TWI780023B - Liquid crystal alignment agent, method for producing liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

A liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element for obtaining an alignment film suitable for photo-alignment, which do not produce bright spots even in negative type liquid crystals and can obtain good afterimage characteristics.

The liquid crystal alignment agent of the present invention contains at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers of the polyimide precursors, the aforementioned polyamide The imine precursor has a structural unit represented by formula (1) and a structural unit represented by formula (2).

(X₁、X₂：式(X1-1)或(X1-2)，R₁、R₂、R₃、R₄、及 R₆係分別獨立為氫原子、或碳數1~4的烷基，R₅係碳數1~4的烷基，n係1~6的整數)

(X ₁ , X ₂ : Formula (X1-1) or (X1-2), R ₁ , R ₂ , R ₃ , R ₄ , and R ₆ are each independently a hydrogen atom, or an alkane with 1 to 4 carbons base, R is an alkyl group with 1 to ₄ carbons, and n is an integer from 1 to 6)

Description

Liquid crystal alignment agent, manufacturing method of liquid crystal alignment film, and liquid crystal display element

The invention relates to a liquid crystal alignment agent suitable for photo-alignment treatment, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.

Liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, etc. are generally provided with a liquid crystal alignment film for controlling the arrangement state of liquid crystals in the element. As a liquid crystal alignment film, a liquid crystal alignment agent mainly composed of a polyimide precursor such as polyamic acid (polyamic acid) or a solution of soluble polyimide is applied to a glass substrate and the like. Polyimide-based liquid crystal alignment film obtained by firing. Now, according to the most popular method in the industry, the liquid crystal alignment film is the so-called method of rubbing the surface of the polyimide-based liquid crystal alignment film formed on the electrode substrate with cotton, nylon, polyester, etc. cloth in one direction. Made with friction treatment.

As a non-friction alignment treatment method, the photo-alignment method also has the advantage of being able to produce it with a simple manufacturing process in the industry.

In IPS (In Plane Switching) drive mode or FFS (Fringe Field Switching) drive mode liquid crystal display elements, By using the liquid crystal alignment film obtained by the photo-alignment method, compared with the liquid crystal alignment film obtained by the rubbing method, the contrast of the liquid crystal display element or the improvement of the viewing angle characteristic can be expected, because the liquid crystal display element can be improved. The performance is improved, so it is expected to become a liquid crystal alignment treatment method that attracts people's attention.

However, compared with the liquid crystal alignment film obtained by rubbing treatment, the liquid crystal alignment film obtained by the photo-alignment method has the problem that the anisotropy of the polymer film with respect to the alignment direction is small. When the anisotropy is small, sufficient liquid crystal alignment cannot be obtained, and when it is made into a liquid crystal display element, problems such as image sticking will arise. As a method of improving the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, it is proposed to remove the low-molecular-weight components generated by the cleavage of the main chain of the polyimide caused by light irradiation after light irradiation.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-297313

[Patent Document 2] Japanese Unexamined Patent Publication No. 2011-107266

[Non-patent literature]

[Non-Patent Document 1] "Liquid Crystal Photoalignment Film", Functional Materials, November 1997, Vol.17, No.11, pp. 13-22

In the liquid crystal display elements of the IPS driving method or the FFS driving method, the positive type liquid crystal is used in the past, but by using the negative type liquid crystal, the transmission loss on the upper part of the electrode can be reduced and the contrast can be improved. If the liquid crystal alignment film obtained by the photo-alignment method is used in an IPS-driven or FFS-driven liquid crystal display element using a negative liquid crystal material, it can be expected to have higher display performance than conventional liquid crystal display elements.

However, as a result of the inventor's research, it can be known that if the liquid crystal alignment film obtained by the photo-alignment method is a liquid crystal display element using a negative type liquid crystal material, the occurrence rate of display defects (bright spots) is high, and it may cause display defects. bad problem.

The object of the present invention is to provide a liquid crystal alignment agent suitable for photo-alignment treatment. It is used to obtain a liquid crystal alignment film for photo-alignment. Even if a negative type liquid crystal is used, no bright spots are generated and good afterimages can be obtained. characteristics, and provide a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element with the liquid crystal alignment agent.

As a result of repeated in-depth research, the present inventors found that a liquid crystal alignment agent comprising a polyimide-based polymer with a specific structure is effective for achieving the above-mentioned purpose, and thus completed the present invention.

The present invention is a liquid crystal alignment agent, which is characterized by containing at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers of the polyimide precursors, the aforementioned The polyimide precursor system has the structural unit represented by the following formula (1), and the following formula (2) The structural unit represented.

(式(1)、式(2)中，X₁及X₂係分別獨立為選自由下述式(X1-1)及(X1-2)所表示之構造所成群之至少1種。R₁、R₂、R₃、R₄、及R₆係分別獨立為氫原子、或碳數1~4的烷基。R₅係碳數1~4的烷基，n係1~6的整數)

(In formula (1) and formula (2), X ₁ and X ₂ are each independently at least one selected from the group of structures represented by the following formulas (X1-1) and (X1-2). R _1. R ₂ , R ₃ , R ₄ , and R ₆ are each independently a hydrogen atom or an alkyl group with 1 to 4 carbons. R ₅ is an alkyl group with 1 to 4 carbons, and n is an integer from 1 to 6 )

According to the present invention, a liquid crystal alignment agent suitable for photo-alignment treatment can be provided, which can suppress the bright spots seen in the conventional photo-alignment treatment method, and can obtain liquid crystal alignment with high irradiation sensitivity and good afterimage characteristics. membrane. By having a liquid crystal alignment film obtained from the above-mentioned liquid crystal alignment agent, It is possible to provide a highly reliable liquid crystal display element without display defects.

[Best Mode for Carrying Out the Invention] <specific polymer>

As mentioned above, the liquid crystal alignment agent of the present invention contains at least one polymer selected from the group consisting of polyimide precursors and imidized polymers of the polyimide precursors (in the present invention Also referred to as the specific polymer (A)), the aforementioned polyimide precursor has structural units represented by the following formula (1) and the following formula (2). In the present invention, the structural unit represented by formula (1) and the structural unit represented by the following formula (2) may exist in the same polyimide precursor, and the structural unit represented by formula (1) and The structural unit represented by the following formula (2) may also exist in each polyimide precursor.

The definitions of X ₁ , X ₂ , R ₁ , and R ₂ in the above formula (1) and formula (2) are the same as above. Among them, X ₁ and X ₂ are preferably those having the aforementioned formula (X1-2) in terms of high sensitivity and liquid crystal alignment. R ₁ and R ₂ are preferably a hydrogen atom, or a methyl group or an ethyl group in view of easiness of imidization by heating. R ₃ , R ₄ , and R ₆ are preferably hydrogen atoms in terms of liquid crystal alignment. From the viewpoint of liquid crystal alignment, R ₅ is preferably a methyl group. Also, n is an integer of 1 to 3, particularly preferably 2, in terms of liquid crystal alignment.

<Manufacture of Polyimide Precursor-Manufacture of Polyamide Acid>

In the present invention, the polyimide precursor (ie, polyamic acid) having the structural unit represented by formula (1) and the structural unit represented by formula (2) is produced by the following method. Still, in the present invention, the polyimide precursor with the structural unit represented by formula (1) and the polyimide precursor with the structural unit represented by formula (2) can be manufactured separately and separately , and is produced by mixing the two.

Also, as the diamine polycondensed with tetracarboxylic acid or its dianhydride, the diamine given to the structural unit represented by formula (1) and the diamine given to the structural unit represented by formula (2) are used as 1 It is preferable to produce a polyimide precursor having a structural unit represented by formula (1) and a structural unit represented by formula (2).

At this time, the tetracarboxylic acid or its dianhydride imparted to X1 in the above formula ( ₁ ), the tetracarboxylic acid or its dianhydride imparted to X2 in the above formula ( ₂ ), and the diamine imparted to _Y1 and the diamine imparted with _Y2 , in the presence of a solvent, undergo polycondensation reaction at -20 to 150°C, preferably at 0 to 50°C, for 30 minutes to 24 hours, preferably 1 to 12 hours to manufacture.

The reaction between diamine and tetracarboxylic acid is generally carried out in a solvent. The solvent used at this time is not particularly limited as long as it can dissolve the produced polyimide precursor. The following are specific examples of solvents used in the reaction, but are not limited to these examples.

For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide amide, dimethylsulfoxide or 1,3-dimethyl-imidazolidinone. Also, when the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxyl-4-methyl-2-pentanone or the following formula [D -1] ~ the solvent represented by the formula [D-3].

(式[D-1]中D¹係表示碳數1~3的烷基，式[D-2]中D²係表示碳數1~3的烷基，式[D-3]中D³係表示碳數1~4的烷基)。

(D 1 in formula [D- ¹ ] represents an alkyl group with 1 to 3 carbons, D 2 in formula [D- ² ] represents an alkyl group with 1 to 3 carbons, D 3 in formula [D- ³ ] represents an alkyl group with 1 to 4 carbon atoms).

These solvents may be used alone or in combination. Furthermore, even if it is a solvent which cannot dissolve a polyimide precursor, it can also be mixed with the said solvent and used within the range which does not precipitate the produced|generated polyimide precursor. Also, because the moisture in the solvent will hinder the polymerization reaction, and then cause the resulting Because of the hydrolysis of the formed polyimide precursor, it is better to use dehydration and drying solvents.

In addition, in order to obtain the polyamic acid alkyl ester system, the following method can be used: the method of polycondensing tetracarboxylic acid that is dialkylated to the carboxylic acid group and the 1st or 2nd diamine compound, making the A method of polycondensation of a tetracarboxylic acid dihalide with dialkyl esterification of a carboxylic acid group and a primary or secondary diamine compound, or a method of converting the carboxyl group of polyamic acid into an ester.

When reacting the diamine component and the tetracarboxylic acid component in a solvent, for example, the following method can be used: stirring the solution formed by dispersing or dissolving the diamine component in the solvent, and directly dispersing or dispersing or dissolving the tetracarboxylic acid component. A method of adding by dissolving in a solvent, conversely dispersing a tetracarboxylic acid component in a solvent, or adding a diamine component to a dissolved solution, a method of alternately adding a diamine component and a tetracarboxylic acid component, etc., Any of these methods can also be used. In addition, when two kinds of diamine components or tetracarboxylic acid components are respectively used and reacted, they may be reacted in a pre-mixed state, or they may be reacted separately and sequentially, and further, the low molecular weight bodies reacted separately may be mixed and reacted. into polymers.

The polymerization temperature at this time may be any temperature from -20 to 150°C, but is preferably within the range of -5 to 100°C. Also, the reaction system can be carried out at any concentration, but if the concentration is too low, it will become difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution will become too high to allow uniform stirring. become difficult. Therefore, it is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The initial stage of the reaction is carried out at a high concentration, and the solvent can be added thereafter.

In the polymerization reaction of the polyimide precursor, the ratio of the total number of moles of the diamine components to the total number of moles of the tetracarboxylic acid components is preferably 0.8~1.2, especially preferably 0.9~1.0. Similar to a general polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyimide precursor to be produced becomes.

The polyimide in the present invention is a polyimide obtained by ring-closing the aforementioned polyimide precursor. In order to obtain the polyimide, the aforementioned polyamide acid or polyamide acid can be used. Alkyl ester ring closure to make polyimide method.

The ring-closing rate (also called imidization rate) of the polyimide-based amide acid group of the present invention is not necessarily 100%, and can be adjusted arbitrarily according to the application or purpose, preferably 50-80%.

As a method for imidizing a polyimide precursor, thermal imidization in which a solution of a polyimide precursor is directly heated, or a method of adding a catalyst to a solution of a polyimide precursor can be exemplified. Catalytic imidization. The temperature for thermal imidization of the polyimide precursor in the solution is 100-400°C, preferably 120-250°C, so that the water generated by the imidization reaction is removed to the outside of the system, and at the same time It is better to come to carry out. The reaction time is preferably 30 minutes to 4 hours.

Catalyzed imidization of polyimide precursors can be done by adding alkaline catalyst and acid anhydride to the solution of polyimide precursors, by heating at -20~250°C, preferably 0~180°C Stir to proceed. The reaction time is preferably 30 minutes to 4 hours.

The amount of alkaline catalyst is 0.5 ~ 30 mole times of amide acid group, preferably 2~20 mole times, the amount of acid anhydride is 1~50 mole times of amide acid group. Preferably it is 3 to 30 mole times. The basic catalyst may, for example, be pyridine, triethylamine, trimethylamine, tributylamine or trioctylamine. Among them, pyridine is preferred because it has moderate basicity during the reaction.

As the acid anhydride, acetic anhydride, trimellitic anhydride, or pyromellitic anhydride may, for example, be mentioned. Among them, acetic anhydride is preferred because it is easy to refine after the reaction is completed. The imidization rate of catalyst imidization can be controlled by adjusting the amount of catalyst, reaction temperature and reaction time.

When recovering the polyimide precursor or polyimide produced from the polyimide precursor or polyimide reaction solution, the reaction solution may be put into a solvent for precipitation. Examples of solvents used for precipitation include methanol, ethanol, isopropanol, acetone, hexane, butyl celluloid, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water, and the like. The polymer thrown into the solvent and precipitated can be dried at normal temperature or heated under normal pressure or reduced pressure after being collected by filtration.

In addition, if the polymer recovered by precipitation is redissolved in the solvent, if the operation of re-precipitation recovery is repeated 2 to 10 times, the impurities in the polymer can be reduced. As the solvent at this time, for example, alcohols, ketones, hydrocarbons, etc. are used, and when three or more solvents selected from these are used, it is preferable because the efficiency of purification can be further improved.

For the specific polymer (A) of the present invention, it is preferable to use polyamic acid alkyl ester. A preferred specific method for producing the polyamic acid alkyl ester is shown in the following (1) to (3).

(1) Method of producing by esterification reaction of polyamic acid

A method of producing polyamic acid from a diamine component and a tetracarboxylic acid component, and performing a chemical reaction on the carboxyl group (COOH group), that is, performing an esterification reaction to produce a polyamic acid alkyl ester.

The esterification reaction is specifically to react the polyamic acid and the esterifying agent in the presence of a solvent, preferably at -20 to 150°C, and preferably at 0 to 50°C, preferably for 30 minutes to 24 minutes. hours, preferably 1 to 4 hours.

As the aforementioned esterifying agent, those that can be easily removed after the esterification reaction are preferred, such as N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide di-neopentyl butyl acetal, N,N-dimethylformamide di-neopentyl acetal -t-butyl acetal, 1-methyl-3-p-tolyl triazene, 1-ethyl-3-p-tolyl triazene, 1-propyl-3-p-tolyl triazene Nitrene, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride, and the like. The usage amount of the esterifying agent is preferably 2-6 molar equivalents relative to 1 molar repeating unit of polyamic acid. Among them, 2 to 4 molar equivalents are preferred.

As a solvent used for the said esterification reaction, the solvent used for the reaction of the said diamine component and a tetracarboxylic-acid component is mentioned from the point of the solubility of polyamic acid with respect to a solvent. Among them, N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone are preferred. The solvent can be used alone or in combination of two or more.

The concentration of the polyamic acid in the solvent of the aforementioned esterification reaction is preferably 1 to 30% by mass in terms of the point that the precipitation of the polyamic acid is less likely to occur. Among them, 5 to 20% by mass is preferred.

(2) Method of producing by reaction of diamine component and tetracarboxylic acid diester dichloride

The reaction between the diamine component and the tetracarboxylic acid diester dichloride, specifically, in the presence of a base and a solvent, preferably at -20~150°C, and preferably at 0~50°C, makes the diamine The method of reacting the components with the tetracarboxylic acid diester dichloride is preferably 30 minutes to 24 hours, and more preferably 1 to 4 hours.

As the aforementioned base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used. Among them, pyridine is preferable in order to proceed the reaction stably. The amount of base used is the amount that can be easily removed after the above-mentioned reaction. It is preferably 2 to 4 times mole relative to the tetracarboxylic acid diester dichloride. Among them, 2 to 3 times the mole is more preferable.

The solvent used in the aforementioned reaction can be used, for example, in the reaction of the aforementioned diamine component and tetracarboxylic acid component in terms of the solubility of the obtained polymer (i.e., polyamic acid alkyl ester) to the solvent. solvent. Among them, N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone are preferred. These solvents may be used alone or in combination of two or more.

The concentration of the polyamic acid alkyl ester in the solvent of the above-mentioned reaction is preferably 1 to 30% by mass in view of the point that the precipitation of the polyamic acid alkyl ester is less likely to occur. Among them, 5 to 20% by mass is preferred. Also, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable to dehydrate the solvent used for the preparation of the polyamic acid alkyl ester as much as possible. Furthermore, the aforementioned It should be carried out in a nitrogen environment, and it is better to prevent the mixing of outside air.

(3) A method of producing by reacting a diamine component with a tetracarboxylic acid diester

The method of producing by polycondensation reaction of diamine component and tetracarboxylic acid diester, specifically, in the presence of condensing agent, alkali and solvent, at 0~150°C, preferably 0~100°C, The method of reacting the diamine component and the tetracarboxylic acid diester is preferably 30 minutes to 24 hours, and more preferably 3 to 15 hours.

The aforementioned condensing agent can use triphenyl phosphite, dicyclohexyl carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'- Tetramethyluronium tetrafluoroborate, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2 -thione-3-benzoxazolyl)phosphonic acid diphenyl ester and the like. The usage amount of the condensing agent is preferably 2~3 moles, especially 2~2.5 moles relative to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of alkali used is preferably an amount that can be easily removed after the aforementioned polycondensation reaction, preferably 2 to 4 times the mole of the diamine component, particularly preferably 2 to 3 times the mole.

The solvent used for the polycondensation reaction may, for example, be the solvent used for the reaction of the above-mentioned diamine component and tetracarboxylic acid component in terms of the solubility of the polyamic acid alkyl ester of the obtained polymer to the solvent. In particular, N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone are preferred. The solvent system can be used in mixture of 2 or more types.

In addition, by adding Lewis acid as an additive in the above-mentioned polycondensation reaction, the reaction can be efficiently carried out. Lithium halides such as lithium chloride and lithium bromide are preferred as the Lewis acid. The amount of Lewis acid used is preferably 0.1-10 times mole, especially 2.0-3.0 times mole, relative to the diamine component.

When recovering the polyamic acid alkyl ester from the solution of the polyamic acid alkyl ester obtained by the method (1)-(3) above, it is sufficient to put the reaction solution into a solvent to precipitate it. As a solvent used for precipitation, water, methanol, ethanol, 2-propanol, hexane, butyl celluloid, acetone, toluene etc. are mentioned. The polymer that has been put into a solvent and allowed to precipitate is preferably washed multiple times with the above-mentioned solvent for the purpose of removing the additives and catalysts used in the above. After filtration and recovery, it can be dried at normal temperature or heated under normal pressure or reduced pressure. Also, if the polymer collected by precipitation is redissolved in a solvent, and the operation of reprecipitation recovery is repeated 2 to 10 times, the impurities in the polymer can be reduced. As a solvent in this case, the solvent which can dissolve a polymer is mentioned, for example.

Among the aforementioned methods (1) to (3) for the polyamic acid alkyl ester of the present invention, the method of (1) or (2) is preferred.

<Liquid crystal alignment agent>

The liquid crystal alignment agent is a coating solution used to form a liquid crystal alignment film (also called a resin film), and a coating solution used to form a liquid crystal alignment film containing a specific polymer (A) and a solvent. The content of the specific polymer (A) in the liquid crystal alignment agent can be set according to the coating method of the liquid crystal alignment agent or The film thickness of the target liquid crystal alignment film can be changed appropriately, preferably 2-10% by mass, especially preferably 3-7% by mass. On the other hand, the content of the solvent is preferably 70 to 99.9% by mass, more preferably 90 to 98% by mass.

The solvent used in the liquid crystal alignment agent of the present invention is a solvent (also called a good solvent) for dissolving the specific polymer (A), especially an organic solvent is preferred. Although the specific example of a good solvent can be mentioned below, it is not limited to these examples.

For example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl Acine, γ-butyrolactone, 1,3-dimethyl-imidazolinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, etc. Among them, it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone.

Furthermore, when the solubility to the solvent of a specific polymer (A) is high, it is preferable to use the solvent represented by said formula [D-1] - a formula [D-3].

The good solvent in the liquid crystal alignment agent is preferably 20-99% by mass of the total solvent, more preferably 20-90% by mass, and most preferably 30-80% by mass.

As long as the liquid crystal alignment agent does not impair the effect of the present invention, it may contain a solvent (also known as a poor solvent) that improves the filmability or surface smoothness of the liquid crystal alignment film when coating the liquid crystal alignment agent. These poor solvents are preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent. Among them, with 10~80 Mass % is preferred. More preferably, it is 20 to 70% by mass.

Although the specific example of a poor solvent can be mentioned below, it is not limited to these examples. For example, ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol alcohol, isoamyl alcohol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol , 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol Alcohol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethanediol -1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2- Butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexane Ketone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoethyl ester, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol Alcohol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1-(butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, di Propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether Acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol Glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene Glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, Methyl 3-methoxypropionate, methylethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionate, 3-methoxypropionate, 3- Propyl methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, the aforementioned formula [D-1] ~ The solvent represented by the formula [D-3], etc.

Among them, 1-hexanol, cyclohexanol, 1,2-ethylene glycol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether are preferred.

In the liquid crystal alignment agent of the present invention, a cross-linking compound having an epoxy group, an isocyanate group, an oxetanyl group or a cyclic carbonate group is introduced, and a compound having a group selected from hydroxyl, hydroxyalkyl and lower-order alkoxy A crosslinkable compound having at least one substituent grouped by an alkyl group or a crosslinkable compound having a polymerizable unsaturated bond is preferred. It is necessary to have two or more of these substituents or polymerizable unsaturated bond systems in the crosslinkable compound.

Examples of crosslinkable compounds having epoxy or isocyanate groups include bisphenol acetone glycidyl ether, phenol novolac epoxy resin, cresol novolac epoxy resin, triglycidyl isocyanurate, tetraglycidyl Diphenylene, tetraglycidyl-m-xylylenediamine, tetraglycidyl-1,3-bis(aminoethyl)cyclohexane, tetraphenylglycidyl ether ethane , triphenyl glycidyl ether ethane, bisphenol hexafluoroacetyl Diglycidyl ether, 1,3-bis(1-(2,3-epoxypropoxy)-1-trifluoromethyl-2,2,2-trifluoromethyl)benzene, 4,4-bis (2,3-Glycidyloxy) octafluorobiphenyl, triglycidyl-p-aminophenol, tetraglycidyl m-xylylenediamine, 2-(4-(2,3-glycidyloxypropoxy base)phenyl)-2-(4-(1,1-bis(4-(2,3-epoxypropoxy)phenyl)ethyl)phenyl)propane, 1,3-bis(4- (1-(4-(2,3-epoxypropoxy)phenyl)-1-(4-(1-(4-(2,3-epoxypropoxy)phenyl)-1-methyl (ethyl)phenyl)ethyl)phenoxy)-2-propanol, etc.

The crosslinkable compound which has an oxetanyl group is a compound which has at least 2 oxetanyl groups represented by following formula [4A].

Specifically, the cross-linking compounds represented by the formula [4a] to the formula [4k] disclosed on pages 58 to 59 of International Publication No. WO2011/132751 (published on October 27, 2011) can be cited.

As a crosslinking compound which has a cyclic carbonate group, it is a crosslinking compound which has at least 2 cyclic carbonate groups represented by following formula [5A].

Specifically, the formula [5-1] ~ formula [5-42] disclosed on pages 76 to 82 of International Publication No. WO2012/014898 (published on February 2, 2012) can be exemplified. Represents a cross-linking compound.

As a crosslinkable compound having at least one substituent selected from a group consisting of hydroxyl and alkoxy groups, for example, amino resins having hydroxyl or alkoxy groups include melamine resins, urea resins, guanamine resins, Glycoluril-formaldehyde resin, succinamide-formaldehyde resin, ethylene urea-formaldehyde resin, etc. Specifically, a melamine derivative, a benzoguanamine derivative, or a glycoluril in which the hydrogen atom of an amine group is substituted with a methylol group or an alkoxymethyl group or both thereof can be used. The melamine derivatives or benzoguanamine derivatives can also exist in the form of dimers or trimers. These preferably have an average of 3 or more and 6 or less methylol or alkoxymethyl groups per one triazine ring.

Examples of the above-mentioned melamine derivatives or benzoguanamine derivatives include commercially available MX-750 in which an average of 3.7 methoxymethyl groups are substituted per triazine ring, and MX-750 per triazine ring is substituted with MW-30 with an average of 5.8 methoxymethyl groups (manufactured by Sanwa Chemical Co.) or methoxymethyl groups such as CYMEL 300, 301, 303, 350, 370, 771, 325, 327, 703, 712, etc. Melamine, methoxymethylated melamine of CYMEL 235, 236, 238, 212, 253, 254, etc., butoxymethylated melamine of CYMEL 506, 508, etc., such as CYMEL 1141 and the like Carboxyl-containing methoxymethylated isobutoxymethylated melamine, methoxymethylated ethoxymethylated benzoguanamine such as CYMEL 1123, such as CYMEL 1123-10 and the like Methoxymethylated butoxymethylated benzoguanamines, butoxymethylated benzoguanamines such as CYMEL 1128, benzoguanamines such as CYMEL 1125-80 containing Methoxymethylated ethoxymethylated benzoguanamine having a carboxyl group (manufactured by Mitsui Cyanamid Co., Ltd. above). In addition, as examples of glycolurils, butoxymethylated glycolurils such as CYMEL 1170, methylolated glycolurils such as CYMEL 1172, methoxymethylated glycolurils such as Powder link 1174, etc. Kylated glycoluril, etc.

Examples of benzene or phenolic compounds having a hydroxyl group or an alkoxy group include 1,3,5-paraffin(methoxymethyl)benzene, 1,2,4-paraffin(isopropoxymethyl)benzene, 1,4-bis(sec-butoxymethyl)benzene or 2,6-dihydroxymethyl-p-tert-butyrol.

More specifically, the cross-linking compounds of [6-1] to [6-48] disclosed on pages 62 to 66 of International Publication No. WO2011/132751 (published on October 27, 2011) can be cited.

Examples of the crosslinkable compound having a polymerizable unsaturated bond include trimethylolpropane tri(meth)acrylate, neopentylthritol tri(meth)acrylate, dipenteoerythritol penta(methyl) ) acrylate, tri(meth)acryloxyethoxytrimethylolpropane, glycerol polyglycidyl ether poly(meth)acrylate, etc. have three polymerizable unsaturated groups in the molecule. Compound; Ethylene Glycol Di(meth)acrylate, Diethylene Glycol Di(meth)acrylate, Tetraethylene Glycol Di(meth)acrylate, Polyethylene Glycol Di(meth)acrylate, Propylene Glycol Di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide bisphenol A type Di(meth)acrylate, propylene oxide bisphenol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerin di (Meth)acrylate, Neopentylthritol Di(meth)acrylate, Ethylene Glycol Diglycidyl Ether Di(meth)acrylate, Diethylene Glycol Diglycidyl Ether Di(meth)acrylate, Diglycidyl phthalate di(meth)acrylate, hydroxytrimethylacetate neopentyl glycol di(meth)acrylate, etc. have crosslinkability with two polymerizable unsaturated groups in the molecule Compound; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl ( Meth)acrylate, 2-(meth)acryloxy-2-hydroxypropyl ester, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerol mono(meth)acrylate, 2- (Meth)acryloxyethyl phosphate, N-methylol (meth)acrylamide, and other crosslinkable compounds having one polymerizable unsaturated group in the molecule.

Furthermore, the compound represented by following formula [7A] can also be used.

(式[7A]中，E₁係表示選自由環己烷環、雙環己烷環、苯環、聯苯環、聯三苯環、萘環、茀環、蔥環及菲環所成群之基，E₂係表示選自由下述式[7a]及式[7b]之基，n係表示1~4的整數)

(In the formula [7A], E represents _a group selected from a cyclohexane ring, a bicyclohexane ring, a benzene ring, a biphenyl ring, a terphenyl ring, a naphthalene ring, a fennel ring, an onion ring and a phenanthrene ring. base, E represents a base selected from the following _formula [7a] and formula [7b], and n represents an integer of 1 to 4)

The above is an example of a crosslinkable compound and is not limited thereto. Also, the cross-linking compound used in the liquid crystal alignment agent of the present invention can be 1 types, or two or more types can be combined.

In the liquid crystal alignment agent of the present invention, the content of the crosslinkable compound is preferably 0.1 to 150 parts by mass relative to 100 parts by mass of all the polymer components. Among them, in order to carry out the crosslinking reaction and exhibit the intended effect, 0.1 to 100 parts by mass is preferable with respect to 100 parts by mass of all the polymer components. More preferably, it is 1 to 50 parts by mass.

As long as the liquid crystal alignment agent of the present invention does not impair the effect of the present invention, a compound that improves the uniformity of film thickness or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied can be used.

As a compound which improves the uniformity of the film thickness of a liquid crystal alignment film, or surface smoothness, a fluorine-type surfactant, a polysiloxane-type surfactant, a nonionic surfactant, etc. are mentioned.

More specifically, for example, F-Top EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd. above), MEGAFACE F171, F173, R-30 (manufactured by Dainippon Ink Co., Ltd. above), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Co., Ltd. Manufactured), AashiGuard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd. above), etc.

The amount of the surfactant used is preferably 0.01-2 parts by mass, more preferably 0.01-1 part by mass, relative to 100 parts by mass of all the polymer components contained in the liquid crystal alignment agent.

Furthermore, in the liquid crystal alignment agent, International Publication No. WO2011/132751 (published on 2011.10.27) can also be added as a compound that promotes the charge movement in the liquid crystal alignment film and promotes the charge release of the device. The nitrogen-containing heterocyclic amine compounds represented by the formulas [M1] to [M156] disclosed on pages 69 to 73 of . The amine compound can also be directly added to the liquid crystal alignment agent at a concentration of 0.1-10% by mass, preferably as a solution of 1-7% by mass for later addition. The solvent is not particularly limited as long as it can dissolve the specific polymer (A).

In the liquid crystal alignment agent of the present invention, in addition to the above-mentioned poor solvents, cross-linking compounds, resin coatings, or compounds that improve the uniformity of film thickness or surface smoothness of liquid crystal alignment films and compounds that promote charge release, as long as they do not damage Within the scope of the effect of the present invention, a dielectric or conductive substance for the purpose of changing the electrical characteristics such as the dielectric constant and conductivity of the liquid crystal alignment film may be added.

<Liquid crystal alignment film‧LCD device>

The liquid crystal alignment film is a film obtained by coating the above-mentioned liquid crystal alignment agent on a substrate, drying and firing. The substrate coated with the liquid crystal alignment agent of the present invention is not particularly limited as long as it is a highly transparent substrate. Glass substrates, silicon nitride substrates, and plastic substrates such as acrylic boards and polycarbonate substrates can also be used. At this time, it is preferable to use a substrate on which ITO electrodes and the like for driving liquid crystals are formed, in terms of simplification of the manufacturing process. In addition, in a reflective liquid crystal display element, if only one side of the substrate is used, an opaque object such as a silicon wafer can also be used, and a light-reflecting material such as aluminum can also be used for the electrode at this time.

The coating method of the liquid crystal alignment agent is not particularly limited. Industrially speaking, screen printing, offset printing, flexographic printing, inkjet method, etc. The method of carrying out is general. As other coating methods, there are dipping method, roll coating method, slot coating method, spinner method, spray method, etc., and these may be used depending on the purpose.

After the liquid crystal alignment agent is coated on the substrate, it can be made into a liquid crystal alignment film after the solvent is evaporated by heating methods such as a heating plate, a thermal cycle oven, and an IR (infrared) oven. In the drying and firing steps after coating the liquid crystal alignment agent of the present invention, any temperature and time can be selected. Generally speaking, in order to fully remove the contained solvent, for example, at 50~120°C, preferably at 60~100°C, for 1~10 minutes, preferably drying for 1~5 minutes, and then at 150~300°C , preferably at 180-250°C for 5-120 minutes, preferably 10-60 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 5-300nm is preferable, and 10-200nm is more preferable.

The method of aligning the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be rubbing treatment, but photo-alignment treatment is suitable. As a preferred example of the photo-alignment treatment method, it can be exemplified on the surface of the aforementioned liquid crystal alignment film, and irradiated with radiation deflected in a certain direction. The method of liquid crystal alignment (also known as liquid crystal alignment energy). As the radiation system, ultraviolet rays or visible rays having a wavelength of 100 to 800 nm can be used. Among them, 100 to 400 nm is preferable, and ultraviolet rays having a wavelength of 200 to 400 nm are more preferable.

In addition, in order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film may be heated at 50 to 250° C. and may be irradiated with radiation at the same time.

The exposure dose of the aforementioned radiation is preferably 1~10,000mJ/cm ² . Among them, 100~5,000mJ/cm ² is preferred. The liquid crystal alignment film produced in such a way can stabilize the liquid crystal molecules in a certain direction and align them.

Furthermore, the liquid crystal alignment film irradiated with the polarized radiation is contact-processed using water or a solvent by the method mentioned above.

The solvent used in the above-mentioned contact treatment is not particularly limited as long as it can dissolve the decomposition product generated from the liquid crystal alignment film by irradiation with radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, Butyl celluloid, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate Wait. Among them, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate are preferred in terms of versatility and safety of the solvent. Also preferred are water, 1-methoxy-2-propanol or ethyl lactate. One type of solvent may be used, or two or more types may be combined.

As the above-mentioned contact treatment, immersion treatment or spray treatment (also referred to as spray treatment) can be exemplified. The treatment time for these treatments is preferably 10 seconds to 1 hour in terms of efficiently dissolving the decomposed products generated from the liquid crystal alignment film by radiation. Among them, it is preferable to perform the dipping treatment for 1 to 30 minutes. Also, the solvent during the aforementioned contact treatment may be at room temperature or may be heated, but it is preferably at 10 to 80°C. Among them, 20~50°C is preferred. In addition, in terms of the solubility of the decomposed product, ultrasonic treatment or the like may be performed as necessary.

After the aforementioned contact treatment, washing (also called wetting) with low-boiling point solvents such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, etc. or firing of the liquid crystal alignment film is relatively good. At this time, either one of wetting and firing may be performed, or both may be performed. The firing temperature is preferably 150~300°C. Among them, 180~250°C is preferred. Still more preferably, it is 200~230°C. Also, 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 of a transverse electric field liquid crystal display element such as an IPS method or an FFS method, and is particularly advantageous as a liquid crystal alignment film of a FFS method liquid crystal display element. 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 manufacturing a liquid crystal cell by a known method, and using the liquid crystal cell.

As an example of a method of manufacturing a liquid crystal cell, a liquid crystal display element with a passive matrix structure will be described by way of example. Furthermore, it may be an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting a screen display.

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, for example, ITO electrodes, formed in a pattern capable of presenting a desired screen display. Next, an insulating film is provided on each substrate so as to cover a common electrode and a segment electrode. The insulating film system can be made as a SiO ₂ -TiO ₂ film formed by, for example, a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate, and another substrate is overlapped with the liquid crystal alignment film facing each other, and the periphery is bonded with a sealant. For the sealant, in order to control the gap between the substrates, the spacer is generally mixed first, and even if the in-plane part where the sealant is not provided, it is better to spread the spacer for controlling the gap between the substrates first. An opening that can be filled with liquid crystal from the outside is provided in a part of the sealant. Next, through the opening provided in the sealant, a liquid crystal material is injected into the space surrounded by the two substrates and the sealant, and then the opening is sealed with an adhesive. For the injection, a vacuum injection method or a method utilizing capillarity in the atmosphere may be used. The liquid crystal material system can also use any one of positive type liquid crystal material or negative type liquid crystal material, and the preferred one is negative type liquid crystal material. Next, setting of the polarizing plate is performed. Specifically, a pair of polarizing plates are attached to the surfaces opposite to the liquid crystal layer of the two substrates.

In the above-mentioned manner, by using the liquid crystal alignment agent of the present invention, not only image sticking caused by AC driving can be suppressed, but also a liquid crystal alignment film having both sealant and adhesion to the underlying substrate can be obtained. In particular, it is advantageous for a liquid crystal alignment film for a photo-alignment treatment method obtained by irradiating polarized radiation.

[Example]

Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these. The compound codes used below and the measurement methods of each characteristic are as follows.

NMP: N-methyl-2-pyrrolidone

BCS: Butyl Celluloid

DA-1: 1,2-bis(4-aminophenoxy)ethane

DA-2: 4-(2-(methylamino)ethyl)aniline

DA-3: p-phenylenediamine

DA-4: 4-(2-Aminoethyl)aniline

DA-5: Refer to the following formula (DA-5)

[viscosity]

The viscosity of polyamic acid ester and polyamic acid solution, etc., is using E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), with a sample volume of 1.1mL and a conical rotor TE-1 (1°34', R24), measured under the condition of temperature 25°C.

[molecular weight]

The molecular weight of polyamide ester, etc., is determined by GPC (normal temperature gel permeation Chromatography) equipment was used to measure, and the number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated as polyethylene glycol and polyethylene oxide conversion values.

GPC device: Shodex company (GPC-101), column: Shodex company (KD803, KD805 in series), column temperature: 50°C, eluent: N,N-dimethylformamide (additive is Lithium bromide-hydrate (LiBr‧H ₂ O) 30mmol/L, phosphoric acid‧anhydrous crystal (o-phosphoric acid) 30mmol/L, tetrahydrofuran (THF) 10ml/L), flow rate: 1.0ml/min

Standard samples for calibration line preparation: TSK standard polyethylene oxide (weight average molecular weight (Mw) about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Co., Ltd., and polyethylene glycol (peak molecular weight (Mp) ) about 12,000, 4,000, 1,000). In order to avoid overlapping of peaks during the measurement, 4 samples of 900,000, 100,000, 12,000, and 1,000 and 2 samples of 150,000, 30,000, and 4,000 were measured separately.

[Anisotropy of Alignment Film]

The measurement was performed using a liquid crystal alignment film evaluation system "LayScan-Labo H" (LYS-LH30S-1A) manufactured by Moritex Corporation. The polyimide film with a film thickness of 100 nm was irradiated with ultraviolet rays at a wavelength of 254 nm of linearly polarized light with an extinction ratio of 10:1 or more through a polarizing plate to measure the magnitude of anisotropy with respect to the alignment direction of the obtained alignment film.

[Production of liquid crystal cells]

Fabricate a liquid crystal cell with a configuration of a fringe field switching (Fringe Field Switching: FFS) mode liquid crystal display element.

First, a substrate with electrodes is prepared. The substrate is a glass substrate with a size of 30 mm×50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a solid pattern as a first layer constituting a counter electrode is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the 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 as the third layer is arranged to form two pixels of the first pixel and the second pixel. The size of each pixel is 10mm long and 5mm wide. 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 "ㄑ"-shaped electrode elements that are bent at the center. The width in the short-side direction of each electrode element was 3 μm, and the interval between electrode elements was 6 μm. The pixel electrodes that form each pixel are composed of multiple ㄑ-shaped electrode elements that are bent at the center, so the shape of each pixel is not rectangular, but has the same bend at the center as the electrode elements. , which is similar to the shape of the ㄑ character in bold font. In addition, each pixel is divided up and down with the curved portion in the center as a boundary, and has a first area on the upper side of the bent portion and a second area on the lower side.

When comparing the first region and the second region of each pixel, the formation directions of the electrode elements constituting the pixel electrodes are different. That is, if the rubbing direction of the liquid crystal alignment film described later is used as the reference, in the first region of the pixel, the electrode elements of the pixel electrode are formed at an angle of +10° (clockwise). In the second region of the pixel, the electrode elements of the pixel electrode are formed at an angle of -10° (clockwise). That is, in the first area and the second area of each pixel, the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode, the direction of the rotation movement (in-plane switching) in the substrate plane is Constructed in opposite directions to each other.

Next, after filtering the liquid crystal alignment agent with a filter of 1.0 μm, it is spin-coated on the prepared substrate with electrodes and a glass substrate with columnar spacers with a height of 4 μm formed on the backside with an ITO film. for coating. After drying for 5 minutes on an 80 degreeC hotplate, it baked for 20 minutes in the hot-air circulation oven of 230 degreeC, and formed the coating film of film thickness 100nm. Ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 10:1 or more are irradiated to the coating film surface through a polarizing plate. The substrate is immersed in at least one solvent selected from water and organic solvents for 3 minutes, then immersed in pure water for 1 minute, and heated on a heating plate at 150~300°C for 5 minutes to obtain a liquid crystal alignment film. the substrate. Use the above two substrates as a group, print a sealant on the substrate, and bond the other substrate so that the liquid crystal alignment film surfaces face each other and the alignment direction becomes 0°, and then harden the sealant to make a hollow crystal cell. Liquid crystal MLC-7026-100 (manufactured by Merck) was injected into this empty unit cell by the decompression injection method, and the injected After the entrance is sealed, an FFS-driven liquid crystal unit cell can be obtained. Then, the obtained liquid crystal cell was heated at 110 degreeC for 1 hour, and it was used for each evaluation after leaving overnight.

[Evaluation of afterimage after long-term AC drive]

A liquid crystal cell having the same structure as the liquid crystal cell used for the above-mentioned afterimage evaluation was prepared.

Using this liquid crystal cell, in a constant temperature environment of 60°C, an AC voltage with a frequency of 60Hz±5V was applied for 120 hours. Afterwards, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and left at room temperature for one day.

After placement, arrange the liquid crystal cell between two polarizers whose polarization axes are perpendicular to each other, turn on the backlight in advance in the state of no external voltage, and adjust the arrangement angle of the liquid crystal cell so that the luminance of the transmitted light becomes the minimum . Moreover, the rotation angle at the time of rotating a liquid crystal cell from the angle at which the 2nd area|region of the 1st pixel becomes the darkest to the angle at which the 1st area becomes the darkest was computed as angle Δ. Similarly, the second pixel compares the second area with the first area, and calculates the same angle Δ. Also, calculate the average value of the angle Δ value between the first pixel and the second pixel as the angle Δ of the liquid crystal cell, and evaluate the liquid crystal alignment by its value. That is, the smaller the value of this angle Δ, the better the liquid crystal alignment.

[Evaluation of Bright Point of Liquid Crystal Cell (Comparison)]

The evaluation of the bright point of the liquid crystal cell produced similarly to the above (production of liquid crystal cell) was performed.

It performed by observing a liquid crystal cell with a polarizing microscope (ECLIPSE E600WPOL) (made by Nikon Corporation). Specifically, the liquid crystal cell is set with crossed Nicols, the liquid crystal cell is observed with a polarizing microscope with a magnification of 5 times, and the number of bright spots confirmed is counted. If the number of bright spots is less than 10 One is "good" and more than this value is "bad".

<Synthesis Example 1>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure DA-1 1.03g (4.20mmol), DA-2 0.421g (2.80mmol), DA-3 0.76g (7.00mmol), Furthermore, after adding 33.60 g of NMP, it stirred and melt|dissolved while feeding nitrogen. While stirring the diamine solution, 2.95 g (13.16 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 3.73 g of NMP was added so that the solid content concentration became 12% by mass. Thereafter, the polyamide acid solution (A) was obtained by stirring at room temperature for 24 hours. The viscosity of the polyamic acid solution at a temperature of 25° C. is 316 mPa‧s. Moreover, the molecular weight of this polyamic acid is Mn=13530, Mw=29850.

<Synthesis Example 2>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, measure DA-1 0.95g (3.90mmol), DA-2 0.98g (6.5mmol), DA-4 0.35g (2.60mmol), Furthermore, after adding 33.15 g of NMP, it stirred and melt|dissolved while feeding nitrogen. While stirring the diamine solution, add 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride 2.74 g (12.22 mmol), and 3.73 g of NMP were further added so that the solid content concentration became 12 mass %. Thereafter, the polyamide acid solution (B) was obtained by stirring at room temperature for 24 hours. The viscosity of the polyamic acid solution at a temperature of 25° C. is 483 mPa‧s. Moreover, the molecular weight of this polyamic acid is Mn=14260, Mw=30050.

<Synthesis Example 3>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure 1.47g (6.00mmol) of DA-1 and 0.90g (6.00mmol) of DA-2, and add 31.96g of NMP, while feeding Nitrogen was dissolved while stirring. While stirring the diamine solution, 2.60 g (11.58 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 3.55 g of NMP was added so that the solid content concentration became 12% by mass. Thereafter, stirring at room temperature for 24 hours can obtain a polyamic acid solution (C). The viscosity of the polyamic acid solution at a temperature of 25° C. is 423 mPa‧s. Moreover, the molecular weight of this polyamic acid is Mn=14010, Mw=29540.

<Synthesis Example 4>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure 1.59g (6.50mmol) of DA-1 and 0.70g (6.50mmol) of DA-3, and add 33.01g of NMP, while feeding Nitrogen was dissolved while stirring. While stirring the diamine solution, 2.78 g (12.42 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 3.66 g of NMP was added so that the solid content concentration became 12% by mass. after, Stir at room temperature for 24 hours to obtain polyamic acid solution (D). The polyamic acid solution has a viscosity of 360 mPa‧s at a temperature of 25°C. Moreover, the molecular weight of this polyamic acid is Mn=13810, Mw=28400.

<Synthesis Example 5>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure DA-1 1.03g (4.20mmol), DA-3 0.76g (7.00mmol), DA-4 0.38g (2.80mmol), Furthermore, 34.38 g of NMP was added, and it stirred and melt|dissolved, sending in nitrogen. While stirring the diamine solution, 3.04 g (13.58 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 3.82 g of NMP was added so that the solid content concentration became 12% by mass. Thereafter, the polyamide acid solution (E) was obtained by stirring at room temperature for 24 hours. The viscosity of the polyamic acid solution at a temperature of 25° C. is 428 mPa‧s. Moreover, the molecular weight of this polyamic acid is Mn=14080, Mw=29960.

<Synthesis Example 6>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure 1.13g (7.50mmol) of DA-2 and 0.81g (7.50mmol) of DA-3, and add 33.87g of NMP, while feeding Nitrogen was dissolved while stirring. While stirring this diamine solution, 3.39 g (14.85 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 3.76 g of NMP was added so that the solid content concentration became 12% by mass. Thereafter, stirring at room temperature for 24 hours can obtain a polyamic acid solution (F). The polyamide The viscosity of the amine acid solution at a temperature of 25°C is 280mPa‧s. Moreover, the molecular weight of this polyamic acid is Mn=12250, Mw=26550.

<Synthesis Example 7>

In a 50mL four-neck flask with a stirring device and a nitrogen introduction tube, measure 3.36g (15.00mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride , and after adding 3.73 g of NMP, it was stirred while feeding nitrogen to dissolve it. Stirring this acid dianhydride solution, 1.13 g (12.68 mmol) of DA-3 and 0.81 g (1.50 mmol) of DA-5 were added, and 7.46 g of NMP was added further so that solid content concentration might become 10 mass %. Thereafter, the polyamide acid solution (G) was obtained by stirring at room temperature for 24 hours. The polyamic acid solution has a viscosity of 460 mPa‧s at a temperature of 25°C. Moreover, the molecular weight of this polyamic acid is Mn=15020, Mw=33320.

<Example 1>

Measure 15.00 g of 12% by mass polyamic acid solution (A) into a 100 ml Erlenmeyer flask, add 9.00 g of NMP and 6.00 g of BCS, and mix at 25°C for 8 hours to obtain liquid crystal alignment agent (1). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Example 2>

Except for using 15.00 g of 12% by mass polyamic acid solution (B), the liquid crystal alignment agent was obtained in the same manner as in Example 1 (2). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Example 3>

Except having used 15.00 g of 12 mass % polyamic-acid solutions (C), it carried out similarly to Example 1, and obtained the liquid crystal alignment agent (3). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Comparative example 1>

Except having used 15.00 g of 12 mass % polyamic-acid solutions (D), it carried out similarly to Example 1, and obtained the liquid crystal aligning agent (4). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Comparative example 2>

Except having used 15.00 g of 12 mass % polyamic-acid solutions (E), it carried out similarly to Example 1, and obtained the liquid crystal aligning agent (5). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Comparative example 3>

Except for using 15.00 g of 12% by mass polyamic acid solution (F), the liquid crystal alignment agent was obtained in the same manner as in Example 1 (6). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Comparative example 4>

Except having used 15.00 g of 12 mass % polyamic-acid solutions (G), it carried out similarly to Example 1, and obtained the liquid crystal aligning agent (7). Abnormalities such as turbidity and precipitation were not found in this liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

(Example 5)

After filtering the said liquid crystal alignment agent (1) with the filter of 1.0 micrometers, it spin-coated and applied on the ITO board|substrate of 30 mm x 40 mm. After drying for 2 minutes on an 80° C. hot plate, it baked for 14 minutes in a 230° C. hot air circulation oven to form a coating film with a film thickness of 100 nm. A liquid crystal alignment film can be obtained by irradiating the surface of this coating film with ultraviolet light having a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate.

The height of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The anisotropy value at 200mJ/cm ² of the above ultraviolet radiation was 3.39, 4.10 at 300mJ/cm ² , and 3.26 at 400mJ/cm ² . The above-mentioned irradiation dose of ultraviolet rays with the highest anisotropy is 300 mJ/cm ² , which is the most suitable irradiation condition under photo-alignment treatment.

(Example 6)

Except for using the liquid crystal alignment agent (2) above, a liquid crystal alignment film was obtained in the same manner as in Example 5. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The anisotropy value at 50mJ/cm ² of the above ultraviolet radiation is 0.05, 0.61 at 100mJ/cm ² , and 0.06 at 200mJ/cm ² . The irradiation amount of the above-mentioned ultraviolet rays at which the anisotropy becomes the largest is 100 mJ/cm ² , which is the most suitable irradiation condition in the photo-alignment process.

(Example 7)

Except for using the above liquid crystal alignment agent (3), the liquid crystal alignment film can be obtained after the implementation is the same as in Example 5. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The above-mentioned ultraviolet irradiation amount is 0.10 at 50mJ/cm ² , 0.92 at 100mJ/cm ² , and 0.15 at 200mJ/cm ² . The irradiation amount of the above-mentioned ultraviolet rays at which the anisotropy becomes the largest is 100 mJ/cm ² , which is the most suitable irradiation condition in the photo-alignment process.

(comparative example 5)

Except for using the liquid crystal alignment agent (4) above, a liquid crystal alignment film was obtained in the same manner as in Example 5. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The above-mentioned ultraviolet irradiation amount is 3.02 at 100mJ/cm ² , 5.37 at 200mJ/cm ² , and 3.40 at 300mJ/cm ² . The irradiation amount of the above-mentioned ultraviolet rays at which the anisotropy becomes the largest is 200 mJ/cm ² , which is the most suitable irradiation condition in the photo-alignment process.

(comparative example 6)

Except for using the liquid crystal alignment agent (5) above, a liquid crystal alignment film was obtained in the same manner as in Example 5. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The above-mentioned ultraviolet irradiation amount is 4.28 at 200mJ/cm ² , 4.57 at 300mJ/cm ² , and 3.03 at 400mJ/cm ² . The irradiation amount of the above-mentioned ultraviolet rays at which the anisotropy becomes the largest is 300 mJ/cm ² , which is the most suitable irradiation condition in the photo-alignment process.

(comparative example 7)

Except for using the liquid crystal alignment agent (6) above, a liquid crystal alignment film was obtained in the same manner as in Example 5. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The above-mentioned ultraviolet irradiation amount is 0.54 at 300mJ/cm ² , 0.65 at 400mJ/cm ² , and 0.60 at 500mJ/cm ² . The irradiation amount of the above-mentioned ultraviolet rays at which the anisotropy becomes the largest is 400 mJ/cm ² , which is the most suitable irradiation condition in the photo-alignment process.

(comparative example 8)

A liquid crystal alignment film was obtained in the same manner as in Example 5, except that the above-mentioned liquid crystal alignment agent (7) was used. The size of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The above-mentioned ultraviolet irradiation amount is 1.61 at 400mJ/cm ² , 1.71 at 600mJ/cm ² , and 1.59 at 800mJ/cm ² . Anisotropy becomes the maximum, and the above-mentioned irradiation amount of ultraviolet rays is 600 mJ/cm ² , which is the most suitable irradiation condition under photo-alignment treatment.

In Examples 5-7 and Comparative Examples 5-8, the measurement results of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film are summarized in Table 1 and shown.

(Embodiment 8)

After filtering the above-mentioned liquid crystal alignment agent (1) with a filter of 1.0 μm, rotate it on the prepared substrate with the above-mentioned electrodes and the glass substrate with a columnar spacer with a height of 4 μm formed on the back with an ITO film. Coating for coating. After drying for 5 minutes on an 80 degreeC hotplate, it baked for 20 minutes in the hot-air circulation oven of 230 degreeC, and formed the coating film of film thickness 100nm. The surface of this coating film was irradiated with 0.3 J/cm ² of ultraviolet rays having a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate. Afterwards, after heating for 14 minutes on a heating plate at 230° C., a substrate with a liquid crystal alignment film can be obtained. Use the above two substrates as a group, print a sealant on the substrate, and bond the other substrate so that the liquid crystal alignment film faces each other and the alignment direction becomes 0°, and then harden the sealant to create an empty unit cell . Liquid crystal MLC-7026-100 (manufactured by Merck) was injected into the empty unit cell by a depressurized injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal unit cell. Afterwards, the obtained liquid crystal cell was heated at 110° C. for 1 hour, and left overnight to carry out image sticking evaluation of long-term AC driving. The angle Δ value of the liquid crystal unit cell after long-term AC driving is 0.04 degrees. Also, as a result of observation of bright spots in the unit cell, the number of bright spots was less than 10, which was good.

(Example 9)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8, except that the above-mentioned liquid crystal alignment agent (2) was used. After irradiating the surface of the coating film with 0.1J/ ^cm2 of ultraviolet rays with a wavelength of 254nm and a linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, heat it on a heating plate at 230°C for 14 minutes to obtain a liquid crystal alignment film. substrate. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle △ value of the liquid crystal unit cell is 0.10 degrees after long-term AC driving. Also, as a result of observation of bright spots in the unit cell, the number of bright spots was less than 10, which was good.

(Example 10)

After irradiating polarized ultraviolet rays, it was immersed in 2-propanol for 3 minutes, and then it was immersed in pure water for 1 minute, and the FFS drive liquid crystal cell was produced by the method similar to Example 9. For this FFS-driven liquid crystal cell, carry out the afterimage evaluation of long-term AC drive. The angle △ value of the liquid crystal unit cell is 0.08 degrees after long-term AC driving. Also, as a result of observation of bright spots in the unit cell, the number of bright spots was less than 10, which was good.

(Example 11)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8 except for using the above-mentioned liquid crystal alignment agent (3). After irradiating the surface of this coating film with 0.1J/ ^cm2 of ultraviolet rays with a wavelength of 254nm and a linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, immerse it in 2-propanol for 3 minutes, and then immerse it in pure water for 1 minute. Afterwards, it was heated on a heating plate at 230° C. for 14 minutes to obtain a substrate with a liquid crystal alignment film. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle △ value of the liquid crystal unit cell is 0.08 degrees after long-term AC driving. Also, as a result of observation of bright spots in the unit cell, the number of bright spots was less than 10, which was good.

(comparative example 9)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8, except that the above-mentioned liquid crystal alignment agent (4) was used. The coating surface was irradiated with 0.2 J/cm ² of ultraviolet rays having a wavelength of 254 nm and a linearly polarized light with an extinction ratio of 26:1 through a polarizing plate. Afterwards, it was heated on a heating plate at 230° C. for 14 minutes to obtain a substrate with a liquid crystal alignment film. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle Δ value of the liquid crystal unit cell after long-term AC driving is 0.15 degrees. In addition, as a result of observation of bright spots in the unit cell, the number of bright spots was 10 or more, which was considered unfavorable.

(comparative example 10)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8, except that the above-mentioned liquid crystal alignment agent (5) was used. The surface of this coating film was irradiated with 0.3 J/cm ² of ultraviolet rays having a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate. Afterwards, it was heated on a heating plate at 230° C. for 14 minutes to obtain a substrate with a liquid crystal alignment film. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle Δ value of the liquid crystal unit cell is 0.20 degrees after long-term AC driving. In addition, as a result of observation of bright spots in the unit cell, the number of bright spots was 10 or more, which was considered unfavorable.

(comparative example 11)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8, except that the above-mentioned liquid crystal alignment agent (6) was used. This coating film surface was irradiated with 0.4 J/cm ² of ultraviolet rays having a wavelength of 254 nm and a linearly polarized light with an extinction ratio of 26:1 through a polarizing plate. Afterwards, it was heated on a heating plate at 230° C. for 14 minutes to obtain a substrate with a liquid crystal alignment film. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle Δ value of the liquid crystal unit cell is 0.20 degrees after long-term AC driving. In addition, as a result of observation of bright spots in the unit cell, the number of bright spots was 10 or more, which was considered unfavorable.

(comparative example 12)

A coating film having a film thickness of 100 nm was formed in the same manner as in Example 8 except for using the above-mentioned liquid crystal alignment agent (7). The coating surface was irradiated with 0.6 J/cm ² of ultraviolet rays having a wavelength of 254 nm and linearly polarized at an extinction ratio of 26:1 through a polarizing plate. Afterwards, it was heated on a heating plate at 230° C. for 14 minutes to obtain a substrate with a liquid crystal alignment film. Except for using the substrate with the liquid crystal alignment film, the same method as in Example 8 was used to manufacture the FFS-driven liquid crystal cell, and the long-term AC driving image sticking evaluation was performed on the obtained unit cell. The angle △ value of the liquid crystal unit cell is 0.24 degrees after long-term AC driving. Also, as a result of observation of bright spots in the unit cell, the number of bright spots was 10 or more, which was considered unfavorable.

[Industrial Utilization]

The liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention has fewer bright spots that cause contrast reduction, and can reduce the residue caused by AC driving in the liquid crystal display element of the IPS driving mode or the FFS driving mode. It is possible to obtain liquid crystal display elements of IPS driving method or FFS driving method with excellent image sticking characteristics.

The liquid crystal display element with the liquid crystal alignment film of the present invention is excellent in reliability, so it can be widely used in large-screen, high-definition and high-quality LCD TVs or small and medium-sized car navigation systems or smart phones.

Still, the Japanese Patent Application No. 2014-219597 specification, scope of claims, and abstract filed on October 28, 2014 are cited here, and incorporated as the disclosure of the specification of the present invention.

Claims (11)

A liquid crystal alignment agent capable of obtaining a liquid crystal alignment film for photo-alignment treatment capable of suppressing the generation of bright spots even when negative type liquid crystals are used, characterized by containing an imide selected from polyimide precursors and the polyimide precursors At least one type of polymer (A) in which the aminated polymer is grouped, the aforementioned polyimide precursor has a structural unit represented by the following formula (1) and a structure represented by the following formula (2) unit, and the aforementioned liquid crystal is a negative type liquid crystal material,

(In formula ( ₁ ) and formula ( ₂ ), X1 and X2 are independently at least one selected from the group of structures represented by the following formulas (X1-1) and (X1-2), R ₁ , R ₂ , R ₃ , R ₄ , and R ₆ are independently hydrogen atoms, R ₅ is an alkyl group with 1 to 4 carbons, n is an integer of 1 to 3)

The liquid crystal alignment agent according to Claim 1, wherein the proportion of the structural unit represented by the above formula (1) is 10 to 50 mol% relative to 1 mol of the total structural unit of the polymer (A), And the above formula (2) The content ratio of the indicated structural unit is 20 to 90 mol% with respect to 1 mol of all structural units of the above-mentioned polymer (A). The liquid crystal alignment agent according to claim 1 or 2, wherein the structural unit represented by the above formula (1) and the structural unit represented by the above formula (2) can exist in the same polyimide precursor, and the above The structural unit represented by the formula (1) and the structural unit represented by the above formula (2) may exist in separate polyimide precursors. The liquid crystal alignment agent according to claim 1 or 2, wherein, in the above formulas (1) and (2), X ₁ and X ₂ are the aforementioned formula (X1-2). The liquid crystal alignment agent according to claim 1 or 2, wherein, in formula (1) and formula (2), R ₅ is methyl, and n is 2. The liquid crystal alignment agent according to claim 1 or 2, which contains 2 to 10% by mass of the above-mentioned polymer (A). The liquid crystal alignment agent according to claim 1 or 2, wherein the above-mentioned liquid crystal alignment film for photo-alignment treatment is used for a liquid crystal display element in a transverse electric field mode. A method for manufacturing a liquid crystal alignment film, which is characterized in that the film obtained by coating and firing the liquid crystal alignment agent according to any one of claims 1 to 7 is irradiated with polarized ultraviolet rays. The method of manufacturing a liquid crystal alignment film according to claim 8, wherein the above-mentioned polarized ultraviolet light has a wavelength of 100-800 nm. A liquid crystal display element, characterized by having a liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film as claimed in claim 8 or 9. The liquid crystal display element according to claim 10, wherein the above-mentioned liquid crystal is a negative type liquid crystal material.