JP2020100822A - Manufacturing method of polyamic acid block polymer, manufacturing method of liquid crystal orientation agent, liquid crystal orientation agent, liquid crystal orientation membrane and liquid crystal display element - Google Patents

Abstract

To provide a manufacturing method of a liquid crystal orientation agent excellent in storage stability at room temperature, in which, even when being stored at room temperature for a long term, obtained characteristic of a liquid crystal orientation membrane and a liquid crystal display element are not lowered.SOLUTION: In a manufacturing method of a polyamic acid block polymer, a solution containing two or more kinds of polyamic acids is heated to 30°C or higher, to thereby carry out an amide exchange reaction. A heating temperature is, for example, 30-100°C. A heating time is, for example, 1-48 hours. The solution containing two or more kinds of polyamic acids is, for example, a solution formed by synthesizing two or more kinds of polyamic acids individually respectively, and thereafter by mixing them.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a polyamic acid block polymer and a method for producing a liquid crystal aligning agent. The present invention also relates to a liquid crystal aligning agent, a liquid crystal aligning film formed using the liquid crystal aligning agent, and a liquid crystal display device having the liquid crystal aligning film.

The liquid crystal alignment film plays an important role in aligning liquid crystals in a liquid crystal display element. At present, a solution (varnish) prepared by dissolving a polyamic acid, a soluble polyimide or a polyamic acid ester in an organic solvent is mainly used for forming the liquid crystal alignment film. The liquid crystal alignment film is a process of applying these varnishes to a substrate to form a coating film, a process of performing orientation treatment to give orientation to the polymer chains forming the film, a process of solidifying the coating film by baking, etc. To be formed. As a method of alignment treatment, a rubbing method of rubbing the surface of the alignment film with a cloth or the like and a photo-alignment method of irradiating the alignment film with linearly polarized ultraviolet rays are known.

With the improvement in image quality of liquid crystal display elements, it has been required for a liquid crystal alignment film to have a plurality of properties such as liquid crystal alignment and electrical properties, which are aligned at a high level. In order to meet such a demand, for example, a method has been proposed in which a plurality of monomers that express different properties are polymerized at one time to form a random polymer. However, in this method, it is known that the liquid crystal orientation and other characteristics such as electric characteristics are likely to be in a trade-off relationship, and it is difficult to arrange the characteristics in parallel (for example, see Patent Document 1).

In order to avoid such a problem, there has been proposed a method of mixing two or more kinds of polyamic acids that are separately polymerized for each composition in order to express different properties (for example, Patent Documents 2 and 3). See.). However, in the liquid crystal aligning agent according to this method, it is known that the polymer composition is averaged by an amide exchange reaction between polyamic acids during storage (for example, see Patent Document 4). As a result, the characteristics of the liquid crystal alignment film formed from the liquid crystal alignment agent immediately after preparation are different from the characteristics of the liquid crystal alignment film formed from the liquid crystal alignment agent after being stored at room temperature for a long time, and a liquid crystal of stable quality is obtained. There was a problem in the production of the alignment film. From such a background, there is a demand for a liquid crystal aligning agent in which liquid crystal aligning properties, electrical properties, and storage stability at room temperature are aligned at a high level.

JP-A-08-043831 JP, 2009-06949, A International Publication No. 2013/161569 International Publication No. 2012/057337

As described in the above background art, when a liquid crystal aligning agent is prepared by mixing two or more kinds of polyamic acids having different properties, there is a problem in storage stability at room temperature. As a method for suppressing the transamidation reaction, there are a method of converting a carboxylic acid in a constitutional unit of the polyamic acid into a polyamic acid ester obtained by converting it into an ester structure, and a method of imidizing the polyamic acid to form a polyimide. These methods require an esterification reaction or an imidization reaction at the stage of producing the liquid crystal aligning agent, and thus have a problem of increasing the production cost. Further, there are problems in the solubility of the polymer and the coatability when the liquid crystal aligning agent is coated on the substrate.
An object of the present invention is to provide a liquid crystal aligning agent containing a polyamic acid block polymer, in which the liquid crystal aligning property of the obtained liquid crystal aligning film, the pretilt angle of the resulting liquid crystal display device, and the afterimage characteristic are retained even after being stored at room temperature for a long time. It is an object of the present invention to provide a liquid crystal aligning agent which does not change and has excellent storage stability at room temperature.

The present inventors take advantage of the fact that polyamic acids having different compositions undergo an amide exchange reaction, and preliminarily cause an amide exchange reaction in the production stage to produce a polyamic acid block polymer that is stable at room temperature (25° C.), and can be used for a long time at room temperature. It has been found that a liquid crystal aligning agent having excellent storage stability at room temperature, in which changes in liquid crystal aligning property and afterimage characteristics are suppressed even when left standing for a long time, is obtained. That is, in the production method of the present invention, a liquid crystal aligning agent having excellent storage stability at room temperature can be obtained by simply heating two or more polyamic acids at 30° C. or higher. Since no reagents for reactions such as esterification reaction and imidization reaction are required, no purification treatment is required, which is advantageous in terms of manufacturing cost and environmental load.
In the production method of the present invention, as will be described later, two or more polyamic acids may be individually produced and then mixed and heated, or after two or more polyamic acids are synthesized in the same reaction vessel. You may heat. The latter case is useful because it can further reduce the manufacturing cost and environmental load.
Furthermore, according to the production method of the present invention, the amide exchange reaction in the production stage does not proceed indefinitely to become a random polymer, maintains certain properties, and is a polyamic acid block excellent in storage stability at room temperature. A polymer is obtained.

The present invention has been proposed on the basis of these findings, and specifically has the following configurations.

[1] A method for producing a polyamic acid block polymer, which comprises heating a solution containing two or more kinds of polyamic acids to 30° C. or higher to cause an amide exchange reaction.
[2] The method for producing a polyamic acid block polymer according to [1], wherein the heating temperature is any one of 30 to 100°C.
[3] The method for producing a polyamic acid block polymer according to [1], wherein the heating temperature is any one of 50 to 100°C.
[4] The method for producing a polyamic acid block polymer according to [1], wherein the heating temperature is 60 to 80°C.
[5] The method for producing a polyamic acid block polymer according to any one of [1] to [4], wherein the heating time is 1 to 48 hours.
[6] The method for producing a polyamic acid block polymer according to any one of [1] to [4], wherein the heating time is 4 to 30 hours.
[7] The method for producing a polyamic acid block polymer according to any one of [1] to [4], wherein the heating time is 5 to 24 hours.
[8] The polyamic acid block according to any one of [1] to [7], wherein the solution containing two or more polyamic acids is a solution obtained by synthesizing two or more polyamic acids individually and then mixed. Method for producing polymer.
[9] A solution containing two or more polyamic acids first synthesizes the first polyamic acid, and then the reaction vessel is charged with diamines and tetracarboxylic acid dianhydride, which are the raw materials of the second polyamic acid. The method for producing a polyamic acid block polymer according to any one of [1] to [7], which is a solution that is introduced and reacted.
[10] A solution containing two or more polyamic acids is ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, propylene glycol monobutyl ether. , Propylene glycol monomethyl ether, or dipropylene glycol monomethyl ether, diisobutyl ketone, 4-methyl-2-pentanol or diisobutylcarbinol, and more preferably ethylene glycol monobutyl ether, ethylene glycol monotert-butyl ether, diethylene glycol methylethyl. The method for producing a polyamic acid block polymer according to any one of [1] to [9], which is a solution containing any one or more selected from the group consisting of ether, diethylene glycol diethyl ether, and propylene glycol monobutyl ether.
[11] A method for producing a liquid crystal aligning agent containing the polyamic acid block polymer produced by the production method according to [1] to [10].
[12] A liquid crystal aligning agent containing the polyamic acid block polymer produced by the production method according to [1] to [10].
[13] A liquid crystal alignment film formed of the liquid crystal alignment agent according to [12].
[14] A liquid crystal display device having the liquid crystal alignment film according to [13].

By using the liquid crystal aligning agent produced by the production method of the present invention, there is no change in the properties of the obtained liquid crystal alignment film even after long-term storage at room temperature, and as a result, a liquid crystal having stable afterimage properties. A display element can be obtained.

It is the figure which compared the molecular weight distribution of the polymer of this invention and the polymer of a comparative example.

Hereinafter, the present invention will be described in detail. The description of the constituent requirements described below may be made based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In the present invention, diamine and dihydrazide may be referred to as “diamines”.

The polyamic acid is a polymer synthesized by a polymerization reaction of a diamine represented by the following formula (DI) and a tetracarboxylic dianhydride represented by the following formula (AN), and represented by the following formula (PAA). Have a structural unit that is A polyimide having a constitutional unit represented by the following formula (PI) can be produced by using a polyamic acid as a precursor and causing a dehydration ring closure reaction in the constitutional unit represented by the formula (PAA).

In formula (AN), formula (PAA) and formula (PI), X ¹ represents a tetravalent organic group. In formula (DI), formula (PAA) and formula (PI), X ² represents a divalent organic group. Regarding the preferred range and specific examples of the tetravalent organic group in X ¹ , the corresponding structure of tetracarboxylic dianhydride having the following photoreactive structure (structure of the part excluding —CO—O—CO—) The preferable range and specific examples thereof and the structure corresponding to the tetracarboxylic acid dianhydride described as the known (non-photosensitive) tetracarboxylic acid dianhydride having no photoreactive structure can be referred to. Regarding the preferred range and specific examples of the divalent organic group in X ² , preferred ranges and specific examples of the corresponding structures (structures of portions excluding —NH ₂ ) of diamines having the following photoreactive structure, and Reference can be made to the corresponding structures of the diamines described as known diamines having no photoreactive structure (non-photosensitive).

Examples of the polyamic acid block polymer in the present invention include a polyamic acid solution (PAA1) having a specific structural unit of a combination of X ¹ and X ^{2 in} the formula (PAA) and (PAA1) in the formula (PAA). Is formed by mixing and heating a polyamic acid solution (PAA2) having different structural units of combinations of X ¹ and X ² , and the block represented by (PAA1) _n1 and the block represented by (PAA2) _n2. Examples include polyamic acid block polymers containing blocks. Here, n1 and n2 are the number of repeating units. N1 and _n2 in (PAA1) _n1 and (PAA2) _n2 are each independently an integer of 1 or more, preferably independently an integer of 2 or more.

The polyamic acid used in the production of the polyamic acid block polymer in the present invention is not particularly limited in its structure as long as it is a polyamic acid, but usually two or more polyamic acids having different compositions are used in order to express different properties. For example, a combination of a polyamic acid for expressing a target pretilt and a polyamic acid for suppressing charge accumulation, a combination of a polyamic acid having a photoreactive structure and a polyamic acid for achieving a high voltage holding ratio are used. Can be mentioned.

As described above, the polyamic acid may be a polymer having a structure of a reaction product of a tetracarboxylic acid dianhydride and a diamine, but other than the tetracarboxylic acid dianhydride and the diamine, other raw materials may be further added. You may use.

The liquid crystal aligning agent containing the polyamic acid block polymer of the present invention can be applied to both an optical alignment method and a rubbing method as an alignment treatment method for forming an alignment film. In the present specification, an alignment agent that uses a photo-alignment method as an alignment treatment method when forming an alignment film is called a liquid crystal alignment agent for photo-alignment, and an alignment film that is formed by using the photo-alignment method as an alignment treatment method is called a photo-alignment film. Sometimes. In this specification, an alignment agent that uses a rubbing method as an alignment treatment method when forming an alignment film may be referred to as a liquid crystal aligning agent for rubbing, and an alignment film that is formed by using the rubbing method as an alignment treatment method may be referred to as a rubbing alignment film. ..

In the present invention, as described above, a polyamic acid having a photoreactive structure may be used. Examples of the photoreactive structure include a photoisomerization structure that causes isomerization by ultraviolet irradiation, a photodecomposition structure that causes decomposition, and a photodimerization structure that causes dimerization. Specifically, for example, a compound having a structure that causes a photoreaction upon irradiation with ultraviolet rays can be appropriately used in the raw material monomer for producing the polyamic acid.

When a coating film of an aligning agent formed of a polymer having a photoreactive structure is irradiated with polarized light for photoalignment as described below, the photoreactive structure of the polymer main chain that is substantially parallel to the polarization direction is selectively A photochemical reaction occurs in the polymer, and the component of the polymer chain that faces a specific direction becomes dominant. This state in which the component of the polymer chain that faces a specific direction is dominant is referred to as the orientation of the polymer chain. When a photo-alignment film formed by firing this coating film is used for a liquid crystal display element, the liquid crystal molecules are aligned with their major axes aligned in a certain direction as a result of the interaction between the surface of the aligned film and the liquid crystal molecules.
For example, in the photolysis reaction, the main chain of the polymer that is substantially parallel to the polarization direction is selectively decomposed, so that the main chain of the polymer that forms the film is almost parallel to the polarization direction of the irradiated light. The component oriented in the perpendicular direction becomes dominant. In the photoisomerization reaction, the photoreactive sites of the polymer, which are roughly parallel to the polarization direction, are selectively isomerized, so that the main chain of the polymer forming the film is aligned with the polarization direction of the irradiated light. Thus, the component that is oriented almost at right angles becomes dominant. In the photodimerization reaction, the chains of the polymer forming the film are cross-linked with respect to the polarization direction of the irradiated light by cross-linking between the polymers that are substantially parallel to the polarization direction in the direction substantially perpendicular to the polarization direction. The components that are oriented almost at right angles become dominant. As a result, in the liquid crystal display device using the photo-alignment film described in the above example, the liquid crystal molecules are aligned with their long axes aligned in the direction perpendicular to the polarization direction of the irradiated light.

In this specification, the state in which the polymer chains forming the alignment film are oriented in a specific direction may be referred to as imparting anisotropy. Further, the fact that the polymer chains are aligned in a specific direction may be expressed as having large anisotropy.

In order to produce a polyamic acid having a photoreactive structure, a diamine having a photoreactive structure or a tetracarboxylic acid dianhydride having a photoreactive structure can be used as a raw material. The diamine having a photoreactive structure and the tetracarboxylic acid dianhydride having a photoreactive structure may be used in combination.

As the photoreactive structure, a photolytic structure represented by the following formula (P-1), a photoisomerization structure represented by formula (P-2) to formula (P-4), and a formula (P-5) to formula (P) The photodimerization structure represented by -7) is mentioned.

式（Ｐ−１）中、Ｒ^６１は独立して、水素原子、炭素数１〜５のアルキル基、またはフェニル基である。式（Ｐ−５）〜（Ｐ−７）中、ベンゼン環の炭素原子に位置が固定されていない結合手は、ベンゼン環における結合手の位置が任意であることを示す。

In formula (P-1), R ⁶¹ is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group. In formulas (P-5) to (P-7), a bond whose position is not fixed to the carbon atom of the benzene ring indicates that the position of the bond on the benzene ring is arbitrary.

Examples of the compound having a photoreactive structure that causes photolysis represented by formula (P-1) include compounds represented by the following formulas (PA-1) and (PA-2).

The compounds represented by the formulas (PA-1) and (PA-2) are liquid crystal aligning agents utilizing liquid crystal aligning ability based on photoisomerization reaction, liquid crystal aligning agents utilizing liquid crystal aligning ability based on photodimerization, Alternatively, when used as a raw material for a liquid crystal aligning agent for rubbing, it can be used as a “tetracarboxylic dianhydride having no photoreactive structure”.

Examples of the compound having a photoreactive structure that causes photoisomerization represented by Formula (P-2) to Formula (P-4) include the following Formula (II-1), Formula (II-2), and Formula (III). -1), formula (III-2), formula (IV-1), formula (IV-2), formula (V-1) to formula (V-3), formula (VI-1), and formula (VI). At least one selected from the group of compounds represented by -2) can be preferably used.

上記各式において、環を構成するいずれかの炭素原子に結合位置が固定されていない基は、その環における結合位置が任意であることを示し、式（Ｖ−２）において、Ｒ^６は独立して−ＣＨ_３、−ＯＣＨ_３、−ＣＦ_３、−ＣＯＯＣＨ_３、下記式（Ｐ１−１）、または下記式（Ｐ１−２）で表される基であり、ａは独立して０〜２の整数であり、式（Ｖ−３）において、環Ａおよび環Ｂはそれぞれ独立して、単環式炭化水素、縮合多環式炭化水素および複素環から選ばれる少なくとも１つであり、Ｒ^１１は、炭素数１〜２０の直鎖アルキレン、−ＣＯＯ−、−ＯＣＯ−、−ＮＨＣＯ−、−ＣＯＮＨ−、−Ｎ（ＣＨ_３）ＣＯ−、または−ＣＯＮ（ＣＨ_３）−であり、Ｒ^１２は、炭素数１〜２０の直鎖アルキレン、−ＣＯＯ−、−ＯＣＯ−、−ＮＨＣＯ−、−ＣＯＮＨ−、−Ｎ（ＣＨ_３）ＣＯ−、または−ＣＯＮ（ＣＨ_３）−であり、Ｒ^１１およびＲ^１２において、直鎖アルキレンの−ＣＨ_２−の１つまたは隣接しない２つは−Ｏ−で置換されてもよく、Ｒ^７〜Ｒ^１０は、それぞれ独立して、−Ｆ、−ＣＨ_３、−ＯＣＨ_３、−ＣＦ_３、または−ＯＨであり、そして、ｂ〜ｅは、それぞれ独立して、０〜４の整数である。

In each of the above formulas, a group in which the bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary, and in formula (V-2), R ⁶ is independent. _-CH 3 _{and, -OCH 3, -CF 3, -COOCH} 3, a group represented by the following formula (P1-1), or the following formula (P1-2), a is independently 0-2 In formula (V-3), ring A and ring B are each independently at least one selected from a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, and a heterocycle, and R ¹¹ Is a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N(CH ₃ )CO—, or —CON(CH ₃ )—, and R ¹² is a straight-chain alkylene having 1 to 20 carbon atoms, -COO -, - OCO -, - NHCO -, - CONH -, - N (CH 3) CO-, or -CON (CH ₃₎ - and ^{is, R 11} In R ¹² and R ¹² , one of —CH ₂ — of the straight-chain alkylene or two non-adjacent ones may be substituted with —O—, and R ^{7 to} R ¹⁰ are each independently —F, —CH _3. , -OCH _3, a -CF ₃ or -OH,, and, b to e are each independently an integer of 0 to 4.

In formulas (P1-1) and (P1-2), R ^{6a to} R ^8a each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted Represents a substituted arylcarbonyl group. R ^{6a to} R ^8a may be the same as or different from each other. * Represents a bonding position to the benzene ring in the formula (V-2).

In formula (P1-1), the alkyl group for R ^6a may be linear, branched, or cyclic. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, further preferably 1 to 4 carbon atoms, and still more preferably 1 to 3 carbon atoms. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 Examples thereof include a methylbutyl group, a 1-ethylpropyl group, a hexyl group, an isohexyl group, a 1-methylpentyl group and a 1-ethylbutyl group.

The alkanoyl group for R ^6a may be linear, branched or cyclic. The alkanoyl group has preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 2 carbon atoms, and even more preferably 1 carbon atom. Specific examples of the alkanoyl group include a methanoyl group, an ethanoyl group, a propanoyl group, an isopropanoyl group, a butanoyl group, an isobutanoyl group, a sec-butanoyl group, a tert-butanoyl group, a pentanoyl group, an isopentanoyl group, a neopentanoyl group, Examples thereof include tert-pentanoyl group, 1-methylbutanoyl group, 1-ethylpropanoyl group, hexanoyl group, isohexanoyl group, 1-methylpentanoyl group, 1-ethylbutanoyl group and the like.

The aryl group of the arylcarbonyl group for R ^6a may be a single ring or a condensed ring. The aryl group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and further preferably 6 to 10 carbon atoms. Specific examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group and the like. Specific examples of the arylcarbonyl group include a phenylcarbonyl group and a 1-naphthylcarbonyl group.

The hydrogen atom on the alkyl group, alkanoyl group and arylcarbonyl group in R ^6a may be independently substituted with a substituent. Examples of the substituent include a hydroxyl group, an amino group, a halogeno group and the like.

Of these, R ^6a is preferably a methyl group, an ethyl group, a propyl group, a hydrogen atom, a methanoyl group, or a phenyl group from the viewpoint that the orientation of the finally manufactured liquid crystal alignment film can be improved.

In formula (P1-2), the alkyl group, alkanoyl group, arylcarbonyl group for R ^7a and R ^8a and the substituents that may be substituted on these groups, the preferred ranges, and the specific examples are described above in formula (P1- Reference can be made to the description, preferred ranges, and specific examples of the alkyl group, alkanoyl group, arylcarbonyl group and the substituents that can be substituted on these groups in R ^6a in 1).

The compounds represented by the formula (V-1), the formula (V-2) and the formula (VI-2) can be particularly preferably used from the viewpoint of photosensitivity. In formula (V-2) and formula (VI-2), compounds in which the bonding positions of two amino groups are both para-positions are preferable. Further, in the formula (V-2), a in the compound in which a=0, and a in the substituent on one benzene ring is 1, a in the substituent on the other benzene ring is 0, and R ⁶ is represented by the formula ( The compound of P1-1) can be more preferably used from the viewpoint of liquid crystal alignment.

Formula (II-1), Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (V-1), Formula The tetracarboxylic acid dianhydride or diamine having a photoreactive structure causing photoisomerization represented by (V-2), formula (V-3), formula (VI-1) and formula (VI-2) is as follows. Formula (II-1-1), Formula (II-2-1), Formula (II-2-2), Formula (III-1-1), Formula (III-2-1), Formula (III-2) -2), formula (IV-1-1), formula (IV-2-1), formula (IV-2-2), formula (V-1-1), formula (V-2-1) to formula (V-2-13), Formula (V-3-1) to Formula (V-3-8), Formula (VI-1-1), or Formula (VI-2-1) to Formula (VI-2). -3).

Among these, by using at least one compound selected from the group consisting of formulas (V-1-1) to (V-3-8), a liquid crystal for photo-alignment having higher sensitivity to ultraviolet irradiation. An aligning agent can be obtained. Formula (V-1-1), Formula (V-2-1), Formula (V-2-4) to Formula (V-2-13), and Formula (V-3-1) to Formula (V- By using at least one compound selected from the group consisting of 3-8), a liquid crystal aligning agent for photo-alignment that can align liquid crystal molecules more uniformly can be obtained. By using at least one compound selected from the group consisting of formula (V-2-12) and formula (V-2-13), the liquid crystal aligning agent for photo-alignment in which the formed photo-alignment film is less colored. Can be obtained.

Above all, when at least one compound selected from the group consisting of formula (V-2-1), formula (V-2-12) and formula (V-2-13) is used, when a photo-alignment film is formed It is preferable to have greater anisotropy because the liquid crystal orientation can be further improved.

The photoisomerization structure may be incorporated in either the main chain or the side chain of the polymer according to the present invention, but by incorporating it in the main chain, it can be suitably used for an in-plane switching mode liquid crystal display device.

The compound having a photoreactive structure that causes photodimerization represented by formula (P-5) to formula (P-7) is a compound represented by formula (PDI-9) to formula (PDI-14) below. Are listed.

式（ＰＤＩ−１２）において、Ｒ^５４は炭素数１〜１０のアルキル基またはアルコキシ基であり、アルキル基またはアルコキシ基上の１つ以上の水素原子はフッ素に置き換えられていてもよい。

In formula (PDI-12), R ⁵⁴ is an alkyl group or alkoxy group having 1 to 10 carbon atoms, and one or more hydrogen atoms on the alkyl group or alkoxy group may be replaced by fluorine.

Among the above compounds, at least one compound selected from the group consisting of formula (PDI-9), formula (PDI-11), and formula (PDI-14) can be preferably used.

As a raw material of the polyamic acid used in the present invention, in addition to the compound having a photoreactive structure described above, it does not have a known photoreactive structure tetracarboxylic dianhydride and a photoreactive structure Diamines can be used. The raw material of the polyamic acid used for the liquid crystal aligning agent for rubbing may be selected from only tetracarboxylic dianhydrides having no photoreactive structure and diamines having no photoreactive structure.

The known (non-photosensitive) tetracarboxylic dianhydride having no photoreactive structure is an aromatic system (including a heteroaromatic ring system) in which a dicarboxylic acid anhydride is directly bonded to an aromatic ring, and an aromatic ring. It may belong to any group of an aliphatic system (including a heterocyclic system) to which a dicarboxylic acid anhydride is not directly bonded. For example, the tetracarboxylic acid dianhydride disclosed in JP-A-2016-029447 and JP-A-2016-041683 can be used. Preferred examples are shown below.

式（ＡＮ−４−１７）において、ｍは１〜１２の整数である。

In the formula (AN-4-17), m is an integer of 1-12.

In the above tetracarboxylic dianhydride which is further used as a raw material for the polyamic acid used, suitable materials for improving the respective properties will be described.

When it is important to improve the liquid crystal alignment, as a raw material of the polymer, the formula (AN-1-13), the formula (AN-4-5), the formula (AN-4-17), or the formula (AN) is used. A compound represented by -4-29) is preferable. In Formula (AN-4-17), m=2 to 12 is preferable, and m=4 and 8 is more preferable.

When importance is attached to improving the transmittance of the liquid crystal display device, the formula (AN-1-1), the formula (AN-3-1), the formula (PA-1) and the formula (AN- 4-30), formula (AN-5-1), formula (AN-7-2), formula (AN-10-1), formula (AN-16-1), formula (AN-16-3), Alternatively, a compound represented by the formula (AN-16-4) is preferable.

When it is important to improve the voltage holding ratio (hereinafter, abbreviated as VHR) of the liquid crystal display device, as the raw material of the polymer, the formula (AN-1-1), the formula (AN-3-1), Formula (PA-1), Formula (AN-4-30), Formula (AN-7-2), Formula (AN-10-1), Formula (AN-16-1), Formula (AN-16-3). ) Or a compound represented by the formula (AN-16-4) is preferable.

Improving the relaxation rate of the residual charge (residual DC) in the alignment film by lowering the volume resistance value of the liquid crystal alignment film is effective as one of the methods for preventing image sticking. When this purpose is emphasized, the formula (AN-1-13), formula (AN-3-2), formula (AN-4-5), formula (AN-4-21), formula ( AN-4-29) or a compound represented by the formula (AN-11-3) is preferable.

As the raw material of the polymer of the present invention, the diamines having no photoreactive structure (non-photosensitive) should be selected from known diamines having no photoreactive structure without limitation. You can For example, diamines disclosed in JP-A-2016-029447 and JP-A-04-041683 can be used. Preferred examples are shown below.

式（ＤＩ−４−２０）および式（ＤＩ−４−２１）において、ｍは１〜１２の整数であり、Ｂｏｃはｔ−ブトキシカルボニル基であり、式（ＤＩ−５−１）、式（ＤＩ−５−１２）、および式（ＤＩ−５−１３）において、ｍは１〜１２の整数であり、そして、式（ＤＩ−７−３）において、ｍは１〜１２の整数であり、ｎはそれぞれ独立して１または２である。式（ＤＩ−５−３０）において、ｋは１〜６の整数であり、式（ＤＩＨ−１−２）において、ｐは１〜１２の整数である。

In formula (DI-4-20) and formula (DI-4-21), m is an integer of 1 to 12, Boc is a t-butoxycarbonyl group, and formula (DI-5-1) and formula (DI-5-1) In DI-5-12) and formula (DI-5-13), m is an integer of 1 to 12, and in formula (DI-7-3), m is an integer of 1 to 12, n is 1 or 2 each independently. In formula (DI-5-30), k is an integer of 1 to 6, and in formula (DIH-1-2), p is an integer of 1 to 12.

In the above-mentioned diamines used as one of the raw materials for the polymer, suitable materials for improving each property will be described.

When it is important to further improve the liquid crystal alignment, among the above-mentioned diamines, the formula (DI-1-3), the formula (DI-4-1), and the formula (DI-4) are used as raw materials for the polymer. -18), formula (DI-4-19), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula A compound represented by formula (DI-5-13), formula (DI-6-7), formula (DI-7-3), formula (DI-11-2) or formula (DIH-1-2). It is preferable to use the compound of formula (DI-4-1), formula (DI-5-1), formula (DI-5-12), formula (DI-5-13) and formula (DI-7-3). The diamine represented is more preferred. In the formula (DI-5-1), m=2, 4 or 6 is preferable, and m=4 is more preferable. In formula (DI-5-12), m=2 to 6 is preferable, and m=5 is more preferable. In Formula (DI-5-13), m=1 or 2 is preferable, and m=1 is more preferable. In the formula (DI-7-3), m=2 or 3, n=1 or 2 is preferable, and m=3 and n=1 is more preferable. In the formula (DIH-1-2), p=4 to 8 is preferable.

When importance is attached to improving the transmittance, as the raw material of the polymer, among the above-mentioned diamines, the formula (DI-1-3), the formula (DI-2-1) and the formula (DI-5-1) are used. ), a compound represented by formula (DI-5-5), or a compound represented by formula (DI-7-3) is preferable, and a diamine represented by (DI-2-1) is more preferable. In formula (DI-5-1), m=2, 4 or 6 is preferable, and m=4 is more preferable. In the formula (DI-7-3), m=2 or 3, n=1 or 2 is preferable, and m=3 and n=1 is more preferable.

When importance is placed on improving the VHR of the liquid crystal display element, as the raw material of the polymer, among the above diamines, the formula (DI-2-1), the formula (DI-4-1), and the formula (DI- 4-2), formula (DI-4-10), formula (DI-4-22), formula (DI-5-1), formula (DI-5-28), formula (DI-5-30), Alternatively, it is preferable to use a compound represented by the formula (DI-13-1), which is represented by the formula (DI-2-1), the formula (DI-5-1), and the formula (DI-13-1). Are more preferred. In the formula (DI-5-1), m=1 is preferable. In the formula (DI-5-30), k=2 is preferable.

Improving the relaxation rate of the residual charge (residual DC) in the alignment film by lowering the volume resistance value of the liquid crystal alignment film is effective as one of the methods for preventing image sticking. When this purpose is emphasized, as the raw material of the polymer, among the above diamines, the formula (DI-4-1), the formula (DI-4-2), the formula (DI-4-10), the formula (DI DI-4-13), formula (DI-4-15), formula (DI-4-20), formula (DI-4-21), formula (DI-5-28), (DI-13-1). Or a compound represented by the formula (DI-16-1) is preferably used, and represented by the formula (DI-4-1), the formula (DI-5-28), or the formula (DI-13-1). Are more preferred.

In each of the diamines, a part of the diamines may be replaced with the monoamine within the range of the monoamine to diamine ratio of 20 mol% or less. By such replacement, it is possible to cause termination of the polymerization reaction when generating the polyamic acid, and to suppress the further progress of the polymerization reaction. Then, the weight average molecular weight of the obtained polyamic acid can be easily controlled, and for example, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. The diamines that can be replaced with monoamines may be one type or two or more types unless the effects of the present invention are impaired. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n- Undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine Are listed.

The polymer of the present invention may further contain a monoisocyanate compound as its raw material. By including the monoisocyanate compound in the raw material, the terminal of the obtained polyamic acid is modified, and the Mw (weight average molecular weight) is adjusted. By using this end-modified polyamic acid, for example, the coating properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. From the above viewpoint, the content of the monoisocyanate compound in the raw material is preferably 1 to 10 mol% with respect to the total amount of the diamines and the tetracarboxylic dianhydride in the raw material. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

In the polyamic acid having a photoreactive structure used in the present invention, in a mode in which diamines having no photoreactive structure and diamines having a photoreactive structure are used in combination, a decrease in sensitivity of the liquid crystal alignment film to light is caused. In order to prevent, it is preferable to use diamines having a photoreactive structure in an amount of 20 to 100 mol %, preferably 70 to 100 mol% with respect to the total amount of diamines used as a raw material for the polyamic acid having a photoreactive structure. Is particularly preferable. Further, two or more (photosensitive) diamines having a photoreactive structure may be used in combination in order to improve the above-mentioned various characteristics such as sensitivity to light and afterimage characteristics. As described above, the embodiment of the present invention includes the case where the total amount of tetracarboxylic dianhydride is occupied by tetracarboxylic dianhydrides having no photoreactive structure (non-photosensitive). However, it is preferable that at least 20 mol% of the total amount of diamines is photosensitive diamines.

The polyamic acid used in the present invention has a (photosensitive) tetracarboxylic dianhydride having a photoreactive structure and a photoreactive structure in order to improve the above-mentioned various characteristics such as sensitivity to light and afterimage characteristics. A (photosensitive) diamine may be used in combination, or two or more of each may be used in combination. As described above, the embodiment of the present invention includes the case where the total amount of the tetracarboxylic dianhydride does not have a photoreactive structure (non-photosensitive). For this reason, it is preferable to use (photosensitive) diamines having a photoreactive structure as the (photosensitive) monomer having a photoreactive structure in an amount of at least 20 mol% of all diamines.

The molar ratio of the tetracarboxylic dianhydride and the diamine in the raw material composition of the polyamic acid used in the present invention can be the same as that in the case of synthesizing a normal polyamic acid. The terminal structure of the polymer can be controlled by arbitrarily changing the molar ratio of the tetracarboxylic dianhydride and the diamine, but the production method of the present invention involves transamidation of two or more polyamic acids. Since it is characterized by forming a block polymer, it is not necessary to intentionally shift the molar ratio of tetracarboxylic dianhydride and diamine in the raw material composition of polyamic acid before heating. Specifically, it is not necessary that one end of the polyamic acid to be mixed has a structure having a carboxylic acid anhydride group and the other end of the polyamic acid has a structure having an amino group.
In the production method of the present invention, the molar ratio of the tetracarboxylic acid and the diamine in the raw material composition of the polyamic acid is preferably 0.9 to 1.1. More preferably, it is 0.99 to 1.01. More preferably, it is 0.991 to 1.009. Particularly preferably, it is 0.999 to 1.001. More preferably, it is equimolar (1.000).
The closer the molar ratio is to equimolar, the more easily the polymerization reaction proceeds, and a polyamic acid having a sufficiently high molecular weight can be obtained. If a polymer having a sufficiently high molecular weight is obtained, it is possible to suppress application defects such as repellency and unevenness when applied to a substrate as an aligning agent. Moreover, since a polyamic acid having a sufficiently high molecular weight can be obtained, even when the reactivity of the monomer constituting the polymer is low, the restriction on the amount of such monomer used can be relaxed.

As described above, the production method of the present invention is characterized in that it is obtained by heating a polyamic acid solution containing two or more polyamic acids to 30° C. or higher and subjecting it to an amide exchange reaction. Is.

In the present invention, when two kinds of polyamic acid solutions are mixed, they can be mixed at an arbitrary ratio, but the ratio may be determined depending on which property of the liquid crystal alignment film is important. In the liquid crystal aligning agent for photo-alignment having a photoreactive structure, the ratio of polyamic acid having a larger number of photoreactive structures is 0.2 to 0 when the total (weight) of two polyamic acids is 1. It is preferable to mix them at a ratio of 0.9, and a ratio of 0.4 to 0.6 is more preferable. When the pretilt angle is important, the ratio of the polyamic acid containing more monomers for controlling the pretilt is 0.2 to 0.9 when the total (weight) of the two polyamic acids is 1. Mixing is preferable, and a ratio of 0.4 to 0.6 is more preferable.

The polyamic acid block polymer of the present invention can be produced, for example, by independently synthesizing two or more kinds of polyamic acids, mixing them, and heating at a temperature of 30° C. or higher. It can also be produced by synthesizing two or more polyamic acids in the same reaction vessel and then heating at a temperature of 30° C. or higher. Specifically, the latter method is to charge the first polyamic acid raw material monomer in one reaction vessel and polymerize the same, and then add the second polyamic acid raw material monomer into the same reaction vessel and polymerize the same. It can be manufactured by heating this at a temperature of 30° C. or higher. More specifically, an organic solvent such as a diamine, a tetracarboxylic dianhydride, and N-methyl-2-pyrrolidone, which are raw material monomers for the first polyamic acid, is charged into one reaction vessel and stirred. After the polymerization, the raw material monomer of the second polyamic acid, diamines, tetracarboxylic acid dianhydride, and, if necessary, an organic solvent such as N-methyl-2-pyrrolidone were charged into the same reaction vessel. , Stir to polymerize. Then, it can manufacture by heating a reaction container at the temperature of 30 degreeC or more. After mixing two or more polyamic acids, or after synthesizing the second polyamic acid, the heating temperature during heating is preferably 30 to 100°C, more preferably 50 to 100°C. More preferably, it is 60 to 80°C.

It is also preferable to add a solvent other than the hydrophilic solvent during heating after mixing two or more kinds of polyamic acid or after synthesizing the second polyamic acid. Examples of the solvent other than the lyophilic solvent include the solvents listed as other solvents for the purpose of improving the coatability described later.
Among these, preferably, ethylene glycol monobutyl ether, ethylene glycol monotert-butyl ether, diethylene glycol monoethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, or di Propylene glycol monomethyl ether, diisobutyl ketone, 4-methyl-2-pentanol or diisobutylcarbinol, more preferably ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, or propylene. Glycol monobutyl ether.
It is preferable to add the poor solvent and heat it, because the amide exchange reaction can be promoted as compared with the case of heating only by using the hydrophilic solvent (for example, NMP). The poor solvent added during heating is preferably 5 to 50% by weight, more preferably 10 to 50% by weight, based on the total amount of the poor solvent and the hydrophilic solvent.

In the method for producing a polyamic acid block polymer of the present invention, the heating time at a temperature of 30° C. or higher is preferably 1 to 48 hours, more preferably 4 to 30 hours, and further preferably 5 to 24 hours. When heating at a low temperature, it is preferable to heat for a long time. When heating at a high temperature, heating for a short time may be used. In the case of heating at 30° C. or higher and lower than 60° C., 1 to 30 hours are preferable, 4 to 30 hours are more preferable, and 8 to 24 hours are further preferable. In the case of heating at 60° C. or higher and 80° C. or lower, 1 hour to 24 hours is preferable, 2 to 12 hours is more preferable, and 2 to 8 hours is further preferable. When heating at 100° C. or higher, 1 to 30 hours is preferable.

A liquid crystal alignment film obtained by producing a liquid crystal alignment agent containing the polyamic acid block polymer of the present invention and then coating the liquid crystal alignment agent on a substrate has excellent liquid crystal alignment properties and afterimage characteristics. Further, the liquid crystal alignment film obtained by applying the liquid crystal aligning agent to the substrate after storing the liquid crystal aligning agent at room temperature for a long time also maintains high values of the liquid crystal aligning property and the afterimage property.

<Oxazine compound>
For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The oxazine compound may be one kind of compound or two or more kinds of compounds. From the above-mentioned purpose, the content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and further preferably 1 to 20% by weight with respect to the polyamic acid. More preferable.

The oxazine compound is soluble in a solvent that dissolves the polyamic acid, and in addition, an oxazine compound having ring-opening polymerizability is preferable. Examples of preferable oxazine compounds include oxazine compounds represented by formula (OX-3-1) and formula (OX-3-9), and oxazine compounds disclosed in JP2013-242526A. it can.

<Oxazoline compound>
For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one kind of compound or two or more kinds of compounds. From the above-mentioned purpose, the content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and further preferably 1 to 20% by weight based on the polyamic acid. Is preferred. Alternatively, the content of the oxazoline compound is preferably 0.1 to 40% by weight based on the polyamic acid when the oxazoline structure in the oxazoline compound is converted into oxazoline.

Examples of the oxazoline compound include the oxazoline compounds disclosed in JP2013-242526A and the like. Preferred oxazoline compounds include 1,3-bis(4,5-dihydro-2-oxazolyl)benzene.

<Epoxy compound>
For example, the liquid crystal aligning agent of the present invention may further contain an epoxy compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display device for a long period of time. The epoxy compound may be one kind of compound or two or more kinds of compounds. From the above-mentioned purpose, the content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and more preferably 1 to 20% by weight with respect to the polyamic acid. Is more preferable.

Examples of the epoxy compound include the epoxy compounds disclosed in JP2013-242526A and the like. Preferred epoxy compounds include N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxy. Examples thereof include silane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and (3,3′,4,4′-diepoxy)bicyclohexyl.

Further, for example, the liquid crystal aligning agent of the present invention may further contain various additives. Examples of various additives include high molecular compounds other than polyamic acid and low molecular compounds, which can be selected and used according to their respective purposes.

For example, examples of the polymer compound other than the polyamic acid include polymer compounds soluble in an organic solvent. It is preferable to add such a polymer compound to the liquid crystal aligning agent of the present invention from the viewpoint of controlling the electrical characteristics and the orientation of the liquid crystal aligning film to be formed. Examples of the polymer compound include polyamide, polyurethane, polyurea, polyester, epoxy resin, polyester polyol, silicone-modified polyurethane, silicone-modified polyester, polyimide, and polyamic acid ester.

Examples of the low molecular weight compound include 1) a surfactant that meets such a purpose when it is desired to improve coatability, 2) an antistatic agent when it is necessary to improve antistatic property, and 3) adhesion to a substrate. A silane coupling agent or a titanium-based coupling agent may be used to improve the properties, and 4) an imidization catalyst may be used to promote imidization at low temperature.

Examples of the silane coupling agent include silane coupling agents disclosed in JP 2013-242526 A and the like. A preferred silane coupling agent is 3-aminopropyltriethoxysilane. Further, examples of the imidization catalyst include the imidization catalyst disclosed in JP2013-242526A.

The amount of the silane coupling agent added is usually 0 to 20% by weight, and preferably 0.1 to 10% by weight, based on the total weight of the polyamic acid.

The imidization catalyst is usually added in an amount of 0.01 to 5 equivalents, preferably 0.05 to 3 equivalents, based on the carbonyl group of the polyamic acid.

The amount of the other additives added varies depending on the application, but is usually 0 to 100% by weight, and preferably 0.1 to 50% by weight, based on the total weight of the polyamic acid.

Further, the liquid crystal aligning agent of the present invention contains a solvent from the viewpoint of adjusting the coating property of the liquid crystal aligning agent and the concentration of the polyamic acid. Examples of the solvent include a hydrophilic solvent having an ability to dissolve a polymer component. As the lyophilic solvent, a wide range of solvents that are normally used in the manufacturing process and application of polymer components such as polyamic acid and soluble polyimide are included, and can be appropriately selected according to the purpose of use. The hydrophilic solvent may be one kind or a mixed solvent of two or more kinds.

Examples of the solvent other than the lyophilic solvent include other solvents for the purpose of improving the coating property of the liquid crystal aligning agent of the present invention.

As the aprotic polar organic solvent which is a hydrophilic solvent for the polyamic acid or its derivative, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropione is used. Examples include amide, N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutyramide, γ-butyrolactone, and γ-valerolactone. ..
Among these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, or γ-valerolactone is preferable.

Examples of other solvents for the purpose of improving coatability include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotertiary butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, and diethylene glycol methyl ethyl ether. And diethylene glycol dialkyl ethers such as diethylene glycol diethyl ether and diethylene glycol butyl methyl ether. Further, propylene glycol monomethyl ether, propylene glycol monoalkyl ether such as propylene glycol monobutyl ether, dipropylene glycol monoalkyl ether such as dipropylene glycol monomethyl ether, ethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, phenyl acetate, and the like. Examples thereof include ester compounds such as acetates. Further, dialkyl malonate such as diethyl malonate, alkyl lactate, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol and diisobutylcarbinol can be mentioned.

Among these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl carbinol, ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl Ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, or dipropylene glycol monomethyl ether are preferred.

The concentration of polyamic acid in the liquid crystal aligning agent of the present invention is preferably 0.1 to 40% by weight. When this aligning agent is applied to the substrate, it may be further diluted with a solvent in order to adjust the film thickness. In the present specification, a state in which the polymer is dissolved in an organic solvent may be referred to as a varnish.

The polymer solid content concentration in the liquid crystal aligning agent of the present invention is not particularly limited, and an optimum value may be selected according to various coating methods described below. Usually, it is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight based on the weight of the varnish in order to suppress unevenness and pinholes during coating.

The viscosity of the liquid crystal aligning agent of the present invention can be adjusted to a preferable range depending on the coating method, the concentration of polyamic acid, the type of polyamic acid used, the type and ratio of the solvent. For example, when applying using a printing machine, it is preferable that the thickness is in the range of 5 to 100 mPa·s because a sufficient film thickness can be obtained and uneven printing can be suppressed, and more preferably 10 to 80 mPa·s. preferable. When applying by spin coating, it is preferably 5 to 200 mPa·s, more preferably 10 to 100 mPa·s. When coating using an inkjet coating device, it is preferably 5 to 50 mPa·s, and more preferably 5 to 20 mPa·s. The viscosity of the liquid crystal aligning agent is measured by a rotational viscosity measuring method, for example, using a rotational viscometer (TVE-20L type manufactured by Toki Sangyo) (measurement temperature: 25° C.).

The liquid crystal aligning agent of the present invention may further contain various additives. As the additive, N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane , 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, isocyanuric acid tris(2,3-epoxy) Propyl), 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or an epoxy compound such as N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(4 ,5-dihydro-2-oxazolyl)benzene and other oxazoline compounds, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, Examples thereof include silane compounds such as paraaminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatepropyltriethoxysilane, and 3-ureidopropyltriethoxysilane. In addition, for example, the descriptions in JP2013-242526A, JP2016-118753A, and the like can be referred to.

<Liquid crystal alignment film>
The liquid crystal aligning agent of the present invention can be applied to both a photo-alignment film using a photo-alignment method as an alignment treatment method and a rubbing alignment film using a rubbing method.
The photo-alignment film of the present invention will be described in detail. The photo-alignment film of the present invention can be obtained by a usual method of producing a photo-alignment film from a photo-alignment liquid crystal aligning agent. The photo-alignment film of the present invention includes, for example, a step of forming a coating film of the liquid crystal aligning agent for photo-alignment of the present invention, a step of heating and drying, a step of irradiating light to impart anisotropy, and a heating and baking step. It can be obtained by going through the process of The photo-alignment film of the present invention may be irradiated with light to give anisotropy after the coating step and heating/drying step, or may be irradiated with light after the heating/baking step to change the optical alignment film. You may give directionality.

The coating film can be formed by applying the liquid crystal aligning agent for photo-alignment of the present invention to a substrate in a liquid crystal display element, as in the production of a normal liquid crystal aligning film. The substrate may be provided with electrodes such as ITO (Indium Tin Oxide), IZO (In ₂ O ₃ —ZnO), IGZO (In—Ga—ZnO ₄ ) electrodes, a color filter, etc., made of glass, made of silicon nitride, Substrates made of acrylic, polycarbonate, polyimide, etc. may be mentioned.

The spinner method, the printing method, the dipping method, the dropping method, the ink jet method and the like are generally known as methods for applying the liquid crystal aligning agent for photo-alignment onto the substrate. These methods are similarly applicable to the present invention.

In the heat drying step, a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, etc. are generally known. The heating and drying step is preferably carried out at a temperature within the range where the solvent can be evaporated, and more preferably at a temperature relatively lower than the temperature in the heating and baking step. Specifically, the heating and drying temperature is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 120°C.

The heating and firing step can be performed under the conditions necessary for the polyamic acid to undergo a dehydration/ring-closing reaction. The baking of the coating film is generally known by a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, and the like. These methods are similarly applicable in the present invention. Generally, it is preferably carried out at a temperature of about 100 to 300° C. for 1 minute to 3 hours, more preferably 120 to 280° C., further preferably 150 to 250° C. In addition, it is possible to perform heating and firing a plurality of times at different temperatures. A plurality of heating devices set to different temperatures may be used, or one heating device may be used while sequentially changing to different temperatures. When the heating and firing are performed twice at different temperatures, it is preferable that the first heating is performed at 90 to 180° C. and the second heating is performed at a temperature of 185° C. or higher. Further, the temperature can be continuously changed from low temperature to high temperature for firing. When firing is performed by continuously changing the temperature, the initial temperature is preferably 90 to 180°C. The final temperature is preferably 185 to 300°C, more preferably 190 to 230°C.

In the method for forming a photo-alignment film of the present invention, a known photo-alignment method is preferably used as a means for imparting anisotropy to a thin film in order to align liquid crystals in one direction with respect to the horizontal and/or vertical directions. be able to.

The method for forming the photo-alignment film of the present invention by the photo-alignment method will be described in detail. The photo-alignment film of the present invention using the photo-alignment method is obtained by heating and drying the coating film, and then imparting anisotropy to the thin film by irradiating it with linearly polarized light or non-polarized light, and baking the film by heating. Can be formed. Alternatively, it can be formed by irradiating the thin film with linearly polarized light or non-polarized light after the coating film is dried by heating and baked. From the viewpoint of orientation, the light irradiation step is preferably performed before the heating and firing step.

Further, in order to enhance the liquid crystal aligning ability of the photo-alignment film, linearly polarized light or non-polarized light may be irradiated while heating the coating film. The irradiation of light may be performed in the step of heating and drying the coating film, or in the step of heating and baking, or may be performed between the heating and drying step and the heating and baking step. The heating and drying temperature in this step is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 120°C. The heating and firing temperature in this step is preferably in the range of 30°C to 300°C, more preferably 50°C to 250°C.

As the light, for example, ultraviolet rays or visible rays containing light with a wavelength of 150 to 800 nm can be used, but ultraviolet rays containing light with a wavelength of 250 to 400 nm are preferable. The light can also be used as linearly polarized light or non-polarized light. The light is not particularly limited as long as it can impart liquid crystal aligning ability to the thin film, but irradiation of linearly polarized light is preferable when it is desired to exert a strong alignment regulating force on the liquid crystal.

The liquid crystal alignment film of the present invention can exhibit a high liquid crystal alignment ability even with low energy light irradiation. Preferably the dose of linearly polarized light in the light irradiation step is 0.05~20J / cm ^2, more preferably 0.5~10J / cm ^2. The wavelength of linearly polarized light is preferably 200 to 400 nm, more preferably 250 to 400 nm. The irradiation angle of the linearly polarized light with respect to the film surface is not particularly limited, but when it is desired to exert a strong alignment regulating force on the liquid crystal, it is preferable to be as perpendicular as possible to the film surface from the viewpoint of shortening the alignment treatment time. Moreover, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating the liquid crystal with the linearly polarized light.

The light with which the film is irradiated when the pretilt angle is desired to be expressed may be linearly polarized light or non-polarized light as described above. Dose of light applied to the film when it is desired to express a pre-tilt angle is preferably from 0.05~20J / cm ^2, particularly preferably 0.5~10J / cm ^2, its wavelength is 250 It is preferably 400 nm, particularly preferably 300 to 380 nm. The irradiation angle of the light for irradiating the thin film with respect to the film surface when the pretilt angle is desired to be expressed is not particularly limited, but is preferably 30 to 60 degrees from the viewpoint of shortening the alignment treatment time.

Light sources used in the process of irradiating linearly polarized light or non-polarized light include ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, deep UV lamp, halogen lamp, metal halide lamp, high power metal halide lamp, xenon lamp, mercury xenon lamp. Excimer lamps, KrF excimer lasers, fluorescent lamps, LED lamps, sodium lamps, microwave-excited electrodeless lamps, etc. can be used without limitation.

The photo-alignment film of the present invention can be suitably obtained by a method further including steps other than the steps described above. For example, the photo-alignment film of the present invention does not require a step of washing the film after baking or light irradiation with a washing liquid, but a washing step can be provided if necessary.

Examples of the cleaning method using a cleaning liquid include brushing, jet spraying, steam cleaning, ultrasonic cleaning and the like. These methods may be used alone or in combination. As the cleaning liquid, pure water or various alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene and xylene, halogen solvents such as methylene chloride, ketones such as acetone and methyl ethyl ketone are used. It can be used, but is not limited thereto. Of course, as these cleaning liquids, those which are sufficiently purified and contain few impurities are used. Such a cleaning method can also be applied to the cleaning step in the formation of the photo-alignment film of the present invention.

In order to enhance the liquid crystal aligning ability of the photo-alignment film of the present invention, an annealing treatment by heat or light can be used before and after the heating/baking step or before and after the polarized or non-polarized light irradiation step. In the annealing treatment, the annealing temperature is 30 to 180° C., preferably 50 to 150° C., and the time is preferably 1 minute to 2 hours. The annealing light used for the annealing treatment may be a UV lamp, a fluorescent lamp, an LED lamp or the like. The light irradiation amount is preferably 0.3 to 10 J/cm ² .

The film thickness of the photo-alignment film of the present invention is not particularly limited, but is preferably 10 to 300 nm, more preferably 30 to 150 nm. The film thickness of the photo-alignment film of the present invention can be measured by a known film thickness measuring device such as a step meter or an ellipsometer.

The photo-alignment film of the present invention is characterized by having a particularly large anisotropy of alignment. The magnitude of such anisotropy can be evaluated by a method using a polarized infrared absorption spectrum (polarized IR) described in JP-A-2005-275364 and the like. It can also be evaluated by a method using ellipsometry as shown below. Specifically, the retardation value of the photo-alignment film can be measured by a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain. That is, a polymer film having a large retardation value has a large degree of alignment, and when used as a liquid crystal alignment film, an alignment film having a larger anisotropy is considered to have a large alignment regulating force with respect to the liquid crystal composition. ..

The photo-alignment film of the present invention can be suitably used for a horizontal electric field type liquid crystal display device. When used in a horizontal electric field type liquid crystal display element, the smaller the pretilt angle and the higher the liquid crystal alignment ability, the higher the black display level in the dark state and the higher the contrast. The pretilt angle is preferably 0.1° or less.

The photo-alignment film of the present invention can be used for controlling the alignment of liquid crystal compositions for liquid crystal displays such as smartphones, tablets, in-vehicle monitors and televisions. It can be used for alignment control of optical compensators and all other liquid crystal materials, in addition to the alignment application of liquid crystal compositions for liquid crystal displays. Further, since the photo-alignment film of the present invention has a large optical anisotropy, it can be used alone as an optical compensator.
When an alignment film is formed from the liquid crystal aligning agent of the present invention by a rubbing method, the method described in International Publication 2019/031604 can be referred to, for example.

<Liquid crystal display element>
The liquid crystal display element of the present invention will be described in detail. According to the present invention, a pair of substrates that are arranged to face each other, an electrode that is formed on one or both of the faces that face each other of the pair of substrates, and a pair of substrates that face each other are formed. A liquid crystal display device having the liquid crystal alignment film formed as described above and a liquid crystal layer formed between the pair of substrates, wherein the liquid crystal alignment film is the alignment film of the present invention.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such an electrode include an ITO film and a metal vapor deposition film. In addition, the electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired patterned shape, for example. Examples of the desired shape of the electrode include a comb shape or a zigzag structure. The electrodes may be formed on one of the pair of substrates, or may be formed on both substrates. The form of formation of electrodes differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element, the electrodes are arranged on one of the pair of substrates, and in the case of other liquid crystal display elements, the pair of substrates is formed. Electrodes are arranged on both sides. The liquid crystal alignment film is formed on the substrate or the electrode.

The liquid crystal layer is formed such that the liquid crystal composition is sandwiched between the pair of substrates whose surfaces on which the liquid crystal alignment film is formed face each other. In the formation of the liquid crystal layer, spacers such as fine particles and a resin sheet that intervene between the pair of substrates and form an appropriate interval can be used as necessary.

As a method of forming the liquid crystal layer, for example, a vacuum injection method or an ODF (One Drop Fill) method can be used. As the sealant used for bonding the substrates, for example, a UV-curable or thermosetting sealant can be used. Screen printing can be used for printing the sealant, for example.

The liquid crystal composition is not particularly limited, and various liquid crystal compositions having a positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions having a positive dielectric anisotropy include JP3086228, JP2635435, JP-A-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP885272A1), and JP Kaihei 9-302346 (EP806466A1), JP-A-8-199168 (EP722998A1), JP-A-9-235552, JP-A-9-2559596, JP-A-9-241643 (EP885271A1), JP-A-10-201416 (EP844229A1), JP-A-10-1041. Liquid crystal compositions disclosed in, for example, -204436, JP-A-10-231482, JP-A-2000-0887040, and JP-A-2001-48822.

Preferred examples of the liquid crystal composition having the negative dielectric anisotropy include JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, and JP-A-8-104869. Kaihei 10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP-A-10-236993, JP-A-10-236994, JP-A-10-237000, JP-A-10-237000. -237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, JP-A-10-237076, JP-A-10-237448 (EP9672661A1), JP-A-10-287874, JP-A-10-287875, and JP-A-10-287875. 10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP-A-2001-072626, JP-A-2001-192657, JP-A-2010-037428, International Publication 2011/ Liquid crystal compositions disclosed in 024666, International Publication 2010/072370, Japanese Patent Publication No. 2010-5370010, JP 2012-077201, JP 2009-084362 and the like can be mentioned. There is no problem in using one or more optically active compounds added to a liquid crystal composition having a positive or negative dielectric anisotropy.

In addition, for example, the liquid crystal composition used for the liquid crystal display element of the present invention may further contain an additive from the viewpoint of improving the orientation, for example. Such additives are photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators, polymerization inhibitors and the like. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators and polymerization inhibitors are compounds disclosed in WO 2015/146330. Are listed.

A polymerizable compound may be mixed with the liquid crystal composition in order to adapt to a liquid crystal display device of PSA (polymer sustained alignment) mode. Preferred examples of the polymerizable compound are compounds having a polymerizable group such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxirane, oxetane) and vinyl ketone. Preferred compounds include compounds disclosed in WO 2015/146330 and the like.

Hereinafter, the present invention will be described with reference to examples. The evaluation methods and compounds used in the examples are as follows.

<Evaluation method>

1. Weight average molecular weight (Mw)
The weight average molecular weight of the polyamic acid was measured by the GPC method using a 2695 Separation Module/2414 differential refractometer (manufactured by Waters) and determined by converting to polystyrene. The obtained polyamic acid was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100: weight ratio) so that the polyamic acid concentration was about 2% by weight. As the column, HSPgel RT MB-M (manufactured by Waters) was used, and the mixed solution was used as a developing agent, and the measurement was performed at a column temperature of 50° C. and a flow rate of 0.40 mL/min. As the standard polystyrene, TSK standard polystyrene manufactured by Tosoh Corporation was used.
2. AC afterimage measurement The luminance-voltage characteristics (BV characteristics) of the liquid crystal display element described later were measured. This is defined as the brightness-voltage characteristic before stress application: B(before). Next, an alternating current of 5.5 V and 30 Hz was applied to the device for 20 minutes, then short-circuited for 1 second, and the luminance-voltage characteristic (B-V characteristic) was measured again. This is defined as the brightness-voltage characteristic after stress application: B (after). Based on these values, the brightness change rate ΔB (%) is

ΔB(%)=[[B(after)−B(before)]/B(before)]×100 (Equation 1)

It estimated using the formula of. These measurements were performed with reference to the pamphlet of International Publication No. 2000/43833. It can be said that the smaller the value of ΔB (%) at a voltage of 1.35 V, the more the generation of AC afterimage that occurs due to the orientation can be suppressed, and it can be said to be a usable level at less than 10.0%.
It can also be said that the better the afterimage characteristic, the better the orientation.

3. Pretilt angle (Pt angle)
It was measured at room temperature with a liquid crystal evaluation device (OMS-CA3) manufactured by Chuo Seiki Co., Ltd.

<Tetracarboxylic acid dianhydride>

<Diamine>

<Solvent>
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)
BP: Propylene glycol monobutyl ether EDM: Diethylene glycol ethyl methyl ether

[Synthesis example 1]
[First-stage polymerization]
A 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet was charged with 0.9514 g of the compound represented by the formula (DI-4-1) and 20.0 g of dehydrated NMP, and dried. It was dissolved under stirring in a nitrogen stream. Next, 1.7254 g of the compound represented by the formula (PA-1) and 10.0 g of dehydrated NMP were added, and stirring was continued at room temperature for 6 hours to obtain a solution of the first polyamic acid. When this reaction solution was sampled and the Mw of the polyamic acid produced by the above method was measured, the Mw of the first polyamic acid was 90,000.
[Second-stage polymerization]
In a flask in which the first-stage polymerization was performed, 1.2449 g of the compound represented by the formula (V-2-1), 0.2905 g of the compound represented by the formula (AN-1-1), and formula (AN-4). -17, m=8) of the compound represented by 1.778 g and dehydrated NMP of 34.0 g were added, and stirring was continued at room temperature for 24 hours to obtain a mixed solution of the first polyamic acid and the second polyamic acid. When this reaction solution was sampled and Mw was measured by the above method, peaks were confirmed on the high molecular weight side (Mw: around 90,000) and the low molecular weight side (Mw: around 30,000). The Mw of the second polyamic acid was estimated to be about 30,000. BC (30.0 g) was added to this reaction solution, and the mixture was stirred for 8 hours while heating at 60°C to obtain a polyamic acid block polymer solution having a polymer solid content concentration of 6% by weight. This polyamic acid block polymer solution is called varnish A1.

[Synthesis example 2]
A varnish A2 having a polymer solid content concentration of 6% by weight was prepared according to Synthesis Example 1 except that the combination of tetracarboxylic dianhydride and diamine was changed to those shown in Table 1.

[Synthesis example 3]
[First-stage polymerization]
A 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet was charged with 1.0139 g of the compound represented by the formula (DI-4-1) and 20.0 g of dehydrated NMP, and dried. It was dissolved under stirring in a nitrogen stream. Next, 1.8389 g of the compound represented by the formula (PA-1) and 10.0 g of dehydrated NMP were added, and stirring was continued at room temperature for 3 hours to obtain a solution of the first polyamic acid.
[Second-stage polymerization]
In a flask subjected to the first-stage polymerization, 1.3267 g of the compound represented by the formula (V-2-1), 0.3096 g of the compound represented by the formula (AN-1-1), and the formula (AN-4). -17, m=2) of the compound (1.5108 g) and dehydrated NMP (34.0 g) were added, and stirring was continued at room temperature for 24 hours to obtain a mixed solution of the first polyamic acid and the second polyamic acid. BC (30.0 g) was added to this reaction solution, and the mixture was stirred for 24 hours while heating at 30° C. to obtain a polyamic acid block polymer solution having a polymer solid content concentration of 6% by weight. This polyamic acid block polymer solution is called varnish A3.

[Synthesis example 4]
[First-stage polymerization]
In a 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet, 0.4257 g of a compound represented by the formula (DI-4-1), a formula (DI-13-1). 1.0564 g of the compound represented by and 20.0 g of dehydrated NMP were added, and the mixture was stirred and dissolved under a stream of dry nitrogen. Next, 1.5440 g of the compound represented by the formula (PA-1) and 10.0 g of dehydrated NMP were added, and stirring was continued at room temperature for 3 hours to obtain a solution of the first polyamic acid.
[Second-stage polymerization]
1.1140 g of a compound represented by the formula (V-2-1), 1.5999 g of a compound represented by the formula (AN-4-17, m=8), a formula 0.2600 g of the compound represented by (AN-1-1) and 34.0 g of dehydrated NMP were added, and stirring was continued at room temperature for 24 hours to obtain a mixed solution of the first polyamic acid and the second polyamic acid. BP (15.0 g) and EDM (15.0 g) were added to this reaction solution, and the mixture was stirred for 12 hours while heating at 40°C to obtain a polyamic acid block polymer solution having a polymer solid content concentration of 6% by weight. This polyamic acid block polymer solution is called varnish A4.

[Synthesis example 5]
A varnish A5 having a polymer solid content concentration of 6% by weight was prepared according to Synthesis Example 4 except that the combination of tetracarboxylic dianhydride and diamine was changed to the combination shown in Table 1.

[Synthesis example 6]
[First-stage polymerization]
A 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet was charged with 0.9028 g of the compound represented by the formula (DI-4-1) and 20.0 g of dehydrated NMP, and dried. It was dissolved under stirring in a nitrogen stream. Then, 1.0915 g of the compound represented by the formula (PA-1), 0.5513 g of the compound represented by the formula (AN-1-1), and 10.0 g of dehydrated NMP are added, and stirring is continued at room temperature for 3 hours. A solution of the first polyamic acid was obtained.
[Second-stage polymerization]
1.5046 g of the compound represented by the formula (V-2-13), 1.9498 g of the compound represented by the formula (AN-4-17, m=4), and Dehydrated NMP (34.0 g) was added and stirring was continued at room temperature for 24 hours to obtain a mixed solution of the first polyamic acid and the second polyamic acid. BC (30.0 g) was added to this reaction solution, and the mixture was stirred for 4 hours while heating at 80°C to obtain a polyamic acid block polymer solution having a polymer solid content concentration of 6% by weight. This polyamic acid block polymer solution is called varnish A6.

[Synthesis example 7]
Varnish A7 having a polymer solid content concentration of 6% by weight was prepared according to Synthesis Example 6 except that the combination of tetracarboxylic dianhydride and diamine was changed to the combination shown in Table 1.

Table 1 shows the diamine used in Synthesis Examples 1 to 7, the tetracarboxylic dianhydride, the molar ratio thereof, and the heating temperature and heating time during varnish synthesis.

表１において、［］内の数値は各モノマーのモル比を表す。

In Table 1, the numerical value in [] represents the molar ratio of each monomer.

[Example 1] Preparation of liquid crystal aligning agent, preparation of FFS liquid crystal display device and measurement of AC afterimage 10.0 g of varnish A1 was weighed in a 50 mL round-bottomed flask, and 5.0 g of N-methyl-2-pyrrolidone and butyl cellosolve 5. 0 g was added and the mixture was stirred at room temperature for 1 hour to obtain a liquid crystal aligning agent B1 having a resin content concentration of 3% by weight. The prepared liquid crystal aligning agent B1 was dispensed into a brown bottle and stored at room temperature for 7 days. This stored liquid crystal aligning agent was designated as liquid crystal aligning agent B1′. The liquid crystal aligning agent B1 was applied to the substrate with the SiNx/ITO comb-teeth electrode and the opposite substrate by a spinner. The alignment film formed was applied so as to have the following film thickness. After coating, it was heated and dried at 60° C. for 80 seconds on a hot plate (EC hot plate (EC-1200N, manufactured by As One Co., Ltd.)). Then, using Ushio Denki Co., Ltd. Multi Light ML-501C/B, the substrate was irradiated with linearly polarized ultraviolet rays from the vertical direction through a polarizing plate. The exposure energy at this time is 2.0±0.1 J/cm ² at a wavelength of 365 nm by measuring the light amount using a UVT photometer UIT-150 (light receiver UVD-S365) manufactured by USHIO INC. So that the exposure time was adjusted. Then, it heat-processed at 230 degreeC for 15 minutes in a clean oven (Espec Co., Ltd. PVHC-231), and formed the photo-alignment film with a film thickness of 100±10 nm. Further, a liquid crystal aligning agent B1′ was used instead of the liquid crystal aligning agent B1, and a substrate on which a photo-alignment film was formed was prepared in the same manner as B1.

A substrate with a SiNx/ITO comb-tooth electrode on which a photo-alignment film was formed using the liquid crystal aligning agent B1 and a counter-side substrate were prepared, and a sealant was applied to the surface on which the photo-alignment film was formed. In each of the substrates, the surfaces on which the photo-alignment film was formed are made to face each other so that the polarization directions of the irradiated ultraviolet rays are parallel to each other, and a space for injecting the liquid crystal composition is provided and the substrates are bonded to each other. An empty FFS cell was prepared. The negative type liquid crystal composition A was vacuum-injected into the prepared empty FFS cell to prepare an FFS liquid crystal display element 1.
<Negative liquid crystal composition A>

物性値：ＮＩ ７５．７℃； Δε −４．１； Δｎ ０．１０１； η １４．５ｍＰａ・ｓ．

Physical property value: NI 75.7° C.; Δε-4.1; Δn 0.101; η 14.5 mPa·s.

When AC afterimage was measured using the manufactured FFS liquid crystal display element 1, ΔB at 1.35 V was 1.5%. This value was used as the afterimage value before storage. Similarly, with the liquid crystal aligning agent B1′, when an FFS liquid crystal display element 1′ was prepared and subjected to AC afterimage measurement, ΔB at 1.35 V was 1.5%. This value was used as the afterimage value after storage. The rate of change in afterimage characteristics before and after storage was obtained from the following equation (Equation 2).
(Formula 2);
Afterimage characteristic change rate (%)=[(afterimage value after storage−afterimage value before storage)/afterimage value before storage]×100
When the afterimage characteristic change rate is less than 30%, the storage stability at room temperature is good, and when it is less than 10%, it is particularly good. The rate of change in afterimage characteristics of this example was 0.0%, which was particularly good.

[Examples 2 to 6]
Liquid crystal aligning agents B2 to B6 and liquid crystal aligning agents B2' to B6' were prepared according to the method shown in Example 1 except that the varnish used was changed from A1 to A2 to A6. Specifically, using varnishes A2 to A6, N-methyl-2-pyrrolidone and butyl cellosolve were added in the same manner as in Example 1 to obtain liquid crystal aligning agents B2 to B6 having a resin content concentration of 3% by weight. Further, B2 to B6 were separated into brown bottles and stored at room temperature for 7 days to obtain liquid crystal aligning agents B2' to B6'. An FFS liquid crystal display element was manufactured according to Example 1 using B2 to B6 and B2′ to B6′, and AC afterimage was measured to obtain the afterimage characteristic change rate.
Table 2 shows the relationship between the varnishes A2 to A6, the liquid crystal aligning agents B2 to B6 prepared by diluting them with a solvent, and B2′ to B6′ stored at room temperature.

[Example 7]
Preparation of liquid crystal alignment agent, preparation of FFS liquid crystal display element, measurement of AC afterimage, preparation of liquid crystal cell for pretilt angle measurement, and varnish synthesized in Synthesis Example 7 in a 50 mL eggplant flask equipped with a pretilt angle measurement stirring blade and a nitrogen introducing tube. 10.0 g of A7 was weighed, 5.0 g of N-methyl-2-pyrrolidone and 5.0 g of butyl cellosolve were added thereto, and the mixture was stirred at room temperature for 1 hour to obtain a liquid crystal aligning agent B7 having a resin content concentration of 3% by weight. Further, the prepared liquid crystal aligning agent B7 was dispensed into a brown bottle and stored at room temperature for 7 days. This stored liquid crystal aligning agent is referred to as liquid crystal aligning agent B7'. This liquid crystal aligning agent B7 was applied to a glass substrate with an FFS electrode and a glass substrate with a column spacer by a spinner method (2,000 rpm, 15 seconds). After coating, pre-baking was performed at 80° C. for about 3 minutes, and then baking was performed at 230° C. for 30 minutes to form a liquid crystal alignment film having a film thickness of about 100 nm. The obtained liquid crystal alignment film was rubbed with a rubbing treatment apparatus manufactured by Iinuma Gauge Manufacturing Co., Ltd., with a rubbing cloth (foot length 2.8 mm: cotton) pushing amount of hair of 0.40 mm, stage moving speed of 20 mm/sec, The rubbing treatment was performed under the condition that the roller rotation speed was 1000 rpm. The surface of the obtained substrate was washed with ultrapure water and then dried in an oven at 120° C. for 30 minutes. Next, the two substrates on which the liquid crystal alignment film is formed are made to face each other with the surfaces on which the liquid crystal alignment film is formed, and a space for injecting a liquid crystal composition is provided between the opposed liquid crystal alignment films. Pasted together. At this time, the rubbing directions of the respective liquid crystal alignment films were made parallel to each other. The negative type liquid crystal composition A was vacuum-injected into these cells, and the injection port was sealed with a photo-curing agent to prepare a liquid crystal cell (liquid crystal display element) having a cell thickness of 4 μm. When an AC afterimage was measured, ΔB at 1.35 V was 2.0%. The pretilt angle was 2.3°. Similarly, with the liquid crystal aligning agent B7′, an FFS liquid crystal display device was prepared and subjected to AC afterimage measurement. As a result, ΔB at 1.35 V was 2.1%. The pretilt angle was 2.3°. The rate of change of the pretilt angle before and after storage was obtained from the following formula (Formula 3).
(Formula 3);
Pretilt angle change rate (%)=[(pretilt angle after saving−pretilt angle before saving)/pretilt angle before saving]×100
When the pretilt angle change rate is less than 30%, the storage stability at room temperature is good, and when it is less than 10%, it is particularly good. The pretilt angle change rate in this example was 0.0%, which was particularly good.

[Comparative Example 1]
[Synthesis of First Polyamic Acid]
A 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet was charged with 0.9514 g of the compound represented by the formula (DI-4-1) and 20.0 g of dehydrated NMP, and dried. It was dissolved under stirring in a nitrogen stream. Next, 1.7254 g of the compound represented by the formula (PA-1) and 10.0 g of dehydrated NMP were added, and stirring was continued at room temperature for 6 hours. Then, 11.94 g of BC was added and stirred until uniform, to obtain a polyamic acid solution having a polymer solid content concentration of 6 wt %. When this reaction solution was collected and the Mw of the polyamic acid produced by the above method was measured, the Mw was 90,000. This polyamic acid solution is called varnish CA1. The raw material composition of the varnish CA1 is the same as the raw material composition of the first polyamic acid in Example 1.
[Synthesis of Second Polyamic Acid]
Separately from the above, in a 200 mL brown four-necked flask equipped with a thermometer, a stirrer, a raw material charging inlet and a nitrogen gas inlet, 1.2449 g of the compound represented by the formula (V-2-1) and dehydrated NMP20. 0 g was added, and the mixture was dissolved with stirring under a stream of dry nitrogen. Next, 0.2905 g of the compound represented by the formula (AN-1-1), 1.7787 g of the compound represented by the formula (AN-4-17, m=8), and 14.0 g of dehydrated NMP were added, and the mixture was stirred at room temperature. Stirring was continued for 24 hours. Then, 18.06 g of BC was added and stirred until it became uniform to obtain a polyamic acid solution having a polymer solid content concentration of 6 wt %. When this reaction solution was sampled and the Mw produced by the above method was measured by the above method, the Mw was 30,000. This polyamic acid solution is called varnish CB1. The raw material composition of the varnish CB1 is the same as the raw material composition of the second polyamic acid in Example 1.
[Preparation of liquid crystal aligning agent]
Varnish C1 was obtained by mixing varnish CA1 and varnish CB1 at a weight ratio of the solution of varnish CA1:varnish CB1=6:4. This varnish C1 is a varnish that has not been heat-treated after mixing. 10.0 g of varnish C1 was weighed in a 50 mL eggplant flask, 5.0 g of N-methyl-2-pyrrolidone and 5.0 g of butyl cellosolve were added thereto, and the mixture was stirred at room temperature for 1 hour to prepare a liquid crystal aligning agent C1 having a resin content of 3% by weight. Got Further, the prepared liquid crystal aligning agent C1 was dispensed into a brown bottle and stored at room temperature for 7 days. This stored liquid crystal aligning agent was designated as liquid crystal aligning agent C1′.
[Measurement of physical properties]
Using the liquid crystal aligning agent C1 and the liquid crystal aligning agent C1′, respectively, an FFS liquid crystal display device was manufactured according to Example 1 and subjected to AC afterimage measurement to determine the afterimage characteristic change rate.

[Comparative Examples 2 to 7]
A first polyamic acid (varnishes CA2 to CA7) and a second polyamic acid (varnishes CB2 to CB7) were synthesized according to the method shown in Comparative Example 1 except that the raw materials used and the composition ratio were changed. did. Here, the raw material composition of the varnishes CA2 to CA7 is the same as the raw material composition of the first polyamic acid in Examples 2 to 7, respectively, and the raw material composition of the varnishes CB2 to CB7 is the same as that of the second polyamic acid in Examples 2 to 7, respectively. It is the same as the raw material composition of the polyamic acid.
A liquid crystal aligning agent C2 to C7 and a liquid crystal thereof stored at room temperature for 7 days in accordance with the method shown in Comparative Example 1 except that the varnish used was changed from CA1 and CB1 to CA2 to CA7 and CB2 to CB7. Orienting agents C2' to C7' were prepared. Specifically, varnishes CA2 to CA7 and CB2 to CB7 were used and mixed in the same manner as in Comparative Example 1 to obtain varnishes C2 to C7. These varnishes are varnishes that have not been heat-treated after mixing. Then, in accordance with Comparative Example 1, liquid crystal aligning agents C2 to C7 were prepared from the varnishes C2 to C7, and the prepared liquid crystal aligning agents C2 to C7 were fractionated in a brown bottle and stored at room temperature for 7 days, and the liquid crystal Alignment agents C2' to C7' were obtained.
Table 3 shows the relationship between the polyamic acid solutions (CA1 to CA7, CB1 to CB7) synthesized in Comparative Examples 1 to 7 and the polyamic acid solutions (C1 to C7) prepared by mixing these.

液晶配向剤Ｃ２〜Ｃ６および液晶配向剤Ｃ２’〜Ｃ６’を用いて、比較例１に準拠してＦＦＳ液晶表示素子を作製し、ＡＣ残像測定を行い、残像特性変化率を求めた。
液晶配向剤Ｃ７および液晶配向剤Ｃ７’を用いて、実施例７に準拠してＦＦＳ液晶表示素子を作製し、ＡＣ残像測定およびプレチルト角測定を行い、残像特性変化率およびプレチルト角変化率を求めた。

実施例１〜７、及び比較例１〜７の結果を併せて、表４に示す。

Using the liquid crystal aligning agents C2 to C6 and the liquid crystal aligning agents C2′ to C6′, an FFS liquid crystal display element was produced according to Comparative Example 1, and AC afterimage measurement was performed to obtain the afterimage characteristic change rate.
Using liquid crystal aligning agent C7 and liquid crystal aligning agent C7′, an FFS liquid crystal display device was manufactured according to Example 7, and AC afterimage measurement and pretilt angle measurement were performed to obtain the afterimage characteristic change rate and the pretilt angle change rate. It was

The results of Examples 1 to 7 and Comparative Examples 1 to 7 are shown together in Table 4.

In Examples 1 to 7, both the AC afterimage change rate and the pretilt angle change rate of liquid crystal display devices produced using the liquid crystal aligning agent containing the polyamic acid block polymer of the present invention were very small values of 0 to 5%. Became. That is, it was found that the storage stability of the liquid crystal aligning agent at room temperature was good. On the other hand, in Comparative Examples 1 to 7, the AC afterimage change rate was 63 to 120%, and in Comparative Example 7, the pretilt angle change rate was 41%, which was a high change rate, and the storage stability at room temperature was poor. Do you get it.
Further, in producing the polyamic acid block polymer of the present invention, even if the heating temperature is produced under the temperature condition of 30 to 80° C., the AC afterimage change rate and the pretilt angle change rate are both 0 to 5%, which are very high. The value was small, and it was found that the liquid crystal aligning agent had good storage stability at room temperature. Since good results were obtained even under a wide heating temperature condition of 30 to 80° C., even if the viscosity of the varnish, that is, the Mw of the polymer was adjusted in a wide temperature range, the storage stability at room temperature was high. It has been found that a good liquid crystal aligning agent can be produced. This also means that, in the raw material used for the polyamic acid in the present invention, even a polyamic acid having a high Mw synthesized using a monomer having good reactivity is a polyamic acid having a low Mw synthesized using a monomer having poor reactivity. However, it means usefulness and means that monomers having different reactivity can be used without limitation.

Here, the GPC (gel permeation chromatography) spectra of the polyamic acid block polymer solution (varnish A1) prepared in Synthesis Example 1 and the mixed solution (varnish C1) of varnishes CA1 and CB1 prepared in Comparative Example 1 are shown in FIG. Show. The UV-visible detector (365 nm) of GPC can confirm the spectrum of the polymer having an absorption at 365 nm, that is, the spectrum of the polymer using a raw material having an azo group as represented by formula (V-2-1). Can be confirmed. In Synthesis Example 1, spectra are shown before heating, 3 hours after the heating temperature reaches 80° C., and 10 hours after the heating temperature reaches 80° C., respectively. The spectrum of the varnish prepared in Comparative Example 1 (varnish C1) is also shown.

In Comparative Example 1, since heating was not performed after mixing two kinds of polyamic acid in FIG. 1, it is considered that the transamidation reaction did not occur, and one peak could be simply confirmed. This peak is an absorption derived from the formula (V-2-1). In Synthesis Example 1, after the synthesis of the second polyamic acid and before heating, when compared with the spectrum of the comparative example, the retention time of the main peak is almost unchanged, but it spreads to the left, and the shoulder peak on the high molecular weight side. I found out that. It was found that the change was remarkable in the spectrum after heating for 3 hours at 80° C. and the spectrum after heating for 10 hours at 80° C., and the area on the high molecular weight side increased. The Mw of the first polyamic acid in Synthesis Example 1 is about 90,000, and the Mw of the second polyamic acid is about 30,000, which means that the first polyamic acid has a larger Mw. The Mw of the second polyamic acid, that is, the polyamic acid having a structure derived from the formula (V-2-1) is shifted to the higher molecular weight side because the structure derived from the formula (V-2-1) is It can be said that the high molecular weight polymer is incorporated into the first polyamic acid, that is, it means that the transamidation reaction proceeds and the polyamic acid block polymer is synthesized.

From the results of the examples, in the liquid crystal display device having the photo-alignment film and the rubbing alignment film formed by using the liquid crystal aligning agent containing the polyamic acid block polymer of the present invention, before and after storage at room temperature as compared with Comparative Example. It was found that the rate of change in afterimage characteristics was significantly reduced, and in the liquid crystal display device having the rubbing alignment film, the rate of change in pretilt angle before and after storage at room temperature was significantly reduced. The liquid crystal aligning agent containing the polyamic acid block polymer according to the production method of the present invention showed good storage stability at room temperature.

The liquid crystal aligning agent containing the polyamic acid block polymer according to the production method of the present invention can reduce the deterioration of the characteristics of the liquid crystal aligning film formed from the liquid crystal aligning agent, even if it is stored at room temperature for a long time. Further, it is possible to suppress the change in the pretilt angle and the deterioration of the afterimage characteristic of the liquid crystal display device having the liquid crystal alignment film.

Claims (14)

A method for producing a polyamic acid block polymer, which comprises heating a solution containing two or more polyamic acids to 30° C. or higher to cause an amide exchange reaction. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating temperature is 30 to 100°C. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating temperature is 50 to 100°C. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating temperature is 60 to 80°C. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating time is 1 to 48 hours. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating time is 4 to 30 hours. The method for producing a polyamic acid block polymer according to claim 1, wherein the heating time is 5 to 24 hours. The production of the polyamic acid block polymer according to any one of claims 1 to 7, wherein the solution containing two or more polyamic acids is a solution obtained by synthesizing two or more polyamic acids individually and then mixed. Method. A solution containing two or more polyamic acids first synthesizes the first polyamic acid, and then charges the reaction vessel with diamines and tetracarboxylic dianhydrides, which are the raw materials for the second polyamic acid. The method for producing a polyamic acid block polymer according to any one of claims 1 to 7, which is a reacted solution. A solution containing two or more polyamic acids is ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, propylene glycol monobutyl ether, propylene glycol. Monomethyl ether, or dipropylene glycol monomethyl ether, diisobutyl ketone, 4-methyl-2-pentanol or diisobutylcarbinol, more preferably ethylene glycol monobutyl ether, ethylene glycol monotert-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol. The method for producing a polyamic acid block polymer according to any one of claims 1 to 9, which is a solution containing any one or more selected from the group consisting of diethyl ether and propylene glycol monobutyl ether. The manufacturing method of the liquid crystal aligning agent containing the polyamic acid block polymer manufactured by the manufacturing method of Claims 1-10. A liquid crystal aligning agent containing the polyamic acid block polymer produced by the production method according to claim 1. A liquid crystal alignment film formed by the liquid crystal alignment agent according to claim 12. A liquid crystal display device comprising the liquid crystal alignment film according to claim 13.

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