JPWO2015050133A1 - Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display element using the same - Google Patents

Abstract

Charge accumulation due to asymmetry of positive and negative voltages during AC drive can be suppressed, the accumulated charge can be quickly relaxed, a liquid crystal aligning agent, a liquid crystal alignment film having excellent liquid crystal alignment properties and excellent alignment stability, and using the same A liquid crystal display element is provided. At least one 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 polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine component containing diamine and an imidized polymer of the polyamic acid. [In formula (2), A1 is a divalent organic group containing a linear alkylene group having 1 to 10 carbon atoms, and R1 and R2 are each independently a hydrogen atom or a carbon number. 1 to 4 alkyl groups, wherein A2 is a single bond, —O—, —S—, —NR 6 —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate bond. R6 is a hydrogen atom, a methyl group or a t-butoxycarbonyl group, R3 is a linear alkylene group having 1 to 10 carbon atoms, and R4 and R5 are each independently a hydrogen atom or a carbon atom. (It is an alkyl group of formulas 1 to 4.)

Description

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

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

  Liquid crystal molecule driving methods include vertical electric field methods such as TN (Twisted Nematic) method and VA (Virtical Alignment) method, IPS (In-Place-Switching) method, fringe field switching (hereinafter referred to as FFS). ) Method and other horizontal electric field methods are known. In general, the lateral electric field method in which an electrode is formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate is compared with a conventional vertical electric field method in which a liquid crystal is driven by applying a voltage to the electrodes formed on the upper and lower substrates. It is known as a liquid crystal display element having a wide viewing angle characteristic and capable of high-quality display.

  However, although the horizontal 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 holding ratio of the liquid crystal alignment film is weak, sufficient voltage is applied to the liquid crystal. Therefore, the display contrast is lowered. In addition, charges are accumulated in the liquid crystal display element due to the asymmetry of the DC voltage component applied from the active matrix structure which is a problem in the past and the positive and negative voltage at the time of AC driving that has been attracting attention in recent years, These accumulated charges affect the display as disorder of the alignment of the liquid crystal, and also afterimage and burn-in, and the display quality of the liquid crystal display element is significantly lowered. Alternatively, when driving in a state where charges are accumulated, liquid crystal molecules are not normally controlled immediately after driving, and flicker (flicker) or the like occurs. In particular, in the horizontal electric field method, since the distance between the pixel electrode and the common electrode is shorter than in the vertical electric field method, a strong electric field acts on the alignment film and the liquid crystal layer, and these inconveniences are likely to be noticeable. is there.

Furthermore, in a system in which liquid crystal molecules that are aligned parallel to the substrate are driven by lateral electrolysis, such as an IPS system or an FFS driving system, the stability of the liquid crystal alignment is also important. If the alignment stability is poor, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast, an afterimage or a burn-in.
With the improvement in performance of liquid crystal display elements, requirements for characteristics required for liquid crystal alignment films have become strict. That is, excellent liquid crystal alignment and alignment stability, high voltage holding ratio and stability of voltage holding ratio for long-time driving, less accumulated charge when applying DC voltage, asymmetry of positive and negative voltage during AC driving Characteristics such as suppression of charge accumulation due to, and rapid relaxation of accumulated charge are important.

Various proposals have been made for polyimide-based liquid crystal alignment films in order to meet the above requirements. For example, a liquid crystal alignment agent containing a tertiary amine having a specific structure in addition to polyamic acid or imide group-containing polyamic acid as a liquid crystal alignment film having a short time until an afterimage generated by application of a DC voltage disappears (For example, refer patent document 1), the thing using the liquid crystal aligning agent containing the soluble polyimide which used the specific diamine compound which has pyridine frame | skeleton etc. as a raw material (for example, refer patent document 2), etc. are proposed.
In addition, as a liquid crystal aligning agent for a lateral electric field driving method having excellent printability and rubbing resistance and less afterimage and image sticking, Patent Document 3 discloses an amic acid unit derived from an aromatic tetracarboxylic acid, and an alicyclic type. A liquid crystal aligning agent containing both amic acid units derived from tetracarboxylic acid by copolymerization or mixing is disclosed.

Furthermore, as a liquid crystal aligning agent for obtaining a liquid crystal aligning film that is excellent in orientation, alignment regulating power, rubbing resistance, high voltage holding ratio, and reduced charge accumulation when a DC voltage is applied, Patent Document 4 discloses And a low-resistance polyimide precursor having a volume resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ωcm when formed into a film, and a highly-oriented polyimide precursor or polyimide having a specific structure, A liquid crystal aligning agent and a liquid crystal display element using the liquid crystal aligning agent are disclosed.
Further, as a liquid crystal aligning agent having a high voltage holding ratio and maintaining a high voltage holding ratio even after being exposed to a high temperature for a long time, and having a small residual charge when a DC voltage is applied, Patent Document 5 includes a liquid crystal aligning agent characterized by containing a copolymer obtained by reacting a diamine containing a tertiary amine having a specific molecular structure, a diamine containing a carboxyl group, and an acid dianhydride. And a liquid crystal display device using the liquid crystal aligning agent is disclosed.

Also, a first alignment film formed on the electrode, and a polymer composed of pyromellitic dianhydride and diamine formed on the surface thereof, and a second alignment film having a lower resistance than the first alignment film In a liquid crystal display element having a liquid crystal alignment film as described above, it has been reported that charge accumulation due to asymmetry of positive and negative voltages during AC driving can be suppressed, and that the accumulated charge can be quickly relaxed (see Patent Document 6).
However, 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 charge with one type of alignment film has not yet been reported.

Japanese Unexamined Patent Publication No. 9-316200 Japanese Unexamined Patent Publication No. 10-104633 International Publication WO02 / 33481 Pamphlet International Publication WO 2004/53583 Pamphlet International Publication WO2009 / 93709 Pamphlet Japanese Unexamined Patent Publication No. 2013-167788

The present inventors have found that it is difficult to achieve both the suppression of charge accumulation due to the asymmetry of the positive and negative voltages during AC driving and the simultaneous relaxation of the accumulated charges with one type of liquid crystal alignment film. confirmed.
The present invention can suppress charge accumulation due to the asymmetry of positive and negative voltages during AC driving, which is a problem particularly in the lateral electric field driving method, and can quickly relieve the accumulated charges, and is further excellent. An object of the present invention is to provide a liquid crystal aligning agent from which a liquid crystal alignment film having excellent liquid crystal alignment properties and excellent alignment stability can be obtained.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the gist of the present invention is as follows.
1. At least one 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 polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine component containing diamine and an imidized polymer of the polyamic acid.

(In the 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 1 carbon atom. In formula (3), A ₂ is a single bond, —O—, —S—, —NR ₆ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate. A 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 It is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

2. 2. The liquid crystal aligning agent according to 1, wherein 10 to 100 mol% of the tetracarboxylic dianhydride component is pyromellitic dianhydride.
3. The liquid crystal aligning agent of said 1 or 2 whose 10-90 mol% of the said diamine component is the diamine of the said Formula (1).
4). The liquid crystal alignment according to any one of 1 to 3, wherein 10 to 90 mol% of the diamine component is at least one diamine selected from the group consisting of the diamines represented by the formulas (2) and (3). Agent.

5). Liquid crystal aligning agent containing the following polymers (A) and (B).
Polymer (A): a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride with a diamine component containing the diamine of the above formula (1), and the polyamic acid At least one polymer selected from imidized polymers;
Polymer (B): a polyamic acid obtained by reacting a tetracarboxylic dianhydride component with a diamine component containing at least one diamine selected from the diamines of the above formulas (2) and (3), and the polyamic acid At least one polymer selected from acid imidized polymers;
6). 6. The liquid crystal aligning agent according to 5 above, wherein in the polymer (A), 20 to 100 mol% of the tetracarboxylic dianhydride component is pyromellitic dianhydride.
7). The liquid crystal aligning agent of said 5 or 6 whose 20-100 mol% of a diamine component is the diamine of the said Formula (1) in the said polymer (A).
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). The liquid crystal aligning agent in any one.

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

（式（４）において、Ｒ_７及びＲ_８は、それぞれ独立して、炭素数１〜１０の直鎖アルキレン基であり、同一でも異なってもよい。式（１０）において、Ｒ_９は水素原子、又は炭素数１〜４のアルキル基であり、Ｒ_１０は炭素数１〜１０の直鎖アルキレン基である。）

(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 1 to 4 carbon atoms, and R ₁₀ is a linear alkylene group having 1 to ₁₀ carbon atoms.)

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

11. The liquid crystal aligning film obtained by apply | coating and baking the liquid crystal aligning agent in any one of said 1-10.
12 12. A liquid crystal display device comprising the liquid crystal alignment film as described in 11 above.

  The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention and the liquid crystal display element using the same can suppress charge accumulation due to asymmetry of positive and negative voltages during AC driving, and can quickly relax the accumulated charge. Further, it has excellent liquid crystal alignment and excellent alignment stability.

<Polyamic acid and imidized polymer of the polyamic acid>
The liquid crystal aligning agent of this invention is from the tetracarboxylic dianhydride component containing pyromellitic dianhydride, the diamine of following formula (1), and the diamine represented by following formula (2) and (3). A polyamic acid obtained by reacting a diamine component containing at least one diamine selected from the group (hereinafter also referred to as a specific diamine) and an imidized polymer of the polyamic acid (hereinafter also referred to as a single polymer). Characterized in that it contains at least one polymer selected from the group consisting of:

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 a carbon number. 1 to 4 alkyl groups, which may be the same or different.
Examples of the linear alkylene group include 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-dexylene group and the like can be 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 above formula (3), A ₂ is a single bond, —O—, —S—, —NR ₆ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or 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 It is a C1-C4 alkyl group and may be the same or different.

The ester bond is represented by -C (O) O- or -OC (O)-.
As said amide bond, the 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.
As the thioester bond, a structure represented by -C (O) S- or -SC (O)-can be shown.
As the urea bond, a structure represented by -NH-C (O) NH- or -NR-C (O) NR- can be shown. Here, R is an alkyl group having 1 to 4 carbon atoms.

As said carbonate bond, the structure represented by -O-C (O) -O- can be shown.
Examples of the carbamate bond include —NH—C (O) —O—, —O—C (O) —NH—, —NR—C (O) —O—, and —O—C (O) —NR—. The structure represented by can be shown. Here, R is an alkyl group having 1 to 4 carbon atoms.
As said linear alkylene group, the structure similar to the said linear alkylene group can be shown.
As said alkyl group, the structure similar to the said alkyl group can be shown. From the viewpoint of polymerization reactivity, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.

  Note that only the diamine represented by the above formula (1) needs to be reacted with pyromellitic dianhydride in order to exhibit the effects of the present invention. 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 certain ratio. good.

Polymer (A): a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride with a diamine component containing the diamine of the above formula (1), and the polyamic acid At least one polymer selected from imidized polymers;
Polymer (B): obtained by reacting a tetracarboxylic dianhydride component with a diamine component containing at least one diamine selected from the group consisting of the diamines represented by the above formulas (2) and (3) At least one polymer selected from a polyamic acid obtained and an imidized polymer of the polyamic acid.

<Tetracarboxylic dianhydride component>
For at least one polymer selected from the group consisting of a polyamic acid contained in the liquid crystal aligning agent of the present invention and an imidized polymer of the polyamic acid, pyromellitic acid is used as a tetracarboxylic dianhydride. When the ratio of the pyromellitic dianhydride used when obtaining the polyamic acid of this invention and the imidized polymer of this polyamic acid is too small, the effect of this invention will not be acquired. Therefore, in the case of a single polymer, the proportion of pyromellitic dianhydride is preferably 10 to 100 mol%, more preferably 20 to 100 mol%, relative to 1 mol of all tetracarboxylic dianhydrides. More preferably, it is 30 to 100 mol%. In the case of a blend polymer, in the polymer (A), 20 to 100 mol% of the tetracarboxylic dianhydride component is preferably pyromellitic dianhydride, and more preferably 30 to 100 mol%. More preferably, it is 40 to 100 mol%.

  When obtaining the polyamic acid contained in the liquid crystal aligning agent of the present invention and the imidized polymer of the polyamic acid, in addition to pyromellitic dianhydride, tetracarboxylic dianhydride represented by the following formula (17) May be used.

式（１７）において、Ｘは４価の有機基であり、その構造は特に限定されない。具体的例を挙げるならば、下記式（Ｘ−１）〜（Ｘ−４２）の構造の有機基が挙げられる。

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

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 more preferably a hydrogen atom or a methyl group.
From the viewpoint of availability of the compound, the tetracarboxylic dianhydride is preferably at least one selected from the group consisting of tetracarboxylic dianhydrides represented by the following formula (18).

（式（１８）において、Ｘ_１は上記式（Ｘ−１）〜（Ｘ−１３）で表される構造の有機基からなる群から選ばれる少なくとも１種である。）

(In Formula (18), X ₁ is at least one selected from the group consisting of organic groups having a structure represented by Formulas (X-1) to (X-13) above.)

Since the reliability such as the stability of the voltage holding ratio with respect to long-time driving of the obtained liquid crystal alignment film can be further improved, fats such as (X-1) to (X-7) and (X-10) The structure which consists only of group groups is preferable, and the structure represented by (X-1) is more preferable. Furthermore, to show the good liquid crystal alignment property, the structure of _{X 1,} the following formula (X1-1) or (Xl-2) is more preferable.

  When the ratio of the tetracarboxylic dianhydride represented by the above formula (17) used in obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is increased, the effect of the present invention may be impaired. This is not preferable. Therefore, the ratio of the tetracarboxylic dianhydride represented by the above formula (17) is 1 mol of all tetracarboxylic dianhydrides in the polymer (A) in the single polymer and the blend polymer. On the other hand, 0-90 mol% is preferable, More preferably, it is 0-80 mol%, More preferably, it is 0-70 mol%.

<Specific diamine>
When obtaining the polyamic acid which is a polymer which the liquid crystal aligning agent of this invention contains, and the imidation polymer of this polyamic acid, the diamine of said Formula (1), (2) and (3) is used. Even if the ratio of the diamine represented by the above formula (1) is too small or too large, the effect of the present invention cannot be obtained. Therefore, in the case of a single polymer, the proportion of the diamine represented by the above formula (1) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, based on 1 mol of all diamines. More preferably, it is 30-70 mol%. In the case of a blend polymer, the proportion of the diamine represented by the above formula (1) in the polymer (A) is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, based on the total diamine component. More preferably, it is 40-100 mol%.

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

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.
As said linear alkylene group, the structure similar to the said linear alkylene group can be shown.
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.
As said alkyl group, the structure similar to the said alkyl group can be shown. From the viewpoint of polymerization reactivity, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.
As said linear alkylene group, the structure similar to the said linear alkylene group can be shown.
From the viewpoint of liquid crystal alignment and alignment stability and the availability of the compound, the diamine represented by the above formula (2) or (3) is represented by the above formula (6) and the following formulas (11) to (16). It is more preferable that it is at least one selected from the group consisting of diamines represented.

  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 may be too small or too large. The effect of can not be obtained. Therefore, in the case of a single polymer, the proportion of the diamine represented by the above formula (2) or (3) is preferably 10 to 90 mol%, more preferably 20 to 20 mol% with respect to 1 mol of the total diamine. It is 80 mol%, More preferably, it is 30-70 mol%. In the case of a blend polymer, the proportion of the diamine represented by the above formula (1) in the polymer (B) is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, based on the total diamine component. More preferably, it is 40-100 mol%.

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

  Among these, 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, The diamine of Y-76 or Y-79 is more preferable.

  When the ratio of the diamine represented by the above formula (17) used in obtaining the polyamic acid of the present invention and the imidized polymer of the polyamic acid is increased, the effect of the present invention may be impaired. Absent. Therefore, the proportion of the diamine represented by the above formula (17) is preferably 0 to 90 mol% with respect to 1 mol of the total diamine in any case of a single polymer or a blend polymer. Preferably it is 0-70 mol%, More preferably, it is 0-50 mol%.

<Method for producing polyamic acid>
The polyamic acid which is a polyimide precursor used in the present invention can be synthesized by the following method.
Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at −20 to 150 ° C., preferably at 0 to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 12 hours. Can be synthesized.
The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc. in view of the solubility of the monomer and polymer. May be used.

The concentration of the polymer is preferably 1 to 30% by mass and more preferably 5 to 20% by mass from the viewpoint that the polymer is hardly precipitated and a high molecular weight body is easily obtained.
The polyamic acid obtained as described above can be recovered by precipitating a polymer by pouring it into a poor solvent while thoroughly stirring the reaction solution. In addition, by performing precipitation several times, washing with a poor solvent, and then drying at normal temperature or heat, 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, 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.
When manufacturing a polyimide from a polyamic acid, the chemical imidation which adds a catalyst to the solution of the said polyamic acid obtained by reaction of a diamine component and tetracarboxylic dianhydride is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer does not easily decrease during the imidization process.
Chemical imidation 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 an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among these, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated.

  The temperature at which the imidization reaction is performed is -20 to 140 ° C, preferably 0 to 100 ° C, and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times mol of the polyamic acid group, preferably 2 to 20 times mol, and the amount of the acid anhydride is 1 to 50 times mol of the polyamic acid group, preferably 3 to 3 times. 30 moles. The imidation ratio of the resulting 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 imidization reaction of the polyamic acid, the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent. It is preferable to use a liquid crystal aligning agent.
The polyimide solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is carried out several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polymer powder.
Examples of the poor solvent include, but are not limited to, 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 is preferred.

<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 in terms of weight average molecular weight, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000. 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 density | concentration of the polymer of the liquid crystal aligning agent used for this invention can be suitably changed by 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 and defect-free coating film, and is 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 will not be specifically limited if a polymer component melt | dissolves uniformly. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, Examples include 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropanamide and the like. You may use these 1 type or in mixture of 2 or more types. Moreover, even if it is a solvent which cannot melt | dissolve a polymer component uniformly by itself, if it is a range which a polymer does not precipitate, you may mix with said organic solvent.

  The liquid crystal aligning agent used for this invention may contain the solvent for improving the coating-film uniformity at the time of apply | coating a liquid crystal aligning agent to a board | substrate other than the organic solvent for dissolving a polymer component. . As such a solvent, a solvent having a surface tension lower than that of 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, and 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, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate isoa Glycol ester and the like. Two or more of these solvents may be used in combination.

In addition to the above, the liquid crystal aligning agent of the present invention is a polymer other than the polymer necessary for the liquid crystal aligning agent of the present invention, and the dielectric constant and conductivity of the liquid crystal aligning film as long as the effects of the present invention are not impaired. The dielectric or conductive material for the purpose of changing the electrical properties such as the property, the silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate, the hardness and density of the film when the liquid crystal alignment film is made A target crosslinkable compound, and further an imidization accelerator for the purpose of efficiently proceeding imidization of the polyamic acid when the coating film is baked may be added.
In addition, when it is a liquid crystal aligning agent containing a blend type polymer, the preferable mixing ratio of a polymer (A) and a polymer (B) is 10 as a weight ratio of a polymer (A): polymer (B). : Within the range of 90-90: 10, more preferably 20: 80-80: 20.

<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 aligning agent to a substrate, 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 highly transparent substrate, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, or the like can be used. It is preferable to use a substrate on which an ITO electrode or the like for driving is formed from the viewpoint of simplification of the process. In the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum can be used as the electrode.

Examples of the method for applying the liquid crystal aligning agent of the present invention include a spin coating method, a printing method, and an ink jet method. Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent of the present invention. Usually, in order to sufficiently remove the contained organic solvent, the organic solvent is dried at 50 to 120 ° C. for 1 minute to 10 minutes, and then baked at 150 to 300 ° C. for 5 minutes to 120 minutes. Although the thickness of the coating film after baking is not specifically limited, Since the reliability of a liquid crystal display element may fall when too thin, it is 5-300 nm, Preferably it is 10-200 nm.
Examples of a method for aligning the obtained liquid crystal alignment film include a rubbing method and a photo-alignment processing method.

As a specific example of the photo-alignment treatment method, the surface of the coating film is irradiated with radiation deflected in a certain direction, and in some cases, a heat treatment is further performed at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability. Is mentioned. As the 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 liquid crystal orientation, you may irradiate a radiation, heating a coating-film board | substrate at 50-250 degreeC. Dose of the radiation is preferably ^{1~10,000mJ / cm 2, 100~5,000mJ / cm} 2 is particularly preferred. The liquid crystal alignment film produced as described above can stably align liquid crystal molecules in a certain direction.
In the above, the film irradiated with polarized radiation may then be contact-treated with a solvent containing at least one selected from the group consisting of water and organic solvents.

The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves a decomposition product generated by light irradiation. 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, 3- Examples include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate and the like. Two or more of these solvents may be used in combination.
From the viewpoint of versatility and safety, at least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate is more preferable. 1-methoxy-2-propanol or ethyl lactate is particularly preferred.

In the present invention, the contact treatment between the film irradiated with polarized radiation and the solution containing the organic solvent is a treatment such that the film and the liquid are preferably sufficiently in contact with each other, such as immersion treatment or spraying treatment. Done. Especially, the method of immersing a film | membrane in the solution containing an organic solvent, Preferably it is 10 seconds-1 hour, More preferably, it is 1 to 30 minutes is preferable. The contact treatment may be heated at normal temperature, but is preferably performed at 10 to 80 ° C, more preferably at 20 to 50 ° C. Moreover, a means for enhancing contact such as ultrasonic waves can be applied as necessary.
After the above contact treatment, for the purpose of removing the organic solvent in the used solution, either rinsing with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or drying, or both May be done.
Further, the film subjected to the contact treatment with the 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. A higher temperature promotes reorientation of molecular chains. However, if the temperature is too high, molecular chains may be decomposed. Therefore, as heating temperature, 180-250 degreeC is more preferable, and 200-230 degreeC is especially preferable.
If the heating time is too short, the effect of the present invention may not be obtained, and if it is too long, the molecular chain may be decomposed, and therefore it is preferably 10 seconds to 30 minutes, and preferably 1 minute to 10 minutes. Is more preferable.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a horizontal electric field type liquid crystal display element such as an IPS mode or an FFS mode, and is particularly useful as a liquid crystal alignment film of an FFS mode liquid crystal display element.

<Liquid crystal display element>
In the liquid crystal display element of the present invention, after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal aligning agent obtained by the production method of the present invention, a liquid crystal cell is prepared by a known method and the liquid crystal cell is used. Thus, a liquid crystal display element is obtained.
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 as an example. Note that an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.

First, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be ITO electrodes, for example, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover 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 superposed on one substrate so that the alignment film surfaces face each other, and the periphery is bonded with a sealant. In order to control the substrate gap, a spacer is usually mixed in the sealing material. In addition, it is preferable to spray spacers for controlling the substrate gap on the in-plane portion where no sealing material is provided. A part of the sealing material is provided with an opening that can be filled with liquid crystal from the outside.

  Next, a liquid crystal material is injected into a space surrounded by two substrates and the sealing material through an opening provided in the sealing material. Thereafter, the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used. As the liquid crystal material, either a positive liquid crystal material or a negative liquid crystal material may be used. In particular, even when a negative liquid crystal material having a voltage holding ratio lower than that of a positive liquid crystal material is used, if the liquid crystal alignment film of the present invention is used, the afterimage characteristics are excellent. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surfaces 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. Since this liquid crystal display element uses the liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film of the present invention as the liquid crystal alignment film, it has excellent afterimage characteristics, and has a high-definition multifunctional mobile phone ( Smartphones), tablet personal computers, liquid crystal televisions, and the like.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples. Abbreviations in the following are as follows.
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: Butyl cellosolve dianhydride (D-1): Compound represented by the following formula (D-1) Acid dianhydride (D-2): Compound DA-1 represented by the formula (D-2): Compound DA-2 represented by the following formula (DA-1): Compound DA-3 represented by the following formula (DA-2): Compound DA-4 represented by DA-3): Compound represented by the following formula (DA-4)

  The following are methods for measuring viscosity and solid content concentration, liquid crystal cell fabrication, accumulated charge relaxation characteristics, accumulated charge due to asymmetry of positive and negative voltages during AC drive, and evaluation of liquid crystal alignment afterimage by long-term AC drive. .

[Viscosity measurement]
As for the viscosity of the polyamic acid solution, an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) was used, the sample amount was 1.1 mL (milliliter), the cone rotor TE-1 (1 ° 34 ′, R24), and the temperature was 25 ° C. Measured with

[Solid concentration measurement]
Calculation of the solid content concentration of the polyamic acid solution was performed as follows.
Aluminum cup with handle No. About 1.1 g of polyamic acid solution was weighed into 2 (manufactured by ASONE), heated in an oven DNF400 (manufactured by Yamato) at 200 ° C. for 2 hours, and then left at room temperature for 5 minutes to leave the solid content in the aluminum cup. Was weighed. The solid content concentration was calculated from the solid content weight and the original solution weight value.

[Production of liquid crystal cell]
A liquid crystal cell having a configuration of an FFS liquid crystal display element is manufactured.
First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode having a solid pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. A comb-like pixel electrode formed by patterning an IZO film is arranged as a third layer on the second layer SiN film to form two pixels, a first pixel and a second pixel. doing. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

  The pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of electrode elements having a dogleg shape whose central portion is bent. The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is configured by arranging a plurality of bent-shaped electrode elements in the central portion, the shape of each pixel is not rectangular, but the central portion is similar to the electrode element. It has a shape similar to that of a bold-faced koji that bends at Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

  When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film to be described later is used as a reference, in the first region of the pixel, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise), and in the second region of the pixel The electrode elements of the pixel electrode are formed at an angle of −10 ° (clockwise). That is, in the first region and the second region of each pixel, the direction of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode in the substrate plane is It is comprised so that it may become a mutually reverse direction.

  Next, after filtering the obtained liquid crystal aligning agent with a 1.0 micrometer filter, it apply | coated to the prepared said board | substrate with an electrode by spin coat application | coating. After drying on an 80 ° C. hot plate for 5 minutes, baking was performed in a hot air circulation oven at 230 ° C. for 30 minutes to obtain a polyimide film having a thickness of 60 nm. This polyimide film is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation length: 0.3 mm, rubbing direction: inclined by 10 ° with respect to the third layer IZO comb-teeth electrode Then, the substrate was cleaned by irradiating with ultrasonic waves in pure water for 1 minute, and water droplets were removed by air blowing, followed by drying at 80 ° C. for 15 minutes to obtain a substrate with a liquid crystal alignment film. Also, as a counter substrate, a polyimide film is formed on a glass substrate having a columnar spacer with a height of 4 μm on which the ITO electrode is formed on the back surface, and an alignment treatment is performed in the same procedure as above. The obtained substrate with a liquid crystal alignment film was obtained. One set of these two substrates with a liquid crystal alignment film is printed, and the sealant is printed on the substrate leaving the liquid crystal injection port. The other substrate has the liquid crystal alignment film surface facing and the rubbing direction is antiparallel. Then, the sealing agent was cured to produce an empty cell having a cell gap of 4 μm. Liquid crystal MLC-2041 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and left at 23 ° C. overnight before being used for each evaluation.

[Evaluation of relaxation characteristics of accumulated charge]
The liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the pixel electrode and the counter electrode are short-circuited to be at the same potential, and the LED is displayed from under the two polarizing plates. The backlight was irradiated, and the angle of the liquid crystal cell was adjusted so that the luminance of the LED backlight transmitted light to be measured was minimized on the two polarizing plates.
Next, while applying a rectangular wave with a frequency of 30 Hz to this liquid crystal cell, the VT characteristics (voltage-transmittance characteristics) at a temperature of 23 ° C. are measured, and an AC voltage with a relative transmittance of 23% is measured. Calculated.
Next, a rectangular wave with a relative transmittance of 23% and a frequency of 30 Hz was applied for 5 minutes, and then a +1.0 V DC voltage was superimposed and driven for 30 minutes. Thereafter, the DC voltage was turned off, and only a rectangular wave with an AC voltage at a relative transmittance of 23% and a frequency of 30 Hz was applied for 20 minutes.

  The faster the accumulated charge is relaxed, the faster the charge accumulation in the liquid crystal cell when the DC voltage is superimposed. Therefore, the accumulated charge relaxation characteristic is that the relative transmittance immediately after the DC voltage is superimposed is 30% or more. When the relative transmittance decreased to less than 28% by the time 30 minutes passed from the state, the evaluation was defined as “good”. When the relative transmittance did not decrease to less than 28% even after 30 minutes had elapsed since the DC voltage was superimposed, the evaluation was defined as “defective”.

[Evaluation of accumulated charge by asymmetry of positive and negative voltage during AC drive]
The liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the pixel electrode and the counter electrode are short-circuited to be at the same potential, and the LED is displayed from under the two polarizing plates. The angle of the liquid crystal cell was adjusted so that the brightness of the LED backlight transmitted light measured on the two polarizing plates was minimized by irradiating the backlight.
Next, while applying a rectangular wave with a frequency of 30 Hz to the liquid crystal cell, the VT characteristic (voltage-transmittance characteristic) at a temperature of 23 ° C. is measured, and the relative transmittance becomes 23% and 100%. AC voltage was calculated. Thereafter, the pixel electrode and the counter electrode were short-circuited to be at the same potential and left for 60 minutes or more to discharge the charge accumulated in the liquid crystal cell.

  Next, a rectangular wave having an AC voltage with a relative transmittance of 100% and a frequency of 30 Hz was applied for 30 minutes. However, in the 30 minutes, the AC voltage was switched to an AC voltage at which the relative transmittance was 23% only for 20 seconds every 3 minutes. VF characteristics (DC voltage-flicker characteristics) are measured during 20 seconds when the AC voltage is switched to an AC voltage at which the relative transmittance is 23%, and driving is performed at an AC voltage at which the relative transmittance is 100%. The DC voltage value that cancels the accumulated charge due to the asymmetry of the positive and negative voltages was recorded. When the DC voltage value for canceling the accumulated charge changed by 15 mV or more by driving for 30 minutes, it was defined as “defective” and evaluated. When the DC voltage value for canceling the accumulated charge changed by less than 15 mV by driving for 30 minutes, it was defined as “good” and evaluated.

[Evaluation of liquid crystal alignment afterimages by long-term AC drive]
Using the liquid crystal cell, a rectangular wave of ± 5 V was applied for 168 hours at a frequency of 30 Hz in a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited to the same potential, and left as it was at 23 ° C. for 24 hours.
After being left, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal to each other, and the pixel electrode and the counter electrode are short-circuited to have the same potential. The LED backlight was irradiated from below, and the angle of the liquid crystal cell was adjusted so that the luminance of the LED backlight transmitted light measured on the two polarizing plates 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 became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a similar angle Δ was calculated. Then, the average value of the angle Δ values 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, the evaluation was defined as “defective”.

(Synthesis Example 1)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 3.18 g (8.10 mmol) DA-1, 1.98 g (8.10 mmol) DA-2, and 1. DA-3 1. 62 g (10.8 mmol) was weighed, and further 71.2 g of NMP was added, and dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 5.36 g (24.6 mmol) of acid dianhydride (D-1) was added, 17.8 g of NMP was further added, and the mixture was stirred at 23 ° C. for 3 hours in a nitrogen atmosphere to be polyamic. An acid solution (PAA-1) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 247 mPa · s. The solid content concentration of this polyamic acid solution was 11.5% by weight.

(Synthesis Example 2)
In a 100 mL four-necked flask with a stirrer and a nitrogen inlet tube, DA-1 (3.30 g, 8.40 mmol), DA-2 (2.05 g, 8.40 mmol), and DA-3 (1. 68 g (11.2 mmol) was weighed, and 67.8 g of NMP was further added, and dissolved by stirring while feeding 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. 22.6 g of NMP was added, and the mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a 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% by weight.

(Comparative Synthesis Example 1)
In a 50 mL four-necked flask with a stirrer and a nitrogen inlet tube, 1.4-1 (3.60 mmol) of DA-1, 0.88 g (3.60 mmol) of DA-2, and 0.8 of DA-3 were added. 72 g (4.80 mmol) was weighed, and 27.1 g of NMP was further added, and dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 2.16 g (11.0 mmol) of acid dianhydride (D-2) was added, 10.9 g of NMP was further added, and the mixture was stirred at 23 ° C. for 3 hours in a nitrogen atmosphere to be polyamic. An acid solution (PAA-3) was obtained. The viscosity of the 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% by weight.

(Comparative Synthesis Example 2)
In a 100 mL four-necked flask with a stirrer and a nitrogen inlet tube, 2.27 g (9.30 mmol) of DA-2, 1.86 g (12.4 mmol) of DA-3, and 1. 85 g (9.30 mmol) was weighed, 71.2 g of NMP was further added, and the mixture was stirred and dissolved while feeding 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 the mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to be polyamic. An acid solution (PAA-4) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 178 mPa · s. The solid content concentration of this polyamic acid solution was 11.6% by weight.

Example 1
In a 100 mL Erlenmeyer flask containing a stirrer, 15.6 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 4.47 g of NMP, 7.93 g of GBL, 3-glycidoxy 1.78 g of an NMP solution containing 1% by weight of propyltriethoxysilane and 9.91 g of BCS were added and stirred for 2 hours with a magnetic stirrer to obtain a liquid crystal aligning agent (A-1).

(Example 2)
In a 100 mL Erlenmeyer flask containing a stir bar, 15.5 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, 4.41 g of NMP, 7.89 g of GBL, 3-glycidoxy 1.78 g of NMP solution containing 1% by weight of propyltriethoxysilane and 9.86 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-2).

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

(Comparative Example 2)
In a 100 mL Erlenmeyer flask containing a stir bar, 15.4 g of the polyamic acid solution (PAA-4) obtained in Comparative Synthesis Example 2 was collected, 5.21 g of NMP, 7.95 g of GBL, and 3-glycidide. 1.79 g of an NMP solution containing 1% by weight of xylpropyltriethoxysilane and 9.38 g of BCS were added and stirred for 2 hours with a magnetic stirrer to obtain a 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, an IZO electrode having a thickness of 50 nm was formed on the glass substrate as the first layer, and the second layer was insulated. Glass with silicon nitride having a thickness of 500 nm as a film and an FFS electrode having a comb-shaped IZO electrode (electrode width: 3 μm, electrode interval: 6 μm, electrode height: 50 nm) as the third layer The substrate was applied by spin coating. Then, after drying for 5 minutes on an 80 degreeC hotplate, 230 degreeC hot-air circulation type oven performed baking for 30 minutes, and the polyimide film with a film thickness of 60 nm was obtained. This polyimide film is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation length: 0.3 mm, rubbing direction: 10 ° with respect to the third-layer IZO comb-teeth electrode In a tilted direction), the substrate was cleaned by irradiating with ultrasonic waves in pure water for 1 minute to remove water droplets by air blow, and then dried at 80 ° C. for 15 minutes to obtain a substrate with a liquid crystal alignment film. Also, as a counter substrate, a polyimide film is formed on a glass substrate having an ITO electrode on the back surface and having a columnar spacer with a height of 4 μm in the same manner as described above. A substrate with a liquid crystal alignment film was obtained.

One set of these two substrates with a liquid crystal alignment film is printed, and the sealant is printed on the substrate leaving the liquid crystal injection port. The other substrate has the liquid crystal alignment film surface facing and the rubbing direction is antiparallel. Then, the sealing agent was cured to produce an empty cell having a cell gap of 4 μm. Liquid crystal MLC-2041 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, left at 23 ° C. overnight, and used for each evaluation.
As a result of evaluating the relaxation characteristics of the stored charge for this FFS type liquid crystal cell, it was satisfactory. In addition, as a result of evaluating the accumulated charge due to the asymmetry of positive and negative voltages during AC driving, it was good. Moreover, as a result of evaluating the liquid crystal alignment afterimage by long-term alternating current drive, it was favorable.

Example 4
An FFS mode liquid crystal cell was produced in the same manner as in Example 3 except that the liquid crystal aligning agent (A-2) obtained in Example 2 was used. As a result of evaluating the relaxation characteristics of the stored charge for this FFS type liquid crystal cell, it was satisfactory. In addition, as a result of evaluating the accumulated charge due to the asymmetry of positive and negative voltages during AC driving, it was good. Moreover, as a result of evaluating the liquid crystal alignment afterimage by long-term alternating current drive, it was favorable.

(Comparative Example 3)
An FFS mode liquid crystal cell was produced in the same manner as in Example 3 except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 1 was used. The FFS type liquid crystal cell was defective as a result of evaluating the relaxation characteristics of accumulated charges. In addition, as a result of evaluating the accumulated charge due to the asymmetry of positive and negative voltages during AC driving, it was good. Moreover, as a result of evaluating the liquid crystal alignment afterimage by long-term alternating current drive, it was favorable.

(Comparative Example 4)
An FFS mode liquid crystal cell was produced in the same manner as in Example 3 except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 2 was used. As a result of evaluating the relaxation characteristics of the stored charge for this FFS type liquid crystal cell, it was satisfactory. Moreover, as a result of evaluating the accumulated charge due to the asymmetry of positive and negative voltages during AC driving, it was defective. Moreover, as a result of evaluating the liquid crystal alignment afterimage by long-term alternating current drive, it was favorable.

By using the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention, it is possible to suppress charge accumulation due to asymmetry of positive and negative voltages during AC driving, and it is possible to quickly relieve the accumulated charge, and Thus, an IPS driving type or FFS driving type liquid crystal display element having excellent liquid crystal alignment properties and excellent alignment stability and excellent afterimage characteristics can be obtained. In particular, the liquid crystal display element having the liquid crystal alignment film can be used for a multifunctional mobile phone (smart phone), a tablet personal computer, a liquid crystal television, and the like.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2013-206728 filed on October 1, 2013 are incorporated herein as the disclosure of the specification of the present invention. Is.

Claims (12)

At least one 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 polymer selected from the group consisting of a polyamic acid obtained by reacting a diamine component containing diamine and an imidized polymer of the polyamic acid.

(In the 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 1 carbon atom. In formula (3), A ₂ is a single bond, —O—, —S—, —NR ₆ —, ester bond, amide bond, thioester bond, urea bond, carbonate bond, or carbamate. A 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 It is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)   The liquid crystal aligning agent of Claim 1 whose 10-100 mol% of the said tetracarboxylic dianhydride component is pyromellitic dianhydride.   The liquid crystal aligning agent of Claim 1 or 2 whose 10-90 mol% of the said diamine component is the diamine of Formula (1).   The 10-90 mol% of the said diamine component is at least 1 diamine chosen from the group which consists of diamine represented by Formula (2) and (3), The any one of Claims 1-3. Liquid crystal aligning agent. Liquid crystal aligning agent containing the following polymers (A) and (B).
Polymer (A): a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing pyromellitic dianhydride with a diamine component containing the diamine of the above formula (1), and the polyamic acid At least one polymer selected from imidized polymers;
Polymer (B): a polyamic acid obtained by reacting a tetracarboxylic dianhydride component with a diamine component containing at least one diamine selected from the diamines of the above formulas (2) and (3), and the polyamic acid At least one polymer selected from acid imidized polymers;   The liquid crystal aligning agent of Claim 5 whose 20-100 mol% of tetracarboxylic dianhydride components are the pyromellitic dianhydrides in the said polymer (A).   The liquid crystal aligning agent of Claim 5 or 6 whose 20-100 mol% of a diamine component is the diamine of Formula (1) in the said polymer (A).   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 liquid crystal aligning agent of any one of Claims. The diamine of formula (2) is at least one selected from the group consisting of diamines represented by the following formulas (4) to (9), and the diamine of formula (3) is represented by the following formula (10). The liquid crystal aligning agent of any one of Claims 1-8 which is at least 1 sort (s) chosen from the group which consists of diamine.

(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 1 to 4 carbon atoms, and R ₁₀ is a linear alkylene group having 1 to ₁₀ carbon atoms.) The diamine of formula (2) is at least one selected from the group consisting of diamines represented by the above formula (6) and the following formulas (11) to (14), and the diamine of formula (3) is The liquid crystal aligning agent of any one of Claims 1-9 which is at least 1 sort (s) chosen from the group which consists of diamine represented by (15) and (16)).

  The liquid crystal aligning film obtained by apply | coating and baking the liquid crystal aligning agent of any one of Claims 1-10.   A liquid crystal display device comprising the liquid crystal alignment film according to claim 11.