JP6160610B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film formed from the liquid crystal aligning agent, and a liquid crystal display element.

  An organic material film made of a polymer material has been widely used as an interlayer insulating film, a protective film, and the like in electronic devices because of its ease of formation and insulation performance. There are various materials such as an acrylic resin, an epoxy resin, and a polyimide resin, but polyimide resins having high heat resistance are widely used in applications that require high durability. For example, in a liquid crystal display element well known as a display device, a film made of polyimide is used as a liquid crystal alignment film.

The liquid crystal alignment film is a constituent member of a liquid crystal display element widely used as a display device, and is formed on the surface of a substrate that sandwiches a liquid crystal layer.
The liquid crystal alignment film has a role of aligning liquid crystal molecules constituting the liquid crystal layer in a certain direction, and in addition, has a role of controlling the pretilt angle of the aligned liquid crystal molecules.

As described above, polyimide-based organic films that are excellent in durability and suitable for controlling the pretilt angle of liquid crystals are widely used as liquid crystal alignment films that are currently used industrially. This polyimide-based liquid crystal alignment film is usually formed using a resin composition called a liquid crystal aligning agent or the like. The resin composition is prepared as a polymer containing a polymer synthesized using a diamine compound having a desired structure and a tetracarboxylic acid derivative. Examples of the polymer to be contained include polyamic acid that is a polyimide precursor (sometimes referred to as polyamic acid), polyimide formed by imidizing polyamic acid, and the like.
The liquid crystal alignment film is formed as a cured film made of polyimide by forming a coating film using such a resin composition and heating the coating film to cure the coating film.

Although polyimide has the characteristics of high heat resistance and excellent durability, there is a problem that polyimide itself and its precursor polyamic acid are usually difficult to dissolve in a solvent. Therefore, a resin composition containing a polymer such as polyimide and polyamic acid is required to improve applicability, for example, when applied to a substrate or the like.
Further, in order for the cured film made of polyimide to realize a desired alignment state of the liquid crystal molecules and to function as a liquid crystal alignment film, it is necessary to perform an alignment process on the cured film.

  As the alignment treatment, a rubbing treatment is known in which the surface of a cured film made of polyimide is rubbed in a certain direction using a cloth. However, the rubbing treatment has various problems such as generation of dust by rubbing the cured film and the possibility of causing scratches on the surface of the formed liquid crystal alignment film to cause uneven alignment of liquid crystal molecules. ing. Thus, attention has been paid to a photo-alignment processing technique that does not require rubbing in the formation of the liquid crystal alignment film of the liquid crystal display element.

In a liquid crystal display element, liquid crystal molecules respond by applying a voltage to an electrode provided between a substrate and a liquid crystal alignment film, and display a desired image using the change in the alignment of the liquid crystal molecules.
The liquid crystal display element has various display methods in which the initial alignment state of liquid crystal molecules and the form of alignment change by voltage application are different.

In recent years, among liquid crystal display element display methods, a vertical alignment (VA) type liquid crystal display element in which liquid crystal molecules having negative dielectric anisotropy are aligned perpendicularly to a substrate has been used in large-screen liquid crystal televisions and the like. Widely used for high-definition mobile applications (digital camera and mobile phone display). In this VA mode liquid crystal display element, it is required that the orientation change so that the liquid crystal molecules are tilted in a desired fixed direction parallel to the substrate by voltage application. Therefore, in the VA liquid crystal display element, the liquid crystal molecules need to be slightly inclined from the normal direction of the substrate toward one direction in the substrate surface as the initial alignment state of the liquid crystal molecules before voltage application. .
In a VA liquid crystal display element, a liquid crystal alignment film is used, and the liquid crystal molecules are aligned in the initial direction of the substrate from the normal direction of the substrate with a pretilt angle as the initial alignment state before voltage application. A slightly tilted alignment state can be realized.

  In a VA liquid crystal display element, a protrusion for controlling the direction in which the liquid crystal falls is formed on a TFT substrate or a color filter substrate, and a slit is formed on an ITO (Indium Tin Oxide) electrode on the substrate. A PVA (Patterned Vertical Alignment) system is known that controls the direction in which the liquid crystal falls by an electric field. In addition to providing a liquid crystal alignment film between the substrate and the liquid crystal layer and rubbing it to align the liquid crystal molecules with a slight tilt from the substrate normal direction to one direction in the substrate surface, a patent A photo-alignment method disclosed in Document 1, Patent Document 2, and the like is known.

In Patent Document 1 and Patent Document 2, a highly durable polyimide is used, and the molecular structure of the polyimide is suitably designed, and the vertical alignment property and light of the liquid crystal molecules required for the liquid crystal alignment film used for the VA liquid crystal display element. Orientation is realized.
In Patent Document 1, a diamine compound having a cinnamate structure having photodimerization in the molecule and a linear hydrophobic side chain structure is used. And the polyamic acid which is a polyimide precursor is synthesize | combined from the diamine compound and tetracarboxylic dianhydride, and the polyimide is formed from the polyamic acid, The photo-alignment vertical alignment type liquid crystal aligning film is obtained. .

Polyimide is a high heat-resistant polymer material that has high reliability and is suitable for use as a liquid crystal alignment film. However, polyimide and its precursor polyamic acid or the like usually have a problem of low solubility in a solvent. Furthermore, polyimide used for a liquid crystal aligning agent for VA liquid crystal display elements often has an alicyclic structure, an alkyl group, a fluorine atom, etc. in its side chain. There is a problem that repelling, film thickness unevenness, and the like are likely to occur during application to the coating (see Patent Document 3).
Therefore, the polyamic acid and polyimide formed from the diamine compound described in Patent Document 1 are also required to improve the solubility in a solvent and the coating property to a substrate.

  Moreover, the diamine compound described in Patent Document 1 has photoreactivity based on an intramolecular cinnamate structure. Therefore, for example, in the process of forming the liquid crystal alignment film, attention must be paid to the handling of the diamine compound, such as the need for light shielding during the process. That is, when obtaining a polyimide precursor and a polyimide from a diamine compound having a photoreactive group described in Patent Document 1 or the like, it is necessary to take measures so that an undesired photoreaction does not proceed. Similarly, when forming a liquid crystal aligning film using the obtained polyimide precursor or polyimide, it is necessary to suppress unwanted photoreactions. Therefore, a diamine compound having a structure rich in photoreactivity in the molecule such as a cinnamic acid ester structure described in Patent Document 1 and the like, and a polyimide precursor and a polyimide obtained using the diamine compound are used at the time of use. Therefore, attention to light and the like is required, and the liquid crystal alignment film forming process is complicated.

Japan Special Table 2009-520702 Japanese Unexamined Patent Publication No. 2011-100099 International Publication No. 2010/079637 Pamphlet

  In the field of electronic devices, highly durable polyimide is frequently used as a main component, but in addition to the original features, the molecular structure has been improved to suit specific applications, and the characteristics have been improved. . For example, as described above, in a liquid crystal display element which is an electronic device, the molecular structure of polyimide is designed and controlled so as to have characteristics suitable as a liquid crystal alignment film, and is used for a liquid crystal alignment film.

  Control of a desired molecular structure in polyimide is realized by controlling the molecular structure of a diamine compound or the like used for forming a polyimide. For example, in order for a polyimide film to exhibit the performance required for a liquid crystal alignment film, the molecular structure of a diamine compound or the like is controlled, and a polyimide precursor or a polymer such as polyimide is synthesized using the diamine compound. Thereby, a cured film made of polyimide having a desired molecular structure is formed, and formation of a liquid crystal alignment film having desired characteristics is realized.

That is, the molecular structure of a diamine compound or the like used for forming a polyimide precursor or a polymer such as polyimide plays an important role in realizing desired properties in polyimide and is very important.
However, when a characteristic molecular structure for realizing desired characteristics is introduced into the molecule at the stage of the diamine compound used for forming the polyimide, there may be a problem in the process for producing the polyimide.
For example, the formation of a liquid crystal alignment film made of polyimide is, as described above, a resin composition containing a polymer such as polyamic acid formed from a diamine compound (synonymous with a liquid crystal alignment agent, hereinafter also referred to as a liquid crystal alignment agent). And the resin composition is used to form a liquid crystal alignment film. At this time, the diamine compound having a characteristic molecular structure may affect the properties of the polymer and the resin composition, and may affect the formation of a liquid crystal alignment film made of polyimide.

  For example, the diamine compound disclosed in Patent Document 1 has photoreactivity based on a cinnamate structure in order to realize the photoalignment of the liquid crystal alignment film. Therefore, in the process of forming the liquid crystal alignment film, care must be taken in handling the diamine compound, such as the need for light shielding during the process. That is, when trying to obtain a polymer such as a polyimide precursor and a polyimide from a diamine compound having a photoreactive group disclosed in Patent Document 1, etc., light is blocked so that an undesired photoreaction does not proceed. It is necessary to take measures. Moreover, even when preparing a resin composition using the obtained polymer, it is necessary to suppress an undesired photoreaction. Furthermore, even when forming a cured film using a resin composition, it is necessary to suppress unwanted photoreactions.

A diamine compound having a structure rich in photoreactivity in the molecule, such as a cinnamic acid ester structure disclosed in Patent Document 1 and the like, and a polyimide precursor and a polyimide obtained using the diamine compound are Care was required and the process of forming the cured film was complicated.
Furthermore, the polyimide precursor and polyimide formed using the diamine compound disclosed in Patent Documents 1 and 2 are not sufficiently soluble in the solvent, and the molecular structure of the diamine compound is not sufficiently improved. As a result, when the resin composition was prepared using them, the subject remained in the applicability | paintability.

In addition, in the formation of a liquid crystal alignment film having photo-alignment properties, there is a strong demand for a diamine compound that does not require measures such as shading, is easy to handle, and can be used for synthesis of a polymer such as a polyimide precursor and polyimide. It is done. Furthermore, the formed polyimide precursor and polyimide do not require light shielding and the like, are easy to handle, have excellent solubility in solvents, and have excellent coating properties for forming a polyimide film. Is required to be prepared.
In addition, the liquid crystal alignment film formed using the prepared resin composition can realize vertical alignment and photo-alignment in which the liquid crystal molecules are slightly tilted in a certain direction by photo-alignment treatment. It is required to be.

  That is, the object of the present invention is to prepare a liquid crystal aligning agent that can be easily formed, has excellent coating properties, and can form a vertical alignment type photo-alignment liquid crystal alignment film, and the liquid crystal aligning agent. It is to provide a polyimide precursor and a diamine compound to be used for producing a polyimide, a liquid crystal alignment film having a vertical alignment type photo-alignment property, and a liquid crystal display element having the liquid crystal alignment film.

（式（ＨＥ−１）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。）The present invention has the following gist.
(1) A liquid crystal aligning agent comprising at least one polymer selected from the group consisting of a polyimide precursor having a β-hydroxyester structure and a polyimide having a β-hydroxyester structure.
(2) The liquid crystal aligning agent according to (1), wherein the polyimide precursor having the β-hydroxyester structure and the polyimide having the β-hydroxyester structure are obtained from a diamine compound having a β-hydroxyester structure.
(3) The liquid crystal aligning agent as described in said (2) in which the said diamine compound has a structure represented by a following formula (HE-1).

(In Formula (HE-1), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms.

（式（ＨＥ−２）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。Ｘ_２は、単結合又は、エーテル、エステル、アミド、及びウレタンからなる群より選ばれる少なくとも１種の２価の結合基を表す。Ｘ_３は、炭素数３〜２０の直鎖状アルキル基又は炭素数４〜４０の脂環式骨格を有する１価の有機基を表す。ただし、このアルキル基の水素原子は、フッ素原子に置き換わっていてもよい。）(4) The liquid crystal aligning agent as described in said (2) or (3) in which the said diamine compound has a structure represented by a following formula (HE-2).

(In Formula (HE-2), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or And at least one divalent linking group selected from the group consisting of ether, ester, amide, and urethane, X ₃ represents a linear alkyl group having 3 to 20 carbon atoms or a fat having 4 to 40 carbon atoms. Represents a monovalent organic group having a cyclic skeleton, provided that the hydrogen atom of the alkyl group may be replaced by a fluorine atom.)

（式（ＤＡ）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。Ｘ_２は、単結合又は、エーテル、エステル、アミド、及びウレタンからなる群より選ばれる少なくとも１種の２価の結合基を表す。Ｘ_３は、炭素数３〜２０の直鎖状アルキル基又は炭素数４〜４０の脂環式骨格を有する１価の有機基を表す。ただし、このアルキル基の水素原子は、フッ素原子に置き換わっていてもよい。Ｘ_４は単結合、メチレン基又は炭素数２〜６のアルキレン基を表す。ただし、このアルキレン基は、水酸基によって置換されていてもよい。Ｘ_５は、単結合、酸素原子、＊−ＯＣＯ−又は＊−ＯＣＨ_２−（ただし、「＊」を付した結合手がＸ_４と結合する。）を表す。ただし、Ｘ_４が単結合であるときＸ_５は単結合である。）(5) The liquid crystal aligning agent in any one of said (2)-(4) whose said diamine compound is a compound represented by a following formula (DA).

(In the formula (DA), X ₁ is a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, a bicyclic ring system having 8 to 10 atoms, And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or an ether Represents at least one divalent linking group selected from the group consisting of ester, amide, and urethane, X ₃ is a C 3-20 linear alkyl group or C 4-40 alicyclic. A monovalent organic group having a skeleton, wherein a hydrogen atom of the alkyl group may be replaced by a fluorine atom, X ₄ represents a single bond, a methylene group or an alkylene group having 2 to 6 carbon atoms. However, this alkylene group may be substituted with a hydroxyl group. X ₅ represents a single bond, an oxygen atom, * —OCO— or * —OCH ₂ — (where a bond marked with “*” is bonded to X ₄ ), provided that X ₄ is a single bond. When it is a bond, X ₅ is a single bond.)

（式（ＨＥ−１）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。）(6) The liquid crystal aligning film obtained from the liquid crystal aligning agent in any one of said (1)-(5).
(7) A liquid crystal display device having the liquid crystal alignment film according to (6).
(8) A diamine compound having a structure represented by the following formula (HE-1).

(In Formula (HE-1), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms.

（式（ＨＥ−３）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。Ｘ_２は、単結合又は、エーテル、エステル、アミド、及びウレタンからなる群より選ばれる少なくとも１種の２価の結合基を表す。Ｘ_６は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_７は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_８は、炭素数１〜２０の直鎖状アルキル基を表す。）(9) The diamine compound according to (8), which has a structure represented by the following formula (HE-3).

(In Formula (HE-3), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or Represents at least one divalent linking group selected from the group consisting of benzene, ether, ester, amide, and urethane, and X ₆ is a divalent organic group having a single bond or an alicyclic skeleton having 4 to 40 carbon atoms. X ₇ represents a single bond or a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, and X ₈ represents a linear alkyl group having 1 to 20 carbon atoms.

（式（ＤＩＡ）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。Ｘ_２は、単結合又は、エーテル、エステル、アミド、及びウレタンからなる群より選ばれる少なくとも１種の２価の結合基を表す。Ｘ_６は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_７は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_８は、炭素数１〜２０の直鎖状アルキル基を表す。Ｘ_９は、単結合、メチレン基又は炭素数２〜６のアルキレン基を表す。ただし、このアルキレン基は水酸基によって置換されていてもよい。Ｘ_１０は、単結合、酸素原子、＊−ＯＣＯ−、＊−ＯＣＨ_２−、＊−ＣＯＯ−、＊−ＮＨＣＯ−、又は＊−ＣＯＮＨ−（ただし、「＊」を付した結合手がＸ_９と結合する。）を表す。ただし、Ｘ_９が単結合であるときＸ_１０は単結合である。）(10) The diamine compound according to the above (8) or (9) represented by the following formula (DIA).

(In the formula (DIA), X ₁ is a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, a bicyclic ring system having 8 to 10 atoms, And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or an ether X ₆ represents at least one divalent linking group selected from the group consisting of ester, amide, and urethane, and X ₆ represents a divalent organic group having a single bond or an alicyclic skeleton having 4 to 40 carbon atoms. X ₇ represents a single bond or a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, X ₈ represents a linear alkyl group having 1 to 20 carbon atoms, X ₉ Represents a single bond, a methylene group or an alkylene group having 2 to 6 carbon atoms, provided that the alkylene group is a hydroxyl group. Therefore substituted _{.X 10} represents a single bond, an oxygen _{atom, * - OCO -, * -} OCH 2 -, * - COO -, * - NHCO-, or * -CONH- (where "*" bond marked with binds to X _9.) represents a. However, X ₁₀ when X ₉ is a single bond is a single bond.)

(11) A polymer having a β-hydroxyester structure in the molecule, obtained by using the diamine compound according to any one of (8) to (10) above.
(12) A liquid crystal aligning agent containing the polymer described in (11) above.
(13) A liquid crystal alignment film obtained from the liquid crystal aligning agent according to (12).
(14) A method for producing a diamine compound represented by the following formula (DIA),
A step of obtaining a compound represented by the following formula (C-2) by a reaction between the compound represented by the following formula (C-1) and Meldrum's acid;
A step of obtaining a compound represented by the following formula (C-4) by a reaction between the compound represented by the formula (C-2) and the following formula (C-3);
Reducing the nitro group of the compound represented by the formula (C-4), and reducing the ketone structure part of the β-ketoester structure.

（式（ＤＩＡ）、（Ｃ−１）、（Ｃ−２）、（Ｃ−３）及び（Ｃ−４）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。Ｘ_２は、単結合又は、エーテル、エステル、アミド、及びウレタンからなる群より選ばれる少なくとも１種の２価の結合基を表す。Ｘ_６は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_７は、単結合又は炭素数４〜４０の脂環式骨格を有する２価の有機基を表す。Ｘ_８は、炭素数１〜２０の直鎖状アルキル基を表す。Ｘ_９は、単結合、メチレン基又は炭素数２〜６のアルキレン基を表す。ただし、このアルキレン基は水酸基によって置換されていてもよい。Ｘ_１０は、単結合、酸素原子、＊−ＯＣＯ−、＊−ＯＣＨ_２−、＊−ＣＯＯ−、＊−ＮＨＣＯ−、又は＊−ＣＯＮＨ−（ただし、「＊」を付した結合手がＸ₉と結合する。）を表す。ただし、Ｘ_９が単結合であるときＸ_１０は単結合である。）

(In Formula (DIA), (C-1), (C-2), (C-3) and (C-4), X ₁ represents a monocyclic ring having 5 or 6 atoms, 5 or 6 atoms, An unsubstituted or substituted selected from the group consisting of 6 adjacent monocyclic rings of 6; bicyclic ring systems of 8 to 10 atoms; and tricyclic ring systems of 13 or 14 atoms Represents a carbocyclic or heterocyclic aromatic group, and X ₂ represents a single bond or at least one divalent linking group selected from the group consisting of ether, ester, amide, and urethane. ₆ represents a single bond or a divalent organic group having an alicyclic skeleton having 4 to 40 carbon atoms, and X ₇ is a divalent organic group having a single bond or an alicyclic skeleton having 4 to 40 carbon atoms. the representative .X ₈ is .X ₉ representing a linear alkyl group having 1 to 20 carbon atoms is a single bond, a methylene group or a 2 to 6 carbon atoms Represents a Killen group provided that the alkylene group may _{.X 10} be substituted by a hydroxyl group, a single bond, an oxygen _{atom, * -. OCO -, *} - OCH 2 -, * - COO -, * - NHCO- Or * —CONH— (wherein the bond marked with “*” binds to X ₉ ), provided that when X ₉ is a single bond, X ₁₀ is a single bond.)

ADVANTAGE OF THE INVENTION According to this invention, the diamine compound which can be easily handled and can form polymers, such as a polyimide precursor excellent in solubility, and a polyimide, can be provided.
Furthermore, according to the present invention, a liquid crystal aligning agent that is easy to handle, has excellent coating properties, and can form a vertical alignment type photo-alignment liquid crystal alignment film, is formed from the liquid crystal aligning agent, and is vertically An alignment-type photo-alignment liquid crystal alignment film and a liquid crystal display element having the liquid crystal alignment film can be provided, and can be used as a display element that displays a high-definition image.

It is a figure which shows the measurement result of the ultraviolet absorption spectrum before and behind baking. It is a figure which shows the measurement result of the ultraviolet absorption spectrum of the cured film of a comparative example. It is a figure which shows the measurement result of the ultraviolet absorption spectrum after linearly polarized light irradiation.

As a result of intensive studies, the present inventors have obtained the following knowledge and completed the present invention.
In a liquid crystal display element as a display device, as described above, a polyimide film having high heat resistance and high strength is often used as a liquid crystal alignment film for aligning liquid crystal molecules.

Furthermore, when forming the polyimide film used as a liquid crystal aligning film on the board | substrate which comprises a liquid crystal display element, the method of using the following liquid crystal aligning agents is used suitably.
As the method, a liquid crystal aligning agent containing a polyimide precursor such as polyamic acid is prepared. Next, a method of forming a coating film using the obtained liquid crystal aligning agent and imidizing on a substrate to obtain a polyimide film is known. As another method, previously imidized polyimide is dissolved in a solvent to prepare a solvent-soluble liquid crystal aligning agent, and a coating film is formed using the liquid crystal aligning agent. There is a method for obtaining a polyimide film.

The method for forming a polyimide film to be a liquid crystal alignment film is the same for the VA liquid crystal display element.
The VA liquid crystal display element requires a vertical alignment type liquid crystal alignment film in which liquid crystal molecules are slightly inclined from the normal direction of the substrate toward one direction in the substrate surface. In order to obtain such a liquid crystal alignment film, a polyimide film that aligns liquid crystal molecules in the normal direction of the substrate is obtained using a liquid crystal alignment agent containing a polyimide precursor or polyimide. Next, this polyimide film is subjected to an alignment treatment so that the liquid crystal molecules are slightly inclined from the normal direction of the substrate toward one direction in the substrate surface, thereby forming a desired vertical alignment type liquid crystal alignment film. doing.

As for the alignment treatment, a rubbing treatment is known in which the surface of a polyimide film is rubbed in a certain direction using a cloth. However, the rubbing treatment has various problems because it generates dust by rubbing the polyimide film and may cause scratches on the surface of the liquid crystal alignment film to cause uneven alignment of liquid crystal molecules.
Therefore, in the manufacture of a VA liquid crystal display element, a liquid crystal alignment film photo-alignment technique that does not require a rubbing process has been used. That is, development of a vertical alignment type photo-alignment liquid crystal alignment film is underway.

  The vertical alignment type photo-alignment liquid crystal alignment film has a structure for realizing vertical alignment of liquid crystal molecules and a structure for realizing photo-alignment inside. For example, when the liquid crystal aligning agent is composed of a polyimide film, a diamine compound or a tetracarboxylic acid derivative for forming the polyimide film contains a specific structure for realizing such vertical alignment and photoalignment. It is preferable to use it. In this case, the formed polyimide can realize a liquid crystal alignment film having vertical alignment and photo alignment.

  In Patent Documents 1 and 2, a polyimide film is formed using a diamine compound having a cinnamate structure having photodimerization and a linear hydrophobic side chain structure in the molecule. Next, the polyimide film is subjected to a photo-alignment treatment, thereby realizing a vertical alignment type photo-alignment liquid crystal alignment film.

  However, in the techniques disclosed in Patent Documents 1 and 2, the diamine compound for forming polyimide has a cinnamic acid ester structure in the molecule, and has a structure rich in photoreactivity. Therefore, attention such as shading is indispensable for the handling. That is, in the polyimide precursor forming step and the polyimide forming step, attention and measures for suppressing unwanted photoreactions are required.

  In addition, as described above, in the polyimide precursor and polyimide structures as disclosed in Patent Documents 1 and 2, there is an improvement in molecular structure for improving the solubility in a solvent and the coating property on a substrate. Not enough. Therefore, when preparing a liquid crystal aligning agent using them, a subject remains in the applicability | paintability of the obtained liquid crystal aligning agent.

The diamine compound of the present invention is a novel compound having a characteristic molecular structure, and can be suitably used for the synthesis of polymers such as polyimide precursors and polyimides.
Although the diamine compound of the present invention does not have photoreactivity by itself, a cured film obtained from a polymer formed using the diamine compound can have photoreactivity. That is, it can be suitably used to provide a liquid crystal alignment film made of polyimide having a structure suitable for photo-alignment processing. In particular, it can be used to provide a vertical alignment type photo-alignment liquid crystal alignment film suitable for forming a VA liquid crystal display element.

The diamine compound of the present invention has a β-hydroxyester structure in the molecule. In addition, the liquid crystal alignment film formed using the diamine compound has a structure suitable for realizing vertical alignment of liquid crystal molecules.
The β-hydroxyester structure in the molecule undergoes a dehydration reaction by heating to form a photoreactive double bond.
The diamine compound having a β-hydroxyester structure of the present invention can react with a tetracarboxylic acid derivative to provide a polymer such as a polyimide precursor and polyimide. The coating film formed using the obtained liquid crystal aligning agent containing the polymer can produce | generate a photoreactive double bond in molecular structure by the heating after forming.

  For example, a polyimide precursor is synthesized from a diamine compound having a β-hydroxy ester structure, and a liquid crystal aligning agent containing the obtained polyimide precursor can be prepared. In that case, the coating film of the liquid crystal aligning agent is heated to perform the imidation reaction of the polyimide precursor component, and at the same time, a dehydration reaction is caused in the β-hydroxy ester structure portion, and a photoreactive double bond is formed in the molecule Can be introduced.

In addition, by locally heating the coating film of the liquid crystal aligning agent, a cured film in which a cured film portion having photoreactivity and a portion having a polyimide precursor not having photoreactivity are mixed can be prepared. .
That is, it is possible to make a part having a photoreactive group and a part having no photoreactivity on the same film. As a result, the conventional process of forming a negative pattern by covering the resin surface with a mask or the like and irradiating the resin with a mask or the like can be made by only the heating process without a mask.

  Furthermore, a polyimide is synthesized from a diamine compound having a β-hydroxyester structure, and a liquid crystal aligning agent containing the obtained polyimide can be prepared. In that case, the coating film of the liquid crystal aligning agent can be heated to form a polyimide film, and at the same time, a dehydration reaction can be caused in the β-hydroxyester structure and a photoreactive double bond can be introduced into the molecule.

By introducing the double bond into the molecule as described above, the polyimide precursor and the polymer such as polyimide according to the present invention form a cured film made of polyimide and, for example, cinnamic acid in the molecule. Photoreactive sites such as ester structures can be introduced. As a result, the cured film formed from the polymer can exhibit photoreactivity. That is, in a liquid crystal alignment film formed using these cured films, photoalignment can be realized.
In addition, the diamine compound according to the present invention has a molecular structure suitable for aligning liquid crystal molecules in the normal direction of the substrate when a liquid crystal alignment film is formed. A cured film formed from at least one of a polyimide precursor and a polyimide obtained by synthesis from a diamine compound having a β-hydroxyester structure according to the present invention is a vertically aligned photoreactive liquid crystal. It can be used as an alignment film.

  The diamine compound having a β-hydroxyester structure of the present invention does not have a photoreactive structure in the molecule and is stable to light. Therefore, no care or countermeasure is required for its handling.

  The diamine compound having a β-hydroxy ester structure of the present invention can synthesize a polyimide precursor and a polymer such as polyimide having a β-hydroxy ester structure. The obtained polymer does not have a photoreactive structure in the molecule, and does not have photoreactivity before introducing a double bond. Therefore, the polymer of the present invention is stable with respect to light, and conventional handling, measures, etc. are not required for its handling. The photoreactive double bond can be introduced into the structure after the cured film using the polymer is formed.

  In addition, the polyimide precursor and the polymer such as polyimide of the present invention have a β-hydroxyester structure in the molecule, and have a high solubility in a solvent by having a hydroxy group derived from the structure in the molecule. . Therefore, the liquid crystal aligning agent of this invention has high solubility with polymers, such as a polyimide precursor to contain and a polyimide, and has the outstanding applicability | paintability. Therefore, it is possible to increase the amount of a poor solvent such as butyl cellosolve contained in order to improve applicability. In addition, since the polymer itself has a hydroxy group at the side chain site, the polymer itself has high hydrophilicity and excellent coating property to the substrate.

The diamine compound of the present invention has a β-hydroxyester structure and a linear hydrophobic side chain structure in the molecule.
The diamine compound of the present invention can react with a tetracarboxylic acid derivative to provide a polymer such as a polyimide precursor or polyimide.
The polymer of the present invention can be dissolved in a solvent or the like to form a liquid crystal aligning agent, and after forming a coating film, a cured film can be formed.
The cured film of the present invention is derived from the β-hydroxyester structure of the diamine compound, has a photoreactive double bond in the molecule, and has a linear hydrophobic side chain structure. Therefore, the cured film of the present invention can form a liquid crystal alignment film, is suitable for a photo-alignment treatment in the liquid crystal alignment film, and provides a vertical alignment type photo-alignment liquid crystal alignment film. it can.

The present inventors have developed a polyimide and a polyimide precursor having a novel structure for use in a vertical alignment type photo-alignment liquid crystal alignment film.
The polyimide and the polyimide precursor of the present invention each have a β-hydroxy ester structure in the molecule, and also have a structure for realizing vertical alignment of liquid crystal molecules.
Various methods can be used to form the polyimide and the polyimide precursor used for the vertical alignment type photo-alignment liquid crystal alignment film having the novel structure of the present invention. In particular, it has been found that a method using a diamine compound having a novel structure is suitable.
The diamine compound of the present invention has a β-hydroxy ester structure in the molecule, and also has a structure for realizing vertical alignment of liquid crystal molecules.

The polyimide precursor of the present invention and the polyimide obtained by imidizing it have a β-hydroxyester structure in the molecule.
A method for obtaining a polyimide precursor having a β-hydroxy ester structure in the molecule can be realized by a method using a diamine compound having a β-hydroxy ester structure in the molecule. Moreover, it is realizable by the method of using the tetracarboxylic acid derivative which has (beta) -hydroxyester structure in a molecule | numerator.
Further, when a polyimide precursor is obtained by polymerization reaction of a diamine compound and a tetracarboxylic acid derivative, a compound having a β-hydroxyester structure in the molecule is used as an additive, and β-hydroxy is added to the formed polyimide precursor. There is a method for introducing an ester structure.

Among the methods for introducing the β-hydroxyester structure as described above, the method using the diamine compound of the present invention having a β-hydroxyester structure in the molecule is particularly preferable from the viewpoint of certainty.
Hereinafter, the present invention using a diamine compound having a β-hydroxyester structure in the molecule will be described in detail.
In the present invention, the polyimide precursor includes polyamic acid, polyamic acid ester, and the like.

本発明のジアミン化合物は、下記式（ＨＥ−１）の構造を有することが好ましい。下記式（ＨＥ−１）の構造を有することにより、該ジアミン化合物を用いて形成されたポリイミド前駆体及びポリイミド前駆体をイミド化したポリイミドにおいては、加熱した場合に、分子内に優れた光反応性を有する二重結合を形成することができる。二重結合が形成されたポリイミド前駆体及びポリイミド前駆体をイミド化したポリイミドは、液晶配向膜の形成に用いられた場合、優れた光配向性能を発現することができる。<Diamine compound having β-hydroxy ester structure>
The diamine compound of the present invention is a diamine compound having a β-hydroxyester structure. The β-hydroxyester structure can be represented by the following formula (HE).

The diamine compound of the present invention preferably has a structure represented by the following formula (HE-1). By having a structure represented by the following formula (HE-1), a polyimide precursor formed using the diamine compound and a polyimide obtained by imidizing the polyimide precursor have excellent photoreaction in the molecule when heated. A double bond having a property can be formed. When the polyimide precursor in which the double bond is formed and the polyimide obtained by imidizing the polyimide precursor are used for the formation of a liquid crystal alignment film, it can exhibit excellent optical alignment performance.

上記式（ＨＥ−１）中、Ｘ_１は、原子数５若しくは６の単環式環、原子数５若しくは６の２つの隣接する単環式環、原子数８〜１０の二環式の環系、及び原子数１３若しくは１４の三環式の環系からなる群より選択される、非置換若しくは置換の、炭素環式又は複素環式の芳香族基を表す。

In the above formula (HE-1), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms.

In the structure of the above formula (HE-1), a particularly preferred structure is a structure represented by the following formula (HE-1-1). In a polyimide precursor and polyimide formed using a diamine compound having a structure represented by the following formula (HE-1-1), when heated, a double bond having photoreactivity in the molecule Can be formed. The polyimide precursor in which the double bond is formed and the polyimide imidized from the polyimide precursor can exhibit particularly excellent photo-alignment performance when used for forming a liquid crystal alignment film.

上記式（ＨＥ−２）中、Ｘ_１は、上記式（ＨＥ−１）と同義である。The diamine compound of the present invention preferably has a structure of the following formula (HE-2) having a β-hydroxyester structure and a structure for realizing vertical alignment of liquid crystal molecules.

In the formula (HE-2), X ₁ has the same meaning as the formula (HE-1).

In the formula (HE-2), X ₂ represents a single bond or at least one divalent linking group selected from the group consisting of ether, ester, amide, and urethane.
X ₂ is preferably a single bond, an ether group, an ester group or an amide group, more preferably a single bond, an ether group or an ester group.
X ₃ represents a monovalent organic group having a linear alkyl group having 3 to 20 carbon atoms or an alicyclic skeleton having 4 to 40 carbon atoms. However, the hydrogen atom of this alkyl group may be replaced with a fluorine atom.
Examples of X ₃ include n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, and n-undecyl. Group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, adamantyl group, spiro [5.5] undecyl group, bicyclo [2.2.2] octyl group, bicyclo [2.2.1] heptyl group, cyclohexyl-n-heptyl group, bicyclohexyl-n-pentyl group, phenyl group, Naphthyl group, anthracenyl group, cyclohexylphenyl group, n-pentyl-cyclohexylphenyl group, n-heptyl-cyclohexylphenyl group, A cyclohexyloxyphenyl group or an n-pentyl-cyclohexyloxyphenyl group is preferred, and an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a cyclohexyl group, a cyclohexyl- An n-heptyl group, a bicyclohexyl-n-pentyl group, a cyclohexyloxyphenyl group, or an n-pentyl-cyclohexyloxyphenyl group is more preferable.
The linear alkyl group having 3 to 20 carbon atoms as X ₃ has a function as a hydrophobic side chain structure in the present invention.

上記式（ＤＡ）中、Ｘ_１は、上記式（ＨＥ−１）における定義と同義であり、好ましい例についても同様である。Preferable examples of the diamine compound of the present invention include compounds represented by the following formula (DA).

In the above formula (DA), X ₁ has the same definition as in the above formula (HE-1), and the same applies to the preferred examples.

X ₂ has the same definition as in the above formula (HE-2), and the same applies to the preferred examples.
X ₃ has the same definition as in the above formula (HE-2), and the same applies to the preferred examples.

X ₄ represents a single bond, a methylene group or an alkylene group having 2 to 6 carbon atoms. However, this alkylene group may be substituted with a hydroxyl group.
X ₄ is preferably a single bond, a methylene group, an ethylene group, an n-propylene group, or an n-butylene group, and more preferably a single bond or an ethylene group.
X ₅ represents a single bond, an oxygen atom, * —OCO— or * —OCH ₂ — (wherein a bond marked with “*” is bonded to X ₄ ). However, when X ₄ is a single bond, X ₅ is a single bond.
X ₅ is preferably a single bond, an oxygen atom, or * —OCH ₂ —, more preferably * —OCH ₂ — or an oxygen atom.

Preferable examples of the diamine compound represented by the above formula (DA) include diamine compounds represented by the following formulas (DA-1) to (DA-8).

In the above formulas (DA-1) to (DA-8), R _a is an alkyl group having 3 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom.
The X _a, linear alkyl group having 3 to 16 carbon atoms, for example, n- propyl, n- butyl, n- pentyl, n- hexyl, n- heptyl, n- octyl radical, n -Nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, or n-hexadecyl group are preferable, n-octyl group, n- A nonyl group, an n-decyl group, an n-undecyl group, or an n-dodecyl group is more preferable.
R _b is an alkyl group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom.
_Xb is a linear alkyl group having 1 to 12 carbon atoms such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n -An octyl group, n-nonyl group, n-decyl group, n-undecyl group or n-dodecyl group is preferable, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, or n- A heptyl group is more preferred.

The diamine compound of the present invention is a diamine compound having a β-hydroxyester structure, and has a structure of the following formula (HE-3) having a structure for realizing vertical alignment of liquid crystal molecules. Is preferred.

In formula (HE-3), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring system having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of 13 or 14 tricyclic ring systems.
X ₁ includes benzene ring, naphthalene ring, pentalene ring, indene ring, azulene ring, anthracene ring, furan ring, thiophene ring, pyrrole ring, pyridine ring, pyridazine ring, benzofuran ring, indole ring, quinoline ring, benzimidazole ring , A quinoxaline ring, a carbazole ring, a fluorene ring, or a xanthene ring, and a benzene ring or a naphthalene ring is more preferable.

X ₂ represents a single bond or at least one divalent linking group selected from the group consisting of ethers, esters, amides, and urethanes.
X ₂ is preferably a single bond, an ether group, an ester group or an amide group, more preferably a single bond, an ether group or an ester group.
X ₆ represents a divalent organic group having a single bond or an alicyclic skeleton having 4 to 40 carbon atoms.
X ₆ is cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, spiro [5.5] undecyl, bicyclo [2.2.2] octyl, bicyclo [2 2.1] A heptyl group, a phenyl group, a naphthyl group, or an anthracenyl group is preferable, and a cyclohexyl group or a phenyl group is more preferable.

X ₇ represents a divalent organic group having a single bond or an alicyclic skeleton having 4 to 40 carbon atoms.
X ₇ includes a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantyl group, a spiro [5.5] undecyl group, a bicyclo [2.2.2] octyl group, and a bicyclo [2 2.1] A heptyl group, a phenyl group, a naphthyl group, and an anthracenyl group are preferable, and a cyclohexyl group or a phenyl group is more preferable.
X ₈ represents a linear alkyl group having 1 to 20 carbon atoms.
X ₈ is a linear alkyl group having 1 to 12 carbon atoms, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, An n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, or an n-dodecyl group is preferable, and an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, or An n-heptyl group is more preferable.
In the linear alkyl group having 1 to 20 carbon atoms as X ₈ , the linear alkyl group having 1 to 20 carbon atoms has a function as a hydrophobic side chain structure in the present invention.

式（ＤＩＡ）中、Ｘ_１は、上記式（ＨＥ−３）における定義と同義であり、好ましい例についても同様である。Preferred examples of the diamine compound of the present invention having the above structure include a diamine compound represented by the following formula (DIA).

In the formula (DIA), X ₁ has the same definition as in the above formula (HE-3), and the same applies to the preferred examples.

X ₂ has the same definition as in the above formula (HE-3), and the same applies to the preferred examples.
X ₆ has the same definition as in the above formula (HE-3), and the same applies to the preferred examples.
X ₇ has the same definition as in the above formula (HE-3), and the same applies to the preferred examples.
X ₈ has the same definition as in the above formula (HE-3), and the same applies to the preferred examples.

X ₉ represents a single bond, a methylene group or an alkylene group having 2 to 6 carbon atoms. However, this alkylene group may be substituted with a hydroxyl group.
X ₉ is preferably a single bond, a methylene group, an ethylene group, an n-propylene group, or an n-butylene group, and more preferably a single bond or an ethylene group.
X ₁₀ represents a single bond, an oxygen atom, * —OCO—, * —OCH ₂ —, * —COO—, * —NHCO—, or * —CONH— (where the bond marked with “*” is X ₉ It is combined with.) However, when X ₉ is a single bond, X ₁₀ is a single bond.
X ₁₀ is preferably a single bond, an oxygen atom, * —OCO—, * —OCH ₂ —, or * —COO—, more preferably —OCH ₂ — or an oxygen atom.

Examples of the diamine compound represented by the formula (DIA) include diamine compounds represented by the following formulas (DIA-1) to (DIA-7).

In the present invention, in addition to the diamine compound having a β-hydroxyester structure, as a preferred diamine compound, for example, a diamine compound having a β-hydroxyketone structure as represented by the following formula (HK-1) Can be illustrated. The diamine compound having this β-hydroxyketone structure can be used for the synthesis of a polymer such as the polyimide precursor and the polyimide of the present invention.
Although this diamine compound itself does not have photoreactivity, a cured film formed from a polymer synthesized using the diamine compound introduces a photoreactive double bond structure into the molecule by heating or the like. And has photoreactivity. Therefore, it can be suitably used for providing a liquid crystal alignment film made of polyimide having a structure suitable for optical alignment treatment. In particular, it can be used to provide a vertical alignment type photo-alignment liquid crystal alignment film suitable for forming a VA liquid crystal display element.

式（ＨＫ−１）で表されるジアミン化合物の例としては、下記式（ＤＩＡ−８）〜（ＤＩＡ−１１）で表されるジアミン化合物を挙げることができる。

Examples of the diamine compound represented by the formula (HK-1) include diamine compounds represented by the following formulas (DIA-8) to (DIA-11).

The formation method of (beta) -hydroxyester structure in the diamine compound of this invention is not specifically limited. For example, it can be formed by preparing zinc enolate from the corresponding α-haloester by a Reformatsky reaction and reacting with an aldehyde.
In addition, a method of reacting an α-haloester with an aldehyde in the presence of a metal alkoxide, performing Darzens condensation for synthesizing an epoxide, and then deriving the β-hydroxyester by hydrolysis is exemplified.

  Another method is to selectively reduce only the ketone moiety in the presence of an ester from β-ketoester, which is a precursor of β-hydroxy ester, using sodium borohydride, sodium cyanoborohydride, or the like. Even so, β-hydroxyesters can be synthesized. Also known is a method of obtaining the target β-hydroxy ester by reducing the ketone moiety under a metal catalyst such as Ru.

  As a method for synthesizing β-ketoesters, which are precursors of β-hydroxyesters, the target β-ketoester or β-hydroxyester is obtained by cross-Claisen condensation when there is no acidic αhydrogen in one ester. Examples thereof include a synthesis method, a method in which an alkyl cyanoformate (Mander reagent) is reacted with a ketone enolate, a method in which an acid imidazolide is produced from carbonyldiimidazole and a carboxylic acid, and a monoalkylmagnesium malonate is reacted.

In the present invention, a method for synthesizing a diamine compound having a preferable β-hydroxyester structure is as follows.
First, Meldrum's acid derivative is synthesized from carboxylic acid chloride having a target skeleton by reacting Meldrum's acid in the presence of a base catalyst. Next, the Meldrum's acid derivative is reacted with an alcohol having a corresponding structure having a nitro group that is subsequently reduced to an amino group, thereby synthesizing a target β-ketoester. Thereafter, by reducing the nitro group in the molecule by hydrogenation and reducing the ketone with sodium borohydride, a β-hydroxyester structure can be formed, and a diamine compound having a novel structure can be synthesized.

  In particular, in the case of synthesizing the diamine compound as described above, the molecule may have an aromatic ring having an electron withdrawing group such as a nitro group that is subsequently reduced to an amino group, and a benzyl structure. In this case, the acidity at the benzyl position becomes high, and side reactions often occur in the presence of a strong base, and the desired synthesis reaction may not proceed well. Claisen condensation or the like generally performed when synthesizing β-hydroxyesters or β-ketoesters is often performed in the presence of a strong base catalyst. As described above, the proton at the benzyl position may be withdrawn, causing an undesirable side reaction or preventing the reaction from proceeding.

In the method for synthesizing a diamine compound having a β-hydroxyester structure of the present invention, it is desirable to select a production method that avoids the use of a strong base. For example, even when dinitrobenzyl alcohol is used as a raw material, the synthesis of the target compound can be achieved with high efficiency by suppressing the side reaction.
The main steps of the method for producing a diamine compound represented by the above formula (DIA) are as follows.

A step of obtaining a compound represented by the following formula (C-2) by a reaction between the compound represented by the following formula (C-1) and Meldrum's acid;
A step of obtaining a compound represented by the following formula (C-4) by a reaction between the compound represented by the formula (C-2) and the following formula (C-3);
Reducing the nitro group of the compound represented by formula (C-4), and further reducing the ketone structure portion of the β-ketoester structure.

X ₁ , X ₂ , X ₆ , X ₇ , X ₈ , in formula (DIA), formula (C-1), formula (C-2), formula (C-3), and formula (C-4), X ₉ and X ₁₀ are synonymous with the definitions in the above formula (HE-3) and formula (DIA), and the same applies to preferred examples.
However, when X ₉ is a single bond, X ₁₀ is a single bond.

<Other diamine compounds>
As a diamine for reacting with a tetracarboxylic acid derivative to synthesize a polyimide precursor and a polyimide that can be contained in the liquid crystal aligning agent of the present invention, a diamine represented by the above formula (DA) or formula (DIA) A compound may be used alone. Moreover, you may use combining the compound represented by the said formula (DA) or a formula (DIA), and the other diamine compound represented by a following formula (AM).

上記式（ＡＭ）中、Ｙ_１は、２価の有機基であり、２種類以上が混在していてもよい。また、上記式（ＡＭ）中、Ｒ^１よびＲ^２は水素原子又は１価の有機基を表す。
より具体的には、上記式（ＡＭ）において、Ｒ^１〜Ｒ^２は、それぞれ独立して、水素原子、又は置換基を有してもよい炭素数１〜１０のアルキル基、アルケニル基、アルキニル基である。

In the above formula (AM), Y ₁ is a divalent organic group, and two or more kinds may be mixed. In the above formula (AM), R ¹ and R ² represent a hydrogen atom or a monovalent organic group.
More specifically, in the above formula (AM), R ^{1 and} R ² are each independently a hydrogen atom or an optionally substituted alkyl group, alkenyl group, alkynyl group having 1 to 10 carbon atoms. It is a group.

Specific examples of the alkyl group having 1 to 10 carbon atoms that may have a substituent include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, and a cyclopentyl group. , A cyclohexyl group, a bicyclohexyl group, and the like.
Examples of the alkenyl group having 1 to 10 carbon atoms which may have a substituent include those in which one or more CH ₂ —CH ₂ structures present in the above alkyl group are replaced with a CH═CH structure. More specifically, vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group And cyclohexenyl group.

Examples of the alkynyl group having 1 to 10 carbon atoms which may have a substituent include those obtained by replacing one or more CH ₂ —CH ₂ structures present in the alkyl group with a C≡C structure. More specifically, an ethynyl group, 1-propynyl group, 2-propynyl group and the like can be mentioned.
The above alkyl group, alkenyl group, and alkynyl group may have a substituent as long as it has 1 to 10 carbon atoms as a whole, and may further form a ring structure with the substituent. The formation of a ring structure by a substituent means that the substituents or a substituent and a part of the mother skeleton are bonded to form a ring structure.

  Examples of substituents include halogen groups, hydroxyl groups, thiol groups, nitro groups, aryl groups, organooxy groups, organothio groups, organosilyl groups, acyl groups, ester groups, thioester groups, phosphate ester groups, amide groups, alkyls. A group, an alkenyl group and an alkynyl group.

Examples of the halogen group as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
A phenyl group is mentioned as an aryl group which is a substituent. This aryl group may be further substituted with the other substituent described above.

  The organooxy group which is a substituent can have a structure represented by OR. R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples of the organooxy group include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.

  As the organothio group which is a substituent, the structure represented by -S-R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the substituent described above. Specific examples of the organothio group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

As the organosilyl group which is a substituent, a structure represented by -Si- (R) ₃ can be shown. R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples of the organosilyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a tripentylsilyl group, a trihexylsilyl group, a pentyldimethylsilyl group, and a hexyldimethylsilyl group.

  As an acyl group which is a substituent, the structure represented by -C (O) -R can be shown. Examples of R include the alkyl groups, alkenyl groups, and aryl groups described above. These Rs may be further substituted with the substituent described above. Specific examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoyl group and the like.

As an ester group which is a substituent, the structure represented by -C (O) O-R or OC (O) -R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the substituent described above.
As a thioester group which is a substituent, the structure represented by -C (S) O-R or OC (S) -R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the substituent described above.

As a phosphate group which is a substituent, the structure represented by -OP (O)-(OR) ₂ can be shown. R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above.
As the amide group as a substituent, —C (O) NH ₂ , or —C (O) NHR, —NHC (O) R, —C (O) N (R) ₂ , —NRC (O) R The structure represented by can be shown. R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above.

Examples of the aryl group as a substituent include the same aryl groups as described above. The aryl group may be further substituted with the other substituent described above.
Examples of the alkyl group as a substituent include the same alkyl groups as described above. The alkyl group may be further substituted with the other substituent described above.
Examples of the alkenyl group as a substituent include the same alkenyl groups as described above. The alkenyl group may be further substituted with the other substituent described above.
Examples of the alkynyl group that is a substituent include the same alkynyl groups as described above. The alkynyl group may be further substituted with the other substituent described above.

In general, when a bulky structure is introduced, there is a possibility that the reactivity of the amino group and the liquid crystal orientation may be lowered. Therefore, as R ¹ and R ² , a hydrogen atom or a carbon atom that may have a substituent is 1 The alkyl group of ˜5 is more preferable, and a hydrogen atom, a methyl group or an ethyl group is particularly preferable.

In the above formula (AM), examples of specific structures of Y ₁ include Y- ₁ to Y-106 shown below, but are not limited thereto.

<Tetracarboxylic acid derivative>
The tetracarboxylic acid derivative used for the reaction with the diamine compound described above and for synthesizing the polyimide precursor or polyimide that can be contained in the liquid crystal aligning agent of the present invention is not particularly limited.
Examples of the tetracarboxylic acid derivative include tetracarboxylic dianhydride (represented by the following formula (CB1)), tetracarboxylic monoanhydride (represented by the following formula (CB2)), and tetracarboxylic acid (represented by the following formula (CB1)). And a dicarboxylic acid dialkyl ester (represented by the following formula (CB4)), a dicarboxylic acid chloride dialkyl ester (represented by the following formula (CB5)), and the like. As the tetracarboxylic acid derivative, one kind may be used alone, or two or more kinds may be used in combination.

In the above formulas (CB4) and (CB5), R ³ represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 2 carbon atoms.
In the above formulas (CB1) to (CB5), specific examples of Z ₁ include the following formulas (Z-1) to (Z-46).

<Polyimide precursor>
The polyimide precursor contained in the liquid crystal aligning agent of this invention was synthesize | combined using the diamine component which contains diamine compounds, such as said Formula (DA) which has a beta-hydroxyester structure, and said Formula (DIA) as an essential component. Is.
Examples of the polyimide precursor include polyamic acid and polyamic acid ester, and have a structural unit represented by the following formula (PA).

In the above formula (PA), Z is an example of the above-described tetracarboxylic acid derivative, tetracarboxylic dianhydride, tetracarboxylic monoanhydride, tetracarboxylic acid, dicarboxylic acid dialkyl ester, and dicarboxylic acid chloride dialkyl ester. It is a group derived from the Z ₁ group.
R _C is a hydrogen atom or a monovalent organic group derived from the above-described tetracarboxylic acid derivative or esterifying agent described later, preferably having 1 to 5 carbon atoms, more preferably 1 to 2 carbon atoms. Represents an alkyl group.
Wherein (PA), Y is a group derived from Y ₁ groups corresponding other diamine compound represented by the group and the formula (AM) of the diamine compound having the above-described β- hydroxy ester structure. A ₁ and A ₂ represent a hydrogen atom or a monovalent organic group derived from the R ¹ group and the R ² group of the other diamine compound represented by the above formula (AM).

The polyamic acid which is a polyimide precursor of the present invention includes, for example, a diamine component (hereinafter, referred to as a diamine compound having a β-hydroxy ester structure of a diamine compound such as the above formula (DA) or the above formula (DIA) as an essential component. It is simply referred to as a diamine component.) And a tetracarboxylic dianhydride that is a tetracarboxylic acid derivative.
As a reaction method of the diamine component and tetracarboxylic dianhydride for obtaining the polyamic acid contained in the liquid crystal aligning agent of the present invention, a known method can be used. The reaction method is a method in which a diamine component and tetracarboxylic dianhydride are reacted in an organic solvent. The reaction between the diamine component and tetracarboxylic dianhydride is advantageous in that it proceeds relatively easily in an organic solvent and no by-products are generated.

The organic solvent is not particularly limited as long as the generated polyamic acid dissolves. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide , Γ-butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl Carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethyl Glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene Glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n- Hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, Ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropion , 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy -N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like.

The above organic solvents may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the organic solvent as long as the generated polyamic acid does not precipitate.
In addition, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

  When the diamine component and tetracarboxylic dianhydride are reacted in an organic solvent, the solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride is used as it is or in an organic solvent. A method of adding by dispersing or dissolving, a method of adding a diamine component to a solution in which tetracarboxylic dianhydride is dispersed or dissolved in an organic solvent, and alternately adding a tetracarboxylic dianhydride and a diamine component. Any of these methods may be used. Further, when the diamine component or tetracarboxylic dianhydride is composed of a plurality of types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further reacted individually. May be mixed and reacted to form a high molecular weight product.

  Although the reaction (polymerization reaction) temperature can select arbitrary temperature of -20-150 degreeC, Preferably it is -5-100 degreeC. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. It becomes. Therefore, as the reaction concentration, the total concentration of the diamine component and the tetracarboxylic dianhydride in the reaction solution is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.

  In the reaction (polymerization reaction), the ratio of the total number of moles of tetracarboxylic dianhydride and the total number of moles of the diamine component is preferably 0.8 to 1.2. Similar to a normal polycondensation reaction, the closer the molar ratio is to 1.0, the greater the molecular weight of the polyamic acid produced.

<Polyamic acid ester>
Examples of the polyimide precursor that can be contained in the liquid crystal aligning agent of the present invention include polyamic acid and polyamic acid ester as described above. The polyamic acid ester which is a polyimide precursor includes, for example, a diamine component and a tetracarboxylic acid derivative containing a diamine compound having a β-hydroxy ester structure of a diamine compound such as the above formula (DA) or the above formula (DIA) as an essential component. Can be synthesized by the following methods (1) to (3).

(1) Method of synthesizing from polyamic acid The polyamic acid obtained from a diamine component and tetracarboxylic dianhydride can be synthesized by esterification.
Specifically, it is synthesized by reacting a polyamic acid and an esterifying agent in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours. can do.

As the esterifying agent, those that can be easily removed by purification are preferred, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide Dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -Tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like.
The addition amount of the esterifying agent is preferably 2 to 10 molar equivalents and more preferably 2 to 6 molar equivalents per 1 mol of the polyamic acid repeating unit.

The organic solvent used in the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the viewpoint of polymer solubility. These may be used alone or in combination. May be.
The concentration of the polyamic acid during the reaction is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight body is easily obtained.

(2) Method of synthesizing by reaction of tetracarboxylic acid diester dichloride and diamine component It can be synthesized by reaction of tetracarboxylic acid diester dichloride and the above-mentioned diamine component.
Specifically, the tetracarboxylic acid diester dichloride and the diamine component are -20 to 150 ° C., preferably 0 to 50 ° C. in the presence of a base and an organic solvent, for 30 minutes to 24 hours, preferably 1 to 4 hours. It can synthesize | combine by making it react for time.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently.
The addition amount of the base is preferably 2 to 10 times, more preferably 2 to 4 times the amount of tetracarboxylic acid diester dichloride, from the viewpoint of easy removal and high molecular weight. More preferred.

The organic solvent is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of solubility of the monomer and polymer, and these may be used alone or in combination of two or more.
The polymer concentration during the reaction is preferably 1 to 30% by mass and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight body is easily obtained.
In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(3) Method of synthesizing by reaction of tetracarboxylic acid diester and diamine component It can be synthesized by polycondensation of tetracarboxylic acid diester and the above-mentioned diamine component.
Specifically, tetracarboxylic acid diester and the above-mentioned diamine component are added in the presence of a condensing agent, a base, and an organic solvent at 0 ° C. to 150 ° C., preferably at 0 to 100 ° C., for 30 minutes to 24 hours, Preferably, it can be synthesized by reacting for 3 to 15 hours.

Examples of condensing agents include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazinyl. Methylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like can be used.
It is preferable that the addition amount of a condensing agent is 2-10 times mole with respect to tetracarboxylic-acid diester, and 2-3 mole times is more preferable.

As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 10 mol times, more preferably 2 to 4 mol times with respect to the diamine component, from the viewpoint of easy removal and high molecular weight.
In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive.
As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0.1 to 3.0 mol times, more preferably 0.1 to 1.0 mol times relative to the diamine component.

Among the above-mentioned three polyamic acid ester synthesis methods, a high molecular weight polyamic acid ester is obtained, and therefore the synthesis method (1) or (2) is particularly preferable.
The solution of the polyamic acid ester obtained by the above-described method can precipitate a polymer by being poured into a poor solvent while being well stirred. After dissolving and precipitating several times and washing with a poor solvent, purified polyamic acid ester powder can be obtained by drying at room temperature or by heating.
Although it does not specifically limit as a poor solvent, Water, methanol, ethanol, isopropyl alcohol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned, Methanol, ethanol, and isopropyl alcohol are preferable.

<Polyimide>
The liquid crystal aligning agent of this invention contains the at least 1 sort (s) of polymer chosen from the group which consists of the polyimide precursor mentioned above and a polyimide.
As a polyimide, it can be set as the polyimide obtained by carrying out dehydration ring closure of the polyamic acid as a polyimide precursor mentioned above. That is, polyamic acid as a polyimide precursor synthesized using a diamine component containing a diamine compound having a β-hydroxyester structure of a diamine compound such as the above formula (DA) or the above formula (DIA) as an essential component is dehydrated. Obtained by ring closure. The obtained polyimide is useful as a polymer for obtaining the liquid crystal alignment film of the present invention, and is dissolved in a solvent to constitute a liquid crystal aligning agent. By curing the coating film, a cured film made of polyimide is obtained. Can be provided.
In addition, in the polyimide which the liquid crystal aligning agent of this invention contains, the dehydration ring closure rate (imidation rate) of an amic acid group does not necessarily need to be 100%, It can adjust arbitrarily according to a use and the objective. it can.

<Production method of polyimide>
Examples of the method for imidizing a polyamic acid include thermal imidization in which a polyamic acid solution is heated as it is, and catalytic imidation in which a catalyst is added to a polyamic acid solution.
The polyamic acid used for imidation has a β-hydroxy ester structure derived from a diamine compound having a β-hydroxy ester structure used at the time of synthesis. Therefore, as a method for polyimidizing the polyamic acid, catalytic imidation that allows a reaction at a relatively low temperature is desirable so that the β-hydroxyester structure inside the polyamic acid can be maintained.

The catalytic imidation of the polyamic acid can be performed by adding a basic catalyst and an acid anhydride to the polyamic acid solution and stirring at -20 to 250 ° C, preferably 0 to 180 ° C.
The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times of the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times of the amido group, preferably 3 to 3 times. 30 mole times.
Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction.

Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Of these, use of acetic anhydride is preferred because purification after completion of the reaction is facilitated.
The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.
As mentioned above, although the component which can be contained in the liquid crystal aligning agent of this invention was demonstrated, the liquid crystal aligning agent of this invention prepared using those components is demonstrated next.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of this invention is a coating liquid for forming a liquid crystal aligning film, and is a solution which the resin component for forming a resin film melt | dissolved in the organic solvent. Here, the resin component includes at least one polymer selected from the group consisting of the polyimide precursor and polyimide described above.
As for content of a resin component, 1-20 mass% is preferable, More preferably, it is 3-15 mass%, More preferably, it is 3-10 mass%.
In the present invention, the resin component may be all the above-described polymers, or other polymers may be mixed. In that case, content of other polymers other than the polymer mentioned in the resin component is 0.5-15 mass%, Preferably it is 1-10 mass%.

The organic solvent used for the liquid crystal aligning agent of this invention will not be specifically limited if it is an organic solvent in which the resin component containing the polymer etc. which were mentioned above is dissolved. Specific examples are given below.
N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, Dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3 -Dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4 Methyl-2-pentanone and the like.
These may be used alone or in combination.

The liquid crystal aligning agent of this invention may contain components other than the above. Examples thereof include solvents and compounds that improve the film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, and compounds that improve the adhesion between the liquid crystal aligning film and the substrate.
The following are mentioned as a specific example of the solvent (poor solvent) which improves the uniformity of film thickness and surface smoothness.

  For example, isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoacetate Isopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipro Lenglycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3 -Methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl Ether, 1-hexanol, n-hexane, n-pentane, n-octane Diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, Ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1 -Butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol- Low 1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate isoamyl ester Examples include solvents having surface tension.

  These poor solvents may be used alone or in combination. When using the above solvent, it is preferable that it is 5-80 mass% of the whole solvent contained in a liquid crystal aligning agent, More preferably, it is 20-60 mass%.

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.
More specifically, for example, EFTOP (registered trademark) EF301, EF303, EF352 (manufactured by Tochem Products), MegaFac (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.) and the like.
The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent.

Specific examples of the compound for improving the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds.
For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy Carbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-to Ethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-amino Propyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetra Glycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N',-tetraglycidyl-4,4'-diaminodiphenylmethane and the like.

  When using the compound which improves adhesiveness with a board | substrate, it is preferable that the usage-amount is 0.1-30 mass parts with respect to 100 mass parts of the resin component contained in a liquid-crystal aligning agent, and more. Preferably it is 1-20 mass parts. If the amount used is less than 0.1 parts by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the liquid crystal alignment of the liquid crystal alignment film to be formed may be lowered.

In addition to the above, the liquid crystal aligning agent of the present invention has a dielectric or conductive material for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, as long as the effects of the present invention are not impaired. Further, a crosslinkable compound for the purpose of increasing the hardness and density of the liquid crystal alignment film may be added.
Next, the liquid crystal alignment film of the present invention and the liquid crystal display element having the liquid crystal alignment film will be described.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal aligning agent of this invention is the polyimide precursor synthesize | combined using the diamine component which contains the diamine compound which has (beta) -hydroxyester structure of diamine compounds, such as said formula (DA) and said formula (DIA), as an essential component. And at least one polymer selected from the group consisting of polyimide and polyimide. The liquid crystal aligning agent is preferably filtered before being applied to the substrate, then applied, dried by pre-baking, and then heated and fired to form a polyimide film.
When baking with heat, the polyimide precursor and / or polyimide contained in the liquid crystal aligning agent of the present invention has a β-hydroxy ester structure in the molecule, so that a photoreactive double bond is formed in the molecule. Can be formed.

That is, in the liquid crystal aligning agent of the present invention, when the coating film of the liquid crystal aligning agent is heated and baked to perform the imidization reaction of the polyimide precursor component, a dehydration reaction is simultaneously performed in the β-hydroxyester structure part, A photoreactive double bond can be introduced into the polyimide film.
In addition, in the liquid crystal aligning agent of the present invention containing polyimide, when a polyimide film is formed by heating and baking a coating film obtained by applying and drying the liquid crystal aligning agent, dehydration is simultaneously performed in the β-hydroxyester structure part. The reaction takes place and photoreactive double bonds can be introduced into the polyimide film.

  As described above, the liquid crystal aligning agent of the present invention can form a polyimide film and introduce a double bond by heating and baking the coating obtained by applying and drying the liquid crystal aligning agent. For example, a photoreactive site such as a cinnamic acid ester structure can be introduced. As a result, in the liquid crystal alignment film using the polyimide film formed from the liquid crystal aligning agent of this invention containing a polyimide precursor and / or a polyimide, photo-alignment property is realizable.

When applying the liquid crystal aligning agent of this invention to a board | substrate, a highly transparent board | substrate can be used as a board | substrate to be used.
As the substrate, for example, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate.
When using the liquid crystal aligning agent of this invention in manufacture of a liquid crystal display element, it is preferable to form a liquid crystal aligning film using the board | substrate with which the ITO (Indium Tin Oxide) electrode etc. for a liquid crystal drive were formed. In the case of manufacturing a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum is used for the electrode. You can also

Although it does not specifically limit as a coating method which apply | coats a liquid crystal aligning agent on a board | substrate, Industrially, screen printing, offset printing, flexographic printing, the inkjet method etc. are common. As other coating methods, there are a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, and the like, and these may be used according to the purpose.
The liquid crystal aligning agent of the present invention has good coating properties even when the above coating method is used.

A drying step by pre-baking after applying the liquid crystal aligning agent is not necessarily required, but if the time from application to heating and baking is not constant for each substrate, or if heating and baking is not performed immediately after application, drying is performed. It is preferable to include a process. The drying by this pre-bake should just evaporate the solvent to such an extent that a coating-film shape does not deform | transform by conveyance of a board | substrate. Moreover, it is preferable to carry out in the temperature range in which a dehydration reaction does not occur in the β-hydroxyester structure of the polyimide precursor and / or polyimide contained in the liquid crystal aligning agent.
The drying means by pre-baking is not particularly limited. As a specific example, a method of drying on a hot plate at 50 to 120 ° C., preferably 80 to 120 ° C. for 0.5 to 30 minutes, preferably 1 to 5 minutes is preferable.

  Firing of the substrate coated with the liquid crystal aligning agent can be performed at a temperature of 120 to 350 ° C. by a heating means such as a hot plate, a thermal circulation oven, or an IR (infrared) oven. The baking temperature is a temperature suitable for forming a polyimide film, and a temperature at which a dehydration reaction proceeds is selected in the polyimide precursor and / or the β-hydroxyester structure of the polyimide contained in the liquid crystal aligning agent. The firing temperature is preferably 140 to 300 ° C, more preferably 180 to 250 ° C. However, firing is preferably performed at a temperature higher by 10 ° C. or more than the heat treatment temperature required for the manufacturing process of the liquid crystal display element such as sealing agent curing.

  If the thickness of the polyimide film obtained after firing is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered. Is 50-100 nm.

The polyimide film formed on the substrate as described above is subjected to photo-alignment treatment, and the liquid crystal alignment film of the present invention is formed.
The method of the photo-alignment treatment is not particularly limited, but it is preferable to use polarized ultraviolet rays for obtaining uniform liquid crystal alignment. In this case, the method of irradiating polarized ultraviolet rays is not particularly limited. For example, it is possible to irradiate a substrate on which a polyimide film is formed with polarized ultraviolet rays through a polarizing plate from a certain direction. Moreover, you may irradiate twice or more, changing the incident angle of the polarized ultraviolet-ray. Further, if polarized light can be obtained substantially, non-polarized ultraviolet rays may be irradiated at a certain angle from the normal line of the substrate.

As the wavelength of the ultraviolet rays to be used, ultraviolet rays in the range of generally 100 to 400 nm, preferably 250 to 370 nm can be used, but particularly preferably, the optimum wavelength is selected through a filter or the like depending on the type of polyimide used. It is preferable to select.
The irradiation amount of ultraviolet rays is generally several mJ / cm ² ~ number J / cm ^2, preferably in the range of ^{5mJ / cm 2 ~500mJ / cm 2} . In particular, considering the possibility of causing a decrease in the voltage holding ratio of a liquid crystal display device manufactured thereafter due to industrial productivity and an increase in irradiation amount, a necessary amount that can provide good orientation is used. It is preferable to select according to the type of polyimide.

The liquid crystal aligning agent of the present invention can form a vertical alignment type photo-alignment liquid crystal alignment film on a substrate by the method described above. The formed liquid crystal alignment film can be photo-aligned, and in the rubbing process, which is a conventional alignment processing method, the problem of dust generated when the liquid crystal alignment film is scraped and scratches on the liquid crystal alignment film are liquid crystal. The problem of reducing the display quality of the display element can be reduced.
After the liquid crystal aligning agent of this invention forms a liquid crystal aligning film on a board | substrate by an above-described method, a liquid crystal display element can be manufactured by a well-known method using this board | substrate with a liquid crystal aligning film.

An example of manufacturing a liquid crystal display element will be described below.
A pair of substrates on which a vertical alignment type liquid crystal alignment film is formed using the liquid crystal alignment agent of the present invention is prepared. Next, it is preferably placed so that the projection direction of the optical axis of the polarized ultraviolet light irradiated on each substrate is antiparallel, for example, with a spacer of 1 to 30 μm, more preferably 2 to 10 μm sandwiched between them. Fix with sealant. Next, liquid crystal is injected between the substrates and sealed. The method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method in which liquid crystal is injected after reducing the pressure inside the manufactured liquid crystal cell, and a dropping method in which sealing is performed after dropping the liquid crystal.

The manufactured liquid crystal display element has the liquid crystal aligning film formed from the liquid crystal aligning agent of this invention, and this liquid crystal display element can comprise a VA system liquid crystal display element.
The liquid crystal display element of the present invention has no deterioration in display quality due to scratches on the liquid crystal alignment film, has excellent display quality, and has high reliability.

The following examples further illustrate the present invention. The present invention is not construed as being limited to these.
The structures and abbreviations of main compounds used in Examples and Comparative Examples are as follows.
The diamine compound (DA-1-1) is an example of a diamine compound represented by the formula (DA-1) described above. The diamine compound (DAM-1) is a conventional diamine compound having a cinnamic acid ester structure in the molecule.
<Structural formulas and abbreviations>

<Tetracarboxylic acid derivative>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride PMDA: pyromellitic dianhydride <diamine compound>
DA-1-1: 3,5-diaminobenzyl 3- (4- (decyloxy) phenyl) -3-hydroxypropanoate DAM-1: (E) -3,5-diaminobenzyl 3- (4- (decyloxy) Phenyl) acrylate DMAP: N, N′-dimethyl-4-aminopyridine <solvent>
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve DMF: N, N′-dimethylformamide

  In Examples 1 to 6, compounds [2] to [7] were synthesized according to the reaction formulas (1) to (6) exemplified. The obtained compound [7] was used for the synthesis of a diamine compound (DA-1-1).

４−ヒドロキシ安息香酸エチル［１］（１９．９ｇ、０．１２０ｍｏｌ）と、１−ブロモデカン（２２．１ｇ、０．１００ｍｏｌ）と、炭酸カリウム（２７．６ｇ、０．２００ｍｏｌ）とジメチルホルムアミド１２０ｇを四つ口フラスコ中に添加し、窒素雰囲気下で攪拌し、８０℃に昇温した。４時間攪拌した後、^１Ｈ−ＮＭＲ（ｎｕｃｌｅａｒ ｍａｇｎｅｔｉｃ ｒｅｓｏｎａｎｃｅ：核磁気共鳴）法により、反応液中の１−ブロモデカンの消失を確認した。その後、溶媒を留去し、トルエンと２規定のＮａＯＨ水溶液にて水洗操作を実施し、水層を除去した。得られた有機層を、純水で２回水洗し、得られた有機層を無水硫酸マグネシウムにて乾燥した。乾燥後、硫酸マグネシウムをろ取し、得られた有機層を減圧下、溶媒を留去して、化合物［２］を得た（収量２７．７ｇ、０．０９０ｍｏｌ、収率９０．３％）。
化合物［２］の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（溶媒；ＣＤＣｌ_３）：δ７．９８（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），６．８９（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），４．３４（ｑ，２Ｈ，Ｊ＝７．２Ｈｚ），３．９９（ｔ，２Ｈ，Ｊ＝６．８Ｈｚ），１．８２−１．７５（ｍ，２Ｈ），１．４７−１．２６（ｍ，１７Ｈ），０．８９（ｔ，３Ｈ，Ｊ＝６．８Ｈｚ）．<Example 1>

Ethyl 4-hydroxybenzoate [1] (19.9 g, 0.120 mol), 1-bromodecane (22.1 g, 0.100 mol), potassium carbonate (27.6 g, 0.200 mol) and dimethylformamide 120 g. The mixture was added to a four-necked flask, stirred under a nitrogen atmosphere, and heated to 80 ° C. After stirring for 4 hours, disappearance of 1-bromodecane in the reaction solution was confirmed by ¹ H-NMR (nuclear magnetic resonance) method. Thereafter, the solvent was distilled off, and a water washing operation was performed with toluene and a 2N NaOH aqueous solution, and the aqueous layer was removed. The obtained organic layer was washed twice with pure water, and the obtained organic layer was dried over anhydrous magnesium sulfate. After drying, magnesium sulfate was filtered off, and the resulting organic layer was evaporated under reduced pressure to remove the solvent to obtain compound [2] (yield 27.7 g, 0.090 mol, yield 90.3%). .
The structure of the compound [2] was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (solvent; CDCl ₃ ): δ 7.98 (d, 2H, J = 10.8 Hz), 6.89 (d, 2H, J = 10.8 Hz), 4.34 (q, 2H, J = 7.2 Hz), 3.99 (t, 2H, J = 6.8 Hz), 1.82-1.75 (m, 2H), 1.47-1.26 (m, 17H), 0.89 (T, 3H, J = 6.8 Hz).

化合物［２］（１０．８ｇ、０．０３５４ｍｏｌ）と、水酸化カリウム（１０．０ｇ）と、エタノール１１８ｇと水２０．０ｇを、四つ口フラスコ中に添加し、室温で３日間攪拌した。その後、さらに８０℃に加温して１時間攪拌した。その溶液を冷却し、ＨＰＬＣ（Ｈｉｇｈ ｐｅｒｆｏｒｍａｎｃｅ ｌｉｑｕｉｄ ｃｈｒｏｍａｔｏｇｒａｐｈｙ：高速液体クロマトグラフィ）にて原料の消失を確認した。その後、１２規定塩酸水溶液１８ｍｌを氷浴下で加えて、さらに攪拌した。次いで、水３００ｇを加えて結晶を析出させた。結晶をろ取した後、結晶を乾燥させて化合物［３］を得た（収量９．０５ｇ、０．０３２５ｍｏｌ、収率９１．８％）。
化合物［３］の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（溶媒；ＣＤＣｌ_３）：δ８．０５（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），６．９３（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），４．０３（ｔ，２Ｈ，Ｊ＝６．８Ｈｚ），１．８４−１．７７（ｍ，２Ｈ），１．４８−１．２８（ｍ，１４Ｈ），０．８９（ｔ，３Ｈ，Ｊ＝６．８Ｈｚ）．<Example 2>

Compound [2] (10.8 g, 0.0354 mol), potassium hydroxide (10.0 g), 118 g of ethanol and 20.0 g of water were added to a four-necked flask and stirred at room temperature for 3 days. Thereafter, the mixture was further heated to 80 ° C. and stirred for 1 hour. The solution was cooled, and disappearance of the raw material was confirmed by HPLC (High performance liquid chromatography: high performance liquid chromatography). Thereafter, 18 ml of 12N hydrochloric acid aqueous solution was added in an ice bath and further stirred. Next, 300 g of water was added to precipitate crystals. After the crystals were collected by filtration, the crystals were dried to obtain compound [3] (yield 9.05 g, 0.0325 mol, yield 91.8%).
The structure of the compound [3] was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (solvent: CDCl ₃ ): δ 8.05 (d, 2H, J = 10.8 Hz), 6.93 (d, 2H, J = 10.8 Hz), 4.03 (t, 2H, J = 6.8 Hz), 1.84-1.77 (m, 2H), 1.48-1.28 (m, 14H), 0.89 (t, 3H, J = 6.8 Hz).

化合物［３］（５２．２ｇ、０．１８８ｍｏｌ）と、テトラヒドロフラン２００ｍｌとＤＭＦ（５．１９ｇ）を、四つ口フラスコ中に添加し、その溶液にオキザリルクロリド（３９．５ｇ、０．３１１ｍｏｌ）をゆっくり滴下した。４時間室温で攪拌した後、溶媒を留去し、化合物［４］の酸クロリド体の粗物を得た。また、予めメルドラム酸（２１．６ｇ、０．１５０ｍｏｌ）と、Ｎ，Ｎ−ジメチル−４−アミノピリジン（３６．７ｇ、０．３００ｍｏｌ）と、ジクロロメタン２５０ｍｌとを添加してある四つ口フラスコ中へ、化合物［４］の粗物を溶解しているジクロロメタン１２０ｍｌを、シリンジを用いてゆっくり滴下し、氷浴下１時間攪拌した。その後、室温で１５時間攪拌した。反応終了後、クロロホルム３００ｍｌと２規定塩酸水溶液３００ｍｌを加えて溶液中の塩基を塩として水に溶解させて除去し、さらに純水で３回有機層を洗浄した。得られた有機層を無水硫酸マグネシウムで乾燥し、硫酸マグネシウムをろ取した後、得られた有機層を減圧下、溶媒を留去し、化合物［５］の粗物を得た（収量７２．７ｇ、収率９５．８％）。
化合物［５］の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（溶媒；ＣＤＣｌ_３）：δ８．０９−８．０３（ｍ，２Ｈ），６．９８−６．９１（ｍ，２Ｈ），４．０３（ｑ，２Ｈ，Ｊ＝６．８Ｈｚ），３．６４（ｓ，１Ｈ，），１．８６−１．７７（ｍ，８Ｈ），１．４８−１．２４（ｍ，１４Ｈ），０．８９（ｔ，３Ｈ，Ｊ＝６．８Ｈｚ）．<Example 3>

Compound [3] (52.2 g, 0.188 mol), 200 ml of tetrahydrofuran and DMF (5.19 g) were added into a four-necked flask, and oxalyl chloride (39.5 g, 0.311 mol) was added to the solution. Was slowly added dropwise. After stirring at room temperature for 4 hours, the solvent was distilled off to obtain a crude acid chloride of compound [4]. In a four-necked flask to which Meldrum's acid (21.6 g, 0.150 mol), N, N-dimethyl-4-aminopyridine (36.7 g, 0.300 mol), and 250 ml of dichloromethane were added in advance. To the solution, 120 ml of dichloromethane in which the crude product of compound [4] was dissolved was slowly added dropwise using a syringe and stirred for 1 hour in an ice bath. Then, it stirred at room temperature for 15 hours. After completion of the reaction, 300 ml of chloroform and 300 ml of 2N aqueous hydrochloric acid were added to dissolve and remove the base in the solution as a salt in water, and the organic layer was washed three times with pure water. The obtained organic layer was dried over anhydrous magnesium sulfate, and magnesium sulfate was collected by filtration. Then, the solvent was distilled off from the obtained organic layer under reduced pressure to obtain a crude product of compound [5] (yield 72. 7 g, yield 95.8%).
The structure of the compound [5] was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (solvent; CDCl ₃ ): δ 8.09-8.03 (m, 2H), 6.98-6.91 (m, 2H), 4.03 (q, 2H, J = 6.8 Hz) ), 3.64 (s, 1H,), 1.86-1.77 (m, 8H), 1.48-1.24 (m, 14H), 0.89 (t, 3H, J = 6. 8 Hz).

化合物［５］（７２．７ｇ）と、３，５−ジニトロベンジルアルコール（２９．７ｇ、０．１５０ｍｏｌ）と脱水アセトニトリル４５０ｇを、四つ口フラスコ中に添加し、７０℃で加熱攪拌した。攪拌を２時間行った後、ＨＰＬＣで原料の消失と、ガス（二酸化炭素を含むガス）の発生が終了したことを確認し、その後溶媒を濃縮した。濃縮物にメタノール４５０ｍｌを加えて結晶を析出させ、結晶をろ取した。得られた結晶をシリカゲルのカラムクロマトグラフィーで精製（溶出溶媒：ヘキサン：酢酸エチル＝４：１（容量比））し、目的の化合物［６］を得た（収量３０．８ｇ、０．０６１５ｍｏｌ，収率４１．０％）。
化合物［６］の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（様ない；ＣＤＣｌ_３）：δ８．９９（ｓ，１Ｈ），８．５４（ｓ，２Ｈ），７．８９（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），６．９２（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），５．３９（ｓ，２Ｈ），４．０９（ｓ，２Ｈ），４．０２（ｔ，２Ｈ，Ｊ＝６．４Ｈｚ），１．８５−１．７８（ｍ，２Ｈ），１．５０−１．２８（ｍ，１４Ｈ），０．８８（ｔ，３Ｈ，Ｊ＝６．８Ｈｚ）．<Example 4>

Compound [5] (72.7 g), 3,5-dinitrobenzyl alcohol (29.7 g, 0.150 mol) and 450 g of dehydrated acetonitrile were added to a four-necked flask and heated and stirred at 70 ° C. After stirring for 2 hours, it was confirmed by HPLC that the disappearance of the raw materials and the generation of gas (gas containing carbon dioxide) were completed, and then the solvent was concentrated. 450 ml of methanol was added to the concentrate to precipitate crystals, and the crystals were collected by filtration. The obtained crystals were purified by silica gel column chromatography (elution solvent: hexane: ethyl acetate = 4: 1 (volume ratio)) to obtain the target compound [6] (yield 30.8 g, 0.0615 mol, Yield 41.0%).
The structure of the compound [6] was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (not shown; CDCl ₃ ): δ 8.99 (s, 1H), 8.54 (s, 2H), 7.89 (d, 2H, J = 10.8 Hz), 6.92 (d , 2H, J = 10.8 Hz), 5.39 (s, 2H), 4.09 (s, 2H), 4.02 (t, 2H, J = 6.4 Hz), 1.85-1.78. (M, 2H), 1.50-1.28 (m, 14H), 0.88 (t, 3H, J = 6.8 Hz).

化合物［６］（２９．９ｇ、０．０５９７ｍｏｌ）と、白金カーボン粉末（３％）７．５４ｇとテトラヒドロフラン２６０ｇを、四つ口フラスコ中に添加し、水素ガス雰囲気下、室温で２１時間攪拌した。原料である化合物［６］の消失をＨＰＬＣで確認した後、^１Ｈ−ＮＭＲにより、主生成物が目的物であることを確認した。その後、反応液をろ過し、白金カーボン粉末を取り除いた。得られたろ液を濃縮し、メタノール３００ｍｌで１回のスラリー洗浄を行った。次いで、結晶をろ取し、乾燥させて化合物［７］を得た（収量１４．１ｇ、０．０３２０ｍｏｌ，収率５３．６％）。
化合物［７］の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（溶媒；ＣＤＣｌ_３）：δ７．９０（ｄ，２Ｈ，Ｊ＝８．８Ｈｚ），６．９２（ｄ，２Ｈ，Ｊ＝８．８Ｈｚ），６．０４−５．９６（ｍ，２Ｈ），５．９６（ｓ，１Ｈ），５．００（ｓ，２Ｈ），４．０３−３．９９（ｍ，４Ｈ），３．５７−３．４９（ｂｒｏａｄ，４Ｈ），１．８２−１．７７（ｍ，２Ｈ），１．４７−１．２８（ｍ，１４Ｈ），０．８８（ｔ，３Ｈ，Ｊ＝６．８Hz)．<Example 5>

Compound [6] (29.9 g, 0.0597 mol), 7.54 g of platinum carbon powder (3%) and 260 g of tetrahydrofuran were added to a four-necked flask and stirred at room temperature for 21 hours in a hydrogen gas atmosphere. . After confirming disappearance of the starting compound [6] by HPLC, it was confirmed by ¹ H-NMR that the main product was the target product. Thereafter, the reaction solution was filtered to remove platinum carbon powder. The obtained filtrate was concentrated and washed once with 300 ml of methanol. Next, the crystals were collected by filtration and dried to obtain compound [7] (yield 14.1 g, 0.0320 mol, yield 53.6%).
The structure of the compound [7] was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (solvent: CDCl ₃ ): δ 7.90 (d, 2H, J = 8.8 Hz), 6.92 (d, 2H, J = 8.8 Hz), 6.04-5.96 (m , 2H), 5.96 (s, 1H), 5.00 (s, 2H), 4.03-3.99 (m, 4H), 3.57-3.49 (road, 4H), 1. 82-1.77 (m, 2H), 1.47-1.28 (m, 14H), 0.88 (t, 3H, J = 6.8 Hz).

化合物［７］（１１．６ｇ、０．０２６３ｍｏｌ）と、テトラヒドロフラン５０．０ｇとエタノール５０．０ｇを、四つ口フラスコ中に添加し、０℃に冷却した。その後、ＮａＢＨ_４（１．００ｇ、０．０２６４ｍｏｌ）を加えて１５分攪拌した後、さらに追加のＮａＢＨ_４（０．３８４ｇ、０．０１０２ｍｏｌ）を少しずつ加えて４０分攪拌を行った。原料である化合物［７］の減少が停止したのを、ＨＰＬＣにより確認した後、テトラヒドロフラン１８ｍｌと飽和塩化アンモニウム水溶液をゆっくり加え、反応を停止（クエンチ）させた。反応液からの発熱が見られなくなったのを、反応液中にさしこんだ温度計により確認し、さらにテトラヒドロフラン４００ｍｌと飽和塩化アンモニウム水溶液を３００ｍｌ加えて、有機層と水層の２層に分離させた。２層を分離後、有機層を無水硫酸マグネシウムにて乾燥し、その後硫酸マグネシウムをろ取した。得られた有機層を減圧下、溶媒を留去した。得られた結晶のメタノール１００ｇによるスラリー洗浄を１回実施し、結晶をろ取して、さらに乾燥させ、ジアミン化合物（ＤＡ−１−１）を得た（収量５．９３ｇ、０．０１３４ｍｏｌ，収率５１．０％）。
ジアミン化合物（ＤＡ−１−１）の構造は、^１Ｈ−ＮＭＲ分析により以下のスペクトルデータを得て確認した。
^１Ｈ−ＮＭＲ（ＣＤＣｌ_３）:δ７．２７（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），６．８７（ｄ，２Ｈ，Ｊ＝１０．８Ｈｚ），６．０４（ｓ，２Ｈ），５．９７（ｓ，１Ｈ），５．１１−５．０８（ｍ，１Ｈ），４．９６（Ｓ，２Ｈ），３．９４（ｔ，２Ｈ，Ｊ＝６．８Ｈｚ），３．５６（ｂｒｏａｄ，４Ｈ），３．１５（ｂｒｏａｄ，１Ｈ），２．８５−２．７０（ｍ，２Ｈ），１．８０−１．７３（ｍ，２Ｈ），１．４６−１．２７（ｍ，１４Ｈ），０．８８（ｔ，３Ｈ，Ｊ＝６．８Ｈｚ）。<Example 6>

Compound [7] (11.6 g, 0.0263 mol), 50.0 g of tetrahydrofuran and 50.0 g of ethanol were added to a four-necked flask and cooled to 0 ° C. _Then, NaBH 4 _{(1.00g, 0.0264mol)} was stirred for 15 minutes by the addition of further additional NaBH ₄ (0.384g, 0.0102mol) was subjected to 40 minutes stirring was added little by little. After confirming by HPLC that the reduction of the starting compound [7] stopped, 18 ml of tetrahydrofuran and a saturated aqueous ammonium chloride solution were slowly added to stop the reaction. It was confirmed that heat generation from the reaction solution was stopped with a thermometer inserted in the reaction solution, and further 400 ml of tetrahydrofuran and 300 ml of saturated aqueous ammonium chloride solution were added to separate the organic layer and the aqueous layer into two layers. I let you. After separating the two layers, the organic layer was dried over anhydrous magnesium sulfate, and then magnesium sulfate was collected by filtration. The solvent was distilled off from the obtained organic layer under reduced pressure. The obtained crystals were washed once with 100 g of methanol, and the crystals were collected by filtration and further dried to obtain a diamine compound (DA-1-1) (yield 5.93 g, 0.0134 mol, yield). Rate 51.0%).
The structure of the diamine compound (DA-1-1) was confirmed by obtaining the following spectral data by ¹ H-NMR analysis.
¹ H-NMR (CDCl ₃ ): δ 7.27 (d, 2H, J = 10.8 Hz), 6.87 (d, 2H, J = 10.8 Hz), 6.04 (s, 2H), 5. 97 (s, 1H), 5.11-5.08 (m, 1H), 4.96 (S, 2H), 3.94 (t, 2H, J = 6.8 Hz), 3.56 (broad, 4H), 3.15 (road, 1H), 2.85-2.70 (m, 2H), 1.80-1.73 (m, 2H), 1.46-1.27 (m, 14H) , 0.88 (t, 3H, J = 6.8 Hz).

<Example 7>
CBDA (0.471 g, 2.40 mmol) and diamine compound (DA-1-1) (1.17 g, 2.5 mmol) were mixed in NMP (8.94 g) and reacted at room temperature for 10 hours to obtain polyamic acid. A solution was obtained. NMP (7.89 g) and BC (7.89 g) were added to the polyamic acid solution and diluted to 6% by mass. Subsequently, the liquid crystal aligning agent (A1) was obtained by stirring at room temperature for 5 hours. The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (A1) was 6700, and the weight average molecular weight was 24400.

<Example 8>
PMDA (0.518 g, 2.40 mmol) and DA-1-1 (1.17 g, 2.5 mmol) were mixed in NMP (10.83 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. . NMP (8.12 g) and BC (8.12 g) were added to this polyamic acid solution, and diluted to 6% by mass. Subsequently, the liquid crystal aligning agent (A2) was obtained by stirring at room temperature for 5 hours. The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (A2) was 8500, and the weight average molecular weight was 24500.

<Comparative Example 1>
CBDA (0.577 g, 2.9 mmol) and DAM-1 (1.274 g, 3.0 mmol) were mixed in NMP (10.48 g) and reacted at room temperature for 10 hours to obtain a polyamic acid solution. NMP (9.25 g) and BC (9.25 g) were added to the polyamic acid solution and diluted to 6% by mass. Subsequently, the liquid crystal aligning agent (A3) which is a comparative example was obtained by stirring at room temperature for 5 hours. The number average molecular weight of the polyamic acid contained in the liquid crystal aligning agent (A3) was 9700, and the weight average molecular weight was 19,200.

The molecular weight of the polyamic acid obtained in Example 7, Example 8 and Comparative Example 1 was measured as follows.
[Measurement of molecular weight]
It measured as follows using the normal temperature gel permeation chromatography (GPC) apparatus (SSC-7200) by a Senshu scientific company, and the column (KD-803, KD-805) by Shodex.
Column temperature: 50 ° C
Eluent: N, N′-dimethylformamide (as additives, lithium bromide-hydrate (LiBr · H ₂ O) is 30 mmol / L (liter), phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, 10 ml / L of tetrahydrofuran (THF))
Flow rate: 1.0 mL / min Standard sample for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: about 9000000, 150,000, 100,000, and 30000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weight: about 12000, 4000, and 1000) manufactured by Polymer Laboratory ).

<Example 9>
With respect to the cured film formed using the liquid crystal aligning agent (A1) obtained in Example 7, the ultraviolet (UV) absorption spectrum was measured and the coating property was evaluated as described below.
Also, each liquid crystal cell having a cured film (polyimide film) formed using the liquid crystal aligning agent (A1) obtained in Example 7 and having linearly polarized light irradiation doses of 0 mJ, 20 mJ, 50 mJ, and 100 mJ, respectively. Was prepared by the following method, and the pretilt angle was evaluated.

[Measurement of ultraviolet (UV) absorption spectrum]
The liquid crystal aligning agent (A1) obtained in Example 7 was spin-coated on a quartz substrate, dried on a hot plate at 80 ° C. for 90 seconds, and then baked in a hot air circulation oven at 200 ° C. for 30 minutes to obtain a film thickness of 100 nm. The polyimide film was formed. At this time, using this substrate, using a UV absorption spectrum measuring instrument (UV-3600) manufactured by Shimadzu Corporation, before baking in a hot air circulation oven at 200 ° C. for 30 minutes (also referred to as “before baking”). Also called “after firing”. The UV absorption spectrum was measured.
In FIG. 1, the measurement result of the UV absorption spectrum before and behind baking was shown.

Next, a substrate after being baked in a hot air circulation oven at 200 ° C. for 30 minutes was irradiated with 300 mJ and 1 J (1000 mJ) of 313 nm linearly polarized light with an irradiation intensity of 11.0 mW / cm ⁻² . . The direction of incident light was inclined by 40 ° with respect to the normal direction of the substrate. The linearly polarized light was adjusted by passing a 313 nm polarizing plate through a 313 nm bandpass filter through the ultraviolet light of a high-pressure mercury lamp. And the UV absorption spectrum was measured by the method mentioned above using the board | substrate with which 300 mJ and 1J (1000mJ) linearly polarized light were irradiated. The measurement result of the UV absorption spectrum is shown in FIG.

In FIG. 3, the UV absorption spectrum obtained as described above is labeled “300 mJ” and is shown in FIG. 3 together with the UV absorption spectrum after firing shown in FIG. 1.
The substrate used for measurement of the UV absorption spectrum after firing shown in FIG. 1 is not irradiated with linearly polarized light as described above. Therefore, this corresponds to the case where the irradiation amount of linearly polarized light is 0 mJ, and in FIG. 3, “0 mJ” is indicated.

[Evaluation of applicability]
The liquid crystal aligning agent (A1) obtained in Example 7 was spin-coated on the ITO electrode surface of a glass substrate with an ITO electrode made of an ITO film, dried on a hot plate at 80 ° C. for 90 seconds, and the coated surface was observed. The applicability of the liquid crystal aligning agent (A1) was evaluated as “bad” when unevenness or repellency occurred on the coated surface and “good” when uniform without repellency or unevenness.

[Production of liquid crystal cell]
Using the liquid crystal aligning agent (A1) obtained in Example 7, a liquid crystal cell as a liquid place display element was produced as follows.
The liquid crystal aligning agent (A1) obtained in Example 7 was spin coated on the ITO electrode surface of a glass substrate with an ITO electrode made of an ITO film, dried on a hot plate at 80 ° C. for 90 seconds, and then heated at 200 ° C. for circulating hot air. Baking was performed for 30 minutes in a type oven to form a polyimide film having a thickness of 100 nm.
This substrate was irradiated with 20 mJ of 313 nm linearly polarized light having an irradiation intensity of 11.0 mW / cm ⁻² . In the above-described measurement of the UV absorption spectrum, the direction of the incident light was inclined by 40 ° with respect to the normal direction of the substrate, similarly to the irradiation with linearly polarized light. This linearly polarized light was prepared by passing a 313 nm bandpass filter through the ultraviolet light of a high-pressure mercury lamp and then passing it through a 313 nm polarizing plate.

Two substrates were prepared, and 6 μm bead spacers were sprayed on the liquid crystal alignment film of one substrate, and then a sealant was printed thereon. Next, the liquid crystal alignment surfaces of the two substrates are made to face each other, and pressure-bonded so that the projection direction of the optical axis of the linearly polarized light on each substrate is antiparallel, and a sealant (manufactured by Kyoritsu Chemical Co., Ltd.) is taken at 150 ° C. for 105 minutes. XN-1500T) was heat cured. A negative liquid crystal having negative dielectric anisotropy (MLC, MLC-6608) having a negative dielectric anisotropy was injected into this empty cell by a reduced pressure injection method, and a liquid crystal cell having a linear polarized light irradiation amount of 20 mJ was produced.
Next, a liquid crystal cell having a linearly polarized light irradiation amount of 50 mJ was produced in the same manner as described above except that the linearly polarized light irradiation amount was 50 mJ.
In addition, a liquid crystal cell having a linearly polarized light irradiation amount of 100 mJ was produced in the same manner as described above except that the linearly polarized light irradiation amount was 100 mJ.
Further, a liquid crystal cell having a linearly polarized light irradiation amount of 0 mJ was produced in the same manner as described above except that the linearly polarized light was not irradiated.

[Evaluation of pretilt angle]
Using each liquid crystal cell with a different amount of linearly polarized light, the pretilt angle in the liquid crystal alignment was measured. The pretilt angle was measured by the Mueller matrix method using “Axo Scan” manufactured by Axo Metrix.
In the measurement result of the pretilt angle, in the liquid crystal cell in which the irradiation amount of the linearly polarized light is 20 mJ, the pretilt angle is 89.1 degrees, and the liquid crystal molecules are slightly shifted from the normal direction of the substrate toward one direction in the substrate surface. It was tilted and oriented.
On the other hand, in the liquid crystal cell in which the irradiation amount of linearly polarized light was 0 mJ, the pretilt angle was 90.0 degrees, and the liquid crystal molecules were aligned in the normal direction of the substrate, and were not tilted.
The above evaluation results are shown in Table 1 together with the results of Example 10 and Comparative Example 2.

<Example 10>
About the cured film obtained using the liquid crystal aligning agent (A2) obtained in Example 2, the ultraviolet (UV) absorption spectrum was measured and the coating property was evaluated in the same manner as in Example 9.
A liquid crystal cell was prepared and the pretilt angle was measured according to the same method as in Example 9 except that the liquid crystal aligning agent (A1) was changed to the liquid crystal aligning agent (A2).

<Comparative example 2>
The cured film obtained using the liquid crystal aligning agent (A3) obtained in Comparative Example 1 was measured for ultraviolet (UV) absorption spectrum and evaluated for coating properties in the same manner as Example 9.
A liquid crystal cell was prepared and the pretilt angle was measured in the same manner as in Example 9 except that the liquid crystal aligning agent (A1) was changed to the liquid crystal aligning agent (A3).
In FIG. 2, the ultraviolet absorption spectrum of the cured film which consists of a polyimide formed using the liquid crystal aligning agent (A3) of the comparative example 1 is shown.

From the results shown in FIG. 1, it was confirmed that the cured film formed using the liquid crystal aligning agent (A1) of Example 7 formed a polyimide film by baking and generated new absorption in the ultraviolet region. It was. The absorption in the ultraviolet region is based on a comparison with the UV spectrum of the cured film formed using the liquid crystal aligning agent (A3) of Comparative Example 1 shown in FIG. Interpreted as derived.
Moreover, as shown in FIG. 3, in the cured film formed using the liquid crystal aligning agent (A1) of Example 7, the absorbance of absorption in the ultraviolet region is reduced by irradiating with ultraviolet rays that are linearly polarized light. I was able to confirm. This is interpreted as a part of the double bond structure formed in the cured film was lost due to the irradiation of ultraviolet rays.

From the results shown in FIG. 1, it was confirmed that the liquid crystal aligning agent of the present invention forms a polyimide film by firing and generates new absorption in the ultraviolet region. This absorption in the ultraviolet region is interpreted as originating from the double bond structure formed in the polyimide film.
In addition, as shown in FIG. 3, it is confirmed that the polyimide film formed from the liquid crystal aligning agent of the present invention decreases the absorbance of newly generated ultraviolet region absorption by irradiation with ultraviolet rays that are linearly polarized light. I was able to. It is interpreted that a part of the double bond structure formed in the polyimide film was lost due to the irradiation of the linearly polarized ultraviolet ray.

In the results shown in Table 1, the polyimide film formed from the liquid crystal aligning agent of the present invention can be used as it is without irradiating linearly polarized light, whereby a liquid crystal aligning film in which liquid crystal molecules are aligned in the normal direction of the substrate. I found it to be composed.
In addition, the polyimide film formed from the liquid crystal aligning agent of the present invention is a vertical alignment type light in which liquid crystal molecules are slightly tilted from the normal direction of the substrate toward one direction in the substrate plane by irradiation of linearly polarized light. It was found to constitute a reactive liquid crystal alignment film.

  The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be suitably used as a liquid crystal alignment film of a VA liquid crystal display element, and is excellent in terms of coating properties that have been considered as a problem in the past. It was confirmed. It was also found that the film can be used as a vertically aligned photoreactive liquid crystal alignment film having excellent uniformity.

The liquid crystal aligning agent of the present invention is excellent in coatability, does not require light-shielding and the like, and can provide a vertical alignment type photo-alignment liquid crystal alignment film, which is excellent in high productivity. A VA liquid crystal display element having display quality can be manufactured. That is, the liquid crystal surface element of the present invention can be suitably used as a liquid crystal display element for a portable information terminal such as a large liquid crystal TV or a smartphone displaying a high-definition image.
The specification, claims, drawings and abstract of Japanese Patent Application No. 2012-064186, filed on March 21, 2012, and Japanese Patent Application No. 2012-064187, filed on March 21, 2012. The entire contents of this document are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims (7)

  A liquid crystal aligning agent comprising at least one polymer selected from the group consisting of a polyimide precursor having a β-hydroxyester structure and a polyimide having a β-hydroxyester structure.   The liquid crystal aligning agent of Claim 1 from which the polyimide precursor which has the said (beta) -hydroxyester structure, and the polyimide which has the said (beta) -hydroxyester structure are obtained from the diamine compound which has a (beta) -hydroxyester structure. The liquid crystal aligning agent of Claim 2 in which the said diamine compound has a structure represented by a following formula (HE-1).

(In Formula (HE-1), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms. The liquid crystal aligning agent of Claim 2 or 3 in which the said diamine compound has a structure represented by a following formula (HE-2).

(In Formula (HE-2), X ₁ represents a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, or a bicyclic ring having 8 to 10 atoms. And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a system and a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or And at least one divalent linking group selected from the group consisting of ether, ester, amide, and urethane, X ₃ represents a linear alkyl group having 3 to 20 carbon atoms or a fat having 4 to 40 carbon atoms. Represents a monovalent organic group having a cyclic skeleton, provided that the hydrogen atom of the alkyl group may be replaced by a fluorine atom.) The liquid crystal aligning agent according to any one of claims 2 to 4, wherein the diamine compound is a compound represented by the following formula (DA).

(In the formula (DA), X ₁ is a monocyclic ring having 5 or 6 atoms, two adjacent monocyclic rings having 5 or 6 atoms, a bicyclic ring system having 8 to 10 atoms, And an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from the group consisting of a tricyclic ring system having 13 or 14 atoms, X ₂ represents a single bond or an ether Represents at least one divalent linking group selected from the group consisting of ester, amide, and urethane, X ₃ is a C 3-20 linear alkyl group or C 4-40 alicyclic. A monovalent organic group having a skeleton, wherein a hydrogen atom of the alkyl group may be replaced by a fluorine atom, X ₄ represents a single bond, a methylene group or an alkylene group having 2 to 6 carbon atoms. However, this alkylene group may be substituted with a hydroxyl group. X ₅ represents a single bond, an oxygen atom, * —OCO— or * —OCH ₂ — (where a bond marked with “*” is bonded to X ₄ ), provided that X ₄ is a single bond. When it is a bond, X ₅ is a single bond.)   The liquid crystal aligning film obtained from the liquid crystal aligning agent of any one of Claims 1-5.   The liquid crystal display element which has a liquid crystal aligning film of Claim 6.

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