JP4561607B2 - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent in which a polyamic acid or a derivative thereof is dissolved in a solvent, and a liquid crystal display device including a liquid crystal alignment film formed from the liquid crystal aligning agent.

  Liquid crystal display elements are used in various liquid crystal display devices such as monitors for notebook computers and desktop computers, video camera viewfinders, and projection displays. Recently, they have also been used as televisions. . Furthermore, it is also used as an optoelectronic-related element such as an optical printer head, an optical Fourier transform element, or a light valve.

  The liquid crystal display element usually has 1) a pair of substrates arranged opposite to each other, 2) electrodes formed on one or both of the opposed surfaces of each of the pair of substrates, and 3) each of the pair of substrates. And 4) a liquid crystal layer formed between the pair of substrates.

  As conventional liquid crystal display elements, display elements using nematic liquid crystals are the mainstream. In the nematic liquid crystal display element, 1) a TN (Twisted Nematic) type liquid crystal display element in which the alignment direction of the liquid crystal on one substrate side and the alignment direction of the liquid crystal on the other substrate side in the liquid crystal layer are twisted at an angle of 90 degrees. 2) STN (Super Twisted Nematic) type liquid crystal display element in which the alignment direction is twisted at an angle of usually 180 degrees or more, 3) So-called TFT (Thin Film Transistor) type liquid crystal display element using a thin film transistor has been put into practical use. Yes.

  These liquid crystal display elements have a drawback that a viewing angle at which an image can be properly viewed is narrow, and when viewed from an oblique direction, luminance and contrast decrease and luminance inversion occurs in a halftone. In recent years, the problem of viewing angle is as follows: 1) TN-TFT type liquid crystal display element using optical compensation film, 2) VA (vertical alignment) type liquid crystal display element using vertical alignment and optical compensation film, 3) vertical MVA (Multi Domain Vertical Alignment) type liquid crystal display element using alignment and protrusion structure technology together, or 4) IPS (In-Plane Switching) type liquid crystal display element of lateral electric field type, 5) ECB (Electrically Controlled Birefringence type) Liquid crystal display element, 6) Optically compensated bend (Optically self-compensated birefringence: OCB) type liquid crystal It has been improved by technologies such as display elements and put into practical use or being studied.

  The development of the technology of the liquid crystal display element has been achieved not only by improving the drive system and the element structure, but also by improving the components used for the display element. Among the constituent members used in display elements, the liquid crystal alignment film is one of the important elements related to the display quality of the liquid crystal display element, and the role of the liquid crystal alignment film is increasing as the quality of the display element increases. It has become important year after year.

The liquid crystal alignment film is prepared from a liquid crystal aligning agent. Currently, the liquid crystal aligning agent mainly used is a solution in which polyamic acid or soluble polyimide is dissolved in an organic solvent. After applying such a solution to a substrate, a polyimide-based alignment film is formed by film formation by means such as heating. Various liquid crystal aligning agents other than polyamic acid are also being studied, but they are almost practical in terms of heat resistance, chemical resistance (liquid crystal resistance), coating properties, liquid crystal alignment properties, electrical properties, optical properties, display properties, etc. It has not been converted.

  Important characteristics required for the liquid crystal alignment film in order to improve the display quality of the liquid crystal display element include voltage holding ratio and residual DC. If the voltage holding ratio is low, the voltage applied to the liquid crystal during the frame period decreases, resulting in a decrease in luminance and hinders normal gradation display. On the other hand, if the residual DC is large, a so-called “afterimage” is generated in which an erased image remains even though the voltage is turned off after the voltage is applied.

In recent years, several methods have been proposed as an attempt to solve the above problems.
1) A polyamic acid composition containing a combination of two or more polyamic acids having different physical properties for forming a liquid crystal alignment film is known (see, for example, Patent Documents 1 and 2).
2) A varnish composition containing a polymer component containing polyamic acid and polyamide and a solvent is known (see, for example, Patent Document 3).
3) A varnish composition containing two or more polyamic acids and polyamides having different physical properties and a solvent is known. (For example, refer to Patent Document 4).
4) A varnish composition containing a polymer material containing a polyamic acid or the like synthesized using a diamine compound having a specific structure is known (see, for example, Patent Document 5).
However, these prior arts do not sufficiently solve the problems of voltage holding ratio and residual DC.

On the other hand, a compound represented by the following general formula (I) or (I ′) is disclosed as tetracarboxylic dianhydride which is a raw material of polyamic acid (see, for example, Patent Document 6). However, at present, no study has been made on the application of polyamic acid using the tetracarboxylic dianhydride as a liquid crystal aligning agent.
JP 11-193345 A JP-A-11-193347 International Publication No. 00/61684 Pamphlet WO 01/000733 pamphlet JP 2002-162630 A U.S. Pat. No. 4,490,545

  In view of the above situation, it is desired to develop a liquid crystal aligning agent for a liquid crystal display element in which the problems of voltage holding ratio and residual DC are improved, and a liquid crystal display element having a liquid crystal alignment film formed using the same. ing.

The present inventors have intensively studied to solve the above problems.
As a result, a liquid crystal aligning agent containing one or more polyamic acids or derivatives thereof obtained by reacting a tetracarboxylic dianhydride compound containing a specific tetracarboxylic dianhydride with a diamine compound is obtained. It has been found that a good voltage holding ratio and a remarkable residual DC reduction effect can be imparted to a liquid crystal display element having a liquid crystal alignment film produced by using the present invention, and the present invention has been completed.

  Furthermore, it has been found that by appropriately selecting the polyamic acid, a liquid crystal alignment film prepared using the liquid crystal aligning agent can be appropriately applied to liquid crystal display elements of various display drive systems.

The present invention has the following configuration.
[1] A polyamic acid or a derivative thereof obtained by reacting a tetracarboxylic dianhydride compound containing a tetracarboxylic dianhydride represented by the following general formula (I) or (I ′) with a diamine compound: Liquid crystal aligning agent to contain.

In formulas (I) and (I ′), R is independently —H or alkyl having 1 to 10 carbons, X and Y are independently a single bond or — (CH ₂ ) _n —, Here, n is an integer of 1 to 10.

  [2] The tetracarboxylic dianhydride represented by the general formula (I) is represented by the following formulas (I-1), (I-2), (I-3), (I-7), (I- 8) and at least one selected from the group consisting of compounds of (I-9), and the tetracarboxylic dianhydride represented by the general formula (I ′) is represented by the following formula (I′-1) , (I'-2), (I'-3), (I'-7), (I'-8) and (I'-9) at least one selected from the group consisting of compounds The liquid crystal aligning agent as described in [1] characterized by these.

  [3] The liquid crystal aligning agent according to [2], wherein the tetracarboxylic dianhydride represented by the general formula (I) is a compound of the formula (I-9).

  [4] The liquid crystal aligning agent according to [1], wherein the tetracarboxylic dianhydride compound further includes an aromatic tetracarboxylic dianhydride.

  [5] The liquid crystal aligning agent according to [4], wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride.

  [6] The liquid crystal aligning agent according to [1], wherein the tetracarboxylic dianhydride compound further includes an alicyclic tetracarboxylic dianhydride.

  [7] The liquid crystal aligning agent according to [6], wherein the alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

  [8] The liquid crystal aligning agent according to [1], wherein the diamine compound includes diamines represented by the following general formulas (II) to (VIII).

In Formula (II), A ₁ is — (CH ₂ ) _m —, where m is an integer of 1 to 12. In formula (IV), (VI) (VIII), A ₁ is a single bond, —O—, —S—, —S—S—, —SO ₂ —, —CO—, —CONH—, —NHCO—. _{, -C (CH 3) 2 -} , - C (CF 3) 2 -, - (CH 2) m -, - O- (CH 2) m -O- or -S- (CH _{2) m} -S- Where m is an integer from 1 to 12. In formulas (VII) and (VIII), A ₂ is independently a single bond, —O—, —S—, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or It is C1-C3 alkylene. In formulas (III) to (VIII), hydrogen bonded to the cyclohexane ring or the benzene ring may be independently replaced with -F or -CH ₃ .

  [9] The diamine compound is at least one selected from the group consisting of p-phenylenediamine, m-phenylenediamine, and compounds of the following formulas (VI-1) to (VI-12). The liquid crystal aligning agent as described in [8].

  [10] The liquid crystal aligning agent according to [9], wherein the diamine compound is p-phenylenediamine or a compound of the formula (VI-1).

  [11] The liquid crystal aligning agent according to any one of [1] to [10], wherein the diamine compound includes a diamine having a side chain structure.

[12] The liquid crystal aligning agent according to [11], wherein the diamine having a side chain structure is a diamine represented by the following general formulas (IX) , (XI) to (XIV).

In formula (IX), A ₃ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH— or — (CH ₂ ) _m —, wherein m is 1 to 6 R ₁ is a group having a steroid skeleton, a group represented by the following formula (X), or two amino groups bonded to the benzene ring when the positional relationship between the groups is para. When the positional relationship is meta, it is alkyl having 1 to 10 carbon atoms or phenyl. In the alkyl, any —CH ₂ — may be independently replaced by —CF ₂ —, —CHF—, —O—, —CH═CH— or —C≡C—, and —CH ₃ May be replaced by —CH ₂ F, —CHF ₂ or —CF ₃ . Hydrogen bonded to the phenyl ring-forming carbon, -F _{independently, -CH 3, -OCH 3, -OCH} 2 F, may be replaced with -OCHF ₂ or -OCF _3.

In Formula (X), A ₄ and A ₅ are each independently a single bond, —O—, —COO—, —OCO—, —CONH—, —CH═CH—, or alkylene having 1 to 20 carbon atoms. Each of R ₂ and R ₃ is independently —F or —CH ₃ , and ring S is 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, Pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl, R ₄ is —H, —F , alkyl having 1 to 20 carbon atoms, a fluorine-substituted alkyl having 1 to 20 carbon atoms, having 1 to 20 carbon atoms alkoxy, -CN, a -OCH ₂ F, -OCHF ₂ or -OCF _3, a and b are each Independently represents an integer of 0 to 4, and a or b is 2 A ₄ or A ₅ adjacent to each other when ˜4 is a different group, c, d and e each independently represent an integer of 0 to 3, and when e is 2 or 3, a plurality of rings S are the same Or f and g each independently represents an integer of 0 to 2 and c + d + e ≧ 1.

In formula (XI), hydrogen bonded to carbon forming the steroid skeleton may be independently replaced with —CH ₃ . In formulas (XI) and (XII), each R ₅ is independently —H or —CH ₃ , each R ₆ is independently —H or an alkyl or alkenyl having 1 to 20 carbon atoms, A ₆ is each independently a single bond, —C (═O) — or —CH ₂ —. In formula (XII), R ₇ and R ₈ are each independently —H, alkyl having 1 to 20 carbons, or phenyl.

In the formula (XIII), R ₉ is —H or alkyl having 1 to 20 carbons, and arbitrary —CH ₂ — of the alkyl having 2 to 20 carbons among the alkyls is —O—, —CH═CH. -Or -C≡C- may be substituted. In formulas (XIII) and (XIV), A ₇ is independently —O— or alkylene having 1 to 6 carbons. In formula (XIII), A ₈ is a single bond or alkylene having 1 to 3 carbon atoms, ring T is 1,4-phenylene or 1,4-cyclohexylene, and h is 0 or 1. In Formula (XIV), R ₁₀ is alkyl having 6 to 22 carbons, and R ₁₁ is —H or alkyl having 1 to 22 carbons.

  [13] The diamine having the side chain structure is selected from the group consisting of compounds of the following formulas (IX-2), (IX-4), (IX-5), (IX-6) and (XIII-2) The liquid crystal aligning agent according to [12], which is at least one of the above.

In formula (IX-2), R ₁₂ is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and in formulas (IX-4) to (IX-6), R ₁₃ is 1 to 1 carbon atoms. 10 is alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons, and R ₁₈ is —H and alkyl having 1 to 20 carbons in the formula (XIII-2).

[14] The diamine having the side chain structure is a compound in which R ₁₃ is C ₇ H ₁₅ in the formula (IX-6), or a compound in which R ₁₈ is C ₄ H ₉ in (XIII-2). The liquid crystal aligning agent as described in [13] characterized by the above-mentioned.

  [15] A polyamic acid or a derivative thereof obtained by reacting the compound of formula (I-9) and pyromellitic dianhydride with the compound of formula (VI-1). The liquid crystal aligning agent in any one of [1]-[10].

[16] A liquid crystal aligning agent containing two or more polyamic acids or derivatives thereof,
A) a polyamic acid obtained by reacting a tetracarboxylic dianhydride compound A1 with a diamine compound A2 containing a diamine represented by the following general formulas (II) to (VIII), or a derivative A thereof, and B) tetracarboxylic A liquid crystal aligning agent containing a polyamic acid obtained by reacting the acid dianhydride compound B1 and a diamine compound B2 containing a diamine having a side chain structure, or a derivative B thereof;
At least one of the tetracarboxylic dianhydride compound A1 and the tetracarboxylic dianhydride compound B1 contains a tetracarboxylic dianhydride represented by the following general formula (I) or (I ′): Liquid crystal aligning agent characterized by being a compound.

  In formula (I), each R is independently -H or alkyl having 1 to 10 carbons.

In Formula (II), A ₁ is — (CH ₂ ) _m —, where m is an integer of 1 to 12. In formulas (IV), (VI), and (VIII), A ₁ represents a single bond, —O—, —S—, —S—S—, —SO ₂ —, —CO—, —CONH—, —NHCO. _{-, - C (CH 3)} 2 -, - C (CF 3) 2 -, - (CH 2) m -, - O- (CH 2) m -O -, - S- (CH 2) m -S Where m is an integer from 1 to 12. In formulas (VII) and (VIII), A ₂ is independently a single bond, —O—, —S—, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or It is C1-C3 alkylene. Hydrogen bonded to a cyclohexane ring or a benzene ring in the formula (III) ~ (VIII) it is, -F independently may be replaced with -CH _3.

  [17] The tetracarboxylic dianhydride compounds A1 and B1 are represented by the following formulas (I-1), (I-2), (I-3), (I-7), (I-8) and Compounds of (I-9), the following formulas (I′-1), (I′-2), (I′-3), (I′-7), (I′-8) and (I′-9) ), An aromatic tetracarboxylic dianhydride, and an alicyclic tetracarboxylic dianhydride, at least one selected from the group consisting of a liquid crystal aligning agent according to [16].

  [18] The liquid crystal aligning agent according to [17], wherein the compound of formula (I-9) is contained in at least one of the tetracarboxylic dianhydride compounds A1 and B1.

  [19] The liquid crystal aligning agent according to [17], wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride.

  [20] The liquid crystal aligning agent according to [17], wherein the alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

[21] The liquid crystal aligning agent according to [16], wherein the diamine having a side chain structure is a diamine represented by the following general formulas (IX) , (XI) to (XIV).

In formula (IX), A ₃ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH— or — (CH ₂ ) _m —, wherein m is 1 to 6 R ₁ is a group having a steroid skeleton, a group represented by the following formula (X), or two amino groups bonded to the benzene ring when the positional relationship between the groups is para. When the positional relationship is meta, it is alkyl having 1 to 10 carbon atoms or phenyl. In the alkyl, any —CH ₂ — may be independently replaced by —CF ₂ —, —CHF—, —O—, —CH═CH— or —C≡C—, ₃ may be replaced by —CH ₂ F, —CHF ₂ or —CF ₃ . Hydrogen bonded to the phenyl ring-forming carbon, -F _{independently, -CH 3, -OCH 3, -OCH} 2 F, may be replaced with -OCHF ₂ or -OCF _3.

In Formula (X), A ₄ and A ₅ are each independently a single bond, —O—, —COO—, —OCO—, —CONH—, —CH═CH—, or alkylene having 1 to 20 carbon atoms. Each of R ₂ and R ₃ is independently —F or —CH ₃ , and ring S is 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, Pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl, R ₄ is —H, —F , alkyl having 1 to 20 carbon atoms, a fluorine-substituted alkyl having 1 to 20 carbon atoms, having 1 to 20 carbon atoms alkoxy, -CN, a -OCH ₂ F, -OCHF ₂ or -OCF _3, a and b are each Independently represents an integer of 0 to 4, and a or b is 2 A ₄ or A ₅ adjacent to each other when ˜4 is a different group, c, d and e each independently represent an integer of 0 to 3, and when e is 2 or 3, a plurality of rings S are the same Or f and g each independently represents an integer of 0 to 2 and c + d + e ≧ 1.

In formula (XI), hydrogen bonded to carbon forming the steroid skeleton may be independently replaced with —CH ₃ . In formulas (XI) and (XII), each R ₅ is independently —H or —CH ₃ , each R ₆ is independently —H or an alkyl or alkenyl having 1 to 20 carbon atoms, A ₆ is each independently a single bond, —C (═O) — or —CH ₂ —. In formula (XII), R ₇ and R ₈ are each independently —H, alkyl having 1 to 20 carbons, or phenyl.

In the formula (XIII), R ₉ is —H or alkyl having 1 to 20 carbons, and any —CH ₂ — of the alkyl having 2 to 20 carbons among the alkyls is independently —O—, — CH = CH- or -C≡C- may be substituted. In formulas (XIII) and (XIV), A ₇ is —O— or alkylene having 1 to 6 carbons. In formula (XIII), A ₈ is a single bond or alkylene having 1 to 3 carbon atoms, ring T is 1,4-phenylene or 1,4-cyclohexylene, and h is 0 or 1. In Formula (XIV), R ₁₀ is alkyl having 6 to 22 carbons, and R ₁₁ is —H or alkyl having 1 to 22 carbons.

[22] The diamine compounds A2 and B2 are respectively p-phenylenediamine, m-phenylenediamine, the following formulas (VI-1) to (VI-12), (IX-2), (IX-4), ( [IX] The liquid crystal aligning agent according to [21], which is at least one selected from the group consisting of compounds of (IX-5), (IX-6) and (XIII-2).

In formula (IX-2), R ₁₂ is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and in formulas (IX-4) to (IX-6), R ₁₃ is 1 to 1 carbon atoms. 10 is alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons, and R ₁₈ is —H and alkyl having 1 to 20 carbons in the formula (XIII-2).

[23] The formula (IX-6) is a compound in which R ₁₃ is C ₇ H ₁₅ , or the formula (XIII-2) is a compound in which R ₁₈ is C ₄ H _9. The liquid crystal aligning agent according to [22], which is characterized.

[24] A polyamic acid or derivative thereof obtained by reacting the compound of formula (I-9) and pyromellitic dianhydride with the compound of formula (VI-1) as the polyamic acid or derivative A thereof. PA1,
The polyamic acid or its derivative B is a polyamic acid or its derivative PA2 obtained by reacting the compound of the formula (I-9) with p-phenylenediamine and the compound of the formula (XIII-2), or It is a polyamic acid or its derivative PA3 obtained by reacting the compound of formula (I-9) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride with the compound of formula (IX-6). The liquid crystal aligning agent in any one of [16]-[23] characterized by these.

  [25] The liquid crystal aligning agent according to [24], comprising the polyamic acid or its derivatives PA1 and PA2.

  [26] The liquid crystal aligning agent according to [24], containing the polyamic acid or its derivatives PA1 and PA3.

[27] 1) A pair of substrates arranged opposite to each other,
2) Electrodes formed on one or both of the opposing surfaces of the pair of substrates,
3) a liquid crystal display element comprising: a liquid crystal alignment film formed on opposing surfaces of each of the pair of substrates; and 4) a liquid crystal layer formed between the pair of substrates.
The liquid crystal alignment element is a liquid crystal display element which is a liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of [1] to [26].

  In the general formulas (III) to (XIV), the bond between the center of the ring and the amino displayed outside the ring indicates that the amino is bonded to any carbon of the ring. . Similarly, in the present specification, the bond between the center of the ring and the group displayed outside the ring in the chemical formula is such that this group is bonded to any atom of atoms such as carbon constituting the ring. Indicates that

  According to the present invention, it is possible to provide liquid crystal display elements of various drive systems that have a high voltage holding ratio and a suppressed residual DC.

  The liquid crystal aligning agent of this invention is a composition containing 1 type, or 2 or more types of polyamic acid or its derivative (s).

<1. Polyamic acid or derivative thereof in the present invention>
At least one of the polyamic acids or derivatives thereof contained in the liquid crystal aligning agent of the present invention includes a tetracarboxylic dianhydride containing a tetracarboxylic dianhydride represented by the following general formula (I) or (I ′): A polyamic acid or a derivative thereof obtained by reacting a physical compound with a diamine compound.

In formulas (I) and (I ′), R is independently —H or alkyl having 1 to 10 carbons, X and Y are independently a single bond, — (CH ₂ ) _n —, Here, n is an integer of 1 to 10.

The tetracarboxylic dianhydride compound in the present invention comprises one or more tetracarboxylic dianhydrides, but a part of the tetracarboxylic dianhydride may be substituted with a dicarboxylic acid. Here, the ratio of the dicarboxylic acid to the tetracarboxylic dianhydride is preferably 10 mol% or less.

  The diamine compound in the present invention is composed of one or more diamines, but a part of the diamine may be substituted with a monoamine. Here, the ratio of monoamine to diamine is preferably 10 mol% or less.

  Here, the derivative of polyamic acid is a component that is liquid when used as a liquid crystal aligning agent described later, and can form a liquid crystal aligning film containing polyimide as a main component when used as a liquid crystal aligning film described later. . Examples of such polyamic acid derivatives include soluble polyimides, polyamic acid esters, and polyamic acid amides. More specifically, 1) all amino groups of the polyamic acid and carboxylic acid undergo a dehydration ring-closing reaction. Polyimide, 2) Partially dehydrated ring-closure reaction, 3) Polyamic acid-polyamide obtained by reacting part of acid dianhydride contained in tetracarboxylic dianhydride compound with organic dicarboxylic acid A copolymer, and 4) polyamideimide obtained by subjecting a part or all of the polyamic acid-polyamide copolymer to a dehydration ring-closing reaction.

  As described above, at least one of the polyamic acids or derivatives thereof in the present invention includes a tetracarboxylic dianhydride compound containing a tetracarboxylic dianhydride represented by the general formula (I) or (I ′). It is obtained by reacting with a diamine compound.

  R in the general formula (I) is —H or alkyl having 1 to 10 carbons, and in the case of alkyl having 3 to 10 carbons, it is linear alkyl or alkyl having a branched structure. R is preferably -H or alkyl having 1 to 2 carbon atoms when used for applications requiring a small pretilt angle, and alkyl having 3 to 10 carbon atoms is preferable when used for applications requiring a large pretilt angle. . The four Rs may be the same or different.

X in the general formula (I) is a single bond or — (CH ₂ ) _n —, and n is an integer of 1 to 10. When rigidity is required for the polyamic acid or its derivative, X is preferably a single bond or —CH ₂ —, and when flexibility is required, n is an integer of 2 to 10 — (CH ₂ ). _n- is preferred.

  Examples of the tetracarboxylic dianhydride represented by the general formula (I) include the following tetracarboxylic dianhydrides. Of these, tetracarboxylic dianhydrides represented by the formulas (I-1) to (I-12) are more preferable, and most preferable are the formulas (1-1), (I-2), ( Examples thereof include tetracarboxylic dianhydrides represented by I-3), (I-7), (I-8), and (I-9).

R in the general formula (I ′) is —H or alkyl having 1 to 10 carbons, and in the case of alkyl having 3 to 10 carbons, it is linear alkyl or alkyl having a branched structure. R is preferably -H or alkyl having 1 to 2 carbon atoms when used for applications requiring a small pretilt angle, and alkyl having 3 to 10 carbon atoms is preferable when used for applications requiring a large pretilt angle. . The four Rs may be the same or different.

X and Y in the general formula (I ′) are each independently a single bond or — (CH ₂ ) _n —, and n is an integer of 1 to 10. When rigidity is required for the polyamic acid or its derivative, X and Y are preferably a single bond, —CH ₂ —, — (CH ₂ ) ₂ —, or — (CH ₂ ) ₃ —, and flexibility is required. In this case, — (CH ₂ ) _n — in which n is an integer of 4 to 10 is preferable.

  Examples of the tetracarboxylic dianhydride represented by the general formula (I ′) include the following tetracarboxylic dianhydrides. Among these, tetracarboxylic dianhydrides represented by the formulas (I′-1) to (I′-18) are more preferable, and most preferable are the formulas (1′-1) and (I′−). 2), tetracarboxylic dianhydrides represented by (I′-3), (I′-7), (I′-8), and (I′-9).

  For the production method of the tetracarboxylic dianhydride represented by the general formula (I) or (I ′), reference can be made to, for example, US Pat. No. 4,490,545. For example, a tetracarboxylic dianhydride represented by the general formula (I) can be obtained by photocycloaddition reaction of maleic anhydride having R as a substituent with a chain diene of 2 times or more. The tetracarboxylic dianhydride represented by the formula (I ′) can be obtained by subjecting maleic anhydride having R as a substituent to a photocycloaddition reaction with a cyclic diene twice or more.

  The tetracarboxylic dianhydride compound may contain one kind of tetracarboxylic dianhydride represented by the general formula (I) or (I ′), or may contain two or more kinds. . In the tetracarboxylic dianhydride compound, the total content of the tetracarboxylic dianhydride represented by the general formula (I) and / or (I ′) is 10 to 100 of the total tetracarboxylic dianhydride compound. It is preferably mol%, more preferably 25 to 100 mol%.

  Other tetracarboxylic dianhydrides other than the tetracarboxylic dianhydride represented by the general formula (I) or (I ′) which may be contained in the tetracarboxylic dianhydride compound are arbitrarily selected. 1) Aromatic tetracarboxylic dianhydride, 2) Aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride may be sufficient.

  In addition, in order for the polyamic acid in this invention to be used as a component of a liquid crystal aligning agent, it is preferable to take a form soluble in a solvent. In order to make the polyamic acid in the present invention into the soluble form, it is preferable to appropriately select the other tetracarboxylic dianhydride.

  Here, 1) As an aromatic tetracarboxylic dianhydride, the acid dianhydride represented, for example by following formula (1)-(13) is mentioned as a specific example. Of the following aromatic tetracarboxylic dianhydrides, dianhydrides represented by Formula (1), Formula (2), Formula (5), Formula (6), and Formula (7) are more preferable. Most preferred is pyromellitic dianhydride represented by the formula (1).

  Examples of the 2) aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride that can be included in the other tetracarboxylic dianhydride compounds include the following formulas (14) to (62). The acid dianhydride represented by this is specifically exemplified.

  Among the above tetracarboxylic dianhydrides, the acid dianhydrides represented by the formulas (14) to (29) and the formula (60) are more preferable, and the formula (14) is particularly preferable. 1,2,3,4-cyclobutanetetracarboxylic dianhydride. In order to make the polyamic acid in the present invention soluble in a solvent, an acid dianhydride represented by formula (19), formula (20), formula (27) to (29), or formula (60) is used. It is preferable.

  The other tetracarboxylic dianhydride compounds may include tetracarboxylic dianhydrides represented by the formulas (1) to (62) alone or in combination of two or more. it can. Aromatic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride (particularly preferably pyromellitic dianhydride, 1,2,3,4-cyclobutanetetra A liquid crystal alignment film formed using a liquid crystal aligning agent containing a polyamic acid synthesized from a tetracarboxylic dianhydride compound in the present invention, including a carboxylic acid dianhydride). In particular, a good voltage holding ratio and a remarkable residual DC reduction effect can be provided.

  Furthermore, in addition to the tetracarboxylic dianhydrides represented by the formulas (1) to (62), the other tetracarboxylic dianhydride compounds include, for example, a tetracarboxylic dianhydride having a side chain structure. Can also be mentioned. The liquid crystal aligning film formed using the liquid crystal aligning agent containing the polyamic acid synthesized from the tetracarboxylic dianhydride compound in this invention containing the tetracarboxylic dianhydride which has a side chain structure contains it The pretilt angle in the liquid crystal display element can be increased.

  The tetracarboxylic dianhydride having a side chain structure is not particularly limited, but those having a steroid skeleton represented by the following formulas (63) and (64) can be preferably used in the present invention.

  The other tetracarboxylic dianhydrides that can be contained in the tetracarboxylic dianhydride compound in the present invention are not limited to the above-mentioned tetracarboxylic dianhydrides, and the object of the present invention is achieved. It goes without saying that various other forms of tetracarboxylic dianhydride exist within the range. Such further other tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  As described above, the polyamic acid or derivative thereof contained in the liquid crystal aligning agent of the present invention is obtained by reacting a tetracarboxylic dianhydride compound with a diamine compound.

  Although the diamine contained in the diamine compound is arbitrarily selected, diamines represented by the general formulas (II) to (VIII) are preferable.

  Examples of the diamine represented by the general formula (II) include diamines represented by the formulas (II-1) to (II-3).

  Examples of the diamine represented by the general formula (III) include diamines represented by the formulas (III-1) and (III-2).

  Examples of the diamine represented by the general formula (IV) include diamines represented by the formulas (IV-1) to (IV-3).

  Examples of the diamine represented by the general formula (V) include diamines represented by the formulas (V-1) to (V-5).

  Examples of the diamine represented by the general formula (VI) include diamines represented by the formulas (VI-1) to (VI-30).

  Examples of the diamine represented by the general formula (VII) include diamines represented by the formulas (VII-1) to (VII-6).

  Examples of the diamine represented by the general formula (VIII) include diamines represented by the formulas (VIII-1) to (VIII-11).

  Of these, more preferably, the formulas (V-1) to (V-5), the formulas (VI-1) to (VI-12), the formula (VI-26), the formula (VI-27), the formula ( VII-1), formula (VII-2), formula (VII-6), diamines represented by formulas (VIII-1) to (VIII-5), and most preferably formula (V-1), Examples include diamines represented by formula (V-2) and formulas (VI-1) to (VI-12).

The diamine compound in the present invention may contain one kind of diamine represented by the general formulas (II) to (VIII), or may contain two or more kinds. The molar ratio of the diamines represented by the general formulas (II) to (VIII) in the diamine compound according to the present invention is the desired diamine structure represented by the general formulas (II) to (VIII). What is necessary is just to adjust according to a voltage holding | maintenance rate and a residual DC reduction effect, and it is preferable that it is 1-100%, and it is more preferable that it is 5-80%.

  As described above, the diamine compound in the present invention is composed of one or more diamines, and in particular, a large pretilt angle is required for VA liquid crystal display elements, OCB liquid crystal display elements, STN liquid crystal display elements, and the like. For such applications, it is preferable to include a diamine having a side chain structure.

  In this specification, the diamine having a side chain structure means a diamine having a side chain branched from the main chain when a group connecting two amino groups is used as the main chain. That is, a diamine having a side chain structure reacts with tetracarboxylic dianhydride to provide a polyamic acid or polyimide (branched polyamic acid or branched polyimide) having a side chain group with respect to the polymer main chain. Can do. A liquid crystal alignment film formed from a liquid crystal alignment agent containing a polyamic acid or a polyimide having a side chain group with respect to such a polymer main chain can increase the pretilt angle in the liquid crystal display element. This is described in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 11-193345).

Therefore, the side chain in the diamine having a side chain structure may be appropriately selected according to the required pretilt angle. For example, the side chain is preferably a group having 3 or more carbon atoms. In particular,
1) phenyl which may have a substituent, cyclohexylphenylene which may have a substituent, bis (cyclohexyl) phenylene which may have a substituent, alkyl having 3 or more carbon atoms, alkenyl or Alkynyl,
2) phenyloxy which may have a substituent, cyclohexyloxy which may have a substituent, bis (cyclohexyl) oxy which may have a substituent, which may have a substituent Phenylcyclohexyloxy, optionally substituted cyclohexylphenyloxy, or alkyloxy, alkenyloxy or alkynyloxy having 3 or more carbon atoms,
3) Phenylcarbonyl, or alkylcarbonyl, alkenylcarbonyl or alkynylcarbonyl having 3 or more carbon atoms,
4) Phenylcarbonyloxy, or alkylcarbonyloxy, alkenylcarbonyloxy or alkynylcarbonyloxy having 3 or more carbon atoms,
5) phenyloxycarbonyl which may have a substituent, cyclohexyloxycarbonyl which may have a substituent, bis (cyclohexyl) oxycarbonyl which may have a substituent, which has a substituent Bis (cyclohexyl) phenyloxycarbonyl which may be substituted, cyclohexylbis (phenyl) oxycarbonyl which may have a substituent, or alkyloxycarbonyl having 3 or more carbon atoms, alkenyloxycarbonyl or alkynyloxycarbonyl,
6) phenylaminocarbonyl, or alkylaminocarbonyl having 3 or more carbon atoms, alkenylaminocarbonyl or alkynylaminocarbonyl,
7) Cyclic alkylene having 3 or more carbon atoms,
8) Cycloalkylalkylene which may have a substituent, phenylalkylene which may have a substituent, bis (cyclohexyl) alkylene which may have a substituent, which may have a substituent Cyclohexyl phenylalkylene, optionally substituted bis (cyclohexyl) phenylalkylene, optionally substituted phenylalkyloxy, alkylphenyloxycarbonyl, or alkylbiphenylyloxycarbonyl,
9) phenyl or cyclohexyl substituted by alkyl, fluorine-substituted alkyl, or alkoxy, and
10) Two or more benzene rings or cyclohexane rings are single-bonded, or are bonded via —O—, —COO—, —OCO—, —CONH—, or alkylene having 1 to 3 carbon atoms,
Examples include, but are not limited to, a ring assembly group substituted by alkyl, fluorine-substituted alkyl, or alkoxy, or a group having a steroid skeleton.

  Here, examples of the “substituent” include alkyl, alkoxy, alkoxyalkyl and the like.

  Moreover, bis (cyclohexyl) or bis (phenyl) may be interrupted by alkylene.

  In the present specification, the terms “alkyl”, “alkenyl”, and “alkynyl” may be linear or branched.

Specific examples of the diamine having a side chain structure used in the present invention include diamines represented by the general formulas (IX) and (XI) to (XIV).

In the general formula (IX), the two amino groups are bonded to the phenyl ring carbon. Preferably, the bonding positional relationship between the two amino groups is meta or para. Further, each of the two amino groups is preferably bonded to the 3-position and 5-position, or the 2-position and 5-position, when the bonding position of “R ₁ -A ₃ —” is the 1-position.

  Examples of the diamine represented by the general formula (IX) include diamines represented by the following formulas (IX-1) to (IX-48).

In formulas (IX-1) to (IX-11), R ₁₂ is preferably alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and alkyl having 5 to 12 carbons or alkoxy having 5 to 12 carbons. Is more preferable. R ₁₃ is preferably alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons, more preferably alkyl having 3 to 10 carbons or alkoxy having 3 to 10 carbons.

In the formulas (IX-12) to (IX-15), R ₁₄ is preferably alkyl having 4 to 16 carbons, and more preferably alkyl having 6 to 16 carbons. In Formula (IX-16) and Formula (IX-17), R ₁₅ is preferably alkyl having 6 to 20 carbons, and more preferably alkyl having 8 to 20 carbons.

In the formulas (IX-18) to (IX-38), R ₁₆ is preferably alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, alkyl having 3 to 20 carbons or alkoxy having 3 to 20 carbons. Is more preferable. R ₁₇ is preferably —H, —F, alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, —CN, —OCH ₂ F, —OCHF ₂ or —OCF ₃ , and alkyl having 3 to 20 carbons. Alternatively, alkoxy having 3 to 20 carbon atoms is more preferable. A ₉ is alkylene having 1 to 20 carbons.

  Among these, Preferably, the diamine represented by Formula (IX-1)-Formula (IX-11) is mentioned. More preferably, the diamine represented by Formula (IX-2), Formula (IX-4), Formula (IX-5), and Formula (IX-6) is mentioned.

In the general formula (XI), it is preferable that one of the two “NH ₂ —Ph-A ₆ —O—” is bonded to the 3-position of the steroid nucleus and the other is bonded to the 6-position. The two amino groups are each bonded to a phenyl ring carbon, and preferably bonded to meta or para with respect to the bonding position of A ₆ .

  Examples of the diamine represented by the general formula (XI) include diamines represented by the formulas (XI-1) to (XI-4).

In the general formula (XII), two “NH ₂ — (R ₈ —) Ph—A ₆ —O—” are each bonded to the phenyl ring carbon, but preferably to the carbon to which the steroid nucleus is bonded. In contrast, it is bound to meta or para carbon. The two amino groups are each bonded to the phenyl ring carbon, but are preferably bonded to meta or para to A ₆ .

  Examples of the diamine represented by the general formula (XII) include diamines represented by the formulas (XII-1) to (XII-8).

In the general formula (XIII), the two amino groups are each bonded to a phenyl ring carbon, but are preferably bonded to meta or para to A ₇ .

  Examples of the diamine represented by the general formula (XIII) include diamines represented by the formulas (XIII-1) to (XIII-9).

In formulas (XIII-1) to (XIII-9), R ₁₈ is preferably -H and alkyl having 1 to 20 carbons, and R ₁₉ is more preferably -H and alkyl having 1 to 10 carbons.

In the general formula (XIV), the two amino groups are each bonded to the phenyl ring carbon, but are preferably bonded to meta or para to A ₇ .

  Examples of the diamine represented by the general formula (XIV) include diamines represented by (XIV-1) to (XIV-3).

In formulas (XIV-1) to (XIV-3), R ₂₀ is preferably alkyl having 6 to ₂₀ carbon atoms,
R ₂₁ is more preferably —H and alkyl having 1 to 10 carbon atoms.

The diamine compound in the present invention may contain one kind of diamine represented by the general formulas (IX) , (XI) to (XIV), or may contain two or more kinds. The molar ratio of the diamine having a side chain structure in the diamine compound in the present invention may be adjusted according to the structure of the diamine having the selected side chain structure and the desired pretilt angle, and is 1 to 100%. Preferably, it is 5 to 80%.

Furthermore, the diamine represented by general formula (II)-(VIII) and the side chain structure represented by general formula (IX) , (XI) -(XIV) which may be contained in the diamine compound in this invention. A diamine other than the diamine is optional, but for example, a naphthalene diamine having a naphthalene structure, a fluorene diamine having a fluorene structure, a siloxane diamine having a siloxane bond, or general formulas (IX) 1 , Mention may also be made of diamines having side chain structures other than XIV).

  The siloxane-based diamine is not particularly limited, but those represented by the following general formula (XV) can be preferably used in the present invention.

In formula (XV), R ₂₂ and R ₂₃ are each independently alkyl or phenyl having 1 to 3 carbon atoms, and A ₁₀ is methylene, phenylene or alkyl-substituted phenylene. i represents an integer of 1 to 6, and j represents an integer of 1 to 10.

Furthermore, although the diamine which has side chains other than general formula (IX) , (XI) -(XIV) is not specifically limited, For example, what is represented by following formula (1 ')-(8') is shown. It can be preferably used in the present invention.

In formulas (1 ′) to (8 ′), R ₂₄ and R ₂₅ are independently alkyl having 3 to 20 carbons.

The diamines other than the general formulas (II) to (IX) and (XI) to (XIV) that can be included in the diamine compound in the present invention are not limited to the diamine, and the object of the present invention is achieved. It goes without saying that various other forms of diamine exist within the range. Moreover, this other diamine can be used individually by 1 type or in combination of 2 or more types.

  The diamine compound in the present invention can give a suitable pretilt angle to the liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention by appropriately selecting the type of diamine and the combination thereof.

  In the case of a VA type liquid crystal display element, a large pretilt angle of about 80 to 90 °, and in the case of an OCB type liquid crystal display element, a pretilt angle of about 7 to 20 ° has a TN type liquid crystal display element or STN type liquid crystal display element. In this case, a pretilt angle of about 3 to 10 ° is often required, and in the case of an IPS liquid crystal display element, a small pretilt angle of about 0 to 3 ° is often required. Therefore, the liquid crystal aligning agent of the present invention that can adjust the pretilt angle as appropriate can be applied to any kind of liquid crystal display element.

  Hereinafter, the diamine compound in the present invention will be described in relation to the driving method of the liquid crystal display element and the pretilt angle.

1) In the case of VA type liquid crystal display element In order to provide a large pretilt angle suitable for the VA type liquid crystal display element, as a diamine having a side chain structure, a diamine having both a phenylenediamine structure and a side chain structure, for example, the above formula Diamines represented by (IX-1) to (IX-48) can be particularly preferably used.

  When the diamine having a phenylenediamine structure has a main chain as a group connecting two amino groups, for example, the molecular length of the main chain structure portion is shorter than the diamines represented by the formulas (XI) to (XIV). Become. As a result, in the polyamic acid obtained by reacting the diamine with tetracarboxylic dianhydride or a derivative thereof, the spatial density of the side chain structure (side chain density) can be increased. It can use more suitably as a liquid crystal aligning agent of a display element.

  Furthermore, the diamine having both a phenylenediamine structure and a side chain structure includes diamines having other side chain structures, diamines represented by the general formulas (II) to (VIII), fluorene diamines, siloxane diamines, and the like. They can be used in combination.

2) For OCB type liquid crystal display elements, TN type liquid crystal display elements, STN type liquid crystal display elements A pretilt angle suitable for liquid crystal display elements such as OCB type liquid crystal display elements, TN type liquid crystal display elements, STN type liquid crystal display elements is given. In order to do so, a diamine having a side chain structure represented by the general formulas (IX) , (XI) to (XIV) can be preferably used. More preferably, a diamine having a side chain structure can be used in combination with a diamine represented by the above general formulas (II) to (VIII), a fluorene diamine, a siloxane diamine, or the like. The diamine compound in the present invention can give a suitable pretilt angle to the liquid crystal display element by appropriately selecting the kind of diamine and the combination thereof.

3) In the case of an IPS type liquid crystal display element In order to give a small pretilt angle suitable for an IPS type liquid crystal display element, preferably a diamine represented by the above general formulas (II) to (VIII), or a fluorene diamine, A siloxane diamine or the like can be used in combination. Furthermore, as long as a small pretilt angle suitable for an IPS liquid crystal display element can be obtained, a diamine having a side chain structure can also be used in combination.

  As described above, a part of the diamine contained in the diamine compound in the present invention may be substituted with a monoamine. By substituting a part of the diamine with a monoamine, the termination of the polymerization reaction can be caused, and further progress of the reaction can be suppressed, so the molecular weight of the resulting polymer (polyamic acid) can be easily controlled. be able to. The ratio of the monoamine to the diamine may be in a range that does not impair the effects of the present invention, but as a guideline, it is preferably 10 mol% or less of the total amine amount.

The polyamic acid or derivative thereof in the present invention can have any weight average molecular weight and is not particularly limited. However, when used as a component of a liquid crystal aligning agent, it is preferably 5 × 10 ³ or more, and 1 × 10 ^4. More preferably. The polyamic acid or derivative thereof having a weight average molecular weight of 5 × 10 ³ or more does not evaporate in the step of firing the alignment film, and has preferable physical properties as a component of the liquid crystal aligning agent.

About the upper limit of this weight average molecular weight, what is necessary is just a weight average molecular weight which becomes a preferable viscosity when it uses as a liquid crystal aligning agent, and the gelatinization of a liquid crystal aligning agent is suppressed, and is 5 * 10 as a standard. It is preferably ⁵ or less.

Here, the weight average molecular weight of the polyamic acid or its derivative is measured by a gel permeation chromatography (GPC) method. For example, the obtained polyamic acid or derivative thereof is diluted with dimethylformamide (DMF) so that the polyamic acid concentration is about 1% by weight,
Using Chromatopack C-R7A (manufactured by Shimadzu Corporation), it is measured by gel permeation chromatographic analysis (GPC) method using DMF as a developing agent, and obtained by polystyrene conversion. Furthermore, in order to perform GPC measurement such as polyamic acid and polyacrylic acid with high accuracy, the pH value of the developing agent and diluent may be adjusted to 2 to 6 with an inorganic acid such as phosphoric acid, hydrochloric acid, nitric acid or sulfuric acid. (See JP-A-60-73456).

The polyamic acid in this invention can be manufactured using a well-known method. For example, in a reaction vessel equipped with a raw material inlet, a nitrogen inlet, a thermometer, a stirrer, and a condenser, one kind of diamines represented by the general formulas (II) to (IX) and (XI) to (XIV) or Two or more kinds, one kind or two or more kinds of diamines selected from other diamines as the case may be, and a desired amount of monoamine as necessary.

  Next, a solvent (for example, N-methyl-2-pyrrolidone or dimethylformamide which is an amide polar solvent) and one of tetracarboxylic dianhydrides represented by the general formula (I) or (I ′) or Two or more types, and optionally one or two or more types of other tetracarboxylic dianhydrides, and a dicarboxylic acid as necessary. At this time, it is preferable that the total charge amount of tetracarboxylic dianhydride is approximately equal to the total number of moles of diamine (molar ratio of about 0.9 to 1.1).

  A polyamic acid solution can be obtained by reacting at a temperature of 0 to 70 ° C. for 1 to 48 hours under stirring. Moreover, the polyamic acid with a small molecular weight can also be obtained by heating and raising reaction temperature (for example, 50-80 degreeC).

  The polyamic acid in the present invention can be identified by precipitating with a large amount of a poor solvent, completely separating the solid and the solvent by filtration or the like, and analyzing by IR or NMR. Furthermore, after decomposing solid polyamic acid with an aqueous solution of strong alkali such as KOH or NaOH, the monomer used can be identified by extracting with an organic solvent and analyzing by GC, HPLC or GC-MS. it can.

  The obtained polyamic acid solution can be used by diluting with a solvent in order to adjust to a desired viscosity.

  In addition, when the polyamic acid in the present invention is a soluble polyimide that is a polyamic acid derivative, the resulting polyamic acid solution is used as an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride as a dehydrating agent. , And a tertiary amine such as triethylamine, pyridine, collidine, etc., which are dehydration ring closure catalysts, can be obtained by imidization reaction at a temperature of 20 to 150 ° C.

  Alternatively, polyamic acid is precipitated from the obtained polyamic acid solution using a large amount of poor solvent (alcohol solvent or glycol solvent such as methanol, ethanol, isopropanol), and the precipitated polyamic acid is converted into toluene, xylene, or the like. The imidization reaction can also be carried out at a temperature of 20 to 150 ° C. in a solvent together with the same dehydrating agent and dehydration ring closure catalyst as described above.

  In the imidization reaction, the ratio of the dehydrating agent to the dehydrating ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total use amount of both is preferably 1.5 to 10 times the molar amount of the total acid dianhydride contained in the tetracarboxylic dianhydride compound to be used. By adjusting the dehydrating agent, catalyst amount, reaction temperature and reaction time of this chemical imidization, the degree of imidization can be controlled to obtain a partial polyimide.

  The obtained polyimide can be separated from the solvent and redissolved in a solvent described later and used as a liquid crystal aligning agent, or can be used as a liquid crystal aligning agent without being separated from the solvent.

  As described above, a part of the acid dianhydride that can be contained in the tetracarboxylic dianhydride compound in the present invention may be substituted with an organic dicarboxylic acid. When the polyamic acid in this invention is manufactured using the tetracarboxylic dianhydride compound containing organic dicarboxylic acid, a polyamic acid-polyamide copolymer can be obtained. Here, the ratio of the dicarboxylic acid to the tetracarboxylic dianhydride may be in a range that does not impair the effects of the present invention, but as a guideline, it is preferably 10 mol% or less.

  Furthermore, polyamideimide can be produced by chemically imidizing the polyamic acid-polyamide copolymer.

  Another preferable form of the liquid crystal aligning agent of the present invention is a composition containing two or more kinds of polyamic acids or derivatives thereof.

  One kind of the polyamic acid or a derivative thereof is a polyamic acid obtained by reacting a tetracarboxylic dianhydride compound A1 with a diamine compound A2 containing a diamine represented by the general formulas (II) to (VIII) or a derivative thereof. Derivative A (hereinafter also referred to as “polyamic acid A”), and another type is a polyamic obtained by reacting a tetracarboxylic dianhydride compound B1 with a diamine compound B2 containing a diamine having a side chain structure. It is an acid or a derivative B thereof (hereinafter also referred to as “polyamic acid B”). A tetracarboxylic acid containing at least one of the tetracarboxylic dianhydride compound A1 and the tetracarboxylic dianhydride compound B1 contains the tetracarboxylic dianhydride represented by the general formula (I) or (I ′). It is a dianhydride compound.

  In the present invention, the tetracarboxylic dianhydride compound A1 and the tetracarboxylic dianhydride compound B1 are composed of one or more tetracarboxylic dianhydrides, but some of the tetracarboxylic dianhydrides are dicarboxylic. It may be substituted with an acid. Here, the ratio of the dicarboxylic acid to the tetracarboxylic dianhydride is preferably 10 mol% or less.

  The diamine compound A2 and the diamine compound B2 in the present invention are composed of one or more diamines, and a part of the diamine may be substituted with a monoamine. Here, the ratio of monoamine to diamine is preferably 10 mol% or less.

  Here, examples of the derivative of polyamic acid include soluble polyimide, polyamic acid ester, polyamic acid amide, and the like. More specifically, 1) polyimide in which all amino groups of polyamic acid and carboxylic acid are subjected to dehydration ring-closing reaction. 2) Partially dehydrated ring-closed partial polyimide, 3) Polyamic acid-polyamide copolymer obtained by reacting part of the acid dianhydride contained in the tetracarboxylic dianhydride compound with organic dicarboxylic acid. And 4) polyamideimide obtained by subjecting part or all of the polyamic acid-polyamide copolymer to a dehydration ring-closing reaction.

  In addition, the liquid crystal aligning agent as another preferable form of this invention may contain only polyamic acid A and B, and may further contain polyamic acid other than polyamic acid A and B, or its derivative (s).

As described above, the polyamic acid A and the polyamic acid B in the present invention are polyamic acid obtained by reacting a tetracarboxylic dianhydride compound and a diamine compound, or a derivative thereof, but the tetracarboxylic dianhydride compound. At least one of A1 and the tetracarboxylic dianhydride compound B1 is a tetracarboxylic dianhydride compound containing the tetracarboxylic dianhydride represented by the general formula (I) or (I ′).

  At least one of the tetracarboxylic dianhydride compounds may contain one kind of tetracarboxylic dianhydride represented by the general formula (I) or (I ′), or two or more kinds. May be. In at least one of the tetracarboxylic dianhydride compounds, the total content of the tetracarboxylic dianhydrides represented by the general formula (I) and / or (I ′) is the total content of the tetracarboxylic dianhydrides compound. It is preferably 10 to 100 mol%, more preferably 25 to 100 mol%. The liquid crystal alignment film formed using the liquid crystal aligning agent containing the polyamic acid synthesized from the tetracarboxylic dianhydride compound in the present invention has a good voltage holding ratio and a remarkable residual in a liquid crystal display element containing the same. A DC reduction effect can be imparted.

  Furthermore, the polyamic acid A in the present invention is a polyamic acid obtained by reacting a tetracarboxylic dianhydride compound A1 with a diamine compound A2 containing a diamine represented by the general formulas (II) to (VIII). Its derivatives.

  The diamine compound A2 is composed of one or more diamines and includes at least diamines represented by the general formulas (II) to (VIII). The liquid crystal alignment film formed using the liquid crystal aligning agent containing the polyamic acid synthesized from the diamine compound containing the diamine represented by the general formulas (II) to (VIII) is a liquid crystal display element including the same. A good voltage holding ratio and a remarkable residual DC reduction effect can be imparted.

The diamine compound A2 may further contain any other diamine as necessary. Here, as another diamine, the diamine represented by the said general formula (IX) , (XI) -(XIV), a fluorene type diamine, a siloxane type diamine, etc. are mentioned.

  The molar ratio of the diamines represented by the general formulas (II) to (VIII) in the diamine compound A2 depends on the structure of the selected diamines represented by the general formulas (II) to (VIII) and the desired voltage holding. It may be adjusted according to the rate and the residual DC reduction effect, preferably 1 to 100%, more preferably 5 to 80%.

  On the other hand, the polyamic acid B in the present invention is a polyamic acid obtained by reacting a tetracarboxylic dianhydride compound B1 with a diamine compound B2 containing a diamine having a side chain structure, or a derivative thereof. The liquid crystal alignment film formed by using a liquid crystal aligning agent containing a polyamic acid synthesized from a diamine compound containing a diamine having a side chain structure in the present invention gives a suitable pretilt angle to the liquid crystal display element containing the same. can do.

The diamine compound B2 is composed of one or more diamines, but includes at least a diamine having a side chain structure. Specific examples of the diamine having a side chain structure include diamines represented by the general formulas (IX) and (XI) to (XIV).

  The diamine compound B2 may further contain any other diamine as necessary. Here, examples of the other diamines include diamines represented by the general formulas (II) to (VIII), fluorene-based diamines, and siloxane-based diamines.

  The molar ratio of the diamine having a side chain structure in the diamine compound B2 may be adjusted according to the structure of the diamine having the selected side chain structure and the desired pretilt angle, and is preferably 1 to 100%. More preferably, it is 5 to 80%.

  By combining (blending) the polyamic acid A and the polyamic acid B in the present invention, preferable characteristics as a component of the liquid crystal aligning agent of the present invention can be imparted.

  Specifically, for the diamine compounds A2 and B2 that are the raw materials for polyamic acid, by appropriately selecting the type of diamine and the combination thereof, the liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention, Furthermore, a good voltage holding ratio, a remarkable residual DC reduction effect, and a suitable pretilt angle can be provided.

  The weight average molecular weight and molecular weight distribution of the polyamic acid A and the polyamic acid B in the present invention are measured by the same method as the polyamic acid or the derivative thereof in the present invention described above. The preferred weight average molecular weight is also the same as that of the polyamic acid or derivative thereof in the present invention described above.

  The polyamic acid A and the polyamic acid B in the present invention can be produced in the same manner as the polyamic acid or the derivative thereof in the present invention described above.

<2. Liquid crystal aligning agent of the present invention>
The liquid crystal aligning agent of the present invention includes the polyamic acid or derivative thereof according to the present invention described above, the composition of the polyamic acid A and polyamic acid B described above, and a solvent, and various additives contained in a normal liquid crystal aligning agent. May be further included as necessary.

  In addition, the composition of the polyamic acid A and the polyamic acid B in this invention is prepared by mixing the above-mentioned polyamic acid A and the polyamic acid B. The weight ratio of the polyamic acid A and the polyamic acid B to be mixed is preferably A / B = 99/1 to 50/50, and more preferably A / B = 95/5 to 80/20. The weight ratio may be appropriately adjusted according to the required pretilt angle, and the pretilt angle can be increased by increasing the ratio of polyamic acid B.

  The content rate of the polyamic acid or its derivative in the liquid crystal aligning agent of this invention can be suitably selected with the coating method to the board | substrate of a liquid crystal aligning agent. For example, a polyamic acid in a liquid crystal aligning agent used in a printing machine (including an offset printing machine and an ink jet printing machine, which may be abbreviated as “printing machine” hereinafter) used in a manufacturing process of a normal liquid crystal display element. The content of the derivative is preferably 0.5 to 30% by weight, more preferably 1 to 15% by weight, but it is appropriately adjusted in relation to the viscosity (described later) of the liquid crystal aligning agent. The

  The solvent used in the present invention includes a wide variety of solvents usually used in the production process and applications of polymer components such as polyamic acid, soluble polyimide, and polyamideimide, and can be appropriately selected depending on the purpose of use. The solvent is a mixed solvent containing 1) an aprotic polar organic solvent that is insoluble in polyamic acid and soluble polyimide, and 2) a solvent for improving coating properties by changing the surface tension. Is preferred.

Examples of these solvents are as follows.
1) Aprotic polar organic solvent (hereinafter referred to as aprotic polar organic solvent) which is a parent solvent for polyamic acid and soluble polyimide: for example, N-methyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N, N-dimethylacetamide, dimethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, diethylacetamide, γ-butyrolactone, and γ-valerolactone. Of these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, γ-valerolactone, and the like are more preferred.

  2) Solvents for improving coating properties by changing surface tension (hereinafter referred to as other solvents): for example, ethylene glycol such as alkyl lactate, 3-methyl-3-methoxybutanol, tetralin, isophorone, ethylene glycol monobutyl ether Monoalkyl ether, diethylene glycol monoalkyl ether such as diethylene glycol monoethyl ether, ethylene glycol monoalkyl or phenyl acetate, propylene glycol monoalkyl ether such as triethylene glycol monoalkyl ether, propylene glycol monobutyl ether, dialkyl malonate such as diethyl malonate Dipropylene glycol monoalkyl ether such as dipropylene glycol monomethyl ether, ester compounds such as these acetates That. Of these, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and the like are more preferred.

  The types and ratios of the aprotic polar solvent and the other solvent can be appropriately set in consideration of the printability, coatability, solubility, storage stability, and the like of the liquid crystal aligning agent. Aprotic polar solvents are relatively superior in solubility and storage stability to other solvents, and other solvents tend to be excellent in printability and coatability.

  As described above, the liquid crystal aligning agent of the present invention may contain various additives. As various additives, a polymer compound other than polyamic acid or a derivative thereof, or a low molecular compound can be selected and used according to each purpose.

  For example, a polymer compound soluble in an organic solvent may be used as an additive, and by adding them, the electrical characteristics and orientation of the formed alignment film can be controlled. Examples of the polymer compound include polyamide, polyurethane, polyurea, polyester, polyepoxide, polyester polyol, silicone-modified polyurethane, and silicone-modified polyester.

  Examples of additives for low molecular weight compounds include 1) a surfactant in accordance with the purpose when improvement in coating properties is desired, 2) an antistatic agent when improvement in antistatic properties is required, and 3) When it is desired to improve the adhesion to the substrate and the rubbing property, a silane coupling agent or a titanium coupling agent can be used.

  Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and N- (2-aminoethyl) -3-aminopropyl. Methyltrimethoxysilane, paraaminophenyltrimethoxysilane, paraaminophenyltriethoxysilane, metaaminophenyltrimethoxysilane, metaaminophenyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycyl Sidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyl Pyrtrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine, N, N Examples include '-bis [3- (trimethoxysilyl) propyl] ethylenediamine.

  The addition amount of these additives is 0 to 10% by weight, preferably 0.1 to 3% by weight, based on the total weight of the polyamic acid and its derivatives.

  The viscosity of the liquid crystal aligning agent of the present invention varies depending on the coating method, the concentration of the polyamic acid and its derivative, the type of polyamic acid and its derivative used, and the type and ratio of the solvent. For example, in the case of application by a printing press, it is 5 to 100 mPa · s (more preferably 10 to 80 mPa · s). If it is less than 5 mPa · s, it is difficult to obtain a sufficient film thickness, and if it exceeds 100 mPa · s, printing unevenness may increase. In the case of application by spin coating, 5 to 200 mPa · s (more preferably 10 to 100 mPa · s) is suitable. The viscosity of the liquid crystal aligning agent is measured by a rotational viscosity measuring method, and is measured using a rotational viscometer (TVE-20L type manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25 ° C.).

<3. Liquid crystal display element of the present invention>
The liquid crystal display element of the present invention includes 1) a pair of substrates arranged opposite to each other, 2) electrodes formed on one or both of the opposed surfaces of each of the pair of substrates, and 3) each of the pair of substrates. A liquid crystal alignment film formed on the opposing surfaces; and 4) a liquid crystal layer sandwiched between the pair of substrates.

  The substrate is preferably a transparent substrate (for example, a glass substrate). The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. This electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired shape that is patterned, for example. Such electrodes include, for example, ITO and metal deposition films, and examples of the desired shape of the electrodes include a comb shape or a zigzag structure. The electrode may be formed on one of the pair of substrates, or may be formed on both substrates. For example, electrodes may be disposed on both of the pair of substrates, but in the case of an IPS liquid crystal display element, electrodes are disposed on one of the pair of substrates.

  The liquid crystal alignment film is formed by applying and heating the liquid crystal alignment agent of the present invention to the substrate. Here, the film thickness of the liquid crystal alignment film is preferably 10 to 300 nm, and more preferably 30 to 100 nm. The liquid crystal alignment film is preferably rubbed.

  The liquid crystal layer sandwiched between the pair of substrates includes a liquid crystal composition. Here, the liquid crystal composition is not particularly limited, and either a liquid crystal composition having a positive dielectric anisotropy or a liquid crystal composition having a negative dielectric anisotropy may be used depending on the driving mode. it can.

  Examples of preferred liquid crystal compositions having a positive dielectric anisotropy that can be used in the present invention include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Laid-Open No. 5-501735, and Japanese Patent Laid-Open No. Hei 8-. 157826, JP-A-8-231960, JP-A-9-241644 (EP88272A1), JP-A-9-302346 (EP806466A1), JP-A-8-199168 (EP722998A1), JP-A-9-235552. JP-A-9-255596, JP-A-9-241463 (EP882711A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, Special JP 2000-087040, JP 2001-4 It disclosed in 822 Publication.

The liquid crystal composition used in the VA liquid crystal display element can be various liquid crystal compositions having negative dielectric anisotropy. Examples of preferred liquid crystal compositions that can be used in the present invention include JP-A-57-114532, JP-A-2-4725, JP-A-4-222485, JP-A-8-40953, and JP-A-5-40953. JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP-A-10- 23
No. 6993, JP-A-10-236994, JP-A-10-237000, JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075 JP-A-10-237076, JP-A-10-237448 (EP967261A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581 JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP-A-2001-072626, JP-A-2001-192657, and the like.

  One or more optically active compounds may be added to the liquid crystal composition having a positive or negative dielectric anisotropy.

Of course, the liquid crystal display element of the present invention may have other members.
For example, in a TFT-type liquid crystal element for color display using a thin film transistor, a thin film transistor, an insulating film, a protective film, a signal electrode, a pixel electrode, and the like are formed on a first transparent substrate, A black matrix, a color filter, a planarization film, a pixel electrode, and the like that block light outside the pixel region may be included.

  Further, in a VA liquid crystal display element, in particular, an MVA liquid crystal display element, a minute protrusion called a domain is formed on a first transparent substrate. A spacer may be formed for adjusting the cell gap between the substrates.

  The liquid crystal display element of the present invention can be manufactured by any method. For example, 1) a liquid crystal aligning agent on the surface having electrodes if the substrate has electrodes on two transparent substrates having electrodes on at least one substrate. 2) Step of drying the applied liquid crystal aligning agent, 3) Step of performing heat treatment necessary for dehydrating and ring-closing reaction of the dried liquid crystal aligning agent, 4) Obtained liquid crystal alignment film 5) A step of aligning the liquid crystal as necessary, 5) A step of sealing the two substrates so that the alignment liquid crystal alignment films face each other, and then encapsulating the liquid crystal between the substrates, or the liquid crystal on one substrate After dripping, it is manufactured by a method including a step of bonding to another substrate.

  As a coating method in the step of applying the liquid crystal aligning agent, a spinner method, a printing method, a dipping method, a dropping method, an ink jet method and the like are generally known. These methods are also applicable in the present invention.

  Further, as a method of the drying step and a step of performing a heat treatment necessary for the dehydration / ring closure reaction, a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, etc. are generally known. . These methods are also applicable in the present invention. The drying step is preferably performed at a relatively low temperature (50 to 100 ° C.) within a range where the solvent can be evaporated. In general, the heat treatment step is preferably performed at a temperature of about 150 to 300 ° C.

  The alignment process is usually performed by a rubbing process in which a liquid crystal alignment film formed on a substrate is rubbed in a predetermined direction with a rubbing cloth, but may not be performed depending on the type of liquid crystal display element to be manufactured. For example, an OCB type liquid crystal display element, a TN type liquid crystal display element, an STN type liquid crystal display element, and an IPS type liquid crystal display element are usually rubbed. In many cases, the VA liquid crystal display element is not subjected to the rubbing treatment.

  Next, an adhesive is applied onto one substrate, and the liquid crystal is injected in a vacuum. In the case of the dropping injection method, the liquid crystal is dropped on the substrate before bonding, and then bonded on the other substrate. The liquid crystal display element of the present invention is produced by curing the adhesive used for bonding with heat or ultraviolet rays.

  In the liquid crystal display element of the present invention, a polarizing plate (polarizing film), a wave plate, a light scattering film, a driving circuit, and the like may be further mounted.

  The liquid crystal alignment film used for the VA type liquid crystal display element preferably gives a pretilt angle of about 80 to 90 °, and the liquid crystal alignment film used for the OCB type liquid crystal display element is about 5 to 45 °, preferably 7 to 20 °. It is preferable to give a pretilt angle of about, and a liquid crystal alignment film used for a TN liquid crystal display element or an STN liquid crystal display element preferably gives a pretilt angle of about 3 to 10 °, and is used for an IPS liquid crystal display element. The liquid crystal alignment film preferably gives a pretilt angle of about 0 to 3 °. As described above, the pretilt angle is mainly adjusted by 1) the kind of diamine having a side chain structure in the present invention, and the molar ratio of the diamine having a side chain structure in the diamine compound in the present invention. This is achieved by adjusting the weight ratio of polyamic acids A and B in the liquid crystal aligning agent.

  In addition, the liquid crystal display element of the present invention is characterized by high voltage holding ratio and low residual DC. This is because the liquid crystal alignment film of the liquid crystal display element of the present invention is synthesized using a tetracarboxylic dianhydride compound containing the tetracarboxylic dianhydride represented by the general formula (I) or (I ′). This is because it is formed of a liquid crystal aligning agent containing polyamic acid or a derivative thereof. This is also explained in the examples described later.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In addition, the name of the tetracarboxylic dianhydride used in an Example, diamine, and a solvent may be shown with the following abbreviations.

[Tetracarboxylic dianhydride]
3,3 ′-(1,2-ethane-diyl) bis (1,2-dimethylcyclobutane-1,2-dicarboxylic anhydride) {formula (I-9)}: 2DMCB
Pyromellitic dianhydride {(1)}: PMDA
1,2,3,4-cyclobutanetetracarboxylic dianhydride {(14)}: CBDA

[Diamine]
4,4′-Diaminodiphenylmethane {Formula (VI-1)}: DDM
p-phenylenediamine {formula (V-1)}: PDA
1,1-bis {4-[(4-aminophenyl) methyl] phenyl} -4-n-butylcyclohexane {formula (XIII-2) / R ₁₈ = C ₄ H ₉ }: 4Ch
5- {4- [2- (4- n- heptyl cyclohexyl) ethyl] cyclohexyl} phenyl-1,3-diaminobenzene {formula _{(IX-6) / R 13} = C 7 H 15}: 7Ch2Ch

[solvent]
N-methyl-2-pyrrolidone: NMP
γ-butyrolactone: GBL
Butyl cellosolve (ethylene glycol monobutyl ether): BC

<1. Synthesis of polyamic acid>
[Synthesis of polyamic acid]
Synthesis example 1
In a 100 mL four-necked flask equipped with a thermometer, a stirrer, a raw material charging charge port and a nitrogen gas inlet port, 2.0892 g (10.54 mmol) of DDM and 30 g of dehydrated NMP were placed and dissolved under stirring in a dry nitrogen stream. Next, 1.1492 g (5.27 mmol) of PMDA and 1.7616 g (5.27 mmol) of 2DMCB were added and reacted for 30 hours in a room temperature environment. When the reaction temperature rose during the reaction, the reaction temperature was kept at about 70 ° C. or lower for the reaction.

  GBL30g and BC35g were added to the obtained solution, and the polyamic acid solution (PA1) with a density | concentration of 5 weight% was synthesize | combined. The viscosity of PA1 obtained was 20 mPa · s. Moreover, the weight average molecular weight of the produced polyamic acid was 38,000.

  Here, the weight average molecular weight of the polyamic acid is the concentration of polyamic acid in a diluted solution (phosphoric acid / DMF = 0.6 / 100: weight ratio) obtained by diluting the obtained polyamic acid with dimethylformamide (DMF). Was diluted to about 1% by weight, and was measured by GPC method using Chromatopack C-R7A (manufactured by Shimadzu Corporation) with the above diluent as a developing agent and converted to polystyrene. In addition, the column used GF-7HQ (made by Showa Denko KK), and measured it on conditions with a column temperature of 50 degreeC and the flow rate of 0.6 ml / min.

Synthesis Example 2 and Synthesis Example 3
A polyamic acid solution (PA2, PA3) was synthesized according to Synthesis Example 1 except that the composition of tetracarboxylic dianhydride, diamine and solvent was changed to the ratio shown in Table 1. The viscosity of PA2 obtained was 19 mPa · s. The viscosity of PA3 obtained was 12 mPa · s. The results are summarized in Table 1 including Synthesis Example 1.

<2. Production of liquid crystal display element>
[Example 1]
The polyamic acid solution (PA1) having a concentration of 5% by weight synthesized in Synthesis Example 1 was diluted to 3% by weight with a mixed solvent of NMP / BC = 1/1 (weight ratio) to obtain a liquid crystal aligning agent. Using the obtained liquid crystal aligning agent, an IPS liquid crystal display element was produced as follows.

2. Manufacturing method of IPS type liquid crystal display element Two glass substrates of the glass substrate with the comb-like electrode for IPS shown in FIG. 1 and the glass substrate without electrodes were used. The liquid crystal aligning agent was apply | coated with the spinner on the glass substrate with an interdigital electrode for IPS, and the glass substrate without an electrode, and the film | membrane with a film thickness of 100 nm was formed. After the coating, it was heated and dried at 80 ° C. for about 5 minutes, and then heat-treated at 220 ° C. for 30 minutes to form a liquid crystal alignment film.

Each of the two substrates on which the alignment film is formed is rubbed with a rubbing cloth (hair length 1.9 mm: rayon) using a rubbing treatment apparatus manufactured by Iinuma Gauge Co., Ltd. The rubbing treatment was performed so as to have an inclination of 15 ° with respect to the extending direction of the electrodes extending in a comb shape under the conditions of a speed of 60 mm / sec and a roller rotation speed of 1,000 rpm.

  The rubbed substrate was ultrasonically cleaned in ultrapure water for 5 minutes and then dried in an oven at 120 ° C. for 30 minutes. A 4 μm gap material was sprayed on the glass substrate with comb-like electrodes for IPS. With the surface on which the liquid crystal alignment film was formed facing inward, a glass substrate without electrodes was placed opposite to the glass substrate with comb-like electrodes for IPS so that the rubbing direction of the glass substrate was reverse and parallel. After that, the space between both glass substrates was sealed with an epoxy curing agent to produce an anti-parallel cell with a gap of 4 μm. The following liquid crystal composition A was injected into the cell, and the injection port was sealed with a photocuring agent. Next, a heat treatment was performed at 110 ° C. for 30 minutes to produce an IPS liquid crystal display element. The nematic / isotropic phase transition temperature (NI) of the liquid crystal composition A is 100.0 ° C., the refractive index anisotropy (Δn) is 0.093, and the dielectric anisotropy (Δε) is 5 .1.

[Example 2]
The polyamic acid solution (PA1) having a concentration of 5% by weight synthesized in Synthesis Example 1 and the polyamic acid solution (PA2) synthesized in Synthesis Example 2 were mixed at a weight ratio of 9/1. The obtained mixture was diluted to 4% by weight with a mixed solvent of NMP / BC = 1/1 (weight ratio) to obtain a liquid crystal aligning agent. Using the obtained liquid crystal aligning agent, a TN liquid crystal display element was produced as follows.

Preparation of TN type liquid crystal display element A liquid crystal aligning agent was applied to two glass substrates with an ITO electrode by a spinner to form a film having a thickness of 70 nm. After coating, the film was heated and dried at 80 ° C. for about 5 minutes, and then heat-treated at 220 ° C. for 30 minutes to form a liquid crystal alignment film.

One glass substrate on which the liquid crystal alignment film is formed is moved by a rubbing cloth (hair leg length: 1.9 mm: rayon) using a rubbing treatment apparatus manufactured by Iinuma Gauge Co., Ltd. The rubbing process was performed under the conditions of a speed of 60 mm / sec and a roller rotation speed of 1,000 rpm. The other glass substrate was similarly rubbed by changing the rubbing direction by 90 ° so as to be orthogonal to the rubbing direction of the other glass substrate. The substrate was ultrasonically cleaned in ultrapure water for 5 minutes and then dried in an oven at 120 ° C. for 30 minutes. A gap material of 7 μm was sprayed on one glass substrate.

  Both glass substrates were placed facing each other so that the surface on which the liquid crystal alignment film was formed was inward and the rubbing directions were orthogonal, and the space between both glass substrates was sealed with an epoxy curing agent, and a 90 ° twist cell with a gap of 7 μm was formed. Produced. Into the cell, a composition obtained by adding 5 parts by mass of cholesteric nonanoate, which is an optically active substance, to 100 parts by mass of the liquid crystal composition A was injected, and the injection port was sealed with a photocuring agent. Next, a heat treatment was performed at 110 ° C. for 30 minutes to produce a TN type liquid crystal display element.

[Example 3]
The polyamic acid solution (PA1) having a concentration of 5% by weight synthesized in Synthesis Example 1 and the polyamic acid solution (PA3) synthesized in Synthesis Example 3 were mixed at a weight ratio of 9/1. The obtained mixed liquid was diluted to 4% by weight with a mixed solvent of NMP / BC = 1/1 (weight ratio) to obtain a liquid crystal aligning agent. Using the obtained liquid crystal aligning agent, a VA liquid crystal display element was produced as follows.

Manufacturing method of VA type liquid crystal display element A liquid crystal aligning agent was apply | coated to the glass substrate with two ITO electrodes with the spinner, and the film | membrane with a film thickness of 70 nm was formed. After coating, the film was heated and dried at 80 ° C. for about 5 minutes, and then heat-treated at 220 ° C. for 30 minutes to form a liquid crystal alignment film.

  Using a rubbing treatment apparatus manufactured by Iinuma Gauge Co., Ltd., the glass substrate on which the liquid crystal alignment film was formed was rubbed with a rubbing cloth (hair leg length 1.9 mm: rayon), the amount of pushing the hair foot 0.30 mm, and the stage moving speed The rubbing process was performed under the conditions of 60 mm / sec and a roller rotation speed of 1,000 rpm. The glass substrate on which the liquid crystal alignment film was formed was ultrasonically cleaned in ultrapure water for 5 minutes and then dried in an oven at 120 ° C. for 30 minutes.

  4 μm gap material is sprayed on one glass substrate, and the surface on which the liquid crystal alignment film is formed is placed inside so that the rubbing direction is opposite and parallel to each other, and then the space between both glass substrates is epoxy-cured. The mixture was sealed with an agent to produce an anti-parallel cell with a gap of 4 μm. Liquid crystal composition B described below was injected into the cell, and the injection port was sealed with a photocuring agent. Next, heat treatment was performed at 110 ° C. for 30 minutes, and a VA liquid crystal display element was manufactured. The nematic / isotropic phase transition temperature (NI) of the liquid crystal composition B is 75.4 ° C., the refractive index anisotropy (Δn) is 0.081, and the dielectric anisotropy (Δε) is −. 3.4.

<3. Evaluation of electrical characteristics>
[Test Examples 1 to 3]
About the liquid crystal display element produced in Examples 1-3, the electrical property and the pretilt angle were evaluated. Specifically, the electrical characteristics were 1) voltage holding ratio, 2) residual DC by flicker free method, and 3) residual DC by dielectric absorption method. Each measurement was performed as follows.

1) Measurement of voltage holding ratio The voltage holding ratio was measured using a liquid crystal property evaluation apparatus 6254 type manufactured by Toyo Technica. The measurement conditions were a gate width of 60 μs, a frequency of 0.3 Hz, a wave height of ± 5 V, and a measurement temperature of 60 ° C. The larger this value, the better the electrical characteristics.

2) Measurement of residual DC by flicker free method 2-1) In case of IPS type liquid crystal display element (Test Example 1)
Using FG-110 manufactured by Yokogawa Electric Corporation, a DC voltage of 1 V was superimposed on a 30 Hz, 2 V rectangular wave and applied for 30 minutes. The flicker erasing voltage was measured for 30 minutes immediately after the application was completed.

The table shows the flicker erasing voltage immediately after the end of application and the flicker erasing voltage after 10 minutes as initial values. The measurement temperature was 25 ° C. The closer this value is to 0 (zero), the better the electrical characteristics.

2-2) In the case of a TN liquid crystal display element (Test Example 2)
Using FG-110 manufactured by Yokogawa Electric Corporation, a DC voltage of 3 V was superimposed on a 30 Hz, 2 V rectangular wave and applied for 30 minutes. The flicker erasing voltage was measured for 30 minutes immediately after the application was completed.

  The table shows the flicker erasing voltage immediately after the end of application and the flicker erasing voltage after 10 minutes as initial values. The measurement temperature was 25 ° C. The closer this value is to 0 (zero), the better the electrical characteristics.

2-3) In the case of VA type liquid crystal display element (Test Example 3)
Using FG-110 manufactured by Yokogawa Electric Corporation, a DC voltage of 1 V was superimposed on a 30 Hz, 5.5 V rectangular wave and applied for 30 minutes. The flicker erasing voltage was measured for 30 minutes immediately after the application was completed.

  The table shows the flicker erasing voltage immediately after the end of application and the flicker erasing voltage after 10 minutes as initial values. The measurement temperature was 25 ° C. The closer this value is to 0 (zero), the better the electrical characteristics.

3) Measurement of residual DC by dielectric absorption method Residual DC was measured by dielectric absorption method using a liquid crystal property evaluation apparatus 6254 type manufactured by Toyo Technica. Measurement conditions were as follows: DC 5V was applied to the cell for 1 hour, then the electrodes were shorted for 1 second, and then the potential difference between the electrodes was observed for 30 minutes. The table lists the maximum residual DC and the minimum residual DC. The measurement temperature is 60 ° C. It can be said that the smaller this value, the better the electrical characteristics.

4) Measurement of pretilt angle The pretilt angles in Examples 1 to 3 were measured according to Journal of Applied Physics, Vol. 48, no. 5, p. 1783-1792 (1977), and measured based on the crystal rotation method.

  About the liquid crystal display element produced in Example 1 and 2, it calculated | required from the tilt angle-retardation curve of the sample using the Chuo Seiki liquid crystal characteristic evaluation apparatus OMS-CA3 type | mold. About the liquid crystal display element produced in Example 3, it calculated | required from the tilt angle-light transmission amount curve of the sample under crossed Nicols. The measurement conditions of the pretilt angle in Examples 1 to 3 were a light spot diameter of 1 mm, a measurement temperature of 25 ° C., and a tilt angle of the sample of −60 to 60 °.

As shown in Table 2, the voltage holding ratio of each liquid crystal display element was 94% or more.
On the other hand, it can be seen that the residual DC is remarkably suppressed by any measurement method. It can be seen that the pretilt angle has a suitable value for the IPS liquid crystal display element in Example 1, the TN liquid crystal display element in Example 2, and the VA liquid crystal display element in Example 3.

  As mentioned above, the liquid crystal aligning agent containing the polyamic acid and its derivative in this invention can be used for formation of the liquid crystal aligning film of the liquid crystal display element of a various display drive system. In any display driving type liquid crystal display element, the voltage holding ratio is high and the residual DC is suppressed.

It is a figure which shows the comb-tooth electrode structure for IPS in the glass substrate with the comb-tooth electrode for IPS used in the present Example.

Explanation of symbols

  R Arrow indicating the wrapping direction of the glass substrate shown in FIG.

Claims (27)

A liquid crystal containing a polyamic acid or a derivative thereof obtained by reacting a tetracarboxylic dianhydride compound containing a tetracarboxylic dianhydride represented by the following general formula (I) or (I ′) with a diamine compound Alignment agent.

[In the formulas (I) and (I ′), R is independently —H or alkyl having 1 to 10 carbons, and X and Y are independently a single bond or — (CH ₂ ) _n —. Where n is an integer from 1 to 10. ] The tetracarboxylic dianhydride represented by the general formula (I) is represented by the following formulas (I-1), (I-2), (I-3), (I-7), (I-8) and The tetracarboxylic dianhydride which is at least one selected from the group consisting of the compounds of (I-9) and represented by the general formula (I ′) is represented by the following formulas (I′-1), (I '-2), (I'-3), (I'-7), (I'-8) and at least one selected from the group consisting of compounds of (I'-9), The liquid crystal aligning agent of Claim 1 to do.

  The liquid crystal aligning agent according to claim 2, wherein the tetracarboxylic dianhydride represented by the general formula (I) is a compound of the formula (I-9).   The liquid crystal aligning agent according to claim 1, wherein the tetracarboxylic dianhydride compound further includes an aromatic tetracarboxylic dianhydride.   The liquid crystal aligning agent according to claim 4, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride.   The liquid crystal aligning agent according to claim 1, wherein the tetracarboxylic dianhydride compound further includes an alicyclic tetracarboxylic dianhydride.   The liquid crystal aligning agent according to claim 6, wherein the alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride. The liquid crystal aligning agent according to claim 1, wherein the diamine compound contains a diamine represented by the following general formulas (II) to (VIII).

[In the formula (II),
A ₁ is — (CH ₂ ) _m —, where m is an integer of 1 to 12,
In the formulas (IV), (VI), (VIII),
A ₁ is a single bond, —O—, —S—, —S—S—, —SO ₂ —, —CO—, —CONH—, —NHCO—, —C (CH ₃ ) ₂ —, —C ( CF ₃ ) ₂ —, — (CH ₂ ) _m —, —O— (CH ₂ ) _m —O— or —S— (CH ₂ ) _m —S—, wherein m is an integer of 1 to 12. Yes,
In formulas (VII) and (VIII)
A ₂ is independently a single bond, —O—, —S—, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or alkylene having 1 to 3 carbon atoms,
Hydrogen bonded to a cyclohexane ring or a benzene ring in the formula (III) ~ (VIII) it is, -F independently may be replaced with -CH _3. ] The diamine compound is at least one selected from the group consisting of p-phenylenediamine, m-phenylenediamine, and compounds of the following formulas (VI-1) to (VI-12). 8. A liquid crystal aligning agent according to 8.

  The liquid crystal aligning agent according to claim 9, wherein the diamine compound is p-phenylenediamine or a compound of the formula (VI-1).   The said diamine compound contains the diamine which has a side chain structure, The liquid crystal aligning agent as described in any one of Claims 1-10 characterized by the above-mentioned. The liquid crystal aligning agent according to claim 11, wherein the diamine having a side chain structure is a diamine represented by the following general formulas (IX) and (XI) to (XIV).

[In the formula (IX),
A ₃ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH— or — (CH ₂ ) _m —, wherein m is an integer of 1 to 6,
R ₁ is a group having a steroid skeleton, a group represented by the following formula (X), an alkyl having 1 to 20 carbons when the positional relationship between two amino groups bonded to the benzene ring is para, or When the positional relationship is meta, it is alkyl or phenyl having 1 to 10 carbon atoms,
In the alkyl, any —CH ₂ — may be independently replaced by —CF ₂ —, —CHF—, —O—, —CH═CH— or —C≡C—, ₃ may be replaced by —CH ₂ F, —CHF ₂ or —CF ₃ ,
Hydrogen bonded to the phenyl ring-forming carbon, -F _{independently, -CH 3, -OCH 3, -OCH} 2 F, may be replaced with -OCHF ₂ or -OCF _3. ]

[In Formula (X),
A ₄ and A ₅ are each independently a single bond, —O—, —COO—, —OCO—, —CONH—, —CH═CH—, or alkylene having 1 to 20 carbon atoms,
R ₂ and R ₃ are each independently —F or —CH ₃ ;
Ring S is 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5- Diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl;
R ₄ is —H, —F, alkyl having 1 to 20 carbon atoms, fluorine-substituted alkyl having 1 to 20 carbon atoms, alkoxy having 1 to 20 carbon atoms, —CN, —OCH ₂ F, —OCHF ₂ or —OCF _3. And
a and b each independently represent an integer of 0 to 4, and when a or b is 2 to 4, adjacent A ₄ or A ₅ are different groups;
c, d and e each independently represent an integer of 0 to 3, and when e is 2 or 3, the plurality of rings S may be the same group or different groups,
f and g each independently represent an integer of 0 to 2 and c + d + e ≧ 1. ]

[In Formula (XI), the hydrogen bonded to the carbon forming the steroid skeleton may be independently replaced with —CH ₃ ;
In formulas (XI) and (XII)
Each R ₅ is independently —H or —CH ₃ ;
Each R ₆ is independently —H or an alkyl or alkenyl having 1 to 20 carbon atoms;
Each A ₆ is independently a single bond, —C (═O) — or —CH ₂ —;
In formula (XII),
R ₇ and R ₈ are each independently —H, C 1-20 alkyl or phenyl. ]

[In the formula (XIII),
R ₉ is —H or alkyl having 1 to 20 carbons, and any —CH ₂ — in the alkyl having 2 to 20 carbons is independently —O—, —CH═CH— or —. C≡C- may be substituted,
In formulas (XIII) and (XIV),
A ₇ is independently —O— or alkylene having 1 to 6 carbons,
In formula (XIII),
A ₈ is a single bond or alkylene having 1 to 3 carbon atoms,
Ring T is 1,4-phenylene or 1,4-cyclohexylene,
h is 0 or 1,
In formula (XIV),
R ₁₀ is alkyl having 6 to 22 carbon atoms,
R ₁₁ is —H or alkyl having 1 to 22 carbons. ] The diamine having the side chain structure is at least selected from the group consisting of compounds of the following formulas (IX-2), (IX-4), (IX-5), (IX-6) and (XIII-2) It is one, The liquid crystal aligning agent of Claim 12 characterized by the above-mentioned.

[In the formula (IX-2), R ₁₂ is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and in formulas (IX-4) to (IX-6), R ₁₃ is 1 carbon. Or an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ₁₈ is —H or alkyl having 1 to 20 carbon atoms in the formula (XIII-2). ] The diamine having the side chain structure is a compound in which R ₁₃ is C ₇ H ₁₅ in the formula (IX-6) or a compound in which R ₁₈ is C ₄ H ₉ in (XIII-2). The liquid crystal aligning agent of Claim 13.   A polyamic acid or a derivative thereof obtained by reacting the compound of formula (I-9) and pyromellitic dianhydride with the compound of formula (VI-1). The liquid crystal aligning agent as described in any one of 1-10. A liquid crystal aligning agent containing two or more polyamic acids or derivatives thereof,
A) a polyamic acid obtained by reacting a tetracarboxylic dianhydride compound A1 with a diamine compound A2 containing a diamine represented by the following general formulas (II) to (VIII), or a derivative A thereof, and B) tetracarboxylic A liquid crystal aligning agent containing a polyamic acid obtained by reacting the acid dianhydride compound B1 and a diamine compound B2 containing a diamine having a side chain structure, or a derivative B thereof;
At least one of the tetracarboxylic dianhydride compound A1 and the tetracarboxylic dianhydride compound B1 contains a tetracarboxylic dianhydride represented by the following general formula (I) or (I ′): Liquid crystal aligning agent characterized by being a compound.

[In the formulas (I) and (I ′), R is independently —H or alkyl having 1 to 10 carbons, and X and Y are independently a single bond, — (CH ₂ ) _n —. Where n is an integer from 1 to 10. ]

[In the formula (II),
A ₁ is — (CH ₂ ) _m —, where m is an integer of 1 to 12,
In the formulas (IV), (VI), (VIII),
A ₁ is a single bond, —O—, —S—, —S—S—, —SO ₂ —, —CO—, —CONH—, —NHCO—, —C (CH ₃ ) ₂ —, —C ( CF ₃ ) ₂ —, — (CH ₂ ) _m —, —O— (CH ₂ ) _m —O—, and —S— (CH ₂ ) _m —S—, where m is an integer from 1 to 12. Yes,
In formulas (VII) and (VIII)
A ₂ is independently a single bond, —O—, —S—, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or alkylene having 1 to 3 carbon atoms,
Hydrogen bonded to a cyclohexane ring or a benzene ring in the formula (III) ~ (VIII) it is, -F independently may be replaced with -CH _3. ] The tetracarboxylic dianhydride compounds A1 and B1 are represented by the following formulas (I-1), (I-2), (I-3), (I-7), (I-8) and (I-), respectively. 9) Compounds of the following formulas (I′-1), (I′-2), (I′-3), (I′-7), (I′-8) and (I′-9) The liquid crystal aligning agent according to claim 16, wherein the liquid crystal aligning agent is at least one selected from the group consisting of: an aromatic tetracarboxylic dianhydride, and an alicyclic tetracarboxylic dianhydride.

  The liquid crystal aligning agent according to claim 17, wherein the compound of the formula (I-9) is contained in at least one of the tetracarboxylic dianhydride compounds A1 and B1.   The liquid crystal aligning agent according to claim 17, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride.   The liquid crystal aligning agent according to claim 17, wherein the alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride. 17. The liquid crystal aligning agent according to claim 16, wherein the diamine having a side chain structure is a diamine represented by the following general formulas (IX) and (XI) to (XIV).

[In the formula (IX),
A ₃ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH— or — (CH ₂ ) _m —, wherein m is an integer of 1 to 6,
R ₁ is a group having a steroid skeleton, a group represented by the following formula (X), an alkyl having 1 to 20 carbons when the positional relationship between two amino groups bonded to the benzene ring is para, or When the positional relationship is meta, it is alkyl or phenyl having 1 to 10 carbon atoms,
In the alkyl, any —CH ₂ — may be independently replaced by —CF ₂ —, —CHF—, —O—, —CH═CH— or —C≡C—, ₃ may be replaced by —CH ₂ F, —CHF ₂ or —CF ₃ ,
Hydrogen bonded to the phenyl ring-forming carbon, -F _{independently, -CH 3, -OCH 3, -OCH} 2 F, may be replaced with -OCHF ₂ or -OCF _3. ]

[In Formula (X),
A ₄ and A ₅ are each independently a single bond, —O—, —COO—, —OCO—, —CONH—, —CH═CH—, or alkylene having 1 to 20 carbon atoms,
R ₂ and R ₃ are each independently —F or —CH ₃ ;
Ring S is 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5- Diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl;
R ₄ is —H, —F, alkyl having 1 to 20 carbon atoms, fluorine-substituted alkyl having 1 to 20 carbon atoms, alkoxy having 1 to 20 carbon atoms, —CN, —OCH ₂ F, —OCHF ₂ or —OCF _3. And
a and b each independently represent an integer of 0 to 4, and when a or b is 2 to 4, adjacent A ₄ or A ₅ are different groups;
c, d and e each independently represent an integer of 0 to 3, and when e is 2 or 3, the plurality of rings S may be the same group or different groups,
f and g each independently represent an integer of 0 to 2 and c + d + e ≧ 1. ]

[In Formula (XI), the hydrogen bonded to the carbon forming the steroid skeleton may be independently replaced with —CH ₃ ;
In formulas (XI) and (XII)
Each R ₅ is independently —H or —CH ₃ ;
Each R ₆ is independently —H or an alkyl or alkenyl having 1 to 20 carbon atoms;
Each A ₆ is independently a single bond, —C (═O) — or —CH ₂ —;
In formula (XII),
R ₇ and R ₈ are each independently —H, C 1-20 alkyl or phenyl. ]

[In the formula (XIII),
R ₉ is —H or alkyl having 1 to 20 carbons, and any —CH ₂ — in the alkyl having 2 to 20 carbons is independently —O—, —CH═CH— or —. C≡C- may be substituted,
In formulas (XIII) and (XIV),
A ₇ is independently —O— or alkylene having 1 to 6 carbons,
In formula (XIII),
A ₈ is a single bond or alkylene having 1 to 3 carbon atoms,
Ring T is 1,4-phenylene or 1,4-cyclohexylene,
h is 0 or 1,
In formula (XIV),
R ₁₀ is alkyl having 6 to 22 carbon atoms,
R ₁₁ is —H or alkyl having 1 to 22 carbons. ] The diamine compounds A2 and B2 are respectively p-phenylenediamine, m-phenylenediamine, the following formulas (VI-1) to (VI-12), (IX-2), (IX-4), (IX-5). The liquid crystal aligning agent according to claim 21, wherein the liquid crystal aligning agent is at least one selected from the group consisting of compounds of (II), (IX-6) and (XIII-2).

[In the formula (IX-2), R ₁₂ is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and in formulas (IX-4) to (IX-6), R ₁₃ is 1 carbon. Or an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ₁₈ is —H or alkyl having 1 to 20 carbon atoms in the formula (XIII-2). ] The formula (IX-6) is a compound in which R ₁₃ is C ₇ H ₁₅ , or the formula (XIII-2) is a compound in which R ₁₈ is C ₄ H _9. The liquid crystal aligning agent of Claim 22. The polyamic acid or derivative A thereof is a polyamic acid or derivative PA1 obtained by reacting the compound of formula (I-9) and pyromellitic dianhydride with the compound of formula (VI-1). ,
The polyamic acid or its derivative B is a polyamic acid or its derivative PA2 obtained by reacting the compound of the formula (I-9) with p-phenylenediamine and the compound of the formula (XIII-2), or It is a polyamic acid or its derivative PA3 obtained by reacting the compound of formula (I-9) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride with the compound of formula (IX-6). The liquid crystal aligning agent as described in any one of Claims 16-23 characterized by these.   The liquid crystal aligning agent according to claim 24, comprising the polyamic acid or its derivatives PA1 and PA2.   The liquid crystal aligning agent according to claim 24, comprising the polyamic acid or its derivatives PA1 and PA3. 1) a pair of substrates arranged opposite to each other;
2) Electrodes formed on one or both of the opposing surfaces of the pair of substrates,
3) a liquid crystal display element comprising: a liquid crystal alignment film formed on opposing surfaces of each of the pair of substrates; and 4) a liquid crystal layer formed between the pair of substrates.
The said liquid crystal aligning film is a liquid crystal display element which is a liquid crystal aligning film formed using the liquid crystal aligning agent as described in any one of Claims 1-26.

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