TWI541269B - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

The present invention relates to a liquid crystal alignment agent containing polyamic acid or a derivative thereof and use thereof.

The liquid crystal display element is used for a view finder or a projection display such as a video camera represented by a notebook personal computer or a desktop personal computer. Liquid crystal display devices have recently also been used in televisions. Moreover, the liquid crystal display element is also used as an optoelectronics related element such as an optical printer head, an optical Fourier transform element, and a light valve.

The liquid crystal display device generally includes: 1) a pair of substrates disposed oppositely, 2) electrodes formed on one or both of the opposing faces of the pair of substrates, and 3) faces formed on the pair of substrates The liquid crystal alignment film and 4) a liquid crystal layer formed between the pair of substrates.

The mainstream of the conventional liquid crystal display elements is a display element using a nematic liquid crystal, 1) a twisted nematic (TN) liquid crystal display element which is twisted by 90 degrees, and 2) a super twisted nematic which is normally twisted by 180 degrees or more ( A so-called thin film transistor (TFT) liquid crystal display element using a thin film transistor for a switching element of a voltage of a liquid crystal is used in practical use. These liquid crystal display elements have disadvantages in that the angle of view of the image which can be correctly visually viewed is narrow, and when viewed from the oblique direction, a decrease in brightness or contrast and a brightness inversion in halftone are generated.

In recent years, the problem of this viewing angle is to use 1) a TN-TFT mode liquid crystal display element using an optical compensation film, 2) a vertical alignment (VA) mode liquid crystal display element using a vertical alignment and an optical compensation film, and 3 Multi-Field Vertical Alignment (MVA) mode liquid crystal display element using either vertical alignment and protrusion structure technology, or 4) In-Plane Switching (IPS) mode liquid crystal display Techniques such as components are improved to make each component practical.

The development of the technology of the liquid crystal display element is achieved not only by the improvement of these driving methods or element structures, but also by the improvement of the constituent members for the elements. Among the constituent members used for the liquid crystal display element, in particular, the liquid crystal alignment film is one of important materials related to display quality, and as the liquid crystal display element is made higher in quality, it is important to improve the performance of the alignment film.

The liquid crystal alignment film is prepared by using a liquid crystal alignment agent. At present, a liquid crystal alignment agent mainly used is a solution obtained by dissolving polylysine or a soluble polyimide in an organic solvent. After such a solution is applied onto a substrate, a film is formed by heating or the like to form an alignment film. Liquid crystal alignment agents using polymers other than polyaminic acid have also been studied, and have heat resistance, chemical resistance (liquid crystal resistance), coating properties, liquid crystal alignment properties, electrical properties, optical properties, display properties, and the like. In fact, it has not been put to practical use.

Such an alignment film is required to have an effect on the liquid crystal display element as described below.

(1) A suitable pretilt angle is imparted to the liquid crystal molecules. Moreover, the pretilt angle is hardly affected by the crushing strength at the time of friction or the temperature condition at the time of heating.

(2) There is no defect that the alignment of the liquid crystal molecules is caused by unevenness in rubbing, scratching, or removal of the alignment film.

(3) An appropriate voltage holding ratio (VHR) is applied to the liquid crystal display element.

(4) When the liquid crystal display element displays an arbitrary image for a long period of time and changes to another image, it is difficult to cause a phenomenon in which the previous image remains as an afterimage, which is called "burning".

The liquid crystal display element using the VA mode or the IPS mode is used for most of the liquid crystal TV developed in recent years because of good viewing angle characteristics as described above. In the case of comparing the performances of the two modes, the length and the length caused by the driving principle exist separately. For example, in the case of the IPS mode, there is an advantage that the viewing angle characteristics are particularly good, and the response speed in halftones is relatively fast. However, the contrast is worse than the VA mode. The IPS mode displays black when no voltage is applied, and this state depends on the initial alignment state of the liquid crystal accompanying the friction, which is one of the causes of deterioration of contrast. That is, in the IPS alignment film, it is strongly required that the liquid crystal alignment property is high, and the black display can display the alignment film (black level is good). An example of the prior art for the purpose of solving the above problems is exemplified by Patent Document 1, which is characterized in that a diamine having a triple bond at its end is used.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-300940

An object of the present invention is to develop a liquid crystal alignment agent for obtaining a liquid crystal alignment film having high liquid crystal alignment property and good black level.

The present inventors have found that a liquid crystal display element having improved characteristics described above can be obtained by using a liquid crystal alignment agent containing a polylysine having a specific structure or a derivative thereof, thereby completing the present invention. That is, the liquid crystal alignment agent of the present invention is shown in the following item [1].

[1] A liquid crystal alignment agent comprising a polyglycine which is obtained by reacting a mixture of a tetracarboxylic dianhydride represented by the formula (I) with another tetracarboxylic dianhydride and a diamine, and a derivative thereof The composition of at least one of the polymers, and the ratio of the tetracarboxylic dianhydride represented by the formula (I) is 5 mol% (mol%) based on the total amount of the mixture of the tetracarboxylic dianhydrides - 95 mol%, the ratio of other tetracarboxylic dianhydride is 5 mol% to 95 mol%:

Wherein X is an alkylene having 2 to 12 carbon atoms.

Further, an example in which a polyphthalic acid obtained by using a tetracarboxylic dianhydride of the formula (I) is used in a liquid crystal alignment agent is disclosed in Japanese Laid-Open Patent Publication No. 2001-131285. However, in this prior document, a specific example of a mixture of a tetracarboxylic dianhydride of the formula (I) and another tetracarboxylic dianhydride is not used, and there is no description about the improvement of the black level. Further, examples of the diamine to be reacted are also limited.

[Effects of the Invention]

According to the present invention, a liquid crystal alignment agent having good alignment property can be obtained. Especially effective for the improvement of the black level associated with the IPS mode.

First, the terms used in the present invention will be described. The tetracarboxylic dianhydride may be abbreviated as an acid anhydride. Therefore, the tetracarboxylic dianhydride represented by the formula (I) may be simply referred to as an acid anhydride (I). The tetracarboxylic dianhydride represented by other chemical formulas is sometimes referred to by the same shorthand. The diamine represented by the formula (2) is sometimes referred to as a diamine (2). The diamines represented by other chemical formulas are sometimes also referred to by the same shorthand.

The term "arbitrary" used in the definition of a chemical formula means "not only the position but also the quantity can be freely selected." For example, the expression "arbitrary A may be substituted by B, C, D or E", except that one A may be substituted by B, C, D or E, any one of the plurality A may pass B, C In addition to the meaning of any one of D and E, at least two of A substituted by B, A substituted by C, A substituted by D, and A substituted by E may be mixed. Wherein, when any -CH ₂ - may be substituted by another group, the case where a plurality of consecutive -CH ₂ - groups are substituted by the same group is not included.

The substituent which is not explicitly bonded to any one of the carbons constituting the ring is free in the range in which the bonding position is chemically problem-free.

The case where the same mark is used in a plurality of chemical formulas means that the groups have the same definition range, but does not mean that they must be the same group at the same time in all chemical formulas. In this case, the same group may be selected among a plurality of chemical formulas, or different groups may be selected among the respective chemical formulas. In this case, when a plurality of identical symbols are used in one chemical formula, the plurality of groups may be different from the groups in the other chemical formulas, or may be different only in part.

Me in the chemical formula means a methyl group.

The present invention is composed of the above item [1] and the following items [2] to [12].

[2] The liquid crystal alignment agent according to [1], wherein the other tetracarboxylic dianhydride is at least one of tetracarboxylic dianhydride represented by formula (A-1) to formula (A-46), The amine is at least one diamine selected from the group consisting of diamines represented by formula (1-1) to formula (1-3), formula (2), formula (3) and formula (4):

In the formula (1-1), b is 0 or 1; any hydrogen in the cyclohexylene may be substituted by a methyl group; in the formula (1-2), W ¹ is -CH ₂ - or -NH-:

Wherein X ¹ is a single bond or an alkylene group having 1 to 10 carbon atoms; any -CH ₂ - of the alkylene group may be -O-, -S-, -NH-, -N(CH ₃ )- , -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CO-, -SO ₂ -, 1,3-phenylene, 1,4-phenylene Or substituted with piperazine-1,4-diyl;

In the formula (3), X ² is a single bond, -O-, -COO-, -OCO- or an alkylene group having 1 to 6 carbon atoms; R ¹ is an alkyl group having 3 to 30 carbon atoms, or a formula (a) In the formula (a), X ³ and X ^{4 are} independently a single bond or an alkylene group having 1 to 4 carbon atoms; and ring B and ring C are independently a 1,4-phenylene group or 1 , 4-cyclohexylene; R ² and R ^{3 are} independently fluorine or methyl, and f and g are independently 0, 1 or 2; c, d and e are independently 0 or 1, and the total of these is 1 to 3; R ⁴ is an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, an alkoxyalkyl group having 2 to 30 carbon atoms or a cholesteryl group, and these alkyl groups, alkoxy groups and In the alkoxyalkyl group, any hydrogen can be substituted by fluorine:

Wherein X ^{5 is} independently -O- or an alkylene group having 1 to 6 carbon atoms; j is 0 or 1; R ⁵ is hydrogen, an alkyl group having 2 to 12 carbon atoms or an alkoxy group having 2 to 12 carbon atoms; The ring T is 1,4-phenylene or 1,4-cyclohexylene; X ⁶ is a single bond or a C 1-3 alkyl group; h is 0 or 1.

[3] The liquid crystal alignment agent according to [2], wherein the other tetracarboxylic dianhydride is of the formula (A-1) to the formula (A-4), the formula (A-11), and the formula (A-12) Formula (A-14), Formula (A-18) to Formula (A-21), Formula (A-28) to Formula (A-30), Formula (A-32), Formula (A-37), At least one of the tetracarboxylic anhydrides represented by the formulae (A-39) to (A-41) and (A-43) to (A-46), and the diamine is a formula (1-2-1). Formula (1-3), Formula (2-1) to Formula (2-3), Formula (2-7), Formula (2-10) to Formula (2-27), Formula (2-29), Formula (2-37) to formula (2-39), formula (2-41), formula (2-43) to formula (2-47), formula (2-51), formula (3-1) to formula ( 3-12) and at least one of the diamines represented by the formula (4-1) to the formula (4-12):

Wherein, R ²⁰ is an alkyl group having 5 to 16 carbon atoms, R ²¹ is alkyl of 3 to 10, R ²² is an alkyl group having 6 to 16 carbon atoms or cholesterol group;

Wherein R ²⁶ is an alkyl group having 4 to 7 carbon atoms.

[4] The liquid crystal alignment agent according to [3], wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-2), the formula (A-12), and the formula (A-14) , formula (A-18), formula (A-20), formula (A-21), formula (A-28), formula (A-30), formula (A-37), formula (A-40) and At least one of the tetracarboxylic anhydrides represented by the formula (A-45), the diamine is a formula (1-2-1), a formula (1-3), a formula (2-7), and a formula (2-10). Formula (2-12), Formula (2-16) to Formula (2-19), Formula (2-21) to Formula (2-27), Formula (2-37) to Formula (2-39), Formula (2-41), Formula (2-43) to Formula (2-47), Formula (2-51), Formula (3-1) to Formula (3-12), and Formula (4-1) to Formula ( 4-12) At least one of the diamines represented.

[5] The liquid crystal alignment agent according to [4], wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-12), the formula (A-14), and the formula (A-18) And at least one of the tetracarboxylic anhydrides represented by the formula (A-45), wherein the diamine is a formula (1-2-1), a formula (1-3), a formula (2-7), and a formula (2-10) At least one of the diamines represented by the formula (2-12), the formula (2-26), the formula (2-44), the formula (2-45), and the formula (3-1) to the formula (3-6) One.

[6] The liquid crystal alignment agent according to [3], wherein the other tetracarboxylic dianhydride is of the formula (A-14), the formula (A-18), the formula (A-19), and the formula (A-20) , formula (A-21), formula (A-28), formula (A-29), formula (A-30), formula (A-32), formula (A-39), formula (A-40), At least one of the tetracarboxylic anhydrides represented by the formula (A-41), the formula (A-43), the formula (A-44) and the formula (A-46), and the diamine is a formula (1-2-1), Formula (1-3), Formula (2-1) to Formula (2-3), Formula (2-26), Formula (2-29), Formula (2-37), Formula (2-43) to Formula (2-47), at least one of the diamines represented by the formula (3-1) to the formula (3-12) and the formula (4-1) to the formula (4-12).

[7] The liquid crystal alignment agent according to [6], wherein the other tetracarboxylic dianhydride is a formula (A-14), a formula (A-20), a formula (A-21), and a formula (A-39). At least one of the tetracarboxylic anhydrides represented by the formula (A-44) and the formula (A-46), and the diamine is a formula (1-2-1), a formula (1-3), and a formula (2-1) At least one of the diamines represented by the formula (2-3), the formula (2-26), the formula (2-29), the formula (2-44), and the formula (3-1) to the formula (3-6) One.

[8] The liquid crystal alignment agent according to [3], wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-2), the formula (A-3), and the formula (A-4) At least one of the tetracarboxylic anhydrides represented by the formula (A-11), the formula (A-12) and the formula (A-45), and the diamine is a formula (1-2-1) or a formula (1-3) Formula (2-1) to Formula (2-3), Formula (2-13) to Formula (2-15), Formula (2-20) to Formula (2-26), Formula (2-29), At least one of the diamines represented by the formula (2-39) and the formula (2-41).

[9] The liquid crystal alignment agent according to [8], wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-2), the formula (A-4), and the formula (A-12) And at least one of the tetracarboxylic anhydrides represented by the formula (A-45), wherein the diamine is a formula (1-2-1), a formula (1-3), and a formula (2-1) to a formula (2-3) At least one of the diamines represented by the formula (2-13) to the formula (2-15), the formula (2-26), and the formula (2-29).

[10] The liquid crystal alignment agent according to any one of [1] to [9], further comprising another polyamic acid selected from the group consisting of not using the tetracarboxylic dianhydride represented by the formula (I) At least one polymer of its derivatives.

[11] A liquid crystal alignment film which is formed by heating a coating film of the liquid crystal alignment agent according to any one of [1] to [10].

[12] A liquid crystal display element comprising: a pair of substrates; a liquid crystal layer formed between the substrates; an electrode for applying a voltage to the liquid crystal layer; and a liquid crystal alignment film according to [11].

The liquid crystal alignment agent of the present invention is a composition containing at least one polymer selected from the group consisting of polylysine and a derivative thereof, and a solvent. Examples of the polyproline derivative include a polyimine obtained by subjecting polylysine to a complete dehydration ring-closure reaction, and a partial ruthenium polyamine obtained by partially performing a dehydration ring-closure reaction of polyglycine. An acid, a polyphthalate, a polyphthalic acid-polyamine copolymer obtained by substituting a part of a tetracarboxylic dianhydride with a dicarboxylic acid, and a polyglycolic acid-polyamine copolymer A polyamidoquinone imine obtained by subjecting a part or all of the dehydration ring closure reaction. Among these derivatives of polylysine, polyimide and partially ruthenium polyamine are preferred, and polyimine is more preferred.

In the present invention, at least one polymer selected from the group consisting of polylysine obtained by reacting a mixture of an acid anhydride (I) with another acid anhydride and a diamine and a derivative thereof is used.

X in the formula (I) is an alkylene group having 2 to 12 carbon atoms. The alkylene group is a linear alkyl group and has a carbon number of 5 to 12, and is preferred because it imparts a large liquid crystal alignment property to the alignment film.

The polymer may be used singly or in combination of at least two kinds of the above polylysines having different starting materials, or the polylysine may be used in combination with a derivative thereof. Further, as described below, at least one selected from the group consisting of polylysine and a derivative thereof, at least one selected from the group consisting of other polyamines obtained by using no acid anhydride (I), and derivatives thereof may be used. The polymer is used in combination. In addition, in the following description except the example, the "polylysine" which is used without a comment has the general term of the poly lysine and its derivative which are obtained by reacting the mixture of the acid anhydride (I) and other acid anhydride, and a diamine. The meaning.

The other acid anhydride used in combination with the acid anhydride (I) can be selected from known acid anhydrides without limitation, and preferred examples thereof include the acid anhydrides (A-1) to (A-46) shown below. It is preferred to use at least one of these acid anhydrides.

Further, among the above acid anhydrides, the acid anhydrides (A-1) to (A-4), acid anhydrides (A-11), acid anhydrides (A-12), and acid anhydrides (A-14) shown below are more preferred. Anhydride (A-18) to acid anhydride (A-21), acid anhydride (A-28) to acid anhydride (A-30), acid anhydride (A-32), acid anhydride (A-37), acid anhydride (A-39)~ Anhydride (A-41) and anhydride (A-43) to anhydride (A-46).

In the case of further improving the alignment of the liquid crystal, among the above other acid anhydrides, the acid anhydride (A-1), the acid anhydride (A-2), the acid anhydride (A-12), the acid anhydride (A-14), and the acid anhydride (A) are more preferable. -18), acid anhydride (A-20), acid anhydride (A-21), acid anhydride (A-28), acid anhydride (A-30), acid anhydride (A-37), acid anhydride (A-40), and acid anhydride (A- 45), particularly preferred are an acid anhydride (A-1), an acid anhydride (A-12), an acid anhydride (A-14), an acid anhydride (A-18), and an acid anhydride (A-45).

In order to increase the VHR of the liquid crystal display element, among the above other acid anhydrides, an acid anhydride (A-14), an acid anhydride (A-18), an acid anhydride (A-19), an acid anhydride (A-20), and an acid anhydride (A) are more preferable. -21), acid anhydride (A-28), acid anhydride (A-29), acid anhydride (A-30), acid anhydride (A-32), acid anhydride (A-39), acid anhydride (A-40), acid anhydride (A- 41) an alicyclic compound of an acid anhydride (A-43), an acid anhydride (A-44) and an acid anhydride (A-46), particularly preferably an acid anhydride (A-14), an acid anhydride (A-20), an acid anhydride (A- 21), anhydride (A-39), an acid anhydride (A-44), and an acid anhydride (A-46).

By lowering the volume resistance value of the liquid crystal alignment film, the relaxation rate of residual electric charge (residual DC) in the alignment film is improved, which is effective as one of methods for preventing baking. In view of the above, in the above other acid anhydrides, the acid anhydride (A-1), the acid anhydride (A-2), the acid anhydride (A-3), the acid anhydride (A-4), and the acid anhydride (A-11) are more preferable. Anhydride (A-12) and anhydride (A-45), particularly preferably anhydride (A-1), anhydride (A-2), anhydride (A-4), anhydride (A-12) and anhydride (A-45) ). The acid anhydride is not limited to these acid anhydrides, and other known compounds can be used within the scope of achieving the object of the present invention.

The mixing ratio of these acid anhydrides in the mixture of the acid anhydride (I) and other acid anhydrides is based on the total amount of the mixture, the acid anhydride (I) is 5 mol% to 95 mol%, and the other acid anhydride is 5 mol% to 95. Mol%. The mixing ratio is preferably from 15 mol% to 85 mol% of the acid anhydride (I) and from 15 mol% to 85 mol% of the other acid anhydride.

The diamine used in the present invention can be selected from known diamines without limitation. Preferred diamines include diamines (1-1) to diamines (1-3) and diamines (2) shown below. ), diamine (3) and diamine (4). It is preferred to use at least one diamine selected from the group of these diamines.

In the formula (1-1), b is 0 or 1, and any hydrogen in the cyclohexyl group may be substituted with a methyl group.

In the formula (1-2), W ¹ is -CH ₂ - or -NH-.

Specific examples of these diamines are listed below.

In the formula (2), X ¹ is a single bond or an alkylene group having 1 to 10 carbon atoms, and any -CH ₂ - of the alkylene group may be -O-, -S-, -NH-, -N ( CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CO-, -SO ₂ -, 1,3-phenylene, 1,4-phenylene or pyridazine -1,4-diyl substituted. A preferred example of X ¹ is an alkylene group having 1 to 10 carbon atoms. In this case, any -CH ₂ - of the alkyl group may be subjected to -O-, -S-, -NH-, -C(CH ₃ ). ₂ -, 1,4-phenylene or 1,4-piperazinyl group is substituted. Further, any hydrogen of the benzene ring to which the amino group is bonded may be substituted with a methyl group, but is preferably not substituted with a methyl group.

Specific examples of the diamine (2) are listed below.

In the formula (3), X ² is a single bond, -O-, -COO-, -OCO- or an alkylene group having 1 to 6 carbon atoms, preferably a single bond, -O-, -COO- or a carbon number. 1 to 3 alkyl groups. R ¹ is an alkyl group having 3 to 30 carbon atoms or a group represented by the formula (a), and is preferably an alkyl group having 4 to 20 carbon atoms or a group represented by the formula (a).

In the formula (a), X ³ and X ^{4 are} independently a single bond or an alkylene group having 1 to 4 carbon atoms, preferably a single bond, -CH ₂ - or -CH ₂ CH ₂ -. Ring B and Ring C are independently 1,4-phenylene or 1,4-cyclohexylene. R ² and R ^{3 are} independently fluorine or methyl, and f and g are independently 0, 1, or 2, and it is preferred that both f and g are 0. c, d and e are independently 0 or 1, and the total of these is 1 to 3. R ⁴ is an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, an alkoxyalkyl group having 2 to 30 carbon atoms or a cholesteryl group, and these alkyl groups, alkoxy groups and alkoxyalkyl groups Any hydrogen may be substituted by fluorine. Preferred examples of R ⁴ are an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyl group having 2 to 20 carbon atoms, and a cholesteryl group, and these alkyl groups, alkoxy groups and alkane The hydrogen in the oxyalkyl group is not substituted by fluorine.

Preferred examples of the diamine (3) are listed below.

In the formula (3-1) to the formula (3-25), R ²⁰ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably an alkyl group having 5 to 16 carbon atoms. R ²¹ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably an alkyl group having 3 to 10 carbon atoms. R ²² is an alkyl group having 4 to 20 carbon atoms or a cholesteryl group, preferably an alkyl group having 6 to 16 carbon atoms or a cholesteryl group. R ²³ is an alkyl group having 4 to 20 carbon atoms, preferably an alkyl group having 6 to 16 carbon atoms. R ²⁴ is an alkyl group having 3 to 20 carbon atoms or an alkoxy group having 3 to 20 carbon atoms, preferably an alkyl group having 5 to 12 carbon atoms.

In the formula (4), X ^{5 is} independently -O- or an alkylene group having 1 to 6 carbon atoms, preferably -O-, -CH ₂ - or -CH ₂ CH ₂ -. j is 0 or 1. R ⁵ is hydrogen, an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably hydrogen, an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms, more preferably It is an alkyl group having 4 to 7 carbon atoms. Ring T is 1,4-phenylene or 1,4-cyclohexylene. X ⁶ is a single bond or an alkylene group having 1 to 3 carbon atoms. Moreover, h is 0 or 1. Further, the bonding position of the amino-p-phenyl ring is preferably para-position with respect to X ⁵ .

Preferred examples of the diamine (4) are listed below.

In the formulae (4-1) to (4-16), R ²⁶ is hydrogen, an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms, preferably an alkyl group having 4 to 7 carbon atoms. .

In the specific example of the above diamine, the diamine (1-2-1), the diamine (1-3), the diamine (2-1) to the diamine (2-3), and the following are more preferable. Amine (2-7), diamine (2-10) to diamine (2-27), diamine (2-29), diamine (2-37) to diamine (2-39), diamine ( 2-41), diamine (2-43) to diamine (2-47), diamine (2-51), diamine (3-1) to diamine (3-12), and diamine (4) -1) to diamine (4-12).

Here, R ²⁰ is an alkyl group having 5 to 16 carbon atoms, R ²¹ is an alkyl group having 3 to 10 carbon atoms, and R ²² is an alkyl group having 6 to 16 carbon atoms or a cholesteryl group.

Wherein R ²⁶ is an alkyl group having 4 to 7 carbon atoms.

In the specific example of the above-mentioned more preferable diamine, in order to further improve the alignment property of the liquid crystal, it is more preferred to be a diamine (1-2-1), a diamine (1-3), or a diamine (2-7). , diamine (2-10) to diamine (2-12), diamine (2-16) to diamine (2-19), diamine (2-21) to diamine (2-27), Amine (2-37) to diamine (2-39), diamine (2-41), diamine (2-43) to diamine (2-47), diamine (2-51), diamine ( 3-1) to diamine (3-11), and diamine (4-1) to diamine (4-12), particularly preferably diamine (1-2-1), diamine (1-3) , diamine (2-7), diamine (2-10) to diamine (2-12), diamine (2-26), diamine (2-44), diamine (2-45), and Diamine (3-1) to diamine (3-6).

In the specific example of the above-described preferred diamine, it is preferable to impart a high VHR to the liquid crystal alignment film, and more preferably a diamine (1-2-1), a diamine (1-3), or a diamine (2-1). ~Diamine (2-3), diamine (2-26), diamine (2-29), diamine (2-37), diamine (2-43) to diamine (2-47), two Amine (3-1) to diamine (3-11), and diamine (4-1) to diamine (4-12), particularly preferably diamine (2-1) to diamine (2-3) , diamine (2-26), diamine (2-29), diamine (2-44), and diamine (3-1) to diamine (3-6).

In the specific example of the above-described preferred diamine, it is more preferable to reduce the volume resistivity of the liquid crystal alignment film, preferably diamine (1-2-1), diamine (1-3), and diamine (2- 1) to diamine (2-3), diamine (2-13) to diamine (2-15), diamine (2-20) to diamine (2-26), diamine (2-29) , diamine (2-39) and diamine (2-41), particularly preferably diamine (2-1) to diamine (2-3), diamine (2-13) to diamine (2-15) ), diamine (2-26) and diamine (2-29).

However, diamines can be classified into two types depending on their structures. That is, when the skeleton linking two amino groups is regarded as a main chain, the diamine is a diamine having a side chain group which is a branch of an autonomous chain, and a diamine having no side chain group. By reacting a diamine having a side chain group with a tetracarboxylic dianhydride, a polylysine having a plurality of side chain groups to the main chain of the polymer is obtained. When such a polyamic acid having a side chain group to the polymer main chain is used, the liquid crystal alignment film formed of the liquid crystal alignment agent containing the polymer can increase the pretilt angle of the liquid crystal display element. That is, the side chain group is a group having an effect of increasing the pretilt angle. The side chain group having such an effect must be a group having 3 or more carbon atoms, and specific examples thereof include an alkyl group having 3 or more carbon atoms, an alkoxy group having 3 or more carbon atoms, and an alkoxyalkyl group having 3 or more carbon atoms. Base. A group having one or more rings and having a terminal having a carbon number of 1 or more, an alkoxy group having 1 or more carbon atoms, and an alkoxyalkyl group having 2 or more carbon atoms as a substituent It has an effect as a side chain group. When a diamine having such a side chain group is used as a side chain type diamine, and a diamine having no such side chain group is used as a non-side chain type diamine, the above diamine (3) and diamine (4) The side chain type diamine, the diamine (1-1) to the diamine (1-3), and the diamine (2) are non-side chain type diamines.

Further, by appropriately separating the side chain type diamine from the non-side chain type diamine, it is possible to correspond to the pretilt angle necessary for each of the display elements. That is, a relatively large pretilt angle is required in the longitudinal electric field method represented by the TN mode or the VA mode, and therefore a side chain type diamine is mainly used. At this time, in order to further control the pretilt angle, a non-side chain type diamine can be used at the same time. The blending ratio of the non-side chain type diamine and the side chain type diamine may be determined according to the target pretilt angle. Of course, it is also possible to use only a side chain type diamine by appropriately selecting a side chain group. In the transverse electric field mode, since the pretilt angle is small and high liquid crystal alignment is required, at least one of non-side chain type diamines can be used.

In the present invention, in particular, in order to exhibit a pretilt angle of 2 or more, it is preferred to use the ratio of the side chain type diamine to 5 mol% to 70 mol%, more preferably 10 mol% to 50 in the total amount of the diamine. Mol%.

The polyphthalic acid used in the liquid crystal alignment agent of the present invention is obtained by reacting a mixture of the above acid anhydrides and a diamine in a solvent. In addition to the selection of the raw materials in the synthesis reaction, no special conditions are required, and the conditions in the usual polyaminic acid synthesis can be directly applied. The solvent used is as described later.

In the liquid crystal alignment agent of the present invention, at least one of siloxane-based diamines may be used in combination in order to prevent the removal by friction. A preferred example of the a halogenated alkane diamine is a diamine represented by the formula (15).

Wherein R ³⁰ and R ^{31 are} independently an alkyl group having 1 to 3 carbon atoms or a phenyl group; and R ³² is an alkylene group having 1 to 6 carbon atoms, a phenyl group or a phenyl group substituted by an alkyl group, and y is An integer from 1 to 10.

Specific examples of the diamine (15) include the following compounds or polymers.

(The molecular weight of the polymer of the formula (15-2) is 850 to 3,000.)

When these decane-based diamines are used, the amount thereof is preferably from 0.5 mol% to 30 mol%, more preferably from 1 mol% to 10 mol%, based on the total amount of the diamine used as a raw material.

The alignment agent of the present invention may further contain an organic ruthenium compound from the viewpoint of adjusting the adhesion of the alignment film to the glass substrate. Examples of the organic ruthenium compound are: amino propyl trimethoxysilane, amino propyl triethoxysilane, vinyl trimethoxysilane, N-(2- N-(2-aminoethyl)-3-amino propyl methyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethyl N-(2-aminoethyl)-3-amino propyl trimethoxysilane, vinyl triethoxysilane, 3-methacryloxy propyl Trimethoxysilane), 3-glycidoxy propyl trimethoxysilane, 3-glycidoxy propyl methyl dimethoxysilane, 2-( a silane coupling agent such as 2-(3,4-epoxy cyclohexyl)ethyl trimethoxysilane, and dimethyl polyoxane (dimethyl) Polysiloxane), polydimethyl siloxane, poly Silicon phenyl siloxane (polydiphenyl siloxane), silicone oil and the like (silicone oil).

The addition ratio of the organic ruthenium compound to the alignment agent is not particularly limited as long as it is in the range in which the effects of the present invention are obtained, and it is preferable that the concentration of the organic ruthenium compound is relatively the weight of the polymer contained in the alignment agent. It is in the range of 0.01% by weight (wt%) to 5% by weight. When the concentration is 5 wt% or less, the possibility of occurrence of poor alignment of the liquid crystal due to the addition of the organic ruthenium compound may not be considered. The addition ratio is particularly preferably in the range of 0.1 wt% to 3 wt%.

The alignment agent of the present invention may further contain a compound having two or more functional groups reactive with a carboxyl group of poly-proline or a derivative thereof from the viewpoint of preventing degradation of characteristics over time or deterioration caused by environment. Crosslinker. Examples of such a crosslinking agent include a polyfunctional epoxy or isocyanate material described in, for example, Japanese Patent No. 3049699, Japanese Patent Laid-Open No. Hei. No. Hei. No. Hei. No. Hei. Wait.

Further, a polymer which reacts with the crosslinking agent itself to form a network structure, such as a crosslinking agent which enhances the film strength of polyglycolic acid or polyimine, can also be used for the same purpose as described above. The polyfunctional vinyl ether, maleimide, or diallyl described in JP-A-2004-341030, and the like. A bisallyl nadimide derivative or the like. When these crosslinking agents are used, a preferred ratio of these crosslinking agents is from 5 wt% to 100 wt%, more preferably from 10 wt% to 50 wt%, based on the total amount of the polymer components.

In the liquid crystal alignment agent of the present invention, at least one of polyamic acids is preferably used, and polylysine may be used in combination with other polyamic acid produced without using the acid anhydride (I). In the case of combining other polylysines, the mixing ratio is based on the total amount of the polymer, the polyglycine is 10 wt% to 95 wt%, and the other polyglycine is 5 wt% to 90 wt%, even if it is polyfluorene. A sufficient effect can be obtained even if the proportion of the amine acid is small. In the liquid crystal alignment agent of the present invention, a polymer other than polyamic acid obtained by a reaction of an acid anhydride and a diamine, such as a polyester or an epoxy resin, can be used at the same time. However, when such other polymers are used at the same time, the proportion of the polymer is preferably 30% by weight or less based on the total weight of the polymer.

The alignment agent of the present invention is a solution obtained by dissolving polylysine in a solvent. The solvent can be appropriately selected depending on the purpose of use, from the solvent used in the production or use of the known polylysine. These solvents are exemplified as follows.

Examples of the aprotic polar organic solvent include N-methyl-2-pyrrolidone (NMP), dimethyl imidazolidinone, and N-methyl caprolactam. (N-methyl caprolactam), N-methyl propionamide, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethyl formamide (DMF), N,N-diethyl formamide, N,N-diethylacetamide (N, N-diethyl acetamide, DMAc), and lactones such as γ-butyrolactone (GBL).

Preferable examples of the solvent for the purpose of improving the coating property and the like other than the above-mentioned solvent include alkyl lactate and 3-methyl-3-methoxybutanol (3-methyl-3-methoxy). Butanol), tetralin, isophorone, ethylene glycol monoalkyl ether (eg ethylene glycol monobutyl ether (BCS)), diethylene glycol monoalkane Ether (eg diethylene glycol monoethyl ether), ethylene glycol monophenyl ether, triethylene glycol monoalkyl ether, propylene glycol monoalkyl ether (eg propylene glycol monobutyl ether), dialkyl malonate Ester (for example: diethyl malonate, dipropylene glycol monoalkyl ether (for example: dipropylene glycol monomethyl ether), and ester compounds of these glycol monoethers. Among these solvents, NMP is particularly preferred. , dimethyl imidazolidinone, GBL, BCS, diethylene glycol monoethyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether.

The alignment agent of the present invention may further contain various additives as needed. For example, when it is desired to further improve the coatability, an appropriate amount of the surfactant suitable for the purpose may be contained, and when it is necessary to further improve the antistatic property, an appropriate amount of the antistatic agent may be contained.

The concentration of the polymer in the alignment agent of the present invention is preferably from 0.1% by weight to 40% by weight, more preferably from 1% by weight to 10% by weight. When the alignment agent is applied to the substrate, it is necessary to adjust the film thickness, and the concentration of the polymer to be contained can be adjusted by diluting with a solvent in advance.

The alignment film of the present invention is obtained by applying the above-mentioned alignment agent onto a substrate by the method described below, optionally removing the solvent at a relatively low temperature (prepared for calcination); and then, in order to further promote The solvent is removed to increase the ruthenium iodide ratio of the poly-proline to exhibit the original characteristics of the alignment film, and to heat at a relatively high temperature (formally calcined). For the film obtained in the above manner, a rubbing treatment can be carried out as needed.

The liquid crystal display device of the present invention includes: a pair of substrates disposed oppositely, an electrode formed on one or both surfaces of the pair of substrates facing each other, and the present invention formed on a surface on which the pair of substrates face each other a liquid crystal alignment film and a liquid crystal layer formed between the pair of substrates.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such an electrode include, for example, indium tin oxide (ITO) or a vapor deposited film of a metal. In addition, the electrodes may be formed on the entire surface of one of the faces of the substrate, for example, may be formed into a desired shape that is patterned. The above-mentioned desired shape of the electrode may, for example, be a comb type or a sawtooth structure or the like. The electrodes may be formed on one of the pair of substrates or may be formed on the two substrates. The form of formation of the electrode differs depending on the type of the liquid crystal display element. For example, in the case of an IPS type liquid crystal display element, an electrode is disposed on one of the pair of substrates, and in the case of another liquid crystal display element, the above one Electrodes are disposed on the two pieces of the substrate. The liquid crystal alignment film is formed on the substrate or the electrode.

The liquid crystal layer is formed by sandwiching a liquid crystal composition from the pair of substrates facing each other on a surface on which the liquid crystal alignment film is formed. When the liquid crystal layer is formed, a spacer or a resin sheet or the like may be inserted between the pair of substrates as needed to form a spacer at an appropriate interval. A known liquid crystal composition can be used without particular limitation in the liquid crystal composition.

When the alignment film of the present invention is used as a liquid crystal alignment film to form a liquid crystal display element, it is possible to improve characteristics of all known liquid crystal compositions. The alignment film of the present invention produced by the above method is particularly effective for improvement of alignment defects of a large-screen display which is difficult to perform rubbing treatment. This large-screen display uses TFT to drive control. In addition, the liquid crystal composition used in such a TFT-type liquid crystal display device is described in Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Laid-Open No. Hei 5-501735, and Japanese Patent Laid-Open No. Hei 9-255956 In the communique. Therefore, the alignment film of the present invention is preferably used in combination with the liquid crystal composition described in these publications.

The liquid crystal display element of the present invention is excellent in alignment properties such as high black level value when used for IPS. The value of this black level can be measured in the following manner. That is, the liquid crystal cell assembled in the rubbing direction in anti-parallel is placed on the stage of the microscope, and the polarizer and the analyzer are rotated to have a minimum brightness. The minimum brightness was measured using a photomultiplier tube (the magnification of the polarizing microscope was 100 times, the attachment was 10 times × the attachment was 10 times). The smaller the value of the brightness, the better the black level. With the above measurement system, the preferred minimum brightness is 1500 μV or less, more preferably 900 μV or less. In the present application, the value of the minimum brightness is used as the value of the black level.

The liquid crystal display element of the present invention is also excellent in electrical characteristics related to the reliability of the liquid crystal display element. Such electrical characteristics include voltage holding ratio and ion density. The voltage holding ratio (VHR) is a ratio at which a voltage applied to a liquid crystal display element is held in a liquid crystal display element during a frame period, and indicates a display characteristic of the liquid crystal display element. The liquid crystal display device of the present invention uses a rectangular wave of 5 V and a frequency of 30 Hz to have a voltage holding ratio of 97.0% or more measured at a temperature of 60 ° C, and a rectangular wave of 5 V and a frequency of 0.3 Hz is used at a temperature of 60 ° C. The voltage holding ratio measured below is preferably 85.0% or more, which is preferable from the viewpoint of preventing display failure.

The ion density is a transient current other than the driving of the liquid crystal generated when a voltage is applied to the liquid crystal display element, and indicates the concentration of the ionic impurities contained in the liquid crystal in the liquid crystal display element. The liquid crystal display element of the present invention preferably has an ion density of 300 pC or less from the viewpoint of preventing the burning of the liquid crystal display element.

The pretilt angle in the liquid crystal display element of the present invention can be, for example, a liquid crystal characteristic evaluation apparatus OMS-CA3 type manufactured by Central Seiki, and is described in Journal of Applied Physics, Vol. 48, No. 5, p. 1783-1792 (1977). The crystal rotation method is used for the measurement.

[Example]

Hereinafter, the present invention will be described by way of examples and comparative examples.

The evaluation method of the liquid crystal display element in the examples is as follows.

<Measurement of retardation, film thickness, and pretilt angle of alignment film>

It was determined using an ellipsometer spectrometer M-2000U (manufactured by J. A. Woollam Co. Inc.). In the case of this example, the retardation value of the film increases in proportion to the degree of alignment of the polymer backbone. That is, a film having a large retardation value has a large degree of alignment.

<voltage retention rate>

This was carried out by the method described in "Water Island, 14th LCD Symposium Prep (p. 1988)". The measurement was performed by applying a rectangular wave having a wave height of ±5 V to the liquid crystal cell. The measurement was carried out at 60 °C. This value is an index indicating how much the applied voltage remains after the frame period. If the value is 100%, it means that all the charges are held.

<Ion Measurement in Ion Liquid (Ion Density)>

The liquid crystal physical property measurement system 6254 manufactured by Toyo Technica Co., Ltd. was used for measurement according to the method described in Applied Physics, Vol. 65, No. 10, 1065 (1996). A triangular wave with a frequency of 0.01 Hz was used for measurement in a voltage range of ±10 V at a temperature of 60 ° C (the area of the electrode was 1 cm ² ). If the ion density is large, problems such as burning due to ionic impurities tend to occur. That is, the ion density is a physical property value which is an index for predicting the occurrence of burning.

<weight average molecular weight (Mw)>

The weight average molecular weight (Mw) of the polylysine in the liquid crystal alignment agent is a gel permeation chromatography (Gel Permeation Chromatography, GPC, manufactured by Shodex Co., Ltd., GF7MHQ), using DMF containing 0.6 wt% of phosphoric acid as an eluate, and a tube. The column temperature was 50 ° C and the measurement was carried out using polystyrene as a standard solution.

<viscosity>

It was measured at 25 ° C using a viscometer (manufactured by Toki Sangyo Co., Ltd., TV-22).

The compounds used in the examples and comparative examples are listed below.

Anhydride (I)

Anhydride (A-1): pyromellitic dianhydride (PMDA)

Anhydride (A-2): 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA)

Anhydride (A-12): 2,3,6,7-naphthalene tetracarboxylic dianhydride (NPDA)

Anhydride (A-14): 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA)

Anhydride (A-18): 1,2,3,4-butane tetracarboxylic dianhydride (BDA)

Anhydride (A-20): 1,2,4,5-cyclohexane tetracarboxylic dianhydride (CHDA)

Anhydride (A-30): Rikacid TDA-100 (New Japan Physical and Chemical Co., Ltd.)

Anhydride (A-45): ethylene diamine tetraacetic dianhydride (EDTAD)

The above acid anhydride is subjected to an acid anhydride treatment of a commercially available compound, followed by vacuum drying. The acetic anhydride treatment is carried out in the following manner. First, each compound was heated at 80 ° C for 2 hours using 10 times the amount of acetic anhydride and the same amount of toluene as needed. It was then cooled to room temperature and the precipitate was filtered.

Anhydride (A-21): 2,3,5-tricarboxycyclopentyl acetic dianhydride (TCMP)

Anhydride (A-44): 2,4,6,8-tetracarboxy-bicyclo[3.3.0]octane dianhydride (2,4,6,8-tetracarboxy-bicyclo[3.3.0]octane dianhydride, BODA)

The above acid anhydrides are synthesized in accordance with JP-A-58-109479, J. Am. Chem. Soc., Vol. 82, 6342 (1960), respectively.

Diamine (2-1): 4,4'-diamino diphenyl methane (DDM)

Diamine (2-7): 1,2-bis(4-aminophenyl)ethane (DD2)

The above diamine is a commercially available compound used directly in the experiment.

Diamine (2-11): 1,4-bis(4-aminophenyl)butane (1,4-bis(4-aminophenyl)butane, DD4)

Diamine (2-26): N,N'-dimethyl-N,N'-bis(4-aminophenyl)ethylenediamine (N,N'-dimethyl-N,N'-bis(4- Aminophenyl)ethylene diamine,MPED)

Diamine (2-29): 1,4-bis(4-aminophenyl)piperazine (APPD)

Diamine (2-44): 1,3-bis(4-(4-aminophenylmethyl)phenyl)propane (APMPP)

The above diamines are respectively based on J. Appl. Polym. Sci., Vol. 8, No. 1, 533 (1964), J. Polym. Sci., Part A, Polym. Chem., Vol. 30, No. 6, It is synthesized by the method described in Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei.

Diamine (3-5-1): R ²¹ = pentyl

Diamine (4-6-1): R ²⁶ = heptyl

Diamine (4-9-1): R ²⁶ = propyl

The above-mentioned diamine is synthesized by referring to the method described in JP-A-2004-341030, EP601813, and JP-A-2002-210328, and the compound represented by the formula (N) (hereinafter referred to as a short form). The compound (N) is synthesized by the method described in JP-A-2002-162630.

In addition, the preparation of the polymer was carried out entirely in a stream of nitrogen.

[Synthesis Example 1]

<Preparation of polyamic acid varnish A>

DDM (2.2611 g, 11.405 mmol) was dissolved in NMP (22.5 g), anhydride (I-1) (0.9988 g, 2.851 mmol), PMDA (0.6219 g, 2.851 mmol), and CBDA (1.1183 g, 5.702 mmol) ) Add while keeping it below room temperature. After stirring for 2 hours, NMP (10.0 g) and BC (12.5 g) were added. The viscosity of the solution is 83mPa. s. The solution was stirred at 70 ° C for about 4 hours to obtain a viscosity of 34 mPa. s varnish A. The polyamido acid of the varnish had a weight average molecular weight of 52,000.

[Synthesis Example 2 to Synthesis Example 23]

<Preparation of Polyamic Acid Varnish B~W>

Using the raw material compositions shown in Tables 1 and 2, polyamic acid varnishes B to W were prepared in the same manner as in Synthesis Example 1, and physical properties were measured in the same manner as in Synthesis Example 1. In addition, the percentage of moles is indicated in brackets.

[Example 1]

<Production of liquid crystal cell for black level measurement>

1.0 g of varnish A was weighed into a sample bottle, and a mixed solvent of NMP/BC = 1/1 (weight ratio) was added to become 1.67 g. Next, a polyglycine solution having a polymer concentration of about 3 wt% was dropped on a transparent glass substrate, and coating was carried out by a spinner method (2,000 rpm, 15 seconds). After coating, the substrate was heated at 80 ° C for 3 minutes to evaporate the solvent, followed by heat treatment at 230 ° C for 20 minutes in an oven. The polyimide film with a thickness of about 70 nm was rubbed (extrusion: 0.3 mm, platform feed rate: 60 m/s, rotation speed: 1000 rpm, rubbing cloth: YA-18-R (rayon) )). Then, the glass substrate on which the alignment film was formed was subjected to ultrasonic cleaning in ultrapure water for 5 minutes, and then dried in an oven at 120 ° C for 30 minutes.

The anti-parallel liquid crystal having a gap of 25 μm was formed by sealing the surface on which the alignment film was formed and facing each other so that the rubbing direction was anti-parallel, and then sealing with an epoxy curing agent containing a gap agent of 25 μm. Unit (antiparallel cell). Then, the liquid crystal composition A shown below was injected into the liquid crystal cell, and the injection port was sealed with a light hardener. Next, heat treatment was performed at 110 ° C for 30 minutes to prepare a liquid crystal display element. The black level of the liquid crystal cell was measured and found to be 1,250 μV.

<Preparation of pretilt angle and liquid crystal cell for measuring electrical characteristics>

A 7 μm interstitial agent was dispersed on one of the alignment films using the glass substrate on which the alignment film was formed in the same manner as described above. This was placed opposite to the other substrate so that the alignment film surface was inside and the rubbing direction was antiparallel, and then sealed with an epoxy curing agent to prepare an antiparallel liquid crystal cell having a gap of 7 μm. Then, the liquid crystal composition A was injected into the liquid crystal cell in the same manner as described above, and the injection port was sealed with a light hardener. Next, heat treatment was performed at 110 ° C for 30 minutes to prepare a liquid crystal display element. The VHR (30 Hz and 0.3 Hz) and ion density of the liquid crystal cell were measured and found to be 98.3%, 88.8%, and 157 pC.

<Liquid crystal composition A>

[Example 2 to Example 15]

A liquid crystal display element was obtained in the same manner as in Example 1 using varnish B to varnish O shown in Table 1. The values of the black level, VHR, and ion density at this time are shown in Table 3 together with the results of Example 1.

[Comparative Example 1]

A liquid crystal display element was produced in the same manner as in Example 1 except that varnish T was used instead of varnish A. The black level, VHR (30 Hz and 0.3 Hz) and ion density of the liquid crystal cell were measured and found to be 2,810 μV, 99.0%, 91.5%, and 46 pC.

[Comparative Example 2]

A liquid crystal display element was produced in the same manner as in Example 1 except that varnish U was used instead of varnish A. The black level, VHR (30 Hz and 0.3 Hz) and ion density of the liquid crystal cell were measured and found to be 2,130 μV, 95.0%, 79.8%, and 421 pC.

[Example 16]

A liquid crystal display element was produced in the same manner as in Example 1 except that varnish R was used instead of varnish A. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 5.8, 98.7%, 90.0%, and 101 pC. Further, the retardation of the glass substrate attached to the film before assembly of the liquid crystal cell was measured and found to be 0.23 nm.

[Example 17 to Example 19]

A liquid crystal display element was obtained in the same manner as in Example 1 using varnish S. Further, a liquid crystal display element was obtained in the same manner as in Example 1 using a mixture in which varnish R and varnish S were respectively added to the varnish T. The results of measuring the pretilt angle, VHR (30 Hz and 0.3 Hz) and ion density values for these liquid crystal display elements, and the retardation measurement values of the glass substrates attached to the film before assembly of the liquid crystal cell are shown in Table 4. In addition, the percentage of weight is indicated in brackets.

[Example 20]

A liquid crystal display element was produced in the same manner as in Example 16 except that the compound (N) was added to the varnish R in an amount of 20% by weight based on the polymer component. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 5.3°, 99.2%, 92.3%, and 63 pC. Further, the retardation of the glass substrate attached to the film before assembly of the liquid crystal cell was measured and found to be 0.17 nm.

[Example 21]

A liquid crystal display element was produced in the same manner as in Example 16 except that 3-aminopropyltrimethoxydecane was added to the varnish R in an amount of 3 wt% based on the polymer component. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 5.5, 99.0%, 91.2%, and 96 pC. Further, the retardation of the glass substrate attached to the film before assembly of the liquid crystal cell was measured and found to be 0.18 nm.

[Comparative Example 3]

A liquid crystal display element was produced in the same manner as in Example 16 except that varnish V was used instead of varnish R. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 6.0, 97.5%, 84.8%, and 248 pC. Further, the retardation value of the glass substrate attached to the film before the assembly of the liquid crystal cell was 0.13 nm.

[Example 23]

A liquid crystal display element was produced in the same manner as in Example 1 except that varnish P was used instead of varnish A. At this time, in place of the liquid crystal composition A, the following liquid crystal composition B was sealed in the liquid crystal cell. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 98.2°, 99.3%, 92.1%, and 52 pC. The liquid crystal cell was observed under a polarizing microscope under crossed nicols. As a result, although a number of streaks of light leakage due to friction were observed, it was in a good alignment state.

<Liquid Crystal Composition B>

[Example 24]

A liquid crystal display element was produced in the same manner as in Example 20 except that varnish Q was used instead of varnish P. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 98.0, 99.0%, 90.6%, and 89 pC. The liquid crystal cell was observed under a polarizing microscope under a crossed Nicol prism. As a result, although a number of streaks of light leakage due to friction were observed, it was in a good alignment state.

[Comparative Example 4]

A liquid crystal display element was produced in the same manner as in Example 23, except that varnish W was used instead of varnish P. The pretilt angle, VHR (30 Hz and 0.3 Hz), and ion density of the liquid crystal cell were measured and found to be 98.3, 98.5%, 87.3%, and 186 pC. The liquid crystal cell was observed under a polarizing microscope under a crossed Nicol prism. As a result, compared with Example 23 or Example 24, the streaks of light leakage caused by friction were many and the state was poor.

[Industrial availability]

The liquid crystal alignment agent of the present invention can be used for an alignment film for a liquid crystal display element. Since the alignment film obtained by the liquid crystal alignment agent of the present invention has high liquid crystal alignment property, it is particularly useful as an IPS mode, a TN mode, and a VA mode used for rubbing an alignment film.

Claims (13)

A liquid crystal alignment agent capable of at least substantially reducing a black level, which comprises a polydecylamine obtained by reacting a mixture of a tetracarboxylic dianhydride represented by the formula (I) with another tetracarboxylic dianhydride and a diamine. a composition of at least one of the acid and the derivative thereof, and the ratio of the tetracarboxylic dianhydride represented by the formula (I) is from 5 mol% to 95 mol based on the total amount of the mixture of the tetracarboxylic dianhydride %, the ratio of other tetracarboxylic dianhydride is 5 mol% to 95 mol%: Wherein X is an alkylene group having 2 to 12 carbon atoms, and the other tetracarboxylic dianhydride is at least one of tetracarboxylic dianhydride represented by formula (A-1) to formula (A-46), and the second The amine is at least one diamine selected from the group consisting of diamines represented by formula (1-1) to formula (1-3), formula (2), formula (3) and formula (4): In the formula (1-1), b is 0 or 1; any hydrogen in the cyclohexyl group may be substituted by a methyl group; in the formula (1-2), W ¹ is -CH ₂ - or -NH-: Wherein X ¹ is a single bond or an alkylene group having 1 to 10 carbon atoms; any -CH ₂ - of the alkylene group may be -O-, -S-, -NH-, -N(CH ₃ )- , -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CO-, -SO ₂ -, 1,3-phenylene, 1,4-phenylene or pyridazine-1,4 - replaced by two bases; In the formula (3), X ² is a single bond, -O-, -COO-, -OCO- or an alkylene group having 1 to 6 carbon atoms; R ¹ is an alkyl group having 3 to 30 carbon atoms, or a formula (a) In the formula (a), X ³ and X ^{4 are} independently a single bond or an alkylene group having 1 to 4 carbon atoms; and ring B and ring C are independently a 1,4-phenylene group or 1 , 4-cyclohexylene; R ² and R ^{3 are} independently fluorine or methyl, and f and g are independently 0, 1 or 2; c, d and e are independently 0 or 1, and the total of these is 1~ 3; R ⁴ is an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, an alkoxyalkyl group having 2 to 30 carbon atoms or a cholesteryl group, and these alkyl groups, alkoxy groups and alkoxy groups In the alkyl group, any hydrogen can be substituted by fluorine: Wherein X ^{5 is} independently -O- or an alkylene group having 1 to 6 carbon atoms; j is 0 or 1; R ⁵ is hydrogen, an alkyl group having 2 to 12 carbon atoms or an alkoxy group having 2 to 12 carbon atoms; The ring T is 1,4-phenylene or 1,4-cyclohexylene; X ⁶ is a single bond or an alkylene group having 1 to 3 carbon atoms; h is 0 or 1. A liquid crystal alignment agent capable of at least substantially reducing black level as described in claim 1, wherein the other tetracarboxylic dianhydride is of the formula (A-1) to the formula (A-4), and the formula (A-11) , formula (A-12), formula (A-14), formula (A-18) to formula (A-21), formula (A-28) to formula (A-30), formula (A-32), At least one of the tetracarboxylic anhydrides represented by the formula (A-37), the formula (A-39) to the formula (A-41), and the formula (A-43) to the formula (A-46), and the diamine is a formula ( 1-2-1), Formula (1-3), Formula (2-1)~Formula (2-3), Formula (2-7), Formula (2-10)~Formula (2-27), Formula (2-29), Formula (2-37)~Formula (2-39), Formula (2-41), Formula (2-43)~Formula (2-47), Formula (2-51), Formula ( 3-1) at least one of the diamines represented by the formula (3-12) and the formula (4-1) to the formula (4-12): Wherein R ²⁰ is an alkyl group having 5 to 16 carbon atoms; R ²¹ is an alkyl group having 3 to 10 carbon atoms; and R ²² is an alkyl group having 6 to 16 carbon atoms or a cholesteryl group; Wherein R ²⁶ is an alkyl group having 4 to 7 carbon atoms. A liquid crystal alignment agent capable of at least substantially reducing black level as described in claim 2, wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-2), and the formula (A-12) , formula (A-14), formula (A-18), formula (A-20), formula (A-21), formula (A-28), formula (A-30), formula (A-37), At least one of the tetracarboxylic anhydride represented by the formula (A-40) and the formula (A-45), and the diamine is a formula (1-2-1), a formula (1-3), a formula (2-7), Formula (2-10)~Formula (2-12), Formula (2-16)~Formula (2-19), Formula (2-21)~Formula (2-27), Formula (2-37)~ (2-39), Formula (2-41), Formula (2-43)~Formula (2-47), Formula (2-51), Formula (3-1)~Formula (3-12) and Formula ( 4-1) at least one of the diamines represented by the formula (4-12). A liquid crystal alignment agent capable of at least substantially reducing black level as described in claim 3, wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-12), and the formula (A-14) At least one of the tetracarboxylic anhydrides represented by the formula (A-18) and the formula (A-45), and the diamine is a formula (1-2-1), a formula (1-3), and a formula (2-7). Equation (2-10)~Formula (2-12), Formula (2-26), Formula (2-44), Formula (2-45), and Formula (3-1)~Formula (3-6) At least one of the diamines indicated. A liquid crystal alignment agent capable of at least substantially reducing black level as described in claim 2, wherein the other tetracarboxylic dianhydride is of the formula (A-14), the formula (A-18), and the formula (A-19) , formula (A-20), formula (A-21), formula (A-28), formula (A-29), formula (A-30), formula (A-32), formula (A-39), At least one of the tetracarboxylic anhydrides represented by the formula (A-40), the formula (A-41), the formula (A-43), the formula (A-44), and the formula (A-46), and the diamine is a formula ( 1-2-1), Formula (1-3), Formula (2-1) to Formula (2-3), Formula (2-26), Formula (2-29), Formula (2-37), Formula (2-43) At least one of the diamines represented by the formula (2-47), the formula (3-1) to the formula (3-12), and the formula (4-1) to the formula (4-12). A liquid crystal alignment agent capable of at least substantially reducing a black level as described in claim 5, wherein the other tetracarboxylic dianhydride is of the formula (A-14), the formula (A-20), and the formula (A-21) At least one of the tetracarboxylic anhydrides represented by the formula (A-39), the formula (A-44) and the formula (A-46), and the diamine is a formula (1-2-1) or a formula (1-3) , (2-1) to (2-3), (2-26), (2-29), (2-44) and (3-1) to (3-6) At least one of the diamines indicated. A liquid crystal alignment agent capable of at least substantially reducing black level as described in claim 2, wherein the other tetracarboxylic dianhydride is of the formula (A-1), the formula (A-2), and the formula (A-3) At least one of the tetracarboxylic anhydrides represented by the formula (A-4), the formula (A-11), the formula (A-12) and the formula (A-45), and the diamine is a formula (1-2-1) , formula (1-3), formula (2-1) to formula (2-3), formula (2-13) to formula (2-15), formula (2-20) to formula (2-26), At least one of the diamines represented by the formula (2-29), the formula (2-39), and the formula (2-41). As described in item 7 of the patent application, at least the black power can be greatly reduced. A flat liquid crystal alignment agent in which other tetracarboxylic dianhydrides are represented by formula (A-1), formula (A-2), formula (A-4), formula (A-12) and formula (A-45) At least one of the tetracarboxylic anhydrides, the diamines are of the formula (1-2-1), the formula (1-3), the formula (2-1) to the formula (2-3), and the formula (2-13). At least one of the diamines represented by (2-15), (2-26) and (2-29). The liquid crystal alignment agent which can at least greatly reduce the black level, according to any one of the above-mentioned items, wherein the method further comprises the use of the tetracarboxylic dianhydride represented by the formula (I). At least one of the other polylysines and derivatives thereof produced. A liquid crystal alignment film which is formed by heating a coating film of a liquid crystal alignment agent which at least greatly reduces black level as described in any one of claims 1 to 8. A liquid crystal alignment film formed by heating a coating film of a liquid crystal alignment agent capable of at least greatly reducing a black level as described in claim 9 of the patent application. A liquid crystal display element comprising: a pair of substrates, a liquid crystal layer formed between the substrates, an electrode for applying a voltage to the liquid crystal layer, and a liquid crystal alignment film according to claim 10 of the patent application. A liquid crystal display element comprising: a pair of substrates, a liquid crystal layer formed between the substrates, an electrode for applying a voltage to the liquid crystal layer, and a liquid crystal alignment film according to claim 11 of the patent application.