JP6919574B2 - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element using it - Google Patents

Description

The present invention relates to a liquid crystal alignment agent used in the manufacture of a liquid crystal display element, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element using the liquid crystal alignment film.

Liquid crystal display elements used in liquid crystal televisions, navigators, smartphones, and the like are usually provided with a liquid crystal alignment film for controlling the arrangement state of liquid crystals. The liquid crystal alignment film has a function of controlling the orientation of liquid crystal molecules in a certain direction in a liquid crystal display element, a retardation plate using a polymerizable liquid crystal, or the like. For example, a liquid crystal display element has a structure in which liquid crystal molecules forming a liquid crystal layer are sandwiched between liquid crystal alignment films formed on the respective surfaces of a pair of substrates. There, the liquid crystal molecules are oriented in a certain direction with a pretilt angle by the liquid crystal alignment film, and respond by applying a voltage to an electrode provided between the substrate and the liquid crystal alignment film. As a result, the liquid crystal display element displays a desired image by utilizing the change in orientation due to the response of the liquid crystal molecules.

The liquid crystal alignment film has mainly been a polyimide-based liquid crystal alignment film obtained by applying a liquid crystal alignment agent containing a polyimide precursor such as polyamic acid (polyamic acid) or a solution of soluble polyimide as a main component to a glass substrate or the like and firing the liquid crystal alignment film. It is used.
With the sophistication of liquid crystal display elements, in the liquid crystal alignment film, in addition to the development of excellent liquid crystal orientation and stable pretilt angle, high voltage retention, low residual charge when DC voltage is applied, and / Alternatively, characteristics such as quick relaxation of the residual charge accumulated by the DC voltage are required, but in recent years, a material having a high voltage holding ratio is particularly required for power saving of the liquid crystal display element.

Various proposals have been made to meet the above requirements. For example, a liquid crystal alignment agent containing a tertiary amine having a specific structure in addition to a polyamic acid or an imide group-containing polyamic acid (see, for example, Patent Document 1), or a liquid crystal alignment agent containing an additive containing an isocyanate structure (for example, for example). (See Patent Document 2) and the like have been proposed.

Japanese Patent Application Laid-Open No. 9-316200 WO2014 / 178406

With the recent improvement in the performance of liquid crystal display elements, liquid crystal display elements are used in large-screen, high-definition liquid crystal televisions and in-vehicle applications such as car navigation systems and meter panels. In such applications, a backlight with a large calorific value may be used in order to obtain high brightness. Therefore, the liquid crystal alignment film is required to have high stability with respect to the light from the backlight. In particular, when the voltage retention rate, which is one of the electrical characteristics of the liquid crystal display element, is lowered by the light irradiation from the backlight, the burn-in defect (also called line burn-in), which is one of the display defects of the liquid crystal display element, is caused. Is likely to occur, and a highly reliable liquid crystal display element cannot be obtained.

Therefore, in addition to having good initial characteristics, the liquid crystal alignment film is required to have a voltage retention rate that is unlikely to decrease even after being exposed to light for a long time, for example. Further, there is an increasing demand for low-frequency driving in order to reduce power consumption, and an alignment film having a high voltage holding capacity is further required.
When a liquid crystal alignment agent obtained by adding various cross-linking agents to polyamic acid is used, a liquid crystal display element having excellent voltage holding characteristics can be obtained, but the liquid crystal orientation may be impaired. In addition, the effect of the cross-linking agent may not be sufficiently exhibited depending on the combination with the polymer species contained in the liquid crystal alignment agent, and the voltage retention rate may be insufficient.

As a result of diligent studies to solve the above problems, the present inventors have completed the present invention. That is, the gist of the present invention is as shown below.

（Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、炭素数１〜４のアルキル基又は下記式（１）で表される基であり、その少なくとも一方は、熱により水素原子に置き換わる保護基である熱脱離性基である。Ｒ_３、Ｒ_４、及びＲ_５は、それぞれ独立して、水素原子又は置換基を有してもよい炭素数１〜２０の１価の炭化水素基であり、Ｄは熱により水素原子に置き換わる保護基である熱脱離性基である。）
（Ｂ）成分：下記式（２）で表される構造単位を有するポリイミド前駆体及び該ポリイミド前駆体のイミド化重合体からなる群から選ばれる少なくとも１種類の重合体。

Ｘ_１は、下記式（Ｘ−１）で表される４価の有機基であり、Ｙ_１は２価の有機基であり、Ｒ_１は、水素原子、又は炭素数１〜５のアルキル基であり、Ａ_１〜Ａ_２はそれぞれ独立して水素原子、又は置換基を有してもよい炭素数１〜１０のアルキル基、炭素数２〜１０のアルケニル基、又は炭素数２〜１０のアルキニル基である。

（Ｃ）成分：架橋性官能基を２つ以上含有する化合物。A liquid crystal alignment agent containing the following component (A), component (B), component (C) and an organic solvent.
Component (A): A tetracarboxylic acid derivative component, a diamine compound having a structure of the following formula [A-1], a diamine compound having a structure of the following formula [A-2], and a structure of the following formula [A-3]. A polyimide precursor obtained by using a diamine component containing at least one diamine compound selected from the diamine compounds having the above, and at least one polymer selected from the polyimide.

(R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a group represented by the following formula (1), and at least one of them is a protecting group that replaces a hydrogen atom by heat. R ₃ , R ₄ , and R ₅ are monovalent hydrocarbon groups having 1 to 20 carbon atoms, which may independently have a hydrogen atom or a substituent. Yes, D is a thermally desorbing group, which is a protecting group that replaces hydrogen atoms by heat.)
Component (B): At least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (2) and an imidized polymer of the polyimide precursor.

X ₁ is a tetravalent organic group represented by the following formula (X-1), Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. A _{1 to} A ₂ each have an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, which may independently have a hydrogen atom or a substituent. It is an alkynyl group.

Component (C): A compound containing two or more crosslinkable functional groups.

According to the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal alignment film that maintains the voltage retention rate even after being exposed to light irradiation, in particular, without impairing the liquid crystal alignment for a long period of time. Thereby, the liquid crystal display element having the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can provide an excellent display used for a liquid crystal television, a smartphone, a car navigation system, and the like.

<Ingredient (A)>
The component (A) contained in the liquid crystal alignment agent of the present invention includes a tetracarboxylic acid derivative component, a diamine compound having a structure of the following formula [A-1], and a diamine having a structure of the following formula [A-2]. A polyimide precursor obtained by using a diamine component containing at least one diamine compound selected from diamine compounds having the structure of the following formula [A-3] and at least one polymer selected from polyimide (hereinafter, specified. It is also referred to as a polymer (A)).

式（１）中、Ａは、単結合、又は炭素数１〜４の炭化水素基、好ましくはアルキレン基からなる２価の基である。脱離する温度の点から、ｔｅｒｔ−ブトキシカルボニル基が好ましい。Wherein ^{[A-1], R 1} , R 2, and A is are as defined above. Among them, R ¹ and R ² are thermal desorption groups which are protective groups that replace hydrogen atoms by heat at least one or both of them. From the viewpoint of the strength of the alignment film during rubbing, it ^{is particularly preferable that only one} of R 1 and R ² is a heat-removable group.
The thermally desorbable group is preferably a protective group that does not desorb at room temperature, preferably 80 ° C. or higher, and more preferably 100 ° C. or higher, from the viewpoint of storage stability of the liquid crystal aligning agent. be. As the thermoremovable group, a group represented by the following formula (1) or a 9-fluorenylmethoxycarbonyl group is preferable.

In the formula (1), A is a divalent group consisting of a single bond or a hydrocarbon group having 1 to 4 carbon atoms, preferably an alkylene group. The tert-butoxycarbonyl group is preferred in terms of the temperature at which it desorbs.

A preferred example of a diamine having a structure represented by the above formula [A-1] in the molecule is a diamine represented by the following formula [A-1-1].

In the above formula [A-1-1], R ¹ and R ² are the same as those in the formula [A-1], including their preferred ones. The two ns are independently integers of 0 to 3, preferably 0 or 1, and more preferably 1 from the viewpoint of easy availability of raw materials.
Further, in the formula [A-1-1], the amino group (-NH ₂ ) in each benzene ring may be in any of ortho, meta, or para positions with respect to the bond position of the alkylene group, but it is synthesized. The meta-position or the para-position is preferable, and the para-position is more preferable, from the viewpoint of ease of use and polymerization reactivity.

Preferred examples of the diamine represented by the formula [A-1-1] include the following compounds.

In the formula [A-2], R ₃ and R ₄ are independently hydrogen atoms or monovalent hydrocarbon groups having 1 to 20 carbon atoms which may have a substituent. In particular, a bulky substituent may lower the liquid crystal orientation, so a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group is preferable, and a hydrogen atom or a methyl group is particularly preferable.

D is a thermally desorbing group which is a protecting group that replaces a hydrogen atom by heat, and is as defined by the above formula [A-2] including its preferred embodiment. In particular, the tert-butoxycarbonyl group is preferred.

As the diamine having the structure represented by the above formula [A-2], the diamine represented by the following formula [A-2-1] is preferable.

Among them, the case represented by the following formula [A-2-2] is particularly preferable because the liquid crystal orientation of the obtained liquid crystal alignment film is high.

A ¹ and A ⁵ are independently single bonds or alkylene groups having 1 to 5 carbon atoms. A single bond or a methylene group is preferable from the viewpoint of reactivity with a functional group in the sealant. A ² and A ⁴ are alkylene groups having 1 to 5 carbon atoms, preferably a methylene group or an ethylene group.
A ³ is an alkylene group having 1 to 6 carbon atoms or a cycloalkylene group. A methylene group or an ethylene group is preferable from the viewpoint of reactivity with a functional group in the sealant.

B ¹ and B ² are independently single-bonded, -O-, -NH-, -NMe-, -C (= O)-, -C (= O) O-, -C (= O). NH-, -C (= O) NMe-, -OC (= O)-, -NHC (= O)-, or -N (Me) C (= O)-. From the viewpoint of liquid crystal orientation of the obtained liquid crystal alignment film, single bond or —O— is preferable.
D ₁ is a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group. The tert-butoxycarbonyl group is preferred from the standpoint of deprotecting temperature. a is 0 or 1.

Specific examples of the diamine represented by the formula (A-2-2) include the following formulas (2-1) to (2-21).

In formulas (2-1) to (2-21), Me represents a methyl group and D ₂ represents a tert-butoxycarbonyl group.
Of these, formulas (2-1) to (2-4) are more preferable, and formula (2-1) is particularly preferable.
As the diamine having the structure represented by the above formula [A-3], the diamine represented by the following formula [A-3-1] or the following formula [A-3-2] is preferable.

Among them, the cases represented by the following formulas [A-3-3] and the following formulas [A-3-4] are particularly preferable because the liquid crystal orientation of the obtained liquid crystal alignment film is high.

In the formulas [A-3-1] and [A-3-3], A ¹ , A ⁵ , B ¹ , and B ² are described in the formula [A-2-1], including preferable examples. , A ¹ , A ⁵ , B ¹ , and B ² with the same definition. R ₅ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may independently have a hydrogen atom or a substituent. From the viewpoint of liquid crystal alignment property, the R _5, a hydrogen atom, preferably a methyl group, or ethyl group, more preferably a hydrogen atom.
A ⁶ is a single bond or an alkylene group having 1 to 6 carbon atoms. From the viewpoint of liquid crystal orientation, a single bond, a methylene group, an ethylene group, or a propylene group is preferable, and a single bond or a methylene group is more preferable.

D ₁ is a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group, and a tert-butoxycarbonyl group is preferable from the viewpoint of the temperature for deprotection. a is 0 or 1.
In the formula [A-3-2] and the formula ^{[A-3-4], A 6} , R 5, and _{D 1} is, according to the preferred examples are also the formula ^{[A-2-1], A 6} , R 5 , And D ₁ have the same definition.
Specific examples include the following formulas (3-1) to (3-5).

In formulas (3-1) to (3-5), D ₂ represents the tert-butoxycarbonyl group.
Of these, formulas (3-1) to (3-4) are more preferable, and formula (3-1) is particularly preferable.
Select from a diamine having a structure represented by the above formula [A-1], a diamine having a structure represented by the above formula [A-2], and a diamine having a structure represented by the above formula [A-3]. The content of at least one diamine is the total diamine component used in the production of the polyimide precursor used for the component (A) contained in the liquid crystal alignment agent of the present invention and the imidized polymer of the polyimide precursor. On the other hand, it is preferably 5 to 80 mol%, more preferably 10 to 50 mol%.

The diamine component used for the component (A) contained in the liquid crystal alignment agent of the present invention is a diamine having a structure represented by the above formulas [A-1], [A-2] and [A-3]. Other diamines can also be used with at least one diamine selected.

Examples of the other diamines include 2,4-dimethyl-m-phenylenediamine, 2,6-diaminotoluene, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminobiphenyl, and 3,3'-dimethyl-. 4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dicarboxy-4,4' -Diaminobiphenyl, 3,3'-difluoro-4,4'-biphenyl, 3,3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl , 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylmethane, 2 , 3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, 4,4 '-Sulfonyldianiline, 3,3'-sulfonyldianiline, bis (4-aminophenyl) silane, bis (3-aminophenyl) silane, dimethyl-bis (4-aminophenyl) silane, dimethyl-bis (3-) Aminophenyl) Silane, 4,4'-thiodianiline, 3,3'-thiodianiline, 4,4'-diaminodiphenylamine, 3,3'-diaminodiphenylamine, 3,4'-diaminodiphenylamine, 2,2'-diaminodiphenylamine , 2,3'-diaminodiphenylamine, N-methyl (4,4'-diaminodiphenyl) amine, N-methyl (3,3'-diaminodiphenyl) amine, N-methyl (3,4'-diaminodiphenyl) amine , N-methyl (2,2'-diaminodiphenyl) amine, N-methyl (2,3'-diaminodiphenyl) amine, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'- Diaminobenzophenone, 1,4-diaminonaphthalene, 2,2'-diaminobenzophenone, 2,3'-diaminobenzophenone, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8 − Diaminonaphthalene, 2,5- Diaminonaphthalene, 2,6 diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 1,2-bis (4-aminophenyl) ethane, 1,2-bis (3-aminophenyl) ethane, 1 , 3-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenyl) propane, 1,4-bis (4 aminophenyl) butane, 1,4-bis (3-aminophenyl) butane, Bis (3,5-diethyl-4-aminophenyl) methane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-amino) Phenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenyloxy) benzene, 4,4'-[1 , 4-Phenylenebis (methylene)] dianiline, 4,4'-[1,3-phenylenebis (methylene)] dianiline, 3,4'-[1,4-phenylenebis (methylene)] dianiline, 3,4 '-[1,3-Phenylenebis (methylene)] dianiline, 3,3'-[1,4-phenylenebis (methylene)] dianiline, 3,3'-[1,3-phenylenebis (methylene)] dianiline , 1,4-Phenylenebis [(4-aminophenyl) methanone], 1,4-phenylenebis [(3-aminophenyl) methanone], 1,3-phenylenebis [(4-aminophenyl) methanone], 1 , 3-Phenylenebis [(3-aminophenyl) methanone], 1,4-Phenylenebis (4-aminobenzoate), 1,4-Phenylenebis (3-aminobenzoate), 1,3-Phenylenebis (4-) Aminobenzoate), 1,3-phenylenebis (3-aminobenzoate), bis (4-aminophenyl) terephthalate, bis (3-aminophenyl) terephthalate, bis (4-aminophenyl) isophthalate, bis (3-amino) Phenyl) isophthalate, N, N'-(1,4-phenylene) bis (4-aminobenzamide), N, N'-(1,3-phenylene) bis (4-aminobenzamide), N, N'- (1,4-phenylene) bis (3-aminobenzamide), N, N'-(1,3-phenylene) bis (3-aminobenzamide), N, N'-bis (4-aminophenyl) terephthalamide, N, N'-bis (3-aminophenyl) terephthalamide , N, N'-bis (4-aminophenyl) isophthalamide, N, N'-bis (3-aminophenyl) isophthalamide, 9,10-bis (4-aminophenyl) anthracene, 4,4'-bis (4-Aminophenoxy) diphenylsulfone, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2 , 2'-bis (4-aminophenyl) hexafluoropropane, 2,2'-bis (3-aminophenyl) hexafluoropropane, 2,2'-bis (3-amino-4-methylphenyl) hexafluoropropane , 2,2'-bis (4-aminophenyl) propane, 2,2'-bis (3-aminophenyl) propane, 2,2'-bis (3-amino-4-methylphenyl) propane, 1,3 -Bis (4-aminophenoxy) propane, 1,3-bis (3-aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,4-bis (3-aminophenoxy) butane, 1, , 5-bis (4-aminophenoxy) pentane, 1,5-bis (3-aminophenoxy) pentane, 1,6-bis (4-aminophenoxy) hexane, 1,6-bis (3-aminophenoxy) Hexane, 1,7-bis (4-aminophenoxy) heptane, 1,7- (3-aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,8-bis (3-amino) Phenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1,9-bis (3-aminophenoxy) nonane, 1,10- (4-aminophenoxy) decane, 1,10- (3-amino) Phenoxy) decane, 1,11- (4-aminophenoxy) undecane, 1,11- (3-aminophenoxy) undecane, 1,12- (4-aminophenoxy) dodecane, 1,12- (3-aminophenoxy) Dodecane, bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diamino Hexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane or 1,12-diaminododecane, and their amino groups. Is a secondary amino group Diamine can be mentioned.

The other diamine compound used for the component (A) contained in the liquid crystal alignment agent of the present invention has the solubility of the component (A) in a solvent, the coatability of the liquid crystal alignment agent, and the liquid crystal orientation when used as a liquid crystal alignment film. , One type or two or more types can be used depending on the characteristics such as voltage retention and accumulated charge.

<Tetracarboxylic acid derivative component>
The tetracarboxylic acid derivative component for producing the component (A) contained in the liquid crystal alignment agent of the present invention includes not only tetracarboxylic dianhydride but also tetracarboxylic acid and tetracarboxylic dianhydride which are the tetracarboxylic acid derivatives thereof. Acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid dialkyl ester dihalide can also be used. Among them, it is preferable to use at least one selected from the tetracarboxylic dianhydride represented by the following formula [4] and the tetracarboxylic acid dialkyl ester which is a derivative thereof. The tetracarboxylic dianhydride represented by the following formula [4] and its derivatives are also collectively referred to as a specific tetracarboxylic acid component.

In formula (4), Z represents at least one structure selected from the group consisting of the following formulas [4a] to [4q].

Z ^{1 to} Z ⁴ independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring. Z ⁵ and Z ⁶ each independently represent a hydrogen atom or a methyl group.
In particular, Z has formulas [4a], formulas [4c] to [4g], and formulas [4k] to [4m] from the viewpoints of ease of synthesis and easiness of polymerization reactivity when producing a polymer. ] Or the formula [4p] is preferable. More preferred are formulas [4a], formulas [4e] to formulas [4g], formulas [4l], formulas [4m] or formulas [4p]. Particularly preferred are formula [4a], formula [4e], formula [4f], formula [4l], formula [4m] or formula [4p].

More specifically, the following formula [4a-1] or formula [4a-2] is preferable.

The specific tetracarboxylic acid component in the component (A) is preferably 50 to 100 mol%, preferably 70 to 100 mol%, particularly 80 to 100 mol%, out of 100 mol% of all the tetracarboxylic acid derivative components. preferable.
The specific tetracarboxylic acid component depends on the characteristics such as the solubility of the specific polymer (A) in the solvent, the coatability of the liquid crystal alignment agent, the orientation of the liquid crystal when it is used as a liquid crystal alignment film, the voltage retention rate, and the accumulated charge. It is also possible to use one type or two or more types.

As the polyimide-based polymer of the specific polymer (A), other tetracarboxylic acid components other than the specific tetracarboxylic acid component can also be used.
Examples of other tetracarboxylic acid components include the following tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl ester dihalide.

Other tetracarboxylic acid components include 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3, 3', 4,4'-biphenyltetracarboxylic acid, 2,3,3',4-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3', 4,4'-benzophenone Tetracarboxylic acid, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) propane, 1,1,1, 3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane, bis (3,4-dicarboxyphenyl) diphenylsilane , 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis (3,4-dicarboxyphenyl) pyridine, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid, 3,4 Examples thereof include 9,10-perylenetetracarboxylic acid and 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic acid.

The other tetracarboxylic acid components have characteristics such as solubility of the specific polymer (A) in a solvent, coatability of a liquid crystal alignment agent, liquid crystal orientation when used as a liquid crystal alignment film, voltage retention, and accumulated charge. Depending on the situation, one type or a mixture of two or more types may be used.

<Ingredient (B)>
The component (B) contained in the liquid crystal alignment agent of the present invention is at least one selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (2) and an imidized polymer of the polyimide precursor. (Hereinafter, also referred to as a specific polymer (B)).

In the formula (2), X ₁ , Y _1, R _1, A _{1 to} A _2, are as defined above. Among _them, R ₁ is preferably a hydrogen atom or a methyl group, a hydrogen atom is particularly preferred. A _{1 to} A ₂ are preferably hydrogen atoms or methyl groups.

Specific examples of the above alkyl group in R ₁ include methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group and n-pentyl group. And so on. From the viewpoint of ease of imidization by heating, R ₁ is preferably a hydrogen atom or a methyl group.
The preferable content ratio of the structural unit of the above (2) is 5 to 90 mol% in the same polymer, more preferably 10 to 90 mol%, and further preferably 10 to 80 mol%.

本発明の（Ｂ）成分は、式（２）で表される構造単位と式（３）の構造単位とを有する重合体であってよく、式（２）で表される構造単位を有する重合体と、式（３）の構造単位とを有する重合体との混合物でもよいが、前者が好ましい。（Ｂ）成分の重合体に含まれる式（３）の構造単位の含有割合は、重合体中、５〜９０モル％であり、好ましく、１０〜９０モル％が好ましく、２０〜９０モル％がより好ましい。Further, the polymer of the component (B) may have a structural unit of the following formula (3) in addition to the structural unit represented by the above formula (2).

The component (B) of the present invention may be a polymer having a structural unit represented by the formula (2) and a structural unit represented by the formula (3), and a weight having the structural unit represented by the formula (2). A mixture of the coalescence and the polymer having the structural unit of the formula (3) may be used, but the former is preferable. The content ratio of the structural unit of the formula (3) contained in the polymer of the component (B) is 5 to 90 mol%, preferably 10 to 90 mol%, and 20 to 90 mol% in the polymer. More preferred.

In the above formula (3), X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. Two or more types of X _{2 may be mixed.} Specific examples of X ₂ include the following formulas (X-2) to (X-44).

In the above formula (X-2), R _{8 to} R ₁₁ are independently hydrogen atom, halogen atom, alkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkynyl group or phenyl group. Is. When R _{8 to} R ₁₁ have a bulky structure, a hydrogen atom, a methyl group or an ethyl group is preferable, and a hydrogen atom or a methyl group is particularly preferable, because the liquid crystal orientation may be lowered.

In the formula (3), X ₂ preferably contains a structure selected from (X-2) to (X-14) from the viewpoint of the availability of the monomer.
Since the reliability of the obtained liquid crystal alignment film can be further enhanced, it is preferable that X ₂ has a structure consisting only of aliphatic groups such as (X-2) to (X-7) and (X-10). X-2) is more preferable. Furthermore, to show the good liquid crystal orientation, _{X 2} is, more preferably the following formula (X2-1) or (X2-2).

In the above formulas (2) and (3), A ₁ and A ₂ each have an alkyl group having 1 to 10 carbon atoms and a substituent which may independently have a hydrogen atom or a substituent. It is an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms which may have a substituent.
Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group, a bicyclohexyl group and the like. Examples of the alkenyl group include one in which one or more CH-CH structures existing in the above alkyl group are replaced with a C = C structure, and more specifically, a vinyl group, an allyl group, and a 1-propenyl group. , Isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group and the like. Examples of the alkynyl group include one in which one or more CH _2- CH ₂ structures existing in the above alkyl group are replaced with a C≡C structure, and more specifically, an ethynyl group, a 1-propynyl group, and 2 -Propynyl group and the like.

The above alkyl group, alkenyl group, and alkynyl group may have a substituent, and further, a ring structure may be formed by the substituent. In addition, forming a ring structure by a substituent means that the substituents or the substituents are bonded to a part of the mother skeleton to form a ring structure.
Examples of this substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organooxy group, an organothio group, an organosilyl group, an acyl group, an ester group, a thioester group, a phosphoric acid ester group, an amide group and an alkyl. Examples include groups, alkenyl groups and alkynyl groups.

Examples of the halogen group as a substituent include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
Examples of the aryl group as a substituent include a phenyl group. The aryl group may be further substituted with the other substituents described above.
As the organooxy group which is a substituent, a structure represented by OR can be shown. The R may be the same or different, and the above-mentioned alkyl group, alkenyl group, alkynyl group, aryl group and the like can be exemplified. These Rs may be further substituted with the above-mentioned substituents. Specific examples of the organooxy group include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group and the like.

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

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

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

As the thioester group which is a substituent, a structure represented by -C (S) OR or -OC (S) -R can be shown. Examples of this R include the above-mentioned alkyl group, alkenyl group, alkynyl group, aryl group and the like. These Rs may be further substituted with the above-mentioned substituents.
As the phosphate ester group which is a substituent, a _{structure represented by −OP (O) − (OR) 2} can be shown. The R may be the same or different, and the above-mentioned alkyl group, alkenyl group, alkynyl group, aryl group and the like can be exemplified. These Rs may be further substituted with the above-mentioned substituents.

As the amide group which is a substituent, -C (O) NH ₂ , or -C (O) NHR, -NHC (O) R, -C (O) N (R) ₂ , -NRC (O) R The structure represented by can be shown. The R may be the same or different, and the above-mentioned alkyl group, alkenyl group, alkynyl group, aryl group and the like can be exemplified. These Rs may be further substituted with the above-mentioned substituents.
Examples of the aryl group as the substituent include the same aryl groups as those described above. The aryl group may be further substituted with the other substituents described above.
Examples of the alkyl group as the substituent include the same alkyl groups as those described above. The alkyl group may be further substituted with the other substituents described above.

Examples of the alkenyl group as the substituent include the same alkenyl groups as those described above. The alkenyl group may be further substituted with the other substituents described above.
Examples of the alkynyl group as the substituent include the same alkynyl groups as described above. The alkynyl group may be further substituted with the other substituents described above.
In general, when a bulky structure is introduced, the reactivity of the amino group and the orientation of the liquid crystal may be lowered. _{Therefore, as A 1} and A ₂ , the number of carbon atoms which may have a hydrogen atom or a substituent is 1. Alkyl groups of ~ 5 are more preferred, and hydrogen atoms, methyl or ethyl groups are particularly preferred.

In the formulas (2) and (3), Y ₁ is a diamine-derived divalent organic group, and examples thereof include the following Y-1 to Y-118.

In the formula (Y-109), m and n are independently 1 to 11, m + n is 2 to 12, and in the formula (Y-114), h is 1 to 3 and the formula (Y-). 111), (Y-117), j is 0 to 3.
As Y ₁ , at least one selected from the structures represented by the following formulas (5) and (6) is more preferable from the viewpoint of the liquid crystal orientation and the pretilt angle of the obtained liquid crystal alignment film.

In formula (5), R ₁₂ is a single bond or a divalent organic group _{having 1 to 30 carbon atoms, R 13} is a hydrogen atom, a halogen atom or a monovalent organic group having 1 to 30 carbon atoms, and a is. When a is an integer of 1 to 4 and a is 2 or more, R ₁₂ and R ₁₃ may be the same or different from each other, and R ₁₄ in the equation (6) is a single bond, −O−, −S−. , _{-NR 15} -, an amide bond, an ester bond, a urea bond, or a divalent organic group having a carbon number of 1 to _{40, R 15} is a hydrogen atom, or a methyl group.

Specific examples of the formula (5) and the formula (6) include the following structures.
A structure with high linearity can enhance the orientation of the liquid crystal when it is used as a liquid crystal alignment film. Therefore, as Y ₁ , Y-7, Y-21, Y-22, Y-23, Y-25, Y-43, Y-44, Y-45, Y-46, Y-48, Y-63, Y-71, Y-72, Y-73, Y-74, Y-75, Y-98, Y- 99, Y-100 and Y-118 are more preferable. The proportion of the structure that can increase the liquid crystal alignment property, is preferably at least 20 mole% of the total Y _1, more preferably 60 mol% or more, still more preferably 80 mol% or more.

_{If it is desired to increase the pretilt angle of the liquid crystal when the liquid crystal alignment film is used, it is preferable that Y 1} has a long-chain alkyl group, an aromatic ring, an aliphatic ring, a steroid skeleton, or a structure combining these in the side chain. .. Such Y ₁ includes Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, Y-. 86, Y-87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96, Y-97 are preferable. The proportion of the structure when it is desired to increase the pretilt angle is preferably 1 to 30 mol% of the total _{Y 1,} and more preferably 1 to 20 mol%.
The polyimide precursor used in the present invention is obtained from a reaction between a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acids and polyamic acid esters.

<Ingredient (C)>
The component (C) contained in the liquid crystal alignment agent of the present invention is a compound containing two or more crosslinkable functional groups. Examples of the crosslinkable functional group include, but are not limited to, a hydroxyl group, a hydroxyalkylamide group, a (meth) acrylate group, a blocked isocyanate group, an oxetane group, and an epoxy group.
Among them, a hydroxyl group, a blocked isocyanate group, or an epoxy group is preferable, and a hydroxyl group or an epoxy group is more preferable, from the viewpoint of availability and the effect of improving the voltage retention rate. The component (C) may have two or more of the same crosslinkable functional groups in its structure, or may have two or more different types of crosslinkable functional groups.
Examples of the compound containing two or more hydroxyl groups include a compound represented by the following formula (7).

Ｒ_８〜Ｒ_１１は、それぞれ独立に、水素原子、炭化水素基、又は、ヒドロキシ基で置換された炭化水素基のいずれかを表す。Ｘ_３は、脂肪族炭化水素基であることが、上記と同じく液晶配向性及び溶解性の観点から好ましく、炭素数１〜１０であることがより好ましい。ｎは２〜６の整数を表すが、溶解性の観点からｎは２〜４が好ましい。X ₃ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an n-valent organic group containing an aromatic hydrocarbon group, n is an integer of 2 to _6, and R _{6 and R 7} are R 6 and R 7, respectively. Independently, it is an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkynyl group having 2 to 4 carbon atoms, which may have a hydrogen atom or a substituent, and is R ₆ and R _7. At least one of them is represented by the following formula (6).

R _{8 to} R ₁₁ each independently represent either a hydrogen atom, a hydrocarbon group, or a hydrocarbon group substituted with a hydroxy group. X ₃ is preferably an aliphatic hydrocarbon group, as described above, from the viewpoint of liquid crystal orientation and solubility, and more preferably 1 to 10 carbon atoms. Although n represents an integer of 2 to 6, n is preferably 2 to 4 from the viewpoint of solubility.

Specifically, the following compounds are exemplified.

４つのＺは、それぞれ独立して、炭素数１〜３のアルキル基、水酸基又は下記式（１０）で表される有機基であり、Ｚの少なくとも１つは、下記式（１０）で表される有機基である。Examples of the compound containing two or more blocked isocyanate groups include a compound represented by the following formula (9).

Each of the four Zs is independently an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or an organic group represented by the following formula (10), and at least one of Z is represented by the following formula (10). It is an organic group.

具体的には、以下のような化合物が例示される。

Specifically, the following compounds are exemplified.

Examples of the compound containing two or more blocked isocyanate groups other than the above formula (11) include the following compounds.

Specific examples of the compound containing two or more epoxy groups include the following compounds.

Specific examples of the compound containing two or more (meth) acrylate groups include the following compounds.

In addition, the following compounds are also exemplified.

<Content ratio of each component>
Regarding the content ratios of the component (A), the component (B), and the component (C) contained in the liquid crystal alignment agent of the present invention, the content ratio of the component (A) is preferably 20 to 80% by mass during the liquid crystal alignment. 20 to 60% by mass is more preferable, and 30 to 50% by mass is particularly preferable.
The content ratio of the component (B) is preferably 20 to 80% by mass, more preferably 40 to 80% by mass, and particularly preferably 50 to 70% by mass with respect to the component (A).
The content ratio of the component (C) is preferably 1 to 30% by weight, more preferably 3 to 20% by weight, particularly preferably 3 to 15% by weight, based on the total of the components (A) and (B). preferable.

<Polyimide precursor-Production of polyamic acid>
The polyamic acid, which is a polyimide precursor used for the components (A) and (B), is produced by the following method. Specifically, the tetracarboxylic acid component such as tetracarboxylic dianhydride and the diamine component are mixed in the presence of an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C. for 30 minutes to 24 hours. It can be produced preferably by reacting for 1 to 12 hours.

The reaction between the diamine component and the tetracarboxylic acid component is usually carried out in an organic solvent. The organic solvent used at that time is not particularly limited as long as it dissolves the produced polyimide precursor. Specific examples of the organic solvent used in the reaction below include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide and dimethyl sulfoxide. Alternatively, 1,3-dimethyl-imidazolidinone can be mentioned.

When the polyimide precursor has high solubility, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or the following formulas [D-1] to [D-3]. Organic solvent can be used.

In the formulas [D-1] to D-3], D ¹ represents an alkyl group having 1 to 3 carbon atoms ^{, D 2 represents an alkyl group having 1 to 3} carbon atoms, and D 3 represents an alkyl group having 1 to 4 carbon atoms. Indicates an alkyl group.
These solvents may be used alone or in combination. Further, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the solvent and used as long as the produced polyimide precursor does not precipitate. Further, since the water content in the solvent inhibits the polymerization reaction and further causes the produced polyimide precursor to be hydrolyzed, it is preferable to use a dehydrated and dried solvent.

The concentration of the polyamic acid polymer in the reaction system is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, because precipitation of the polymer is unlikely to occur and a high molecular weight polymer is easily obtained.
The obtained polyamic acid can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while stirring well. Further, the purified polyamic acid powder can be obtained by performing precipitation several times, washing with a poor solvent, and then drying at room temperature or by heating. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Manufacturing of polyimide precursor-polyamic acid ester>
The polyamic acid ester which is a polyimide precursor can be produced by the production method (1), (2) or (3) shown below.
(1) When produced from polyamic acid The polyamic acid ester can be produced by esterifying the polyamic acid produced as described above. Specifically, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 4 hours. Can be manufactured.

The esterifying agent is preferably one that can be easily removed by purification, and is preferably N, N-dimethylformamide dimethylacetal, N, N-dimethylformamide diethylacetal, N, N-dimethylformamide dipropylacetal, N, N-dimethylformamide. Dineopentylbutylacetal, N, N-dimethylformamide di-t-butylacetal, 1-methyl-3-p-tolyltriasel, 1-ethyl-3-p-tolyltriasel, 1-propyl-3-p Examples thereof include −triltriazene, 4- (4,6-dimethoxy-1,3,5-triazine-2-yl) -4-methylmorpholinium chloride and the like. The amount of the esterifying agent added is preferably 2 to 6 mol with respect to 1 mol of the repeating unit of the polyamic acid.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-. Imidazolidinone can be mentioned. When the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the above formulas [D-1] to [D-3] can be used. The solvent shown can be used.
These solvents may be used alone or in combination. Further, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the solvent and used as long as the produced polyimide precursor does not precipitate. Further, since the water content in the solvent inhibits the polymerization reaction and further causes the produced polyimide precursor to be hydrolyzed, it is preferable to use a dehydrated and dried solvent.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone because of the solubility of the polymer, and these may be used alone or in combination of two or more. good. The concentration at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that the precipitation of the polymer is unlikely to occur and a high molecular weight substance is easily obtained.

(2) When produced by reacting tetracarboxylic dianester dichloride with diamine The polyamic acid ester can be produced from tetracarboxylic dianester dichloride and diamine.
Specifically, the tetracarboxylic dianester dichloride and diamine are mixed in the presence of a base and an organic solvent at −20 ° C. to 150 ° C., preferably 0 ° C. to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 4 hours. It can be produced by reacting.
Pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used as the base, but pyridine is preferable because the reaction proceeds mildly. The amount of the base added is preferably 2 to 4 times the molar amount of the tetracarboxylic dianester dichloride from the viewpoint that it can be easily removed and a high molecular weight substance can be easily obtained.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone because of the solubility of the monomer and the polymer, and these may be used alone or in admixture of two or more. The polymer concentration at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer is unlikely to occur and a high molecular weight polymer is easily obtained. Further, in order to prevent hydrolysis of the tetracarboxylic dianester dichloride, the solvent used for producing the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(3) Case of Producing from Tetracarboxylic Acid Diester and Diamine Polyamic acid ester can be produced by polycondensing tetracarboxylic dianester and diamine.
Specifically, tetracarboxylic acid diester and diamine are mixed in the presence of a condensing agent, a base, and an organic solvent at 0 ° C. to 150 ° C., preferably 0 ° C. to 100 ° C. for 30 minutes to 24 hours, preferably 3 to 15 It can be manufactured by reacting for a time.
The condensing agent includes triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy-1,3,5-triazi. Nylmethylmorpholinium, O- (benzotriazole-1-yl) -N, N, N', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazole-1-yl) -N, N , N', N'-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate and the like can be used. The amount of the condensing agent added is preferably 2 to 3 times the molar amount of the tetracarboxylic dianester.

A tertiary amine such as pyridine or triethylamine can be used as the base. The amount of the base added is preferably 2 to 4 times the molar amount of the diamine component because it is easy to remove and a high molecular weight substance can be easily obtained.
Further, in the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halide such as lithium chloride and lithium bromide is preferable. The amount of Lewis acid added is preferably 0 to 1.0 times the molar amount of the diamine component.

Among the above three methods for producing a polyamic acid ester, the above method (1) or the above (2) is particularly preferable because a high molecular weight polyamic acid ester can be obtained.
The solution of the polyamic acid ester obtained as described above can be injected into a poor solvent with good stirring to precipitate a polymer. Precipitation is carried out several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Polyimide>
The polyimide used in the present invention can be produced by imidizing the above-mentioned polyamic acid ester or polyamic acid. When polyimide is produced from a polyamic acid ester, chemical imidization in which a basic catalyst is added to the polyamic acid ester solution or the polyamic acid solution obtained by dissolving the polyamic acid ester resin powder in an organic solvent is convenient. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the imidization process.
Chemical imidization can be performed by stirring the polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, the solvent used in the above-mentioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. In particular, triethylamine is preferable because it has sufficient basicity to allow the reaction to proceed.

The temperature at which the imidization reaction is carried out is −20 ° C. to 140 ° C., preferably 0 ° C. to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, that of the amic acid ester group. The imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, the temperature, and the reaction time. Since the added catalyst and the like remain in the solution after the imidization reaction, the obtained imidized polymer is recovered by the means described below and redissolved in an organic solvent to obtain a liquid crystal alignment agent. Is preferable.
When polyimide is produced from a polyamic acid, it is convenient to chemically imidize by adding a catalyst to the solution of the polyamic acid obtained by the reaction of a diamine component and a tetracarboxylic dianhydride. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the imidization process.

Chemical imidization can be performed by stirring the polyamic acid to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the solvent used in the above-mentioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Among them, pyridine is preferable because it has an appropriate basicity for advancing the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Among them, acetic anhydride is preferable because it facilitates purification after the reaction is completed.
The temperature at which the imidization reaction is carried out is −20 ° C. to 140 ° C., preferably 0 ° C. to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, that of the amic acid group, and the amount of acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times that of the amic acid group. It is double. The imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, the temperature, and the reaction time.

Since the added catalyst and the like remain in the solution after the imidization reaction of the polyamic acid ester or polyamic acid, the obtained imidized polymer is recovered by the means described below and redissolved in an organic solvent. Therefore, it is preferable to use the liquid crystal aligning agent of the present invention.
The polyimide solution obtained as described above can be injected into a poor solvent with good stirring to precipitate a polymer. Precipitation is carried out several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying.
The poor solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellsolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

<Liquid crystal alignment agent>
The liquid crystal alignment agent of the present invention has the form of a solution in which the above-mentioned specific polymer (A), specific polymer (B), and (C) components are dissolved in an organic solvent. The molecular weights of the specific polymer (A) and the specific polymer (B) are preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10, It is 000 to 100,000. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and even more preferably 5,000 to 50,000.

The content (concentration) of the specific polymer (A) and the polymer containing the specific polymer (B) in the liquid crystal alignment agent of the present invention can be appropriately changed by setting the thickness of the coating film to be formed. However, 1 quality by weight or more is preferable from the viewpoint of forming a uniform and defect-free coating film, and 10 quality by weight or less is preferable from the viewpoint of storage stability of the solution. Of these, 2 to 7% by mass is preferable, and 3 to 6% by mass is particularly preferable.
The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as the specific structural polymer dissolves uniformly. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methylethylketone. , Cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone and the like. Of these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferable.

Further, when the polymer has high solubility in a solvent, it is preferable to use the solvent represented by the above formulas [D-1] to [D-3].
The good solvent in the liquid crystal alignment agent is preferably 20% by mass to 99% by mass of the total solvent contained in the liquid crystal alignment agent. Of these, 20 to 90% by mass is preferable. More preferably, it is 30 to 80% by mass.

As the liquid crystal alignment agent of the present invention, a solvent (also referred to as a poor solvent) that improves the coating film property and surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied can be used as long as the effect of the present invention is not impaired. can. Specific examples of the poor solvent are given below, but the present invention is not limited to these examples.

For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-Pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol , 2-Heptanol, 3-Heptanol, 1-Octanol, 2-Octanol, 2-Ethylene-1-hexanol, Cyclohexanol, 1-Methylcyclohexanol, 2-Methylcyclohexanol, 3-Methylcyclohexanol, 1,2- Ethylene diol, 1,2-propane diol, 1,3-propane diol, 1,2-butane diol, 1,3-butane diol, 1,4-butane diol, 2,3-butane diol, 1,5-pentane Diol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-Butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-Methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetylate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether , Ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1- (butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, Dipropylene glycol, Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetyl Tart, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol Monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate , 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactic acid ester, ethyl lactic acid ester, n-propyl ester lactic acid, n lactic acid -Butyl ester, lactate isoamyl ester or the above formulas [D-1] to [D-3] can be mentioned.

Of these, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether are preferable.
These poor solvents are preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent. Of these, 10 to 80% by mass is preferable. More preferably, it is 20 to 70% by mass.

In addition to the above, the liquid crystal aligning agent of the present invention includes polymers other than the polymers described in the present invention, and electricity such as the dielectric constant and conductivity of the liquid crystal alignment film, as long as the effects of the present invention are not impaired. Dielectric or conductive material for changing properties, silane coupling agent for improving adhesion between liquid crystal alignment film and substrate, crosslinkability for improving film hardness and density when made into liquid crystal alignment film The compound, and further, an imidization accelerator for the purpose of efficiently advancing imidization by heating the polyimide precursor when firing the coating film may be added.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is a film obtained by applying the above liquid crystal alignment agent to a substrate, drying and firing. The substrate to which the liquid crystal alignment agent is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, or the like can be used, and is used for driving the liquid crystal. It is preferable to use a substrate on which an ITO electrode or the like is formed from the viewpoint of simplifying the process. Further, in the reflective liquid crystal display element, an opaque object such as a silicon wafer can be used if only one substrate is used, and in this case, a material that reflects light such as aluminum can also be used as the electrode.

Examples of the method for applying the liquid crystal alignment agent include a spin coating method, a printing method, and an inkjet method. Any temperature and time can be selected for the drying and firing steps after applying the liquid crystal alignment agent. Usually, it is dried at 50 ° C. to 120 ° C. for 1 minute to 10 minutes and then calcined at 150 ° C. to 300 ° C. for 5 minutes to 120 minutes in order to sufficiently remove the contained organic solvent. The thickness of the coating film after firing is not particularly limited, but is 5 to 300 nm, preferably 10 to 200 nm because the reliability of the liquid crystal display element may decrease if it is too thin.
Examples of the method for aligning the obtained liquid crystal alignment film include a rubbing method and a photoalignment treatment method.

The rubbing process can be performed using an existing rubbing device. Examples of the material of the rubbing cloth at this time include cotton, nylon, rayon and the like. Generally, the conditions of the rubbing process are a rotation speed of 300 to 2000 rpm, a feed rate of 5 to 100 mm / s, and a pushing amount of 0.1 to 1.0 mm. After that, the residue generated by rubbing is removed by ultrasonic cleaning with pure water or alcohol.

As a specific example of the photo-alignment treatment method, a method in which the surface of the coating film is irradiated with radiation deflected in a certain direction and, in some cases, further heat-treated at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability. Can be mentioned. As the radiation, ultraviolet rays having a wavelength of 100 to 800 nm and visible light can be used. Of these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable. Further, in order to improve the liquid crystal orientation, the coating film substrate may be irradiated with radiation while being heated at 50 to 250 ° C. Dose of the radiation is preferably ^{1~10,000mJ / cm 2, 100~5,000mJ / cm} 2 is particularly preferred. As described above, the liquid crystal alignment film can stably orient the liquid crystal molecules in a certain direction.
The higher the extinction ratio of polarized ultraviolet rays, the higher the anisotropy can be imparted, which is preferable. Specifically, the extinction ratio of linearly polarized ultraviolet rays is preferably 10: 1 or more, more preferably 20: 1 or more.

The above-polarized radiation-irradiated membrane may then be contact treated with a solvent containing at least one selected from water and organic solvents.
The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves the decomposition products produced by light irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, 3-. Examples thereof include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate and the like. Two or more of these solvents may be used in combination.

From the viewpoint of versatility and safety, at least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate is more preferable. Water, 2-propanol, and a mixed solvent of water and 2-propanol are particularly preferred.
The contact treatment between the film irradiated with polarized radiation and the solution containing the organic solvent is performed by a treatment such as a dipping treatment or a spray treatment so that the membrane and the liquid are preferably in sufficient contact with each other. Of these, a method of immersing the membrane in a solution containing an organic solvent for preferably 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferable. The contact treatment may be carried out at room temperature or at a temperature of 10 to 80 ° C, more preferably 20 to 50 ° C. Further, if necessary, a means for enhancing contact such as ultrasonic waves can be provided.

After the contact treatment, either rinse or dry with a low boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, or both, for the purpose of removing the organic solvent in the solution used. May be done.
Further, the membrane contact-treated with the solvent may be heated at 150 ° C. or higher for the purpose of drying the solvent and reorienting the molecular chains in the membrane.

The heating temperature is preferably 150 to 300 ° C. The higher the temperature, the more the reorientation of the molecular chain is promoted, but if the temperature is too high, the molecular chain may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 ° C., particularly preferably 200 to 230 ° C.
If the heating time is too short, the effect of reorientation of the molecular chains may not be obtained, and if it is too long, the molecular chains may be decomposed. Therefore, 10 seconds to 30 minutes is preferable, and 1 minute is preferable. 10 minutes is more preferable.

<Liquid crystal display element>
The liquid crystal display element of the present invention includes a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film. The liquid crystal display element is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal alignment agent by the method for producing the liquid crystal alignment film, then producing a liquid crystal cell by a known method, and using the liquid crystal display element. be.
As an example of the liquid crystal cell manufacturing method, a liquid crystal display element having a passive matrix structure will be described. A liquid crystal display element having an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.

First, a transparent glass substrate is prepared, and a common electrode is provided on one substrate and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes and are patterned so that a desired image can be displayed. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO _2- TiO ₂ formed by the sol-gel method.
Next, the liquid crystal alignment film of the present invention is formed on each substrate. Next, the other substrate is superposed on one substrate so that the alignment film surfaces face each other, and the periphery is bonded with a sealing material. A spacer is usually mixed in the sealing material in order to control the gap between the substrates. Further, it is preferable to spray the spacer for controlling the substrate gap also on the in-plane portion where the sealing material is not provided. A part of the sealing material is provided with an opening that can be filled with liquid crystal from the outside.

Next, the liquid crystal material is injected into the space surrounded by the two substrates and the sealing material through the opening provided in the sealing material. The opening is then sealed with an adhesive. For injection, a vacuum injection method may be used, or a method utilizing a capillary phenomenon in the atmosphere may be used. Next, the polarizing plate is installed. Specifically, a pair of polarizing plates are attached to the surfaces of the two substrates opposite to the liquid crystal layer. By going through the above steps, the liquid crystal display element of the present invention can be obtained.
As the sealing agent, for example, a resin having a reactive group such as an epoxy group, an acryloyl group, a meta-acryloyl group, a hydroxyl group, an allyl group, or an acetyl group and cured by irradiation with ultraviolet rays or heating is used. In particular, it is preferable to use a cured resin system having both reactive groups of an epoxy group and a (meth) acryloyl group.

An inorganic filler may be added to the sealant for the purpose of improving adhesiveness and moisture resistance. The inorganic filler that can be used is not particularly limited, but specifically, spherical silica, molten silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, etc. Calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, etc. Spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate. , Aluminum silicate. Two or more kinds of the above-mentioned inorganic fillers may be mixed and used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The abbreviations and measuring methods of the compounds in the following are as follows.
NMP: N-methyl-2-pyrrolidone, GBL: γ-butyl lactone BCS: butyl cellosolve, PB: propylene glycol monobutyl ether,
IPA: Isopropanol, DA-1: 1,2-bis (4-aminophenoxy) ethane DA-2: See formula (DA-2) below,
DA-3: 1,2-bis (4-aminophenoxy) methane,
DA-4: p-phenylenediamine,
DA-5: 1,2-bis (4-aminophenoxy) propane DA-6: see formula (DA-6) below, DA-7: 4,4'diaminodiphenylamine,
DA-8: See formula (DA-8) below, DA-9: 4,4'diaminodiphenylmethane,

DAH-1: 1,2,3,4-cyclobutanetetracarboxylic dianhydride DAH-2: Refer to the following formula (DAH-2), DAH-3: Refer to the following formula (DAH-3) DAH-4: Cyclobutanetetra Caroxydionic dianhydride DAH-5: Pyromellitic dianhydride 1,3DM-CBDE-Cl: Dimethyl 1,3-bis (chlorocarbonyl) -1,3-dimethylcyclobutane-2,4-dicarboxylate

[添加剤]
ＡＤ−１〜３：架橋性添加剤、 ＡＤ−４：イミド化促進剤

[Additive]
AD-1 to 3: Crosslinkable additive, AD-4: Imidization accelerator

[ ^{1 1} H NMR]
Device: Fourier transform type superconducting nuclear magnetic resonance device (FT-NMR) INOVA-400 (manufactured by Varian) 400 MHz, solvent: deuterated dimethyl sulfoxide (DMSO-d ₆ ))
Standard substance: Tetramethylsilane (TMS), number of integrations: 8 or 32
[viscosity]
In the synthesis example, the viscosity of the polyimide and the polyamic acid solution was determined by using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), a sample volume of 1.1 mL, a cone rotor TE-1 (1 ° 34', R24), and the like. It was measured at a temperature of 25 ° C.

[Molecular weight]
The molecular weight of polyimide was measured by a GPC (normal temperature gel permeation chromatography) apparatus, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated as polyethylene glycol and polyethylene oxide equivalent values.
GPC device: Shodex (GPC-101),
Column: Made by Shodex (KD803, KD805 in series), Column temperature: 50 ° C.
Eluent: N, N-dimethylformamide (as an additive, lithium bromide-hydrate (LiBr · H ₂ O) 30 mmol / L (liter), phosphoric acid / anhydrous crystal (o-phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) is 10 ml / L), flow velocity: 1.0 ml / min Standard sample for preparation of calibration line: TSK standard polyethylene oxide manufactured by Toso Co., Ltd. (weight average molecular weight (Mw) about 900,000, 150,000, 100 , 000, 30,000), and polyethylene glycol manufactured by Polymer Laboratory (peak top molecular weight (Mp) about 12,000, 4,000, 1,000). For the measurement, in order to avoid overlapping peaks, a sample in which 4 types of 900,000, 100,000, 12,000, and 1,000 were mixed, and 3 types of 150,000, 30,000, and 4,000 were used. Two samples of the mixed sample were performed separately.

[Measurement of imidization rate]
20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, φ5 (manufactured by Kusano Kagaku)), and deuterated dimethyl sulfoxide (DMSO-d 6,0.05% TMS (tetramethylsilane) mixture) (0.53 ml). ) Was added, and ultrasonic waves were applied to completely dissolve the mixture. This solution was measured for proton NMR at 500 MHz with an NMR measuring machine (JNW-ECA500) (manufactured by JEOL Datum). The imidization rate is determined by using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integrated value of this proton and the proton peak derived from the NH group of amic acid appearing near 9.5 ppm to 10.0 ppm. It was calculated by the following formula using the integrated value.
Imidization rate (%) = (1-α · x / y) × 100
In the above formula, x is the integrated proton peak value derived from the NH group of amic acid, y is the integrated peak value of the reference proton, and α is one NH group proton of amic acid in the case of polyamic acid (imidization rate is 0%). It is the number ratio of the reference protons to.

[Evaluation of liquid crystal orientation]
The liquid crystal cell was sandwiched between polarizing plates, and the liquid crystal cell was rotated in a state where the backlight was irradiated from the rear portion, and it was visually observed whether the liquid crystal was oriented depending on the change in brightness and the presence or absence of flow orientation. At that time, evaluation was made according to the following criteria.
Evaluation criteria ⊚: Liquid crystal orientation can be confirmed and there is no flow orientation ○: Liquid crystal is oriented but some flow orientation is observed ×: Liquid crystal is oriented but many flow orientations are observed ..

(Synthesis Example 1)
Take 42.75 g (175 mmol) of DA-1 and 59.7 g (175 mmol) of DA-2 in a 1000 mL four-necked flask with a stirrer and a nitrogen introduction tube, add 586 g of NMP, and stir while sending nitrogen. And dissolved. While stirring this diamine solution, 74.53 g (332.5 mmol) of DAH-1 was added, NMP was further added so that the solid content concentration became 18% by mass, and the mixture was stirred at room temperature for 24 hours to obtain a polyamic acid (PAA-). The solution of 1) (viscosity: 832 mPa · s) was obtained.

(Synthesis Example 2)
200 g of the polyamic acid solution (PAA-1) obtained in a 1000 ml four-necked flask equipped with a stirrer and a nitrogen introduction tube was taken, 100 g of NMP was added, and the mixture was stirred for 30 minutes. To the obtained polyamic acid solution, 21.78 g of acetic anhydride and 2.81 g of pyridine were added, and the mixture was heated at 60 ° C. for 3 hours for chemical imidization. The obtained reaction solution was added to 624.2 g of methanol with stirring, and the precipitated precipitate was collected by filtration, followed by washing with 624.2 g of methanol three times and with 1248 g of methanol twice. The obtained resin powder was dried at 60 ° C. for 12 hours to obtain a polyimide resin powder. The imidization ratio of this polyimide resin powder was 68%, the molecular weight was Mn = 9189, and Mw = 18252.
32.70 g of the obtained polyimide resin powder was taken in a 200 ml sample tube containing a stirrer, 239.8 g of NMP was added, and the mixture was stirred and dissolved at 70 ° C. for 20 hours to obtain a polyimide solution (SPI-1).

(Synthesis Example 3)
Take 7.14 g (31 mmol) of DA-3 in a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, add 75.1 g of a 1: 1 mixed solvent of NMP and GBL, and stir while sending nitrogen. It was dissolved. 2.33 g (9.3 mmol) of DAH-3 was added while stirring this diamine solution, and the mixture was stirred overnight. After that, 6.13 g (20.8 mmol) of DAH-2 was further added, a 1: 1 mixed solvent of NMP and GBL was added so that the solid content concentration became 15% by weight, and the mixture was stirred at room temperature for 5 hours to obtain a polyamic acid (PAA). A solution of -2) (viscosity: 787 mPa · s) was obtained.

(Synthesis Example 4)
Take 5.53 g (24 mmol) of DA-3 into a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, add 72.7 g of a 1: 1 mixed solvent of NMP and GBL, and stir while sending nitrogen. It was dissolved. While stirring this diamine solution, 6.87 g (23.4 mmol) of DAH-2 was added, a 1: 1 mixed solvent of NMP and GBL was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight to obtain a polyamic acid. A solution of (PAA-3) (viscosity: 520 mPa · s) was obtained.

(Synthesis Example 5)
0.908 g (8.4 mmol) of DA-4, 1.37 g (5.6 mmol) of DA-1, and 2.17 g (2.17 g) of DA-5 in a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube. 8.4 mmol), 2.23 g (5.6 mmol) of DA-6 was taken, 76.8 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 5.99 g (26.7 mmol) of DAH-1 was added, NMP was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight to obtain a solution of polyamic acid (PAA-4) (PAA-4). Viscosity: 397 mPa · s) was obtained.

(Synthesis Example 6)
Take 15.9 g (80 mmol) of DA-7 and 6.0 g (20 mmol) of DA-8 in a 500 mL four-necked flask with a stirrer and a nitrogen introduction tube, add 230.0 g of NMP, and feed nitrogen. While stirring, it was dissolved. 4.4 g (22.5 mmol) of DAH-4 was added while stirring this diamine solution, and the mixture was stirred overnight. After that, 18.8 g (75 mmol) of DAH-3 was further added, NMP was added so that the solid content concentration became 15% by weight, and the mixture was stirred at 50 ° C. for 10 hours to obtain a solution of polyamic acid (PAA-5) (viscosity: 1405 mPa). -S) was obtained.

(Synthesis Example 7)
1.91 g (9.6 mmol) of DA-7 and 0.72 g (2.4 mmol) of DA-8 were taken in a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, and 1: 1 of NMP and GBL. 35.4 g of the mixed solvent was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 3.40 g (11.6 mmol) of DAH-2 was added, a 1: 1 mixed solvent of NMP and GBL was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight to obtain a polyamic acid. A solution of (PAA-6) (viscosity: 810 mPa · s) was obtained.

(Synthesis Example 8)
10.00 g (92.4 mmol) of DA-4, 13.60 g (55.5 mmol) of DA-1 and 12.60 g of DA-2 (12.60 g) in a 2 L four-necked flask equipped with a stirrer and a nitrogen introduction tube. 37.0 mmol) was taken, and 379.00 g of NMP, 1023.00 g of GBL and 34.60 g (0.43 mol) of pyridine were added and dissolved. Next, 58.30 g (179.4 mmol) of 1,3 DMCBDE-Cl was added with stirring of this solution, and the mixture was reacted under water cooling for 14 hours. 2.41 g (26.6 mmol) of acryloyl chloride was added to the obtained polyamic acid solution, and the mixture was further reacted for 4 hours. Then, this solution was added to 8653 ml of isopropanol with stirring, and the precipitated white precipitate was collected by filtration. .. Subsequently, 21635 ml of isopropanol was washed using 5 times and dried to obtain a white polyamic acid ester resin powder (PWD-1). The molecular weight of this polyamic acid ester was Mn = 24,366 and Mw = 54,808.
The polyamic acid ester resin powder (PWD-1) obtained above was dissolved in GBL to obtain a polyamic acid ester solution (PAE-1) having a solid content concentration of 12% by mass.

(Synthesis Example 9)
Take 2.23 g (11.2 mmol) of DA-7 and 0.56 g (2.8 mmol) of DA-9 in a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, and add 26.4 g of NMP. , Nitrogen was sent and stirred to dissolve. While stirring this diamine solution, 2.63 g (9.3 mmol) of DAH-3 was added, 4.4 g of NMP was further added, and the mixture was stirred at room temperature for 3 hours. After that, 0.58 g (2.94 mmol) of DAH-4 was further added, a 1: 1 mixed solvent of NMP and GBL was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight at room temperature to form a polyamic acid (PAA-). A solution of 7) (viscosity: 630 mPa · s) was obtained.

(Synthesis Example 10)
In a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, take 3.9 g (20 mmol) of DA-7 and 0.99 g (5.0 mmol) of DA-9, add 74.8 g of NMP, and add nitrogen. Was stirred and dissolved while feeding. While stirring this diamine solution, 5.15 g (17.5 mmol) of DAH-2 was added, and the mixture was stirred at room temperature for 5 hours. After that, 1.20 g (6.13 mmol) of DAH-4 was added, NMP was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight to add a solution of polyamic acid (PAA-8) (viscosity: 398 mPa · s). Obtained.

(Synthesis Example 11)
3.10 g (12 mmol) of DA-5 and 4.78 g (12 mmol) of DA-6 are taken in a 100 mL four-necked flask with a stirrer and a nitrogen introduction tube, 74.5 g of NMP is added, and nitrogen is sent. While stirring, it was dissolved. While stirring this diamine solution, 4.97 g (22.8 mmol) of DAH-5 was added, NMP was added so that the solid content concentration became 12% by weight, and the mixture was stirred overnight to obtain a solution of polyamic acid (PAA-9). Viscosity: 273 mPa · s) was obtained.

(Example 1)
2.929 g of the polyimide solution (SPI-1) obtained in Synthesis Example 2 and 4.62 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were placed in a 50 mL Erlenmeyer flask containing a stirrer. Add 2.83 g of NMP, 3.45 g of GBL, 3.60 g of PB, 0.495 g of 10% NMP solution of AD-1 and 0.139 g of AD-4, and stir overnight with a magnetic stirrer to align the liquid crystal. Agent (AL-1) was obtained.

(Example 2)
2.929 g of the polyimide solution (SPI-1) obtained in Synthesis Example 2 and 4.62 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were placed in a 50 mL Erlenmeyer flask containing a stirrer. Add 3.32 g of NMP, 3.45 g of GBL, 3.60 g of PB, 0.0297 g of AD-2 and 0.139 g of AD-4, and stir overnight with a magnetic stirrer to stir the liquid crystal alignment agent (AL-2). ) Was obtained.

(Example 3)
2.929 g of the polyimide solution (SPI-1) obtained in Synthesis Example 2 and 4.62 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were placed in a 50 mL Erlenmeyer flask containing a stirrer. Add 3.32 g of NMP, 3.45 g of GBL, 3.60 g of PB, 0.0297 g of AD-3 and 0.139 g of AD-4, and stir overnight with a magnetic stirrer to stir the liquid crystal alignment agent (AL-3). ) Was obtained.

(Comparative Example 1)
2.929 g of the polyimide solution (SPI-1) obtained in Synthesis Example 2 and 4.62 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were placed in a 50 mL Erlenmeyer flask containing a stirrer. 3.32 g of NMP, 3.45 g of GBL and 3.60 g of PB were added, 0.139 g of AD-4 was added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-A).

(Comparative Example 2)
2.929 g of the polyimide solution (SPI-1) obtained in Synthesis Example 2 and 5.90 g of the polyamic acid solution (PAA-3) obtained in Synthesis Example 4 were placed in a 50 mL Erlenmeyer flask containing a stirrer. 2.19 g of NMP, 2.81 g of GBL, 3.60 g of PB were added, 0.495 g of 10% NMP solution of AD-1 and 0.139 g of AD-4 were added, and the mixture was stirred overnight with a magnetic stirrer to prepare a liquid crystal alignment agent. (AL-B) was obtained.

(Example 4)
3.249 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 3.60 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 5.40 g of NMP and 5.40 g of BCS were added, 0.45 g of a 10% NMP solution of AD-1 was added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-4).

(Example 5)
3.249 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 3.60 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 5.85 g of NMP and 5.40 g of BCS were added, 0.027 g of AD-2 was added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-5).

(Example 6)
3.249 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 3.60 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 5.85 g of NMP and 5.40 g of BCS were added, 0.045 g of AD-3 was added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-6).

(Comparative Example 3)
3.249 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 3.60 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 5.85 g of NMP and 5.40 g of BCS were added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-C).

(Comparative Example 4)
3.249 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 and 4.58 g of the polyamic acid solution (PAA-6) obtained in Synthesis Example 7 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 4.42 g of NMP and 5.40 g of BCS were added, 0.45 g of a 10% NMP solution of AD-1 was further added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-D).

(Example 7)
In a 50 mL Erlenmeyer flask containing a stirrer, 3.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 8 and 3.96 g of the polyamic acid solution (PAA-7) obtained in Synthesis Example 9 were taken. rice field. Add 1.54 g of NMP, 5.12 g of GBL, 3.60 g of BCS, 0.495 g of 10% NMP solution of AD-1, and stir overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-7). rice field.

(Comparative Example 5)
In a 50 mL Erlenmeyer flask containing a stirrer, 3.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 8 and 3.96 g of the polyamic acid solution (PAA-7) obtained in Synthesis Example 9 were taken. rice field. 2.03 g of NMP, 5.12 g of GBL and 3.60 g of BCS were added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-E).

(Comparative Example 6)
In a 50 mL Erlenmeyer flask containing a stirrer, 3.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 8 and 4.94 g of the polyamic acid solution (PAA-8) obtained in Synthesis Example 10 were taken. rice field. Add 0.56 g of NMP, 5.12 g of GBL, 3.60 g of BCS, 0.495 g of 10% NMP solution of AD-1, and stir overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-F). rice field.

(Example 8)
1.87 g of the polyamic acid solution (PAA-9) obtained in Synthesis Example 11 and 4.80 g of the polyamic acid solution (PAA-7) obtained in Synthesis Example 9 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 5.58 g of NMP and 5.40 g of BCS were added, 0.45 g of a 10% NMP solution of AD-1 was further added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-8).

(Comparative Example 7)
1.87 g of the polyamic acid solution (PAA-9) obtained in Synthesis Example 11 and 4.80 g of the polyamic acid solution (PAA-7) obtained in Synthesis Example 9 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 6.03 g of NMP and 5.40 g of BCS were added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-G).

(Comparative Example 8)
1.87 g of the polyamic acid solution (PAA-9) obtained in Synthesis Example 11 and 5.99 g of the polyamic acid solution (PAA-8) obtained in Synthesis Example 10 were taken in a 50 mL Erlenmeyer flask containing a stir bar. .. 4.50 g of NMP and 5.40 g of BCS were added, 0.45 g of a 10% NMP solution of AD-1 was further added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal aligning agent (AL-H).

(Example 9)
The liquid crystal alignment agent (AL-1) obtained in Example 1 is filtered through a filter having a pore size of 1.0 μm, spin-coated on a glass substrate with a transparent electrode, and dried on a hot plate at a temperature of 80 ° C. for 2 minutes. rice field. Then, it was calcined in a hot air circulation type oven at a temperature of 230 ° C. for 20 minutes to obtain an imidized film having a film thickness of 110 nm. The fired film was irradiated with ultraviolet rays of 254 nm through a polarizing plate at 200 mJ / cm ^2. Then, the substrate was washed with IPA / water = 1: 1 mixed solvent for 5 minutes, and further fired in a hot air circulation oven at 230 ° C. for 20 minutes. As a result, a substrate with a liquid crystal alignment film was obtained.

In order to evaluate the electrical characteristics of the liquid crystal cell, two substrates with the liquid crystal alignment film were prepared, and a 6 μm spacer was sprayed on the one liquid crystal alignment film. A sealant was printed on the substrate, and another substrate was bonded so that the liquid crystal alignment film surfaces faced each other and the photoalignment directions were parallel, and then the sealant was cured to prepare an empty cell. Liquid crystal ML-7026-100 (manufactured by Merck Japan) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an IPS liquid crystal cell. The results of evaluating and confirming the initial orientation of the liquid crystal cell based on the above criteria are shown in Table 1 below. This cell was heat-treated at 120 ° C. for 30 minutes to complete a liquid crystal cell.
Further, after aging the liquid crystal cell on the backlight for 3 days, a voltage of 1 V is applied for 60 μs at a temperature of 60 ° C., and the voltage after 500 ms is measured to determine how much the voltage can be maintained. Obtained as the retention rate.

(Examples 10 and 11, Comparative Examples 9 and 10)
Liquid crystal cells were prepared and evaluated in the same procedure as in Example 9 except that the liquid crystal alignment agents shown in Table 1 were used instead of the liquid crystal alignment agent AL-1. Table 1 shows the results of the initial orientation and voltage retention of each liquid crystal cell.

(Example 12)
The liquid crystal alignment agent (AL-4) obtained in Example 4 is filtered through a filter having a pore size of 1.0 μm, spin-coated on a glass substrate with a transparent electrode, and dried on a hot plate at a temperature of 80 ° C. for 2 minutes. rice field. Then, it was calcined in a hot air circulation type oven at a temperature of 230 ° C. for 30 minutes to obtain an imidized film having a film thickness of 100 nm. The fired film was irradiated with ultraviolet rays of 254 nm through a polarizing plate at 150 mJ / cm ^2. After that, it was further fired in a hot air circulation oven at 230 ° C. for 30 minutes. As a result, a substrate with a liquid crystal alignment film was obtained.
In order to evaluate the electrical characteristics of the liquid crystal cell, two substrates with the liquid crystal alignment film were prepared, and a 6 μm spacer was sprayed on the one liquid crystal alignment film. A sealant was printed on the substrate, and another substrate was bonded so that the liquid crystal alignment film surfaces faced each other and the photoalignment directions were parallel, and then the sealant was cured to prepare an empty cell. Liquid crystal ML-7026-100 (manufactured by Merck Japan) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an IPS liquid crystal cell. The results of evaluating and confirming the initial orientation of the liquid crystal cell based on the above criteria are shown in Table 1 below. This cell was heat-treated at 120 ° C. for 30 minutes to complete a liquid crystal cell.
Further, after aging the liquid crystal cell on the backlight for 3 days, a voltage of 1 V is applied for 60 μs at a temperature of 60 ° C., and the voltage after 500 ms is measured to determine how much the voltage can be maintained. Obtained as the retention rate.

(Examples 13 and 14, Comparative Examples 11 and 12)
Liquid crystal cells were prepared and evaluated in the same procedure as in Example 9 except that the liquid crystal alignment agents shown in Table 1 were used instead of the liquid crystal alignment agent AL-4. Table 1 shows the results of the initial orientation and voltage retention of each liquid crystal cell.

(Example 16)
The liquid crystal alignment agent (AL-8) obtained in Example 8 is filtered through a filter having a pore size of 1.0 μm, spin-coated on a glass substrate with a transparent electrode, and dried on a hot plate at a temperature of 80 ° C. for 2 minutes. rice field. Then, it was calcined in a hot air circulation type oven at a temperature of 230 ° C. for 20 minutes to obtain an imidized film having a film thickness of 110 nm. The fired film was oriented by rubbing. Then, it was washed with running water for 1 minute, and dried at 80 ° C. for 10 minutes. As a result, a substrate with a liquid crystal alignment film was obtained.
In order to evaluate the electrical characteristics of the liquid crystal cell, two substrates with the liquid crystal alignment film were prepared, and a 6 μm spacer was sprayed on the one liquid crystal alignment film. A sealant was printed on the substrate, and another substrate was bonded so that the liquid crystal alignment film surfaces faced each other and the orientation directions were parallel, and then the sealant was cured to prepare an empty cell. Liquid crystal ML-7026-100 (manufactured by Merck Japan) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an IPS liquid crystal cell. The results of evaluating and confirming the initial orientation of the liquid crystal cell based on the above criteria are shown in Table 1 below. This cell was heat-treated at 120 ° C. for 30 minutes to complete a liquid crystal cell.
Further, after aging the liquid crystal cell on the backlight for 3 days, a voltage of 1 V is applied at 20 ° C. for 60 μs, the voltage after 500 ms is measured, and how much the voltage can be maintained is defined as the voltage retention rate. I asked.

(Comparative Examples 15 and 16)
Liquid crystal cells were prepared and evaluated in the same procedure as in Example 16 except that the liquid crystal alignment agents shown in Table 1 were used instead of the liquid crystal alignment agent AL-G. Table 1 shows the results of the initial orientation and voltage retention of each liquid crystal cell.

The above results are summarized in Table 1. In Table 1, the component 1 is a polymer component containing a thermal leaving group.

The liquid crystal display element having a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be suitably used as a wide range display such as a liquid crystal television, a smartphone, and a car navigation system.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2016-001659 filed on January 7, 2016 are cited here and incorporated as disclosure of the specification of the present invention. It is a thing.

Claims (13)

A liquid crystal alignment agent containing the following component (A), component (B), component (C) and an organic solvent.
Component (A): At least one diamine compound selected from a tetracarboxylic acid derivative component, a diamine compound having a structure of the following formula [A-1], and a diamine compound having a structure of the following formula [A-2]. At least one polymer selected from a polyimide precursor obtained by using the contained diamine component and polyimide which is an imidized polymer of the polyimide precursor.

(R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a group represented by the following formula (1), and at least one of them is a protecting group that replaces a hydrogen atom by heat. R ₃ and R ₄ are monovalent hydrocarbon groups having 1 to 20 carbon atoms which may independently have a hydrogen atom or a substituent, respectively, and are D. Is a thermally desorbing group, which is a protecting group that replaces hydrogen atoms by heat.)

(A is a divalent group consisting of a single bond or a hydrocarbon group having 1 to 4 carbon atoms.)
Component (B): At least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (2) and an imidized polymer of the polyimide precursor.

(X ₁ is a tetravalent organic group represented by the following formula (X-1), Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl having 1 to 5 carbon atoms. Groups A _{1 to} A ₂ are alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, or alkenyl groups having 2 to 10 carbon atoms, each of which may have a hydrogen atom or a substituent independently. It is an alkynyl group of.)

Component (C): A compound containing two or more crosslinkable functional groups. The compound containing two or more crosslinkable functional groups contains at least two or more functional groups selected from a hydroxyl group, a hydroxyalkylamide group, a (meth) acrylate group, a blocked isocyanate group, an oxetane group, and an epoxy group. The liquid crystal alignment agent according to claim 1, which is a compound contained. The liquid crystal alignment agent according to claim 1 or 2, wherein the compound containing two or more crosslinkable functional groups is a compound containing two or more hydroxyl groups. The invention according to any one of claims 1 to 3, wherein the compound containing two or more crosslinkable functional groups is contained in an amount of 0.1 to 20% by mass based on the total of the component (A) and the component (B). Liquid crystal alignment agent. The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the compound containing two or more crosslinkable functional groups is represented by the following formula (7).

(X ₃ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an n-valent organic group containing an aromatic hydrocarbon group, n is an integer of 2 to _6, and R _{6 and R 7} are respectively. Independently, it is an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkynyl group having 2 to 4 carbon atoms, which may have a hydrogen atom or a substituent, and is R ₆ and R _7. At least one of them represents a hydrocarbon group substituted with a hydroxy group.) The liquid crystal alignment agent according to claim 5, wherein at least one of R ₆ and R _{7 is represented by the following formula (8).}

(R _{8 to} R ₁₁ each independently represent a hydrocarbon group substituted with a hydrogen atom, a hydrocarbon group, or a hydroxy group.) The liquid crystal alignment agent according to any one of claims 1 to 6, wherein the component (C) is a compound represented by the following formula.

The liquid crystal alignment agent according to any one of claims 1 to 7, wherein the heat-removable group is a group represented by the following formula (1).

(A is a divalent group consisting of a single bond or a hydrocarbon group having 1 to 4 carbon atoms.) The liquid crystal alignment agent according to any one of claims 1 to 8, wherein the thermoremovable group is a tert-butoxycarbonyl group. The liquid crystal alignment agent according to any one of claims 1 to 9, wherein the polymer of the component (B) further has a structural unit represented by the following formula (3).

(X ₂ is a tetravalent organic group (excluding the above formula (X-1)), Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl having 1 to 5 carbon atoms. Groups A _{1 to} A ₂ are alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, or alkenyl groups having 2 to 10 carbon atoms, each of which may have a hydrogen atom or a substituent independently. It is an alkynyl group of.) A liquid crystal alignment film obtained from the liquid crystal alignment agent according to any one of claims 1 to 10. A liquid crystal display element comprising the liquid crystal alignment film according to claim 11. A transverse electric field drive type liquid crystal display element including the liquid crystal alignment film according to claim 11.