JP7326852B2 - Liquid crystal aligning agent for photo-alignment, liquid crystal alignment film and liquid crystal display element using the same - Google Patents

Description

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display device using the same. Specifically, a liquid crystal alignment agent for forming a photo-alignment liquid crystal alignment film (hereinafter sometimes abbreviated as a photo-alignment film), and a photo-alignment liquid crystal alignment film formed using this liquid crystal alignment agent and a liquid crystal display element having this liquid crystal alignment film. Furthermore, it relates to a polymer such as polyamic acid or polyimide used for the liquid crystal aligning agent, and a tetracarboxylic dianhydride as a raw material thereof.

As a liquid crystal display element, TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, vertical alignment type VA (Multi-domain Vertical Alignment) mode etc., various drive systems are known. These liquid crystal display elements are applied to image display devices of various electronic devices such as televisions and mobile phones, and are being developed with the aim of further improving the display quality. Specifically, the improvement of the performance of the liquid crystal display element is achieved not only by improving the driving system and the element structure, but also by the constituent members used in the element. Among the constituent members used in the liquid crystal display element, the liquid crystal alignment film is one of the most important materials related to the display quality. is also being actively researched.

Here, the liquid crystal alignment film is provided on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element so as to be in contact with the liquid crystal layer. It has the function of orienting with regularity. By using a liquid crystal alignment film with high liquid crystal alignment, a liquid crystal display element with high contrast and improved afterimage properties can be realized (see, for example, Patent Documents 1 and 2).
At present, a solution (varnish) obtained by dissolving polyamic acid, soluble polyimide or polyamic acid ester in an organic solvent is mainly used for forming such a liquid crystal alignment film. In order to form a liquid crystal alignment film from these varnishes, the varnish is applied to a substrate, and then the coating film is cured by heating or the like to form a polyimide liquid crystal alignment film. process. As the alignment treatment method, there is a rubbing method in which the surface of the alignment film is rubbed with a cloth to adjust the direction of the polymer molecules, and a method in which the alignment film is irradiated with linearly polarized ultraviolet rays to cause photoisomerization, dimerization, etc. of the polymer molecules. A photo-alignment method is known in which a photochemical change is caused to impart anisotropy to a film. Therefore, there are advantages such as that the film is not damaged, and that the cause of display failure of the liquid crystal display element such as dust generation and static electricity can be reduced.

As a liquid crystal alignment film using such a photo-alignment method, for example, Patent Documents 1 to 6 apply photoisomerization technology to obtain a photo-alignment film with large anchoring energy and good liquid crystal alignment. It is stated that

JP 2010-197999 A WO2013/157463 JP 2005-275364 A JP 2007-248637 A JP 2009-069493 A WO2015/016118 JP-A-11-249142 WO2013/161569 JP 2015-135464 A WO2017/119376

As described above, there is known a liquid crystal alignment film formed by subjecting a polyimide-based liquid crystal alignment film to alignment treatment using a photo-alignment method. However, the polyimide-based liquid crystal alignment film formed by the photo-alignment method is generally inferior in electrical properties to the polyimide-based liquid crystal alignment film formed by the rubbing treatment, which tends to impair the display quality of the liquid crystal display element. This is because the specific site (photoreactive group) introduced to cause the photochemical reaction, especially the azo group, absorbs light and easily generates radicals, so the voltage holding ratio of the liquid crystal display element (hereinafter referred to as , abbreviated as VHR).
In response to this, studies have been conducted to suppress the decrease in voltage holding ratio by devising the layer structure, etc., while using conventional polyimide-based liquid crystal alignment films (see, for example, Patent Documents 7 to 10). ).

However, in recent years, while higher display quality has been demanded of liquid crystal display elements, it has also been required to increase the brightness of the backlight, which is the light source, compared to the previous ones, in consideration of outdoor use. ing. In a situation exposed to such a high-brightness backlight, even if the configurations described in Patent Documents 7 to 10 are adopted, the deterioration of the electrical characteristics of the element due to the polyimide-based liquid crystal alignment film cannot be avoided. In this case, it is actually difficult to achieve sufficient display quality to meet recent demands.

Therefore, in order to solve such problems of the prior art, the present inventors have developed a liquid crystal alignment film that can be imparted anisotropy by a photo-alignment method and is stable to light, and such a liquid crystal alignment film. Intensive studies were conducted with the aim of providing a liquid crystal aligning agent capable of forming a liquid crystal aligning film. Further, the present inventors have made intensive studies with the aim of providing a liquid crystal display element that maintains a high voltage holding ratio and does not deteriorate in display quality even when exposed to strong light for a long period of time.

As a result of intensive studies to solve the above problems, the present inventors have found a structural unit containing a photoreactive structure, and the structural unit containing the photoreactive structure undergoes a chemical reaction by heating. By using the resulting polymer for the liquid crystal aligning agent, in the heating and baking process after performing the photo-alignment treatment on the coating film of the liquid crystal aligning agent, the structural unit can be changed to a structure that does not contain a photoreactive group. The present inventors have obtained the knowledge that a liquid crystal alignment film stable against light can be realized by this. The present invention has been proposed based on these findings, and specifically has the following configurations.

<1> Contains at least one monomer selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides, and at least one monomer selected from the group consisting of diamines and dihydrazides containing a polymer that is a reaction product from raw materials,
The polymer is at least one selected from the group consisting of polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide,
At least one monomer selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides has a photoreactive structure represented by formula (1) or formula (2). A liquid crystal aligning agent for photo-alignment, which is a monomer having a structural unit containing.

[In formulas (1) and (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R ¹ and at least one of R ² is a group represented by formula (1-1) or formula (1-2);
* represents the bonding position on the benzene ring, any position that can be substituted with a hydrogen atom on one benzene ring, and any position that can be substituted with a hydrogen atom on the other benzene ring;
A hydrogen atom of the benzene ring may be substituted with a substituent. ]

[In formulas (1-1) and (1-2), R ³ and R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or represents an unsubstituted arylcarbonyl group;
* represents the bonding position to the benzene ring in formulas (1) and (2). ]
<2> The monomer having the structure represented by the formula (1) or (2) is at least one tetracarboxylic dianhydride represented by the following formula (3) or (4) The liquid crystal aligning agent for photo-alignment according to <1>.

[In formulas (3) and (4), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R at least one of ¹ and R ² is a group represented by the above formula (1-1) or the above formula (1-2);
R ⁵ and R ⁷ are linear alkylene groups having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, -CON(CH ₃ )- , or represents a single bond, and in R ⁵ and R ⁷ , one or two non-adjacent -CH ₂ - of the linear alkylene group may be replaced with -O-;
R ⁶ and R ⁸ each independently represent a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, or a heterocyclic ring;
A hydrogen atom in the benzene ring may be substituted with a substituent. ]
<3> Described in <2>, wherein the tetracarboxylic dianhydride is represented by any one of the following formulas (3-1) to (3-4) and (4-1) to (4-6) , a liquid crystal aligning agent for photo-alignment.

[In formulas (3-1) to (3-4) and (4-1) to (4-6), R ³ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted represents an alkanoyl group, or a substituted or unsubstituted arylcarbonyl group;
hydrogen atoms of the benzene ring may be substituted with substituents;
In Formula (3-3), Formula (3-4), Formula (4-5) and Formula (4-6), R ⁴ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or represents an unsubstituted alkanoyl group or a substituted or unsubstituted arylcarbonyl group; ]
<4> The tetracarboxylic dianhydride is represented by the following formulas (3-1-1) to (3-1-8), formulas (3-2-1) to (3-2-8), formula (3-3-1), formula (3-3-2), formula (3-4-1), formula (3-4-2), the following formula (4-1-1) ~ formula (4-1 -8), formula (4-2-1) ~ formula (4-2-7), formula (4-3-1) ~ formula (4-3-3), formula (4-4-1) ~ formula (4-4-3), Formula (4-5-1), Formula (4-5-2), Formula (4-6-1) and Formula (4-6-2) , the liquid crystal aligning agent for photo-alignment according to <3>.

[In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, ⁱ Pr represents an isopropyl group, Bu represents a butyl group, ^{and t} Bu represents a t-butyl group. ]
<5> When the film formed from the liquid crystal aligning agent for photo-alignment is heated and baked at 230 ° C. for 30 minutes, the transmittance at 365 nm of the film is 25% or more from the transmittance at 365 nm of the film before heating and baking. The liquid crystal aligning agent for photo-alignment according to any one of <1> to <4>, which increases.
<6> The liquid crystal aligning agent for photo-alignment according to any one of <1> to <5>, which is used for manufacturing a horizontal electrolytic liquid crystal display device.
<7> A liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment according to any one of <1> to <6>.
<8> A liquid crystal display device comprising the liquid crystal alignment film according to <7>.
<9> A horizontal electrolytic liquid crystal display device comprising the liquid crystal alignment film according to <7>.
<10> A method for forming a liquid crystal alignment film formed by a photo-alignment liquid crystal alignment agent containing a polymer having a photoreactive structure,
The film of the liquid crystal aligning agent formed by applying the liquid crystal aligning agent for photoalignment according to any one of <1> to <6> to a substrate is irradiated with polarized light to impart anisotropy, and then heated and baked. and cyclizing the photoreactive structure during the heating and baking to make the structure non-photoreactive.
<11> The method for forming a liquid crystal alignment film according to <10>, wherein the heating and baking are performed in two or more stages with different heating temperatures.
<12> A method for producing a liquid crystal display element, comprising forming a liquid crystal alignment film by the method for forming a liquid crystal alignment film according to <10> or <11>.
<13> A method for producing a horizontal electric field type liquid crystal display element, comprising forming a liquid crystal alignment film by the method for forming a liquid crystal alignment film according to <10> or <11>.
<14> A tetracarboxylic dianhydride represented by the following formula (3) or (4).

[In formulas (3) and (4), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R at least one of ¹ and R ² is a group represented by formula (1-1) or formula (1-2);
R ⁵ and R ⁷ are linear alkylene groups having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, -CON(CH ₃ )- , or represents a single bond, and in R ⁵ and R ⁷ , one or two non-adjacent -CH ₂ - of the linear alkylene group may be replaced with -O-;
R ⁶ and R ⁸ each independently represent a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, or a heterocyclic ring;
A hydrogen atom in the benzene ring may be substituted with a substituent.

[In formulas (1-1) and (1-2), R ³ and R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or represents an unsubstituted arylcarbonyl group;
* represents the bonding position to the benzene ring in formula (3). ]
<15> The tetracarboxylic dianhydride according to <14>, represented by any one of the following formulas (3-1) to (3-4) and (4-1) to (4-6).

[In formulas (3-1) to (3-4) and (4-1) to (4-6), R ³ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted represents an alkanoyl group, or a substituted or unsubstituted arylcarbonyl group;
hydrogen atoms of the benzene ring may be substituted with substituents;
In Formula (3-3), Formula (3-4), Formula (4-5) and Formula (4-6), R ⁴ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or represents an unsubstituted alkanoyl group or a substituted or unsubstituted arylcarbonyl group; ]
<16> The following formulas (3-1-1) to (3-1-8), formulas (3-2-1) to (3-2-8), formulas (3-3-1), formulas (3-3-2), formula (3-4-1), formula (3-4-2), the following formulas (4-1-1) to formulas (4-1-8), formulas (4-2 -1) to formula (4-2-7), formula (4-3-1) to formula (4-3-3), formula (4-4-1) to formula (4-4-3), formula (4-5-1), formula (4-5-2), formula (4-6-1) and tetracarboxylic acid according to <15>, represented by any one of formula (4-6-2) dianhydride.

[In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, ⁱ Pr represents an isopropyl group, Bu represents a butyl group, ^{and t} Bu represents a t-butyl group. ]
<17> A reaction product from a raw material containing the tetracarboxylic dianhydride according to any one of <14> to <16> and at least one monomer selected from diamines and dihydrazides, and
A polymer selected from the group consisting of polyamic acids, polyimides, partial polyimides, polyamic acid esters, polyamic acid-polyamide copolymers, and polyamideimides.

ADVANTAGE OF THE INVENTION According to the liquid crystal aligning agent for photo-alignment of this invention, anisotropy can be provided using the photo-alignment method, and a stable liquid crystal aligning film can be formed with respect to light. Further, by using the liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment of the present invention, the liquid crystal layer is highly aligned and excellent in afterimage properties, and even when a high-brightness backlight is mounted, It is possible to realize a liquid crystal display device in which a high voltage holding ratio is maintained and the display quality does not deteriorate.

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments. In this specification, the numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits.

<<Liquid crystal aligning agent for photo-alignment>>
The "liquid crystal aligning agent for photo-alignment" in the present invention means a liquid crystal aligning agent capable of imparting anisotropy by irradiating polarized light when the film is formed on a substrate, and is used in the present specification. Then, it may simply be called a "liquid crystal aligning agent".
The liquid crystal aligning agent for photo-alignment of the present invention contains a polymer having a structural unit that contains a photoreactive structure and causes a chemical reaction by heating. In the present specification, a structural unit containing a photoreactive structure and causing a chemical reaction by heating is referred to as a "structural unit containing a thermoreactive photoreactive structure". That is, the liquid crystal aligning agent for photo-alignment of the present invention contains a polymer having a constitutional unit containing a thermoreactive photoreactive structure. According to the liquid crystal aligning agent of the present invention, orientation can be imparted by a photo-alignment method.

The "photoreactive structure" in the present invention means an atomic group whose structure is changed by light irradiation. Such a photoreactive structure usually has a specific site (photoreactive group) that absorbs light and undergoes a chemical change, and the structure changes due to the chemical change of the photoreactive group. In the following description, the chemical reaction of the photoreactive structure caused by such light absorption is referred to as "photochemical reaction", and the structural change caused by the photochemical reaction is referred to as photochemical change. A photochemical reaction is a chemical reaction caused by electrons being excited by absorption of light, and is distinguished from a chemical reaction caused by heating. Specific examples of photochemical changes include photoisomerization and photofries rearrangement. The wavelength of light that causes a structural change in the photoreactive structure is not particularly limited, but is preferably 150 to 800 nm, more preferably 200 to 400 nm, even more preferably 300 to 400 nm. Further, the light irradiation intensity required to cause structural change in the photoreactive structure is preferably 0.05 to 20 J/cm ² .

The "structural unit containing a thermoreactive photoreactive structure" in the present invention is a structural unit that constitutes a polymer, contains the photoreactive structure as described above, and causes a chemical reaction when heated. means

The liquid crystal aligning agent for photo-alignment (liquid crystal aligning agent) of the present invention is used for forming a liquid crystal aligning film. In order to form a liquid crystal aligning film with the liquid crystal aligning agent of the present invention, for example, the liquid crystal aligning agent is applied to a substrate to form a film, and then polarized light for photoalignment is irradiated. As a result, the photoreactive structure of the polymer main chain, which is roughly parallel to the polarization direction, selectively undergoes a photochemical reaction to change the structure, and the component of the polymer main chain that faces a specific direction (the structure changes As a result, the component oriented in a particular direction) becomes dominant. That is, the polymer main chains constituting the film are oriented in a specific direction (anisotropic state). Thereafter, the photo-aligned film is heated and baked to form a solid liquid crystal alignment film. At this time, in the polymer used in the present invention, the constituent units having a photoreactive structure undergo a chemical reaction by heating, the photoreactive groups disappear, and the number of photoreactive groups in the entire film decreases. or no photoreactive groups are present. Therefore, the formed liquid crystal alignment film does not easily generate radicals even when exposed to strong light, and exhibits high stability to light. Further, at this time, the polymer used in the present invention undergoes orientation amplification upon heating, and can exhibit high orientation. Here, "orientation amplification" refers to a phenomenon in which a polymer whose molecular motion is facilitated by heating is oriented along the component of the polymer main chain oriented in a specific direction by photo-orientation treatment, and anisotropy is amplified. means that
In addition, description of the column of a liquid crystal aligning film can be referred for the detailed formation conditions of a liquid crystal aligning film.

<Polymer Having a Structural Unit Containing a Thermally Reactive Photoreactive Structure: Polymer Having a Structure Represented by Formula (1) or Formula (2)>
Below, the polymer which has a structural unit containing the thermoreactive photoreactive structure which the liquid crystal aligning agent of this invention contains is demonstrated. In the following description, "a polymer having a constitutional unit containing a heat-reactive photoreactive structure" may be referred to as "a polymer having a heat-reactive photoreactive structure".
The polymer having structural units containing a thermoreactive photoreactive structure contained in the liquid crystal aligning agent for photoalignment of the present invention is a tetracarboxylic dianhydride, a tetracarboxylic diester, and a tetracarboxylic diester dihalide. Polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide obtained by reacting a raw material containing at least one monomer selected from the group consisting of diamines and dihydrazides with at least one monomer selected from the group consisting of A polymer selected from the group consisting of copolymers, and polyamideimides. The above tetracarboxylic dianhydride, tetracarboxylic diester, and tetracarboxylic diester dihalide have a structure represented by the following formula (1) or the following formula (2) containing a thermally reactive photoreactive structure. The structural unit containing a thermally reactive photoreactive structure is derived from the tetracarboxylic dianhydride, tetracarboxylic diester, or tetracarboxylic diester dihalide contained in the raw material. That is, the polymer having a structural unit containing a thermoreactive photoreactive structure contained in the liquid crystal aligning agent for photoalignment of the present invention is a polymer having a structure represented by the following formula (1) or the following formula (2) is.

In formulas (1) and (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R ¹ and At least one of R ² is a group represented by formula (1-1) or formula (1-2). Of R ¹ and R ² , the group represented by formula (1-1) or (1-2) may be either one or both of R ¹ and R ² . When both R ¹ and R ² are groups represented by formula (1-1) or formula (1-2), these groups may be the same or different.
* represents the bonding position to the structures on both sides of the structures represented by formulas (1) and (2), either of the positions that can be substituted with the hydrogen atoms in one benzene ring, or the other benzene It is any position that can be substituted with a hydrogen atom in the ring.

In formulas (1-1) and (1-2), R ³ and R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted represents a substituted arylcarbonyl group, and in formulas (1-1) and (1-2), * represents the bonding position to the benzene ring in formulas (1) and (2).

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

The alkanoyl group for R ³ may be linear or branched. The alkanoyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 2 carbon atoms, and still more preferably 1 carbon atom. Specific examples of alkanoyl groups include methanoyl, ethanoyl, propanoyl, isopropanoyl, butanoyl, isobutanoyl, sec-butanoyl, tert-butanoyl, pentanoyl, isopentanoyl, neopentanoyl groups, Examples include tert-pentanoyl group, 1-methylbutanoyl group, 1-ethylpropanoyl group, hexanoyl group, isohexanoyl group, 1-methylpentanoyl group, 1-ethylbutanoyl group and the like.
The aryl group of the arylcarbonyl group in R ³ may be monocyclic or condensed. The aryl group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and still more preferably 6 to 10 carbon atoms. Specific examples of aryl groups include phenyl, 1-naphthyl and 2-naphthyl groups. Specific examples of the arylcarbonyl group include a phenylcarbonyl group and a 1-naphthylcarbonyl group.
Each of the alkyl group, alkanoyl group and arylcarbonyl group in R ³ may be substituted with a substituent. A hydroxyl group, an amino group, a halogeno group, etc. can be mentioned as a substituent.
Among these, R ³ is preferably a methyl group, an ethyl group, a propyl group, a hydrogen atom, a methanoyl group, or a phenyl group from the viewpoint of improving the performance of the finally produced liquid crystal alignment film.

Description of the alkyl group, alkanoyl group, arylcarbonyl group, and substituents that can be substituted on these groups for R ³ and R ⁴ in formula (1-2), preferred ranges, and specific examples are given in the above formula (1-1 ), descriptions, preferred ranges, and specific examples of the alkyl group, alkanoyl group, arylcarbonyl group, and substituents that can be substituted on these groups for R ³ of ) can be referred to.

A hydrogen atom of the benzene ring in formulas (1) and (2) may be substituted with a substituent. Preferred examples of substituents include alkyl groups, alkoxy groups, halogenated alkyl groups, halogeno groups, and carboxyalkyl groups. Alkyl groups may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1-4, more preferably 1-2. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group and the like. The alkoxy group preferably has 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms. Specific examples of alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, and tert-butoxy groups. A trifluoromethyl group etc. can be illustrated as a specific example of a halogenated alkyl group. Specific examples of the halogeno group include a fluoro group, a chloro group, a bromo group, an iodo group and the like. A carboxymethyl group, a carboxyethyl group, etc. can be illustrated as a specific example of a carboxyalkyl group.

The structural units constituting the polymer having a structural unit containing a thermoreactive photoreactive structure contained in the liquid crystal aligning agent of the present invention are all structural units containing a thermoreactive photoreactive structure (formula (1) and a structural unit containing a structure represented by formula (2)), part of which contains a thermoreactive photoreactive structure and the rest contains a non-thermally reactive photoreactive structure It may be a structural unit, a part of which contains a thermoreactive photoreactive structure, another part of which contains a non-thermally reactive photoreactive structure, and the rest of which contains a photoreactive structure. It may be a structural unit that does not contain a photoreactive structure, or a structural unit that partially contains a thermoreactive photoreactive structure and the rest of which does not contain a photoreactive structure. Structural units constituting a polymer having a structural unit containing a thermoreactive photoreactive structure contained in the liquid crystal aligning agent of the present invention, a part of the structural unit containing a thermoreactive photoreactive structure, the rest Structural units that do not contain a photoreactive structure are preferred.
The number of structural units containing a thermoreactive photoreactive structure in the polymer is not particularly limited, but is preferably 3 to 100, more preferably 5 to 50, more preferably 5 to 5 per molecule of the polymer. Thirty is more preferred. When the polymer has two or more structural units containing photoreactive structures, the plurality of structural units may be the same or different.

[Photoreaction and chemical reaction of structures represented by formula (1) and formula (2)]
When the structures represented by formulas (1) and (2) are irradiated with UV light, trans-cis isomerization of the azo groups occurs to change the orientation of the polymer backbone. Thereby, a liquid crystal alignment film in which the polymer main chain is oriented in a specific direction is obtained. Furthermore, the structure represented by Formula (1) or Formula (2) undergoes a chemical reaction by heating. This chemical reaction is a reaction that converts the photoreactive group of the photoreactive structure into a non-photoreactive structure, and is usually a cyclization reaction between the photoreactive group and another group. Thereby, the linearity of the polymer is increased, and a liquid crystal alignment film with higher alignment can be obtained. Further, in the polymer containing the structure represented by formula (1) or formula (2), after imparting anisotropy by a photo-alignment method (after causing a structural change in the photoreactive structure by light irradiation) By heating, the photoreactivity of the photoreactive structure can be extinguished and converted into a structure stable to light.

The heating temperature for causing the chemical reaction is preferably 40 to 300.degree. C., more preferably 100 to 300.degree. C., even more preferably 150 to 280.degree. The heating time is preferably 1 minute to 3 hours, more preferably 5 minutes to 1 hour, even more preferably 15 minutes to 45 minutes. Regarding the heating temperature and heating time for causing a chemical reaction, when the heating temperature is 40 to 180°C, the heating time is preferably 10 minutes to 3 hours, and when the heating temperature is 180 to 300°C, the heating time is reduced. It is preferably from 1 minute to 1 hour. Among them, it is more preferable that the heating temperature is 150 to 280° C. and the heating time is 10 minutes to 1 hour, and the heating temperature is 180 to 250° C. and the heating time is 15 minutes to 45 minutes, because the reaction efficiency can be improved. Minutes is more preferred.

The mechanism of disappearance of photoreactive groups due to chemical reactions caused by heating in the structures represented by formulas (1) and (2) having an azobenzene structure will be described below.
(A) Cyclization reaction of azobenzene structure: 5-membered ring formation An azobenzene structure having a substituent R ^1A at the ortho position to the azo group of one benzene ring, that is, an azobenzene structure represented by the following formula (A-1) As shown in the following reaction formula, the azo group of the structural unit having the compound reacts with the substituent R ^1A of the benzene ring to form an indazole ring upon heating, and the azo group disappears. For details of this reaction, reference can be made to New J. chem., 1999, 23, 1223-1230.

In formula (A-1), R ^1A represents a group represented by formula (A-1-1) or formula (A-1-2). In formulas (A-1-1) and (A-1-2), R ^4A and R ^5A are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or represents a substituted or unsubstituted arylcarbonyl group. Descriptions, preferred ranges, and specific examples of R ^4A and R ^5A are described with respect to the alkyl group, alkanoyl group, arylcarbonyl group, and substituents that can be substituted on these groups for ^R a in formula (a-1) above. and preferred ranges and specific examples can be referred to.

(B) Cyclization reaction of azobenzene structure: 6-membered ring formation An azobenzene structure having a substituent (—CH ₂ COOR ^1B ) at the ortho position to the azo group on one benzene ring, that is, represented by the following formula (B-1) In the structural unit having an azobenzene structure, the azo group reacts with the substituent (—CH ₂ COOR ^1B ) on the benzene ring to form a cyclic structure by heating, and the azo group disappears, as shown in the reaction formula below. do.

In formula (B-1), R ^1B represents a hydrogen atom or a substituted or unsubstituted alkyl group. For the description, preferred range, and specific examples of the alkyl group and the substituents that can be substituted on the alkyl group, the description, preferred range, and specific examples of the alkyl group and the substituent thereof for R ^a in the above formula (a-1) are provided. You can refer to it.

Whether or not a structural unit containing a thermoreactive photoreactive structure has undergone a chemical reaction should be confirmed by ultraviolet-visible absorption spectrum (transmittance), nuclear magnetic resonance (NMR) spectrum, and infrared spectroscopy (IR) spectrum. can be done. For example, when the photoreactive structure is an azobenzene structure, the occurrence of the cyclization reaction can be confirmed by an increase in transmittance at 365 nm, which is the absorption wavelength of azobenzene. Here, in a liquid crystal aligning agent containing an azobenzene structure as a structural unit of a polymer, it is preferable that the chemical reaction caused by heating increases the transmittance at 365 nm by 25% or more. Specifically, when the film formed from the liquid crystal aligning agent for photo-alignment is heated and baked at 230 ° C. for 30 minutes, the transmittance at 365 nm of the film is 25% or more from the transmittance at 365 nm of the film before heating and baking. Rise is preferred. With such a liquid crystal aligning agent for photoalignment, the photoreactivity of the azobenzene structure can be reliably reduced by heating, and a liquid crystal alignment film having high photostability and exhibiting good liquid crystal alignment can be formed.

[Cyclization start temperature and orientation amplification start temperature]
As described above, the liquid crystal aligning agent of the present invention contains a polymer having a structural unit containing a thermoreactive photoreactive structure, and the structural unit containing the thermoreactive photoreactive structure undergoes a cyclization reaction by heating. is what causes The cyclization onset temperature may be lower or higher than the orientation amplification onset temperature. For example, when the cyclization initiation temperature is lower than the orientation amplification initiation temperature, after the film of the liquid crystal aligning agent is subjected to photo-alignment treatment, when heating and baking, first, the cyclization initiation temperature is higher than the orientation amplification initiation temperature. By maintaining the temperature within the range of , cyclization can proceed to some extent prior to orientational amplification. Thereafter, by raising the temperature to or above the orientation amplification start temperature and maintaining it, orientation amplification can be caused. Conversely, when the cyclization initiation temperature is higher than the orientation amplification initiation temperature, when the film of the liquid crystal aligning agent is subjected to photo-alignment treatment and then heated and baked, first, the orientation amplification initiation temperature is higher than the orientation amplification initiation temperature and lower than the cyclization temperature. A certain degree of orientational amplification can be achieved prior to cyclization by maintaining the temperature within the range of . Thereafter, the temperature is raised to the cyclization initiation temperature or higher and maintained to cause cyclization. By staggering the start times of cyclization and orientation amplification in this manner, the orientation of the obtained liquid crystal orientation film can be controlled to be better.

Here, "holding at a temperature within a specific temperature range" means not only fixing at a constant temperature, but also increasing the temperature, decreasing the temperature, or increasing or decreasing the temperature from that temperature range. It also includes the case of preventing it from coming off. The time for holding within the temperature range can be usually 1 minute to 1 hour, preferably 1 minute to 30 minutes.
To measure the cyclization initiation temperature of a polymer, for example, a film containing the polymer is heat-treated at different temperatures, and then the transmittance is measured. Create a correlation diagram as an axis. The temperature at the boundary where the transmittance curve rises from the flat line on the correlation diagram is defined as the "cyclization start temperature". Transmittance here is a measure of the cyclization reaction, the transmission of light in the absorption wavelength range of the polymer where the absorbance decreases (transmittance increases) when the polymer undergoes a cyclization reaction. use the rate. For example, for a polymer having an azobenzene structure, the transmittance at 365 nm can be used as an indicator of the cyclization reaction, and the cyclization initiation temperature can be determined from the correlation diagram between the transmittance and the heating temperature. The polymer-containing film used for transmittance measurement may be subjected to photo-alignment treatment.

To measure the orientation amplification start temperature of a polymer, for example, films containing the polymer are subjected to photo-orientation treatment and then heat treatment at different temperatures, and the retardation value is measured. Then, create a correlation diagram with the heating temperature on the horizontal axis and the retardation value on the vertical axis. and Here, the retardation value is an index of the degree of orientation of the polymer main chain, and the higher the retardation value, the more highly oriented the polymer chain. Light of 400 to 700 nm can be used to measure the retardation value.

For specific measurement conditions of the transmittance and retardation value, the description in the Examples section can be referred to.
When the film of the liquid crystal aligning agent is held within a specific temperature range, it may be temporarily heated to the target temperature within that range, but the temperature lower than the target temperature (eg, 90 to 180 ° C.) is preheated. After performing (preliminary baking), it is preferable to heat and hold the target temperature (for example, 185° C. or higher). This allows the cyclization reaction and orientation amplification to proceed stably. For specific conditions of the heating and baking, reference can be made to the description of the heating and baking process in the column of the liquid crystal alignment film.

The cyclization initiation temperature of the polymer used for the liquid crystal aligning agent is preferably any temperature of 100 to 200° C. For example, a polymer having a cyclization initiation temperature within the range of 110 to 160° C. can be used. . The cyclization initiation temperature of the polymer can be adjusted by changing the type of monomer (acid dianhydride, etc.) having a structure represented by formula (1) or formula (2) used during polymer synthesis.
The orientation amplification initiation temperature of the polymer used for the liquid crystal aligning agent is preferably any temperature of 100 to 200° C. For example, a polymer having an orientation amplification initiation temperature within the range of 110 to 180° C. can be used. . The orientation amplification starting temperature of the polymer is adjusted by changing the type and composition ratio of acid dianhydrides and diamines other than the acid dianhydrides having the structure represented by formula (1) or formula (2) used during polymer synthesis. It is possible to

[Polyamic acid and its derivatives]
The polymer containing the structure represented by formula (1) or formula (2) (polymer having a thermoreactive photoreactive structure) used for the liquid crystal aligning agent in the present invention is represented by formula (1) or formula (2) At least one selected from the group consisting of polyamic acids, polyimides, partial polyimides, polyamic acid esters, polyamic acid-polyamide copolymers, and polyamideimides containing a structure represented by Polyimides, partial polyimides, polyamic acid esters, polyamic acid-polyamide copolymers, and polyamideimides are sometimes referred to herein as polyamic acid derivatives. One type or two or more types of the polymer containing the structure represented by Formula (1) or Formula (2) used for the liquid crystal aligning agent may be used. That is, the liquid crystal aligning agent of the present invention may contain a polymer containing two or more structures represented by formula (1) or formula (2).

Polyamic acid is a polymer synthesized by a polymerization reaction of one or more selected from the group consisting of diamines and dihydrazides and tetracarboxylic dianhydride. For example, a polyamic acid is a polymer synthesized by a polymerization reaction of a diamine represented by the formula (DI) and a tetracarboxylic dianhydride represented by the formula (AN), and is represented by the formula (PAA). It has structural units. By imidizing polyamic acid, a polyimide liquid crystal alignment film having a structural unit represented by formula (PI) can be formed.

In Formula (AN), Formula (PAA), and Formula (PI), X ¹ represents a tetravalent organic group. In Formula (DI), Formula (PAA), and Formula (PI), ^X2 represents a divalent organic group. Preferred ranges and specific examples of the tetravalent organic group in X ¹ are the corresponding tetracarboxylic dianhydrides described in the column of formula (1), formula (2) or known tetracarboxylic dianhydrides below. You can refer to the structure that For the preferred range and specific examples of the divalent organic group in X ² , reference can be made to the description of the corresponding structures of the diamines or dihydrazides described in the section on known diamines and dihydrazides below.

Derivatives of polyamic acid are compounds in which a part of polyamic acid is replaced with other atoms or atomic groups to modify the properties, and in particular, it is preferred that the solubility in the solvent used for the liquid crystal aligning agent is increased. Derivatives of polyamic acid are 1) polyimides in which all amino groups and carboxyl groups of polyamic acid undergo dehydration ring-closing reaction, 2) partial polyimides in which partial dehydration ring-closure reaction occurs, and 3) carboxyl groups of polyamic acid are converted to esters. polyamic acid ester, 4) polyamic acid-polyamide copolymer obtained by replacing part of the acid dianhydride contained in the tetracarboxylic acid dianhydride compound with an organic dicarboxylic acid and reacting it, and 5) the polyamic acid-polyamide Polyamideimides obtained by subjecting a part or all of the copolymer to a dehydration ring closure reaction are included.

For example, polyimides include those having a structural unit represented by the above formula (PI), and polyamic acid esters include those having a structural unit represented by the following formula (PAE). .

In formula (PAE), X ¹ represents a tetravalent organic group, X ² represents a divalent organic group, and Y represents an alkyl group. For preferred ranges and specific examples of X ¹ and X ² , the description of X ¹ and X ² in Formula (PAA) can be referred to. For the description, preferred range, and specific examples of Y, the description, preferred range, and specific examples of the alkyl group for R ^a in formula (a-1) above can be referred to.

In the present invention, the polyamic acid and its derivative used as the polymer having a thermoreactive photoreactive structure have a structural unit containing a structure represented by Formula (1) or Formula (2). This structural unit may be included in the main chain, for example. The polyamic acid and its derivatives are monomers containing a structure represented by formula (1) or formula (2), and are a group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides. can be obtained as a reaction product by a polymerization reaction of a monomer selected from and a diamine or dihydrazide. For example, a polyamic acid can be obtained as a reaction product from a polymerization reaction between a tetracarboxylic dianhydride represented by formula (3) or formula (4) described below and a diamine or dihydrazide.

Here, the diamine or dihydrazide used in the polymerization reaction may or may not contain a photoreactive structure, and it is also preferred that the diamine or dihydrazide only contain no photoreactive structure. Description and preferred range of diamine or dihydrazide, and specific examples are described below in the column of "monomer containing non-thermally reactive photoreactive structure" and "diamine and dihydrazide containing no photoreactive structure". You can refer to the description in the column. The monomer containing the structure represented by Formula (1) or Formula (2) and the diamine or dihydrazide used for synthesizing the polyamic acid may be of one type or two or more types. As monomers containing a structure represented by formula (1) or formula (2), a tetracarboxylic dianhydride having a structure represented by formula (3) and a tetracarboxylic acid having a structure represented by formula (4) It may be used in combination with an acid dianhydride for the polymerization reaction. Further, as the tetracarboxylic dianhydride, tetracarboxylic diester, or tetracarboxylic diester dihalide, in addition to the monomer containing the structure represented by formula (1) or (2), other monomers may be used in combination. However, a structural unit derived from the monomer may be introduced into the polyamic acid. Other monomers include tetracarboxylic dianhydrides that do not contain thermally reactive photoreactive structures. For descriptions, preferred ranges, and specific examples thereof, descriptions of tetracarboxylic dianhydrides in the column of monomers containing a non-thermally reactive photoreactive structure described later, and tetracarboxylic acid dianhydrides containing no photoreactive structures described later Reference can be made to the dianhydride column.

Monomers (tetracarboxylic dianhydride, tetracarboxylic dianhydride, tetracarboxylic dianhydride, tetracarboxylic dianhydride, tetracarboxylic dianhydride, The amount of carboxylic acid diester or tetracarboxylic acid diester dihalide) is preferably 20 to 100 mol %, more preferably 50 to 100 mol %.

A polyamic acid or derivative thereof having a structure represented by formula (1) or formula (2) in its main chain can be produced in the same manner as known polyamic acids or derivatives thereof used for forming polyimide films.
For example, the total amount of tetracarboxylic dianhydride charged is preferably 0.9 to 1.1 mol per 1 mol of diamine.

Further, a polyamic acid having a structure represented by formula (1) or formula (2) in the main chain is a polyamic acid derivative having a structure represented by formula (1) or formula (2) in the main chain In the case of polyimide, the resulting polyamic acid solution is mixed with acid anhydrides such as acetic anhydride, propionic anhydride and trifluoroacetic anhydride as dehydrating agents, and triethylamine, pyridine and collidine as dehydration ring closure catalysts. A polyimide can be obtained by an imidization reaction with a class amine at a temperature of 20 to 150°C. Alternatively, polyamic acid is precipitated from the resulting polyamic acid solution using a large amount of poor solvent (alcoholic solvent such as methanol, ethanol, isopropanol, or glycol solvent), and the precipitated polyamic acid is dissolved in toluene, xylene, or the like. A polyimide can also be obtained by an imidization reaction at a temperature of 20 to 150° C. in a solvent together with the dehydrating agent and the dehydration ring-closing catalyst.

In the imidization reaction, the ratio of the dehydrating agent to the dehydration ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total amount of the dehydrating agent and dehydration ring-closing catalyst used is preferably 1.5 to 10 times the molar amount of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid. By adjusting the dehydrating agent, catalyst amount, reaction temperature and reaction time used in this imidization reaction, the degree of imidization can be controlled, thereby obtaining a partial polyimide in which only a portion of the polyamic acid is imidized. be able to. The resulting polyimide can be separated from the solvent used for the reaction and re-dissolved in another solvent to be used as a liquid crystal aligning agent, or can be used as a liquid crystal aligning agent without separating from the solvent. .

A polyamic acid ester having a structure represented by formula (1) or formula (2) in the main chain is a polyamic acid having a structure represented by the above formula (1) or formula (2) in the main chain and a hydroxyl group-containing A method of synthesizing by reacting a compound, a halide, an epoxy group-containing compound, etc., or a tetracarboxylic acid derived from a tetracarboxylic dianhydride having a structure represented by formula (1) or formula (2) It can be obtained by a method of synthesizing by reacting an acid diester or a tetracarboxylic acid diester dichloride with a diamine. A tetracarboxylic acid diester derived from a tetracarboxylic acid dianhydride can be obtained, for example, by reacting a tetracarboxylic acid dianhydride with two equivalents of alcohol to open the ring, and a tetracarboxylic acid diester dichloride is a tetracarboxylic acid It can be obtained by reacting the diester with 2 equivalents of a chlorinating agent (for example, thionyl chloride, etc.). The polyamic acid ester may have only the amic acid ester structure, or may be a partially esterified product in which the amic acid structure and the amic acid ester structure coexist.

The liquid crystal aligning agent for photo-alignment of the present invention may contain only one type of these polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these, or may contain two or more types.

The molecular weight of the polyamic acid or derivative thereof having the structure represented by formula (1) or formula (2) in the main chain is 7,000 to 500,000 in terms of polystyrene-equivalent weight average molecular weight (Mw). It is preferably from 10,000 to 200,000. The molecular weight of the polyamic acid or derivative thereof can be obtained from measurement by gel permeation chromatography (GPC).

A polyamic acid having a structure represented by formula (1) or formula (2) in its main chain or a derivative thereof is precipitated with a large amount of poor solvent, and the solid content obtained is analyzed by IR (infrared spectroscopy), NMR (nuclear Its presence can be confirmed by analysis with magnetic resonance analysis). Further, an extract of the decomposition product of the polyamic acid or its derivative with an organic solvent using a strong alkaline aqueous solution such as KOH or NaOH is subjected to GC (gas chromatography), HPLC (high performance liquid chromatography) or GC-MS (gas chromatography mass spectrometry). The monomers used can be confirmed by analyzing with .

<Other polymers>
The liquid crystal aligning agent for photo-alignment of the present invention may contain only a polymer having a structure represented by Formula (1) or Formula (2) as a polymer, or may contain other polymers. Other polymers can include polymers that do not contain thermally reactive photoreactive structures but do contain photoreactive structures and polymers that do not contain photoreactive structures.
Polymers that do not contain thermally reactive photoreactive structures but do contain photoreactive structures include monomers selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides. Mention may be made of polyamic acids and derivatives thereof obtainable as reaction products by polymerization reactions with diamines or dihydrazides. The tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides used herein include tetracarboxylic dianhydrides in the column of monomers containing non-thermally reactive photoreactive structures described below. Reference can be made to the description and the section on tetracarboxylic dianhydrides containing no photoreactive structures below. Descriptions of diamines and dihydrazides, preferred ranges, and specific examples are described below in the column of "monomers containing non-thermally reactive photoreactive structures" and "diamines and dihydrazides containing no photoreactive structures". You can refer to the description in the column. Here, a monomer containing a non-thermally reactive photoreactive structure is used as one of the monomers used in the polymerization reaction to obtain a polymer containing a photoreactive structure but not containing a thermally reactive photoreactive structure. Obtainable. For the production of polymers that do not contain thermally reactive photoreactive structures but do contain photoreactive structures, reference can be made to the description in the section on polyamic acids and derivatives thereof above.

Polymers containing no photoreactive structure include reaction products obtained by polymerization of monomers selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides with diamines or dihydrazides. Polyamic acid and its derivatives that can be obtained as. As the tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides used herein, the column of tetracarboxylic dianhydrides containing no photoreactive structure described later can be referred to. For descriptions, preferred ranges, and specific examples of diamines and dihydrazides, the descriptions in the section "Diamines and dihydrazides containing no photoreactive structure" below can be referred to. For the production of a polymer that does not contain a photoreactive structure, reference can be made to the above section on polyamic acid and its derivatives.

<Raw material monomer for polymer production>
[Monomer having structural unit containing thermally reactive photoreactive structure: tetracarboxylic acid dianhydride having thermally reactive photoreactive structure represented by formula (1) or formula (2)]
The structural unit containing a thermoreactive photoreactive structure in the polymer having a structural unit containing a thermoreactive photoreactive structure contained in the liquid crystal aligning agent for photoalignment of the present invention is a thermoreactive polymer contained in the raw material. derived from a monomer having a constitutional unit containing a photoreactive structure. The number of monomers having a constitutional unit containing a thermoreactive photoreactive structure may be one, or two or more may be used in combination.

The monomer having a structural unit containing a thermally reactive photoreactive structure is a tetracarboxylic acid dianhydride or tetracarboxylic acid having a thermally reactive photoreactive structure represented by formula (1) or formula (2). It is a diester or a tetracarboxylic acid diester dihalide, and is preferably a tetracarboxylic acid dianhydride having a heat-reactive photoreactive structure represented by formula (1) or formula (2).
A tetracarboxylic dianhydride having a thermoreactive photoreactive structure represented by formula (1) or formula (2) has a structure represented by formula (3) or formula (4). is preferred.

The tetracarboxylic dianhydride represented by formula (3) or formula (4) has an azobenzene structure common to the structure represented by formula (1) or formula (2), respectively. By synthesizing polymers such as polyamic acids, polyimides, polyamides, partial polyimides, polyamic acid esters, polyamic acid-polyamide copolymers and polyamideimides using monomers containing structures represented by formula (1) or formula (2) It is possible to obtain a polymer having constitutional units in the main chain. Therefore, the tetracarboxylic dianhydride represented by Formula (3) or Formula (4) is useful as a raw material for the polymer used in the liquid crystal aligning agent of the present invention. In addition to the liquid crystal alignment film, the polymer synthesized using the tetracarboxylic dianhydride represented by the formula (3) or the formula (4) as a monomer is an optical anisotropic body, a retardation film, an optical compensation It can also be used for films, antireflection agents, various films, optical members, and the like.

In formulas (3) and (4), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1), or formula (1-2); At least one of R ¹ and R ² in 3) and formula (4) is a group represented by formula (1-1) or formula (1-2). For the description of R ¹ and R ² in formulas (3) and (4), the description of R 1 and R 2 in formulas ( ¹ ) and ( ²⁾ can be referred to.
In formula (4), R ⁵ and R ⁷ are linear alkylene groups having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, - CON(CH ₃ )—, or represents a single bond. In R ⁵ and R ⁷ , one or two non-adjacent straight-chain alkylene groups —CH ₂ — may be replaced with —O—. R ⁵ and R ⁷ may be the same or different from each other. R ⁶ and R ⁸ each independently represent a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, or a heterocyclic ring. R ⁶ and R ⁸ may be the same or different from each other. ;

In formula (4), the monocyclic hydrocarbon for R ⁶ and R ⁸ may be an alicyclic ring or an aromatic ring. The number of carbon atoms in the monocyclic hydrocarbon is preferably 6-12, more preferably 6-10, even more preferably 6-8. Specific examples of monocyclic hydrocarbons include a benzene ring and a cyclohexane ring.
In formula (4), the heterocyclic ring for R ⁶ and R ⁸ may be an alicyclic ring or an aromatic ring. The number of carbon atoms in the heterocyclic ring is preferably 1-26, more preferably 3-14, even more preferably 3-8. A nitrogen atom, an oxygen atom, and a sulfur atom can be mentioned as a heteroatom contained as a ring member in the heterocyclic ring. Specific examples of heterocyclic rings include pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indole ring and oxazole ring.

In formula (4), —R ⁵ is bonded to one of the benzene rings in formula (2), and the bonding position is any position that can be substituted with a hydrogen atom on the benzene ring. —R ⁷ is bonded to the other benzene ring in formula (2), and the bonding position is any position that can be substituted with a hydrogen atom on the benzene ring. The remaining substitutable positions on the benzene ring may be unsubstituted or substituted with a substituent. As for the preferred range and specific examples of the substituent, the preferred range and specific examples of the substituent that can be substituted on the benzene ring in the above formula (1) can be referred to.

In formulas (1-1) and (1-2), R ³ and R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted represents a substituted arylcarbonyl group. In formulas (1-1) and (1-2), * represents the bonding position to the benzene ring in formulas (3) and (4). Descriptions of R ³ , R ⁴ and * in formulas (1-1) and (1-2) refer to R 3 in formulas (1-1) and (1-2) in formulas (1) and ( ² ). , R ⁴ , * can be referred to.

The acid dianhydrides represented by the formulas (3) and (4) are easy to synthesize and easy to obtain raw materials. Acid dianhydrides represented by any of the following formulas (3-1) to (3-4) and formulas (4-1) to (4-6) are preferred.

In formulas (3-1) to (3-4) and formulas (4-1) to (4-6), R ³ and R ⁴ are the formulas (1-1 ) and R ³ and R ⁴ in formula (1-2). R ³ and R ⁴ are each independently preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkanoyl group having 1 to 10 carbon atoms. ^R 3 in formula (3-1), formula (4-1) and formula (4-3), R ³ in formula (3-3) and formula (4-5), R ⁴ and R ³ R ⁴ , and R ³ and R ⁴ in formulas (3-4) and (4-6) may be the same or different, but are preferably the same.

As a preferred specific example of the tetracarboxylic dianhydride represented by any one of formulas (3-1) to (3-4) and formulas (4-1) to (4-6), formula (3-1 -1) to formula (3-1-8), formula (3-2-1) to formula (3-2-8), formula (3-3-1), formula (3-3-2), formula (3-4-1), formula (3-4-2), the following formulas (4-1-1) to formulas (4-1-8), formulas (4-2-1) to formulas (4-2 -7), formula (4-3-1) to formula (4-3-3), formula (4-4-1) to formula (4-4-3), formula (4-5-1), formula (4-5-2), formula (4-6-1) and formula (4-6-2). Polymers synthesized using these tetracarboxylic dianhydrides as monomers tend to exhibit high liquid crystal orientation. In each formula, Me is a methyl group, Et is an ethyl group, Pr is a propyl group, ⁱ Pr is an isopropyl group, Bu is a butyl group, ^{and t} Bu is a t-butyl group.

In order to provide a liquid crystal aligning agent that can be a liquid crystal alignment film with higher liquid crystal alignment, among these compounds, formulas (3-2-1) to (3-2-4), formula (3-4 -1), formulas (4-2-1) to (4-2-4), and at least one of the tetracarboxylic dianhydrides represented by any of formulas (4-5-1), It is preferably used as a raw material for polymers.

[Monomer Containing Non-Thermal Reactive Photoreactive Structure]
In the present invention, a monomer (tetracarboxylic dianhydride, tetracarboxylic acid Non-thermally reactive monomers, which are monomers containing photoreactive structures other than diesters or tetracarboxylic acid diester dihalides), may be used in combination with monomers containing thermally reactive photoreactive structures. The photoreactive structure introduced by the monomer does not undergo a chemical reaction upon heating.
The photoreactive structure introduced by the monomer containing the non-thermally reactive photoreactive structure is preferably a photoisomerization structure or a photodimerization structure, more preferably a photoisomerization structure. Examples of the photoisomerizable structure include an azobenzene structure, a stilbene structure, an acylhydrazone structure, etc. Examples of the photodimerizable structure include a coumarin structure, a cinnamate structure, a chalcone structure, a tolan structure, and the like.

Monomers containing a non-thermally reactive photoreactive structure include the following formulas (II-1), (II-2), (III-1), (III-2), and (IV-1) ~ (IV-3), Formula (V-1) ~ Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and At least one selected from the group of compounds represented by formula (VIII-2) can be used.

In each of the above formulas, a group in which the bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. In formula (IV-3), r is an integer from 1 to 10. In formula (V-2), R ⁶ is independently -CH ₃ , -OCH ₃ , -CF ₃ , -COOCH ₃ and a is independently an integer of 0-2. In formula (V-3), ring A and ring B are each independently at least one selected from monocyclic hydrocarbons, condensed polycyclic hydrocarbons and heterocyclic rings, and R ¹¹ has 1 carbon atom. -20 linear alkylene, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, or -CON(CH ₃ )-, where R ¹² has 1 carbon -20 linear alkylene, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, or -CON(CH ₃ )-, and at R ¹¹ and R ¹² , One or two of —CH ₂ — in linear alkylene may be substituted with —O—, and R ⁷ to R ¹⁰ are each independently —F, —CH ₃ , —OCH ₃ , —CF ₃ , or -OH, and b to e are each independently an integer of 0 to 4; In formula (VII-1), R ⁴ and R ⁶ are independently linear alkylene having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ ) CO—, —CON(CH ₃ )—, or a single bond, and in R ⁴ and R ⁶ , one or two non-adjacent straight-chain alkylene —CH ₂ — may be replaced with —O—; , R ⁵ and R ⁷ are independently a monocyclic hydrocarbon, a fused polycyclic hydrocarbon, a heterocyclic ring, or a single bond.

The monocyclic hydrocarbons in rings A and B of formula (V-3) and R ⁵ and R ⁷ of formula (VII-1) may be alicyclic or aromatic rings. The number of carbon atoms in the monocyclic hydrocarbon is preferably 6-12, more preferably 6-10, even more preferably 6-8. Specific examples of monocyclic hydrocarbons include benzene ring, cyclohexane ring, and cyclohexene ring.
The number of carbon atoms in the condensed polycyclic hydrocarbon in rings A and B of formula (V-3) and R ⁵ and R ⁷ of formula (VII-1) is preferably 10 to 26, preferably 10 to 18. is more preferable, and 10 to 14 is even more preferable. Specific examples of condensed polycyclic hydrocarbons include naphthalene ring, anthracene ring, and phenanthrene ring.
The heterocycles in ring A and ring B in formula (V-3) and R ⁵ and R ⁷ in formula (VII-1) may be alicyclic or aromatic rings. The number of carbon atoms in the heterocyclic ring is preferably 1-26, more preferably 3-14, even more preferably 3-8. A nitrogen atom, an oxygen atom, and a sulfur atom can be mentioned as a heteroatom contained as a ring member in the heterocyclic ring. Specific examples of heterocyclic rings include pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indole ring and oxazole ring.

When more uniform alignment of liquid crystal molecules is emphasized, formula (V-1), formula (V-2), formula (VI-1), formula (VI-2), formula (V-3) ) and compounds represented by formula (VII-1) can be particularly preferably used.
Preferred specific examples of compounds represented by formula (V-1), formula (V-2), formula (VI-1), formula (VI-2), formula (V-3) or formula (VII-1) As, the following compounds can be mentioned.

[Tetracarboxylic dianhydride containing no photoreactive structure]
The raw material for the polymer may contain a tetracarboxylic dianhydride other than the tetracarboxylic dianhydride containing no photoreactive structure. The tetracarboxylic dianhydride containing no photoreactive structure can be selected without limitation from known tetracarboxylic dianhydrides. Such tetracarboxylic dianhydrides include aromatic systems (including heteroaromatic ring systems) in which a dicarboxylic anhydride is directly bonded to an aromatic ring, and aliphatic dianhydrides in which a dicarboxylic anhydride is not directly bonded to an aromatic ring. It may belong to any group of systems (including heterocyclic ring systems).

Preferable examples of such tetracarboxylic dianhydrides include the following formulas (AN-I) to (AN-V) from the viewpoint of ease of raw material availability, ease of polymer production, and electrical properties of films. A tetracarboxylic dianhydride represented by any one is mentioned.

In Formula (AN-I), Formula (AN-IV) and Formula (AN-V), each X independently represents a single bond or -CH ₂ -. In formula (AN-II), G is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ -, -C (CF ₃ ) ₂ —, or a divalent group represented by the following formula (G13-1), wherein —CH ₂ — may be replaced with —O—, —CO— or —NH—.

In formula (G13-1), G ^13a and G ^13b each independently represent a single bond or a divalent group selected from -O-, -CONH- or -NHCO-. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

In formulas (AN-II) to (AN-IV), Y independently represents one selected from the group of trivalent groups below. Each bond of the trivalent group is attached to any carbon atom, and at least one hydrogen atom may be substituted with a methyl, ethyl or phenyl group.

In formulas (AN-III) to (AN-V), ring A ¹⁰ is a cyclic group obtained by removing hydrogen atoms by the number of bonds from a monocyclic hydrocarbon having 3 to 10 carbon atoms, or a cyclic group having 6 to 30 carbon atoms. It represents a cyclic group obtained by removing hydrogen atoms from a condensed polycyclic hydrocarbon by the number of bonds. At least one hydrogen atom in each cyclic group may be replaced with a methyl group, an ethyl group or a phenyl group. Moreover, the bond hanging on each ring is connected to any carbon constituting the ring, and two bonds may be bonded to the same carbon atom.

Furthermore, examples of tetracarboxylic dianhydrides include those represented by the following formulas (AN-1) to (AN-16-15).

In formula (AN-1), G ¹¹ represents a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group or a 1,4-cyclohexylene group. X ¹¹ independently represents a single bond or -CH ₂ -. G ¹² independently represents any of the following trivalent groups.

When G ¹² is >CH--, the hydrogen atom of >CH-- may be substituted with a methyl group. When G ¹² is >N-, G ¹¹ cannot be a single bond and -CH ₂ - and X ¹¹ cannot be a single bond. R ¹¹ represents a hydrogen atom or a methyl group.

Examples of the tetracarboxylic dianhydride represented by formula (AN-1) include compounds represented by the following formula.

In formulas (AN-1-2) and (AN-1-14), m is each independently an integer of 1 to 12.

In formula (AN-2), R ⁶¹ independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

Examples of the tetracarboxylic dianhydride represented by formula (AN-2) include compounds represented by the following formula.

In formula (AN-3), ring A ¹¹ represents a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formula.

In formula (AN-4), G ¹³ is a single bond, —(CH ₂ ) _m —, —O—, —S—, —C(CH ₃ ) ₂ —, —SO ₂ —, —CO—, —C (CF ₃ ) ₂ —, or a divalent group represented by the following formula (G13-1), where m is an integer of 1-12. Each ring A ¹¹ independently represents a cyclohexane ring or a benzene ring. G ¹³ may be attached to any position of ring A ¹¹ .

In formula (G13-1), G ^13a and G ^13b each independently represent a divalent group represented by a single bond, —O—, —CONH— or —NHCO—. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include compounds represented by the following formula.

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

In formula (AN-5), R ¹¹ independently represents a hydrogen atom or a methyl group. Of the two R ¹¹ , the R ¹¹ on the benzene ring binds to any of the substitutable positions on the benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include compounds represented by the following formula.

In formula (AN-6), X ¹¹ independently represents a single bond or -CH ₂ -. X ¹² represents -CH ₂ -, -CH ₂ CH ₂ - or -CH=CH-. n is 1 or 2; When n is 2, two X ¹² may be the same or different.

Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include compounds represented by the following formula.

In formula (AN-7), X ¹¹ represents a single bond or -CH ₂ -.

Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include compounds represented by the following formula.

In formula (AN-8), X ¹¹ represents a single bond or -CH ₂ -. ^R12 represents a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. Ring A ¹² represents a cyclohexane ring or a cyclohexene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include compounds represented by the following formula.

In formula (AN-9), each r is independently 0 or 1.

Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include compounds represented by the following formula.

In formula (AN-11), ring A ¹¹ independently represents a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include compounds represented by the following formula.

In formula (AN-12), each ring A ¹¹ independently represents a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include compounds represented by the following formula.

In formula (AN-15), w is an integer of 1-10.

Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include compounds represented by the following formula.

Examples of tetracarboxylic dianhydrides other than the above include the following compounds.

In the above tetracarboxylic dianhydride, suitable materials for improving each characteristic of the liquid crystal alignment film to be described later will be described. When it is important to further improve the orientation of the liquid crystal, compounds represented by formulas (AN-1), (AN-3), and (AN-4) are preferred, and formula (AN-1 -2), formula (AN-1-13), formula (AN-3-2), formula (AN-4-17), and formula (AN-4-29) are more preferred compounds represented by formula In (AN-1-2), m=4 or 8 is preferable, and in formula (AN-4-17), m=4 or 8 is preferable, and m=8 is more preferable.

When emphasis is placed on improving the transmittance of the liquid crystal display element, formula (AN-1-1), formula (AN-1-2), formula (AN-3-1), formula (AN-4- 17), formula (AN-4-30), formula (AN-5-1), formula (AN-7-2), formula (AN-10-1), formula (AN-16-3), formula ( AN-16-4), and compounds represented by formula (AN-2-1) are preferred, and among them, in formula (AN-1-2), m = 4 or 8 is preferred, and formula (AN-4- In 17), m=4 or 8 is preferable, and m=8 is more preferable.

When emphasis is placed on improving the VHR of the liquid crystal display element, formula (AN-1-1), formula (AN-1-2), formula (AN-3-1), formula (AN-4-17 ), formula (AN-4-30), formula (AN-7-2), formula (AN-10-1), formula (AN-16-3), formula (AN-16-4), and formula ( AN-2-1) is preferred, m = 4 or 8 is preferred in formula (AN-1-2), m = 4 or 8 in formula (AN-4-17) is preferred, and m=8 is more preferred.

Improving the rate of relaxation of residual charges (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film is effective as one of the methods for preventing burn-in. When emphasizing this purpose, formula (AN-1-13), formula (AN-3-2), formula (AN-4-21), formula (AN-4-29), and formula (AN- 11-3) are preferred.

[Diamine ioobidihydrazide containing a photoreactive structure]
The diamine and dihydrazide used as raw materials for the polymer contained in the liquid crystal aligning agent of the present invention include the diamines (formula (II-2), formula (III- 2), formula (IV-2), formula (V-2), formula (V-3), formula (VI-2), formula (VII-1), formula (VIII-1), and formula (VIII- In addition to compounds represented by any one of 2), diamines and dihydrazides that do not contain a photoreactive structure can be used. Diamines and dihydrazides that do not contain a photoreactive structure can be selected without limitation from known ones.

Diamines can be classified into two types according to their structures. That is, when the skeleton connecting two amino groups is viewed as a main chain, there are groups branched from the main chain, that is, diamines having side chain groups and diamines having no side chain groups. In the following description, diamines having such side chain groups may be referred to as side chain type diamines. Such diamines having no side chain groups are sometimes referred to as non-side chain diamines. This side chain group is a group having the effect of increasing the pretilt angle.
By properly using the non-side chain type diamine and the side chain type diamine properly, it is possible to correspond to the pretilt angle required for each.

Side chain type diamines are preferably used in combination to the extent that the properties of the present invention are not impaired. Moreover, it is preferable to select and use the side-chain type diamine and the non-side-chain type diamine for the purpose of improving the vertical alignment property, VHR, image sticking property and alignment property with respect to the liquid crystal.

Known diamines and dihydrazides are shown below.

In formula (DI-1) above, G ²⁰ represents —CH ₂ — or a group represented by formula (DI-1-a). When G ²⁰ is -CH ₂ -, at least one of m -CH ₂ - may be replaced with -NH-, -O-, and at least one hydrogen atom of m -CH ₂ - may be substituted with hydroxyl or methyl groups. m is an integer from 1 to 12; When m in DI-1 is 2 or more, a plurality of G ²⁰ may be the same or different. However, m is 1 when G ²⁰ is a group represented by formula (DI-1-a).

In formula (DI-1-a), v is each independently an integer of 1 to 6.

In Formula (DI-3), Formula (DI-6) and Formula (DI-7), G ²¹ is independently a single bond, —NH—, —NCH ₃ —, —O—, —S—, —S -S-, -SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O-(CH ₂ ) _m -O-, -N(CH ₃ )-(CH ₂ ) _k -N(CH ₃ )-, -(O-C ₂ H ₄ ) _m -O-, -O -CH ₂ -C(CF ₃ ) ₂ -CH ₂ -O-, -O-CO-(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, - (CH ₂ ) _m —NH—(CH ₂ ) _m —, —CO—(CH ₂ ) _k —NH—(CH ₂ ) _k —, —(NH—(CH ₂ ) _m ) _k —NH—, —CO —C ₃ H ₆ —(NH—C ₃ H ₆ ) _n —CO— or —S—(CH ₂ ) _m —S—, m is independently an integer of 1 to 12, k is 1 is an integer from ~5 and n is 1 or 2; In formula (DI-4), s is independently an integer of 0-2.

In formula (DI-5), G ³³ is a single bond, -NH-, -NCH ₃ -, -O-, -S-, -S-S-, -SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O-(CH ₂ ) _m -O-, -N( CH ₃ )--(CH ₂ ) _k --N(CH ₃ )--, --(O--C ₂ H ₄ ) _m --O--, --O--CH ₂ --C(CF ₃ ) ₂ --CH ₂ --O--, -O-CO-(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, -(CH ₂ ) _m -NH-(CH ₂ ) _m -, -CO —(CH ₂ ) _k —NH—(CH ₂ ) _k —, —(NH—(CH ₂ ) _m ) _k —NH—, —CO—C ₃ H ₆ —(NH—C ₃ H ₆ ) _n —CO -, or -S-(CH ₂ ) _m -S-, -N(Boc)-(CH ₂ ) _e -N(Boc)-, -NH-(CH ₂ ) _e -N(Boc)-, -N (Boc)-( _CH2 ) _e -,-( _CH2 ) _m -N(Boc)-CONH-( _CH2 ) _m -,-( _CH2 ) _m -N(Boc)-( _CH2 ) _m- , a group represented by the following formula (DI-5-a) or the following formula (DI-5-b), m is independently an integer of 1 to 12, k is an integer of 1 to 5 , e is an integer from 2 to 10, and n is 1 or 2. Boc is a t-butoxycarbonyl group.

In formulas (DI-6) and (DI-7), G ²² is independently a single bond, -O-, -S-, -CO-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, or an alkylene group having 1 to 10 carbon atoms.

At least one hydrogen atom of the cyclohexane ring and the benzene ring in formulas (DI-2) to (DI-7) is -F, -Cl, an alkylene group having 1 to 3 carbon atoms, -OCH ₃ , -OH, - CF ₃ , —CO ₂ H, —CONH ₂ , —NHC ₆ H ₅ , —NHC 6 H 5 , phenyl group, or benzyl group. One hydrogen atom may be substituted with one selected from the group of groups represented by any of the following formulas (DI-4-a) to (DI-4-i), and the formula (DI-5 ), at least one hydrogen atom of the cyclohexane ring and the benzene ring may be substituted with NHBoc or N(Boc) ₂ when G ³³ is a single bond.

A group in which the bonding position is not fixed to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. The bonding position of —NH ₂ to the cyclohexane ring or benzene ring is any position except the bonding position of G ²¹ , G ²² or G ³³ .

In formulas (DI-4-a) and (DI-4-b), R ²⁰ independently represents a hydrogen atom or —CH ₃ . In formulas (DI-4-f) and (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a t-butoxycarbonyl group.

In formula (DI-5-a), each q is independently an integer of 0-6. R ⁴⁴ represents a hydrogen atom, --OH, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

In formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), the bonding position of —NH ₂ bonded to the ring is any position.

In formula (DI-12), R ²¹ and R ²² each independently represent an alkyl group having 1 to 3 carbon atoms or a phenyl group, and G ²³ independently represents an alkylene group having 1 to 6 carbon atoms or a phenylene group. or represents a phenylene group substituted with an alkyl group, and w is an integer of 1-10.

In formula (DI-13), R ²³ independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms or -Cl, p is independently an integer of 0 to 3, q is an integer from 0 to 4;

In formula (DI-14), ring B represents a monocyclic heterocyclic aromatic group, R ²⁴ is a hydrogen atom, -F, -Cl, an alkyl group having 1 to 6 carbon atoms, an alkoxy group, an alkenyl group, It represents an alkynyl group, and q is independently an integer of 0-4. When q is 2 or more, multiple R ²⁴ may be the same or different. In formula (DI-15), ring C represents a heterocyclic aromatic group or a heterocyclic aliphatic group. In formula (DI-16), G ²⁴ represents a single bond, an alkylene group having 2 to 6 carbon atoms or a 1,4-phenylene group, and r is 0 or 1. A group in which the bonding position is not fixed to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. In formulas (DI-13) to (DI-16), the bonding position of —NH ₂ bonded to the ring is any position.

Specific examples of the diamines of formulas (DI-1) to (DI-16) having no side chain include the following formulas (DI-1-1) to (DI-16-1). .

Examples of diamines represented by formula (DI-1) are shown below.

In formulas (DI-1-7) and (DI-1-8), k is each independently an integer of 1-3. In formula (DI-1-9), v is each independently an integer of 1 to 6.

Examples of diamines represented by formulas (DI-2) to (DI-3) are shown below.

Examples of diamines represented by formula (DI-4) are shown below.

In formulas (DI-4-20) and (DI-4-21), m is each independently an integer of 1 to 12.

Examples of diamines represented by formula (DI-5) are shown below.
In formula (DI-5-1), m is an integer of 1-12.

In Formula (DI-5-12) and Formula (DI-5-13), m is each independently an integer of 1 to 12.

In formula (DI-5-16), v is an integer of 1-6.

In formula (DI-5-30), k is an integer of 1-5.

In formulas (DI-5-35) to (DI-5-37) and (DI-5-39), m is each independently an integer of 1 to 12, and formula (DI-5-38 ) and formula (DI-5-39), k is each independently an integer of 1 to 5, and n is an integer of 1 or 2 in formula (DI-5-40).

In formulas (DI-5-42) to (DI-5-44), e is each independently an integer of 2 to 10, and in formula (DI-5-45) R ⁴³ is a hydrogen atom, —NHBoc , or -N(Boc) ₂ . In Formulas (DI-5-42) to (DI-5-44), Boc is a t-butoxycarbonyl group.

Examples of diamines represented by formula (DI-6) are shown below.

Examples of diamines represented by formula (DI-7) are shown below.
In Formula (DI-7-3) and Formula (DI-7-4), m is each independently an integer of 1 to 12, and n is independently 1 or 2.

Examples of diamines represented by formula (DI-8) are shown below.

Examples of diamines represented by formula (DI-9) are shown below.

Examples of diamines represented by formula (DI-10) are shown below.

Examples of diamines represented by formula (DI-11) are shown below.

Examples of diamines represented by formula (DI-12) are shown below.

Examples of diamines represented by formula (DI-13) are shown below.

Examples of diamines represented by formula (DI-14) are shown below.

Examples of diamines represented by formula (DI-15) are shown below.

Examples of diamines represented by formula (DI-16) are shown below.

Next, the dihydrazide used as a starting material for the polymer of the present invention will be described. Known side chain-free dihydrazides include compounds represented by any of the following formulas (DIH-1) to (DIH-3).

In formula (DIH-1), G ²⁵ is a single bond, an alkylene group having 1 to 20 carbon atoms, —CO—, —O—, —S—, —SO ₂ —, —C(CH ₃ ) ₂ —, or — represents C(CF ₃ ) ₂ —.
In formula (DIH-2), ring D represents a cyclohexane ring, benzene ring or naphthalene ring, and at least one hydrogen atom in this group may be substituted with a methyl group, an ethyl group or a phenyl group. In formula (DIH-3), each ring E independently represents a cyclohexane ring or a benzene ring, and at least one hydrogen atom in this group may be substituted with a methyl group, an ethyl group, or a phenyl group. A plurality of E may be the same or different. Y represents a single bond, alkylene having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ -, or -C(CF ₃ ) ₂ - . In formulas (DIH-2) and (DIH-3), the bonding position of —CONHNH ₂ bonded to the ring is any position.

Examples of compounds represented by formulas (DIH-1) to (DIH-3) are shown below.
In formula (DIH-1-2), m is an integer of 1-12.

The above diamines and dihydrazides have the effect of improving the electrical properties of the liquid crystal display element, such as reducing the ion density.

A diamine suitable for increasing the pretilt angle will be described. Diamines having a side chain group suitable for increasing the pretilt angle include formulas (DI-31) to (DI-35) and formulas (DI-36-1) to (DI-36-8). and diamines represented by

In formula (DI-31), G ²⁶ is a single bond, -O-, -COO-, -OCO-, -CO-, -CONH-, -CH ₂ O-, -OCH ₂ -, -CF ₂ O- , —OCF ₂ —, or —(CH ₂ ) _ma —, where ma is an integer of 1-12. Preferred examples of G ²⁶ are a single bond, —O—, —COO—, —OCO—, —CH ₂ O— and an alkylene group having 1 to 3 carbon atoms, and particularly preferred examples are a single bond, —O—, --COO--, --OCO--, --CH ₂ O--, --CH ₂ -- and --CH ₂ CH ₂ --. R ²⁵ represents an alkyl group having 3 to 30 carbon atoms, a phenyl group, a group having a steroid skeleton, or a group represented by the following formula (DI-31-a). In this alkyl group, at least one hydrogen atom may be replaced by -F, and at least one -CH ₂ - may be replaced by -O-, -CH=CH- or -C≡C-. good. The hydrogen atom of this phenyl group is substituted with -F, -CH ₃ , -OCH ₃ , -OCH ₂ F, -OCHF ₂ , -OCF3, an alkyl group having 3 to 30 carbon atoms or an alkoxy group having 3 to 30 carbon atoms. may have been Although the bonding position of —NH ₂ bonded to the benzene ring is any position on the ring, the bonding position is preferably meta-position or para-position. That is, when the bonding position of the group "R ²⁵ -G ²⁶ -" is the 1st position, the two bonding positions are preferably the 3rd and 5th positions, or the 2nd and 5th positions.

In formula (DI-31-a), G ²⁷ , G ²⁸ and G ²⁹ are bonding groups, each of which is independently a single bond or an alkylene group having 1 to 12 carbon atoms. One or more -CH ₂ - may be replaced by -O-, -COO-, -OCO-, -CONH-, -CH=CH-. Ring B ²¹ , Ring B ²² , Ring B ²³ and Ring B ²⁴ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,3-dioxane-2,5-diyl group, represents a pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, naphthalene-1,5-diyl group, naphthalene-2,7-diyl group or anthracene-9,10-diyl group, and ring B ²¹ , ring B ²² , ring B ²³ and ring B ²⁴ , at least one hydrogen atom may be substituted with —F or —CH ₃ , and s, t and u are each independently an integer of 0 to 2. and the sum of these is 1 to 5, when s, t or u is 2, the two bonding groups within each parenthesis may be the same or different, and the two rings are They may be the same or different. R ²⁶ is a hydrogen atom, -F, -OH, an alkyl group having 1 to 30 carbon atoms, a fluorine-substituted alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, -CN, -OCH ₂ F, - represents OCHF ₂ or -OCF ₃ , wherein at least one -CH ₂ - of the alkyl group having 1 to 30 carbon atoms is substituted with a divalent group represented by the following formula (DI-31-b); good too.

In formula (DI-31-b), R ²⁷ and R ²⁸ are each independently an alkyl group having 1-3 carbon atoms, and v is an integer of 1-6. Preferred examples of R ²⁶ are C 1-30 alkyl groups and C 1-30 alkoxy groups.

In formulas (DI-32) and (DI-33), G ³⁰ independently represents a single bond, —CO— or —CH ₂ —, R ²⁹ independently represents a hydrogen atom or —CH ₃ , R ³⁰ independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. At least one hydrogen atom of the benzene ring in formula (DI-33) may be substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group. A group in which the bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. Preferably, one of the two groups "-phenylene-G ³⁰ -O-" in formula (DI-32) is attached to the 3-position of the steroid nucleus and the other is attached to the 6-position of the steroid nucleus. The bonding positions of the two groups "-phenylene-G ³⁰ -O-" in the formula (DI-33) to the benzene ring are preferably meta-positions or para-positions relative to the bonding position of the steroid nucleus. In formulas (DI-32) and (DI-33), --NH ₂ bound to the benzene ring indicates that the binding position on the ring is arbitrary.

In formulas (DI-34) and (DI-35), G ³¹ independently represents —O— or an alkylene group having 1 to 6 carbon atoms, and G ³² is a single bond or an alkylene group having 1 to 3 carbon atoms. represents R ³¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and at least one —CH ₂ — in this alkyl group may be replaced with —O—, —CH═CH— or —C≡C—. good. R ³² represents an alkyl group having 6 to 22 carbon atoms, and R ³³ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. Ring B ²⁵ is a 1,4-phenylene group or a 1,4-cyclohexylene group, and r is 0 or 1. The --NH ₂ binding to the benzene ring indicates that the binding position on the ring is optional, but it is independently preferred that it is meta-position or para-position with respect to the binding position of G ³¹ .

Examples of compounds represented by formula (DI-31) are shown below.

In formulas (DI-31-1) to (DI-31-11), each R ³⁴ independently represents an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably 5 carbon atoms. ∼25 alkyl groups or C5-25 alkoxy groups. Each R ³⁵ independently represents an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms.

In formulas (DI-31-12) to (DI-31-17), each R ³⁶ independently represents an alkyl group having 4 to 30 carbon atoms, preferably an alkyl group having 6 to 25 carbon atoms. Each R ³⁷ independently represents an alkyl group having 6 to 30 carbon atoms, preferably an alkyl group having 8 to 25 carbon atoms.

In formulas (DI-31-18) to (DI-31-43), each R ³⁸ independently represents an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably 3 carbon atoms. ∼20 alkyl groups or C3-20 alkoxy groups. Each R ³⁹ independently represents a hydrogen atom, -F, an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, -CN, -OCH ₂ F, -OCHF ₂ or -OCF ₃ , preferably is an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms. G ³³ represents an alkylene group having 1 to 20 carbon atoms.

Examples of compounds represented by formula (DI-32) are shown below.

Examples of compounds represented by formula (DI-33) are shown below.

Examples of compounds represented by formula (DI-34) are shown below.

In formulas (DI-34-1) to (DI-34-12), each R ⁴⁰ is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. and each R ⁴¹ independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

Examples of compounds represented by formula (DI-35) are shown below.

In formulas (DI-35-1) to (DI-35-3), R ³⁷ each independently represents an alkyl group having 6 to 30 carbon atoms, and R ⁴¹ each independently represents a hydrogen atom or represents 12 alkyl groups.

Compounds represented by formulas (DI-36-1) to (DI-36-8) are shown below.

In formulas (DI-36-1) to (DI-36-8), each R ⁴² independently represents an alkyl group having 3 to 30 carbon atoms.

Among the above diamines and dihydrazides, suitable materials for improving each property of the liquid crystal alignment film to be described later will be described. When emphasis is placed on improving the orientation of the liquid crystal, formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9) , Formula (DI-5-12), Formula (DI-5-13), Formula (DI-5-29), Formula (DI-6-7), Formula (DI-7-3), and Formula (DI -11-2) is preferably used. In formula (DI-5-1), m=2, 4, 6 or 8 is preferred, and m=8 is more preferred. In formula (DI-5-12), m=2 to 6 is preferred, and m=5 is more preferred. In formula (DI-5-13), m=1 or 2 is preferred, and m=1 is more preferred.

When emphasizing improving the transmittance, formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-24) and a diamine represented by formula (DI-7-3) are preferably used, and a compound represented by formula (DI-2-1) is more preferable. In formula (DI-5-1), m=2, 4, 6 or 8 is preferred, and m=8 is more preferred. In formula (DI-7-3), m=2 or 3 and n=1 or 2 are preferred, and m=3 and n=1 are more preferred.

When emphasizing improving the VHR of the liquid crystal display element, formula (DI-2-1), formula (DI-4-1), formula (DI-4-2), formula (DI-4-10 ), Formula (DI-4-15), Formula (DI-4-22), Formula (DI-5-28), Formula (DI-5-30), and Formula (DI-13-1) Diamines represented by formulas (DI-2-1), (DI-5-1), and (DI-13-1) are more preferred. In formula (DI-5-1), m=1 is preferred. In formula (DI-5-30), k=2 is preferred.

Improving the rate of relaxation of residual charges (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film is effective as one of the methods for preventing burn-in. When emphasizing this purpose, formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-5 -1), formula (DI-5-12), formula (DI-5-13), formula (DI-5-28), formula (DI-4-20), formula (DI-4-21), formula (DI-7-12) and compounds represented by the formula (DI-16-1) are preferably used, and the formulas (DI-4-1), (DI-5-1) and (DI -5-13) is more preferred. In formula (DI-5-1), m=2, 6 or 8 is preferred, and m=8 is more preferred. In formula (DI-5-12), m=2 to 6 is preferred, and m=5 is more preferred. In formula (DI-5-13), m=1 or 2 is preferred, and m=1 is more preferred. In formula (DI-7-12), m=3 or 4 is preferred, and m=4 is more preferred.

In each diamine, part of the diamine may be replaced with a monoamine, provided that the ratio of the monoamine to the diamine is 40 mol % or less. Such replacement can cause the termination of the polymerization reaction during production of the polyamic acid, and can suppress the further progress of the polymerization reaction. Therefore, by such replacement, the molecular weight of the resulting polymer (polyamic acid or derivative thereof) can be easily controlled, and for example, the coating properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. can be done. As long as the effects of the present invention are not impaired, one or two or more diamines may be substituted for the monoamine. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n- undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine is mentioned.

The raw material for the polyamic acid or derivative thereof may further contain a monoisocyanate compound as a monomer. By including the monoisocyanate compound in the monomer, the terminal of the obtained polyamic acid or derivative thereof is modified, and the molecular weight is adjusted. By using this terminal-modified polyamic acid or derivative thereof, for example, the application properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. From the above viewpoint, the content of the monoisocyanate compound in the monomer is preferably 1 to 10 mol % relative to the total amount of diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compounds include phenyl isocyanate and naphthyl isocyanate.

<Combination of Polymers: Blended Liquid Crystal Aligning Agent>
Liquid crystal aligning agent of the present invention may be composed of one type of polymer containing a structure represented by formula (1) or formula (2), the structure represented by formula (1) or formula (2) It may be composed of two or more types of polymers containing one or more types of polymers containing a structure represented by formula (1) or formula (2) and a structure represented by formula (1) or formula (2) It may be composed of one or more types of polymers other than the containing polymer.
As described above, the polymer other than the polymer containing the structure represented by formula (1) or formula (2) includes a polymer that does not contain a heat-reactive photoreactive structure but contains a photoreactive structure, and a polymer that contains a photoreactive structure. Polymers that do not contain reactive structures are included, and these polymers are also preferably polyamic acids or derivatives thereof.

In the specification of the present application, a liquid crystal aligning agent composed of one type of polymer may be referred to as a single-layer type liquid crystal aligning agent, and a liquid crystal aligning agent composed of two or more types of polymers may be referred to as a blend type liquid crystal aligning agent. .
A blend-type liquid crystal aligning agent is preferable when considering the balance between the storage stability of the liquid crystal aligning agent, the printability of the liquid crystal aligning agent on a display element substrate, and the characteristics of the liquid crystal aligning film to be formed. As the blend type liquid crystal aligning agent, specifically, two types of polymers selected from the group consisting of polyamic acids and derivatives thereof using tetracarboxylic dianhydride represented by formula (3) or formula (4). Liquid crystal aligning agent obtained by the above mixture, polyamic acid using tetracarboxylic dianhydride represented by formula (3) or formula (4) and non-thermally reactive polymer selected from the group consisting of derivatives thereof A liquid crystal aligning agent obtained by mixing one or more polymers selected from the group consisting of polyamic acids or derivatives thereof containing a photoreactive structure, or a tetra represented by formula (3) or formula (4) At least one polymer selected from the group consisting of polyamic acid and its derivatives using carboxylic acid dianhydride and at least one polymer selected from the group consisting of polyamic acid and its derivatives containing no photoreactive structure are mixed. A liquid crystal aligning agent obtained by

For the production of the photoreactive structure-free polyamic acid and its derivatives, the photoreactive structure-free tetracarboxylic dianhydride and the photoreactive structure-free diamine or dihydrazide are preferably used.

When two-component polymers are used for the liquid crystal aligning agent, for example, one polymer having excellent liquid crystal alignment ability is selected, and the other polymer has excellent performance in improving the electrical properties of the liquid crystal display element. There is an aspect of selecting a polymer that has In this case, by controlling the structure and molecular weight of each polymer, a liquid crystal aligning agent obtained by dissolving these polymers in a solvent is applied to the substrate and pre-dried to form a thin film, as described later. Alternatively, a polymer having excellent liquid crystal alignment ability can be segregated in the upper layer of the thin film, and a polymer having excellent performance in improving the electrical characteristics of the liquid crystal display element can be segregated in the lower layer of the thin film. This can be done by applying a phenomenon in which polymers with small surface energy separate into an upper layer and polymers with large surface energy into a lower layer in mixed polymers. Confirmation of such layer separation is that the surface energy of the formed liquid crystal alignment film is the same as or close to the surface energy of the film formed by the liquid crystal alignment agent containing only the polymer intended to be segregated to the upper layer. It can be confirmed by being a value.

As a method for developing layer separation, it is possible to reduce the molecular weight of the polymer to be segregated in the upper layer.

In a liquid crystal aligning agent comprising a mixture of polyamic acid and polyimide, layer separation can be realized by using polyimide as the polymer to be segregated in the upper layer.

The tetracarboxylic dianhydride represented by the formula (3) or (4) may be used as a raw material monomer for the polymer that segregates in the upper layer of the thin film, and is used as a raw material monomer for the polymer that segregates in the lower layer of the thin film. may be Alternatively, it may be used as a raw material monomer for both polymers.

As the tetracarboxylic dianhydride used for synthesizing the polyamic acid or its derivative that segregates in the upper layer of the thin film, in addition to the tetracarboxylic dianhydride represented by the formula (3) or (4), It can be selected without limitation from the known tetracarboxylic dianhydrides exemplified above.

Both the tetracarboxylic dianhydride represented by the formula (3) and the tetracarboxylic dianhydride represented by the formula (4) used for synthesizing the polyamic acid or its derivative that segregates in the upper layer of the thin film Tetracarboxylic dianhydrides other than carboxylic dianhydrides are formula (AN-1-1), formula (AN-2-1), formula (AN-3-1), formula (AN-4-5) , and compounds represented by formula (AN-4-17) are preferred, and formula (AN-4-17) is more preferred. In formula (AN-4-17), m=4 or 8 is preferred, and m=8 is more preferred.

The diamine and dihydrazide used for synthesizing the polyamic acid or its derivative that segregates in the upper layer of the thin film can be selected without limitation from the known diamines exemplified above.

Diamines and dihydrazides used for synthesizing the polyamic acid or its derivative that segregates in the upper layer of the thin film include formula (DI-4-13), formula (DI-4-15), and formula (DI-5-1). , and compounds represented by formula (DI-13-1) are preferably used. Among them, it is more preferable to use compounds represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), and formula (DI-13-1). In formula (DI-5-1), m=4 to 8 is preferred, and m=8 is more preferred.

The tetracarboxylic dianhydride represented by the formula (3) and the tetracarboxylic dianhydride represented by the formula (4) and the monomer containing the non-thermally reactive photoreactive structure segregate in the upper layer of the thin film. It is more preferably used for synthesizing polyamic acid or its derivatives.

As the tetracarboxylic dianhydride used for synthesizing the polyamic acid or its derivative that segregates in the lower layer of the thin film, in addition to the tetracarboxylic dianhydride represented by the formula (3) or (4), the above can be selected without limitation from the known tetracarboxylic dianhydrides exemplified in .

Tetracarboxylic dianhydrides used for synthesizing the polyamic acid or its derivative that segregates in the lower layer of the thin film include formula (AN-1-1), formula (AN-2-1), formula (AN-3 -2), and the compound represented by formula (AN-4-21) are preferred, and formula (AN-1-1), formula (AN-2-1), and formula (AN-3-2) are more preferable.

The diamine and dihydrazide used for synthesizing the polyamic acid or its derivative that segregates to the lower layer of the thin film can be selected without limitation from the known diamines exemplified above.

Diamines and dihydrazides used for synthesizing the polyamic acid or its derivative that segregates in the lower layer of the thin film include Formula (DI-4-1), Formula (DI-4-2), and Formula (DI-4-10). , Formula (DI-4-18), Formula (DI-4-19), Formula (DI-5-1), Formula (DI-5-9), Formula (DI-5-28), Formula (DI- 5-30), formula (DI-13-1), and formula (DIH-2-1) are preferred. In formula (DI-5-1), compounds where m=1 or 2 are preferred, and in formula (DI-5-30), compounds where k=2 are preferred. Among them, formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), formula (DI-13-1) and formula (DIH -1-2) is more preferred.

Both the polyamic acid or its derivative segregating in the upper layer of the thin film and the polyamic acid or its derivative segregating in the lower layer of the thin film are described below as a method for synthesizing the polyamic acid or its derivative, which is an essential component of the liquid crystal aligning agent of the present invention. can be synthesized according to the method described in .

<Solvent>
The liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of coating properties of the liquid crystal aligning agent and adjusting the concentration of the polymer having the structure represented by formula (1) or formula (2). The solvent can be applied without particular limitation as long as it has the ability to dissolve the polymer component. The solvent includes a wide range of solvents that are commonly used in manufacturing processes and applications of polymer components such as polyamic acid and soluble polyimide, and can be appropriately selected according to the purpose of use. The solvent may be one kind or a mixed solvent of two or more kinds.

Examples of the solvent include a solvent affinity for the polyamic acid or its derivative, and other solvents intended to improve coatability.

Aprotic polar organic solvents that are affinity for polyamic acid or derivatives thereof include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, and N-methylpropion. Lactones such as amides, N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutyramide, γ-butyrolactone, γ-valerolactone, etc. be done.

Among these hydrophilic solvents, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, and γ-valerolactone are more preferred.

Examples of other solvents aimed at improving coatability include diisobutyl ketone, alkyl lactate, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutylcarbinol, tetralin, isophorone, ethylene glycol monoalkyl ether such as ethylene glycol monobutyl ether, diethylene glycol monoalkyl ether such as diethylene glycol monoethyl ether, diethylene glycol dialkyl ether such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, ethylene glycol monoalkyl or phenyl Propylene glycol monoalkyl ether such as acetate, triethylene glycol monoalkyl ether, propylene glycol monomethyl ether, 1-butoxy-2-propanol, dialkyl malonate such as diethyl malonate, dipropylene glycol monoalkyl such as dipropylene glycol monomethyl ether Ester compounds such as ethers and these acetates are included.

Among these other solvents, diisobutyl ketone, 4-methyl-2-pentanol, diisobutylcarbinol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1- More preferred are butoxy-2-propanol, propylene glycol monomethyl ether and dipropylene glycol monomethyl ether, butyl cellosolve acetate.

The concentration of the polymer having the structure represented by formula (1) or (2) in the liquid crystal aligning agent of the invention is preferably 0.1 to 40% by weight. When applying this liquid crystal aligning agent to a substrate, it may be necessary to dilute the contained polymer in advance with a solvent in order to adjust the film thickness.

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

The preferred range of the viscosity of the liquid crystal aligning agent of the present invention varies depending on the coating method, the concentration of the polyamic acid or its derivative, the type of polyamic acid or its derivative used, and the type and ratio of the solvent. For example, it is 5 to 100 mPa·s (more preferably 10 to 80 mPa·s) in the case of coating by a printing machine. If it is 5 mPa·s or more, a sufficient film thickness can be easily obtained, and if it is 100 mPa·s or less, printing unevenness can be easily suppressed. 5 to 200 mPa·s (more preferably 10 to 100 mPa·s) is suitable for application by spin coating. When applying using an inkjet coating device, 5 to 50 mPa·s (more preferably 5 to 20 mPa·s) is suitable. The viscosity of the liquid crystal aligning agent is measured by a rotational viscosity measurement method, for example, using a rotational viscometer (Model TVE-20L manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25° C.).

<Additive>
The liquid crystal aligning agent of the present invention may further contain various additives. Various additives can be selected and used according to their respective purposes in order to improve various properties of the alignment film. An example is shown below.

[Alkenyl-Substituted Nadimide Compound]
For example, the liquid crystal aligning agent of the present invention may further contain an alkenyl-substituted nadimide compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. Alkenyl-substituted nadimide compounds may be used alone or in combination of two or more. The content of the alkenyl-substituted nadimide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, more preferably 1 to 20% by weight, based on the polyamic acid or its derivative, for the above purpose. is more preferable. The alkenyl-substituted nadimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polyamic acid or derivative thereof used in the present invention. Preferred alkenyl-substituted nadimide compounds include alkenyl-substituted nadimide compounds disclosed in JP-A-2008-096979, JP-A-2009-109987, and JP-A-2013-242526. Particularly preferred alkenyl-substituted nadimide compounds include bis{4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl}methane, N,N'-m-xylylene- Bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide), N,N'-hexamethylene-bis(allylbicyclo[2.2.1]hept-5-ene -2,3-dicarboximide).

[Compound having a radically polymerizable unsaturated double bond]
For example, the liquid crystal aligning agent of the present invention may further contain a compound having a radically polymerizable unsaturated double bond for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. The compound having a radically polymerizable unsaturated double bond may be one kind of compound or two or more kinds of compounds. The compounds having a radically polymerizable unsaturated double bond do not include alkenyl-substituted nadimide compounds. Preferred compounds with radically polymerizable unsaturated double bonds include N,N'-methylenebisacrylamide, N,N'-dihydroxyethylene-bisacrylamide, ethylenebisacrylate, and 4,4'-methylenebis( N,N-dihydroxyethylene acrylate aniline), triallyl cyanurate, and other radicals disclosed in JP 2009-109987, JP 2013-242526, WO 2014/119682, WO 2015/152014 A compound having a polymerizable unsaturated double bond can be mentioned. The content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, based on the polyamic acid or its derivative for the above purpose. preferable.

[Oxazine compound]
For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. The oxazine compound may be one kind of compound or two or more kinds of compounds. The content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, more preferably 1 to 20% by weight, based on the polyamic acid or its derivative, for the above purpose. is more preferable.

The oxazine compound is preferably an oxazine compound that is soluble in a solvent that dissolves polyamic acid or a derivative thereof and that has ring-opening polymerizability. Preferred oxazine compounds include oxazine compounds represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10). Examples include the oxazine compounds disclosed in JP-A-2013-242526.

[Oxazoline compound]
For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. An oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one kind of compound or two or more kinds of compounds. The content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, more preferably 1 to 20% by weight, based on the polyamic acid or its derivative for the above purpose. is preferred. Preferred oxazoline compounds include oxazoline compounds disclosed in JP-A-2010-054872 and JP-A-2013-242526. More preferred is 1,3-bis(4,5-dihydro-2-oxazolyl)benzene.

[Epoxy compound]
For example, the liquid crystal aligning agent of the present invention further contains an epoxy compound for the purpose of stabilizing the electrical properties in the liquid crystal display element for a long period of time, the purpose of improving the hardness of the film, or the purpose of improving the adhesion with the sealant. may be The epoxy compound may be one compound, or two or more compounds. The content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, more preferably 1 to 10% by weight, based on the polyamic acid or its derivative, for the above purpose. is more preferable.
Various compounds having one or more epoxy rings in the molecule can be used as the epoxy compound.
A compound having two or more epoxy rings in the molecule is preferable, and a compound having three or four epoxy rings is more preferable for the purpose of improving the hardness of the film or improving the adhesion to the sealant.
Examples of epoxy compounds include those disclosed in JP-A-2009-175715, JP-A-2013-242526, JP-A-2016-170409, and International Publication 2017/217413. Preferred epoxy compounds include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxy Silane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3- epoxypropyl), 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylenediamine.
In addition to the above, an oligomer or polymer having an epoxy ring can also be added. As the oligomer or polymer having an epoxy ring, the oligomer or polymer disclosed in JP-A-2013-242526 can be used.

[Silane compound]
For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving adhesion to the substrate and sealing agent. The content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, more preferably 0.5 to 20% by weight, based on the polyamic acid or its derivative, for the above purpose. More preferably ~10% by weight.
As the silane coupling agent, the silane coupling agents disclosed in JP-A-2013-242526, JP-A-2015-212807, JP-A-2018-173545, and International Publication 2018/181566 can be used.
Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, para-aminophenyltrimethoxysilane, and 3 -aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-trimethoxypropylsuccinic acid, 3-triethoxypropylsuccinic acid, 3-isocyanatopropyltriethoxysilane, 3-ureidopropyltriethoxysilane mentioned.

In addition to the additives described above, a compound having a cyclocarbonate group, a compound having a hydroxyalkylamide moiety or a hydroxyl group is added for the purpose of increasing the strength of the alignment film or stabilizing the electrical properties of the liquid crystal display element for a long period of time. can also Specific compounds include compounds disclosed in JP-A-2016-118753 and International Publication 2017/110976. Preferred compounds include the following formulas (HD-1) to (HD-4). The content of these compounds is preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight, even more preferably 1 to 10% by weight, relative to the polyamic acid or derivative thereof.

In addition, an antistatic agent can be used when the antistatic properties need to be improved, and an imidization catalyst can be used when the imidization is to proceed at a low temperature. Examples of imidization catalysts include imidization catalysts disclosed in JP-A-2013-242526.

<< liquid crystal alignment film >>
Next, the liquid crystal alignment film of the present invention will be described.
The liquid crystal alignment film of the present invention is formed from the liquid crystal alignment agent for photo-alignment of the present invention. The liquid crystal aligning agent for photo-alignment of the present invention can form a liquid crystal alignment film by causing chemical reaction and alignment amplification of structural units having a photoreactive structure in the step of heating and baking. The liquid crystal aligning agent for photo-alignment of the present invention containing polyamic acid or a derivative thereof can further undergo an imidation reaction to form a liquid crystal alignment film.
Below, the formation method of the liquid crystal aligning film by the liquid crystal aligning agent for photoalignment of this invention is demonstrated.

The liquid crystal alignment film of the present invention can be obtained by a normal method for producing a liquid crystal alignment film from a liquid crystal alignment agent for photoalignment. The liquid crystal aligning film of the present invention includes, for example, a step of forming a coating film of the liquid crystal aligning agent for photoalignment of the present invention, a step of heating and drying the coating film to form a film of the liquid crystal aligning agent, and a liquid crystal aligning agent. It can be obtained through a step of irradiating the film with light to impart anisotropy and a step of heating and baking the film of the liquid crystal aligning agent to which the anisotropy is imparted. During this heating and baking, in the liquid crystal aligning agent for photo-alignment according to the present invention, the structural units having a photo-reactive structure undergo a chemical reaction to reduce or eliminate photo-reactive groups. For this reason, the liquid crystal alignment film of the present invention is preferably irradiated with light to impart anisotropy after the coating process and the heat drying process, and then subjected to the heat baking process. In the present specification, making a photoreactive group of a photoreactive structure disappear is sometimes referred to as making the photoreactive structure into a structure that does not react with light.

When emphasis is placed on improving the orientation, in the heating and baking step of the liquid crystal alignment film according to the present invention, in the polymer containing the liquid crystal alignment agent, at least two processes of chemical reaction, orientation amplification and imidization reaction are allowed to take time. It is preferable to start with a significant difference. The order of starting the chemical reaction, orientation amplification, and imidization reaction is not particularly limited. For example, the chemical reaction, orientation amplification, and imidization reaction may be started in this order. You can start. Moreover, the chemical reaction, the orientation amplification, and the imidization reaction may all start at different times, and the chemical reaction, the orientation amplification, and the imidization may overlap with each other. That is, at least two processes of chemical reaction, orientational amplification and imidization reaction may proceed at the same time if there is a difference in their initiation times. Thus, by shifting the start timing of the chemical reaction, orientation amplification, and imidization reaction, the anisotropy is further increased, and in addition to the stability to light, it is possible to obtain a liquid crystal orientation film exhibiting superior orientation. can. The start timing of the chemical reaction, orientation amplification, and imidization reaction can be controlled by the heating and baking conditions of the liquid crystal aligning agent. For example, when the chemical reaction initiation temperature of the polymer contained in the liquid crystal aligning agent is lower than the orientation amplification initiation temperature, the film of the liquid crystal aligning agent is heated to a temperature within the range of the chemical reaction initiation temperature or higher and the orientation amplification initiation temperature. By holding at , the chemical reaction can be started and progressed prior to the orientation amplification, and then by raising the temperature to the orientation amplification start temperature or higher and holding it, the orientation is delayed from the start of the chemical reaction. can be amplified. Here, for explanations of the cyclization initiation temperature and the orientation amplification initiation temperature as examples of the chemical reaction initiation temperature, reference can be made to the description of [Cyclization initiation temperature and orientation amplification initiation temperature]. Further, for specific heating and baking conditions, the description in the section of the heating and baking process can be referred to.

A coating film can be formed by apply|coating the liquid crystal aligning agent of this invention to the board|substrate in a liquid crystal display element similarly to preparation of a normal liquid crystal aligning film. The substrate may be provided with electrodes such as ITO (Indium Tin Oxide), IZO (In ₂ O ₃ —ZnO), IGZO (In—Ga—ZnO ₄ ) electrodes, color filters, and the like. Substrates made of acrylic, polycarbonate, polyimide, or the like can be used.

A spinner method, a printing method, a dipping method, a dropping method, an inkjet method, and the like are generally known as methods for applying a liquid crystal aligning agent to a substrate. These methods are equally applicable in the present invention.

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

The heating and baking step can be performed under the conditions necessary for the polyamic acid or its derivative to undergo an imidation reaction. For baking the coating film, a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, and the like are generally known. These methods are similarly applicable in the present invention. In general, it is preferably carried out at a temperature of about 100 to 300°C for 1 minute to 3 hours, more preferably 120 to 280°C, even more preferably 150 to 250°C. Moreover, it is possible to heat and bake a plurality of times at different temperatures. A plurality of heating devices set to different temperatures may be used, or one heating device may be used while sequentially changing the temperatures to different temperatures. When heating and firing are performed twice at different temperatures, it is preferable to perform the first firing at a temperature of 90 to 180° C. and the second firing at a temperature of 185° C. or higher. In addition, firing can be performed by changing the temperature from a low temperature to a high temperature. When firing is performed by changing the temperature, the initial temperature is preferably 90 to 180°C. The final temperature is preferably 185-300°C, more preferably 190-230°C. When it is important to improve the orientation, it is preferable to gently raise the temperature in the heating step. For example, heating can be performed by changing the temperature from a low temperature to a high temperature, or heating and baking can be performed multiple times at different temperatures while increasing the temperature stepwise. When firing is performed by changing the temperature, the time to reach the final temperature is preferably 5 minutes or more, the final temperature is preferably 185°C to 300°C, more preferably 190 to 230°C. When heating and firing multiple times, the initial firing temperature is preferably 90 to 180°C, and the final firing temperature is preferably 185 to 300°C. For example, heat and bake at 110°C and then heat and bake at 220°C, heat and bake at 110°C and then heat and bake at 230°C, heat and bake at 130°C and then heat and bake at 220°C, and heat and bake at 150°C and then heat and bake at 200°C. It is preferable to heat and bake at 150°C and then heat and bake at 220°C, heat and bake at 150°C and then heat and bake at 230°C, and heat and bake at 170°C and then heat and bake at 200°C. It is also preferable to increase the number of stages and heat and bake while gently raising the temperature. When heating and baking are performed in two or more steps by changing the heating temperature, the heating time in each heating step is preferably 5 to 30 minutes.

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

A method for forming the liquid crystal alignment film of the present invention by a photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using a photo-alignment method is obtained by irradiating the thin film after heat-drying the coating film with linearly polarized or non-polarized radiation to impart anisotropy to the thin film. It can be formed by heating and baking. Alternatively, the thin film can be formed by drying the coating film by heating, baking it by heating, and then irradiating the thin film with linearly polarized or non-polarized radiation. From the viewpoint of orientation, it is preferable to carry out the radiation irradiation step before the heating and baking step.

Further, in order to increase the liquid crystal alignment ability of the liquid crystal alignment film, linearly polarized or non-polarized radiation can be irradiated while heating the coating film. Irradiation with radiation may be performed in the step of drying the coating film by heating, or in the step of baking by heating, or may be performed between the step of drying by heating and the step of baking by heating. The heat drying temperature in this step is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 120°C. The heating and firing temperature in this step is preferably in the range of 30°C to 300°C, more preferably in the range of 50°C to 250°C.

As the radiation, for example, ultraviolet light containing light with a wavelength of 150 to 800 nm or visible light can be used, but ultraviolet light containing light with a wavelength of 300 to 400 nm is preferable. Also, linearly polarized light or non-polarized light can be used. The light is not particularly limited as long as it can impart liquid crystal alignment ability to the thin film, but linearly polarized light is preferable when a strong alignment control force is to be exerted on the liquid crystal.

The liquid crystal alignment film of the present invention can exhibit high liquid crystal alignment ability even with low-energy light irradiation. The dose of linearly polarized light in the radiation irradiation step is preferably 0.05 to 20 J/cm ² , more preferably 0.5 to 10 J/cm ² . The wavelength of linearly polarized light is preferably 200-400 nm, more preferably 300-400 nm. Although the irradiation angle of the linearly polarized light to the film surface is not particularly limited, it is preferably perpendicular to the film surface as much as possible from the viewpoint of shortening the alignment treatment time when it is desired to develop a strong alignment control force on the liquid crystal. Moreover, the liquid crystal aligning film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating it with the linearly polarized light.

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

The liquid crystal alignment film of the present invention can be preferably obtained by a method further including steps other than the steps described above. For example, the liquid crystal alignment film of the present invention does not necessarily require a step of washing the film after baking or irradiation with a washing liquid, but a washing step can be provided for convenience of other steps.

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

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

Although the film thickness of the liquid crystal alignment film of the present invention is not particularly limited, it is preferably 10 to 300 nm, more preferably 30 to 150 nm. The film thickness of the liquid crystal alignment film of the present invention can be measured by a known film thickness measuring device such as a profilometer or an ellipsometer.

The liquid crystal alignment film of the present invention is characterized by having particularly large anisotropy of alignment. The magnitude of such anisotropy can be evaluated by the method using polarized IR described in JP-A-2005-275364. It can also be evaluated by a method using ellipsometry. Specifically, the retardation value of the liquid crystal alignment film can be measured using a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain. In other words, a polymer film with a large retardation value has a large degree of orientation, and when used as a liquid crystal alignment film, it is thought that a liquid crystal alignment film with a larger anisotropy has a large alignment control force with respect to the liquid crystal composition. be done.

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

The liquid crystal alignment film of the present invention can be used for alignment control of liquid crystal compositions for liquid crystal displays such as smartphones, tablets, vehicle-mounted monitors, and televisions. In addition to alignment of liquid crystal compositions for liquid crystal displays, it can be used for alignment control of optical compensation materials and all other liquid crystal materials. Moreover, since the liquid crystal alignment film of the present invention has a large anisotropy, it can be used alone as an optical compensation material.

<<Liquid crystal display element>>
Next, the liquid crystal display device of the present invention will be explained.
The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention.
INDUSTRIAL APPLICABILITY The liquid crystal display device of the present invention can maintain a high voltage holding ratio and realize high display quality even when a high-brightness backlight is mounted.
The liquid crystal display device of the present invention will be described in detail. The present invention comprises a pair of substrates arranged to face each other, electrodes formed on one or both of the facing surfaces of the pair of substrates, and electrodes formed on the facing surfaces of the pair of substrates. A liquid crystal display element having a liquid crystal alignment film formed with the liquid crystal aligning film, a liquid crystal layer formed between the pair of substrates, and a pair of polarizing films, a backlight, and a driving device arranged so as to sandwich the counter substrate, wherein the A liquid crystal alignment film is composed of the liquid crystal alignment film of the present invention.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Such electrodes include, for example, ITO and metal vapor deposition films. Also, the electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired patterned shape, for example. The desired shape of the electrode includes, for example, a comb-shaped or zig-zag structure. The electrodes may be formed on one substrate of the pair of substrates, or may be formed on both substrates. The form of formation of the electrodes differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element (lateral electric field type liquid crystal display element), electrodes are arranged on one of the pair of substrates, and on other liquid crystal display elements. In the case of (1), electrodes are arranged on both of the pair of substrates. The liquid crystal alignment layer is formed on the substrate or electrode.

In the case of a homogeneously aligned liquid crystal display element (for example, IPS, FFS, etc.), the configuration includes, from the backlight side, at least a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, It has a second substrate and a second polarizing film, and the polarizing axis of the polarizing film is such that the polarizing axis of the first polarizing film (direction of polarized light absorption) and the polarizing axis of the second polarizing film intersect (preferably perpendicular). At this time, the polarizing axis of the first polarizing film and the liquid crystal orientation direction can be set to be parallel or perpendicular to each other. A liquid crystal display device in which the polarization axis of the first polarizing film and the liquid crystal orientation direction are parallel to each other is called O-mode, and a liquid crystal display device in which they are perpendicular to each other is called E-mode. The liquid crystal alignment film of the present invention can be applied to both O-mode and E-mode, and can be selected depending on the purpose.

Dichroic compounds are used in many photoisomerizable materials. Therefore, the polarization axis of the polarized light irradiated in order to add anisotropy to the liquid crystal aligning agent is aligned parallel to the polarization axis of the polarized light from the polarizing film arranged on the backlight side (the liquid crystal aligning agent of the present invention When used, the arrangement is in O-mode), and the transmittance in the light absorption wavelength range of the liquid crystal alignment film increases. Therefore, the transmittance of the liquid crystal display element can be further improved.

The liquid crystal layer is formed in such a manner that the liquid crystal composition is sandwiched between the pair of substrates whose surfaces on which the liquid crystal alignment films are formed face each other. In the formation of the liquid crystal layer, spacers such as fine particles and resin sheets can be used as necessary to form an appropriate gap between the pair of substrates.

A vacuum injection method and an ODF (One Drop Fill) method are known as methods of forming a liquid crystal layer.

In the vacuum injection method, a gap (cell gap) is provided so that the surfaces of the liquid crystal alignment films face each other, a liquid crystal injection port is left, a sealant is printed, and the substrates are bonded together. After liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealant using a vacuum differential pressure, the injection port is sealed to manufacture the liquid crystal display element.

In the ODF method, a sealant is printed on the outer circumference of the liquid crystal alignment film surface of one of a pair of substrates, and liquid crystal is dropped on the inner region of the sealant, and then the other substrate is placed so that the liquid crystal alignment film surfaces face each other. glue together. Then, the liquid crystal is spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, thereby manufacturing a liquid crystal display element.

In addition to the UV curing type, a heat curing type is also known as a sealant used for laminating substrates. Printing of the sealant can be performed by, for example, a screen printing method.

The liquid crystal composition is not particularly limited, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions with positive dielectric anisotropy include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Publication No. 5-501735, Japanese Patent Laid-Open No. 8-157826, Japanese Patent Laid-Open No. 8-231960, Japanese Patent Laid-Open No. 9-241644. (EP885272A1), JP-A-9-302346 (EP806466A1), JP-A-8-199168 (EP722998A1), JP-A-9-235552, JP-A-9-255956, JP-A-9-241643 (EP885271A1), JP-A-9 10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822 and the like liquid crystal compositions disclosed in each publication. .

Preferred examples of liquid crystal compositions having negative dielectric anisotropy include JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, and JP-A-8. -104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP-A-10-236993, JP-A-10- 236994, JP-A-10-237000, JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, JP-A-10-237076, JP-A-10-237448 No. (EP967261A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001 -019965, JP 2001-072626, JP 2001-192657, JP 2010-037428, WO 2011/024666, WO 2010/072370, JP 2010-537010, JP 2012- 077201, JP-A-2009-084362 and other publications disclose liquid crystal compositions.

A liquid crystal composition having a positive or negative dielectric anisotropy may be used by adding one or more optically active compounds.

Further, for example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain an additive from the viewpoint of improving the orientation. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, polymerization inhibitors, and the like. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, and polymerization inhibitors include compounds disclosed in International Publication 2015/146330 and the like. .

A polymerizable compound can be mixed into the liquid crystal composition in order to adapt it to a PSA (polymer sustained alignment) mode liquid crystal display device. Preferred examples of polymerizable compounds are compounds with polymerizable groups such as acrylates, methacrylates, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes, oxetanes), vinyl ketones. Preferred compounds include compounds disclosed in International Publication 2015/146330 and the like.

A polymerizable compound can be mixed into the liquid crystal composition in order to adapt it to a PSA (polymer sustained alignment) mode liquid crystal display device. Preferred examples of polymerizable compounds are compounds with polymerizable groups such as acrylates, methacrylates, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes, oxetanes), vinyl ketones. Preferred compounds include compounds disclosed in International Publication 2015/146330 and the like.

<<Other Modes of Use of Polymer Having Structure Represented by Formula (1) or Formula (2)>>
Polymers having a structure represented by the above formula (1) or formula (2), in addition to the above liquid crystal alignment film, optical anisotropic body, retardation film, optical compensation film, antireflection film, various films, or It can be used for materials such as optical members. Here, when a polymer having a structure represented by formula (1) or formula (2) is used for an optical anisotropic body, a retardation film, an optical compensation film, an antireflection film, various films, or an optical member, these may be composed of one type of polymer having a structure represented by formula (1) or formula (2), or two types of polymers having a structure represented by formula (1) or formula (2) or more may be mixed. Among these applications, applications in which orientation is more important, such as retardation films, are preferably composed of one type of polymer having a structure represented by formula (1) or formula (2).

EXAMPLES The features of the present invention will be more specifically described below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

Measurement method and evaluation method [measurement of weight average molecular weight (Mw)]
The weight-average molecular weight of the polyamic acid was measured by GPC using a 2695 separation module/2414 differential refractometer (manufactured by Waters) and converted to polystyrene. The sample used for the measurement was the obtained polyamic acid in a phosphoric acid-DMF mixed solution (phosphoric acid/N,N-dimethylformamide = 0.6/100: mixed solution by weight), with a polyamic acid concentration of about 2. It is diluted to be weight %. HSPgel RT MB-M (manufactured by Waters) was used as a column, phosphoric acid-DMF mixed solution was used as a developing solvent, and measurement was performed under conditions of a column temperature of 50° C. and a flow rate of 0.40 mL/min. TSK standard polystyrene manufactured by Tosoh Corporation was used as the standard polystyrene.

[Evaluation of voltage holding ratio]
The voltage holding ratio of the liquid crystal display element was measured by applying a rectangular wave with a wave height of ±5 V to the cell at 60° C. according to the method described in “Mizushima et al. . The voltage retention rate is an index indicating how much the applied voltage is retained after the frame cycle, and if this value is 100%, it means that all charges are retained. A cell mounted with a negative type liquid crystal can be regarded as a liquid crystal display element with good display quality if the voltage holding ratio is 97.5% or more.

[Evaluation of transmittance]
A liquid crystal alignment film is formed on a transparent glass substrate, and the transmittance at 330 nm to 480 nm is measured with an ultraviolet-visible spectrophotometer V-660 (manufactured by JASCO Corporation), and the average transmittance at 380 nm to 430 nm is calculated. was obtained and the transmittance was evaluated.

[Measurement of AC afterimage (evaluation of liquid crystal orientation)]
The AC afterimage was measured according to the method described in International Publication No. 2000/43833.
Specifically, the luminance-voltage characteristic (BV characteristic) of the manufactured liquid crystal cell was measured, and this was defined as the luminance-voltage characteristic before stress application: B (before). Next, after applying an alternating current of 4.5 V and 60 Hz to the liquid crystal cell for 20 minutes, it was short-circuited for 1 second, and the luminance-voltage characteristics (BV characteristics) were measured again. This was taken as the luminance-voltage characteristic after stress application: B (after). Here, using the luminance at a voltage of 1.3 V of each measured luminance-voltage characteristic, the luminance change rate ΔB (%) was obtained by the following formula. A smaller value of ΔB (%) means that the generation of the AC afterimage can be suppressed, that is, the liquid crystal orientation is better.
ΔB (%) = [B (after) - B (before)] / B (before) × 100

Compound used [tetracarboxylic dianhydride represented by formula (4)]
The tetracarboxylic dianhydride represented by formula (4) used in the preparation of the varnish in this example is shown below.

[Tetracarboxylic dianhydride containing no thermally reactive photoreactive structure]
Tetracarboxylic dianhydrides other than the tetracarboxylic dianhydride represented by the formula (4) used in the preparation of the varnish in this example are shown below.

[Diamine]
The diamines used in the preparation of the varnishes in this example are shown below.

[solvent]
The solvent used for preparation of the liquid crystal aligning agent in this example is shown below.
NMP: N-methyl-2-pyrrolidone BC: butyl cellosolve (ethylene glycol monobutyl ether)
GBL: γ-butyrolactone

Synthesis of tetracarboxylic dianhydride represented by formula (4 ) Among the tetracarboxylic dianhydrides represented by formula (4) used in this example, tetracarboxylic dianhydride (4-2- 2) and (4-2-3) were synthesized by the following procedure. Tetracarboxylic dianhydrides (4-2-1) and (4-2-4) are according to the synthesis examples of tetracarboxylic dianhydrides (4-2-2) and (4-2-3) synthesized by

[Synthesis Example 1] Synthesis of compound (4-2-2) <First step: protection>
3-Hydroxybenzyl alcohol (30.0 g, 241.7 mmol) and acetone (750 mL) were added to a 2000 mL three-necked flask equipped with a reflux tube, thermometer and nitrogen inlet tube. Potassium carbonate (39.5 g, 580.0 mmol) and 4-methoxybenzyl chloride (41.6 g, 265.8 mmol) were then added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After cooling the reaction solution, it was filtered and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 59.0 g, quantitative).

<Second step: chlorination>
A 1000 mL three-necked flask equipped with a dropping funnel, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the first step (59.0 g, 241.6 mmol), dichloromethane (300 mL), and triethylamine (40.4 mL, 290.0 mmol). ) was added and ice bathed. Methanesulfonyl chloride (22.4 mL, 290.0 mmol) was then added dropwise and the solution was stirred for 24 hours at room temperature under a nitrogen atmosphere. After completion of the reaction, dichloromethane (200 mL) was added and washed with water (500 mL×2 times). After drying the organic layer with magnesium sulfate, the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 60.9 g, 96%).

<Third step: ether synthesis>
Sodium ethoxide (18.3 g, 255.1 mmol) and methanol (300 mL) were added to a 2000 mL three-necked flask equipped with a reflux tube, a dropping funnel, a thermometer and a nitrogen inlet tube, and placed in an ice bath. A solution of the compound from the second step (60.9 g, 231.9 mmol) in methanol (600 mL) was added dropwise, then the solution was stirred at reflux under nitrogen for 5 hours. After distilling off the solvent under reduced pressure, ethyl acetate (500 mL) was added and washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 57.5 g, yield: 96%).

<Fourth Stage: Protection>
4-Nitrophenol (60.0 g, 431.3 mmol) and acetone (1500 mL) were added to a 3000 mL three-necked flask equipped with a reflux tube, thermometer and nitrogen inlet tube. Potassium carbonate (70.4 g, 1035.2 mmol) and 4-methoxybenzyl chloride (74.3 g, 474.4 mmol) were then added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After cooling the reaction solution, it was filtered and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 111.8 g, quantitative).

<Step 5: Reduction>
A 2000 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the fourth step (111.8 g, 431.2 mmol), iron (48.2 g, 862.5 mmol), ammonium chloride (46 .1 g, 862.5 mmol), ethanol (600 mL) and water (300 mL) were added and the solution was stirred at reflux under a nitrogen atmosphere for 8 hours. After cooling the reaction solution, it was filtered, and the solvent was distilled off under reduced pressure. After that, the organic layer was washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 91.0 g, yield: 92%).

<Sixth step: diazo coupling>
The compound obtained in the fifth step (44.3 g, 193.5 mmol) and 6 mol/L hydrochloric acid (110 mL) were added to a 300 mL three-necked flask equipped with a dropping funnel, thermometer and nitrogen inlet tube, and placed in an ice bath. Sodium nitrite (16.0 g, 232.3 mmol) and water (80 mL) were added dropwise, then the solution was left in an ice bath and stirred under a nitrogen atmosphere for 1 hour to give a diazonium salt solution. The compound obtained in the third step (50.0 g, 193.5 mmol), water (500 mL) and methanol (1000 mL) were added to a 3000 mL three-necked flask equipped with a separately prepared thermometer and a nitrogen inlet tube, followed by ice bathing. . After the previous diazonium salt solution was added, the solution was left in the ice bath and stirred under a nitrogen atmosphere for 1 hour. After completion of the reaction, a crude product was obtained by filtration. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 63.7 g, yield: 55%).

<Seventh step: Deprotection>
A 3000 mL three-necked flask equipped with a reflux tube, a thermometer and a nitrogen inlet was charged with the compound obtained in the sixth step (63.6 g, 127.5 mmol), dichloromethane (1300 mL) and water (200 mL). DDQ (115.8 g, 510.2 mmol) was then added and the solution was stirred for 2 hours at room temperature under a nitrogen atmosphere. After completion of the reaction, the reaction solution was filtered, added with dichloromethane (200 mL), and washed with saturated aqueous sodium hydrogencarbonate solution (1000 mL x 2 times) and water (1000 mL x 2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (14.5 g, 44% yield).

<Eighth step: Esterification>
A 500 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet was charged with the compound obtained in the seventh step (14.4 g, 55.7 mmol), THF (100 mL) and triethylamine (11.9 mL, 117.1 mmol). was added and an ice bath was performed. The chloride below (30.1 g, 117.1 mmol, prepared as described in WO2011/103321) and THF (100 mL) were added dropwise, then the solution was stirred at room temperature for 5 hours under a nitrogen atmosphere. After completion of the reaction, ethyl acetate (300 mL) was added and washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 31.2 g, yield: 80%).

<Ninth step: Hydrolysis>
A 500 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the eighth step (31.0 g, 44.4 mmol), sodium hydroxide (7.1 g, 177.5 mmol), ethanol ( 320 mL), and water (70 mL) were added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After the solvent was distilled off under reduced pressure, 6M hydrochloric acid was added until the pH became 1. After filtering the precipitated solid, it was dried to obtain the following compound (yield: 28.2 g, yield: 99%).

<Tenth step: Dehydration>
A 300 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet was charged with the compound obtained in the eighth step (28.0 g, 43.5 mmol) and acetic anhydride (120 mL). The solution was then stirred at reflux under a nitrogen atmosphere for 3 hours. After distilling off the solvent under reduced pressure, recrystallization was performed with acetic anhydride to obtain compound (4-2-2) (21.1 g, 80% yield).

[Synthesis Example 2] Synthesis of compound (4-2-3) <First step: protection>
3-Hydroxybenzyl alcohol (30.0 g, 241.7 mmol) and acetone (750 mL) were added to a 2000 mL three-necked flask equipped with a reflux tube, thermometer and nitrogen inlet tube. Potassium carbonate (39.5 g, 580.0 mmol) and 4-methoxybenzyl chloride (41.6 g, 265.8 mmol) were then added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After cooling the reaction solution, it was filtered and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 59.0 g, quantitative).

<Second step: chlorination>
A 1000 mL three-necked flask equipped with a dropping funnel, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the first step (59.0 g, 241.6 mmol), dichloromethane (300 mL), and triethylamine (40.4 mL, 290.0 mmol). ) was added and ice bathed. Methanesulfonyl chloride (22.4 mL, 290.0 mmol) was then added dropwise and the solution was stirred for 24 hours at room temperature under a nitrogen atmosphere. After completion of the reaction, dichloromethane (200 mL) was added and washed with water (500 mL×2 times). After drying the organic layer with magnesium sulfate, the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 60.9 g, 96%).

<Third step: ether synthesis>
Sodium ethoxide (18.3 g, 255.1 mmol) and ethanol (300 mL) were added to a 2000 mL three-necked flask equipped with a reflux tube, a dropping funnel, a thermometer, and a nitrogen introduction tube, and placed in an ice bath. An ethanol solution (600 mL) of the compound from the second step (60.9 g, 231.9 mmol) was added dropwise, then the solution was stirred at reflux under nitrogen for 5 hours. After distilling off the solvent under reduced pressure, ethyl acetate (500 mL) was added and washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 61.9 g, yield: 98%).

<Fourth Stage: Protection>
4-Nitrophenol (60.0 g, 431.3 mmol) and acetone (1500 mL) were added to a 3000 mL three-necked flask equipped with a reflux tube, thermometer and nitrogen inlet tube. Potassium carbonate (70.4 g, 1035.2 mmol) and 4-methoxybenzyl chloride (74.3 g, 474.4 mmol) were then added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After cooling the reaction solution, it was filtered and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 111.8 g, quantitative).

<Step 5: Reduction>
A 2000 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the fourth step (111.8 g, 431.2 mmol), iron (48.2 g, 862.5 mmol), ammonium chloride (46 .1 g, 862.5 mmol), ethanol (600 mL) and water (300 mL) were added and the solution was stirred at reflux under a nitrogen atmosphere for 8 hours. After cooling the reaction solution, it was filtered, and the solvent was distilled off under reduced pressure. After that, the organic layer was washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 91.0 g, yield: 92%).

<Sixth step: diazo coupling>
The compound obtained in the fifth step (42.1 g, 184.0 mmol) and 6 mol/L hydrochloric acid (100 mL) were added to a 300 mL three-necked flask equipped with a dropping funnel, thermometer, and nitrogen inlet tube, and placed in an ice bath. Sodium nitrite (15.2 g, 220.3 mmol) and water (75 mL) were added dropwise, then the solution was left in an ice bath and stirred under a nitrogen atmosphere for 1 hour to give a diazonium salt solution. The compound (50.0 g, 183.6 mmol) obtained in the third step, water (500 mL) and ethanol (1000 mL) were added to a 3000 mL three-necked flask equipped with a separately prepared thermometer and a nitrogen inlet tube, followed by ice bathing. . After the previous diazonium salt solution was added, the solution was left in the ice bath and stirred under a nitrogen atmosphere for 1 hour. After completion of the reaction, a crude product was obtained by filtration. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 64.4 g, yield: 57%).

<Seventh step: deprotection>
A 3000 mL three-necked flask equipped with a reflux tube, a thermometer and a nitrogen inlet was charged with the compound obtained in the sixth step (64.4 g, 125.6 mmol), dichloromethane (1300 mL) and water (200 mL). DDQ (114.1 g, 502.5 mmol) was then added and the solution was stirred for 2 hours at room temperature under a nitrogen atmosphere. After completion of the reaction, the reaction solution was filtered, added with dichloromethane (200 mL), and washed with saturated aqueous sodium hydrogencarbonate solution (1000 mL x 2 times) and water (1000 mL x 2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 14.4 g, yield: 42%).

<Eighth step: Esterification>
A 500 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet was charged with the compound obtained in the seventh step (14.4 g, 52.9 mmol), THF (100 mL) and triethylamine (11.2 mL, 111.1 mmol). was added and an ice bath was performed. The chloride below (28.5 g, 111.1 mmol, prepared as described in WO2011/103321) and THF (100 mL) were added dropwise, then the solution was stirred at room temperature for 5 hours under a nitrogen atmosphere. After completion of the reaction, ethyl acetate (300 mL) was added and washed with water (500 mL×2 times). The organic layer was dried with magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography to obtain the following compound (yield: 29.4 g, yield: 78%).

<Ninth step: Hydrolysis>
A 500 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet tube was charged with the compound obtained in the eighth step (29.4 g, 41.3 mmol), sodium hydroxide (6.6 g, 165.0 mmol), ethanol ( 300 mL), and water (50 mL) were added. The solution was then stirred at reflux under a nitrogen atmosphere for 7 hours. After the solvent was distilled off under reduced pressure, 6M hydrochloric acid was added until the pH became 1. After filtering the precipitated solid, it was dried to obtain the following compound (yield: 26.8 g, yield: 99%).

<Tenth step: Dehydration>
A 300 mL three-necked flask equipped with a reflux tube, a thermometer, and a nitrogen inlet was charged with the compound obtained in the eighth step (26.8 g, 40.8 mmol) and acetic anhydride (100 mL). The solution was then stirred at reflux under a nitrogen atmosphere for 3 hours. After distilling off the solvent under reduced pressure, recrystallization was performed with acetic anhydride to obtain compound (4-2-3) (20.5 g, 81% yield).

Preparation of varnish The varnish used in this example was prepared by the following procedure. Here, varnishes 1 to 12 are varnishes in which a photoreactive structure is introduced into a polymer using a tetracarboxylic dianhydride represented by formula (4), and blending varnishes 1 to 10 are represented by formula (4 ) A varnish prepared using a tetracarboxylic dianhydride other than the tetracarboxylic dianhydride represented by ), which is used by blending with varnishes 1 to 12. Comparative varnishes 1 and 2 are Using a tetracarboxylic dianhydride (VII-3) having no substituent at the ortho position to the azo group of the azobenzene structure or a diamine (VI-II-1) having no substituent at the ortho position to the azo group of the azobenzene structure for comparison purposes.

[Varnish Preparation Example 1] Preparation of varnish 1 Into a 100 mL three-necked flask equipped with a stirring blade and a nitrogen inlet tube, 1.7029 g of a compound (DI-5-1) having m of 4 as a diamine compound was added. , N-methyl-2-pyrrolidone (74.0 g) was added. To this solution, 4.2971 g of tetracarboxylic dianhydride (4-2-2) was added and stirred at room temperature for 24 hours. γ-Butyrolactone (10.0 g) and butyl cellosolve (10.0 g) were added to the reaction solution, and the mixture was heated and stirred at 80° C. until the polymer produced had the target weight average molecular weight. As a result, Varnish 1 having a polymer weight average molecular weight of 13,000 and a resin concentration (polymer concentration as solid content) of 6% by weight was obtained.

[Varnish Preparation Examples 2 to 10] Preparation of varnishes 2 to 10 Resin concentration Varnishes 2-10 were prepared with 6 wt. At this time, the polymer synthesis conditions were adjusted so that the weight average molecular weight was in the range of 5,000 to 20,000. Table 1 shows the weight average molecular weight of the polymer produced. In Table 1, preparation examples in which two or more compounds are listed as diamines mean that all the compounds were used together as diamines, and two or more compounds are listed as tetracarboxylic dianhydrides. In the preparation examples given, it means that all the compounds were combined and used as the tetracarboxylic dianhydride. Numerical values in square brackets represent compounding ratios (mol %). The same applies to Tables 2 and 3 as well.

[Varnish Preparation Examples 44 to 59] Preparation of blending varnishes 1 to 10 Resin Blending varnishes 1-10 with a concentration of 6% by weight were prepared. However, the polymer synthesis conditions were adjusted so that the weight average molecular weight was in the range of 45,000 to 51,000. Table 2 shows the weight average molecular weights of the polymers produced.

[Comparative Preparation Examples 1 and 2 of Varnishes] Preparation of Comparative Varnishes 1 and 2 Resins were prepared in the same manner as in Preparation Example 1, except that the compounds used as the diamine and tetracarboxylic dianhydride were changed as shown in Table 3. Comparative varnishes 1 and 2 were prepared with a concentration of 6% by weight. Table 3 shows the weight average molecular weights of the polymers produced.

Preparation of Liquid Crystal Aligning Agent Using varnishes 1 to 12, blending varnishes 1 to 10, and comparative varnishes 1 and 2 prepared in each preparation example, liquid crystal aligning agents were prepared in the following procedure.

[Example 1] Preparation of alignment agent 1 Varnish 1 (10.0 g) was weighed and put into a 50 mL eggplant flask equipped with a stirring blade and a nitrogen inlet tube, and N-methyl-2-pyrrolidone (1 .0 g), butyl cellosolve (0.5 g) and diisobutyl ketone (0.5 g) were added and stirred at room temperature for 1 hour to obtain alignment agent 1 having a resin concentration of 5% by weight.

[Examples 2 to 12] Preparation of alignment agents 2 to 12 Alignment agents 2 to 12 were prepared in the same manner as in Example 1, except that varnishes 2 to 12 were used instead of varnish 1.

[Example 13] Preparation of alignment agent 13 Varnish 1 (3.0 g) and blending varnish 1 (7.0 g) were each weighed and put into a 50 mL eggplant flask equipped with a stirring blade and a nitrogen inlet tube. , N-methyl-2-pyrrolidone (3.0 g), butyl cellosolve (1.0 g) and diisobutyl ketone (1.0 g) were added thereto, and stirred at room temperature for 1 hour to obtain alignment agent 11 having a resin concentration of 4% by weight. got

[Examples 14 to 35] Preparation of alignment agents 14 to 35 Instead of varnish 1 and blending varnish 1, the varnishes and blending varnishes shown in Table 5 were used, respectively, and the blending ratios of the varnishes and blending varnishes are shown in Table 5. Aligning agents 14 to 45 were prepared in the same manner as in Example 13, except for the changes shown.

[Comparative Examples 1 and 2] Preparation of Comparative Aligning Agents 1 and 2 Comparative aligning agents 1 and 2 were prepared in the same manner as in Example 1, except that comparative varnishes shown in Table 6 were used instead of varnish 1.

[Comparative Examples 3 and 4] Preparation of comparative alignment agents 3 and 4 In the same manner as in Example 37, except that the comparative varnishes and blending varnishes shown in Table 7 were used instead of varnish 1 and blending varnish 1, respectively. Comparative alignment agents 3 and 4 were prepared.
Tables 3 to 7 show varnishes used in the preparation of liquid crystal aligning agents in each example and each comparative example.

Evaluation [Evaluation of voltage holding ratio]
The liquid crystal aligning agents prepared in Examples 1 to 35 and Comparative Examples 1 to 4 were dropped onto a glass substrate with IPS electrodes and a glass substrate with column spacers, and the substrates were rotated at 2,000 rpm for 15 seconds by a spinner method. applied. After coating, the substrate was heated at 60° C. for 1 minute to evaporate the solvent to form a liquid crystal aligning agent film. Multilight ML-501C/B manufactured by Ushio Inc. is used for this liquid crystal aligning agent film, and linearly polarized ultraviolet light with a wavelength of 365 nm is applied from a vertical direction to the substrate through a polarizing plate at 2.0±0. A photo-alignment treatment was performed by irradiation at 1 J/cm ² . The film of the liquid crystal aligning agent subjected to the photo-alignment treatment was first subjected to heating and baking at 150° C. for 20 minutes, and then subjected to heating and baking treatment at 230° C. for 15 minutes to form a liquid crystal alignment film having a thickness of 100 nm. formed.
Next, two substrates on which these liquid crystal alignment films are formed are opposed to each other with the surfaces on which the liquid crystal alignment films are formed, and a gap for injecting a liquid crystal composition is formed between the opposed liquid crystal alignment films. It was pasted together so that it would be. At this time, the substrates were oriented so that the polarization directions of the linearly polarized light applied to the respective liquid crystal alignment films were parallel. A negative liquid crystal composition A having the following composition was injected into the gap between the bonded substrates to prepare a liquid crystal cell (liquid crystal display element) having a cell thickness of 7 μm.

<Negative liquid crystal composition A>
Physical properties: NI 75.7°C; Δε -4.1; Δn 0.101; η 14.5 mPa·s.

The voltage holding ratio (initial voltage holding ratio) was measured at 5 V and 30 Hz for each liquid crystal cell produced. Subsequently, the liquid crystal cell was placed on a lit backlight tester (manufactured by Fuji Film Co., Ltd., FujiCOLOR LED Viewer Pro HR-2; luminance: 2,700 cd/m ² ), held for 300 hours, and irradiated with light. After that, the voltage holding ratio was measured. The results are shown in Tables 8-11.

As shown in Tables 8 to 11, liquid crystal cells using alignment agents 1 to 35 containing varnishes 1 to 10 prepared using the carboxylic acid dianhydride represented by formula (4) are all A voltage retention rate of 97.5% or more was obtained both at the initial stage and after 300 hours of backlight irradiation. In particular, the liquid crystal cells using the aligning agents 11 to 30 in which the carboxylic acid dianhydride represented by the formula (4) and the blending varnish are mixed achieve a high voltage holding rate of 98.4% or more after backlight irradiation. I was able to On the other hand, a comparative varnish 1 or 2 prepared using a carboxylic acid dianhydride (V1-1) having no substituent at the ortho position to the azo group of the azobenzene structure and a diamine (V-2-1) The liquid crystal cells using the comparative alignment agents 1 to 4 contained had a voltage retention rate of less than 97.5% after backlight irradiation. It is considered that this is because the electrical properties of the liquid crystal alignment film deteriorated due to the photochemical reaction of the azobenzene structure due to the irradiation of the backlight. From this, by using a polymer in which structural units having a photoreactive structure undergo a chemical reaction (in this example, a cyclization reaction between an azo group and an ortho-position substituent) when heated, the liquid crystal alignment film reacts to light. It was confirmed that the stability was increased and that the electrical properties of the liquid crystal cell were improved by using it.

[Evaluation of transmittance]
Using the liquid crystal aligning agents prepared in Examples 1 to 12 and Comparative Examples 1 and 2, on a transparent glass substrate, a coating film of the liquid crystal aligning agent was formed under the same conditions as in the evaluation of the voltage holding ratio, and photoaligned. processed. The ultraviolet-visible transmittance spectrum of the substrate on which this film was formed was measured, and the transmittance (transmittance before heating and baking) at 365 nm, which is the absorption wavelength of azobenzene, was determined. Subsequently, a liquid crystal alignment film having a thickness of 100 nm was formed by subjecting the film subjected to the photo-alignment treatment to a heating and baking treatment at 230° C. for 30 minutes. The ultraviolet-visible transmittance spectrum of these substrates was measured to obtain the transmittance at 365 nm (transmittance after heating and baking) and the average transmittance in the range of 380 nm to 430 nm. Also, based on the following formula, the amount of change in transmittance at 365 nm before and after heat firing was calculated. These results are shown in Tables 12 and 13.
Amount of change (%) = transmittance after heat firing (%) - transmittance before heat firing (%)
Further, using the liquid crystal aligning agents prepared in Examples 13 to 35 and Comparative Examples 3 and 4, a coating film of the liquid crystal aligning agent was formed on the transparent glass substrate under the same conditions as in the evaluation of the voltage holding ratio, After performing the photo-alignment treatment, a liquid crystal alignment film having a thickness of 100 nm was formed by performing a heating and baking treatment at 230° C. for 30 minutes. The ultraviolet-visible transmittance spectrum was also measured for the substrates on which these liquid crystal alignment films were formed, and the average transmittance in the range of 380 nm to 430 nm was evaluated. The results are shown in Tables 14-15.

Liquid crystal alignment formed using alignment agents 1-12 containing varnishes 1-12 prepared using carboxylic acid dianhydride represented by formula (4), as shown in Table 12 and Table 13. It was confirmed that the film had a large change in transmittance at 365 nm and a high average transmittance. It is considered that this is because the azobenzene structure was reduced by cyclization of a part of the azobenzene structure by the heating and baking treatment. On the other hand, the liquid crystal alignment films formed using the comparative alignment agents 1 and 2 containing the comparative varnishes 1 and 2 had a small change in transmittance at 365 nm and a low average transmittance. It is considered that the reason why the change in transmittance at 365 nm is small and the average transmittance is low is that the azobenzene structure does not form an indazole ring even after the heating and baking treatment, and remains as an azobenzene structure. .
Further, as shown in Tables 14 and 15, liquid crystals formed using aligning agents 13 to 35 containing a varnish prepared using a carboxylic acid dianhydride represented by formula (4) and a blending varnish The alignment film was also able to obtain a high average transmittance after heating and baking. On the other hand, the liquid crystal alignment films formed by using the comparative varnishes 1 and 2 and the comparative alignment agents 3 and 4 containing the blending varnishes had a low average transmittance, and the liquid crystal alignment films formed by the liquid crystal alignment agents of each example. was inferior to From this, it was suggested that a similar mechanism (reduction of azo groups due to formation of indazole rings) contributes to an improvement in transmittance also in the blend type liquid crystal aligning agent.

[Measurement of AC afterimage (evaluation of liquid crystal orientation)]
Using the alignment agents 1, 2, 15, and 31 prepared in Examples 1, 2, 15, and 31, films were formed on the glass substrate with FFS electrodes and the glass substrate with column spacers under the same conditions as in the evaluation of the voltage holding rate. A liquid crystal alignment film having a thickness of 100 nm was formed. Two substrates on which these liquid crystal alignment films are formed are opposed to each other with the surfaces on which the liquid crystal alignment films are formed, and a gap for injecting a liquid crystal composition is formed between the opposed liquid crystal alignment films. I glued it together like this. At this time, the substrates were oriented so that the polarization directions of the linearly polarized light applied to the respective liquid crystal alignment films were parallel. A liquid crystal cell (liquid crystal display element) having a cell thickness of 4 μm was produced by injecting the negative type liquid crystal composition A having the above composition into the gap between the laminated substrates and sealing the injection port with a photo-curing agent. The obtained liquid crystal display device was subjected to AC afterimage measurement (evaluation of liquid crystal orientation) according to the procedure described above. The results are shown in Tables 16 and 17.

As shown in Tables 16 and 17, the liquid crystal alignment film by the liquid crystal alignment agent containing the varnish prepared using the carboxylic acid dianhydride represented by formula (4) has good liquid crystal alignment. I was able to confirm that.

By using the liquid crystal aligning agent for photo-alignment of the present invention, it is possible to provide a liquid crystal display element that maintains high voltage holding ratio and light resistance even in long-term use and has high display quality. The liquid crystal aligning agent for photo-alignment of the present invention can be suitably applied to a horizontal electric field type liquid crystal display device. In addition, the liquid crystal alignment film of the present invention can also be used for a broadband variable phase shifter in the microwave/millimeter wave band using liquid crystal. This wideband variable phase shifter can be suitably used for an antenna or the like for phase control of an electromagnetic wave signal.

Claims (13)

From a raw material containing at least one monomer selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides, and at least one monomer selected from the group consisting of diamines and dihydrazides containing a polymer that is a reaction product,
The polymer is at least one selected from the group consisting of polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide,
At least one monomer selected from the group consisting of tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides has a photoreactive structure represented by formula (1) or formula (2). A liquid crystal aligning agent for photo-alignment, which is a monomer having a structural unit containing.

[In formulas (1) and (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R ¹ and at least one of R ² is a group represented by formula (1-1) or formula (1-2);
* represents the bonding position on the benzene ring, any position that can be substituted with a hydrogen atom on one benzene ring, and any position that can be substituted with a hydrogen atom on the other benzene ring;
A hydrogen atom of the benzene ring may be substituted with a substituent. ]

[In formulas (1-1) and (1-2), R ³ and R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or represents an unsubstituted arylcarbonyl group;
* represents the bonding position to the benzene ring in formulas (1) and (2). ] wherein the monomer having the structure represented by formula (1) or (2) is at least one tetracarboxylic dianhydride represented by formula (3) or (4) below; Item 1. The liquid crystal aligning agent for photo-alignment according to item 1.

[In formulas (3) and (4), R ¹ and R ² each independently represent a hydrogen atom, a group represented by formula (1-1) or formula (1-2), and R at least one of ¹ and R ² is a group represented by the above formula (1-1) or the above formula (1-2);
R ⁵ and R ⁷ are linear alkylene groups having 1 to 20 carbon atoms, -COO-, -OCO-, -NHCO-, -CONH-, -N(CH ₃ )CO-, -CON(CH ₃ )- , or represents a single bond, and in R ⁵ and R ⁷ , one or two non-adjacent -CH ₂ - of the linear alkylene group may be replaced with -O-;
R ⁶ and R ⁸ each independently represent a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, or a heterocyclic ring;
A hydrogen atom in the benzene ring may be substituted with a substituent. ] The light according to claim 2, wherein the tetracarboxylic dianhydride is represented by any one of the following formulas (3-1) to (3-4) and (4-1) to (4-6) Liquid crystal aligning agent for alignment.

[In formulas (3-1) to (3-4) and (4-1) to (4-6), R ³ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted represents an alkanoyl group, or a substituted or unsubstituted arylcarbonyl group;
hydrogen atoms of the benzene ring may be substituted with substituents;
In Formula (3-3), Formula (3-4), Formula (4-5) and Formula (4-6), R ⁴ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or represents an unsubstituted alkanoyl group or a substituted or unsubstituted arylcarbonyl group; ] The tetracarboxylic dianhydride is the following formula (3-1-1) ~ formula (3-1-8), formula (3-2-1) ~ formula (3-2-8), formula (3- 3-1), formula (3-3-2), formula (3-4-1), formula (3-4-2), the following formulas (4-1-1) to formulas (4-1-8) , Formula (4-2-1) ~ Formula (4-2-7), Formula (4-3-1) ~ Formula (4-3-3), Formula (4-4-1) ~ Formula (4- 4-3), represented by any of formula (4-5-1), formula (4-5-2), formula (4-6-1) and formula (4-6-2), claim 3. The liquid crystal aligning agent for photo-alignment according to 3.

[In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, ⁱ Pr represents an isopropyl group, Bu represents a butyl group, ^{and t} Bu represents a t-butyl group. ] When the film formed from the liquid crystal aligning agent for photo-alignment is heated and baked at 230 ° C. for 30 minutes, the transmittance at 365 nm of the film is increased by 25% or more from the transmittance at 365 nm of the film before baking. The liquid crystal aligning agent for photo-alignment according to any one of claims 1 to 4. The liquid crystal aligning agent for photo-alignment according to any one of claims 1 to 5, which is used for manufacturing a horizontal electrolysis type liquid crystal display device. A liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment according to any one of claims 1 to 6. A liquid crystal display device comprising the liquid crystal alignment film according to claim 7 . A horizontal electrolytic liquid crystal display device comprising the liquid crystal alignment film according to claim 7 . A method for forming a liquid crystal alignment film formed by a liquid crystal alignment agent for photoalignment containing a polymer having a photoreactive structure,
The film of the liquid crystal aligning agent formed by applying the liquid crystal aligning agent for photoalignment according to any one of claims 1 to 6 on a substrate is irradiated with polarized light to impart anisotropy, and then heated and baked. and cyclizing the photoreactive structure during the heating and baking to make the structure non-photoreactive. 11. The method of forming a liquid crystal alignment film according to claim 10, wherein the heating and baking are performed in two or more stages with different heating temperatures. A method for manufacturing a liquid crystal display element, comprising forming a liquid crystal alignment film by the method for forming a liquid crystal alignment film according to claim 10 or 11. A method for manufacturing a lateral electric field type liquid crystal display device, comprising forming a liquid crystal alignment film by the method for forming a liquid crystal alignment film according to claim 10 or 11.