JP2007025216A - Liquid crystal aligning agent for homeotropic alignment liquid crystal display element, and homeotropic alignment liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent for a homeotropic alignment liquid crystal display element, which has excellent solubility. <P>SOLUTION: The liquid crystal aligning agent contains a polyamic acid which is obtained by making a diamine compound including a diamine with a side chain structure and a tetracarboxylic acid dianhydride compound react with each other and of which the weight average molecular weight is in a predetermined range, or a derivative thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Liquid crystal display elements are used in various liquid crystal display devices, such as monitors for laptop computers and desktop computers, video camera viewfinders, and projection displays. Recently, they have also been used as televisions. . Furthermore, they are also used as optoelectronic-related elements such as optical printer heads, optical Fourier transform elements, and light valves.
As a conventional liquid crystal display element, a display element using a nematic liquid crystal is a mainstream, and 1) a TN (twisted nematic) type liquid crystal display element twisted by 90 degrees, and 2) a STN (super twisted nematic) twisted usually by 180 degrees or more. 3) A so-called TFT (Thin Film Transistor) type liquid crystal display element using a thin film transistor has been put into practical use.

  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 are lowered and luminance is inverted in a halftone. In recent years, regarding this viewing angle problem, 1) a TN-TFT type liquid crystal display element using an optical compensation film, 2) a VA (vertical alignment) type display element using an optical compensation film, and 3) vertical alignment and protrusion structure. MVA (Multi Domain Vertical Alignment) type liquid crystal display element combined with physical technology, or 4) IPS (In-Plane Switching) type liquid crystal display element, 5) ECB (Electrically Controlled Birefringence) type liquid crystal display element 6) Optically compensated bend (Optically self-compensated birefringence: OCB) type liquid crystal display element Is improved by the technique, it has been put to practical use, or study.

  Among these good viewing angle type liquid crystal display elements, 2) VA type display elements using optical compensation films, and 3) vertical alignment methods such as MVA type liquid crystal display elements using a combination of vertical alignment and protrusion structure technology. The liquid crystal display element performs display by aligning n-type nematic liquid crystal having negative dielectric anisotropy in the normal direction with respect to the substrate surface and tilting the liquid crystal when an electric field is applied. When no voltage is applied, the liquid crystal is vertically aligned and does not generate birefringence at all. Therefore, incident light passes through the liquid crystal with almost no change in its plane of polarization. Therefore, a good black display can be easily realized under crossed nicols, so that this liquid crystal display element can obtain extremely high contrast.

  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 the substrate, a polyimide-based alignment film is formed by film formation by means such as heating. Various liquid crystal aligning agents other than polyimide-based alignment films have been studied, but in terms of heat resistance, chemical resistance (liquid crystal resistance), coatability, liquid crystal alignment, electrical characteristics, optical characteristics, display characteristics, etc. Almost no practical use.

  A vertically aligned liquid crystal display element is required to have a high pretilt angle of about 85 to 90 ° in view of its driving principle. In order to realize such a high pretilt angle (that is, a vertical alignment state), 1) a method of applying a surfactant, a chromium complex, or the like, and 2) a vertical evaporation method of SiO or the like are generally used. As mentioned above, it has hardly been put to practical use as a liquid crystal aligning agent. The orientation mechanism in this case is considered to be mainly due to the anisotropic excluded volume effect between the hydrocarbon chain of the surfactant and the liquid crystal molecules. (For example, see Liquid Crystal Dictionary, Bafukan Publishing (1989/12/5), P186 surface treatment (Non-Patent Document 1).)

  In order to achieve the same effect in the polyimide-based alignment film, it is considered to use a polyamic acid or polyimide having a side chain group (branched polyamic acid or branched polyimide) instead of the hydrocarbon chain of the surfactant described above. ing. The polyamic acid or polyimide having a side chain group can be prepared by using a tetracarboxylic dianhydride having a side chain structure or a diamine having a side chain structure as a reaction raw material, but for a vertically aligned liquid crystal display element. As the liquid crystal aligning agent, those using a diamine having a side chain structure are common.

However, any diamine having a side chain structure is not applicable. For example, for the diamine shown below, the pretilt angle of the liquid crystal alignment film formed from the liquid crystal aligning agent using this diamine is about 14 °, and does not necessarily exhibit a high pretilt angle of about 85 to 90 °. . (For example, refer to JP-A-3-167162 (Patent Document 1).)

On the other hand, as a diamine having a side chain structure that can be used for a liquid crystal aligning agent for a vertically aligned liquid crystal display element, for example, a diamine having a side chain structure represented by the following general formula (I ′) has been proposed. (See, for example, JP-A-5-27244 (Patent Document 2), JP-A-9-278724 (Patent Document 3), and JP-A-4-281427 (Patent Document 4).)
Wherein R ^{1 ′} is a single bond, —O—, —COO—, —OCO—, —CONH— or alkylene, and R ^{2 ′} is an aromatic ring which may have a substituent. Or an aliphatic ring or a cyclic hydrocarbon group in which these are bonded through a single bond or a bonding group.)

Furthermore, it is known that a compound represented by the following general formula (2) or (3) is preferable in order to develop various properties such as heat resistance, electrical characteristics, orientation stability, and reliability in a balanced manner. Yes. (For example, refer to JP 2002-162630 A (Patent Document 5), JP 2003-96034 A (Patent Document 6).)

(In the formula, ring Y is 1,4-cyclohexylene or 1,4-phenylene which may have a substituent, and A ^{1 to} A ³ are each independently a single bond, 1,4-cyclohexane. Hexylene or optionally substituted 1,4-phenylene, B ^{1 to} B ³ are each independently a single bond, alkylene having 1 to 4 carbon atoms, R is H, any CH ₂ is alkyl having 1 to 10 carbon atoms which may be replaced with CF ₂ , etc.)

  In order to provide a high pretilt angle suitable for a vertically aligned liquid crystal display element, a diamine having both a phenylenediamine structure and a side chain structure as represented by the above formula (I ') is particularly preferably used.

As described above, the diamine represented by the above formula (I ′) can be suitably used as a liquid crystal aligning agent for a vertically aligned liquid crystal display element. However, on the other hand, the polyamic acid or polyimide obtained by using the diamine represented by the above formula (I ′) has a problem that the “solubility” with respect to the solvent is poor. This tendency was particularly remarkable in polyimide having a rigid molecular structure (imide bond).
On the other hand, polyamic acid having relatively high “solubility” usually needs to be stored frozen in a temperature range of −30 to 0 ° C. because the stability of the polymer is poor. In such a case, the polyamic acid has a problem in that a polymer may precipitate during freezing storage.

  When the chain connecting two amino groups is a main chain, for example, the diamine disclosed in Patent Document 1 has a flexible ether bond in the main chain, whereas in the above formula (I ′) The diamine having the phenylenediamine structure shown does not have a flexible linking group in the main chain structure portion. Therefore, the diamine represented by the above formula (I ′) is likely to have a rigid molecular structure even in the resulting polyamic acid or polyimide, so that it is considered that the “solubility” in the solvent is deteriorated.

  In particular, in order to stabilize the vertical alignment state, when the side chain length is increased in a diamine having a non-polar side chain structure such as an alkyl chain, 1,4-phenylene or 1,4-cyclohexylene, a polyamic acid Extremely “soluble” in aprotic polar organic solvents (for example, N-methyl-2-pyrrolidone) which is a parent solvent for polyimide and polar organic solvents (ethylene glycol monobutyl ether) for the purpose of improving coating properties The problem worsened.

  In addition, in order to impart various characteristics such as heat resistance, electrical characteristics, alignment stability, and reliability, a technique of a liquid crystal aligning agent containing a combination of two or more polyamic acids or polyimides having different characteristics is known. (For example, refer to JP-A-11-193345 (Patent Document 7) and JP-A-11-193347 (Patent Document 8).) However, in this case as well, the “solubility” of one polyamic acid or polyimide is poor. The compatibility of each component in the liquid crystal aligning agent deteriorates. In an extreme case, the liquid crystal aligning agent is separated into two layers, which is a problem.

JP-A-3-167162 JP-A-5-27244 JP-A-9-278724 JP-A-4-281427 JP 2002-162630 A JP 2003-96034 A JP 11-193345 A JP-A-11-193347 Liquid crystal dictionary, published by Baifukan (1989/12/5), page 186

  In view of the above situation, development of a liquid crystal aligning agent for a vertically aligned liquid crystal display element in which the problem of “solubility” has been improved, and a vertical aligned liquid crystal display element having a liquid crystal alignment film formed using the same It is desired.

The present inventors have intensively studied to solve the above problems. As a result, a polyamic having a weight average molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ obtained by reacting a diamine compound containing a diamine having a side chain structure with a tetracarboxylic dianhydride compound. It has been found that the acid or its derivative is particularly excellent in solubility in a solvent. In addition, this polyamic acid or derivative thereof has good compatibility with other polyamic acid or derivative thereof, and the desired “solubility” can be obtained even when these two or more kinds of polyamic acid or derivative thereof are combined. As a result, the present invention was completed.

In addition, as a technique for controlling the weight average molecular weight in the polyimide-based liquid crystal aligning agent, for example, Japanese Patent Application Laid-Open No. 11-95227 discloses “Liquid composed of a resin composition containing a polyamic acid having a weight average molecular weight of 1000 to 20000”. A protective film and alignment film for liquid crystal, characterized in that the film is made of a polyimide film formed by printing on the surface of the liquid crystal sandwiching substrate on which the electrodes are formed and drying by heating. " However, the technique of this publication obtains good flatness during film formation by controlling the weight average molecular weight to 1000 to 20000, and a specific side chain structure in a liquid crystal aligning agent for use in a vertical alignment liquid crystal display element. There is no description about the “solubility” of the polyamic acid containing the diamine having.
JP-A-10-10535 discloses that “an imide ring-containing organic polymer has an average molecular weight of 20,000 or less, a resin concentration of 15% by weight or more, and a varnish viscosity of 50 mPa · s or less. The liquid crystal planarization and alignment control film is disclosed. However, the technique of this publication is to flatten the concavo-convex structure of a substrate with an imide ring-containing organic polymer having a single layer thickness of 0.5 μm or more and a weight average molecular weight of 20,000 or less. The present invention relates to an electric field type liquid crystal element. A horizontal electric field type liquid crystal element usually has a small pretilt angle of 0 to 2 °, and is completely different from the vertical alignment liquid crystal display element of the present invention.

The present invention has the following configuration.
[1] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising a polyamic acid or a derivative thereof, and a solvent,
A weight average molecular weight obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by the following general formula (I) with a tetracarboxylic dianhydride compound A2 is 1.0 × 10 ⁴ to 4. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising: a polyamic acid of 0.0 × 10 ⁴ or a derivative A thereof.
[In Formula (I),
R ¹ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH—, or alkylene having 1 to 6 carbon atoms,
R ² is a group having a steroid skeleton, a group represented by the following formula (II), or an alkyl having 1 to 20 carbon atoms 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 having 2 to 6 carbon atoms in the alkyl, any —CH ₂ — may be replaced by —O—, —CH═CH— or —C≡C—,
Hydrogen bonded to the phenyl ring carbon _{is, -F, -CH 3, -OCH 3} , -OCH 2 F, may be replaced with -OCHF ₂ or -OCF _3. ]


[In the formula (II),
R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond, —O—, —COO—, —OCO—, —CONH— or alkylene having 1 to 3 carbon atoms,
R ¹³ and R ¹⁴ are each independently —F or —CH ₃ ;
Ring C is 1,4-phenylene or 1,4-cyclohexylene,
R ¹⁵ is —F, alkyl having 1 to 20 carbons, fluorine-substituted alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, —OCH ₂ F, —OCHF ₂ or —OCF ₃ ;
a, b and c each independently represents an integer of 0 to 4;
d, e and f each independently represents an integer of 0 to 3, and when f is 2 or 3, the plurality of rings C may be the same group or different groups,
g and h each independently represent an integer of 0 to 2 and d + e + f ≧ 1. ]

[2] In the diamine having a side chain structure represented by the general formula (I), R ¹ is a single bond, —O—, —COO—, —OCO—, alkylene having 1 to 2 carbon atoms, R ² is a group represented by the formula (II),
In the formula (II), R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond or alkylene having 1 to 3 carbon atoms, and R ¹³ and R ¹⁴ are each independently —F or —CH ₃ , ring C is 1,4-phenylene or 1,4-cyclohexylene, R ¹⁵ is alkyl having 1 to 20 carbons or alkoxy having 1 to 20 carbons, and a, b and c are each Independently represents an integer of 0 to 1, d, e and f each independently represents an integer of 0 to 1, g and h each represents an integer of 0 to 1, and d + e + f ≧ 1 The liquid crystal aligning agent for vertically aligned liquid crystal display according to [1].

[3] In the diamine compound A1, the total content of the diamine having a side chain structure represented by the general formula (I) is 30 to 100 mol% of the entire diamine, [1] or The liquid crystal aligning agent for vertical alignment liquid crystal display elements as described in [2].

[4] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising a polyamic acid or a derivative thereof, and a solvent,
A weight average molecular weight obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by the following general formula (I) with a tetracarboxylic dianhydride compound A2 is 1.0 × 10 ⁴ to 4. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising: a polyamic acid of 0.0 × 10 ⁴ or a derivative A thereof.
[In Formula (I),
R ¹ is alkylene having 1 to 2 carbon atoms, and R ² is a group represented by the following formula (II). ]

[In the formula (II),
R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond, —O—, —COO—, —OCO—, —CONH— or alkylene having 1 to 3 carbon atoms,
R ¹³ and R ¹⁴ are each independently —F or —CH ₃ ;
Ring C is 1,4-phenylene or 1,4-cyclohexylene,
R ¹⁵ is —F, alkyl having 1 to 20 carbons, fluorine-substituted alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, —OCH ₂ F, —OCHF ₂ or —OCF ₃ ;
a, b and c each independently represents an integer of 0 to 4;
d, e and f each independently represents an integer of 0 to 3, and when f is 2 or 3, the plurality of rings C may be the same group or different groups,
g and h each independently represent an integer of 0 to 2 and d + e + f ≧ 1. ]

[5] In the formula (II), R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond or alkylene having 1 to 3 carbon atoms, and R ¹³ and R ¹⁴ are each independently -F Or —CH ₃ , ring C is 1,4-phenylene or 1,4-cyclohexylene, R ¹⁵ is alkyl having 1 to 20 carbons or alkoxy having 1 to 20 carbons, and a, b and c each independently represents an integer of 0 to 1, d, e and f each independently represents an integer of 0 to 1, g and h each represents an integer of 0 to 1, and d + e + f ≧ 1 The liquid crystal aligning agent for vertical alignment liquid crystal display as described in [4] characterized by the above-mentioned.

[6] In the diamine compound A1, the total content of the diamine having a side chain structure represented by the general formula (I) is 30 to 100 mol% of the entire diamine, [4] or The liquid crystal aligning agent for vertical alignment liquid crystal display elements as described in [5].

[7] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising a polyamic acid or a derivative thereof, and a solvent,
Weight average obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by any of the following formulas (I-13) to (I-23) with a tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element comprising a polyamic acid having a molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ or a derivative A thereof.

[In the formulas (I-13) to (I-23), R ²² is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and R ²³ is alkyl having 1 to 10 carbons or 1 carbon. -10 alkoxy. ]

[8] In the diamine compound A1, the total content of the diamines represented by the formulas (I-13) to (I-23) is 30 to 100 mol% of the total diamine, [7] A liquid crystal aligning agent for a vertically aligned liquid crystal display element according to [7].

[9] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising a polyamic acid or a derivative thereof, and a solvent,
Weight average obtained by reacting diamine compound A1 containing a diamine having a side chain structure represented by any of the following formulas (I-16) to (I-18) with tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element comprising a polyamic acid having a molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ or a derivative A thereof.

[In the formulas (I-16) to (I-18), R ²³ is alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons. ]

[10] In the diamine compound A1, the total content of diamines represented by the formulas (I-16) to (I-18) is 30 to 100 mol% of the total diamine, [9] A liquid crystal aligning agent for a vertically aligned liquid crystal display element according to [9].

[11] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising a polyamic acid or a derivative thereof, and a solvent,
Diamine containing a diamine having a side chain structure represented by any of the following formulas (I-16) to (I-18) and a diamine represented by the following formula (V-6) or (VI-1) It contains polyamic acid or its derivative A having a weight average molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ obtained by reacting compound A1 with tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element.

[12] In the diamine compound A1, the total content of diamines represented by the formulas (I-16) to (I-18) is 30 to 100 mol% of the total diamine, 11] The liquid crystal aligning agent for vertical alignment liquid crystal display elements of description.

[13] The weight average molecular weight of the polyamic acid or derivative A thereof is 1.5 × 10 ^{4 to} 2.5 × 10 ⁴ , according to any one of [1] to [12], Liquid crystal aligning agent for vertically aligned liquid crystal display elements.

[14] A liquid crystal aligning agent for a vertically aligned liquid crystal display device, comprising two or more polyamic acids or derivatives thereof, and a solvent,
A) The polyamic acid or derivative A thereof according to any one of claims 1 to 13, and B) a diamine compound B1 containing a diamine represented by the following general formulas (III) to (VIII), and a tetracarboxylic acid A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising a polyamic acid obtained by reacting the dianhydride compound B2 or a derivative B thereof.
[In the formulas (III) to (VIII),
X 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—, —S— (CH ₂ ) _m —S—, wherein m is an integer of 1-6. ,
Y is 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 may be replaced with -F or -CH ₃ . Furthermore, hydrogen bonded to the benzene ring in formula (V) may be replaced with benzyl. ]

[15] The liquid crystal display element according to [14], wherein the weight ratio of the polyamic acid or its derivative A to the polyamic acid or its derivative B is 1/99 to 50/50. Liquid crystal aligning agent.

[16] The vertical alignment liquid crystal display element according to [14], wherein a weight ratio of the polyamic acid or derivative A thereof to the polyamic acid or derivative B thereof is 5/95 to 20/80. Liquid crystal aligning agent.

[17] The tetracarboxylic dianhydride compounds A2 and B2 are each independently an aromatic tetracarboxylic dianhydride represented by the following formulas (1) to (13) and the following formulas (14) to (14): 62) including one or more selected from the group consisting of aliphatic tetracarboxylic dianhydrides or alicyclic tetracarboxylic dianhydrides represented by [1] to [1] 16] The liquid crystal aligning agent for vertical alignment liquid crystal display elements as described in any one of.

[18] The tetracarboxylic dianhydride compounds A2 and B2 each independently include pyromellitic dianhydride and / or cyclobutanetetracarboxylic dianhydride, [1] to [17] ] The liquid crystal aligning agent for vertical alignment liquid crystal display elements as described in any one of these.

[19]
1) A pair of substrates which are arranged opposite to each other and electrodes are arranged on both sides,
2) a vertical alignment liquid crystal display element comprising: a liquid crystal alignment film formed on the opposing surfaces of each of the pair of substrates; and 3) a vertically aligned liquid crystal layer sandwiched between the pair of substrates. ,
The said liquid crystal aligning film is a vertical alignment liquid crystal display element which is a liquid crystal aligning film formed by apply | coating the liquid crystal aligning agent as described in any one of [1]-[18] to the said board | substrate, and heating.

  According to the present invention, it is possible to provide a liquid crystal aligning agent for a vertically aligning liquid crystal display element having good solubility and a vertical aligning liquid crystal display element including a liquid crystal aligning film formed from the liquid crystal aligning agent.

The liquid crystal aligning agent of this invention is a liquid crystal aligning agent for vertical alignment liquid crystal display elements containing 1 type, or 2 or more types of polyamic acid or its derivative (s), and a solvent.
Among the polyamic acids or derivatives thereof contained in the liquid crystal aligning agent of the present invention, at least one of them is a diamine compound A1 containing a diamine having a side chain structure represented by the above general formula (I), and tetracarboxylic dianhydride. A polyamic acid or a derivative A thereof (hereinafter also referred to as “polyamic acid A”) having a weight average molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ obtained by reacting the compound A2. It is a liquid crystal aligning agent for vertical alignment liquid crystal display elements characterized by these.
Furthermore, the liquid crystal aligning agent of this invention reacts diamine compound B1 containing the diamine represented by polyamic acid or its derivative A, and said general formula (III)-(VIII), and tetracarboxylic dianhydride compound B2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising a polyamic acid or a derivative B thereof (hereinafter also referred to as “polyamic acid B”) obtained by heating.
In addition, the liquid crystal aligning agent of this invention may contain only polyamic acid A and B as polyamic acid or its derivative (s), and may further contain polyamic acid other than polyamic acid A and B or its derivative (s). .
Hereinafter, the liquid crystal aligning agent and the vertical alignment liquid crystal display element for the vertical alignment liquid crystal display element of the present invention will be described in detail.

<1. Polyamic acid A contained in the liquid crystal aligning agent of the present invention>
As described above, the polyamic acid A contained in the liquid crystal aligning agent of the present invention is a polyamic acid or a derivative thereof obtained by reacting the diamine compound A1 with the tetracarboxylic dianhydride compound A2.
The diamine compound A1 is composed of one or more diamines, but a part of the diamine contained in A1 may be substituted with a monoamine.
The tetracarboxylic dianhydride compound A2 is composed of one or more tetracarboxylic dianhydrides, but a part of the tetracarboxylic dianhydride contained in A2 may be substituted with a dicarboxylic acid.

Here, the derivatives of polyamic acid are: 1) polyimide in which all amino groups of polyamic acid and carboxylic acid are subjected to dehydration ring-closing reaction, 2) partial polyimide in which partial dehydration ring-closing reaction is performed, 3) tetracarboxylic dianhydride compound A part of the acid dianhydride contained in A2 is replaced with an organic dicarboxylic acid to obtain a polyamic acid-polyamide copolymer, and 4) part or all of the polyamic acid-polyamide copolymer is dehydrated. Polyamideimide subjected to ring-closing reaction is included.
Hereinafter, the diamine compound A1 and the tetracarboxylic dianhydride compound A2 that are raw materials of the polyamic acid A will be described.

(Diamine compound A1)
First, the diamine compound A1 used in the present invention will be described.
As described above, the diamine compound A1 is composed of one or more diamines, but includes at least a diamine having a side chain structure represented by the general formula (I).
In this specification, the diamine having a side chain structure means a diamine having a side chain when a chain connecting two amino groups is a 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. It is something that can be done. A liquid crystal alignment film formed from a liquid crystal aligning agent containing polyamic acid or 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.

What is necessary is just to select suitably the side chain in the diamine which has a side chain structure represented by general formula (I) so that it may become a pretilt angle of about 85-90 degrees suitable for a vertical alignment liquid crystal display element. For example, the side chain is preferably a group having 3 or more carbon atoms. In particular,
1) A phenyl group which may have a substituent, a cyclohexylphenylene which may have a substituent, a bis (cyclohexyl) phenylene which may have a substituent, or an alkyl or alkenyl having 3 or more carbon atoms 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, cyclohexylphenyloxy which may have a substituent, 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 Optionally bis (cyclohexyl) phenyloxycarbonyl, optionally substituted cyclohexylbis (phenyl) oxycarbonyl, or alkyloxycarbonyl, alkenyloxycarbonyl or alkynyloxycarbonyl having 3 or more carbon atoms,
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 Cyclohexylphenylalkylene, 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) Alkyl or fluorine in which two or more benzene rings or cyclohexane rings are bonded through a single bond, or bonded through —O—, —COO—, —OCO—, —CONH—, or alkylene having 1 to 3 carbon atoms. Examples thereof include a substituted alkyl or a ring assembly group substituted by alkoxy, but the present invention is not limited thereto as long as the pretilt angle is about 85 to 90 °.
Here, examples of the “substituent” include alkyl, alkoxy, alkoxyalkyl and the like.
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.

  Thus, the diamine represented by the general formula (I) used in the present invention is a phenylenediamine having a side chain structure. Since the diamine has only one phenyl ring in the main chain connecting two amino groups, for example, the diamine has a side chain structure and has a main chain structure as compared to a diamine having 2 to 4 phenyl rings in the main chain structure. The molecular length of the chain structure is shortened. As a result, in the polyamic acid A obtained by reacting the diamine with tetracarboxylic dianhydride, the spatial density (side chain density) of the side chain structure can be increased. Since the pretilt angle tends to increase as the side chain density increases, the diamine represented by the general formula (I) can be preferably used particularly as a raw material for a liquid crystal alignment film for a vertical alignment liquid crystal display element.

In the general formula (I), 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 3rd and 5th positions or the 2nd and 5th positions when the bonding position of “R ² —R ¹ —” is the 1st position. Among these, it is more preferable that the two amino groups are bonded to the 3-position and the 5-position, respectively.

Examples of the diamine represented by the general formula (I) include diamines represented by the formulas (I-1) to (I-31).

In formulas (I-1) to (I-3), R ¹⁹ is preferably an alkyl group having 4 to 12 carbon atoms, and in formula (I-4), R ²⁰ is preferably an alkyl group having 6 to ²⁰ carbon atoms.

In the formula, R ²² is preferably an alkyl group having 3 to 12 carbon atoms or an alkoxy group having 3 to 12 carbon atoms, and R ²³ is preferably an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

Of these, more preferably a diamine having a side chain structure represented by the general formula (I), R ¹ is alkylene of 1 to 2 carbon atoms, represented by R ² is the formula (II) Examples thereof include diamines that are groups, that is, diamines represented by formulas (I-13) to (I-23), and most preferably diamines represented by formulas (I-16) to (I-18). .

  The diamine compound A1 of the present invention may contain the diamine represented by the general formula (I) alone or may contain two or more kinds.

As described above, it includes a polyamic acid obtained by reacting at least a diamine compound A1 containing a diamine having a side chain structure represented by the general formula (I) with a tetracarboxylic dianhydride compound A2, or a derivative thereof. A liquid crystal alignment film formed from a liquid crystal aligning agent can be preferably used as a liquid crystal aligning agent for a vertical alignment liquid crystal display element because a pretilt angle in the liquid crystal display element is increased. Furthermore, the vertical alignment state becomes more stable as the molecular length (side chain length) of the side chain structure of the diamine having the side chain structure represented by the general formula (I) increases. For this reason, the polyamic acid obtained by using diamine having a large molecular length of the side chain structure or a derivative thereof can be more suitably used as a liquid crystal aligning agent for a vertical alignment liquid crystal display element.
In the diamine compound A1, the total content of the diamine having a side chain structure represented by the general formula (I) is preferably 30 to 100 mol%, and preferably 50 to 100 mol% of the entire diamine. More preferably, it is more preferably 50 to 90 mol%. When the total content of the diamine represented by the general formula (I) is 30 mol% or more, it is possible to impart a pretilt angle of 85 to 90 ° suitable for a vertically aligned liquid crystal display element.

  The diamine other than the diamine represented by the general formula (I) contained in the diamine compound A1 is arbitrary, and preferably diamines represented by the above general formulas (III) to (VIII). Details of the diamines represented by the general formulas (III) to (VIII) will be described later.

Furthermore, as a diamine other than the diamine represented by the general formula (I) contained in the diamine compound A1, in addition to the diamine represented by the general formulas (III) to (VIII), a siloxane diamine having a siloxane bond is used. It can also be mentioned. The siloxane-based diamine is not particularly limited, but those represented by the following formula (IX) can be preferably used in the present invention.
Wherein R ¹⁶ and R ¹⁷ are independently alkyl or phenyl having 1 to 3 carbon atoms, R ¹⁸ is methylene, phenylene or alkyl-substituted phenylene. Q represents an integer of 1 to 6; r represents an integer of 1 to 10.)

  In addition, the diamine other than the diamine represented by the general formula (I) contained in the diamine compound A1 includes the diamine represented by the general formulas (III) to (VIII) and the diamine represented by the formula (IX). Without limitation, various other forms of diamine (for example, diamine having a side chain structure other than the diamine represented by the general formula (I)) exist within the scope of achieving the object of the present invention. Needless to say. Moreover, this other diamine can be used individually or in combination of 2 or more types.

  As already described, a part of the diamine contained in the diamine compound A1 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 A) can be easily controlled. can do. 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.

(Tetracarboxylic dianhydride A2)
Next, the tetracarboxylic dianhydride compound A2 used in the present invention will be described.
As described above, the polyamic acid A is synthesized using the tetracarboxylic dianhydride compound A2 as a raw material. The tetracarboxylic dianhydride compound A2 is composed of one or more tetracarboxylic dianhydrides. Tetracarboxylic dianhydride is a compound represented by the following general formula (X).

The tetracarboxylic dianhydride contained in the tetracarboxylic dianhydride compound A2 used in the present invention is arbitrarily selected, 1) aromatic tetracarboxylic dianhydride, 2) aliphatic tetracarboxylic dianhydride or Any of alicyclic tetracarboxylic dianhydride may be sufficient.
In order to use polyamic acid A as a component of the liquid crystal aligning agent, it is preferable to take a form soluble in a solvent. In order to make the polyamic acid A soluble, it is preferable to appropriately select a tetracarboxylic dianhydride contained in the tetracarboxylic dianhydride compound A2.

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, acid dianhydrides represented by (1), (2), (5), (6), and (7) are more preferable, and most preferably Examples include pyromellitic dianhydride represented by (1).

Examples of the 2) aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride contained in the tetracarboxylic dianhydride compound A2 of the present invention include, for example, the following formulas (14) to (62): The acid dianhydride represented by this is specifically exemplified.
Among the acid dianhydrides described below, the acid dianhydrides represented by the formulas (14) to (29) and the formula (60) are more preferable, and the acid dianhydrides represented by the formula (14) are particularly preferable. 2,3,4-cyclobutanetetracarboxylic dianhydride is mentioned. In order to make the polyamic acid of 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 tetracarboxylic dianhydride compound A2 of the present invention can contain the above-mentioned tetracarboxylic dianhydride alone or in combination of two or more.

As described above, the polyamic acid A of the present invention is obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by the general formula (I) with a tetracarboxylic dianhydride compound A2. Polyamic acid or its derivative.
The liquid crystal aligning agent containing the polyamic acid A and a solvent can be suitably used as a liquid crystal aligning agent for a vertically aligned liquid crystal display element.

In the present invention, the polyamic acid A has a weight average molecular weight in the range of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ , preferably 1.5 × 10 ⁴ in order to improve the “solubility” in the solvent. It is controlled in the range of ˜2.5 × 10 ⁴ . By controlling the weight average molecular weight of the polyamic acid within the above range, the “solubility” of the polyamic acid A in the solvent can be improved. Further, when polyamic acid A is used in combination with, for example, polyamic acid B described later in order to impart various properties such as heat resistance, electrical characteristics, alignment stability, and reliability, The compatibility of each component can be made favorable.
The polyamic acid A having a weight average molecular weight of 1.0 × 10 ⁴ or more does not evaporate in the step of baking the alignment film, and is chemically and mechanically used for the alignment film cleaning process and alignment process process. Therefore, it has preferable physical properties as a component of the liquid crystal aligning agent.
Regarding the upper limit of the weight average molecular weight, polyamic acid A having a weight average molecular weight of 4.0 × 10 ⁴ or less can improve the solubility in a solvent, and can be preferably used as a liquid crystal aligning agent.

As a method for controlling the weight average molecular weight of the polyamic acid A of the present invention within the above range, 1) a method of heating the polyamic acid A solution of the present invention, and 2) the solid content of the polyamic acid A of the present invention in a poor solvent. 3) a method of heating (boiling) at 3), a method of deviating the molar ratio of tetracarboxylic dianhydride, which is a reaction raw material of the polyamic acid A of the present invention, and diamine from an equimolar amount, etc. You can choose.
Among them, 1) the method of heating the polyamic acid A solution of the present invention is preferable because it can be finely adjusted while confirming the weight average molecular weight after the reaction between the tetracarboxylic dianhydride compound and the diamine, and is easy to handle. . Although the weight average molecular weight is reduced by heating the solution, the heating temperature when finely adjusting the weight average molecular weight is usually 40 to 150 ° C, preferably 50 to 80 ° C. A higher heating temperature is preferable because the weight average molecular weight decreases in a short time, but if the change to be reduced is too large, it may be difficult to adjust to a desired weight average molecular weight. In addition, it is preferable that the heating temperature be equal to or lower than the boiling point of the solvent because handling is easy.
Here, the weight average molecular weight of the polyamic acid A is measured by a gel permeation chromatography (GPC) method. For example, the obtained polyamic acid A is diluted with dimethylformamide (DMF) so that the polyamic acid concentration is about 1% by weight, and a gel is used with DMF as a developing agent using Chromatopack C-R7A (manufactured by Shimadzu Corporation). Measured by a permeation chromatographic analysis (GPC) method and determined 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 the diluting solution 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)
Further, the molecular weight distribution of the polyamic acid A can be expressed by polydispersity. The polydispersity is a value of weight average molecular weight / number average molecular weight (Mw / Mn). In the present invention, the value is preferably 1.5 to 5. Here, the molecular weight distribution is measured by the GPC method similar to the molecular weight measurement.

Polyamic acid A can be produced using a 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 or more of diamines having a side chain structure represented by the general formula (I), and depending on circumstances One or more diamines selected from the other diamines (diamines of the general formulas (III) to (VIII) and formula (IX)), and a desired amount of monoamine as necessary.
Next, one or more of a solvent (for example, N-methyl-2-pyrrolidone and dimethylformamide which are amide polar solvents) and a tetracarboxylic dianhydride represented by the above general formula (X) are further required. Depending on the situation, dicarboxylic acid is added. At this time, the total amount of tetracarboxylic dianhydride is preferably approximately equimolar to the total number of moles of diamine (molar ratio of about 0.9 to 1.1), but by adjusting the molar ratio. The weight average molecular weight can also be controlled within a desired range.
A polyamic acid solution can be obtained by reacting at a temperature of 0 to 70 ° C. for 1 to 48 hours under stirring.

  The polyamic acid A can be identified by precipitating with a large amount of a poor solvent, separating the solid and the solvent completely by filtration or the like, and analyzing by IR or NMR. Moreover, a weight average molecular weight can also be controlled to a desired range by boiling the obtained solid content in a poor solvent. Furthermore, after decomposing solid polyamic acid A with an aqueous solution of a strong alkali such as KOH or NaOH, it is extracted with an organic solvent and analyzed by GC, HPLC or GC-MS to identify the monomer used. Can do.

The obtained polyamic acid solution can be used by diluting with a solvent in order to adjust to a desired viscosity.
Further, when polyamic acid A is a soluble polyimide that is a polyamic acid derivative, the resulting polyamic acid solution is prepared by using acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride as dehydrating agents, and It can be obtained by imidization reaction at a temperature of 20 to 150 ° C. with a tertiary amine such as triethylamine, pyridine, collidine and the like as a dehydration ring closure catalyst.
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-closing 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 amount of both is preferably 1.5 to 10 times the total molar amount of the acid dianhydride contained in the tetracarboxylic dianhydride compound A2 used. By adjusting the dehydrating agent, catalyst amount, reaction temperature and reaction time of this chemical imidization, the degree of imidization can be controlled and a partial polyimide can be obtained.
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 contained in the tetracarboxylic dianhydride compound A2 may be substituted with an organic dicarboxylic acid. When polyamic acid A is produced using A2 containing an 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.

  The diamine having a side chain structure represented by the general formula (I) used in the present invention is, for example, JP-A-4-281427, JP-A-5-27244, JP-A-9-278724. It is described in JP-A-2003-96034, or can be easily manufactured by the method described in the publication. Moreover, the tetracarboxylic dianhydride used for this invention is well-known, and can be obtained easily by a commercial item or a well-known method.

  Polyamic acid A thus obtained can be used alone as a component of a liquid crystal aligning agent, but can also be used as a component of a liquid crystal aligning agent by mixing with polyamic acid B described later.

<2. Polyamic acid B contained in the composition of the present invention>
As described above, the polyamic acid B contained in the liquid crystal aligning agent of the present invention is a polyamic acid or a derivative thereof obtained by reacting the diamine compound B1 with the tetracarboxylic dianhydride compound B2.
The diamine compound B1 is composed of one or more diamines, and a part of the diamine contained in B1 may be substituted with a monoamine.
The tetracarboxylic dianhydride compound B2 is composed of one or more tetracarboxylic dianhydrides, but a part of the tetracarboxylic dianhydride contained in B2 may be substituted with a dicarboxylic acid.
The derivative of the polyamic acid has the same meaning as that described for the polyamic acid A.

(Diamine compound B1)
First, the diamine compound B1 will be described.
As described above, the diamine compound B1 includes one or more diamines, but includes at least one of the diamines represented by the general formulas (III) to (VIII). The diamine compound B1 may further contain any other diamine as necessary. Here, examples of the other diamine include diamines represented by the formula (IX). The molar ratio of the diamines represented by the general formulas (III) to (VIII) in the diamine compound B1 may be adjusted according to the structure of the selected diamine, and is preferably 100/0 to 1/99. 80/20 to 5/95 is more preferable. When using 2 or more types of diamine represented by the said general formula (III)-(VIII), it is preferable that the total amount is the said range.
Furthermore, a part of the diamine contained in the diamine compound B1 may be substituted with a monoamine. Here, the ratio of monoamine to diamine is preferably 10 mol% or less.

As described above, the diamine compound B1 preferably contains a diamine having no side chain structure represented by the general formulas (III) to (VIII).
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-7).

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-7), 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-6), Examples include diamines represented by formula (V-7) and formulas (VI-1) to (VI-12).

  The diamine compound B1 of the present invention may contain one kind of diamine represented by the general formulas (III) to (VIII), or may contain two or more kinds.

The polyamic acid B obtained by reacting the diamine compound B1 of the present invention is combined (blended) with the above-described polyamic acid A, whereby preferable characteristics as a component of a liquid crystal aligning agent for a vertical alignment liquid crystal display element ( Heat resistance, electrical characteristics, orientation stability, reliability, and the like).
Specifically, the liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention can be suitably selected by appropriately selecting the kind of diamine contained in the diamine compound B1 that is the raw material of the polyamic acid B and the combination thereof. Excellent electrical characteristics (voltage holding ratio, residual DC, etc.) can be provided. Of the diamines represented by the general formulas (III) to (VIII), those having a structure containing no oxygen or sulfur such as carbonyl or ether bond tend to impart particularly excellent electrical properties to the liquid crystal alignment film. Is preferable.

(Tetracarboxylic dianhydride compound B2)
The polyamic acid B is obtained by reacting the diamine compound B1 with the tetracarboxylic dianhydride compound B2. The tetracarboxylic dianhydride contained in the tetracarboxylic dianhydride compound B2 includes tetracarboxylic acid dianhydride. The thing similar to the tetracarboxylic dianhydride described in description of acid dianhydride compound A2 is mentioned.
Moreover, like A2, a part of tetracarboxylic dianhydride contained in the tetracarboxylic dianhydride compound B2 may be substituted with dicarboxylic acid.
The tetracarboxylic dianhydride compound B2 can include tetracarboxylic dianhydride alone or in combination of two or more. Preferably, the combination includes 1) aromatic tetracarboxylic dianhydride and 2) aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride, particularly preferably represented by formula (1). The pyromellitic dianhydride is combined with 1,2,3,4-cyclobutanetetracarboxylic dianhydride represented by the formula (14).

Aromatic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride or alicyclic tetracarboxylic dianhydride (particularly preferably, pyromellitic dianhydride and 1,2,3,4-cyclobutanetetra The liquid crystal aligning agent containing polyamic acid synthesized from the tetracarboxylic dianhydride compound B2 containing carboxylic dianhydride) can impart excellent electrical properties to the liquid crystal alignment film.
When tetracarboxylic dianhydride compound B2 includes pyromellitic dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride, pyromellitic dianhydride / 1,2,3,4 -The molar ratio of cyclobutanetetracarboxylic dianhydride is preferably 10/90 to 90/10, and more preferably 15/85 to 75/25.

Since polyamic acid B is different from polyamic acid A, it is relatively easily soluble in a solvent usually used in the production process and applications of polymer components such as polyamic acid, soluble polyimide, and polyamideimide. It can have a weight average molecular weight. The weight average molecular weight of the polyamic acid B is not particularly limited, but is preferably 1 × 10 ⁴ or more for the same reason as the polyamic acid A. 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. ⁴ or less is preferable.
Further, the molecular weight distribution of the polyamic acid B can be expressed by polydispersity. The polydispersity is a value of weight average molecular weight / number average molecular weight (Mw / Mn). In the present invention, the value is preferably 1.5 to 5.
The weight average molecular weight and molecular weight distribution of polyamic acid B are measured in the same manner as for polyamic acid A.

  The method for producing polyamic acid B is not particularly limited, and can be produced in the same manner as polyamic acid A.

<3. Liquid crystal aligning agent of the present invention>
The liquid crystal aligning agent of this invention is prepared by mixing polyamic acid or its derivative (s), and a solvent. As the polyamic acid used in the present invention, polyamic acid A can be used alone, or polyamic acid A and polyamic acid B can be mixed and used. In the present invention, since desired characteristics can be easily obtained as a liquid crystal aligning agent such as heat resistance, electrical characteristics, alignment stability and reliability, it is possible to use a mixture of polyamic acid A and polyamic acid B. preferable.
The weight ratio of the polyamic acid A and the polyamic acid B to be mixed is preferably “polyamic acid A” / “polyamic acid B” = 1/99 to 50/50, and “polyamic acid A” / “polyamic acid B”. "= 5/95 to 20/80 is more preferable. The weight ratio may be appropriately adjusted so that a pretilt angle of about 85 to 90 ° suitable for a vertically aligned liquid crystal display element is obtained.
As described above, polyamic acid A can be used as a component of a preferred liquid crystal aligning agent by being combined with polyamic acid B. However, in order to use polyamic acid A as a component of the liquid crystal aligning agent, it is not necessarily required to be combined with polyamic acid B.

The liquid crystal aligning agent of this invention may further contain the various additives contained in a normal liquid crystal aligning agent.
The content of the polymer component (component having a weight average molecular weight of 1 × 10 ⁴ or more such as polyamic acid A and polyamic acid B) in the liquid crystal aligning agent of the present invention is appropriately selected depending on the method of applying the liquid crystal aligning agent to the substrate. be able to. For example, a polymer component in a liquid crystal aligning agent used in a printing press (including offset printing and ink jet printing press, which may be abbreviated as “printing press” hereinafter) used in the manufacturing process of a normal liquid crystal display element. The content 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 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 changing the surface tension to improve coating properties. 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 ethers such as dipropylene glycol monomethyl ether, acetates etc. It is an ester compound. 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, coating property, storage stability, and the like of the liquid crystal aligning agent.

As described above, the liquid crystal aligning agent of the present invention may contain various additives. As various additives, a high molecular 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, silicon-modified polyurethane, and silicon-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 widely depending on the coating method, the concentration of 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 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 measurement method, for example, measured using a rotational viscometer (TVE-20L type manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25 ° C.).

<4. Vertically Aligned Liquid Crystal Display Element of the Present Invention>
The vertically aligned liquid crystal display element of the present invention includes 1) a pair of substrates arranged opposite to each other, 2) a liquid crystal alignment film formed on the opposed surfaces of each of the pair of substrates, and 3) between the pair of substrates. It includes a vertically aligned liquid crystal layer that is sandwiched. Here, electrodes are arranged on both of the pair of substrates.

  The liquid crystal alignment film is a liquid crystal alignment film formed by applying the liquid crystal aligning agent of the present invention to the substrate and heating. Here, the film thickness of the liquid crystal alignment film is preferably 10 to 300 nm, and more preferably 30 to 100 nm. In addition, depending on the application, the liquid crystal alignment film may be rubbed.

  The pair of substrates with electrodes arranged opposite to each other is preferably a transparent substrate (for example, a glass substrate).

  The liquid crystal layer sandwiched between the pair of substrates includes a liquid crystal composition. The liquid crystal composition used in the vertical alignment liquid crystal display element is preferably various liquid crystal compositions having negative dielectric anisotropy. Examples of preferred liquid crystal compositions include JP-A-57-141432, JP-A-2-4725, JP-A-4-224858, JP-A-8-40953, JP-A-8-104869, Japanese Laid-Open Patent Publication No. 10-168076, Japanese Laid-Open Patent Publication No. 10-168453, Japanese Laid-Open Patent Publication No. 10-236989, Japanese Laid-Open Patent Publication No. 10-236990, Japanese Laid-Open Patent Publication No. 10-236992, Japanese Laid-Open Patent Publication No. 10-236993, Japanese Laid-open Patent Publication No. -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, 10-237448, (EP967261A1), JP 10-28787. JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP 2001-072626 A, JP 2001-192657 A, and the like.

  One or more optically active compounds may be added to the liquid crystal composition for use.

Of course, the vertical alignment liquid crystal display element of this invention may have another member.
For example, in a color display TFT type liquid crystal element 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, and the second transparent substrate is formed. 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.
In particular, in the MVA type liquid crystal display element, a minute protrusion called a domain is formed on the first transparent substrate. A spacer may be formed for adjusting the cell gap between the substrates.

  The vertical alignment liquid crystal display element of the present invention can be manufactured by any method. For example, 1) a step of applying a liquid crystal alignment agent on the two transparent substrates, and 2) a step of drying the applied liquid crystal alignment agent. 3) Step of performing heat treatment necessary for dehydrating and ring-closing reaction of the dried liquid crystal aligning agent, 4) Step of aligning the obtained alignment film, 5) After bonding the two substrates, It is manufactured by a method including a step of enclosing a liquid crystal in between, or a step of dropping a liquid crystal on one substrate and then bonding it to the other substrate.

  As an application 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.

  Moreover, as a method of the drying step and the step of performing the 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.

  In the vertical alignment liquid crystal display element, an alignment process such as a rubbing process is not usually performed, but a rubbing process may be performed if necessary.

  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.

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

  Usually, it is preferable that the liquid crystal alignment film used for the vertical alignment liquid crystal display element gives a pretilt angle of 85 to 90 °. As described above, the pretilt angle is adjusted mainly by adjusting 1) the type of diamine that is the raw material of polyamic acid A and the content ratio thereof, and 2) the content ratio of polyamic acid A and polyamic acid B. Achieved.

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

[Tetracarboxylic dianhydride]
Pyromellitic dianhydride {Formula (1)}: PMDA
1,2,3,4-cyclobutanetetracarboxylic dianhydride {formula (14)}: CBDA

[Diamine]
5- {4- [2- (4- n -heptylcyclohexyl) ethyl] cyclohexyl} phenyl-1,3-diaminobenzene {formula ^{_{(I-18) / R 23}} = C 7 H 15}: 7Ch2Ch
5- (4-n-propyl) phenyl-1,3-diaminobenzene {formula _{^{(I-16) / R 23}} = C 3 H 7}: 3Ch
4,4′-Diaminodiphenylmethane {Formula (VI-1)}: DDM
1-phenylmethyl-2,5-diaminobenzene {formula (V-6)}: P1PDA

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

<1. Synthesis of polyamic acid>
[Synthesis of polyamic acid A]
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, 7Ch2Ch (3.2449 g (6.639 mmol: molar fraction = 0.45)) and DDM (0.1462 g) 0.737 mmol: molar fraction = 0.05) and 20 g of dehydrated NMP were added and dissolved by stirring under a dry nitrogen stream. Next, 1.6089 g of PMDA (7.376 mmol: mole fraction = 0.5) was added, and the reaction temperature was suppressed to about 30 ° C. or lower and reacted for 30 hours.
To the obtained solution, 40 g of NMP and 35 g of BC were added to synthesize a polyamic acid solution having a concentration of 5% by weight. The obtained polyamic acid solution was heated at 75 ° C. for 3 hours and then cooled to about 30 ° C. or less to synthesize a polyamic acid solution (PA1). The resulting PA1 had a weight average molecular weight of 44,000.
Here, the weight average molecular weight of the polyamic acid is obtained by diluting the obtained polyamic acid with a diluted solution (phosphoric acid / DMF = 0.6 / 100: weight ratio) so that the polyamic acid concentration is about 1% by weight, Using Chromatopack C-R7A (manufactured by Shimadzu Corporation), the diluted solution was measured by the GPC method using a developing agent, and determined by polystyrene conversion. 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
A polyamic acid solution (PA2) was synthesized according to Synthesis Example 1 except that the heating time was changed from 3 hours to 13 hours. The obtained PA2 had a weight average molecular weight of 24,000.

Synthesis example 3
A polyamic acid solution (PA3) was synthesized according to Synthesis Example 1 except that the heating time was changed from 3 hours to 16 hours. The resulting PA3 had a weight average molecular weight of 21,000.

Synthesis example 4
A polyamic acid solution (PA4) was synthesized according to Synthesis Example 1 except that the heating temperature was changed from 75 ° C to 120 ° C and the heating time was changed from 3 hours to 16 hours. The resulting PA4 had a weight average molecular weight of 9,500.

Synthesis example 5
A polyamic acid solution (PA6) was synthesized according to Synthesis Example 3 except that the molar fractions of 7Ch2Ch, DDM and PMDA were changed to 0.35, 0.15 and 0.5, respectively. The resulting PA5 had a weight average molecular weight of 24,500.

Synthesis Example 6
A polyamic acid solution (PA6) was synthesized according to Synthesis Example 3 except that the molar fractions of 7Ch2Ch, DDM and PMDA were changed to 0.25, 0.25 and 0.5, respectively. The obtained PA6 had a weight average molecular weight of 23,000.

Synthesis example 7
A polyamic acid solution (PA7) was synthesized according to Synthesis Example 3 except that the molar fractions of 7Ch2Ch, DDM and PMDA were changed to 0.15, 0.35 and 0.5, respectively. The resulting PA7 had a weight average molecular weight of 17,500.

Synthesis example 8
A polyamic acid solution (PA8) was synthesized according to Synthesis Example 3 except that PMDA was changed to CBDA and the molar fractions of 7Ch2Ch, DDM and CBDA were changed to 0.25, 0.25 and 0.5, respectively. did. The obtained PA8 had a weight average molecular weight of 23,500.

Synthesis Example 9
A polyamic acid solution (PA9) was synthesized according to Synthesis Example 3, except that DDM was replaced with P1PDA and the molar fractions of 7Ch2Ch, P1PDA and PMDA were changed to 0.25, 0.25 and 0.5, respectively. did. The obtained PA9 had a weight average molecular weight of 19,000.

Synthesis Example 10
A polyamic acid solution (PA10) was synthesized according to Synthesis Example 3 except that 7Ch2Ch was replaced with 3Ch and the molar fractions of 3Ch, DDM and PMDA were changed to 0.45, 0.05 and 0.5, respectively. did. The resulting PA10 had a weight average molecular weight of 24,500.

[Synthesis of polyamic acid B]
Synthesis Examples 11-12
Conforms to Synthesis Example 1 except that the tetracarboxylic dianhydride and diamine are changed to the molar fractions shown in Table 1, the heating temperature 75 ° C. is changed to 60 ° C., and the heating time 3 hours is changed to 4 hours. Thus, a polyamic acid solution (PA11 to PA12) was synthesized.

The results of Synthesis Examples 1 to 12 are summarized in Table 1. (PA1 to PA12)

<2. Production of liquid crystal display element>
[Example 1]
After mixing 0.4 g of the polyamic acid solution (PA2) synthesized in Synthesis Example 2 and 3.6 g of the polyamic acid solution (PA11) synthesized in Synthesis Example 11, a mixed solvent of NMP / BC = 1/1 (weight ratio) Was diluted to 4% by weight to obtain a liquid crystal aligning agent. The obtained liquid crystal aligning agent was stored frozen at −10 ° C. for 2 days. Then, when it returned to normal temperature, the precipitation which can be visually recognized did not arise or it isolate | separated into two layers, and the solubility with respect to a solvent was favorable. Using the obtained liquid crystal aligning agent, a vertically aligned liquid crystal display element was produced as follows.

Method for Producing Vertically Aligned Liquid Crystal Display Element A liquid crystal aligning agent was applied to each of 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.
Using a rubbing treatment apparatus manufactured by Iinuma Gauge Co., Ltd., the glass substrate on which the alignment film was formed was pushed into the rubbing cloth (hair leg length 1.9 mm: rayon) by 0.30 mm and the stage moving speed was 60 mm. / Sec., And the roller rotation speed was 1000 rpm. The glass substrate on which the 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 was sprayed on one glass substrate, and the surface on which the alignment film was formed was placed inside so that the rubbing direction was antiparallel, then sealed with an epoxy curing agent, and anti-parallel with a gap of 4 μm. A cell was produced. Liquid crystal composition B described below 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 a vertical alignment liquid crystal display element.

[Examples 2 to 8]
A liquid crystal aligning agent was obtained in the same manner as in Example 1 except that PA3 and PA5 to 10 were used instead of PA2. The solubility of the obtained liquid crystal aligning agent (after freezing storage at −10 ° C. for 2 days) was good. Further, using the obtained liquid crystal aligning agent, a vertically aligned liquid crystal display element was produced in the same manner as in Example 1.

[Example 9]
A liquid crystal aligning agent was obtained in the same manner as in Example 1 except that PA12 was used instead of PA11. The solubility of the obtained liquid crystal aligning agent (after freezing storage at −10 ° C. for 2 days) was good. Further, using the obtained liquid crystal aligning agent, a vertically aligned liquid crystal display element was produced in the same manner as in Example 1.

[Comparative Example 1]
A liquid crystal aligning agent was obtained in the same manner as in Example 1 except that PA1 was used instead of PA2. The obtained liquid crystal aligning agent was stored frozen at −10 ° C. for 2 days. Thereafter, when the temperature was returned to room temperature, no visible precipitate was formed. However, since it was separated into two layers, production of a vertically aligned liquid crystal display element was abandoned.

[Comparative Example 2]
4.0 g of the polyamic acid solution (PA4) synthesized in Synthesis Example 4 was diluted to 4% by weight with a mixed solvent of NMP / BC = 1/1 (weight ratio) to obtain a liquid crystal aligning agent. The obtained liquid crystal aligning agent was stored frozen at −10 ° C. for 2 days. Then, when it returned to normal temperature, the precipitation which can be visually recognized did not arise or it isolate | separated into two layers, and the solubility with respect to a solvent was favorable. Using the obtained liquid crystal aligning agent, it apply | coated to the glass substrate with an ITO electrode with the spinner similarly to Example 1. FIG. After heat drying at 80 ° C. for about 5 minutes, a heat treatment was performed at 220 ° C. for 30 minutes to form a liquid crystal alignment film. Further, the rubbing treatment was performed in the same manner as in Example 1. As a result, the film strength was weak, or the film was scraped, and the production of the vertical alignment liquid crystal display element was abandoned.

[Comparative Examples 3 to 4]
4.0 g of the polyamic acid solution (PA11) and 4.0 g of the polyamic acid solution (PA12) synthesized in Synthesis Example 11 and Synthesis Example 12 were each 4% by weight with a mixed solvent of NMP / BC = 1/1 (weight ratio). The liquid crystal aligning agent was diluted. The solubility of the obtained liquid crystal aligning agent (after freezing storage at −10 ° C. for 2 days) was good. Further, using the obtained liquid crystal aligning agent, a vertically aligned liquid crystal display element was produced in the same manner as in Example 1.

<3. Evaluation results>
The pretilt angle of the obtained vertically aligned liquid crystal display element was measured by a crystal rotation method. The evaluation results are summarized in Table 2 including the results of solubility (after freezing at −10 ° C. for 2 days) and film strength. If a high pretilt angle of about 85 to 90 ° is obtained, it is suitable for a vertically aligned liquid crystal display element.

As shown in Examples 1 to 9 and Comparative Examples 1 and 2 in Table 2, it is obtained by reacting a diamine compound containing a diamine having a side chain structure represented by the general formula (I). When the weight average molecular weight is 1.0 × 10 ^{4 to} 4.0 × 10 ^4, it can be seen that good solubility can be obtained and film shaving does not occur.
Furthermore, as shown in Comparative Example 3 and Comparative Example 4 in Table 2, a liquid crystal containing no polyamic acid obtained by reacting a diamine compound containing a diamine having a side chain structure represented by the general formula (I). Even if the weight average molecular weight is 4.0 × 10 ⁴ or more, the aligning agent does not cause film scraping, but it cannot be used for a vertically aligned liquid crystal display device because of a small pretilt angle. Recognize.

  As mentioned above, the liquid crystal aligning agent containing the polyamic acid of this invention and its derivative can be used for formation of the liquid crystal aligning film for vertical alignment liquid crystal display elements. And according to the preferable aspect of this invention, this liquid crystal aligning agent has favorable solubility, and film | membrane scraping does not generate | occur | produce the liquid crystal aligning film formed after an alignment process.

  The liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention is useful as a liquid crystal alignment film for a vertical alignment liquid crystal display element. The vertical alignment liquid crystal display element of the present invention using this liquid crystal alignment film has a wide viewing angle and can realize extremely high contrast.

Claims (19)

A liquid crystal aligning agent for a vertically aligned liquid crystal display element containing a polyamic acid or a derivative thereof, and a solvent,
A weight average molecular weight obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by the following general formula (I) with a tetracarboxylic dianhydride compound A2 is 1.0 × 10 ⁴ to 4. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising: a polyamic acid of 0.0 × 10 ⁴ or a derivative A thereof.
[In Formula (I),
R ¹ is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH—, or alkylene having 1 to 6 carbon atoms,
R ² is a group having a steroid skeleton, a group represented by the following formula (II), or an alkyl having 1 to 20 carbon atoms 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 having 2 to 6 carbon atoms in the alkyl, any —CH ₂ — may be replaced by —O—, —CH═CH— or —C≡C—,
Hydrogen bonded to the phenyl ring carbon _{is, -F, -CH 3, -OCH 3} , -OCH 2 F, may be replaced with -OCHF ₂ or -OCF _3. ]

[In the formula (II),
R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond, —O—, —COO—, —OCO—, —CONH— or alkylene having 1 to 3 carbon atoms,
R ¹³ and R ¹⁴ are each independently —F or —CH ₃ ;
Ring C is 1,4-phenylene or 1,4-cyclohexylene,
R ¹⁵ is —F, alkyl having 1 to 20 carbons, fluorine-substituted alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, —OCH ₂ F, —OCHF ₂ or —OCF ₃ ;
a, b and c each independently represents an integer of 0 to 4;
d, e and f each independently represents an integer of 0 to 3, and when f is 2 or 3, the plurality of rings C may be the same group or different groups,
g and h each independently represent an integer of 0 to 2 and d + e + f ≧ 1. ] In the diamine having a side chain structure represented by the general formula (I), R ¹ is a single bond, —O—, —COO—, —OCO—, alkylene having 1 to 2 carbon atoms, and R ² is the above-mentioned A group represented by formula (II),
In the formula (II), R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond or alkylene having 1 to 3 carbon atoms, and R ¹³ and R ¹⁴ are each independently —F or —CH ₃ , ring C is 1,4-phenylene or 1,4-cyclohexylene, R ¹⁵ is alkyl having 1 to 20 carbons or alkoxy having 1 to 20 carbons, and a, b and c are each Independently represents an integer of 0 to 1, d, e and f each independently represents an integer of 0 to 1, g and h each represents an integer of 0 to 1, and d + e + f ≧ 1 The liquid crystal aligning agent for vertically aligned liquid crystal display according to claim 1.   3. The diamine compound A1 according to claim 1, wherein the diamine compound A1 has a total content of diamine having a side chain structure represented by the general formula (I) of 30 to 100 mol% of the entire diamine. Liquid crystal aligning agent for vertically aligned liquid crystal display elements. A liquid crystal aligning agent for a vertically aligned liquid crystal display element containing a polyamic acid or a derivative thereof, and a solvent,
A weight average molecular weight obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by the following general formula (I) with a tetracarboxylic dianhydride compound A2 is 1.0 × 10 ⁴ to 4. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising: a polyamic acid of 0.0 × 10 ⁴ or a derivative A thereof.
[In Formula (I),
R ¹ is alkylene having 1 to 2 carbon atoms, and R ² is a group represented by the following formula (II). ]

[In the formula (II),
R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond, —O—, —COO—, —OCO—, —CONH— or alkylene having 1 to 3 carbon atoms,
R ¹³ and R ¹⁴ are each independently —F or —CH ₃ ;
Ring C is 1,4-phenylene or 1,4-cyclohexylene,
R ¹⁵ is —F, alkyl having 1 to 20 carbons, fluorine-substituted alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, —OCH ₂ F, —OCHF ₂ or —OCF ₃ ;
a, b and c each independently represents an integer of 0 to 4;
d, e and f each independently represents an integer of 0 to 3, and when f is 2 or 3, the plurality of rings C may be the same group or different groups,
g and h each independently represent an integer of 0 to 2 and d + e + f ≧ 1. ] In the formula (II), R ¹⁰ , R ¹¹ and R ¹² are each independently a single bond or alkylene having 1 to 3 carbon atoms, and R ¹³ and R ¹⁴ are each independently —F or —CH ₃ , ring C is 1,4-phenylene or 1,4-cyclohexylene, R ¹⁵ is alkyl having 1 to 20 carbons or alkoxy having 1 to 20 carbons, and a, b and c are each Independently represents an integer of 0 to 1, d, e and f each independently represents an integer of 0 to 1, g and h each represents an integer of 0 to 1, and d + e + f ≧ 1 The liquid crystal aligning agent for vertically aligned liquid crystal display according to claim 4.   6. The diamine compound A1 according to claim 4, wherein the diamine compound A1 has a total content of diamine having a side chain structure represented by the general formula (I) of 30 to 100 mol% of the entire diamine. Liquid crystal aligning agent for vertically aligned liquid crystal display elements. A liquid crystal aligning agent for a vertically aligned liquid crystal display element containing a polyamic acid or a derivative thereof, and a solvent,
Weight average obtained by reacting a diamine compound A1 containing a diamine having a side chain structure represented by any of the following formulas (I-13) to (I-23) with a tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element comprising a polyamic acid having a molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ or a derivative A thereof.

[In the formulas (I-13) to (I-23), R ²² is alkyl having 3 to 12 carbons or alkoxy having 3 to 12 carbons, and R ²³ is alkyl having 1 to 10 carbons or 1 carbon. -10 alkoxy. ]   The diamine compound A1 is characterized in that the total content of diamines represented by the formulas (I-13) to (I-23) is 30 to 100 mol% of the entire diamine. The liquid crystal aligning agent for vertical alignment liquid crystal display elements of description. A liquid crystal aligning agent for a vertically aligned liquid crystal display element containing a polyamic acid or a derivative thereof, and a solvent,
Weight average obtained by reacting diamine compound A1 containing a diamine having a side chain structure represented by any of the following formulas (I-16) to (I-18) with tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element comprising a polyamic acid having a molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ or a derivative A thereof.

[In the formulas (I-16) to (I-18), R ²³ is alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons. ]   The said diamine compound A1 WHEREIN: The total content of the diamine represented by the said formula (I-16)-(I-18) is 30-100 mol% of the whole diamine, It is characterized by the above-mentioned. The liquid crystal aligning agent for vertical alignment liquid crystal display elements of description. A liquid crystal aligning agent for a vertically aligned liquid crystal display element containing a polyamic acid or a derivative thereof, and a solvent,
Diamine containing a diamine having a side chain structure represented by any of the following formulas (I-16) to (I-18) and a diamine represented by the following formula (V-6) or (VI-1) It contains polyamic acid or its derivative A having a weight average molecular weight of 1.0 × 10 ^{4 to} 4.0 × 10 ⁴ obtained by reacting compound A1 with tetracarboxylic dianhydride compound A2. A liquid crystal aligning agent for a vertically aligned liquid crystal display element.
  The said diamine compound A1 WHEREIN: The total content of the diamine represented by the said formula (I-16)-(I-18) is 30-100 mol% of the whole diamine, It is characterized by the above-mentioned. The liquid crystal aligning agent for vertical alignment liquid crystal display elements of description. The vertically aligned liquid crystal display according to claim 1, wherein the polyamic acid or its derivative A has a weight average molecular weight of 1.5 × 10 ^{4 to} 2.5 × 10 ^4. Liquid crystal aligning agent for device. A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising two or more kinds of polyamic acids or derivatives thereof, and a solvent,
A) The polyamic acid or derivative A thereof according to any one of claims 1 to 13, and B) a diamine compound B1 containing a diamine represented by the following general formulas (III) to (VIII), and a tetracarboxylic acid A liquid crystal aligning agent for a vertically aligned liquid crystal display element, comprising a polyamic acid obtained by reacting the dianhydride compound B2 or a derivative B thereof.
[In the formulas (III) to (VIII),
X 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—, —S— (CH ₂ ) _m —S—, wherein m is an integer of 1-6. ,
Y is 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 may be replaced with -F or -CH ₃ . Furthermore, hydrogen bonded to the benzene ring in formula (V) may be replaced with benzyl. ]   The liquid crystal alignment for a vertically aligned liquid crystal display device according to claim 14, wherein a weight ratio of the polyamic acid or derivative A thereof to the polyamic acid or derivative B thereof is 1/99 to 50/50. Agent.   The liquid crystal alignment for a vertically aligned liquid crystal display device according to claim 14, wherein the weight ratio of the polyamic acid or its derivative A to the polyamic acid or its derivative B is 5/95 to 20/80. Agent. The tetracarboxylic dianhydride compounds A2 and B2 are each independently an aromatic tetracarboxylic dianhydride represented by the following formulas (1) to (13) and the following formulas (14) to (62). One or two or more types selected from the group consisting of aliphatic tetracarboxylic dianhydrides or alicyclic tetracarboxylic dianhydrides represented by any one of claims 1 to 16, The liquid crystal aligning agent for vertical alignment liquid crystal display elements of one term.
  The tetracarboxylic dianhydride compounds A2 and B2 each independently include pyromellitic dianhydride and / or cyclobutanetetracarboxylic dianhydride. The liquid crystal aligning agent for vertical alignment liquid crystal display elements of description. 1) A pair of substrates which are arranged opposite to each other and electrodes are arranged on both sides,
2) a vertical alignment liquid crystal display element comprising: a liquid crystal alignment film formed on the opposing surfaces of each of the pair of substrates; and 3) a vertically aligned liquid crystal layer sandwiched between the pair of substrates. ,
The said liquid crystal aligning film is a vertical alignment liquid crystal display element which is a liquid crystal aligning film formed by apply | coating the liquid crystal aligning agent as described in any one of Claims 1-18 to the said board | substrate, and heating.