KR102172129B1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using same - Google Patents

Abstract

(식 (2) 중, A₁ 은 탄소수 1 ∼ 10 의 직사슬 알킬렌기를 함유하는 2 가의 유기기이고, R₁ 및 R₂ 는, 각각 독립적으로 수소 원자, 또는 탄소수 1 ∼ 4 의 알킬기이고, 식 (3) 중, A₂ 는 단결합, -O-, -S-, -NR₆-, 에스테르 결합, 아미드 결합, 티오에스테르 결합, 우레아 결합, 카보네이트 결합, 또는 카르바메이트 결합이고, R₆ 은 수소 원자, 메틸기, 또는 t-부톡시카르보닐기이고, R₃ 은 탄소수 1 ∼ 10 의 직사슬 알킬렌기이고, R₄ 및 R₅ 는, 각각 독립적으로 수소 원자, 또는 탄소수 1 ∼ 4 의 알킬기이다.)A liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element using the same, which can suppress the accumulation of charges due to asymmetry of the positive and negative voltages during AC drive, and quickly alleviate the accumulated charge, and have excellent liquid crystal alignment properties and excellent alignment stability. to provide.
Contains at least one diamine selected from the group consisting of a tetracarboxylic dianhydride component containing pyromellitic dianhydride, a diamine of the following formula (1), and a diamine represented by the following formulas (2) and (3). A liquid crystal aligning agent containing at least one type of polymer selected from the group consisting of a polyamic acid obtained by reacting the diamine component described above and an imidized polymer of the polyamic acid.

(In formula (2), A ₁ is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, and R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, In formula (3), A ₂ is a single bond, -O-, -S-, -NR ₆ -, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond, and R ₆ Is a hydrogen atom, a methyl group, or a t-butoxycarbonyl group, R ₃ is a linear alkylene group having 1 to 10 carbon atoms, and R ₄ and R ₅ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. )

Description

A liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element using the same TECHNICAL FIELD [LIQUID CRYSTAL ALIGNMENT AGENT, LIQUID CRYSTAL ALIGNMENT FILM, AND LIQUID CRYSTAL DISPLAY ELEMENT USING SAME}

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element using the liquid crystal aligning agent used in a liquid crystal display element driven by applying a parallel electric field to a substrate.

BACKGROUND ART Liquid crystal display elements have conventionally been widely used as display units for personal computers, mobile phones, and television receivers. The liquid crystal display element is supplied to, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that applies an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, and a pixel electrode. A thin film transistor (TFT) or the like for switching an electrical signal to be used is provided.

As a driving method of the liquid crystal molecules, a vertical electric field method such as a TN (Twisted Nematic) method and a VA (Virtical Alignment) method, an IPS (In-Place-Switching) method, or a fringe field switching method. Hereinafter, a transverse electric field method such as an FFS method is known. In general, in the lateral electric field method in which electrodes are formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate, compared to the vertical electric field method in which a voltage is applied to electrodes formed on the upper and lower substrates to drive the liquid crystal, the viewing angle is wider. It is known as a liquid crystal display device having characteristics and capable of displaying high quality.

However, although the transverse electric field type liquid crystal display device has excellent viewing angle characteristics, since there are few electrode portions formed in the substrate, if the voltage retention of the liquid crystal alignment film is weak, a sufficient voltage is not applied to the liquid crystal and the display contrast is lowered. In addition, due to the asymmetry of the DC voltage component applied from the active matrix structure, which is a conventional problem, and the positive and negative voltages during AC driving, which has attracted attention relatively recently, charges are accumulated in the liquid crystal display device, and these accumulated charges are converted into liquid crystals. It affects the display as a disturbance in the orientation of, and furthermore, an afterimage or burn-in, and significantly lowers the display quality of the liquid crystal display element. Alternatively, when driving is performed in a state in which electric charges are accumulated, control of liquid crystal molecules is not normally performed immediately after driving, causing flicker (flicker) or the like. In particular, in the horizontal electric field method, since the distance between the pixel electrode and the common electrode is closer than that of the vertical electric field method, there is a problem that a strong electric field acts on the alignment film or the liquid crystal layer, and these problems are liable to become remarkable.

In addition, stability of liquid crystal alignment also becomes important in a system in which liquid crystal molecules aligned parallel to the substrate, such as an IPS system or an FFS driving system, are driven by a horizontal electric field. If the stability of alignment is insufficient, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, resulting in a decrease in contrast, an afterimage, or burn-in.

Along with the high performance of the liquid crystal display element, the demand for the characteristics required for the liquid crystal alignment film is also becoming strict. That is, excellent liquid crystal alignment and excellent alignment stability, high voltage retention and stability of the voltage retention rate for long-time driving, little accumulated charge when DC voltage is applied, suppression of charge accumulation due to asymmetry of positive and negative voltages during AC drive, Characteristics such as rapid relaxation of accumulated charges are becoming important.

In the polyimide liquid crystal aligning film, various proposals have been made in order to respond to the above demand. For example, as a liquid crystal alignment film with a short time until afterimages generated by the application of a DC voltage disappear, in addition to polyamic acid or polyamic acid containing an imide group, liquid crystal alignment containing a tertiary amine of a specific structure Using an agent (for example, see Patent Document 1) or using a liquid crystal aligning agent containing a soluble polyimide using a specific diamine compound having a pyridine skeleton or the like as a raw material (for example, see Patent Document 2) Etc. are proposed.

In addition, as a liquid crystal aligning agent for a transverse electric field driving system that is excellent in printability and rubbing resistance, and has little afterimage or burn-in, Patent Document 3 discloses an amic acid unit derived from an aromatic tetracarboxylic acid and an alicyclic tetracar. A liquid crystal aligning agent containing both of an amic acid unit derived from an acid by copolymerization or mixing is disclosed.

In addition, as a liquid crystal aligning agent for obtaining a liquid crystal aligning film in which the liquid crystal alignment property, alignment regulating force, and rubbing resistance are excellent, the voltage retention is high, and the charge accumulation when a DC voltage is applied is reduced, Patent Document 4 is used as a film. A liquid crystal aligning agent comprising a low-resistance polyimide precursor having a volume resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ωcm and a polyimide precursor or polyimide having a specific structure and A liquid crystal display device using a liquid crystal aligning agent is disclosed.

In addition, as a liquid crystal aligning agent that has a high voltage retention rate and maintains a high voltage retention rate even after exposure to high temperatures for a long period of time, and has a low residual charge when a DC voltage is applied, Patent Document 5 discloses a tertiary amine having a specific molecular structure. A liquid crystal aligning agent characterized by containing a copolymer obtained by reacting a diamine containing and a carboxyl group-containing diamine and an acid dianhydride, and a liquid crystal display device using this liquid crystal aligning agent are disclosed.

In addition, in a liquid crystal display device having a first alignment film formed on the electrode, a polymer composed of pyromellitic dianhydride and diamine formed on the surface thereof, and a liquid crystal alignment film comprising a second alignment film having a lower resistance than the first alignment film, AC It has been reported that the accumulation of charges due to asymmetry of the positive and negative voltages during driving can be suppressed and a rapid relaxation of the accumulated charges can be achieved (see Patent Document 6).

However, in one type of alignment film, there is still no report on an alignment film that achieves both suppression of charge accumulation due to asymmetry of positive and negative voltages during AC driving and rapid relaxation of accumulated charges.

Japanese Laid-Open Patent Publication No. Hei 9-316200 Japanese Laid-Open Patent Publication No. Hei 10-104633 International Publication No. WO02/33481 pamphlet International Publication No. WO2004/53583 pamphlet International Publication No. WO2009/93709 pamphlet Japanese Unexamined Patent Publication No. 2013-167782

The inventors of the present invention have confirmed that it is difficult to achieve both suppression of charge accumulation due to asymmetry of positive and negative voltages during AC drive and rapid relaxation of accumulated charge in one type of liquid crystal alignment film.

The present invention can suppress the accumulation of charges due to asymmetry of the positive and negative voltages during AC driving, which is a problem in the lateral electric field driving method, and can quickly alleviate the accumulated charges, and furthermore, an excellent liquid crystal It aims at providing a liquid crystal aligning agent from which a liquid crystal aligning film which has orientation property and excellent orientation stability is obtained.

The inventors of the present invention have completed the present invention as a result of intensive examination in order to solve the above problems. That is, the gist of the present invention is as shown below.

1.At least one diamine selected from the group consisting of a tetracarboxylic dianhydride component containing pyromellitic dianhydride, a diamine of the following formula (1), and a diamine represented by the following formulas (2) and (3). A liquid crystal aligning agent containing at least one type of polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine component containing and an imidized polymer of the polyamic acid.

[Formula 1]

(In formula (2), A ₁ is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and the formula In (3), A ₂ is a single bond, -O-, -S-, -NR ₆ -, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond, and R ₆ is hydrogen An atom, a methyl group, or a t-butoxycarbonyl group, R ₃ is a C 1 to C 10 linear alkylene group, and R ₄ and R ₅ are each independently a hydrogen atom or a C 1 to C 4 alkyl group.)

2. The liquid crystal aligning agent according to the above 1, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component is pyromellitic dianhydride.

3. The liquid crystal aligning agent according to the above 1 or 2, wherein 10 to 90 mol% of the diamine component is a diamine of the formula (1).

4. The liquid crystal aligning agent in any one of said 1-3 in which 10-90 mol% of the said diamine component is at least 1 diamine selected from the group consisting of diamines represented by said formula (2) and (3).

5. Liquid crystal aligning agent containing the following polymers (A) and (B).

Polymer (A): selected from polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride and a diamine component containing diamine of formula (1), and an imidized polymer of the polyamic acid At least one kind of polymer.

Polymer (B): Polyamic acid obtained by reacting a tetracarboxylic dianhydride component and a diamine component containing at least one diamine selected from the diamines of formulas (2) and (3), and imidization of the polyamic acid At least one type of polymer selected from polymers.

6. In the said polymer (A), 20-100 mol% of a tetracarboxylic dianhydride component is pyromellitic dianhydride, the liquid crystal aligning agent as described in said 5 above.

7. In the polymer (A), the liquid crystal aligning agent according to 5 or 6, wherein 20 to 100 mol% of the diamine component is a diamine of the formula (1).

8. In the polymer (B), 20 to 100 mol% of the diamine component is at least one diamine selected from the group consisting of diamines represented by the formulas (2) and (3). Any of the above 5 to 7 The liquid crystal aligning agent according to one.

9. The diamine of the formula (2) is at least one species selected from the group consisting of diamines represented by the following formulas (4) to (9), and the diamine of the formula (3) is represented by the following formula (10). The liquid crystal aligning agent in any one of said 1-8 which is at least 1 type selected from the group consisting of diamine.

[Formula 2]

(In formula (4), R ₇ and R ₈ are each independently a linear alkylene group having 1 to 10 carbon atoms, and may be the same or different. In formula (10), R ₉ is a hydrogen atom, or an alkyl group having a carbon number of 1 to 4, R ₁₀ is a straight-chain alkylene group having 1 to 10 carbon atoms.)

10. The diamine of the formula (2) is at least one species selected from the group consisting of diamines represented by the formula (6) and the following formulas (11) to (14), and the diamine of the formula (3), The liquid crystal aligning agent in any one of said 1-9 which is at least 1 type selected from the group which consists of diamines represented by following formula (15) and (16).

[Formula 3]

11. A liquid crystal aligning film obtained by applying the liquid crystal aligning agent in any one of said 1-10, and baking.

12. A liquid crystal display device comprising the liquid crystal alignment film according to 11 above.

The liquid crystal aligning film obtained from the liquid crystal aligning agent of the present invention and the liquid crystal display element using the same can suppress the accumulation of charge due to asymmetry of the positive and negative voltage during AC drive, and can quickly alleviate the accumulated charge. Has excellent liquid crystal orientation and excellent orientation stability.

<Polyamic acid and imidized polymer of the polyamic acid>

The liquid crystal aligning agent of the present invention is a group consisting of a tetracarboxylic dianhydride component containing pyromellitic dianhydride, a diamine of the following formula (1), and a diamine represented by the following formulas (2) and (3). At least one selected from the group consisting of a polyamic acid obtained by reacting a diamine component containing at least one selected diamine (hereinafter, also referred to as a specific diamine), and an imidized polymer of the polyamic acid (hereinafter, also referred to as a monopolymer) It is characterized by containing a kind of polymer.

[Formula 4]

In the above formula (2), A ₁ is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, and R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms And may be the same or different.

As the linear alkylene group, a methylene group, 1,2-ethylene group, 1,3-propylene group, 1,4-butylene group, 1,5-pentylene group, 1,6-hexylene group, 1,7 -Heptylene group, 1,8-octylene group, 1,9-nonylene group, 1,10-decylene group, etc. are mentioned.

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a t-butyl group. From the viewpoint of polymerization reactivity, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.

In the formula (3), A ₂ is a single bond, -O-, -S-, -NR ₆ -, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond. , R ₆ is a hydrogen atom, a methyl group, or a t-butoxycarbonyl group, R ₃ is a linear alkylene group having 1 to 10 carbon atoms, and R ₄ and R ₅ are each independently a hydrogen atom or a carbon number of 1 to It is an alkyl group of 4, and may be the same or different.

As the ester bond, it is represented by -C(O)O- or -OC(O)-.

As the amide bond, a structure represented by -C(O)NH-, -C(O)NR-, -NHC(O)-, or -NRC(O)- can be shown. Here, R is an alkyl group having 1 to 4 carbon atoms.

The thioester bond may represent a structure represented by -C(O)S-, or -SC(O)-.

As the urea bond, a structure represented by -NH-C(O)NH- or -NR-C(O)NR- may be represented. Here, R is an alkyl group having 1 to 4 carbon atoms.

As the carbonate bond, a structure represented by -O-C(O)-O- may be represented.

As the carbamate bond, -NH-C(O)-O-, -OC(O)-NH-, -NR-C(O)-O-, or -OC(O)-NR- It can represent a losing structure. Here, R is an alkyl group having 1 to 4 carbon atoms.

The linear alkylene group may have the same structure as the linear alkylene group.

The alkyl group may have the same structure as the alkyl group. From the viewpoint of polymerization reactivity, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.

In addition, in order to express the effect of the present invention, only the diamine represented by the above formula (1) needs to be reacted with pyromellitic dianhydride. Therefore, the liquid crystal aligning agent of the present invention may be a liquid crystal aligning agent containing a polymer (hereinafter also referred to as a blend polymer) in which the following polymers (A) and (B) are mixed at a constant ratio.

Polymer (A): selected from polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride and a diamine component containing diamine of formula (1), and an imidized polymer of the polyamic acid At least one kind of polymer.

Polymer (B): Polyamic acid obtained by reacting a tetracarboxylic dianhydride component and a diamine component containing at least one diamine selected from the group consisting of diamines represented by the above formulas (2) and (3), and a polyamic acid thereof. At least one type of polymer selected from imidized polymers of mixed acids.

<Tetracarboxylic dianhydride component>

In the at least one type of polymer selected from the group consisting of the polyamic acid contained in the liquid crystal aligning agent of the present invention and the imidized polymer of the polyamic acid, pyromellitic acid is used as tetracarboxylic dianhydride. If the ratio of the pyromellitic dianhydride used when obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is too small, the effect of the present invention cannot be obtained. Therefore, in the case of a single polymer, the ratio of pyromellitic dianhydride is preferably 10 to 100 mol%, more preferably 20 to 100 mol%, more preferably, based on 1 mol of all tetracarboxylic dianhydride. It is 30 to 100 mol%. In the case of a blended polymer, 20 to 100 mol% of the tetracarboxylic dianhydride component in the polymer (A) is preferably pyromellitic dianhydride, more preferably 30 to 100 mol%, and more preferably It is 40 to 100 mol%.

When obtaining the polyamic acid contained in the liquid crystal aligning agent of this invention and the imidation polymer of the polyamic acid, you may use tetracarboxylic dianhydride represented by following formula (17) other than pyromellitic dianhydride.

[Formula 5]

In formula (17), X is a tetravalent organic group, and its structure is not specifically limited. If a specific example is given, the organic group of the structure of following formula (X-1)-(X-42) is mentioned.

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

In formula (X-1), R ₁₁ to R ₁₄ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and a hydrogen atom or a methyl group is more preferable.

From the viewpoint of availability of the compound, the tetracarboxylic dianhydride is preferably at least one selected from the group consisting of tetracarboxylic dianhydride represented by the following formula (18).

[Formula 10]

(In formula (18), X ₁ is at least one species selected from the group consisting of organic groups having structures represented by formulas (X-1) to (X-13))

Since reliability, such as stability of voltage retention for long-time driving of the obtained liquid crystal aligning film, can be further improved, structures consisting of only aliphatic groups such as (X-1) to (X-7) and (X-10) are preferable. And the structure represented by (X-1) is more preferable. Moreover, since favorable liquid crystal orientation is shown, the following formula (X1-1) or (X1-2) is more preferable as the structure of X ₁ .

[Formula 11]

If the proportion of the tetracarboxylic dianhydride represented by the above formula (17) used when obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is increased, it is preferable because the effect of the present invention may be impaired. Not. Therefore, the ratio of the tetracarboxylic dianhydride represented by the above formula (17) is 0 to 90 with respect to 1 mole of the total tetracarboxylic dianhydride in the polymer (A) in the single polymer and the blend polymer. Mole% is preferable, More preferably, it is 0 to 80 mol%, More preferably, it is 0 to 70 mol%.

<Specific diamine>

When obtaining the polyamic acid which is the polymer which the liquid crystal aligning agent of this invention contains, and the imidation polymer of the polyamic acid, the diamine of said formula (1), (2), and (3) is used. Even if the ratio of the diamine represented by said formula (1) is too much at least too much, the effect of this invention is not obtained. Therefore, in the case of a single polymer, the ratio of the diamine represented by the above formula (1) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, and still more preferably 30 to 1 mol of all diamines. It is-70 mol%. In the case of a blended polymer, the proportion of the diamine represented by the formula (1) in the polymer (A) is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, and further Preferably it is 40 to 100 mol%.

From the viewpoint of liquid crystal orientation and orientation stability, the diamine represented by the formula (2) or (3) is preferably at least one selected from the group consisting of diamines represented by the following general formulas (4) to (10).

[Formula 12]

In formula (4), R ₇ and R ₈ are each independently a linear alkylene group having 1 to 10 carbon atoms, and may be the same or different.

The linear alkylene group may have the same structure as the linear alkylene group.

In formula (10), R ₉ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ₁₀ is a linear alkylene group having 1 to 10 carbon atoms.

The alkyl group may have the same structure as the alkyl group. From the viewpoint of polymerization reactivity, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.

The linear alkylene group may have the same structure as the linear alkylene group.

From the viewpoint of liquid crystal orientation and orientation stability and compound availability, as the diamine represented by the formula (2) or (3), in the group consisting of the diamine represented by the formula (6) and the following formulas (11) to (16) It is more preferable that it is at least 1 type selected.

[Formula 13]

Even if the ratio of the diamine represented by the above formula (2) or (3) used when obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is too large at least, the effect of the present invention is not obtained. Therefore, the ratio of the diamine represented by the above formula (2) or (3) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, more preferably 20 to 80 mol% with respect to 1 mol of all diamines in the case of a single polymer. Preferably it is 30 to 70 mol%. In the case of a blended polymer, the ratio of the diamine represented by the formula (1) in the polymer (B) is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, furthermore, based on the total diamine component. Preferably it is 40 to 100 mol%.

<Other diamines>

When obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid, in addition to the diamine represented by the above formulas (1) and (2) and (3), a diamine represented by the following formula (17) may be used. Y in the following formula (17) is a divalent organic group, and its structure is not particularly limited, and two or more types may be mixed. If a specific example is shown, the following (Y-1)-(Y-82) will be mentioned.

[Formula 14]

[Formula 15]

[Formula 16]

[Formula 17]

[Formula 18]

[Formula 19]

[Formula 20]

[Formula 21]

[Formula 22]

[Formula 23]

[Formula 24]

[Formula 25]

[Formula 26]

Especially, from the viewpoint of compound availability, Y is Y-4, Y-5, Y-16, Y-20, Y-21, Y-22, Y-32, Y-41, Y-42, Y-76 Or Y-79 diamine is more preferable.

If the proportion of the diamine represented by the above formula (17) used when obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is increased, it is not preferable because the effect of the present invention may be impaired. Therefore, the ratio of the diamine represented by the above formula (17) is preferably 0 to 90 mol%, more preferably 0 to 70 mol with respect to 1 mol of all diamines in either case of a single polymer or a blend polymer. %, more preferably 0 to 50 mol%.

<Production method of polyamic acid>

The polyamic acid which is a polyimide precursor used in the present invention can be synthesized by the method shown below.

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

The organic solvent used in the reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc., from the solubility of the monomer and polymer, and these are one or two You may mix and use the above.

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

The polyamic acid obtained as described above can be recovered by depositing a polymer by injecting it into a poor solvent while stirring the reaction solution well. In addition, by performing precipitation several times, washing with a poor solvent, and drying by heating or at room temperature, a purified polyamic acid powder can be obtained. Although a poor solvent is not specifically limited, Water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene, etc. are mentioned, and water, methanol, ethanol, 2-propanol, etc. are preferable.

<Production method of polyimide>

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

In the case of producing a polyimide from a polyamic acid, chemical imidization by adding a catalyst to the solution of the polyamic acid obtained by reaction of a diamine component and tetracarboxylic dianhydride is simple. Chemical imidation is preferable because the imidation reaction proceeds at a relatively low temperature, and the molecular weight of the polymer is less likely to decrease in the process of imidation.

Chemical imidization can be performed 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, a solvent used in the polymerization reaction described above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferable because it has a suitable basicity for advancing the reaction. Further, examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like, and among them, use of acetic anhydride is preferable because purification after completion of the reaction becomes easy.

The temperature when performing the imidation reaction is -20 to 140°C, preferably 0 to 100°C, and the reaction time can be performed in 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times the mole, preferably 2 to 20 times the mole of the polyamic acid group, and the amount of the acid anhydride is 1 to 50 times the mole, preferably 3 to 30 times the mole of the polyamic acid group. The imidation ratio of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

Since the added catalyst and the like remain in the solution after the imidation reaction of the polyamic acid, the obtained imidized polymer is recovered by the means described below, re-dissolved in an organic solvent, and used as the liquid crystal aligning agent of the present invention. desirable.

A polymer can be precipitated by injecting the polyimide solution obtained as described above into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or heated to obtain a purified polymer powder.

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

<Liquid crystal aligning agent>

The liquid crystal aligning agent used in the present invention has a 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 still more preferably 10,000 to 100,000 in terms of weight average molecular weight. Further, 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 concentration of the polymer of the liquid crystal aligning agent used in the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed. It is preferably 1% by mass or more from the viewpoint of forming a uniform, defect-free coating film, and preferably 10% by mass or less from the viewpoint of storage stability of the solution. A particularly preferable concentration of the polymer is 2 to 8% by mass.

The organic solvent contained in the liquid crystal aligning agent used for this invention is not specifically limited as long as the polymer component is uniformly dissolved. For specific examples, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrroly Don, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3- And methoxy-N,N-dimethylpropanamide. These may be used alone or in combination of two or more. Moreover, even if it is a solvent in which the polymer component cannot be dissolved uniformly by itself, it may be mixed with the organic solvent as long as the polymer is not precipitated.

In addition to the organic solvent for dissolving the polymer component, the liquid crystal aligning agent used in the present invention may contain a solvent for improving the coating film uniformity when the liquid crystal aligning agent is applied to a substrate. As such a solvent, a solvent having a lower surface tension than the organic solvent is generally used. 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, isoamyl lactate Ester, etc. are mentioned. These solvents may be used in combination of two or more.

In the liquid crystal aligning agent of the present invention, in addition to the above, as long as the effects of the present invention are not impaired, polymers other than the polymer required for the liquid crystal aligning agent of the present invention, the purpose of changing electrical properties such as dielectric constant and conductivity of the liquid crystal aligning film Dielectric or conductive material, a silane coupling agent for the purpose of improving the adhesion between the liquid crystal aligning film and the substrate, a crosslinkable compound for increasing the hardness and density of the film when used as a liquid crystal aligning film, and furthermore, the image of polyamic acid when firing the coating film. An imidation accelerator or the like for the purpose of efficiently advancing decomposition may be added.

In addition, in the case of a liquid crystal aligning agent containing a blended polymer, the preferred mixing ratio of the polymer (A) and the polymer (B) is in the range of 10:90 to 90:10 as the weight ratio of the polymer (A):polymer (B). And more preferably 20:80 to 80:20.

<Method of manufacturing liquid crystal alignment film>

The liquid crystal aligning film of this invention is a film obtained by apply|coating the said liquid crystal aligning agent to a board|substrate, and drying and baking. 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 plastic substrates such as glass substrates, silicon nitride substrates, acrylic substrates, and polycarbonate substrates can be used, and ITO for liquid crystal drive It is preferable from the viewpoint of process simplification to use a substrate on which electrodes or the like are formed. In addition, in the reflective liquid crystal display device, as long as it is only on the substrate on one side, an opaque material such as a silicon wafer can be used, and as an electrode in this case, a material that reflects light such as aluminum can also be used.

As a coating method of the liquid crystal aligning agent of this invention, a spin coating method, a printing method, an inkjet method, etc. are mentioned. The drying and baking process after applying the liquid crystal aligning agent of this invention can select arbitrary temperature and time. Usually, in order to sufficiently remove the organic solvent contained, it is dried at 50-120 degreeC for 1 minute to 10 minutes, and then fired at 150 to 300 degreeC for 5 minutes 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 device may be lowered, and thus it is 5 to 300 nm, preferably 10 to 200 nm.

A rubbing method, a photoalignment treatment method, etc. are mentioned as a method of aligning the obtained liquid crystal aligning film.

As a specific example of the photoalignment treatment method, the surface of the coating film is irradiated with radiation polarized in a certain direction, and in some cases, further heat treatment is performed at a temperature of 150 to 250°C to impart liquid crystal alignment ability. There is a method. As radiation, ultraviolet rays and visible rays having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable. Moreover, in order to improve the liquid crystal orientation, you may irradiate a radiation while heating the coating film substrate at 50-250 degreeC. The radiation dose is preferably 1 to 10,000 mJ/cm 2, and particularly preferably 100 to 5,000 mJ/cm 2. The liquid crystal alignment film prepared as described above can stably align liquid crystal molecules in a predetermined direction.

In the above, the film irradiated with polarized radiation may then be subjected to contact treatment with a solvent containing at least one type selected from the group consisting of water and an organic solvent.

The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves the decomposition product generated by irradiation with light. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 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 two or more.

From the viewpoint of versatility and safety, at least one species selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate is more preferable. Particularly preferred is 1-methoxy-2-propanol or ethyl lactate.

In the present invention, the contact treatment of the film irradiated with polarized radiation and the solution containing the organic solvent is performed by a treatment in which the film and the liquid are preferably sufficiently contacted, such as an immersion treatment or a spray (spray) treatment. Among them, a method of immersing the film in a solution containing an organic solvent is preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes. The contact treatment may be at room temperature or may be heated, but is preferably 10 to 80°C, more preferably 20 to 50°C. Further, if necessary, means for increasing contact such as ultrasonic waves can be implemented.

After the contact treatment, for the purpose of removing the organic solvent in the used solution, either rinsing (rinsing) or drying with a low-boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or both You may do it.

Further, the film subjected to the contact treatment with a solvent may be heated at 150°C or higher for the purpose of drying the solvent and reorienting the molecular chains in the film.

The heating temperature is preferably 150 to 300°C. The higher the temperature, the more promoted the rearrangement of the molecular chain, but too high a temperature may involve decomposition of the molecular chain. Therefore, 180-250 degreeC is more preferable as a heating temperature, and 200-230 degreeC is especially preferable.

If the heating time is too short, there is a possibility that the effect of the present invention may not be obtained, and if it is too long, the molecular chain may be decomposed. Therefore, 10 seconds to 30 minutes are preferable, and 1 minute to 10 minutes are more preferable.

The liquid crystal aligning film of this invention is preferable as a liquid crystal aligning film of a horizontal electric field type liquid crystal display element, such as an IPS method and an FFS method, and is especially useful as a liquid crystal aligning film of a liquid crystal display element of an FFS method.

<Liquid crystal display element>

In the liquid crystal display device of the present invention, after obtaining a substrate on which a liquid crystal alignment film obtained from the liquid crystal aligning agent obtained by the production method of the present invention was formed, a liquid crystal cell was prepared by a known method, and the liquid crystal cell was used as a liquid crystal display device. will be.

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

First, a transparent glass substrate is prepared, a common electrode is formed on one substrate, and a segment electrode is formed on the other substrate. These electrodes can be used as ITO electrodes, for example, and are patterned so as to display a desired image. Subsequently, an insulating film is formed on each substrate by covering the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ -TiO ₂ formed by a sol-gel method.

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

Next, the other substrate is superimposed on one substrate so that the alignment film surfaces thereof face each other, and the periphery is adhered with a sealing material. In order to control the gap between the substrates, a spacer is usually mixed with the sealing material. In addition, it is preferable to disperse a spacer for controlling a substrate gap even in an in-plane portion where a sealing material is not formed. In a part of the sealing material, an opening portion capable of filling liquid crystal from the outside is formed.

Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing material through the opening formed in the sealing material. After that, this opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method using a capillary phenomenon in the atmosphere may be used. As a liquid crystal material, you may use either a positive liquid crystal material and a negative liquid crystal material. In particular, even when a negative liquid crystal material having a lower voltage retention rate than a positive liquid crystal material is used, when the liquid crystal aligning film of the present invention is used, the afterimage property is excellent. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is affixed on the surface of the two substrates opposite to the liquid crystal layer. By passing through the above process, the liquid crystal display element of this invention is obtained. This liquid crystal display element uses a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film of the present invention as a liquid crystal alignment film, so that the afterimage property is excellent, and a high-definition multifunctional mobile phone (smart phone) or a tablet type personal computer , Liquid crystal televisions, and the like.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and the like. In addition, the present invention is not limited to these Examples. In addition, the abbreviations in the following are as follows.

NMP: N-methyl-2-pyrrolidone

GBL: γ-butyrolactone

BCS: Butyl Cellosolve

Acid dianhydride (D-1): a compound represented by the following formula (D-1)

Acid dianhydride (D-2): a compound represented by the following formula (D-2)

DA-1: compound represented by the following formula (DA-1)

DA-2: compound represented by the following formula (DA-2)

DA-3: compound represented by the following formula (DA-3)

DA-4: compound represented by the following formula (DA-4)

[Formula 27]

Hereinafter, the viscosity and solid content concentration measurement, production of a liquid crystal cell, relaxation characteristics of the accumulated charge, accumulated charge due to asymmetry of the positive and negative voltage during AC drive, and a method for evaluating a liquid crystal alignment afterimage by long-term AC drive are shown. .

[Viscosity measurement]

The viscosity of the polyamic acid solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Industries, Ltd.) at a sample amount of 1.1 ml (milliliters), cone rotor TE-1 (1° 34', R24), and a temperature of 25°C. .

[Measurement of solid content concentration]

The calculation of the solid content concentration of the polyamic acid solution was carried out as follows.

Approximately 1.1 g of a polyamic acid solution was weighed and taken in an aluminum cup No.2 with a handle (manufactured by Asone), heated in an oven DNF400 (manufactured by Yamato) at 200°C for 2 hours, then left at room temperature for 5 minutes, and aluminum The weight of the solid content remaining in the cup was weighed. The solid content concentration was calculated from the values of this solid content weight and the original solution weight.

[Production of liquid crystal cell]

A liquid crystal cell provided with the structure of a liquid crystal display element of the FFS system is produced.

First, a substrate on which electrodes were formed was prepared. The substrate is a glass substrate having a size of 30 mm x 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode having a solid pattern constituting the counter electrode as the first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed as a second layer by the CVD method is formed. The second layer of SiN film has a thickness of 500 nm and functions as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an IZO film as a third layer is disposed on the second SiN film, forming two pixels, a first pixel and a second pixel. Each pixel has a size of 10 mm in length and about 5 mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

The pixel electrode of the third layer has a comb-like shape constituted by arranging a plurality of U-shaped electrode elements with a central portion bent. The width of each electrode element in the width direction is 3 μm, and the spacing between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is configured by arranging a plurality of U-shaped electrode elements with a central portion bent, the shape of each pixel is not a rectangular shape, but a bold font that is curved at the center portion like the electrode element. It has a shape similar to a く. Then, each pixel is divided up and down with the central bent portion as a boundary, and has a first area on the upper side of the bent portion and a second area on the lower side.

When the first region and the second region of each pixel are compared, the formation directions of electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment layer described later is taken as a reference, the electrode element of the pixel electrode is formed to form an angle of +10° (clockwise direction) in the first region of the pixel, and the pixel electrode in the second region of the pixel The electrode elements of are formed to achieve an angle of -10° (clockwise). That is, in the first region and the second region of each pixel, the directions of the rotational operation (inplane switching) of the liquid crystal in the substrate plane caused by the application of a voltage between the pixel electrode and the counter electrode are opposite to each other. Consists of.

Next, the obtained liquid crystal aligning agent was filtered through a 1.0 µm filter, and then applied to the prepared substrate on which the electrode was formed by spin coating. After drying for 5 minutes on an 80 degreeC hot plate, it baked for 30 minutes in a 230 degreeC hot air circulation type oven, and obtained the polyimide film with a film thickness of 60 nm. Rubbing this polyimide film with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, movement speed: 30 mm/sec, press fit length: 0.3 mm, rubbing direction: a direction inclined by 10° to the third layer IZO comb electrode ), after washing|cleaning by ultrasonic irradiation for 1 minute in pure water, and after removing water droplets by air blow, it dried at 80 degreeC for 15 minutes, and the board|substrate with a liquid crystal aligning film was obtained. In addition, as a counter substrate, a glass substrate having a columnar spacer having a height of 4 μm on which an ITO electrode is formed on the back surface was also formed with a polyimide film in the same manner as above, and the liquid crystal alignment film subjected to alignment treatment in the same procedure as above. This formed substrate was obtained. The two substrates on which the liquid crystal alignment film is formed are used as a set, and the sealant is printed in the form of leaving the liquid crystal injection hole on the substrate, and the other substrate is attached with the liquid crystal alignment layer facing each other and the rubbing direction is antiparallel. After that, the sealing agent was cured to prepare a blank cell having a cell gap of 4 μm. Liquid crystal MLC-2041 (manufactured by Merck) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain a liquid crystal cell of the FFS system. After that, the obtained liquid crystal cell was heated at 110°C for 1 hour and left at 23°C overnight, and then used for each evaluation.

[Evaluation of relaxation characteristics of accumulated charge]

The liquid crystal cell is installed between two polarizing plates arranged so that the polarization axes are perpendicular to each other, and the pixel electrode and the counter electrode are short-circuited to achieve the same potential, while the LED backlight is irradiated from the bottom of the two polarizing plates, and on the two polarizing plates. , The angle of the liquid crystal cell was adjusted so that the brightness of the transmitted light of the LED backlight to be measured was minimized.

Next, while applying a square wave with a frequency of 30 Hz to this liquid crystal cell, the V-T characteristic (voltage-transmittance characteristic) under a temperature of 23°C was measured, and an alternating voltage at which the relative transmittance was 23% was calculated.

Next, after applying a square wave having a frequency of 30 Hz for 5 minutes at an alternating current voltage having a relative transmittance of 23%, a DC voltage of +1.0 V was superimposed and driven for 30 minutes. Thereafter, the DC voltage was cut off, and only a square wave having a frequency of 30 Hz was applied for 20 minutes with an AC voltage having a relative transmittance of 23%.

Since the faster the relaxation of the accumulated charge is, the faster the charge accumulation in the liquid crystal cell when the DC voltage is superimposed. Therefore, the relaxation characteristic of the accumulated charge is from the state where the relative transmittance is 30% or more immediately after the DC voltage is superimposed. When the relative transmittance decreased to less than 28% until 30 minutes elapsed, it was defined as "good" and evaluated. Even if 30 minutes elapsed after superimposing the DC voltage, when the relative transmittance did not decrease to less than 28%, it was defined as "defect" and evaluated.

[Evaluation of accumulated charge by asymmetry of positive and negative voltage during AC drive]

The liquid crystal cell is installed between two polarizing plates arranged so that the polarization axes are perpendicular to each other, and the pixel electrode and the counter electrode are short-circuited to achieve the same potential, while the LED backlight is irradiated from the bottom of the two polarizing plates, and on the two polarizing plates. The angle of the liquid crystal cell was adjusted so that the luminance of the transmitted light of the LED backlight to be measured was minimized.

Next, while applying a square wave with a frequency of 30 Hz to this liquid crystal cell, the V-T characteristic (voltage-transmittance characteristic) under a temperature of 23°C was measured, and the AC voltage at which the relative transmittance was 23% and 100% was calculated. Thereafter, the pixel electrode and the counter electrode were short-circuited and allowed to stand at the same potential for 60 minutes or longer to release the electric charges accumulated in the liquid crystal cell.

Next, a square wave with a frequency of 30 Hz was applied for 30 minutes with an alternating voltage at which the relative transmittance was 100%. However, during the 30 minutes, the voltage was switched to an AC voltage having a relative transmittance of 23% for only 20 seconds at intervals of 3 minutes. VF characteristic (DC voltage-flicker characteristic) is measured during 20 seconds while switching to AC voltage at which relative transmittance becomes 23%, and asymmetry of positive and negative voltage when driven by AC voltage at which relative transmittance becomes 100% The DC voltage value for eliminating the accumulated charge by fire was recorded. When the DC voltage value for eliminating this accumulated charge changed by 15 mV or more by driving for 30 minutes, it was defined as "defect" and evaluated. In the case where the DC voltage value for removing the accumulated charge only changed by less than 15 mV by driving for 30 minutes, it was defined as "good" and evaluated.

[Evaluation of liquid crystal alignment afterimage by long-term AC drive]

Using the liquid crystal cell, a square wave of ±5 V was applied for 168 hours at a frequency of 30 Hz in a constant temperature environment at 60°C. After that, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited to have the same potential, and left as it is at 23°C for 24 hours.

After standing, the liquid crystal cell was installed between two polarizing plates arranged so that the polarization axes were orthogonal, and the pixel electrode and the counter electrode were short-circuited to achieve the same potential, and the LED backlight was irradiated from the bottom of the two polarizing plates. The angle of the liquid crystal cell was adjusted so that the brightness of the transmitted light of the LED backlight measured on the polarizing plate was minimized. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel becomes darkest to the angle at which the first region becomes darkest was calculated as the angle Δ. Similarly in the second pixel, the second region and the first region were compared, and the same angle Δ was calculated. Then, the average value of the angle Δ value of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. When this angle Δ was less than 0.5 degrees, it was defined as "good" and evaluated. When the angle Δ was 0.5 degrees or more, it was defined as "defective" and evaluated.

(Synthesis Example 1)

In a 100 ml four-necked flask equipped with a stirring device and a nitrogen inlet tube, DA-1 was 3.18 g (8.10 mmol), DA-2 was 1.98 g (8.10 mmol), and DA-3 was 1.62 g (10.8 g). mmol) was weighed and taken, and 71.2 g of NMP was further added, and it was stirred and dissolved while sending nitrogen. While stirring this diamine solution, 5.36 g (24.6 mmol) of acid dianhydride (D-1) was added, 17.8 g of NMP was further added, and it stirred at 23 degreeC under nitrogen atmosphere for 3 hours, and polyamic acid solution ( PAA-1) was obtained. The viscosity of this polyamic acid solution at a temperature of 25°C was 247 mPa·s. Moreover, the solid content concentration of this polyamic acid solution was 11.5 weight%.

(Synthesis Example 2)

To a 100 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, DA-1 was 3.30 g (8.40 mmol), DA-2 was 2.05 g (8.40 mmol), and DA-3 was 1.68 g (11.2). mmol) weighed and taken, further added 67.8 g of NMP, stirred and dissolved while sending nitrogen. While stirring this diamine solution, 3.46 g (17.6 mmol) of acid dianhydride (D-2) and 1.83 g (8.40 mmol) of acid dianhydride (D-1) were added, and 22.6 g of NMP was further added. It added and stirred at 23 degreeC for 3 hours in nitrogen atmosphere, and obtained the polyamic acid solution (PAA-2). The viscosity of this polyamic acid solution at a temperature of 25°C was 417 mPa·s. Moreover, the solid content concentration of this polyamic acid solution was 11.4 weight%.

(Comparative Synthesis Example 1)

In a 50 ml four-necked flask equipped with a stirring device and a nitrogen inlet tube, DA-1 was 1.41 g (3.60 mmol), DA-2 was 0.88 g (3.60 mmol), and DA-3 was 0.72 g (4.80 mmol). mmol) was weighed and taken, and 27.1 g of NMP was further added, and it was stirred and dissolved while sending nitrogen. While stirring this diamine solution, 2.16 g (11.0 mmol) of acid dianhydride (D-2) was added, and 10.9 g of NMP was further added, and it stirred at 23 degreeC under nitrogen atmosphere for 3 hours, and polyamic acid solution ( PAA-3) was obtained. The viscosity of this polyamic acid solution at a temperature of 25°C was 220 mPa·s. Moreover, the solid content concentration of this polyamic acid solution was 12.0 weight%.

(Comparative Synthesis Example 2)

In a 100 ml four-necked flask equipped with a stirring device and a nitrogen inlet tube, DA-2 was 2.27 g (9.30 mmol), DA-3 was 1.86 g (12.4 mmol), and DA-4 was 1.85 g (9.30 mmol). mmol) was weighed and taken, and 71.2 g of NMP was further added, and it was stirred and dissolved while sending nitrogen. While stirring this diamine solution, 6.15 g (28.2 mmol) of acid dianhydride (D-1) was added, 17.8 g of NMP was further added, and under nitrogen atmosphere, it stirred at 23 degreeC for 3 hours, and polyamic acid solution ( PAA-4) was obtained. The viscosity of this polyamic acid solution at a temperature of 25°C was 178 mPa·s. Moreover, the solid content concentration of this polyamic acid solution was 11.6 weight%.

(Example 1)

15.6 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was aliquoted into a 100 ml Erlenmeyer flask containing a stirrer, 4.47 g of NMP, 7.93 g of GBL, and 1 of 3-glycidoxypropyltriethoxysilane. 1.78 g and 9.91 g of BCS were added to the NMP solution containing weight%, and it stirred with a magnetic stirrer for 2 hours, and the liquid crystal aligning agent (A-1) was obtained.

(Example 2)

15.5 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was aliquoted into a 100 ml Erlenmeyer flask containing a stirrer, and 4.41 g of NMP, 7.89 g of GBL, and 3-glycidoxypropyltriethoxysilane were 1 1.78 g of NMP solution containing weight% and 9.86 g of BCS were added, and it stirred with a magnetic stirrer for 2 hours, and the liquid crystal aligning agent (A-2) was obtained.

(Comparative Example 1)

18.2 g of the polyamic acid solution (PAA-3) obtained in Comparative Synthesis Example 1 was aliquoted into a 100 ml Erlenmeyer flask containing a stirrer, 3.60 g of NMP, 8.72 g of GBL, and 3-glycidoxypropyltriethoxysilane. 2.18 g and 10.9 g of BCS were added to the NMP solution containing 1 weight%, and it stirred with a magnetic stirrer for 2 hours, and the liquid crystal aligning agent (B-1) was obtained.

(Comparative Example 2)

15.4 g of the polyamic acid solution (PAA-4) obtained in Comparative Synthesis Example 2 was aliquoted into a 100 ml Erlenmeyer flask containing a stirrer, 5.21 g of NMP, 7.95 g of GBL, and 3-glycidoxypropyltriethoxysilane. 1.79 g and 9.38 g of BCS were added to the NMP solution containing 1 weight%, and it stirred with a magnetic stirrer for 2 hours, and obtained the liquid crystal aligning agent (B-2).

(Example 3)

After filtering the liquid crystal aligning agent (A-1) obtained in Example 1 with a 1.0 µm filter, on a glass substrate, an IZO electrode having a film thickness of 50 nm as the first layer was used as a second insulating film with a film thickness of 500. A spin coat is applied to a glass substrate on which an FFS-type electrode having nm silicon nitride is formed as a third layer with a comb-shaped IZO electrode (electrode width: 3 µm, electrode gap: 6 µm, electrode height: 50 nm) Was applied. Then, after drying for 5 minutes on an 80 degreeC hot plate, it baked for 30 minutes in a 230 degreeC hot air circulation type oven, and obtained the polyimide film with a film thickness of 60 nm. Rubbing this polyimide film with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, movement speed: 30 mm/sec, press fit length: 0.3 mm, rubbing direction: 10° inclined to the third layer IZO comb electrode Orientation) After performing, ultrasonic irradiation was performed in pure water for 1 minute, and after removing water droplets by air blow, it dried at 80 degreeC for 15 minutes, and the board|substrate with a liquid crystal aligning film was obtained. In addition, as a counter substrate, on a glass substrate having a columnar spacer having a height of 4 µm on which an ITO electrode is formed on the back surface, a polyimide film was formed in the same manner as above, and alignment treatment was performed in the same procedure as the above. A substrate on which an alignment film was formed was obtained.

The two substrates on which the liquid crystal alignment film is formed are used as a set, and the sealant is printed in the form of leaving the liquid crystal injection hole on the substrate, and the other substrate is attached with the liquid crystal alignment layer facing each other and the rubbing direction is antiparallel. After that, the sealing agent was cured to prepare a blank cell having a cell gap of 4 μm. Liquid crystal MLC-2041 (manufactured by Merck) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain a liquid crystal cell of the FFS system. After that, the obtained liquid crystal cell was heated at 110°C for 1 hour and left at 23°C overnight, and then used for each evaluation.

The FFS type liquid crystal cell was evaluated for the relaxation characteristics of the accumulated charge, which was good. Moreover, as a result of evaluating the accumulated charge due to the asymmetry of the positive and negative voltages during AC drive, the results were good. Moreover, it was favorable as a result of evaluating a liquid crystal alignment afterimage by long-term AC drive.

(Example 4)

Except having used the liquid crystal aligning agent (A-2) obtained in Example 2, the liquid crystal cell of the FFS system was produced in the same manner as in Example 3. The FFS type liquid crystal cell was evaluated for the relaxation characteristics of the accumulated charge, which was good. Moreover, as a result of evaluating the accumulated charge due to the asymmetry of the positive and negative voltages during AC drive, the results were good. Moreover, it was favorable as a result of evaluating a liquid crystal alignment afterimage by long-term AC drive.

(Comparative Example 3)

Except having used the liquid crystal aligning agent (B-1) obtained in Comparative Example 1, a liquid crystal cell of the FFS system was produced in the same manner as in Example 3. As a result of evaluating the relaxation characteristics of the accumulated charge about the liquid crystal cell of this FFS system, it was defective. Moreover, as a result of evaluating the accumulated charge due to the asymmetry of the positive and negative voltages during AC drive, the results were good. Moreover, it was favorable as a result of evaluating a liquid crystal alignment afterimage by long-term AC drive.

(Comparative Example 4)

Except having used the liquid crystal aligning agent (B-2) obtained in Comparative Example 2, a liquid crystal cell of the FFS system was produced in the same manner as in Example 3. The FFS type liquid crystal cell was evaluated for the relaxation characteristics of the accumulated charge, which was good. Moreover, as a result of evaluating the accumulated charge due to the asymmetry of the positive and negative voltages during AC drive, it was defective. Moreover, it was favorable as a result of evaluating a liquid crystal alignment afterimage by long-term AC drive.

Industrial availability

By using the liquid crystal aligning film obtained from the liquid crystal aligning agent of the present invention, it is possible to suppress the accumulation of charges due to asymmetry of the positive and negative voltages during AC driving, and can quickly alleviate the accumulated charges, and further, excellent liquid crystal alignment and An IPS driving method or an FFS driving method liquid crystal display device having excellent alignment stability and excellent afterimage characteristics can be obtained. In particular, the liquid crystal display element having this liquid crystal alignment film can be used for a multifunctional mobile phone (smart phone), a tablet personal computer, a liquid crystal television, or the like.

In addition, the specification of Japanese Patent Application No. 2013-206728 for which it applied on October 1, 2013, a claim, and all the content of the abstract are cited here, and it takes in as an indication of this invention specification.

Claims (12)

Contains at least one diamine selected from the group consisting of a tetracarboxylic dianhydride component containing pyromellitic dianhydride, a diamine of the following formula (1), and a diamine represented by the following formulas (2) and (3). A liquid crystal aligning agent comprising at least one type of polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine component described above and an imidized polymer of the polyamic acid.

(In formula (2), A ₁ is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, and R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (3), A ₂ is a single bond, -O-, -S-, -NR ₆ -, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond, and R ₆ Is a hydrogen atom, a methyl group, or a t-butoxycarbonyl group, R ₃ is a linear alkylene group having 1 to 10 carbon atoms, and R ₄ and R ₅ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ) The method of claim 1,
The liquid crystal aligning agent in which 10-100 mol% of the said tetracarboxylic dianhydride component is pyromellitic dianhydride. The method of claim 1,
The liquid crystal aligning agent in which 10-90 mol% of the said diamine component is a diamine of Formula (1). The method of claim 1,
A liquid crystal aligning agent in which 10 to 90 mol% of the diamine component is at least one diamine selected from the group consisting of diamines represented by formulas (2) and (3). A liquid crystal aligning agent containing the following polymers (A) and (B).
Polymer (A): selected from polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride and a diamine component containing a diamine of the following formula (1), and an imidized polymer of the polyamic acid At least one kind of polymer.
Polymer (B): Polyamic acid obtained by reacting a tetracarboxylic dianhydride component and a diamine component containing at least one diamine selected from diamines of the following formulas (2) and (3), and imidization of the polyamic acid At least one type of polymer selected from polymers.

(In formula (2), A ₁ is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, and R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (3), A ₂ is a single bond, -O-, -S-, -NR ₆ -, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond, and R ₆ Is a hydrogen atom, a methyl group, or a t-butoxycarbonyl group, R ₃ is a linear alkylene group having 1 to 10 carbon atoms, and R ₄ and R ₅ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ) The method of claim 5,
The liquid crystal aligning agent in which 20-100 mol% of a tetracarboxylic dianhydride component is pyromellitic dianhydride in said polymer (A). The method of claim 5,
In the said polymer (A), 20-100 mol% of a diamine component is a diamine of Formula (1), The liquid crystal aligning agent. The method of claim 5,
In the polymer (B), 20 to 100 mol% of the diamine component is at least one diamine selected from the group consisting of diamines represented by formulas (2) and (3). The method according to any one of claims 1 to 8,
The diamine of formula (2) is at least one species selected from the group consisting of diamines represented by the following formulas (4) to (9), and the diamine of formula (3) is selected from the group consisting of diamines represented by the following formula (10) Liquid crystal aligning agent which is at least 1 type to become.

(In formula (4), R ₇ and R ₈ are each independently a linear alkylene group having 1 to 10 carbon atoms, and may be the same or different. In formula (10), R ₉ is a hydrogen atom, or an alkyl group having a carbon number of 1 to 4, R ₁₀ is a straight-chain alkylene group having 1 to 10 carbon atoms.) The method of claim 9,
The diamine of formula (2) is at least 1 species selected from the group consisting of diamines represented by the formula (6) and the following formulas (11) to (14), and the diamine of formula (3) is the following formula (15) And at least one liquid crystal aligning agent selected from the group consisting of diamines represented by (16).

A liquid crystal aligning film obtained by applying the liquid crystal aligning agent according to any one of claims 1 to 8 and firing. A liquid crystal display device comprising the liquid crystal aligning film according to claim 11.