KR20070093867A - Liquid crystal aligning film, liquid crystal aligning agent, and liquid crystal display device - Google Patents

Abstract

A liquid crystal aligning agent is provided to reduce problems resulting from dust or static electricity, control a pre-tilt angle of liquid crystals easily, and form liquid crystal aligning films. A liquid crystal aligning agent comprises: a polyamic acid which is a reaction product of tetracarboxylic dianhydride and diamines and includes azo groups in the main chain; and a solvent. The diamines contain a diamine having a side chain structure. The liquid crystal aligning film is obtained by imidizing the polyamic acid oriented in a predetermined direction by light irradiation. The liquid crystal aligning film has an alignment index(Delta) of a main chain in the obtained polyimide of 0.03-1.00. When a liquid crystal display device including the liquid crystal aligning film is formed, a pre-tilt angle of liquid crystal ranges from 2 to 90 degrees.

Description

Liquid crystal aligning film, a liquid crystal aligning agent, and a liquid crystal display element {LIQUID CRYSTAL ALIGNING FILM, LIQUID CRYSTAL ALIGNING AGENT, AND LIQUID CRYSTAL DISPLAY DEVICE}

[Technical Field]

The present invention, after performing the alignment treatment of the polyamine acid film by irradiating the light that controlled the polarization without performing a rubbing treatment, by imidization, to align the main chain of the polyimide in the polyimide film in a specific direction, the liquid crystal The liquid crystal aligning film which can express the pretilt angle of this invention, the liquid crystal aligning agent which can form this, and a liquid crystal display element which has the said liquid crystal aligning film.

[Background]

Liquid crystal display elements are used in various liquid crystal display devices such as monitors of notebook computers and desktop computers, view finders of video cameras, projection displays, and the like, and have recently been used in televisions. It is also used as an opto-electronics related element, such as an optical printer head, an optical Fourier conversion element, a light valve. As a conventional liquid crystal display element, a display element using a nematic liquid crystal is mainstream, and TN (the orientation direction of the liquid crystal on the one substrate side and the alignment direction of the liquid crystal on the other substrate side in the liquid crystal layer is twisted by 90 degrees). A twisted nematic liquid crystal display device, a super twisted nematic liquid crystal display device in which the orientation direction is twisted at an angle of 180 degrees or more, and a so-called TFT (thin-film-transistor) type liquid crystal display device using a thin film transistor are put to practical use. It is.

However, these liquid crystal display elements have a narrow viewing angle capable of properly recognizing an image, and when viewed in an inclined direction, the luminance and contrast may be lowered, and luminance inversion may occur in intermediate tones. In recent years, about this viewing angle problem, a TN type liquid crystal display element using an optical compensation film, a multi-domain vertical alignment (MVA) type liquid crystal display element using the technique of a vertical alignment and a projection structure, or IPS (in a transverse electric field system) It has been improved and put into practical use by techniques such as -plane switching) liquid crystal display elements (for example, see Patent Documents 1 to 3).

The development of the technology of a liquid crystal display element is achieved not only by the improvement of these drive system and element structure but also the improvement of the structural member used for a display element. Among the constituent members used for the display elements, in particular, the liquid crystal alignment film is one of important factors affecting the display quality of the liquid crystal display element, and the role of the liquid crystal alignment layer is becoming increasingly important as the quality of the display element is improved.

In such a liquid crystal alignment film, the arrangement of molecules of the liquid crystal must be uniformly controlled for uniform display characteristics of the liquid crystal display device, and thus the liquid crystal molecules on the substrate are uniformly oriented in one direction, and the inclination angle (pretilt angle) on the substrate surface is also uniform. ) Must be expressed. Thus, the liquid crystal aligning film which aligns the direction of the liquid crystal molecule on a board | substrate uniformly is an important but indispensable technique in the manufacturing process of a liquid crystal display element.

A liquid crystal aligning film is manufactured by a liquid crystal aligning agent. Currently, the liquid crystal aligning agent mainly used is the solution which melt | dissolved polyamine acid or soluble polyimide in the organic solvent. After apply | coating such a solution to a board | substrate, it forms into a film by means, such as a heating, and forms a polyimide-type liquid crystal aligning film. Although various liquid crystal aligning agents other than polyamic acid are examined, they are hardly put into practical use from the points of heat resistance, chemical resistance (liquid crystal resistance), coating property, liquid crystal alignability, electrical characteristics, optical characteristics, display characteristics, etc.

Industrially, the rubbing method which can simply process high speed of a large area is widely used as an orientation treatment method. The rubbing method is a process of rubbing the surface of a liquid crystal aligning film to one direction using cloth which modeled fibers, such as nylon, rayon, and polyester, and a liquid crystal molecule of the same orientation is obtained by this. However, problems such as dust generation and static electricity generation by the rubbing method have been pointed out.

Until now, the following two are proposed as an orientation mechanism of the liquid crystal in the liquid crystal aligning film which carried out the orientation process by the rubbing process.

(1) Surface shape effect due to micro grooves generated by rubbing treatment

(2) Intermolecular interaction of the liquid crystal aligning film uniaxially oriented by the rubbing process and the liquid crystal monolayer in contact with the liquid crystal aligning film

In recent years, the contribution of the surface shape effect of (1) is relatively small, and the contribution of the intermolecular interaction of (2) is dominant.

On the other hand, about the photo-alignment method which irradiates and orients light, many orientation mechanisms, such as a photolysis method, a photoisomerization method, a photodimerization method, and a photocrosslinking method, are proposed (for example, patent document 4). Reference). 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 of (2) acts as the alignment mechanism of the liquid crystal. Moreover, since the photo-alignment processing method is non-contact, in principle, generation | occurrence | production of dust and generation of static electricity are less than rubbing process.

Therefore, by using the liquid crystal aligning film which the uniaxial alignment property which carried out the orientation processing by the photo-alignment method especially is good, the molecular orientation state of the liquid crystal monolayer contacting a liquid crystal aligning film can be controlled, and performance improvement as a liquid crystal display element can be expected. On the other hand, in the photo-alignment method, there is room for examination of the control of a wide range of pretilt angles.

[Patent Document 1] Japanese Patent Application Publication No. 63-21907

[Patent Document 2] Japanese Patent Application Laid-Open No. 6-160878

[Patent Document 3] Japanese Patent Application Laid-Open No. 9-15650

[Patent Document 4] Japanese Patent Application Laid-Open No. 2005-275364

The subject of this invention relates to the optical alignment material which irradiates light, and performs an orientation process, The liquid crystal aligning agent and the said liquid crystal aligning agent which are easy to control the pretilt angle of a liquid crystal with few defects by dust and static electricity, and are easy to control. It is providing the liquid crystal display element which has the liquid crystal aligning film formed using this, and the said liquid crystal aligning film.

MEANS TO SOLVE THE PROBLEM The present inventors repeated examination in order to solve the said subject.

As a result, the liquid crystal aligning film which can give the orientation of a principal chain and the pretilt angle of a liquid crystal is obtained by irradiating the light which controlled polarization to the liquid crystal aligning film obtained from the liquid crystal aligning agent manufactured on the specific conditions, and carrying out the alignment process, The liquid crystal display element using the liquid crystal aligning film discovered that industrially stable pretilt angle was easy to control, and completed this invention.

This invention consists of the following structures.

[1] A liquid crystal aligning film formed by imidating a polyamine acid oriented in a predetermined direction by irradiation of light in a film of a polyamine acid containing an azo group in a main chain as a reaction product of tetracarboxylic dianhydride and diamine. At least one of the carboxylic dianhydride and the diamine has a side chain structure, and the orientation index Δ of the main chain of the polyimide in the liquid crystal alignment film obtained by the following formula (1) is in the range of 0.03 to 1.00, and includes a liquid crystal alignment film. The pretilt angle of the liquid crystal at the time of forming a display element is the range of 2-90 degrees: The liquid crystal aligning film characterized by the above-mentioned:

Δ = (| A∥-A⊥ |) / (A∥ + A⊥) × d / d '(1)

In the formula (1), A ′ is applied to the liquid crystal alignment film such that the polarized infrared light is perpendicular to the surface of the liquid crystal alignment film, and the polarization direction of the infrared light is parallel to the average alignment direction of the main chain of the polyimide. The integral absorbance by CNC stretching vibration of the imide ring near the wavenumber 1360cm ^-1 at the time of incidence is shown, and A 'shows the polarized infrared light perpendicular to the surface of the liquid crystal alignment film, and the average orientation of the main chain of the polyimide. The integral absorbance by the CNC stretching vibration of the imide ring near the wave number 1360 cm ^-1 when incident on the liquid crystal alignment film when the polarization direction of the infrared light is perpendicular to the direction is indicated, d denotes the film thickness of the liquid crystal alignment film, d 'Represents the actual film thickness of the photo-aligned region of the liquid crystal alignment film.

[2] The polyamine acid is a reaction product of tetracarboxylic dianhydride having no side chain structure, diamine having no side chain structure containing an azo group between two amino groups, and diamine having side chain structure, and having the side chain structure. Diamine is contained in the range of 7-90 mol% with respect to the total amount of the said diamine, The liquid crystal aligning film as described in [1] characterized by the above-mentioned.

[3] The liquid crystal aligning film according to [2], wherein the diamine having no side chain structure containing an azo group between the two amino groups is 4,4'-diaminoazobenzene.

[4] The liquid crystal aligning film according to [2], wherein the tetracarboxylic dianhydride is pyromellitic dianhydride.

[5] The liquid crystal aligning film according to [2], wherein the diamine having the side chain structure is a compound represented by the following general formula (I'-11):

Wherein R ²⁴ represents alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons.

[6] A reaction product of tetracarboxylic dianhydride and diamine, comprising a polyamine acid containing an azo group in a main chain, and a solvent, wherein the diamine contains a diamine having a side chain structure.

[7] The polyamine acid is a reaction product of tetracarboxylic dianhydride having no side chain structure, diamine having no side chain structure containing an azo group between two amino groups, and diamine having side chain structure, and having the side chain structure. Diamine is contained in the range of 7-90 mol% with respect to the total amount of the said diamine, The liquid crystal aligning agent as described in [6] characterized by the above-mentioned.

[8] A liquid crystal alignment film formed on a pair of substrates that are arranged to face each other, an electrode formed on one or both sides of a surface of each of the pair of substrates facing each other, and a surface of the pair of substrates that face each other And a liquid crystal display device having a liquid crystal layer formed between the pair of substrates, wherein one or both of the liquid crystal alignment films formed on the opposing surfaces of each of the pair of substrates are the items [1] to [5]. It is a liquid crystal aligning film which concerns on any one item, The liquid crystal display element characterized by the above-mentioned.

[9] A reaction product of tetracarboxylic dianhydride and diamine, comprising: irradiating a film of a polyamine acid containing an azo group in a main chain with light to orient the polyamine acid in the film; and imidating the polyamine acid oriented in the film. A method for producing a liquid crystal alignment film by imidating the polyamic acid, comprising a step of at least one of the tetracarboxylic dianhydride and the diamine is used to align the polyamine acid in the film The process to let

(A) When the light which changes the geometric isomer by the azo group from the anti isomer to the syn isomer is irradiated to the film and the polyamic acid in the film is viewed from the direction perpendicular to the surface of the film, in the predetermined direction, Orienting operation, and

Irradiating light from the oblique direction with respect to the surface of the film of the polyamine acid, and orienting the polyamine acid in the oblique direction with respect to the surface of the film; or

(B) When the light which changes the geometric isomer by an azo group from anti-isomer to new isomer is irradiated to the said film | membrane from the diagonal direction with respect to the surface of the said film, and the polyamic acid in a film | membrane is seen from the perpendicular direction with respect to the surface of the film | membrane, Orienting in a predetermined direction and at the same time in an oblique direction with respect to the surface of the film.

Best Mode for Carrying Out the Invention

The present invention can generate a pretilt angle of an arbitrary liquid crystal by irradiating a film of a liquid crystal aligning agent with specific light such as light that controls a polarization component and performing alignment treatment, and industrially stable by using such a liquid crystal aligning film. It is to realize a liquid crystal display element.

The liquid crystal aligning film in this invention is obtained by imidating the polyamine acid oriented in the predetermined direction by irradiating light with respect to a polyamine acid film.

The polyamic acid includes polyamic acid, which is a reaction product of tetracarboxylic dianhydride, and diamine, and a derivative thereof. The said polyamine acid is a form melt | dissolved in the solvent in the liquid crystal aligning agent mentioned later, and when it is set as the liquid crystal aligning film mentioned later, it is a component which can form the liquid crystal aligning film which has polyimide as a main component. As a derivative of the polyamine acid contained in the said polyamine acid in this invention, soluble polyimide, polyamine acid ester, polyamine acid amide, etc. are mentioned, for example. More specifically, 1) a polyimide in which all the amino groups of the polyamic acid are subjected to a dehydration ring closing reaction, 2) a partial polyimide that is partially dehydrated in a ring closure reaction, and 3) a part of tetracarboxylic acid anhydride is replaced with an organic dicarboxylic acid to react. The obtained polyamic acid-polyamide copolymer, and 4) polyamideimide which carried out the dehydration ring-closure reaction of part or all of the said polyamine acid-polyamide copolymer. In the said polyamine acid, it is preferable that the molar ratio of the said tetracarboxylic dianhydride and the said diamine is the same amount in order to acquire the molecular weight of a sufficiently large polyamine acid. However, when molecular weight is made small for a certain reason, this ratio can be changed in the range of 90: 100-100: 90, Preferably it is 95: 100-100: 95.

The polyamic acid includes an azo group in the main chain. The polyamine acid containing an azo group in the main chain has a main chain of the acid or diamine when the molecular structure except for the branched molecular structure is used as the main chain of the acid or diamine among the molecular structures connecting two acid anhydride groups or two amino groups. It is obtained by using tetracarboxylic dianhydride or diamine containing both an azo group, or both as a raw material. Although an azo group may be contained in both of tetracarboxylic dianhydride and diamine, it may be included only in one side. In addition, the polyamic acid preferably has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 10,000 or more in order to prevent deterioration with time of the alignment film, and is preferably 200,000 or less for ease of handling. Do.

At least either of the said tetracarboxylic dianhydride and the said diamine has a side chain structure. Tetracarboxylic dianhydride having a side chain structure has a molecular structure branched from the main chain of the acid. Diamine which has a side chain structure has the molecular structure branched from the main chain of this amine. Since at least one of the tetracarboxylic dianhydride and the diamine has a side chain structure, these tetracarboxylic dianhydrides and the diamine react to provide a polyamic acid (branched polyamine acid) having a side chain structure with respect to the polymer main chain. The liquid crystal aligning film formed from the liquid crystal aligning agent containing the polyamine acid which has a side chain structure can enlarge the pretilt angle in a liquid crystal display element.

As said side chain structure, group containing 3 or more carbon atoms is mentioned, for example. More specifically,

1) phenyl which may have a substituent, cyclohexylphenylene which may have a substituent, bis (cyclohexyl) phenylene which may have a substituent, or alkyl, alkenyl or alkynyl having 3 or more carbon atoms,

2) phenyloxy which may have substituents, cyclohexyloxy which may have substituents, bis (cyclohexyl) oxy which may have substituents, phenylcyclohexyloxy which may have substituents, having substituents Cyclohexylphenyloxy, or alkyloxy, alkenyloxy or alkynyloxy, having 3 or more carbon atoms,

3) phenylcarbonyl or alkylcarbonyl, alkenylcarbonyl or alkynylcarbonyl having 3 or more carbon atoms,

4) phenylcarbonyloxy or alkylcarbonyloxy, alkenylcarbonyloxy or alkynylcarbonyloxy having 3 or more carbon atoms,

5) Phenyloxycarbonyl which may have a substituent, cyclohexyloxycarbonyl which may have a substituent, bis (cyclohexyl) oxycarbonyl which may have a substituent, and bis (cyclo) which may have a substituent Hexyl) phenyloxy carbonyl, cyclohexylbis (phenyl) oxycarbonyl which may have a substituent, or alkyloxycarbonyl, alkenyloxycarbonyl or alkynyloxycarbonyl having 3 or more carbon atoms,

6) phenylaminocarbonyl or alkylaminocarbonyl, alkenylaminocarbonyl or alkynylaminocarbonyl having 3 or more carbon atoms,

7) cyclic alkylene having 3 or more carbon atoms,

8) cyclohexylalkylene which may have substituents, phenylalkylene which may have substituents, bis (cyclohexyl) alkylene which may have substituents, cyclohexylphenylalkylene which may have substituents, substituents Bis (cyclohexyl) phenylalkylene which may have a phenylalkyloxy, alkylphenyloxycarbonyl, or alkylbiphenyryloxycarbonyl which may have a substituent,

9) phenyl or cyclohexyl substituted by alkyl, fluorine substituted alkyl, or alkoxy, and

10) Alkyl and fluorine substituted alkyls in which two or more benzene rings or cyclohexane rings are bonded to each other or are bonded through -O-, -COO-, -OCO-, -CONH- or alkylene having 1 to 3 carbon atoms. Or a ring aggregate group substituted with alkoxy, but is not limited thereto.

Here, as a "substituent", alkyl, alkoxy, or alkoxyalkyl, etc. are mentioned.

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

In addition, in this specification, when it says "alkyl", "alkenyl", and "alkynyl", it may be linear or branched.

The tetracarboxylic dianhydride is any group of an aromatic system (including a heteroaromatic system) in which a dicarboxylic anhydride is directly bonded to an aromatic ring, and an aliphatic system (including a heterocyclic system) in which a dicarboxylic acid anhydride is not directly bonded to an aromatic ring. It may belong to. It is preferable that a polyamic acid is a structure which does not contain oxygen and sulfur, such as ester and ether bond which are a cause of the fall of the electrical property of a liquid crystal display element. Therefore, it is preferable that tetracarboxylic dianhydride also has a structure containing no oxygen or sulfur. However, even if it has such a structure, it will not be a problem at all if it is an amount within the range which does not adversely affect an electrical characteristic.

The specific example of the tetracarboxylic dianhydride which can be used by this invention is as follows.

In Formulas 1-1 to 1-38, Formula 1-1, Formula 1-2, Formula 1-7, Formula 1-13, Formula 1-17, Formula 1-18, Formula 1-19, Formula 1-20, The tetracarboxylic dianhydride represented by Formula 1-27, Formula 1-28, and Formula 1-29 is preferable. Tetracarboxylic dianhydride represented by Formula 1-1, Formula 1-7, Formula 1-13, Formula 1-17, Formula 1-19, Formula 1-20, and Formula 1-29 is more preferable.

The tetracarboxylic dianhydride is not limited to these, and of course, compounds having various molecular structures exist within the range in which the object of the present invention is achieved. In addition, these tetracarboxylic dianhydride can also be used individually or in combination of 2 or more types.

The diamine may include a diamine having an azo group as a structure for performing a photoisomerization reaction, a diamine having a side chain structure, and a diamine having no side chain structure. In this invention, it is possible to use these diamine together.

As the diamine having an azo group, one kind or two or more kinds of various diamines containing an azo group in the main chain of the amine can be used. Especially preferably, the diamine represented by following formula (3) is mentioned.

As diamine which has a side chain structure, 1 type, or 2 or more types of various diamine which has a side chain structure branched from the main chain of an amine can be used. As a diamine which has a side chain structure, in order to express all the characteristics, such as orientation stability and a pretilt angle, evenly, the diamine represented by general formula (I) is mentioned preferably.

In the said general formula (I), although two amino groups are couple | bonded with the phenyl ring carbon, Preferably, the binding position relationship of two amino groups is meta or para. In addition, two amino groups are respectively, "R ² -R ¹ -" is preferably bonded over time, the third and fifth, or second and 5 have a bonding site to the first place (位).

The formula (I) of the, R ¹ is a single bond, -O-, -COO-, -OCO-, -CO- , -CONH- or - (CH _{2) m} -, and where m is 1 to An integer of 6, R ² is alkyl having 1 to 20 carbon atoms when the positional relationship between the group having a steroid skeleton, the group represented by the following general formula (II), or the two amino groups bonded to the benzene ring is para; Or when the positional relationship is meta, alkyl or phenyl having 1 to 10 carbon atoms, and in the alkyl, any -CH ₂ -independently represents -CF _2- , -CHF-, -O-, and -CH = CH-. Or -C≡C- may be substituted (but oxygen is not continuous), -CH ₃ may be substituted with -CH ₂ F, -CHF ₂ or -CF ₃ , and the ring-forming carbon of the phenyl hydrogen which is bonded is, or may independently be substituted with _{-F, -CH 3, -OCH 3,} -OCH 2 F, -OCHF 2 or -OCF _3.

In formula (II), A ¹ and A ² are each independently a single bond, -O-, -COO-, -OCO-, -CONH-, -CH = CH- or alkylene having 1 to 20 carbon atoms. R ³ and R ⁴ are each, independently, -F or -CH ₃ , and ring S is 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl , Pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl, R ⁵ is -H,- F, alkyl having a carbon number of 1 to 20, 1 to 20 carbon atoms, fluorine substituted alkyl, having 1 to 20 carbon atoms alkoxy, -CN, and -OCH ₂ F, -OCHF ₂ or -OCF _3, a and b are independently 0, respectively When a or b is 2 to 4, an adjacent A ¹ or A ² is a different group, c, d and e each independently represent an integer of 0 to 3, and e is 2 or 3 When a plurality of rings S may be the same group or different groups, f and g each independently represent an integer of 0 to 2 High, and also c + d + e≥1.

As diamine represented by general formula (I), the diamine represented by Formula (I-1) (I-11)-is mentioned, for example.

In formula, R <^19> has preferable C3-C12 alkyl or C3-C12 alkoxy, and its C5-C12 alkyl or C2-C12 alkoxy is more preferable. R ²⁰ is preferably alkyl having 1 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms, and more preferably alkyl having 3 to 10 carbon atoms or alkoxy having 3 to 10 carbon atoms.

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

The diamine of this invention may contain the diamine represented by the said general formula (I) independently, and may contain 2 or more types.

Moreover, as long as the objective of this invention is not impaired, diamine which has a side chain structure other than the diamine represented by the said general formula (I) can be used. As diamine which has such a side chain structure, the diamine represented by Formula (I'-1)-(I'-20) is mentioned, for example.

In formulas (I'-1) to (I'-3), R ⁴ is preferably alkyl having 4 to 16 carbons, and more preferably alkyl having 6 to 16 carbons. In Formula (I′-4), R ²² is preferably alkyl having 6 to 20 carbon atoms, and more preferably alkyl having 8 to 20 carbon atoms.

In formula, R <^23> is C3-C12 alkyl or C3-C12 alkoxy is preferable, and C5-C12 alkyl or C5-C12 alkoxy is more preferable. R ²⁴ is preferably alkyl having 1 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms, and more preferably alkyl having 3 to 10 carbon atoms or alkoxy having 3 to 10 carbon atoms.

As diamine which does not have a side chain structure, 1 type, or 2 or more types of various diamines which do not contain the azo group in the main chain of the amine which does not have a side chain structure branched from the main chain of an amine can be used. As diamine which does not have a side chain structure, the following diamine is mentioned preferably.

For example, as a diamine which does not have a side chain structure, the diamine represented by Formula (III-1) and (III-2) is mentioned.

In addition, as a diamine which does not have a side chain structure, the diamine represented by Formula (IV-1) (IV-3)-is mentioned, for example.

In addition, as a diamine which does not have a side chain structure, the diamine represented by Formula (V-1)-(V-7) is mentioned, for example.

In addition, as a diamine which does not have a side chain structure, the diamine represented by Formula (VI-1) (VI-30)-is mentioned, for example.

In addition, as a diamine which does not have a side chain structure, the diamine represented by Formula (VII-1) (VII-6)-is mentioned, for example.

In addition, as a diamine which does not have a side chain structure, the diamine represented by Formula (VIII-1) (VIII-11)-is mentioned, for example.

Among these, as a diamine which does not have a side chain structure, Formula (V-1)-(V-7), Formula (VI-1)-(VI-12), Formula (VI-26), Formula ( And diamines represented by formulas (VII-27), (VII-1), (VII-2), (VII-6), and (VIII-1) to (VIII-5). The diamine represented by Formula (V-6), Formula (V-7), and Formula (VI-1)-(VI-12) is mentioned.

Moreover, the siloxane-based diamine which has a siloxane bond is mentioned as another diamine which can be used together with the said diamine which can be used by this invention. Although the said siloxane diamine is not specifically limited, What is represented by General formula (4) can be used conveniently in this invention.

In formula (4), R ₆ and R ₇ are independently alkyl or phenyl having 1 to 3 carbon atoms, and R ₈ is methylene, phenylene or alkyl substituted phenylene. x is an integer of 1-6, y is an integer of 1-10.

The diamine which can be used by this invention is not limited to these, It goes without saying that the compound of various molecular structures exists in addition to the range in which the objective of this invention is achieved. In addition, these diamine can be used individually or in combination of 2 or more types.

On the other hand, the diamines usable in the present invention are similar to the above-described tetracarboxylic dianhydrides, as well as aromatic systems (including heteroaromatic rings) in which an amino group is directly bonded to an aromatic ring, and aliphatic systems in which no amino group is directly bonded to an aromatic ring (double) It may belong to any group of the summoning system). Among these, the aromatic diamine having a ring structure and the aliphatic diamine having a ring structure are preferable because the alignment of the liquid crystal is maintained well. Moreover, the thing of the structure which does not contain oxygen and sulfur, such as ester and an ether bond which are a cause of the fall of the electrical property of a liquid crystal display element, is preferable. However, even if it has such a structure, it will not be a problem at all if it is an amount which does not adversely affect an electrical characteristic.

In addition to these tetracarboxylic dianhydrides and diamines, it is also possible to use together monoamines and / or monocarboxylic acid anhydrides which form the reaction terminals of polyamine acids. In order to improve adhesiveness to a substrate, an aminosilicon compound may be introduced.

Examples of the aminosilicone compounds include paraaminophenyltrimethoxysilane, paraaminophenyltriethoxysilane, metaaminophenyltrimethoxysilane, metaaminophenyltriethoxysilane, aminopropyltrimethoxysilane, and aminopropyltriethoxysilane. Etc. can be mentioned.

The ratio of the diamine which has a side chain structure, and the diamine which does not have a side chain structure can be arbitrarily selected according to an electrical property or a pretilt angle. It is preferable that it is the range of 7-90 mol%, and, as for the ratio of the diamine which has a side chain structure with respect to all diamine, it is more preferable that it is 10-70 mol%. If the ratio of the diamine which has the said side chain structure is 7 mol% or more, the pretilt angle of a favorable liquid crystal will be obtained, and if it is 90 mol% or less, the favorable orientation of a polyimide main chain can be obtained.

As for the liquid crystal aligning film in this invention, the orientation index (DELTA) of the principal chain of the polyimide in the liquid crystal aligning film calculated | required by following formula (1) is a range of 0.03-1.00.

The orientation (Δ) of the polyimide main chain can be evaluated by infrared absorption spectroscopy using polarized infrared light. This method detects the infrared dichroism which differs according to molecular orientation orientation, and evaluates molecular orientation, when the infrared absorption amount at the time of injecting two linearly polarized infrared lights orthogonal to a sample.

That is, a polarizer is disposed between a light source of an infrared spectrophotometer (preferably FT-IR) and a sample holder holding a sample having a polyimide liquid crystal alignment film, and the polyimide in a direction parallel to the surface of the liquid crystal alignment film. The infrared absorbance is measured by fixing the sample to the sample holder so that the average alignment direction of the main chain is parallel to the polarization direction of the polarizer, and at the same time, the infrared light is incident perpendicularly to the sample surface. Next, the polarizer is rotated 90 degrees while the sample is fixed to the sample holder, and the polarization direction of the infrared light passing through the polarizer is perpendicular to the average alignment direction of the main chain of the polyimide in the direction parallel to the surface of the liquid crystal alignment film. Infrared absorbance is measured. In the infrared absorbance thus obtained, Δ is calculated from the peak value or integral value of the absorption band resulting from molecular vibration polarized so as to be parallel to the molecular axis of the polyimide main chain.

In this method, a sample prepared on a substrate through which infrared light transmits, such as silicon or calcium fluoride (fluorite: CaF ₂ ), can be used.

In the present invention, the average alignment direction of the main chain of the polyimide means the direction in which the polyimide main chain is oriented on average when the liquid crystal alignment film is viewed from the direction perpendicular to the surface of the liquid crystal alignment film. That is, when the infrared absorption spectrum was measured by appropriately rotating the polarizer in the above-described measurement arrangement, the peak value or integral value of the absorption band resulting from molecular vibration polarized parallel to the molecular axis of the polyimide main chain indicates the maximum. The polarization direction by the polarizer at the time is the average orientation direction of the main chain of a polyimide.

Characteristic group frequencies of the polyimide in the present invention, the polyimide is a strong infrared absorption peak near 1360cm ^-1 (imide ring CNC stretching vibration), 1510cm ^-1 vicinity (CC stretching vibration of phenyl), and the vicinity of 1720cm ^-1 (C = O stretching vibration of an imide group) and the like. Although any infrared absorption peak may be used, 1360 cm ^-1 vicinity (CNC stretching vibration of an imide ring) with a relatively small change of the infrared absorption peak due to the polyimide composition according to the polyimide backbone, in which the direction of polarization caused by molecular vibration is along the polyimide backbone It is especially preferable to use. In addition, since an infrared dichroic ratio may differ according to the film thickness of a liquid crystal aligning film, it is preferable to evaluate the orientation of a polyimide main chain using the infrared dichroism which removed the influence of a film thickness.

As mentioned above, in this invention, the anisotropy in the direction parallel to the surface of the liquid crystal aligning film of the orientation of a liquid crystal aligning film is evaluated by the infrared two-color difference of 1360 cm <^-1> vicinity (CNC stretching vibration of an imide ring). On the other hand, the absorbance near 1360cm ^-1 in this invention shall represent the integral value (1330-1430cm- ¹ ) of the band which belongs to CNC stretching vibration of an imide ring. Moreover, in order to correct | amend the influence of a film thickness, the film thickness of a liquid crystal aligning film, and the absorption coefficient (alpha) in the wavelength of the light used for photo-alignment process are measured.

In this invention, the orientation of the polyimide main chain was evaluated by the orientation index (DELTA) of the liquid crystal aligning film after the orientation process represented by following formula (1).

Δ = (| A∥-A⊥ |) / (A∥ + A⊥) × d / d '(1)

In Formula (1), A ′ has been incident on the liquid crystal alignment film such that the polarized infrared light is perpendicular to the surface of the liquid crystal alignment film and parallel to the average alignment direction of the main chain of the polyimide. The integral absorbance by the CNC stretching vibration of the imide ring near the wave number 1360cm ^-1 at the time, and A 'represents the polarized infrared light perpendicular to the surface of the liquid crystal alignment film, and in the average orientation direction of the main chain of the polyimide. The integral absorbance due to the CNC stretching vibration of the imide ring near the wavenumber 1360 cm ^-1 when incident on the liquid crystal alignment film so as to be perpendicular to the polarization direction of the infrared light is shown. d represents the film thickness of a liquid crystal aligning film. d 'represents the substantial thickness of the photo-alignment process area | region of a liquid crystal aligning film.

Substantial thickness d 'of the area | region to which the photo-alignment process of a liquid crystal aligning film is carried out is calculated | required from following Formula (2).

d '= (1 / α) × γ (2)

In Formula (2), α is the absorption coefficient of the polyamine acid film which has not been photoaligned at the wavelength of light used for the photoalignment treatment. (gamma) is a correction coefficient of the thickness of the liquid crystal aligning film by imidization, _Comprising : The film thickness of the polyamine acid film before imidation is set to _dPAA, and it is calculated | required by d / d _PAA . When d is smaller than d ', d' = d. In addition, the film thickness of the polyamine acid film | membrane before imidation can be measured with an ellipsometer, a contact step meter, etc.

Absorption coefficient (alpha) is determined by measuring the transmission spectrum of the ultraviolet-visible region of the polyamic acid film | membrane of film thickness d _PAA measured with a step difference meter, an ellipsometer, etc. with an ultraviolet-visible spectrophotometer before photo-alignment process. When the transmittance of the substrate coated with the polyamic acid film at the wavelength of light used for the photo-alignment treatment is T _sample and the transmittance of only the substrate is T _sub , the absorption coefficient α is obtained by the following equation (3).

α = (1 / d _PAA ) × ln (T _sub / T _sample ) (3)

As for the liquid crystal aligning film in this invention, it is preferable that orientation index (DELTA) is in the range of 0.03 or more and 1.00 or less, (DELTA) is 0.10 or more and 0.95 or less, and it is more preferable that (DELTA) is 0.20 or more and 0.90 or less. When orientation index (DELTA) is 0.03 or more, the orientation of the principal chain of polyimide will be enough, and the stable liquid crystal display element will be obtained.

The pretilt angle of the liquid crystal at the time of forming a liquid crystal display element of the liquid crystal aligning film in this invention is a range of 2-90 degrees. It is preferable that the said pretilt angle is 3-90 degree | times.

The said pretilt angle uses the liquid crystal characteristic evaluation apparatus OMS-CA3 type | mold by the Chuo Seiki Co., Ltd., for example. 48, No. 5, p. It can measure by the crystal rotation method described in 1783-1792 (1977). Or the pretilt angle is Mol. Cryst. Liq. Cryst. It can be measured by the crystal rotation method described in 241 (1994) 147.

The film thickness of the liquid crystal aligning film in this invention is 5-500 nm normally from a viewpoint of the uniformity of the film thickness, and mechanical, optical, and electrical characteristics. It is preferable that it is 5-200 nm, and, as for the film thickness of a liquid crystal aligning film, it is more preferable that it is 5-150 nm.

The film thickness of a liquid crystal aligning film can be measured with an ellipsometer or a contact type stepmeter. Moreover, the film thickness of a liquid crystal aligning film can be adjusted with the density | concentration of a liquid crystal aligning agent, a viscosity, and the application | coating conditions of a liquid crystal aligning agent.

A liquid crystal aligning agent can be used for formation of the liquid crystal aligning film in this invention. This liquid crystal aligning agent is a varnish of the state which contained the azo group in the main chain mentioned above, and melt | dissolved the polyamine acid which has a side chain structure in the main chain in a solvent. The liquid crystal aligning film in this invention is formed by apply | coating this liquid crystal aligning agent on a board | substrate, and drying and aligning a solvent. The polyamine acid may be a copolymer such as a random copolymer, a block copolymer, or may contain a plurality of kinds of the polyamine acid.

The liquid crystal aligning agent which can be used by this invention contains the polyamine acid obtained by making diamine and tetracarboxylic dianhydride react, It is a liquid crystal aligning agent, At least one kind of diamine and tetracarboxylic dianhydride which has a side chain structure, And polyamine acid using at least one kind of diamine and tetracarboxylic dianhydride containing an azo group in its main chain. More preferably, the diamine contains a diamine containing a diamine having a side chain structure and a polyamine acid using a diamine having no side chain structure containing an azo group in its main chain. The tetracarboxylic dianhydride and diamine mentioned above can be used for the liquid crystal aligning agent in this invention.

The liquid crystal aligning agent in this invention contains 7-90 mol% of diamine which has a side chain structure with respect to the total amount of diamine, As mentioned above, the pretilt angle of the favorable liquid crystal in a liquid crystal display element, and a liquid crystal aligning film It is preferable in order to obtain the favorable orientation of the principal chain of the polyimide in.

Although the density | concentration of the polyamine acid in the liquid crystal aligning agent in this invention is not specifically limited, It is preferable that it is 0.1-40 mass%. When apply | coating the said liquid crystal aligning agent to a board | substrate, operation to dilute the polyamine acid contained with the solvent beforehand may be necessary for adjustment of a film thickness. The viscosity of a liquid crystal aligning agent becomes it preferable that the density | concentration of a polyamic acid is 40 mass% or less, and when it is necessary to dilute a liquid crystal aligning agent for adjustment of a film thickness, a solvent can be easily mixed with a liquid crystal aligning agent. It is preferable because it is.

In the case of application | coating methods, such as a spinner method and a printing method, in order to maintain favorable film thickness, it is usually made into 10 mass% or less in many cases. In other coating methods, for example, the dipping method and the inkjet method, the concentration can be further lowered. On the other hand, the film thickness of the liquid crystal aligning film obtained can be made easy as the density | concentration of polyamine acid is 0.1 mass% or more. Therefore, the density | concentration of polyamine acid is 0.1 mass% or more, Preferably it is 0.5-10 mass% in application | coating methods, such as a normal spinner method and the printing method. However, depending on the coating method of the said liquid crystal aligning agent, it can also be used by thinner density | concentration.

The solvent which can be used together with the said polyamine acid in the liquid crystal aligning agent in this invention is applicable without a restriction | limiting in particular if it is a solvent which has the ability to melt | dissolve polyamine acid. Such a solvent can contain the solvent normally used in manufacture or use of a polyamic acid, and can be suitably selected according to a use purpose. Illustrative of these solvents are as follows.

Examples of aprotic polar organic solvents that are good solvents for polyamine acids include N-methyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N, N-dimethylacetamide And lactones such as dimethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N-diethylacetamide, and γ-butyrolactone.

As a solvent other than the above-mentioned solvents, examples of solvents other than those for the purpose of improving applicability include ethylene such as alkyl lactate, 3-methyl-3-methoxybutanol, tetralin, isopron, and ethylene glycol monobutyl ether. Diethylene glycol monoalkyl ethers such as glycol monoalkyl ether and diethylene glycol monoethyl ether, propylene glycol monoalkyl ethers such as ethylene glycol monoalkyl and phenyl acetate, triethylene glycol monoalkyl ether, and propylene glycol monobutyl ether, and malonic acid di Ester compounds, such as dipropylene glycol monoalkyl ether, such as dialkyl malonic acid and dipropylene glycol monomethyl ether, such as ethyl, and these glycol monoethers, are mentioned.

Among these, as the solvent, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene It is particularly preferable to use glycol monomethyl ether or the like.

The liquid crystal aligning agent in this invention can contain various additives as needed. For example, an appropriate amount of a surfactant according to a related purpose may be used to improve applicability, an antistatic agent may be used to improve antistatic properties, and a silane coupling agent or a titanium-based coupling agent may be added in an appropriate amount to improve adhesion to a substrate. It may be.

A liquid crystal display element according to the present invention is a pair of substrates that are arranged to face each other, an electrode formed on one or both sides of the surface facing each of the pair of substrates, and the pair of substrates respectively. It has a liquid crystal aligning film formed in the surface which exists, and the liquid crystal layer formed between the said pair of board | substrates. The liquid crystal display element in this invention can be comprised similarly to the conventional liquid crystal display element except a liquid crystal aligning film. The liquid crystal aligning film in the above-mentioned this invention can be used for one or both of the liquid crystal aligning film formed in the opposing surface of each of said pair of board | substrates.

The board | substrate can use a suitable board | substrate according to the use. For the display, a transparent substrate such as glass is preferable for display, and a substrate that transmits infrared light such as silicon or calcium fluoride is preferable in order to confirm the alignment index Δ of the liquid crystal alignment film.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. As such an electrode, ITO, a vapor deposition film of a metal, etc. are mentioned, for example. Moreover, the electrode may be formed in the whole surface of one side of a board | substrate, for example, may be formed in the patterned predetermined shape. As said predetermined shape of an electrode, a comb-tooth type | mold or a zigzag structure etc. are mentioned, for example. An electrode may be formed in one board | substrate of a pair of board | substrates, and may be formed in both board | substrates. Formation of the electrode varies depending on the type of the liquid crystal display element. For example, in the case of the IPS type liquid crystal display element, the electrode is disposed in one direction of the pair of substrates, and in the case of the other liquid crystal display element, Electrodes are arranged on both sides of the pair of substrates. The liquid crystal alignment layer is formed on the substrate or the electrode.

The said liquid crystal layer is formed in the form which a liquid crystal composition is clamped by the said pair of board | substrate which the surface in which the liquid crystal aligning film was formed opposes. In formation of a liquid crystal layer, the spacer which forms moderate space | interval between said pair of board | substrates, such as microparticles | fine-particles and a resin sheet, can be used as needed.

There is no restriction | limiting in particular in the liquid crystal composition which can be used in the liquid crystal display element of this invention, Various liquid crystal compositions with positive dielectric anisotropy can be used. Examples of preferred liquid crystal compositions include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Application Laid-Open No. 5-501735, Japanese Patent Application Laid-Open No. 8-157826, Japanese Patent Application Laid-Open No. 8-231960, Japanese Patent Application Laid-Open No. 9-241644. (EP885272A1 specification), JP-A 9-302346 (EP806466A1 specification), JP-A 8-199168 (EP722998A1 specification), JP-A 9-235552, JP-A 9-255956, JP 9-241643 Japanese Patent Application Laid-Open Publication No. EP885271A1, Japanese Patent Application Laid-Open No. Hei 10-204016 (EP844229A1 Specification), Japanese Patent Application Laid-Open No. 10-204436, Japanese Patent Application Laid-Open No. 10-231482, Japanese Patent Application Laid-Open No. 2000-087040, Japanese Patent Application Laid-Open No. 2001-48822 It is.

Various liquid crystal compositions with negative dielectric anisotropy can be used. Examples of preferred liquid crystal compositions include Japanese Patent Application Laid-Open No. 57-114532, Japanese Patent Laid-Open Nos. 2-4725, Japanese Patent Laid-Open Nos. 4-224885, Japanese Patent Laid-Open Nos. 8-40953, Japanese Patent Laid-Open Nos. -168076, JP 10-168453, JP 10-236989, JP 10-236990, JP 10-236992, JP 10-236993, JP 10-236994 JP-A 10-237000, JP 10-237004, JP 10-237024, JP 10-237035, JP 10-237075, JP 10-237076 Japanese Patent Application Laid-Open No. 10-237448 (EP967261A1 Specification), Japanese Patent Application Laid-Open No. 10-287874, Japanese Patent Application Laid-Open No. 10-287875, Japanese Patent Application Laid-Open No. 10-291945, Japanese Patent Application Laid-Open No. 11-029581, Japanese Patent Application Laid-Open No. 11-080049 Japanese Patent Application Laid-Open No. 2000-256307, Japanese Patent Laid-Open No. 2001-019965, Japanese Patent Laid-Open No. 2001-072626, Japanese Patent Laid-Open No. 2001-192657, and the like.

It is also not a problem to add and use at least one optically active compound to the liquid crystal composition having the dielectric anisotropy plus or minus.

In the liquid crystal display element in this invention, a pair of board | substrate opposes so that the average orientation direction of the principal chain of the polyimide in the liquid crystal aligning film on each board | substrate may become a specific direction according to the kind of liquid crystal display element. For example, when a liquid crystal display element is a TN type liquid crystal display element, a pair of board | substrates form an electrode or a liquid crystal aligning film so that the average orientation direction of the principal chain of the polyimide in a liquid crystal aligning film of each board | substrate may cross 90 degrees. Facing the surface facing inward. In the case where the liquid crystal display element is an STN type liquid crystal display element, the average orientation direction of the main chain of the polyimide in the liquid crystal alignment film of each substrate is a normal reverse direction, that is, 180 degrees or so as to intersect at an angle greater than that. The pair of substrates oppose the surface on which the electrode or the liquid crystal alignment film is formed to face inward.

In addition, the liquid crystal display element in this invention can have other members according to the kind of liquid crystal display element. For example, in a TFT type liquid crystal device of color display using a thin film transistor, a thin film transistor, an insulating film, a protective film, a pixel electrode and the like are formed on the first transparent substrate, and light other than the pixel region is blocked on the second transparent substrate. Black matrix, color filter, planarization film, and pixel electrode.

Moreover, in an IPS type liquid crystal display element, a liquid crystal is clamped between the 1st transparent substrate in which the thin film transistor was formed, the opposing 2nd transparent substrate, and these substrates. The first transparent substrate has a pixel electrode and a common electrode formed so that the comb teeth alternately extend. Similarly to the conventional liquid crystal display element, the second transparent substrate has a black matrix, a color filter, a planarization film, and the like, which block light other than the pixel region. The comb-tooth shaped electrode is formed by depositing a resist pattern having a predetermined shape with a mask after depositing, for example, on a transparent substrate such as glass by using a sputtering method of metal such as Cr.

In addition, in the MVA type liquid crystal display element, when a minute projection is formed on a transparent substrate, or multi-domainization by light irradiation process may be performed through a masking process.

The liquid crystal aligning film in this invention is a reaction product of tetracarboxylic dianhydride and diamine, The process of orienting the polyamine acid in a film by irradiating light to the film of the polyamine acid containing an azo group in a principal chain, It can manufacture by the method containing the process of imidating a polyamic acid. The compound which has a side chain structure can be used for at least one of the said tetracarboxylic dianhydride and the said diamine.

The film of polyamine acid can be formed by apply | coating the liquid crystal aligning agent in this invention mentioned above on a board | substrate or an electrode, for example. As a coating method of a liquid crystal aligning agent, the spinner method, the printing method, the dipping method, the dropping method, the inkjet method, etc. are generally known. These methods are similarly applicable to this invention.

The azo group contained in the skeletal structure of the polyamine acid can normally take two geometric isomers of cinna and anti. Although anti-isomers are usually stable, when light of appropriate energy is irradiated to polyamine acids, the light is absorbed, and the azo group is changed into a new isomer. Since the new isomers are less stable than the anti isomers, the azo groups return to the anti isomers, but the anti isomers returned from the new isomers point in a random direction. At this time, when the light polarized in a specific direction is irradiated, the anti-isomer facing the specific direction is selectively changed to the new isomer, the new isomer is returned to the anti-isomer with a random orientation change. Since the anti-new photoisomerization reaction is repeated until no light absorption occurs, after sufficient light irradiation, the anti isomers are oriented vertically in the polarization direction of the light. In this invention, such photoisomerization reaction is used for the orientation control of polyamine acid.

In the step of orienting the polyamine acid in the film, the main chain of the polyamine acid is oriented by light irradiation. Such photo-alignment treatment conditions may be in any form as long as the object of the present invention is achieved. As a light source used for the photo-alignment process, a low pressure mercury lamp, a high pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, a Deep UV lamp, an excimer laser, etc. can be used.

In the case of the present invention using an azo group photoisomerization reaction, the wavelength of the light used for the photoalignment process is 300 to 600 nm, more preferably 340 to 500 nm. This is because photodegradation of the coating film is unlikely to occur in light having a wavelength of 300 nm or more, and photoisomerization reaction proceeds easily in light having a wavelength of 600 nm or less. In addition, it is preferable to remove low wavelength light using a long wavelength transmission filter, a band pass filter, or the like. On the other hand, it is preferable to use an ultraviolet-visible continuous light source and a band pass filter together, and to irradiate an ultraviolet light and a visible light simultaneously.

Although the irradiation light quantity of the light used for the alignment process of the polyamine acid in the direction parallel to the surface of a liquid crystal aligning film changes with kinds of the liquid crystal aligning agent to be used, the wavelength of a light source, and irradiation conditions, the larger the irradiation amount, the stronger the photo-alignment process is The high orientation index Δ is obtained. As a reference, Deep light irradiation dose when using a UV lamp and a band-pass filter of 340~500nm perform the alignment treatment is not less than 2J / cm ^2, and preferably at least 30J / cm ^2, and more preferably 100J / cm ² or more. Light dose, special upper limit, but, if in order to avoid degradation of the liquid crystal alignment film, 2,000J / cm ² or less is preferable, and considering economic efficiency, such as the cost of the equipment and the process is preferably 300J / cm ² or less.

The main chain of polyamine acid in a film | membrane can be orientated in a predetermined direction by irradiating the said film | membrane with the light by which polarization was controlled. The main chain of polyamine acid is oriented in the direction perpendicular to the polarization direction of the irradiated light. Examples of light in which polarization is controlled include linearly polarized light, circular flat light, elliptical polarized light, and the like. Here, the non-polarized light is also light having a random polarization, and is included in the light which controlled the polarization. Control of polarization can be performed with a polarizing filter or a polarizing prism. Or light can be performed by transmitting the inclined glass plate.

In order to orient the polyamic acid in a predetermined direction when viewed in a direction perpendicular to the surface of the film, light with the polarization controlled can be used as light for changing the geometric isomer by the azo group from the anti isomer to the new isomer. In order to orientate in the diagonal direction with respect to the surface of the film of polyamine acid, light is irradiated from the diagonal direction with respect to the surface of the film of the said polyamine acid.

The light irradiated from the oblique direction with respect to the surface of the film of the said polyamine acid can be changed in order to obtain the orientation of the polyimide main chain made into the objective, and the pretilt angle of a liquid crystal.

Although the irradiation angle at the time of irradiating light from the inclination direction with respect to the surface of a film | membrane is not specifically limited, In order to acquire arbitrary pretilt angle, it is preferable that it is 20-70 degree with respect to the surface of a liquid crystal aligning film or the board surface, and also 30 It is more preferable that it is -60 degree | times, in order to acquire favorable orientation of a polyimide main chain and the pretilt angle of a liquid crystal.

In the present invention, the polyamic acid in the film in a direction parallel to the surface of the film is irradiated by irradiating light from the inclination angle with respect to the surface (substrate surface) of the film to change the geometric isomer by the azo group from the anti-isomer to the new isomer. It is possible to control both the orientation (average orientation direction) and the orientation (tilt angle with respect to the substrate surface) of the polyamine acid on the incident surface of light. In the present invention, a preferred method of controlling the orientation of the polyamine acid in the film is that after irradiating light linearly polarized from the vertical direction with respect to the surface (substrate surface) of the film, the vertical plane is further incident in the polarization direction of the linearly polarized light. It is irradiating unpolarized light at the said irradiation angle as a surface. By doing in this way, the degree (alignment index (DELTA)) of the orientation of the principal chain of a polyimide can be raised, and the orientation of the liquid crystal which has a pretilt angle can be obtained by the same method.

In manufacture of a liquid crystal aligning film, it is preferable to perform the process of drying the film of the liquid crystal aligning agent obtained on a transparent substrate further. It is preferable to perform a drying process before the photo-alignment process mentioned above, As a drying process, the method of heat-processing in oven or an infrared furnace, the method of heat-processing on a hotplate, etc. are generally known. These methods are similarly applicable in this invention. It is preferable to perform a drying process at comparatively low temperature within the range which can evaporate a solvent.

The imidation of the polyamine acid oriented in the said film is normally performed by heating. Also in this invention, heat processing can be applied to the imidation of the polyamine acid after orientation. As a method of a heat processing process, the method similar to the above-mentioned drying process is applicable. It is preferable to perform a heat processing process at the temperature of about 150-300 degreeC generally.

The liquid crystal display element in this invention manufactures a liquid crystal aligning film on a board | substrate as mentioned above, and then, arranges the said board | substrate to face each other via a spacer, the process of putting a liquid crystal composition and sealing, the process of adhering a polarizing film, etc. It is manufactured through the process of.

The liquid crystal display element in this invention can also perform the washing process with a washing | cleaning liquid. As a washing | cleaning method, jet spray, steam washing | cleaning, ultrasonic washing | cleaning, etc. are mentioned. These methods may be used alone or in combination. Pure water, alcohols such as methyl alcohol, ethanol or isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene or xylene, halogenated hydrocarbons such as methylene chloride or ketones such as acetone or methyl ethyl ketone can be used as the washing liquid. It is not limited to these. Of course, these washing | cleaning liquids can utilize the thing refine | purified fully and few impurities.

The ratio of tetracarboxylic dianhydride and / or diamine having a photoisomerization structure and / or diamine to be used in the present invention should be 10 to 90 mol%, preferably 15 to 80 mol%, more preferably It needs to be 20-70 mol%. When the ratio of tetracarboxylic dianhydride and / or diamine having a photoisomerized structure is 10 mol% or more, the orientation of the polymer main chain is improved by photoisomerization, and the ratio of tetracarboxylic dianhydride and / or diamine having a photoisomerized structure is obtained. If it is 90 mol% or less, a pretilt angle will become favorable.

EXAMPLE

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

Tetracarboxylic acid dianhydride

  Pyromellitic dianhydride: PMDA

Diamine

  4,4'-diaminoazobenzene: DAZ

Diamine with side chain structure

  A compound of formula 1: T1

  Compound of formula II: T2

solvent

  N-methyl-2-pyrrolidone: NMP

Example  One

1) Preparation of Liquid Crystal Aligner A1

Into a 200 mL four-necked flask equipped with a thermometer, a stirrer, a raw material inlet, and a nitrogen gas inlet, 2.1104 g and 0.4802 g of DAZ and T1 and 30.00 g of dehydrated NMP were introduced, respectively, and stirred and dissolved under a dry nitrogen stream. After adding 2.4096g of PMDA, and making it react for 30 hours, maintaining the temperature of a reaction system at 5 degreeC, 65.00g of dehydration NMP was added, and the liquid crystal aligning agent of polyamine acid of 5 mass% of the density | concentration of a polymer component was manufactured. When temperature rises by reaction heat during reaction of a raw material, it reacted by restricting reaction temperature to about 70 degreeC or less.

2) Absorbance of Infrared Light, Measurement of Film Thickness of Liquid Crystal Alignment Film, and Calculation of Orientation Index Δ

By diluting the liquid crystal aligning agent of the obtained A1 PMDA / DAZ / T1 (the raw material molar ratio = 50/45/5) with NMP it was applied to and then to 1.34% by mass, the spinner on the CaF ₂ substrate (thickness 2mm). Application conditions were 3,000 rpm and 60 second. After coating, light was irradiated using a 500W Deep UV lamp (UXM-501MD) manufactured by Ushio Electric Co., Ltd. as a light source. The wavelength range of the irradiated light was 340-500 nm by transmitting the band pass filter (The product made by Chosun Spectroscopy) of 340-500 nm of transmission wavelength ranges.

First, the light which made linearly polarized light through the granular polarizing prism was irradiated from the perpendicular direction with respect to the board | substrate surface. The irradiation amount was 156 J / cm ² . Subsequently, the light of unpolarized light was irradiated with 45 degrees of incidence angles (defined from a board | substrate normal line) using the perpendicular | vertical surface as an incident surface in the polarization direction of the light in 1st linearly polarized light irradiation. The irradiation amount was 221 J / cm ² . Subsequently, the light-irradiated sample was heat-processed for 60 minutes at 250 degreeC in nitrogen atmosphere, and the liquid crystal aligning film was formed.

Except that does not already have a film thickness d is, the light irradiation of the polyamic acid film has a thickness d _PAA and the liquid crystal alignment layer before encoding a polyimide film thickness produced in the same process, the automatic polarization analysis device (Co., Ltd. Shimadzu product, APE-100 ), The measurement wavelength was measured at 632.8 nm (He-Ne laser) and the incident angle of 62.5 degrees, and was determined to be d _PAA = 19 nm and d = 11 nm, respectively. From the ratio of the film thickness before and after imidation, the correction coefficient (gamma) of the thickness of the liquid crystal aligning film by imidation was 0.58.

The infrared absorption spectrum of the obtained liquid crystal aligning film was measured on the conditions of measurement temperature 32 degreeC and 400 times of integration using FT-IR apparatus (spectrometer: Mattson Galaxy 3020, detector: mercury cadmium telluride).

The infrared light which permeate | transmitted the polarizer was irradiated from the board | substrate plane vertical direction of a liquid crystal aligning film. The infrared light spectrum when measured so that the average orientation direction and polarization direction of a sample may be parallel, and the infrared light spectrum when measured so that it was perpendicular | vertical were measured. The difference in absorbance (| A∥-A (|) of the liquid crystal alignment film and the liquid crystal alignment film were obtained by using the integral value of the absorption band in the vicinity of 1360 cm ^-1 attributable to the CNC stretching vibration of the infrared light spectrum measured in parallel and vertical directions. The sum of absorbances (A⊥ + A∥) was calculated.

In order to calculate the absorption coefficient α of the polyamine acid film before imidization, a 2.00 mass% polyamine acid solution was applied onto the CaF ₂ substrate (thickness 2 mm) with a spinner. Application conditions were 3,000 rpm and 60 second. It was 36 nm as a result of measuring the film thickness of the polyamic-acid film which does not irradiate light. The ultraviolet-visible absorption spectrum of the polyamic acid membrane before imidation was measured by vertical transmission, and the absorbance (= log (T _sub / T _sample )) having a wavelength of 364 nm was 0.36. From formula (3), the absorption coefficient (alpha) of the polyamine acid film before imidation is calculated | required as 0.023. An ultraviolet-visible absorption spectrum can be measured, for example with an ultraviolet-visible spectrophotometer (Shimadzu MPS-2000).

From (alpha) = 0.023 and (gamma) = 0.58, the substantial film thickness d 'of the photo-alignment process area | region of the said liquid crystal aligning film was 25 nm. In the case where the film thickness is 11 nm, since d <d ', d / d' = 1, the liquid crystal alignment film is calculated by the values of (| A∥-A⊥ |) and (A⊥ + A∥) obtained. The orientation index (DELTA) of the polyimide main chain of was 0.28.

3) Measurement of the pretilt angle of the liquid crystal

Held between a pair of CaF ₂ substrate to prepare a liquid crystal alignment film on the same conditions, as a spacer for polyester film having a thickness of 25μm, allowed to face the one surface to form a liquid crystal alignment film so that the inner side was prepared by anti-parallel cell. The antiparallel cell referred to here means a cell formed so that the irradiation direction of unpolarized light when the photoalignment process is performed on the film of the polyamic acid apply | coated to the board | substrate is parallel and opposite.

A cyano phenyl liquid crystal (5CB) represented by the following structural formula (5) was injected into the cell at 80 ° C, and gradually cooled to room temperature to prepare a pretilt measuring cell (liquid crystal display device). As a result of measuring the pretilt angle of the liquid crystal of the manufactured pretilt angle measuring cell, the pretilt angle was 3.3 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light. The pretilt angle was measured using a He-Ne laser (oscillation wavelength 632.8 nm) by the crystal rotation method. The temperature at the time of measuring the pretilt angle was 25 degreeC. The NI point (nematic isotropic phase transition temperature) of 5 CB was 35 ° C., and the refractive index at a wavelength of 632.8 nm was n _e = 1.706 (ideal light) and n _o = 1.530 (normal light).

Example  2

Instead of the liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent A2 of PMDA / DAZ / T2 (raw material molar ratio = 50 / 37.5 / 12.5) was manufactured. A liquid crystal aligning agent A2 is obtained, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering, pursuant to, thereby forming a liquid crystal alignment film having a thickness of 9nm. The film thickness d _PAA of the polyamic acid film before imidation was 18 nm, and the correction coefficient (gamma) of the thickness of the liquid crystal aligning film by imidation was 0.50. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.015, and the substantial thickness d 'of the liquid crystal aligning film was 33 nm.

Next, when the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, it was 0.17. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 71.3 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Example  3

Instead of liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent A3 of PMDA / DAZ / T2 (raw material molar ratio = 50/25/25) was manufactured. A liquid crystal aligning agent A3 obtained, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering pursuant to, thereby forming a liquid crystal alignment film having a thickness of 11nm. The film thickness d _PAA of the polyamine acid film before imidation was 19 nm, and the correction coefficient gamma of the thickness of the liquid crystal aligning film by imidation was 0.58. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.009, and the substantial film thickness d 'of the liquid crystal aligning film was 64 nm.

Next, when the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, it was 0.06. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 89.6 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Example  4

Instead of the liquid crystal aligning agent A1 in Example 1, the liquid crystal aligning agent A4 of PMDA / DAZ / T1 (raw material molar ratio = 50 / 43.75 / 6.25) was manufactured. A liquid crystal aligning agent thus obtained A4, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering, pursuant to, thereby forming a liquid crystal alignment film having a thickness of 12nm. The film thickness d _PAA of the polyamic acid film before imidation was 20 nm, and the correction coefficient (gamma) of the thickness of the liquid crystal _aligning film by imidation was 0.60. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.022, and the substantial film thickness d 'of the liquid crystal aligning film was 27 nm.

Next, the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, and it was 0.27. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 4.8 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Example  5

Instead of liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent A5 of PMDA / DAZ / T1 (raw material molar ratio = 50 / 42.5 / 7.5) was manufactured. A liquid crystal aligning agent obtained A5, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering, pursuant to, thereby forming a liquid crystal alignment film having a thickness of 10nm. The film thickness d _PAA of the polyamic acid film before imidation was 17 nm, and the correction coefficient gamma of the thickness of the liquid crystal aligning film by imidation was 0.59. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.020, and the substantial film thickness d 'of the liquid crystal aligning film was 30 nm.

Next, the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, and it was 0.25. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 5.8 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Example  6

Instead of liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent A6 of PMDA / DAZ / T1 (raw material molar ratio = 50 / 37.5 / 12.5) was manufactured. A liquid crystal aligning agent obtained A6, carried out in Example 1, Method a CaF ₂ substrate coated on a spinner, light irradiation, pursuant to firing, thereby forming a liquid crystal alignment film having a thickness of 10nm. The film thickness d _PAA of the polyamine acid film before imidation was 15 nm, and the correction coefficient gamma of the thickness of the liquid crystal aligning film by imidation was 0.66. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.020, and the substantial film thickness d 'of the liquid crystal aligning film was 33 nm.

Next, when the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, it was 0.20. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 75.4 degrees. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Comparative example  One

Instead of liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent B1 of PMDA / DAZ (raw material molar ratio = 50/50) was manufactured. A first B1 obtained liquid crystal alignment, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering, pursuant to, thereby forming a liquid crystal alignment film having a thickness of 10nm. However, the baking time was performed in 120 minutes. The film thickness d _PAA of the polyamic acid film before imidation was 16 nm, and the correction coefficient (gamma) of the thickness of the liquid crystal aligning film by imidation was 0.63. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.028, and the substantial film thickness d 'of the liquid crystal aligning film was 23 nm.

Next, the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, and it was 0.27. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 1.4 degrees. The inclination direction of the liquid crystal was an irradiation direction of non-polarized light.

Comparative example  2

Instead of liquid crystal aligning agent A1 in Example 1, liquid crystal aligning agent B2 of PMDA / DAZ / T1 (raw material molar ratio = 50 / 47.5 / 2.5) was manufactured. B2 the liquid crystal aligning agent thus obtained, carried out in Example 1, Method a CaF ₂ substrate on a spinner coating, irradiation, sintering, pursuant to, thereby forming a liquid crystal alignment film having a thickness of 12nm. The film thickness d _PAA of the polyamic acid film before imidation was 18 nm, and the correction coefficient (gamma) of the thickness of the liquid crystal aligning film by imidation was 0.67. The absorption coefficient (alpha) of the polyamine acid film before imidation was 0.026, and the substantial film thickness d 'of the liquid crystal aligning film was 26 nm.

Next, the orientation index (DELTA) of the polyimide main chain of a liquid crystal aligning film was evaluated by the method according to Example 1, and it was 0.33. Moreover, the antiparallel cell was produced by the method according to Example 1, and the pretilt angle was measured and found to be 1.0 degree. The inclination direction of the liquid crystal was an irradiation direction of unpolarized light.

Comparative example  3

Except for irradiating linearly polarized light after heat treatment at 250 ° C. for 60 minutes in a nitrogen atmosphere from the direction perpendicular to the substrate surface, that is, irradiating ultraviolet light of linearly polarized light after imidating the polyamine acid film by heat, A pair of liquid crystal aligning films were formed by the method according to Example 1.

Next, the pretilt angle was measured by the method according to Experimental Example 1, but the pretilt angle and the orientation index Δ could not be measured because of the poor orientation.

In Table 1, mol% of the liquid crystal aligning agent raw material of each Example and each comparative example was shown.

TABLE 1

Table 2 shows the measurement results of the film thickness of the liquid crystal aligning film of each Example and each comparative example, the orientation index Δ and the pretilt angle of the polyimide main chain.

TABLE 2

From the results of Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1, 2, 3, the content rate of the side chain structure diamine with respect to all the diamine was changed, the liquid crystal which carried out the orientation process by irradiating the light which controlled polarization By using the alignment film, it can be seen that a liquid crystal display element having a wide range of liquid crystal pretilt angles is obtained.

In particular, the liquid crystal aligning agent B1 which does not contain side chain structure diamine is irradiated by carrying out the orientation treatment by irradiating the light which controlled polarization to the board | substrate which apply | coated the liquid crystal aligning agent which introduce | transduced the side chain structure diamine in the molar ratio with respect to all diamine at least 10% or more. It turns out that the pretilt angle larger than the pretilt angle produced | generated by the liquid crystal aligning film manufactured similarly using the can be produced.

According to the present invention, it is possible to provide a liquid crystal display element having less dust generation and static electricity problems and easy control of the pretilt angle, and at the same time, a liquid crystal aligning film and a liquid crystal capable of forming the liquid crystal aligning film. An alignment agent can be provided.

Claims (9)

In the reaction product of tetracarboxylic dianhydride and diamine, in the film of the polyamine acid which contains an azo group in a principal chain, the liquid crystal aligning film formed by imidating the polyamine acid orientated in the predetermined direction by irradiation of light, At least one of the tetracarboxylic dianhydride and the diamine has a side chain structure, The orientation index (DELTA) of the main chain of the polyimide in the liquid crystal aligning film calculated | required by following formula (1) is the range of 0.03-1.00, The pretilt angle of the liquid crystal at the time of forming the liquid crystal display element containing a liquid crystal aligning film is the range of 2-90 degrees: The liquid crystal aligning film characterized by the above-mentioned: Δ = (| A∥-A⊥ |) / (A∥ + A⊥) × d / d '(1) In the formula (1), A ′ is applied to the liquid crystal alignment film such that the polarized infrared light is perpendicular to the surface of the liquid crystal alignment film, and the polarization direction of the infrared light is parallel to the average alignment direction of the main chain of the polyimide. The integral absorbance by CNC stretching vibration of the imide ring near the wavenumber 1360cm ^-1 at the time of incidence is shown, and A 'shows the polarized infrared light perpendicular to the surface of the liquid crystal alignment film, and the average orientation of the main chain of the polyimide. The integral absorbance by the CNC stretching vibration of the imide ring near the wavenumber 1360 cm ^-1 when incident on the liquid crystal alignment film when the polarization direction of the infrared light is perpendicular to the direction, d represents the film thickness of the liquid crystal alignment film, d 'represents the actual film thickness of the photo-alignment process area | region of a liquid crystal aligning film. The method of claim 1, Said polyamine acid is a reaction product of tetracarboxylic dianhydride which does not have a side chain structure, diamine which does not have a side chain structure containing an azo group between two amino, and diamine which has a side chain structure, The diamine which has the said side chain structure is contained in 7 to 90 mol% with respect to the total amount of the said diamine, The liquid crystal aligning film characterized by the above-mentioned. The method of claim 2, The diamine which does not have a side chain structure containing an azo group between said 2 amino is 4,4'- diamino azobenzene, The liquid crystal aligning film characterized by the above-mentioned. The method of claim 2, Said tetracarboxylic dianhydride is a pyromellitic dianhydride, The liquid crystal aligning film characterized by the above-mentioned. The method of claim 2, The diamine having the side chain structure is a compound represented by the following general formula (I'-11):

Wherein R ²⁴ represents alkyl having 1 to 10 carbons or alkoxy having 1 to 10 carbons. As a reaction product of tetracarboxylic dianhydride and diamine, Polyamine acid which contains an azo group in the principal chain; And solvent It includes, wherein the diamine comprises a diamine having a side chain structure liquid crystal aligning agent. The method of claim 6, Said polyamine acid is a reaction product of tetracarboxylic dianhydride which does not have a side chain structure, diamine which does not have a side chain structure containing an azo group between two amino, and diamine which has a side chain structure, The diamine which has the said side chain structure is contained in 7 to 90 mol% with respect to the total amount of the said diamine, The liquid crystal aligning agent characterized by the above-mentioned. A pair of substrates that are arranged to face each other, an electrode formed on one or both sides of the facing surfaces of each of the pair of substrates, a liquid crystal alignment film formed on the facing surfaces of each of the pair of substrates, and In a liquid crystal display device having a liquid crystal layer formed between a pair of substrates, One or both of the liquid crystal aligning films formed in the opposing surface of each of the said pair of board | substrates are liquid crystal aligning films in any one of Claims 1-5, The liquid crystal display element characterized by the above-mentioned. A reaction product of tetracarboxylic dianhydride and diamine, comprising: irradiating a film of a polyamine acid containing azo groups in a main chain with light to orient the polyamine acid in the film; and imidizing the polyamine acid oriented in the film. As a method of imidating the said polyamine acid to manufacture a liquid crystal aligning film, At least one of the tetracarboxylic dianhydride and the diamine is used a compound having a side chain structure, The step of orienting the polyamine acid in the film, (A) When the light which changes the geometric isomer by said azo group from anti isomer to syn isomer is irradiated to the said film | membrane, and the polyamic acid in the said film | membrane is seen from the perpendicular direction with respect to the surface of a film | membrane, To orient in the direction, and Irradiating light from the oblique direction to the surface of the film of the polyamine acid and orienting the polyamine acid in the oblique direction with respect to the surface of the film, or (B) When the light which changes the geometric isomer by an azo group from anti-isomer to new isomer is irradiated to the said film | membrane from the inclination direction with respect to the surface of the said film | membrane, and the polyamic acid in the said film | membrane is seen from the perpendicular direction with respect to the surface of the film | membrane. And orienting in a predetermined direction and at the same time in an oblique direction with respect to the surface of the film.