JP5671797B2 - Alignment agent and liquid crystalline polyimide used therefor - Google Patents

Description

  The present invention relates to an aligning agent mainly used for manufacturing a liquid crystal display element.

  Liquid crystal display elements are used in various liquid crystal display devices such as monitors for notebook computers and desktop personal computers, viewfinders for video cameras, and projection displays. Recently, liquid crystal display devices have also been used for televisions. Furthermore, it is also used as an optoelectronic-related element such as an optical printer head, an optical Fourier transform element, or a light valve. As a conventional liquid crystal display element, a display element using a nematic liquid crystal is mainly used, and the alignment direction of the liquid crystal in the vicinity of one substrate and the liquid crystal in the vicinity of the other substrate are twisted at an angle of 90 degrees. Liquid crystal display elements such as (Twisted Nematic) mode and STN (Super Twisted Nematic) mode in which the alignment direction is twisted at an angle of usually 180 degrees or more have been put into practical use. A so-called TFT (Thin-film-transistor) mode liquid crystal display element using a thin film transistor has also been put into practical use.

  However, these liquid crystal display elements have a narrow viewing angle at which an image can be properly viewed, and when viewed from an oblique direction, luminance and contrast may be reduced, and luminance inversion may occur in a halftone. In recent years, this viewing angle problem has been caused by a TN type liquid crystal display element using an optical compensation film, a MVA (Multi-domain Vertical Alignment) mode in which vertical alignment and a technique of a protruding structure are used in combination (for example, see Patent Document 1). ) Or lateral electric field type IPS (In-Plane Switching) mode (see, for example, Patent Document 2).

  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.

  In such a liquid crystal alignment film, it is necessary to uniformly control the molecular arrangement of the liquid crystal for the uniform display characteristics of the liquid crystal display element. For this purpose, the liquid crystal molecules on the substrate are uniformly aligned in one direction. Furthermore, it is required to develop a certain tilt angle (pretilt angle) from the substrate surface. Thus, a liquid crystal alignment film that uniformly aligns the directions of liquid crystal molecules on a substrate is an important and indispensable technique in the manufacturing process of a liquid crystal display element.

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

  Industrially, a rubbing method that is simple and capable of high-speed processing of a large area is widely used as an alignment processing method. The rubbing method is a process of rubbing the surface of the liquid crystal alignment film in one direction using a cloth in which fibers of nylon, rayon, polyester, or the like are planted, and this makes it possible to obtain uniform alignment of liquid crystal molecules. However, problems such as dust generation by static rubbing and generation of static electricity have been pointed out.

Until now, the following two proposals have been made as alignment mechanisms of liquid crystals on alignment films that have been subjected to alignment treatment by rubbing treatment.
(1) Surface shape effect of liquid crystal alignment film caused by microgroove generated by rubbing treatment (2) Intermolecular interaction between liquid crystal alignment film uniaxially aligned by rubbing treatment and liquid crystal monolayer in contact with this liquid crystal alignment film Then, it was confirmed that the contribution of the surface shape effect of (1) is relatively small, and the contribution of the intermolecular interaction of (2) is dominant.

  In the case of such a rubbing method, it is generally known that a large alignment regulating force (anchoring energy) for the liquid crystal can be imparted to the polyimide film. However, in this method, the direction in which the film is rubbed by the hair implanted in the rubbing cloth is not uniform at the molecular level, and as a result, the alignment of the liquid crystal at the alignment film interface is disturbed. Furthermore, due to scratches on the film due to the contact of the cloth, when the liquid crystal display element is displayed black when no voltage is applied (normally black method), the black level will be lower than the ideal case. It was known.

  On the other hand, with respect to a photo-alignment method in which alignment treatment is performed by irradiating light, many alignment mechanisms such as a photolysis method, a photoisomerization method, a photo-dimerization method, a photo-crosslinking method have been proposed (for example, Non-Patent Document 1). , See Patent Document 3 and Patent Document 4.) In particular, since the photo-alignment method is a non-contact alignment method unlike the rubbing method, it is considered that only the intermolecular interaction (2) acts as the alignment mechanism of the liquid crystal.

  Those skilled in the art know that the photo-alignment treatment method has higher alignment uniformity than the rubbing method, and is a non-contact alignment method, so that the film is not damaged and the black level is easily improved compared to the rubbing method. It was done. In addition, the photo-alignment treatment method has many advantages because it can reduce the cause of defects during the production of liquid crystal display elements such as dust generation and static electricity. However, the anchoring energy is smaller than that of the rubbing method, and this causes a decrease in response speed and seizure, and improvement has been demanded.

  In order to overcome such disadvantages of photo-alignment, we have found a method of applying a liquid crystal aligning agent comprising a polyamic acid to a substrate, irradiating with light, and then baking by a method described in Patent Document 3, for example. . Although it has become possible to obtain a photo-alignment film having a large anchoring energy by this method, in order to obtain a liquid crystal alignment film having a sufficient anchoring energy, the light irradiation energy must be increased, Further improvements were needed.

Japanese Patent No. 2947350 Japanese Patent No. 2940354 JP 2005-275364 A Japanese Patent Laid-Open No. 11-15001

Liquid Crystal, Vol. 3, No. 4, 262 pages, 1999

  An object of the present invention is to provide an alignment film for rubbing with high alignment uniformity. Another object is to provide a photo-alignment film having good sensitivity and high stability.

  As a result of diligent research and development, the present inventors imparted anisotropy to a polyimide material having liquid crystallinity and high heat resistance by rubbing or light, and then aligning by heating to the polyimide liquid crystal temperature. As a result, the present invention was completed. The essence of the present invention is to use liquid crystalline polyimide as an alignment film material. The present invention is represented by the following item [1].

[1] A composition containing at least one polymer selected from a polyamic acid and a polyimide obtained by a dehydration reaction of the polyamic acid, the polymer being based on the total amount of film-forming components contained in the composition Is an aligning agent capable of forming a film having a liquid crystal temperature range of 100 to 300 ° C. by forming this composition into a film.

  When the alignment agent of the present invention is used as a liquid crystal alignment agent, for example, an alignment film for rubbing with high alignment uniformity can be provided. In addition, it is possible to provide a photoalignment film having good sensitivity and high stability.

Terms used in the present invention will be described.
The compound represented by the formula (I-1) may be described as the compound (I-1). Similarly, compounds represented by other formulas may be abbreviated.
The term “arbitrary” used in the definition of chemical formula means “can be freely selected not only by position but also by number”. For example, the expression “any A may be replaced with B, C, D, or E” means that one A may be replaced with B, C, D, or E, and In addition to the meaning that any may be replaced by any one of B, C, D and E, A replaced by B, A replaced by C, A replaced by D, and E replaced It also means that at least two of A may be mixed. However, when any —CH ₂ — may be replaced with another group, it is a precondition that a plurality of consecutive —CH ₂ — cannot be replaced with the same group. Further, when any —CH ₂ — may be replaced by —O—, such a replacement that results in the bonding group —O—O— is not included.
In the chemical structural formula, a group in which a letter (for example, A) is surrounded by a hexagon means a group having a ring structure (ring A).
A substituent which is described as not clearly bonded to any one of the carbons constituting the ring means that the bonding position is free as long as there is no chemical problem.
When the same symbol is used in more than one formula, it means that the ring, linking group or terminal group indicated by the symbol has the same defined range, but all formulas are within the defined range at the same time. It does not mean that they must be the same group. In such a case, the same group may be selected in a plurality of formulas, or different groups may be selected for each formula.

The present invention comprises the above item [1] and the following items [2] to [22].
[2] The aligning agent according to the item [1], wherein the polyamic acid is a polyamic acid having a photosensitive group in the main chain.

（ここに、Ｒ^１、Ｒ^２およびＲ^３は独立して芳香族の２価の基である。） [3] The aligning agent according to item [2], wherein the photosensitive group is at least one of groups represented by formulas (I) to (VI).

(Here, R ¹ , R ² and R ³ are independently an aromatic divalent group.)

[4] The polyamic acid having a photosensitive group in the main chain is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III-1), formula ( IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to at least one diamine having a photosensitive group represented by formula (VI-7) and tetracarboxylic dianhydride The aligning agent according to item [2], which is a polyamic acid obtained by reacting a product.

[5] By reacting a diamine with at least one of tetracarboxylic dianhydrides having a photosensitive group represented by formula (IV-4) and formula (VI-8), a polyamic acid having a photosensitive group in the main chain The aligning agent according to item [2], which is a polyamic acid obtained.

（ここに、Ｒ^４は炭素数６〜２０のアルキレンであり；Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンであり；そして、Ｍｅはメチルである。） [6] The polyamic acid having a photosensitive group in the main chain is represented by the formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (4), III-1), a diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) A mixture of one and at least one of the diamines represented by formula (VII-1) to formula (VII-3) and formula (VIII-1) to formula (VIII-6) is reacted with tetracarboxylic dianhydride The aligning agent according to item [2], which is a polyamic acid obtained by the method.

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; R ⁵ is optional —CH ₂ — is —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) _2. Osyl (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be replaced; and Me is methyl.)

（ここに、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。） [7] At least one of tetracarboxylic dianhydrides having a photosensitive group represented by formula (IV-4) and formula (VI-8) according to item [5], wherein the polyamic acid having a photosensitive group in the main chain Reacting a mixture with at least one of the tetracarboxylic dianhydrides represented by formula (VII-4), formula (VII-5), formula (VIII-7) and formula (VIII-8) with diamine The aligning agent according to the item [2], which is a polyamic acid obtained by the following step.

(Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replacement And alkylene having 6 to 20 carbon atoms.)

（ここに、Ａ^１、Ａ^２、Ａ^３およびＡ^４は独立してシクロへキシレンまたはフェニレンであり；Ｘ^３およびＸ^４は独立して単結合、炭素数１〜５のアルキレンまたは−Ｏ−であり；Ｘ^５およびＸ^６は独立して単結合、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−、−Ｏ−または−Ｓ−であり；Ｙ^１は−ＣＨ_２−、−Ｃ（Ｒ^１１）（Ｒ^１２）−、−ＣＯ−または−ＳＯ_２−であり、Ｒ^１１およびＲ^１２は独立して水素、炭素数１〜１２のアルキル、または炭素数１〜１２のフッ素化アルキルであり；ｍ１、ｍ２、ｍ３、ｍ４およびｎは独立して０または１を表す。そして、上記のシクロヘキシレンおよびフェニレンにおいて、任意の水素は炭素数１〜４のアルキルまたはベンジルで置き換えられてもよく、これらの置換基の結合位置は任意である。但し、Ａ^１、Ａ^２、Ａ^３およびＡ^４のすべてが１，４−フェニレンであるとき、Ｘ^３、Ｘ^４、Ｘ^５およびＸ^６はいずれも単結合ではない。）

（ここに、Ｘ^１およびＸ^２は単結合、−Ｏ−、−ＣＯＯ−、−ＯＣＯ−、−ＮＨ−、−ＣＯＮＨ−、または炭素数１〜１２のアルキレンであり；Ｇ^１およびＧ^２は単結合、または炭素数６〜１２の芳香族環および炭素数３〜１２の脂環式環から選ばれる１〜３個の環を含む２価の基であり；Ｒ^６は水素、フッ素、−ＣＮ、−ＯＨ、炭素数１〜３０のアルキル、炭素数１〜３０のフッ素化アルキルまたは炭素数１〜３０のアルコキシであり；そして、Ｘ^１、Ｇ^１、Ｘ^２およびＧ^２の全てが単結合である場合は、Ｒ^６は炭素数３〜３０のアルキル、炭素数３〜３０のフッ素化アルキルまたは炭素数３〜３０のアルコキシであり、Ｇ^２が単結合でありＸ^２が単結合でもなくアルキレンでもない場合は、Ｒ^６は水素または炭素数３〜３０のアルキルであり、Ｇ^１およびＧ^２が共に単結合である場合は、Ｘ^１、Ｘ^２およびＲ^６の合計の炭素数が３以上である。）

（ここに、Ｒ^７は水素または炭素数１〜１２のアルキルであり；環Ｂは任意の水素が炭素数１〜４のアルキルで置き換えられてもよい１，４−フェニレン、または任意の水素が炭素数１〜４のアルキルで置き換えられてもよい１，４−シクロへキシレンであり；Ｘ^０は単結合または炭素数１〜５のアルキレンであり、そしてｓは０〜３の整数であり；ｓが２または３であるとき、複数の環Ｂはすべて同じ環であってもよく、少なくとも２つの異なる環で構成されてもよく、複数のＸ^０もすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよく；Ｚ^１およびＺ^２は独立して単結合、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−または−Ｏ−であり、ｔ１およびｔ２は独立して０〜３の整数であり；ｔ１が２または３であるとき、複数のＺ^１はすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよく；ｔ２が２または３であるとき、複数のＺ^２はすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよい。 [8] A polyamic acid having a photosensitive group in the main chain is represented by the formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (4), III-1), a diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) Item [2], which is a polyamic acid obtained by reacting a mixture of one and at least one selected from diamines represented by formulas (2) to (4) with tetracarboxylic dianhydride. Orientation agent.

(Where A ¹ , A ² , A ³ and A ⁴ are independently cyclohexylene or phenylene; X ³ and X ⁴ are independently a single bond, alkylene having 1 to 5 carbon atoms or —O— X ⁵ and X ⁶ are each independently a single bond, —CH ₂ —, —CH ₂ CH ₂ —, —O— or —S—; Y ¹ is —CH ₂ —, —C (R ¹¹ ) (R ¹² ) —, —CO— or —SO ₂ —, wherein R ¹¹ and R ¹² are independently hydrogen, alkyl having 1 to 12 carbons, or fluorinated alkyl having 1 to 12 carbons; m1, m2, m3, m4 and n independently represent 0 or 1. In the above cyclohexylene and phenylene, any hydrogen may be replaced by alkyl or benzyl having 1 to 4 carbon atoms. The bonding position of the substituent of It. ^However, when all of A ^1, A 2, ^{A 3} and ^{A 4} is ^{1,4-phenylene, X 3, X 4, X} 5 and ^{X 6} are both not a single bond.)

(Where X ¹ and X ² are a single bond, —O—, —COO—, —OCO—, —NH—, —CONH—, or alkylene having 1 to 12 carbon atoms; G ¹ and G ² are A single bond or a divalent group containing 1 to 3 rings selected from an aromatic ring having 6 to 12 carbon atoms and an alicyclic ring having 3 to 12 carbon atoms; R ⁶ is hydrogen, fluorine,- CN, —OH, alkyl having 1 to 30 carbons, fluorinated alkyl having 1 to 30 carbons or alkoxy having 1 to 30 carbons; and all of X ¹ , G ¹ , X ² and G ² are simple When it is a bond, R ⁶ is alkyl having 3 to 30 carbons, fluorinated alkyl having 3 to 30 carbons or alkoxy having 3 to 30 carbons, and G ² is a single bond and X ² is a single bond. If not a rather alkylene, ^{R 6} is hydrogen or number 3-30 carbon Is alkyl, when ^{G 1} and ^{G 2} are both single ^bonds, the total number of carbon atoms of X 1, ^{X 2} and ^{R 6} is 3 or more.)

(Where R ⁷ is hydrogen or alkyl having 1 to 12 carbons; ring B is 1,4-phenylene in which any hydrogen may be replaced by alkyl having 1 to 4 carbons, or any hydrogen is 1,4-cyclohexylene optionally substituted by alkyl having 1 to 4 carbons; X ⁰ is a single bond or alkylene having 1 to 5 carbons, and s is an integer of 0 to 3; When s is 2 or 3, the plurality of rings B may all be the same ring, may be composed of at least two different rings, and the plurality of X ⁰ may all be the same group, and at least May be composed of two different groups; Z ¹ and Z ² are independently a single bond, —CH ₂ —, —CH ₂ CH ₂ — or —O—, and t 1 and t 2 are independently 0 to 0 An integer of 3; when t1 is 2 or 3 All of the plurality of Z ¹ may be the same group, may be composed of at least two different groups; when t2 is 2 or 3, all of the plurality of Z ² may be the same group, at least It may be composed of two different groups.

[9] The polyamic acid having a photosensitive group in the main chain is represented by the formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (4), III-1), a diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) 1, at least one of the diamines represented by the formula (VII-1) to the formula (VII-3) and the formula (VIII-1) to the formula (VIII-6) according to the item [6], and [8] In the item [2], the polyamic acid obtained by reacting at least one mixture selected from the diamines represented by the formulas (2) to (4) described in the item with a tetracarboxylic dianhydride The aligning agent described.

（ここに、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。） [10] The tetracarboxylic dianhydride has the formula (A-1), formula (A-2), formula (A-12), formula (A-14), formula (A-18), formula (A-20). ), Formula (A-21), formula (A-37), formula (VII-4), formula (VII-5), formula (VIII-7) and tetracarboxylic acid represented by formula (VIII-8) The aligning agent according to any one of [4], [6], [8] and [9], which is at least one of dianhydrides.

(Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replacement And alkylene having 6 to 20 carbon atoms.)

（ここに、Ｒ^４は炭素数６〜２０のアルキレンであり；Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンであり；そして、Ｍｅはメチルである。） [11] The item [5] or [5], wherein the diamine is at least one of diamines represented by formulas (VII-1) to (VII-3) and (VIII-1) to (VIII-6): The alignment agent according to item 7].

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; R ⁵ is optional —CH ₂ — is —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) _2. Osyl (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be replaced; and Me is methyl.)

（ここに、Ｒ^４は炭素数６〜２０のアルキレンであり；そして、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。）

（ここに、Ｍｅはメチルである。） [12] Tetracarboxylic acid dianhydride represented by formula (VIII-7) and formula (VIII-8), wherein the polyamic acid is at least one of diamines represented by formula (VII-1) to formula (VII-3) A polyamic acid obtained by reacting at least one of the compounds or at least one diamine represented by formula (VIII-1) to formula (VIII-6) with formula (VII-4) and formula (VII-5) The aligning agent according to item [1], which is a polyamic acid obtained by reacting at least one of tetracarboxylic dianhydrides represented by:

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; and R ⁵ is any —CH ₂ — being —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) ₂ OSi (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be substituted.

(Where Me is methyl.)

[13] Anisotropy is imparted to the film obtained by applying the aligning agent according to the item [1] to the substrate by rubbing or light irradiation, and then heated to the liquid crystal temperature range of the film to change the film anisotropy. Liquid crystal alignment film obtained by increasing.

[14] Anisotropy is imparted to the film obtained by applying the alignment agent according to any one of [2] to [11] to the substrate by light irradiation, and then heated to a liquid crystal temperature range of the film. A liquid crystal alignment film obtained by increasing the anisotropy of the film.

[15] By imparting rubbing anisotropy to the film obtained by applying the alignment agent according to item [12] to the substrate, and then heating the film to the liquid crystal temperature range to increase the film anisotropy. Obtained liquid crystal alignment film.

[16] A liquid crystal display device having the liquid crystal alignment film according to any one of [13] to [15].

ここに、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンであり；Ｒ^９はジアミンの残基である。 [17] Polyamic acid containing a structural unit represented by formula (IX) and having a liquid crystal temperature range at 100 to 300 ° C., or a precursor thereof, polyamic acid:

Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replaces Optionally alkylene of 6 to 20 carbon atoms; R ⁹ is a residue of a diamine.

ここに、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンであり；Ｒ^９はジアミンの残基である。 [18] Polyamic acid that includes a structural unit represented by the formula (X) and has a liquid crystal temperature range of 100 to 300 ° C. or a precursor thereof:

Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replaces Optionally alkylene of 6 to 20 carbon atoms; R ⁹ is a residue of a diamine.

[19] R ⁵ is alkylene having 6 to 12 carbon atoms, and R ⁹ is represented by the formula (I-1) to the formula (I-3), the formula (II-1) to the formula (II-3), the formula ( III-1), the residue of any one of diamines represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) The polyamic acid which is a polyimide or a precursor thereof according to the item [17] or [18], which is a group.

（ここに、Ｍｅはメチルである。） [20] R ⁵ is alkylene having 6 to 12 carbon atoms, and R ⁹ is any one residue of diamines represented by formula (VIII-1) to formula (VIII-6). ] The polyamic acid which is a polyimide or its precursor as described in a term or a [18] term.

(Where Me is methyl.)

ここに、Ｒ^５は炭素数６〜１２のアルキレンであり；Ｒ^９は式（Ｉ−１）〜式（Ｉ−３）、式（II−１）〜式（II−３）、式（III−１）、式（IV−１）〜式（IV−３）、式（Ｖ−１）および式（VI−１）〜式（VI−７）で表されるジアミンのいずれか１つの残基であり；Ｒ^１０は式（VIII−１）〜式（VIII−６）で表されるジアミンのいずれか１つの残基である。

（ここに、Ｍｅはメチルである。） [21] Polyamic acid which is a polyimide or a precursor thereof having a liquid crystal temperature range at 100 to 300 ° C., including a structural unit represented by formula (IX) and a structural unit represented by formula (XI):

Here, R ⁵ is alkylene having 6 to 12 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), a residue of any one of diamines represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) R ¹⁰ is a residue of any one of the diamines represented by formula (VIII-1) to formula (VIII-6).

(Where Me is methyl.)

ここに、Ｒ^５は炭素数６〜１２のアルキレンであり；Ｒ^９は式（Ｉ−１）〜式（Ｉ−３）、式（II−１）〜式（II−３）、式（III−１）、式（IV−１）〜式（IV−３）、式（Ｖ−１）および式（VI−１）〜式（VI−７）で表されるジアミンのいずれか１つの残基であり；Ｒ^１０は式（VIII−１）〜式（VIII−６）で表されるジアミンのいずれか１つの残基である。

（ここに、Ｍｅはメチルである。） [22] Polyamic acid, which is a polyimide or a precursor thereof, containing a structural unit represented by formula (X) and a structural unit represented by formula (XII) and having a liquid crystal temperature range at 100 to 300 ° C .:

Here, R ⁵ is alkylene having 6 to 12 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), a residue of any one of diamines represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) R ¹⁰ is a residue of any one of the diamines represented by formula (VIII-1) to formula (VIII-6).

(Where Me is methyl.)

  The aligning agent of the present invention is a composition containing at least one polymer selected from polyamic acid and polyimide obtained by dehydration reaction of the polyamic acid, and is based on the total amount of film-forming components contained in the composition. The ratio of the polymer is 50 to 100% by weight. By depositing this composition, a film having a liquid crystal temperature range between 100 ° C. and 300 ° C. can be formed. That is, this alignment agent is applied to a substrate to form a film, and anisotropy is given to the film by rubbing or irradiating, and then the film is heated to the liquid crystal temperature range of the film, whereby the orientation is increased and high. An alignment film having alignment properties can be formed. Moreover, it can be set as a film | membrane with high thermal and chemical stability by using the aligning agent which contains the said polymer as a main component.

  When the polyamic acid used in the present invention is polyimide, the glass transition point is smaller than that of normal polyimide because the polymer main chain is easy to move, and is below the liquid crystal temperature. Therefore, with the aligning agent of the present invention having such a polyamic acid as a main component, a film having a high imidization ratio can be obtained even by firing at a relatively low temperature. In the following description, unless otherwise specified, “polyamic acid used in the present invention” is simply referred to as “polyamic acid”.

  As described above, the alignment film of the present invention exhibits its performance by heating to the liquid crystal temperature range of the material. When anisotropy is imparted to a film by a rubbing method, an orientation agent is applied to the substrate, the solvent is removed by pre-baking, and then rubbing is performed after baking at about 200 ° C. in order to prevent the film from being scraped. Done. However, if it is possible to prevent the film from being scraped by selecting materials, it is possible to perform rubbing after pre-baking and simultaneously perform baking and heat treatment for increasing anisotropy at about 200 ° C.

  Since the photo-alignment method can impart anisotropy to the alignment film in a non-contact manner, there is no fear of film scraping. That is, the photo-alignment method is more preferable as a method for imparting anisotropy to the alignment film of the present invention, since polyamic acid is used and photo-alignment can be followed by thermal imidization and heat treatment at the same time. For this reason, it is preferable to select a material whose thermal imidation temperature is within the liquid crystal temperature range.

  Although the limit temperature of the heat treatment may be restricted depending on the type of the substrate, a film having a liquid crystal temperature range in the range of 100 to 300 ° C. can be formed by using the alignment agent of the present invention. At this time, when forming an alignment film for the nematic liquid crystal used, a material having a liquid crystal temperature range of preferably 150 to 300 ° C., more preferably 180 to 300 ° C. in order to maintain alignment stability. It is desirable to select.

  In order to use the photo-alignment method, the aligning agent of the present invention preferably contains a polymer having a photosensitive group. As this photosensitive group, all known photosensitive groups having photo-alignment ability can be selected. However, when a photosensitive group that exhibits orientation ability by photodimerization or photolysis is used, the liquid crystal temperature range of the material is likely to change with the light irradiation conditions. Therefore, it is preferable to use a photoisomerization type photosensitive group in the present invention.

That is, in the present invention, it is preferable to use a polymer having at least one of the following photosensitive groups in the main chain.

R ¹ , R ² and R ³ are independently aromatic divalent groups, preferred examples of which are 1,4-phenylene, 1,3-phenylene, 4,4′-biphenylene and diphenylmethane-4,4. '-Diyl. Any hydrogen in these rings may be replaced with methyl, methoxy, trifluoromethyl, methyloxycarbonyl, fluorine or chlorine. Of these groups, 1,4-phenylene and 1,3-phenylene are more preferred, and 1,4-phenylene is most preferred.

  By selecting the photosensitive groups represented by the formulas (I) to (VI), it is possible to maximize the characteristics of the photo-alignment agent of the present invention that have high photo-alignment properties and high sensitivity. There are two isomers of cis or trans in the double bond of the photosensitive group of formula (III) and formula (V), and any of these isomers may be used for the photoalignment agent of the present invention. Absent.

  In order to obtain a polyamic acid having at least one photosensitive group represented by formulas (I) to (VI) in the main chain, a diamine or / and carboxylic dianhydride having such a photosensitive group is used as a raw material. May be used. In order to obtain particularly high photo-alignment properties, it is preferable to use a raw material having a photosensitive group in diamine.

Preferred examples of the diamine having such a photosensitive group and tetracarboxylic dianhydride include compound (I-1) to compound (I-3), compound (II-1) to compound (II-3), compound ( III-1), Compound (IV-1) to Compound (IV-4), Compound (V-1), and Compound (VI-1) to Compound (VI-8). In the following description, tetracarboxylic dianhydride may be abbreviated as acid anhydride.

In producing a polyamic acid, a diamine or acid anhydride having no photosensitive group can be used in combination with the above compound. At this time, in order to easily reduce the Tg of the polyimide obtained by the dehydration reaction of the polyamic acid, it is preferable to select a diamine or acid anhydride that can introduce an alkylene having 6 to 20 carbon atoms into the main chain of the polymer. For more reducing the tg, any -CH ₂ in the alkylene - is _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO It may be replaced with-. As such diamine and acid anhydride, compounds represented by the following formulas (VII-1) to (VII-5) are particularly preferable.

ここに、Ｒ^４は炭素数６〜２０のアルキレンであり、好ましい炭素数は６〜１２である。Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。好ましいＲ^５は１つの−ＣＨ_２−が−Ｏ−で置き換えられてもよい炭素数６〜１２のアルキレンである。そして、Ｒ^５のより好ましい例は基中の−ＣＨ_２−に関する置き換えがない炭素数６〜１２のアルキレン、即ち−Ｃ_６Ｈ_１２−〜−Ｃ_１２Ｈ_２４−である。

Here, R ⁴ is alkylene having 6 to 20 carbon atoms, and preferably 6 to 12 carbon atoms. R ⁵ is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in may be replaced It is alkylene having 6 to 20 carbon atoms. Preferred R ⁵ is alkylene having 6 to 12 carbons in which one —CH ₂ — may be replaced by —O—. A more preferred example of R ⁵ is alkylene having 6 to 12 carbon atoms, ie, —C ₆ H ₁₂ — to —C ₁₂ H ₂₄ —, in which —CH ₂ — in the group is not replaced.

  And in order to make liquid crystallinity easy to express, it is also preferable to use together the diamine or acid anhydride which combined the aromatic ring assembly and two amino groups or two carboxyl groups in series as much as possible. As such diamines and acid anhydrides, compounds represented by the following formulas (VIII-1) to (VIII-8) are particularly preferable.

これらの式において、Ｍｅはメチルである。

In these formulas, Me is methyl.

  In the present invention, diamines other than the diamines mentioned above can be used in combination. For example, when an alignment film is used as an alignment film for a nematic liquid crystal composition in a liquid crystal display application, it has a high voltage holding ratio (VHR) and exhibits characteristics such as hardly causing seizure. Diamines can be used.

式（２）において、Ａ^１、Ａ^２、Ａ^３およびＡ^４は独立してシクロへキシレンまたはフェニレンであり；Ｘ^３およびＸ^４は独立して単結合、炭素数１〜５のアルキレンまたは−Ｏ−であり；Ｘ^５およびＸ^６は独立して単結合、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−、−Ｏ−または−Ｓ−であり；Ｙ^１は−ＣＨ_２−、−Ｃ（Ｒ^１１）（Ｒ^１２）−、−ＣＯ−または−ＳＯ_２−であり、Ｒ^１１およびＲ^１２は独立して水素、炭素数１〜１２のアルキル、または炭素数１〜１２のフッ素化アルキルであり、好ましくは水素、メチルまたは−ＣＦ_３であり；ｍ１、ｍ２、ｍ３、ｍ４およびｎは独立して０または１を表す。そして、上記のシクロヘキシレンおよびフェニレンにおいて、任意の水素は炭素数１〜４のアルキルまたはベンジルで置き換えられてもよく、これらの置換基の結合位置は化学的に問題のない範囲内で自由である。ただし、Ａ^１、Ａ^２、Ａ^３およびＡ^４が１，４−フェニレンの場合、Ｘ^３、Ｘ^４、Ｘ^５、およびＸ^６が単結合であることはない。 Suitable examples of such known diamines include diamines represented by the formula (2).

In formula (2), A ¹ , A ² , A ³ and A ⁴ are each independently cyclohexylene or phenylene; X ³ and X ⁴ are each independently a single bond, alkylene having 1 to 5 carbon atoms or — X ⁵ and X ⁶ are each independently a single bond, —CH ₂ —, —CH ₂ CH ₂ —, —O— or —S—; Y ¹ is —CH ₂ —, —C ( R ¹¹ ) (R ¹² ) —, —CO— or —SO ₂ —, wherein R ¹¹ and R ¹² are independently hydrogen, alkyl having 1 to 12 carbons, or fluorinated alkyl having 1 to 12 carbons. Yes, preferably hydrogen, methyl or —CF ₃ ; m1, m2, m3, m4 and n independently represent 0 or 1. In the above cyclohexylene and phenylene, any hydrogen may be replaced by alkyl or benzyl having 1 to 4 carbon atoms, and the bonding position of these substituents is free as long as there is no chemical problem. . However, when A ¹ , A ² , A ^3, and A ⁴ are 1,4-phenylene, X ³ , X ⁴ , X ⁵ , and X ⁶ are not single bonds.

Preferred examples of the diamine represented by the formula (2) are shown below.

  Among these, from the viewpoint of imparting a high VHR to the liquid crystal alignment film and suppressing the image sticking phenomenon, Formula (2-6) to Formula (2-24), Formula (2-36), Formula (2-42), Formula Diamines represented by (2-43) or formula (2-48) to formula (2-52) are more preferred, and formula (2-6), formula (2-11), formula (2-12), formula The diamine represented by (2-13), formula (2-17), formula (2-22), formula (2-23), formula (2-24), or formula (2-49) is more preferable.

  The proportion of the diamine of formula (2) in the present invention can be arbitrarily selected according to the target orientation and electrical characteristics. However, since the liquid crystallinity is lowered when the use ratio of these diamines is large, the use ratio is preferably in the range of 0 to 30 mol% of the total amount of diamine used when synthesizing the polyamic acid. More preferably, it is 10 mol%.

Another example of a diamine having no photosensitive group that can be suitably used for producing a polyamic acid is a diamine having a side chain group represented by Formula (3) or Formula (4).

In Formula (3), X ¹ and X ² are each independently a single bond, —O—, —COO—, —OCO—, —NH—, —CONH—, or alkylene having 1 to 12 carbons; G ¹ And G ^{2 each} independently represents a single bond or a divalent group containing 1 to 3 rings selected from an aromatic ring having 6 to 12 carbon atoms and an alicyclic ring having 3 to 12 carbon atoms; R ⁶ represents hydrogen, fluorine, —CN, —OH, alkyl having 1 to 30 carbons, fluorinated alkyl having 1 to 30 carbons or alkoxy having 1 to 30 carbons. However, when all of X ¹ , G ¹ , X ² and G ² are a single bond, R ⁶ is alkyl having 3 to 30 carbons, fluorinated alkyl having 3 to 30 carbons or 3 to 30 carbons. When G ² is a single bond and X ² is neither a single bond nor alkylene; R ⁶ is hydrogen or alkyl; and when G ¹ and G ² are both single bonds, The total carbon number of X ¹ , X ² and R ⁶ is 3 or more.

In the above formula (3), the two amino groups are bonded to the carbon of the benzene ring, but the bonding position relationship between the two amino groups is preferably meta or para. The two amino groups are preferably bonded to the 3rd and 5th positions or the 2nd and 5th positions, respectively, when the bonding position of X1 is the ^1st position. It is particularly preferable.

式（４）において、Ｒ^７は水素または炭素数１〜１２のアルキルであり；環Ｂは任意の水素が炭素数１〜４のアルキルで置き換えられてもよい１，４−フェニレン、または任意の水素が炭素数１〜４のアルキルで置き換えられてもよい１，４−シクロへキシレンであり；Ｘ^０は単結合または炭素数１〜５のアルキレンであり、そしてｓは０〜３の整数であり；ｓが２または３であるとき、複数の環Ｂはすべて同じ環であってもよく、少なくとも２つの異なる環で構成されてもよく、複数のＸ^０もすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよく；Ｚ^１およびＺ^２は独立して単結合、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−または−Ｏ−であり、ｔ１およびｔ２は独立して０〜３の整数であり；ｔ１が２または３であるとき、複数のＺ^１はすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよく；ｔ２が２または３であるとき、複数のＺ^２はすべて同じ基であってもよく、少なくとも２つの異なる基で構成されてもよい。

In the formula (4), R ⁷ is hydrogen or alkyl having 1 to 12 carbons; ring B is 1,4-phenylene in which any hydrogen may be replaced by alkyl having 1 to 4 carbons, or any Hydrogen is 1,4-cyclohexylene optionally substituted with alkyl having 1 to 4 carbons; X ⁰ is a single bond or alkylene having 1 to 5 carbons, and s is an integer of 0 to 3 Yes; when s is 2 or 3, the plurality of rings B may all be the same ring, may be composed of at least two different rings, and the plurality of X ⁰ may all be the same group May be composed of at least two different groups; Z ¹ and Z ² are independently a single bond, —CH ₂ —, —CH ₂ CH ₂ — or —O—, and t 1 and t 2 are independently An integer from 0 to 3; t1 is 2 or 3 Rutoki, all of the plurality of Z ¹ may be the same group, may be composed of at least two different groups; when t2 is 2 or 3, even all of the plurality of Z ² are the same group It may well be composed of at least two different groups.

Preferred examples of the diamine represented by the formula (3) are shown below.

In the formula (3-1) to the formula (3-25), R ²⁰ is alkyl or alkoxy having 1 to ²⁰ carbons, preferably alkyl having 5 to 16 carbons. R ²¹ is alkyl or alkoxy having 1 to 20 carbons, preferably alkyl having 3 to 10 carbons. R ²² is alkyl having 4 to 20 carbons, preferably alkyl having 6 to 16 carbons. R ²³ is alkyl having 6 to 20 carbon atoms, preferably alkyl having 8 to 20 carbon atoms. R ²⁴ is alkyl or alkoxy having 3 to 20 carbon atoms, preferably alkyl having 5 to 12 carbon atoms. R ²⁵ is alkyl having 1 to 20 carbons or alkoxy, preferably alkyl having 3 to 10 carbons.

  Among these diamines, more preferred examples are represented by each of formula (3-1), formula (3-2), formula (3-4), formula (3-5), and formula (3-6). More preferred examples are diamines represented by formula (3-1) and formula (3-2), respectively.

Preferred examples of the diamine represented by the formula (4) are shown below.

In Formula (4-1) to Formula (4-16), R ²⁶ is hydrogen, alkyl having 1 to 12 carbons or alkoxy, and preferably alkyl having 4 to 7 carbons.

  The ratio of the diamine having a side chain group represented by formula (3) or formula (4) in the present invention can be arbitrarily selected according to the desired orientation, electrical characteristics, or pretilt angle. In particular, in order to express a pretilt angle of 2 degrees or more, the use ratio is preferably 1 to 50 mol%, and preferably 5 to 30 mol%, based on the total amount of diamine used in producing the polyamic acid. Is more preferable. However, if the ratio of the diamine having a side chain group of (3) or (4) is large, the liquid crystallinity is lowered, so that it is preferable to minimize the amount.

  Of the diamines having a side chain group of formula (3) or formula (4), in order to maintain the liquid crystal properties of the alignment film of the present invention, formula (3-5), formula (3-6) or It is preferred to select a diamine of formula (3-10).

式（１５）において、Ｒ^３０およびＲ^３１はそれぞれ独立して炭素数１〜３のアルキルまたはフェニルであり、Ｒ^３２は炭素数１〜６のアルキレン、フェニレンまたはアルキル置換されたフェニレンであり、ｙは１〜１０の整数である。 In the present invention, in addition to the above diamine, at least one of siloxane-based diamines may be used. Preferable examples of the siloxane-based diamine include diamine represented by the formula (15).

In the formula (15), R ³⁰ and R ³¹ are each independently alkyl or phenyl having 1 to 3 carbon atoms, R ³² is alkylene, phenylene or alkyl-substituted phenylene having 1 to 6 carbon atoms, y Is an integer from 1 to 10.

これらの式において、Ｍｅはメチルであり、式（１５−２）のポリマーの分子量は８５０〜３０００である。 Specific examples of the diamine represented by the formula (15) include the following compounds or polymers.

In these formulas, Me is methyl and the molecular weight of the polymer of formula (15-2) is 850 to 3000.

  The addition amount of these siloxane-based diamines is preferably 0.5 to 30 mol% with respect to the total amount of diamine used as a raw material when producing polyamic acid for the purpose of expressing the above effects and preventing deterioration of other properties. 1 to 10 mol% is more preferable.

  According to the required characteristics of the alignment film, a known acid anhydride having excellent electric characteristics, such as high voltage holding ratio (VHR) and hardly causing seizure, can be used when producing polyamic acid.

  The acid anhydride which is a raw material for producing polyamic acid can be selected from known compounds without limitation. The acid anhydride may belong to any group of aromatic (including heteroaromatic ring) acid anhydrides and aliphatic (including heterocyclic) acid anhydrides. The polyimide or polyamic acid preferably has a structure that does not contain oxygen or sulfur such as an ester or ether bond that tends to cause a decrease in the electrical characteristics of the liquid crystal display element. Therefore, it is preferable that the acid anhydride also has a structure containing no oxygen or sulfur. However, even if it has such a structure, there is no problem as long as the amount is within a range that does not adversely affect the electrical characteristics.

The acid anhydride is represented by the formula (20).

（Ｇ^３は単結合、炭素数１〜１２のアルキレン、１，４−フェニレン、または１，４−シクロヘキシレンであり、Ｘ^７は独立して単結合または−ＣＨ_２−を表す。）

（Ｒ^４１、Ｒ^４２、Ｒ^４３およびＲ^４４は独立して水素、メチル、エチルまたはフェニルを表す。）

（環Ｄ^１はシクロヘキサン環またはベンゼン環を表す。） Preferred examples of R ⁴⁰ in formula (20) are tetravalent groups represented by formula (21) to formula (29).

(G ³ is a single bond, alkylene having 1 to 12 carbon atoms, 1,4-phenylene, or 1,4-cyclohexylene, and X ⁷ independently represents a single bond or —CH ₂ —.)

(R ⁴¹ , R ⁴² , R ⁴³ and R ⁴⁴ independently represent hydrogen, methyl, ethyl or phenyl.)

(Ring D ¹ represents a cyclohexane ring or a benzene ring.)

（Ｇ^４は単結合、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−、−Ｏ−、−ＣＯ−、−Ｓ−、−Ｃ（ＣＨ_３）_２−、または−Ｃ（ＣＦ_３）_２−であり、環Ｄ^２は独立してシクロヘキサン環またはベンゼン環を表す。）

（Ｒ^４５は水素またはメチルを表す。）

（Ｘ^８は独立して単結合または−ＣＨ_２−であり、ｖは１または２を表す。）

^{(G 4} represents a single _{bond, -CH 2 -, - CH 2} CH 2 -, - O -, - CO -, - S -, - C (CH 3) 2 -, or -C _{(CF 3) 2} - with And ring D ² independently represents a cyclohexane ring or a benzene ring.)

(R ⁴⁵ represents hydrogen or methyl.)

(X ⁸ is independently a single bond or —CH ₂ —, and v represents 1 or 2.)

（Ｘ^６は単結合または−ＣＨ_２−を表す。）

（Ｒ^４６は水素、メチル、エチルまたはフェニルであり、環Ｄ^３はシクロヘキサン環またはベンゼン環を表す。）

（ｗ１およびｗ２は独立して０または１を表す。）

(X ⁶ represents a single bond or —CH ₂ —).

(R ⁴⁶ is hydrogen, methyl, ethyl or phenyl, and ring D ³ represents a cyclohexane ring or a benzene ring.)

(W1 and w2 independently represent 0 or 1)

Specific examples of the acid anhydride include compounds of the following formulas (A-1) to (A-44).

  In these acid anhydrides, for the purpose of maintaining the liquid crystallinity of the polyamic acid, the formula (A-1), formula (A-2), formula (A-12), formula (A-14), formula (A- 18), a compound of formula (A-20), formula (A-21) or formula (A-37) is preferably used. From the viewpoint of improving the photo-alignment ability of the alignment film, the formula (A-1), the formula (A-2), the formula (A-12), the formula (A-14), the formula (A-18), the formula ( A-20), a formula (A-21), a formula (A-28), a formula (A-30), a formula (A-37) or a compound of the formula (A-40) is preferably used. -1), a compound of formula (A-12), formula (A-14) or formula (A-18) is particularly preferably used. Furthermore, from the viewpoint of improving VHR of the liquid crystal alignment film or reducing coloring, the formula (A-14), the formula (A-18), the formula (A-19), the formula (A-20), and the formula (A- 21), Formula (A-28), Formula (A-29), Formula (A-30), Formula (A-32), Formula (A-39), Formula (A-40), Formula (A-41) ), The formula (A-43), or the compound of the formula (A-44) is preferably used. The formula (A-14), the formula (A-18), the formula (A-21), or the formula (A- It is particularly preferred to use the compound 44). The acid anhydride is not limited to these, and other known compounds may be used as long as the object of the present invention is achieved. These acid anhydrides may be used alone or in combination of two or more.

In the present invention, a polyamic acid is produced by reacting the above diamine and acid anhydride in appropriate combination. The first preferable example of this polyamic acid is compound (I-1) to compound (I-3), compound (II-1) to compound (II-3), compound (III-1) which are diamines having a photosensitive group. ), Compound (IV-1) to compound (IV-3), compound (V-1) and compound (VI-1) to compound (VI-7), and an acid anhydride. Polyamic acid.

Preferred examples of the acid anhydride used at this time include compound (A-1), compound (A-2), compound (A-12), compound (A-14), compound (A-18), and compound (A -20), compound (A-21), compound (A-37), compound (VII-4), compound (VII-5), compound (VIII-7) and acid selected from compound (VIII-8) Anhydrous. Compound (VII-4) and compound (VII-5) are particularly preferable.

（ここに、Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。そして、Ｒ^５は−Ｃ_６Ｈ_１２−〜−Ｃ_１２Ｈ_２４−のいずれか１つであることが好ましい。）

(Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replacement And C 5-20 alkylene which may be used, and R ⁵ is preferably any one of —C ₆ H ₁₂ — to —C ₁₂ H ₂₄ —.

The second preferred example of the polyamic acid is a reaction of diamine with at least one of the acid anhydrides represented by the formulas (IV-4) and (VI-8), which are acid anhydrides having the above-mentioned photosensitive group. Is a polyamic acid obtained.

（ここに、Ｒ^４は炭素数６〜２０のアルキレンであり、好ましい炭素数は６〜１２である。Ｒ^５は任意の−ＣＨ_２−が−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−Ｓｉ（ＣＨ_３）_２ＯＳｉ（ＣＨ_３）_２−または−ＣＯＯ−で置き換えられてもよい炭素数６〜２０のアルキレンである。そして、Ｒ^５は−Ｃ_６Ｈ_１２−〜−Ｃ_１２Ｈ_２４−のいずれか１つであることが好ましい。） Preferable examples of the diamine used at this time are diamines selected from the compounds represented by formula (VII-1) to formula (VII-3) and formula (VIII-1) to formula (VIII-6).

(Here, R ⁴ is alkylene having 6 to 20 carbon atoms, and preferably 6 to 12 carbon atoms. R ⁵ is optional —CH ₂ — is —O—, —NH—, —N (CH ₃ )-, —Si (CH ₃ ) ₂ OSi (CH ₃ ) ₂ — or —COO— is alkylene having 6 to 20 carbon atoms, and R ⁵ is —C ₆ H ₁₂ — to —. it is preferably one of) - C ₁₂ H _24.

（これらの式におけるＭｅはメチルである。）

(Me in these formulas is methyl.)

  A third preferred example of the polyamic acid is the compound (I-1) to compound (I-3), compound (II-1) to compound (II-3), compound (III-1), compound (IV). -1) to compound (IV-3), compound (V-1) and compound (VI-1) to compound (VI-7) and at least one diamine selected from the compound (VII-1) to compound A polyamic acid obtained by reacting a mixture of (VII-3) and at least one diamine selected from compound (VIII-1) to compound (VIII-6) with an acid anhydride. Preferred examples of the acid anhydride include the compound (A-1), the compound (A-2), the compound (A-12), the compound (A-14), the compound (A-18), and the compound (A- 20) Acid anhydride selected from Compound (A-21), Compound (A-37), Compound (VII-4), Compound (VII-5), Compound (VIII-7) and Compound (VIII-8) It is a thing. And when the diamine combined with the diamine which has a photosensitive group is selected from a compound (VII-1)-a compound (VII-3), especially preferable acid anhydride is a compound (VIII-7) or a compound (VIII-8). When the diamine combined with the diamine having a photosensitive group is selected from the compound (VIII-1) to the compound (VIII-6), the particularly preferred acid anhydride is the compound (VII-4) or the compound (VII-5). is there.

（これらの式におけるＲ^５の意味は前記の通りである） A fourth preferred example of the polyamic acid includes at least one acid anhydride having a photosensitive group represented by the above (IV-4) and the formula (VI-8), the formula (VII-4) and the formula (VII- 5) A polyamic acid obtained by reacting a mixture with at least one of the acid anhydrides represented by formula (VIII-7) and formula (VIII-8) with diamine. Preferred examples of the diamine are diamines selected from the compounds represented by the formulas (VII-1) to (VII-3) and (VIII-1) to (VIII-6).

(The meaning of R ⁵ in these formulas is as described above.)

  The fifth preferred examples of the polyamic acid include the above formulas (I-1) to (I-3), the formula (II-1) to the formula (II-3), the formula (III-1) and the formula (IV). -1) to formula (IV-3), formula (V-1) and formula (VI-1) to at least one diamine having a photosensitive group represented by formula (VI-7) and the above formula (2) A polyamic acid obtained by reacting a mixture of at least one selected from diamines represented by formula (4) with an acid anhydride. Preferred examples of the acid anhydride include the above formula (A-1), formula (A-2), formula (A-12), formula (A-14), formula (A-18), formula (A- 20) From the compounds represented by formula (A-21), formula (A-37), formula (VII-4), formula (VII-5), formula (VIII-7) and formula (VIII-8) The acid anhydride selected. Compound (VII-4) and compound (VII-5) are particularly preferable.

  The sixth preferred examples of the polyamic acid include the above formulas (I-1) to (I-3), formulas (II-1) to (II-3), formula (III-1), and formula (IV). -1) to formula (IV-3), formula (V-1) and formula (VI-1) to at least one diamine having a photosensitive group represented by formula (VI-7), the above formula (VII) -1) to formula (VII-3) and at least one of diamines represented by formula (VIII-1) to formula (VIII-6) and the diamines represented by the above formulas (2) to (4) A polyamic acid obtained by reacting at least one mixture selected from Preferred examples of the acid anhydride include the above formula (A-1), formula (A-2), formula (A-12), formula (A-14), formula (A-18), formula (A-20). ), Formula (A-21), Formula (A-37), Formula (VII-4), Formula (VII-5), Formula (VIII-7) and Formula (VIII-8) Acid anhydride.

（これらの式におけるＲ^４およびＲ^５の意味は前記の通りである。） A seventh preferred example of the polyamic acid is at least one of diamines represented by formulas (VII-1) to (VII-3) and tetra represented by formulas (VIII-7) and (VIII-8). Polyamic acid obtained by reacting at least one of carboxylic dianhydrides or at least one of diamines represented by formula (VIII-1) to formula (VIII-6) and formula (VII-4) and formula ( It is a polyamic acid obtained by reacting at least one of tetracarboxylic dianhydrides represented by VII-5).

(The meanings of R ⁴ and R ⁵ in these formulas are as described above.)

（Ｍｅはメチルを意味する。）

(Me means methyl)

  A preferred example of the aligning agent of the present invention is an aligning agent containing one polyamic acid selected from the above seven preferable polyamic acids or a polyimide obtained by a dehydration reaction thereof. May be two or more. Furthermore, if it is in the range which does not inhibit the effect of this invention, in addition to at least 1 of said 7 polyamic acid, the orientation agent of this invention contains general polyamic acid other than said example. Also good. That is, in the present invention, as long as the condition of forming a film having a liquid crystal temperature range between 100 ° C. and 300 ° C. is satisfied, in addition to the above polyamic acid, polyamic acid having no photosensitive group in the main chain or 100 ° C. To 300 ° C., polyamic acid that cannot form a film having a liquid crystal temperature range can be used in combination. When such a polyamic acid other than the above examples is used, the proportion thereof is less than 50% by weight, preferably less than 20% by weight, based on the total amount of the film-forming component in the alignment agent.

  The alignment agent of the present invention may further contain an organosilicon compound from the viewpoint of adjusting the adhesion of the alignment film to the glass substrate. Examples of organosilicon compounds are aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxy A silane coupling agent such as (cyclohexyl) ethyltrimethoxysilane, and a silicone oil such as dimethylpolysiloxane, polydimethylsiloxane, and polydiphenylsiloxane.

  The addition ratio of the organosilicon compound to the alignment agent is not particularly limited as long as the effect of the present invention is obtained. However, when a large amount of the organosilicon compound is added, liquid crystal alignment failure may occur when the alignment film is formed. Therefore, when the organosilicon compound is added, its concentration is preferably in the range of 0.01 to 5% by weight, particularly preferably 0.1 to 3%, based on the total amount of polymer components contained in the aligning agent. It is in the range of wt%.

  The aligning agent of the present invention may further contain a compound having two or more functional groups that react with the carboxylic acid residue of the polyamic acid, so-called cross-linking agent, from the viewpoint of preventing deterioration with time and deterioration due to the environment. . Examples of such a crosslinking agent include polyfunctional epoxies and isocyanate materials as described in Japanese Patent No. 3049699, Japanese Patent Application Laid-Open No. 2005-275360, Japanese Patent Application Laid-Open No. 10-212484, and the like.

  A crosslinking agent that reacts with itself to form a polymer having a network structure and improves the film strength of polyamic acid or polyimide can also be used for the same purpose as described above. Examples of such a crosslinking agent include polyfunctional vinyl ethers, maleimides, and bisallyl nadiimide derivatives as described in JP-A-10-310608, JP-A-2004-341030, and the like. A desirable ratio of these crosslinking agents is 0 to 50% by weight, more preferably 0 to 30% by weight, based on the total amount of the polymer components.

  The aligning agent of the present invention contains a solvent having the ability to dissolve the polyamic acid. Such solvents widely include solvents usually used in the production and use of polyamic acid or derivatives thereof, and can be appropriately selected according to the purpose of use. Examples of these solvents are as follows.

  Examples of aprotic polar organic solvents that are good solvents for polyamic acids include N-methyl-2-pyrrolidone (NMP), dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N, N- Examples include lactones such as dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide (DMF), N, N-diethylformamide, N, N-diethylacetamide (DMAc), and γ-butyrolactone (GBL).

  Examples of other solvents other than the above-mentioned solvents for the purpose of improving coatability include alkyl lactate, 3-methyl-3-methoxybutanol, tetralin, isophorone, ethylene glycol monobutyl ether (BCS), etc. Ethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether such as diethylene glycol monoethyl ether, ethylene glycol monoalkyl and phenyl acetate, triethylene glycol monoalkyl ether, propylene glycol monoalkyl ether such as propylene glycol monobutyl ether, diethyl malonate, etc. Dipropylene glycol monoalkyl ethers such as dialkyl malonate and dipropylene glycol monomethyl ether, and these glycol monoethers Ester compounds such as Le acids and the like. Among these, NMP, dimethylimidazolidinone, GBL, BCS, diethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether and the like can be particularly preferably used as the solvent.

  The alignment agent of the present invention may further contain various additives as desired. For example, when a further improvement in coatability is desired, a surfactant suitable for such purpose may be contained, and when a further improvement in antistatic property is required, an appropriate amount of an antistatic agent may be contained.

  The concentration of the polyamic acid in the alignment agent of the present invention is preferably 0.1 to 40% by weight. When this aligning agent is applied to the substrate, an operation of diluting the contained polyamic acid with a solvent in advance may be required to adjust the film thickness.

  The solid content concentration in the alignment agent of the present invention is not particularly limited, and an optimum value may be selected according to the following various coating methods. Usually, in order to suppress unevenness and pinholes at the time of application, the content is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the varnish weight.

  The alignment film of the present invention imparts anisotropy to the film obtained by applying the above aligning agent to the substrate by rubbing or light irradiation, and then heats the film to the liquid crystal temperature range to form the film anisotropy. Is obtained by increasing.

At this time, from the viewpoint of expressing sufficient orientation, it is preferably produced by the following procedure.
(1) The varnish is applied onto a substrate by a brush coating method, a dipping method, a spinner method, a spray method, a printing method, or the like.
(2) The film formed on the substrate is heated at 50 to 120 ° C., preferably 80 to 100 ° C., to evaporate the solvent.
(3) The film is irradiated with light to orient the polyamic acid in the film.
(4) The film in which the polyamic acid is oriented is heated at 150 to 300 ° C., preferably 180 to 250 ° C., and imidized.

  In addition, when a predetermined pretilt angle is to be expressed in a liquid crystal display element using an alignment film, a method of irradiating a substrate with linearly polarized light from an arbitrary angle when irradiating light, or a straight line from a direction perpendicular to the substrate It can be performed by combining polarized light irradiation and non-polarized light irradiation from an arbitrary angle.

  In the production of the alignment film of the present invention, linearly polarized light is used for the alignment of the polyamic acid. The polyamic acid main chain is oriented in a direction perpendicular to the polarization direction of the linearly polarized light by irradiation with the linearly polarized light. The linearly polarized light is not particularly limited as long as it is light capable of orienting the polyamic acid in the film. The alignment film of the present invention can be aligned by low energy light irradiation. Therefore, the irradiation amount of linearly polarized light in the photo-alignment treatment of the polyamic acid is preferably 0.5 to 10 J / cm 2. The wavelength of linearly polarized light is preferably 300 to 400 nm. Although the irradiation angle with respect to the film surface of linearly polarized light is not particularly limited, it is preferable from the viewpoint of shortening the alignment processing time that it is as perpendicular as possible to the film surface in order to develop a strong alignment regulating force for the liquid crystal.

  In the production of the alignment film of the present invention, the light applied to the film when it is desired to express the pretilt angle may be polarized light or non-polarized light. When it is desired to develop a pretilt angle, the amount of light applied to the film is preferably 0.5 to 10 J / cm2, and the wavelength is preferably 300 to 400 nm. When it is desired to express the pretilt angle, the irradiation angle of the light irradiated to the film with respect to the film surface is not particularly limited, but is preferably 30 to 60 degrees from the viewpoint of shortening the alignment processing time.

  The alignment film of the present invention is particularly characterized by having a large orientation anisotropy. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in JP-A-2005-275364. Further, as shown in the following examples, evaluation can also be made by a method using ellipsometry. When the alignment film of the present invention is used as an alignment film for a liquid crystal composition, a material having a larger film anisotropy is considered to have a large alignment regulating force for the liquid crystal composition.

  The alignment film of the present invention can be used for alignment control of an optical compensation material and all other liquid crystal materials in addition to the alignment use of a liquid crystal composition for a liquid crystal display. Further, since the alignment film of the present invention has large anisotropy, it can be used alone for an optical compensator application.

  The present invention is formed on a pair of substrates disposed opposite to each other, an electrode formed on one or both of the surfaces opposed to each of the pair of substrates, and a surface opposed to each of the pair of substrates. A liquid crystal display element having a liquid crystal alignment film formed and a liquid crystal layer formed between the pair of substrates, wherein the liquid crystal alignment film is the alignment film of the present invention.

  The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such electrodes include ITO and metal vapor deposition films. Further, the electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired shape that is patterned, for example. Examples of the desired shape of the electrode include a comb shape or a zigzag structure. The electrode may be formed on one of the pair of substrates, or may be formed on both substrates. The form of electrode formation varies depending on the type of liquid crystal display element. For example, in the case of an IPS liquid crystal display element, an electrode is disposed on one of the pair of substrates, and in the case of other liquid crystal display elements, the electrodes of the pair of substrates are arranged. Electrodes are arranged on both sides. The liquid crystal alignment film is formed on the substrate or electrode.

  The liquid crystal layer is formed in such a manner that the liquid crystal composition is sandwiched between the pair of substrates facing each other on which the liquid crystal alignment film is formed. In the formation of the liquid crystal layer, a spacer such as fine particles or a resin sheet that is interposed between the pair of substrates to form an appropriate interval can be used as necessary. The liquid crystal composition is not particularly limited, and a known liquid crystal composition can be used.

  The alignment film of the present invention can improve the characteristics of all known liquid crystal compositions when a liquid crystal display element is formed as a liquid crystal alignment film. In particular, it is highly effective in improving alignment defects of large screen displays that are difficult to rub. Such a large screen display is driven and controlled by TFTs. Liquid crystal compositions used for such TFT type liquid crystal display elements are described in Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Laid-Open No. 5-501735, and Japanese Patent Laid-Open No. 9-255556. Yes. Therefore, the alignment film of the present invention is preferably used in combination with the liquid crystal composition described therein.

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

  The liquid crystal display element of the present invention is excellent in electrical characteristics relating to the reliability of the liquid crystal display element. Such electrical characteristics include voltage holding ratio and ion density.

  The voltage holding ratio (VHR) is a ratio at which the voltage applied to the liquid crystal display element during the frame period is held in the liquid crystal display element, and indicates display characteristics of the liquid crystal display element. The liquid crystal display element of the present invention uses a rectangular wave of 5 V and a frequency of 30 Hz, has a voltage holding ratio measured at a temperature of 60 ° C. of 90.0% or more, and uses a rectangular wave of 5 V and a frequency of 0.3 Hz. From the viewpoint of preventing display defects, it is preferable that the voltage holding ratio measured at a temperature of 60 ° C. is 85.0% or more.

  The ion density is a transient current other than that caused by driving of the liquid crystal generated when a voltage is applied to the liquid crystal display element, and indicates the magnitude of the concentration of ionic impurities contained in the liquid crystal in the liquid crystal display element. The liquid crystal display element of the present invention preferably has an ion density of 500 pC or less from the viewpoint of preventing image sticking of the liquid crystal display element.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples. Pyromellitic anhydride (PMDA, compound (A-1)), 1,2,3,4-cyclobutanetetracarboxylic acid (CBTA, compound (A-14)), and compound (2-13) are commercially available compounds. Was purified by recrystallization and used in experiments. 1,8-diaminooctane (DAO, compound (VII-1-1)) was used by distilling a commercially available product. Compound (II-1) and compound (A-21) were synthesized according to Japanese Patent Publication No. 5-65530 and Japanese Patent Application Laid-Open No. 58-109479, respectively. The following compound (VII-2-1), compound (VII-2-2), and compound (VII-5-1) are disclosed in JP-A-11-160712 and Bulletin de la Societe Chimique de France, 9-10. , Pr. 2, 2195 (1975). Compound (VIII-5) and compound (VIII-6) were used in the experiment without purification of commercial products. Compound (VIII-8) was recrystallized from ethanol and used in the experiment. Compound (2-22) and Compound (3-5-1) are the same methods as those described in Journal of Polymer Science Part A: Polymer Chemistry, 30 (6), 1099 (1992), JP 2002-162630 A Was synthesized. Compound (A-21) was synthesized according to JP-A-58-109479. The polymer was prepared in a nitrogen stream.

  For the light irradiation, a 250 W high-pressure mercury lamp sold by Iuchi Seieido was used, and ultraviolet rays having a wavelength of about 300 to 380 nm were irradiated. Irradiation was performed in air at room temperature.

The evaluation method of the liquid crystal display element used in the examples is shown below.
<Measurement of retardation and thickness of alignment film>
It was determined using a spectroscopic ellipsometer M-2000U (manufactured by JAWoollam Co. Inc.). In this example, the retardation value of the film increases in proportion to the degree of orientation of the polymer main chain. That is, those having a large retardation value have a large degree of orientation.
<Measurement of UV-Vis spectrum>
Using a UV-Vis spectrum measuring device (JASCO V-660), a glass substrate on which no alignment film was formed was measured as a reference.
<Voltage holding ratio>
It carried out by the method as described in "Mizushima et al., The 14th Liquid Crystal Discussion Meeting Proceedings p78 (1988)". The measurement was performed by applying a rectangular wave having a wave height of ± 4.5 V to the cell. The measurement was performed at 60 ° C. This value is an index indicating how much the applied voltage is retained after the frame period. If this value is 100%, it indicates that all charges are retained.
<Measurement of ion content in liquid crystal (ion density)>
According to the method described in Applied Physics, Vol. 65, No. 10, 1065 (1996), measurement was performed using a liquid crystal property measuring system 6254 type manufactured by Toyo Technica. Using a triangular wave with a frequency of 0.01 Hz, measurement was performed at a voltage range of ± 10 V and a temperature of 60 ° C. If the ion density is high, defects such as seizure due to ionic impurities are likely to occur. That is, the ion density is a physical property value that is an index for predicting the occurrence of image sticking.
<Viscosity>
It measured using the rotational viscometer (TV-22L, the Toki Sangyo company make).
<Weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the polyamic acid in the liquid crystal aligning agent was determined by using gel permeation chromatography (GPC), 0.6 wt% phosphoric acid-containing DMF as an eluent, a column temperature of 50 ° C., and polystyrene. Was measured as a standard solution. As the column, Shodex GF-7M HQ (manufactured by Showa Denko) was used.
<Confirmation of polymer liquid crystal>
The thin film (film thickness: about 70 nm) formed on the substrate was baked at 230 ° C. for 10 minutes, and then observed with a polarizing microscope. The temperature rising rate was 3 ° C./min.
<Glass transition temperature>
Measurement was performed using a differential scanning calorimeter (DSC). The heating rate was 8 ° C./min.
<Check the black level of the cell>
The prepared cell was observed with a polarizing microscope and judged according to the following table.

（VII−２−２）の化合物と同様に合成した。融点；９８．０−９９．２℃。 [Synthesis Example 1]
Synthesis of compound (VII-2-3)

The compound was synthesized in the same manner as the compound (VII-2-2). Melting point: 98.0-99.2 ° C.

４−ブロモフタル酸ジエチルエステル（５０ｇ、１６６ｍｍｏｌ）、１，７−オクタジイン（８．７ｇ、８２ｍｍｏｌ）、ジクロロトリフェニルフォスフィンパラジウム（ＩＩ）（２９０ｍｇ、０．４１ｍｍｏｌ）、およびヨウ化銅（１５８ｍｍｏｌ、０．８３ｍｍｏｌ）の混合物を、窒素気流下、トリエチルアミン（２００ｍｌ）中、４時間還流した。反応終了後、トルエン（５００ｍｌ）および純水（５００ｍｌ）を加え、抽出を行った。有機層を純水（３００ｍｌ）で一回洗浄したのち、無水硫酸マグネシウムで乾燥した。ろ過および溶媒を減圧留去し、目的物である１，４−ビス（３，４−ジカルボキシフェニル）エチニルブタン テトラエチルエステルを得た。収量４２ｇ、収率９５％。この化合物は精製せずにそのまま次の反応に用いた。 [Synthesis Example 2]
Synthesis of compound (VII-4-1)

4-Bromophthalic acid diethyl ester (50 g, 166 mmol), 1,7-octadiyne (8.7 g, 82 mmol), dichlorotriphenylphosphine palladium (II) (290 mg, 0.41 mmol), and copper iodide (158 mmol, 0 .83 mmol) was refluxed in triethylamine (200 ml) under nitrogen flow for 4 hours. After completion of the reaction, toluene (500 ml) and pure water (500 ml) were added for extraction. The organic layer was washed once with pure water (300 ml) and then dried over anhydrous magnesium sulfate. Filtration and the solvent were distilled off under reduced pressure to obtain 1,4-bis (3,4-dicarboxyphenyl) ethynylbutane tetraethyl ester as a target product. Yield 42 g, 95% yield. This compound was used in the next reaction without purification.

  5 wt% Pd / C (2.1 g) was added to 1,4-bis (3,4-dicarboxyphenyl) ethynylbutane tetraethyl ester (42 g, 77 mmol) and hydrogen in a toluene / ethanol mixed solvent (300 ml / 300 ml). The hydrogenation reaction was performed at a pressure of 720 MPa. After completion of the reaction, the catalyst was filtered off and the solvent was distilled off under reduced pressure. The residue was purified by column chromatography (silica gel / toluene: ethyl acetate = 10: 1 v / v) to obtain the desired 1,8-bis (3,4-dicarboxyphenyl) octane tetraethyl ester. Yield 43 g, yield 100%.

  1,8-bis (3,4-dicarboxyphenyl) octane tetraethyl ester (43 g, 77 mmol) was dissolved in ethanol (250 ml), 5.7% aqueous sodium hydroxide solution (250 ml) was added, and the mixture was refluxed for 2 hours. After the reaction, the solvent was distilled off under reduced pressure, and concentrated hydrochloric acid was added until the pH reached 1. After the produced precipitate was filtered, the precipitate was washed with pure water (200 ml) three times. The obtained crystals were dried under reduced pressure to obtain 1,8-bis (3,4-dicarboxyphenyl) octane. Yield 31 g, yield 90%.

Acetic anhydride (50 ml) was added to 1,8-bis (3,4-dicarboxyphenyl) octane (10 g, 23 mmol) and refluxed for 2 hours. After acetic anhydride was distilled off under reduced pressure, cyclohexane (50 ml) was added to the residue, and the resulting precipitate was filtered. The obtained crystal was dried under reduced pressure to obtain Compound (VII-4-1). Yield 9.2 g, 97% yield. Melting point: 109.7-11.
¹ H NMR (500Hz, CDCl3); δ (ppm) 7.92 (d, 4H, J = 7.80Hz), 7.70 (d, 4H, J = 8.1Hz), 2.82 (t, 4H, J = 7.65Hz), 1.3 -1.7 (m, 12H).

[Synthesis Example 3]
<Preparation of polyamic acid varnish A>
Compound (II-1) (0.1818 g, 0.7827 mmol) was dissolved in N-methyl-2-pyrrolidone (NMP, 3.0 g) to give compound (VII-4-1) (0.3182 g, 0.7829 mmol). ) Was added while keeping the temperature below room temperature. After stirring overnight, varnish A was prepared by adding NMP (3.5 g) and ethylene glycol monobutyl ether (BSC, 3.0 g). The viscosity of varnish A was 49.8 mPa · s. The weight average molecular weight of the polyamic acid of this varnish was 74,000, and the liquid crystal layer was expressed in the range of 200-300 ° C.

[Synthesis Examples 4 to 14]
<Preparation of polyamic acid varnishes B to L>
Polyamic acid varnishes B to L were prepared in the same manner as in Synthesis Example 1 with the raw material compositions shown in Table 1, and the physical properties were measured in the same manner as in Synthesis Example 1. Figures in parentheses indicate mol%. In addition, when all these varnishes confirmed the liquid crystal phase according to said measuring method, the liquid crystal phase existed in the range of 170-250 degreeC.

<Table 1>

[Example 1]
1.0 g of varnish A was weighed into a sample bottle and NMP / BC = 1/1 (weight ratio) was added to make 1.67 g. The polyamic acid solution of about 3% by weight was dropped on a transparent glass substrate and applied by a spinner method (2,000 rpm, 15 seconds). After coating, the substrate was heated at 80 ° C. for 3 minutes to evaporate the solvent, and then irradiated with linearly polarized light through the polarizing plate (at 365 nm, energy of about 1.3 J / cm 2). The substrate after light irradiation was heat-treated in an oven at 210 ° C. for 15 minutes to obtain an alignment film A having a thickness of about 100 nm. When the retardation of this alignment film A was measured, it was 12.9 nm.

[Examples 2 to 6]
Using the varnish shown in Table 2, alignment films B to F were obtained in the same manner as in Example 1. The result of measuring the retardation is shown together with the result of Example 1.
<Table 2>

[Example 7]
An alignment film M was produced according to the same method as in Example 1 except that varnish M in which 0.5 g of varnish A and varnish B was mixed was used instead of varnish A. The retardation value of the alignment film M was 30.5 nm.

[Comparative Example 1]
Compound (II-1) (2.6432 g, 11.38 mmol) was dissolved in NMP (35.0 g), and PMDA (1.2410 g, 5.690 mmol) and CBTA (1.1158 g, 5.690 mmol) were added at room temperature or lower. Added while keeping. After stirring at room temperature overnight, NMP (35 g) and BSC (25 g) were added. The viscosity of this product was 120 mPa · s. This solution was stirred at 60 ° C. for about 4 hours to obtain varnish N having a viscosity of 28.0 mPa · s. The weight average molecular weight of the polyamic acid of this varnish was 37,000, and the glass transition temperature (Tg) exceeded 300 ° C.

  Using the varnish N, the alignment film N was obtained in the same manner as in Example 1, and the retardation thereof was measured. The result was 0.4 nm.

[Comparative Example 2]
A varnish P having a viscosity of 34.0 mPa · s was obtained in the same manner as in Comparative Example 1 except that the compound (VI-1) was used instead of the compound (II-1). The weight average molecular weight of the polyamic acid of this varnish was 54,000, and the glass transition temperature (Tg) exceeded 300 ° C.

  Using the varnish P, the alignment film P was obtained in the same manner as in Example 1, and the retardation thereof was measured. The result was 0.8 nm.

  Comparing the examples with Comparative Examples 1 and 2, the alignment film of the present invention obtained using the polymer of the present invention is very low in the amount of irradiation energy compared to the alignment film manufactured from a polymer having no liquid crystallinity. It can be seen that it has a large retardation value.

[Example 8]
An alignment film A having a thickness of about 100 nm was obtained in the same manner as in Example 1 except that the glass substrate was replaced with a transparent glass substrate provided with an ITO electrode on one side. The two substrates on which the alignment films are formed on the ITO electrode are opposed to each other so that the polarization directions of the linearly polarized light irradiated to the respective alignment films are parallel to each other, and the surfaces on which the alignment films are formed are opposed to each other. Further, a gap for injecting the liquid crystal composition was formed between the opposing alignment films and bonded together to assemble a liquid crystal cell A (liquid crystal display element) having a cell thickness of 7 μm. Then, a liquid crystal composition A shown below was injected into these cells.

<Liquid crystal composition A>

When this liquid crystal cell A was visually observed, no so-called flow alignment in which the liquid crystals were aligned along the direction in which the liquid crystals flowed was not observed at all. When the polarizing microscope was set in a crossed Nicol state and the liquid crystal cell A was rotated, clear bright and dark states were observed. The pretilt angle of the liquid crystal cell A was 0.0 °. VHR (voltage holding ratio) and ion density were 99.0% (30 Hz), 85.0% (0.3 Hz) and 120 pC.
Further, when the black level of the liquid crystal cell A was observed, a small crushing unevenness was observed in all the observed areas, but the black level was satisfactory.

[Example 9]
A liquid crystal cell B was produced in the same manner as in Example 8 except that the varnish used was replaced with varnish B. The pretilt angle of the liquid crystal cell B was 0.0 °. VHR (voltage holding ratio) and ion density were 92.2% (30 Hz), 76.3% (0.3 Hz) and 340 pC.
Further, when the black level of the liquid crystal cell B was observed, no crushing unevenness was found at all in the observed region, and the black level was very good.

[Example 10]
A liquid crystal cell F was produced in the same manner as in Example 8 except that the varnish used was replaced with the varnish F. The pretilt angle of the liquid crystal cell F was 0.0 °. VHR (voltage holding ratio) and ion density were 99.2% (30 Hz), 85.3% (0.3 Hz), and 80 pC.
When the black level of the liquid crystal cell F was observed, the crushing unevenness was not observed at all in the observed region, and the black level was very good.

[Example 11]
A liquid crystal cell L was produced in the same manner as in Example 8 except that the varnish used was replaced with the varnish L. These liquid crystal cells L had a pretilt angle of 0.0 °. VHR (voltage holding ratio) and ion density were 99.4% (30 Hz), 88.2% (0.3 Hz), and 35 pC.
Further, when the black level of the liquid crystal cell L was observed, no crushing unevenness was observed at all in the observed region, and the black level was very good.

[Example 12]
A liquid crystal cell M was produced in the same manner as in Example 8 except that the varnish used was replaced with the varnish M. These liquid crystal cells M had a pretilt angle of 0.1 °. VHR (voltage holding ratio) and ion density were 99.0% (30 Hz), 82.1% (0.3 Hz), and 120 pC.
Further, when the black level of the liquid crystal cell M was observed, no crushing unevenness was found at all in the observed region, and the black level was very good.

[Comparative Example 3]
A liquid crystal cell N was produced in the same manner as in Example 8 except that the varnish used was replaced with varnish N. The pretilt angle of the liquid crystal cell N was 0.1 °. VHR (voltage holding ratio) and ion density were 99.1% (30 Hz), 76.0% (0.3 Hz), and 300 pC.
Further, when the black level of the liquid crystal cell N was observed, large crushing unevenness was observed in all the observed regions, and the black level was much worse than that of the liquid crystal display element using the alignment film of the present invention.

[Comparative Example 4]
A liquid crystal cell P was produced in the same manner as in Example 8 except that the varnish used was replaced with the varnish P. The pretilt angle of the liquid crystal cell P was 0.0 °. VHR (voltage holding ratio) and ion density were 92.4% (30 Hz), 85.3% (0.3 Hz) and 110 pC.
Further, when the black level of the liquid crystal cell P was observed, large crushing unevenness was observed in all the observed regions, and the black level was worse than that of the liquid crystal display element using the alignment film of the present invention.

[Example 13]
A transparent glass substrate provided with an ITO electrode on one side was spin-coated with varnish A in the same manner as in Example 1, and then the substrate was heated at 80 ° C. for 3 minutes to evaporate the solvent and then 210 ° C. in an oven. Baked for 15 minutes. The obtained polyimide film having a film thickness of about 100 nm was rubbed (indentation: 0.3 mm, stage feed speed: 60 m / s, rotation speed: 1000 rpm, rubbing cloth: YA-18-R (rayon)). Thereafter, the alignment film was ultrasonically cleaned in ultrapure water for 5 minutes and then dried in an oven at 200 ° C. for 15 minutes.
Two substrates having these alignment films formed on ITO electrodes are opposed to each other so that the rubbing directions of the respective alignment films are antiparallel to each other, and the surfaces on which the alignment films are formed are opposed to each other. A gap for injecting the liquid crystal composition was formed between and bonded together to assemble a liquid crystal cell Ar having a cell thickness of 7 μm. Then, the liquid crystal composition A was injected into these cells.

  The pretilt angle of the liquid crystal cell Ar was 0.3 °, and the VHR (voltage holding ratio) and ion density were 98.7% (30 Hz), 80.2% (0.3 Hz) and 230 pC. Further, when the black level of the liquid crystal cell Ar was observed, scratches due to rubbing were not observed at all in the observed region, and the black level was further excellent.

[Example 14]
A liquid crystal cell Jr having a cell thickness of 7 μm was assembled in the same manner as in Example 13 except that varnish J was used instead of varnish A. The pretilt angle of this liquid crystal cell Jr was 0.5 degree, and VHR (voltage holding ratio) and ion density were 99.1% (30 Hz), 87.5% (0.3 Hz) and 78 pC.
Further, when the black level of the liquid crystal cell Jr was observed, no scratches due to rubbing were observed at all in the observed area, and the black level was very good.

  Thus, when the alignment film of the present invention is applied to an alignment film for a liquid crystal display element, the black level can be greatly improved. In addition, it can be seen that it has sufficient electrical characteristics to withstand practical use.

Claims (18)

A composition containing at least one polymer selected from a polyamic acid having a photosensitive group in the main chain and a polyimide obtained by a dehydration reaction of the polyamic acid, wherein the polymer has 6 carbon atoms in the structural unit of the main chain. The proportion of the polymer having an alkylene bond of ˜20 and based on the total amount of film-forming components contained in the composition is 50 to 100% by weight, and the composition is formed into a film at 100 to 300 ° C. A liquid crystal aligning agent capable of forming a film having a liquid crystal temperature range between ° C. Photosensitive group is at least one of the groups represented by the formula (I) ~ formula (VI), the liquid crystal aligning agent of claim 1.

(Here, R ¹ , R ² and R ³ are independently an aromatic divalent group.) The polyamic acid having a photosensitive group in the main chain is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III-1), formula (IV-1) ) To Formula (IV-3), Formula (V-1), and Formula (VI-1) to Formula (VI-7) are reacted with at least one diamine having a photosensitive group and tetracarboxylic dianhydride. a polyamic acid obtained by the liquid crystal alignment agent of claim 1.

A polyamic acid obtained by reacting a diamine with at least one of tetracarboxylic dianhydrides having a photosensitive group represented by formulas (IV-4) and (VI-8), wherein the polyamic acid having a photosensitive group in the main chain it is an acid, the liquid crystal aligning agent of claim 1.

Expression of the main chain is a polyamic acid having a photosensitive group claim 3 (I-1) ~ formula (I-3), formula (II-1) ~ formula (II-3), formula (III-1) At least one diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7); Obtained by reacting a mixture of at least one of the diamines represented by formula (VII-1) to formula (VII-3) and formula (VIII-1) to formula (VIII-6) with tetracarboxylic dianhydride a polyamic acid, a liquid crystal aligning agent of claim 1.

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; R ⁵ is optional —CH ₂ — is —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) _2. Osyl (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be replaced; and Me is methyl.) The polyamic acid having a photosensitive group in the main chain is at least one tetracarboxylic dianhydride having a photosensitive group represented by the formula (IV-4) and the formula (VI-8) according to claim 4 and the formula (VII -4), polyamics obtained by reacting a mixture with at least one of tetracarboxylic dianhydrides represented by formula (VII-5), formula (VIII-7) and formula (VIII-8) with diamine it is an acid, the liquid crystal aligning agent of claim 1.

(Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replacement And alkylene having 6 to 20 carbon atoms.) Expression of the main chain is a polyamic acid having a photosensitive group claim 3 (I-1) ~ formula (I-3), formula (II-1) ~ formula (II-3), formula (III-1) At least one diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7); 2) to (at least one of the mixture is selected from diamines represented by 4) a polyamic acid obtained by reacting a tetracarboxylic dianhydride, a liquid crystal aligning agent of claim 1.

(Where A ¹ , A ² , A ³ and A ⁴ are independently cyclohexylene or phenylene; X ³ and X ⁴ are independently a single bond, alkylene having 1 to 5 carbon atoms or —O— X ⁵ and X ⁶ are each independently a single bond, —CH ₂ —, —CH ₂ CH ₂ —, —O— or —S—; Y ¹ is —CH ₂ —, —C (R ¹¹ ) (R ¹² ) —, —CO— or —SO ₂ —, wherein R ¹¹ and R ¹² are independently hydrogen, alkyl having 1 to 12 carbons, or fluorinated alkyl having 1 to 12 carbons; m1, m2, m3, m4 and n independently represent 0 or 1. In the above cyclohexylene and phenylene, any hydrogen may be replaced by alkyl or benzyl having 1 to 4 carbon atoms. The bonding position of the substituent of It. ^However, when all of A ^1, A 2, ^{A 3} and ^{A 4} is ^{1,4-phenylene, X 3, X 4, X} 5 and ^{X 6} are both not a single bond.)

(Where X ¹ and X ² are a single bond, —O—, —COO—, —OCO—, —NH—, —CONH—, or alkylene having 1 to 12 carbon atoms; G ¹ and G ² are A single bond or a divalent group containing 1 to 3 rings selected from an aromatic ring having 6 to 12 carbon atoms and an alicyclic ring having 3 to 12 carbon atoms; R ⁶ is hydrogen, fluorine,- CN, —OH, alkyl having 1 to 30 carbons, fluorinated alkyl having 1 to 30 carbons or alkoxy having 1 to 30 carbons; and all of X ¹ , G ¹ , X ² and G ² are simple When it is a bond, R ⁶ is alkyl having 3 to 30 carbons, fluorinated alkyl having 3 to 30 carbons or alkoxy having 3 to 30 carbons, and G ² is a single bond and X ² is a single bond. If not a rather alkylene, ^{R 6} is hydrogen or number 3-30 carbon Is alkyl, when ^{G 1} and ^{G 2} are both single ^bonds, the total number of carbon atoms of X 1, ^{X 2} and ^{R 6} is 3 or more.)

(Where R ⁷ is hydrogen or alkyl having 1 to 12 carbons; ring B is 1,4-phenylene in which any hydrogen may be replaced by alkyl having 1 to 4 carbons, or any hydrogen is 1,4-cyclohexylene optionally substituted by alkyl having 1 to 4 carbons; X ⁰ is a single bond or alkylene having 1 to 5 carbons, and s is an integer of 0 to 3; When s is 2 or 3, the plurality of rings B may all be the same ring, may be composed of at least two different rings, and the plurality of X ⁰ may all be the same group, and at least May be composed of two different groups; Z ¹ and Z ² are independently a single bond, —CH ₂ —, —CH ₂ CH ₂ — or —O—, and t 1 and t 2 are independently 0 to 0 An integer of 3; when t1 is 2 or 3 All of the plurality of Z ¹ may be the same group, may be composed of at least two different groups; when t2 is 2 or 3, all of the plurality of Z ² may be the same group, at least It may be composed of two different groups.) Expression of the main chain is a polyamic acid having a photosensitive group claim 3 (I-1) ~ formula (I-3), formula (II-1) ~ formula (II-3), formula (III-1) At least one diamine having a photosensitive group represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7), At least one of the diamines represented by the formula (VII-1) to the formula (VII-3) and the formula (VIII-1) to the formula (VIII-6) according to the item 6, and the formula ( 2) to (at least one mixture selected from diamines represented by 4) a polyamic acid obtained by reacting a tetracarboxylic dianhydride, a liquid crystal aligning agent of claim 1. Tetracarboxylic dianhydride has formula (A-1), formula (A-2), formula (A-12), formula (A-14), formula (A-18), formula (A-20), formula Tetracarboxylic dianhydrides represented by (A-21), formula (A-37), formula (VII-4), formula (VII-5), formula (VIII-7) and formula (VIII-8) at least one of the liquid crystal alignment agent according to any one of claims 3, 5, 7 and 8.

(Here, ^{R 5} is arbitrary -CH ₂ - _{-O -, - NH -, -} N (CH 3) -, - Si (CH 3) 2 OSi (CH 3) 2 - or -COO- in replacement And alkylene having 6 to 20 carbon atoms.) The liquid crystal according to claim 4 or 6 , wherein the diamine is at least one of diamines represented by formula (VII-1) to formula (VII-3) and formula (VIII-1) to formula (VIII-6). Alignment agent.

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; R ⁵ is optional —CH ₂ — is —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) _2. Osyl (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be replaced; and Me is methyl.) A composition comprising at least one polymer selected from a polyamic acid and a polyimide obtained by a dehydration reaction of the polyamic acid, wherein the polymer has an alkylene bond having 6 to 20 carbon atoms in the structural unit of the main chain. The ratio of the polymer based on the total amount of the film-forming components contained in the composition is 50 to 100% by weight, and the liquid crystal temperature range is between 100 ° C. and 300 ° C. by forming the composition. Anisotropy is imparted to the film obtained by applying a liquid crystal aligning agent capable of forming a film having a surface to the substrate by rubbing or light irradiation, and then heated to the liquid crystal temperature range of the film to increase the film anisotropy. Liquid crystal alignment film obtained by increasing. Anisotropy of the film by applying anisotropy to the film obtained by applying the liquid crystal aligning agent according to any one of claims 1 to 10 to a substrate by light irradiation, and then heating to a liquid crystal temperature range of the film Liquid crystal alignment film obtained by increasing the property. A composition comprising at least one polymer selected from a polyamic acid and a polyimide obtained by a dehydration reaction of the polyamic acid, wherein the polymer has an alkylene bond having 6 to 20 carbon atoms in the structural unit of the main chain. The ratio of the polymer based on the total amount of the film-forming components contained in the composition is 50 to 100% by weight, and the liquid crystal temperature range is between 100 ° C. and 300 ° C. by forming the composition. By applying rubbing anisotropy to a film obtained by applying a liquid crystal aligning agent capable of forming a film having a film to a substrate, and then heating to the liquid crystal temperature range of the film to increase the film anisotropy A liquid crystal alignment film obtained ;
The polyamic acid comprises at least one of diamines represented by formulas (VII-1) to (VII-3) and tetracarboxylic dianhydrides represented by formulas (VIII-7) and (VIII-8). A polyamic acid obtained by reacting at least one or at least one diamine represented by formula (VIII-1) to formula (VIII-6) and a formula (VII-4) or formula (VII-5) Obtained by reacting at least one of the tetracarboxylic dianhydrides prepared.

(Where R ⁴ is alkylene having 6 to 20 carbon atoms; and R ⁵ is any —CH ₂ — being —O—, —NH—, —N (CH ₃ ) —, —Si (CH ₃ ) ₂ OSi (CH ₃ ) ₂ — or —COO— is an alkylene having 6 to 20 carbon atoms which may be substituted.

(Where Me is methyl.) The liquid crystal display device having a liquid crystal alignment film according to any one of claims 11 to 13. Polyamic acid containing a structural unit represented by the formula (IX) and having a liquid crystal temperature range at 100 to 300 ° C. or a precursor thereof, polyamic acid:

Here, R ⁵ is alkylene having 6 to 20 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) one of the remaining diamine represented by - formula (VI-7) It is a group.

Polyamic acid containing a structural unit represented by the formula (X) and having a liquid crystal temperature range at 100 to 300 ° C. or a precursor thereof, polyamic acid:

Here, R ⁵ is alkylene having 6 to 20 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) one of the remaining diamine represented by - formula (VI-7) It is a group.

Polyamic acid, which is a polyimide or a precursor thereof, containing a structural unit represented by formula (IX) and a structural unit represented by formula (XI) and having a liquid crystal temperature range of 100 to 300 ° C .:

Here, R ⁵ is alkylene having 6 to 12 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), a residue of any one of diamines represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) R ¹⁰ is a residue of any one of the diamines represented by formula (VIII-1) to formula (VIII-6).

(Where Me is methyl.) Polyamic acid, which is a polyimide or precursor thereof, containing a structural unit represented by formula (X) and a structural unit represented by formula (XII) and having a liquid crystal temperature range of 100 to 300 ° C .:

Here, R ⁵ is alkylene having 6 to 12 carbon atoms; R ⁹ is represented by formula (I-1) to formula (I-3), formula (II-1) to formula (II-3), formula (III) -1), a residue of any one of diamines represented by formula (IV-1) to formula (IV-3), formula (V-1) and formula (VI-1) to formula (VI-7) R ¹⁰ is a residue of any one of the diamines represented by formula (VIII-1) to formula (VIII-6).

(Where Me is methyl.)