CN107533259B - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

The liquid crystal aligning agent contains the following component (A) and component (B). Component (A): at least one polymer selected from polyimide precursors having a side chain for aligning liquid crystals vertically and a side chain having a radical generating site, and polyimides obtained by imidizing the polyimide precursors. Component (B): a polymer selected from a polyimide precursor obtained by using at least one diamine selected from the following and a polyimide obtained by imidizing the same, or a polymer selected from a polyimide precursor obtained by using at least one tetracarboxylic dianhydride selected from the following and a polyimide obtained by imidizing the same. The definition of the symbols in the formula is as described in the specification.

Description

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

Technical Field

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element which can be used in a vertical alignment type liquid crystal display element and the like produced by irradiating liquid crystal molecules with ultraviolet rays under voltage application.

Background Art

The manufacturing process of a liquid crystal display element in which liquid crystal molecules aligned vertically with respect to a substrate respond to an electric field (also referred to as a vertical alignment (VA) method) sometimes includes a step of irradiating the liquid crystal molecules with ultraviolet light while applying voltage.

For this type of vertically aligned liquid crystal display element, there is a known technology that adds a photopolymerizable compound to a liquid crystal composition in advance, uses a vertically aligned film such as a polyimide-based film, applies voltage to the liquid crystal unit while irradiating it with ultraviolet light, thereby accelerating the response speed of the liquid crystal (PSA (Polymer Sustained Alignment) element, for example, refer to Patent Document 1 and Non-Patent Document 1).

In the PSA type element, usually, the tilt direction of the liquid crystal molecules that respond to the electric field is controlled by protrusions provided on the substrate, slits provided on the display electrode, etc. It is said that by adding a photopolymerizable compound to the liquid crystal composition, a voltage is applied to the liquid crystal unit while irradiating ultraviolet rays, thereby forming a polymer structure that memorizes the tilt direction of the liquid crystal molecules on the liquid crystal orientation film. Therefore, compared with the method of controlling the tilt direction of the liquid crystal molecules only by using protrusions and slits, the response speed of the liquid crystal display element becomes faster.

On the other hand, in the PSA method liquid crystal display element, the unreacted polymerizable compound remaining in the liquid crystal becomes an impurity (contamination) in the liquid crystal, so there is also a problem of reducing the reliability of the liquid crystal display element. In addition, for the UV irradiation treatment required in the PSA method, if the irradiation amount is large, the components in the liquid crystal will decompose, resulting in reduced reliability.

Furthermore, it has been reported that the response speed of a liquid crystal display element becomes faster by adding a photopolymerizable compound to a liquid crystal aligning film instead of adding the photopolymerizable compound to a liquid crystal composition (SC-PVA type liquid crystal display, for example, refer to Non-Patent Document 2).

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2003-307720

Non-patent literature

Non-patent document 1: K. Hanaoka, SID 04 DIGEST, P. 1200-1202

Non-patent document 2: K.H Y.-J. Lee, SID 09 DIGEST, P.666-668

Summary of the invention

Problem that the invention aims to solve

In recent years, with the improvement of the quality of liquid crystal display elements, it is expected to further accelerate the response speed of liquid crystal to voltage application. To this end, it is necessary to efficiently react the polymerizable compound by irradiating with long-wavelength ultraviolet rays without decomposing the components in the liquid crystal, so as to exert the orientation fixation ability. Furthermore, it is required that no unreacted polymerizable compound remains after ultraviolet irradiation, and no adverse effect is caused on the reliability of the liquid crystal display element.

Moreover, it is also desired to make the electric characteristics of the obtained liquid crystal display element favorable, and in particular, make the direct current charge storage characteristics favorable.

The object of the present invention is to solve the problems of the above-mentioned prior art, and to provide a liquid crystal alignment agent, a liquid crystal alignment film, a liquid crystal display element and a method for manufacturing a liquid crystal display element, which can make a polymerizable compound react efficiently even under long-wavelength ultraviolet irradiation, thereby improving the response speed of a liquid crystal display element in a vertical alignment mode, and further making the electrical properties of the obtained liquid crystal display element, especially the DC charge accumulation properties, good.

Solutions for solving problems

The present inventors have conducted intensive studies and, as a result, have found that the above-mentioned problems can be achieved by introducing a specific structure that generates radicals by ultraviolet irradiation into a polymer constituting a liquid crystal aligning agent, thereby completing the present invention.

That is, the present invention has the following gist.

1. A liquid crystal aligning agent, comprising the following (A) component, (B) component and an organic solvent.

(A) Component: at least one polymer selected from a polyimide precursor having a side chain for vertically aligning liquid crystals and a side chain having a site for generating radicals upon ultraviolet irradiation represented by the following formula (I), and a polyimide obtained by imidizing the polyimide precursor.

R ₁ and R ₂ are each independently an alkyl group or an alkoxy group having 1 to 10 carbon atoms, T ₁ and T ₂ are each independently a single bond or a linking group of -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ )-, -CON(CH ₃ )-, or -N(CH ₃ )CO-, and S is a single bond or an alkylene group having 1 to 20 carbon atoms which is unsubstituted or substituted with a fluorine atom. In this case, -CH ₂ - or -CF ₂ - of the alkylene group may be arbitrarily replaced by -CH=CH-, and when the following arbitrary groups are not adjacent to each other, they may be arbitrarily replaced by the following groups: -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, a divalent carbocyclic ring, or a divalent heterocyclic ring, and Q represents a structure selected from the following.

R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

(B) component: a polymer selected from a polyimide precursor obtained by using as a raw material a diamine component containing at least one diamine selected from the following formulas (B-1) to (B-5), and a polyimide obtained by imidizing the polyimide precursor, or a polymer selected from a polyimide precursor obtained by using as a raw material a tetracarboxylic dianhydride component containing at least one tetracarboxylic dianhydride selected from the following formulas (3) and (4), and a polyimide obtained by imidizing the polyimide precursor.

_Y1 is a monovalent organic group having a secondary amine, a tertiary amine or a heterocyclic structure, and _Y2 is a divalent organic group having a secondary amine, a tertiary amine or a heterocyclic structure.

n and m are 0 or 1, and X and y are a single bond, a carbonyl group, an ester group, a phenylene group, or a sulfonyl group.

2. A liquid crystal alignment film, characterized in that it is obtained by applying the liquid crystal alignment agent described in 1 on a substrate and firing it.

3. A liquid crystal display element, characterized in that a liquid crystal layer is provided in contact with a liquid crystal alignment film obtained by applying the liquid crystal alignment agent described in 1 on a substrate and firing it, and ultraviolet rays are irradiated while applying voltage to the liquid crystal layer, thereby providing a liquid crystal unit.

4. A method for producing a liquid crystal display element, characterized in that a liquid crystal layer is provided in contact with a liquid crystal alignment film obtained by coating the liquid crystal alignment agent described in 1 on a substrate and firing it, and a voltage is applied to the liquid crystal layer while irradiating ultraviolet rays to produce a liquid crystal unit.

Effects of the Invention

According to the present invention, it is possible to provide a vertical alignment liquid crystal display element in which the response speed of liquid crystal is improved even by long-wavelength ultraviolet irradiation and the accumulation of direct current charges is small.

DETAILED DESCRIPTION

The liquid crystal aligning agent of this invention contains the following (A) component, (B) component, and an organic solvent.

(A) Component: at least one polymer selected from a polyimide precursor having a side chain for vertically aligning liquid crystals and a side chain having a site for generating radicals upon ultraviolet irradiation represented by the following formula (I), and a polyimide obtained by imidizing the polyimide precursor.

(B) component: a polymer selected from a polyimide precursor obtained by using at least one diamine selected from the following formulas (B-1) to (B-5) as a raw material, and a polyimide obtained by imidizing the polyimide precursor, or a polymer selected from a polyimide precursor obtained by using at least one tetracarboxylic dianhydride selected from the following formulas (3) and (4) as a raw material, and a polyimide obtained by imidizing the polyimide precursor.

The liquid crystal aligning agent refers to a solution for forming a liquid crystal aligning film, and the liquid crystal aligning film refers to a film for aligning liquid crystals in a predetermined direction.

Hereinafter, each constituent element will be described in detail.

<(A) Ingredients>

The liquid crystal aligning agent of the present invention is at least one polymer selected from a polyimide precursor having a side chain for vertically aligning a liquid crystal and a side chain having a site for generating radicals upon ultraviolet irradiation represented by the above formula (1), and a polyimide obtained by imidizing the polyimide precursor.

Here, the polyimide precursor refers to a polyamic acid and a polyamic acid ester.

<Side chains that generate free radicals due to ultraviolet irradiation>

The component (A) contained in the liquid crystal aligning agent of the present invention has a site that generates radicals by ultraviolet irradiation as a side chain. The site that generates radicals by ultraviolet irradiation can be represented by the following formula (I).

In the above formula (I), Ar bonded to the carbonyl group interferes with the absorption wavelength of ultraviolet rays, so in the case of a longer wavelength, it is preferably a structure with a long conjugated length such as naphthylene and biphenylene. In addition, Ar may be optionally substituted with a substituent, and the substituent is preferably an electron-donating organic group such as an alkyl group, a hydroxyl group, an alkoxy group, an amino group, etc.

When Ar is a structure such as a naphthylene group or a biphenylene group, the solubility is poor and the difficulty of synthesis is increased. When the wavelength of ultraviolet rays is in the range of 250 nm to 380 nm, sufficient characteristics can be obtained even with a phenyl group, so a phenyl group is most preferred.

Furthermore, R ₁ and R ₂ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group, a benzyl group, or a phenethyl group. In the case of an alkyl group or an alkoxy group, R ₁ and R ₂ may form a ring.

Q is preferably an electron-donating organic group, and is preferably as follows.

(R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ₃ represents -CH ₂ -, -NR-, -O-, or -S-.)

When Q is represented by -OR, R is preferably an alkyl group having 1 to 4 carbon atoms for the purpose of increasing the surface presence rate of component (A) after coating. This is because by making R an alkyl group, the polarity becomes low and it is easy to move to the surface. Furthermore, considering the ease of synthesis, etc., it is preferably 1 to 2, and most preferably 1.

When Q is an amino group derivative, there is a possibility that problems such as salt formation between the generated carboxylic acid group and the amino group may occur during polymerization of the polyamic acid as a precursor of the polyimide. Therefore, a hydroxyl group or an alkoxy group is more preferably used.

When it is desired to introduce the structure of the above formula (I) into a side chain using a polyimide precursor and/or a polyimide as a polymer containing a liquid crystal aligning agent, it is preferred to use the side chain structure of the above formula (I) from the viewpoint of the handleability of the raw material and the ease of synthesis of the polymer.

The site where free radicals are generated by ultraviolet irradiation in the above formula (I) is preferably as follows. In particular, from the viewpoint of the reliability of the obtained liquid crystal display element, (b), (c) or (d) is preferred, and from the viewpoint of the surface existence rate of the free radical generating site on the surface of the liquid crystal alignment film, (d) is more preferred.

It should be noted that -T ₁ -ST ₂ - has the function of a linking group that connects diaminobenzene to a site where free radicals are generated by ultraviolet irradiation. T ₁ and T ₂ are independently single bonds, -O-, -S-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ )-, -CON(CH 3 )-, or -N(CH ₃ )CO-. S is a single bond or an alkylene group having 1 to 20 carbon atoms which is optionally substituted with a fluorine atom (wherein -CH ₂ - or -CF ₂ - of the alkylene group is optionally substituted with -CH=CH-, and when any of the following groups are not adjacent to each other, they are optionally _substituted with these groups: -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, a divalent carbocyclic ring or a heterocyclic ring.). In particular, from the viewpoint of ease of synthesis, T ₂ is most preferably -O-. Furthermore, S is preferably an alkylene group having 2 to 10, more preferably 4 to 8, from the viewpoint of ease of synthesis and solubility.

<Side Chains for Vertically Aligning Liquid Crystals>

The polymer contained in the liquid crystal aligning agent of the present invention preferably has a side chain that vertically aligns the liquid crystal in addition to the side chain represented by the above formula (I). The side chain that vertically aligns the liquid crystal is represented by the following formula [II-1] or formula [II-2].

X ¹ , X ² , X ³ , X ⁴ , X ⁵ , and n in formula [II-1] are as defined above.

Among them, ^X1 is preferably a single bond, -( _CH2 ) _a- (a is an integer of 1 to 15), -O-, _-CH2O- or -COO-, and more preferably a single bond, -( _CH2 ) _a- (a is an integer of 1 to 10), -O-, _-CH2O- or -COO-, from the viewpoint of availability of raw materials and ease of synthesis. Among them, ^X2 is preferably a single bond or ( _CH2 ) _b- (b is an integer of 1 to 10). ^X3 is preferably a single bond, -( _CH2 ) _c- (c is an integer of 1 to 15), -O-, _-CH2O- or -COO-, and more preferably a single bond, -( _CH2 ) _c- (c is an integer of 1 to 10), -O-, _-CH2O- or -COO-, from the viewpoint of ease of synthesis.

Among them, ^X4 is preferably a benzene ring, a cyclohexane ring or an organic group having 17 to 51 carbon atoms and having a steroid skeleton from the viewpoint of ease of synthesis. ^X5 is particularly preferably a benzene ring or a cyclohexane ring. n is preferably 0 to 3, more preferably 0 to 2, from the viewpoint of availability of raw materials and ease of synthesis.

^X6 is particularly preferably an alkyl group having 1 to 18 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluorinated alkoxy group having 1 to 10 carbon atoms. It is more preferably an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. It is particularly preferably an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms.

Preferred combinations of X ¹ , X ² , X ³ , X ⁴ , X ⁵ , X ⁶ and n in formula [II-1] include the same combinations as (2-1) to (2-629) described in Tables 6 to 47 on pages 13 to 34 of International Publication WO 2011/132751 (published on October 27, 2011). In addition, in each table of the International Publication, X ¹ to X ⁶ in the present invention are shown as Y 1 to Y 6, but Y 1 to Y 6 can be understood as X ¹ to X ⁶ .

In addition, in (2-605) to (2-629) described in each table of the international publication, the organic group having 17 to 51 carbon atoms in the steroid skeleton of the present invention is shown as an organic group having 12 to 25 carbon atoms in the steroid skeleton, but the organic group having 12 to 25 carbon atoms in the steroid skeleton can be understood as an organic group having 17 to 51 carbon atoms in the steroid skeleton. Among them, the combination of (2-25) to (2-96), (2-145) to (2-168), (2-217) to (2-240), (2-268) to (2-315), (2-364) to (2-387), (2-436) to (2-483), or (2-603) to (2-615) is preferred. Particularly preferred combinations are (2-49) to (2-96), (2-145) to (2-168), (2-217) to (2-240), (2-603) to (2-606), (2-607) to (2-609), (2-611), (2-612) or (2-624).

-X ⁷ -X ⁸ [II-2]

In formula [II-2], ^X7 and ^X8 are as defined above. ^X7 is preferably a single bond, -O-, _-CH2O- , -CONH-, -CON( _CH3 )- or -COO-, and more preferably a single bond, -O-, -CONH- or -COO-. ^X8 is particularly preferably an alkyl group having 8 to 18 carbon atoms.

As the side chain for vertically aligning a liquid crystal, it is preferable to use a structure represented by formula [II-1] from the viewpoint of obtaining high and stable vertical alignment of the liquid crystal.

It should be noted that the ability of a polymer having a side chain that orients a liquid crystal vertically to orientate a liquid crystal vertically varies depending on the structure of the side chain that orients the liquid crystal vertically. Generally, if the amount of the side chain that orients the liquid crystal vertically increases, the ability to orient the liquid crystal vertically increases, and if it decreases, the ability to orient the liquid crystal vertically decreases. In addition, when having a cyclic structure, there is a tendency for the ability to orient the liquid crystal vertically to be higher than when not having a cyclic structure.

<Photoreactive side chain>

The component (A) contained in the liquid crystal aligning agent of the present invention may have a photoreactive side chain in addition to the side chain represented by the above formula (I). The photoreactive side chain has a functional group (hereinafter also referred to as a photoreactive group) that can react and form a covalent bond by irradiation with light such as ultraviolet light (UV).

The photoreactive side chain may be directly bonded to the main chain of the polymer or may be bonded via a linking group. The photoreactive side chain is represented by the following formula (III), for example.

-R ⁸ -R ⁹ -R ¹⁰ [III]

In formula (III), R ⁸ , R ⁹ and R ¹⁰ are as defined above. Among them, R ⁸ is preferably a single bond, -O-, -COO-, -NHCO-, or -CONH-. R ⁹ can be formed by a common organic synthesis method, and is preferably a single bond or an alkylene group having 1 to 12 carbon atoms from the viewpoint of ease of synthesis.

In addition, specific examples of the divalent carbocyclic or heterocyclic ring replacing any -CH ₂ - in R ⁹ include the following groups.

From the viewpoint of photoreactivity, R ¹⁰ is preferably a methacryloyl group, an acryloyl group, a vinyl group or a styryl group.

The amount of photoreactive side chains present is preferably within a range capable of increasing the response speed of liquid crystals by reacting with ultraviolet rays to form covalent bonds. To further increase the response speed of liquid crystals, it is preferably as much as possible without affecting other properties.

<Specific diamine>

The diamine (hereinafter also referred to as specific diamine) used for production of the above polymer forming the liquid crystal aligning agent of the present invention has a site which is decomposed by ultraviolet irradiation and generates radicals as a side chain.

In the above formula (1), Ar, R ₁ , R ₂ , T ₁ , T ₂ , and Sn are as defined above.

The diaminobenzene in the formula (1) may be any structure of o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine, and is preferably m-phenylenediamine or p-phenylenediamine from the viewpoint of reactivity with an acid dianhydride.

As the specific diamine, a structure represented by the following formula is most preferred from the viewpoints of ease of synthesis, high versatility, properties, etc. In addition, in the formula, n is an integer of 2 to 8.

<Synthesis of specific diamine>

In the present invention, the specific diamine can be obtained by synthesizing a dinitro compound, a mononitro compound having an amino group to which a protective group that can be removed by a reduction step, or a diamine through various steps, and converting the nitro group to an amino group or deprotecting the protective group by a commonly used reduction reaction.

There are various methods for synthesizing a diamine precursor, and for example, the following method is shown: a site that generates free radicals by ultraviolet irradiation is synthesized, a spacer site is introduced, and then a bond is made with dinitrobenzene. In the formula, n is an integer of 2 to 8.

In the case of the above reaction, a substance having two hydroxyl groups is used, and selective synthesis can be achieved by optimizing the type of base (catalyst) and the feed ratio.

The base used is not particularly limited, but is preferably an inorganic base such as potassium carbonate, sodium carbonate, cesium carbonate, or the like, or an organic base such as pyridine, dimethylaminopyridine, trimethylamine, triethylamine, tributylamine, or the like.

The method for reducing the dinitro compound as a diamine precursor is not particularly limited, and generally, there is a method of using palladium carbon, platinum oxide, Raney nickel, platinum carbon, rhodium-alumina, platinum sulfide carbon, etc. as a catalyst, and reducing it with hydrogen, hydrazine, hydrogen chloride, etc. in a solvent such as ethyl acetate, toluene, tetrahydrofuran, dioxane, alcohol, etc. An autoclave or the like may be used as needed.

On the other hand, when the structure contains an unsaturated bond site, if palladium carbon, platinum carbon, etc. are used, there is a concern that the unsaturated bond site may be reduced to form a saturated bond. Therefore, as preferred conditions, it is preferred to use a reduction condition using a transition metal such as reduced iron and/or tin, tin chloride, etc., a poisoned palladium carbon and/or platinum carbon, platinum carbon doped with iron, etc. as a catalyst.

In addition, the diamine of the present invention can be obtained by deprotecting a diaminobenzene derivative protected with a benzyl group or the like in the same manner through the above-mentioned reduction step.

The specific diamine is preferably used in an amount of preferably 10 to 80 mol %, more preferably 20 to 60 mol %, particularly preferably 30 to 50 mol % of the diamine component used for synthesis of the polyamic acid.

<Diamine Having a Side Chain for Vertically Aligning Liquid Crystals>

Regarding the method of introducing a side chain that vertically aligns a liquid crystal into a polyimide polymer, it is preferable to use a diamine having a specific side chain structure as part of the diamine component. In particular, it is preferable to use a diamine represented by the following formula [2] (also referred to as a specific side chain type diamine compound).

In formula [2], X represents the structure represented by the above formula [II-1] or formula [II-2], and n represents an integer of 1 to 4, and is particularly preferably 1.

As the specific side chain type diamine, it is preferable to use a diamine represented by the following formula [2-1] from the viewpoint of obtaining high and stable vertical alignment of liquid crystals.

X ¹ , X ² , X ³ , X ⁴ , X ⁵ , and n in the above formula [2-1] have the same definitions as in the above formula [II-1], and preferred embodiments thereof also have the same definitions as in the above formula [II-1].

In addition, in formula [2-1], m is an integer of 1 to 4. Preferably, it is an integer of 1.

As a specific side chain type diamine, the structure shown by following formula [2a-1] - formula [2a-31] is mentioned specifically, for example.

( ^R1 represents -O-, _-OCH2- , _-CH2O- , _-COOCH2- or _-CH2OCO- , and R2 represents a linear or branched alkyl group having 1 to 22 carbon atoms, a linear or branched alkoxy group having 1 to 22 carbon atoms, or a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 22 carbon atoms. ⁾

(R ³ represents -COO-, -OCO-, -CONH-, -NHCO-, -COOCH ₂ -, -CH ₂ OCO-, -CH ₂ O-, -OCH ₂ - or -CH ₂ -, and R ⁴ represents a linear or branched alkyl group having 1 to 22 carbon atoms, a linear or branched alkoxy group having 1 to 22 carbon atoms, or a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 22 carbon atoms).

( ^R5 represents -COO-, -OCO-, -CONH-, -NHCO-, _-COOCH2- , _-CH2OCO- , _-CH2O- , _-OCH2- , _-CH2- , -O- or -NH-, and ^R6 represents fluoro, cyano, trifluoromethane, nitro, azo, formyl, acetyl, acetoxy or hydroxy).

( ^R7 is a linear or branched alkyl group having 3 to 12 carbon atoms, and the cis and trans isomers of 1,4-cyclohexylene are respectively trans isomers).

( ^R8 is a linear or branched alkyl group having 3 to 12 carbon atoms, and the cis and trans isomers of 1,4-cyclohexylene are respectively trans isomers).

( _A4 is a linear or branched alkyl group having 3 to 20 carbon atoms which may be substituted with a fluorine atom, _A3 is a 1,4-cyclohexylene group or a 1,4-phenylene group, _A2 is an oxygen atom or COO-* (wherein the bond with "*" is bonded to _A3 ), and _A1 is an oxygen atom or COO-* (wherein the bond with "*" is bonded to ( _CH2 ) _a2 ). In addition, _a1 is an integer of 0 or 1, _a2 is an integer of 2 to 10, and _a3 is an integer of 0 or 1).

Among the above formulas [2a-1] to [2a-31], formulas [2a-1] to [2a-6], formulas [2a-9] to [2a-13], or formulas [2a-22] to [2a-31] are particularly preferred.

Moreover, as a diamine which has the specific side chain structure represented by said formula [II-2], the diamine represented by the following formula [2b-1] - [2b-10] is mentioned.

( ^A1 represents an alkyl group having 1 to 22 carbon atoms or a fluorine-containing alkyl group).

In the above formulas [2b-5] to [2b-10], ^A1 represents -COO-, -OCO-, -CONH-, -NHCO-, _-CH2- , -O-, -CO- or -NH-, and ^A2 represents a linear or branched alkyl group having 1 to 22 carbon atoms or a linear or branched fluorinated alkyl group having 1 to 22 carbon atoms.

The above-mentioned diamines may be used alone or in combination of two or more thereof depending on the liquid crystal orientation, pretilt angle, voltage holding characteristics, stored charge and other characteristics when used as a liquid crystal alignment film.

The diamine having a side chain for vertically aligning a liquid crystal is preferably used in an amount of 5 to 50 mol %, more preferably 10 to 40 mol %, and particularly preferably 15 to 30 mol % of the diamine component used for synthesis of the polyamic acid.

When a diamine having a side chain that orients a liquid crystal vertically is used, it is particularly excellent in terms of improvement of the response speed and the ability to fix the orientation of the liquid crystal.

<Diamine containing a photoreactive side chain>

Examples of the diamine having a photoreactive side chain include diamines having a side chain represented by formula (3). Specifically, diamines represented by the following general formula (3) are exemplified, but the diamines are not limited thereto.

(R ⁸ , R ⁹ and R ¹⁰ in formula (3) have the same meanings as in the above formula (III).)

The bonding positions of the two amino groups (-NH ₂ ) in formula (3) are not limited. Specifically, the bonding positions of the two amino groups (-NH 2 ) on the benzene ring relative to the connecting group of the side chain are 2,3, 2,4, 2,5, 2,6, 3,4, and 3,5. Among them, from the viewpoint of reactivity during synthesis of polyamic acid, the bonding positions 2,4, 2,5, or 3,5 are preferred. In consideration of the ease of synthesis of diamine, the bonding positions 2,4 or 3,5 are more preferred.

Specific examples of the diamine having a photoreactive side chain include the following diamines.

(X ⁹ and X ¹⁰ each independently represent a linking group belonging to a single bond, -O-, -COO-, -NHCO-, or -NH-, and Y represents an alkylene group having 1 to 20 carbon atoms which may be substituted with a fluorine atom.)

Examples of the diamine having a photoreactive side chain include diamines represented by the following formulas, which have a group that undergoes a photodimerization reaction and a group that undergoes a photopolymerization reaction in a side chain.

In the above formula, _Y1 represents _-CH2- , -O-, -CONH-, -NHCO-, -COO-, -OCO-, -NH-, or -CO-. _Y2 represents an alkylene group having 1 to 30 carbon atoms, a divalent carbocyclic ring or a heterocyclic ring, and one or more hydrogen atoms of the alkylene group, the divalent carbocyclic ring or the heterocyclic ring are optionally substituted with a fluorine atom or an organic group. When the following groups are not adjacent to each other, _-CH2- is optionally replaced with these groups: -O-, -NHCO-, -CONH-, -COO-, -OCO-, -NH-, -NHCONH-, -CO-. _Y3 represents _-CH2- , -O-, -CONH-, -NHCO-, -COO-, -OCO-, -NH-, -CO-, or a single bond. _Y4 represents a _cinnamoyl group. _Y5 is a single bond, an alkylene group having 1 to 30 carbon atoms, a divalent carbocyclic ring or a heterocyclic ring, wherein one or more hydrogen atoms of the alkylene group, the divalent carbocyclic ring or the heterocyclic ring may be substituted with a fluorine atom or an organic group. When the following groups are not adjacent to each other, _-CH2- may be replaced with the following groups: -O-, -NHCO-, -CONH-, -COO-, -OCO-, -NH-, -NHCONH-, -CO-. _Y6 represents a photopolymerizable group which is an acryloyl group or _a methacryloyl group.

Specific examples of the diamine having a photodimerization-reactive group and a photopolymerization-reactive group in a side chain include the following diamines, but the diamines are not limited to these.

The diamines may be used alone or in combination of two or more depending on the liquid crystal orientation, pretilt angle, voltage holding characteristics, stored charge and other characteristics when used as a liquid crystal alignment film, the response speed of liquid crystal when used as a liquid crystal display element, and the like.

The diamine having a photoreactive side chain is preferably used in an amount of 10 to 70 mol %, more preferably 20 to 60 mol %, and particularly preferably 30 to 50 mol % of the diamine component used for synthesis of the polyamic acid.

<Other diamines>

It should be noted that, when manufacturing the polyimide precursor and/or the polyimide, other diamines other than the above diamines may be used in combination as the diamine component as long as the effect of the present invention is not impaired. Specifically, for example, p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,5-diaminophenol, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4, 4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dicarboxy-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-biphenyl, 3,3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diamino Biphenyl, 2,2’-diaminobiphenyl, 2,3’-diaminobiphenyl, 4,4’-diaminodiphenylmethane, 3,3’-diaminodiphenylmethane, 3,4’-diaminodiphenylmethane, 2,2’-diaminodiphenylmethane, 2,3’-diaminodiphenylmethane, 4,4’-diaminodiphenyl ether, 3,3’-diaminodiphenyl ether, 3,4’-diaminodiphenyl ether, 2,2’-diaminodiphenyl ether , 2,3'-diaminodiphenyl ether, 4,4'-sulfonyl diphenylamine, 3,3'-sulfonyl diphenylamine, bis(4-aminophenyl)silane, bis(3-aminophenyl)silane, dimethyl-bis(4-aminophenyl)silane, dimethyl-bis(3-aminophenyl)silane, 4,4'-thiodiphenylamine, 3,3'-thiodiphenylamine, 4,4'-diaminodiphenylamine, 3,3'-diaminodiphenylamine, 3,4' -diaminodiphenylamine, 2,2'-diaminodiphenylamine, 2,3'-diaminodiphenylamine, N-methyl(4,4'-diaminodiphenyl)amine, N-methyl(3,3'-diaminodiphenyl)amine, N-methyl(3,4'-diaminodiphenyl)amine, N-methyl(2,2'-diaminodiphenyl)amine, N-methyl(2,3'-diaminodiphenyl)amine, 4,4'-diaminobenzophenone, 3,3 '-Diaminobenzophenone, 3,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2,2'-diaminobenzophenone, 2,3'-diaminobenzophenone, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 1,2-bis(4-aminophenyl)ethane, 1 ,2-bis(3-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,3-bis(3-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(3-aminophenyl)butane, bis(3,5-diethyl-4-aminophenyl)methane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-[1,4-phenylenebismethylene]diphenylamine, 4,4'-[1,3-phenylenebismethylene]diphenylamine, 3,4'-[1,4-phenylenebismethylene]diphenylamine, 3,4'-[1,3-phenylenebismethylene]diphenylamine, 3,3'-[1,4-phenylene 1,4-phenylenebis[(4-aminophenyl) ketone], 1,4-phenylenebis[(3-aminophenyl) ketone], 1,3-phenylenebis[(4-aminophenyl) ketone], 1,3-phenylenebis[(3-aminophenyl) ketone], 1,4-phenylenebis(4-aminobenzoate), 1,4-phenylenebis(3-aminobenzoate), 1,3-phenylenebis(4-aminobenzoate), 1,3-phenylenebis(3-aminobenzoate), bis(4-aminophenyl) terephthalate, bis(3-aminophenyl) terephthalate, bis(4-aminophenyl) isophthalate, bis(3-aminophenyl) isophthalate, N,N'-(1,4-phenylene)bis(4-aminobenzamide), N,N'-(1,3 -phenylene)bis(4-aminobenzamide), N,N'-(1,4-phenylene)bis(3-aminobenzamide), N,N'-(1,3-phenylene)bis(3-aminobenzamide), N,N'-bis(4-aminophenyl)terephthalamide, N,N'-bis(3-aminophenyl)terephthalamide, N,N'-bis(4-aminophenyl)isophthalamide, N,N'-bis(3-aminophenyl) Isophthalamide, 9,10-bis(4-aminophenyl)anthracene, 4,4'-bis(4-aminophenoxy)diphenyl sulfone, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(3-aminophenyl)hexafluoropropane, 2,2'-bis(3-aminophenyl)hexafluoropropane 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(3-aminophenyl)propane, 2,2'-bis(3-amino-4-methylphenyl)propane, 3,5-diaminobenzoic acid, 2,5-diaminobenzoic acid, 1,3-bis(4-aminophenoxy)propane, 1,3-bis(3-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,4-bis(3-aminophenoxy)butane 1,5-bis(4-aminophenoxy)pentane, 1,5-bis(3-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 1,6-bis(3-aminophenoxy)hexane, 1,7-bis(4-aminophenoxy)heptane, 1,7-(3-aminophenoxy)heptane, 1,8-bis(4-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,6-bis(4-aminophenoxy)hexane, 1,7-bis(3-aminophenoxy)heptane, 1,8-bis(4-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,6-bis(3-aminophenoxy)hexane, 1,7-bis(4-aminophenoxy)heptane, 1,8-bis(3-aminophenoxy)octane, 1,8-bis(4-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,8-bis(4-aminophenoxy)hexane, 1,8-bis(3 ...hexane, 1,8 9-bis(4-aminophenoxy)nonane, 1,9-bis(3-aminophenoxy)nonane, 1,10-(4-aminophenoxy)decane, 1,10-(3-aminophenoxy)decane, 1,11-(4-aminophenoxy)undecane, 1,11-(3-aminophenoxy)undecane, 1,12-(4-aminophenoxy)dodecane, 1,12-(3-aminophenoxy)dodecane and other aromatic diamines, bis( aliphatic diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane and 1,12-diaminododecane.

The above other diamines may be used alone or in combination of two or more depending on the liquid crystal orientation, pretilt angle, voltage holding characteristics, stored charge and other characteristics when used as a liquid crystal alignment film.

<Tetracarboxylic dianhydride>

The tetracarboxylic dianhydride component reacting with the above-mentioned diamine component is not particularly limited. Specifically, pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4-biphenyltetracarboxylic acid, bis(3,4-dicarboxyphenyl)ether, 3,3',4,4'-benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl)sulfone, bis(3,4-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl)propane, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane alkane, bis(3,4-dicarboxyphenyl)dimethylsilane, bis(3,4-dicarboxyphenyl)diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis(3,4-dicarboxyphenyl)pyridine, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid, 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic acid, oxydiphthalic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2-dimethyl-1,2,3,4-cyclobutane alkanetetracarboxylic acid, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cycloheptanetetracarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, 3,4-dicarboxy-1-cyclohexylsuccinic acid, 2,3,5-tricarboxycyclopentylacetic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid, bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic acid, bicyclo[4,3,0]nonane-2,4,7,9-tetracarboxylic acid, bicyclo[4,4,0]decane-2,4,7,9-tetracarboxylic acid, bicyclo[4,4,0]decane-2,4,8,10-tetracarboxylic acid, tricyclo[6,3,0] Tetracarboxylic acid dianhydrides such as 4-(2,5-dioxatetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid, 5-(2,5-dioxatetrahydrofuran-3-yl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid, tetracyclo[6,2,1,1,0,2,7]dodecane-4,5,9,10-tetracarboxylic acid, 3,5,6-tricarboxynorbornane-2:3,5:6 dicarboxylic acid, and 1,2,4,5-cyclohexanetetracarboxylic acid. Of course, tetracarboxylic dianhydride may be used alone or in combination of two or more kinds depending on the liquid crystal orientation, voltage holding characteristics, stored charge and other characteristics when used as a liquid crystal alignment film.

<(B) Component>

As the (B) component, the liquid crystal aligning agent of the present invention contains: a polymer selected from a polyimide precursor obtained by using a diamine component containing at least one diamine selected from the following formulas (B-1) to (B-5) as a raw material, and a polyimide obtained by imidizing the polyimide precursor, or a polymer selected from a polyimide precursor obtained by reacting a tetracarboxylic dianhydride component containing at least one tetracarboxylic dianhydride selected from the following formulas (3) and (4) with a diamine, and a polyimide obtained by imidizing the polyimide precursor.

When at least one tetracarboxylic dianhydride selected from the above formulas (3) and (4) is used as a raw material, the accumulated charge characteristics can be improved, possibly due to interaction between the [liquid crystal-aligned film] by light irradiation. As tetracarboxylic dianhydride represented by the chemical formula selected from the above formulas (3) and (4), the following compounds can be listed, but are not limited to these.

The at least one tetracarboxylic dianhydride selected from the above formulae (1-1) to (1-4) is preferably used in an amount of 10 to 100%, more preferably 10 to 60%, of the tetracarboxylic dianhydride component used in the synthesis of the component (B) of the polyamic acid.

Furthermore, as long as the effects of the present invention are not impaired, tetracarboxylic dianhydrides other than those of the formulae (1-1) to (1-4) may be used as a raw material for the component (B). Specific examples include the tetracarboxylic dianhydrides described for the component (A), but are not limited thereto.

For example, when tetracarboxylic dianhydride having an aliphatic group or an alicyclic group is also used as a raw material, it is preferably used in an amount of 0 to 90% of the tetracarboxylic dianhydride component used for synthesis of the component (B) of the polyamic acid.

When at least one tetracarboxylic dianhydride selected from the above formulas (1-1) to (1-4) is used in the component (B), the diamine component to be reacted is not particularly limited. Specific examples thereof include the diamines listed in the component (A). When at least one diamine selected from the above formulas (B-1) to (B-5) is used, it is preferred from the viewpoint of charge accumulation characteristics.

The polymer as the component (B) may be a polymer selected from a polyimide precursor obtained using as a raw material a diamine component containing at least one diamine selected from the following formulas (B-1) to (B-5), and a polyimide obtained by imidating the polyimide precursor.

(In the formula, _Y1 represents a monovalent organic group having a secondary amine, a tertiary amine or a heterocyclic structure, and _Y2 represents a divalent organic group having a secondary amine, a tertiary amine or a heterocyclic structure.)

By using at least one diamine having a specific structure with high polarity selected from the above formulas (B-1) to (B-5), or further using at least one diamine having a carboxyl group and a diamine having a nitrogen-containing aromatic heterocycle in combination, charge transfer is promoted by electrostatic interaction such as salt formation and hydrogen bonding, thereby improving the charge accumulation characteristics. As at least one diamine selected from the above formulas (B-1) to (B-5), the following diamines can be listed, but are not limited to these.

Furthermore, the polymer as the component (B) may also be made of the diamine having a side chain for vertically aligning a liquid crystal used in the component (A).

The at least one diamine selected from the above formulae (B-1) to (B-5) is preferably used in an amount of 10 to 80 mol% of the diamine component used for synthesis of the component (B) of the polyamic acid.

When at least one diamine selected from the above formulas (B-1) to (B-5) is used, the tetracarboxylic dianhydride component to be reacted is not particularly limited. Specific examples thereof include the tetracarboxylic dianhydrides listed in the component (A). When at least one tetracarboxylic dianhydride selected from the above formulas (3) and (4) is used, it is preferred from the viewpoint of reducing accumulated charge.

<Polymerizable Compound>

The liquid crystal alignment agent of the present invention may also contain a polymerizable compound having a group that can undergo photopolymerization or photocrosslinking at two or more ends as required. The polymerizable compound is a compound having two or more ends having a group that can undergo photopolymerization or photocrosslinking. Here, the polymerizable compound having a group that can undergo photopolymerization refers to a compound having a functional group that can undergo polymerization by irradiating light. In addition, the compound having a group that can undergo photocrosslinking refers to a compound having a functional group that can undergo crosslinking by reacting with a polymer of a polymerizable compound, a polyimide precursor, and at least one polymer selected from the polyimide obtained by imidizing the polyimide precursor by irradiating light. It should be noted that the compound having a group that can undergo photocrosslinking and the compound having a group that can undergo photocrosslinking will also react with each other.

By using the liquid crystal alignment agent of the present invention containing the above-mentioned polymerizable compound in a liquid crystal display element of a vertical alignment mode such as a SC-PVA type liquid crystal display, the response speed can be significantly improved compared to the case where a polymer having side chains and photoreactive side chains for vertically aligning the liquid crystal and the polymerizable compound are used alone, and the response speed can be sufficiently improved even with a small amount of polymerizable compound added.

Examples of the group that can be photopolymerized or photocrosslinked include a monovalent group represented by the following formula (IV).

( ^R12 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ^Z1 represents a divalent aromatic ring or heterocyclic ring optionally substituted with an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. ^Z2 represents a monovalent aromatic ring or heterocyclic ring optionally substituted with an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms.)

Specific examples of polymerizable compounds include a compound having photopolymerizable groups at both ends as represented by the following formula (V), a compound having an end having a photopolymerizable group and an end having a photocrosslinkable group as represented by the following formula (VI), and a compound having photocrosslinkable groups at both ends as represented by the following formula (VII).

It should be noted that in the following formulas (V) to (VII), ^R12 , ^Z1 and ^Z2 _are the same as ^R12 , ^Z1 and ^Z2 in the above formula (IV), and ^Q1 is a divalent organic group. ^Q1 preferably has a ring structure such as phenylene ( _-C6H4- ), biphenylene (-C6H4- _{C6H4- )} , cyclohexylene ( _-C6H10- ), _etc. This _is because the interaction with the liquid crystal _is likely to be increased.

Specific examples of the polymerizable compound represented by formula (V) include polymerizable compounds represented by the following formula (4). In the following formula (4), V and W are single bonds or represented by -R ¹ O-, where R ¹ is a linear or branched alkylene group having 1 to 10 carbon atoms, preferably represented by -R ¹ O-, where R ¹ is a linear or branched alkylene group having 2 to 6 carbon atoms. It should be noted that V and W may be the same or different, but synthesis is easy when they are the same.

It should be noted that even if the polymerizable compound has an acrylate group or a methacrylate group other than an α-methylene-γ-butyrolactone group as a group that can be photopolymerized or photocrosslinked, the polymerizable compound having a structure in which the acrylate group or the methacrylate group is bonded to a phenylene group via a spacer group such as an oxyalkylene group can significantly improve the response speed, similarly to the polymerizable compound having α-methylene-γ-butyrolactone groups at both ends. In addition, the polymerizable compound having a structure in which the acrylate group or the methacrylate group is bonded to a phenylene group via a spacer group such as an oxyalkylene group has improved thermal stability and can fully withstand high temperatures, for example, calcination temperatures of 200° C. or higher.

<Synthesis of Polyamic Acid>

When polyamic acid is obtained by the reaction of a diamine component and tetracarboxylic dianhydride, a known synthesis method can be used. There is usually a method in which a diamine component and a tetracarboxylic dianhydride component are reacted in an organic solvent. The reaction of a diamine component and a tetracarboxylic dianhydride is easier to carry out in an organic solvent and does not produce by-products, which is advantageous.

As the organic solvent used in the above-mentioned reaction, as long as the generated polyamic acid can be dissolved, there is no particular limitation. And then, even if it is an organic solvent that does not dissolve polyamic acid, within the range that the generated polyamic acid can not be precipitated, it can also be mixed with the above-mentioned solvent for use. It should be noted that the moisture in the organic solvent can suppress the polymerization reaction, and then cause the generated polyamic acid to be hydrolyzed, therefore, the organic solvent is preferably used after dehydration and drying.

Examples of the organic solvent used in the above reaction include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropaneamide, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, isopropyl alcohol, methoxymethyl 1-Amyl Alcohol, Dipentene, Ethyl Amyl Ketone, Methyl Nonyl Ketone, Methyl Ethyl Ketone, Methyl Isoamyl Ketone, Methyl Isopropyl Ketone, Methyl Cellosolve, Ethyl Cellosolve, Methyl Cellosolve Acetate, Butyl Cellosolve Acetate, Ethyl Cellosolve Acetate, Butyl Carbitol, Ethyl Carbitol, Ethyl Glycol, Ethylene Glycol Monoacetate, Ethylene Glycol Monoisopropyl Ether, Ethylene Glycol Monobutyl Ether, Propylene Glycol, Propylene Glycol Monoacetate, Propylene Glycol Monomethyl Ether, Propylene Glycol Monobutyl Ether, Propylene Glycol Tert-Butyl Ether, Dipropylene Glycol Monomethyl Ether, Propylene Glycol Monomethyl Ether Acetate, Diethylene Glycol, Diethylene Glycol alcohol monoacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, 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 monoethyl acetate, methyl glutarate, ethyl glutarate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diethylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, 2-ethyl-1-hexanol, etc. These organic solvents can be used alone or in combination.

The method of reacting the diamine component and the tetracarboxylic dianhydride component in an organic solvent may be any of the following methods: stirring a solution obtained by dispersing or dissolving the diamine component in an organic solvent, and directly adding the tetracarboxylic dianhydride component or dispersing or dissolving the tetracarboxylic dianhydride component in an organic solvent before adding the tetracarboxylic dianhydride component; conversely, adding the diamine component to a solution obtained by dispersing or dissolving the tetracarboxylic dianhydride component in an organic solvent; alternately adding the tetracarboxylic dianhydride component and the diamine component, etc. In addition, when the diamine component or the tetracarboxylic dianhydride component is composed of a plurality of compounds, the reaction may be carried out in a state of being mixed in advance, or they may be reacted separately in sequence, and further, the low molecular weight bodies obtained by the separate reactions may be mixed to react to form a high molecular weight body.

The temperature when the diamine component and the tetracarboxylic dianhydride component are reacted is, for example, in the range of -20°C to 150°C, preferably -5°C to 100°C. In the reaction, the total concentration of the diamine component and the tetracarboxylic dianhydride component is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, based on the reaction solution.

The ratio of the total molar number of the tetracarboxylic dianhydride component to the total molar number of the diamine component in the above polymerization reaction can be selected according to the desired molecular weight of the polyamic acid. As in the usual polycondensation reaction, the closer the molar ratio is to 1.0, the greater the molecular weight of the generated polyamic acid is, and the preferred range is 0.8 to 1.2.

The synthesis method of the polyamic acid used in the present invention is not limited to the above method, and the corresponding polyamic acid can be obtained by using a tetracarboxylic acid or a tetracarboxylic acid dihalide or other tetracarboxylic acid derivative having a corresponding structure instead of the above tetracarboxylic dianhydride and reacting them by a known method, similarly to the synthesis method of a conventional polyamic acid.

Examples of methods for imidizing the polyamic acid to form polyimide include thermal imidization in which a polyamic acid solution is directly heated and catalytic imidization in which a catalyst is added to a polyamic acid solution. It should be noted that the imidization rate from polyamic acid to polyimide is not necessarily 100%.

The temperature when the polyamic acid is thermally imidized in a solution is 100° C. to 400° C., preferably 120° C. to 250° C., and the thermal imidization is preferably performed while discharging water generated by the imidization reaction to the outside of the system.

The catalytic imidization of polyamic acid can be carried out by adding a basic catalyst and anhydride to a solution of polyamic acid and stirring at -20 to 250°C, preferably at 0 to 180°C. The amount of the basic catalyst is 0.5 to 30 times by mole of the amic acid group, preferably 2 to 20 times by mole, and the amount of the anhydride is 1 to 50 times by mole of the amic acid group, preferably 3 to 30 times by mole. As the basic catalyst, pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. can be listed, among which pyridine has a moderate alkalinity for promoting the reaction, so it is preferred. As the anhydride, acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. can be listed, among which, if acetic anhydride is used, it is easy to purify after the reaction is completed, so it is preferred. The imidization rate based on catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

In addition, polyamic acid esters can be manufactured by reacting tetracarboxylic acid diester dichloride with the same diamine as the synthesis of the above-mentioned polyamic acid, and reacting tetracarboxylic acid diester with the same diamine as the synthesis of the above-mentioned polyamic acid in the presence of a suitable condensing agent, a base, etc. In addition, polyamic acid can also be pre-synthesized by the above method, and the carboxylic acid in the amic acid is esterified by a polymer reaction to obtain it. Specifically, for example, tetracarboxylic acid diester dichloride and diamine are reacted in the presence of a base and an organic solvent at -20°C to 150°C, preferably at 0°C to 50°C for 30 minutes to 24 hours, preferably 1 hour to 4 hours, so that polyamic acid esters can be synthesized. Then, the polyamic acid ester is heated at a high temperature to promote dealcoholization to close the ring, and polyimide can also be obtained.

When the polyimide precursor or polyimide of the generated polyamic acid, polyamic acid ester, etc. is recovered from the reaction solution, the reaction solution can be put into a poor solvent to precipitate it. As the poor solvent used for precipitation, methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, water, etc. can be listed. After the polymer put into the poor solvent and precipitated, it can be dried at room temperature or heated under normal pressure or reduced pressure after filtration recovery. In addition, if the operation of dissolving the recovered polymer again in an organic solvent and recovering the precipitate again is repeated 2 to 10 times, the impurities in the polymer can be reduced. As the poor solvent at this time, for example, alcohols, ketones, hydrocarbons, etc. can be listed. If three or more poor solvents selected from these are used, the refining efficiency is further improved, so it is preferred.

<Liquid Crystal Alignment Agent>

The liquid crystal aligning agent of the present invention contains at least one polymer having a structure represented by the above formula (1) in a side chain, and the content of the polymer is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass. In addition, when a polymerizable compound having a group capable of photopolymerization or photocrosslinking at two or more ends is contained, the content thereof is preferably 1 to 50 parts by mass, and more preferably 5 to 30 parts by mass relative to 100 parts by mass of the above polymer.

Moreover, the liquid crystal aligning agent of this invention may contain other polymers other than the said polymer. In this case, content of the said other polymer in all polymer components is preferably 0.5-80 mass %, More preferably, it is 20-50 mass %.

The molecular weight of the polymer contained in the liquid crystal aligning agent is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000 as a weight average molecular weight measured by GPC (Gel Permeation Chromatography) method in consideration of the strength of the liquid crystal aligning film obtained by applying the liquid crystal aligning agent, workability during coating formation, and uniformity of the coating.

The solvent contained in the liquid crystal alignment agent is not particularly limited, and can be dissolved in a polymer having a structure shown in the above formula (1) in the side chain and a polymerizable compound having a group that can undergo photopolymerization or photocrosslinking at two or more ends as needed. For example, organic solvents such as those exemplified in the synthesis of the above-mentioned polyamic acid can be listed. Among them, from the viewpoint of solubility, preferably N-methyl-2-pyrrolidone, γ-butyrolactone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropionamide. Of course, it can also be a mixed solvent of more than two kinds.

In addition, it is preferred to mix a solvent for improving the uniformity and smoothness of the coating film with a solvent having high solubility of the components contained in the liquid crystal aligning agent. Examples of the solvent include isopropyl alcohol, methoxymethylpentyl alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, butyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol tert-butyl ether, dipropylene glycol mono Methyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, acetic acid amyl ester, butyl butyrate, butyl ether, diisobutyl ketone, methyl cyclohexene, propyl ether, dihexyl ether, n-hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl acetate, methyl glutarate, ethyl glutarate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, 3-methoxy The invention relates to butyl propionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-(2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isopentyl lactate, 2-ethyl-1-hexanol, etc. These solvents can be mixed and used in a variety of ways. These solvents are preferably 5 to 80% by mass of the overall solvent contained in the liquid crystal aligning agent, and more preferably 20 to 60% by mass.

The liquid crystal aligning agent may contain components other than those mentioned above, and examples thereof include compounds for improving the uniformity of film thickness and surface smoothness when the liquid crystal aligning agent is applied, and compounds for improving the adhesion between the liquid crystal aligning film and the substrate.

As compounds for improving film thickness uniformity and surface smoothness, fluorine-based surfactants, silicone-based surfactants, nonionic surfactants, etc. can be cited. More specifically, for example, Eftop EF301, EF303, EF352 (Tohkem products Corporation), Megafac F171, F173, R-30 (Dainippon Ink Co., Ltd.), Fluorad FC430, FC431 (Sumitomo 3M Co., Ltd.), AsahiGuard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Co., Ltd.) etc. can be cited. The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the total amount of the polymer contained in the liquid crystal aligning agent.

As specific examples of compounds for improving the adhesion between the liquid crystal alignment film and the substrate, compounds containing functional silanes, compounds containing epoxy groups, etc. can be listed. For example, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 2-aminopropyl trimethoxysilane, 2-aminopropyl triethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxysilane, 3-urea propyl trimethoxysilane, 3-urea propyl triethoxysilane, N-ethoxycarbonyl-3-aminopropyl trimethoxysilane, N-ethoxycarbonyl-3-aminopropyl triethoxysilane can be listed. Silane, N-triethoxysilylpropyl triethylenetriamine, N-trimethoxysilylpropyl triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyl trimethoxysilane, N-benzyl-3-aminopropyl triethoxysilane, N -phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2 -Dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N’,N’,-tetraglycidyl-m-phenylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N’,N’,-tetraglycidyl-4,4’-diaminodiphenylmethane, 3-(N-allyl-N-glycidyl)aminopropyltrimethoxysilane, 3-(N,N-diglycidyl)aminopropyltrimethoxysilane, etc.

In order to further improve the film strength of the liquid crystal alignment film, phenol compounds such as 2,2'-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane and tetrakis(methoxymethyl)bisphenol may be added. These compounds are preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of the total amount of the polymer contained in the liquid crystal alignment agent.

Furthermore, in addition to the above, a dielectric or a conductive substance for changing electrical properties such as a dielectric constant and conductivity of the liquid crystal aligning film may be added to the liquid crystal aligning agent within a range that does not impair the effects of the present invention.

By applying the liquid crystal alignment agent on a substrate and firing it, a liquid crystal alignment film for vertically aligning the liquid crystal can be formed. By using the liquid crystal alignment agent of the present invention, the response speed of the liquid crystal display element using the obtained liquid crystal alignment film can be accelerated. In addition, regarding the polymerizable compound that can also be contained in the liquid crystal alignment agent of the present invention, which has a group that can undergo photopolymerization or photocrosslinking at two or more ends, by containing it in the liquid crystal but not in the liquid crystal alignment agent, or containing it in the liquid crystal together with the liquid crystal alignment agent, the sensitivity of the photoreaction is also increased in the so-called PSA mode, and the inclination angle can be given even with less ultraviolet irradiation.

For example, the liquid crystal aligning agent of the present invention may be applied to a substrate, dried and fired as needed, and the cured film obtained may be directly used as a liquid crystal aligning film. In addition, the cured film may be brushed, irradiated with polarized light or light of a specific wavelength, or processed with an ion beam to form an alignment film for PSA, and the liquid crystal display element filled with liquid crystal may be irradiated with UV under a voltage applied state. In particular, it is useful to use it as an alignment film for PSA.

At this time, as the substrate used, as long as it is a substrate with high transparency, there is no particular limitation, and the plastic substrates of glass plate, polycarbonate, poly (methyl) acrylate, polyether sulfone, polyarylate, polyurethane, polysulfone, polyether, polyether ketone, trimethylpentene, polyolefin, polyethylene terephthalate, (methyl) acrylonitrile, triacetyl cellulose, diacetyl cellulose, cellulose acetate butyrate, etc., etc. can be used. In addition, from the viewpoint of simplifying the process, it is preferred to use a substrate formed with an ITO electrode for driving liquid crystal, etc. In addition, in the liquid crystal display element of the reflection type, if it is only a substrate on one side, then an opaque substrate such as a silicon wafer can also be used, and the electrode at this time can also use materials that reflect light such as aluminum.

The coating method of the liquid crystal alignment agent is not particularly limited, and examples thereof include printing methods such as screen printing, gravure printing, and flexographic printing; inkjet method, spray coating method, roll coating method, dipping, roll coater, slit coater, spin coater, etc. From the perspective of productivity, transfer printing method is widely used in industry and can also be suitably used in the present invention.

The coating formed by applying the liquid crystal alignment agent by the above method can be fired to form a cured film. The drying process after the liquid crystal alignment agent is applied is not necessary. When the time from coating to firing of each substrate is not fixed or when firing is not performed immediately after coating, it is preferred to perform a drying process. The drying process only requires the solvent to be removed to the extent that the shape of the coating will not be deformed due to the transportation of the substrate, etc., and there is no particular limitation on the drying means. For example, a method of drying on a heating plate at a temperature of 40°C to 150°C, preferably 60°C to 100°C for 0.5 minutes to 30 minutes, preferably 1 minute to 5 minutes, can be cited.

The firing temperature of the coating formed by applying the liquid crystal aligning agent is not limited, and is, for example, 100 to 350° C., preferably 120 to 300° C., and more preferably 150 to 250° C. The firing time is 5 to 240 minutes, preferably 10 to 90 minutes, and more preferably 20 to 90 minutes. Heating can be performed by a generally known method, such as a hot plate, a hot air circulation oven, an infrared oven, etc.

Moreover, although the thickness of the liquid crystal aligning film obtained by baking is not specifically limited, It is preferably 5-300 nm, More preferably, it is 10-100 nm.

<Liquid Crystal Display Element>

Regarding the liquid crystal display element of the present invention, after forming a liquid crystal alignment film on a substrate by the above method, a liquid crystal unit can be prepared by a known method. As a specific example of a liquid crystal display element, a liquid crystal display element having a vertical alignment mode of a liquid crystal unit, the liquid crystal unit having: two substrates arranged in a relative manner, a liquid crystal layer arranged between the substrates, and the above-mentioned liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention and arranged between the substrate and the liquid crystal layer. Specifically, it is a liquid crystal display element having a vertical alignment mode of a liquid crystal unit prepared as follows: a liquid crystal alignment film is formed by coating the liquid crystal alignment agent of the present invention on two substrates and firing them, two substrates are arranged in a manner relative to the liquid crystal alignment film, a liquid crystal layer composed of liquid crystals is sandwiched between the two substrates, that is, a liquid crystal layer is arranged in contact with the liquid crystal alignment film, and a voltage is applied to the liquid crystal alignment film and the liquid crystal layer while irradiating ultraviolet light, thereby preparing a liquid crystal unit.

By using a liquid crystal orientation film formed by the liquid crystal orientation agent of the present invention, a voltage is applied to the liquid crystal orientation film and the liquid crystal layer while irradiating ultraviolet rays to polymerize the polymerizable compound, and the photoreactive side chains of the polymer are reacted with each other and the photoreactive side chains of the polymer are reacted with the polymerizable compound, so that the orientation of the liquid crystal is more effectively fixed, forming a liquid crystal display element with significantly excellent response speed.

As the substrate used in the liquid crystal display element of the present invention, there is no particular limitation as long as it is a substrate with high transparency, and it is usually a substrate on which a transparent electrode for driving liquid crystal is formed. As a specific example, a substrate identical to the substrate described in the above-mentioned liquid crystal alignment film can be cited. A substrate provided with an existing electrode pattern or a protrusion pattern can also be used, but the liquid crystal display element of the present invention uses the liquid crystal alignment agent of the present invention, so it can work even if a line/slit electrode pattern of, for example, 1 to 10 μm is formed on a single-side substrate and a slit pattern or a protrusion pattern is not formed on the opposite substrate. The liquid crystal display element of this structure can be used to simplify the process during manufacturing and obtain a high transmittance.

In addition, in high-performance elements such as TFT type elements, elements such as transistors formed between electrodes for driving liquid crystal and a substrate can be used.

In the case of a transmissive liquid crystal display element, the above-mentioned substrate is usually used, but in a reflective liquid crystal display element, if only one side of the substrate is used, an opaque substrate such as a silicon wafer can also be used. In this case, the electrode formed on the substrate can also use a material such as aluminum that reflects light.

The liquid crystal material constituting the liquid crystal layer of the liquid crystal display element of the present invention is not particularly limited, and liquid crystal materials used in the vertical alignment method in the past can be used, such as negative liquid crystals such as MLC-6608 and MLC-6609 manufactured by MERCK Corporation. In addition, in the PSA mode, for example, liquid crystals containing polymerizable compounds such as those shown in the following formula can be used.

In the present invention, as a method for sandwiching the liquid crystal layer between two substrates, a known method can be cited. For example, the following method can be cited: prepare a pair of substrates with a liquid crystal alignment film, scatter spacers such as beads on the liquid crystal alignment film of one substrate, paste the other substrate in a manner that the surface of the side with the liquid crystal alignment film becomes the inner side, and inject the liquid crystal under reduced pressure and seal. In addition, a liquid crystal unit can also be made by the following method: prepare a pair of substrates with a liquid crystal alignment film, scatter spacers such as beads on the liquid crystal alignment film of one substrate, then drip liquid crystal, and then paste the other substrate in a manner that the surface of the side with the liquid crystal alignment film becomes the inner side for sealing. The thickness of the above-mentioned spacer is preferably 1 to 30 μm, more preferably 2 to 10 μm.

The process of making a liquid crystal unit by applying voltage to the liquid crystal alignment film and the liquid crystal layer while irradiating ultraviolet rays can be listed, for example, by applying a voltage between electrodes provided on the substrate to apply an electric field to the liquid crystal alignment film and the liquid crystal layer, and irradiating ultraviolet rays under the condition of maintaining the electric field. Here, the voltage applied between the electrodes is, for example, 5 to 30 Vp-p, preferably 5 to 20 Vp-p. The irradiation amount of ultraviolet rays is, for example, 1 to 60 J, preferably 40 J or less. When the irradiation amount of ultraviolet rays is small, it is possible to suppress the reduction in reliability caused by the destruction of the components constituting the liquid crystal display element, and reduce the ultraviolet irradiation time, thereby improving the manufacturing efficiency, which is suitable.

As described above, if a voltage is applied to the liquid crystal alignment film and the liquid crystal layer while ultraviolet rays are irradiated, the polymerizable compound reacts to form a polymer, and the tilt direction of the liquid crystal molecules is remembered by the polymer, thereby accelerating the response speed of the resulting liquid crystal display element. In addition, when a voltage is applied to the liquid crystal alignment film and the liquid crystal layer while ultraviolet rays are irradiated, the photoreactive side chains of at least one polymer selected from a polyimide precursor having a side chain for vertically aligning the liquid crystal and a photoreactive side chain, and a polyimide obtained by imidizing the polyimide precursor react with each other, and the photoreactive side chains of the polymer react with the polymerizable compound, thereby accelerating the response speed of the resulting liquid crystal display element.

Example

Hereinafter, the present invention will be described in further detail based on Examples, but the present invention is not limited to these Examples at all.

<Synthesis of Liquid Crystal Alignment Agent>

The abbreviations used in preparation of the following liquid crystal aligning agent are as follows.

(Acid dianhydride)

BODA: Bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride

CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

PMDA: pyromellitic dianhydride

TCA: 2,3,5-tricarboxycyclopentylacetic acid-1,4,2,3-dianhydride

(Diamine)

p-PDA: p-phenylenediamine

DBA: 3,5-diaminobenzoic acid

3AMPDA: 3,5-diamino-N-(pyridin-3-ylmethyl)benzamide Photosensitive diamines represented by the following formulas DA-1 to DA-3

The polymerizable diamine represented by the following formula DA-4

Vertically aligning side chain diamines represented by the following formulas DA-5 to DA-7

Diamines represented by the following formulas DA-8 to DA-9

<Solvent>

NMP: N-methyl-2-pyrrolidone

BCS: Butyl Cellosolve

<Additives>

3AMP: 3-pyridylmethylamine

<Polymerizable Compound>

The polymerizable compound represented by the following formula RM1

In addition, the molecular weight measurement conditions of the polyimide are as follows.

Apparatus: Normal temperature gel permeation chromatography (GPC) apparatus (SSC-7200) manufactured by Senshu Scientific Co., Ltd.

Column: Column manufactured by Shodex (KD-803, KD-805)

Column temperature: 50°C

Eluent: N,N'-dimethylformamide (as additives, lithium bromide monohydrate (LiBr·H ₂ O) 30 mmol/L, phosphoric acid·anhydrous crystals (orthophosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 ml/L)

Flow rate: 1.0ml/min

Standard samples for preparing the calibration curve: TSK standard polyethylene oxide manufactured by Tosoh Corporation (molecular weight of approximately 9,000,000, 150,000, 100,000, and 30,000) and polyethylene glycol manufactured by Polymer Laboratories Ltd. (molecular weight of approximately 12,000, 4,000, and 1,000).

The imidization rate of polyimide is measured as follows. 20 mg of polyimide powder is put into an NMR sample tube (NMR sample tube standard φ5 manufactured by Kusano Scientific Co., Ltd.), 1.0 ml of deuterated dimethyl sulfoxide (DMSO-d ₆ , 0.05% TMS mixture) is added, and ultrasonic waves are applied to completely dissolve it. The solution is measured with a 500 MHz proton NMR using an NMR measuring device (JNW-ECA500) manufactured by JEOL DATUM LTD. The imidization rate is determined using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integral value of the proton derived from the NH group of the amic acid appearing near 9.5 to 10.0 ppm is used to determine the peak integral value of the proton, and the peak integral value of the proton derived from the NH group of the amic acid appearing near 9.5 to 10.0 ppm is used. In the following formula, x is the peak integral value of protons derived from the NH group of amic acid, y is the peak integral value of reference protons, and α is the number ratio of reference protons to one proton of the NH group of amic acid in the case of polyamic acid (imidation ratio 0%).

Imidization rate (%) = (1-α·x/y) × 100

(Synthesis Example 1)

BODA (10.01 g, 40.0 mmol), 3AMPDA (4.85 g, 20.0 mmol), DA-2 (13.22 g, 40.0 mmol), and DA-5 (15.22 g, 40.0 mmol) were dissolved in NMP (164.6 g), and reacted at 60°C for 5 hours. Then, CBDA (11.57 g, 59.0 mmol) and NMP (54.9 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (250 g) to dilute it to 6.5% by mass, and then acetic anhydride (46.4 g) and pyridine (14.4 g) were added as imidization catalysts, and the mixture was reacted at 70° C. for 3 hours. The reaction solution was put into methanol (3300 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (A). The imidization rate of the polyimide was 72%, the number average molecular weight was 14,000, and the weight average molecular weight was 38,000.

NMP (44.0 g) was added to the obtained polyimide powder (A) (6.0 g), and the mixture was dissolved by stirring at 70° C. for 20 hours. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (U1).

(Synthesis Example 2)

BODA (10.01 g, 40.0 mmol), 3AMPDA (4.85 g, 20.0 mmol), DA-1 (14.34 g, 40.0 mmol), and DA-5 (15.22 g, 40.0 mmol) were dissolved in NMP (168.0 g), and reacted at 60°C for 5 hours. Then, CBDA (11.57 g, 59.0 mmol) and NMP (55.98 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (250 g) to dilute it to 6.5% by mass, and then acetic anhydride (45.4 g) and pyridine (14.0 g) were added as imidization catalysts, and the mixture was reacted at 70° C. for 3 hours. The reaction solution was put into methanol (3300 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (B). The imidization rate of the polyimide was 73%, the number average molecular weight was 18,000, and the weight average molecular weight was 37,000.

NMP (44.0 g) was added to the obtained polyimide powder (B) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (U2).

(Synthesis Example 3)

BODA (10.01 g, 40.0 mmol), 3AMPDA (4.85 g, 20.0 mmol), DA-3 (13.78 g, 40.0 mmol), and DA-5 (15.22 g, 40.0 mmol) were dissolved in NMP (166.2 g), and reacted at 60°C for 5 hours. Then, CBDA (11.57 g, 59.0 mmol) and NMP (55.42 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (250 g) to dilute it to 6.5% by mass, and then acetic anhydride (45.49 g) and pyridine (14.3 g) were added as imidization catalysts, and the mixture was reacted at 70° C. for 3 hours. The reaction solution was put into methanol (3300 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (C). The imidization rate of the polyimide was 72%, the number average molecular weight was 21,000, and the weight average molecular weight was 82,000.

NMP (44.0 g) was added to the obtained polyimide powder (C) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1 mass % NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (U3).

(Synthesis Example 4)

TCA (11.21 g, 50.0 mmol), p-PDA (4.33 g, 40.0 mmol), DA-3 (6.89 g, 20.0 mmol), DA-5 (7.61 g, 20.0 mmol), and DA-7 (9.90 g, 20.0 mmol) were dissolved in NMP (148.6 g), and reacted at 80°C for 5 hours. Then, CBDA (9.61 g, 49.0 mmol) and NMP (49.54 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (220 g) to dilute it to 6.5% by mass, and then acetic anhydride (35.1 g) and pyridine (10.9 g) were added as imidization catalysts, and the mixture was reacted at 50° C. for 3 hours. The reaction solution was put into methanol (2900 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (D). The imidization rate of the polyimide was 51%, the number average molecular weight was 11,000, and the weight average molecular weight was 25,000.

NMP (44.0 g) was added to the obtained polyimide powder (D) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (U4).

(Synthesis Example 5)

BODA (10.01 g, 40.0 mmol), DA-4 (7.93 g, 30.0 mmol), DA-3 (10.33 g, 30.0 mmol), DA-5 (7.61 g, 20.0 mmol), and DA-6 (8.69 g, 20.0 mmol) were dissolved in NMP (168.4 g), and reacted at 80°C for 5 hours. Then, CBDA (11.57 g, 49.0 mmol) and NMP (56.14 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (250 g) to dilute it to 6.5% by mass, and then acetic anhydride (27.2 g) and pyridine (70.2 g) were added as imidization catalysts, and the mixture was reacted at 50° C. for 3 hours. The reaction solution was put into methanol (3500 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (E). The imidization rate of the polyimide was 59%, the number average molecular weight was 14,000, and the weight average molecular weight was 51,000.

NMP (44.0 g) was added to the obtained polyimide powder (E) (6.0 g), and the mixture was dissolved by stirring at 70° C. for 20 hours. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (U5).

(Synthesis Example 6)

BODA (18.77 g, 75.0 mmol), DBA (3.04 g, 20.0 mmol), DA-8 (9.96 g, 50.0 mmol), and DA-5 (11.42 g, 30.0 mmol) were dissolved in NMP (143.7 g), and reacted at 60°C for 5 hours. Then, CBDA (4.12 g, 21.0 mmol) and NMP (47.89 g) were added, and the mixture was reacted at 40°C for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (180 g) to dilute it to 6.5% by mass, and then acetic anhydride (19.1 g) and pyridine (14.8 g) were added as imidization catalysts, and the mixture was reacted at 80° C. for 4 hours. The reaction solution was put into methanol (2200 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (E). The imidization rate of the polyimide was 57%, the number average molecular weight was 12,000, and the weight average molecular weight was 39,000.

NMP (44.0 g) was added to the obtained polyimide powder (E) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (L1).

(Synthesis Example 7)

BODA (12.51 g, 50.0 mmol), DBA (12.93 g, 85.0 mmol), and DA-9 (6.16 g, 15.0 mmol) were dissolved in NMP (123.3 g), and reacted at 60° C. for 3 hours. Then, CBDA (9.51 g, 48.5 mmol) and NMP (41.11 g) were added, and reacted at 40° C. for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (180 g) to dilute it to 6.5% by mass, and then acetic anhydride (44.4 g) and pyridine (13.8 g) were added as imidization catalysts, and the mixture was reacted at 80° C. for 2 hours. The reaction solution was put into methanol (2400 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (F). The imidization rate of the polyimide was 70%, the number average molecular weight was 12,000, and the weight average molecular weight was 31,000.

NMP (44.0 g) was added to the obtained polyimide powder (F) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (L2).

(Synthesis Example 8)

BODA (5.00 g, 20.0 mmol), DBA (6.09 g, 40.0 mmol), 3AMPDA (7.27 g, 30.0 mmol), and DA-5 (11.42 g, 30.0 mmol) were dissolved in NMP (136.5 g), and reacted at 60° C. for 3 hours. Then, PMDA (4.36 g, 48.5 mmol), CBDA (11.37 g, 58.0 mmol), and NMP (45.51 g) were added, and the mixture was reacted at 40° C. for 10 hours to obtain a polyamic acid solution.

NMP was added to the polyamic acid solution (180 g) to dilute it to 6.5% by mass, and then acetic anhydride (40.0 g) and pyridine (12.4 g) were added as imidization catalysts, and the mixture was reacted at 50° C. for 3 hours. The reaction solution was put into methanol (2300 ml), and the resulting precipitate was filtered out. The precipitate was washed with methanol and dried under reduced pressure at 100° C. to obtain a polyimide powder (G). The imidization rate of the polyimide was 78%, the number average molecular weight was 9000, and the weight average molecular weight was 20000.

NMP (44.0 g) was added to the obtained polyimide powder (G) (6.0 g), and the mixture was stirred at 70° C. for 20 hours to dissolve. 6.0 g of 3AMP (1% by mass NMP solution), NMP (4.0 g), and BCS (40.0 g) were added to the solution, and the mixture was stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (L3).

[Table 1]

(Example 1)

3.0 g of the liquid crystal aligning agent (U1) obtained in Synthesis Example 1 as the first component and 7.0 g of the liquid crystal aligning agent (L1) obtained in Example 5 as the second component were mixed and stirred for 1 hour to prepare a liquid crystal aligning agent (A1).

<Preparation of Liquid Crystal Cell>

The liquid crystal unit was prepared by the following steps using the liquid crystal alignment agent (A1) obtained in Example 1. The liquid crystal alignment agent (A1) obtained in Example 1 was spin-coated on the ITO surface of an ITO electrode substrate having an ITO electrode pattern with a pixel size of 100 μm×300 μm and a line/space of 5 μm, dried on a hot plate at 80°C for 90 seconds, and then sintered in a hot air circulation oven at 200°C for 30 minutes to form a liquid crystal alignment film with a film thickness of 100 nm.

Moreover, the liquid crystal aligning agent (A1) was spin-coated on the ITO surface where the electrode pattern was not formed, and it dried for 90 seconds on an 80 degreeC hot plate, and it baked for 30 minutes in a 200 degreeC hot air circulation oven, and formed the liquid crystal aligning film with a film thickness of 100 nm.

For the above two substrates, after spreading 4 μm bead spacers on the liquid crystal alignment film of one substrate, a sealant (solvent-based thermosetting epoxy resin) was printed from above. Next, the other substrate was attached to the aforementioned substrate with the surface on the side where the liquid crystal alignment film was formed as the inner side, and the sealant was cured to prepare an empty cell. Liquid crystal MLC-3023 (trade name manufactured by MERCK Corporation) containing a polymerizable compound for PSA was injected into the empty cell by a reduced pressure injection method to prepare a liquid crystal cell.

The response speed of the obtained liquid crystal unit is measured by the following method. Then, 10 J/ ^cm2 of UV passing through a 365 nm bandpass filter is irradiated from the outside of the liquid crystal unit while a DC voltage of 15 V is applied to the liquid crystal unit. It should be noted that the UV illumination is measured using UV-MO3A manufactured by ORC Co., Ltd. Then, in order to deactivate the unreacted polymerizable compound remaining in the liquid crystal unit, UV (UV lamp: FLR40SUV32/A-1) is irradiated for 30 minutes using a UV-FL irradiation device manufactured by Toshiba Lightec Co., Ltd. without applying voltage. Then, the response speed is measured again, and the response speeds before and after UV irradiation are compared. In addition, the pretilt angle of the pixel portion is measured for the unit after UV irradiation.

In addition, the residual DC voltage of each cell was measured and the results are shown in the table.

「Measurement method of response speed」

First, in a measuring device composed of a backlight, a set of polarizing plates in a crossed Nicol prism state, and a light quantity detector, a liquid crystal cell is arranged between the set of polarizing plates. At this time, the pattern of the ITO electrode forming the line/space is made to be at an angle of 45° with respect to the crossed Nicol prism. Then, a rectangular wave with a voltage of ±7V and a frequency of 1kHz is applied to the liquid crystal cell, and the change until the brightness observed by the light quantity detector is saturated is collected by an oscilloscope, and the brightness when no voltage is applied is set to 0%, the value of the brightness saturated by applying a voltage of ±6V is set to 100%, and the time taken for the brightness to change from 10% to 90% is set to the response speed.

「Measurement of pretilt angle」

An LCD analyzer LCA-LUV42A manufactured by Meiryo Technica Corporation was used.

「Evaluation of residual DC voltage」

For the liquid crystal cell manufactured as described above, a rectangular wave of 30 Hz, 7.8 Vpp superimposed with a DC voltage of 2 V was applied for 100 hours at 23° C., and the voltage remaining in the liquid crystal cell just after the DC voltage was cut off (residual DC voltage) was obtained by the flicker elimination method. This value becomes an indicator of the residual image caused by DC accumulation, and when this value is about 30 mV or less, the residual image characteristic is judged to be excellent.

(Example 2)

Liquid crystal aligning agent (A2) was prepared by performing the same operation as in Example 1 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 3)

Liquid crystal aligning agent (A3) was prepared by the same operation as in Example 1 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by the same operation as in Example 1.

(Example 4)

Liquid crystal aligning agent (A4) was prepared by performing the same operation as in Example 1 except that liquid crystal aligning agent (U1) was changed to liquid crystal aligning agent (U2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 5)

Liquid crystal aligning agent (A5) was prepared by performing the same operation as in Example 4 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 6)

Liquid crystal aligning agent (A6) was prepared by performing the same operation as in Example 4 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 7)

Liquid crystal aligning agent (A7) was prepared by performing the same operation as in Example 1 except that liquid crystal aligning agent (U1) was changed to liquid crystal aligning agent (U3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 8)

Liquid crystal aligning agent (A8) was prepared by performing the same operation as in Example 7 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 9)

Liquid crystal aligning agent (A9) was prepared by the same operation as in Example 7 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by the same operation as in Example 1.

(Example 10)

Liquid crystal aligning agent (A10) was prepared by performing the same operation as in Example 1 except that liquid crystal aligning agent (U1) was changed to liquid crystal aligning agent (U4). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 11)

Liquid crystal aligning agent (A11) was prepared by performing the same operation as in Example 10 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 12)

Liquid crystal aligning agent (A12) was prepared by performing the same operation as in Example 10 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 13)

Liquid crystal aligning agent (A13) was prepared by performing the same operation as in Example 1 except that liquid crystal aligning agent (U1) was changed to liquid crystal aligning agent (U5). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 14)

Liquid crystal aligning agent (A14) was prepared by performing the same operation as in Example 13 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L2). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 15)

Liquid crystal aligning agent (A15) was prepared by performing the same operation as in Example 13 except that liquid crystal aligning agent (L1) was changed to liquid crystal aligning agent (L3). Furthermore, the response speed, pretilt angle, and residual DC voltage were measured by performing the same operation as in Example 1.

(Example 16)

5.0 g of a liquid crystal aligning agent (U5) as the first component, 5.0 g of a liquid crystal aligning agent (L1) as the second component, and 0.06 g (10% by mass relative to the solid content of the liquid crystal aligning agent) as a polymerizable compound were mixed and stirred for 1 hour to prepare a liquid crystal aligning agent (A16). Furthermore, MLC-6608 was used as a liquid crystal not containing a polymerizable compound for PSA, and the same operation as in Example 1 was performed to measure the response speed, pretilt angle, and residual DC voltage.

(Comparative Example 1)

As a liquid crystal aligning agent, the response speed, the pretilt angle, and the residual DC voltage were measured by carrying out the same operation as in Example 1 except that a liquid crystal aligning agent (U1) was used.

(Comparative Example 2)

The response speed, the pretilt angle, and the residual DC voltage were measured by performing the same operation as in Example 1 except that a liquid crystal aligning agent (U2) was used as a liquid crystal aligning agent.

(Comparative Example 3)

As a liquid crystal aligning agent, the response speed, the pretilt angle, and the residual DC voltage were measured by carrying out the same operation as in Example 1 except that a liquid crystal aligning agent (U3) was used.

(Comparative Example 4)

The response speed, the pretilt angle, and the residual DC voltage were measured by performing the same operation as in Example 1 except that the liquid crystal aligning agent (U4) was used as the liquid crystal aligning agent.

(Comparative Example 5)

As a liquid crystal aligning agent, the response speed, the pretilt angle, and the residual DC voltage were measured by carrying out the same operation as in Example 1 except that a liquid crystal aligning agent (U5) was used.

[Table 2]

As shown in the above results, in Examples 1 to 12, the tilt angle was given by UV irradiation by introducing the component 1 having a free radical generating structure, thereby improving the response speed. Furthermore, it can be seen that the residual DC voltage characteristics are also good, and there is basically no accumulation of residual DC voltage after long-term DC application.

On the other hand, in the comparative example, since the component 2 was not introduced, it was confirmed that a residual DC voltage was accumulated due to long-term DC application.

As described above, by using a first component having a radical generating structure and a second component having the effect of suppressing residual DC voltage in combination, a liquid crystal display element can be provided that has an improved response speed even when irradiated with ultraviolet rays of a long wavelength (eg, 365 nm) and has excellent afterimage characteristics.

Claims (4)

1. A liquid crystal aligning agent characterized by comprising the following component (A), component (B) and an organic solvent, and further comprising a polymerizable compound having at least 2 terminal groups capable of photopolymerization or photocrosslinking selected from monovalent groups represented by the following formula (IV),

(A) The components are as follows: at least one polymer selected from polyimide precursors having side chains for vertically aligning liquid crystals and side chains having a site where radicals are generated by ultraviolet irradiation as shown in the following formula (1), and polyimides obtained by imidizing the polyimide precursors,

R ₁、R₂ is independently an alkyl group or an alkoxy group having 1 to 10 carbon atoms, T1 and T2 are independently a single bond or a -O-、-COO-、-OCO-、-NHCO-、-CONH-、-NH-、-CH₂O-、-N(CH₃)-、-CON(CH₃)-、-N(CH₃)CO- linking group, and S is a single bond or an alkylene group having 1 to 20 carbon atoms which is unsubstituted or substituted with a fluorine atom; wherein, -CH ₂ -or-CF ₂ -of the alkylene group is optionally replaced by-ch=ch-, and, in the case where any of the groups listed below are not adjacent to each other, are optionally replaced by these groups: -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, a divalent carbocyclic ring, a divalent heterocyclic ring, ar is phenylene, naphthylene or biphenylene optionally substituted with an organic group, Q represents the structure,

-OR

R is alkyl with 1-4 carbon atoms;

(B) The components are as follows: a polymer selected from a polyimide precursor obtained from a diamine component containing at least one diamine selected from the following formulas (B-1) to (B-5) as a raw material and a polyimide obtained by imidizing the polyimide precursor, a polyimide precursor obtained from a tetracarboxylic dianhydride component containing at least one tetracarboxylic dianhydride selected from the following formulas (3) and (4) as a raw material and a polyimide obtained by imidizing the polyimide precursor,

Y ₁ is a monovalent organic group having a secondary amine, tertiary amine or heterocyclic structure, Y ₂ is a divalent organic group having a secondary amine, tertiary amine or heterocyclic structure,

N and m are 0 or 1, X and y are single bond, carbonyl, ester group, phenylene and sulfonyl,

R ¹² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, Z ¹ represents a divalent aromatic ring or a heterocyclic ring optionally substituted with an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms, and Z ² represents a monovalent aromatic ring or a heterocyclic ring optionally substituted with an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms.

2. A liquid crystal alignment film obtained by applying the liquid crystal alignment agent according to claim 1 to a substrate and firing the applied liquid crystal alignment agent.

3. A liquid crystal display element comprising a liquid crystal cell, wherein a liquid crystal layer is provided in contact with a liquid crystal alignment film obtained by applying the liquid crystal alignment agent of claim 1 to a substrate and firing the liquid crystal alignment film, and ultraviolet light is irradiated to the liquid crystal layer while applying a voltage thereto.

4. A method for manufacturing a liquid crystal display element, characterized in that a liquid crystal layer is provided in contact with a liquid crystal alignment film obtained by applying the liquid crystal alignment agent of claim 1 on a substrate and firing the liquid crystal alignment film, and ultraviolet rays are irradiated to the liquid crystal layer while applying a voltage thereto, thereby manufacturing a liquid crystal cell.