TWI704183B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

Provided is a liquid crystal alignment agent, which can obtain a liquid crystal alignment film with excellent rub resistance or stability of liquid crystal alignment, rapid relaxation of accumulated charges, and a small flicker (flicker level) instantaneously after driving, and excellent storage stability.

A liquid crystal alignment agent, which contains a specific repeating unit with a structure of formula (Y1-1) and a polyamide (component A) having a specific repeating unit of formula (Y2-1), and a specific Structure of polyamide acid (component B).

(式中記號的定義與說明書中相同)。

(The definition of the symbol in the formula is the same as in the specification).

Description

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

The present invention relates to a liquid crystal alignment agent used to make a liquid crystal alignment film, a liquid crystal alignment film obtained from the aforementioned liquid crystal alignment agent, and a liquid crystal display element having the aforementioned liquid crystal alignment film.

At present, liquid crystal display elements are widely used in the image display part of various devices such as digital cameras, personal computers, portable terminals, and televisions. Such a liquid crystal display element has a structure in which a fluid liquid crystal composition is sandwiched and sealed by two supporting substrates, and a liquid crystal alignment film for aligning liquid crystal molecules is provided on the surface of the liquid crystal contacting the substrate. The liquid crystal alignment film is generally produced through the step of coating a liquid crystal alignment agent on the aforementioned substrate. In addition, when the liquid crystal molecules are aligned in the in-plane direction of the substrate, the film obtained from the liquid crystal alignment agent is subjected to rubbing treatment or photo-alignment treatment.

Although the basic characteristic of the liquid crystal alignment film is to align the liquid crystal molecules in a specific direction, it is necessary to realize the improvement of other various characteristics of the high-performance liquid crystal display element. Furthermore, in the stable industrial production, the coating of the liquid crystal alignment agent Properties such as cloth property or storage stability are also important. For example, Patent Document 1 discloses a liquid crystal alignment agent whose purpose is to provide A liquid crystal alignment film that is prone to wear or damage to the film caused by rubbing treatment. In addition, Patent Document 2 discloses a liquid crystal alignment agent whose purpose is to provide a film with rub resistance, but also to suppress the deviation of the rubbing direction from the liquid crystal alignment direction, and has a high voltage retention rate when made into a liquid crystal display element. A liquid crystal alignment film that quickly relaxes the accumulated charge.

[Prior technical literature] 〔Patent Literature〕

[Patent Document 1] Pamphlet of International Publication WO2010/053128

[Patent Document 2] Pamphlet of International Publication No. WO2015/122413

With the increasing performance of liquid crystal display elements in recent years, liquid crystal alignment films are seeking to achieve various characteristics in a higher-level manner than today. For example, due to the high-definition of liquid crystal display elements, abrasion and damage smaller than before have also become a problem with regard to friction resistance. It also pursues the characteristics of other complex numbers at the same time.

From the foregoing, the subject of the present invention is to provide a liquid crystal alignment agent with excellent storage stability, which can obtain a liquid crystal alignment film with excellent friction resistance or liquid crystal alignment stability, and a rapid relaxation of the accumulated charge of the liquid crystal display element, and further Flicker (flicker Grade) Small liquid crystal alignment film.

As a result of intensive research, the inventors have finally completed the present invention. The gist of the present invention is as follows.

A liquid crystal alignment agent characterized by containing the following components (A) and (B),

(A) Component: Polyurethane containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

(B) Component: Polyamide acid having a repeating unit represented by the following formula (3).

(In formulas (1) and (2), each of the plural R ^{1 is} independently an alkyl group with 1 to 6 carbons, and the plural R ^{2 is} each independently a hydrogen atom or an alkyl group with 1 to 6 carbons, and Y ¹ is The divalent organic group represented by the following formula (Y1-1), Y ² is the divalent organic group represented by the following formula (Y2-1)).

In the formula (Y1-1), the two R ³ are each independently a single bond, -O-, -S-, -OCO-, or -COO-, and the two R ⁴ are each independently an alkane with a carbon number of 1 to 3 Group, R ⁵ is an oxygen atom or a sulfur atom.

In formula (Y2-1), A ¹ and A ⁵ are each independently a single bond, a methylene group, an alkylene group with 2 to 5 carbon atoms, azetidine diyl, pyrrolidine diyl, or piperidine diyl Group, B ¹ and B ² are each independently a single bond, -O-, -COO-, -OCO-, -CONH-, -NHCO-, -CONCH ₃ -, or -NCH ₃ CO-, A ² and A ⁴ Each independently is a single bond, a methylene group, or an alkylene group with 2 to 5 carbons, A ³ is a methylene group, or an alkylene group with 2 to 6 carbons, a is 0 or 1, and R is a hydrogen atom or Methyl group, D is a protecting group that is replaced by a hydrogen atom due to heat.

In the formula (3), X is a tetravalent organic group, Y is a divalent organic group, and R ⁶ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

According to the present invention, a liquid crystal alignment agent with excellent storage stability can be provided, which can obtain a liquid crystal alignment film with excellent friction resistance or liquid crystal alignment stability, and a relaxation and rapid accumulation of charge of the liquid crystal display element, thereby driving the liquid crystal display element A liquid crystal alignment film with a small subsequent flicker (flicker level), a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a high-performance liquid crystal display element provided with the liquid crystal alignment film can be provided.

<Polyurethane (A)>

The polyamide ester of the aforementioned component (A) is a polyamide ester containing a repeating unit represented by the above formula (1) and a repeating unit represented by the following formula (2).

In formula (1) and formula (2), each of the plural R ^{1 is} independently an alkyl group having 1 to 6 carbon atoms, preferably methyl or ethyl. In addition, in formulas (1) and (2), each of the plural R ^{2 is} independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or a methyl group.

In the formula (1), Y ¹ is a divalent organic group represented by the following formula (Y1-1).

In formula (Y1-1), R ³ , R ⁴ and R ^{5 are} as defined above, wherein R ³ is a single bond, -O- is preferably, R ⁴ is preferably methylene, and R ⁵ is an oxygen atom. good.

Although specific examples of Y ^{1 are} given below, the present invention is not limited to these.

Among the above, (Y1-1-1) to (Y1-1-8) are preferable from the viewpoint of the alignment stability of the liquid crystal. In addition, the (contained) ratio of the repeating unit represented by the formula (1) is preferably 1 to 70 mole% of all repeating units contained in the polyamide ester of component (A), and more preferably 5 ~50 mol%.

In the aforementioned formula (2), Y ² is a divalent organic group represented by the following formula (Y2-1).

In formula (Y2-1), A ¹ , A ⁵ , B ¹ , B ² , A ² , A ³ , A ⁴ , R, and a are as defined above. Among them, A ¹ and A ⁵ are preferably single bonds, methylene, ethylene, or ethylene. In addition, when A ¹ or A ⁵ is an aliphatic heterocyclic ring such as azetidine diyl, pyrrolidine diyl, piperidin diyl, etc., it is azetidine-1,3-diyl, pyrrolidine- 1,3-diyl or piperidine-1,4-diyl is preferred, and the nitrogen atom in the ring is bonded to the adjacent benzene ring.

In addition, B ¹ and B ² are preferably single bonds, or -O-. A ² and A ⁴ are preferably a single bond, methylene, ethylene, or propylene. A ³ is preferably ethylene group. a is preferably 0. R is preferably a hydrogen atom.

In the formula (Y2-1), D is a protective group that is replaced by a hydrogen atom due to heat. From the viewpoint of the storage stability of the liquid crystal alignment agent, it does not depart at room temperature and is heated during the liquid crystal alignment film production step It is more suitable to leave the group substituted with a hydrogen atom. Preferably, the desorption temperature is 80 to 200°C, more preferably 100 to 200°C, and particularly preferably 150 to 200°C. As a specific example of such a group, 1,1-dimethyl-2-chloroethoxycarbonyl, 1,1-dimethyl-2-cyanoethoxycarbonyl, tert-butoxycarbonyl, or 9-Pentylmethoxycarbonyl, etc., preferably tert-butoxycarbonyl, or 9-Pentylmethoxycarbonyl V group, particularly preferably tert-butoxycarbonyl.

Among the divalent organic groups represented by the above formula (Y2-1), as preferred combinations of A ¹ to A ⁵ , B ¹ , B ² and a, the following combinations of type 1 to type 3 can be exemplified. More preferred is type 1 or type 2, and particularly preferred is type 1.

Type 1: A ¹ and A ^{5 are} independently single bonds, methylene groups, and alkylene groups with 2 to 5 carbon atoms, B ¹ and B ^{2 are} independently single bonds, -O-, -COO-, -OCO-,- CONH-, -NHCO-, -CONCH ₃ -, or -NCH ₃ CO-, A ² and A ^{4 are} independently methylene groups, or alkylene groups with 2 to 5 carbons, and A ³ is methylene or carbon For alkylene groups of 2-6, a is 0 or 1.

More preferably, A ¹ and A ⁵ are both single bonds, B ¹ and B ^{2 are} independently single bonds or -O-, and A ² and A ^{4 are} independently methylene groups or alkylene groups with 2 to 5 carbon atoms, A ³ is a methylene group or an alkylene group with 2 to 6 carbon atoms, and a is 0 or 1.

Type 2: A ¹ and A ^{5 are} independently single bonds, azetidine diyl, pyrrolidine diyl, or piperidine diyl, B ¹ and B ² are both single bonds, and A ² and A ^{4 are} independently sub- A methyl group or an alkylene group with 2 to 5 carbon atoms, a is 0. More preferably, A ¹ is azetidine diyl, pyrrolidine diyl, or piperidindiyl, A ² is methylene or an alkylene group with 2 to 5 carbon atoms, A ⁴ , A ⁵ , B ¹ and B ² are single bonds, and a is 0.

Type 3: A ¹ , A ² , A ⁴ , A ⁵ , B ¹ , and B ² are single bonds, A ³ is a methylene group or an alkylene group with 2 to 6 carbon atoms, and a is 1.

Although specific examples of Y ^{2 are} given below, the present invention is not limited to these. In addition, D in the following structure has the same definition as the formula (Y2-1).

The (contained) ratio of the repeating unit shown in formula (2) is preferably 1 to 70 mole% of all repeating units contained in the polyamide ester of component (A), more preferably 5 to 50 mole% ear%.

In the polyamide ester of component (A), the preferred ratio of the repeating unit represented by formula (1) to the repeating unit represented by formula (2) is 1:10~10:1 in molar ratio , More preferably 1:6~6:1. Also, of (A) component Among all the repeating units contained in the polyamide, the total of the repeating unit represented by formula (1) and the repeating unit represented by formula (2) is preferably 15 mol% or more, more preferably 30 mol %the above.

The polyamide ester of the aforementioned (A) component may have repeating units other than the aforementioned formulas (1) and (2). Although the structure of the repeating unit other than the formula (1) and the formula (2) is not particularly limited, the repeating unit represented by the following formula (4) is preferred if the specific example is given.

In the formula (4), R ¹ and R ^{2 have the} same definitions as in the formula (1), and Y ³ represents a divalent organic group other than the aforementioned formula (Y1-1) and formula (Y2-1). The structure of Y ³ in the formula (4) is not particularly limited as long as it is a divalent organic group other than the aforementioned formula (Y1-1) and formula (Y2-1). Although specific examples of preferable structures are shown below, the present invention is not limited to these.

Among the above structures, (Y-5), (Y-10)~(Y-16), (Y-18), (Y-24)~(Y-29), etc. are particularly preferred.

The polyamide ester of the above component (A) can be obtained by a known synthesis method. As an example, a method of polycondensing a tetracarboxylic acid derivative component containing a compound represented by the following formula (1a) and a diamine component containing a compound represented by the following formula (1b) and (2b) , Or the addition polymerization of the tetracarboxylic dianhydride component containing the compound represented by the following formula (1a') and the diamine component containing the compound represented by the following formula (1b) and (2b) After the polyamide acid is reached, the carboxyl group is then esterified.

In the formula, R is a hydroxyl group or a chlorine atom, R ¹ , R ² , and Y ^{1 have the} same definition as the formula (1), and Y ^{2 has the} same definition as the formula (2).

In the liquid crystal alignment agent of the present invention, although the molecular weight of the polyamide ester of component (A) is not particularly limited, it is preferably 2,000 to 500,000 in terms of weight average molecular weight, more preferably 5,000 to 300,000, and still more preferably 10,000 ~100,000.

<Polyamic acid (B)>

The polyamide acid of the aforementioned component (B) has a repeating unit represented by the following formula (3). In addition, the structure of formula (3) contained in this polyamide acid may be one type or two or more types.

In the formula (3), X is a tetravalent organic group, Y is a divalent organic group, and R ⁶ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

The above-mentioned polyamide acid having the repeating unit represented by the formula (3) can be formed by, for example, at least one type of compound represented by the following formula (3a) and at least one type of compound represented by the following formula (3b) The compound is obtained by condensation polymerization. Therefore, in formula (3), X may include structures corresponding to all compounds represented by formula (3a). Similarly, Y and R ⁶ in formula (3) may include structures corresponding to all compounds represented by formula (3b).

X, Y, and R ^{6 in} formula (3a) and formula (3b) have the same definition as each in formula (3).

Although specific examples of preferred structures of X in formula (3) are shown below, the present invention is not limited to these.

In the above (X-1), R ⁷ to R ¹⁰ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

X in the aforementioned formula (3) is preferably selected from at least one of the above-mentioned (X-1)~(X-14) groups, and the most preferred one is selected from R in the above-mentioned (X-1) ⁷ ~ R ^{10 are} all hydrogen atoms, (X-2), (X-3), (X-5), (X-6), (X-7), (X-8), (X- 10) At least one of the group consisting of (X-11), and (X-14).

The structure of Y in formula (3) is not particularly limited as long as it is a divalent organic group, but from the viewpoint of improving the effect of improving the flicker (flicker level) immediately after driving the liquid crystal display element, Y does not include The repeating unit of formula (Y1-1) or formula (Y2-1) is preferred.

More specifically, Y is preferably a divalent organic group selected from the group consisting of (i) to (iii) below.

(i) The structure shown in (c-1) or (c-2) below.

(ii) A combination of structures selected from the following (c-1) to (c-4).

(iii) A combination of structures selected from the following (c-1) to (c-4), which includes a bonding group selected from the following (d-1) to (d-3).

In formula (c-1), R represents a hydrogen atom, a methyl group, or a carboxyl group.

Among the above, the combination of structures selected from the group consisting of (c-1) to (c-4) may be a combination of the same structure using plural numbers. In addition, the bonding groups selected from the group consisting of (d-1) to (d-3) are not adjacent to each other. The molecular weight of the divalent organic group selected from the group consisting of (i) to (iii) is preferably 1000 or less. As a specific example of this Y, the aforementioned (Y-1) to (Y-34), etc. can be exemplified, but the present invention is not limited to these. Among them, (Y-5), (Y-8), (Y-9), (Y-12), (Y-17), (Y-18)~(Y-20), or (Y-29) Especially good.

In the liquid crystal alignment agent of the present invention, the molecular weight of the polyamide acid of component (B) is preferably 2,000 to 500,000 in terms of weight average molecular weight, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000.

<Liquid crystal alignment agent>

The mass (contained) ratio (polyamide/polyamide) of polyamide (A) and polyamide (B) contained in the liquid crystal alignment agent of the present invention is 1/9~9 /1 is better, more preferably 2/8~8/2.

The liquid crystal alignment agent of the present invention is preferably in the form of a solution containing polyamide (A) and polyamide (B). At this time, the total content of polyamide (A) and polyamide (B) can be appropriately changed according to the setting of the thickness of the liquid crystal alignment film to be formed, but it is formed uniformly and without From the point of view of the defective coating film, it is preferably 0.5% by mass or more of the total liquid crystal alignment agent, and from the point of view of the storage stability of the solution, it is preferably 15% by mass or less. In particular, 0.5-10% by mass is more preferable, and 1-10% by mass is particularly preferable.

The organic solvent contained in the liquid crystal alignment agent of the present invention is not particularly limited as long as the polymer components of the polyamide (A) and polyamide (B) are uniformly dissolved. If specific examples are given, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrole Pyridone, N-ethyl-2-pyrrolidone, N-methylcaprolactone, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfide, dimethyl sulfide , Γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, 3-methyl Oxy-N,N-dimethyl propanamide and the like. These can be used alone or in combination of two or more.

In addition, from the viewpoint of the compatibility of the polyamide (A) and the polyamide (B) contained in the liquid crystal alignment agent of the present invention, the content ratio of N-methyl-2-pyrrolidone, It is preferably 30 to 80% by mass relative to the total weight of the liquid crystal alignment agent. In addition, even if it is a solvent that cannot uniformly dissolve the polymer component alone, it can be mixed with the above-mentioned organic solvent as long as it is within a range where the polymer does not precipitate.

In addition to the organic solvent, the liquid crystal alignment agent of the present invention may also contain a solvent for improving the uniformity of the coating film when the liquid crystal alignment agent is applied to the substrate. As this solvent, a solvent with a lower surface tension than the above-mentioned organic solvent is generally used. If specific examples are given, examples include ethyl siloxol, butyl siloxol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy 2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetic acid Ester, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl siloxol acetate, dipropylene glycol, 2-(2-ethyl (Oxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, etc. Two types of these solvents can be used in combination.

The liquid crystal alignment agent of the present invention may also contain various additives such as a silane coupling agent, a crosslinking agent, and an imidization accelerator.

A silane coupling agent can be added for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate. In addition, the silane coupling agent may be one type, or two or more types may be combined. The content of silane coupling agent is relative to 100 parts by mass of polymer It is preferably 0.01 to 5.0 parts by mass, and more preferably 0.1 to 2.0 parts by mass.

Although specific examples of silane coupling agents are given below, they are not limited to these. 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxy Silyl, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene) Amine-based silane coupling agents such as propylamine, 3-aminopropyl diethoxymethyl silane, etc.; vinyl trimethoxy silane, vinyl triethoxy silane, vinyl ginseng (2-methoxyethoxy) ) Silane, vinyl methyl dimethoxy silane, vinyl triacetoxy silane, vinyl triisopropoxy silane, allyl trimethoxy silane, p-styryl trimethoxy silane, etc. Vinyl silane coupling agent; 3-glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl triethoxy silane, 3-glycidoxy propyl methyl diethoxy Epoxy silane coupling agent such as 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; 3-methyl Allyloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3- Methacryloxypropyltriethoxysilane and other methacrylic based silane coupling agents; 3-propenoxypropyltrimethoxysilane and other acrylic based silane coupling agents; 3-ureidopropyl Urea-based silane coupling agents such as triethoxysilane; bis(3-(triethoxysilyl)propyl) disulfide, bis(3-(triethoxysilyl)propyl) tetra Sulfide-based silane coupling agents such as sulfides; 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-octylthio-1-propyltriethoxy Mercapto-based silane coupling agents such as silane; isocyanate-based silane coupling agents such as 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane, etc.; aldehydes such as triethoxy silyl butyl aldehyde Silane coupling agent; triethoxysilyl propyl methyl carbamate, (3-triethoxysilyl propyl)-t-butyl carbamate and other carbamate silane coupling agents .

The above-mentioned crosslinking agent can be used for the purpose of improving the film strength of the liquid crystal alignment film. In addition, the crosslinking agent may be one type, or two or more types may be combined. The amount of the crosslinking agent used is preferably 0.1-50 parts by mass relative to 100 parts by mass of the polymer component, and more preferably 1-20 parts by mass.

As the above-mentioned crosslinking agent, an epoxy group, an isocyanate group, an oxetanyl group, a cyclocarbonate group, or a crosslinkable compound having a hydroxyalkylamino group, a hydroxyl group, a hydroxyalkyl group and A crosslinkable compound having at least one substituent in the group of lower alkoxyalkyl groups, or a crosslinkable compound having a polymerizable unsaturated bond, etc. These substituents or polymerizable unsaturated bonds preferably have two or more in the crosslinkable compound.

Although specific examples of the crosslinking agent are given below, they are not limited to these. Examples of crosslinkable compounds having epoxy groups or isocyanate groups include bisphenol acetone glycidyl ether, phenol novolac epoxy resin, cresol novolac epoxy resin, and triglycidyl isocyanuric acid. Ester, tetraglycidyl diphenylene, tetraglycidyl-m-xylene diamine, tetraglycidyl-1,3-bis(aminoethyl)cyclohexane, tetraphenyl ring Oxypropyl ether ethane, triphenyl glycidyl ether ethane, bisphenol hexafluoroacetone diglycidyl ether, 1,3-bis(1-(2,3-glycidoxy) -1-Trifluoromethyl-2,2,2-trifluoromethyl)benzene, 4,4-bis(2,3-epoxypropoxy)octafluorobiphenyl, triglycidyl-p- Aminophenol, tetraepoxypropyl m-xylene diamine, 2-(4-(2,3-epoxypropoxy)phenyl)-2-(4-(1,1-bis(4-( 2,3-glycidoxy)phenyl)ethyl)phenyl)propane, 1,3-bis(4-(1-(4-(2,3-glycidoxy)phenyl)- 1-(4-(1-(4-(2,3-epoxypropoxy)phenyl)-1-methylethyl)phenyl)ethyl)phenoxy)-2-propanol and the like.

As the crosslinkable compound having an oxetanyl group, the crosslinkable compound represented by formula [4a] to [4k] disclosed on pages 58 to 59 of the pamphlet of WO2011/132751 can be exemplified. As the crosslinkable compound having a cyclic carbonate group, the crosslinkable compound represented by formulas [5-1] to [5-42] disclosed on pages 76 to 82 of the pamphlet of WO2012/014898 can be exemplified.

As the crosslinkable compound having a hydroxyalkylamino group, the crosslinkable compound disclosed on page 23 of the pamphlet [Chemical Formula 35] of WO2015/072554 can be exemplified. As a crosslinkable compound having at least one substituent selected from the group consisting of a hydroxyl group and an alkoxy group, the formula [6-1] disclosed in pages 62 to 66 of the pamphlet of WO2011/132751 can be exemplified ]~[6-48] the cross-linking compound shown in.

As the cross-linkable compound having a polymerizable unsaturated bond, the cross-linkable compound disclosed in International Publication WO2015/060357 pamphlet 58-59 pages [0112] to [0113] can be exemplified.

When the coating film of the liquid crystal alignment agent of the present invention is fired, the imidization reaction of polyamide (A) and polyamide (B) can be used for the purpose of efficiently proceeding. Accelerator. The usage amount of the imidization accelerator is relative to the amide acid site and the amide acid ester site of the imidization reaction In terms of 1 mol, it is preferably 0.01 mol or more, more preferably 0.05 mol or more, and still more preferably 0.1 mol or more. In addition, the imidization accelerator itself remaining in the film after firing, from the viewpoint of keeping the adverse effects on the properties of the liquid crystal alignment film to a minimum, is preferably 2 mol or less, more preferably It is 1 mol or less, more preferably 0.5 mol or less.

As specific examples of the imidization accelerator, the compounds represented by formulas (B-1) to (B-17) disclosed on page 29 of the pamphlet of International Publication No. WO2010/114103 can be cited, but they are not limited to this.

<Liquid crystal alignment film>

The liquid crystal alignment film of the present invention is a liquid crystal alignment film obtained by using the liquid crystal alignment agent of the present invention described above. The method for obtaining the liquid crystal alignment film can use a known technique. For example, a liquid crystal alignment agent is applied to a substrate, and a coating film obtained by drying and firing is rubbed or irradiated with polarized ultraviolet rays to impart liquid crystal alignment ability to a liquid crystal alignment film.

The substrate on which the liquid crystal alignment agent is applied is not particularly limited as long as it is a highly transparent substrate. Plastic substrates such as glass substrates, silicon nitride substrates, acrylic substrates, or polycarbonate substrates can be used. Regarding substrates such as ITO electrodes, it is preferable from the viewpoint of simplification of the process flow. In addition, in the reflective liquid crystal display element, only one side of the substrate can use an opaque material such as a silicon wafer. In this case, the electrode can also use a light-reflecting material such as aluminum. As the coating method of the liquid crystal alignment agent, spin coating method, printing method, inkjet method, etc. can be exemplified.

Drying and firing steps after coating liquid crystal alignment agent, optional Choose any temperature and time. Usually, in order to fully remove the organic solvent contained, it is dried at 50-120°C for 1 minute to 10 minutes, and then fired at 150-300°C for 5 to 120 minutes. Although the thickness of the coating film after firing is not particularly limited, if it is too thin, the reliability of the liquid crystal display element may decrease, so it is 5 to 300 nm, preferably 10 to 200 nm.

As a method of aligning the coating film, rubbing method, photo alignment processing method, etc. can be exemplified, but the liquid crystal alignment agent of the present invention is particularly useful when used by rubbing method.

<Liquid crystal display element>

The liquid crystal display element of the present invention is a liquid crystal display element having the above-mentioned liquid crystal alignment film. More specifically, after obtaining a substrate with a liquid crystal alignment film from the liquid crystal alignment agent of this embodiment by the above-mentioned method, a liquid crystal cell is produced by a known method, and a liquid crystal display element is produced.

If an example of liquid crystal cell production is given, it is as follows. First, a pair of substrates on which a liquid crystal alignment film is formed is prepared. Next, after bonding the substrate on the other side so that the surface of the liquid crystal alignment film becomes the inner side, the liquid crystal is injected under reduced pressure for packaging. Alternatively, the liquid crystal may be dropped on the surface of the liquid crystal alignment film, and then the substrate may be bonded for packaging. At this time, in order to ensure the space filled by the liquid crystal material between the pair of substrates, columnar protrusions are provided on one of the substrates, or spacers are spread on one of the substrates, or spacers are mixed into the sealing material, or a combination of these methods is adopted. good. The thickness of the separator is preferably 1-30 μm, more preferably 2-10 μm.

As the above-mentioned liquid crystal materials, nematic liquid crystals and discotic liquid crystals can be exemplified. Among them, nematic liquid crystals are preferred, and positive liquid crystal materials or Any of negative liquid crystal materials. Next, set up the polarizing plate. Specifically, it is better to stick a pair of polarizing plates on the surface opposite to the liquid crystal layer of the two substrates.

In addition, the liquid crystal alignment film and the liquid crystal display element of the present invention are not limited to those described above, and may be produced by other known methods. The steps until the liquid crystal display element is obtained from the liquid crystal alignment agent are disclosed in most literatures, in addition to pages 17 [0074] to pages 19 [0081] of Japanese Patent Application Laid-Open No. 2015-135393, for example.

[Example]

Examples are given below to further specifically illustrate the present invention. However, the present invention is not limited to those explained in these embodiments. The abbreviations of the compounds used later and the methods for measuring each characteristic are as follows.

<Abbreviation of compound>

In the following, "Boc" is tert-butoxycarbonyl.

<Abbreviation for solvent>

NMP: N-Methyl-2-pyrrolidone, BCS: Butyl Cyrus

GBL: γ-butyrolactone, IPA: isopropanol

<Viscosity>

The viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a cone rotor TE-1 (1°34', R24), and a temperature of 25°C.

<Molecular weight>

The molecular weight of the polymer is measured by GPC (normal temperature gel permeation chromatography) device, and the number average molecular weight (hereinafter also referred to as Mn) and weight average molecular weight (hereinafter Also known as Mw).

GPC device: manufactured by Shodex (GPC-101)

Column: manufactured by Shodex (KD803, KD805 in-line), column temperature: 50°C

Eluent: N,N-dimethylformamide (as an additive, lithium bromide-hydrate (LiBr‧H ₂ O) is 30mmol/L, phosphoric acid‧anhydrous crystal (o-phosphoric acid) is 30mmol/L, tetrahydrofuran (THF) ) Is 10ml/L), flow rate: 1.0ml/min

Standard samples for calibration curve creation: TSK standard polyethylene oxide manufactured by Tosoh (weight average molecular weight (Mw) approximately 900,000, 150,000, 100,000, 30,000), and polyethylene glycol manufactured by Polymer Laboratory (peak top molecular weight (Mp)) About 12,000, 4,000, 1,000). In order to avoid overlapping of the peaks, the measurement is performed to measure 4 samples of 900,000, 100,000, 12,000, and 1,000, and 2 samples of 3 samples of 150,000, 30,000, and 4,000.

<Abrasion resistance evaluation>

After filtering the liquid crystal alignment agent with a 1.0μm filter, it was spin-coated on a glass substrate with transparent electrodes, dried on a hot plate at 80°C for 5 minutes, and fired at 230°C for 20 minutes to obtain a film thickness 100nm polyimide film. This polyimide film was rubbed once with rayon cloth (rolling diameter 120mm, rotation number 1000rpm, moving speed 20mm/sec, pressing amount 0.4mm). The surface of the film was observed with a confocal laser microscope, and the presence or absence of wear debris and damage were observed at a magnification of 100 times. Those with almost no wear debris or damage were evaluated as "good", and those with many wear debris or friction damage were evaluated as "bad".

<Production of Liquid Crystal Display Elements>

First prepare the substrate with electrodes. The substrate is a glass substrate with a size of 30mm×35mm and a thickness of 0.7mm. As the first layer on the substrate The counter electrode is formed with an IZO electrode with an integral pattern. On the counter electrode of the first layer, as the second layer, a SiN (silicon nitride) film formed by a CVD method is formed. The SiN film of the second layer has a thickness of 500 nm and functions as an interlayer insulating film. On the second layer of SiN film, as the third layer, comb-shaped pixel electrodes formed by patterning an IZO film are arranged as the third layer, and two types of pixels, a first pixel and a second pixel, are formed. The size of each pixel is 10mm in length and about 5mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the SiN film of the second layer.

The pixel electrode of the third layer has a comb-like shape formed by arranging a plurality of "ㄑ"-shaped electrode elements with a curved central part. The width of each electrode element in the width direction is 3 μm, and the interval between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is composed of a plurality of "ㄑ"-shaped electrode elements with a curved central part, the shape of each pixel is not a rectangle. Like the electrode elements, the central part is curved and has a similar bold "ㄑ". "The shape of the word. In addition, each pixel is divided up and down with the curved portion in the center as a boundary, and has a first area above the curved portion and a second area below the curved portion.

If the first area and the second area of each pixel are compared, the formation directions of the electrode elements constituting the pixel electrodes are different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, in the first area of the pixel, the electrode elements of the pixel electrode are formed at an angle of +10° (clockwise), and in the second area of the pixel, the pixel electrode The electrode elements are formed at an angle of -10° (clockwise). That is, in the first area and the second area of each pixel, the voltage between the pixel electrode and the counter electrode It is constructed in such a way that the directions of the in-plane switching (in-plane switching) of the liquid crystal induced by the application are opposite to each other.

Then, the obtained liquid crystal alignment agent was filtered with a 1.0 μm filter, and then applied to the prepared substrate with electrodes, and the back surface of the counter substrate was coated with an ITO film and a columnar spacer with a height of 4 μm. Plate on the glass substrate. Next, after drying on a hot plate at 80°C for 5 minutes, it was fired at 230°C for 20 minutes to form a coating film with a film thickness of 60 nm, and a polyimide film was obtained on each substrate. This polyimide film is rubbed with a rayon cloth in a specific rubbing direction (rolling diameter 120mm, rotation number 500rpm, moving speed 30mm/sec, pressing amount 0.3mm), then ultrasonic irradiation is performed in pure water 1 minute, drying at 80°C for 10 minutes.

After that, using the above-mentioned two kinds of substrates with liquid crystal alignment film, they were combined so that the respective rubbing directions became anti-parallel, leaving a liquid crystal injection port to seal the surroundings to produce a void cell with a cell gap of 3.8 μm. After vacuum injecting liquid crystal (MLC-2041, manufactured by Merck) into this empty cell at room temperature, the injection port was sealed to form an anti-parallel-aligned liquid crystal cell. The obtained liquid crystal cell constitutes an FFS mode liquid crystal display element. After that, the obtained liquid crystal cell was heated at 120° C. for 1 hour and left overnight and used for each evaluation.

<Evaluation of the relaxation characteristics of accumulated charge>

Use the following optical system to evaluate the residual image. The fabricated liquid crystal cell is placed between two polarizing plates arranged with the polarization axis orthogonal to each other. The LED backlight is turned on without voltage applied, and the arrangement angle of the liquid crystal cell is adjusted to minimize the brightness of the transmitted light.

Next, the V-T curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to the liquid crystal cell, and an AC voltage with a relative transmittance of 23% was calculated as the drive voltage.

In the afterimage evaluation, while applying an AC voltage of 30 Hz with a relative transmittance of 23% to drive the liquid crystal cell, a DC voltage of 1 V was simultaneously applied to drive it for 60 minutes. After that, the applied DC voltage value was adjusted to 0V, only the application of the DC voltage was stopped, and driving was continued for 30 minutes in this state.

It is evaluated that when the relative transmittance falls below 30% after 60 minutes have elapsed since the time when the DC voltage is applied, the evaluation is defined as "good". When it takes more than 60 minutes for the relative transmittance to drop below 30%, it is evaluated as "bad".

Then, the after-image evaluation according to the above method is performed under the temperature condition that the temperature of the liquid crystal cell is 23°C.

<The stability evaluation of liquid crystal alignment>

Using this liquid crystal cell, an AC voltage of 10VPP was applied at a frequency of 30Hz for 168 hours under a constant temperature environment of 60°C. After that, the pixel electrode and the counter electrode of the liquid crystal cell are short-circuited, and the state is maintained at room temperature for one day.

After placement, the liquid crystal cell is placed between the two polarizing plates arranged in a way that the polarization axis is perpendicular to each other, the backlight is turned on without voltage applied, and the arrangement angle of the liquid crystal cell is adjusted to minimize the brightness of the transmitted light. Then, calculate the angle from which the second area of the first pixel becomes the darkest to The rotation angle when the liquid crystal cell is rotated until the first area becomes the darkest angle is taken as the angle Δ. The same is true for the second pixel, comparing the second area with the first area, and the same angle Δ is spread. Then, the average value of the angle Δ between the first pixel and the second pixel is calculated as the angle Δ of the liquid crystal cell. When the value of the angle △ of the liquid crystal cell exceeds 0.2 degrees, the evaluation is defined as "bad". When the value of the angle Δ of the liquid crystal cell exceeds 0.2 degrees, the evaluation is defined as "good".

<Evaluation of flicker level immediately after driving>

Use the following optical system to evaluate the residual image.

The fabricated liquid crystal cell is placed between two polarizing plates arranged so that the polarization axis becomes orthogonal, and the LED backlight is turned on without voltage applied, and the arrangement of the liquid crystal cell is adjusted to minimize the brightness of the transmitted light. angle.

Next, the V-T curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to the liquid crystal cell, and an AC voltage with a relative transmittance of 23% was calculated as the drive voltage.

In the measurement of the flicker level, once the lit LED backlight is turned off and shading for 72 hours, the LED backlight is turned on again. When the backlight is turned on, an AC voltage of 30 Hz with a relative transmittance of 23% is applied to make the liquid crystal cell Drive for 60 minutes to track the flicker amplitude. The flicker amplitude is to pass the transmitted light of the LED backlight of the two polarizing plates and the liquid crystal cell between them to the data collection/data logger switch unit 34970A (Agilent technologies company) connected through the photodiode and the I-V conversion amplifier. Division system) to read. The flicker level is calculated by the following formula.

Flicker level (%)=(flicker amplitude/(2×z))×100

In the above formula, z is the value read by the data collection/data logger switch unit 34970A when the brightness is driven by an AC voltage of 30 Hz with a relative transmittance of 23%.

The evaluation of the flicker level is defined as "good" when the flicker level remains below 3% after 60 minutes have elapsed since the time when the LED backlight was turned on and the AC voltage was applied. When the flicker level reaches 3% in 60 minutes, the evaluation is defined as "bad".

Then, the evaluation of the flicker level according to the above method is performed under the temperature condition that the temperature of the liquid crystal cell is 23°C.

<Evaluation of Storage Stability>

In the evaluation of storage stability, the viscosity of the following adjustment solution before and after storage at room temperature for 1 week is evaluated as "good" when the viscosity change is less than 5mPa‧s, and when it is more than 5mPa‧s, it is evaluated as "bad".

<Synthesis example>

(Synthesis example 1)

Put it into a 7L separable flask with a stir bar, put in 119g (0.46mol) of CE-1, add 2372g of NMP and stir to dissolve it. Next, 146 g (1.44 mol) of triethylamine, 61 g (0.26 mol) of DA-1, 21 g (0.072 mol) of DA-3, and 49 g (0.14 mol) of DA-5 were added and stirred and dissolved.

While stirring this solution under ice cooling, 362 g (0.94 mol) of DBOP was added, and 326 g of NMP was further added, followed by stirring at room temperature for 12 hours to obtain a solution of polyamide ester. The viscosity of this polyamide ester solution was 27.3mPa‧s.

This polyamide ester solution was poured into 20739 g of IPA, and the obtained precipitate was separated by filtration. After washing this deposit with methanol, it was dried under reduced pressure at a temperature of 100°C to obtain a powder of polyamide ester. The molecular weight of this polyamide ester is Mn=12,200 and Mw=21,700.

To the obtained polyamide ester powder, NMP was added so that the solid content concentration became 12% by weight, and the mixture was stirred at 50° C. for 30 hr to dissolve to obtain a polyamide ester solution (PAE-1).

(Synthesis example 2)

Put it into a 300 mL four-necked flask with a stir bar, put in 6.85 g (26.3 mmol) of CE-1, add 140 g of NMP and stir to dissolve it. Next, 8.5 g (84.0 mmol) of triethylamine, 4.10 g (16.8 mmol) of DA-2, and 3.82 g (11.2 mmol) of DA-5 were added, and the mixture was stirred and dissolved.

While stirring this solution under ice cooling, 20.7 g (54.0 mmol) of DBOP was added, and 19.2 g of NMP was further added, and stirred at room temperature for 12 hours to obtain a solution of polyamide ester. The viscosity of this polyamide ester solution was 31.4mPa‧s.

This polyamide ester solution was poured into 1218 g of IPA, and the obtained precipitate was separated by filtration. After washing the precipitate with methanol, use a temperature of 100 Dry under reduced pressure at °C to obtain a powder of polyamide ester. The molecular weight of this polyamide ester is Mn=11,600 and Mw=20,500.

To the obtained polyamide powder, NMP was added so that the solid content concentration became 12% by weight, and the mixture was stirred at 50° C. for 30 hr to dissolve to obtain a polyamide acid ester solution (PAE-2).

(Synthesis example 3)

Take DA-4 243.9g (1.22mol) and DA-2 74.8g (0.31mol) in a 5L separable flask equipped with a stirring device and nitrogen introduction tube, and add a solvent (NMP: GBL=50wt%: 50wt%) 3154g, stirring and dissolving while supplying nitrogen.

While stirring the diamine solution under ice cooling, 129.0 g (0.66 mol) of CA-2 and 166.8 g (0.77 mol) of CA-1 were added, and the solvent (NMP: GBL) was added so that the solid content concentration became 12% by weight. =50wt%: 50wt%), stirred at 50°C for 12 hours to obtain a polyamide acid solution (PAA-1). The viscosity of this polyamic acid solution is 310mPa‧s. In addition, the Mn of this polyamide acid is 11,700, and the Mw is 24,300.

(Synthesis example 4)

In a 200mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, take DA-4 4.1g (20.4mmol), DA-6 5.4g (13.6mmol), and DA-2 8.3g (34.0mol), and add NMP Add 173 g, and stir to dissolve while supplying nitrogen.

Add CA-2 while stirring this diamine solution under ice cooling 5.3 g (27.2 mmol), CA-1 7.4 g (34.0 mmol), and further NMP was added so that the solid content concentration became 15% by weight, and the mixture was stirred at 50°C for 12 hours to obtain a polyamide acid solution (PAA-2). The viscosity of this polyamic acid solution at a temperature of 25°C is 530mPa‧s. In addition, the molecular weight of this polyamide acid is Mn=11,700 and Mw=27,200.

(Example 1)

Put PAE-1 2.31g, PAA-1 8.31g in a 20ml sample tube with a stir bar, add NMP 1.31g, GBL 2.38g, BCS 4.0g, 1.2g of NMP solution containing 1% by weight AD-1 And 0.60 g of AD-2, stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-1).

(Example 2)

Put PAE-1 3.46g, PAA-1 7.18g in a 20ml sample tube with a stir bar, add NMP 0.73g, GBL 2.38g, BCS 4.0g, 1.2g of NMP solution containing 1% by weight AD-1 And 0.60 g of AD-2, stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-2).

(Example 3)

Put PAE-1 4.62g, PAA-1 6.15g into a 20ml sample tube with a stir bar, add NMP 0.15g, GBL 2.38g, BCS 4.0g, 1.2g of NMP solution containing 1% by weight of AD-1 And 0.60 g of AD-2, stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-3).

(Comparative example 1)

Put PAE-2 2.40g, PAA-2 6.88g into a 20ml sample tube with a stir bar, add GBL 4.92g, BCS 4.0g, 1.2g of NMP solution containing 1% by weight of AD-1, and AD- 2 0.60 g, stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (B-1).

Using the liquid crystal alignment agent obtained above, evaluations of friction resistance, accumulated charge relaxation characteristics, stability of liquid crystal alignment, flicker level immediately after driving, and storage stability were performed. The results are shown in Table 1.

As described above, the liquid crystal alignment film of the present invention shows good results in any of evaluation of rub resistance, evaluation of after-image erasing time, evaluation of stability of liquid crystal alignment, and evaluation of flicker level immediately after driving.

〔Industrial availability〕

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention pursues a higher level of realization of various characteristics than today, and can be used in IPS In a wide range of liquid crystal display elements such as the driving method or the FFS driving method.

In addition, the entire contents of the specification, scope of patent application, drawings, and abstract of Japanese Patent Application No. 2015-229489 filed on November 25, 2015 are cited here, and the disclosure is incorporated as the specification of the present invention.

Claims (13)

A liquid crystal alignment agent characterized by containing the following (A) component and (B) component, (A) component: containing the repeating unit represented by the following formula (1) and the repeating unit represented by the following formula (2) The polyamide ester, component (B): polyamide acid having a repeating unit represented by the following formula (3),

(In formula (1) and formula (2), each of the plural R ^{1 is} independently an alkyl group with 1 to 6 carbons; each of the plural R ^{2 is} independently a hydrogen atom or an alkyl group with 1 to 6 carbons; Y ¹ is A divalent organic group represented by the following formula (Y1-1), Y ² is a divalent organic group represented by the following formula (Y2-1)),

(In formula (Y1-1), two R ³ are each independently a single bond, -O-, -S-, -OCO-, or -COO-; two R ⁴ are each independently a carbon number of 1 to 3 Alkyl; R ⁵ is an oxygen atom or a sulfur atom),

(In formula (Y2-1), A ¹ and A ⁵ are each independently a single bond, a methylene group, an alkylene group with 2 to 5 carbon atoms, azetidine diyl, pyrrolidine diyl, or piperidine Diyl; B ¹ and B ² are each independently a single bond, -O-, -COO-, -OCO-, -CONH-, -NHCO-, -CONCH ₃ -, or -NCH ₃ CO-; A ² and A ⁴ each independently is a single bond, a methylene group, or an alkylene group with 2 to 5 carbons; A ³ is a methylene group, or an alkylene group with 2 to 6 carbons; a is 0 or 1; R is a hydrogen atom Or methyl, D is a protecting group that is replaced by a hydrogen atom due to heat),

(In formula (3), X is a tetravalent organic group, Y is a divalent organic group, and R ⁶ is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms). The liquid crystal alignment agent of claim 1, wherein the formula (Y1-1) is selected from the group consisting of the following (Y1-1-1)~(Y1-1-8),

Such as the liquid crystal alignment agent of claim 1 or 2, wherein in formula (Y2-1), A ¹ , A ² , A ⁴ , A ⁵ , B ¹ , and B ² are single bonds, and A ³ is methylene or carbon number 2~6 alkylene, a is 1. The liquid crystal alignment agent of claim 1 or 2, wherein in formula (3), Y is a divalent organic group selected from the group consisting of (i), (iii) and (iii) below, (i) below The structure shown in (c-1) or (c-2), (ii) a combination of structures selected from the following group (c-1)~(c-4), (iii) selected from The combination of the structures in the group formed by (c-1)~(c-4) below contains a bonding group selected from the group formed by (d-1)~(d-3) below,

(In formula (c-1), R represents a hydrogen atom, a methyl group, or a carboxyl group). The liquid crystal alignment agent of claim 4, wherein in formula (3), X is a tetravalent organic group selected from at least one of the following groups (X-1) to (X-14),

The liquid crystal alignment agent of claim 1 or 2, wherein the ratio of the repeating unit represented by formula (1) or the ratio of the repeating unit represented by formula (2) is contained in the polyamide ester of component (A) 1~70 mole% of all repeat units. The liquid crystal alignment agent of claim 1 or 2, wherein the content ratio of the repeating unit represented by the formula (1) in the polyamide ester of the component (A) to the repeating unit represented by the following formula (2) ( Mo Er ratio) is 1:10~10:1. The liquid crystal alignment agent of claim 1 or 2, wherein the total content of the aforementioned (A) component and (B) component is 0.5 to 15% by mass relative to the entire liquid crystal alignment agent. The liquid crystal alignment agent of claim 1 or 2, wherein relative to 100 parts by mass of the aforementioned (A) component, the mass content ratio of the aforementioned (A) component to the aforementioned (B) component is 1/9-9/1, And it contains 100-400 mass parts of said (B) component. The liquid crystal alignment agent of claim 1 or 2, which contains N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N- Methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactone, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylene One of the group consisting of sulphur, dimethyl sulphur, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, and 3-methoxy-N,N-dimethylpropanamide Organic solvents. The liquid crystal alignment agent of claim 1 or 2, which further contains a silane coupling agent, a crosslinking agent, or an imidization accelerator. A liquid crystal alignment film, which is used as any of the requirements 1~11 One item of liquid crystal alignment agent. A liquid crystal display element having the liquid crystal alignment film as claimed in claim 12.