TWI816939B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent for photo-alignment, a liquid crystal alignment film and a liquid crystal display element, which can suppress image sticking caused by long-term AC driving in an IPS-driven or FFS-driven liquid crystal display element. The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film. The liquid crystal alignment agent is characterized by containing: four elements represented by the following formula (1) A tetracarboxylic acid component of a carboxylic dianhydride or a derivative thereof, a tetracarboxylic dianhydride represented by the following formula (2) or a derivative thereof and an aromatic tetracarboxylic dianhydride represented by the following formula (6) Polyimide is a polyimide product of a polyimide precursor obtained by the polymerization reaction of a diamine component. (X ₁ represents any one of formulas (X1-1) to (X1-4), X ₂ represents formula (X2-1) or (X2-2), and X ₃ represents a tetravalent aromatic ring group).

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element provided with the obtained liquid crystal alignment film.

Liquid crystal display elements used in LCD TVs, LCD monitors, etc. usually have a liquid crystal alignment film inside the element for controlling the alignment state of the liquid crystal. At present, the most popular liquid crystal alignment film in the industry is a film made of polyamide and/or imidized polyimide, which is formed on the surface of an electrode substrate and is made of cotton or nylon. It is made by rubbing a cloth such as polyester or polyester in one direction and performing a so-called rubbing treatment. The friction treatment is an industrially useful method that is simple and has excellent productivity. However, as liquid crystal display elements become more high-performance, high-definition, and large-scale, the effects of scratches, dust, mechanical force, or static electricity on the surface of the alignment film caused by the rubbing treatment, and even the effects within the alignment treatment surface Various problems such as unevenness become apparent.

As an alternative to the rubbing treatment, a photo-alignment method is known that imparts alignment ability to liquid crystal by irradiating polarized radiation. As for the processing of the photoalignment method, there are proposals using photoisomerization reaction, photocrosslinking reaction, photodecomposition reaction, etc. (see Non-Patent Document 1).

Patent Document 1 proposes using a polyimide film having an alicyclic structure such as a cyclobutane ring in the main chain for a photoalignment method. As a friction-free alignment treatment method, the above-mentioned photo-alignment method can not only be produced with an industrially simple process, but also has a higher performance in IPS-driven or FFS (edge field switching)-driven liquid crystal display elements than friction treatment. The liquid crystal alignment film obtained by this method can be expected to improve the contrast or viewing angle characteristics of the liquid crystal display element, so it has attracted attention as a promising liquid crystal alignment treatment method.

In addition to basic properties such as excellent liquid crystal alignment or electrical properties, the liquid crystal alignment film used in IPS-driven or FFS-driven liquid crystal display elements also needs to suppress image sticking caused by long-term AC driving. However, the liquid crystal alignment film obtained by the photo-alignment method has a problem that the anisotropy of the alignment direction of the polymer film is smaller than that obtained by rubbing. If the anisotropy is small, sufficient liquid crystal alignment will not be obtained, and problems such as image sticking will occur when a liquid crystal display element is used. On the other hand, Patent Document 2 proposes, as a method of improving the anisotropy of a liquid crystal alignment film obtained by a photo-alignment method, removing the polyimide produced by cutting the main chain of the polyimide due to light irradiation after light irradiation. of low molecular weight components. Prior art documents Patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 9-297313 Patent Document 2: Japanese Patent Application Publication No. 2011-107266 non-patent literature

Non-patent document 1: "Liquid crystal photo-alignment film" Kidowaki, Ichimura Functional Materials, November 1997 issue Vol.17, No.11, pages 13~22

Invent the problem to be solved

In the past, when performing photo-alignment treatment of organic films such as polyimide precursors and polyimide, according to the inventor's knowledge, it was found that the effect of photo-alignment is sensitive to the amount of light irradiation used. A relatively narrow range of optimum irradiation dose is required. If the irradiation dose deviates from this optimum range, alignment may become incomplete in a part or the entire liquid crystal alignment film, resulting in a situation where stable alignment of liquid crystal cannot be achieved. Furthermore, it was found that especially when processing large-sized panels by the photo-alignment method, it becomes difficult to perform photo-alignment irradiation with a uniformly controlled light irradiation amount. As a result, stable alignment processing by the photo-alignment method becomes difficult.

Therefore, an object of the present invention is to provide a liquid crystal alignment agent that achieves a wide irradiation amount margin by expanding the range of light irradiation amount that achieves good alignment control capability (hereinafter, also referred to as the optimal irradiation amount margin). Especially in the case of large-sized panels, good quality and stable liquid crystal alignment capabilities can be obtained. That is, an object of the present invention is to provide a liquid crystal alignment agent that has a wide light irradiation amount range in which alignment control ability can stably occur, and that can efficiently obtain a high-quality liquid crystal alignment film. means of solving problems

The inventors of the present invention repeatedly conducted diligent examinations and found that the above object can be achieved by an invention including a liquid crystal alignment agent having the following points. A liquid crystal alignment agent characterized by containing: tetracarboxylic dianhydride or its derivative represented by the following formula (1), tetracarboxylic dianhydride represented by the following formula (2) or its derivative and a polyimide which is an imide product of a polyimide precursor obtained by the polymerization reaction of a tetracarboxylic acid component and a diamine component of an aromatic tetracarboxylic dianhydride represented by the following formula (6).

However, X ₁ has a structure represented by any one of the following formulas (X1-1) to (X1-4); X ₂ has a structure represented by the following formula (X2-1) or (X2-2); X ₃ is an aromatic ring having 4 bonds.

However, R ₃ to R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkynyl group with 2 to 6 carbon atoms, or a carbon number containing a fluorine atom. The monovalent organic groups or phenyl groups of 1 to 6 may be the same or different, but at least one of them is other than a hydrogen atom; R ₇ to R ₂₃ are each independently a hydrogen atom, a halogen atom, or an alkane with 1 to 6 carbon atoms. group, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group.

Effect of the invention

With the liquid crystal alignment agent of the present invention, it is possible to expand the light irradiation amount margin to achieve excellent photo alignment processing, which has been difficult in the past, and a liquid crystal alignment film with good image sticking properties can be obtained. Therefore, the liquid crystal alignment film system obtained from the liquid crystal alignment agent of the present invention has a high yield in the manufacture of liquid crystal panels, and can reduce the image sticking caused by AC driving in the IPS driving mode or FFS driving mode liquid crystal display element, and obtain IPS-driven or FFS-driven liquid crystal display elements with excellent image sticking characteristics.

Form of carrying out the invention

The liquid crystal alignment agent of the present invention is as described above, and is characterized by containing: a polyimide precursor obtained from a tetracarboxylic acid component derivative having a specific structure or a tetracarboxylic acid component derivative having a derivative thereof, and a diamine component. Polyimide compound (hereinafter also referred to as specific polymer).

＜Specified polymer＞ The specific polymer used in the present invention is a polyimide which is an imide product of a polyimide precursor having a specific structure. As a polyimide precursor, as long as it is a polyimide precursor that forms an imine ring through chemical imidization caused by heating of polyamide acid, polyamide ester, or the like or a catalyst, There are no special restrictions. From the viewpoint of easiness of heating or chemical imidization, the polyimide precursor is preferably polyamide acid or polyamide ester. The imidization rate of the polyimide is not particularly limited, but is preferably 10 to 100%, more preferably 50 to 100%, and particularly preferably 50 to 80%. Each component of the raw material forming the above-mentioned specific polymer will be described below.

＜Tetracarboxylic acid component＞ The polymerized tetracarboxylic acid component used in the specific polymer of the present invention may be not only tetracarboxylic dianhydride but also its derivatives. Tetracarboxylic acid, tetracarboxylic acid dihalide, and tetracarboxylic acid dialkyl ester may also be used. Or dialkyl tetracarboxylate dihalide.

The polymerized tetracarboxylic acid component used in the specific polymer of the present invention contains tetracarboxylic dianhydride or a derivative thereof represented by the following formula (1), and tetracarboxylic dianhydride represented by the following formula (2). anhydride or a derivative thereof and an aromatic tetracarboxylic dianhydride represented by the following formula (6) or a derivative thereof. By containing the tetracarboxylic dianhydride of the above formula (1) or its derivatives, the amount of light irradiation required for the photoreaction of a specific polymer can be reduced, and a liquid crystal alignment film showing high liquid crystal alignment can be obtained. By containing the tetracarboxylic dianhydride of the above formula (2) or its derivatives and the tetracarboxylic dianhydride of the above formula (6) or its derivatives, the photoreactivity of a specific polymer can be adjusted and the irradiation amount margin can be obtained Broad LCD alignment film. X ₁ has a structure represented by any one of the following formulas (X1-1) to (X1-4). R ₃ to R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkynyl group with 2 to 6 carbon atoms, or a fluorine atom containing 1 to 6 carbon atoms. 6 is a monovalent organic group or a phenyl group, and at least one of them is other than a hydrogen atom; R ₇ ~ R ₂₃ are each independently a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, and an alkene with 2 to 6 carbon atoms. group, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group.

In order to suppress image sticking caused by long-term AC driving, _X1 is preferably at least one selected from the structure represented by any one of the following formulas (X1-12) to (X1-16), and particularly preferably The following formula (X1-12).

The content ratio of the tetracarboxylic dianhydride or its derivative represented by the above formula (1) relative to the tetracarboxylic acid component reacted with the diamine component is preferably 50 to 98 mol%, more preferably 60 to 93 mol%. Ear%, especially 65~87 mol%.

In the formula (2), X ₂ has a structure of the following formula (X2-1) or (X2-2). In order to suppress image retention caused by long-term AC driving, X ₂ is preferably formula (X2-1).

The content ratio of the tetracarboxylic dianhydride or its derivative represented by the above formula (2) is preferably 1 to 30 mol%, more preferably 5 to 25%, based on 1 mole of the total tetracarboxylic acid component. The best is 10~20%.

X ₃ is a tetravalent organic group and is an aromatic ring with 4 bonds. Preferably, it is an aromatic ring with at least 1 benzene ring or naphthalene ring and 4 bonds on the benzene ring or naphthalene ring. If specific examples are given, any structure of the following formulas (X3-1) to (X3-26) can be cited. When improving liquid crystal alignment, X ₃ is preferably any one of (X3-1), (X3-5)~(X3-11), (X3-14)~(X3-26). More preferably, it is a structure in which n in (X3-1), (X3-7), and (X3-8) is 1~4, and more preferably (X3-9)~(X3-10) or (X3-14) ~(X3-26).

The content ratio of the aromatic tetracarboxylic dianhydride or its derivative represented by the above formula (6) is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, based on 1 mole of the tetracarboxylic acid component. %, preferably 3~15 mol%.

The tetracarboxylic acid component used in the polymerization of the specific polymer of the present invention may contain, in addition to the above formulas (1), (2) and (6), a tetracarboxylic dianhydride represented by the following formula (7) or its derivatives. However, X ₄ is a tetravalent organic group other than the above-mentioned X ₁ to X ₃ , but its structure is not particularly limited. Specific examples include the following formulas (X4-1) to (X4-26), tetravalent groups derived from ethylenediaminetetraacetic dianhydride, and the like. When improving liquid crystal alignment, examples of X ₄ include (X4-8) to (X4-12), (X4-17) to (X4-19), and (X4-24) to (X4-26).

＜Diamine＞ The diamine component used for producing the specific polymer of the present invention is not particularly limited as long as it is a well-known diamine. From the viewpoint of suppressing image sticking caused by long-term AC driving, it is preferable to contain at least one type of diamine selected from the following formula (3), the following formula (4), and the following formula (5). .

In the above formulas (3) to (5), A ₁ and A ₄ each independently represent a single bond, -CO-O-, -OCO-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ - (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group) group), a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or -CH ₂ - of the divalent chain hydrocarbon group is replaced by -O-, -CO-, -CO-O-, -NRCO-(R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ -(R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group), -NR- (R represents a methyl group), a group (h1) substituted by a group selected from a group selected from pyrrolidine, piperidine and piperidine. Furthermore, the chain hydrocarbon groups of _A1 and _A4 and a part of the hydrogen atoms of the group (h1) may be replaced by an alkyl group having 1 to 3 carbon atoms such as a methyl group, a halogen atom such as a fluorine atom or a chlorine atom. Or all of them. A ₂ is a hydrogen atom, a halogen atom, a hydroxyl group, an amine group, a thiol group, a nitro group, a phosphate group or a monovalent organic group having 1 to 20 carbon atoms. A ₃ represents a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or -CH ₂ - of the divalent chain hydrocarbon group is replaced by -O-, -CO-, -CO-O-, -NRCO-(R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ -(R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group), -NR- (R represents a methyl group), a group (h2) substituted by a group selected from pyrrolidine, piperidine, and piperazine. Furthermore, part or all of the hydrogen atoms contained in the chain hydrocarbon group of _A3 and the group (h2) may be replaced by an alkyl group having 1 to 3 carbon atoms such as a methyl group or a halogen atom such as a fluorine atom or a chlorine atom. . a is an integer from 1 to 4, and when a is 2 or more, the structures of A ₂ may be the same or different. b and c are integers of 1 or 2. d is an integer of 0 or 1).

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include methanediyl, ethanediyl, n-propanediyl, isopropanediyl, n-butanediyl, and isobutanediyl. The second butanediyl, the third butanediyl, etc. alkylenediyl; the alkenediyl such as ethylenediyl, propylenediyl, butenediyl, etc.; the acetylenediyl, propynediyl, butynediyl Etc. Alkyne diyl and so on.

Examples of the monovalent organic group having 1 to 20 carbon atoms in A ₂ include a divalent chain hydrocarbon group having 1 to 20 carbon atoms in the above-mentioned A ₃ , a group (h2), a methyl group, or the like. Examples include groups in which part or all of the hydrogen atoms of the bivalent chain hydrocarbon group having 1 to 20 carbon atoms and the hydrogen atoms of the group (h2) are replaced with halogen atoms such as 1 to 3 alkyl groups or fluorine atoms or chlorine atoms. Or the base after adding 1 hydrogen atom, etc.

In order to suppress image sticking caused by long-term AC driving, the above formula (3) and the above formula (4) are preferably the following formulas (DA-3-1), (DA-4-1) to (DA- 4-24), (DA-5-1)~(DA-5-3). Among them, (DA-3-1), (DA-4-1)~(DA-4-11), (DA-4-13)~(DA-4-24), (DA-5- 1)~(DA-5-2).

The content of the diamine represented by the above formula (3), formula (4) or formula (5) is preferably 50 to 100 mol%, more preferably 70 mol% to 100 mol% relative to 1 mole of the diamine component. Mol%.

From the viewpoint of improving the solubility of the polymer, the diamine used for producing the specific polymer of the present invention preferably contains a diamine represented by the following formula (8). In the above formula (8), Y ₆ is a divalent organic group containing a structure represented by the following formula (9); A ₆ is each independently a hydrogen atom, or an alkyl group having 1 to 5 carbon atoms, or an alkyl group having 2 to 2 carbon atoms. Alkenyl group of 5 or alkynyl group with 2 to 5 carbon atoms. From the viewpoint of liquid crystal alignment, A ₆ is preferably a hydrogen atom or a methyl group.

D is the third butoxycarbonyl group.

Specific examples of the divalent organic group containing the structure represented by the above formula (9) include the following formula (J-1) or formula (J-2).

In the above formulas (J-1) and (J-1), *1 represents a bond to NH-A ₆ , Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer from 1 to 20), Or any -CH ₂ - of -(CH ₂ ) _n - is replaced by -O-, -COO-, -OCO-, -NR-, -NRCO-, -CONR-, under the condition that they are not adjacent to each other. -NRCONR-, -NRCOO-, -OCOO-, R represents a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) ₂ . Q ₈ represents -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) ₂ . D represents tert-butoxycarbonyl group. However, at least one of Q ₅ , Q ₆ and Q ₇ has a third butoxycarbonyl group (Boc) in the group. More preferably, it is a divalent organic group represented by the following formulas (J-1-a) to (J-1-d) or (J-2-1).

The diamine used for polymerization of the specific polymer of the present invention may include a diamine represented by the following formula (10) in addition to the above formulas (3) to (5) and (8). In the above formula (10), A ₈ is each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal alignment, A ₈ is preferably a hydrogen atom or a methyl group. Y ₈ is a divalent organic group, and examples thereof include groups represented by any one of the formulas (Y-1) to (Y-167) described in WO2018/117239 pamphlet, and the like.

＜Manufacturing methods of polyamide ester, polyamide acid and polyimide＞ The polyamide ester, polyamide acid and polyimide precursor used in the present invention can be synthesized by a well-known method described in International Publication No. WO2013/157586, for example.

＜Liquid crystal alignment agent＞ The liquid crystal alignment agent of the present invention has a solution form in which polymer components such as a specific polymer are dissolved in an organic solvent. The molecular weight of the specific polymer is preferably from 2,000 to 500,000, more preferably from 5,000 to 300,000, and even more preferably from 10,000 to 100,000. Moreover, the number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and particularly preferably 5,000 to 50,000.

The liquid crystal alignment agent of the present invention is a composition containing the above-mentioned specific polymer and an organic solvent, and may also contain two or more specific polymers with different structures. In addition, the liquid crystal alignment agent of the present invention may also contain polymers other than the specific polymer (hereinafter also referred to as the second polymer) or various additives.

When the liquid crystal alignment agent of the present invention contains the second polymer, the ratio of the specific polymer to all polymer components is preferably 5 mass % or more, and examples thereof include 5 to 95 mass %.

Examples of the second polymer include polyamic acid, polyimide, polyamide ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, and polyacetal. Polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylate, etc. In particular, a polyamic acid (hereinafter also referred to as a second polyamic acid) obtained from a tetracarboxylic dianhydride component and a diamine component is suitable as the second polymer.

Examples of the tetracarboxylic acid component used to obtain the second polyamic acid include tetracarboxylic dianhydride represented by the following formula (11). The tetracarboxylic dianhydride may be of two or more types. In the above formula (11), A is a tetravalent organic group, preferably a tetravalent organic group having 4 to 30 carbon atoms.

The following shows a preferred structure of the above-mentioned A, but the present invention is not limited thereto.

Among the above structures, (A-1) and (A-2) are preferred from the viewpoint of further improving photo-alignment, and (A-1) is preferred from the viewpoint of further improving the relaxation speed of accumulated charge. -4), from the viewpoint of further improving the liquid crystal alignment and the relaxation speed of accumulated charges, (A-15) to (A-17) are preferred. The tetracarboxylic dianhydride component used to obtain the second polyamic acid may be one type of tetracarboxylic dianhydride, or two or more types of tetracarboxylic dianhydride may be used in combination.

The diamine component used to obtain the second polyamide acid can be appropriately determined according to the purpose. For example, a diamine represented by the following formula (12) can be used. (Y ₉ represents a divalent organic group; A ₉ is each independently a hydrogen atom, or an alkyl group with 1 to 5 carbon atoms, an alkenyl group with 2 to 5 carbon atoms, or an alkynyl group with 2 to 5 carbon atoms; from liquid crystal alignment From the viewpoint of properties, A ₉ is preferably a hydrogen atom or a methyl group).

For the purpose of improving electrical characteristics or relaxing characteristics, Y ₉ is preferably a divalent organic group having a tertiary nitrogen atom or a divalent organic group having -NH-CO-NH- in the molecule. Specific examples of formula (12) when Y ₉ is a divalent organic group having a tertiary nitrogen atom include diamines having a pyrrole structure described in International Publication No. WO2017/126627, and the preferred formula is the following formula ( The diamine shown in pr).

In the above formula (pr), R ¹ represents a hydrogen atom, hydrogen, fluorine atom, cyano group, hydroxyl group or methyl group; R ² each independently represents a single bond or group "*1-R ³ -Ph-*2", R ³ represents a divalent organic group selected from a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- (l and m represent integers from 1 to 5), *1 represents the site bonded to the benzene ring in formula (pr), *2 represents the site bonded to the amine group in formula (pr); Ph represents benzene extension Base; n represents 1~3. The diamine having a pyrrole structure described in International Publication WO2018/062197 is preferably a diamine having a structure represented by the following formula (pn).

(R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents a single bond or group "*1-R ⁴ -Ph-*2", R ⁴ represents a single bond, -O-, -COO- , -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH- and -NHCO- divalent organic groups selected (l and m represent integers from 1 to 5), * 1 represents the site bonded to the benzene ring in the formula (pn), *2 represents the site bonded to the amine group in the formula (pn); Ph represents the phenyl group; n represents 1 to 3), International Publication Gazette WO2018 The diamine having a carbazole structure described in /110354 is preferably a diamine having a structure represented by the following formula (cz).

(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a methyl group), the diamine having a nitrogen-containing heterocycle described in paragraphs [0173] to [0188] of International Publication WO2015/046374 or Japanese Patent Application Laid-Open No. 2016-218149 The diamine having a nitrogen-containing structure described in paragraph [0050] of Publication No. 1, and the diamine represented by the following formula (BP).

(X is a biphenyl ring or a fluorine ring, Y is a benzene ring, a biphenyl ring or a group selected from -phenyl-Z-phenyl-, Z is -O-, -NH-, -CH ₂ -, - Divalent group represented by SO ₂ -, -C(CH ₃ ) ₂ - or C(CF ₃ ) ₂ -; A and B are hydrogen atoms or methyl groups), 2,3-diaminopyridine, 2,6 -Diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyridine, 5,6-diamino- 2,4-dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-trisulfate, 1,4-bis(3-aminopropyl)piperdine, 4 ,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]diphenylamine, 2,4-diamino-6-isopropoxy-1 , 3,5-trisulfate, 2,4-diamino-6-methoxy-1,3,5-trisphenyl, 2,4-diamino-6-phenyl-1,3,5- Tris, 2,4-diamino-6-methyl-s-tris, 2,4-diamino-1,3,5-tris, 4,6-diamino-2-vinyl -s-Tris-triazole, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino- 6-Phenylphenanthridine, 1,4-diaminopiperdine, 3,6-diaminoacridine, bis(4-aminophenyl)phenylamine, 4,4'-diphenylmethyl Amine, 4,4'-diphenylamine, 3,6-diaminocarbazole, 9-methyl-3,6-diaminocarbazole, 9-ethyl-3,6-diaminocarbazole Azoles, diamines represented by the following formulas (w1) to (w2), etc.

(Sp is a phenylene group, pyrrolidine, piperidine, piperidine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or -CH ₂ - of the divalent chain hydrocarbon group is replaced by -O-, -CO- , -CO-O-, -NRCO-(R represents a hydrogen atom or methyl group), -NRCOO-(R represents a hydrogen atom or methyl group), -CONR-(R represents a hydrogen atom or methyl group), -COS-, -NR- (R represents methyl), a group substituted by a group selected from pyrrolidine, piperidine, and piperidine).

Specific examples of the above formula (12) when Y ₉ is a divalent organic group having -NH-CO-NH- in the molecule include A ₁ in the above formula (4) being -NH-CO-NH- , or at least one -CH ₂ - of a chain hydrocarbon group having 2 to 20 carbon atoms substituted by -NH-CO-NH-, or at least one -CH ₂ - of a chain hydrocarbon group having 2 to 20 carbon atoms Replaced by -NH-CO-NH- and at least one of the other -CH ₂ - is replaced by -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or methyl group), -NRCOO - (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group) and the like when the group is substituted by a selected group. Specific examples of more preferred diamines include diamines represented by the following formulas (U-1) to (U-9).

Preferable specific examples of the diamine represented by the above formulas (w1) to (w2) include diamines represented by the following formulas (n3-1) to (n3-7), diamines represented by the following formula (n4- Diamines shown in 1)~(n4-6), etc.

For the purpose of improving printability, a diamine compound having a carboxyl group (COOH group) or a hydroxyl group (OH group) can also be used. Specific examples include 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, and 4,6-diaminobenzyl alcohol. Aminoresorcinol, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid. Among them, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid is preferred. Moreover, diamine compounds represented by the following formula [3b-1] to formula [3b-4] and diamine compounds in which the amine group is a secondary amine group can also be used.

(In formula [3b-1], Q ¹ represents a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON( CH ₃ )- or N(CH ₃ )CO-, m ¹ and m ² each independently represent an integer from 0 to 4, and m ¹ +m ² represents an integer from 1 to 4. In formula [3b-2], m ³ and m ⁴ each independently represent an integer from 1 to 5. In the formula [3b-3], Q ² represents a linear or branched alkylene group with 1 to 5 carbon atoms, and m ⁵ represents an integer from 1 to 5. The formula [ 3b-4], Q ³ and Q ⁴ each independently represent a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON(CH ₃ )- or N(CH ₃ )CO-, m ⁶ represents an integer from 1 to 4).

As the diamine component used to obtain the second polyamic acid, in addition to the above, diamines used in specific polymers or well-known diamines can be used, but the present invention is not limited thereto. The diamine component system used to obtain the second polyamide acid may be one type of diamine, or two or more types of diamines may be used in combination.

The molecular weight of the second polymer contained in the liquid crystal alignment agent of the present invention is not particularly limited as long as it can form a uniform and defect-free coating film on the substrate. The preferred weight average molecular weight and number average molecular weight are The same is true for specific polymers.

Examples of various additives added to the above-mentioned liquid crystal alignment agent include dielectrics or conductive substances for the purpose of changing the electrical properties such as dielectric properties or conductivity of the liquid crystal alignment film, and for improving the adhesion between the liquid crystal alignment film and the substrate. A silane coupling agent for the purpose of improving the properties of the liquid crystal alignment film, a cross-linking compound for the purpose of improving the hardness or density of the film when forming a liquid crystal alignment film, and a silane coupling agent for imidizing the polyamide acid when the coating film is fired. An accelerator for the purpose of efficiently carrying out imidization, etc.

As the cross-linking compound, it is preferable to add a cross-linking compound having a substituent such as an epoxy group, an isocyanate group, an oxetanyl group, a cyclic carbonate group, a blocked isocyanate group, a hydroxyl group or an alkoxy group, and At least one compound from the group of crosslinkable compounds having a polymerizable unsaturated group. In addition, from the viewpoint of improving crosslinkability, it is preferable that the crosslinkable compound has two or more substituents or polymerizable unsaturated bonds. Specific examples of the crosslinking compound include compounds having an epoxy group or an isocyanate group, compounds having an oxetanyl group, and compounds described in paragraphs [0169] to [0190] of International Publication No. 2011/132751. Amino resins having hydroxyl groups, alkoxy groups or lower alkoxyalkyl groups, benzene or phenolic compounds having hydroxyl groups or alkoxy groups, and those described in paragraphs [0103] to [0112] of International Publication No. 2012/014898 Compounds having a cyclic carbonate group, compounds having a hydroxyalkylamide group described in International Publication No. 2015/072554, compounds having blocked isocyanate groups described in International Publication No. 2015/141598, etc.

More preferred specific examples of the crosslinking compound include those represented by the following formulas (CL-1) to (CL-13), Takenate B-830, and Takenate B-882 (all manufactured by Mitsui Chemicals Co., Ltd.).

Relative to 100 parts by mass of all polymer components contained in the liquid crystal alignment agent, the content of the cross-linking compound is preferably 0.1 to 100 parts by mass. From the perspective of improving the alignment properties of the liquid crystal, the content of the cross-linking compound is more preferably 0.1 to 50 parts by mass. parts, preferably 1 to 50 parts by mass.

Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, and 2-aminopropyltriethoxysilane. Propyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl) )-3-Aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilyl Propyl triethylene triamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonylacetate, 9-triethoxysilyl-3,6-diazanonylacetate, N-benzyl-3- Aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-amine Triethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyl Trimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styrene group Trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyl Diethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, ginseng-(trimethoxysilylpropyl)isocyanuric acid acid ester, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, etc. When using such a silane coupling agent, from the viewpoint of ensuring liquid crystal alignment, it is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass relative to 100 parts by mass of all polymer components contained in the liquid crystal alignment agent. parts by mass.

The concentration of the polymer containing the specific polymer in the liquid crystal alignment agent of the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed. Among them, the content is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and the content is preferably 10% by mass or less from the viewpoint of storage stability of the solution. The optimal polymer concentration is 2 to 8% by mass.

The organic solvent contained in the liquid crystal alignment agent of the present invention is not particularly limited as long as the polymer component can be dissolved uniformly. Specific examples thereof include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methyl-2- Pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfoxide , γ-butyrolactone, 1,3-dimethyl-imidazolinone, 3-methoxy-N,N-dimethylpropanamide, etc. These systems can be used alone or in combination of two or more types. Furthermore, even if the solvent cannot uniformly dissolve the polymer component alone, it can be mixed with the above-mentioned organic solvent as long as the polymer does not precipitate.

In addition to the organic solvent used to dissolve the polymer component, the liquid crystal alignment agent of the present invention may also contain a solvent used to improve the uniformity of the coating film when the liquid crystal alignment agent is applied to the substrate. This solvent generally uses a solvent with a lower surface tension than the above-mentioned organic solvent. Specific examples thereof include ethyl cellosole, butyl cellosole, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, and 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, butyl cellulose acetate, dipropylene glycol, 2-(2-ethoxy Propoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, diacetone alcohol, diisobutyl ketone, dipropylene glycol monomethyl ether, diisobutyl methanol, etc. These solvents may be used in combination of two types.

＜Manufacturing method of liquid crystal alignment film＞ The manufacturing method of a liquid crystal alignment film using the liquid crystal alignment agent of the present invention is as described above, and is characterized by proceeding in sequence: the step of applying the liquid crystal alignment agent (step (A)), and the step of firing the coating film obtained in step (A). The step (step (B)), the step (step (C)) of irradiating polarized ultraviolet light to the film obtained in step (B), and the step (step (C)) of irradiating the film obtained in step (C) to a temperature above 100°C and higher than that in step (B). The step of firing at high temperature (step (D)).

＜Step (A)＞ The substrate on which the liquid crystal alignment agent used in the present invention is coated is not particularly limited as long as it is highly transparent. Glass substrates, silicon nitride substrates, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used. At that time, it was preferable from the viewpoint of simplifying the manufacturing process to use a substrate on which ITO electrodes for driving liquid crystals are formed. In addition, when only one side of the substrate is used in a reflective liquid crystal display element, an opaque material such as a silicon wafer may be used. In this case, a material that reflects light such as aluminum may be used as the electrode. The coating method of the liquid crystal alignment agent is not particularly limited, but industrially it is generally carried out by screen printing, offset printing, flexographic printing or inkjet method. As other coating methods, there are dipping method, roll coating method, slit coating method, spin method, spray method, etc., and these can be used according to the purpose.

＜Step (B)＞ Step (B) is a step of burning the liquid crystal alignment agent coated on the substrate to form a film. After the liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated by heating means such as a hot plate, a thermal cycle oven or an IR (infrared) oven, or the amide or amide in the polymer can be removed. Thermal imidization of esters. The drying and firing steps after coating the liquid crystal alignment agent of the present invention can be carried out at any temperature and time, or can be carried out multiple times. The temperature of the organic solvent for removing the liquid crystal alignment agent can be, for example, in the range of 40 to 150°C. From the perspective of shortening the process, it can be carried out at 40~120℃. The firing time is not particularly limited, but examples include a firing time of 1 to 10 minutes or 1 to 5 minutes. When performing thermal imidization of amide acid or amide ester in the polymer, the step of removing the above-mentioned organic solvent can be followed by firing at a temperature range of 190 to 250°C or 200 to 240°C, for example. steps. The firing time is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes.

<Step (C)> Step (C) is a step of irradiating polarized ultraviolet rays to the film obtained in step (B). As ultraviolet rays, it is preferable to use ultraviolet rays having a wavelength of 200 to 400 nm, and more preferably, ultraviolet rays having a wavelength of 200 to 300 nm. In order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film can be heated at 50 to 250°C while irradiating it with ultraviolet rays. In addition, the irradiation dose of the above-mentioned radiation is preferably 1 to 10,000 mJ/cm ² . Among them, 100 to 5,000 mJ/cm ² is preferred. The liquid crystal alignment film system produced in this way can stably align liquid crystal molecules in a certain direction. The higher the extinction ratio of the polarized ultraviolet rays, the higher the anisotropy can be imparted, which is preferable. Specifically, the extinction ratio of ultraviolet light polarized into a straight line is preferably 10:1 or more, and more preferably 20:1 or more.

＜Step (D)＞ Step (D) is a step in which the film obtained in step (C) is fired at a temperature above 100° C. and higher than that in step (B). The firing temperature is not particularly limited as long as it is 100°C or higher and higher than the firing temperature in step (B), but it is preferably 150~300°C, more preferably 150~250°C, and particularly preferably 200~250°C. ℃. The firing time is preferably 5 to 120 minutes, more preferably 5 to 60 minutes, particularly preferably 5 to 30 minutes. If the thickness of the liquid crystal alignment film after firing is too thin, the reliability of the liquid crystal display element may be reduced, so the thickness is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

Furthermore, after performing any of the above steps (C) or (D), water or a solvent can also be used to contact the obtained liquid crystal alignment film. The solvent used in the contact treatment is not particularly limited as long as it can dissolve decomposition products generated from the liquid crystal alignment film due to irradiation with ultraviolet rays. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, Butylcellulose, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate or cyclohexyl acetate wait. Among these, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate is preferred from the viewpoint of versatility and solvent safety. More preferably, it is water, 1-methoxy-2-propanol or ethyl lactate. The solvent may be one type or a combination of two or more types.

The above-mentioned contact treatment, that is, treating the liquid crystal alignment film with water or solvent after irradiating polarized ultraviolet rays, may include immersion treatment or spray treatment (also called spray treatment). The processing time of these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving decomposition products generated from the liquid crystal alignment film due to ultraviolet rays. Among them, it is preferable to perform the immersion treatment for 1 minute to 30 minutes. In addition, the solvent during the above contact treatment may be at normal temperature or heated, but is preferably 10 to 80°C. Among them, 20 to 50°C is preferred. In addition, from the viewpoint of the solubility of the decomposed products, ultrasonic treatment, etc. may be performed if necessary.

After the above contact treatment, it is preferable to perform cleaning (also called rinsing) with a low-boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone or methyl ethyl ketone or calcining the liquid crystal alignment film. At that time, either washing or firing can be performed, or both can be performed. The preferred firing temperature is 150~300℃. Among them, 180 to 250°C is preferred, and 200 to 230°C is more preferred. Moreover, the firing time is preferably 10 seconds to 30 minutes. Among them, 1 to 10 minutes is preferred.

The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for transverse electric field liquid crystal display elements such as IPS mode or FFS mode, and is particularly suitable as a liquid crystal alignment film for FFS mode liquid crystal display elements. The liquid crystal display element is obtained by obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, then producing a liquid crystal cell by a known method, and using the liquid crystal cell. As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element with a passive matrix structure is taken as an example for description. Furthermore, a liquid crystal display element with an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided on each pixel portion constituting the image display may be used.

Specifically, transparent glass substrates are prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be used as ITO electrodes, for example, and are patterned to display desired images. Then, an insulating film is placed on each substrate to cover the common electrode and the segment electrode. The insulating film may be, for example, a SiO ₂ -TiO ₂ film formed by a sol-gel method. Next, a liquid crystal alignment film is formed on each substrate, and one substrate is stacked on the other substrate so that the liquid crystal alignment film surfaces face each other, and the periphery is connected with a sealant. In the sealant, spacers are usually mixed in advance in order to control the substrate gap, and it is preferable that spacers for substrate gap control are also spread in advance on the in-plane portions where the sealant is not provided. An opening that can be filled with liquid crystal from the outside is provided in a part of the sealant. Next, the liquid crystal material is injected into the space surrounded by the two substrates and the sealant through the opening provided in the sealant, and then the opening is sealed with adhesive. During the injection, a vacuum injection method can be used, or a method utilizing capillary phenomena in the atmosphere can be used. As the liquid crystal material, either a positive liquid crystal material or a negative liquid crystal material can be used. Next, set up the polarizer. Specifically, a pair of polarizing plates is attached to the surface of the two substrates opposite to the liquid crystal layer.

As described above, by using the manufacturing method of the present invention, a liquid crystal alignment film can be obtained that suppresses the image sticking caused by long-term AC driving in an IPS-driven or FFS-driven liquid crystal display element and does not contain low molecular weight compounds. Defects such as bright spots caused by remaining parts can be produced with fewer steps than before. Example

The following examples are given to illustrate the present invention in more detail, but the present invention is not limited thereto. The abbreviations of the compounds below and the measurement methods of each characteristic are as follows. (diamine)

(Boc represents tertiary butoxycarbonyl)

(Tetracarboxylic dianhydride) CA-X-1: Compound represented by the following formula (CA-X-1) (Compound C) c-1: Compound represented by the following formula (c-1) (other additives) LS-4668: 3-glycidoxypropyltriethoxysilane (the following (s-1) compounds shown)

(Organic solvent) NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone, BCS: butylcellosine.

＜Measurement of acyl imidization rate＞ Place 20 mg of polyimide powder into an NMR sample tube (NMR standard sampling tube, φ5 (manufactured by Kusano Scientific Co., Ltd.)), add deuterated dimethylsulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane)) and mix product) 0.53ml, apply ultrasound to completely dissolve it. This solution was measured for proton NMR at 500 MHz using an NMR measuring machine (JNW-ECA500, manufactured by JEOL DATUM Corporation). The rate of imidization is determined by using protons from a structure that does not change before and after imidization as a reference proton, and using the peak accumulation value of this proton and the value of the NH group derived from amide acid that appears around 9.5 ppm ~ 10.0 ppm. The proton wave peak accumulation value is obtained by the following formula. Imination rate (%) = (1-α・x/y)×100 In the above formula, x is the peak accumulation value of protons derived from the NH group of amide acid, y is the peak accumulation value of reference protons, and α is the relative value in the case of polyamide acid (imidation rate of 0%) The NH base proton of amide acid is 1, which is the ratio of the number of standard protons.

[Synthesis of polymers] ＜Synthesis example 1＞ In a four-necked flask equipped with a stirring device and a nitrogen pipe, weigh 3.62g (14.8mmol) of DA-h-1, 4.75g (14.8mmol) of DA-h-2, and 1.92g (17.8mmol). DA-i-1 and 4.05 g (11.9 mmol) of DA-j-1 were added with NMP so that the solid content concentration became 12% by mass, and they were stirred and dissolved while feeding nitrogen gas. While stirring the obtained solution, 10.1g (45.2mmol) of CA-1-1, 2.12g (8.5mmol) of CA-2-1 and 0.83g (2.8mmol) of CA-3-1 were added, and the solid content was added NMP was added so that the concentration becomes 15% by mass. Next, the mixture was stirred at 40° C. for 24 hours to obtain a polyamide solution.

In a 100 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, 30.0 g of the obtained polyamide solution was taken, NMP was added so that the solid content concentration became 10% by mass, and the mixture was stirred for 30 minutes. To the obtained polyamic acid solution, 2.80 g of acetic anhydride and 1.50 g of pyridine were added, and the mixture was heated at 55° C. for 3 hours to perform chemical imidization. The obtained reaction liquid was added to methanol in an amount 3.5 times the mass of the reaction liquid while stirring, and the precipitated precipitate was collected by filtration, and then washed three times with methanol. The obtained resin powder was dried at 60° C. for 12 hours to obtain polyimide (PI-A-1) powder. The imidization rate of this polyimide resin powder is 62%. NMP was added to the obtained polyimide (PI-A-1) and stirred at 70° C. for 24 hours to obtain a solution of polyimide (PI-A-1) with a solid content concentration of 12 mass %.

＜Synthesis Examples 2~5＞ Using the diamine component, the tetracarboxylic acid component and the organic solvent shown in the following Table 1, the same procedure as Synthesis Example 1 was carried out to obtain the polyimide (PI- Solutions of A-2)~(PI-A-4), (R-PI-1) and polyamide (PAA-B-1)~(PAA-B-3). In addition, regarding the polyamide acids (PAA-B-1) to (PAA-B-3), LS-4668 was added so that the solid content of the polyamide acid would be 1% by mass.

The numerical values in parentheses in Table 1 refer to the tetracarboxylic acid component and represent the blending ratio (mol parts) of each compound relative to 100 mole parts of the total amount of the tetracarboxylic acid components used in the synthesis. Regarding the diamine acid component , represents the blending ratio (mol parts) of each compound relative to 100 mol parts of the total amount of diamine components used for synthesis. Regarding the organic solvent, it means the blending ratio (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents used for synthesis.

[Preparation of liquid crystal alignment agent] <Example 1> The solution of the polyimide (PI-A-1) obtained in Synthesis Example 1 was diluted with NMP and BCS, and stirred at room temperature. Next, the obtained solution was filtered through a filter with a pore size of 0.5 μm to obtain a liquid crystal alignment agent (1) with a solvent composition ratio (NMP: BCS = 80: 20 (mass ratio)) and a polymer solid content concentration of 6 mass %. (Refer to Table 2 below). In this liquid crystal alignment agent, no abnormalities such as turbidity or precipitation were observed, and it was confirmed to be a homogeneous solution.

<Examples 2 to 4, Comparative Example 1> Except using the respective polymers shown in Table 2 below, the liquid crystal alignment agents (2) to (4) and (R1) were obtained in the same manner as in Example 1.

<Examples 5 to 7, Comparative Example 2> The solution of polyimide (PI-A-2) obtained in Synthesis Example 2 and the solution of polyamide (PAA-B-1) obtained in Synthesis Example 6 were diluted with NMP, GBL and BCS, and further Compound (c-1) was added so as to become 3 parts by mass relative to 100 parts by mass of the total polymer, and stirred at room temperature. Then, the obtained solution was filtered through a filter with a pore size of 0.5 μm, and the component ratio of the polymer was (PI-A-2): (PAA-B-1) = 40: 60 (solid content conversion mass ratio), solvent The liquid crystal alignment agent (1) has a composition ratio of NMP:GBL:BCS=50:30:20 (mass ratio) and a polymer solid content concentration of 6 mass% (see Table 2 below). In this liquid crystal alignment agent, no abnormalities such as turbidity or precipitation were observed, and it was confirmed to be a homogeneous solution.

In Table 2, the numerical values in parentheses refer to the polymer and compound (C), and represent the blending amount of each polymer component or compound (C) relative to 100 parts by mass of the total polymer components used in the preparation of each liquid crystal alignment agent. Total proportion (mass parts). Regarding the organic solvent, it means the blending ratio (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents used in the preparation of the liquid crystal alignment agent.

[Production of liquid crystal display components] A liquid crystal cell composed of an FFS mode liquid crystal display element is produced. First, prepare a substrate with electrodes attached. The substrate is a glass substrate with a size of 30mm×50mm and a thickness of 0.7mm. An ITO electrode with a solid pattern constituting the counter electrode is formed on the substrate as the first layer. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by a CVD method is formed as a second layer. The SiN film of the second layer has a film thickness of 500 nm and functions as an interlayer insulating film. On the SiN film of the second layer, a comb-shaped pixel electrode formed by patterning the ITO film is arranged as the third layer, and two pixels of the first pixel and the second pixel are formed. The size of each pixel is 10mm vertically and approximately 5mm horizontally. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the SiN film of the second layer.

The pixel electrode of the third layer has a comb-tooth shape formed by arranging a plurality of electrode elements in a "U" shape with a central portion bent into an internal angle of 160°. The width of each electrode element in the short side direction is 3 μm, and the interval between electrode elements is 6 μm. The pixel electrode that forms each pixel is composed of a plurality of "U"-shaped electrode elements with a curved central part. Therefore, the shape of each pixel is not a rectangular shape, but has a central part similar to the electrode element. It is curved and has the shape of a bold "ㄑ" character. Furthermore, each pixel is divided into upper and lower parts with a central curved portion as a boundary, and has a first region above the curved portion and a second region below the curved portion.

Next, a liquid crystal alignment agent was applied to the substrate with electrodes and the glass substrate having columnar spacers with a height of 4 μm formed of an ITO film on the back surface by a spin coating method. After drying on a hot plate at 80°C for 2 minutes, irradiate the coating surface with linearly polarized ultraviolet light of a wavelength of 254nm with an extinction ratio of 26:1 through a polarizing plate, and then dry it in a hot air circulation oven at 230°C for 30 minutes. After firing, a substrate with a liquid crystal alignment film having a film thickness of 100 nm was obtained. In addition, the liquid crystal alignment film formed on the above-mentioned substrate with electrodes is aligned so that the direction that bisects the inner angle of the pixel curved portion is orthogonal to the alignment direction of the liquid crystal, and is formed on the second glass substrate. The liquid crystal alignment film is aligned so that the alignment direction of the liquid crystal on the first substrate becomes consistent with the alignment direction of the liquid crystal on the second substrate when the liquid crystal cell is produced. The two obtained substrates with liquid crystal alignment films were treated as a set, and a sealant was printed on the substrates in the form of remaining liquid crystal injection ports, and the other substrate was bonded so that the liquid crystal alignment film surfaces faced each other. Then, the sealant was hardened to produce empty cells with a cell gap of 4 μm. In this empty cell, liquid crystal MLC-3019 (manufactured by MERCK) was injected by a reduced pressure injection method, and the injection port was closed to obtain an FFS-type liquid crystal display element. Then, the obtained liquid crystal display element was heated at 120°C for 1 hour and left at 23°C overnight, and then used for evaluation.

[Evaluation] ・Evaluation of irradiation dose margin The liquid crystal display element obtained above was subjected to an AC voltage of ±5V with a frequency of 60Hz for 120 hours in a constant temperature environment of 60°C. Then, the pixel electrode and the counter electrode of the liquid crystal display element were short-circuited, and left at room temperature for one day. For the liquid crystal display element that has undergone the above process, in the state where no voltage is applied, the deviation between the alignment direction of the liquid crystal in the first area of the pixel and the alignment direction of the liquid crystal in the second area is calculated as an angle. Specifically, a liquid crystal display element is placed between two polarizing plates arranged so that their polarization axes are orthogonal, a backlight is turned on, and the liquid crystal cell is adjusted so that the intensity of transmitted light in the first region of the pixel is minimized. Arrangement angle, and then find the rotation angle (hereinafter referred to as Δ _ac ) required to rotate the liquid crystal cell in such a way that the intensity of the transmitted light in the second area of the pixel is minimized. Using the minimum light exposure dose E _min (mJ/cm ² ) and the maximum light exposure dose E _max (mJ/cm ² ) where _Δac does not reach 0.15°, the following three-level index is used for evaluation. The evaluation results are shown in Table 3 below.

Excellent: The difference between E _max and E _min is 300mJ/cm ² or more. Good: The difference between E _max and E _min is 200 mJ/cm ² or more but less than 300 mJ/cm ² . Defective: The difference between E _max and E _min is less than 200mJ/cm ² .

As mentioned above, the liquid crystal alignment film obtained from the liquid crystal alignment agents (1) to (7) used in Examples 1 to 7 of the present invention is irradiated with a light irradiation dose of 150 to 350 mJ/cm ² or 150 to 450 mJ/cm ² When , △ _ac does not reach 0.15°, showing good image retention characteristics. On the other hand, the liquid crystal alignment agents (R1) to (R2) used in Comparative Examples 1 to 2 showed good image retention even though _Δac did not reach 0.15° when irradiated with a light irradiation dose of 150 to 250 mJ/cm ² However, when irradiated with a light irradiation dose of 350mJ/ ^cm2 , _Δac becomes 0.15° or more, and good image sticking characteristics cannot be obtained. From the above, it can be seen that by using the liquid crystal alignment agent of the present invention, a liquid crystal alignment film that can expand the margin of light irradiation and has good image sticking characteristics can be obtained. Therefore, the liquid crystal alignment film system obtained from the liquid crystal alignment agent of the present invention has a high yield in the manufacture of liquid crystal panels, and can reduce the image sticking caused by AC driving that occurs in IPS-driven or FFS-driven liquid crystal display elements. Obtain an IPS-driven or FFS-driven liquid crystal display element with excellent image sticking characteristics. Possibility of industrial use

The liquid crystal alignment agent of the present invention can be used to form liquid crystal alignment films in a wide range of liquid crystal display elements such as IPS driving mode or FFS driving mode. In addition, the entire contents of the specification, patent application scope, drawings and abstract of Japanese Invention Patent Application No. 2018-216789 filed on November 19, 2018 are quoted here and incorporated as the disclosure of the specification of the present invention.

Claims (14)

A liquid crystal alignment agent characterized by containing: tetracarboxylic dianhydride or its derivative represented by the following formula (1), tetracarboxylic dianhydride represented by the following formula (2) or its derivative And a polyimide which is an imide product of a polyimide precursor obtained by the polymerization reaction of a tetracarboxylic acid component and a diamine component of an aromatic tetracarboxylic dianhydride represented by the following formula (6);

(X ₁ is a structure represented by any one of the following formulas (X1-1) to (X1-4); X ₂ is a structure represented by the following formula (X2-1) or (X2-2); ₃ series is an aromatic ring with 4 bonds);

(R ₃ ~ R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkynyl group with 2 to 6 carbon atoms, or a fluorine atom containing 1 carbon group. ~6 monovalent organic groups, or phenyl groups, and at least one of them is other than a hydrogen atom; R ₇ ~ R ₂₃ are each independently a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, or an alkyl group with 2 to 6 carbon atoms. Alkenyl group, alkynyl group with 2 to 6 carbon atoms, monovalent organic group with 1 to 6 carbon atoms containing a fluorine atom, or phenyl group);

The liquid crystal alignment agent of claim 1, wherein the polyimide has an imidization rate of 10 to 100%. The liquid crystal alignment agent of claim 1 or 2, wherein the tetracarboxylic acid component contains 1 to 30 mol% of the tetracarboxylic dianhydride represented by the formula (2) or a derivative thereof relative to the tetracarboxylic acid component. things. The liquid crystal alignment agent of claim 1 or 2, wherein the tetracarboxylic acid component contains 1 to 20 mol% of the tetracarboxylic dianhydride represented by the formula (6) or a derivative thereof relative to the tetracarboxylic acid component. things. The liquid crystal alignment agent of claim 1 or 2, wherein in the aforementioned formula (1), _X1 is at least one selected from the structure represented by any one of the following formulas (X1-12) to (X1-16) 1 species;

The liquid crystal alignment agent of claim 1 or 2, wherein in the aforementioned formula (2), X ₂ is a structure represented by the aforementioned formula (X2-1). The liquid crystal alignment agent of claim 1 or 2, wherein the diamine component contains at least one selected from the structure represented by any one of the following formula (3), the following formula (4) and the following formula (5). 1 diamine;

(A ₁ and A ₄ each independently represent a single bond, -CO-O-, -OCO-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), - CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ - (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), divalent carbon number 2 to 20 chain hydrocarbon group, or -CH ₂ - of the divalent chain hydrocarbon group is replaced by -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ - (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group) base), -NR-(R represents methyl), pyrrolidine, piperidine, piperazine

The group (h1) substituted by the selected group; A ₂ is a hydrogen atom, a halogen atom, a hydroxyl group, an amine group, a thiol group, a nitro group, a phosphate group or a monovalent organic group having 1 to 20 carbon atoms; and, also The aforementioned chain hydrocarbon groups of A ₁ and A ₄ and one or all of the hydrogen atoms of the group (h1) may be replaced by an alkyl group or a halogen atom having 1 to 3 carbon atoms; A ₃ is a divalent hydroxyl group having 1 to 20 carbon atoms. The chain hydrocarbon group, or -CH ₂ - of the divalent chain hydrocarbon group is represented by -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or methyl group), -NRCOO-( R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR ₂ - (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group ), -NR-(R represents methyl), pyrrolidine, piperidine, piperazine

The group (h2) to which the selected group is substituted; in addition, an alkyl group with 1 to 3 carbon atoms or a halogen atom may be substituted for part or all of the aforementioned chain hydrocarbon group of A ₃ and one or all of the hydrogen atoms of the group (h2); a is an integer from 1 to 4. When a is 2 or more, A ₂ can be the same or different; b and c are each independently an integer of 1 or 2; d is an integer of 0 or 1). Such as the liquid crystal alignment agent of claim 1 or 2, wherein the aforementioned diamine component is selected from the following formula (DA-3-1), (DA-4-1) ~ (DA-4-24), (DA-5 At least one diamine from the group consisting of -1)~(DA-5-3);

A method for manufacturing a liquid crystal alignment film, which has the following steps (A), (B), (C) and (D); Step (A): Coating the liquid crystal alignment according to any one of claims 1 to 8 Step (B): The step of firing the coating film obtained in step (A). Step (C): The step of irradiating polarized ultraviolet rays to the film obtained in step (B). Step (D): The step (D) of burning the coating film obtained in step (A). C) A step in which the obtained film is fired at a temperature above 100°C and higher than that of step (B). The manufacturing method of the liquid crystal alignment film of claim 9, wherein in the aforementioned step (B), the liquid crystal alignment film is fired at 50°C to 150°C. The method for manufacturing a liquid crystal alignment film according to claim 9 or 10, wherein in the aforementioned step (D), the film is fired at 150~300°C. A liquid crystal alignment film obtained by using the liquid crystal alignment agent in any one of claims 1 to 8. A liquid crystal display element provided with the liquid crystal alignment film of claim 12. Such as the liquid crystal display element of claim 13, which uses a transverse electric field to drive the liquid crystal.