TW201504344A - Liquid crystal aligning agent for in-plane switching - Google Patents

Abstract

Provided are: a liquid crystal aligning agent which is capable of eliminating a feeling of strangeness about the color of a display screen in an in-plane switching liquid crystal display element, said feeling of strangeness being based on a black component; a liquid crystal alignment film; and a liquid crystal display element. A liquid crystal aligning agent for in-plane switching, which is characterized by containing a polyimide that is obtained by ring-closing a polyimide precursor that has a structural unit represented by formula (1) as a structural unit that is derived from a tetracarboxylic acid dianhydride. In formula (1), X1 represents a tetravalent organic group represented by formula (X1); and R1 represents a hydrogen atom or an alkyl group having 1-10 carbon atoms.

Description

Liquid crystal alignment treatment agent for driving transverse electric field

The present invention relates to a liquid crystal alignment treatment agent used for a liquid crystal element of a transverse electric field drive method, a liquid crystal alignment film using the same, and a transverse electric field drive type liquid crystal element.

The liquid crystal display element is a display element that utilizes electrical and optical changes of liquid crystal, and its characteristics such as small size, light weight, and low power consumption are attracting attention, and in recent years, it has been remarkably developed as a display device for various displays.

The liquid crystal display device is configured to apply an electric field in a direction perpendicular to the substrate to drive liquid crystal molecules that are aligned in parallel to a pair of transparent substrates for display, and to apply an electric field in a direction parallel to the substrate. In the form of display. The former is called a liquid crystal display device of the TN mode, and the latter is called a liquid crystal display device of a transverse electric field drive mode (IPS).

In the liquid crystal display device of the transverse electric field driving method, basically, even if the short-axis direction of the liquid crystal molecules is observed even when the viewpoint is moved, the "erecting mode" of the liquid crystal molecules does not depend on the viewing angle, and can be achieved. A wider viewing angle than the TN mode liquid crystal display device (refer to Patent Document 1). Therefore, in recent years, compared with the liquid crystal display device of the TN mode, there has been a tendency to bias the liquid crystal display device using the IPS mode in recent years.

As a liquid crystal alignment film in a liquid crystal display device of such a lateral electric field drive method, a polyimide film is preferably used in view of chemical stability, thermal stability, and the like.

Polyimine-based liquid crystal alignment film, generally, a polyamic acid (also known as polyamide acid) solution as a polyimide precursor is coated on a substrate, at 150 After sintering at a temperature of ° C or higher, the ruthenium is imidized, and then subjected to a rubbing treatment to form a liquid crystal alignment film.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2-37324

From the viewpoint of producing a liquid crystal display element, it is important that the alignment film has characteristics such as tightness, printability, and abrasion resistance of the substrate. In particular, although the rubbing treatment is a liquid crystal alignment treatment method used in the industry, the display characteristics are affected by the peeling of the liquid crystal alignment film from the substrate or the damage of the liquid crystal alignment film due to the friction during the rubbing. The problem point.

A liquid crystal alignment film obtained by a conventional polyimine-based liquid crystal alignment treatment agent, wherein both of the solvent-soluble polyimine and the poly-proline contained in the liquid crystal alignment treatment agent have opposite phases as the liquid crystal alignment film. Advantages and disadvantages, it is not easy to satisfy all the characteristics required as a liquid crystal alignment film. Therefore, it is strongly desired to develop a liquid crystal alignment treatment agent which is excellent in printability, tightness, and abrasion resistance of a substrate, and which has high reliability.

In addition, according to the findings of the present inventors, in the liquid crystal display device of the above-described lateral electric field drive type, when a liquid crystal alignment film is formed from a polyimine-based liquid crystal alignment treatment agent, the obtained liquid crystal display element is used. There is a problem with the black level in color display, and an uncomfortable feeling is generated in the hue of the picture. In this case, in the liquid crystal display device of the lateral electric field drive method, the orientation of the guide body in which the liquid crystal molecules are arranged is determined by applying a rubbing treatment to the liquid crystal alignment film. Therefore, after the rubbing step, variations in the initial alignment may occur. The deterioration of the black level is regarded as a phenomenon caused by the disorder of the initial alignment, and becomes a problem that should be eliminated.

Here, as one of the means for eliminating the disorder of the initial alignment, a solution containing a solvent-soluble polyimine is applied to a substrate and sintered to form a liquid crystal alignment film. However, solvent-soluble polyimine, in general, is poorly soluble compared to polyimine precursors, and the diamines currently available are also limited. In particular, when a diamine having a high crystallinity is used, the solubility tends to be deteriorated, and when the diamine is used, there is a problem that the amount of introduction is limited.

Accordingly, it is an object of the present invention to provide a method for obtaining an uncomfortable feeling in a hue of a picture based on a black element. A liquid crystal display device for a lateral electric field drive type of a liquid crystal alignment film which is excellent in printability and tightness to a substrate and which is not peeled off from the substrate during polishing and which is less likely to be damaged by the polishing film. A polyimine-based liquid crystal alignment treatment agent, a liquid crystal alignment film using the same, and a liquid crystal element of a transverse electric field drive method.

The inventors of the present invention have conducted intensive studies in order to achieve the above object, and have focused on the use of solvent-soluble polyimine as a polyimine-based liquid crystal alignment treatment agent, and using bicyclo[3.3.0]octane-2,4, 6,8-tetracarboxylic dianhydride is a tetracarboxylic dianhydride component which is a raw material of one of solvent-soluble polyimine. Further, it has been found that by using a liquid crystal alignment treatment agent containing the solvent-soluble polyimine, in the liquid crystal display device of the transverse electric field drive mode, the image based on the black element can be eliminated without affecting other characteristics. The problem of uncomfortable feeling in the hue.

The present invention is based on the findings and is based on the following.

A liquid crystal alignment treatment agent for a transverse electric field, which comprises: dehydrating a polyfluorene imine precursor having a structural unit represented by the following formula (1) as a structural unit derived from tetracarboxylic dianhydride And get the polyimine.

In the formula (1), X ¹ is a tetravalent organic group represented by the following formula (X ¹ ), and R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

2. The liquid crystal alignment treatment agent for a transverse electric field according to the above 1, wherein the polyamidene precursor has a structural unit represented by the following formula (2) as a structural unit derived from a diamine.

In the formula (2), n is 1 to 12.

3. As 1 or 2, the transversal electric field driving the alignment of the liquid crystal with the treating agent, wherein the above formula (X ¹⁾ of the tetravalent organic group represented, for the selected formula [IV] ~ [VI] isomers thereof a single ingredient or a mixture of such.

4. The liquid crystal alignment treatment agent for transverse electric field drive according to the above 3, wherein the content of the isomer [IV] is 90% or more.

5. The liquid crystal alignment treatment agent for transverse electric field according to any one of the above 1 to 4, wherein the content of the structural unit represented by the above formula (1) is 1 mol relative to the total structural unit derived from the tetracarboxylic acid derivative. , 30% to 100% by mole.

6. The liquid crystal alignment treatment agent for transverse electric field according to any one of the above 1 to 5, wherein the content of the structural unit represented by the formula (2) is 20 per mol of the structural unit derived from the diamine. ~100% by mole.

A liquid crystal alignment film for driving a transverse electric field, which is obtained by applying a liquid crystal alignment treatment agent according to any one of the above 1 to 6 to a substrate and sintering it.

A liquid crystal display element for driving a transverse electric field, comprising the liquid crystal alignment film of the above seventh.

According to the liquid crystal alignment treatment agent of the present invention, in the liquid crystal display element of the transverse electric field drive mode, the element according to black can be solved. A problem of uncomfortable feeling in the hue of the screen, and a liquid crystal alignment film which is excellent in printability and tightness to the substrate, is not peeled off from the substrate during polishing, and is not easily damaged by the rubbing film to the alignment film. .

According to the liquid crystal alignment agent of the present invention, the mechanism for solving the problem of causing an uncomfortable feeling in the hue of the black element-based screen in the liquid crystal display device of the transverse electric field drive type is not clear, but it can be roughly estimated as follows.

Since a circuit having intense concavities and convexities is formed on the solid substrate of the liquid crystal display element, the liquid crystal must be uniformly aligned even in the flat portion and the step portion. On the flat portion, a strong liquid crystal alignment property is required, and on the other hand, the elongation of the polymer chain is important in the step portion. Since the brushing conditions are different due to the influence of the step, the improvement of the elongation characteristics by the flexibility of the film is extremely effective for the step portion. In the present invention, it can be considered that by using a specific diamine compound having a good alignment property and a specific tetracarboxylic dianhydride having flexibility, it is possible to improve the alignment order on the flat portion and the step portion. .

<Liquid alignment treatment agent>

The liquid crystal alignment treatment agent of the present invention is characterized by comprising a polyfluorene obtained by ring-closing a polyimine precursor having a structural unit represented by the following formula (1) as a structural unit derived from tetracarboxylic dianhydride. Imine.

In the formula (1), X ¹ is a tetravalent organic group represented by the following formula (X ¹ ), and R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

The structure represented by the formula (X ¹ ) is derived from bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid. Bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid having (X ¹ ) having structural isomers of the following formulas [IV], [V], and [VI], but In the present invention, one of the isomers may be used to produce a polyimide precursor, or a mixture of isomers may be used to produce a polyimide precursor. In the production of the polyimine precursor, the content of the isomer [IV] is preferably 90% or more, and particularly preferably 95% or more from the viewpoint of polymerization reactivity.

In the polyimine precursor of the present invention, the structural unit of the formula (1) is preferably 1 to 30 mol%, more preferably 50 to 100 mol%, based on the total structural unit derived from the tetracarboxylic acid derivative. 80% by mole.

The polyimine precursor used in the present invention may comprise a structural unit represented by the following formula (3) as a structural unit derived from a tetracarboxylic acid derivative.

In the formula (3), R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X is a tetravalent organic group. However, X is deducted from X ¹ in the above formula (1).

Specific examples of X are shown, and (X-1) to (X-42) shown below are exemplified.

In the above formula (X-1), R ³ to R ⁶ each independently represent a hydrogen atom, an alkyl group or a phenyl group. Among them, from the viewpoint of the availability of the compound, the structure of X may be exemplified by the formula (X-1) (R ³ to R ⁶ are each a hydrogen atom, or R ³ and R ⁵ are a methyl group, R ⁴ and R ⁶ is a hydrogen atom), (X-2), (X-5), (X-6), (X-7), (X-17), (X-25), (X-26), (X-27), (X-28), (X-32), and (X-39). Further, from the viewpoint of obtaining a liquid crystal alignment film having a high relaxation rate of residual charge accumulated by a DC voltage, it is preferred to use a tetracarboxylic dianhydride having an aromatic ring structure, and the structure of X is particularly preferably a formula (X). -26), (X-27), (X-28), (X-32), (X-35), and (X-37).

In the formula (3), specific examples of the above alkyl group in R ² include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group. , n-pentyl and so on.

The ratio of the structural unit represented by the formula (3) in the polyimine precursor used in the present invention, relative to the polyimide precursor The structural unit is 1 mol, preferably 0 to 70 mol%, and particularly preferably 20 to 50 mol%.

Further, the polyimine precursor used in the present invention may comprise a structural unit represented by the following formula (4) as a structural unit derived from a diamine.

In the formula (4), A ¹ and A ² are each independently a hydrogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an alkenyl group having 1 to 15 carbon atoms which may have a substituent. Or an alkynyl group having 1 to 15 carbon atoms which may have a substituent. In the formula (4), these groups are not only chain members, but also those having a ring structure.

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a tertiary butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group, and a dicyclohexyl group. The alkenyl group may be one in which one or more CH-CH structures present in the above alkyl group are substituted with a C=C structure, and specific examples thereof include a vinyl group, an allyl group, a 1-propenyl group, an isopropenyl group, and a 2- Butenyl, 1,3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl, and the like. The alkynyl group may be a structure in which one or more CH ₂ -CH ₂ structures present in the above alkyl group are substituted with a C≡C structure, and specific examples thereof include an ethynyl group, a 1-propynyl group, a 2-propynyl group, and the like. .

The above alkyl group, alkenyl group, alkynyl group may have a substituent, and A ring structure can be formed by a substituent. The formation of a ring structure by a substituent means that the substituents are bonded to each other or a part of the substituent to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organic oxy group, an organic thio group, an organic decyl group, a decyl group, an ester group, a thioester group, a phosphate group, and Amidino, alkyl, alkenyl, alkynyl.

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

The aryl group of the substituent may, for example, be a phenyl group. Among the aryl groups, the other substituents described above may be further substituted.

The organooxy group of the substituent may exhibit a structure represented by OR. The organothio group of the substituent may exhibit a structure represented by -SR. The organoalkylene group of the substituent may exhibit a structure represented by -Si-(R) ₃ . The thiol group of the substituent may exhibit a structure represented by -C(O)-R. The ester group of the substituent may exhibit a structure represented by -C(O)OR or -OC(O)-R. The thioester group of the substituent may exhibit a structure represented by -C(S)OR or -OC(S)-R. The phosphate group of the substituent may exhibit a structure represented by -OP(O)-(OR) ₂ . The amine group of the substituent may be represented by -C(O)NH ₂ , or -C(O)NHR, -NHC(O)R, -C(O)N(R) ₂ , -NRC(O) The structure shown by R.

These R may be the same or different and may be exemplified by the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. In the above R, the above substituent may be further substituted.

Specific examples of the organic oxy group include methoxy group and ethoxy group. Base, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy and the like.

Specific examples of the organic sulfur group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group and the like.

Specific examples of the organic decyl group include a trimethyl decyl group, a triethyl decyl group, a tripropyl decyl group, a tributyl decyl group, a tripentyl decyl group, a trihexyl decyl group, and a pentyl dimethyl group. a decyl group, a hexyl dimethyl decyl group, and the like.

Specific examples of the mercapto group include a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a pentamidine group, an isovaleryl group, a benzamidine group, and the like.

The aryl group of the substituent may be the same as the above aryl group. Among the aryl groups, the other substituents described above may be further substituted.

The alkyl group of the substituent may be the same as the alkyl group described above. In the alkyl group, the other substituents described above may be further substituted.

The alkenyl group of the substituent may be the same as the above alkenyl group. In the alkenyl group, the other substituents described above may be further substituted.

The alkynyl group of the substituent may be the same as the alkynyl group described above. Among the alkynyl groups, the other substituents described above may be further substituted.

In general, when a larger volume structure is introduced, A ¹ and A ² are preferably a hydrogen atom or a carbon number which may have a substituent, since the reactivity of the amine group or the liquid crystal alignment property may be lowered. The alkyl group of 5 is particularly preferably a hydrogen atom, a methyl group or an ethyl group.

Y is a divalent organic group, and the structure is not particularly limited and can be mixed In two or more types. Here, specific examples are given, and the following Y-1 to Y-118 are mentioned.

Among them, in order to obtain good liquid crystal alignment, it is preferred to introduce a highly linear diamine into the polyphthalate, and Y is preferably Y-7, Y-21, Y-22, Y-23, Y. -25, Y-26, Y-27, Y-43, Y-44, Y-45, Y-46, Y-48, Y-63, Y-71, Y-73, Y-74, Y-75 , Y-98, Y-99, Y-100 diamine. Further, when it is desired to increase the pretilt angle, it is preferred to introduce a diamine having a long chain alkyl group, an aromatic ring, an aliphatic ring, a steroid skeleton, or a combination thereof in a side chain. Jia is Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, Y-86, Y-87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96, Y-97 diamine. Any pretilt angle can be exhibited by adding 1 to 50 mol% of these diamines to all diamines. Further, when the rubbing property is improved, a diamine of Y-118 is preferred.

In the formula (Y-109), m and n are each an integer of 1 to 11, m+n is an integer of 2 to 12, and in the formula (Y-114), h is an integer of 1 to 3, and the formula (Y-111) And (Y-117), j is an integer of 0 to 3.

Further, the polyimine precursor used in the present invention preferably comprises a structural unit represented by the following formula (2) as a structural unit derived from a diamine from the viewpoint of liquid crystal alignment, as The structural unit shown in formula (4).

n in the formula (2) is from 1 to 12, preferably from 1 to 5.

The structural unit represented by the formula (2) is preferably 10 to 100 mol%, more preferably 20 to 100 mol%, and particularly preferably 20 to 100 mol%, based on the structural unit of the structural unit represented by the formula (4). It is 40~100% by mole.

<Polyurethane>

When the polyimine precursor used in the present invention is a polyphthalate, the polyphthalate can be synthesized by the methods (1) to (3) shown below.

(1) Synthetic conditions synthesized by polyaminic acid

The polyglycolate can be synthesized by esterifying a polyamine obtained from a tetracarboxylic dianhydride and a diamine.

Specifically, the polylysine may be reacted with the esterifying agent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C in the presence of an organic solvent for 30 minutes to 24 hours, preferably 1 to 4 Synthesized in hours.

The esterifying agent is preferably one which can be easily removed by purification, and examples thereof include N,N-dimethylformamide dimethyl acetal and N,N-dimethylformamide diethyl acetal. , N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dipinobutyl acetal, N,N-dimethylformamide II (third grade Butyl)acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene, 4-(4, 6-Dimethoxy-1,3,5-triazinetriazin-2-yl)-4-methylmorpholinium chloride or the like. The amount of the esterifying agent to be added is preferably 2 to 6 mol equivalents per 1 mol of the repeating unit of polylysine.

The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of solubility of the polymer. One type may be used or two or more types may be used in combination. The concentration at the time of the synthesis is preferably from 1 to 30% by mass, particularly preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer is less likely to occur and that a high molecular weight body is easily obtained.

(2) Synthesis by reaction of dicarboxylic acid dicarboxylate with diamine

Polyammonium esters can be synthesized from dicarboxylic acid dicarboxylic acid diesters and diamines.

Specifically, in the presence of a base and an organic solvent, the dicarboxylic acid dicarboxylic acid diester and the diamine are reacted at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably. It is synthesized for 1 to 4 hours.

As the base, pyridine, triethylamine or 4-dimethylaminopyridine can be used, and since the reaction can be carried out stably, pyridine is preferred. The amount of the base to be added is preferably 2 to 4 moles per mole of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal amount and easy availability of a high molecular weight body.

The solvent to be used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of the solubility of the monomer and the polymer. These may be used alone or in combination of two or more. use. The concentration of the polymer at the time of synthesis is not easy From the viewpoint of causing precipitation of the polymer and easily obtaining a high molecular weight body, it is preferably from 1 to 30% by mass, particularly preferably from 5 to 20% by mass. Further, in order to prevent hydrolysis of the dicarboxylic acid dicarboxylic acid diester, the solvent used for the synthesis of the polyphthalate is preferably dehydrated as much as possible, and is preferably contained in a nitrogen atmosphere to prevent the incorporation of external gas. .

(3) The case of synthesizing tetracarboxylic acid diester and diamine

Polyammonium esters can be synthesized by polycondensation of a tetracarboxylic acid diester with a diamine.

Specifically, the tetracarboxylic acid diester and the diamine can be reacted at 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C for 30 minutes to 24 hours in the presence of a condensing agent, a base, and an organic solvent. It is synthesized for 3 to 15 hours.

As the condensing agent, triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy-1,3,5-triazinemethylmorpholine salt, O-(benzotriazol-1-yl)-N,N,N',N'-four Methyl urea salt tetrafluoroborate, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea salt hexafluoroborate, (2,3-two Diphenyl 2-hydroperoxy-3-benzoxazolyl)phosphonate and the like. The amount of the condensing agent to be added is preferably 2 to 3 moles per mole of the tetracarboxylic acid diester.

As the base, a tertiary amine such as pyridine or triethylamine can be used. The amount of the base to be added is preferably 2 to 4 moles per mole of the diamine component from the viewpoint of easy removal amount and easy availability of a high molecular weight body.

Further, in the above reaction, by adding a Lewis acid as Additives allow the reaction to proceed efficiently. The Lewis acid is preferably a lithium halide such as lithium chloride or lithium bromide. The amount of the Lewis acid to be added is preferably 0 to 1.0 times the molar amount of the diamine component.

In the method for synthesizing the above three polyglycolates, a high molecular weight polyglycolate is obtained, and thus the synthesis method of the above (1) or (2) is preferred.

The solution of the polyglycolate obtained above can be precipitated by injecting a poor solvent while stirring to precipitate a polymer. After several times of precipitation and washing with a poor solvent, it is dried at normal temperature or under heating to obtain a powder of the purified polyphthalate. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<polylysine>

The polyaminic acid of the polyimine precursor used in the present invention can be synthesized by the method shown below.

Specifically, the tetracarboxylic dianhydride and the diamine may be reacted at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably 1 to 12, in the presence of an organic solvent. Synthesized in hours.

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

The polylysine obtained above can be precipitated and recovered by injecting a poor solvent while sufficiently stirring the reaction solution. Further, after several times of precipitation and washing with a poor solvent, the mixture is dried at normal temperature or under heating to obtain a powder of the purified polyamic acid. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<polyimine]

The polyimine used in the present invention can be obtained by imidating the aforementioned polyamidomate or polyphosphonium amide as a polyimide precursor. When the polyimide is produced from a polyphthalate, a basic catalyst is added to the polyphthalate solution or a polyamine which is added to dissolve the polyphthalate resin powder in an organic solvent. The chemical imidization of an acid solution is simple. The chemical hydrazine imidization is preferred because the hydrazine imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not easily lowered during the imidization.

The chemical hydrazine imidization can be carried out by stirring the polyamine phthalate imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, the solvent used in the above polymerization reaction can be used. As the basic catalyst, pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine or the like can be used. Among them, triethylamine is preferred because it has a basicity which allows the reaction to proceed sufficiently.

The temperature at which the hydrazine imidization reaction is carried out is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be increased from 1 to 100 hours. Row. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, per mole of the valinate group. The oxime imidization ratio of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature, and the reaction time. Since the added catalyst or the like remains in the solution after the hydrazine imidization reaction, it is preferred to recover the obtained quinone imidized polymer by the means described below, and dissolve it again in an organic solvent to form the present invention. Liquid crystal alignment treatment agent.

When the polyimine is produced from polylysine, it is convenient to add a catalyst to the chemical hydrazine imidization of the solution of the polyamic acid obtained by the reaction of the diamine component and the tetracarboxylic dianhydride. The chemical hydrazine imidization is preferred because the hydrazine imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not easily lowered during the imidization.

The chemical hydrazine imidization can be carried out by stirring the polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the solvent used in the above polymerization reaction can be used. As the basic catalyst, pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine or the like can be used. Among them, triethylamine is preferred because it has a moderate alkalinity for allowing the reaction to proceed. Further, examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyrogallic acid dianhydride. Among them, when acetic anhydride is used, it is preferred because it is easily purified after completion of the reaction.

The temperature at which the hydrazine imidization reaction is carried out is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be carried out in 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the prolyl group, and the amount of the acid anhydride is 1 to 50 moles of the prolyl group, preferably 3 to 30 moles. The yield of the obtained ruthenium of the polymer can be borrowed It is controlled by adjusting the amount of catalyst, temperature, and reaction time.

Since the added catalyst or the like remains in the solution after the imidization reaction of the polyphthalate solution or the polyphthalic acid, it is preferred to recover the obtained imidization by the means described below. The polymer is redissolved in an organic solvent to form a liquid crystal alignment treatment agent of the present invention.

The solution of the polyimine obtained above can be precipitated and recovered by injecting into a poor solvent while stirring sufficiently. Further, after several times of precipitation and washing with a poor solvent, the mixture is dried at normal temperature or under heating to obtain a powder of the purified polyphthalate.

The poor solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

<Liquid alignment treatment agent>

The liquid crystal alignment treatment agent used in the present invention is in the form of a solution in which a soluble polyimine having a specific structure is dissolved in an organic solvent. The molecular weight of the polyimine of a specific structure preferably has a weight average molecular weight of 2,000 to 500,000, particularly preferably 5,000 to 300,000, more preferably 10,000 to 100,000. Further, the number average molecular weight is preferably from 1,000 to 250,000, particularly preferably from 2,500 to 150,000, more preferably from 5,000 to 50,000.

The concentration of the polymer of the liquid crystal alignment agent used in the present invention can be appropriately changed by setting the thickness of the coating film to be formed, but from the viewpoint of forming a uniform and defect-free coating film, it is preferably 1% by weight or more, from the viewpoint of storage stability of the solution, preferably 10% by weight under.

The organic solvent contained in the liquid crystal alignment treatment agent used in the present invention is a polymer which can uniformly dissolve a polymer having a specific structure. Preferred examples thereof include N,N'-dimethylformamide, N,N'-diethylformamide, N,N'-dimethylacetamide, and N-methyl. -2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl azine, Dimethyl hydrazine, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N,N-dimethylpropane decylamine, and the like.

Of these, N,N'-dimethylformamide, N-methyl-2-pyrrolidone, and γ-butyrolactone are preferred, and N-methyl-2-pyrrolidone is particularly preferred.

These organic solvents may be used alone or in combination of two or more. Further, even if the solvent of the polymer cannot be uniformly dissolved alone, the organic solvent may be used in combination as long as it does not precipitate the polymer.

The liquid crystal alignment treatment agent used in the present invention may contain, in addition to the organic solvent for dissolving the polymer of a specific structure, a solvent for improving the uniformity of the coating film when the liquid crystal alignment treatment agent is applied to the substrate. The solvent is generally a solvent having a lower surface tension than the above organic solvent. Specific examples of the solution include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, and 1-methoxy- 2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, Propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene glycol, 2-(2-ethoxypropoxy) Propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and the like. These solvents may be used in combination of two or more kinds.

In addition to the above, the liquid crystal alignment agent of the present invention may be added with other materials within the range not impairing the effects of the present invention. (A) a polymer other than the polymer described in the present invention, and (B) a dielectric or a conductive material for the purpose of changing electrical properties such as dielectric constant or conductivity of the liquid crystal alignment film, (C) a decane coupling agent for the purpose of improving the tightness of the liquid crystal alignment film and the substrate, (D) a crosslinkable compound for the purpose of improving the hardness or firmness of the film when forming the liquid crystal alignment film, and (E) In the case of sintering a coating film, a ruthenium imidization accelerator or the like for the purpose of ruthenium imidization by heating of a polyimide precursor is efficiently performed.

<Liquid alignment film>

The liquid crystal alignment film of the present invention is obtained by applying the liquid crystal alignment treatment agent onto a substrate and sintering the film. The substrate to which the liquid crystal alignment agent of the present invention is applied is not particularly limited as long as it is a substrate having high transparency, and a plastic substrate such as a glass substrate, a tantalum nitride substrate, an acrylic substrate or a polycarbonate substrate can be used. From the viewpoint of simplification of the process, it is preferred to use a substrate which forms an ITO electrode or the like which is useful for driving a liquid crystal. Further, in the reflective liquid crystal display device, an opaque material such as a germanium wafer may be used as the substrate on one side, and a material such as aluminum that reflects light may be used as the electrode.

The coating method of the liquid crystal alignment treatment agent of the present invention can be listed A spin coating method, a printing method, an inkjet method, etc. are mentioned. The drying and sintering steps after the application of the liquid crystal alignment agent of the present invention can be carried out at any temperature and time. Usually, in order to sufficiently remove the organic solvent contained, it is dried at 50 ° C to 120 ° C for 1 minute to 10 minutes, and then sintered at 150 ° C to 300 ° C for 5 minutes to 120 minutes. The thickness of the coating film after sintering is not particularly limited. However, when it is too thin, the reliability of the liquid crystal display element may be lowered, so that it is 5 to 300 nm, preferably 10 to 200 nm.

The method of performing the alignment treatment on the obtained liquid crystal alignment film may, for example, be a rubbing method or a photoalignment treatment method.

Specific examples of the photo-alignment treatment method include a method of irradiating a radiation line deflected in a certain direction on the surface of the coating film, and further heat-treating at a temperature of 150 to 250 ° C depending on the case to impart a liquid crystal alignment energy. . The radiation can use ultraviolet light and visible light having a wavelength of 100 to 800 nm. Among them, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and ultraviolet rays having a wavelength of 200 to 400 nm are particularly preferable. Further, in order to improve the alignment of the liquid crystal, it is possible to irradiate the radiation while heating the coated substrate at 50 to 250 °C. The irradiation amount of the radiation is preferably from 1 to 10,000 mJ/cm ² , particularly preferably from 100 to 5,000 mJ/cm ² . The liquid crystal alignment film produced as described above can stably align liquid crystal molecules in a certain direction.

[Liquid Crystal Display Element]

In the liquid crystal display device of the present invention, the substrate having the liquid crystal alignment film is obtained from the liquid crystal alignment treatment agent of the present invention by the above-described method, and is subjected to an alignment treatment by a rubbing treatment or the like, and then formed by a known method. Horizontal electricity Field driven liquid crystal display elements.

The method for producing the liquid crystal cell of the liquid crystal display device of the transverse electric field drive method is not particularly limited, and an example is generally shown in which the liquid crystal alignment film surface is inside, and preferably 1 to 30 μm, particularly preferably 2 to 10 μm. The spacer is provided with a pair of substrates on which a liquid crystal alignment film is formed, and then the periphery is fixed with a sealant, and then liquid crystal is injected and sealed. The liquid crystal sealing method is not particularly limited, and examples thereof include a vacuum method in which a liquid crystal cell is produced by depressurizing the liquid crystal cell, and a dropping method in which liquid crystal is dropped and then sealed.

Example

The invention is illustrated in more detail in the following examples, but the invention should not be construed as limited. The abbreviations used in the following examples and comparative examples are as follows.

<tetracarboxylic acid component>

CA-1:1,2,3,4-cyclobutane tetracarboxylic dianhydride

CA-2: bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic dianhydride (content of isomer [IV] is 97%)

CA-3: pyrethic acid dianhydride

CA-4: 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride

<Diamine component>

DA-1:1,5-bis(4-aminophenoxy)pentane

DA-2: 3,5-diaminobenzoic acid

DA-3: N-(3-pyridylmethyl)-3,5-diaminobenzoic acid decylamine

DA-4: 3-aminobenzylamine

DA-5: p-phenylenediamine

DA-6: 1,3-diamino-4-n-dodecyloxybenzene

DA-7: 4,4'-diaminodiphenylmethane

DA-8: 4,4'-diaminodiphenylamine

<solvent>

BCS: butyl cellosolve

NMP: N-methyl-2-pyrrolidone

<Measurement of molecular weight of polyimine precursor and polyimine]

The molecular weight of the polyimine precursor and the polyimine in the synthesis example is a room temperature gel permeation chromatography (GPC) apparatus (GPC-101) (manufactured by Showa Denko Co., Ltd.) and a column (KD-803, KD-805) (manufactured by Shodex Co., Ltd.) was measured in the following manner.

Column temperature: 50 ° C

Dissolution: N,N'-dimethylformamide (additives include lithium bromide monohydrate (LiBr‧H ₂ O) 30 mmol/L (liter), phosphoric acid ‧ anhydrous crystals (orthophosphoric acid) 30 mmol/L (liter) Tetrahydrofuran (THF) 10ml/L)

Flow rate: 1.0ml/min

Standard sample for the production of calibration lines: TSK standard polyethylene oxide (minutes Amounts; about 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight; about 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratory).

(Determination of the imidization rate of polyimine)

The oxime imidization ratio of the polyimine in the synthesis example was measured in the following manner. 20 mg of polyimine powder was placed in an NMR (nuclear magnetic resonance) sample tube (NMR standard sampling tube, 5 (manufactured by Kusano Scientific Co., Ltd.), dimethyl-denidinide (DMSO-d6, 0.05% by mass of TMS (tetramethyl decane) mixed product) (0.53 ml) was added, and ultrasonic waves were applied thereto to completely dissolve. The solution was measured for 500 MHz proton NMR by an NMR measuring machine (JNW-ECA500) (manufactured by JEOL DATUM Co., Ltd.). The rate of ruthenium iodization is determined by using protons from a structure that does not change before and after imidization as a reference proton, and the peak value of the proton is used, and the proline from 9.5 ppm to 10.0 ppm appears. The peak value of the proton peak of the NH group is obtained by the following formula.

醯 imidization rate (%) = (1-α‧x/y) × 100

In the above formula, x is the proton peak integrated value of the NH group derived from proline, y is the peak integrated value of the reference proton, and α is the reference proton relative to the polyproline (the imidization ratio is 0%). The ratio of the number of protons of the NH group of valine.

[Synthesis Example 1]

Mix DA-1 (14.32g, 50.0) in NMP (207.4g) Methyl), DA-2 (4.56 g, 30.0 mmol), DA-3 (4.85 g, 20.0 mmol) and CA-2 (12.51 g, 50.0 mmol) were reacted at 50 ° C for 6 hours. Then, CA-1 (9.51 g, 48.5 mmol) and NMP (51.9 g) were added, and the mixture was reacted at 40 ° C for one night to obtain a polyamic acid solution (1) having a resin solid concentration of 15% by mass.

After adding NMP to the obtained polyamic acid solution (1) (100.0 g) to be diluted to 5% by mass, acetic anhydride (22.41 g) and pyridine (8.69 g) were added as a ruthenium catalyzed catalyst at 50 ° C. Reaction for 2 hours. The reaction solution was poured into methanol (1500 ml), and the obtained precipitate was filtered. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (1). The polyimine has a oxime imidization ratio of 50%, a number average molecular weight of 24,800, and a weight average molecular weight of 88,000.

[Synthesis Example 2]

DA-1 (18.61 g, 65.0 mmol), DA-2 (5.93 g, 39.0 mmol), DA-3 (6.30 g, 26.0 mmol) and CA-2 (24.40 g, 97.5 mmol) were mixed with NMP (195.3 g). ), reacted at 50 ° C for 6 hours. Then, CA-1 (5.79 g, 29.5 mmol) and NMP (48.8 g) were added, and the mixture was reacted at 40 ° C for 1 night to obtain a polyamic acid solution (2) having a resin solid concentration of 20% by mass.

After adding NMP to the obtained polyamic acid solution (2) (100.0 g) to be diluted to 5% by mass, acetic anhydride (10.87 g) and pyridine (8.43 g) were added as a ruthenium catalyzed catalyst at 90 ° C. Reaction for 2.5 hours. The reaction solution was poured into methanol (1500 ml), and the resulting precipitate was filtered. Things. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (2). The polyimine had a hydrazide conversion ratio of 50%, a number average molecular weight of 24,800, and a weight average molecular weight of 76,230.

[Synthesis Example 3]

NMP was added to the polyamic acid solution (2) (60.0 g) obtained in Synthesis Example 2 to be diluted to 5% by mass, and then acetic anhydride (13.05 g) and pyridine (4.05 g) were added as a ruthenium catalyzed catalyst. The reaction was carried out at 100 ° C for 3 hours. The reaction solution was poured into methanol (900 ml), and the obtained precipitate was filtered. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (3). The polyimine had a hydrazide conversion ratio of 70%, a number average molecular weight of 22,100, and a weight average molecular weight of 70,000.

[Synthesis Example 4]

DA-1 (30.78 g, 107 mmol), DA-2 (13.08 g, 86.0 mmol), DA-3 (5.21 g, 21.5 mmol) and CA-2 (40.35 g, 161 mmol) were mixed with NMP (278.4 g). The reaction was carried out at 50 ° C for 6 hours. Then, CA-1 (9.99 g, 50.9 mmol) and NMP (119.3 g) were added, and the mixture was reacted at 40 ° C for one night to obtain a polyamic acid solution (3) having a resin solid concentration of 20% by mass.

After adding NMP to the obtained polyamic acid solution (3) (50.0 g) to be diluted to 3.5% by mass, acetic anhydride (11.04 g) and pyridine (3.42 g) were added as a ruthenium catalyzed catalyst at 100 ° C. Reaction for 3 hours. Will The reaction solution was poured into methanol (750 ml), and the resulting precipitate was filtered. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (4). The polyimine had a hydrazide conversion ratio of 67%, a number average molecular weight of 28,500, and a weight average molecular weight of 99,600.

[Synthesis Example 5]

DA-1 (36.94 g, 129 mmol), DA-2 (13.08 g, 86.0 mmol) and CA-2 (40.35 g, 167 mmol) were mixed with NMP (280.2 g), and reacted at 50 ° C for 6 hours. Then, CA-1 (9.70 g, 49.5 mmol) and NMP (120.1 g) were added, and the mixture was reacted at 40 ° C for one night to obtain a polyamic acid solution (4) having a resin solid concentration of 20% by mass.

After adding NMP to the obtained polyamic acid solution (4) (50.0 g) to dilute to 4% by mass, acetic anhydride (10.96 g) and pyridine (3.40 g) were added as a ruthenium catalyzed catalyst at 100 ° C. Reaction for 3 hours. The reaction solution was poured into methanol (750 ml), and the obtained precipitate was filtered. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (5). The polyimine had a oxime imidization ratio of 69%, a number average molecular weight of 36,700, and a weight average molecular weight of 134,800.

[Synthesis Example 6]

DA-1 (16.04 g, 55.9 mmol), DA-2 (6.39 g, 42.0 mmol), DA-4 (5.13 g, 42.0 mmol) and CA-3 (7.02 g, 32.2 mmol) were mixed with NMP (194.7 g). ), reacting at 23 ° C for 1 small Time. Then, CA-2 (26.27 g, 105 mmol) and NMP (48.68 g) were added, and the mixture was reacted at 40 ° C for one night to obtain a polyamic acid solution (5) having a resin solid concentration of 20% by mass.

After adding NMP to the obtained polyamic acid solution (5) (40.0 g) to be diluted to 5% by mass, acetic anhydride (4.66 g) and pyridine (3.61 g) were added as a ruthenium catalyzed catalyst at 90 ° C. Reaction for 2.5 hours. The reaction solution was poured into methanol (600 ml), and the obtained precipitate was filtered. The precipitate was washed with methanol, and dried under reduced pressure at 100 ° C to obtain a polyimine powder (6). The polyimine had a hydrazide conversion ratio of 69%, a number average molecular weight of 13,900, and a weight average molecular weight of 40,600.

[Examples 1 to 6]

NMP (106.67 g) was added to each of the polyimine powders (1) to (6) (10.0 g each) obtained by the synthetic methods of Synthesis Examples 1 to 6, and the mixture was stirred at 80 ° C for 24 hours to be dissolved. BCS (50.0 g) was added to the solution, and the mixture was stirred at 23 ° C for 2 hours to obtain liquid crystal alignment treatment agents (1) to (6). In the liquid crystal alignment treatment agents (1) to (6), no abnormality such as generation of dirt or precipitates was observed, and it was confirmed that the solution was a uniform solution.

[Comparative Example 1]

A solvent-soluble polyimine of CA-4(100)/DA-5(90), DA-6(10), and CA-1 are mixed at a ratio of 95:5, in Japanese Patent Application Laid-Open No. Hei 8-220541. 100) /DA-7 (100) of polylysine to obtain a comparative liquid crystal alignment treatment agent (A). In this comparison liquid crystal In the treatment agent (A), no abnormality such as the occurrence of contamination or precipitates was observed, and it was confirmed that the solution was a uniform solution.

[Comparative Example 2]

Referring to the WO2004/053583 manual, CA-1 (80), CA-4 (20) / DA-8 (80), DA-7 (20) polylysine, and CA- are mixed at a ratio of 80:20. 3 (100) / DA-1 (100) of polyamic acid to obtain a comparative liquid crystal alignment treatment agent (B). In the comparative liquid crystal alignment treatment agent (B), no abnormality such as generation of dirt or precipitates was observed, and it was confirmed that the solution was a uniform solution.

<Production of liquid crystal cell>

The obtained liquid crystal alignment treatment agent was filtered through a 1.0 μm filter, and spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at 70° C. for 2 minutes, and then sintered at 230° C. for 15 minutes to obtain a film thickness. 100 nm coating film. The polyimine film was rubbed with a crepe cloth (roller diameter: 120 mm, number of revolutions: 1000 rpm, moving speed: 20 mm/sec, and press-in amount: 0.4 mm), and then subjected to ultrasonic irradiation for 1 minute in pure water for 80 minutes. Dry at °C for 10 minutes.

After two substrates having the liquid crystal alignment film were prepared, the rubbing directions of the two substrates were combined in antiparallel, and a sealing agent containing 5 wt% of a spacer of 4 μm was used to leave the liquid crystal injection port. The surrounding area was sealed, and an empty cell having a cell gap of 4 μm was produced. Vacuum injection of liquid crystal ("MLC-2041", manufactured by Merck) into the single sheet at normal temperature The element is sealed to form an anti-parallel liquid crystal cell.

<Black Level Evaluation>

Liquid crystal cells (Examples 1 to 6, Comparative Examples 1 and 2) produced in the same manner as in the above (Production of Liquid Crystal Cell) were placed between two polarizing plates arranged such that the polarization axes were orthogonal to each other. The backlight is turned on in a state where the voltage is not applied, and the arrangement angle of the liquid crystal cell is adjusted to minimize the brightness of the transmitted light. The liquid crystal cell was observed by a digital CCD camera "C8800-21C" manufactured by Hamamatsu Photonics Co., Ltd., and the image of the captured image was quantized using the company's analysis software "ExDcam Image capture Software".

If the brightness value of these liquid crystal cells is 500 to 550, it is "◎", 550 to 600 is "○", and the value is "x" or more.

[Industrial Applicability]

The liquid crystal alignment treatment agent of the invention is driven by a transverse electric field In the liquid crystal display device of the aspect, the problem of causing an uncomfortable feeling in the hue of the screen based on the black element can be solved, and the industry is extremely useful.

The entire contents of the specification, the scope of the patent application, and the summary of the disclosure of the Japanese Patent Application No. 2013-57263, filed on March 19, 2013, are hereby incorporated by reference.

Claims (8)

A liquid crystal alignment treatment agent for a transverse electric field, characterized by comprising a ring closure of a polyamidene precursor having a structural unit represented by the following formula (1) as a structural unit derived from tetracarboxylic dianhydride Polyimine, (In the formula (1), X ¹ is a tetravalent organic group represented by the following formula (X ¹ ), and R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms) A liquid crystal alignment treatment agent for a transverse electric field according to claim 1, wherein the polyfluorene imide precursor has a structural unit represented by the following formula (2) as a structural unit derived from a diamine, (in the formula (2), n is 1 to 12). The requested item 1 or 2 of a transverse electric field driving the liquid crystal alignment treating agent, wherein in the above formula (X ¹⁾ of the tetravalent organic group represented, is selected from the group of isomers of formula [IV] ~ [VI] of a single ingredient or a mixture of these, The liquid crystal alignment treatment agent for driving a transverse electric field according to claim 3, wherein the content of the isomer [IV] is 90% or more. The liquid crystal alignment treatment agent for transverse electric field according to any one of claims 1 to 4, wherein the content of the structural unit represented by the above formula (1) is 1 mol relative to the total structural unit derived from the tetracarboxylic acid derivative. , 30% to 100% by mole. The liquid crystal alignment treatment agent for a transverse electric field according to any one of claims 1 to 5, wherein the content of the structural unit represented by the formula (2) is 20 per mol of the structural unit derived from the diamine. ~100% by mole. A liquid crystal alignment film for driving a transverse electric field, which is obtained by applying a liquid crystal alignment treatment agent according to any one of claims 1 to 6 to a substrate and sintering. A liquid crystal display element for driving a transverse electric field, which has the liquid crystal alignment film of claim 7.