CN107077032B

CN107077032B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element using same

Info

Publication number: CN107077032B
Application number: CN201580057130.1A
Authority: CN
Inventors: 佐藤夏树; 铃木加名子; 坂本谦治; 石川和典; 巴幸司
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2014-10-20
Filing date: 2015-10-19
Publication date: 2021-04-16
Anticipated expiration: 2035-10-19
Also published as: JPWO2016063834A1; WO2016063834A1; CN107077032A; KR102420194B1; TWI699386B; JP6627772B2; TW201629124A; KR20170071513A

Abstract

Provided are a liquid crystal aligning agent, a liquid crystal alignment film and a liquid crystal display element, which have high liquid crystal alignment properties and voltage holding ratios, and which can realize rapid relaxation of residual charges and high contrast. A liquid crystal aligning agent comprising: at least 1 polymer selected from the group consisting of polyamic acid and imidized polymer thereof, the polyamic acid being obtained by polycondensation reaction of tetracarboxylic dianhydride component comprising tetracarboxylic dianhydride of formula (a) and diamine component comprising diamine of formula (B); and a compound represented by the formula (C). (m is an integer of 1 to 5. X¹Is an n-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 20 carbon atoms, n is an integer of 2 to 6, R¹、R²Is a hydrogen atom or an optionally substituted alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, R¹、R²At least one of them has a hydrocarbon group substituted with a hydroxyl group. )

Description

Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element using same

Technical Field

The present invention relates to a liquid crystal aligning agent and a liquid crystal alignment film used for a lateral electric field driving type liquid crystal display element driven by applying a parallel electric field to a substrate, and a liquid crystal display element using the same.

Background

Liquid crystal devices have been widely used as display units of personal computers, mobile phones, television receivers, and the like. The liquid crystal device includes, for example: a liquid crystal layer interposed between the element substrate and the color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling liquid crystal molecular alignment of the liquid crystal layer, a Thin Film Transistor (TFT) for switching an electric signal supplied to the pixel electrode, and the like. As a driving method of liquid crystal molecules, a longitudinal electric field method such as a TN (Twisted Nematic) method and a VA (Vertical Alignment) method; an IPS (In Plane Switching) mode, an FFS (Fringe Field Switching) mode, and other lateral electric Field modes. In general, a lateral electric field system in which electrodes are formed only on one side of a substrate and an electric field is applied in a direction parallel to the substrate has a wider viewing angle characteristic than a conventional longitudinal electric field system in which a voltage is applied to electrodes formed on upper and lower substrates to drive liquid crystals, and is known as a liquid crystal display element capable of realizing high-quality display.

However, in the liquid crystal cell of the transverse electric field system, although the viewing angle characteristics are excellent, since the number of electrode portions formed in the substrate is small, if the voltage holding rate of the liquid crystal alignment film is poor, a sufficient voltage is not applied to the liquid crystal, which indicates that the contrast is decreased. In addition, static electricity is easily accumulated in the liquid crystal cell, and even when an asymmetric voltage generated by driving is applied, electric charges are accumulated in the liquid crystal cell, and the accumulated electric charges cause disturbance of liquid crystal alignment or affect the display in the form of afterimages or afterimages, thereby significantly reducing the display quality of the liquid crystal element. When power is applied again in this state, liquid crystal molecules are not well controlled and flicker (flicker) or the like occurs in an initial stage. In particular, since the pixel electrode and the common electrode are closer to each other in the lateral electric field system than in the vertical electric field system, a strong electric field acts on the alignment film and the liquid crystal layer, which is a problem that such a problem tends to become conspicuous.

Further, in the IPS method, the FFS driving method, and the like, the method of driving liquid crystal molecules aligned horizontally with respect to the substrate by a lateral electric field also becomes important for the stability of liquid crystal alignment. If the alignment stability is low, the liquid crystal does not return to its original state when driven for a long time, and the contrast is lowered, resulting in an afterimage.

As a method for solving the charge accumulation due to the asymmetry of the ac drive, a liquid crystal display device having a liquid crystal alignment film provided with: a 1 st alignment film formed on the electrode; and a 2 nd alignment film formed on the surface thereof and made of a polymer of pyromellitic dianhydride and diamine and having a lower electric resistance than the 1 st alignment film, and it has been reported that the device can suppress charge accumulation due to asymmetry of ac drive and can rapidly relax the accumulated charge (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-167782

Disclosure of Invention

Problems to be solved by the invention

However, with the recent high definition of liquid crystal display elements, the level of the above-described demand has become higher. In addition, in a system such as an IPS system or an FFS drive system in which liquid crystal molecules aligned in parallel with a substrate are driven by a lateral electric field, stability and electrical reliability of liquid crystal alignment under severe environments are also important. Liquid crystal aligning agents that can satisfy all of these requirements at a high level are sought.

The present invention aims to provide a liquid crystal aligning agent which can obtain a liquid crystal alignment film having various characteristics particularly important for liquid crystal display devices of an IPS driving method and an FFS driving method, that is, having high liquid crystal alignment properties and high voltage holding ratio, and further rapidly relaxing residual charges accumulated by a dc voltage, and realizing high contrast.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found a liquid crystal aligning agent which can satisfy the above characteristics at a high level, and have completed the present invention.

Thus, the present invention is a liquid crystal aligning agent comprising: at least 1 polymer selected from the group consisting of polyamic acid and imide polymer of the polyamic acid, wherein the polyamic acid is obtained by the polycondensation reaction of tetracarboxylic dianhydride component containing tetracarboxylic dianhydride represented by the following formula (A) and diamine component containing diamine represented by the following formula (B); and a compound represented by the following formula (C).

(in the formula (B), m is an integer of 1-5.)

(in the formula (C), X¹An n-valent organic group having 1 to 20 carbon atoms and containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group; n is an integer of 2-6; r¹And R²Each independently represents a hydrogen atom, or an optionally substituted alkyl group having 1 to 4 carbon atoms, alkenyl group having 2 to 4 carbon atoms or alkynyl group having 2 to 4 carbon atoms; r¹And R²At least one of them represents a hydrocarbon group substituted with a hydroxyl group. )

ADVANTAGEOUS EFFECTS OF INVENTION

By using the liquid crystal alignment film obtained by the liquid crystal aligning agent of the present invention, a liquid crystal display device having various characteristics which are particularly important for liquid crystal display devices of an IPS driving method and an FFS driving method, that is, having high liquid crystal alignment properties and high voltage holding ratio, and further having high contrast ratio in which residual charges accumulated by a dc voltage are rapidly relaxed can be obtained.

The reason why the above-mentioned results can be obtained by the liquid crystal aligning agent of the present invention is not clear, but is roughly presumed as follows.

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention has a high liquid crystal alignment property because the polymer main chain constituting the liquid crystal alignment film has a flexible structure that can be sufficiently stretched by a brushing treatment and an aromatic functional group that can sufficiently interact with liquid crystal molecules in the main chain. Further, the compound represented by the formula (C) reacts with a carboxyl group in the polymer at the time of firing to improve heat resistance, and the amount of decomposition products generated from the liquid crystal alignment film at the time of firing is suppressed, thereby having a high voltage holding ratio. Further, since a crosslinked structure is formed in the polymer by the reaction between the compound represented by the formula (C) and the carboxyl group of the polymer, the film hardness is improved and the film is less likely to be affected by the rubbing cloth during the rubbing treatment, and therefore, the contrast of the liquid crystal display element using the liquid crystal alignment film can be suppressed from being lowered by the rubbing. Further, it can be considered that: the liquid crystal alignment film of the present invention has a structure in which a pi-electron conjugated system is expanded in the main chain of the polymer, and thus has a low volume resistance value, thereby rapidly relaxing residual charges accumulated by a direct current voltage.

Detailed Description

< Polyamic acid and imidized Polymer of the same >

The liquid crystal aligning agent of the present invention contains: at least 1 polymer selected from the group consisting of polyamic acid and imide polymer of the polyamic acid, wherein the polyamic acid is obtained by the polycondensation reaction of tetracarboxylic dianhydride component containing tetracarboxylic dianhydride represented by the following formula (A) and diamine component containing diamine represented by the following formula (B); and a compound represented by the following formula (C).

In the formula (B), m is an integer of 1 to 5, preferably 1 to 3.

In the formula, X¹Is an n-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 20 carbon atoms, preferably an aliphatic hydrocarbon group having 1 to 5 carbon atoms. n is an integer of 2 to 6, preferably 3 to 4. R¹And R²Each independently represents a hydrogen atom or an optionally substituted hydrocarbon group consisting of an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, preferably an optionally substituted alkyl group having 1 to 4 carbon atoms. And, R¹And R²At least one of them represents a hydrocarbon group substituted with a hydroxyl group, preferably a hydroxyethyl group.

< tetracarboxylic dianhydride component >

The tetracarboxylic dianhydride component used for producing the liquid crystal aligning agent of the present invention contains the tetracarboxylic dianhydride represented by the above formula (a). The proportion of the tetracarboxylic dianhydride represented by the formula (a) is 20 to 80 mol%, preferably 30 to 70 mol%, more preferably 40 to 60 mol%, and still more preferably 40 to 50 mol% based on 1 mol of the total tetracarboxylic dianhydride.

< other tetracarboxylic dianhydrides >

The tetracarboxylic dianhydride component used for producing the liquid crystal aligning agent of the present invention may contain a tetracarboxylic dianhydride represented by the following formula (1) in addition to the tetracarboxylic dianhydride represented by the above formula (a).

In the formula (1), X is a 4-valent organic group, and the structure thereof is not particularly limited. Specific examples of the structure include the following structures represented by the formulae (X-1) to (X-42).

In the formula (X-1), R₃～R₆Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, and more preferably a hydrogen atom or a methyl group.

Among them, at least 1 tetracarboxylic dianhydride selected from the group consisting of structures represented by the following formula (2) is preferable from the viewpoint of compound availability.

(in the formula (2), X₁Is at least 1 selected from the group consisting of the structures represented by the above formulae (X-1) to (X-14). )

Since the reliability of the liquid crystal alignment film obtained can be further improved, a structure composed of only aliphatic groups such as (X-1) to (X-7) and (X-11) is preferable, and the structure shown by (X-1) is more preferable. Further, X is a number of X to exhibit good liquid crystal alignment properties₁Particularly preferred is the following formula (X1-1) or (X1-2).

The proportion of the tetracarboxylic dianhydride represented by the formula (1) is preferably 30 to 70 mol%, more preferably 40 to 60 mol%, and still more preferably 50 to 60 mol% with respect to 1 mol of the total tetracarboxylic dianhydride.

< diamine component >

The diamine component used in the present invention contains a diamine represented by the above formula (B). In the formula (B), m is an integer of 1 to 5, preferably an integer of 1 to 3.

The diamine component preferably contains at least 1 kind of diamine selected from the group consisting of the following structures of formulae (YD-1) to (YD-5) in addition to the diamine of formula (B).

In the formula (YD-1), A₁Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms, Z₁Is a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms.

In the formula (YD-2), W₁Is a C1-10 hydrocarbon group, A₂Is a C3-15 organic group having a nitrogen atom-containing heterocycle, or a disubstituted amino group substituted with a C1-6 aliphatic group.

In the formula (YD-3), W₂A C6-15 and a 2-valent organic group having 1-2 benzene rings, W₃Is alkylene or biphenylene having 2 to 5 carbon atoms, Z₂Is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a benzene ring, and a is an integer of 0 to 1.

In the formula (YD-4), A₃Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms.

In the formula (YD-5), A₄Is a C3-15 nitrogen atom-containing heterocycle, W₅Is an alkylene group having 2 to 5 carbon atoms.

A in the formulae (YD-1), (YD-2), (YD-4) and (YD-5)₁、A₂、A₃And A₄The nitrogen atom-containing heterocycle having 3 to 15 carbon atoms is not particularly limited. Among them, pyrrolidine, pyrrole, imidazole, pyrazole, oxazole, thiazole, piperidine, piperazine, pyridine, pyrazine, indole, benzimidazole, quinoline, isoquinoline and the like are exemplified, and piperazine, piperidine, indole, benzimidazole, imidazole, carbazole or pyridine is more preferable.

Specific examples thereof include 2-valent organic groups having a nitrogen atom represented by the following formulae (YD-6) to (YD-21). Since charge accumulation due to ac driving can be suppressed, the formula (YD-14) to the formula (YD-21) is more preferable, and the formula (YD-14) or (YD-18) is particularly preferable.

In the formulae (YD-14) and (YD-21), j is an integer of 0 to 3, preferably 0 to 1.

In the formula (YD-17), h is an integer of 1 to 3, preferably 2 to 3.

The ratio of at least 1 kind of diamine selected from the group consisting of the structures of the formulae (YD-1) to (YD-5) in the polyamic acid and the imidized polymer of polyamic acid according to the present invention is preferably 10 to 80 mol%, more preferably 20 to 60 mol%, and further preferably 30 to 50 mol% with respect to 1 mol of all the diamines.

< other diamines >

In the polyamic acid contained in the liquid crystal aligning agent of the present invention, a diamine represented by the following formula (3) may be used in addition to the diamine represented by the above formula (B) and at least 1 kind of diamine selected from the group consisting of the above formulae (YD-1) to (YD-5). Y in the following formula (3)₂The organic group is a 2-valent organic group, and the structure thereof is not limited, and 2 or more kinds thereof may be mixed. Specific examples thereof include the following (Y-1) to (Y-102).

Among them, diamines having high linearity are preferable as Y for obtaining good liquid crystal alignment properties₂More preferably Y-7, Y-21 to Y-23,Y-25 to Y-27, Y-43 to Y-46, Y-48, Y-63, Y-71, Y-73 to Y-75, Y-98 to Y-101 or Y-102.

The proportion of the diamine represented by the formula (3) is preferably 0 to 40 mol%, more preferably 0 to 25 mol%, and still more preferably 0 to 15 mol% based on 1 mol of the total diamines.

< Compound represented by formula (C) >

The liquid crystal aligning agent of the present invention contains a compound represented by the following formula (C) (hereinafter, also referred to as a specific compound).

In the above formula (C), X¹An n-valent organic group having 1 to 20 carbon atoms and containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group; n is an integer of 2-6; r¹And R²Each independently represents a hydrogen atom or an optionally substituted hydrocarbon group consisting of an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, R¹And R²At least one of them represents a hydrocarbon group substituted with a hydroxyl group.

Wherein X in the formula (C) is a group represented by the formula¹The atom directly bonded to the carbonyl group in (1) is preferably a carbon atom which does not form an aromatic ring.

In the formula (C), n represents an integer of 2 to 6. From the viewpoint of solubility, n is preferably 2 to 4.

In the formula (C), R¹And R²Each independently represents a hydrogen atom or an optionally substituted hydrocarbon group consisting of an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, R¹And R²At least one of them represents a hydrocarbon group substituted with a hydroxyl group. Wherein, from the viewpoint of reactivity, R¹And R²At least one of them is preferably a structure represented by the following formula (3), and more preferably a structure represented by the following formula (4).

In the formula (3), R³～R⁶Each independently represents any of a hydrogen atom, a hydrocarbon group, or a hydrocarbon group substituted with a hydroxyl group.

Preferable specific examples of the specific compound include the following compound (C-1).

When the content of the specific compound in the liquid crystal aligning agent is too large, the liquid crystal aligning property and the pretilt angle are affected, and when the content is too small, the effect of the present invention cannot be obtained. Therefore, the content of the specific compound is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the polymer of the component (a) in the liquid crystal aligning agent.

< method for producing Polyamic acid >

The polyamic acid as a polyimide precursor used in the present invention can be produced by the following method. Specifically, the tetracarboxylic dianhydride and the diamine are reacted in the presence of an organic solvent at-20 to 150 ℃, preferably 0 to 50 ℃, for 30 minutes to 24 hours, preferably 1 to 12 hours.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ -butyrolactone, or the like, and 1 or 2 or more thereof may be used in combination, from the viewpoint of solubility of the monomer and the polymer.

The concentration of the polymer in the reaction system is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is not likely to occur and a high molecular weight product is easily obtained.

The polyamic acid obtained in the above manner can be recovered by precipitating a polymer by pouring the reaction solution into a poor solvent while sufficiently stirring the reaction solution. Further, the polyamic acid can be obtained as a powder by precipitation several times, washing with a poor solvent, and drying at room temperature or heating. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene and the like, and water, methanol, ethanol, 2-propanol and the like are preferable.

< method for producing polyimide >

The polyimide used in the present invention can be produced by imidizing the polyamic acid.

In the production of a polyimide from a polyamic acid, chemical imidization by adding a catalyst to the polyamic acid solution obtained by the reaction of a diamine component and a tetracarboxylic dianhydride is simple. Chemical imidization is preferred because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not easily reduced during the imidization.

Chemical imidization can be performed by stirring a polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, a solvent used in the polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferable because it has basicity suitable for promoting the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride, and among these, acetic anhydride is preferable because purification after completion of the reaction is easy.

The imidization may be carried out as follows: the temperature for the imidization is-20 to 140 ℃, preferably 0 to 100 ℃, and the reaction time is 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times by mol, preferably 2 to 20 times by mol, and the amount of the acid anhydride is 1 to 50 times by mol, preferably 3 to 30 times by mol, based on the amount of the polyamic acid group. The imidization rate of the obtained polymer can be controlled by adjusting the amount of the catalyst, the temperature and the reaction time.

Since the added catalyst and the like remain in the solution after the imidization of the polyamic acid, it is preferable to recover the obtained imidized polymer by the following means and redissolve it in an organic solvent to obtain the liquid crystal aligning agent of the present invention.

The polyimide solution obtained in the above-described manner can be poured into a poor solvent while sufficiently stirring, thereby precipitating a polymer. The polymer is precipitated several times, washed with a poor solvent, and dried at room temperature or heated to obtain a purified polymer powder.

The poor solvent is not particularly limited, and examples thereof include methanol, 2-propanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene, and methanol, ethanol, 2-propanol, and acetone are preferable.

< liquid Crystal alignment agent >

The liquid crystal aligning agent of the present invention is in the form of a solution in which a polymer component is dissolved in an organic solvent. The molecular weight of the polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000 in terms of weight average molecular weight. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.

The polymer concentration of the liquid crystal aligning agent of the present invention can be appropriately changed according to the thickness of a coating film to be formed, and is preferably 1 mass% or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10 mass% or less from the viewpoint of the storage stability of a solution. The concentration of the polymer is particularly preferably 2 to 8 mass%.

The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it is a solvent that uniformly dissolves the polymer component. Specific examples thereof include N, N-dimethylformamide, N-diethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ -butyrolactone, 1, 3-dimethylimidazolidinone, and 3-methoxy-N, N-dimethylpropionamide. These may be used in 1 kind or in combination of 2 or more kinds. The organic solvent may be mixed with the solvent, which cannot uniformly dissolve the polymer component when it is present alone, as long as the polymer is not precipitated.

The liquid crystal aligning agent of the present invention may contain a solvent for improving the uniformity of a coating film when the liquid crystal aligning agent is applied to a substrate, in addition to an organic solvent for dissolving a polymer component. The solvent is generally a solvent having a lower surface tension than the above-mentioned organic solvent. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol 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, and isoamyl lactate. These solvents may be used in combination of 2 or more.

In the liquid crystal aligning agent of the present invention, in addition to the above-mentioned substances, a polymer other than the polyimide precursor of the present invention and the polymer of polyimide may be added as long as the effect of the present invention is not impaired; a dielectric or conductive material for changing electric characteristics such as a dielectric constant and conductivity of the liquid crystal alignment film; a silane coupling agent for improving the adhesion between the liquid crystal alignment film and the substrate; a crosslinkable compound for improving the hardness and density of the film when the film is produced into a liquid crystal alignment film; and an imidization accelerator for efficiently promoting imidization of polyamic acid when the coating film is fired.

< method for producing liquid Crystal alignment film >

The liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal alignment agent to a substrate, drying the applied liquid crystal alignment agent, and baking the dried liquid crystal alignment agent. The substrate to which the liquid crystal aligning 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 silicon nitride substrate, an acrylic substrate, or a polycarbonate substrate can be used. From the viewpoint of simplifying the process, it is preferable to use a substrate on which an ITO electrode or the like for driving liquid crystal is formed. In the reflective liquid crystal display element, an opaque material such as a silicon wafer may be used as the single-sided substrate, and a material that reflects light such as aluminum may be used as the electrode in this case.

Examples of the method for applying the liquid crystal aligning agent of the present invention include spin coating, printing, and ink jet. The drying and firing steps after the application of the liquid crystal aligning agent of the present invention can be carried out at any temperature and for any time. In general, in order to sufficiently remove the organic solvent contained, it is preferable to dry the mixture at 50 to 120 ℃ for 1 to 10 minutes, and then to bake the mixture at 150 to 300 ℃ for 5 to 120 minutes. The thickness of the coating film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, and therefore, it is 5 to 300nm, preferably 10 to 200 nm.

Examples of the method for aligning the liquid crystal alignment film include brushing and photo-alignment treatment.

When the liquid crystal alignment film is subjected to a brushing treatment, a conventional brushing apparatus can be used. Examples of the material of the brush polishing cloth in this case include cotton, rayon, and nylon.

Specific examples of the photo-alignment treatment method include the following methods: the surface of the coating film is irradiated with radiation polarized in a predetermined direction, and may be further subjected to a heat treatment at a temperature of 150 to 250 ℃ to impart liquid crystal aligning ability. As the radiation, ultraviolet rays and visible rays having a wavelength of 100 to 800nm can be used. Among them, ultraviolet rays having a wavelength of 100 to 400nm are preferable, and ultraviolet rays having a wavelength of 200 to 400nm are particularly preferable. In addition, in order to improve the liquid crystal alignment, the coated substrate may be irradiated with radiation while being heated at 50 to 250 ℃. The irradiation amount of the radiation is preferably 1 to 10,000mJ/cm²Particularly preferably 100 to 5,000mJ/cm². The liquid crystal alignment film produced in the above-described manner can stably align liquid crystal molecules in a certain direction.

The film irradiated with the polarized radiation as described above is then subjected to a contact treatment with at least 1 solvent including one selected from the group consisting of water and organic solvents.

The solvent used in the contact treatment is not particularly limited as long as it dissolves a decomposition product generated by light irradiation. Specific examples thereof include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. These solvents may be used in combination of 2 or more.

The solvent is more preferably at least 1 selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate from the viewpoints of general-purpose properties and safety. Particularly preferred is 1-methoxy-2-propanol or ethyl lactate.

In the present invention, the contact treatment of the film irradiated with the polarized radiation and the solution containing the organic solvent is preferably performed by a treatment such as a dipping treatment or a spraying (spraying) treatment, in which the film is sufficiently contacted with the solution. Among these, a method of immersing the film in a solution containing an organic solvent is preferable, and the immersion treatment is preferably performed for 10 seconds to 1 hour, and more preferably for 1 to 30 minutes. The contact treatment may be carried out at normal temperature or by heating, and is preferably carried out at 10 to 80 ℃ and more preferably at 20 to 50 ℃. Further, means for improving the contact such as ultrasonic waves may be applied as necessary.

After the contact treatment, either or both of rinsing (washing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, and methyl ethyl ketone and drying may be performed in order to remove the organic solvent in the solution used.

Further, the film treated by the contact with the solvent may be heated at 150 ℃ or higher in order to dry the solvent and reorient the molecular chains in the film.

The heating temperature is preferably 150 to 300 ℃. The higher the temperature, the more the reorientation of the molecular chain is promoted, but if the temperature is too high, the molecular chain may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 ℃, and particularly preferably 200 to 230 ℃.

If the heating time is too short, the effect of the present invention may not be obtained, and if the heating time is too long, the molecular chain may be decomposed, and therefore, it is preferably 10 seconds to 30 minutes, more preferably 1 minute to 10 minutes.

The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a liquid crystal display element of a transverse electric field system such as an IPS drive system or an FFS drive system, and is particularly useful as a liquid crystal alignment film for a liquid crystal display element of an FFS drive system.

< liquid Crystal display element >

The liquid crystal display element of the present invention is obtained as follows: after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, a liquid crystal cell was produced by a known method, and a liquid crystal display element was obtained using the liquid crystal cell.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described. In addition, a liquid crystal display element of an active matrix structure in which a conversion element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting an image display may be used.

First, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode (segment electrode) is provided on the other substrate. These electrodes may be made, for example, as ITO electrodes, patterned so as to enable a desired image representation. Next, an insulating film is provided on each substrate to cover the common electrode and the segment electrode. The insulating film can be made to contain SiO formed by a sol-gel method, for example₂-TiO₂The film of (1).

Next, the liquid crystal alignment film of the present invention is formed on each substrate.

Next, one substrate is laminated on the other substrate with the alignment films facing each other, and the periphery is bonded with a sealing material. In order to control the substrate gap, a spacer is usually mixed in the sealing material in advance. In addition, it is preferable that spacers for controlling the substrate gap are also dispersed in advance in the in-plane portion where the sealing material is not provided. The sealing material is partially provided with an opening capable of being filled with liquid crystal from the outside.

Next, a liquid crystal material is injected into a space surrounded by the two substrates and the sealing material through an opening provided in the sealing material. Thereafter, the opening is sealed with an adhesive. The injection may be performed by a vacuum injection method or a method using a capillary phenomenon in the atmosphere. As the liquid crystal material, any of a positive type liquid crystal material and a negative type liquid crystal material can be used. Subsequently, a polarizing plate was disposed. Specifically, a pair of polarizing plates is attached to surfaces of the two substrates on the side opposite to the liquid crystal layer. Through the above steps, the liquid crystal display element of the present invention can be obtained. Since the liquid crystal alignment film obtained by the present invention can be used as a liquid crystal alignment film for the liquid crystal display element, the liquid crystal display element has excellent afterimage characteristics and can be suitably used for a large-screen, high-definition liquid crystal television or the like.

Examples

The present invention will be specifically described below by way of examples. The present invention is not limited to these examples. The abbreviations used hereinafter are as follows.

NMP: n-methyl-2-pyrrolidone

GBL: gamma-butyrolactone

BCS: butyl cellosolve

Acid dianhydride (a): a tetracarboxylic dianhydride represented by the following formula (A).

Acid dianhydride (B): a tetracarboxylic dianhydride represented by the following formula (B).

Acid dianhydride (C): a tetracarboxylic dianhydride represented by the following formula (C).

DA-1: a diamine of the formula (DA-1)

DA-2: a diamine of the formula (DA-2)

Specific compound a: the following compounds (Primid XL552, エムスケミー Co., Ltd.)

The measurement methods of the various characteristics are shown below.

[ viscosity ]

The measurement was carried out at a temperature of 25 ℃ with a sample volume of 1.1mL and a conical rotor TE-1(1 ℃ C., 34' C., R24) using an E-type viscometer TVE-22H (manufactured by Toyobo industries, Ltd.).

[ molecular weight ]

The number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated in terms of polyethylene glycol and polyethylene oxide by GPC (normal temperature gel permeation chromatography) measurement.

GPC apparatus: shodex Ltd (GPC-101)

Column: shodex products (series KD803 and KD 805)

Column temperature: 50 deg.C

Eluent: n, N-dimethylformamide (as additive, lithium bromide monohydrate (LiBr. H)₂O) 30mmol/L (liter), phosphoric acid anhydrous crystal (orthophosphoric acid) 30mmol/L, Tetrahydrofuran (THF) 10ml/L)

Flow rate: 1.0 ml/min

Standard sample for standard curve preparation: TSK standard polyethylene oxide (weight average molecular weight (Mw) of about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh corporation and polyethylene glycol (peak molecular weight (Mp) of about 12,000, 4,000, 1,000) manufactured by Polymer Laboratories Ltd. In order to avoid overlapping of peaks, the measurement was performed for two types of samples of 4 kinds of samples of 900,000, 100,000, 12,000 and 1,000 mixed and samples of 3 kinds of samples of 150,000, 30,000 and 4,000 mixed, respectively.

[ production of liquid Crystal cell ]

A liquid crystal cell having a structure including an FFS mode liquid crystal display element was produced.

On the prepared glass substrate with electrodes (30 mm in length × 50mm in width × 0.7mm in thickness), as the 1 st layer, an ITO electrode having a solid pattern for constituting a counter electrode was formed. On the counter electrode of the 1 st layer, as a 2 nd layer, an SiN (silicon nitride) film formed by a CVD (chemical vapor deposition) method is formed. The SiN film of the 2 nd layer has a film thickness of 500nm and functions as an interlayer insulating film. On the SiN film of the 2 nd layer, a comb-shaped pixel electrode formed by patterning an ITO film is disposed as a 3 rd layer, and two pixels, i.e., a 1 st pixel and a 2 nd pixel, are formed. The size of each pixel is: 10mm long and about 5mm wide. At this time, the counter electrode of the 1 st layer and the pixel electrode of the 3 rd layer are electrically insulated by the SiN film of the 2 nd layer.

The pixel electrode of the layer 3 has a comb-like shape in which a plurality of "く" -shaped electrode elements having a bent central portion are arranged. The width of each electrode element in the width direction was 3 μm, and the interval between the electrode elements was 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of "く" -shaped electrode elements each having a bent central portion, each pixel has a shape similar to a bold "く" word, in which the central portion is bent in the same manner as the electrode elements, instead of a rectangular shape. Each pixel is divided vertically with a curved portion at the center thereof as a boundary, and has a 1 st region on the upper side and a 2 nd region on the lower side of the curved portion.

When comparing the 1 st region and the 2 nd region of each pixel, the forming directions of the electrode elements constituting the pixel electrodes are different. That is, when the brushing direction of the liquid crystal alignment film described later is set as a reference, the electrode elements of the pixel electrode are formed so as to make an angle of +10 ° (clockwise) in the 1 st region of the pixel, and the electrode elements of the pixel electrode are formed so as to make an angle of-10 ° (clockwise) in the 2 nd region of the pixel. That is, the 1 st region and the 2 nd region of each pixel are configured as follows: the directions of the rotation (planar switching) of the liquid crystal in the substrate plane induced by applying a voltage between the pixel electrode and the counter electrode are opposite to each other.

Next, the obtained liquid crystal aligning agent was filtered with a 1.0 μm filter, and then applied by spin coating to the prepared electrode-attached substrate and a glass substrate having an ITO film formed on the back surface thereof and a columnar spacer having a height of 4 μm. After drying on a hot plate at 80 ℃ for 5 minutes, the resultant was baked in a hot air circulating oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100 nm. The coated surface is subjected to alignment treatment such as brushing and polarized ultraviolet irradiation to obtain a substrate with a liquid crystal alignment film. The two substrates were used as a set, the sealant was printed on the substrates, and another 1 substrate was attached so that the liquid crystal alignment films face each other and the alignment direction was 0 °, and then the sealant was cured to prepare an empty cell. Liquid crystal MLC-2041 (manufactured by MERCK CORPORATION) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Thereafter, the resulting liquid crystal cell was heated at 110 ℃ for 1 hour, and placed late for each evaluation.

[ evaluation of liquid Crystal alignment Properties ]

The liquid crystal cell obtained by the above-described production method was subjected to an alternating voltage having a frequency of 30Hz and a relative transmittance of 100% for 168 hours in a constant temperature environment of 60 ℃. Thereafter, a short circuit state was caused to occur between the pixel electrode and the counter electrode of the liquid crystal cell, and the liquid crystal cell was left to stand at room temperature for one day. After the placement, the liquid crystal cell was placed between 2 polarizing plates arranged so that the polarization axes were perpendicular, the backlight was turned on in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of transmitted light became minimum. Then, the angle Δ is calculated as the rotation angle when the liquid crystal cell is rotated from the angle at which the 2 nd area of the 1 st pixel reaches the darkest to the angle at which the 1 st area reaches the darkest. Similarly, for the 2 nd pixel, the 2 nd area is compared with the 1 st area, and the same angle Δ is calculated. Then, the average value of the angle Δ values of the 1 st pixel and the 2 nd pixel is calculated as the angle Δ of the liquid crystal cell, and the liquid crystal alignment property is evaluated based on the magnitude of the value. That is, when the value of the angle Δ is small, the liquid crystal alignment property is good.

[ evaluation of Voltage Holding Ratio (VHR) (backlight aging resistance (Voltage holding ratio 1) ]

An ITO electrode having a film thickness of 35nm was formed on the prepared electrode-equipped glass substrate (30 mm in length × 50mm in width × 0.7mm in thickness), and the electrode was in a stripe pattern of 40mm in length and 10mm in width. Next, the liquid crystal aligning agent was filtered through a 1.0 μm filter and applied to the prepared electrode-attached substrate by spin coating. After drying on a hot plate at 50 ℃ for 5 minutes, the resultant was baked in an IR oven at 230 ℃ for 20 minutes to form a coating film having a thickness of 100nm, thereby obtaining a substrate with a liquid crystal alignment film. The liquid crystal alignment film was brushed with rayon cloth (roll diameter: 120mm, roll rotation speed: 1000rpm, moving speed: 20 mm/sec, pressing length: 0.4mm), then washed by ultrasonic irradiation in pure water for 1 minute, and water droplets were removed by air blowing, and then dried at 80 ℃ for 15 minutes to obtain a substrate with a liquid crystal alignment film.

2 pieces of the above-mentioned substrates with liquid crystal alignment films were prepared, and after spreading spacers of 4 μm on the surface of 1 of the liquid crystal alignment films, a sealant was printed thereon, and another 1 piece of the substrate was attached so that the brushing direction was opposite and the film surfaces were opposite to each other. Thereafter, the sealant is cured to produce an empty cell. Liquid crystal MLC-2041 (manufactured by MERCK CORPORATION) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. Thereafter, the resulting liquid crystal cell was heated at 110 ℃ for 1 hour and placed at 23 ℃ for one hour, thereby obtaining a VHR measuring cell. The unit was then aged in an oven at 70 ℃ for 72 hours under an LED light source (1000 cd).

After backlight aging for 72 hours, a voltage of 1V was applied to the cell at a temperature of 60 ℃ for 60 microseconds, the voltage after 100 milliseconds was measured, and the VHR was evaluated for the resistance to backlight aging by the magnitude of the voltage. That is, the larger the value of VHR, the better the VHR backlight aging resistance.

[ evaluation of Black level ]

A liquid crystal cell fabricated in the same manner as described above (fabrication of liquid crystal cell) was placed between 2 polarizing plates arranged so that the polarization axis was perpendicular to each other, and the backlight was turned on in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of transmitted light became minimum. The liquid crystal cell was observed using a digital CCD camera "C8800 to 21C" manufactured by Kohamamatsu ホトニクス, and the photographed Image was digitized into brightness using analysis Software "ExDcam Image capture Software" of the company. If the brightness value of the liquid crystal cell is 500 to 600, it is referred to as "good", and if the brightness value is 500 to 600 or more, it is referred to as "bad".

[ relaxation characteristics of accumulated Charge ]

A liquid crystal cell fabricated in the same manner as described above (fabrication of liquid crystal cell) was placed between 2 polarizing plates arranged so that the polarization axis was perpendicular to each other, and in a state where the pixel electrode and the counter electrode were short-circuited and made the same potential, the LED backlight was irradiated from below the 2 polarizing plates, and the angle of the liquid crystal cell was adjusted so that the luminance of the LED backlight transmitted light measured above the 2 polarizing plates was minimized.

Then, while applying a rectangular wave having a frequency of 30Hz to the liquid crystal cell, the V-T characteristics (voltage-transmittance characteristics) at a temperature of 23 ℃ were measured, and an AC voltage at which the relative transmittance reached 23% was calculated. Then, after applying an alternating voltage having a relative transmittance of 23% and a rectangular wave having a frequency of 30Hz for 5 minutes, a direct voltage of +1.0V was superimposed thereon and driven for 30 minutes. Thereafter, the DC voltage was cut off, and only a rectangular wave having a frequency of 30Hz and an AC voltage of 23% relative transmittance was applied again for 20 minutes.

Since the faster the relaxation of the accumulated charge, the faster the charge accumulation in the liquid crystal cell when the dc voltage is superimposed, the relaxation characteristic of the accumulated charge is defined and evaluated as "good" when the relative transmittance decreases to less than 28% after 30 minutes has elapsed from the state where the relative transmittance immediately after the dc voltage is superimposed is 30% or more. Even when 30 minutes elapsed since the dc voltage was superimposed, the relative transmittance was not decreased to less than 28%, and the case was defined and evaluated as "poor".

(Synthesis example 1)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-179.4 g (0.33mol) and DA-264.8 g (0.33mol) were measured, and then 911g of NMP and 911g of GBL were added thereto, and the mixture was dissolved with stirring while feeding nitrogen gas. While stirring the diamine solution, 65.0g (0.33mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 86.1g (0.29mol) of acid dianhydride (A) was added, and further 390g of NMP and 390g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-1). The polyamic acid solution had a viscosity of 215 mPas at 25 ℃. The polyamic acid had Mn of 15,773 and Mw of 31,242.

(Synthesis example 2)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-195.3 g (0.39mol) and DA-251.8 g (0.26mol) were measured, NMP 939g and GBL 939g were added thereto, and the mixture was dissolved by stirring while feeding nitrogen gas. While stirring the diamine solution, 65.0g (0.33mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 86.1g (0.29mol) of acid dianhydride (A) was added, and further 402g of NMP and 402g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-2). The polyamic acid solution had a viscosity of 221 mPas at a temperature of 25 ℃. The polyamic acid had Mn of 14,773 and Mw of 32,212.

(Synthesis example 3)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-179.4 g (0.33mol) and DA-264.8 g (0.33mol) were measured, NMP 859g and GBL 859g were added thereto, and the mixture was dissolved by stirring while feeding nitrogen gas. While stirring the diamine solution, 65.0g (0.33mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 63.8g (0.29mol) of acid dianhydride (B) was added, and further, 369g of NMP and 369g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-3). The polyamic acid solution had a viscosity of 207 mPas at a temperature of 25 ℃. The polyamic acid had Mn of 13,853 and Mw of 28,251.

(Synthesis example 4)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-179.4 g (0.33mol) and DA-264.8 g (0.33mol) were measured, and then NMP 839g and GBL 839g were added thereto, and dissolved by stirring while feeding nitrogen gas. While stirring the diamine solution, 122.3g (0.62mol) of acid dianhydride (C) was added, 360g of NMP and 360g of GBL were further added, and the mixture was stirred at 40 ℃ for 30 hours under a nitrogen atmosphere to obtain a polyamic acid solution (PAA-4). The polyamic acid solution had a viscosity of 212 mPas at a temperature of 25 ℃. The polyamic acid had Mn of 14,255 and Mw of 28,373.

(Synthesis example 5)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-2129.5 g (0.65mol) was measured, NMP 884g and GBL 884g were added thereto, and the mixture was dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 65.0g (0.33mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 86.1g (0.29mol) of acid dianhydride (A) was added, and further 379g of NMP and 379g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-5). The polyamic acid solution had a viscosity of 225 mPas at a temperature of 25 ℃. The polyamic acid had Mn of 12,799 and Mw of 33,192.

(Synthesis example 6)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-191.6 g (0.38mol) and DA-274.7 g (0.38mol) were measured, NMP 661g and GBL 661g were added, and the mixture was dissolved with stirring while feeding nitrogen. While stirring the diamine solution, 67.7g (0.35mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 99.3g (0.34mol) of acid dianhydride (A) was added, and further 283g of NMP and 283g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-6). The polyamic acid solution had a viscosity of 583 mPas at 25 ℃. The polyamic acid had Mn of 11,141 and Mw of 21,889.

(Synthesis example 7)

A3L four-necked flask equipped with a stirrer was placed in a nitrogen atmosphere, DA-173.3 g (0.30mol) and DA-259.8 g (0.30mol) were measured, NMP 674g and GBL 674g were added, and the mixture was dissolved with stirring while feeding nitrogen. While stirring the diamine solution, 50.0g (0.26mol) of acid dianhydride (C) was added, and after stirring at room temperature for 2 hours, 79.4g (0.27mol) of acid dianhydride (A) was added, and further 288g of NMP and 288g of GBL were added, and stirring was carried out at 40 ℃ for 30 hours under a nitrogen atmosphere, thereby obtaining a polyamic acid solution (PAA-7). The polyamic acid solution had a viscosity of 117 mPas at a temperature of 25 ℃. The polyamic acid had Mn of 8,953 and Mw of 19,521.

(example 1)

Into A5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-1) obtained in Synthesis example 1, and added were NMP 578g, 1.8g of 3-glycidoxypropyltriethoxysilane, 5.4g of the specific Compound A, GBL 122g and BCS 642g, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal alignment agent (A-1).

(example 2)

Into a 5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-2) obtained in Synthesis example 2, and added were NMP 578g, 3-glycidoxypropyltriethoxysilane 1.8g, specific Compound A5.4g, GBL 122g and BCS 642g, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal alignment agent (A-2).

(example 3)

Into a 3L Erlenmeyer flask equipped with a stirrer were charged 371g of the polyamic acid solution (PAA-6) obtained in Synthesis example 6, and 84.6g of NMP, 0.53g of 3-glycidoxypropyltriethoxysilane, 1.6g of the specific compound A, 201g of GBL and 165g of BCS were added, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-3).

(example 4)

213g of the polyamic acid solution (PAA-7) obtained in Synthesis example 7 was put into a 2L Erlenmeyer flask equipped with a stirrer, and 101g of NMP, 0.25g of 3-glycidoxypropyltriethoxysilane, 0.74g of the specific Compound A, 146g of GBL and 109g of BCS were added thereto, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal alignment agent (A-4).

Comparative example 1

Into A5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-3) obtained in Synthesis example 3, and added were NMP 578g, 1.8g of 3-glycidoxypropyltriethoxysilane, 5.4g of the specific Compound A, GBL 122g and BCS 642g, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1).

Comparative example 2

Into A5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-4) obtained in Synthesis example 4, and added were NMP 578g, 3-glycidoxypropyltriethoxysilane 1.8g, specific Compound A5.4g, GBL 122g and BCS 642g, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal alignment agent (B-2).

Comparative example 3

Into A5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-5) obtained in Synthesis example 5, and added were NMP 578g, 1.8g of 3-glycidoxypropyltriethoxysilane, 5.4g of the specific Compound A, GBL 122g and BCS 642g, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal alignment agent (B-3).

Comparative example 4

Into a 5L Erlenmeyer flask equipped with a stirrer were charged 1861g of the polyamic acid solution (PAA-1) obtained in Synthesis example 1, and further added 583g of NMP, 1.8g of 3-glycidoxypropyltriethoxysilane, 122g of GBL, and 642g of BCS, followed by stirring with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-4).

[ Table 1]

Industrial applicability

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention is particularly useful as a liquid crystal display element of IPS drive system or FFS drive system, or a liquid crystal alignment film of liquid crystal television.

The entire contents of the specification, claims and abstract of japanese patent application 2014-213835 filed on 10/20/2014 and japanese patent application 2015-032093 filed on 2/20/2015 are incorporated herein by reference as disclosures of the present specification.

Claims

1. A liquid crystal aligning agent, comprising:

at least 1 polymer selected from the group consisting of polyamic acid and imide polymer of the polyamic acid, wherein the polyamic acid is obtained by the polycondensation reaction of tetracarboxylic dianhydride component containing tetracarboxylic dianhydride represented by the following formula (A) and diamine component containing diamine represented by the following formula (B); and

a compound represented by the following formula (C),

in the formula (B), m is an integer of 1 to 5,

in the formula (C), X¹An n-valent organic group having 1 to 20 carbon atoms and containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group; n is an integer of 2-6; r¹And R²Each independently represents a hydrogen atom or an optionally substituted hydrocarbon group consisting of an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms or an alkynyl group having 2 to 4 carbon atoms, R¹And R²At least one of which is a hydrocarbon group substituted with a hydroxyl group.

2. The liquid crystal aligning agent according to claim 1, wherein 20 to 80 mol% of the tetracarboxylic dianhydride component is a tetracarboxylic dianhydride represented by formula (A).

3. The liquid crystal aligning agent according to claim 1 or 2, wherein 20 to 80 mol% of the diamine component is a diamine of the formula (B).

4. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine component contains at least 1 kind of diamine selected from the group consisting of structures represented by the following formulas (YD-1) to (YD-5),

in the formula (YD-1), A₁Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms, Z₁A hydrogen atom or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms; in the formula (YD-2), W₁Is a C1-10 hydrocarbon group, A₂Is a C3-15 organic group having a nitrogen atom-containing heterocycle, or a disubstituted amino group substituted with a C1-6 aliphatic group; in the formula (YD-3), W₂A C6-15 and a 2-valent organic group having 1-2 benzene rings, W₃Is alkylene or biphenylene having 2 to 5 carbon atoms, Z₂Is a hydrogen atomAn alkyl group having 1 to 5 carbon atoms or a benzene ring, a is an integer of 0 to 1; in the formula (YD-4), A₃Is a nitrogen atom-containing heterocycle having 3 to 15 carbon atoms; in the formula (YD-5), A₄Is a C3-15 nitrogen atom-containing heterocycle, W₅Is an alkylene group having 2 to 5 carbon atoms.

5. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine component contains at least 1 kind selected from the group consisting of 2-valent organic groups having structures of the following formulae (YD-6) to (YD-21),

in the formula (YD-17), h is an integer of 1-3; in the formulae (YD-14) and (YD-21), j is an integer of 1 to 3.

6. The liquid crystal aligning agent according to claim 1 or 2, wherein the compound represented by the formula (C) is contained in an amount of 0.1 to 20 mass% based on the polymer of the component (A).

7. The liquid crystal aligning agent according to claim 1 or 2, wherein the compound represented by the formula (C) is a compound represented by the following formula (C-1),

8. a liquid crystal alignment film obtained by applying the liquid crystal aligning agent according to any one of claims 1 to 7 and firing the applied liquid crystal aligning agent.

9. A liquid crystal display element comprising the liquid crystal alignment film according to claim 8.

10. The liquid crystal display element according to claim 9, which is an IPS drive system or an FFS drive system.