JP5109979B2 - Liquid crystal alignment treatment agent and liquid crystal display element using the same - Google Patents

Description

  The present invention relates to a liquid crystal alignment treatment agent, a liquid crystal alignment film using the same, and a liquid crystal display element. In particular, the present invention relates to a liquid crystal alignment treatment agent used for a liquid crystal display element manufactured through a rubbing treatment step, a liquid crystal alignment film using the same, and a liquid crystal display element.

The liquid crystal display element has a structure in which liquid crystal molecules are sandwiched between liquid crystal alignment films formed on a substrate, and is a display element utilizing the response of the liquid crystal molecules by voltage. The liquid crystal alignment film has an important role of controlling the alignment direction and pretilt angle of the liquid crystal molecules in an arbitrary state.
The liquid crystal alignment film is generally produced by performing a so-called “rubbing process” in which the surface of a polyimide film formed on a substrate is rubbed against the surface with rayon, nylon cloth, or the like. The rubbing treatment determines the alignment direction of the liquid crystal molecules.
As means for increasing the pretilt angle of the liquid crystal, means for introducing a long-chain alkyl group into the structure of the polyimide forming the liquid crystal alignment film is known (for example, see Patent Document 1).
As a means for forming a polyimide film on the substrate, there are a method of applying a solution such as polyamic acid and imidizing on the substrate, and a method of applying a soluble polyimide solution.
Among them, the method using a soluble polyimide solution is capable of forming a polyimide film with good characteristics when used as a liquid crystal alignment film, even when firing at a relatively low temperature. There is a problem that the strength of the film is low, and the rubbing treatment tends to cause scratches and peeling of the film surface.

In addition, flexographic printing is widely used industrially as a means for applying a polymer solution to a substrate when preparing a liquid crystal alignment film. However, since a solution of a soluble polyimide having a high imidization rate is inferior in printability, it has been necessary to devise such as mixing polyamic acid or a soluble polyimide having a low imidization rate (for example, see Patent Document 2). ). Furthermore, when a long-chain alkyl group is introduced into the structure of the soluble polyimide in order to give a large pretilt angle to the liquid crystal, this printability tends to deteriorate.
As means for improving the printability of a polymer solution on a substrate, a method of adding a solvent such as butyl cellosolve is known (see, for example, Patent Document 3). However, since soluble polyimide generally has lower solubility than polyamic acid and the like, a solvent such as butyl cellosolve cannot be used in a large amount.

JP-A-2-282726 JP-A-9-297312 Japanese Unexamined Patent Publication No. 2-037324

  The object of the present invention is to obtain a liquid crystal alignment film having excellent rubbing resistance of the coating film, a large pretilt angle of the liquid crystal (for example, 4 ° or more), and good printability even when the imidization ratio is high. It is in providing the liquid crystal aligning agent of this.

（式（２）中、Ｘ_１は、単結合、又は、エーテル、エステル、及びアミドからなる群より選ばれる結合基を表し、Ｘ_２は炭素数１〜１２の直鎖状アルキル基を表す。式（３）において、ｎは１又は２である。式（５）において、Ｘ_３は、単結合、又は、−Ｏ−、−ＣＨ_２−、−ＮＨ−、及び−ＣＯＮＨ−からなる群より選ばれる結合基を表し、Ｒは水素原子又はメチル基である。）

（式（６）中、Ｘ_４は、単結合、又は、エーテル、エステル、メチレンエーテル、及びアミドからなる群より選ばれる結合基を表し、Ｘ_５は炭素数１４〜２０の直鎖状アルキル基、又は下記式（７）で表される１価の有機基である。）

（式（７）中、Ｘ_６は、フェニル基又はシクロヘキシル基であり、Ｘ_７は炭素数１〜１２の直鎖状アルキル基を有するシクロヘキシル基である。）
（２）ポリイミド（Ａ）とポリイミド（Ｂ）とを５０：５０〜９０：１０の質量比で含有する、上記（１）に記載の液晶配向処理剤。
（３）ポリイミド（Ａ）及びポリイミド（Ｂ）のイミド化率が共に４０％以上である、上記（１）又は（２）に記載の液晶配向処理剤。
（４）ポリイミド（Ａ）中の全ジアミン量１００モル％に対して、式（１）で表されるジアミンが２０〜１００モル％含有し、かつ、式（１）のジアミン含有量が１００モル％未満の場合には、残りのジアミンは、式（２）、式（３）、式（４）、及び式（５）からなる群より選ばれる少なくとも１種のジアミンである、上記（１）〜（３）のいずれかに記載の液晶配向処理剤。
（５）ポリイミド（Ｂ）中の全ジアミン量１００モル％に対して、式（１）で表されるジアミンを２０〜９０モル％、式（６）で表されるジアミンを５〜４０モル％含有し、かつ、式（１）のジアミンと式（６）のジアミンの合計含有量が１００モル％未満の場合には、残りのジアミンは式（２）、式（３）、式（４）、及び式（５）からなる群より選ばれる少なくとも１種のジアミンである、上記（１）〜（４）のいずれかに記載の液晶配向処理剤。
（６）さらに、有機溶媒成分を含有する上記（１）〜（５）のいずれかに記載の液晶配向処理剤。
（７）前記有機溶媒成分が、γ−ブチロラクトンと、ブチルセロソルブと、ジプロピレングリコールモノメチルエーテル又はジエチレングリコールジエチルエーテルと、を含有する上記（６）に記載の液晶配向処理剤。
（８）液晶配向処理剤が、ラビング処理される液晶配向膜用である上記（１）〜（７）のいずれかに記載の液晶配向処理剤。
（９）上記（１）〜（８）のいずれかに記載の液晶配向処理剤を用いて得られる液晶配向膜。
（１０）上記（１）〜（８）のいずれかに記載の液晶配向処理剤を電極付き基板上に塗布、焼成し、ラビング処理して得られる液晶配向膜。
（１１）上記（９）又は（１０）に記載の液晶配向膜を有する液晶表示素子。As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the present invention has the following gist.
(1) A liquid crystal aligning agent containing the following polyimide (A) and the following polyimide (B).
Polyimide (A):
(I) a diamine component comprising a diamine represented by formula (1), or (ii) a diamine represented by formula (1), formula (2), formula (3), formula (4), and formula (5) A polyimide obtained by imidizing a polyamic acid obtained by reacting at least one diamine selected from the group consisting of a diamine component and a tetracarboxylic dianhydride component.
Polyimide (B):
(Iii) A diamine component consisting of a diamine represented by formula (1) and a diamine represented by formula (6), or (iv) a diamine represented by formula (1) and a formula (6) A diamine component, and at least one diamine selected from the group consisting of Formula (2), Formula (3), Formula (4), and Formula (5), and a tetracarboxylic dianhydride component Polyimide obtained by imidizing polyamic acid obtained by reacting with.

(In formula (2), X ₁ represents a single bond or a linking group selected from the group consisting of ethers, esters, and amides, and X ₂ represents a linear alkyl group having 1 to 12 carbon atoms. In the formula (3), n is 1 or 2. In the formula (5), X ₃ is a single bond or a group consisting of —O—, —CH ₂ —, —NH—, and —CONH—. Represents a selected bonding group, and R is a hydrogen atom or a methyl group.)

(In formula (6), X ₄ represents a single bond or a linking group selected from the group consisting of ether, ester, methylene ether and amide, and X ₅ is a linear alkyl group having 14 to 20 carbon atoms. Or a monovalent organic group represented by the following formula (7).)

(In the formula (7), _{X 6} is phenyl or cyclohexyl, _{X 7} is a cyclohexyl group having a linear alkyl group having 1 to 12 carbon atoms.)
(2) The liquid-crystal aligning agent as described in said (1) which contains a polyimide (A) and a polyimide (B) by mass ratio of 50: 50-90: 10.
(3) The liquid-crystal aligning agent as described in said (1) or (2) whose imidation ratio of a polyimide (A) and a polyimide (B) is both 40% or more.
(4) The diamine represented by the formula (1) is contained in an amount of 100 to 100 mol% in the polyimide (A), and the diamine content in the formula (1) is 100 mol. In the case of less than%, the remaining diamine is at least one diamine selected from the group consisting of formula (2), formula (3), formula (4), and formula (5), (1) Liquid crystal aligning agent in any one of-(3).
(5) 20 to 90 mol% of the diamine represented by the formula (1) and 5 to 40 mol% of the diamine represented by the formula (6) with respect to 100 mol% of the total diamine amount in the polyimide (B). When the total content of the diamine of the formula (1) and the diamine of the formula (6) is less than 100 mol%, the remaining diamine is represented by the formula (2), the formula (3), and the formula (4). And the liquid crystal aligning agent according to any one of (1) to (4), which is at least one diamine selected from the group consisting of Formula (5).
(6) Furthermore, the liquid-crystal aligning agent in any one of said (1)-(5) containing an organic-solvent component.
(7) The liquid crystal aligning agent according to (6), wherein the organic solvent component contains γ-butyrolactone, butyl cellosolve, and dipropylene glycol monomethyl ether or diethylene glycol diethyl ether.
(8) The liquid crystal aligning agent according to any one of (1) to (7), wherein the liquid crystal aligning agent is for a liquid crystal alignment film to be rubbed.
(9) A liquid crystal alignment film obtained using the liquid crystal aligning agent according to any one of (1) to (8).
(10) A liquid crystal alignment film obtained by applying the liquid crystal alignment treatment agent according to any one of (1) to (8) above onto a substrate with electrodes, baking, and rubbing.
(11) A liquid crystal display device having the liquid crystal alignment film according to (9) or (10).

  Since the liquid crystal alignment treatment agent of the present invention is excellent in printability when applied to a substrate, there are few scratches on the film surface and peeling of the film during rubbing treatment, and a liquid crystal alignment film having a large liquid crystal pretilt angle is obtained. It is possible to obtain a liquid crystal display element with few display defects and good characteristics. In addition, the liquid crystal aligning agent of the present invention has the above-described characteristics even though the imidation ratio of the polyimide contained therein can be increased, and thus a highly reliable liquid crystal display element can be obtained. Can do.

Hereinafter, the present invention will be described in detail.
The liquid-crystal aligning agent of this invention contains two types of polyimides, the following polyimide (A) and the following polyimide (B), and polyimide (A) and polyimide (B) are 50: 50- It is contained at a mass ratio of 90:10. The liquid crystal aligning agent of the present invention is particularly suitable for a liquid crystal alignment film to be rubbed. That is, the liquid crystal aligning agent of this invention is used in order to apply | coat and bake on a board | substrate with an electrode, and to rub and to make a liquid crystal aligning film.

<Polyimide (A)>
The polyimide (A) used in the present invention is a polyimide obtained by imidizing a polyamic acid obtained by reacting a diamine component and a tetracarboxylic dianhydride component. The polyimide (A) is soluble in the organic solvent contained in the liquid crystal aligning agent of the present invention, and a reaction system for obtaining a polyimide (A) by reacting a diamine component and a tetracarboxylic dianhydride component. It is also soluble in the organic solvent used.

[Diamine component]
The diamine component used to obtain the polyimide (A) has a diamine represented by the following formula (1) as an essential component.

  In the diamine represented by the formula (1), the position of each substituent on the benzene ring is not particularly limited, but the positional relationship between the two amino groups is preferably meta or para. Although the preferable specific example of this diamine is given to the following, it is not limited to this.

Use of the diamine represented by the formula (1) is effective in suppressing scratches on the film surface and peeling of the film during the rubbing treatment, and also increases the solubility of the polyimide (A) in the organic solvent. . Although the diamine represented by Formula (1) can be used individually by 1 type, you may use multiple types together.
Content of the diamine represented by Formula (1) is 20-100 mol% of the whole diamine component in a polyimide (A), Preferably it is 30-100 mol%, More preferably, it is 40-100 mol%. . As the ratio of the diamine represented by the formula (1) increases, the effect of suppressing scratches on the alignment film surface and peeling of the film during the rubbing treatment increases, and the solubility of polyimide in an organic solvent also increases.
When the diamine represented by the formula (1) is less than 100 mol%, the remaining diamine is selected from the group consisting of the following formula (2), formula (3), formula (4), and formula (5). At least one kind. The content of at least one diamine selected from the group consisting of Formula (2), Formula (3), Formula (4), and Formula (5) is more than 0 to 80 of the total diamine component in polyimide (A). It is mol%, Preferably it is 5-70 mol%, More preferably, it is 10-60 mol%. In particular, the content of the diamine represented by the formula (2) is preferably more than 0 to 40 mol%, more preferably 5 to 30 mol%, still more preferably 10 to 30 mol%, and the remaining content is , At least one diamine selected from the group consisting of formula (3), formula (4), and formula (5).

In formula (2), X ₁ represents a single bond or a linking group selected from the group consisting of ethers, esters, and amides, and X ₂ represents a linear alkyl group having 1 to 12 carbon atoms.
In the formula (3), n is 1 or 2, and preferably 1.
In Formula (5), X ₃ represents a single bond or a bonding group selected from the group consisting of —O—, —CH ₂ —, —NH—, and —CONH—, and R represents a hydrogen atom or a methyl group. And preferably a hydrogen atom.

  Use of the diamine of formula (2) has the effect of increasing the solubility and the pretilt angle of the liquid crystal. Moreover, when the diamine represented by Formula (3)-Formula (5) is used, there exists an effect which improves the orientation of a liquid crystal.

Although the specific example of the diamine represented by Formula (2)-Formula (5) below is given, it is not limited to this.
Examples of the diamine represented by the formula (2) include diamines represented by the following formulas (11) to (14).

式（１１）〜式（１４）においてｍは０〜１１、好ましくは５〜１１の整数である。

In the formulas (11) to (14), m is an integer of 0 to 11, preferably 5 to 11.

  Examples of diamines represented by formula (3) include 2-aminobenzylamine, 3-aminobenzylamine, 4-aminobenzylamine, 2- (2-aminophenyl) ethylamine, 2- (3-aminophenyl) ethylamine , 2- (4-aminophenyl) ethylamine and the like.

Examples of the diamine represented by the formula (4) include paraphenylene diamine, metaphenylene diamine, and ortho phenylene diamine.
Examples of diamines represented by formula (5) include 4,4′-diaminobiphenyl, 4,4′-diamino-2,2′-dimethylbiphenyl, and 4,4′-diamino-3,3′-dimethylbiphenyl. 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diaminodiphenylamine, 4, 4'-diaminodiphenylamide and the like can be mentioned.
Among these, 3-aminobenzylamine or 4-aminobenzylamine is particularly preferable because of its high solubility when used as a polyimide.

[Tetracarboxylic dianhydride component]
In order to obtain the polyimide (A), the tetracarboxylic dianhydride component to be reacted with the diamine component described above is printability when applied to the substrate, scratches on the surface of the liquid crystal alignment film generated during rubbing treatment, and film peeling. It is not limited in terms of improving the problem, but rather various selections may be made according to other characteristics. In the present invention, the tetracarboxylic dianhydride to be used may be used alone or in combination.
For example, from the viewpoint that a polyimide having a relatively high solubility can be easily obtained even with a polyimide having a high imidization ratio, and a voltage holding ratio of a liquid crystal cell can be increased, a tetracyclic structure having an alicyclic structure or an aliphatic structure can be used. It is preferable to use a carboxylic dianhydride.

Examples of the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetra Carboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic Acid dianhydride, 3,4-dicarboxy-1-cyclohexyl succinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, 1, , 3,4-Butanetetracarboxylic dianhydride, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetra Carboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6-tetracarboxylic dianhydride , Tricyclo [4.2.1.0 ^2,5 ] nonane-3,4,7,8-tetracarboxylic acid-3,4: 7,8-dianhydride, hexacyclo [6.6.0.1 ^{2 , 7} . 0 ^3,6 . 1 ^9,14 . 0 ^10,13] hexadecane -4,5,11,12- tetracarboxylic acid-4,5: 11,12-like dianhydride.
In particular, when an aromatic tetracarboxylic dianhydride is used in combination, the liquid crystal alignment can be improved and the accumulated charge of the liquid crystal cell can be reduced.

  As aromatic tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic acid Dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4-benzophenonetetra Carboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Products, 2,3,6,7-naphthalenetetracarboxylic dianhydride and the like.

  Tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure when considering the balance of properties such as solubility of polyimide (A), liquid crystal orientation, voltage holding ratio, and accumulated charge characteristics And the combined ratio of the aromatic tetracarboxylic dianhydride is preferably 90 / 10-60 / 40, more preferably 80 / 20-70 / 30 in terms of the former / the latter molar ratio. A particularly preferred combination of tetracarboxylic dianhydrides is 1,2,3,4-cyclobutanetetracarboxylic dianhydride and pyromellitic dianhydride.

[Production method of polyamic acid]
The reaction for obtaining the polyamic acid by reacting the diamine component with the tetracarboxylic dianhydride component is usually performed by mixing the tetracarboxylic dianhydride component and the diamine component in an organic solvent.
The method for mixing the tetracarboxylic dianhydride component and the diamine component in an organic solvent is not particularly limited. For example, a solution in which a diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic dianhydride component is added as it is or dispersed or dissolved in an organic solvent, or the tetracarboxylic dianhydride component is organically added. Examples thereof include a method of adding a diamine component to a solution dispersed or dissolved in a solvent, and a method of alternately adding a tetracarboxylic dianhydride component and a diamine component. Moreover, when a tetracarboxylic dianhydride component or a diamine component consists of multiple types of compounds, the polymerization reaction may be performed in a state where these multiple types of components are mixed in advance, or the polymerization reaction may be sequentially performed individually.

The temperature at which the tetracarboxylic dianhydride component and the diamine component are subjected to a polymerization reaction in an organic solvent is usually 0 to 150 ° C, preferably 5 to 100 ° C, more preferably 10 to 80 ° C.
When the temperature for the polymerization reaction is high, the polymerization reaction ends quickly, but if it is too high, a high molecular weight polymer may not be obtained.
In addition, the polymerization reaction can be carried out at any concentration of the polymer to be produced, but if the concentration is too low, it will be difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution will become too high. And uniform stirring becomes difficult. Therefore, the concentration when the polymerization reaction is performed is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. Further, a method of performing the polymerization reaction at a high concentration in the initial stage and then reducing the concentration by adding an organic solvent can be used.

  The organic solvent used for the reaction is not particularly limited as long as the generated polyamic acid is soluble. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, etc. Can be mentioned.

These organic solvents may be used alone or in combination. Furthermore, even if it is an organic solvent which does not dissolve a polyamic acid, it can also be mixed and used for the above-mentioned organic solvent, as long as the produced polyamic acid does not precipitate.
Moreover, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

The ratio of the tetracarboxylic dianhydride component and the diamine component used for the polymerization reaction of the polyamic acid is preferably 0.8: 1 to 1.2: 1 in terms of molar ratio, and 0.9: 1 to 1: 1. Is more preferable. The closer the molar ratio is to 1: 1, the higher the molecular weight of the polyamic acid obtained. By controlling the molecular weight of this polyamic acid, the molecular weight of the polyimide obtained after imidation can be adjusted.
In the present invention, the molecular weight of the polyamic acid is not particularly limited, but the precursor for obtaining a polyimide (A) particularly suitable for the present invention is preferably 2,000 to 200,000 in terms of weight average molecular weight, more preferably. 5,000 to 50,000.

[Production method of polyimide (A)]
The imidization of the polyamic acid obtained as described above can be performed by stirring in an organic solvent for 1 to 100 hours in the presence of a basic catalyst and an acid anhydride.
Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity in the progress of the reaction.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, acetic anhydride is preferable because the obtained polyimide can be easily purified after imidization.
As an organic solvent used when imidizing a polyamic acid, the same organic solvent as the organic solvent used for the polymerization reaction of the polyamic acid mentioned above can be used.

The imidation ratio of the polyimide (A) can be controlled by adjusting the amount of catalyst, reaction temperature, reaction time, and the like. The amount of the basic catalyst is preferably 0.2 to 10 times mol, more preferably 0.5 to 5 times mol of the amic acid group. Further, the amount of the acid anhydride is preferably 1 to 30 times mol, more preferably 1 to 10 times mol of the amic acid group. The reaction temperature is preferably -20 to 250 ° C, more preferably 0 to 180 ° C. The reaction time is 1 to 100 hours, preferably 1 to 10 hours.
The imidation ratio of the polyimide (A) is not particularly limited, but is preferably 40% or more, more preferably 60% or more, and particularly preferably 80% or more in order to obtain a high voltage holding ratio.
Since the added catalyst or the like remains in the obtained polyimide (A) solution, it is preferably used for the liquid crystal aligning agent of the present invention after the polyimide is recovered and washed.

The polyimide (A) can be recovered by putting the solution after imidization into a poor solvent that is being stirred, and precipitating the polyimide, followed by filtration. Examples of the poor solvent include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene. The recovered polyimide can also be washed with this poor solvent. The recovered and washed polyimide can be powdered by drying at normal temperature or under reduced pressure at room temperature or by heating.
The molecular weight of the polyimide (A) contained in the liquid crystal aligning agent of the present invention is not particularly limited, but is 2,000 in terms of weight average molecular weight from the viewpoint of the strength of the coating film and ease of handling as the liquid crystal aligning agent. -200,000 are preferable, More preferably, it is 5,000-50,000.

<Polyimide (B)>
The polyimide (B) is a polyimide obtained by imidizing a polyamic acid obtained by reacting a diamine component and a tetracarboxylic dianhydride component. The polyimide (B) is soluble in the organic solvent contained in the liquid crystal aligning agent of the present invention, and a reaction system for obtaining a polyimide (B) by reacting a diamine component and a tetracarboxylic dianhydride component. It is also soluble in the organic solvent used.

[Diamine component]
The diamine component used in order to obtain a polyimide (B) makes the diamine represented by Formula (1) and the diamine represented by Formula (6) an essential component.

In Formula (6), X ₄ represents a single bond or a linking group selected from the group consisting of ether, ester, methylene ether, and amide, and X ₅ is a linear alkyl group having 14 to 20 carbon atoms, Or it is a monovalent organic group represented by following formula (7).

In Formula (7), X ₆ is a phenyl group or a cyclohexyl group, and X ₇ is a cyclohexyl group having a linear alkyl group having 1 to 12 carbon atoms.

As the diamine represented by the formula (1), the [diamine component] described in the polyimide (A) is used, and the role and preferred specific examples thereof are also the same.
In polyimide (B), not only the diamine represented by Formula (1) but also the diamine represented by Formula (6) is essential as a diamine component. Content of the diamine represented by Formula (1) is 20-90 mol% of the whole diamine component in a polyimide (B), Preferably it is 30-60 mol%, More preferably, it is 30-50 mol%.
On the other hand, the diamine represented by the formula (6) is preferably contained in an amount of 5 to 40 mol% of the total diamine component in the polyimide (B) because the pretilt angle of the liquid crystal can be increased. The content of the diamine represented by the formula (6) is more preferably 10 to 40 mol%, still more preferably 10 to 30 mol%. In particular, the larger the ratio of the diamine represented by the formula (6), the greater the pretilt angle of the liquid crystal, which is preferable. The diamine represented by Formula (6) may be used alone or in combination of two or more.

  Further, when the total content of the diamine of formula (1) and the diamine of formula (6) in the entire diamine component in the polyimide (B) is less than 100 mol%, the remaining diamine is represented by the formula (2) described above. , At least one selected from the group consisting of formula (3), formula (4), and formula (5). Preferably, it is at least one diamine selected from the group consisting of Formula (3), Formula (4), and Formula (5), and these diamines have an effect of maintaining good alignment of liquid crystals. The content of these diamines is more than 0 to 75 mol%, preferably 5 to 75 mol%, more preferably 10 to 60 mol% in the diamine component in the polyimide (B).

式（１５）〜式（１９）においてｐは１３〜１９、好ましくは１３〜１７の整数である。Although the specific example of diamine represented by Formula (6) below is given, it is not limited to this.

In the formulas (15) to (19), p is an integer of 13 to 19, preferably 13 to 17.

式（２０）〜式（２４）においてｑは０〜１１、好ましくは２〜６の整数である。

In Formula (20)-Formula (24), q is 0-11, Preferably it is an integer of 2-6.

式（２５）〜式（２９）においてｈは０〜１１、好ましくは２〜６の整数である。

In the formula (25) to the formula (29), h is an integer of 0 to 11, preferably 2 to 6.

[Tetracarboxylic dianhydride component]
In order to obtain the polyimide (B), the tetracarboxylic dianhydride component to be reacted with the diamine component described above is printability when applied to the substrate, scratches on the surface of the liquid crystal alignment film generated during rubbing treatment, and film peeling. It is not limited in terms of improving the problem, but rather may be selected variously according to other characteristics. The tetracarboxylic dianhydride to be used may be used alone or in combination. Preferable specific examples include tetracarboxylic dianhydrides exemplified in [Tetracarboxylic dianhydride component] of polyimide (A).

[Method for producing polyamic acid and polyimide (B)]
The reaction operation of obtaining the polyamic acid by reacting the diamine component and the tetracarboxylic dianhydride component described above, the imidation of the obtained polyamic acid, the operation of recovering the polyimide, etc. are carried out by using [Polyamic acid of the polyimide (A)]. The production method] and [Production method of polyimide (A)] can be performed in the same manner.
The molecular weight of the polyamic acid that is a precursor of the polyimide (B) is not particularly limited, but as a precursor for obtaining a polyimide (B) particularly suitable for the present invention, a weight average molecular weight of 2,000 to 200,000 is used. Preferably, it is 5,000 to 50,000.
The molecular weight of the polyimide (B) is not particularly limited, but is preferably 2,000 to 200,000 in terms of weight average molecular weight, more preferably from the viewpoint of the strength of the coating film and the ease of handling as a liquid crystal aligning agent. Is 5,000 to 50,000.
The imidation ratio of the polyimide (B) is not particularly limited, but is preferably 40% or more, like the polyimide (A), more preferably 60% or more, and particularly preferably 80% or more in order to obtain a high voltage holding ratio. .

<Liquid crystal alignment agent>
The liquid-crystal aligning agent of this invention is a solution containing a polyimide (A) and a polyimide (B) in a suitable ratio. For example, polyimide (A) and polyimide (B) powders are each dissolved in an organic solvent to form a polyimide solution, and these solutions are mixed and then diluted to a desired concentration, or each polyimide solution is desired. The solution was mixed after being diluted to a concentration of In the dilution step, adjustment of the organic solvent composition for controlling the coating property to the substrate, and addition of additives for improving the properties of the coating film can be performed.
The ratio of polyimide (A) and polyimide (B) contained in the liquid crystal aligning agent of the present invention is such that the content of polyimide (A) is 50 with respect to the total content of polyimide (A) and polyimide (B). It is -90 mass%, and it is easy to obtain favorable printability and a large pretilt angle. The content of the polyimide (A) is more preferably 60 to 80% by mass.
That is, polyimide (A) and polyimide (B) are 50:50 to 90:10, and preferably 60:40 to 80:20, in terms of mass ratio of the former and the latter.

  As an organic solvent for re-dissolving the polyimide (A) and / or polyimide (B) powder, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl Examples include caprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, tetramethylurea, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone. Of these, γ-butyrolactone is preferred because it hardly absorbs moisture.

Solvents added to control the coating property to the substrate include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, diethylene glycol diethyl ether, 1-methoxy-2-propanol, 1- Ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-mono Ethyl ether-2-acetate, dipropylene glycol, dipropylene glycol monomethyl ether, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, Acid ethyl ester, lactic acid n- propyl ester, lactate n- butyl ester, and the like lactic isoamyl ester.
These solvents include solvents that cannot dissolve polyimide (A) or polyimide (B) alone, but can be mixed with the liquid crystal aligning agent of the present invention as long as the polyimide does not precipitate. it can. In particular, it is known that the coating film uniformity is improved upon application to a substrate by appropriately mixing a solvent having a low surface tension, and it is also suitably used in the liquid crystal aligning agent of the present invention.

  Among the above solvent combinations, it is preferable to include dipropylene glycol monomethyl ether or diethylene glycol diethyl ether in addition to γ-butyrolactone and butyl cellosolve. Is preferred. As a ratio of each solvent, γ-butyrolactone is 40 to 80% by mass, preferably 40 to 70% by mass, butyl cellosolve is 10 to 30% by mass, preferably 10 to 20% by mass, and dipropylene glycol monomethyl in the whole solvent. Ether or diethylene glycol diethyl ether is 10 to 30% by mass, preferably 10 to 20% by mass. The liquid crystal aligning agent of the present invention using such a composition is less likely to cause unevenness and pinholes due to changes in film thickness when printed.

  Additives for improving the properties of the coating include 3-aminopropylmethyldiethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, (aminoethylaminomethyl) phenethyltrimethoxysilane And silane coupling agents such as By adding a silane coupling agent, the adhesion of the coating film to the substrate can be further improved.

  The content (concentration) of polyimide contained in the liquid crystal alignment treatment agent of the present invention can be appropriately changed depending on the thickness of the liquid crystal alignment film to be formed. Usually, the total content of polyimide (A) and polyimide (B) is preferably 1 to 10% by mass, particularly preferably 2 to 6% by mass. In such a case, it is easy to form a uniform and defect-free coating film. Further, the storage stability of the liquid crystal aligning agent is further improved. In addition, it is preferable that the liquid-crystal aligning agent in this invention is filtered before apply | coating to a board | substrate depending on the case.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is obtained by applying the above-mentioned liquid crystal alignment treatment agent to a substrate, drying, baking and curing to form a coating film, and performing an alignment process such as rubbing on the coating film surface.
The substrate to be used is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, or a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used. In addition, it is preferable to use a substrate on which an ITO electrode or the like for driving liquid crystal is formed from the viewpoint of simplifying the process. Further, in the reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used if only one substrate is used, and a material that reflects light such as aluminum can be used for the electrode.
Examples of the method for applying the liquid crystal aligning agent include spin coating, printing, and inkjet. From the standpoint of productivity, the flexographic printing method is widely used industrially, and is preferably used also in the liquid crystal aligning agent of the present invention.

The drying step after applying the liquid crystal aligning agent is not necessarily required. However, when the time from application to baking is not constant for each substrate, or when baking is not performed immediately after application, a drying step is preferably performed. The degree of drying is not particularly limited as long as the solvent evaporates to such an extent that the shape of the coating film is not deformed by transporting the substrate or the like. For example, a method of drying on a hot plate at a temperature of 50 to 150 ° C., preferably 80 to 120 ° C. for 0.5 to 30 minutes, preferably 1 to 5 minutes can be mentioned.
The substrate coated with the liquid crystal aligning agent can be baked at an arbitrary temperature of 100 to 350 ° C., preferably 150 to 300 ° C., more preferably 180 to 250 ° C. When an amic acid group is present in the polyimide, the imidization rate of the polyimide film obtained varies depending on the firing temperature. However, in the present invention, the imidization rate is not necessarily 100%.

The thickness of the coating film after baking is disadvantageous in terms of power consumption of the liquid crystal display element if it is too thick, and if it is too thin, the reliability of the liquid crystal display element may be lowered, so it is preferably 10 to 200 nm, more preferably 50-100 nm.
An existing rubbing apparatus can be used for rubbing the coating surface formed on the substrate as described above. Examples of the material of the rubbing cloth at this time include cotton, rayon, and nylon.
The liquid crystal alignment film of the present invention can be obtained by the method described above.

<Liquid crystal display element>
The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the method described above, and then preparing a liquid crystal cell by a known method.
For example, the liquid crystal cell is manufactured by any angle of 0 to 270 ° in the rubbing direction with a pair of substrates on which a liquid crystal alignment film is formed, preferably having a spacer of 1 to 30 μm, more preferably 2 to 10 μm. A method is generally used in which the surroundings are fixed with a sealant, and liquid crystal is injected and sealed. The method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method of injecting liquid crystal after reducing the pressure inside the produced liquid crystal cell, and a dropping method of sealing after dropping the liquid crystal.

The present invention will be described in more detail with reference to the following examples, but the present invention should not be construed as being limited thereto.
Abbreviations used in Examples and Comparative Examples are as follows.
<Tetracarboxylic dianhydride>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride PMDA: pyromellitic dianhydride TDA: 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid Anhydride <Diamine>
2,4-DAA: 2,4-diamino-N, N-diallylaniline PCH7AB: 4- {4- (4-heptylcyclohexyl) phenoxy} -1,3-diaminobenzene C12DAB: 4-dodecyloxy-1,3 -Diaminobenzene C14DAB: 4-tetradecyloxy-1,3-diaminobenzene C16DAB: 4-hexadecyloxy-1,3-diaminobenzene 4-ABA: 4-aminobenzylamine 3-ABA: 3-aminobenzylamine < Organic solvent>
NMP: N-methyl-2-pyrrolidone γBL: γ-butyrolactone BS: Butyl cellosolve DPM: Dipropylene glycol monomethyl ether <Structural formula>

<Measurement of molecular weight>
The molecular weight of the polyimide was measured with a GPC (normal temperature gel permeation chromatography) apparatus, and the number average molecular weight and weight average molecular weight were calculated as polyethylene glycol and polyethylene oxide equivalent values.
GPC device: manufactured by Shodex (GPC-101)
Column: manufactured by Shodex (series of KD803 and KD805)
Column temperature: 50 ° C
Eluent: N, N-dimethylformamide (as additives, lithium bromide-hydrate (LiBr · H ₂ O) is 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, tetrahydrofuran (THF) is 10ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation and polyethylene glycol (molecular weight: about 12,000, 4,000, 1,000) manufactured by Polymer Laboratories .

<Measurement of imidization ratio>
The imidation ratio of polyimide was measured as follows. 20 mg of polyimide powder was put in an NMR sample tube, and 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d ₆ , 0.05% TMS mixture) was added and completely dissolved. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNM-ECA500) manufactured by JEOL Datum. The imidation rate is determined based on protons derived from a structure that does not change before and after imidation as a reference proton, and the peak integrated value of this proton and the proton peak integrated value derived from the NH group of the amic acid that appears in the vicinity of 9.5 to 10.0 ppm. Was obtained by the following equation.
Imidation ratio (%) = (1−α · x / y) × 100
In the above formula, x is the proton peak integrated value derived from the NH group of the amic acid, y is the peak integrated value of the reference proton, and α is one NH group proton of the amic acid in the case of polyamic acid (imidation rate is 0%). The number ratio of the reference protons.

(Synthesis Example 1)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 8.13 g (0.040 mol) of 2,4-DAA as a diamine component, Using 4.67 g (0.030 mol) of 4-ABA and 8.77 g (0.030 mol) of C12DAB, the reaction was carried out at room temperature in 161.8 g of NMP for 24 hours to obtain a polyamic acid solution.
To 34.81 g of this polyamic acid solution, 62.65 g of NMP was added for dilution, and 5.15 g of acetic anhydride and 2.19 g of pyridine were added and reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 366.8 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-1). The number average molecular weight of this polyimide was 12,016, and the weight average molecular weight was 35,126. Moreover, the imidation ratio was 90%.
17.91 g of γBL was added to 1.99 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 7.53 g of γBL, 4.82 g of BS, and 4.82 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 2)
As the tetracarboxylic dianhydride component, 13.43 g (0.0685 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 8.13 g (0.040 mol) of 2,4-DAA as the diamine component, Using 4.50 g (0.045 mol) of 4-ABA and 4.39 g (0.015 mol) of C12DAB, the reaction was carried out at room temperature in 152.0 g of NMP for 24 hours to obtain a polyamic acid solution.
To 32.39 g of this polyamic acid solution, 72.88 g of NMP was added for dilution, 5.09 g of acetic anhydride and 2.17 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 393.9 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-2). The number average molecular weight of this polyimide was 12,616, and the weight average molecular weight was 39,703. Moreover, the imidation ratio was 90%.
27.09 g of γBL was added to 3.01 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 10.09 g of γBL, 8.21 g of BS, and 8.21 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 3)
As the tetracarboxylic dianhydride component, 13.33 g (0.068 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 8.13 g (0.040 mol) of 2,4-DAA as the diamine component, Using 7.33 g (0.060 mol) of 4-ABA, the mixture was reacted in 141.4 g of NMP at room temperature for 24 hours to obtain a polyamic acid solution.
67.84 g of NMP was added to 30.15 g of this polyamic acid solution for dilution, 5.11 g of acetic anhydride and 2.18 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 368.5 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol, and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-3). The number average molecular weight of this polyimide was 12,899, and the weight average molecular weight was 39,984. Moreover, the imidation ratio was 85%.
27.54 g of γBL was added to 3.06 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 10.14 g of γBL, 8.24 g of BS, and 8.24 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 4)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, Using 3.89 g (0.040 mol) of 3-ABA and 9.62 g (0.030 mol) of C14DAB, the reaction was carried out at room temperature for 24 hours in 162.7 g of NMP to obtain a polyamic acid solution.
To 35.79 g of this polyamic acid solution, 63.91 g of NMP was added for dilution, 5.16 g of acetic anhydride and 2.20 g of pyridine were added, and the mixture was reacted at 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 374.7 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-4). The number average molecular weight of this polyimide was 13,472, and the weight average molecular weight was 35,859. Further, the imidization ratio was 89%.
15.91 g of γBL was added to 2.17 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 6.37 g of γBL, 7.38 g of BS, and 7.38 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 5)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, A polyamic acid solution was obtained by using 6.11 g (0.050 mol) of 3-ABA and 6.97 g (0.020 mol) of C16DAB and reacting in NMP157.0 g at room temperature for 24 hours.
To 23.20 g of this polyamic acid solution, 32.77 g of NMP was added for dilution, and 3.49 g of acetic anhydride and 1.49 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 213.3 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-5). The number average molecular weight of this polyimide was 12,498, and the weight average molecular weight was 34,121. Further, the imidization ratio was 89%.
11.66 g of γBL was added to 1.59 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 4.99 g of γBL, 5.78 g of BS, and 5.78 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 6)
As the tetracarboxylic dianhydride component, 13.33 g (0.068 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 8.13 g (0.040 mol) of 2,4-DAA as the diamine component, Using 6.11 g (0.040 mol) of 4-ABA and 3.81 g (0.010 mol) of PCH7AB, a reaction was performed in NMP151.7 g at room temperature for 24 hours to obtain a polyamic acid solution.
59.61 g of NMP was added to 33.38 g of this polyamic acid solution to dilute, 5.26 g of acetic anhydride and 2.24 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 351.7 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-6). The number average molecular weight of this polyimide was 10,877, and the weight average molecular weight was 34,898. Moreover, the imidation ratio was 90%.
17.19 g of γBL was added to 1.91 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 2.37 g of γBL, 4.35 g of BS, and 4.35 g of DPM were added and sufficiently stirred to obtain a uniform solution.
(Synthesis Example 7)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, Using 3.67 g (0.030 mol) of 3-ABA and 12.82 g (0.040 mol) of C14DAB, the reaction was performed in 170.6 g of NMP at room temperature for 24 hours to obtain a polyamic acid solution.
To 58.20 g of this polyamic acid solution, 102.3 g of NMP was added for dilution, 8.06 g of acetic anhydride and 3.44 g of pyridine were added, and the mixture was reacted at 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 601.9 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-7). The number average molecular weight of this polyimide was 11,013, and the weight average molecular weight was 36,721. Further, the imidization ratio was 89%.
23.98 g of γBL was added to 3.27 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 7.75 g of γBL, 11.95 g of BS, and 11.95 g of DPM were added and sufficiently stirred to obtain a uniform solution.
(Synthesis Example 8)
As a tetracarboxylic dianhydride component, 19.36 g (0.099 mol) of CBDA, 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, and 4.89 g (0.040 mol) of 3-ABA ), 9.42 g (0.030 mol) of C14DAB was used and reacted at room temperature in 159.8 g of NMP for 24 hours to obtain a polyamic acid solution.
To this polyamic acid solution 74.94 g, 131.68 g of NMP was added for dilution, and 11.09 g of acetic anhydride and 4.73 g of pyridine were added and reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 778.5 ml of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-8). The number average molecular weight of this polyimide was 16,241, and the weight average molecular weight was 40,259. Further, the imidization ratio was 89%.
43.20 g of γBL was added to 4.80 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 3.60 g of γBL, 18.05 g of BS, and 18.05 g of DPM were added and sufficiently stirred to obtain a uniform solution.
(Synthesis Example 9)
As the tetracarboxylic dianhydride component, 9.61 g (0.049 mol) of CBDA, 15.02 g (0.050 mol) of TDA, and 6.10 g (0.030 mol) of 2,4-DAA as the diamine component, Using 3.89 g (0.040 mol) of 3-ABA and 9.62 g (0.030 mol) of C14DAB, the reaction was carried out at room temperature in 180.9 g of NMP for 24 hours to obtain a polyamic acid solution.
To this 40.54 g of this polyamic acid solution, 70.66 g of NMP was added for dilution, and 5.27 g of acetic anhydride and 2.24 g of pyridine were added and reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 415.5 ml of methanol, and the precipitated solid was recovered. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-9). The number average molecular weight of this polyimide was 14,756, and the weight average molecular weight was 35,977. Moreover, the imidation ratio was 90%.
36.63 g of γBL was added to 4.07 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 2.44 g of γBL, 14.16 g of BS, and 14.16 g of DPM were added and sufficiently stirred to obtain a uniform solution.

(Synthesis Example 10)
Using 19.41 g (0.099 mol) of CBDA as the tetracarboxylic dianhydride component and 20.33 g (0.100 mol) of 2,4-DAA as the diamine component, the reaction was conducted at room temperature in 159.00 g of NMP for 24 hours. To obtain a polyamic acid solution.
To 25.13 g of this polyamic acid solution, 38.79 g of NMP was added for dilution, 3.94 g of acetic anhydride and 1.68 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 243.4 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-10). The number average molecular weight of this polyimide was 10,122, and the weight average molecular weight was 21,004. Moreover, the imidation ratio was 97%.
22.52 g of γBL was added to 2.50 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring.

(Synthesis Example 11)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 8.13 g (0.040 mol) of 2,4-DAA as a diamine component, Using 4.67 g (0.030 mol) of 4-ABA and 8.77 g (0.030 mol) of C12DAB, the reaction was carried out at room temperature for 24 hours in 162.6 g of NMP to obtain a polyamic acid solution.
To 38.33 g of this polyamic acid solution, 69.99 g of NMP was added for dilution, 5.67 g of acetic anhydride and 2.42 g of pyridine were added, and the mixture was reacted at a temperature of 45 ° C. for 3 hours to imidize.
The reaction solution was cooled to about room temperature and then poured into 403.9 ml of methanol to recover the precipitated solid. Further, the solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-11). The number average molecular weight of this polyimide was 13,513, and the weight average molecular weight was 47,948. Moreover, the imidation ratio was 76%.
46.89 g of γBL was added to 5.21 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 14.49 g of γBL, 14.49 g of BS, and 14.49 g of DPM were added and sufficiently stirred to obtain a uniform solution.
(Synthesis Example 12)
As a tetracarboxylic dianhydride component, 13.53 g (0.069 mol) of CBDA, 6.54 g (0.030 mol) of PMDA, and 6.10 g (0.030 mol) of 2,4-DAA as a diamine component, Using 3.89 g (0.040 mol) of 3-ABA and 9.62 g (0.030 mol) of C14DAB, the reaction was carried out at room temperature for 24 hours in 162.7 g of NMP to obtain a polyamic acid solution.
69.88 g of NMP was diluted with 39.77 g of this polyamic acid solution, 5.79 g of acetic anhydride and 2.47 g of pyridine were added, and the mixture was reacted at a temperature of 50 ° C. for 1 hour to imidize.
The reaction solution was cooled to about room temperature and then poured into 412.7 ml of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide (SPI-12). The number average molecular weight of this polyimide was 10,734, and the weight average molecular weight was 28,190. The imidation ratio was 79%.
43.2 g of γBL was added to 4.8 g of the polyimide obtained above, and the mixture was stirred at a temperature of 50 ° C. for 24 hours. The polyimide was completely dissolved at the end of stirring. After cooling this solution to about room temperature, 3.6 g of γBL, 18.05 g of BS, and 18.05 g of DPM were added and sufficiently stirred to obtain a uniform solution.
(Reference Example 1)
A polyamic acid was reacted for 24 hours at room temperature in 211.10 g of NMP using 22.59 g (0.115 mol) of CBDA as a tetracarboxylic dianhydride component and 14.66 g (0.120 mol) of 4-ABA as a diamine component. An acid solution was obtained.
22.21 g of this polyamic acid solution was diluted by adding 22.74 g of NMP, and 10.12 g of acetic anhydride and 4.71 g of pyridine were added and reacted at a temperature of 50 ° C., resulting in gelation in 30 minutes. Could not get.
Next, the imidation reaction of the same solution as described above was performed for 3 hours while reducing the reaction temperature to 35 ° C.
The reaction solution was cooled to about room temperature and then poured into 205.7 ml of methanol to recover the precipitated solid. The solid was washed several times with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a white powder of polyimide. The number average molecular weight of this polyimide was 12,994, and the weight average molecular weight was 30,081. The imidation ratio was 78%.
14.64 g of γBL was added to 1.64 g of the polyimide obtained above and stirred at a temperature of 50 ° C. for 24 hours, but undissolved polyimide remained at the end of stirring, and 2,4-DAA was added to the diamine component. When not used, it was confirmed that the solubility of polyimide was inferior.
The results of Synthesis Examples 1 to 12 and Reference Example 1 are shown in Table 1.

Example 1
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 4, SPI-1 and SPI-4 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.

<Evaluation of printability>
The liquid crystal alignment treatment agent was flexographically printed on the cleaned Cr plate using an alignment film printer (“Nongstromer” manufactured by Nissha Printing Co., Ltd.). The substrate after printing was left on a hot plate at 70 ° C. for 5 minutes, and the coating film was temporarily dried.
When the surface of the film after the temporary drying was observed with an optical microscope ("ECLIPSE ME600" manufactured by Nikon Corporation) at a magnification of 50 times, there was no unevenness due to film thickness change, and no pinholes (film repelling) were observed. It was.

<Evaluation of rubbing resistance>
The liquid crystal alignment treatment agent is spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at 70 ° C. for 5 minutes, and then baked on a hot plate at 230 ° C. for 15 minutes to form a coating film having a thickness of 100 nm. Formed. This coating film surface was rubbed with a rubbing apparatus having a roll diameter of 120 mm using a rayon cloth under the conditions of a roll rotation speed of 1000 rpm, a roll traveling speed of 50 mm / sec, and an indentation amount of 0.3 mm to obtain a substrate with a liquid crystal alignment film.
When the film surface of the liquid crystal alignment film was observed with a confocal laser microscope at a magnification of 2000, no scratches or film peeling was observed.
For observation of the film surface, a real-time scanning laser microscope 1LM21D manufactured by Lasertec was used.

(Example 2)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 5, SPI-1 and SPI-5 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.

(Example 3)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 6, SPI-1 and SPI-6 were mixed so that the mass ratio was 7: 3 to obtain the liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.

Example 4
Using the polyimide solutions obtained in Synthesis Example 2 and Synthesis Example 4, SPI-2 and SPI-4 were mixed at a mass ratio of 7: 3 to obtain the liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.

(Example 5)
Using the polyimide solutions obtained in Synthesis Example 3 and Synthesis Example 4, SPI-3 and SPI-4 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 6)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 7, SPI-1 and SPI-7 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 7)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 8, SPI-1 and SPI-8 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 8)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 9, SPI-1 and SPI-9 were mixed at a mass ratio of 7: 3 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
Example 9
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 4, SPI-1 and SPI-4 were mixed at a mass ratio of 6: 4 to obtain a liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 10)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 4, SPI-1 and SPI-4 were mixed at a mass ratio of 9: 1 to obtain the liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 11)
Using the polyimide solutions obtained in Synthesis Example 10 and Synthesis Example 4, SPI-10 and SPI-4 were mixed at a mass ratio of 7: 3 to obtain the liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 12)
Using the polyimide solution obtained in Synthesis Example 1 and Synthesis Example 12, SPI-1 and SPI-12 were mixed so as to have a mass ratio of 7: 3 to obtain a liquid crystal alignment treatment agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.
(Example 13)
Using the polyimide solutions obtained in Synthesis Example 11 and Synthesis Example 4, SPI-11 and SPI-4 were mixed at a mass ratio of 7: 3 to obtain the liquid crystal aligning agent of the present invention.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.

(Comparative Example 1)
Using the polyimide solution obtained in Synthesis Example 4 as a liquid crystal alignment treatment agent, the printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, the unevenness due to the change in film thickness was severe and many pinholes were observed. No scratches or film peeling were observed.

(Comparative Example 2)
Using the polyimide solutions obtained in Synthesis Example 1 and Synthesis Example 4, SPI-1 and SPI-4 were mixed at a mass ratio of 4: 6 to obtain a liquid crystal alignment treatment agent.
Using this liquid crystal aligning agent, printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, the unevenness due to the change in film thickness was severe and many pinholes were observed. No scratches or film peeling were observed.

(Comparative Example 3)
Using the polyimide solution obtained in Synthesis Example 1 as a liquid crystal aligning agent, the printability and rubbing resistance were evaluated in the same manner as in Example 1. As a result, there was no unevenness due to the change in film thickness, no pinholes were observed, and no scratches and film peeling were observed.

<Evaluation of pretilt angle>
About the liquid-crystal aligning agent used in Examples 1-5 and Comparative Examples 1-3, the pretilt angle of the liquid crystal cell was evaluated as follows.
A liquid crystal alignment treatment agent is spin-coated on a glass substrate with a transparent electrode, dried on a hot plate at a temperature of 70 ° C. for 5 minutes, and then baked on a hot plate at 230 ° C. for 15 minutes to form a coating film having a thickness of 100 nm. I let you. This coating film surface was rubbed with a rubbing apparatus having a roll diameter of 120 mm using a rayon cloth under the conditions of a roll rotation speed of 1000 rpm, a roll traveling speed of 50 mm / sec, and an indentation amount of 0.3 mm to obtain a substrate with a liquid crystal alignment film.
Two substrates are prepared, a 6 μm spacer is sprayed on one liquid crystal alignment film surface, a sealant is printed thereon, the other substrate faces the liquid crystal alignment film surface, and the rubbing direction is reversed. After laminating in the direction, the sealing agent was cured to produce an empty cell. Liquid crystal MLC-2003 (manufactured by Merck Japan Co., Ltd.) was injected into this empty cell by a reduced pressure injection method, the inlet was sealed, and an anti-parallel nematic liquid crystal cell was obtained.
Using this liquid crystal cell, the pretilt angle at a temperature of 23 ° C. was measured. For the measurement, TBA107 manufactured by autotronic was used. The evaluation results are shown in Table 2.

<Evaluation of voltage holding ratio>
Using two substrates with a liquid crystal alignment film prepared in the same manner as described above, a 6 μm spacer was sprayed on one liquid crystal alignment film surface, a sealant was printed, and the other substrate was a liquid crystal alignment film surface. Were stuck together so that the rubbing direction was perpendicular, and the sealing agent was cured to produce an empty cell. Liquid crystal MLC-2003 (C080) (manufactured by Merck Japan Ltd.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a twisted nematic liquid crystal cell.
A voltage of 4 V was applied to the liquid crystal cell at a temperature of 23 ° C. for 60 μs, the voltage after 16.67 ms was measured, and how much the voltage could be held was calculated as a voltage holding ratio. The same measurement was performed at a temperature of 90 ° C. For measuring the voltage holding ratio, a VHR-1 voltage holding ratio measuring device manufactured by Toyo Technica Co., Ltd. was used.
Table 2 shows the evaluation results of the characteristics in Examples 1 to 13 and Comparative Examples 1 to 3.
The rubbing resistance was evaluated as ◯ when the surface of the liquid crystal alignment film was not scratched or peeled off.

  From the above evaluation results, it was confirmed that the liquid crystal aligning agent of the present invention was excellent in printability, and the obtained liquid crystal alignment film had a large liquid crystal pretilt angle and excellent rubbing resistance. On the other hand, in the liquid crystal aligning agent of the comparative example, the liquid crystal alignment film obtained has a large pretilt angle of the liquid crystal, but is inferior in printability (Comparative Example 1) or has no problem in printability. It was confirmed that the pretilt angle of the liquid crystal was small (Comparative Example 3).

The liquid-crystal aligning agent of this invention contains the polyimide with a high imidation rate, and can form the liquid-crystal aligning film which the damage | wound and peeling of a film | membrane do not occur easily at the time of a rubbing process. Moreover, the liquid crystal display element produced using the liquid-crystal aligning agent of this invention is suitable for a TN liquid crystal display element, an STN liquid crystal display element, a TFT liquid crystal display element, an OCB liquid crystal display element, etc. as a reliable liquid crystal display device. Used for.

It should be noted that Japanese Patent Application No. 2006-317529 filed on November 24, 2006 and Japanese Patent Application No. 2006-322397 filed on November 29, 2006, claims, and abstracts The entire contents are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims (11)

The liquid crystal aligning agent characterized by containing the following polyimide (A) and the following polyimide (B).
Polyimide (A):
(I) an amine component comprising a diamine represented by formula (1), or (ii) a diamine represented by formula (1), formula (2), formula (3), formula (4), and formula ( 5) A polyimide obtained by imidizing a polyamic acid obtained by reacting a diamine component consisting of at least one diamine selected from the group consisting of 5) and a tetracarboxylic dianhydride component.
Polyimide (B):
(Iii) A diamine component composed of a diamine represented by formula (1) and a diamine represented by formula (6), or (iv) a diamine represented by formula (1) and a formula (6) A diamine component, and at least one diamine selected from the group consisting of Formula (2), Formula (3), Formula (4), and Formula (5), and a tetracarboxylic dianhydride Polyimide obtained by imidizing polyamic acid obtained by reacting components.

(In formula (2), X ₁ represents a single bond or a linking group selected from the group consisting of ethers, esters, and amides, and X ₂ represents a linear alkyl group having 1 to 12 carbon atoms. In the formula (3), n is 1 or 2. In the formula (5), X ₃ is a single bond or a group consisting of —O—, —CH ₂ —, —NH—, and —CONH—. Represents a selected bonding group, and R is a hydrogen atom or a methyl group.)

(In formula (6), X ₄ represents a single bond or a linking group selected from the group consisting of ether, ester, methylene ether and amide, and X ₅ is a linear alkyl group having 14 to 20 carbon atoms. Or a monovalent organic group represented by the following formula (7).)

(In the formula (7), _{X 6} is phenyl or cyclohexyl, _{X 7} is a cyclohexyl group having a linear alkyl group having 1 to 12 carbon atoms.)   The liquid-crystal aligning agent of Claim 1 which contains a polyimide (A) and a polyimide (B) by mass ratio of 50: 50-90: 10.   The liquid-crystal aligning agent of Claim 1 or 2 whose both imidation ratios in a polyimide (A) and a polyimide (B) are 40% or more.   The diamine represented by the formula (1) is contained in an amount of 20 to 100 mol% and the diamine content of the formula (1) is less than 100 mol% with respect to 100 mol% of the total diamine in the polyimide (A). In some cases, the remaining diamine is at least one diamine selected from the group consisting of Formula (2), Formula (3), Formula (4), and Formula (5). The liquid crystal aligning agent according to claim 1.   20 to 90 mol% of the diamine represented by the formula (1) and 5 to 40 mol% of the diamine represented by the formula (6) with respect to 100 mol% of the total diamine amount in the polyimide (B), And when the sum total content of the diamine of Formula (1) and the diamine of Formula (6) is less than 100 mol%, the remaining diamine is Formula (2), Formula (3), Formula (4), and Formula. The liquid-crystal aligning agent as described in any one of Claims 1-4 which is at least 1 sort (s) chosen from the group which consists of (5).   Furthermore, the liquid-crystal aligning agent as described in any one of Claims 1-5 containing an organic-solvent component.   The liquid-crystal aligning agent of Claim 6 containing (gamma) -butyrolactone, a butyl cellosolve, and a dipropylene glycol monomethyl ether or diethylene glycol diethyl ether as an organic-solvent component.   The liquid crystal aligning agent according to any one of claims 1 to 7, wherein the liquid crystal aligning agent is for a liquid crystal alignment film to be rubbed.   The liquid crystal aligning film obtained using the liquid-crystal aligning agent as described in any one of Claims 1-8.   The liquid crystal aligning film obtained by apply | coating and baking the liquid-crystal aligning agent as described in any one of Claims 1-8 on a board | substrate with an electrode, and carrying out a rubbing process.   The liquid crystal display element which has a liquid crystal aligning film of Claim 9 or 10.