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

Abstract

To provide a liquid crystal alignment agent that yields a liquid crystal alignment film exhibiting good liquid crystal alignment properties while possessing insulating film resistance, and further yields a liquid crystal element with superior contrast. [Solution] The polymer (P) has a weight-average molecular weight of 5,000 or more, and has a substructure (a1) represented by formula (1) and at least one substructure (a2) selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having one or two nitrogen atoms, a substructure represented by formula (2) and a substructure represented by formula (3), either in the same molecule or in different molecules; and a compound (A) has a molecular weight of less than 5,000, and has a total of two or more of at least one group selected from the group consisting of a (meth)acryloyl group, a vinylphenyl group and a maleimide group in one molecule. TIFF2026144965000031.tif8169 TIFF2026144965000032.tif38169

Description

[Technical Field]

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element. [Background technology]

[0002] Liquid crystal elements are widely used in televisions, mobile devices, and various monitors. With this increasing versatility, there is a growing demand for higher quality liquid crystal elements. Improvements are being made to the driving method and element structure, as well as to the liquid crystal alignment film, one of the constituent materials of liquid crystal elements.

[0003] To satisfy the demand for higher quality liquid crystal elements, techniques have been proposed to suppress the reduction in contrast (see, for example, Patent Document 1). Patent Document 1 discloses that a liquid crystal alignment agent may contain at least one polymer selected from the group consisting of a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing 3,3',4,4'-biphenyltetracarboxylic dianhydride with a diamine component containing a diamine having at least one structure selected from the group consisting of an amino group, an imino group, and a nitrogen-containing heterocycle, and an imidized polymer of said polyamic acid. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2015 / 050135 [Overview of the project] [Problems that the invention aims to solve]

[0005] By incorporating a crosslinking agent into the liquid crystal alignment agent, the mechanical strength of the liquid crystal alignment film is improved, which makes it possible to suppress display defects caused by, for example, peeling of the liquid crystal alignment film. However, when a crosslinking agent is incorporated into the liquid crystal alignment agent, the liquid crystal alignment properties of the liquid crystal alignment film tend to decrease, raising concerns that bright spots may easily occur in the liquid crystal elements. In addition, in liquid crystal alignment films, coarse particles may form on the film surface due to low molecular weight components in or on the film surface (e.g., unreacted crosslinking agents or polymerizable compounds), which can lead to increased surface irregularities. In this case, light is scattered by the surface irregularities, which can easily cause a decrease in white brightness and an increase in black brightness in the liquid crystal elements, raising concerns that contrast may decrease.

[0006] Furthermore, in high-definition liquid crystal panels such as 4K and 8K equipped with an insulating film, ionic impurities originating from the insulating film may leach into the liquid crystal through the liquid crystal alignment film. The leaching of ionic impurities into the liquid crystal raises concerns about a decrease in the quality of the liquid crystal elements, such as a reduction in voltage retention and an increase in accumulated charge. Therefore, the liquid crystal alignment film is required to have the ability to suppress the leaching of ionic impurities originating from the insulating film into the liquid crystal (hereinafter also referred to as "insulating film resistance").

[0007] To further improve the quality of liquid crystal elements, it is necessary to maintain good liquid crystal alignment while suppressing the decrease in contrast of the liquid crystal elements, and in addition, for the liquid crystal alignment film to have insulating film resistance. However, improving any one of these performance aspects will degrade others, making it difficult to improve all performance aspects simultaneously. Therefore, there is still room for further improvement in liquid crystal alignment agents and liquid crystal elements.

[0008] The present invention has been made in view of the above problems, and one of its objectives is to provide a liquid crystal alignment agent that can obtain a liquid crystal alignment film that exhibits good liquid crystal alignment properties and has insulating film resistance, and furthermore, can obtain a liquid crystal element with excellent contrast. [Means for solving the problem]

[0009] According to the present invention, the following liquid crystal alignment agents, liquid crystal alignment films and liquid crystal elements are provided.

[0010] [1] A polymer (P) having a partial structure (a1) represented by the following formula (1) and at least one partial structure (a2) selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having 1 or 2 nitrogen atoms, a partial structure represented by the following formula (2), and a partial structure represented by the following formula (3), in the same molecule or different molecules, and having a weight average molecular weight of 5,000 or more; and a compound (A) having a total of two or more of at least one group selected from the group consisting of a (meth)acryloyl group, a vinylphenyl group and a maleimide group in one molecule, and having a molecular weight of less than 5,000; a liquid crystal alignment agent comprising the same.

Chemical Formula

Chemical Formula

[0011] According to the liquid crystal alignment agent of the present invention, a liquid crystal alignment film can be obtained that exhibits good liquid crystal alignment properties while also having insulating film resistance. Furthermore, according to the liquid crystal alignment agent of the present invention, a liquid crystal element with excellent contrast can be obtained. [Brief explanation of the drawing]

[0012] [Figure 1] A diagram showing the electrode patterns of the transparent electrode films used in the examples and comparative examples. [Modes for carrying out the invention]

[0013] The following details the aspects of this disclosure.

[0014] In this specification, numerical ranges indicated using "~" include the values ​​indicated before and after "~" as the lower and upper limits, respectively. A "structural unit" is a unit that primarily constitutes the main chain structure and is present in at least two units within the main chain structure. Structural units are typically monomeric units. However, compounds obtained by reacting a monomeric unit having a reactive group with a compound having a functional group that can react with said reactive group are also included as "structural units."

[0015] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include those that have a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may include a linear structure or an alicyclic hydrocarbon structure as part of it. "Aromatic ring" means an aromatic hydrocarbon ring and an aromatic heterocycle. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0016] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which consists of the longest chain of atoms. This "trunk" portion may contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. "Side chains" refer to the parts of a polymer that branch off from the "trunk". "(meth)acrylic" is a term that encompasses acrylic and methacrylic, "(meth)acryloyl" is a term that encompasses acryloyl and methacryloyl, and "(meth)acryloxy" is a term that encompasses acryloxy and methacryloxy.

[0017] Liquid crystal alignment agent The liquid crystal alignment agent of this disclosure contains a polymer (hereinafter also referred to as "polymer (P)") having a specific substructure and a weight-average molecular weight of 5,000 or more, and a compound (hereinafter also referred to as "compound A") having two or more specific groups in one molecule and a molecular weight of less than 5,000. The polymer (P), compound (A), and other components that may be optionally added as needed are described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0018] <Polymer (P)> Polymer (P) is a polymer having a substructure represented by the following formula (1) (hereinafter also referred to as "substructure (a1)") and at least one substructure selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having one or two nitrogen atoms, a substructure represented by the following formula (2), and a substructure represented by the following formula (3), either within the same molecule or in different molecules, and having a weight-average molecular weight of 5,000 or more. [ka] (In formula (1), R 1 This is a monovalent group consisting of a hydrogen atom, a substituted or unsubstituted monovalent linear hydrocarbon group, or any methylene group in the linear hydrocarbon group being replaced with -O-. 1 , A 2 and A 3 Each of these is independently a substituted or unsubstituted divalent hydrocarbon ring group. 1 and X 2 These are, independently, single bonds, alkanediyl groups with 1 to 3 carbon atoms, -CO-O-, and -CO-NR. 2 -, or any methylene group in a carbon-2 or carbon-3 alkanediyl group is -O- or -NR 2 - is a divalent group formed by substitution. 2 A is a hydrogen atom or a monovalent organic group. n is an integer from 0 to 2. If n is 2, then two A 2 They are the same or different, two X2 They are either the same or different. (* represents a combination.) [ka] (In equations (2) and (3), Y 1 Y is a hydrogen atom or a monovalent thermally leaving group. 2 R is a monovalent thermally leaving group. 3 R is a substituted or unsubstituted divalent hydrocarbon group, or a substituted or unsubstituted divalent heterocyclic group. 4 B is a substituted or unsubstituted divalent chain hydrocarbon group. 1 , ">C(R 6 A group represented by )-, or a substituted or unsubstituted trivalent aromatic ring group. 6 X is a hydrogen atom or a monovalent organic group. 3 is a single bond or a divalent organic group. However, B 1 If is a substituted or unsubstituted trivalent aromatic ring group, then X 3 R is a divalent organic group. 5 (This is a hydrogen atom or a monovalent hydrocarbon group. "*" represents a bond.)

[0019] ·Substructure (a1) Substructure (a1) is the substructure represented by the above formula (1). In the above equation (1), R 1 The monovalent linear hydrocarbon group represented by may be linear or branched. From the viewpoint of improving liquid crystal orientation, it is preferable that it be linear. The number of carbon atoms in the monovalent linear hydrocarbon group may be 1 or more, preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. Furthermore, the number of carbon atoms in the monovalent linear hydrocarbon group is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. R 1 When the substituent is a substituted monovalent linear hydrocarbon group, examples of substituents include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), cyano groups, nitro groups, hydroxyl groups, carboxyl groups, and the like.

[0020] R 1Specific examples of monovalent chain hydrocarbon groups represented by include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, 2-butyl group, isobutyl group, tert-butyl group, n-pentyl group, 2-pentyl group, 3-pentyl group, 1-hexyl group, 2-hexyl group, 1-octyl group, 2-octyl group, 1-decyl group, 1-dodecyl group, 1-tetradecyl group, 1-hexadecyl group, 1-octadecyl group, and 1-eicosyl group.

[0021] R 1 Preferably, the group is a substituted or unsubstituted monovalent linear hydrocarbon group, or a monovalent group in which any methylene group in the linear hydrocarbon group is replaced with -O-, and more preferably a substituted or unsubstituted monovalent linear hydrocarbon group.

[0022] A 1 , A 2 and A 3 The divalent hydrocarbon ring group represented by is a divalent group obtained by removing any two hydrogen atoms from an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring. Examples of aliphatic hydrocarbon rings include monocyclic rings such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, and cyclodecane rings; and condensed rings such as decahydronaphthalene and hexadecahydropyrene rings. Examples of aromatic hydrocarbon rings include benzene, naphthalene, anthracene, and phenanthrene rings. 1 , A 2 and A 3 If the substituent is a substituted divalent hydrocarbon ring group, examples of substituents include halogen atoms, C1-C5 alkyl groups, and C1-C5 alkoxy groups. A 1 , A 2 and A 3 As for the divalent hydrocarbon ring group represented by , from the viewpoint of improving liquid crystal orientation, a divalent group obtained by removing any two hydrogen atoms from a cyclopentane ring, cyclohexane ring, benzene ring, or naphthalene ring is preferred, and a divalent group obtained by removing any two hydrogen atoms from a cyclohexane ring or benzene ring is more preferred.

[0023] X 1 and X 2 Of the above, from the viewpoint of improving liquid crystal alignment, it is preferable that the group is a divalent group in which any methylene group in a single bond, a carbon 1-3 alkanediyl group, -CO-O-, or a carbon 2 or 3 alkanediyl group is replaced with -O-, and it is more preferable that the group is a single bond, a carbon 1-3 alkanediyl group, or -CO-O-. In this specification, "-CO-O-" and "-CO-NR" are used. 2 When functional groups are represented as "-", the orientation of these functional groups is not specified. For example, X 1 If it is "-CO-O-", then "-CO-O-" is "* 1 -CO-O-" and "* 1 -O-CO- ("* 1 " is A 1 This represents a combination with . ) Either of these is acceptable.

[0024] R 2 Examples of monovalent organic groups represented by include monovalent hydrocarbon groups having 1 to 10 carbon atoms and monovalent thermally desorbable groups. Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms include monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 10 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms. Examples of monovalent thermally detachable groups include tert-butoxycarbonyl group (Boc group), benzyloxycarbonyl group, 1,1-dimethyl-2-haloethyloxycarbonyl group, allyloxycarbonyl group, 2-(trimethylsilyl)ethoxycarbonyl group, and 9-fluorenylmethyloxycarbonyl group (F-moc group). Of these, the Boc group is preferred because it exhibits excellent thermal detachment properties and allows for a small amount of residual structure in the film after detachment. 2 Preferably, the elements are a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a Boc group. n is preferably 0 or 1.

[0025] Examples of substructures (a1) include structures represented by equations (s-1) to (s-8) below. [ka] (In formulas (s-1) to (s-8), R 2 (This represents a hydrogen atom or a monovalent organic group. * indicates a bond.)

[0026] The substructure (a1) is preferably bonded to an atom constituting the main chain of the polymer (P) via a divalent organic group. Examples of such divalent organic groups include divalent linear hydrocarbon groups having 1 to 5 carbon atoms, -O-, -CO-, -CO-O-, and divalent groups in which any methylene group in a divalent linear hydrocarbon group having 2 to 5 carbon atoms is replaced with -O-, -CO-, or -CO-O-. Among these, linear hydrocarbon groups having 1 to 3 carbon atoms, -O-, -CO-, or -CO-O- are preferred.

[0027] ·Partial structure (a2) Substructure (a2) is at least one substructure selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having one or two nitrogen atoms (hereinafter also referred to as "substructure (NA)"), a substructure represented by formula (2) above (hereinafter also referred to as "substructure (NB)"), and a substructure represented by formula (3) above (hereinafter also referred to as "substructure (NC)"). Among these, substructure (NA) is preferred from the viewpoint of improving the dielectric strength of the insulating film.

[0028] The substructure (NA) has a nitrogen-containing aromatic heterocycle having one or two nitrogen atoms. This nitrogen-containing aromatic heterocycle may be a monocycle or a fused ring. If the nitrogen-containing aromatic heterocycle of the substructure (NA) is a fused ring, the total number of nitrogen atoms of the multiple rings constituting the fused ring may be 1 or 2. Therefore, as long as the fused ring as a whole exhibits aromaticity, only one of the multiple rings constituting the fused ring may have one or two nitrogen atoms, or two rings may each have one nitrogen atom.

[0029] A nitrogen-containing aromatic heterocycle having one or two nitrogen atoms may have only nitrogen atoms as heteroatoms, or it may further have heteroatoms other than nitrogen atoms. Specifically, examples of aromatic heterocycles having only nitrogen atoms as heteroatoms include pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, pyrrole rings, pyrazole rings, imidazole rings, benzimidazole rings, indazole rings, quinoline rings, isoquinoline rings, carbazole rings, acridine rings, etc.; examples of aromatic heterocycles having nitrogen atoms and oxygen atoms include oxazole rings, isoxazole rings, etc.; and examples of aromatic heterocycles having nitrogen atoms and sulfur atoms include thiazole rings, isothiazole rings, etc. Among these, aromatic heterocycles having only nitrogen atoms as heteroatoms are preferred in terms of obtaining liquid crystal alignment films with excellent insulating film resistance, and pyridine rings, pyrrole rings, imidazole rings, and benzimidazole rings are more preferred.

[0030] The nitrogen-containing aromatic heterocycle of the substructure (NA) may have substituents. Examples of such substituents include those described above (A). 1 The description of substituents in the above applies. Furthermore, the nitrogen atom of the nitrogen-containing aromatic heterocycle may be protected by a monovalent thermally leaving group. The monovalent thermally leaving group is the above R. 2 The explanation of monovalent thermally leaving groups represented by applies.

[0031] A substructure (NA) is represented as a substructure obtained by removing any n hydrogen atoms from the ring portion of a substituted or unsubstituted nitrogen-containing aromatic heterocycle (where the nitrogen-containing aromatic heterocycle has one or two nitrogen atoms) (where n is an integer of 1 or more). Specifically, examples of substructures (NA) include the structures represented by the following formulas (NA-1) to (NA-8). [ka] (In equations (NA-1) to (NA-8), R 11 is a substituent. n1 is an integer from 0 to 4. n2 is an integer from 0 to 3. n3 is an integer from 0 to 2. n4 is an integer from 0 to 6. R11 If there are multiple R 11 They are either the same or different. (* represents a combination.)

[0032] In the above equations (NA-1) to (NA-8), R 11 The substituent represented by the above A is 1 The description of substituents in the following context applies. n1 is preferably an integer between 0 and 2, and more preferably 0 or 1. n2 is preferably 0 or 1. n3 is preferably 0 or 1. n4 is preferably an integer between 0 and 4, and more preferably an integer between 0 and 2.

[0033] In the above equations (2) and (3), Y 1 and Y 2 The monovalent thermally desorbable group represented by the above R is 2 The explanation of monovalent thermally leaving groups represented by applies. Y 1 From the viewpoint of improving the solubility of polymer (P) in solvents, it is preferable that the group is a monovalent thermally detachable group.

[0034] R 3 Examples of divalent hydrocarbon groups represented by include chain hydrocarbon groups having 1 to 10 carbon atoms, alicyclic hydrocarbon groups having 3 to 10 carbon atoms, and aromatic hydrocarbon groups having 6 to 12 carbon atoms. 3 If is a substituted divalent hydrocarbon group, the substituent is the above R. 1 The description of substituents in a monovalent chain hydrocarbon group, represented by , applies.

[0035] R 3The divalent heterocyclic group represented by is a divalent group formed by removing any two hydrogen atoms from a heterocyclic ring. Heterocyclic rings include aliphatic heterocyclic rings and aromatic heterocyclic rings. Examples of aliphatic heterocyclic rings include piperidine rings, piperazine rings and the like as nitrogen-containing aliphatic heterocyclic rings; oxetane rings, tetrahydrofuran rings, dioxolane rings and the like as oxygen-containing aliphatic heterocyclic rings; and tetrahydrothiophene rings and the like as sulfur-containing aliphatic heterocyclic rings. Further, examples of aromatic heterocyclic rings include pyridine rings, pyrimidine rings, pyridazine rings, pyrazine rings and the like as nitrogen-containing aromatic heterocyclic rings; furan rings and the like as oxygen-containing aromatic heterocyclic rings; and thiophene rings and the like as sulfur-containing aromatic heterocyclic rings.R 3 is a substituted divalent heterocyclic group, the description of the substituent in the above A 1 applies to the substituent.

[0036] R 4 As the divalent chain hydrocarbon group represented by , a chain hydrocarbon group having 1 to 10 carbon atoms is preferred, a chain hydrocarbon group having 1 to 5 carbon atoms is more preferred, and a chain hydrocarbon group having 1 to 3 carbon atoms is even more preferred.R 4 is a substituted divalent chain hydrocarbon group, the description of the substituent in the monovalent chain hydrocarbon group represented by the above R 1 applies.

[0037] B 1 The trivalent aromatic ring group represented by is a group formed by removing any three hydrogen atoms from an aromatic ring. Aromatic rings include aromatic hydrocarbon rings and aromatic heterocyclic rings. For the aromatic hydrocarbon ring, the description of the aromatic hydrocarbon ring in the description of the above A 1 applies. For the aromatic heterocyclic ring, the description of the aromatic heterocyclic ring in the description of the above R 3 applies.B 1 is a substituted trivalent aromatic ring group, the description of the substituent in the above A 1 applies to the substituent. B 1 as ">C(R 6)-), it is preferably a group represented by or a trivalent aromatic hydrocarbon ring group, and ">C(R 6 )-), it is more preferably a group represented by or a trivalent group formed by removing any three hydrogen atoms from a benzene ring.

[0038] R 6 As the monovalent organic group represented by, the above R 2 description applies. R 6 is preferably a hydrogen atom or a chain hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrogen atom or a chain hydrocarbon group having 1 to 3 carbon atoms.

[0039] X 3 As the divalent organic group represented by, a chain hydrocarbon group having 1 to 10 carbon atoms, and any methylene group in the chain hydrocarbon group is -O-, -CO-, -CO-O- or -NR 7 A divalent group formed by substitution with -CO- can be mentioned. R 7 is a monovalent organic group. As the monovalent organic group, the above R 2 description applies. X 3 is preferably a single bond or a chain hydrocarbon group having 1 to 10 carbon atoms, more preferably a single bond or a chain hydrocarbon group having 2 to 10 carbon atoms, and still more preferably a single bond or a chain hydrocarbon group having 2 to 5 carbon atoms.

[0040] R 5 As the monovalent hydrocarbon group represented by, monovalent hydrocarbon groups having 1 to 10 carbon atoms can be mentioned. As the monovalent hydrocarbon group having 1 to 10 carbon atoms, the above R 2 description of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by applies. R 5 is preferably a hydrogen atom or a chain hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrogen atom or a chain hydrocarbon group having 1 to 3 carbon atoms.

[0041] The polymer (P) may have substructure (a1) and substructure (a2) within the same molecule or within different molecules. Specifically, examples of the polymer (P) include [1] a polymer having substructure (a1) and substructure (a2) within the same molecule, and [2] an embodiment comprising a first polymer having substructure (a1) but not substructure (a2), and a second polymer having substructure (a2) but not substructure (a1). From the viewpoint of improving insulating film resistance, [1] is preferred.

[0042] ·Partial structure (a3) The polymer (P) may further have a substructure containing a radical generating group (hereinafter also referred to as "substructure (a3)"). By introducing substructure (a3) ​​into the polymer (P), it is possible to further improve the contrast of the liquid crystal element while ensuring good liquid crystal alignment. A radical generating group is a group that generates radicals when stimulated (preferably by light or heat). Specific examples of radical generating groups include photoradical generating agents such as alkylphenone compounds, benzoin compounds, ketal compounds, acetophenone compounds, thioxanthone compounds, and anthraquinone compounds; and thermal radical generating agents such as peroxides and azo compounds; and groups having structures derived from these. Among these, groups having structures derived from acetophenone compounds or benzophenone compounds are preferred.

[0043] Specifically, examples of substructures (a3) ​​include structures represented by equations (r-1) to (r-9) below. [ka] (In formulas (r-1) to (r-9), R 12 is a substituent. m1 is an integer from 0 to 4. m2 is an integer from 0 to 5. m3 is an integer from 0 to 3. R 12 If there are multiple R 12 They are either the same or different. "*" represents a coupling.

[0044] In the above equations (r-1) to (r-9), R 12 Examples of substituents represented by include halogen atoms, C1-C10 alkyl groups, and C1-C10 alkoxy groups. m1 is preferably an integer between 0 and 2, and more preferably 0 or 1. m2 is preferably an integer between 0 and 3, and more preferably 0 or 1. m3 is preferably 0 or 1.

[0045] From the viewpoint of improving liquid crystal alignment, contrast, and insulating film resistance in a balanced manner, the polymer (P) is preferably a polymer containing structural units having a substructure (a1) (hereinafter also referred to as "structural unit (U1)") and structural units having a substructure (a2) (hereinafter also referred to as "structural unit (U2)"). The polymer (P) may contain structural unit (U1) and structural unit (U2) in the same molecule or in different molecules. From the viewpoint of improving insulating film resistance, it is preferable that the polymer (P) contains structural unit (U1) and structural unit (U2) in the same molecule.

[0046] When the polymer (P) contains structural units (U1), the content of structural units (U1) in the polymer (P) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to the total structural units of the polymer (P). Furthermore, the content of structural units (U1) in the polymer (P) is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less, relative to the total structural units of the polymer (P).

[0047] When the polymer (P) contains structural units (U2), the content of structural units (U2) in the polymer (P) is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total structural units of the polymer (P). Furthermore, the content of structural units (U2) in the polymer (P) is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less, relative to the total structural units of the polymer (P).

[0048] When the polymer (P) has a substructure (a3), it is preferable that the polymer (P) is a polymer that contains structural units having the substructure (a3) ​​(hereinafter also referred to as "structural units (U3)"). When the polymer (P) contains structural units (U3), the content of structural units (U3) in the polymer (P) is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, relative to the total structural units of the polymer (P). Furthermore, the content of structural units (U3) in the polymer (P) is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, relative to the total structural units of the polymer (P).

[0049] The weight-average molecular weight (Mw) of polymer (P) should be 5,000 or more. If the weight-average molecular weight (Mw) of polymer (P) is less than 5,000, the surface irregularities of the liquid crystal alignment film formed by polymer (P) tend to increase, and the contrast of the liquid crystal element tends to decrease. The weight-average molecular weight (Mw) of polymer (P) is a polystyrene-converted value measured by gel permeation chromatography (GPC). If polymer (P) contains two or more types of polymers, the weight-average molecular weight (Mw) of each polymer should be 5,000 or more. For example, if polymer (P) consists of a first polymer and a second polymer, the Mw of both the first polymer and the second polymer should be 5,000 or more. From the viewpoint of reducing the surface irregularities of the liquid crystal alignment film and improving the contrast of the liquid crystal element, the weight-average molecular weight (Mw) of polymer (P) is preferably 6,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more. Furthermore, the weight-average molecular weight (Mw) of the polymer (P) is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 100,000 or less, from the viewpoint of improving the contrast of the liquid crystal element and improving the solubility of the polymer (P) in the solvent.

[0050] Polymer (P) may be any polymer having substructure (a1) and substructure (a2) within the same molecule or in different molecules, and having a weight-average molecular weight of 5,000 or more, and its main skeleton is not particularly limited. Examples of main skeletons include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and addition polymers. Addition polymers are polymers that contain structural units derived from monomers having polymerizable unsaturated carbon-carbon bonds, and examples include styrene polymers, (meth)acrylic polymers, maleimide polymers, (meth)acrylic-styrene copolymers, (meth)acrylic-maleimide copolymers, (meth)acrylic-styrene-maleimide copolymers, and styrene-maleimide copolymers.

[0051] As the main skeleton of the polymer (P), it is preferable that it is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and addition polymer, from the viewpoint of having high affinity with liquid crystals and mechanical strength, and being able to form a highly reliable liquid crystal alignment film. In particular, from the viewpoint of obtaining better liquid crystal alignment and reliability, it is more preferable that it is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and even more preferable that it is at least one selected from the group consisting of polyamic acid and polyimide. The method for producing polyamic acid, polyamic acid ester, polyimide, and addition polymer as polymer (P) is not particularly limited and can be produced by appropriately combining standard organic chemistry methods. The following describes polyamic acid, polyamic acid ester, polyimide, and addition polymer as polymer (P).

[0052] [Polyamic acid] Polyamic acid (hereinafter also referred to as "polyamic acid (P)") as a polymer (P) can be obtained by using tetracarboxylic dianhydride, a diamine having substructure (a1) (hereinafter also referred to as "specific diamine (A)"), and a diamine having substructure (a2) (hereinafter also referred to as "specific diamine (B)").

[0053] (Tetracarboxylic acid dianhydride) Examples of tetracarboxylic dianhydrides used in the synthesis of polyamic acids (P) include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Examples of aliphatic tetracarboxylic dianhydrides include linear tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0054] Specific examples of these include linear tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride; Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1, 2-c]furan-1,3-dione, 3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, 4,9-dioxatricyclo[5.3.1.0 2,6 Undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride, etc. Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-carbonyl diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, etc., as well as the tetracarboxylic dianhydride described in Japanese Patent Application Publication No. 2010-97188.

[0055] As for the tetracarboxylic dianhydride, it is preferable that it includes an alicyclic tetracarboxylic dianhydride in order to increase the solubility of the polymer and to obtain a liquid crystal alignment film that exhibits good electrical properties. Furthermore, among the alicyclic tetracarboxylic dianhydrides, it is preferable that it includes 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, and 1,2,3,4-cyclobutane It is preferable that the product contains at least one selected from the group consisting of tracarboxylic acid dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and it is particularly preferable that the product contains at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride.

[0056] When alicyclic tetracarboxylic dianhydrides are included as tetracarboxylic dianhydrides, the content of alicyclic tetracarboxylic dianhydrides is preferably 10 mol% or more, and more preferably 20 to 100 mol%, relative to the total amount of tetracarboxylic dianhydrides used in the synthesis of polyamic acids.

[0057] (Diamine) For the synthesis of polyamic acid (P), specific diamines (A) and specific diamines (B) can preferably be used. Examples of specific diamines (A) and specific diamines (B) include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes, with aromatic diamines being preferred.

[0058] The specific diamine (A) is preferably a compound in which the substructure (a1) is bonded to a diaminophenyl group via a divalent organic group. The description of the divalent organic group in the description of the substructure (a1) above applies to the divalent organic group. The two amino groups in the diaminophenyl group are preferably located at the 2,4- or 3,5-positions relative to the other group.

[0059] Specific examples of the specified diamine (A) include compounds represented by formulas (A-1) to (A-9) below. [ka] [ka] (In formula (A-5), R 2 (This is a hydrogen atom or a monovalent organic group.)

[0060] The specific diamine (B) may be any diamine having the above-described substructure (a2), and may have one substructure (a2) or two or more. From the viewpoint of improving insulating film resistance, it is preferable to have 1 to 6 substructures, and more preferably 1 to 4 substructures. From the viewpoint of further improving insulating film resistance, the substructure (a2) of the specific diamine (B) is preferably substructure (NA).

[0061] Specific examples of the specified diamine (B) include, for example, compounds represented by formulas (B-1) to (B-7) below, as having a substructure (NA); for example, compounds represented by formula (B-4) below, and compounds represented by formulas (B-8) to (B-10) below, as having a substructure (NB); and for example, compounds represented by formulas (B-11) to (B-16) below, as having a substructure (NC). In the structural formulas, "Boc" represents a tert-butoxycarbonyl group (the same applies below). [ka] [ka] [ka]

[0062] The diamines used in the synthesis of polyamic acid (P) may be limited to the specified diamines (A) and (B) described above, but other diamines (hereinafter also referred to as "other diamines") may also be used. Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Aliphatic diamines include linear diamines and alicyclic diamines.

[0063] Other specific examples of diamines include chain-like diamines such as metaxylylenediamine and 1,3-bis(aminomethyl)cyclohexane; Examples of alicyclic diamines include 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine);

[0064] Aromatic diamines include, for example, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)propane, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)-piperazine, and 1-(4-aminophenyl)-2,3-dihydroxy Diro-1,3,3-trimethyl-1H-indene-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine, 3,5-diaminobenzoic acid, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostanyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 2,4-diamino-N,N-diallylaniline, 4-aminobenzylamine, and cinnamic acid structure-containing diamines, etc. Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and diamines described in Japanese Patent Publication No. 2010-97188 can also be used.

[0065] When synthesizing polyamic acids (P) having substructure (a3), they can be obtained by using specific diamines (A) and specific diamines (B), as well as a diamine having substructure (a3) ​​(hereinafter also referred to as "specific diamine (C)"). It is preferable that the specific diamine (C) can have substructure (a3) ​​introduced into the side chain of the polymer (P), and specific examples include compounds represented by formulas (C-1) to (C-3) below. [ka]

[0066] In the synthesis of polyamic acid (P), the proportion of specific diamine (A) used is preferably 3 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more, relative to the total amount of diamine used in the synthesis of polyamic acid (P), from the viewpoint of improving liquid crystal alignment. Furthermore, from the viewpoint of improving insulating film resistance, the proportion of specific diamine (A) used is preferably 80 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less, and particularly preferably 50 mol% or less, relative to the total amount of diamine used in the synthesis of polyamic acid (P).

[0067] From the viewpoint of improving insulating film resistance while exhibiting good liquid crystal alignment properties, the proportion of specific diamine (B) used is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and particularly preferably 20 mol% or more, relative to the total amount of diamine used in the synthesis of polyamic acid (P). Furthermore, the proportion of specific diamine (B) used is preferably 80 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less, and particularly preferably 50 mol% or less, relative to the total amount of diamine used in the synthesis of polyamic acid (P).

[0068] (Synthesis of polyamic acids) Polyamic acid (P) can be obtained by reacting a tetracarboxylic dianhydride and a diamine as described above, together with a molecular weight modifier as needed. The ratio of tetracarboxylic dianhydride and diamine used in the synthesis reaction of polyamic acid (P) is preferably such that the acid anhydride groups of the tetracarboxylic dianhydride are in the proportion of 0.2 to 2 equivalents, and more preferably 0.3 to 1.2 equivalents, per 1 equivalent of the amino groups of the diamine.

[0069] 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 proportion of molecular weight modifier used is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the total amount of tetracarboxylic dianhydride and diamine used.

[0070] The synthesis reaction of polyamic acids is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, and more preferably 0.5 to 12 hours.

[0071] Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Of these organic solvents, it is preferable to use one or more selected from the group consisting of aprotic polar solvents and phenolic solvents (organic solvents of group 1), or a mixture of one or more selected from organic solvents of group 1 and one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (organic solvents of group 2). In the latter case, the proportion of organic solvents of group 2 used is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to the total amount of organic solvents of group 1 and group 2.

[0072] Particularly preferred organic solvents are one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoryltriamide, m-cresol, xylenol, and halogenated phenol, or a mixture of one or more of these and other organic solvents within the above proportion range. The amount of organic solvent used (x) is preferably such that the total amount of tetracarboxylic dianhydride and diamine (y) is 0.1 to 50% by mass of the total amount of the reaction solution (x+y).

[0073] As described above, a reaction solution is obtained by dissolving polyamic acid. This reaction solution may be used as is for the preparation of a liquid crystal alignment agent, or the polyamic acid contained in the reaction solution may be isolated and then used for the preparation of the liquid crystal alignment agent, or the isolated polyamic acid may be purified and then used for the preparation of the liquid crystal alignment agent. When dehydrating and cyclizing the polyamic acid to obtain polyimide, the above reaction solution may be used as is for the dehydration and cyclization reaction, or the polyamic acid contained in the reaction solution may be isolated and then used for the dehydration and cyclization reaction, or the isolated polyamic acid may be purified and then used for the dehydration and cyclization reaction. The isolation and purification of polyamic acid can be carried out according to known methods.

[0074] [Polyamic acid ester] Polyamic acid esters as polymers (P) can be obtained, for example, by [I] reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine, [III] reacting a tetracarboxylic acid dihalide with a diamine, etc. The polyamic acid ester to be contained in the liquid crystal alignment agent may have only an amic acid ester structure, or it may be a partially esterified product in which both an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving the polyamic acid ester may be used as is for the preparation of the liquid crystal alignment agent, or the polyamic acid ester contained in the reaction solution may be isolated and then used for the preparation of the liquid crystal alignment agent, or the isolated polyamic acid ester may be purified and then used for the preparation of the liquid crystal alignment agent. Isolation and purification of polyamic acid esters can be carried out according to known methods.

[0075] [Polyimide] Polyimide as the polymer (P) can be obtained, for example, by dehydrating and cyclizing the polyamic acid (P) synthesized as described above to imidize it.

[0076] The polyimide may be a fully imidized product obtained by dehydrating and cyclizing all of the amic acid structure present in its precursor, polyamic acid (P), or it may be a partially imidized product in which only a portion of the amic acid structure is dehydrated and cyclized, resulting in the coexistence of amic acid and imide ring structures. The polyimide contained in the liquid crystal alignment agent of this disclosure preferably has an imidation rate of 20% or more, more preferably 30-90%, and even more preferably 40-80%. In particular, an imidation rate of 60% or less is preferred. This imidation rate is expressed as a percentage of the ratio of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide. Here, a portion of the imide ring may be an isoimide ring.

[0077] Dehydration and ring closure of polyamic acid (P) is preferably carried out by heating the polyamic acid (P), or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration and ring closure catalyst to the solution, and heating as necessary.

[0078] In a method of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of polyamic acid (P), the dehydrating agent can be an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. The amount of dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of polyamic acid (P). As the dehydration ring-closing catalyst, a tertiary amine such as pyridine, colidine, lutidine, triethylamine, or 1-methylpiperidine can be used. The amount of dehydration ring-closing catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of organic solvents used in the dehydration ring-closing reaction include those exemplified as those used in the synthesis of polyamic acid (P). The reaction temperature for the dehydration ring-closing reaction is preferably 0 to 180°C, more preferably 10 to 150°C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

[0079] In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as is for the preparation of the liquid crystal alignment agent, or the dehydrating agent and dehydration ring-closing catalyst may be removed from the reaction solution before preparing the liquid crystal alignment agent, or the polyimide may be isolated before preparing the liquid crystal alignment agent, or the isolated polyimide may be purified before preparing the liquid crystal alignment agent. These purification operations can be carried out according to known methods. In addition, polyimide can also be obtained by imidization of polyamic acid esters.

[0080] [Addition polymer] An addition polymer (hereinafter also referred to as "addition polymer (P)") as polymer (P) is obtained by using a monomer having a substructure (a1) and a group containing a polymerizable unsaturated bond (hereinafter also referred to as "specific monomer (A)"), and a monomer having a substructure (a2) and a group containing a polymerizable unsaturated bond (hereinafter also referred to as "specific monomer (B)"). Examples of groups containing a polymerizable unsaturated bond include (meth)acryloyl groups, vinyl groups, vinylphenyl groups, maleimide groups, etc.

[0081] The specific monomer (A) may be any monomer having a substructure (a1) and a group containing a polymerizable unsaturated bond. In the specific monomer (A), it is preferable that the substructure (a1) is bonded to the group containing the polymerizable unsaturated bond via a divalent organic group. The description of the divalent organic group in the description of the substructure (a1) above applies to the divalent organic group. Specific examples of the specific monomer (A) include, for example, the compounds represented by formulas (1-1) to (1-3) below. [ka]

[0082] The specific monomer (B) can be any monomer having a substructure (a2) and a group containing a polymerizable unsaturated bond. Specific examples include compounds represented by formulas (2-1) to (2-4) below as having substructure (NA); compounds represented by formulas (2-4) and (2-5) below as having substructure (NB); and compounds represented by formulas (2-1), (2-2), and (2-6) below as having substructure (NC). [ka]

[0083] In the synthesis of addition polymer (P), only specific monomer (A) and specific monomer (B) may be used, but monomers that do not have substructure (a1) and substructure (a2) but have a group containing a polymerizable unsaturated bond (hereinafter also referred to as "other monomers") may also be used. Examples of other monomers include compounds having a (meth)acryloyl group, a vinyl group, a vinylphenyl group, a maleimide group, etc.

[0084] Other specific examples of monomers include unsaturated carboxylic acids such as (meth)acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, and vinylbenzoic acid; unsaturated carboxylic acid esters such as alkyl (meth)acrylates (e.g., methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), cycloalkyl (meth)acrylates, benzyl (meth)acrylates, trimethoxysilylpropyl (meth)acrylates, 2-hydroxyethyl (meth)acrylates, glycidyl (meth)acrylates, 3,4-epoxycyclohexylmethyl (meth)acrylates, 3,4-epoxybutyl (meth)acrylates, and 4-hydroxybutyl glycidyl ether (meth)acrylates; and unsaturated polycarboxylic acid anhydrides such as maleic anhydride; and other (meth)acrylic compounds. Aromatic vinyl compounds such as styrene, methylstyrene, divinylbenzene, and 4-(glycidyloxymethyl)styrene; Conjugated diene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene; Examples include maleimide compounds such as N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-(2,5-dioxo-3-pyrrolin-1-yl)benzoic acid, N-(4-glycidyloxyphenyl)maleimide, N-glycidylmaleimide, 3-maleimidobenzoic acid, 3-maleimidopropionic acid, 3-(2,5-dioxo-3-pyrrolin-1-yl)benzoic acid, and methyl 4-(2,5-dioxo-3-pyrrolin-1-yl)benzoate; and others.

[0085] When synthesizing an addition polymer (P) having substructure (a3), it can be obtained by using a monomer having substructure (a3) ​​and a polymerizable unsaturated bond (hereinafter also referred to as "specific monomer (C)") in addition to specific monomer (A) and specific monomer (B). Specific examples of specific monomer (C) include, for example, the compounds represented by formulas (3-1) to (3-3) below. [ka]

[0086] In the synthesis of the addition polymer (P), the proportion of specific monomer (A) used is preferably 3 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of monomers used in the synthesis of the addition polymer (P), from the viewpoint of improving liquid crystal alignment. Furthermore, from the viewpoint of improving insulating film resistance, the proportion of specific monomer (A) used is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less, relative to the total amount of monomers used in the synthesis of the addition polymer (P).

[0087] In the synthesis of the addition polymer (P), the proportion of specific monomer (B) used is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of monomers used in the synthesis of the addition polymer (P), from the viewpoint of improving the insulating film resistance. Furthermore, the proportion of specific monomer (B) used is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, relative to the total amount of monomers used in the synthesis of the addition polymer (P).

[0088] The addition polymer (P) can be obtained, for example, by polymerizing a monomer having a polymerizable unsaturated bond in the presence of a polymerization initiator. Preferred polymerization initiators include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The amount of polymerization initiator used is preferably 0.01 to 30 parts by mass per 100 parts by mass of the total monomer used in the reaction. The polymerization reaction is preferably carried out in an organic solvent. Examples of organic solvents used in the reaction include alcohols, ethers, ketones, amides, esters, and hydrocarbon compounds, with diethylene glycol ethyl methyl ether and propylene glycol monomethyl ether acetate being preferred. The reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of organic solvent used (a) is preferably such that the total amount of monomers used in the reaction (b) is 0.1 to 60% by mass of the total amount of the reaction solution (a + b).

[0089] The polymers (P) obtained as described above, namely polyamic acid, polyamic acid ester, polyimide, and addition polymer, preferably have a solution viscosity of 20 to 1,800 mPa·s when prepared as a 15% by mass solution, and more preferably have a solution viscosity of 50 to 1,500 mPa·s. The solution viscosity (mPa·s) of the polyamic acid, polyamic acid ester, polyimide, and addition polymer was measured at 25°C using an E-type rotational viscometer for a 15% by mass polymer solution prepared using a good solvent (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0090] The content of polyamic acid, polyamic acid ester, polyimide, and addition polymer as polymer (P) in the liquid crystal alignment agent of this disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total amount of solids contained in the liquid crystal alignment agent (components other than the solvent component of the liquid crystal alignment agent).

[0091] <Compound (A)> Compound (A) is a compound having a total of two or more groups (hereinafter also referred to as "specific group F") selected from the group consisting of (meth)acryloyl groups, vinylphenyl groups, and maleimide groups, and having a molecular weight of less than 5,000. Because compound (A) has specific group F which exhibits radical polymerization, it is thought that when compound (A) is incorporated into a liquid crystal alignment agent together with polymer (P), it can react uniformly with low molecular weight components in the liquid crystal alignment film and with polymerizable monomers contained in the liquid crystal in the case of PSA mode, thereby suppressing the formation of coarse particles on the surface of the alignment film. This is presumed to reduce surface irregularities and suppress the reduction in contrast.

[0092] From the viewpoint of improving contrast, the specific group F is preferably a (meth)acryloyl group or a vinylphenyl group, and more preferably a (meth)acryloyl group. From the viewpoint of improving contrast, the total number of specific groups F in compound (A) is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. Furthermore, from the viewpoint of storage stability of the liquid crystal alignment agent, the total number of specific groups F in compound (A) is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less.

[0093] Compound (A) may be a nonpolymer or a polymer. It is preferable that compound (A) be a nonpolymer in that it can provide better insulating film resistance. Hereinafter, a nonpolymer as compound (A) will also be referred to as nonpolymer (A), and a polymer as compound (A) will also be referred to as polymer (A). From the viewpoint of improving contrast, polymer (A) is preferably a polymer that contains structural units having a specific group F (hereinafter also referred to as "structural units (F)"). When polymer (A) contains structural units (F), the content of structural units (F) in polymer (A) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, relative to the total structural units of polymer (A). Furthermore, the content of structural units (F) in polymer (A) is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, relative to the total structural units of polymer (A).

[0094] The main skeleton of polymer (A) is not particularly limited. Examples given in the description of polymer (P) above can be used as the main skeleton of polymer (A). Among these, polyorganosiloxane is preferred from the viewpoint of ease of synthesis of polymers having specific group F.

[0095] The molecular weight of compound (A) may be less than 5,000. From the viewpoint of compound (A) exhibiting sufficient crosslinking properties to improve the contrast of the liquid crystal element, the molecular weight of compound (A) is preferably less than 4,000, more preferably less than 3,000, and even more preferably less than 2,000. Furthermore, the molecular weight of compound (A) is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. When compound (A) is a polymer, the molecular weight of compound (A) represents the weight-average molecular weight (Mw). In this specification, the molecular weight of a polymer is the polystyrene-converted value measured by gel permeation chromatography (GPC).

[0096] From the viewpoint of improving the contrast of the liquid crystal element while exhibiting good liquid crystal alignment properties, compound (A) is preferably a compound that does not have an aromatic ring (hereinafter also referred to as "aliphatic compound (A)"). Aliphatic compound (A) may be a compound consisting of a chain structure or may have an aliphatic ring structure, but it is more preferable that it consists only of a chain structure. Furthermore, from the viewpoint of improving contrast and insulating film resistance, compound (A) is preferably a compound that does not have a substructure represented by the above formula (1).

[0097] Specific examples of nonpolymers (A) include compounds represented by formulas (a-1) to (a-6) below. [ka]

[0098] In the liquid crystal alignment agent, the content of compound (A) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, relative to the total amount of polymer components excluding polymer (A), from the viewpoint of improving contrast while exhibiting good liquid crystal alignment properties. Furthermore, the content of compound (A) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and particularly preferably 10 parts by mass or less, relative to the total amount of polymer components excluding polymer (A).

[0099] <Other ingredients> The liquid crystal alignment agent of this disclosure may contain, in addition to polymer (P) and compound (A), other components as needed. Examples of other components include polymers different from polymer (P) and polymer (A) (hereinafter also referred to as "other polymers"), radical generators (excluding polymer (P) having substructure (a3)), solvents, antioxidants, metal chelating compounds, curing accelerators, surfactants, fillers, dispersants, and the like. The content ratio of the other components can be appropriately selected depending on each compound, as long as it does not impair the effects of the present invention.

[0100] [Other polymers] Other polymers are those that do not have substructures (a1) and (a2), and do not have a total of two or more specific groups F in one molecule, and their main skeleton is not particularly limited. Examples given in the description of polymer (P) above apply to the main skeleton of other polymers. In particular, polymers (hereinafter also referred to as "polymer (Q)") that are at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, addition polymer, and polyorganosiloxane are preferred from the viewpoint of having high affinity with liquid crystal when used in combination with polymer (P) above, and of increasing the reliability of liquid crystal elements. For polyamic acid, polyamic acid ester, and polyimide as polymer (Q), the descriptions other than those for specific diamine (A) and specific diamine (B) in the description of polyamic acid, polyamic acid ester, and polyimide as polymer (P) above apply. For addition polymer as polymer (Q), the descriptions other than those for specific monomer (A) and specific monomer (B) in the description of addition polymer as polymer (P) above apply.

[0101] When a polymer (Q) is included in the liquid crystal alignment agent, the content of polymer (Q) is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of polymer (P) and polymer (Q). Furthermore, the content of polymer (Q) is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on the total amount of polymer (P) and polymer (Q).

[0102] [Radical Generator] The liquid crystal alignment agent of this disclosure may further contain a radical generator. By further incorporating a radical generator into the liquid crystal alignment agent together with the polymer (P) and compound (A), it is possible to further improve the contrast of the liquid crystal element while ensuring good liquid crystal alignment.

[0103] In terms of ease of obtaining the desired effect from the inclusion of a radical generator, ease of adjusting the amount, and simplicity, the molecular weight of the radical generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 500 or less.

[0104] Examples of radical generators include photoradical generators and thermal radical generators. Examples of photoradical generators and thermal radical generators are those given in the description of radical-generating groups above.

[0105] When a radical generator is included in the liquid crystal alignment agent, the amount of radical generator in the liquid crystal alignment agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, relative to the total amount of polymer components. Furthermore, the amount of radical generator is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, relative to the total amount of polymer components.

[0106] In order to ensure good liquid crystal alignment while further improving the contrast of the liquid crystal elements, it is preferable that the liquid crystal alignment agent satisfies at least one of the following conditions (i) and (ii). (i) The liquid crystal alignment agent further contains a radical generating agent (excluding polymer (P)). (ii) The polymer (P) further has a substructure containing a radical generating group. From the viewpoint of improving contrast, it is preferable to satisfy at least (ii).

[0107] [solvent] The liquid crystal alignment agent of this disclosure is preferably prepared as a liquid composition in which a polymer (P) and optionally added components are dispersed or dissolved in a solvent. The solvent is preferably an organic solvent, such as aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc. Specific examples of organic solvents used include, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-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, ethylene glycol-i-propyl ether, and ethylene glycol Examples include chol-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, cyclohexanone, 3-methoxy-1-butanol, and the like.

[0108] Furthermore, the liquid crystal alignment agent may also contain a crosslinking agent different from compound (A) (hereinafter also referred to as "other crosslinking agent"). However, from the viewpoint of minimizing surface irregularities of the liquid crystal alignment film and obtaining a liquid crystal element with excellent contrast, the content of the other crosslinking agent is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, relative to the total amount of compound (A) and the other crosslinking agent.

[0109] The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected considering viscosity, volatility, etc., but is preferably in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, a sufficient film thickness can be ensured for the coating, and a liquid crystal alignment film exhibiting good liquid crystal alignment properties is easily obtained. On the other hand, when the solid content concentration is 10% by mass or less, the coating can be made of an appropriate thickness, a liquid crystal alignment film exhibiting good liquid crystal alignment properties is easily obtained, and the viscosity of the liquid crystal alignment agent tends to be appropriate, resulting in good coatability.

[0110] <Liquid crystal alignment films and liquid crystal elements> The liquid crystal alignment film of this disclosure is formed from a liquid crystal alignment agent prepared as described above. The liquid crystal element of this disclosure comprises a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operating mode of the liquid crystal in the liquid crystal element is not particularly limited and can be applied to various modes such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, OCB (Optically Compensated Bend) type, and PSA (Polymer Sustained Alignment) type. The liquid crystal element can be manufactured by a method including, for example, the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operating mode. Steps 2 and 3 are common to each operating mode.

[0111] <Step 1: Formation of the coating> First, a liquid crystal alignment agent is applied to the substrate, and preferably the applied surface is heated to form a coating on the substrate. For example, transparent substrates made of glass such as float glass or soda glass, or resins such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefin) can be used as the substrate. As the transparent conductive film provided on one surface of the substrate, NESA films (registered trademark of PPG, Inc., USA) made of tin oxide (SnO2), ITO films made of indium oxide-tin oxide (In2O3-SnO2), etc., can be used. When manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS type liquid crystal elements, a substrate with comb-shaped patterned electrodes and a counter substrate without electrodes are used. The liquid crystal alignment agent is applied to the substrate on the electrode formation surface, preferably by offset printing, flexographic printing, spin coating, roll coating, or inkjet printing.

[0112] After applying the liquid crystal alignment agent, preheating (pre-bake) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-bake temperature is preferably 30 to 200°C, and the pre-bake time is preferably 0.25 to 10 minutes. Subsequently, a firing (post-bake) process is performed to further remove the solvent. The firing temperature (post-bake temperature) at this time is preferably 80 to 250°C, more preferably 80 to 200°C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the film formed in this way is preferably 0.001 to 1 μm.

[0113] <Step 2: Orientation Treatment> When manufacturing TN, STN, IPS, or FFS type liquid crystal elements, a process (alignment treatment) is performed to impart liquid crystal alignment ability to the coating film formed in step 1 above. This imparts the liquid crystal molecule alignment ability to the coating film, making it a liquid crystal alignment film. As an alignment treatment, methods such as rubbing, in which the coating film formed on the substrate is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or photo-alignment, in which light is irradiated onto the coating film formed on the substrate to impart liquid crystal alignment ability to the coating film, can be used. On the other hand, when manufacturing vertical alignment (VA) type liquid crystal elements, the coating film formed in step 1 above can be used as is as a liquid crystal alignment film, but an alignment treatment may be applied to the coating film to further enhance its liquid crystal alignment ability. A liquid crystal alignment film suitable for vertical alignment type liquid crystal elements is also suitable for PSA type liquid crystal elements.

[0114] In the photo-alignment process, light irradiation can be performed by methods such as irradiating the coating film after the post-bake process, irradiating the coating film after the pre-bake process but before the post-bake process, or irradiating the coating film while it is being heated in at least one of the pre-bake or post-bake processes. As radiation to irradiate the coating film, for example, ultraviolet light and visible light including light with wavelengths of 150 to 800 nm can be used. Preferably, ultraviolet light including light with wavelengths of 200 to 400 nm is used. If the radiation is polarized, it may be linearly polarized or partially polarized. If the radiation used is linearly polarized or partially polarized, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. In the case of unpolarized radiation, the irradiation direction should be oblique.

[0115] 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 to the substrate surface is preferably 400 to 50,000 J / m². 2 And more preferably 1,000 to 20,000 J / m 2The substrate surface may be washed with, for example, water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.) or a mixture thereof, or the substrate may be heated. As a post-irradiation treatment, it is preferable to heat the substrate to further improve the liquid crystal alignment (heat rearrangement), and the temperature when heating the substrate is preferably 120 to 280°C, and more preferably 150 to 250°C.

[0116] <Step 3: Liquid Crystal Cell Construction> Two substrates with liquid crystal alignment films formed on them as described above are prepared, and a liquid crystal cell is manufactured between the two substrates so that liquid crystal is arranged adjacent to the liquid crystal alignment film. To manufacture the liquid crystal cell, for example, two substrates are placed opposite each other with a gap in between so that the liquid crystal alignment films face each other, the periphery of the two substrates is bonded together with a sealant, and liquid crystal is injected and filled into the cell gap surrounded by the substrate surface and the sealant, sealing the injection hole, or an ODF method can be used. As the sealant, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers can be used. As the liquid crystal, nematic liquid crystal and smectic liquid crystal can be used, and among these, nematic liquid crystal is preferred. In PSA mode, after the construction of the liquid crystal cell, a voltage is applied between the conductive films of the pair of substrates, and the liquid crystal cell is irradiated with light.

[0117] PSA-type liquid crystal elements can be manufactured by a method that includes the following steps. A step of applying the liquid crystal alignment agent of this disclosure onto the conductive film of each of a pair of substrates having a conductive film to form a coating film. A process for constructing a liquid crystal cell by arranging a pair of substrates coated with a liquid crystal alignment agent so that the coating films face each other with a liquid crystal layer in between. • A process of irradiating a liquid crystal cell with light while applying a voltage between conductive films.

[0118] Specifically, a liquid crystal cell is constructed in the same manner as in steps 1 to 3 above, except that a polymerizable monomer is injected or dropped together with the liquid crystal between a pair of substrates having a conductive film. Conventional known compounds can be used as the polymerizable monomer injected or dropped together with the liquid crystal. Preferably, a polyfunctional (meth)acrylic monomer is used.

[0119] In the manufacturing of PSA-type liquid crystal elements, after constructing the liquid crystal cell, a voltage is applied between the conductive films of a pair of substrates, and the liquid crystal cell is irradiated with light. The applied voltage can be, for example, 5 to 50 V DC or AC. As the irradiated light, ultraviolet light and visible light including wavelengths of 150 to 800 nm can be used. Of these, ultraviolet light including wavelengths of 300 to 400 nm is preferred. As the light source for the irradiation light, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, etc. can be used. The amount of light irradiated is preferably 1,000 to 200,000 J / m 2 More preferably, 1,000 to 100,000 J / m 2 That is the case.

[0120] For each mode of liquid crystal cell, a polarizing plate is then attached to the outer surface of the liquid crystal cell as needed to form a liquid crystal element. Examples of polarizing plates include a polarizing plate made by sandwiching a polarizing film called an "H film," which is made by stretching and oriented polyvinyl alcohol while absorbing iodine, between cellulose acetate protective films, or a polarizing plate made of the H film itself.

[0121] The liquid crystal elements of this disclosure can be effectively applied to a variety of uses. Specifically, they can be used, for example, in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, as well as in dimming devices, phase difference films, and the like.

[0122] According to this disclosure, the following means are provided: [Method 1] A liquid crystal alignment agent comprising: a polymer (P) having a substructure (a1) represented by formula (1) above, and at least one substructure (a2) selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having one or two nitrogen atoms, a substructure represented by formula (2) above, and a substructure represented by formula (3) above, either in the same molecule or in different molecules, and having a weight-average molecular weight of 5,000 or more; and a compound (A) having a total of two or more groups selected from the group consisting of a (meth)acryloyl group, a vinylphenyl group, and a maleimide group in one molecule, and having a molecular weight of less than 5,000. [Method 2] The liquid crystal alignment agent according to [Method 1], wherein compound (A) has a total of four or more groups selected from the group consisting of (meth)acryloyl groups, vinylphenyl groups, and maleimide groups in one molecule. [Method 3] The liquid crystal alignment agent of [Method 1] or [Method 2], wherein compound (A) does not have a substructure represented by formula (1). [Method 4] The polymer (P) comprises a structural unit (U1) having the substructure (a1) and a structural unit (U2) having the substructure (a2), wherein the liquid crystal alignment agent is one of [Method 1] to [Method 3]. [Method 5] The polymer (P) is the liquid crystal alignment agent of [Method 4], wherein the polymer (P) contains the structural unit (U1) and the structural unit (U2) within the same molecule. [Method 6] A liquid crystal alignment agent according to any of [Method 1] to [Method 5] that satisfies at least one of (i) and (ii) above. [Method 7] A liquid crystal alignment agent according to any of [Method 1] to [Method 6], further containing a polymer (Q) different from the polymer (P). [Method 8] A liquid crystal alignment film formed using any of the liquid crystal alignment agents from [Method 1] to [Method 7]. [Method 9] A liquid crystal element comprising the liquid crystal alignment film of [Method 8]. [Examples]

[0123] The present invention will be described in more detail below with reference to examples, but the present invention is not to be interpreted as being limited by the following examples. In the following examples, the required amounts of raw material compounds and polymers were obtained by repeating the synthesis on the synthesis scale shown in the synthesis examples below as needed. In the examples and comparative examples, "parts" and "%" are on a mass basis unless otherwise specified.

[0124] In the following example, the imidation rate of polyimide in the polymer solution, the weight-average molecular weight (Mw), the number-average molecular weight (Mn), and the epoxy equivalent of the polymer were measured by the following method. <Imidification rate of polyimides> A polyimide solution was added to pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. Then it was dissolved in deuterated dimethyl sulfoxide, with tetramethylsilane as the reference substance, at room temperature. 1 1H-NMR measurements were performed. 1 The imidization rate [%] was determined from the 1H-NMR spectrum using the following formula (1). Imidization rate [%] = (1 - (A 1 / ( A 2 ×α)))×100 …(1) (In formula (1), A 1 This represents the peak area originating from the proton of the NH group, appearing around a chemical shift of 10 ppm. 2 α represents the peak area derived from other protons. α is the ratio of other protons to one proton in the NH group of the polymer precursor (polyamic acid).

[0125] <Weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers> Mw and Mn were measured by gel permeation chromatography (GPC) under the following conditions. The molecular weight distribution (Mw / Mn) was calculated from the obtained Mw and Mn values. Equipment: Showa Denko Corporation's "GPC-101" GPC columns: Combining "GPC-KF-801", "GPC-KF-802", "GPC-KF-803", and "GPC-KF-804" manufactured by Shimadzu GLC Co., Ltd. Mobile phase: Tetrahydrofuran (for polyorganosiloxanes and addition polymers), or N,N-dimethylformamide solution containing lithium bromide and phosphoric acid (for polyamic acids and polyimides) Column temperature: 40℃ Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0126] <Epoxy equivalent> The epoxy equivalent was measured by the hydrochloride-methyl ethyl ketone method described in JIS C 2105.

[0127] The abbreviations for the compounds are as follows. In the following, the compound represented by formula (X) may simply be referred to as "compound (X)".

[0128] <Tetracarboxylic acid dianhydride> [ka]

[0129] <Diamine> [ka] [ka] [ka]

[0130] <Other monomers> [ka] [ka]

[0131] <Additives> [ka]

[0132] <Synthesis of polymers> 1. Synthesis of polyamic acids [Synthesis Example 1] 70 moles of compound (CA-1) and 30 moles of compound (CA-3) as tetracarboxylic dianhydrides, and 20 moles of compound (DA-1), 30 moles of compound (DB-1), 15 moles of compound (DC-4), and 35 moles of compound (DC-5) as diamines were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 40°C for 24 hours to obtain a solution containing 15% by mass of polyamic acid (referred to as polymer (PAA-1)). The weight-average molecular weight (Mw) of polymer (PAA-1) was 34,000.

[0133] [Synthesis Examples 2-19] The same procedure as in Synthesis Example 1 was followed, except that the types and amounts of tetracarboxylic dianhydride and diamine used were changed as shown in Table 1, to obtain polyamic acids (these were designated as polymers (PAA-2) to (PAA-19)). The weight-average molecular weight (Mw) of each polymer is shown in Table 1.

[0134] 2. Synthesis of polyimides [Synthesis Example 20] A solution containing 15% by mass of polyamic acid was obtained by dissolving 85 mole parts of compound (CA-2) and 15 mole parts of compound (CA-3) as tetracarboxylic dianhydrides, and 30 mole parts of compound (DA-1), 30 mole parts of compound (DB-3), 20 mole parts of compound (DC-1), and 20 mole parts of compound (DC-6) as diamines in NMP and reacting them at 40°C for 24 hours. Next, NMP was added to the obtained polyamic acid solution, and pyridine and acetic anhydride were added in 1.5 molar equivalents relative to the carboxyl groups of the polyamic acid. A dehydration and cyclization reaction was carried out at 60°C for 4 hours. After the dehydration and cyclization reaction, the solvent in the system was replaced with fresh NMP, and the solution was further concentrated to obtain a solution containing 20% ​​by mass of polyimide (referred to as polymer (PI-1)) with an imidization rate of approximately 40%. The weight-average molecular weight (Mw) of polymer (PI-1) was 28,000.

[0135] [Synthesis Examples 21-26] The same procedure as in Synthesis Example 20 was followed, except that the types and amounts of tetracarboxylic dianhydride and diamine used were changed as shown in Table 1, to obtain polyimides (these will be referred to as polymers (PI-2) to (PI-7)). The weight-average molecular weight (Mw) of each polymer is shown in Table 1.

[0136] In Table 1, the values ​​for tetracarboxylic dianhydrides (acid dianhydrides 1 and 2) represent the molar ratio of each compound to 100 moles of the total amount of tetracarboxylic dianhydrides used in the synthesis of each polyamic acid. The values ​​for diamines (diamines 1-4) represent the molar ratio of each compound to 100 moles of the total amount of diamines used in the synthesis of each polyamic acid.

[0137] [Table 1]

[0138] 3. Synthesis of polyorganosiloxanes [Synthesis Example 27] In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (compound (S-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were charged and mixed at room temperature. Next, 100 g of deionized water was added dropwise through the dropping funnel over 30 minutes, and the reaction was carried out at 80°C for 6 hours with stirring under reflux. After the reaction was complete, the organic layer was removed and washed with a 0.2% by mass aqueous solution of ammonium nitrate until the water after washing was neutral. Then, the solvent and water were removed under reduced pressure to obtain a polyorganosiloxane (ESSQ-1) containing epoxy groups as a viscous transparent liquid. Regarding polyorganosiloxane (ESSQ-1), 1 ¹H-NMR analysis revealed a peak based on epoxy groups at a chemical shift (δ) of approximately 3.2 ppm, confirming that no side reactions of epoxy groups occurred during the reaction. The weight-average molecular weight (Mw) of the obtained polyorganosiloxane (ESSQ-1) was 3,500, and the epoxy equivalent was 180 g / mol. Next, 10.0 g of polyorganosiloxane (ESSQ-1), 30.28 g of methyl isobutyl ketone as a solvent, compounds (S-2) and (S-3) as modifying components (carboxylic acids) in amounts corresponding to 20 mol% and 10 mol%, respectively, relative to the total amount of epoxy groups in polyorganosiloxane (ESSQ-1), and 0.10 g of UCAT 18X ​​(trade name, manufactured by Sunapro Co., Ltd.) as a catalyst were charged into a 200 mL three-necked flask, and the reaction was carried out at 100 °C for 48 hours with stirring. After the reaction was complete, ethyl acetate was added to the reaction mixture, and the resulting solution was washed three times with water. The organic layer was dried using magnesium sulfate, and the solvent was removed by distillation to obtain a polyorganosiloxane containing directing groups (referred to as polymer (PSQ-1)). The weight-average molecular weight (Mw) of polymer (PSQ-1) was 8,000.

[0139] 4. Synthesis of oligomeric crosslinking agents [Synthesis Example 28] In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 40.0 g of compound (S-1), 60.0 g of compound (S-4), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were charged and mixed at room temperature. Next, 100 g of deionized water was added dropwise through the dropping funnel over 30 minutes, and the reaction was carried out at 80°C for 6 hours with stirring under reflux. After the reaction was complete, the organic layer was removed and washed with a 0.2% by mass aqueous solution of ammonium nitrate until the water after washing was neutral. Then, the solvent and water were removed under reduced pressure to obtain a polyorganosiloxane containing vinylphenyl groups and epoxy groups (referred to as additive (AD-7)) as a viscous transparent liquid. The weight-average molecular weight (Mw) of additive (AD-7) was 3,000.

[0140] 5. Synthesis of addition polymers [Synthesis Example 29] Under nitrogen, 18.7 mmol of compound (MA-1), 18.7 mmol of compound (MA-2), 10.6 mmol of compound (MA-3), and 5.3 mmol of compound (MA-4) were added to a 100 mL two-necked flask as polymerization monomers, 0.98 g of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator, and 50 ml of NMP as a solvent. Polymerization was carried out at 70°C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and vacuum-dried at room temperature for 8 hours to obtain an addition polymer (referred to as polymer (MI-1)). The weight-average molecular weight (Mw) of polymer (MI-1) was 35,000, and the molecular weight distribution (Mw / Mn) was 2.

[0141] <Preparation of liquid crystal alignment agents, manufacturing and evaluation of liquid crystal display elements> [Example 1: PSA-type liquid crystal display element] 1. Preparation of liquid crystal alignment agent A solution containing 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 was mixed with 3 parts by mass of compound (AD-1), and diluted with NMP and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid content concentration of 3.5% by mass. Liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a pore size filter of 0.2 μm.

[0142] 2. Preparation of liquid crystal composition To 10 g of nematic liquid crystal (Merck, MLC-6608), 5% by mass of a liquid crystalline compound represented by the following formula (L1-1) and 0.3% by mass of a polymerizable monomer represented by the following formula (L2-1) were added and mixed to obtain liquid crystal composition LC1. [ka]

[0143] 3. Manufacturing of PSA-type liquid crystal display elements A liquid crystal alignment agent (AL-1) was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner. After pre-baking on an 80°C hot plate for 1 minute, the solvent was removed by heating in a nitrogen-purged oven at 200°C for 1 hour to form a coating film (liquid crystal alignment film) with a thickness of 0.08 μm. This coating film was then rubbed using a rubbing machine with a roll wrapped in rayon cloth at a roll rotation speed of 400 rpm, a stage movement speed of 3 cm / second, and a pile insertion length of 0.1 mm. Subsequently, ultrasonic cleaning was performed in ultrapure water for 1 minute, and then drying in a 100°C clean oven for 10 minutes to obtain a substrate with a liquid crystal alignment film. This operation was repeated to obtain a pair (2 sheets) of substrates with a liquid crystal alignment film. This rubbing process was a weak rubbing process performed to control the tilting of the liquid crystals and to perform alignment division in a simple manner. An epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was screen printed onto the outer periphery of one of the substrates having a liquid crystal alignment film. Then, the liquid crystal alignment film surfaces of the pair of substrates were placed facing each other, overlapped, and pressed together. The adhesive was then heat-cured at 150°C for 1 hour. Next, the liquid crystal composition LC1 was filled into the gap between the substrates through the liquid crystal injection port, the liquid crystal injection port was sealed with an epoxy adhesive, and then, to remove the flow orientation during liquid crystal injection, it was heated at 150°C for 10 minutes and then slowly cooled to room temperature. Next, a 10V AC current with a frequency of 60Hz is applied between the electrodes of the obtained liquid crystal display element, and while the liquid crystal is in operation, ultraviolet light of 50,000 J / m² is emitted using an ultraviolet irradiation device with a metal halide lamp as the light source. 2 The device was irradiated with the specified dose. This dose was measured using a light meter that measures at a wavelength of 365 nm. A PSA-type liquid crystal display element was manufactured using this method.

[0144] 4. Evaluation of contrast After operating the liquid crystal display element manufactured in step 3 above at an AC voltage of 10V for 30 hours, the minimum relative transmittance (%) expressed by the following formula (1) was measured using an apparatus in which a polarizer and an analyzer were placed between the light source and the light intensity detector. Minimum relative transmittance (%) = (β-B 0 ) / (B 100 -B 0 ) × 100 …(1) (In formula (1), B 0 This is the amount of light transmitted under crossed nicols in a blank. 100 β is the amount of light transmitted under paranicols in a blank field. β is the amount of light transmitted when a liquid crystal display element is placed between the polarizer and analyzer under crossed nicols, minimizing the transmitted light. The black level in a dark state is represented by the minimum relative transmittance of the liquid crystal display element, and the lower the black level in a dark state, the better the contrast. A minimum relative transmittance of less than 0.1% was classified as "Excellent (◎)", 0.1% to less than 0.4% as "Good (○)", and 0.4% or more as "Poor (×)". As a result, this embodiment received a "Good (○)" evaluation.

[0145] 5. Evaluation of liquid crystal alignment (bright spots) The liquid crystal display element manufactured in step 3 above was observed using a polarizing microscope (ECLIPSE E600WPOL, Nikon Corporation) to evaluate the number of bright spots. Specifically, the liquid crystal display element was placed between two polarizing plates arranged so that their polarization axes were orthogonal, and the liquid crystal display element was observed with a polarizing microscope at 5x magnification (observation area: approximately 2,500 μm × 2,500 μm). A smaller number of bright spots indicates better liquid crystal alignment. A number of fewer than 5 bright spots was rated as "Excellent (◎)", a number of 5 or more but less than 20 was rated as "Good (○)", and a number of 20 or more was rated as "Poor (×)". As a result, this embodiment received an evaluation of "Excellent (◎)".

[0146] 6. Insulation Resistance (1) Preparation of insulating film forming composition In a flask equipped with a condenser and a stirrer, 7 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile), 200 parts by mass of propylene glycol monomethyl ether acetate, 15 parts by mass of methacrylic acid, 30 parts by mass of glycidyl methacrylate, 20 parts by mass of styrene, 5 parts by mass of 2-hydroxyethyl acrylate, and 30 parts by mass of isobornyl acrylate were charged. After purging with nitrogen, stirring was started slowly. The reaction solution was raised to 62°C and maintained at this temperature for 5 hours to obtain a polymer solution containing the acrylic copolymer (R-1). The obtained polymer solution was dropped to 900 parts by mass of hexane to precipitate the acrylic copolymer (R-1). The precipitated acrylic copolymer (R-1) was separated, 150 parts by mass of propylene glycol monomethyl ethyl acetate was added, and the mixture was heated to 40°C and distilled under reduced pressure to obtain a polymer solution containing the acrylic copolymer (R-1). The polymer solution containing the obtained acrylic copolymer (R-1) had a solid content concentration of 30% by mass. GPC analysis revealed that the area of ​​unreacted monomers and polymerization initiators was 2.3%, and the weight-average molecular weight (Mw) was 12,800. For every 100 parts by mass (solid content) of acrylic copolymer (R-1), 25 parts by mass of a condensate of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol (1.0 mol) and 1,2-naphthoquinone diazide-5-sulfonic acid chloride (2.0 mol) is added as a photosensitive agent, and a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (manufactured by Nippon Kayaku Co., Ltd., "KAYARAD") is added as a polymerizable compound. 5 parts by mass of DPHA, 10 parts by mass of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Kyowa Nol M, manufactured by Kyowa Hakko Kirin Co., Ltd.) as a film-forming aid, and SH28PA (manufactured by Toray Dow Corning Co., Ltd.) as a leveling agent were mixed and dissolved in diethylene glycol ethyl methyl ether to a solid content concentration of 18% by mass. The mixture was then filtered through a membrane filter with a pore size of 0.2 μm to prepare insulating film-forming composition (RD-1).

[0147] (2) Fabrication of a substrate with an insulating film The insulating film forming composition (RD-1) was applied to a glass substrate using a spin coater, and then pre-baked on a hot plate at 90°C for 2 minutes. Subsequently, exposure was performed using a proximity exposure machine (Canon's "MA-1200" (ghi-line mixed)) at a concentration of 300 mJ / cm². 2 After irradiating the entire substrate with light, it was heated in an oven at 230°C for 30 minutes (post-bake) to cure it, forming an insulating film with a thickness of 3 μm on the glass substrate.

[0148] (3) Manufacturing of liquid crystal cells for insulating film resistance evaluation A liquid crystal alignment agent (AL-1) was applied using a spinner to the electrode formation surface of a substrate equipped with comb-shaped patterned ITO electrodes, and to the insulating film formation surface of a substrate equipped with an insulating film. The substrates were then heated on a hot plate at 80°C for 1 minute (pre-bake). Subsequently, the substrates were heated at 230°C for 1 hour in an oven with nitrogen purging (post-bake) to create a pair (2 substrates) with a liquid crystal alignment film thickness of 0.1 μm. An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was screen-printed onto the outer periphery of the surface of the substrate with the liquid crystal alignment film that had an insulating film. Then, the liquid crystal alignment film surfaces of a pair of substrates were pressed together, and the adhesive was heat-cured at 150°C for 1 hour. Next, the liquid crystal composition LC1 was filled into the gap between the substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with an epoxy adhesive. Furthermore, to eliminate the flow orientation during liquid crystal injection, the mixture was heated at 130°C and then slowly cooled to room temperature to manufacture a liquid crystal cell. For the liquid crystal cell used for insulating film resistance evaluation, an electrode substrate for IPS type liquid crystal cells was used due to the simplicity of substrate fabrication.

[0149] (4) Evaluation of insulating film resistance After the liquid crystal cells for insulating film resistance evaluation manufactured in 6.(3) above were placed in a 60°C oven, the voltage retention rate (VHR) was measured using the VHR-1 VHR measuring device manufactured by Toyo Technica Co., Ltd. under the conditions of 1V and 1670 milliseconds. A VHR higher than 60% was rated as "Excellent (◎)", a VHR between 60% and 45% was rated as "Good (○)", and a VHR lower than 45% was rated as "Poor (×)". As a result, this example received an evaluation of "Excellent (◎)".

[0150] [Examples 2-24 and Comparative Examples 1-10] Liquid crystal alignment agents (designated as (AL-2) to (AL-34)) were 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 2. Liquid crystal display elements were then manufactured using each liquid crystal alignment agent in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2. In Table 2, the values ​​in the columns for polymer components (polymers 1 and 2) and additives represent the solid content ratio (parts by mass) of each compound relative to 100 parts by mass of the total amount of polymer components used in the preparation of the liquid crystal alignment agent.

[0151] [Table 2]

[0152] As shown in Table 2, Examples 1 to 24, which used a liquid crystal alignment agent containing polymer (P) and compound (A), showed excellent (◎) or good (○) results in evaluation of contrast, liquid crystal alignment, and insulating film resistance, indicating a well-balanced improvement in various properties.

[0153] The mechanism by which the liquid crystal alignment agent containing polymer (P) and compound (A) improved contrast, liquid crystal alignment, and insulating film resistance in a well-balanced manner is not clear, but it is speculated to be as follows.

[0154] The liquid crystal alignment agents of Examples 1 to 24 contain a polymer (P) having substructures (a1) and (a2) in the same molecule or in different molecules, with a weight-average molecular weight of 5,000 or more, and a compound (A) having a total of two or more specific groups F in the molecule, with a molecular weight of less than 5,000. Substructure (a1) of polymer (P) is a structure having multiple ring structures, and is a structure that readily acts on the mesogens of liquid crystal molecules. Therefore, it is thought that the presence of substructure (a1) on the surface of the liquid crystal alignment film resulted in good alignment of the liquid crystal. It is then presumed that the good liquid crystal alignment of the liquid crystal alignment film suppressed the generation of bright spots. Furthermore, it is thought that the basic substructure (a2) acted as an adsorption site for impurities in the liquid crystal alignment film. As a result, it is presumed that impurities generated from the insulating film were captured, and their elution into the liquid crystal was suppressed. Furthermore, it is thought that compound (A) is unevenly distributed at the interface between the liquid crystal and the liquid crystal alignment film, and that the specific group F of compound (A) reacts uniformly with the low molecular weight components in the liquid crystal and on the surface of the liquid crystal alignment film, thereby suppressing the formation of coarse particles on the surface of the alignment film. As a result, surface irregularities are suppressed, and the reduction in contrast is thought to be inhibited.

[0155] In contrast, Comparative Examples 1, 2, and 7, which used a polymer without substructure (a2) instead of polymer (P), Comparative Examples 8 and 9, which used a polymer without substructure (a1) instead of polymer (P), and Comparative Examples 3 to 6 and 10, which used a liquid crystal alignment agent without compound (A), all showed a poor (×) result in one or more of the evaluation results for contrast, liquid crystal alignment, and insulating film resistance.

[0156] From these results, it became clear that a liquid crystal alignment agent containing polymer (P) and compound (A) can be used to obtain a liquid crystal alignment film that exhibits good liquid crystal alignment properties while also possessing insulating film resistance, and furthermore, a liquid crystal element with excellent contrast can be obtained.

Claims

1. A polymer (P) having a substructure (a1) represented by the following formula (1), and at least one substructure (a2) selected from the group consisting of a nitrogen-containing aromatic heterocyclic structure having one or two nitrogen atoms, a substructure represented by the following formula (2), and a substructure represented by the following formula (3), either within the same molecule or in different molecules, and having a weight-average molecular weight of 5,000 or more, Compound (A) having a total of two or more groups selected from the group consisting of (meth)acryloyl groups, vinylphenyl groups, and maleimide groups in one molecule, and having a molecular weight of less than 5,000, A liquid crystal alignment agent containing the following: 【Chemistry 1】 (In Formula (1), R １ is a hydrogen atom, a substituted or unsubstituted monovalent chain hydrocarbon group, or a monovalent group obtained by substituting any methylene group in said chain hydrocarbon group with -O-. A １ , A ２ and A ３ are each independently a substituted or unsubstituted divalent hydrocarbon cyclic group. X １ and X ２ are each independently a single bond, an alkanediyl group having 1 to 3 carbon atoms, -CO-O-, -CO-NR ２ -, or a divalent group obtained by substituting any methylene group in an alkanediyl group having 2 or 3 carbon atoms with -O- or -NR ２ -. R ２ is a hydrogen atom or a monovalent organic group. n is an integer from 0 to 2. When n is 2, two A ２ are the same or different, and two X ２ are the same or different. "*" represents a bonding site.) 【Chemistry 2】 (In equations (2) and (3), Y １ This is a hydrogen atom or a monovalent thermally leaving group. ２ R is a monovalent thermally leaving group. ３ R is a substituted or unsubstituted divalent hydrocarbon group, or a substituted or unsubstituted divalent heterocyclic group. ４ This is a substituted or unsubstituted divalent chain hydrocarbon group. １ , ">C(R ６ ) - is a group represented by " or a substituted or unsubstituted trivalent aromatic ring group. ６ X is a hydrogen atom or a monovalent organic group. ３ is a single bond or a divalent organic group. However, B １ If is a substituted or unsubstituted trivalent aromatic ring group, X ３ R is a divalent organic group. ５ (This is a hydrogen atom or a monovalent hydrocarbon group. "*" represents a bonding bond.)

2. The liquid crystal alignment agent according to claim 1, wherein compound (A) has a total of four or more groups selected from the group consisting of (meth)acryloyl groups, vinylphenyl groups, and maleimide groups in one molecule.

3. The liquid crystal alignment agent according to claim 1, wherein the compound (A) does not have a substructure represented by formula (1).

4. The liquid crystal alignment agent according to claim 1, wherein the polymer (P) comprises a structural unit (U1) having the substructure (a1) and a structural unit (U2) having the substructure (a2).

5. The liquid crystal alignment agent according to claim 4, wherein the polymer (P) contains the structural unit (U1) and the structural unit (U2) within the same molecule.

6. A liquid crystal alignment agent according to claim 1, satisfying at least one of the following (i) and (ii). (i) The liquid crystal alignment agent further contains a radical generating agent (excluding the polymer (P)). (ii) The polymer (P) further has a substructure (a3) ​​that includes a radical generating group.

7. Furthermore, the liquid crystal alignment agent according to claim 1, further comprising a polymer (Q) different from the polymer (P).

8. A liquid crystal alignment film formed using the liquid crystal alignment agent described in any one of claims 1 to 7.

9. A liquid crystal element comprising the liquid crystal alignment film described in claim 8.

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