminate the accumulated charges is too long, afterimages or display afterimages may occur.

There are various proposals for properties that can simultaneously meet the above requirements. For example, Patent Document 2 and others have proposed a method for manufacturing a liquid crystal alignment film with excellent friction resistance and less residual images or afterimages. In addition, Patent Document 3 and others have also proposed a method for manufacturing a liquid crystal alignment film with excellent liquid crystal alignment, alignment regulation, friction resistance, high voltage retention, and reduced charge accumulation. [Prior Technical Documents] [Patent Documents]

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

[The problem the invention is trying to solve]

The present invention provides a liquid crystal alignment agent that can produce a liquid crystal alignment film that satisfies various properties required of the liquid crystal alignment film and has excellent reproducibility. [Solution]

The inventors of the present invention have conducted in-depth research to solve the above-mentioned problems and have found that when polyamides and imide polymers of polyamides are obtained from tetracarboxylic acids containing specific aromatic tetracarboxylic dianhydrides and aliphatic tetracarboxylic dianhydrides and diamines having specific structures, a liquid crystal alignment film can be produced while satisfying various properties required of a liquid crystal alignment film and also having excellent reproducibility, thereby completing the present invention.

That is, the present invention is proposed based on the above results, and has the following main contents. 1. A liquid crystal alignment agent, characterized by containing: (A-1) a polyamine obtained by using a tetracarboxylic dianhydride component containing a tetracarboxylic dianhydride represented by the following formula (1) and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from the imide polymer of the polyamine, (A-2) a polyamine obtained by using a tetracarboxylic dianhydride component containing an aliphatic tetracarboxylic dianhydride and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from the imide polymer of the polyamine, (B) at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side-chain acrylic polymer having liquid crystal properties within a specific temperature range, and an organic solvent.

(In formula (1), i is 0 or 1, X is a single bond, an ether bond, a carbonyl group, an ester bond, a phenylene group, a linear alkylene group having 1 to 20 carbon atoms, a branched alkylene group having 2 to 20 carbon atoms, 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 may be interrupted by a bond selected from an ester bond and an ether bond, and the carbon atoms of the phenylene group and the alkylene group may be substituted by one or more identical or different substituents selected from a halogen atom, a cyano group, an alkyl group, a halogenalkyl group, an alkoxy group, and a halogenalkoxy group. In formula (2), Y ₁ is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocyclic ring; B ₁ and B ₂ each independently represent a hydrogen atom, or an alkyl group, alkenyl group, or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

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

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

4. The liquid crystal alignment agent as described in any one of 1 to 3, wherein 10 to 100 mol % of the diamine components of the aforementioned (A-1) and the aforementioned (A-2) are diamines of formula (2).

5. The liquid crystal alignment agent according to any one of 1 to 4, wherein _Y1 in formula (2) is at least one selected from the structures of the following formulas (YD-1) to (YD-5).

(In formula (YD-1), _A1 is a heterocyclic ring containing nitrogen atoms and having 3 to 15 carbon atoms, _Z1 is a hydrogen atom, or a alkyl group having 1 to 20 carbon atoms which may have a substituent; in formula (YD-2), _W1 is a alkyl group having 1 to 10 carbon atoms, _A2 is a monovalent organic group having 3 to 15 carbon atoms and a heterocyclic ring containing nitrogen atoms, or a disubstituted amino group substituted by an aliphatic group having 1 to 6 carbon atoms; in formula (YD-3), _W2 is a divalent organic group having 6 to 15 carbon atoms and 1 to 2 benzene rings, _W3 is an alkylene group or a biphenylene group having 2 to 5 carbon atoms, _Z2 is a hydrogen atom, an alkylene group having 1 to 5 carbon atoms, or a benzene ring, and a is an integer from 0 to 1; in formula (YD-4), A _A4 is a heterocyclic ring having 3 to 15 carbon atoms and containing nitrogen atoms; in formula (YD-5), _A4 is a heterocyclic ring having 3 to 15 carbon atoms and containing nitrogen atoms, and _W5 is an alkylene group having 2 to 5 carbon atoms).

6. The liquid crystal alignment agent described in 5, wherein _A1 , _A2 , _A3 , and A4 described in formula (YD-1), (YD-2), (YD-4), and (YD- ₅ ) are pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyridine, At least one selected from the group consisting of indole, benzoimidazole, quinoline and isoquinoline.

7. The liquid crystal alignment agent as described in any one of 1 to 6, wherein _Y1 in formula (2) is at least one selected from the group consisting of divalent organic groups having structures of the following formulas (YD-6) to (YD-21).

(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).

8. The liquid crystal alignment agent as described in 7, wherein _Y1 in formula (2) is at least one selected from the group consisting of divalent organic groups having the structures of the above formulas (YD-14) and (YD-18).

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

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

11. 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 10.

12. A liquid crystal display element, characterized by having a liquid crystal alignment film as described in 11. [Effect of the invention]

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

The liquid crystal alignment agent of the present invention comprises: (A-1) a polyamide obtained by using a tetracarboxylic dianhydride component containing a tetracarboxylic dianhydride represented by the following formula (1) and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from the imidized polymer of the polyamide, (A-2) a polyamide obtained by using a tetracarboxylic dianhydride component containing an aliphatic tetracarboxylic dianhydride and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from the imidized polymer of the polyamide, (B) at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side-chain acrylic polymer having liquid crystal properties within a specific temperature range, and organic solvents.

In formula (1), i is 0 or 1, and X is a single bond, an ether bond, a carbonyl group, an ester bond, a phenylene group, a linear alkylene group having 1 to 20 carbon atoms, a branched alkylene group having 2 to 20 carbon atoms, 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 may be interrupted by a bond selected from an ester bond and an ether bond, and the carbon atoms of the phenylene group and the alkylene group may be substituted by one or more identical or different substituents selected from the group consisting of a halogen atom, a cyano group, an alkyl group, a halogenalkyl group, an alkoxy group, and a halogenalkoxy group.

In formula (2), _Y1 is a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocyclic ring, and _B1 to _B2 each independently represent a hydrogen atom, or an alkyl group, alkenyl group, or alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Each component is described in detail below.

<Component (A-1) and component (A-2)> The component (A-1) used in the liquid crystal alignment agent of the present invention is a polyamide obtained by a tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the above formula (1) and a diamine component containing the diamine represented by the above formula (2), and at least one polymer selected from an imidized polymer of the polyamide.

Furthermore, the component (A-2) used in the liquid crystal alignment agent of the present invention is a polyamide obtained by a tetracarboxylic dianhydride component containing aliphatic tetracarboxylic dianhydride and a diamine component containing a diamine represented by the above formula (2), and at least one polymer selected from an imide polymer of the polyamide.

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

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

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

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

In the formula, _X1 can be any one of the following (X-1) to (X-28).

In 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 from the viewpoint of not containing an aromatic moiety, and (X-10) is particularly preferred from the viewpoint of being less susceptible to thermal imidization.

In the component (A-1), if the amount of the tetracarboxylic dianhydride represented by formula (1) is too small in the total amount of the tetracarboxylic dianhydride component, the effect of the present invention cannot be obtained. Therefore, the amount of the tetracarboxylic dianhydride represented by formula (1) is preferably 10 to 100 mol%, more preferably 50 to 100 mol%, and particularly preferably 80 to 100 mol%, relative to 1 mol of the total tetracarboxylic dianhydride used in the preparation of the component (A-1).

In the component (A-2), if the amount of aliphatic acid dianhydride in the total amount of tetracarboxylic acid dianhydride components is too small, the effect of the present invention cannot be obtained. Therefore, the amount of aliphatic tetracarboxylic acid dianhydride is preferably 10 to 100 mol%, more preferably 50 to 100 mol%, and particularly preferably 80 to 100 mol%, relative to 1 mol of the total tetracarboxylic acid dianhydride used in the preparation of the component (A-2).

The tetracarboxylic dianhydride represented by formula (1) and the aliphatic tetracarboxylic dianhydride may be used alone or in combination. In this case, the total amount of the tetracarboxylic dianhydride represented by formula (1) and the aliphatic tetracarboxylic dianhydride is preferably the preferred amount described above.

The polyamide contained in the liquid crystal alignment agent of the present invention may use tetracarboxylic dianhydride represented by the following formula (4) in addition to tetracarboxylic dianhydride represented by the formula (1) and aliphatic tetracarboxylic dianhydride.

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

<Diamine component> The diamine component used in the preparation of the component (A-1) or the component (A-2) of the present invention is a diamine having the above-mentioned formula (2). In formula (2), _Y1 is a divalent organic group having a structure of at least one selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocyclic ring, and _B1 to _B2 each independently represent a hydrogen atom, or an alkyl group, an alkenyl group, or an alkynyl group having 1 to 10 carbon atoms which may have a substituent.

Specific examples of the above-mentioned alkyl groups include methyl, ethyl, propyl, butyl, t-butyl, hexyl, octyl, decyl, cyclopentyl, cyclohexyl, etc. Alkenyl groups include, for example, those in which one or more CH-CH structures present in the above-mentioned alkyl groups are replaced by C=C structures, and more specifically, include vinyl, allyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl, etc. Alkynyl groups include, for example, those in which one or more CH ₂ -CH ₂ structures present in the above-mentioned alkyl groups are replaced by C≡C structures, and more specifically, include ethynyl, 1-propynyl, 2-propynyl, etc.

The above-mentioned alkyl, alkenyl, and alkynyl groups, when all of which have 1 to 10 carbon atoms, may have substituents, and may form a ring structure through the substituents. Furthermore, the meaning of forming a ring structure through the substituents 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 a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organic oxygen group, an organic sulfur group, an organic silyl group, an acyl group, an ester group, a thioester group, a phosphate group, an amide group, an alkyl group, an alkenyl group, an alkynyl group, and the like.

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

The aryl group as a substituent is, for example, a phenyl group, etc. The aryl group may be further substituted with the other substituents mentioned above.

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

The organic thio group as a substituent is, for example, a structure represented by -S-R. The R is, for example, the alkyl, alkenyl, alkynyl, aryl, etc. exemplified above. These Rs may be further substituted by the substituents described above. Specific examples of the alkylthio group include, for example, methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, octylthio, etc.

The organic silyl group as a substituent is, for example, a structure represented by -Si-(R) _3. The R may be the same or different, for example, the aforementioned alkyl, alkenyl, alkynyl, aryl, etc. These R groups may be further substituted by the aforementioned substituents. Specific examples of the alkylsilyl group include, for example, trimethylsilyl, triethylsilyl, tripropylsilyl, tributylsilyl, tripentylsilyl, trihexylsilyl, pentyldimethylsilyl, hexyldimethylsilyl, etc.

The acyl group as a substituent is, for example, a structure represented by -C(O)-R. The R is, for example, the alkyl group, alkenyl group, aryl group, etc. exemplified above. These Rs may be further substituted by the substituents mentioned above. Specific examples of the acyl group include, for example, methyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, pentyl group, isopentyl group, benzoyl group, etc.

The ester group as a substituent, for example, a structure represented by -C(O)O-R, or -OC(O)-R. The R, for example, is the aforementioned alkyl, alkenyl, alkynyl, aryl, etc. These Rs 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. The R is, for example, the aforementioned alkyl, alkenyl, alkynyl, aryl, etc. These Rs 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, alkenyl, alkynyl, aryl, etc. These R may be further substituted by the aforementioned substituent.

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

The aryl group as a substituent is, for example, the same as the aforementioned aryl group, and the aryl group may be further substituted by the aforementioned other substituent.

The alkyl group as a substituent is, for example, the same as the aforementioned alkyl group. The alkyl group may be further substituted by the aforementioned other substituent.

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

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

Generally speaking, when a giant structure is introduced, the reactivity of the amino group or the liquid crystal orientation can be reduced. Therefore, _B1 and _B2 are preferably hydrogen atoms or alkyl groups having 1 to 5 carbon atoms which may have a substituent, and hydrogen atoms, methyl groups or ethyl groups are particularly preferred.

The structure of _Y1 in formula (2) is not particularly limited as long as it has at least one structure selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocyclic ring. Therefore, specific examples thereof include a divalent organic group having at least one structure selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocyclic ring represented by the following formulas (YD-1) to (YD-5).

In formula (YD-1), _A1 is a nitrogen-containing heterocyclic ring having 3 to 15 carbon atoms, and _Z1 is a hydrogen atom or a substituted alkyl group having 1 to 20 carbon atoms.

In formula (YD-2), _W1 is a alkyl group having 1 to 10 carbon atoms, and _A2 is a monovalent organic group having 3 to 15 carbon atoms and a heterocyclic ring containing a nitrogen atom, or a disubstituted amino group substituted with an aliphatic group having 1 to 6 carbon atoms.

In formula (YD-3), _W2 is a divalent organic group having 6 to 15 carbon atoms and 1 to 2 benzene rings, _W3 is an alkylene group having 2 to 5 carbon atoms or a biphenylene group, _Z2 is a hydrogen atom, an alkylene group having 1 to 5 carbon atoms, or a benzene ring, and a is an integer from 0 to 1.

In formula (YD-4), _A3 is a heterocyclic ring having 3 to 15 carbon atoms and containing a nitrogen atom.

In formula (YD-5), _A4 is a heterocyclic ring having 3 to 15 carbon atoms and containing a nitrogen atom, and _W5 is an alkylene group having 2 to 5 carbon atoms).

The heterocyclic rings containing nitrogen atoms and having 3 to 15 carbon atoms of _A1 , _A2 , _A3 , and _A4 in formula (YD-1), (YD-2), (YD-4), and (YD-5) are not particularly limited as long as they are known structures. Examples thereof include pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyridine, , indole, benzimidazole, quinoline, isoquinoline, carbazole, etc., with piperazine, piperidine, indole, benzimidazole, imidazole, carbazole and pyridine being preferred.

In addition, specific examples of _Y2 in 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 suppressing charge accumulation caused by AC driving, formulas (YD-14) to (YD-21) are preferred, with (YD-14) and (YD-18) being 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 formulas (YD-24), (YD-25), (YD-28) and (YD-29), j is an integer from 0 to 3.

The ratio of the diamine represented by formula (2) in the polyamide or the imidized polymer of the polyamide of component (A-1) or component (A-2) of the present invention is preferably 10 to 100 mol %, more preferably 30 to 100 mol %, and particularly preferably 50 to 100 mol %, based on 1 mol of the total diamine used to prepare component (A-1) or component (A-2).

The diamine represented by formula (2) in the components (A-1) and (A-2) of the present invention for producing polyamide and imidized polymer of polyamide may be used alone or in combination. In this case, the total amount of the diamine represented by formula (2) is preferably used in the above-mentioned preferred amount. In addition, it is preferred to use the same diamine in the components (A-1) and (A-2) from the viewpoint of further improving the effect of the present invention.

In the present invention, the diamine used in the components (A-1) and (A-2) for producing the polyamide and the imidized polymer of the polyamide is preferably the same.

The polyamide of the component (A-1) or component (A-2) contained in the liquid crystal alignment agent of the present invention may be a diamine represented by the following formula (5) in addition to the diamine represented by the above formula (2). _Y2 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. In addition, the specific examples include the following (Y-1) to (Y-49) and (Y-57) to (Y-75).

If the proportion of the diamine represented by formula (5) in the polyamide of component (A-1) or component (A-2) of the liquid crystal alignment agent of the present invention is too high, the effect of the present invention may be impaired, which is not good. Therefore, the proportion of the diamine represented by formula (5) is preferably 0 to 90 mol%, more preferably 0 to 50 mol%, and particularly preferably 0 to 20 mol%, relative to 1 mol of the total diamine.

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

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

The organic solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc. from the viewpoint of solubility of the monomer and the polymer. These may be used alone or in combination of two or more.

The concentration of the polymer is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of not easily causing the polymer to precipitate and easily obtaining a high molecular weight product.

When the polyamine 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. Alternatively, the precipitation is performed several times, and after washing with a poor solvent, it is dried at room temperature or under heating to obtain a purified polyamine powder. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene, etc., and water, methanol, ethanol, 2-propanol, etc. are preferred.

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

In the case of preparing polyimide from polyamic acid, a simple method is to add a catalyst to the solution of the polyamic acid obtained by reacting the diamine component with tetracarboxylic dianhydride to perform a chemical imidization reaction. Chemical imidization can be performed at a relatively low temperature, and it is not easy to cause the molecular weight of the polymer to decrease during the imidization process, which is preferred.

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. The organic solvent may be the solvent used in the above-mentioned polymerization reaction. Examples of alkaline catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it can maintain appropriate alkalinity during the reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. Among them, acetic anhydride is preferred because it can be easily purified after the reaction.

The temperature for the imidization reaction can be -20 to 140°C, preferably 0 to 100°C, and the reaction time can be 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mole times of the polyamide group, preferably 2 to 20 mole times, and the amount of the acid anhydride is 1 to 50 mole times of the polyamide group, preferably 3 to 30 mole times. The imidization rate of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature, and the reaction time.

Since the added catalyst etc. remain in the solution after the imidization reaction of polyamine, it is preferred to recover the imidized polymer by the following means and redissolve it in an organic solvent to use it as the liquid crystal alignment agent of the present invention.

The polyimide solution obtained in the above manner is injected into a poor solvent while being fully stirred to precipitate the polymer. After several precipitations, the polymer is washed with a poor solvent and dried at room temperature or under heating to obtain a purified polymer powder.

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

The content ratio of the components (A-1) and (A-2) obtained by the method, relative to the content ratio of the tetracarboxylic dianhydride represented by the above formula (1) to the aliphatic tetracarboxylic dianhydride, is 10:90 to 90:10, preferably 20:80 to 80:20, more preferably 40:60 to 60:40, particularly preferably 46:54 to 54:46, and the ratio calculated on an equivalent basis is the best.

<Component (B)> The component (B) contained in the liquid crystal alignment agent of the present invention is at least one polymer selected from the group consisting of a polyimide precursor, an imidized polymer of the polyimide precursor, and a photosensitive side-chain acrylic polymer having liquid crystal properties within a specific temperature range.

<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 independently a tetravalent organic group, Y ₁₁ is 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 are independently a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.

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

In formula (11), _X11 is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. In the polyimide precursor, _X11 may be a mixture of two or more. Specific examples of _X11 include the structures of the following formulas (X-1) to (X-44).

In the above formula (X-1), R ₈ to R ₁₁ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group, or a phenyl group. When R ₈ to R ₁₁ are a giant structure, there is a possibility of reducing the orientation of the liquid crystal. Therefore, a hydrogen atom, a methyl group, or an ethyl group is preferred, and a hydrogen atom or a methyl group is particularly preferred.

In formula (11), _X11 preferably has a structure selected from (X-1) to (X-14) from the viewpoint of monomer availability.

The preferred ratio of the structures selected from (X-1) to (X-14) is, for example, 20 mol% or more of the entire _X11 , more preferably 60 mol% or more, and particularly preferably 80 mol% or more.

In formula (11), _A11 and _A12 each independently represent a hydrogen atom, or 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 alkynyl group having 2 to 10 carbon atoms which may have a substituent.

Specific examples or preferred examples of _A11 and _A12 are the same as those of _B1 and _B2 in the above-mentioned components (A-1) and (A-2).

In formula (11), _Y11 is a divalent organic group derived from a diamine, and its structure is not particularly limited. Specific examples of the structure of _Y11 include (Y-1) to (Y-49) and (Y-57) to (Y-75) or (YD-6) to (YD-38) described in the above-mentioned section of component (A). In addition, the following (Y-76) to (Y-97) and (YD-39) to (YD-52) are also examples.

(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 _Y11 is preferably at least one selected from the structures represented by the following formulae (15) and (16), for example, from the viewpoint of the liquid crystal alignment property or pretilt angle of the obtained liquid crystal alignment film.

In formula (15), _R12 is a single bond or a divalent organic group having 1 to 30 carbon atoms, _R13 is a hydrogen atom, a halogen atom or a monovalent organic group having 1 to 30 carbon atoms, a is an integer of 1 to 4, and when a is 2 or more, _R12 and _R13 may be the same or different from each other. In formula (16), _R14 is a single bond, -O-, -S-, _-NR15- , an amide bond, an ester bond, a urea bond, or a divalent organic group having 1 to 40 carbon atoms, and _R15 is a hydrogen atom or a methyl group.

Specific examples of formula (15) and formula (16) include, for example, the following structures. Since the structure has high linearity, when used as a liquid crystal alignment film, the alignment of the liquid crystal can be improved. Therefore, _Y11 , 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, and Y-75 are more preferred. When the alignment of the liquid crystal can be improved, the proportion of the above structures is, for example, preferably 20 mol% or more of the total _Y11 , more preferably 60 mol% or more, and particularly preferably 80 mol% or more.

From the viewpoint of increasing the pre-tilt angle of the liquid crystal when used as a liquid crystal alignment film, _Y11 preferably has a side chain having a long chain alkyl group, an aromatic ring, an aliphatic ring, a cholesterol skeleton, or a structure obtained by combining them. The _Y11 is preferably 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, and Y-97. Regarding the ratio of the above structure when the pre-tilt angle is increased, for example, 1 to 30 mol% of the total _Y11 is preferred, and 1 to 20 mol% is more preferred.

When a polyimide (pre-driver) having a photo-alignable side chain is used as the polymer of the component (B), it is preferred to use a polyimide (pre-driver) having the following photo-reactive side chain.

(R ¹⁶ represents any one of -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ )-, -CON(CH ₃ )-, -N(CH ₃ )CO-; R ¹⁷ represents a cyclic, unsubstituted or fluorine-substituted alkylene group having 1 to 20 carbon atoms, wherein any -CH ₂ - in the alkylene group may be substituted by -CF ₂ - or -C═C-; and may be substituted by any of the following groups when they are not adjacent to each other: -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, carbocyclic ring, heterocyclic ring. R ¹⁸ represents -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -NH-, -N(CH ₃ )-, -CON(CH ₃ )-, -N(CH ₃ )CO-, a carbocyclic ring, or a heterocyclic ring; R ¹⁹ represents a vinylphenyl group, a -CR ²⁰ =CH ₂ group, a -CR ²⁰ (OH)-CH ₃ group, a carbocyclic ring, a heterocyclic ring, or a structure represented by a formula selected from the following groups; R ²⁰ represents a methyl group which may be substituted by a hydrogen atom or a fluorine atom).

When preparing the polyimide precursors, it is convenient to use a diamine substituted with a side chain represented by the above formula (b).

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

(In formula (21), ^X21 is a single bond or an alkylene group having 1 to 5 carbon atoms, ^X22 is -OCO-CH=CH- or -CH=CH-COO-, ^X23 is a single bond, an alkylene group having 1 to 10 carbon atoms, or a divalent benzene ring, ^X24 is a single bond, -OCO-CH=CH- or -CH=CH-COO-, and ^X25 is a single bond or an alkylene group having 1 to 5 carbon atoms. 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 a bonding group selected from ether (-O-), ester (-COO- or -OCO-) and amide (-CONH- or -NHCO-), Y is an independent single bond or an alkylene group having 1 to 5 carbon atoms, and Z is an independent alkylene group having 1 to 10 carbon atoms or a phenylene group. The bonding position of the amino 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.

The liquid crystal alignment film formed by the liquid crystal alignment agent containing polyimide precursors, polyimide or polyamides, which uses the diamines represented by the above formula (21) as raw materials and contains polyamine acid, polyamine ester, etc., can reduce the change of the liquid crystal alignment performance caused by AC (alternating current) drive, for example, it can reduce the change of the liquid crystal alignment direction. 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 driven by AC, and it will be difficult to produce residual images caused by AC drive, that is, it can achieve a very good effect on the residual image characteristics caused by AC drive. In addition, the liquid crystal alignment film formed by the diamine represented by the above formula (21) has excellent liquid crystal alignment performance itself and has no substantial alignment defects.

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

<Production of polyimide precursor-polyamide> The production method of polyamide listed in the (A-1) component and (A-2) component shall prevail.

<Production of polyimide precursor-polyamic acid ester> The polyamic acid ester used as the polyimide precursor in the present invention can be produced according to the production method (1), (2) or (3) shown below.

(1) Production from polyamine Polyamine esters can be produced by esterifying the polyamine produced by the above method. Specifically, polyamine and an esterifying agent are reacted in the presence of an organic solvent at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to 24 hours, preferably 1 to 4 hours.

The esterifying agent is preferably one that can be easily removed by purification, such as N,N-dimethylformamide dimethyl acetal, 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-triazene) or the like. -2-yl)-4-methylmorpholinium chloride, etc. The amount of the esterifying agent added is preferably 2 to 6 molar equivalents relative to 1 mole of the repeating unit of the polyamine.

The organic solvent includes, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide or 1,3-dimethyl-imidazolidinone. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by formulas [D-1] to [D-3] described below can be used.

These solvents may be used alone or in combination. In addition, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above-mentioned solvents as long as it does not cause the generated polyimide precursor to precipitate. In addition, the water in the solvent will hinder the polymerization reaction and cause the generated polyimide precursor to hydrolyze, so it is better to use the solvent after dehydration and drying.

The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the viewpoint of polymer solubility, and these can be used alone or in combination of two or more. The concentration during production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint of not easily causing polymer precipitation and easily producing a high molecular weight body.

(2) Production by reacting tetracarboxylic acid diester dichloride with diamine Polyamide esters can be produced by reacting tetracarboxylic acid diester dichloride with diamine.

Specifically, the tetracarboxylic acid diester dichloride and diamine are reacted in the presence of an alkali and an organic solvent at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to 24 hours, preferably 1 to 4 hours to obtain the product.

Among the above-mentioned bases, pyridine, triethylamine, 4-dimethylaminopyridine, etc. can be used, but pyridine is preferably used in view of the stable reaction. The amount of base added is an amount that can be easily removed and a high molecular weight body can be easily obtained. It is preferably 2 to 4 molar 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 solubility of monomers and polymers, and these can be used alone or in combination of two or more. The concentration of the polymer during production is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint of preventing the polymer from precipitating and making it easy to produce a high molecular weight body. In addition, in order to prevent the hydrolysis of tetracarboxylic acid diester dichloride, the solvent used in the production of polyamic acid ester is preferably dehydrated as much as possible, and preferably in a nitrogen atmosphere to prevent the mixing of external air.

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

Specifically, the tetracarboxylic acid diester and diamine are reacted in the presence of a condensation agent, a base, and an organic solvent at 0°C to 150°C, preferably 0°C to 100°C, for 30 minutes to 24 hours, preferably 3 to 15 hours to obtain the product.

The condensation agent may be, for example, triphenylphosphite, dicyclohexylcarbonyldiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbonyldiimide hydrochloride, N,N'-carbonyldiimidazole, dimethoxy-1,3,5-tris(II)-iodide, or the like. methylmorpholinium, O-(benzotriazole-1-yl)-N,N,N',N'-tetramethyluronium tetrachloroborate, O-(benzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonicacid diphenyl, etc. The amount of the condensing agent added is preferably 2 to 3 mole times relative to the tetracarboxylic acid diester.

Among the above-mentioned bases, tertiary amines such as pyridine and triethylamine can be used. The amount of base added is preferably 2 to 4 molar times of the diamine component, from the viewpoint of being easy to remove and easy to obtain a high molecular weight product.

In the above reaction, when Lewis acid is added as an additive, the reaction can proceed efficiently. Lewis acid is preferably lithium halides such as lithium chloride and lithium bromide. The amount of Lewis acid added is preferably 0 to 1.0 mole times relative to the diamine component.

Among the above three methods for producing polyamic acid ester, the method (1) or (2) is particularly preferred from the viewpoint of being able to produce polyamic acid ester with a high molecular weight.

When the polyamic acid ester solution prepared by the above method is injected into a poor solvent during sufficient stirring, a polymer can be precipitated. After several precipitations, the solution is washed with a poor solvent and dried at room temperature or under heating to obtain a purified polyamic acid ester powder. The poor solvent is not particularly limited and can be exemplified by water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene, etc.

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

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

The side-chain acrylic polymer can be any one that reacts to light in the wavelength range of 250nm to 400nm and has liquid crystal properties in the temperature range of 100°C to 300°C.

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

The side-chain acrylic polymer preferably has a mesogenic group that exhibits liquid crystallinity within a temperature range of 100° C. to 300° C.

The side chain acrylic polymer has photosensitive side chains in the main chain bond, so it can be responsive to light to cause crosslinking, isomerization, or photo-Fries rearrangement reaction. The structure of the photosensitive side chain is not particularly limited, and generally, a structure that can be responsive to light to cause a crosslinking reaction or a photo-Fries rearrangement reaction is preferred, and a structure that can cause a crosslinking reaction is more preferred. In this case, even when exposed to external pressure such as heat, the achieved orientation control ability can be kept stable for a long time. The structure of the photosensitive side chain acrylic polymer film that can cause liquid crystal is not particularly limited as long as it can meet this characteristic, and generally, a structure with a rigid original liquid crystal component on the side chain structure is preferred. In this case, when the side-chain acrylic polymer is used as a liquid crystal alignment film, a 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 is a structure having an original liquid crystal component such as biphenyl, terphenyl, phenylcyclohexyl, phenylbenzoate, azophenyl, etc., and a photosensitive group bonded to the front end portion that can be sensitive to light and cause a crosslinking reaction or an isomerization reaction, or has a main chain and a side chain bonded to the main chain, the side chain is formed by the original liquid crystal component and has a phenylbenzoate group that can undergo a photo-Fries rearrangement reaction.

More specific examples of the structure of the photosensitive side-chain acrylic polymer having liquid crystal properties within a specific temperature range include, for example, a structure having a main chain consisting of at least one selected from the group consisting of free radical polymerizable groups such as alkyl, (meth)acrylate, itaconate, fumarate, maleate, α-methyl-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, etc., and a side chain formed by at least one of the following formulas (31) to (35).

wherein Ar ₁ represents a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, a naphthyl ring, a pyrrole ring, a furan ring, a thiophene ring, or a pyridine ring; Ar ₂ and Ar ₃ each independently represent a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, a naphthyl ring, a pyrrole ring, a furan ring, a thiophene ring, or a pyridine ring; q ¹ and q ² are either 1 or 0; Ar ₄ and Ar ₅ each independently represent a divalent substituent obtained by removing two hydrogen atoms from a benzene ring, a naphthyl ring, a pyrrole ring, a furan ring, a thiophene ring, or a pyridine ring; Y ₁ -Y ₂ represent 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 having 1 to 18 carbon atoms, a cycloalkylene group having 5 to 8 carbon atoms, a phenylene group, or a biphenylene group, or represents one or more bonds selected from a single bond, an ether bond, an ester bond, an amide bond, a urea bond, a carbamate bond, an amine bond, a carbonyl group, or a combination thereof, or a structure in which the substituent is bonded to 2 or more and 10 positions selected from a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 5 to 8 carbon atoms, a phenylene group, a biphenylene group, or a combination thereof via the one or more bonds, or a structure in which the aforementioned substituents are linked to a plurality of positions via the aforementioned bonds; R ³¹ represents a hydrogen atom, a hydroxyl group, a thiothio group, an amino group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylamino group having 1 to 8 carbon atoms, or a dialkylamino group having 2 to 16 carbon atoms, and the benzene ring and/or the naphthyl ring may be substituted by one or more substituents which are the same or different and are selected from a halogen atom, a cyano group, a nitro group, a carboxyl group, and an alkoxycarbonyl group having 2 to 11 carbon atoms. In this case, the alkyl group having 1 to 10 carbon atoms may be a linear, branched, or cyclic group, or a combination of these structures, and may be substituted by a halogen atom.

The photosensitive side-chain acrylic polymer of component (B) in the present invention has liquid crystal properties within a specific temperature range and may contain liquid crystal side chains.

The original liquid crystal group having liquid crystal side chains may be a group that forms a liquid crystal structure alone, such as biphenyl or phenylbenzoate, or a group that forms a liquid crystal structure in which the side chains form hydrogen bonds, such as benzoic acid. The original liquid crystal group having side chains preferably has the following structure.

<<Method for preparing photosensitive side-chain polymer>> The above-mentioned photosensitive side-chain acrylic polymer having liquid crystal properties within a specific temperature range can be prepared by polymerizing the above-mentioned photoreactive side-chain monomer having photosensitive side chains and the liquid crystal side-chain monomer.

[Photoreactive side chain monomer] When forming a polymer, a photoreactive side chain monomer may be a monomer that forms 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 formula (31) to (35).

More specific examples of the photoreactive side chain monomer include, for example, a structure having a photosensitive side chain formed by a polymerizable group consisting of at least one selected from the group consisting of free radical polymerizable groups such as alkane, (meth)acrylate, itaconate, fumarate, maleate, α-methyl-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, etc., and at least one of the above formulas (31) to (35).

[Liquid crystal side chain monomer] Liquid crystal side chain monomer refers to a monomer whose polymer generated by the monomer has liquid crystal properties and the polymer can form a primary liquid crystal group at the side chain site.

More specific examples of liquid crystalline side chain monomers include, for example, a polymerizable group consisting of at least one selected from the group consisting of free radical polymerizable groups such as alkane, (meth)acrylate, itaconate, fumarate, maleate, α-methyl-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, etc., and a side chain structure of at least one of the aforementioned "original liquid crystalline groups having liquid crystalline side chains".

The side chain acrylic polymer of one aspect of the component (B) can be obtained by polymerizing the above-mentioned photoreactive side chain monomer capable of producing liquid crystallinity. Alternatively, it can be obtained by copolymerizing a photoreactive side chain monomer that does not produce liquid crystallinity with a liquid crystallinity side chain monomer, or by copolymerizing a photoreactive side chain monomer capable of producing liquid crystallinity with a liquid crystallinity side chain monomer. Furthermore, it can be copolymerized with other monomers as long as the ability to produce liquid crystallinity is not impaired.

Other monomers include, for example, monomers that are easily available industrially 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 the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and the like.

Acrylate compounds, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthracene acrylate, anthracene methacrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isoborneol acrylate, 2-methoxyethyl acrylate, triethylene glycol methoxyacrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, and 8-ethyl-8-tricyclodecyl acrylate.

Methyl acrylate compounds, for example, methyl methacrylate, ethyl methyl acrylate, isopropyl methyl acrylate, benzyl methyl acrylate, naphthyl methacrylate, anthracene methacrylate, anthracene methyl methacrylate, phenyl methyl acrylate, 2,2,2-trifluoroethyl methyl acrylate, tert-butyl methyl acrylate, cyclohexyl methyl acrylate, isobornyl methyl acrylate, 2-methoxyethyl methyl acrylate, methoxytriethylene glycol methyl acrylate, 2-ethoxyethyl methyl acrylate, tetrahydrofurfuryl methyl acrylate, 3-methoxybutyl methyl acrylate, 2-methyl-2-adamantyl methyl acrylate, 2-propyl-2-adamantyl methyl acrylate, 8-methyl-8-tricyclodecyl methyl acrylate, and 8-ethyl-8-tricyclodecyl methyl acrylate. (Meth)acrylate compounds having a cyclic ether group such as glycidyl (meth)acrylate, (3-methyl-3-cyclohexyl)methyl (meth)acrylate, and (3-ethyl-3-cyclohexyl)methyl (meth)acrylate may also be used.

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

Styrene compounds, for example, styrene, methylstyrene, chlorostyrene, bromostyrene and the like.

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

The method for producing the side-chain polymer of this embodiment is not particularly limited, and a method widely used in general industrial processing can be used. Specifically, for example, cationic polymerization, free radical polymerization, or anionic polymerization of vinyl groups of liquid crystal side-chain monomers or photoreactive side-chain monomers can be used to produce the polymer. Among these, free radical polymerization is particularly preferred from the perspective of easy reaction control.

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

The free radical polymerization method is not particularly limited, and may be emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization, solution polymerization, or the like.

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 as long as it can dissolve the generated polymer. Specific examples thereof are listed below.

N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfoxide, hexamethyl sulfoxide, γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonanone, methyl ethyl ketone, methyl isoamyl ketone, methyl isoacetone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve 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 monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutyl ester, amyl acetate, butyl butyrate, 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 monoacetate Ethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, glyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropaneamide, 3-ethoxy-N,N-dimethylpropaneamide, 3-butoxy-N,N-dimethylpropaneamide, etc.

These organic solvents may be used alone or in combination. Furthermore, even if the solvent does not dissolve the generated polymer, it may be used in combination with the above organic solvents as long as the generated polymer does not precipitate.

In addition, in free radical polymerization, since oxygen in the organic solvent is the cause of the polymerization reaction, it is better to use an organic solvent that is degassed as much as possible.

The polymerization temperature during free radical polymerization can be selected from any temperature between 30°C and 150°C, preferably from 50°C to 100°C. In addition, although the reaction can be carried out at any concentration, it is difficult to produce a high molecular weight polymer when the concentration is too low, and it is difficult to stir evenly because the viscosity of the reaction solution is excessively increased when the concentration is too high. Therefore, the monomer concentration is preferably 1% by mass to 50% by mass, and more preferably 5% by mass to 30% by mass. The reaction can be carried out at a high concentration at the initial stage, and then an organic solvent can be added.

In the above-mentioned free radical polymerization reaction, if the ratio of the free radical polymerization initiator is too much relative to the monomer, the molecular weight of the obtained polymer will be reduced, and if it is too little, the molecular weight of the obtained polymer will be increased. Therefore, the ratio of the free radical initiator is preferably 0.1 mol% to 10 mol% relative to the monomer to be polymerized. Various monomer components, solvents, initiators, etc. can also be added during the polymerization.

[Recovery of photosensitive side-chain acrylic polymers with liquid crystallinity within a specific temperature range] In the case of recovering the polymers generated from the reaction solution of the photosensitive side-chain polymers that can produce liquid crystallinity obtained by the above reaction, the reaction solution can be put into a poor solvent to precipitate the polymers. The poor solvent used for precipitation is, for example, methanol, acetone, hexane, heptane, butyl solvent, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, water, etc. The polymer precipitated by putting into the poor solvent can be filtered and recovered, and then dried at normal pressure or reduced pressure, at room temperature or under heating. Furthermore, when the polymer recovered by precipitation is dissolved in an organic solvent and then precipitated and recovered for 2 to 10 times, the impurities in the polymer can be reduced. The poor solvent at this time can be, for example, alcohols, ketones, hydrocarbons, etc. It is better to use more than 3 types of poor solvents selected from these because it can further improve the purification efficiency.

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

The content of the components (A-1), (A-2) and (B) in the liquid crystal alignment agent of the present invention is preferably such that the mass ratio of the total amount of the components (A-1) and (A-2) to the component (B) is 5:95 to 95:5, more preferably 10:90 to 90:10.

The imidization ratio of the components (A-1), (A-2) and (B) in the liquid crystal alignment agent of the present invention can be adjusted arbitrarily according to the application or purpose. From the viewpoint of solubility or charge storage characteristics, the imidization ratio of the specific polymer components (A-1) and (A-2) is preferably 0-55%, and more preferably 0-20%. In addition, from the viewpoint of liquid crystal alignment or alignment regulation force, voltage retention, the imidization ratio of the specific polymer (B) is preferably higher, preferably 40%-95%, and more preferably 55-90%.

<Liquid crystal alignment agent> The liquid crystal alignment agent used in the present invention is a solution formed by dissolving a polymer component in an organic solvent. The molecular weight of the polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and particularly preferably 10,000 to 100,000. In addition, 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 in accordance with the thickness of the coating to be formed. From the perspective of forming a uniform and defect-free coating, it is preferably 1% by mass or more, and from the perspective of solution storage stability, it is preferably 10% by mass or less. The most preferred 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 make the polymer components uniformly dissolved. Specific examples thereof include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N,N-dimethylpropaneamide, etc. These can be used alone or in combination of two or more. Furthermore, even if the solvent alone cannot dissolve the polymer component uniformly, it can be used in combination with the above-mentioned organic solvent as long as it is within a range that does not cause the polymer to precipitate.

In addition, the organic solvent contained in the liquid crystal alignment agent can be used as a mixed solvent in addition to the above-mentioned solvents and a solvent that can improve the coating property or the smoothness of the coating surface when the liquid crystal alignment agent is applied. The liquid crystal alignment agent of the present invention is also suitable for use with these mixed solvents. Specific examples of organic solvents that can be used in combination are as follows, but 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, isopentanol, 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-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, Alcohol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate Ester, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(butoxyethoxy)propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl 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, diethylene 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 monoethyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, solvents represented by the following formulas [D-1] to [D-3], etc.

In the formula [D-1], ^D1 represents an alkyl group having 1 to 3 carbon atoms, in the formula [D-2], ^D2 represents an alkyl group having 1 to 3 carbon atoms, and in the formula [D-3], ^D3 represents an alkyl group having 1 to 4 carbon atoms.

Preferred solvent combinations include, 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-pentanone and diethylene glycol diethyl ether, N-methyl- 2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, etc. The types and contents of these solvents can be appropriately selected in accordance with the coating equipment, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

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

The amount of these additives is preferably 0.1 to 30 parts by weight relative to 100 parts by weight of the polymer component contained in the liquid crystal alignment agent. If it is less than 0.1 parts by weight, no effect can be expected, and if it exceeds 30 parts by weight, the liquid crystal alignment will be reduced, so it is more preferably 0.5 to 20 parts by weight.

In addition to the above, the liquid crystal alignment agent of the present invention may include polymers other than polymers, dielectrics or conductive substances for the purpose of changing the electrical properties of the liquid crystal alignment film such as the dielectric constant or conductivity, silane coupling agents for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate, cross-linking compounds for the purpose of increasing the film hardness or density when used as a liquid crystal alignment film, or imidization promoters for the purpose of increasing the effective imidization reaction of polyamine when the coating is sintered, etc., within the scope that does not impair the effect of the present invention.

<Liquid crystal alignment film> <Method for manufacturing liquid crystal alignment film> The liquid crystal alignment film of the present invention is a film obtained by applying 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 applied is not particularly limited as long as it is a substrate with high transparency. It can use a glass substrate, a silicon nitride substrate, an acrylic substrate, a polycarbonate substrate and other plastic substrates. From the perspective of simplification, it is preferred to use a substrate formed with an ITO electrode for driving the liquid crystal. In addition, if the reflective liquid crystal display element is only a single-sided substrate, an opaque material such as a silicon wafer can also be used. In this case, the electrode can also use a material that can reflect light such as aluminum.

The coating method of the liquid crystal alignment agent of the present invention includes, for example, a spin coating method, a printing method, an inkjet method, etc. The drying and sintering steps after coating the liquid crystal alignment agent of the present invention can be performed at any temperature and time. Usually, to fully remove the organic solvent contained, it can be dried at 50°C to 120°C for 1 minute to 10 minutes, and then sintered at 150°C to 300°C for 5 minutes to 120 minutes. There is no special limitation on the thickness of the coating after sintering, but if it is too thin, the reliability of the liquid crystal display element will be reduced, so it is usually 5 to 300nm, preferably 10 to 200nm.

The obtained liquid crystal alignment film is subjected to an alignment treatment method, for example, a rubbing method, a photo-alignment treatment method, etc.

The friction treatment can be performed using an existing friction device. The material of the friction cloth at this time is, for example, cotton, nylon, rayon, etc. The conditions for the friction treatment are generally 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 or alcohol is used to remove the residue generated by the friction caused by ultrasonic cleaning.

Specific examples of photo-alignment treatment methods include, for example, using radiation biased in a specific direction to irradiate the aforementioned coating surface, and depending on the circumstances, further heating it at a temperature of 150 to 250°C to impart liquid crystal alignment capabilities. Radiation, for example, can be ultraviolet light and visible light with a wavelength of 100nm to 800nm. Among them, ultraviolet light with a wavelength of 100nm to 400nm is preferred, and ultraviolet light with a wavelength of 200nm to 400nm is particularly preferred. In addition, for the purpose of improving the alignment of liquid crystals, the coated substrate can be irradiated with radiation while heating at 50 to 250°C. The irradiation amount of the aforementioned radiation is preferably 1 to 10,000mJ/ ^cm2 , and particularly preferably 100 to 5,000mJ/ ^cm2 . The liquid crystal alignment film prepared in the above manner can align the liquid crystal molecules stably in a specific direction.

Furthermore, the higher the extinction ratio of polarized ultraviolet light is, the better it is because it can impart a higher anisotropy. Specifically, the extinction ratio relative to the linearly polarized ultraviolet light is preferably 10:1 or more, more preferably 20:1 or more.

The film irradiated with polarized radiation obtained in the above manner may then be contact treated with a solvent containing at least one selected from water and an organic solvent.

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

From the viewpoint of wide applicability or safety, it is preferred 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 a mixed solvent of water and 2-propanol are particularly preferred.

In the present invention, the contact treatment between the film irradiated with polarized radiation and the solution containing an organic solvent is carried out by using a treatment method such as immersion treatment or spray treatment so that the film and the liquid can be in good and sufficient contact. Among them, the method of immersing the film in the solution containing an organic solvent for preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferred. The contact treatment can be carried out at room temperature or under heating, preferably at 10 to 80°C, more preferably at 20 to 50°C. In addition, if necessary, a means of improving contact such as ultrasound can be applied.

After the above contact treatment, the organic solvent in the solution after use can be removed by rinsing or drying with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, etc., or both.

In addition, the film that has been contact treated with a solvent may 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. A higher temperature can promote the realignment of the molecular chain, but too high a temperature may cause the molecular chain to decompose. Therefore, the heating temperature is preferably, for example, 180 to 250° C., and particularly preferably 200 to 230° C.

If the heating time is too short, the molecular chain realignment effect may not be achieved. If it is too long, the molecular chain may be decomposed. Therefore, 10 seconds to 30 minutes is preferred, and 1 minute to 10 minutes is more preferred.

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

Solvents used in the re-production process include the following solvents: glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, etc.; glycol esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, etc.; glycols such as diethylene glycol, propylene glycol, butylene glycol, hexylene glycol, etc.; alcohols such as methanol, ethanol, 2-propanol, butanol, etc.; acetone, methyl ethyl ketone, cyclopentanone, cyclohexane Ketones such as 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxylate, ethyl hydroxylate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, and amides such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone.

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

The reprocessing is carried out by heating the above-mentioned reprocessing materials at room temperature or between 30°C and 100°C, and then immersing the substrate with the liquid crystal alignment film therein for 1 second to 1000 seconds, preferably 30 seconds to 500 seconds, or spraying the reprocessing materials by spraying, and then washing the liquid with an alcohol solvent or pure water. In addition, the temperature of the reprocessing liquid during the reprocessing is preferably low from the viewpoint of operating efficiency, 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 is a liquid crystal unit manufactured by a known method using the liquid crystal alignment agent of the present invention and a substrate with a liquid crystal alignment film according to the aforementioned method for manufacturing a liquid crystal alignment film, and then used as a liquid crystal display element.

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

First, prepare transparent glass substrates, and set a common electrode on one side of the substrate and a segment electrode on the other side of the substrate. These electrodes can be, for example, ITO electrodes, or can form a pattern of the desired image display. Next, an insulating film covering the common electrode and the segment electrode can be set on each substrate. The insulating film is, for example, a film formed of _SiO2 - _TiO2 obtained by a sol-gel method.

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

Next, the substrate on one side is overlapped with the substrate on the other side in such a way that the alignment film surfaces face each other, and the periphery is connected using a sealant. In the sealant, spacers are usually mixed for the purpose of controlling the gap between the substrates. In addition, in the part of the surface where the sealant is not set, spacers for controlling the gap between the substrates are also preferably dispersed. A part of the sealant is set with an opening 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 with an adhesive. The injection method may be a vacuum injection method or a method utilizing the capillary phenomenon in the atmosphere. Then, the polarizing plate is installed. Specifically, a pair of polarizing plates are attached to the surface opposite to the liquid crystal layer of the two substrates. After the above steps, the liquid crystal display element of the present invention is obtained.

In the present invention, the sealant may be a resin that is cured by ultraviolet irradiation or heating and has a reactive group such as an epoxy group, an acryl group, a methacryl group, a hydroxyl group, an allyl group, an acetyl group, etc. In particular, a curing resin having both an epoxy group and a (meth)acryl group as reactive groups is preferably used.

In order to improve adhesion and moisture resistance, an inorganic filler may be added to the sealant of the present invention. The inorganic filler that can be used is not particularly limited, and specifically includes, for example, spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, silicic acid, etc. Calcium, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanium oxide, nitrate fiber, carbon fiber, molybdenum disulfide, asbestos, etc., preferably spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, aluminum hydroxide, calcium silicate, aluminum silicate. The above-mentioned inorganic fillers may be used in combination of two or more.

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

[Example]

In the detailed description of the manufacturing method of the present invention, the experimental methods for studying the composition of raw materials or the addition ratio, and the results and typical examples of the manufacturing method will be listed. In addition, the present invention is not limited to these examples. Description of the abbreviations used in this embodiment (Organic solvent) NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Butyl cellosolve Acid dianhydride (A): Formula (A) Acid dianhydride (B): Formula (B) Acid dianhydride (C): Formula (C) Acid dianhydride (D): Formula (D) Acid dianhydride (E): Formula (E) DA-1: Formula (DA-1) DA-2: Formula (DA-2) DA-3: Formula (DA-3) DA-4: Formula (DA-4) DA-5: Formula (DA-5) DA-6: Formula (DA-6) DA-7: Formula (DA-7) DA-8: 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 methods for measuring viscosity, measuring imidization rate, evaluating reproducibility, making liquid crystal cells, and evaluating charge relaxation properties.

[Viscosity measurement] In the synthesis examples, the viscosity of polyamide ester and polyamide acid solution was obtained by measuring a sample volume of 1.1 mL and CORD-1 (1°34', R24) at a temperature of 25°C using an E-type viscometer TV-25H (manufactured by Toki Sangyo Co., Ltd.).

[Determination of imidization rate] 20 mg of polyimide powder was placed in an NMR sample tube (NMR standard sample tube φ5 manufactured by Kusano Scientific Co., Ltd.), 0.53 ml of dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) was added, and ultrasonic waves were applied to completely dissolve it. The solution was measured at 500 MHz proton NMR using an NMR analyzer (JNW-ECA500) manufactured by JEC Data Corporation. The imidization rate was measured using protons derived from structures that did not change before and after imidization as reference protons, and the peak integral value of the protons and the peak integral value of the protons derived from the NH group of acylamin acid appearing around 9.5 to 10.0 ppm were calculated according to the following formula.

Imidization rate (%) = (1-α・x/y) × 100 In the above formula, x is the peak integral value of protons generated by the NH group of acylamidin, y is the peak integral value of the reference proton, and α is the ratio of the number of reference protons to one NH group proton of acylamidin in the state of polyacylamidin (acylimidization rate is 0%).

[Evaluation of reproducibility] The liquid crystal alignment agent of the present invention was applied to an ITO substrate using a rotary coater. After drying on a 60°C heating plate for 1 minute and 30 seconds, it was sintered in a 230°C hot air circulation oven for 20 minutes to form a coating with a thickness of 100 nm. Subsequently, the prepared substrate was immersed in the heated reproducible material for 300 seconds, developed, and then washed with ultrapure water for 20 seconds. Subsequently, the spray treatment was performed and evaluated according to the following criteria. The results are shown in Table 4. ○: 35℃, 5 minutes, no residual film is produced △: 40℃, 5 minutes, no residual film is produced ×: 40℃, 5 minutes, residual film is produced

[Production of Liquid Crystal Cell] Production of a liquid crystal cell with the structure of a wide viewing angle switching (Fringe Field Switching: hereinafter also referred to as FFS) mode liquid crystal display element.

First, prepare a substrate with electrodes. The substrate is a glass substrate with a size of 30mm×50mm and a thickness of 0.7mm. An ITO electrode with a viscous pattern is formed on the substrate as the first layer constituting the counter electrode. The second layer on the first layer of the counter electrode is a SiN (silicon nitride) film formed by the CVD method. The second layer of the SiN film has a thickness of 500nm and has the function of an interlayer insulating film. On the second layer of the SiN film, a pixel electrode with a serration shape formed by patterning the ITO film is arranged as the third layer, and two pixels, the first pixel and the second pixel, are formed. The size of each pixel is 10mm in length and about 5mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

The pixel electrode of the third layer has a serrated shape formed by a plurality of electrode elements arranged in a "ㄑ" shape with a bent center portion. The width of each electrode element in the short side direction is 3μm, and the interval between the electrode elements is 6μm. Since the pixel electrode forming each pixel is composed of a plurality of electrode elements arranged in a "ㄑ" shape with a bent center portion, the shape of each pixel is not a rectangular shape, but is similar to the electrode element, in the shape of a bold "ㄑ" with a bent center portion. Therefore, each pixel is divided into upper and lower parts with the bent center portion as a boundary, and has a first region located on the upper side of the bent portion and a second region located on the lower side.

When comparing the first area and the second area of each pixel, the difference is that the electrode elements of the pixel electrode constituting the pixel have different formation directions. That is, based on the rubbing direction of the liquid crystal alignment film described later, the first area of the pixel is formed in a manner that the electrode element of the pixel electrode is at an angle of +10° (clockwise), and the second area of the pixel is formed in a manner that the electrode element of the pixel electrode is at an angle of -10° (clockwise). That is, the first area and the second area of each pixel have a structure in which the directions of the rotation action (in-plane opening and closing) of the liquid crystal in the substrate surface caused by the application of voltage between the pixel electrode and the counter electrode are opposite to each other.

Secondly, the obtained liquid crystal alignment agent is filtered using a 1.0μm filter, and then coated on the prepared substrate with electrodes and a glass substrate with a 4μm high columnar spacer formed on the inner surface of an ITO film using a rotary coater. After drying on a heating plate at 80°C for 5 minutes, it is sintered in a hot air circulation oven at 230°C for 20 minutes to form a coating with a film thickness of 100nm. The coating surface is subjected to alignment treatments such as friction or polarized ultraviolet irradiation to obtain a substrate with a liquid crystal alignment film. The above two substrates are used as a group, and a sealant is printed on the substrate. The other substrate is bonded in a manner that the orientation direction is 0° facing the liquid crystal alignment film surface, and the sealant is hardened to obtain an empty unit. Liquid crystal MLC-2041 (Merck Co., Ltd.) was injected into the empty cell using a reduced pressure injection method, and the injection port was sealed to produce an FFS-driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110°C for 1 hour, left overnight, and used for various evaluations.

[Charge relaxation characteristic evaluation] The above-mentioned liquid crystal unit is placed on a light source, and the V-T characteristic (voltage-transmittance characteristic) is measured at room temperature. Then, the transmittance (Ta) of the liquid crystal unit is measured when a rectangular wave of ±1.5V/60Hz is applied. Subsequently, the transmittance (Tb) of the liquid crystal unit is measured during 30 minutes of driving under superimposed direct current 1V. After the direct current voltage is cut off, the transmittance (Tc) of the liquid crystal unit is measured when only a rectangular wave of ±1.5V/60Hz is used and driven for 20 minutes. The difference (ΔT) between the transmittance at each time (Tb, Tc) and the initial transmittance (Ta) is used to calculate the difference in transmittance caused by the voltage remaining in the liquid crystal display element. The earlier the residual voltage is relaxed, the less likely it is to experience burn-in. (Tb-Ta) is marked as ○ if it drops below 2% 5 minutes after the DC voltage is applied, and marked as × if it is above. (Tc-Ta) is marked as ○ if it drops below 2% 5 minutes after the DC voltage is cut off, and marked as × if it is above. The results are shown in Table 4.

(Polymerization Example 1) 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 stir to dissolve at 23°C with nitrogen flowing in. While stirring, add 93.2g of dianhydride (E) to the diamine solution, and then add 168g of NMP, and stir for 3 hours at 40°C in a nitrogen atmosphere. Then add 28.2g of dianhydride (D), and then add 160g of NMP, and stir for 4 hours at 23°C in a nitrogen atmosphere to obtain a polyamine solution (PAA-1). The viscosity of the polyamine solution at a temperature of 25°C is 200mPa・s. In a 300 mL Erlenmeyer flask equipped with a stirrer, filter out 20.4 g of the polyimide powder, add 150 g of NMP, and stir at 50°C for 20 hours to dissolve it, thereby obtaining a polyimide solution (SPI-1).

20.4 g of the polyimide powder was filtered into a 300 mL Erlenmeyer flask equipped with a stirrer, 150 g of NMP was added, and the mixture was stirred at 50° C. for 20 hours to dissolve. 16.3 g of the solution was filtered into a 100 mL Erlenmeyer flask equipped with a stirrer, 3.46 g of NMP, 13.0 g of GBL, 1.95 g of an NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, and 8.69 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a polyimide solution (SPI-1).

(Polymerization Example 2) Place a 100mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 0.58g of (DA-6), 1.32g of (DA-4), 0.93g of (DA-5), and 3.01g of (DA-7), add 42.8g of NMP, and stir to dissolve at 23°C with nitrogen flowing in. Add 3.91g of dianhydride (E) to the diamine solution while stirring, and then add 12.4g of NMP, stir for 16 hours at 40°C in a nitrogen atmosphere to obtain a polyamide solution (PAA-2). The viscosity of the polyamide solution at 25°C is 450cps.

(Polymerization Example 3) Place a 100mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 6.19g (DA-9) and 2.14g (DA-8), add 61.1g NMP, and stir to dissolve at 23°C with nitrogen flowing in. Add 5.71g of dianhydride (B) to the diamine solution while stirring, and then add 18.5g of NMP, stir for 16 hours at 50°C in a nitrogen atmosphere to obtain a polyamine solution (PAA-3). The viscosity of the polyamine solution at 25°C is 351cps.

(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, and stir to dissolve at 23°C with nitrogen. Add 1.75g of dianhydride (B) and 4.3g of NMP to the diamine solution while stirring. Stir for 2 hours at 23°C in a nitrogen atmosphere, then add 1.41g of dianhydride (D) and 8.0g of NMP. Stir for 2 hours at 23°C in a nitrogen atmosphere. Then, stir at 50°C for 16 hours to obtain a polyamine solution (PAA-4). The viscosity of the polyamine solution at 25°C is 240cps.

(Polymerization Example 5) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.96g of (DA-3), add 25.7g of NMP, and stir to dissolve at 23°C with nitrogen. Add 3.00g of dianhydride (C) and 11.2g of NMP to the diamine solution while stirring. Stir for 2 hours at 23°C in a nitrogen atmosphere, then add 0.77g of dianhydride (D) and 4.4g of NMP. Stir for 2 hours at 23°C in a nitrogen atmosphere. Then, stir at 50°C for 16 hours to obtain a polyamine solution (PAA-5). The viscosity of the polyamine solution at 25°C is 358cps.

(Polymerization Example 6) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.46g of (DA-2), add 22.3g of NMP, and stir to dissolve at 23°C with nitrogen. Add 2.00g of dianhydride (C) and 6.3g of NMP to the diamine solution while stirring, stir for 2 hours at 23°C in a nitrogen atmosphere, then add 1.51g of dianhydride (D) and 8.5g of NMP, and stir for 2 hours at 23°C in a nitrogen atmosphere. Then, stir at 50°C for 16 hours to obtain a polyamine solution (PAA-6). The viscosity of the polyamine solution at 25°C is 333cps.

(Polymerization Example 7) Place a 50mL four-necked flask with a stirring device in a nitrogen atmosphere, weigh 2.55g of (DA-1) and 0.46g of (DA-2), add 22.3g of NMP, and stir to dissolve at 23°C with nitrogen flowing in. Add 4.5g of dianhydride (A) to the diamine solution while stirring, and then add 20.5g of NMP, stir for 2 hours at 23°C and nitrogen atmosphere, and then stir for 16 hours at 50°C to obtain a polyamide solution (PAA-7). The viscosity of the polyamide solution at 25°C is 350cps.

(Polymerization Example 8) 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, and stir to dissolve at 23°C with nitrogen. Add 3.00g of dianhydride (C) and 12.0g of NMP to the diamine solution while stirring. Stir for 2 hours at 23°C in a nitrogen atmosphere, then add 0.72g of dianhydride (D) and 4.1g of NMP. Stir for 2 hours at 23°C in a nitrogen atmosphere. Then, stir at 50°C for 16 hours to obtain a polyamine solution (PAA-8). The viscosity of the polyamine solution at 25°C is 333cps.

(Comparative Example 1) In a 50 mL Erlenmeyer flask with a stirrer, filter 7.00 g of the polyimide solution (SPI-1), 10.40 g of (PAA-4), 2.40 g of NMP solution containing 1 wt% of (AD-1), and 0.72 g of NMP solution containing 10 wt% of (AD-2) obtained above, add 7.48 g of NMP and 12.00 g of BCS, and stir for 2 hours with a magnetic stirrer to obtain a liquid crystal alignment agent (A-1).

(Comparative Example 2) In a 50 mL Erlenmeyer flask with a stirrer, 6.73 g of the polyamide solution (PAA-2), 15.27 g of (PAA-5), 2.40 g of NMP solution containing 1 wt% of (AD-1), and 0.72 g of NMP solution containing 10 wt% of (AD-2) obtained in the comparative synthesis example were filtered, 2.88 g of NMP and 12.00 g of BCS were added, and stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-2).

(Comparative Example 3) In a 50 mL Erlenmeyer flask with a stirrer, 4.00 g of the polyamine solution (PAA-3) obtained in the comparative synthesis example, 12.80 g of (PAA-6), and 2.40 g of the NMP solution containing 1 wt% of (AD-1) were filtered, 8.80 g of NMP and 12.00 g of BCS were added, and stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-3).

(Examples 1-2) In a 50 mL Erlenmeyer flask with a stirrer, add 7.00 g of polyimide solution (SPI-1) and the grams of (PAA-6) and (PAA-7) obtained from the polymerization example shown in Table 1, filter 2.40 g of NMP solution containing 1 wt% of (AD-1) and 0.72 g of NMP solution containing 10 wt% of (AD-2), add 7.48 g of NMP and 12.00 g of BCS, and stir for 2 hours with a magnetic stirrer to obtain the liquid crystal alignment agent (B-1-2) shown in Table 1.

(Examples 3 to 6) In a 50 mL Erlenmeyer flask with a stirrer, add 4.00 g of polyamine solution (PAA-3) and the grams of polyamine solution (PAA-6 to 8) obtained from the polymerization example shown in Table 2, filter 2.40 g of NMP solution containing 1 wt% of (AD-1), add 4.80 g of NMP and 12.00 g of BCS, and stir for 2 hours using a magnetic stirrer to obtain the liquid crystal alignment agent (B-3 to 6) shown in Table 2.

(Examples 7-8) In a 50 mL Erlenmeyer flask with a stirrer, add 6.73 g of the polyamide solution (PAA-2) obtained in the comparative synthesis example, and the grams of the polyamide solutions (PAA-5) and (PAA-7) obtained in the polymerization example shown in Table 3, filter 2.40 g of NMP solution containing 1 wt% of (AD-1) and 0.72 g of NMP solution containing 10 wt% of (AD-2), add 2.88 g of NMP and 12.00 g of BCS, and stir for 2 hours with a magnetic stirrer to obtain a liquid crystal alignment agent (A-2).

[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 liquid crystal display element of IPS drive mode or FFS drive mode, and can quickly alleviate the residual charge accumulated by DC voltage, so as to produce an IPS drive mode or FFS drive mode liquid crystal display element with excellent afterimage characteristics. Therefore, it is particularly suitable as a liquid crystal alignment film for a liquid crystal display element or liquid crystal TV of IPS drive mode or FFS drive mode.

Claims (7)

A liquid crystal alignment agent, characterized by comprising: (A-1) a polyamide obtained by using a tetracarboxylic dianhydride component containing 3,3',4,4'-biphenyltetracarboxylic dianhydride and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from an imidized polymer of the polyamide; (A-2) a polyamide obtained by using a tetracarboxylic dianhydride component containing an aliphatic tetracarboxylic dianhydride and a diamine component containing a diamine represented by the following formula (2), and at least one polymer selected from an imidized polymer of the polyamide; (B) a polyimide precursor and an imidized polymer of the polyimide precursor (but a polymer different from either component (A-1) or component (A-2)); and an organic solvent;

In formula (2), _Y1 is a group represented by formula (YD-14) or formula (YD-18));

As in claim 1, the liquid crystal alignment agent, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component of the aforementioned (A-1) is the tetracarboxylic dianhydride represented by the aforementioned formula (1). As in claim 1, the liquid crystal alignment agent, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component (A-2) is aliphatic tetracarboxylic dianhydride. As in claim 1, the liquid crystal alignment agent, wherein 10 to 100 mol% of the diamine components of the aforementioned (A-1) and (A-2) are diamines of formula (2). As in claim 1, the liquid crystal alignment agent, wherein the aforementioned aliphatic tetracarboxylic dianhydride is bicyclo[3.3.0]octane 2,4,6,8-tetracarboxylic dianhydride. A liquid crystal alignment film, characterized in that the liquid crystal alignment agent of any one of claim 1 to claim 5 is applied and sintered. A liquid crystal display element, characterized by having a liquid crystal alignment film as claimed in claim 6.