TWI845471B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element, and methods for manufacturing the same - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, which comprises: a polymer obtained from a diamine component, and an organic solvent, wherein the diamine component comprises: at least one diamine selected from diamines having structures represented by the following formulas (1) to (3), and a diamine having a structure represented by the following formula (4) (wherein W and X are independently an aromatic ring having 6 to 14 carbon atoms, Y is an oxygen atom or a sulfur atom, Z is a divalent organic group including an oxygen atom and an alkylene group, _R1 to _R7 are independently a hydrogen atom or a monovalent organic group, and m, n, o, p and q are independently integers of 0 to 4).

Description

Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element, and methods for manufacturing the same

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element for manufacturing a liquid crystal display element with excellent burn-in characteristics.

Liquid crystal display elements are known to be lightweight, thin, and low-power display devices. In recent years, they have been used in large-scale television applications and have achieved significant development. Liquid crystal display elements are composed of a pair of transparent substrates with electrodes, for example, holding a liquid crystal layer. In addition, in liquid crystal display elements, an organic film made of organic materials is used as a liquid crystal alignment film in order to achieve a desired alignment state of the liquid crystal between the substrates.

That is, the liquid crystal alignment film is a component of the liquid crystal display element, and is formed on the surface where the substrate holding the liquid crystal contacts the liquid crystal, and plays a role in aligning the liquid crystal in a certain direction between the substrates. In addition, in addition to playing a role in aligning the liquid crystal in a certain direction such as a direction parallel to the substrate, the liquid crystal alignment film is sometimes also required to control the pre-tilt angle of the liquid crystal. In such a liquid crystal alignment film, the ability to control the alignment of the liquid crystal (hereinafter referred to as alignment control ability) can be given by performing an alignment treatment on the organic film constituting the liquid crystal alignment film.

As an alignment treatment method for liquid crystal alignment films that are used to impart alignment control capabilities, the rubbing method has long been known. The so-called rubbing method refers to a method in which an organic film such as polyvinyl alcohol, polyamide, or polyimide on a substrate is wiped (rubbed) along a certain direction using a cloth such as cotton, nylon, or polyester to align the liquid crystal along the wiping direction (rubbing direction). This rubbing method has been used in the manufacturing process of liquid crystal display elements in the past because it can easily achieve a relatively stable alignment state of the liquid crystal. In addition, the organic film used as the liquid crystal alignment film is mainly a polyimide-based organic film with excellent reliability such as heat resistance or electrical properties.

However, the rubbing method of rubbing the surface of the liquid crystal alignment film made of polyimide or the like has the problem of dust generation or static electricity generation. In addition, due to the high precision of liquid crystal display elements in recent years, or the unevenness caused by the electrodes on the corresponding substrate or the active switch element for liquid crystal driving, it is sometimes impossible to rub the surface of the liquid crystal alignment film evenly with a cloth, so it is impossible to achieve uniform liquid crystal alignment.

Therefore, as an alternative alignment treatment method for liquid crystal alignment films that cannot be rubbed, photoalignment is being actively studied.

There are various methods for photo-alignment, which use linearly polarized light or collimated light to form anisotropy in the organic film that constitutes the liquid crystal alignment film, and align the liquid crystal based on the anisotropy.

As the main photo-alignment method, a decomposition-type photo-alignment method is known. For example, a polyimide film is irradiated with polarized ultraviolet light, and the polarization direction dependence of the ultraviolet absorption of the molecular structure is used to cause anisotropic decomposition. Alternatively, the liquid crystal is aligned by using the polyimide that remains without decomposition (for example, refer to patent document 1). [0009] In addition, a photo-crosslinking type or photo-isomerization type photo-alignment method is also known. For example, polyvinyl cinnamate is used and irradiated with polarized ultraviolet light to cause a dimerization reaction (crosslinking reaction) in the double bond parts of the two side chains parallel to the polarization. Alternatively, the liquid crystal is aligned in a direction perpendicular to the polarization direction (for example, refer to non-patent document 1). Furthermore, when using a side-chain polymer having azobenzene in the side chain, polarized ultraviolet light is irradiated to cause an isomerization reaction of the azobenzene part of the side chain parallel to the polarization, so that the liquid crystal is aligned in a direction perpendicular to the polarization direction (for example, refer to non-patent document 2). [0010] As in the above example, in the alignment treatment method of the liquid crystal alignment film by the photoalignment method, there is no need for friction, and there is no risk of dust or static electricity. Furthermore, even a substrate of a liquid crystal display element with an uneven surface can be subjected to an alignment treatment, making it an alignment treatment method of a liquid crystal alignment film suitable for an industrial production process. [Prior Art Literature] [Patent Literature] [0011] [Patent Literature 1] Japanese Patent Gazette No. 3893659 [Non-Patent Literature] [0012] [Non-Patent Literature 1] M. Shadt et al., Jpn. J. Appl. Phys. 31, 2155 (1992). [Non-Patent Literature 2] K. Ichimura et al., Chem. Rev. 100, 1847 (2000).

[Problems to be solved by the invention] [0013] As described above, the optical alignment method does not require the rubbing step itself, compared to the rubbing method that has been used in industry as an alignment processing method for liquid crystal display elements. Therefore, it has a great advantage. In addition, compared to the rubbing method in which the alignment control energy by rubbing is roughly constant, the optical alignment method can change the amount of polarized light irradiation to control the alignment control energy. However, in the optical alignment method, when it is desired to achieve the same degree of alignment control energy as that achieved by the rubbing method, a large amount of polarized light irradiation is sometimes required, or a stable liquid crystal alignment cannot be achieved. [0014] For example, in the decomposable optical alignment method described in the above-mentioned patent document 1, it is necessary to irradiate the polyimide film with ultraviolet light from a high-pressure mercury lamp with an output power of 500W for 60 minutes, which requires a long time and a large amount of ultraviolet light irradiation. Moreover, even in the case of dimerization or photoisomerization type photoalignment method, a large amount of ultraviolet irradiation of several J (joules) to tens of J is sometimes required. Furthermore, in the case of photocrosslinking type or photoisomerization type photoalignment method, since the thermal stability or optical stability of the liquid crystal alignment is poor, there will be problems such as poor alignment or display burn-in when the liquid crystal display element is made. In particular, in the lateral electric field driven liquid crystal display element, since the liquid crystal molecules are switched in the plane, it is easy to produce the alignment misalignment of the liquid crystal after the liquid crystal drive, and the display burn-in caused by AC drive will become a larger issue. [0015] Therefore, in the photo-alignment method, it is required to achieve efficient alignment processing or stable liquid crystal alignment, and it is required to have a liquid crystal alignment film or a liquid crystal alignment agent that can efficiently impart high alignment control energy to the liquid crystal alignment film. [0016] The object of the present invention is to provide a substrate having a liquid crystal alignment film for a lateral electric field driven liquid crystal display element that can efficiently impart alignment control energy and has excellent burning characteristics, and a lateral electric field driven liquid crystal display element having the substrate. [Means for Solving the Problem] [0017] The inventors of the present invention have discovered the following invention as a result of in-depth research in order to achieve the above-mentioned problem. 1. A liquid crystal alignment agent, comprising: a polymer obtained from a diamine component, and an organic solvent, wherein the diamine component comprises: at least one diamine selected from diamines having structures represented by the following formulas (1) to (3), and a diamine having a structure represented by the following formula (4) (wherein W and X are independently an aromatic ring having 6 to 14 carbon atoms, Y is an oxygen atom or a sulfur atom, Z is a divalent organic group including an oxygen atom and an alkylene group, _R1 to _R7 are independently a hydrogen atom or a monovalent organic group, and m, n, o, p and q are independently integers of 0 to 4), [0018] . [Effect of the Invention] [0019] According to the present invention, a substrate having a liquid crystal alignment film for a lateral electric field driven liquid crystal display element that can efficiently impart alignment control capability and has excellent burning characteristics, and a lateral electric field driven liquid crystal display element having the substrate can be provided. The lateral electric field driven liquid crystal display element manufactured according to the method of the present invention can efficiently impart alignment control capability, so that even if it is driven continuously for a long time, the display characteristics will not be damaged.

[Best form for implementing the invention] [0020] As a result of in-depth research, the inventors have obtained the following insights, thereby completing the present invention. The polymer composition used in the manufacturing method of the present invention has a photosensitive main chain polymer that can exhibit liquid crystal properties (hereinafter also referred to as the main chain polymer), and the coating obtained using the aforementioned polymer composition is a film of a photosensitive main chain polymer that can exhibit liquid crystal properties. The coating does not need to be subjected to friction treatment, and the alignment treatment is performed by polarized light irradiation. In addition, after the polarized light irradiation, the main chain polymer film is heated to form a coating that is endowed with alignment control capabilities (hereinafter also referred to as a liquid crystal alignment film). At this time, the tiny anisotropy presented by polarized light irradiation will become a driving force, and the main chain polymer itself will be more efficiently realigned by self-organization. As a result, a liquid crystal alignment film can be obtained that realizes highly efficient alignment processing and is endowed with high alignment control ability. [0021] The following is a detailed description of the implementation form of the present invention. A liquid crystal alignment agent, comprising: a polymer obtained from a diamine component (hereinafter also referred to as a main chain polymer), and an organic solvent, wherein the diamine component comprises: at least one diamine selected from the diamines having structures represented by the following formulas (1) to (3), and a diamine having a structure represented by the following formula (4) (wherein, W and X are independently aromatic rings having 6 to 14 carbon atoms, Y is an oxygen atom or a sulfur atom, Z is a divalent organic group containing an oxygen atom and an alkylene group, _R1 to _R7 are independently hydrogen atoms or monovalent organic groups, and m, n, o, p and q are independently integers of 0 to 4). The following describes each condition in detail. [0022] [0023] <Diamine with a specific structure> The liquid crystal alignment agent of the present invention is a liquid crystal alignment agent containing a polymer obtained from a diamine component and an organic solvent, wherein the diamine component includes: at least one diamine selected from the diamines having structures represented by the following formulas (1) to (3), and a diamine having a structure represented by the following formula (4). [0024] In the above formula (1), W is an aromatic ring having 6 to 14 carbon atoms, and _R1 is a monovalent organic group. As the aromatic ring here, benzene ring, naphthalene ring, biphenyl, etc. can be cited. From the viewpoint of the solubility of the obtained polymer, benzene ring is preferred. [0025] As the monovalent organic group, there can be cited an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group having 1 to 10 carbon atoms (preferably 1 to 3). Among them, a methyl group or a methoxy group is preferred as the monovalent organic group. [0026] As the diamine having the structure of the above formula (1), a diamine having two amino groups bonded in the above structure is preferred. The following are specific examples, but are not limited thereto. [0027] [0028] In the above formula (2), X is an aromatic ring having 6 to 14 carbon atoms, and _R2 is a monovalent organic group. As the aromatic ring here, benzene ring, naphthalene ring, biphenyl, etc. can be cited. From the viewpoint of the solubility of the obtained polymer, benzene ring is preferred. As the monovalent organic group, alkyl, alkenyl, alkoxy, fluoroalkyl, fluoroalkenyl, or fluoroalkoxy having 1 to 10 carbon atoms (preferably 1 to 3) can be cited. Among them, methyl or methoxy is preferred as the monovalent organic group. [0029] As the diamine having the structure of the above formula (2), a diamine having two amine groups bonded in the above structure is preferred. As specific examples, the following can be given, but they are not limited to them. [0030] [0031] In the above formula (3), Y is an oxygen atom or a sulfur atom, and _R3 to _R5 are independently a hydrogen atom or a monovalent organic group. As the monovalent organic group, there can be cited an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group having 1 to 10 carbon atoms (preferably 1 to 3). Among them, a methyl group or a methoxy group is preferred as the monovalent organic group. [0032] As the diamine having the structure of the above formula (3), a diamine having two amino groups bonded in the above structure is preferred. The following are specific examples, but are not limited to them. [0033] [0034] In the above formula (4), Z is a divalent organic group containing an oxygen atom and an alkylene group, and as the divalent organic group here, -O-(CH ₂ )rO- or -(OCH ₂ CH ₂ )sO- can be cited. R ₆ and R ₇ are each independently a monovalent organic group. As the monovalent organic group here, an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group having a carbon number of 1 to 10 (preferably 1 to 3) can be cited. Among them, a methyl group or a methoxy group is preferred as the monovalent organic group. [0035] As the diamine having the structure of the above formula (4), a diamine having two amine groups bonded in the above structure is preferred. As specific examples, the following can be cited, but they are not limited to them. [0036] [0037] Here, if r is an even number such as 2, 4, 6 and 8, the linearity of the obtained polymer will become higher. As a result, in the heating step after polarized light irradiation, a liquid crystal alignment film with high alignment control ability can be obtained by realignment in a higher order. [0038] <Polymer> The polymer of the present invention is a polymer obtained using the above-mentioned diamine. As specific examples, polyamic acid, polyamic acid ester, polyimide, polyurea, polyamide, etc. can be cited. From the perspective of use as a liquid crystal alignment agent, it is more preferred to select at least one of a polyimide precursor containing a structural unit represented by the following formula (5) and a structural unit represented by the following formula (6), and a polyimide of the imide compound. [0039] [0040] In the above formula (5), _X1 is a tetravalent organic group derived from a tetracarboxylic acid derivative, _Y1 is a divalent organic group derived from a diamine having a structure selected from formulas (1) to (3), and _R11 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. In terms of ease of imidization by heating, _R11 is preferably a hydrogen atom, a methyl group or an ethyl group. [0041] <Tetracarboxylic dianhydride> _X1 is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. In addition, _X1 in the polyimide precursor is appropriately selected according to the solubility of the polymer in the solvent or the coating of the liquid crystal alignment agent, the alignment of the liquid crystal when the liquid crystal alignment film is made, the voltage retention rate, the storage charge and other required characteristics. One type can exist in the same polymer, or two or more types can be mixed. If a specific example of _X1 is to be represented, the structures of formulas (X-1) to (X-46) published on pages 13 to 14 of International Publication No. 2015/119168 can be cited. The following represents a preferred structure of _X1 , but the present invention is not limited to such. [0042] [0043] [0044] Among the above structures, (A-1) and (A-2) are particularly preferred from the viewpoint of further improving the film hardness, (A-4) is particularly preferred from the viewpoint of further improving the relaxation rate of stored charges, and (A-15) to (A-17) are particularly preferred from the viewpoint of further improving the liquid crystal orientation and the relaxation rate of stored charges. [0045] <Diamine> In formula (5), a specific example of _Y1 is a structure obtained by removing two amino groups from a diamine having a structure selected from the aforementioned formulas (1) to (3). [0046] In formula (6), _X2 is a tetravalent organic group derived from a tetracarboxylic acid derivative, _Y2 is a divalent organic group derived from a diamine having a structure represented by formula (4), and _R12 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. In terms of easy imidization by heating, R ₁₂ is preferably a hydrogen atom, a methyl group or an ethyl group. [0048] As a specific example of _X2 , including a preferred example, there can be cited a structure that is the same as that exemplified by _X1 in formula (5). As a specific example of _Y2 , there can be cited a structure obtained by removing two amino groups from a diamine having a structure represented by the aforementioned formula (4). [0049] <Polymer (other structural units)> The polyimide precursor containing the structural unit represented by the formula (5) and the structural unit represented by the formula (6) may also contain at least one type of polyimide selected from the structural unit represented by the following formula (7) and the imide compound, within the scope that does not impair the effects of the present invention. [0050] [0051] In formula (7), _X3 is a tetravalent organic group derived from a tetracarboxylic acid derivative, _Y3 is a divalent organic group derived from a diamine that does not include any structure represented by formulas (1) to (4) in the main chain direction, _R13 is the same as the definition of _R11 in the above formula (5), and _R23 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In addition, at least one of the two _R23s is preferably a hydrogen atom. [0052] As specific examples of _X3 , preferred examples are also included, and the same structure as _that exemplified in formula (5) can be cited. In addition, _Y3 is a divalent organic group derived from a diamine that does not include any structure represented by formulas (1) to (4) in the main chain direction, and its structure is not particularly limited. Furthermore, _Y3 is appropriately selected according to the solubility of the polymer in the solvent or the coating property of the liquid crystal alignment agent, the alignment of the liquid crystal when the liquid crystal alignment film is made, the voltage retention rate, the storage charge and other required characteristics. One type may exist in the same polymer, or two or more types may be mixed. [0053] To represent Y ₃ , the structure of formula (2) published on page 4 of International Publication No. 2015/119168, and the structures of formulas (Y-1) to (Y-97), (Y-101) to (Y-118) published on pages 8 to 12; the divalent organic group obtained by removing two amine groups from formula (2) published on page 6 of International Publication No. 2013/008906; the divalent organic group obtained by removing two amine groups from formula (2) published on page 8 of International Publication No. 2015/122413 The divalent organic group formed by removing two amine groups from formula (1) as disclosed in the International Publication No. 2015/060360 on page 8; the divalent organic group formed by removing two amine groups from formula (1) as disclosed in the Japanese Patent Publication No. 2012-173514 on page 8; the divalent organic group formed by removing two amine groups from formula (A) to (F) as disclosed in the International Publication No. 2010-050523 on page 9, etc. The following shows a preferred structure of Y ₃ , but the present invention is not limited thereto. [0054] [0055] [0056] [0057] [0058] Among the above structures, (B-28), (B-29) and the like are particularly preferred from the perspective of further improving the film hardness, (B-1) to (B-3) and the like are particularly preferred from the perspective of further improving the liquid crystal alignment, (B-2), (B-9), (B-14) to (B-18) and (B-27) and the like are particularly preferred from the perspective of further improving the relaxation speed of the stored charge, and (B-26) and the like are preferred from the perspective of further improving the voltage retention rate. At least one of the polyimide precursors comprising the structural units represented by formula (5) and the structural units represented by formula (6), and the polyimide of the imide product, when the polyimide precursor also comprises the structural units represented by formula (7), the total of the structural units represented by formula (5) and the structural units represented by formula (6) is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more relative to the total of formula (5), formula (6) and formula (7). [0059] The molecular weight of the polyimide precursor used in the present invention is preferably a weight average molecular weight of 2,000 to 500,000, more preferably 5,000 to 300,000, and more preferably 10,000 to 100,000. As the polyimide containing the structural units represented by formula (5) and formula (6), there can be cited a polyimide obtained by ring-closing the aforementioned polyimide precursor. In the polyimide, the ring-closing rate (also referred to as the imidization rate) of the amide group does not necessarily need to be 100%, and can be arbitrarily adjusted according to the use or purpose. As a method for imidizing the polyimide precursor, thermal imidization in which a solution of the polyimide precursor is directly heated, or catalytic imidization in which a catalyst is added to the solution of the polyimide precursor can be cited. [0060] <Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention contains a polymer (specific polymer) obtained from a diamine component, and the diamine component includes: at least one diamine selected from the diamine having a structure represented by formula (1) to (3) and a diamine having a structure represented by formula (4), but within the limit that the effect described in the present invention can be exerted, it can also contain two or more specific polymers of different structures. In addition to the specific polymer, it can also contain other polymers, that is, polymers that do not have a divalent group represented by formula (1) to formula (4). As other types of polymers, polyamine, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylate, etc. can be cited. If the liquid crystal alignment agent of the present invention contains other polymers, the ratio of the specific polymer to the total polymer components is preferably 5% by mass or more, and as an example, 5 to 95% by mass can be cited. [0061] The liquid crystal alignment agent is used to prepare a liquid crystal alignment film, and from the viewpoint of forming a uniform thin film, it is generally in the form of a coating liquid. Even the liquid crystal alignment agent of the present invention is preferably a coating liquid containing the aforementioned polymer component and an organic solvent that dissolves the polymer component. At this time, the concentration of the polymer in the liquid crystal alignment agent can be appropriately changed according to the thickness of the coating to be formed. In terms of forming a uniform and defect-free coating, 1% by mass or more is preferred, and in terms of the storage stability of the solution, it is preferably set to 10% by mass or less. The particularly preferred polymer concentration is 2~8% by mass. [0062] The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as it can uniformly dissolve the polymer component. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferably used. [0063] In addition to the above-mentioned solvents, the organic solvent contained in the liquid crystal alignment agent can usually be used in combination with a mixed solvent of a solvent that improves the coating property when the liquid crystal alignment agent is applied or the surface smoothness of the coating film. Even the liquid crystal alignment agent of the present invention can be used appropriately with such a mixed solvent. Specific examples of the organic solvents used in combination can be cited as follows, but are not limited to these examples. [0064] For example, ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentanol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1 ,4-Butanediol, 2,3-Butanediol, 1,5-Pentanediol, 2-Methyl-2,4-pentanediol, 2-Ethyl-1,3-Hexanediol, Dipropyl Ether, Dibutyl Ether, Dihexyl Ether, Dioxane, Ethylene Glycol Dimethyl Ether, Ethylene Glycol Diethyl Ether, Ethylene Glycol Dibutyl Ether, 1,2-Butoxyethane, Diethylene Glycol Dimethyl Ether, Diethylene Glycol Diethyl Ether, 4-Hydroxy-4-methyl-2-pentanone, Diethylene Glycol Methyl Ether, Diethylene Glycol Dibutyl Ether, 2-Pentanone, 3-Pentanone, 2-Hexanone, 2-Heptanone, 4-Heptanone, 3-Ethoxybutyl Acetate, 1-Methylpentyl Acetate, 2-Ethylbutyl Acetate, 2-Ethylhexyl Acetate, Ethylene Glycol Mono acetate, ethylene glycol diacetate, propylene carbonate, ethyl carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1-(butoxyethoxy)propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ethyl acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol acetate monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, or solvents represented by the following formulas [D-1] to [D-3]. [0066] In formula [D-1], ^D1 represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], ^D2 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], ^D3 represents an alkyl group having 1 to 4 carbon atoms. Among them, 1-hexanol, cyclohexanol, 1,2-ethylene glycol, 1,2-propylene glycol, propylene glycol monobutyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether is preferably used. The type and content of such solvents can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent. The liquid crystal alignment agent of the present invention may also contain additional components other than polymer components and organic solvents without damaging the effect of the present invention. As such additional components, an adhesion auxiliary agent for improving the adhesion between the liquid crystal alignment film and the substrate or the adhesion between the liquid crystal alignment film and the sealant, a crosslinking agent for improving the strength of the liquid crystal alignment film, a dielectric or conductive material for adjusting the dielectric constant or resistance of the liquid crystal alignment film, etc. may be cited. As specific examples of such additional components, as disclosed in the well-known literature related to the liquid crystal alignment agent, if one example is to be represented, the components disclosed in the 53rd page [0105] to 55th page [0116] of the specification of Publication 2015/060357, etc. may be cited. [0068] <Method for manufacturing a substrate having a liquid crystal alignment film> and <Method for manufacturing a liquid crystal display element> The method for manufacturing a substrate having a liquid crystal alignment film of the present invention comprises the following steps: [I] a step of coating a polymer composition onto a substrate having a conductive film driven by a lateral electric field to form a coating, wherein the polymer composition comprises: a polymer obtained from a diamine component and an organic solvent, wherein the diamine component comprises: at least one diamine having a structure represented by formula (1) to (3) and a diamine having a structure represented by formula (4); [II] a step of irradiating the coating obtained by [I] with polarized ultraviolet light; and [III] a step of heating the coating obtained by [II]. By the above steps, a liquid crystal alignment film for a lateral electric field driven liquid crystal display element endowed with alignment control capability can be obtained, and a substrate having the liquid crystal alignment film can be obtained. [0069] Furthermore, by preparing a second substrate in addition to the substrate (first substrate) obtained above, a lateral electric field driven liquid crystal display element can be obtained. The second substrate is obtained by using a substrate without a lateral electric field driven conductive film instead of a substrate with a lateral electric field driven conductive film, and by adopting the above steps [I] to [III] (because a substrate without a lateral electric field driven conductive film is used, for convenience, it is sometimes referred to as steps [I'] to [III'] in this case), thereby obtaining a second substrate having a liquid crystal alignment film endowed with alignment control capability. [0070] The method for manufacturing a lateral electric field driven liquid crystal display element comprises the following steps: [IV] The first and second substrates obtained above are arranged opposite to each other in such a manner that the liquid crystal alignment films of the first and second substrates are interposed with liquid crystals, thereby obtaining a liquid crystal display element. In this way, a lateral electric field driven liquid crystal display element can be obtained. [0071] The following describes each of the steps [I] to [III] and [IV] of the manufacturing method of the present invention. <Step [I]> In step [I], a polymer composition containing a photosensitive main chain polymer that can exhibit liquid crystal properties within a specified temperature range and an organic solvent is applied on a substrate having a conductive film for lateral electric field driving to form a coating. [0072] <Substrate> There is no particular limitation on the substrate. If the liquid crystal display element to be manufactured is a transmissive type, it is preferred to use a substrate with high transparency. In this case, a glass substrate, or a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used without particular limitation. In addition, considering that it is suitable for a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can also be used. [0073] <Conductive film for lateral electric field drive> The substrate has a conductive film for lateral electric field drive. As the conductive film, if the liquid crystal display element is a transmissive type, ITO (Indium Tin Oxide: indium tin oxide), IZO (Indium Zinc Oxide: indium zinc oxide) and the like can be cited, but it is not limited to them. Furthermore, in the case of a reflective liquid crystal display element, a light-reflecting material such as aluminum can be cited as the conductive film, but it is not limited to them. The method of forming the conductive film on the substrate can use a conventionally known method. [0074] The method of coating the above-mentioned polymer composition on the substrate having a conductive film for lateral electric field driving is not particularly limited. The coating method is generally performed by screen printing, flat plate printing, flexographic printing or inkjet method in industry. Other coating methods include immersion method, roller coater method, slit coater method, rotator method (rotary coating method) or spray method, which can be used according to the purpose. [0075] After coating the polymer composition on the substrate having the conductive film driven by the lateral electric field, the solvent can be evaporated at 30~200°C, preferably 50~150°C by heating means such as a heating plate, a heat circulation oven or an IR (infrared) oven to obtain a coating. At this time, the drying temperature is preferably lower than that in step [III] from the viewpoint of the stability of the liquid crystal alignment. [0076] When the thickness of the coating is too thick, it is disadvantageous in terms of the power consumption of the liquid crystal display element. If it is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, it is preferably 5nm~300nm, and more preferably 10nm~150nm. In addition, a step of cooling the substrate on which the coating is formed to room temperature may be provided after step [I] and before the subsequent step [II]. [0077] <Step [II]> In step [II], the coating obtained in step [I] is irradiated with polarized ultraviolet light. When the film surface of the coating is irradiated with polarized ultraviolet light, the polarized ultraviolet light is irradiated from a certain direction relative to the substrate through a polarizing plate. The ultraviolet light used can be ultraviolet light within a wavelength range of 100nm to 400nm. It is preferred to select the optimal wavelength according to the type of coating used, through a filter, etc. Furthermore, for example, in order to selectively induce a photocrosslinking reaction, ultraviolet light in the wavelength range of 290 nm to 400 nm can be selected for use. As ultraviolet light, for example, light emitted from a high-pressure mercury lamp can be used. [0078] The irradiation amount of polarized ultraviolet light depends on the coating used. The irradiation amount is preferably in the range of 1% to 70% of the amount of polarized ultraviolet light that can achieve the maximum value of ΔA (hereinafter also referred to as ΔAmax), and is more preferably in the range of 1% to 50%, wherein ΔA is the difference between the absorbance of ultraviolet light in a direction parallel to the polarization direction of the polarized ultraviolet light in the coating and the absorbance of ultraviolet light in a perpendicular direction. [0079] <Step [III]> In step [III], the coating film irradiated with polarized ultraviolet light in step [II] is heated. By heating, the coating film can be given the ability to control its orientation. The heating can be performed using a heating plate, a heat circulation oven, or an IR (infrared) oven. The heating temperature can be determined by considering the temperature at which the coating film exhibits liquid crystal properties. [0080] The heating temperature is preferably within the temperature range at which the main chain polymer exhibits good liquid crystal orientation stability. If the heating temperature is too low, the effect of increasing the anisotropy due to heat will tend to be insufficient. If the heating temperature is too high, the anisotropy imparted by irradiation with polarized ultraviolet light will tend to disappear. In this case, it becomes difficult to realign in one direction by self-organization. [0081] The thickness of the coating formed after heating is preferably 5nm~300nm, and more preferably 50nm~150nm, for the same reasons as described in step [I]. [0082] By having the above steps, the manufacturing method according to the present invention can achieve efficient introduction of anisotropy into the coating. In addition, a substrate with a liquid crystal alignment film can be manufactured efficiently. [0083] <Step [IV]> Step [IV] is as follows: the substrate having a liquid crystal alignment film on a conductive film for lateral electric field driving obtained in [III] (first substrate) and the substrate having a liquid crystal alignment film without a conductive film obtained in the above-mentioned steps [I'] to [III'] (second substrate) are arranged opposite to each other with liquid crystals interposed therebetween and the liquid crystal alignment films on both sides are opposed to each other, and a liquid crystal cell is manufactured by a known method, thereby manufacturing a lateral electric field driven liquid crystal display element. In addition, steps [I'] to [III'] can be performed in the same manner as steps [I] to [III], except that a substrate without the lateral electric field driven conductive film is used in step [I] instead of a substrate with the lateral electric field driven conductive film. The difference between steps [I] to [III] and steps [I'] to [III'] is only the presence or absence of the above-mentioned conductive film, so the description of steps [I'] to [III'] is omitted. [0084] If an example of the manufacture of a liquid crystal cell or a liquid crystal display element is to be given, the following method can be exemplified: prepare the above-mentioned first and second substrates, spread spacers on the liquid crystal alignment film of one substrate, adhere another substrate in a manner that the liquid crystal alignment film surface becomes the inner side, reduce the pressure to inject liquid crystal and seal, or drip liquid crystal on the liquid crystal alignment film surface on which the spacers are spread, and then adhere the substrates and seal them. At this time, the substrate on one side is preferably a substrate having an electrode structure like a comb driven by a lateral electric field. The diameter of the spacer at this time is preferably 1 μm to 30 μm, and more preferably 2 μm to 10 μm. The diameter of the spacer determines the distance between a pair of substrates that clamp the liquid crystal layer, that is, the thickness of the liquid crystal layer. [0085] The manufacturing method of the substrate with coating of the present invention is to coat the polymer composition on the substrate to form a coating, and then irradiate polarized ultraviolet light. Then, by heating, the efficient introduction of anisotropy into the main chain polymer film is achieved, and the substrate with liquid crystal alignment film having the ability to control the alignment of liquid crystal is manufactured. In the coating used in the present invention, the principle of molecular realignment induced by the photoreaction and self-organization energy of the main chain is utilized to achieve the efficient introduction of anisotropy into the coating. In the manufacturing method of the present invention, after the main chain polymer is used to form a coating on the substrate, polarized ultraviolet light is irradiated, and then heating is performed to manufacture a liquid crystal display element. [0086] Therefore, the coating used in the method of the present invention efficiently introduces anisotropy by sequentially irradiating the coating with polarized ultraviolet light and performing a heat treatment, so that a liquid crystal alignment film with excellent alignment control can be produced. [0087] In addition, in the coating used in the method of the present invention, the irradiation amount of polarized ultraviolet light irradiated on the coating and the heating temperature in the heat treatment are optimized. Thereby, the efficient introduction of anisotropy into the coating can be achieved. The coating used in the present invention is introduced with high efficiency into anisotropy, as the irradiation amount of the best polarized ultraviolet light, it is the irradiation amount of the polarized ultraviolet light when the amount of the photosensitive group in the coating produces the photocrosslinking reaction or the photoisomerization reaction or the photoFries rearrangement reaction reaches the best. If the result of the coating used in the present invention irradiating the polarized ultraviolet light is that the photosensitive group of the main chain of the photocrosslinking reaction or the photoisomerization reaction or the photoFries rearrangement reaction is few, then it does not reach the sufficient photoreaction amount. In this case, even if heating is added later, sufficient self-organization will not be carried out. On the other hand, in the coating used in the present invention, if the structure having a photo-crosslinkable group is irradiated with polarized ultraviolet light, and the result is that the photosensitive group of the main chain undergoing a crosslinking reaction is excessive, excessive crosslinking reaction will occur between the main chains. In this case, the resulting film becomes rigid, and sometimes it will hinder the subsequent self-organization by heating. In addition, in the coating used in the present invention, if the structure having a photo-Fries rearrangement group is irradiated with polarized ultraviolet light, and the result is that there are many photo-Fries rearrangement groups in the polymer film, the anisotropy obtained by the polarized ultraviolet light is small, and since it will hinder the subsequent self-organization by heating, it will cause a decrease in the stability of the liquid crystal alignment. Furthermore, if a structure having a photo-Fries rearrangement group is irradiated with polarized ultraviolet light, if the irradiation amount of ultraviolet light is too much, the main chain polymer will be photodecomposed, which will hinder the subsequent self-organization by heating, or the electrical properties of the resulting liquid crystal alignment film will be deteriorated, and the quality of the liquid crystal display element will be reduced. [0089] Therefore, in the coating used in the present invention, the optimal amount of the photosensitive group of the main chain to undergo photocrosslinking reaction or photoisomerization reaction, or photo-Fries rearrangement reaction by irradiation with polarized ultraviolet light is preferably 0.1 mol% to 90 mol% of the photosensitive group possessed by the main chain polymer film, and more preferably 0.1 mol% to 80 mol%. By setting the amount of the photosensitive group of the main chain that undergoes photoreaction within such a range, the self-organization can be efficiently carried out by the subsequent heat treatment, and anisotropy can be efficiently formed in the film. [0090] In the coating used in the method of the present invention, the amount of photocrosslinking reaction or photoisomerization reaction or photoFries rearrangement reaction of the photosensitive group in the main chain of the main chain polymer film can be optimized by optimizing the irradiation amount of polarized ultraviolet light. In addition, the subsequent heat treatment can achieve efficient introduction of anisotropy into the coating used in the present invention. In this case, the amount of suitable polarized ultraviolet light can be evaluated based on the ultraviolet absorption of the coating used in the present invention. That is, for the coating used in the present invention, the ultraviolet absorption in the direction parallel to the polarization direction of the polarized ultraviolet after irradiation with polarized ultraviolet light, and the ultraviolet absorption in the vertical direction are measured respectively. From the measurement result of ultraviolet absorption, the difference (ΔA) between the ultraviolet absorbance in the direction parallel to the polarization direction of the polarized ultraviolet in the coating and the ultraviolet absorbance in the vertical direction is evaluated. In addition, the maximum value (ΔAmax) of ΔA realized in the coating used in the present invention and the irradiation amount of the polarized ultraviolet that realizes the maximum value are obtained. In the manufacturing method of the present invention, the irradiation amount of the polarized ultraviolet that realizes the ΔAmax is used as a benchmark, and the preferred amount of the polarized ultraviolet irradiated in the manufacture of the liquid crystal alignment film can be determined. [0092] Based on the above, in the manufacturing method of the present invention, in order to achieve the introduction of highly efficient anisotropy into the coating, the temperature range in which the main chain polymer can impart excellent liquid crystal alignment stability is used as a benchmark to determine the appropriate heating temperature as mentioned above. Therefore, it is better to set the heating temperature after polarized ultraviolet irradiation to 100°C~300°C, and more preferably to 150°C~250°C. Thereby, greater anisotropy can be imparted to the coating used in the present invention. [0093] Thereby, the liquid crystal display element provided by the present invention will exhibit high reliability against external stresses such as light or heat. [0094] As described above, the substrate for a lateral electric field driven liquid crystal display element manufactured using the composition of the present invention or the lateral electric field driven liquid crystal display element having the substrate can be used in large-screen and high-precision liquid crystal televisions, etc., because of its excellent reliability. In addition, the liquid crystal alignment film manufactured by the method of the present invention can also be used in a variable phase shifter using liquid crystal, because of its excellent liquid crystal alignment stability and reliability. The variable phase shifter can be used in, for example, an antenna that can change the resonance frequency. [Example] [0095] The abbreviations used in the embodiment are as follows. NMP: N-methyl-2-pyrrolidone BCS: Butyl cellulose solvent DA-1: The following structural formula (DA-1) DA-2: The following structural formula (DA-2) DA-3: The following structural formula (DA-3) DA-4: The following structural formula (DA-4) DA-5: The following structural formula (DA-5) DA-6: The following structural formula (DA-6) DA-7: The following structural formula (DA-7) DA-8: The following structural formula (DA-8) DA-9: The following structural formula (DA-9) DA-10: The following structural formula (DA-10) DA-11: The following structural formula (DA-11) DA-12: The following structural formula (DA-12) DA-13: The following structural formula (DA-13) DA-14: The following structural formula (DA-14) DA-15: The following structural formula (DA-15) CA-1: The following structural formula (CA-1) CA-2: The following structural formula (CA-2) [0097] [0098] [0099] <Determination of viscosity> In the synthesis examples, the viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a conical rotor TE-1 (1°34', R24), and a temperature of 25°C. [0100] (Synthesis Example 1) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.88 g (7.0 mmol) of DA-1 and 1.61 g (7.0 mmol) of DA-7 were weighed, 30.6 g of NMP was added, and the mixture was dissolved while stirring while nitrogen was introduced. While stirring the diamine solution under water cooling, 2.61 g (13.3 mmol) of CA-1 was added, and then 13.1 g of NMP was added, and the mixture was stirred at 23°C for 3 hours under a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25°C was 263 mPa·s. 14.5 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.6 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-1). [0101] (Synthesis Example 2) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.88 g (7.0 mmol) of DA-1 and 1.71 g (7.0 mmol) of DA-8 were weighed, 31.1 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.57 g (13.1 mmol) of CA-1 was added, and then 13.3 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamine solution. The viscosity of the polyamine solution at a temperature of 25° C. was 326 mPa·s. 14.9 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 13.0 g of NMP and 12.0 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-2). [0102] (Synthesis Example 3) 1.74 g (6.5 mmol) of DA-1 and 1.68 g (6.5 mmol) of DA-9 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 29.6 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.36 g (12.0 mmol) of CA-1 was added, and then 12.7 g of NMP was added, and the mixture was stirred at 23°C for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25°C was 261 mPa·s. 14.5 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.6 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-3). [0103] (Synthesis Example 4) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.74 g (6.5 mmol) of DA-1 and 1.77 g (6.5 mmol) of DA-10 were weighed, 30.1 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.37 g (12.1 mmol) of CA-1 was added, and then 12.9 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at a temperature of 25° C. was 302 mPa·s. 14.6 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 12.7 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-4). [0104] (Synthesis Example 5) 1.74 g (6.5 mmol) of DA-1 and 1.86 g (6.5 mmol) of DA-11 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 30.5 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.35 g (12.0 mmol) of CA-1 was added, and then 13.1 g of NMP was added, and the mixture was stirred at 23°C for 3 hours under a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25°C was 294 mPa·s. 14.6 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-5). [0105] (Synthesis Example 6) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.74 g (6.5 mmol) of DA-1 and 1.95 g (6.5 mmol) of DA-12 were weighed, 31.0 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.37 g (12.1 mmol) of CA-1 was added, and then 13.3 g of NMP was added, and stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at a temperature of 25° C. was 304 mPa·s. 14.6 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-6). [0106] (Synthesis Example 7) 1.61 g (6.0 mmol) of DA-1 and 1.89 g (6.0 mmol) of DA-13 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 29.1 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.18 g (11.1 mmol) of CA-1 was added, and then 12.5 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25° C. was 305 mPa·s. 15.0 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 13.0 g of NMP and 12.0 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-7). [0107] (Synthesis Example 8) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.78 g (7.0 mmol) of DA-2 and 1.71 g (7.0 mmol) of DA-8 were weighed, 31.0 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.55 g (13.0 mmol) of CA-1 was added, and then 13.3 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamine solution. The viscosity of the polyamine solution at a temperature of 25° C. was 334 mPa·s. 14.9 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 13.0 g of NMP and 12.0 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-8). [0108] (Synthesis Example 9) 1.88 g (7.0 mmol) of DA-3 and 1.71 g (7.0 mmol) of DA-8 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 31.5 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.55 g (13.0 mmol) of CA-1 was added, and then 13.5 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25° C. was 315 mPa·s. 14.6 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-9). [0109] (Synthesis Example 10) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.74 g (6.5 mmol) of DA-1 and 1.59 g (6.5 mmol) of DA-8 were weighed, 29.6 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 1.86 g (9.5 mmol) of CA-1 was added, and the mixture was stirred at 23° C. for 30 minutes in a nitrogen environment. Thereafter, 0.57 g (2.6 mmol) of CA-2 was added, and 12.7 g of NMP was further added, and the mixture was stirred at 50° C. for 15 hours in a nitrogen environment to obtain a solution of polyamide. The viscosity of the polyamide solution at a temperature of 25° C. was 308 mPa·s. 14.6 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-10). [0110] (Synthesis Example 11) 0.80 g (3.5 mmol) of DA-4 and 2.57 g (10.5 mmol) of DA-8 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 30.4 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.55 g (13.0 mmol) of CA-1 was added, and then 13.0 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25° C. was 324 mPa·s. 14.9 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 13.0 g of NMP and 12.0 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-11). [0111] (Synthesis Example 12) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.13 g (3.3 mmol) of DA-5 and 2.38 g (9.8 mmol) of DA-8 were weighed, 30.2 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.37 g (12.1 mmol) of CA-1 was added, and then 12.9 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamine solution. The viscosity of the polyamine solution at a temperature of 25° C. was 298 mPa·s. 14.6 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-12). [0112] (Synthesis Example 13) 0.74 g (3.5 mmol) of DA-6 and 2.57 g (10.5 mmol) of DA-8 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 30.1 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.55 g (13.0 mmol) of CA-1 was added, and then 12.9 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25° C. was 337 mPa·s. 14.6 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (A-13). [0113] (Comparative Synthesis Example 1) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 3.49 g (13.0 mmol) of DA-1 was weighed, 29.9 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.33 g (11.9 mmol) of CA-1 was added, and then 12.8 g of NMP was added, and stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at a temperature of 25° C. was 357 mPa·s. 14.9 g of the polyamine solution was separated and placed in a 100 mL conical flask with a stirrer, 13.0 g of NMP and 12.0 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (B-1). [0114] (Comparative Synthesis Example 2) 1.88 g (7.0 mmol) of DA-1 and 1.40 g (7.0 mmol) of DA-14 were weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 30.1 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.58 g (13.2 mmol) of CA-1 was added, and then 12.9 g of NMP was added, and the mixture was stirred at 23°C for 3 hours in a nitrogen environment to obtain a polyamide solution. The viscosity of the polyamide solution at 25°C was 288 mPa·s. 14.6 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (B-2). [0115] (Comparative Synthesis Example 3) In a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 1.88 g (7.0 mmol) of DA-1 and 1.39 g (7.0 mmol) of DA-15 were weighed, 30.0 g of NMP was added, and nitrogen was introduced while stirring to dissolve. While stirring the diamine solution under water cooling, 2.59 g (13.2 mmol) of CA-1 was added, and then 12.9 g of NMP was added, and the mixture was stirred at 23° C. for 3 hours in a nitrogen environment to obtain a polyamine solution. The viscosity of the polyamine solution at a temperature of 25° C. was 279 mPa·s. 14.6 g of the polyamine solution was separated and placed in a 100 mL Erlenmeyer flask with a stirrer, 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (B-3). [0116] (Comparative Synthesis Example 4) 3.20 g (14.0 mmol) of DA-4 was weighed in a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 29.4 g of NMP was added, and nitrogen was introduced while stirring to dissolve the mixture. While stirring the diamine solution under water cooling, 2.53 g (12.9 mmol) of CA-1 was added, and then 12.6 g of NMP was added, and the mixture was stirred at 23°C for 3 hours in a nitrogen environment to obtain a solution of polyamide. The viscosity of the polyamide solution at 25°C is 364 mPa·s. 14.6 g of the polyamide solution was separated into a 100 mL Erlenmeyer flask with a stirrer, and 12.6 g of NMP and 11.7 g of BCS were added, and the mixture was stirred for 2 hours using a magnetic stirrer to obtain a liquid crystal alignment agent (B-4). [0117] <Preparation of liquid crystal cells for evaluating liquid crystal alignment> The following is a method for preparing liquid crystal cells for evaluating liquid crystal alignment. A liquid crystal cell having a structure of a liquid crystal display element with an FFS method is produced. First, a substrate with electrodes is prepared. The substrate is a glass substrate with a size of 30 mm × 35 mm and a thickness of 0.7 mm. An IZO electrode constituting a counter electrode is formed entirely on the substrate as the first layer. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by a CVD method is formed as the second layer. The second layer of SiN film has a film thickness of 500 nm and acts as an interlayer insulating film. On the second layer of SiN film, a comb-shaped pixel electrode formed by patterning the IZO film is arranged as the third layer to form two pixels, the first pixel and the second pixel. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer. The pixel electrode of the third layer is the same as the figure described in the patent publication 2014-77845 (Japanese Patent Gazette), and has a comb-like shape composed of a plurality of "く"-shaped electrode elements with a bent center portion. The width of each electrode element is 3μm in the width direction, and the interval between the electrode elements is 6μm. The pixel electrode forming each pixel is composed of a plurality of electrode elements arranged in the shape of a "く" character with a curved center portion, so the shape of each pixel is not a rectangle, but has a shape similar to the bold "く" character that is curved in the center like the electrode elements. Moreover, each pixel is divided into upper and lower parts with the curved portion in the center as the boundary, and has a first area on the upper side of the curved portion and a second area on the lower side. When comparing the first area and the second area of each pixel, the formation direction of the electrode elements constituting such pixel electrodes is different. That is, when the direction of the line segment of the polarization plane of the polarized ultraviolet light to be described later projected onto the substrate is used as a reference, in the first area of the pixel, the electrode element of the pixel electrode is formed in a manner to form an angle of +10° (clockwise), and in the second area of the pixel, the electrode element of the pixel electrode is formed in a manner to form an angle of -10° (clockwise). In other words, in the first area and the second area of each pixel, the directions of the rotation action (in-plane rotation) of the liquid crystal induced by the voltage applied between the pixel electrode and the counter electrode in the substrate surface are opposite to each other. [0118] Next, after filtering the liquid crystal alignment agent obtained in the synthesis example and the comparative synthesis example with a 1.0 μm filter, it is applied to the prepared substrate with electrodes by rotation coating. Next, it is dried on a heating plate set at 70° C. for 90 seconds. Next, using an exposure device made by Ushio Electric Co., Ltd.: APL-L050121S1S-APW01, the substrate is irradiated with linear polarized ultraviolet light from a vertical direction through a wavelength selection filter and a polarizing plate. At this time, the direction of the line segment of the polarization plane of the polarized ultraviolet light projected on the substrate is set in a manner that the polarization plane direction becomes a direction inclined by 10° relative to the third layer of IZO comb electrode. Next, the substrate was fired for 30 minutes in an IR (infrared) oven set at 230°C to obtain a substrate with a polyimide liquid crystal alignment film having a film thickness of 100 nm and subjected to an alignment treatment. In addition, as an opposing substrate, a glass substrate having a columnar spacer with a height of 4 μm formed therein with an ITO electrode was subjected to the same method as described above to obtain a substrate with a polyimide liquid crystal alignment film subjected to an alignment treatment. The two substrates with liquid crystal alignment films were grouped as a set, and a sealant was printed on one substrate in the form of retaining a liquid crystal injection port, and the other substrate was bonded and pressed in a manner such that the liquid crystal alignment film surfaces were opposite to each other and the direction of the line segment of the polarization plane of the polarized ultraviolet light projected onto the substrate was parallel. Afterwards, the sealant is cured and an empty cell with a cell pitch of 4 μm is produced. Liquid crystal MLC-7026-100 (negative liquid crystal produced by Merck) is injected into the empty cell by the reduced pressure injection method, and the injection port is sealed to obtain a liquid crystal cell of the FFS method. Afterwards, the obtained liquid crystal cell is heated at 120°C for 30 minutes, and is placed at 23°C overnight before being used for the evaluation of the liquid crystal alignment. [0119] <Evaluation of Liquid Crystal Alignment> Using the liquid crystal cell, an AC voltage of 16 VPP at a frequency of 30 Hz is applied for 168 hours in a constant temperature environment of 70°C. Afterwards, the pixel electrode and the opposite electrode of the liquid crystal cell are short-circuited, and the state is maintained at 23°C overnight. After placement, the liquid crystal cell is set between two polarizing plates arranged in a manner that the polarization axis is perpendicular, and the backlight source is turned on without an external voltage, and the configuration angle of the liquid crystal cell is adjusted in a manner that the brightness of the transmitted light is minimized. In addition, the rotation angle of the liquid crystal cell from the darkest angle of the second area of the first pixel to the darkest angle of the first area is calculated as angle Δ. Similarly for the second pixel, the second area is compared with the first area and the same angle Δ is calculated. In addition, the average value of the angle Δ values of the first pixel and the second pixel is calculated as the angle Δ of the liquid crystal cell. If the value of the angle Δ of the liquid crystal cell is less than 1.5°, it is defined as "good", and if the value of the angle Δ is greater than 1.5°, it is defined as "poor" for evaluation. [0120] <Preparation of liquid crystal cells for voltage retention ratio evaluation> Using a glass substrate with an ITO electrode, a liquid crystal cell for voltage retention ratio measurement is prepared according to the same procedure as the preparation of the liquid crystal cell for liquid crystal orientation evaluation described above, except that 4μm bead spacers are scattered on the liquid crystal alignment film surface on one substrate before printing the sealant. [0121] <Evaluation of voltage retention ratio> The voltage retention ratio is evaluated using the liquid crystal cell. Specifically, an AC voltage of 2VPP for 60μ seconds is applied to the liquid crystal cell obtained by the above method at a temperature of 70°C, and the voltage is measured after 167m seconds. The degree to which the voltage can be maintained is calculated as the voltage retention ratio (also called VHR). The measurement was performed using a voltage holding ratio measuring device (VHR-1, manufactured by TOYO Corporation) with the settings of Voltage: ±1V, Pulse Width: 60μs, and Flame Period: 167ms. If the voltage holding ratio of the liquid crystal cell is 80% or more, it is defined as "good", and if the voltage holding ratio is less than 80%, it is defined as "poor" for evaluation. [0122] (Example 1) Using the liquid crystal alignment agent (A-1) obtained in Synthesis Example 1, two types of liquid crystal cells as described above were prepared. Irradiation with polarized ultraviolet light was performed using a high-pressure mercury lamp through a wavelength selection filter: 240LCF, and a 254nm type polarizing plate. The amount of polarized ultraviolet light irradiation was measured by using an illuminometer UVD-S254SB manufactured by Ushio Electric Co., Ltd., and the amount of light was changed in the range of 200~1500mJ/ ^cm2 at a wavelength of 254nm, thereby producing more than three liquid crystal cells with different amounts of polarized ultraviolet light irradiation. The results of evaluating the liquid crystal alignment of these liquid crystal cells showed that the polarized ultraviolet light irradiation with the best angle Δ was 900mJ/ ^cm2 , and the angle Δ was good at 1.06°. In addition, the voltage retention rate of the liquid crystal cells produced with the same polarized ultraviolet light irradiation was evaluated, and the voltage retention rate was good at 85.3%. [0123] (Examples 2 to 12) Except for using the liquid crystal alignment agents obtained in Synthesis Examples 2 to 12, the same method as in Example 1 was used to evaluate the liquid crystal alignment and voltage holding ratio. [0124] (Example 13) Except for using the liquid crystal alignment agent (A-13) obtained in Synthesis Example 13, and using a metal halogen lamp through a wavelength selection filter: i-wide BPF, and a 313 to 365 nm type polarizing plate to irradiate polarized ultraviolet light, and changing the irradiation amount of polarized ultraviolet light within the range of 1000 to 4000 mJ/ ^cm2 at a wavelength of 365 nm, the same method as in Example 1 was used to evaluate the liquid crystal alignment and voltage holding ratio. [0125] (Comparative Examples 1-4) In addition to using the liquid crystal alignment agents obtained in Comparative Synthesis Examples 1-4, the same method as in Example 1 was used to evaluate the liquid crystal alignment and voltage retention. [0126] Table 1 shows the polarized ultraviolet irradiation wavelength, the polarized ultraviolet irradiation amount with the best angle Δ, the evaluation results of the liquid crystal alignment, and the evaluation results of the voltage retention when using the liquid crystal alignment agents obtained in the Synthesis Examples and the Comparative Synthesis Examples. [0127] As shown in Table 1, in Examples 1 to 13, the difference (angle Δ) of the orientation angle before and after AC driving is less than 1.5°, which is good, and the VHR is also more than 80% and exhibits good characteristics, so all have good afterimage characteristics, so the display quality of the liquid crystal display element is improved to be excellent. On the other hand, in Comparative Examples 1 to 4, it is not possible to confirm the characteristics of both angle Δ and voltage holding rate. In this way, the liquid crystal display element manufactured by the method of the present invention can be confirmed to exhibit very excellent afterimage characteristics. [Industrial Applicability] [0129] The substrate for a lateral electric field driven liquid crystal display element manufactured using the composition of the present invention or the lateral electric field driven liquid crystal display element having the substrate can be used in large-screen and high-precision liquid crystal televisions, etc., because of its excellent reliability. In addition, the liquid crystal alignment film manufactured by the method of the present invention can also be used in a variable phase shifter using liquid crystal, because of its excellent liquid crystal alignment stability and reliability. The variable phase shifter can be used in, for example, an antenna capable of changing the resonance frequency, etc.

Claims (12)

A liquid crystal alignment agent, characterized by comprising: a polymer obtained from a diamine component and an organic solvent, wherein the diamine component comprises: at least one diamine selected from diamines having structures represented by the following formulas (1) to (3), and a diamine having a structure represented by the following formula (4) (wherein W and X are independently an aromatic ring having 6 to 14 carbon atoms, Y is an oxygen atom or a sulfur atom, Z is a divalent organic group consisting only of an oxygen atom and an alkylene group, _R1 to _R7 are independently a hydrogen atom or a monovalent organic group, and m, n, o, p and q are independently an integer of 0 to 4), but X is not an aromatic ring having 6 carbon atoms, and the total number of oxygen atoms and carbon atoms in Z is not 7 at the same time.

The diamine having the structure represented by the above formula (4) is a diamine represented by any one of the following formulas:

As in claim 1, the liquid crystal alignment agent, wherein the aforementioned polymer is at least one polymer selected from the group consisting of a polyimide precursor of a polymer of the aforementioned diamine component and tetracarboxylic dianhydride and a polyimide of the imide compound. The liquid crystal alignment agent of claim 1 or 2, wherein the polyimide precursor comprises: a structural unit represented by the following formula (5) (in the above formula (5), _X1 is a tetravalent organic group derived from a tetracarboxylic acid derivative, _Y1 is a divalent organic group derived from a diamine having a structure selected from formulas (1) to (3), and _R11 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), and a structural unit represented by the following formula (6) (in the above formula (6), _X2 is a tetravalent organic group derived from a tetracarboxylic acid derivative, _Y2 is a divalent organic group derived from a diamine having a structure represented by formula (4), and _R12 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms),

The liquid crystal aligner of claim 3, wherein in the above formula (5) and formula (6), the structure of _X1 and the structure of _X2 are independently selected from at least one of the following structures:

As in claim 3, the liquid crystal alignment agent contains more than 10 mol% of polymers having structural units represented by the aforementioned formula (5) and formula (6) relative to the total polymers contained in the liquid crystal alignment agent. As in claim 4, the liquid crystal alignment agent contains more than 10 mol% of polymers having structural units represented by the aforementioned formula (5) and formula (6) relative to the total polymers contained in the liquid crystal alignment agent. As in claim 1, the liquid crystal alignment agent contains at least one selected from the group consisting of 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether in the above-mentioned organic solvent. A method for manufacturing a substrate having the following liquid crystal alignment film, characterized in that the liquid crystal alignment film for a lateral electric field driven liquid crystal display element endowed with alignment control capability is obtained by the following steps, comprising: [I] a step of coating a composition of any one of claims 1 to 7 on a substrate having a lateral electric field driven conductive film to form a coating; [II] a step of irradiating the coating obtained in [I] with polarized ultraviolet light; and [III] a step of heating the coating obtained in [II]. A substrate characterized by having a liquid crystal alignment film for a lateral electric field driven liquid crystal display element manufactured by the method of claim 8. A lateral electric field driven liquid crystal display element, characterized by having a substrate as claimed in claim 9. A method for manufacturing a liquid crystal display element, characterized in that the method comprises: a step of preparing a substrate (first substrate) of claim 9, a step of obtaining a second substrate, and a step of obtaining a liquid crystal display element, thereby obtaining a lateral electric field driven liquid crystal display element; the liquid crystal alignment film of the second substrate is obtained by the following steps to obtain a liquid crystal alignment film endowed with alignment control capability, comprising: [I'] preparing the substrate of claim 1 to claim 7 [II’] a step of irradiating the coating obtained by [I’] with polarized ultraviolet rays, and [III’] a step of heating the coating obtained by [II’]; the step of obtaining a liquid crystal display element is [IV] arranging the first and second substrates opposite to each other in such a way that the liquid crystal alignment films of the first and second substrates are opposed to each other via liquid crystal. A lateral electric field driven liquid crystal display element is manufactured by the method of claim 11.