Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element

Abstract

To provide a liquid crystal orientation membrane having excellent liquid crystal orientation, mechanical strength, adhesion to a substance and high temperature and humidity resistance.SOLUTION: A liquid crystal orientation agent includes a polyimide including a structural unit (I) having a partial structure represented by a formula (1) and a structural unit (II) (excluding the structural unit (I)) having a partial structure formed by replacing, under the condition not next to each other, an alkylene structure with 5 or more carbons or at least one methylene group in the alkylene structure with 5 or more carbons by a same or different groups selected from a group consisting of -COO-, -OCO-, -O-, -CO-NR4-, -NR4-CO-, -NR4- and -CO-. In the formula (1), Ar1 and Ar2 are divalent aromatic ring group, X1 and X2 are -NR2-, -O-, -S-, *1-NR2-CO- or *1-O-CO-, "*1" represents an atomic bond with Ar1 or Ar2, and R1 is an alkanediyl group with 2 or more carbons.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal device. [Background technology]

[0002] Liquid crystal elements are widely used in televisions, mobile devices, various monitors, etc. As their applications become more diverse, there is a demand for even higher quality liquid crystal elements. Therefore, progress has been made in improving the liquid crystal element drive system and element structure, as well as improving the liquid crystal alignment film, which is one of the components of liquid crystal elements (see, for example, Patent Document 1 and Patent Document 2).

[0003] Patent Document 1 discloses that a liquid crystal alignment film is formed using a polyamic acid having a partial structure in which a urea bond and an alkylene structure are bonded in the main chain, thereby improving liquid crystal alignment properties, transparency, and rubbing resistance. Patent Document 2 discloses that a liquid crystal alignment film is obtained that has little afterimage generation, high transmittance, contrast, voltage retention properties, and good reworkability by blending a polymer having a urea bond or an amino group or the like in the main chain with a polymer having a carbazole structure in the main chain. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-98887 [Patent Document 2] International Publication No. 2020 / 218331 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to further improve the quality of liquid crystal devices, the present inventors have conducted research and discovered that by producing a polyamic acid using a diamine having a partial structure in which an aromatic ring, a specific heteroatom-containing group, and a short-chain alkylene structure are bonded, a liquid crystal alignment film exhibiting good liquid crystal alignment properties can be obtained whether the liquid crystal alignment film is produced by rubbing or photo-alignment. On the other hand, imidization of polyamic acid can result in a decrease in the mechanical properties of the liquid crystal alignment film and a decrease in adhesion of the liquid crystal alignment film to the substrate. When producing a liquid crystal alignment film by rubbing or to prevent a decrease in yield, films formed using a liquid crystal aligning agent must have high mechanical strength.

[0006] In recent years, as liquid crystal elements have become more versatile, they are expected to be used in a variety of environments. Therefore, liquid crystal elements are also required to have excellent resistance to high temperatures and high humidity. However, it is difficult to simultaneously satisfy multiple properties such as liquid crystal alignment, mechanical strength, adhesion to the substrate, and resistance to high temperatures and high humidity, and there is room for further improvement in liquid crystal alignment films.

[0007] The present invention has been made in view of the above circumstances, and its main object is to provide a liquid crystal aligning agent that can give a liquid crystal alignment film that is excellent in liquid crystal alignment property, mechanical strength, adhesion to a substrate, and high-temperature and high-humidity resistance. [Means for solving the problem]

[0008] The present invention employs the following means to solve the above problems.

[0009] <1> The structural unit (I) having a partial structure represented by the following formula (1) and the alkylene structure having 5 or more carbon atoms or at least one methylene group of the alkylene structure having 5 or more carbon atoms are not adjacent to each other, and are -COO-, -OCO-, -O-, -CO-NR 4 -, -NR 4 -CO-, -NR 4 - and -CO- are substituted with the same or different groups selected from the group consisting of4 is a hydrogen atom or a monovalent organic group, and a polyimide containing a structural unit (II) having the structural unit (I) (excluding the structural unit (I)). [ka] (In formula (1), Ar 1 and Ar 2 are each independently a divalent aromatic ring group. 1 and X 2 are each independently -NR 2 -, -O-, -S-, * 1 -NR 2 -CO- or * 1 -O-CO-. 1 " is Ar 1 or Ar 2 R represents a bond that is bonded to 1 is an alkanediyl group having two or more carbon atoms or an alkanediyl group having two or more carbon atoms with -NR 3 -, -O-, -S-, -CO-NR 4 -, -NR 3 R is a divalent group containing -CO-, -COO-, or -OCO-. 2 and R 3 are each independently a hydrogen atom or a monovalent organic group. "*" represents a bond.

[0010] <2> the above <1> A liquid crystal alignment film formed using the liquid crystal alignment agent of the above. <3> the above <2> A liquid crystal element comprising a liquid crystal alignment film. [Effects of the Invention]

[0011] According to the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal alignment film that is excellent in liquid crystal alignment property, mechanical strength, adhesion to a substrate, and resistance to high temperature and high humidity. DETAILED DESCRIPTION OF THE INVENTION

[0012] Matters related to the embodiments of the present disclosure will be described in detail below. In this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain hydrocarbon group" refers to a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, the group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, the group does not necessarily have to be composed solely of an alicyclic hydrocarbon structure, and may also contain a chain structure as part of the ring structure. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, the group does not necessarily have to be composed solely of an aromatic ring structure, and may contain a chain structure or an alicyclic hydrocarbon structure as part of the ring structure. The term "main chain" of a polymer refers to the longest "trunk" portion of the atomic chain of the polymer. The term "side chain" of a polymer refers to a portion branched from the "trunk" of the polymer. The term "organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0013] Liquid crystal alignment agent The liquid crystal aligning agent of the present disclosure contains a polyimide (hereinafter also referred to as "polyimide (P)") containing the following structural unit (I) and structural unit (II). Structural unit (I): a structural unit having a partial structure (A) represented by the following formula (1): [ka] (In formula (1), Ar 1 and Ar 2 are each independently a divalent aromatic ring group. 1 and X 2 are each independently -NR 2 -, -O-, -S-, * 1 -NR 2 -CO- or * 1 -O-CO-. 1 " is Ar 1 or Ar 2 R represents a bond that is bonded to 1is an alkanediyl group having two or more carbon atoms or an alkanediyl group having two or more carbon atoms with -NR 3 -, -O-, -S-, -CO-NR 4 -, -NR 3 R is a divalent group containing -CO-, -COO-, or -OCO-. 2 and R 3 are each independently a hydrogen atom or a monovalent organic group. "*" represents a bond. Structural unit (II): an alkylene structure having 5 or more carbon atoms or at least one methylene group in the alkylene structure having 5 or more carbon atoms is not adjacent to another methylene group, such as -COO-, -OCO-, -O-, or -CO-NR 4 -, -NR 4 -CO-, -NR 4 A structural unit (excluding the structural unit (I)) having a partial structure (B) in which R is replaced by the same or different groups selected from the group consisting of - and -CO-. 4 is a hydrogen atom or a monovalent organic group. The polyimide (P) contained in the liquid crystal aligning agent of the present disclosure and other components that may be optionally blended will be described in detail below.

[0014] <Polyimide (P)> Structural Unit (I) In the above formula (1), Ar 1 and Ar 2 The divalent aromatic ring group represented by the formula (I) is a group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring. Examples of the divalent aromatic ring group include a substituted or unsubstituted divalent aromatic hydrocarbon group and a substituted or unsubstituted divalent aromatic heterocyclic group. Examples of the aromatic heterocyclic group include a nitrogen-containing aromatic heterocyclic group, an oxygen-containing aromatic heterocyclic group, and a sulfur-containing aromatic heterocyclic group. Among these, a nitrogen-containing aromatic heterocyclic group is preferred. In addition, Ar 1 and Ar 2 may have a substituent in the aromatic ring portion, and examples of the substituent include an alkyl group having 1 to 3 carbon atoms, a halogen atom, and a cyano group.

[0015] Ar 1, Ar 2 Specific examples of the divalent aromatic hydrocarbon group include a divalent group having a benzene ring, a biphenyl ring, a naphthalene ring, or an anthracene ring; a divalent nitrogen-containing aromatic heterocyclic group includes a divalent group having a pyridine ring, a pyrimidine ring, a pyridazine ring, or a pyrazine ring; a divalent oxygen-containing aromatic heterocyclic group includes a divalent group having a furan ring; and a divalent sulfur-containing aromatic heterocyclic group includes a divalent group having a thiophene ring. From the viewpoint of improving the mechanical strength and increasing the transmittance by increasing the density of the liquid crystal alignment film, Ar 1 and Ar 2 The divalent aromatic ring group is preferably a substituted or unsubstituted divalent aromatic hydrocarbon group or a substituted or unsubstituted divalent nitrogen-containing aromatic heterocyclic group, more preferably a substituted or unsubstituted phenylene group, biphenylene group, or pyridinediyl group. A substituted or unsubstituted phenylene group or biphenylene group is even more preferred in terms of a higher effect of improving the film strength of the liquid crystal alignment film. The substituent is preferably a methyl group or a halogen atom.

[0016] X 1 and X 2 The group represented by -NR 2 -or* 1 -NR 2 -CO-, R 2 The monovalent organic group represented by the formula (I) is preferably an alkyl group having 1 to 5 carbon atoms or a leaving group which is left by at least one of heat and light, and more preferably an alkyl group having 1 to 5 carbon atoms or a thermally leaving group. 2 From the viewpoint of eliminating R and simplifying the process, the thermally eliminable group is preferably a group that decomposes at a temperature of 120 to 300°C and is replaced with a hydrogen atom. Specifically, a tert-butoxycarbonyl group (Boc group) or a 9-fluorenylmethoxycarbonyl group is preferred, and a tert-butoxycarbonyl group is particularly preferred. 2 is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a thermally detachable group.

[0017] X1 and X 2 is preferred in that it can improve the liquid crystal alignment property, and -NR 2 It is preferably -, -O- or -S-.

[0018] X is a liquid crystal display device with little change in retardation even when irradiated with a backlight for a long time, and with good liquid crystal alignment. 1 and X 2 Ga-NR 2 -or* 1 -NR 2 -CO-, Ar 1 and Ar 2 At least one of Ar is preferably a substituted or unsubstituted divalent nitrogen-containing aromatic heterocyclic group, 1 and Ar 2 and Ar are preferably both substituted or unsubstituted divalent nitrogen-containing aromatic heterocyclic groups, 1 and Ar 2 It is more preferable that both of X and X are substituted or unsubstituted pyridinediyl groups. 1 and X 2 is -O- or -S-, Ar 1 and Ar 2 At least one of Ar is preferably a substituted or unsubstituted divalent aromatic hydrocarbon group, 1 and Ar 2 and Ar are preferably both substituted or unsubstituted divalent aromatic hydrocarbon groups, 1 and Ar 2 It is more preferable that both of the groups are substituted or unsubstituted phenylene groups.

[0019] R 1 The alkanediyl group having 2 or more carbon atoms, represented by the following formula (I) is preferably linear. The number of carbon atoms in the alkanediyl group is preferably 2 to 8, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3, in order to improve the balance between adhesion to the substrate and film strength.

[0020] R 1The group represented by the formula (I) has a carbon-carbon bond of an alkanediyl group having two or more carbon atoms, and the carbon-carbon bond of the alkanediyl group is -NR 3 -, -O-, -S-, -CO-NR 3 -, -NR 3 In the case of a divalent group containing -CO-, -COO-, or -OCO-, the alkanediyl group having 2 or more carbon atoms is preferably linear. The number of carbon atoms in the alkanediyl group is preferably 2 to 7, more preferably 2 to 5, and even more preferably 2 or 3, in order to improve the balance between adhesion to the substrate and film strength. R 3 Specific and preferred examples of R 2 The explanation in paragraph 1 applies.

[0021] The rubbing treatment can promote the stretching of polymer molecular chains, and the photo-alignment treatment can promote the rearrangement of polymer molecular chains by heat treatment after exposure. 1 Among the above, an alkanediyl group having 2 or more carbon atoms is preferable, a linear alkanediyl group having 2 to 8 carbon atoms is more preferable, a linear alkanediyl group having 2 to 6 carbon atoms is even more preferable, a linear alkanediyl group having 2 to 4 carbon atoms is still more preferable, and a linear alkanediyl group having 2 or 3 carbon atoms is particularly preferable.

[0022] Specific examples of the partial structure (A) represented by the above formula (1) include partial structures represented by the following formulas (1-1) to (1-24). [ka] [ka] [ka] [ka] (In formulas (1-1) to (1-24), "*" represents a bond.)

[0023] In the polyimide (P), the content of the structural unit (I) is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units derived from the monomers constituting the polyimide (P). The content of the structural unit (I) is preferably 49 mol% or less, more preferably 45 mol% or less, and even more preferably 40 mol% or less, based on all structural units derived from the monomers constituting the polyimide (P). A content of the structural unit (I) of 1 mol% or more is preferable because it can fully improve mechanical properties by introducing an aromatic ring-specific heteroatom-containing group-alkylene structure derived from the structural unit (I). A content of the structural unit (I) of 49 mol% or less is preferable because it can fully introduce a structural unit (II), i.e., a relatively long-chain unit derived from the structural unit (II), into the polyimide (P), thereby enhancing the effects of improving adhesion to substrates and resistance to high temperatures and high humidity. The structural unit (I) contained in the polyimide (P) may be of one type alone or two or more types.

[0024] Structural Units (II) The structural unit (II) is a structural unit having the partial structure (B). That is, the structural unit (II) is a structural unit (IIa) having an alkylene structure having 5 or more carbon atoms, or a structural unit (IIb) having an alkylene structure having 5 or more carbon atoms in which at least one methylene group is -COO-, -OCO-, -O-, or -CO-NR 4 -, -NR 4 -CO-, -NR 4 R is a structural unit (IIb) having a partial structure in which R is replaced with the same or different groups (hereinafter also referred to as "functional group F1") selected from the group consisting of - and -CO-. 4 is a hydrogen atom or a monovalent organic group. The structural unit (II) is a structural unit different from the structural unit (I).

[0025] The structural unit (II) is highly effective in improving the high temperature and high humidity resistance of a liquid crystal device, and is particularly effective in improving the high temperature and high humidity resistance of a liquid crystal device by forming an alkylene structure having 5 or more carbon atoms, or at least one methylene group in the alkylene structure having 5 or more carbon atoms, such as -COO-, -OCO-, -O-, or -CO-NR, provided that the methylene group is not adjacent to another methylene group. 4a -, -NR 4a -CO-, -NR 4 - and -CO- are substituted with the same or different groups selected from the group consisting of 4 is a hydrogen atom or a monovalent organic group. 4a is a monovalent thermally detachable group.

[0026] The alkylene structure of the structural unit (IIa) is preferably linear. The number of carbon atoms in the alkylene structure is preferably 6 or more, more preferably 7 or more, and even more preferably 8 or more, from the viewpoint of enhancing the effect of improving adhesion to the substrate. Furthermore, the number of carbon atoms in the alkylene structure is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less, from the viewpoint of suppressing a decrease in the mechanical strength of the film.

[0027] In the structural unit (IIb), from the viewpoint of improving the mechanical strength and adhesiveness of the film, at least one methylene group in the alkylene structure having 5 or more carbon atoms is -COO-* 2 , * 2 -OCO-, -O-, -CO-NR 4 -* 2 , * 2 -NR 4 -CO-, -NR 4 - and -CO- (However, "* 2" represents a bond bonded to a group (preferably an alkanediyl group) different from the aromatic ring group.) It is preferable that the structural unit (IIb) has a partial structure in which the alkylene structure is replaced by the same or different group selected from the group consisting of. In the structural unit (IIb), it is preferable that the alkylene structure is linear. From the viewpoint of improving adhesion to the substrate, the number of carbon atoms in the alkylene structure is preferably 6 or more, more preferably 7 or more, and even more preferably 8 or more. Furthermore, from the viewpoint of suppressing a decrease in the mechanical strength of the film, the number of carbon atoms in the alkylene structure is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less.

[0028] The number of functional groups F1 contained in the structural unit (IIb), i.e., the number of functional groups F1 substituting methylene groups in the alkylene structure having 5 or more carbon atoms, is not particularly limited, but is preferably 1 to 4, and more preferably 1 or 2. When the structural unit (II) has two or more functional groups F1, the two or more functional groups F1 are introduced into the structural unit (IIb) under the condition that they are not adjacent to each other.

[0029] R 4 The monovalent organic group represented by R 2 The monovalent organic groups exemplified in the description of R 2 For similar reasons, R 4 The monovalent organic group represented by R is preferably a tert-butoxycarbonyl group (Boc group) or a 9-fluorenylmethoxycarbonyl group, and particularly preferably a tert-butoxycarbonyl group. 4 is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a thermally detachable group, more preferably an alkyl group having 1 to 3 carbon atoms or a thermally detachable group, and even more preferably a thermally detachable group.

[0030] The structural unit (IIb) is particularly preferred in that it can provide a liquid crystal device with excellent resistance to high temperature and high humidity, and ... 4a -, -NR 4a -CO-, -NR 4 - and -CO- are substituted with the same or different groups selected from the group consisting of4 is a hydrogen atom or a monovalent organic group. 4a is a monovalent thermally detachable group. 2 , * 2 -OCO-, -O-, -CO-NR 4a -* 2 , * 2 -NR 4a It is more preferable that the group is at least one of -CO- and -CO-. 2 " has the same meaning as above.

[0031] Specific examples of the partial structure (B) contained in the structural unit (II) include partial structures represented by the following formulas (2-1) to (2-22). [ka] [ka]

[0032] In the polyimide (P), the content of the structural unit (II) is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units derived from the monomers constituting the polyimide (P). The content of the structural unit (II) is preferably 49 mol% or less, more preferably 45 mol% or less, and even more preferably 40 mol% or less, based on all structural units derived from the monomers constituting the polyimide (P). A content of the structural unit (II) of 1 mol% or more is preferable because it can enhance the effect of improving adhesion to the substrate and high-temperature, high-humidity resistance by introducing a relatively long-chain unit derived from the structural unit (II). A content of the structural unit (II) of 49 mol% or less is preferable because it can introduce a sufficient amount of the structural unit (I) into the polyimide (P), thereby enhancing the effect of improving mechanical properties by introducing an aromatic ring-specific heteroatom-containing group-alkylene structure. The structural unit (II) contained in the polyimide (P) may be of one type alone or of two or more types.

[0033] In the polyimide (P), the ratio of the structural units (I) to the structural units (II) (structural units (I) / structural units (II)) is preferably 1 / 10 to 10 / 1 in molar ratio, more preferably 1 / 4 to 4 / 1, even more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1. When the ratio of the structural units (I) to the structural units (II) is within the above range, it is preferable in that the effect of improving the mechanical strength of the film, and the effect of improving adhesion to the substrate and high-temperature / high-humidity resistance (particularly the effect of improving the mechanical strength of the film) can be further enhanced.

[0034] Polyimide (P) manufacturing There is no particular limitation on the method for producing the polyimide (P). The polyimide (P) can be produced, for example, by reacting a tetracarboxylic dianhydride with a diamine to obtain a polyamic acid having the structural unit (I) and the structural unit (II) (hereinafter also referred to as "polyamic acid (P)"), and then subjecting the polyamic acid (P) to dehydration ring closure for imidization.

[0035] Similarly, the method for producing the polyamic acid (P) is not particularly limited. From the viewpoint of a high degree of freedom in the selection of monomers, it is preferable that the structural unit (I) is introduced into the polymer by a diamine having a partial structure (A) (hereinafter also referred to as "specific diamine A"). It is also preferable that the structural unit (II) is introduced into the polymer by a diamine having a partial structure (B) (hereinafter also referred to as "specific diamine B"). One preferred embodiment of the polyimide (P) is a polyimide having a structural unit derived from a diamine having a partial structure (A) and a structural unit derived from a diamine having a partial structure (B).

[0036] (Tetracarboxylic acid dianhydride) Examples of the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (P) include aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aromatic tetracarboxylic acid dianhydrides. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic dianhydride; alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2, Examples of suitable tetracarboxylic dianhydrides include 4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, and 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride; aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-carbonyldiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride; and the tetracarboxylic dianhydrides described in JP 2010-97188 A can be used. Tetracarboxylic dianhydrides can be used alone or in combination.

[0037] The tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (P) preferably contains at least one selected from the group consisting of aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides, and more preferably contains an alicyclic tetracarboxylic acid dianhydride, in order to obtain a liquid crystal alignment film that has high solubility and good electrical properties. The proportion of the alicyclic tetracarboxylic acid dianhydride used is preferably 20 mol % or more, more preferably 50 mol % or more, and even more preferably 80 mol % or more, based on the total amount of tetracarboxylic acid dianhydrides used in the synthesis of the polyamic acid (P).

[0038] When a liquid crystal alignment film is formed by a photoalignment method, a tetracarboxylic dianhydride having a cyclobutane structure (hereinafter also referred to as a "specific acid dianhydride") can be preferably used as the tetracarboxylic dianhydride used in synthesizing the polyamic acid (P). The specific acid dianhydride is preferably a compound represented by the following formula (4). [ka] (In formula (4), R 11 , R 12 , R 13 and R 14 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms.

[0039] Among them, the specific acid dianhydride is particularly preferably one or both of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride. Note that, as the specific acid dianhydride, only one type may be used, or two or more types may be used.

[0040] When a specific acid dianhydride is used in synthesizing the polyamic acid (P), the proportion of the specific acid dianhydride used is preferably 20 mol % or more, more preferably 50 mol % or more, still more preferably 80 mol % or more, and even more preferably 90 mol % or more, based on the total amount of tetracarboxylic acid dianhydride used in synthesizing the polyamic acid (P), from the viewpoint of imparting good liquid crystal alignment properties by light irradiation.

[0041] (Specific diamine A) The specific diamine A is not particularly limited as long as it has the partial structure (A) represented by the above formula (1). Specific examples of the specific diamine A include compounds represented by the following formulas (5-1) to (5-24). [ka] [ka] [ka] [ka]

[0042] In synthesizing the polyimide (P), the amount of the specific diamine A used is preferably 2 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total amount of diamine compounds used in synthesizing the polyimide (P). Furthermore, the amount of the specific diamine A used is preferably 98 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, and even more preferably 70 mol% or less, based on the total amount of diamine compounds used in synthesizing the polyimide (P). Using an amount of the specific diamine A of 2 mol% or more is preferred in that it enhances the effect of improving mechanical properties by introducing an aromatic ring-specific heteroatom-containing group-alkylene structure. Using an amount of the specific diamine A of 98 mol% or less is preferred in that it allows a sufficient amount of structural units derived from the specific diamine B, i.e., relatively long-chain units, to be introduced into the polyimide (P), thereby enhancing the effect of improving adhesion to the substrate and resistance to high temperatures and high humidity. The specific diamine A may be used alone or in combination of two or more.

[0043] (Specific diamine B) The specific diamine B is not particularly limited as long as it has the partial structure (B). The specific diamine B is preferably an aromatic diamine, and examples thereof include compounds represented by the following formula (6). [ka] (In formula (6), Ar 5 and Ar 6 are each independently a divalent aromatic ring group. 6 is an alkanediyl group having 5 or more carbon atoms, or at least one methylene group of the alkanediyl group having 5 or more carbon atoms, and is represented by -COO-, -OCO-, -O-, -CO-NR 4 -, -NR 4 -CO-, -NR 4 R is a divalent group substituted with the same or different groups selected from the group consisting of - and -CO-. 4 is a hydrogen atom or a monovalent organic group.

[0044] In the above formula (6), Ar 5 and Ar 6 The divalent aromatic ring group represented by the formula (1) includes Ar 1 and Ar 2 Examples of the divalent aromatic ring group represented by Ar include the groups exemplified above. 5 and Ar 6 may have a substituent in the aromatic ring portion. Examples of the substituent include an alkyl group having 1 to 3 carbon atoms, a halogen atom, and a cyano group. 5 and Ar 6 From the viewpoint of increasing the density and transmittance of the liquid crystal alignment film, the divalent aromatic ring group represented by the formula (I) is preferably a divalent group having a benzene ring, a naphthalene ring, a pyridine ring, or a pyrimidine ring, and more preferably a divalent group having a benzene ring or a pyridine ring.

[0045] R 6 The description of the partial structure (B) applies to the description of the divalent group represented by R 6 Examples of the divalent group represented by the formula include groups represented by the above formulas (2-1) to (2-22).

[0046] Specific examples of the specific diamine B include compounds represented by the following formulas (6-1) to (6-23). [ka] [ka] [ka] [ka]

[0047] In the polyimide (P), the amount of specific diamine B used is preferably 2 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total amount of diamines used in the synthesis of the polyimide (P). Furthermore, the amount of specific diamine B used is preferably 98 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, and even more preferably 70 mol% or less, based on the total amount of diamines used in the synthesis of the polyimide (P). When the amount of specific diamine B used is 2 mol% or more, it is preferable that the introduction of relatively long-chain units derived from the specific diamine B can enhance the effect of improving adhesion to the substrate and resistance to high temperatures and high humidity. When the amount of specific diamine B used is 98 mol% or less, it is preferable that a sufficient amount of structural unit (I) can be introduced into the polyimide (P), thereby enhancing the effect of improving mechanical properties due to the introduction of an aromatic ring-specific heteroatom-containing group-alkylene structure. The specific diamine B may be used alone or in combination of two or more.

[0048] In the polyimide (P), the ratio of specific diamine A to specific diamine B (specific diamine A / specific diamine B) is preferably 1 / 10 to 10 / 1 in molar ratio, more preferably 1 / 4 to 4 / 1, even more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1. When the ratio of specific diamine A to specific diamine B is within the above range, it is preferable in that the effect of improving the mechanical strength of the film, and the effects of improving adhesion to the substrate and resistance to high temperatures and high humidity can be further enhanced.

[0049] (Other diamines) The diamines used in the synthesis of the polyimide (P) may consist solely of the specific diamine A and the specific diamine B, or may contain a diamine having neither the partial structure (A) nor the partial structure (B) (hereinafter also referred to as "other diamines") in addition to the specific diamine A and the specific diamine B. Examples of other diamines include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes.

[0050] Specific examples of other diamines include aliphatic diamines such as ethylenediamine and tetramethylenediamine; alicyclic diamines such as p-cyclohexanediamine and 4,4'-methylenebis(cyclohexylamine); and diaminoorganosiloxanes such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0051] Aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylamine, 4-aminophenyl-4'-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, N,N-bis(4-aminophenyl)methylamine, N,N'-bis(4-aminophenyl)benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-(phenylenediisopropylidene). Bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4-(4-aminophenoxycarbonyl)-1-(4-aminophenyl)piperidine, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, cholestanyloxydiaminobenzene, cholestanyl diaminobenzoate, cholesteryl diaminobenzoate, lanostannyl diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 2,5-diamino-N,N-diallylaniline, and the following formulas (7-1) to (7-5): [ka] (wherein in formula (7-1) to formula (7-4), n is an integer of 1 to 20). In addition to the above, the other diamines that can be used include the diamines described in JP-A-2010-97188. Note that, as the other diamines, one type may be used alone, or two or more types may be used in combination.

[0052] (Synthesis of Polyimide (P)) When polyimide (P) is obtained by imidizing polyamic acid (P), first, the above-mentioned tetracarboxylic dianhydride and diamine are reacted together with a molecular weight modifier as needed to obtain polyamic acid (P).

[0053] In the synthesis reaction of polyamic acid (P), the ratio of tetracarboxylic dianhydride to diamine is preferably such that 0.2 to 2 equivalents of acid anhydride groups of the tetracarboxylic dianhydride are used per equivalent of amino groups of the diamine. Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The ratio of the molecular weight modifier used is preferably 20 parts by mass or less per 100 parts by mass of the total of the tetracarboxylic dianhydride and diamine used.

[0054] The synthesis reaction of the polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature is preferably −20° C. to 150° C., and the reaction time is preferably 0.1 to 24 hours. Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, ester solvents, ether solvents, halogenated hydrocarbons, and hydrocarbons. Among these, it is preferable to use one or more solvents selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenols as the reaction solvent, or to use a mixture of one or more of these solvents with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used is preferably such that the total amount of tetracarboxylic dianhydride and diamine is 0.1 to 50% by mass based on the total amount of the reaction solution.

[0055] Subsequently, the obtained polyamic acid (P) is subjected to dehydration ring closure. The dehydration ring closure of the polyamic acid (P) is preferably carried out by dissolving the polyamic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to the solution, and heating as needed. In this method, the dehydrating agent may be, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.01 to 20 mol per mol of the amic acid structure of the polyamic acid (P). The dehydration ring closure catalyst may be, for example, a tertiary amine such as pyridine, collidine, lutidine, or triethylamine. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 mol per mol of the dehydrating agent used. Examples of organic solvents used in the dehydration ring closure reaction include the organic solvents exemplified as those used in the synthesis of the polyamic acid (P). The reaction temperature for the dehydration ring closure reaction is preferably 0 to 180°C. The reaction time is preferably 1.0 to 120 hours.

[0056] In this way, a solution containing polyimide (P) is obtained. The reaction solution containing polyimide (P) may be used as it is for preparing a liquid crystal aligning agent, or the polyimide (P) may be isolated and then used for preparing a liquid crystal aligning agent.

[0057] The polyimide (P) preferably has an imidization rate of 30% or more. By introducing the partial structure (A) into the main chain of the polyimide, it is possible to impart good liquid crystal alignment properties to an organic film formed using the liquid crystal alignment agent, regardless of whether a rubbing treatment or a photo-alignment treatment is used. On the other hand, it has been found that imidization of a polyamic acid having the partial structure (A) tends to result in a decrease in mechanical properties and a decrease in adhesion to the substrate. The decrease in mechanical properties and a decrease in adhesion to the substrate of the liquid crystal alignment film due to the imidization of a polyamic acid having the partial structure (A) tend to be more pronounced as the imidization rate increases.

[0058] In view of these points, by introducing partial structure (A) and partial structure (B) into the main chain of the polyimide, even if the imidization rate of the polyimide (P) is high, it is possible to suppress deterioration in mechanical properties and deterioration in adhesion to the substrate, and further to form a liquid crystal alignment film with excellent high-temperature and high-humidity resistance. From the viewpoint of improving the high-temperature and high-humidity resistance of the liquid crystal alignment film, the imidization rate of the polyimide (P) is more preferably 40% or more, even more preferably 45% or more, still more preferably 60% or more, and particularly preferably 80% or more. Furthermore, from the viewpoint of sufficiently increasing the film strength, the imidization rate of the polyimide (P) is preferably 99% or less, more preferably 90% or less.

[0059] The imidization ratio is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide (P). Some of the imide rings may be isoimide rings.

[0060] The solution viscosity of the polyimide (P) is preferably 10 to 800 mPa·s when the polyimide (P) is prepared into a 10% by mass solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is a value measured at 25°C using an E-type rotational viscometer for a 10% by mass polymer solution prepared using a good solvent for the polyimide (P) (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0061] The polyimide (P) has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw / Mn), which is the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC, is preferably 7 or less, more preferably 5 or less.

[0062] The content of polyimide (P) in the liquid crystal aligning agent is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the total of solid components (i.e., components other than the solvent) in the liquid crystal aligning agent. In preparing the liquid crystal aligning agent, one type of polyimide (P) may be used alone, or two or more types may be used in combination.

[0063] <Other ingredients> The liquid crystal aligning agent of the present disclosure may further contain components other than the polyimide (P) (hereinafter also referred to as "other components") The other components will be described below.

[0064] (Other polymers) The liquid crystal aligning agent of the present disclosure may further contain a polymer other than the polyimide (P) (hereinafter also referred to as "other polymer") for the purpose of further improving the liquid crystal alignment property and electrical properties of the liquid crystal alignment film formed using the liquid crystal aligning agent.

[0065] The main skeleton of the other polymer is not particularly limited, and examples thereof include polyamic acid, polyamic acid ester, polyimide (excluding polyimide (P)), polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, etc. The other polymer is preferably a polymer having neither the structural unit (I) nor the structural unit (II).

[0066] As the other polymer, at least one polymer selected from the group consisting of polyamic acid and polyamic acid ester (hereinafter also referred to as "polymer (Q)") can be preferably used. A liquid crystal aligning agent in which polyimide (P) and polymer (Q) are blended is likely to cause phase separation between polyimide (P) and polymer (Q) in the liquid crystal alignment film, and polyimide (P) is likely to be unevenly distributed in the upper layer. This is thought to highly improve the liquid crystal alignment property and rubbing resistance of the liquid crystal alignment film, and also to enable the production of a liquid crystal alignment film with excellent adhesion to the substrate.

[0067] As the other polymer, it is preferable to use a polymer containing a structural unit having a partial structure represented by the following formula (3) (hereinafter also referred to as "structural unit (III)"): By incorporating a polymer containing the structural unit (III) into a liquid crystal aligning agent together with polyimide (P), it is possible to sufficiently reduce the accumulated charge in the liquid crystal alignment film, and it is advantageous in that the occurrence of afterimages can be suppressed in the resulting liquid crystal element. [ka] (In formula (3), Ar 3 , Ar 4 and R 5 satisfies (i), (ii), or (iii) below. (i)Ar 3 and Ar 4 R are each independently a divalent aromatic ring group. 5 is a hydrogen atom or a monovalent organic group. (ii) Ar 3 and Ar4 These are combined together to form Ar 3 an aromatic ring having -NR 5 - and Ar 4 R represents a nitrogen-containing condensed ring structure formed together with the aromatic ring. 5 is a hydrogen atom or a monovalent organic group. (iii) Ar 3 and R 5 These are combined together to form Ar 3 an aromatic ring having R 5 and R 5 represents a nitrogen-containing fused ring structure formed together with the nitrogen atom to which Ar is attached. 4 is a divalent aromatic ring group. "*" indicates a bond.)

[0068] In the above formula (3), Ar 3 and Ar 4 Examples of the divalent aromatic ring group represented by the formula (1) include a substituted or unsubstituted divalent aromatic hydrocarbon group and a substituted or unsubstituted divalent aromatic heterocyclic group. Specific examples of the divalent aromatic heterocyclic group include Ar 1 and Ar 2 From the viewpoint of increasing the density and the transmittance of the liquid crystal alignment film, Ar 3 and Ar 4 The divalent aromatic ring group is preferably a substituted or unsubstituted divalent aromatic hydrocarbon group, more preferably a substituted or unsubstituted phenylene group.

[0069] Ar 3 and Ar 4 and are combined with each other 3 an aromatic ring having -NR 5 - and Ar 4 Examples of the nitrogen-containing condensed ring structure formed together with the aromatic ring of Ar include a carbazole structure, a 9-methylcarbazole structure, and a 9-ethylcarbazole structure. 3 and R 5 and are combined with each other 3 The aromatic ring and R 5Examples of the nitrogen-containing fused ring structure formed together with the nitrogen atom to which the group is bonded include an indoline structure, an isoindoline structure, and a carbazole structure.

[0070] R 5 The monovalent organic group represented by the above R 2 The monovalent organic groups exemplified in the description of R 2 For similar reasons, R 5 The monovalent organic group represented by R is preferably a tert-butoxycarbonyl group (Boc group) or a 9-fluorenylmethoxycarbonyl group, and particularly preferably a tert-butoxycarbonyl group. 5 is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a thermally detachable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a tert-butoxycarbonyl group.

[0071] In other polymers, the partial structure represented by the above formula (3) is preferably introduced into the main chain of the polymer. Specific examples of the partial structure represented by the above formula (3) include partial structures represented by each of the following formulas (3-1) to (3-9). [ka] (In formulas (3-1) to (3-9), "*" represents a bond.)

[0072] The polymer having the structural unit (III) is preferably at least one polymer (i.e., polymer (Q)) selected from the group consisting of polyamic acid and polyamic acid ester. By incorporating the polymer (Q) having the structural unit (III) into the liquid crystal aligning agent together with the polyimide (P), it is possible to provide the liquid crystal aligning agent with the function of reducing accumulated charges in the liquid crystal alignment film while sufficiently improving the liquid crystal alignment property and adhesion to the substrate. The polymer (Q) having the structural unit (III) can be obtained, for example, by polymerization using a diamine having a partial structure represented by the above formula (3) (hereinafter also referred to as "specific diamine C").

[0073] Specific examples of the specific diamine C include compounds represented by the following formulas (8-1) to (8-17). [ka] [ka]

[0074] The polymer (Q) can be synthesized according to a conventionally known method. For example, polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine. Examples of the tetracarboxylic dianhydride include the same compounds as those exemplified as tetracarboxylic dianhydrides that can be used in the synthesis of the polyimide (P). As the diamine, the specific diamine C alone may be used, or the specific diamine C may be used together with other diamines exemplified as diamines that can be used in the synthesis of the polyimide (P).

[0075] When the polymer [Q] is a polyamic acid ester, the polyamic acid ester can be obtained, for example, by a method of reacting the polyamic acid obtained above with an esterifying agent (e.g., methanol, ethanol, N,N-dimethylformamide diethyl acetal, etc.), a method of reacting a tetracarboxylic acid diester with a diamine compound in the presence of a suitable dehydration catalyst, a method of reacting a tetracarboxylic acid diester dihalide with a diamine in the presence of a suitable base, or the like.

[0076] The solution viscosity of polymer (Q) is preferably 10 to 800 mPa·s when the polymer (Q) is prepared into a 10% by mass solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is a value measured at 25°C using an E-type rotational viscometer for a 10% by mass polymer solution prepared using a good solvent for polymer (Q) (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0077] The weight average molecular weight (Mw) of the polymer (Q) measured by GPC in terms of polystyrene is preferably 1,000 to 500,000, more preferably 5,000 to 100,000. The molecular weight distribution (Mw / Mn), which is the ratio of Mw to the number average molecular weight (Mn) measured by GPC in terms of polystyrene, is preferably 15 or less, more preferably 10 or less. The polymer (Q) contained in the liquid crystal aligning agent may be one type alone or two or more types may be combined.

[0078] When a polymer (Q) is blended into the liquid crystal aligning agent of the present disclosure, the ratio of the polyimide (P) to the total content of the polyimide (P) and the polymer (Q) is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the total amount of the polyimide (P) and the polymer (Q). Furthermore, when a polymer (Q) is blended, the content of the polyimide (P) is preferably 95 parts by mass or less, more preferably 70 parts by mass or less, per 100 parts by mass of the total amount of the polyimide (P) and the polymer (Q). By setting the content of the polyimide (P) within the above range, it is possible to reduce accumulated charges in the liquid crystal alignment film, and it is advantageous in that it is possible to improve the adhesion of the film to the substrate, the mechanical properties, and the high-temperature and high-humidity resistance of the film.

[0079] Other components that may be contained in the liquid crystal aligning agent of the present disclosure include, in addition to the polymer (Q), for example, a compound having one or more epoxy groups in the molecule, a compound having two or more methylol groups in the molecule, a functional silane compound, a compound having one or more (meth)acryloyl groups in the molecule, an antioxidant, a metal chelate compound, a curing accelerator, a surfactant, a filler, a dispersant, a photosensitizer, etc. The blending ratio of these can be appropriately selected depending on each compound within a range that does not impair the effects of the present disclosure.

[0080] (solvent) The liquid crystal aligning agent is usually prepared as a liquid composition obtained by dispersing or dissolving the polyimide (P) and other components used as needed, preferably in a suitable solvent.

[0081] Examples of the organic solvent to be used include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone (diacetone alcohol), ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, and ethylene glycol-i-propyl ether. ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, etc. These can be used alone or in combination of two or more.

[0082] The solids concentration in the liquid crystal aligning agent (the ratio of the total mass of the components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected taking into consideration viscosity, volatility, etc., but is preferably in the range of 1 to 10 mass%. That is, the liquid crystal aligning agent is applied to the surface of a substrate as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. In this case, a solids concentration of 1 mass% or more is preferable because it ensures a sufficient thickness of the coating film and makes it easy to obtain a good liquid crystal alignment film. Furthermore, a solids concentration of 10 mass% or less allows the coating film to have an unduly thick thickness, thereby making it possible to obtain a good liquid crystal alignment film, and also ensures an appropriate viscosity of the liquid crystal aligning agent, resulting in good applicability.

[0083] <Liquid crystal alignment film and liquid crystal element> The liquid crystal alignment film of the present disclosure is formed using the liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and various modes such as TN (Twisted Nematic), STN (Super Twisted Nematic), VA (Vertical Alignment) (including VA-MVA, VA-PVA, etc.), IPS (In-Plane Switching), FFS (Fringe Field Switching), OCB (Optically Compensated Bend), and PSA (Polymer Sustained Alignment) can be applied. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, different substrates are used depending on the desired operation mode. Steps 2 and 3 are common to all operation modes.

[0084] (Step 1: Formation of coating film) First, a liquid crystal alignment agent is applied to a substrate, and the coated surface is preferably heated to form a coating film on the substrate. Examples of substrates that can be used include transparent substrates made of glass, such as float glass or soda glass; or plastics, such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefin). Examples of transparent conductive films that can be provided on one side of the substrate include NESA films (registered trademarks of PPG, Inc., USA) made of tin oxide (SnO2) and ITO films made of indium oxide-tin oxide (In2O3-SnO2). When manufacturing TN, STN, or VA liquid crystal devices, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS liquid crystal devices, one substrate is provided with electrodes made of a comb-shaped patterned transparent conductive film or metal film, and another substrate with no electrodes is used. Examples of metal films that can be used include films made of metals such as chromium. The liquid crystal alignment agent is applied to the substrate on the electrode-forming surface, preferably by offset printing, spin coating, roll coating, or inkjet printing.

[0085] After the liquid crystal aligning agent is applied, preliminary heating (pre-baking) is preferably carried out for the purpose of preventing dripping of the applied liquid crystal aligning agent, etc. The pre-baking temperature is preferably 30 to 150° C., more preferably 40 to 120° C. The pre-baking time is preferably 0.25 to 10 minutes.

[0086] Thereafter, the solvent is removed, and if necessary, a baking (post-baking) step is carried out to thermally imidize the amic acid structure present in the polymer. The baking temperature (post-baking temperature) is preferably 280°C or lower, more preferably 250°C or lower. In addition, from the viewpoint of suppressing deterioration of liquid crystal alignment properties and reliability due to the influence of solvent components remaining in the film, the post-baking temperature is preferably 80°C or higher, more preferably 90°C or higher. The post-baking time is preferably 5 to 150 minutes. The film thus formed preferably has a thickness of 0.001 to 1 μm. After applying the liquid crystal alignment agent to a substrate, a liquid crystal alignment film or a film that will become a liquid crystal alignment film is formed by removing the organic solvent.

[0087] (Step 2: Alignment treatment) When manufacturing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal device, the coating film formed in step 1 above is subjected to a treatment (alignment treatment) to impart liquid crystal alignment ability. This imparts the ability to align liquid crystal molecules to the film, turning it into a liquid crystal alignment film. As the alignment treatment, a rubbing treatment in which the surface of the film formed on the substrate is rubbed with cotton or the like, or a photo-alignment treatment in which the film formed on the substrate is irradiated with light to impart liquid crystal alignment ability, is preferably used. When manufacturing a vertical alignment type liquid crystal device, the film formed in step 1 above may be used as a liquid crystal alignment film as is, or the film may be subjected to an alignment treatment to further enhance the liquid crystal alignment ability.

[0088] When a liquid crystal alignment film is produced by a photo-alignment treatment, the film can be irradiated with light by a method of irradiating the film after the post-bake step, a method of irradiating the film after the pre-bake step but before the post-bake step, or a method of irradiating the film while it is being heated in at least one of the pre-bake step and the post-bake step. In the photo-alignment treatment, the radiation to be irradiated to the coating film can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm. Preferably, ultraviolet light containing light with a wavelength of 200 to 400 nm is used. When the radiation is polarized, it may be linearly polarized or partially polarized. Furthermore, when the radiation used is linearly polarized or partially polarized, the radiation may be applied perpendicular to the substrate surface, obliquely, or in a combination thereof. When unpolarized radiation is used, the radiation is applied obliquely.

[0089] Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 400 to 20,000 J / m 2 and more preferably 1,000 to 5,000 J / m 2 The film may be irradiated with light while being heated in order to enhance reactivity.

[0090] In producing a liquid crystal alignment film, the film that has been subjected to light irradiation treatment may be further heated. The method may further include a contacting step in which the film that has been subjected to light irradiation treatment is brought into contact with water, a water-soluble organic solvent, or a mixed solvent of water and a water-soluble organic solvent. Examples of water-soluble organic solvents include methanol, ethanol, 1-propanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone. After the contacting step, the film may be subjected to a heat treatment.

[0091] (Step 3: Construction of liquid crystal cell) Two substrates with liquid crystal alignment films formed thereon are prepared as described above, and a liquid crystal cell is fabricated by disposing a liquid crystal between the two opposing substrates. Examples of methods for fabricating a liquid crystal cell include: (1) arranging the two substrates facing each other with a gap (spacer) between them so that the liquid crystal alignment films face each other, bonding the peripheries of the two substrates together using a sealant, injecting liquid crystal into the substrate surfaces and the cell gap defined by the sealant, and then sealing the injection hole; and (2) applying a sealant to a predetermined location on one of the substrates with a liquid crystal alignment film, dropping liquid crystal onto several predetermined locations on the liquid crystal alignment film, and then bonding the other substrate so that the liquid crystal alignment film faces the other substrate, while spreading the liquid crystal over the entire surface of the substrate (ODF method). The fabricated liquid crystal cell is preferably further heated to a temperature at which the liquid crystal used assumes an isotropic phase and then slowly cooled to room temperature to remove flow alignment during liquid crystal filling.

[0092] The sealing agent may be, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers, such as photospacers and bead spacers.

[0093] Either positive-type or negative-type liquid crystals may be used. The use of negative-type liquid crystals in IPS-type and FFS-type liquid crystal elements is preferred because it reduces transmission loss above the electrodes and improves contrast. Examples of liquid crystals that can be used include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred. Examples of nematic liquid crystals that can be used include Schiff-based liquid crystals, azoxy-based liquid crystals, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, and cubane-based liquid crystals. These liquid crystals may also be used by adding, for example, cholesteric liquid crystals, chiral agents, or ferroelectric liquid crystals.

[0094] In the PSA mode, a polymerizable compound (e.g., a polyfunctional (meth)acrylate compound) is filled into the cell gap together with the liquid crystal, and after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates. In producing a PSA mode liquid crystal element, the proportion of the polymerizable compound used is 0.01 to 3 parts by mass, preferably 0.1 to 1 part by mass, per 100 parts by mass of the total liquid crystal.

[0095] Next, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine, sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself. This produces a liquid crystal device.

[0096] The liquid crystal element of the present disclosure can be effectively applied to various uses, for example, various display devices such as watches, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays, as well as light control films, etc. Furthermore, a liquid crystal element formed using the liquid crystal aligning agent of the present disclosure can also be applied to optical films such as retardation films.

[0097] According to the present disclosure described above, the following means are provided. [Means 1] A structural unit (I) having a partial structure represented by the above formula (1) and an alkylene structure having 5 or more carbon atoms or at least one methylene group of the alkylene structure having 5 or more carbon atoms are not adjacent to each other, and the structural unit (I) is -COO-, -OCO-, -O-, -CO-NR 4 -, -NR 4 -CO-, -NR 4 - and -CO- are substituted with the same or different groups selected from the group consisting of 4 is a hydrogen atom or a monovalent organic group, and a polyimide containing a structural unit (II) having the structural unit (I) (excluding the structural unit (I)). [Means 2] The liquid crystal aligning agent according to [Means 1], wherein the imidization rate of the polyimide is 30% or more. [Means 3] The structural unit (II) is formed by the condition that an alkylene structure having 5 or more carbon atoms or at least one methylene group in the alkylene structure having 5 or more carbon atoms is not adjacent to another, and is —COO—, —OCO—, —O—, —CO—NR 4a -, -NR 4a -CO-, -NR 4 - and -CO- are substituted with the same or different groups selected from the group consisting of 4 is a hydrogen atom or a monovalent organic group. 4a is a monovalent thermally detachable group. [Means 4] The liquid crystal aligning agent according to any one of [Means 1] to [Means 3], further containing a polymer containing a structural unit having a partial structure represented by the above formula (3), which is different from the polyimide. [Means 5] The liquid crystal aligning agent according to any one of [Means 1] to [Means 4], further comprising at least one polymer selected from the group consisting of polyamic acids and polyamic acid esters. [Means 6] A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of [Means 1] to [Means 5]. [Means 7] A liquid crystal element comprising the liquid crystal alignment film according to [Means 6]. [Example]

[0098] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0099] <Measurement method> In the following examples, the solution viscosity of the polymer and the imidization rate of the polyimide were measured by the following methods.

[0100] [Polymer solution viscosity] The solution viscosity of the polymer was measured at 25°C using an E-type viscometer.

[0101] [Imidization rate of polyimide] The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. After that, it was dissolved in deuterated dimethyl sulfoxide and measured at room temperature using tetramethylsilane as a standard substance. 1 H-NMR measurement was carried out. 1 The imidization rate [%] was calculated from the H-NMR spectrum using the following formula (a). Imidization rate [%] = (1-(β 1 / (β 2 ×α)))×100 …(a) (In formula (a), β 1 is the peak area due to the proton of the NH group that appears at a chemical shift of around 10 ppm, and β 2 is the peak area due to other protons, and α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid).

[0102] <Compound abbreviation> The abbreviations of the compounds used in the following examples are shown below. For convenience, hereinafter, a "compound represented by formula (X)" (X is a symbol) may be simply referred to as "compound (X)."

[0103] [Tetracarboxylic acid dianhydride] [ka]

[0104] [Diamine] Specific diamine B [ka] [ka]

[0105] Specific diamine A [ka]

[0106] Other diamines [ka] [ka]

[0107] <Polymer synthesis> 1. Polyimide Synthesis [Synthesis Example 2] 50 mol parts of compound (DB-1) as a diamine and 50 mol parts of compound (DC-11) were dissolved in N-methyl-2-pyrrolidone (NMP), and 100 mol parts of compound (TA-1) as a tetracarboxylic dianhydride were added. The reaction was allowed to proceed at 40 °C for 24 hours to obtain a solution containing 15% by mass of polyamic acid. Next, NMP was added to the resulting polyamic acid solution, and pyridine and acetic anhydride were added in amounts of 1.80 molar equivalents relative to the carboxyl groups derived from the tetracarboxylic dianhydride in the polyamic acid. The dehydration ring-closing reaction was carried out at 80 °C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP and further concentrated to obtain a solution containing 15% by mass of polyimide with an imidization rate of 80% (referred to as polymer (PI-1)). A small aliquot of this solution was taken, and NMP was added to make a 10% solution. The solution viscosity was measured and was 100 mPa·s.

[0108] [Synthesis Examples 3-11, 13-17] Polymerization was performed in the same manner as in Synthesis Example 2, except that the types and amounts of tetracarboxylic dianhydrides and diamines used in the polymerization were changed as shown in Table 1. Solutions containing polyimide polymers (PI-2) to (PI-10) and (PI-12) to (PI-16) were obtained. The polymerizations were carried out with a diamine to tetracarboxylic dianhydride molar ratio (diamine / tetracarboxylic dianhydride) of 0.85 to 1.0, so that the viscosity of a 10% by mass NMP solution of the polymer was 40 to 100 mPa·s. In Table 1, the values ​​for the dianhydrides represent the proportion (in molar parts) of each compound relative to 100 molar parts of the total amount of tetracarboxylic dianhydrides used in the synthesis. The values ​​for the diamines represent the proportion (in molar parts) of each compound relative to 100 molar parts of the total amount of diamines used in the synthesis.

[0109] [Synthesis Example 12] 20 mol parts of compound (DA-6) and 80 mol parts of compound (DB-4) were dissolved in N-methyl-2-pyrrolidone (NMP), and 80 mol parts of compound (TA-1) and 20 mol parts of compound (TA-3) were added as tetracarboxylic dianhydrides. The reaction was carried out at 40 °C for 24 hours to obtain a solution containing 15% by mass of polyamic acid. The resulting polyamic acid solution was then subjected to a dehydration ring-closure reaction at 180 °C for 2 hours. After the dehydration ring-closure reaction, the solvent in the system was replaced with fresh NMP and the mixture was further concentrated to obtain a solution containing 15% by mass of 100% imidized polyimide (referred to as polymer (PI-11)). A small amount of this solution was taken, and NMP was added to make a 10% solution. The solution viscosity was measured and was 80 mPa·s.

[0110] 2. Synthesis of polyamic acid [Synthesis Example 1] 50 mole parts of compound (DA-1) as a diamine and 50 mole parts of compound (DB-1) were dissolved in N-methyl-2-pyrrolidone (NMP), and 100 mole parts of compound (TA-1) as a tetracarboxylic dianhydride was added and reacted at 40°C for 24 hours to obtain a solution containing 15 mass% of polyamic acid (referred to as polymer (PA-1)).

[0111] [Synthesis Examples 18-25] Polymerization was performed in the same manner as in Synthesis Example 1, except that the types and amounts of tetracarboxylic dianhydrides and diamines used in the polymerization were changed as shown in Table 2, to obtain solutions containing polyamic acid polymers (PA-2) to (PA-9). The polymerizations were carried out with a molar ratio of diamine to tetracarboxylic dianhydride (diamine / tetracarboxylic dianhydride) of 0.85 to 1.0, so that the viscosity of a 10% by mass NMP solution of the polymer was 40 to 100 mPa·s. In Table 2, the values ​​for the dianhydrides represent the proportion (in molar parts) of each compound relative to 100 molar parts of the total amount of tetracarboxylic dianhydrides used in the synthesis. The values ​​for the diamines represent the proportion (in molar parts) of each compound relative to 100 molar parts of the total amount of diamines used in the synthesis.

[0112] [Table 1]

[0113] [Table 2]

[0114] <Production and evaluation of liquid crystal elements> [Example 1: FFS-type liquid crystal display element] 1. Preparation of Liquid Crystal Alignment Agent The solution of the polymer (PI-8) obtained in Synthesis Example 9 was diluted with NMP and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP / BC=80 / 20 (mass ratio) and a solid content of 3.5 mass %. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

[0115] 2. Evaluation of adhesion The liquid crystal alignment agent (AL-1) was applied to a glass substrate using a spinner, pre-baked on a hot plate at 80°C for 2 minutes, and then heated (post-baked) for 30 minutes in an oven at 230°C with the interior replaced with nitrogen, forming a coating film with an average thickness of 0.10 μm. By repeating the same procedure, two glass substrates with coating films were produced. On the coating film of one glass substrate with a coating film formed, an ODF sealant (S-WB42, manufactured by Sekisui Chemical Co., Ltd.) was applied to a width of 1 mm, and the other glass substrate was bonded so that the coating film and the ODF sealant were in contact. After that, a metal halide lamp was used to apply 30,000 J / m 2 After irradiating the film with light (equivalent to 365 nm), the film was heated in an oven at 120°C for 1 hour. The adhesion strength was then measured using a tension and compression tester (model number: SDWS-0201-100SL) manufactured by Imada Seisakusho, and the adhesion of the film to the substrate was evaluated. The evaluation was conducted when the adhesion strength was 175 N / cm 2 If it is above 125N / cm, it is considered "Good (◎)" 2 More than 175N / cm 2 If it is less than 125N / cm, it is marked as "Fair (○)" 2 If the adhesive strength was less than 160 N / cm, it was rated as "poor (x)". 2 The adhesion was evaluated as "fair (○)".

[0116] 3. Evaluation of high temperature and humidity resistance (1) Manufacturing of liquid crystal cells for evaluation The liquid crystal alignment agent (AL-1) prepared above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner and pre-baked on a hot plate at 80°C for 1 minute. It was then heated at 230°C for 1 hour in an oven with the interior replaced with nitrogen to form a coating film with a thickness of 0.1 μm. The same procedure was repeated to prepare a pair (2 sheets) of substrates with liquid crystal alignment films. An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer periphery of the surface of one of the substrates bearing the liquid crystal alignment film. The pair of substrates were then pressed together with the liquid crystal alignment film surfaces facing each other, and the adhesive was thermally cured at 150°C for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was filled into the gap between the substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive. To eliminate flow alignment during liquid crystal injection, the cell was heated to 130°C and then slowly cooled to room temperature to obtain a liquid crystal cell for evaluation.

[0117] (2) Measurement of voltage holding ratio (VHR) A voltage of 5 V was applied to the evaluation liquid crystal cell immediately after fabrication in (1) above at 60°C for 60 microseconds over a span of 167 milliseconds, and the voltage holding ratio (initial voltage holding ratio VH1) was measured 167 milliseconds after the application was removed. A measuring device manufactured by Toyo Corporation, model number "VHR-1," was used. After measuring the initial voltage holding ratio VH1, the evaluation liquid crystal cell was then stored in an oven set at 85°C and 85% humidity for 300 hours, after which the voltage holding ratio was measured in the same manner as for the initial voltage holding ratio VH1. This value was designated the post-stress voltage holding ratio VH2. The percentage decrease in the voltage holding ratio calculated using the following formula (b) was designated ΔVHR (%), and ΔVHR was used to evaluate high-temperature, high-humidity resistance. ΔVHR=(VH2 / VH1)×100 …(b) The evaluation was as follows: ΔVHR of 80% or more was "good (◎)", ΔVHR of 60% or more but less than 80% was "fair (◯)", and ΔVHR of less than 60% was "poor (×)". As a result, in Example 1, ΔVHR was 80%, and the evaluation was "good (◎)".

[0118] 4. Evaluation of film strength (rubbing resistance) The liquid crystal alignment agent (AL-1) prepared in 1. above was applied to a glass substrate using a spinner and heated (pre-baked) on a hot plate at 110°C for 3 minutes. The substrate was then dried (post-baked) for 30 minutes in a nitrogen-purged oven at 230°C to form a coating film with an average thickness of 0.08 μm. The haze value of the coating film was measured using a haze meter. The coating film was then rubbed five times using a rubbing machine equipped with a roll wrapped in cotton cloth at a roll rotation speed of 1000 rpm, a stage movement speed of 3 cm / sec, and a pile depth of 0.3 mm. The haze value of the liquid crystal alignment film was then measured using a haze meter, and the difference from the haze value before and after rubbing (haze change) was calculated. If the haze value of the film before rubbing is Hz1 (%) and the haze value of the film after rubbing is Hz2 (%), the haze change is expressed by the following formula (c): Haze change value (%) = Hz2 - Hz1 ... (c) A haze change value of the liquid crystal alignment film was evaluated as "good (◎)" when it was less than 1.0, "fair (○)" when it was 1.0 or more and 1.5 or less, and "poor (×)" when it was more than 1.5. If the haze change value is 1.5 or less (more preferably less than 1.0), it can be said that the film strength is sufficiently high and the rubbing resistance is high, that is, the mechanical properties of the film are good. As a result, in this example, the film strength was evaluated as "good (◎)".

[0119] 5. Fabrication of FFS-type LCD elements using the rubbing method A glass substrate (referred to as the first substrate) with a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) laminated in this order on one side thereof, and a glass substrate (referred to as the second substrate) without an electrode, were prepared. Next, a liquid crystal alignment agent (AL-1) was applied to the electrode-formed surface of the first substrate and one side of the second substrate using a spinner and heated (pre-baked) on a hot plate at 110°C for 3 minutes. This was then dried (post-baked) for 30 minutes in a nitrogen-purged oven at 230°C to form a coating film with an average thickness of 0.08 μm. The coating film surface was then rubbed using a rubbing machine equipped with a roll wrapped around a rayon cloth at a roll rotation speed of 1000 rpm, a stage movement speed of 3 cm / sec, and a pile depth of 0.3 mm. This was followed by ultrasonic cleaning in ultrapure water for 1 minute and then drying in a clean oven at 100°C for 10 minutes to obtain a pair of substrates with liquid crystal alignment films. Next, a pair of substrates with liquid crystal alignment films were screen-printed with an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres, leaving a liquid crystal injection port at the edge of the surface where the liquid crystal alignment film was formed. The substrates were then stacked and pressed together, and the adhesive was thermally cured at 150°C for 1 hour. Next, negative liquid crystal (MLC-6608, manufactured by Merck) was filled into the gap between the pair of substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive. To eliminate flow alignment during liquid crystal injection, the substrates were heated to 120°C and then slowly cooled to room temperature to produce a liquid crystal cell. When stacking the pair of substrates, the rubbing directions of each substrate were set antiparallel. Polarizing plates were then attached to both outer surfaces of the substrates in the liquid crystal cell to obtain a rubbed FFS-mode liquid crystal display device.

[0120] 6. Evaluation of Charge Storage (RDC) Using the rubbed FFS-type liquid crystal display element manufactured in 5. above, a DC voltage of 2 V was applied at 71°C for 10 minutes, followed by a 0.2-second short circuit. The voltage accumulated in the liquid crystal display element when it was then held in an open state for 10 minutes was measured by a dielectric absorption method. The evaluation was based on whether the charge accumulation amount was 0.1 V or less, "good (◎)," whether the charge accumulation amount was greater than 0.1 V and less than 0.2 V, and whether the charge accumulation amount was greater than 0.2 V, or "poor (×)." As a result, the charge accumulation amount in this example was evaluated as "fair (◯)."

[0121] 7. Evaluation of liquid crystal alignment The rubbed FFS type LCD device manufactured in 5 above was subjected to a 27,000 cd / m 2 The FFS-type liquid crystal display element was left standing for 500 hours in front of a high-brightness backlight, and the liquid crystal alignment was evaluated by the rate of change in retardation before and after backlight irradiation. First, the retardation of the FFS-type liquid crystal display element manufactured in 5 above was measured using an Axoscan manufactured by Optoscience, and the rate of change α in retardation before and after backlight irradiation was calculated using the following formula (d). The smaller the rate of change α, the better the liquid crystal alignment. A rate of change α of 1% or less was rated as "good (◎)", a rate of change α between 1% and 2% was rated as "fair (○)", and a rate of change α greater than 2% was rated as "poor (×)". α=(Δθ / θ1)×100 …(d) (In formula (d), Δθ represents the difference in retardation before and after irradiation, and θ1 represents the retardation value before irradiation.) As a result, the liquid crystal alignment property of this example was evaluated as "good (A)".

[0122] 8. Fabrication of FFS-type LCD elements using the photoalignment method A first substrate and a second substrate were prepared in the same manner as in 5 above. Next, a liquid crystal alignment agent (AL-1) was applied to the electrode-forming surface of the first substrate and one of the substrate surfaces of the second substrate using a spinner, and heated (pre-baked) on a hot plate at 80°C for 1 minute. After that, the coating was dried (post-baked) for 30 minutes in an oven at 230°C with the interior replaced with nitrogen, forming a coating film with an average thickness of 0.1 μm. The resulting coating film was irradiated with 1,000 J / m of linearly polarized ultraviolet light containing a 254 nm emission line using an Hg-Xe lamp. 2 The coating film was then irradiated with light from the normal direction of the substrate to perform a photo-alignment treatment. The irradiation dose was measured using an actinometer measuring at a wavelength of 254 nm. The photo-aligned coating film was then heat-treated in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. Next, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer edge of the surface of one of the pair of substrates bearing the liquid crystal alignment film. The substrates were then stacked and pressed together so that the polarization axes projected onto the substrate surfaces during light irradiation were antiparallel. The adhesive was then thermally cured at 150°C for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was injected between the pair of substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, to eliminate flow alignment during liquid crystal injection, the liquid crystal cell was heated to 120°C and then slowly cooled to room temperature. Polarizing plates were then attached to both outer surfaces of the substrates in the liquid crystal cell to obtain a photo-aligned FFS-mode liquid crystal display device. The above series of operations was also performed with a post-baking UV exposure dose of 100 to 10,000 J / m. 2 Three or more liquid crystal display elements with different ultraviolet irradiation doses were manufactured by changing the dose within the range of , and the liquid crystal display element with the exposure dose (optimum exposure dose) that showed the best alignment characteristics was used for the following evaluation.

[0123] 9. Evaluation of Charge Storage (RDC) The photo-aligned FFS-mode liquid crystal display element produced in the above 8. was evaluated by RDC measurement in the same manner as in the above 6. As a result, this example was evaluated as "Fair (◯)".

[0124] 10. Evaluation of liquid crystal alignment The liquid crystal alignment property of the photo-aligned FFS-mode liquid crystal display element produced in the above 8. was evaluated in the same manner as in the above 7. As a result, this example was evaluated as "good (A)".

[0125] [Examples 2 to 13 and Comparative Examples 1 to 6] A liquid crystal alignment agent was prepared in the same manner as in Example 1, except that the composition of the liquid crystal alignment agent was changed as shown in Table 3. Furthermore, using the obtained liquid crystal alignment agent, an FFS-type liquid crystal cell and an FFS-type liquid crystal display element were produced in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3. In Examples 5 to 12 and Comparative Example 3, two types of polymers were used as the polymer component. In Example 13, three types of polymers were used as the polymer component. In Examples 4 and 6, the FFS-type liquid crystal display element was produced by a rubbing method, and no FFS-type liquid crystal display element was produced by a photoalignment method. In Table 3, the numerical values ​​in the polymer column represent the blending ratio (parts by mass) of the solid content of each polymer relative to 100 parts by mass of the total amount of the polymer components used in preparing the liquid crystal alignment agent.

[0126] [Table 3]

[0127] As shown in Table 3, the liquid crystal alignment agents of Examples 1 to 13 were all evaluated as good or fair in terms of film adhesion, high-temperature and high-humidity resistance, and film strength, and had a good balance of various properties. In addition, the liquid crystal alignment films formed using the liquid crystal alignment agents of Examples 1 to 13 had little accumulated charge and good liquid crystal alignment properties.

[0128] In contrast, Comparative Example 1, in which polyamic acid (P) was used instead of polyimide (P), produced a film with poor high-temperature and high-humidity resistance. Furthermore, Comparative Examples 2 to 6, in which polyimides lacking either or both of the structural unit (I) and the structural unit (II) were used, produced films with poor adhesion, high-temperature and high-humidity resistance, and film strength.

Claims

1. A structural unit (I) having a partial structure represented by the following formula (1) and an alkylene structure having 5 or more carbon atoms or at least one methylene group of the alkylene structure having 5 or more carbon atoms are not adjacent to each other, and are -COO-, -OCO-, -O-, -CO-NR ４ -, -NR ４ —CO—, —NR ４ - and -CO- are replaced by the same or different groups selected from the group consisting of ４ is a hydrogen atom or a monovalent organic group, and a polyimide containing a structural unit (II) having the structural unit (II) (excluding the structural unit (I)). 【Chemistry 1】 (In formula (1), Ar １ and Ar ２ are each independently a divalent aromatic ring group. １ and X ２ are each independently -NR ２ -, -O-, -S-, * １ -NR ２ -CO- or * １ -O-CO-. １ " is Ar １ or Ar ２ R represents a bond bonded to １ represents an alkanediyl group having two or more carbon atoms or an alkanediyl group having two or more carbon atoms with -NR between the carbon-carbon bonds thereof ３ -, -O-, -S-, -CO-NR ３ -, -NR ３ R is a divalent group containing —CO—, —COO—, or —OCO—. ２ and R ３ are each independently a hydrogen atom or a monovalent organic group. "*" represents a bond.

2. The liquid crystal aligning agent according to claim 1 , wherein the imidization rate of the polyimide is 30% or more.

3. The structural unit (II) is a —COO—, —OCO—, —O—, or —CO—NR alkylene structure having 5 or more carbon atoms or at least one methylene group in the alkylene structure having 5 or more carbon atoms, provided that these methylene groups are not adjacent to each other. ４ａ -, -NR ４ａ —CO—, —NR ４ - and -CO- are replaced by the same or different groups selected from the group consisting of ４ is a hydrogen atom or a monovalent organic group. ４ａ The liquid crystal aligning agent according to claim 1 , wherein:

4. The liquid crystal aligning agent according to claim 1, further comprising a polymer that includes a structural unit having a partial structure represented by the following formula (3), the polymer being different from the polyimide: 【Chemistry 2】 (In formula (3), Ar ３ , Ar ４ and R ５ satisfies the following (i), (ii), or (iii): (i) Ar ３ and Ar ４ are each independently a divalent aromatic ring group. ５ is a hydrogen atom or a monovalent organic group. (ii) Ar ３ and Ar ４ are combined together to form Ar ３ an aromatic ring having —NR ５ - and Ar ４ represents a nitrogen-containing condensed ring structure formed together with the aromatic ring possessed by ５ is a hydrogen atom or a monovalent organic group. (iii) Ar ３ and R ５ are combined together to form Ar ３ an aromatic ring having R ５ and R ５ represents a nitrogen-containing fused ring structure formed together with the nitrogen atom to which Ar is bonded. ４ is a divalent aromatic ring group. "*" indicates a bond.)

5. The liquid crystal aligning agent according to claim 1, further comprising at least one polymer (Q) selected from the group consisting of polyamic acids and polyamic acid esters.

6. The liquid crystal aligning agent according to claim 5 , wherein the polymer (Q) contains a polymer containing a structural unit having a partial structure represented by the following formula (3): 【Transformation 3】 (In formula (3), Ar ３ , Ar ４ and R ５ satisfies the following (i), (ii), or (iii): (i) Ar ３ and Ar ４ are each independently a divalent aromatic ring group. ５ is a hydrogen atom or a monovalent organic group. (ii) Ar ３ and Ar ４ are combined together to form Ar ３ an aromatic ring having -NR ５ - and Ar ４ represents a nitrogen-containing condensed ring structure formed together with the aromatic ring possessed by ５ is a hydrogen atom or a monovalent organic group. (iii) Ar ３ and R ５ are combined together to form Ar ３ an aromatic ring having R ５ and R ５ represents a nitrogen-containing fused ring structure formed together with the nitrogen atom to which Ar is bonded. ４ is a divalent aromatic ring group. "*" indicates a bond.)

7. A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of claims 1 to 6.

8. A liquid crystal device comprising the liquid crystal alignment film according to claim 7 .

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