Liquid crystal alignment agent for weak anchoring film, method for manufacturing liquid crystal alignment film, and method for manufacturing liquid crystal element

Abstract

To provide a liquid crystal alignment agent which can provide a liquid crystal element with a liquid crystal alignment property, can reduce the voltage which drives a liquid crystal element, and also has an excellent adhesion.SOLUTION: The liquid crystal aligning agent for forming a weak anchoring film relates to a liquid crystal alignment agent for forming a weak anchoring film used to form a weak anchoring liquid crystal alignment film. The liquid crystal aligning agent for forming a weak anchoring film includes a polymer having an aliphatic ring with 7 or more ring members in a side chain and a crosslinking agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a weak anchoring liquid crystal aligning agent, a method for manufacturing a liquid crystal alignment film, and a method for manufacturing a liquid crystal element.

Background Art

[0002] In a liquid crystal element, the initial alignment of liquid crystal molecules is generally defined by the anchoring of liquid crystal molecules by a liquid crystal alignment film. In recent years, in a liquid crystal element having a horizontal alignment mode such as an IPS type or an FFS type, a liquid crystal alignment film having strong anchoring energy (hereinafter, also referred to as a "strong anchoring liquid crystal alignment film") is formed on one of a pair of substrates, and a liquid crystal alignment film having no anchoring energy or very small anchoring energy (hereinafter, also referred to as a "weak anchoring liquid crystal alignment film") is formed on the other substrate. Various liquid crystal elements have been proposed. In a liquid crystal element using a weak anchoring state, it is possible to improve the luminance and contrast ratio, achieve low voltage driving, and high speed response (high speed rise) compared to a normal liquid crystal element in which strong anchoring liquid crystal alignment films are formed on both substrates. Note that "weak anchoring" is also referred to as "zero surface anchoring".

[0003] For example, Patent Document 1 discloses a method for forming a zero surface anchoring film on a first substrate by a method including a step of applying energy sufficient for a polymerization reaction of a radical polymerizable compound to a liquid crystal composition containing a liquid crystal and a radical polymerizable compound in a state of contacting a radical generating film, and forming a liquid crystal alignment film on a second substrate with a known liquid crystal aligning agent to manufacture a liquid crystal cell.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique described in Patent Document 1, when producing a weakly anchoring liquid crystal alignment film, a liquid crystal composition containing a liquid crystal and a radically polymerizable compound is brought into contact with a radical generating film formed on a first substrate, and in that state, a step of applying energy sufficient to polymerize the radically polymerizable compound is required. From the viewpoint of productivity, it is desired to obtain a liquid crystal element that can produce a weakly anchoring liquid crystal alignment film by a simple operation, can achieve low voltage driving derived from the weakly anchoring state, and exhibits good liquid crystal alignment.

[0006] For example, in addition to mobile applications typified by smartphones and tablet PCs, in large TVs and PC monitors, edge narrowing is being carried out from the viewpoints of design and miniaturization of display devices. As one method of edge narrowing, a method is known in which a liquid crystal alignment film is formed over the entire surface of a substrate, and then a sealing agent is applied onto the liquid crystal alignment film to bond the substrates together. On the other hand, when a sealing agent is disposed on the liquid crystal alignment film, there is a concern that the adhesion between the substrates is likely to decrease, and the substrates are likely to peel off due to the action of an external force or the like.

[0007] The present invention has been made in view of the above problems, and a main object thereof is to provide a liquid crystal aligning agent that can obtain a liquid crystal element having excellent liquid crystal alignment, can achieve low voltage driving of the liquid crystal element, and can form a liquid crystal alignment film having excellent adhesion.

Means for Solving the Problems

[0008] According to the present invention, the following means are provided.

[0009] 〔1〕A liquid crystal aligning agent for forming a weakly anchoring liquid crystal alignment film, which contains a polymer (P) having an aliphatic ring with 7 or more ring members in a side chain and a crosslinking agent. 〔2〕A method for manufacturing a liquid crystal alignment film, in which a weakly anchoring liquid crystal alignment film is formed using the liquid crystal aligning agent of the above 〔1〕. 〔3〕 A method for manufacturing a liquid crystal element including a pair of substrates composed of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising: applying a liquid crystal aligning agent for forming a weak anchoring film of the above-mentioned [1] on at least one surface of the first substrate and the second substrate to form a weak anchoring liquid crystal alignment film.

Effects of the Invention

[0010] According to the liquid crystal aligning agent of the present invention, while obtaining a liquid crystal element with excellent liquid crystal alignment properties, it is possible to achieve low voltage driving of the liquid crystal element. Further, according to the liquid crystal aligning agent of the present invention, it is possible to form a liquid crystal alignment film with excellent adhesion.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0012] Hereinafter, matters related to the embodiments will be described in detail. In this specification, a numerical range described using "~" means that the numerical values described before and after "~" are included as the lower limit value and the upper limit value. A "structural unit" is a unit mainly constituting the main chain structure, and means a unit contained in at least two in the main chain structure. A structural unit is typically a repeating unit constituted based on one monomer.

[0013] In this specification, the "hydrocarbon group" means a group including a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The "chain hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not contain a cyclic structure in the main chain and are composed only of a chain structure. However, the chain hydrocarbon group may be saturated or unsaturated. The "alicyclic hydrocarbon group" means a hydrocarbon group that includes only the structure of an alicyclic hydrocarbon as the ring structure and does not include an aromatic ring structure. However, the alicyclic hydrocarbon group does not necessarily have to be composed only of the structure of an alicyclic hydrocarbon and also includes those having a chain structure in a part thereof. The "aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as the ring structure. However, the aromatic hydrocarbon group does not necessarily have to be composed only of the aromatic ring structure and may include a chain structure or the structure of an alicyclic hydrocarbon in a part thereof. The "organic group" means an atomic group formed by removing an arbitrary hydrogen atom from a compound containing carbon (i.e., an organic compound).

[0014] The "main chain" of a polymer means the "trunk" part composed of the longest chain of atoms in the polymer. It is allowed for this "trunk" part to include a cyclic structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. The "side chain" means a part branched from the "trunk" part of the polymer. "(Meth)acryl" is a term encompassing acrylic and methacrylic, and "(meth)acrylo" is a term encompassing acrylo and methacrylo. "(Meth)acrylate" is a term encompassing acrylate and methacrylate.

[0015] 《Liquid Crystal Alignment Agent》 The liquid crystal alignment agent of the present disclosure is a liquid crystal alignment agent for forming a weakly anchoring liquid crystal alignment film used for forming a weakly anchoring liquid crystal alignment film. The liquid crystal alignment agent of the present disclosure contains a polymer (P) having an aliphatic ring with 7 or more ring members in the side chain and a crosslinking agent. Each component will be described in detail below. Unless otherwise specified for each component, one kind may be used alone or two or more kinds may be used in combination.

[0016] <Polymer (P)> Examples of the aliphatic ring having 7 or more ring members in the polymer (P) include aliphatic hydrocarbon rings having 7 to 30 carbon atoms and aliphatic heterocyclic rings having 6 to 30 carbon atoms. These aliphatic rings may be saturated or unsaturated. Further, the aliphatic ring having 7 or more ring members in the polymer (P) may be either a bridged type or a condensed ring type, or a combination of a bridged type and a condensed ring type. The aliphatic ring having 7 or more ring members in the polymer (P) may have a substituent.

[0017] Examples of the aliphatic hydrocarbon ring having 7 to 30 carbon atoms include monocyclic aliphatic hydrocarbon rings having 7 to 30 carbon atoms and polycyclic aliphatic hydrocarbon rings having 7 to 30 carbon atoms. Specific examples of the monocyclic aliphatic hydrocarbon ring include saturated hydrocarbon rings such as cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, cyclotridecane, cyclotetradecane, cyclopentadecane, cyclohexadecane, cycloheptadecane, cyclooctadecane, cyclononadecane, cycloeicosane, cyclodocosane; and unsaturated hydrocarbon rings such as cycloheptene, cyclooctene, cyclodecene, cyclododecene, cyclotridecene, cyclopentadecene, cyclohexadecene, cycloheptadecene, cyclooctadecene. The polycyclic aliphatic hydrocarbon ring is preferably a bridged saturated aliphatic hydrocarbon ring or a condensed aliphatic saturated hydrocarbon ring. For example, bicyclo[3.2.1]octane, tricyclo[3.2.1.0 2,7 octane and the like can be mentioned.

[0018] When the aliphatic ring is polycyclic, the "aliphatic ring having 7 or more ring members" has one or more aliphatic rings having 7 or more ring members in the structure. That is, in the case of a condensed ring type aliphatic ring, at least one of the two or more rings constituting the condensed ring has 7 or more ring members. In the case of a bridged type aliphatic ring, it means one containing a ring having 7 or more ring members in the bridged alicyclic skeleton. Therefore, for example, condensed rings composed only of aliphatic rings having 6 or less ring members such as decahydronaphthalene and bicyclo[4.3.0]nonane, and bridged rings not containing an aliphatic ring having 7 or more ring members in the alicyclic skeleton such as norbornane and bicyclo[2.2.2]octane do not fall under the "aliphatic ring having 7 or more ring members".

[0019] Examples of the aliphatic heterocyclic ring having 7 to 30 carbon atoms include rings in which any methylene group of the rings exemplified as the aliphatic hydrocarbon ring having 7 to 30 carbon atoms is replaced by -O-, -S-, -CO-, -NR- (wherein R is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms), etc. The aliphatic heterocyclic ring may be either monocyclic or polycyclic. Specific examples of the aliphatic heterocyclic ring having 7 to 30 carbon atoms include nitrogen-containing monocyclic saturated aliphatic heterocyclic rings such as azocane and azonane; nitrogen-containing monocyclic unsaturated aliphatic rings such as 2,3-dihydroazepine, 2,5-dihydroazepine, and 4,5-dihydroazepine; nitrogen-containing polycyclic aliphatic rings such as tropane and nortropane; oxygen-containing monocyclic saturated aliphatic heterocyclic rings such as oxepane; sulfur-containing monocyclic saturated aliphatic heterocyclic rings such as thiocane; cyclic lactones such as ε-caprolactone; cyclic lactams such as ε-caprolactam; crown ethers such as 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, 1-aza-18-crown-6-ether, and 4,13-diaza-18-crown-6-ether; etc.

[0020] When the aliphatic ring having 7 or more ring members in the polymer (P) has a substituent, examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), a hydroxyl group, a cyano group, a nitro group, an acyl group, etc.

[0021] From the viewpoint of obtaining a liquid crystal alignment film exhibiting good weak anchoring properties, the polymer (P) preferably has a group obtained by removing one hydrogen atom from an aliphatic ring having 7 or more ring members. Specifically, the polymer (P) preferably has a partial structure represented by the following formula (1). *-L 1 -A 1 …(1) (In formula (1), L 1 is a single bond or a divalent linking group. A 1 is a group obtained by removing one hydrogen atom from an aliphatic ring having 7 or more ring members. “*” represents a bond to the main chain.)

[0022] In the above formula (1), L 1 Examples of the divalent linking group represented by -O-, -CO-, -COO-, -CONR 1 -(provided that R 1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent thermally dissociable group), a divalent hydrocarbon group having 1 to 20 carbon atoms, and any methylene group of the hydrocarbon group is -O-, -CO-, -COO- or -CONR 1 - and the like. The divalent linking group represented by L 1 The hydrogen atom bonded to the carbon atom of the group exemplified above may be substituted. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), a hydroxyl group, and the like.

[0023] R 1 Examples of the monovalent thermally dissociable group represented by -tert-butoxycarbonyl group (Boc group), benzyloxycarbonyl group, 1,1-dimethyl-2-haloethyloxycarbonyl group, allyloxycarbonyl group, 2-(trimethylsilyl)ethyloxycarbonyl group, 9-fluorenylmethyloxycarbonyl group and the like. Among these, the Boc group is particularly preferred in terms of excellent thermal dissociability and the ability to reduce the residual amount in the film of the dissociated structure.

[0024] The bond represented by "*" in the above formula (1) is preferably bonded to a carbon atom or a nitrogen atom constituting the main chain. The bond may be bonded to a chain structure or a ring structure (for example, a benzene ring, a maleimide ring, a succinimide ring, etc.).

[0025] In terms of further improving the effect of improving the low-voltage drivability of the liquid crystal element, the number of ring members of the aliphatic ring contained in the polymer (P) is preferably 7 to 18, more preferably 7 to 15, still more preferably 8 to 15, and even more preferably 8 to 12. For the same reason, the aliphatic ring having 7 or more ring members contained in the polymer (P) is preferably an aliphatic hydrocarbon ring or a nitrogen-containing aliphatic heterocyclic ring, and more preferably an aliphatic hydrocarbon ring.

[0026] From the viewpoint of obtaining a liquid crystal alignment film having good weak anchoring properties, the polymer (P) preferably contains a structural unit having an aliphatic ring with 7 or more ring members. In the polymer (P), the proportion of the structural unit having an aliphatic ring with 7 or more ring members is preferably 15 mol% or more, more preferably 30 mol% or more, and still more preferably 50 mol% or more based on the total amount of the structural units constituting the polymer (P).

[0027] The main chain of the polymer (P) is not particularly limited. Examples of the main chain of the polymer (P) include addition polymers, polyamic acids, polyamic acid esters, polyimides, polyamides, polyamideimides, polyorganosiloxanes, polyesters, polyenamines, polyureas, polybenzoxazoles, and the like. From the viewpoints of making the voltage holding characteristics and liquid crystal alignment properties of the obtained liquid crystal element excellent and the ease of introducing an aliphatic ring with 7 or more ring members into the side chain, the polymer (P) is preferably at least one selected from the group consisting of addition polymers, polyamic acids, polyamic acid esters, polyimides, and polyorganosiloxanes. Hereinafter, each polymer will be described in detail.

[0028] (Addition polymer) Examples of the addition polymer as the polymer (P) (hereinafter, also referred to as "addition polymer (P)") include (meth)acrylic polymers, styrene polymers, maleimide polymers, (meth)acrylic-styrene copolymers, (meth)acrylic-maleimide copolymers, (meth)acrylic-styrene-maleimide copolymers, and styrene-maleimide copolymers. From the viewpoint of obtaining a liquid crystal alignment film having good weak anchoring properties, the addition polymer (P) preferably contains a structural unit having an aliphatic ring with 7 or more ring members, and specifically, preferably has at least one selected from the group consisting of the structural unit represented by the following formula (2-1) and the structural unit represented by the following formula (2-2). [Chemical formula] (In formula (2-1), R 11 is a hydrogen atom or a methyl group. X 1is -CO-, -COO-, -CONH- or a divalent aromatic ring group. X 2 is a single bond or a divalent linking group. A 1 is a group obtained by removing one hydrogen atom from an aliphatic ring having 7 or more ring members. In formula (2-2), R 12 and R 13 are each independently a hydrogen atom or a methyl group. X 3 is a divalent linking group. A 1 is a group obtained by removing one hydrogen atom from an aliphatic ring having 7 or more ring members.)

[0029] In the above formulas (2-1) and (2-2), when the group represented by X 1 is a divalent aromatic ring group, the divalent aromatic ring group is preferably a group obtained by removing two hydrogen atoms from a benzene ring or a naphthalene ring. The aromatic ring group may have a substituent on the ring portion. Examples of the substituent include the same groups as those exemplified as the substituents that an aliphatic ring having 7 or more ring members may have.

[0030] X 2 or X 3 Examples of the divalent linking group represented by include a divalent hydrocarbon group having 1 to 20 carbon atoms, and a divalent group in which any methylene group of the hydrocarbon group is replaced by -O-, -CO-, -COO- or -CONR 1 -. These divalent linking groups may have a hydrogen atom bonded to a carbon atom replaced. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), a hydroxyl group, and the like.

[0031] In terms of facilitating the introduction of an aliphatic ring having 7 or more ring members into the side chain, the addition polymer (P) preferably contains a structural unit derived from a monomer having an aliphatic ring having 7 or more ring members. Specific examples of the monomer that gives a structural unit having an aliphatic hydrocarbon ring having 7 or more ring members include compounds represented by the following formulas (2-1-1) to (2-1-9). Specific examples of the monomer that gives a structural unit having an aliphatic heterocyclic ring having 7 or more ring members include compounds represented by the following formulas (2-2-1) to (2-2-6). [Chemical formula] (In the formula, R a is a hydrogen atom or a methyl group.)

[0032] Monomers having an aliphatic ring with 7 or more ring members show excellent liquid crystal alignment properties (especially AC residual image properties), and in terms of being able to further enhance the effect of improving the low voltage driving of liquid crystal elements, compounds having none of an amide group, a hydroxy group, an amino group, and a protected amino group are preferred. Specifically, among the compounds represented by the above formulas (2-1-1) to (2-1-9) and formulas (2-2-1) to (2-2-6), the compounds represented by the above formulas (2-1-2) to (2-1-5), formulas (2-1-7) to (2-1-9), and formula (2-2-3) are preferred.

[0033] In the synthesis of the addition polymer (P), a monomer having no aliphatic ring with 7 or more ring members (hereinafter also referred to as "other monomer") may be used together with the monomer having an aliphatic ring with 7 or more ring members. Examples of the other monomer include (meth)acrylic compounds, styrene compounds, conjugated diene compounds, maleimide compounds, and the like.

[0034] Specific examples of other monomers include, as (meth)acrylic compounds, unsaturated carboxylic acids such as (meth)acrylic acid; alkyl (meth)acrylates (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), cycloalkyl (meth)acrylates, benzyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 4-hydroxybutyl glycidyl ether (meth)acrylate, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane, etc. unsaturated carboxylic acid esters.

[0035] Examples of aromatic vinyl compounds include styrene, methylstyrene, divinylbenzene, 4-hydroxymethylstyrene, p-styryltrimethoxysilane, 4-(glycidyloxymethyl)styrene, and vinylbenzoic acid, etc. Examples of conjugated diene compounds include 1,3-butadiene and 2-methyl-1,3-butadiene, etc. Examples of maleimide compounds include N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(4-glycidyloxyphenyl)maleimide, N-(4-glycidyloxymethylphenyl)maleimide, N-glycidylmaleimide, N-(4-carboxyphenyl)maleimide, N-(4-tert-butoxycarbonylphenyl)maleimide, etc.

[0036] As other monomers, unsaturated monomers having a photo-orienting group (e.g., cinnamate structure, coumarin structure, azobenzene structure), an alkyl group having 4 to 30 carbon atoms, a halogenated alkyl group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, a halogenated alkoxy group having 4 to 30 carbon atoms, a structure in which one or more rings of a benzene ring and a cyclohexane ring are linked by two or more single bonds or linking groups, or a group having a steroid skeleton may be used as compounds other than those described above.

[0037] In the addition polymer (P), the proportion of the structural unit having an aliphatic ring with 7 or more ring members is preferably 20 mol% or more, more preferably 30 mol% or more, and still more preferably 50 mol% or more with respect to the total amount of the structural units constituting the addition polymer (P) in terms of being able to obtain a liquid crystal element exhibiting excellent liquid crystal alignment while sufficiently achieving low voltage driving.

[0038] The addition polymer (P) preferably contains a structural unit derived from a (meth)acrylic compound in terms of being able to enhance the improvement effect of low voltage driving of the liquid crystal element. In the addition polymer (P), the proportion of the structural unit derived from the (meth)acrylic compound is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol% or more with respect to the total amount of the structural units constituting the addition polymer (P).

[0039] The addition polymer (P) can be obtained, for example, by polymerizing monomers in the presence of a polymerization initiator. As the polymerization initiator to be used, azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) are preferable. The use ratio of the polymerization initiator is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of all the monomers used in the reaction.

[0040] The polymerization reaction is preferably carried out in an organic solvent. Examples of the organic solvent used in the reaction include alcohols, ethers, ketones, amides, esters, hydrocarbon compounds, etc., and diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether acetate, etc. are preferred. The reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of the organic solvent used is preferably such that the total amount of the monomers used in the reaction is 0.1 to 60% by mass based on the total amount of the reaction solution. Incidentally, the addition polymer (P) can also be obtained by a method of synthesizing an addition polymer having an epoxy group in the side chain and then reacting the obtained epoxy group-containing addition polymer with a carboxylic acid having an aliphatic ring having 7 or more ring members (hereinafter also referred to as "specific carboxylic acid").

[0041] Regarding the addition polymer (P), the weight average molecular weight (Mw) in terms of polystyrene measured by GPC is preferably 250 to 500,000, and more preferably 500 to 100,000. Also, the molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 8 or less, and more preferably 6 or less.

[0042] (Polyamic acid) The polyamic acid as the polymer (P) (hereinafter also referred to as "polyamic acid (P)") can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound.

[0043] ·Tetracarboxylic dianhydride Examples of the tetracarboxylic dianhydride used for the synthesis of the polyamic acid (P) include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. The aliphatic tetracarboxylic dianhydrides include chain tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0044] Specific examples of the chain-like tetracarboxylic dianhydride include, for example, butanetetracarboxylic dianhydride and the like. Specific examples of the alicyclic tetracarboxylic dianhydride include, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 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 anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0 2,6 undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, ethylenediaminetetraacetic dianhydride, cyclopentanetetracarboxylic dianhydride and the like.

[0045] Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylenebis(trimellitic monoester anhydride), ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-biphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, and the like. In addition to the above, as the tetracarboxylic dianhydride used for the synthesis of the polyamic acid (P), the tetracarboxylic dianhydride described in JP-A-2010-97188 can also be used.

[0046] ·Diamine compound In the synthesis of the polyamic acid (P), a diamine having an aliphatic ring with 7 or more ring members (hereinafter also referred to as "specific diamine") can be preferably used because of the high degree of freedom in monomer selection. Preferred specific examples of the specific diamine include the compound represented by the following formula (3).

Chemical formula

[0047] In the above formula (3), Ar 1 The aromatic ring group represented by is a group obtained by removing (2 + r) hydrogen atoms from the aromatic ring. The aromatic ring is preferably an aromatic hydrocarbon ring or a nitrogen-containing heterocyclic ring, more preferably a benzene ring, a naphthalene ring or a pyridine ring, and still more preferably a benzene ring. Ar 1 The aromatic ring group represented by may have a substituent on the ring portion. Specific examples of the substituent include the same groups as those exemplified as the substituent that an aliphatic ring having 7 or more ring members may have. X 5 As the divalent linking group represented by, X in the above formula (2-1) 2 and X in the above formula (2-2) 3 include the same groups as those exemplified as specific examples thereof.

[0048] Specific examples of the specific diamine include compounds represented by the following formulas (3-1) to (3-10). In the structural formula, "Boc" represents a tert-butoxycarbonyl group (the same applies hereinafter).

Chemical formula

[0049] The diamine compound used for the synthesis of the polyamic acid (P) may be only the specific diamine. Further, as the diamine compound used for the synthesis of the polyamic acid (P), the specific diamine and a diamine having no aliphatic ring having 7 or more ring members (hereinafter also referred to as "other diamine") may be used in combination. Examples of the other diamine include aliphatic diamines, aromatic diamines, diaminoorganosiloxanes and the like. The aliphatic diamine includes a chain diamine and an alicyclic diamine.

[0050] Specific examples of other diamines include, as chain diamines, for example, m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, etc.; as alicyclic diamines, for example, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), etc.; as aromatic diamines, for example, dodecanoxydiaminobenzene, tetradecanoxydiaminobenzene, pentadecanoxydiaminobenzene, hexadecanoxydiaminobenzene, octadecanoxydiaminobenzene, cholestanyloxydiaminobenzene, cholesteryloxydiaminobenzene, cholestanyl diaminobenzoate, cholesteryl diaminobenzoate, lanostanyl diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenoxy)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, N-(2,4-diaminophenyl)-4-(4-heptylcyclohexyl)benzamide, the following formula (E-1) [Chemical formula] (In formula (E-1), X I and X II are each independently a single bond, -O-, *-COO- or *-OCO- (wherein, "*" represents a bond to the diamino phenyl group side). R I is an alkanediyl group having 1 to 3 carbon atoms. R II is a single bond or an alkanediyl group having 1 to 3 carbon atoms. R IIIis an alkyl group, an alkoxy group, a fluoroalkyl group or a fluoroalkoxy group having 1 to 20 carbon atoms. a is 0 or 1. b is an integer of 0 to 3. c is an integer of 0 to 2. d is 0 or 1. However, 1 ≦ a + b + c ≦ 3.) an orientation group-containing diamine such as a compound represented by: Para-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl-4'-aminobenzoate, 4,4'-diaminoazobenzene, 1,2-bis(4-aminophenoxy)ethane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,5-bis(4-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 1,7-bis(4-aminophenoxy)heptane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, N,N-bis(4-aminophenyl)methylamine, N,N'-di(5-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, 4,4'-(2,2'-oxybis(ethane-2,1-diyl)bis(oxy))dianiline, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,6-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 1,4-bis-(4-aminophenyl)-piperazine, 3,5-diaminobenzoic acid, methyl 3,5-diaminobenzoate, ethyl 3,5-diaminobenzoate, 1-(4-aminophenoxy)-2-(4-(4'-aminophenyl)phenoxy)ethane, 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzamide, the following formulas (f-1) to (f-34) [Chemical formula] [Chemical formula] diamines represented by each of the following, etc.; As the diaminoorganosiloxane, for example, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane and the like can be mentioned respectively. In addition, the diamines described in JP-A-2010-97188 can be used.

[0051] In the above formula (E-1), "-X I -(R I -X II ) d -", the divalent group represented is preferably an alkanediyl group having 1 to 3 carbon atoms, *-O-, *-COO- or *-O-C 2 H 4 -O- (however, the bond marked with "*" is bonded to the diaminophenyl group). The group represented by R III is preferably linear. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position relative to the other groups.

[0052] Specific examples of the compound represented by the above formula (E-1) include, for example, compounds represented by each of the following formulas (E-1-1) to (E-1-4). [Chemical formula]

[0053] In the synthesis of the polyamic acid (P), the use ratio of the specific diamine is preferably 30 mol% or more, more preferably 40 mol% or more, and still more preferably 50 mol% or more based on the total amount of the diamine compounds used in the synthesis of the polyamic acid (P). When the use ratio of the specific diamine is within the above range, it is suitable in that a liquid crystal element excellent in liquid crystal alignment can be obtained while realizing low voltage driving of the liquid crystal element.

[0054] ·Synthesis of Polyamic Acid Polyamic acid (P) can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound as described above, optionally together with a molecular weight regulator. The usage ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of polyamic acid (P) is preferably such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents, more preferably 0.3 to 1.2 equivalents, per equivalent of the amino group of the diamine compound.

[0055] Examples of the molecular weight regulator include acid monohydrides 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 usage ratio of the molecular weight regulator is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass in total of the tetracarboxylic dianhydride and the diamine compound used.

[0056] The synthesis reaction of polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature at this time is preferably -20°C to 150°C, more preferably 0 to 100°C. Also, the reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0057] Examples of the organic solvent used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like. Among these organic solvents, one or more selected from the group consisting of aprotic polar solvents and phenolic solvents (the first group of organic solvents), or a mixture of one or more selected from the first group of organic solvents and one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (the second group of organic solvents) are preferably used. In the latter case, the usage ratio of the second group of organic solvents is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less based on the total amount of the first group of organic solvents and the second group of organic solvents.

[0058] 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, hexamethylphosphoric triamide, m-cresol, xylenol, and halogenated phenol used as a solvent, or a mixture of one or more of these and other organic solvents is preferably used within the above ratio range. The amount (x) of the organic solvent used is preferably such that the total amount (y) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass based on the total amount (x + y) of the reaction solution.

[0059] As described above, a reaction solution obtained by dissolving polyamic acid (P) is obtained. This reaction solution may be directly used for the preparation of a liquid crystal aligning agent, or the polyamic acid (P) contained in the reaction solution may be isolated and then used for the preparation of a liquid crystal aligning agent, or the isolated polyamic acid (P) may be purified and then used for the preparation of a liquid crystal aligning agent. When the polyamic acid (P) is dehydrated and cyclized to form a polyimide, the above reaction solution may be directly subjected to a dehydration cyclization reaction, or the polyamic acid (P) contained in the reaction solution may be isolated and then subjected to a dehydration cyclization reaction, or the isolated polyamic acid (P) may be purified and then subjected to a dehydration cyclization reaction. The isolation and purification of the polyamic acid (P) can be carried out according to known methods.

[0060] (Polyamic acid ester) The polyamic acid ester as the polymer (P) can be obtained, for example, by [I] a method of reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine compound, [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound, and the like.

[0061] In the present specification, the "tetracarboxylic acid diester" means a compound in which two of the four carboxy groups of the tetracarboxylic acid are esterified and the remaining two are carboxy groups. The "tetracarboxylic acid diester dihalide" means a compound in which two of the four carboxy groups of the tetracarboxylic acid are esterified and the remaining two are halogenated.

[0062] Examples of the esterifying agent used in Method [I] include hydroxyl group-containing compounds, acetal compounds, halides, epoxy group-containing compounds, etc. Specific examples thereof include, as the hydroxyl group-containing compound, alcohols such as methanol, ethanol, and propanol, phenols such as phenol and cresol, etc.; as the acetal compound, N,N-dimethylformamide diethyl acetal, N,N-diethylformamide diethyl acetal, etc.; as the halide, methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, 1,1,1-trifluoro-2-iodoethane, etc.; and as the epoxy group-containing compound, propylene oxide, etc.

[0063] The tetracarboxylic acid diester used in Method [II] can be obtained, for example, by ring-opening the tetracarboxylic dianhydride exemplified in the description of the synthesis of polyamic acid (P) using alcohols such as methanol and ethanol. In Method [II], the tetracarboxylic dianhydride may be used in combination. Regarding the diamine compound, the specific diamine exemplified in the synthesis of polyamic acid may be used alone, or other diamines may be used in combination.

[0064] The reaction of Method [II] is preferably carried out in an organic solvent in the presence of a suitable dehydration catalyst. Examples of the organic solvent include the organic solvents exemplified as those used in the synthesis of polyamic acid (P). Examples of the dehydration catalyst include 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium halide, carbonylimidazole, phosphorus-based condensing agents, etc. The reaction temperature at this time is preferably -20 to 150°C, more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0065] The tetracarboxylic acid diester dihalide used in Method [III] can be obtained, for example, by reacting the tetracarboxylic acid diester obtained as described above with a suitable chlorinating agent such as thionyl chloride. In Method [III], a tetracarboxylic dianhydride may be used in combination. Regarding the diamine compound, the specific diamines exemplified in the description of the synthesis of polyamic acid (P) may be used alone, or other diamines may be used in combination.

[0066] The reaction of Method [III] is preferably carried out in an organic solvent in the presence of a suitable base. Examples of the organic solvent can include the organic solvents exemplified as those used in the synthesis of polyamic acid (P). Examples of the base that can be preferably used include tertiary amines such as pyridine and triethylamine; alkali metals such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium, and potassium. The reaction temperature at this time is preferably -20 to 150°C, more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0067] The polyamic acid ester to be contained in the liquid crystal aligning agent may have only an amic acid ester structure, or may be a partial esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving the polyamic acid ester may be directly used for the preparation of the liquid crystal aligning agent, or the polyamic acid ester contained in the reaction solution may be isolated and then used for the preparation of the liquid crystal aligning agent, or the isolated polyamic acid ester may be purified and then used for the preparation of the liquid crystal aligning agent. The isolation and purification of the polyamic acid ester can be carried out according to known methods.

[0068] (Polyimide) The polyimide as the polymer (P) can be obtained, for example, by dehydrating and cyclizing the polyamic acid (P) synthesized as described above to effect imidization.

[0069] The polyimide may be a fully imidized product obtained by dehydrating and cyclizing all of the amic acid structures of its precursor polyamic acid, or may be a partial imidized product in which only a part of the amic acid structure is dehydrated and cyclized, and the amic acid structure and the imide ring structure coexist. The polyimide used in the reaction preferably has an imidization rate of 20% or more, more preferably 30 to 99%, and still more preferably 40 to 99%. This imidization rate is expressed as a percentage of the proportion of the number of imide ring structures to the total of the number of amic acid structures and the number of imide ring structures of the polyimide. Here, a part of the imide ring may be an isoimide ring.

[0070] The dehydration and cyclization of the polyamic acid is preferably carried out by heating the polyamic acid or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration cyclization catalyst to this solution, and heating as necessary.

[0071] In the method of adding a dehydrating agent and a dehydration cyclization catalyst to the solution of the polyamic acid, as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of the dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of the polyamic acid. As the dehydration cyclization catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, triethylamine, and 1-methylpiperidine can be used. The amount of the dehydration cyclization catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of the organic solvent used in the dehydration cyclization reaction include the organic solvents exemplified as those used in the synthesis of the polyamic acid. The reaction temperature of the dehydration cyclization 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.

[0072] In this way, a reaction solution containing polyimide is obtained. This reaction solution may be directly used for the preparation of a liquid crystal aligning agent, or it may be used for the preparation of a liquid crystal aligning agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution, or it may be used for the preparation of a liquid crystal aligning agent after isolating the polyimide, or it may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. These purification operations can be carried out according to known methods. In addition, polyimide can also be obtained by imidization of polyamic acid ester.

[0073] The polyamic acid, polyamic acid ester and polyimide as the polymer (P) obtained as described above preferably have a solution viscosity of 20 to 1,800 mPa·s, more preferably 50 to 1,500 mPa·s when made into a 15% by mass solution. The solution viscosity (mPa·s) of the polymer is the value measured at 25 °C using an E-type rotational viscometer for a 15% by mass polymer solution prepared using a good solvent for the polymer (such as γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0074] The weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the polyamic acid, polyamic acid ester and polyimide as the polymer (P) is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. Also, for the polyamic acid, polyamic acid ester and polyimide as the polymer (P), the molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 8 or less, more preferably 5 or less. By having the Mw and Mw / Mn of the polyamic acid, polyamic acid ester and polyimide as the polymer (P) within the above ranges, good liquid crystal alignment properties of the liquid crystal element can be ensured.

[0075] (Polyorganosiloxane) The polyorganosiloxane as the polymer (P) (hereinafter also referred to as "polyorganosiloxane (P)") is not particularly limited in its production method as long as a polymer having an aliphatic ring with 7 or more ring members in the side chain can be obtained. Specifically, the methods of the following [1s] and [2s] can be mentioned.

[0076] [1s] A method of synthesizing an epoxy group-containing polyorganosiloxane by hydrolytic condensation of a hydrolyzable silane compound (ms-1) having an epoxy group, or a mixture of the silane compound (ms-1) and other silane compounds, and then reacting the obtained epoxy group-containing polyorganosiloxane with a carboxylic acid having an aliphatic ring with 7 or more ring members (specific carboxylic acid). [2s] A method of hydrolytically condensing a hydrolyzable silane compound (ms-2) having an aliphatic ring with 7 or more ring members, or a mixture of the silane compound (ms-2) and other silane compounds. Among these, the method of [1s] is preferable in that it is simple and the introduction rate of the aliphatic ring with 7 or more ring members in the polyorganosiloxane (P) can be increased.

[0077] Specific examples of the silane compound (ms-1) include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylethoxysilane, 4-glycidoxybutyltrimethoxysilane, 4-glycidoxybutylmethyldimethoxysilane, 4-glycidoxybutylmethyldiethoxysilane, 4-glycidoxybutyldimethylmethoxysilane, 4-glycidoxybutyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, etc.

[0078] Other silane compounds used in the synthesis of epoxy group-containing polyorganosiloxanes are not particularly limited as long as they are silane compounds exhibiting hydrolyzability. Specific examples thereof include, for example, alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane; Nitrogen- and sulfur atom-containing alkoxysilanes such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; Unsaturated hydrocarbon-containing alkoxysilanes such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane; trimethoxysilylpropyl succinic anhydride and the like can be mentioned.

[0079] The hydrolysis and condensation reaction of the silane compound can be carried out by reacting one or more of the above silane compounds with water, preferably in the presence of a suitable catalyst and an organic solvent. During the reaction, the usage ratio of water is preferably 1 to 30 moles per 1 mole of the silane compound (total amount). Examples of the catalyst to be used include acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds, and the like. The usage amount of the catalyst varies depending on reaction conditions such as the type of catalyst and temperature, and can be set appropriately. The usage amount of the catalyst is preferably 0.01 to 3 times the molar amount based on the total amount of the silane compound. Examples of the organic solvent to be used include hydrocarbons, ketones, esters, ethers, alcohols, and the like. Among these, it is preferable to use a water-insoluble or poorly water-soluble organic solvent. The usage ratio of the organic solvent is preferably 10 to 10,000 parts by mass per 100 parts by mass of the total silane compound used in the reaction.

[0080] The above hydrolysis and condensation reaction is preferably carried out by heating, for example, using an oil bath. At this time, the heating temperature is preferably 130 °C or lower, and the heating time is preferably 0.5 to 12 hours. After the reaction is completed, the organic solvent layer separated from the reaction solution is dried with a desiccant if necessary, and then the solvent is removed to obtain the target polyorganosiloxane. Note that the synthesis method of the polyorganosiloxane is not limited to the above hydrolysis and condensation reaction, and it may be carried out, for example, by reacting a hydrolyzable silane compound in the presence of oxalic acid and an alcohol.

[0081] In the method of the above [1s], the epoxy group-containing polyorganosiloxane obtained by the above reaction is then reacted with a specific carboxylic acid. Thereby, the epoxy group of the epoxy group-containing polyorganosiloxane reacts with the carboxyl group of the specific carboxylic acid to obtain a polyorganosiloxane (P) having an aliphatic ring with 7 or more ring members in the side chain.

[0082] Specific examples of the specific carboxylic acid include, for example, compounds represented by each of the following formulas (4-1) to (4-6). [Chemical formula]

[0083] The content ratio of the aliphatic ring having 7 or more ring members in one molecule of the polyorganosiloxane (P) is preferably 5 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more with respect to the silicon atoms possessed by the polyorganosiloxane (P). Further, the content ratio of the aliphatic ring having 7 or more ring members in one molecule of the polyorganosiloxane (P) is preferably 90 mol% or less, more preferably 60 mol% or less with respect to the silicon atoms possessed by the polyorganosiloxane (P). When the content ratio of the aliphatic ring having 7 or more ring members in the polyorganosiloxane (P) is within the above range, it is preferable in that a liquid crystal element excellent in liquid crystal alignment can be obtained while sufficiently achieving low voltage driving of the liquid crystal element.

[0084] In addition, when synthesizing the polyorganosiloxane (P), the carboxylic acid used for the reaction with the epoxy group-containing polyorganosiloxane may be only the specific carboxylic acid, but a carboxylic acid having no aliphatic ring having 7 or more ring members (hereinafter, also referred to as "other carboxylic acid") may be used in combination. Examples of the other carboxylic acid include carboxylic acids having a photo-aligning group (for example, a cinnamate structure, a coumarin structure, an azobenzene structure), an alkyl group having 4 to 30 carbon atoms, a halogenated alkyl group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, a halogenated alkoxy group having 4 to 30 carbon atoms, a structure in which one or more rings of a benzene ring and a cyclohexane ring are linked by 2 or more via a single bond or a linking group, a group having a polymerizable carbon-carbon unsaturated bond, or a group having a steroid skeleton, and other compounds such as those described above.

[0085] The reaction between the epoxy group-containing polyorganosiloxane and the carboxylic acid can preferably be carried out in the presence of a catalyst and an organic solvent. As the catalyst to be used, for example, organic bases and compounds known as so-called curing accelerators that promote the reaction of epoxy compounds (for example, tertiary organic amines, quaternary organic amines, quaternary ammonium salts, etc.) can be used. The amount of the catalyst used is preferably 100 parts by mass or less, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the epoxy group-containing polyorganosiloxane.

[0086] Examples of the organic solvent used in the above reaction include hydrocarbons, ethers, esters, ketones, amides, alcohols, etc. The organic solvent is preferably used in a proportion such that the solid content concentration (the proportion of the total mass of the components other than the solvent in the reaction solution to the total weight of the solution) is 0.1% by mass or more, and more preferably in a proportion of 5 to 50% by mass. In the above reaction, the reaction temperature is preferably 0 to 200°C, more preferably 50 to 150°C. The reaction time is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours. After the reaction is completed, it is preferable to wash the organic solvent layer separated from the reaction solution with water. After washing with water, the organic solvent layer is dried with an appropriate desiccant if necessary, and then the solvent is removed to obtain the target polyorganosiloxane (P).

[0087] The polyorganosiloxane (P) preferably has a solution viscosity of 1 to 500 mPa·s, more preferably 3 to 200 mPa·s, when it is made into a 10% by mass solution. For the polyorganosiloxane (P), the weight average molecular weight (Mw) in terms of polystyrene measured by GPC is preferably 1,000 to 200,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000.

[0088] While exhibiting excellent liquid crystal alignment properties (especially AC residual image characteristics), the polymer (P) is preferably an addition polymer among the above, and an addition polymer having no amide group, hydroxy group, amino group, or protected amino group in the structural unit having an aliphatic ring with 7 or more ring members is more preferable in terms of being able to further enhance the effect of improving the low voltage driving of the liquid crystal element.

[0089] The content ratio of the polymer (P) in the liquid crystal aligning agent of the present disclosure is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 30 parts by mass or more with respect to 100 parts by mass of the solid content (components other than the solvent of the liquid crystal aligning agent) contained in the liquid crystal aligning agent.

[0090] <Crosslinking agent> The liquid crystal aligning agent of the present disclosure contains a crosslinking agent together with the polymer (P). Thereby, while aiming at low voltage driving of the liquid crystal element, a liquid crystal alignment film excellent in adhesion can be obtained. Examples of the crosslinking agent include compounds having two or more crosslinkable groups selected from the group consisting of oxiranyl group, protected oxiranyl group, oxetanyl group, thiol group, protected thiol group, carboxy group, protected carboxy group, acid anhydride group, hydroxy group, protected hydroxy group, amino group, protected amino group, protected isocyanate group, and polymerizable carbon-carbon bond in one molecule (however, excluding the polymer (P)).

[0091] The number of crosslinkable groups that the crosslinking agent has in one molecule is preferably 2 to 10, more preferably 2 to 6, from the viewpoint of obtaining a liquid crystal alignment film excellent in adhesion while exhibiting good weak anchoring characteristics. Further, the molecular weight of the crosslinking agent is preferably 100 to 1,000, more preferably 100 to 800, and still more preferably 100 to 600.

[0092] Specific examples of the crosslinking agent include compounds having an oxiranyl group, a protected oxiranyl group or an oxetanyl group, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, triglycidyl isocyanurate, glycerol polyglycidyl ether, pentaerythritol tetraglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, N,N’,N’,N’-tetraglycidyl glycoluril, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N,N,N’,N’-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, N,N-diglycidyl-cyclohexylamine, the epoxidation reaction product of 2,2’-diallylbisphenol A diallyl ether with hydrogen peroxide, compounds represented by the following formulas (d1-1) and (d1-2), and the like.

[0093] Examples of the compound having a thiol group or a protected thiol group include 1,2-ethanedithiol, 1,3-propanedithiol, 1,3,4-thiadiazole-2,5-dithiol, 1,10-decanedithiol, pentaerythritol tetrakis(3-mercaptobutyrate), 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione, and the like. Examples of the compound having a carboxy group, a protected carboxy group or an acid anhydride group include maleic acid, itaconic acid, trimellitic acid, tetracarboxylic acid, cis-1,2,3,4-tetrahydrophthalic acid, ethylene glycol bistrimate, propylene glycol bistrimate, 4,4’-oxydiphthalic acid, trimellitic anhydride, and the like.

[0094] As the compound having a hydroxy group or a protected hydroxy group, a compound having a methylol group, a protected methylol group, a hydroxyalkylamide group or a protected hydroxyalkylamide group can be preferably used. Specific examples thereof include compounds represented by the following formulas (d2-1) to (d2-6), formulas (d3-1) to (d3-8), etc.

[0095] As the compound having an amino group or a protected amino group, compounds represented by the following formulas (d4-1) to (d4-5), etc. can be mentioned. As the compound having a protected isocyanate group, compounds in which the isocyanate group in tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate or diphenylmethane diisocyanate is protected by 3,6-dimethylpyrazole, methyl ethyl ketoxime, diethyl malonate or ε-caprolactam, compounds represented by the following formula (d5-1), etc. can be mentioned.

[0096] As the compound having a polymerizable carbon-carbon bond group, compounds having a (meth)acryloyl group, a maleimide group, an alkenyl group, a vinylphenyl group, a vinyl ether group or a 3-methylenetetrahydrofuran-2(3H)-one-5-yl group can be mentioned. Specific examples thereof include ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, compounds represented by the following formulas (d6-1) to (d6-8), etc.

[0097]

Chemical formula

Chemical formula

[0098] In terms of being able to balance the improvement effect of the liquid crystal alignment and low-voltage drivability and the improvement effect of the adhesion of the liquid crystal alignment film in the liquid crystal element, among the above, the crosslinking agent is preferably a compound having two or more crosslinkable groups selected from the group consisting of an oxiranyl group, a protected oxiranyl group, an oxetanyl group, a hydroxyalkylamide group, a protected hydroxyalkylamide group, an amino group, a protected amino group, and a protected isocyanate group in one molecule, and more preferably a compound having two or more crosslinkable groups selected from the group consisting of an oxiranyl group, a protected oxiranyl group, an oxetanyl group, a hydroxyalkylamide group, and a protected hydroxyalkylamide group in one molecule.

[0099] As the crosslinking agent, a compound having no aromatic ring (hereinafter also referred to as "aliphatic crosslinking agent") can be preferably used in terms of obtaining a liquid crystal element with excellent liquid crystal alignment while sufficiently achieving low-voltage drivability of the liquid crystal element. The aliphatic crosslinking agent may be a compound having a chain structure or may have a cyclic structure. Specific examples of the aliphatic crosslinking agent include compounds having no aromatic ring among the compounds exemplified above.

[0100] The content of the crosslinking agent is preferably 0.5 parts by mass or more, from the viewpoint of enhancing the mechanical properties and adhesion of the liquid crystal alignment film while obtaining a liquid crystal alignment film exhibiting weak anchoring properties, with respect to 100 parts by mass of the total amount of the polymer components contained in the liquid crystal aligning agent (that is, the total amount of the polymer (P) and other polymers). The content of the crosslinking agent is more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, with respect to 100 parts by mass of the total amount of the polymer components. Further, from the viewpoint of obtaining a liquid crystal element exhibiting good liquid crystal alignment properties, the content of the crosslinking agent is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, with respect to 100 parts by mass of the total amount of the polymer components.

[0101] <Other components> In addition to the polymer (P) and the crosslinking agent, the liquid crystal aligning agent of the present disclosure may contain, if necessary, components different from the polymer (P) and the crosslinking agent (hereinafter also referred to as "other components"). Examples of the other components include polymers different from the polymer (P) (hereinafter also referred to as "other polymers"), adhesion aids, solvents, and the like.

[0102] (Other polymers) The other polymer may be a polymer having no aliphatic ring with 7 or more ring members, and the type of its main skeleton is not particularly limited. Examples of the other polymer include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, addition polymer, polybenzoxazole, and the like. Examples of the addition polymer include (meth)acrylic polymers, styrene polymers, maleimide polymers, (meth)acrylic-styrene copolymers, (meth)acrylic-maleimide copolymers, (meth)acrylic-styrene-maleimide copolymers, and styrene-maleimide copolymers.

[0103] From the perspective of obtaining a liquid crystal element with excellent liquid crystal alignment properties and reliability, among the other polymers, it is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and addition polymer, and more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. In terms of forming a liquid crystal alignment film with particularly excellent adhesion, it is particularly preferred that the other polymer is at least one selected from the group consisting of polyamic acid and polyimide.

[0104] When the other polymer is contained in the liquid crystal aligning agent, the content of the other polymer is preferably 99 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent (that is, the total amount of polymer (P) and the other polymer).

[0105] (Adhesion aid) The adhesion aid is a component that improves the adhesion between the liquid crystal alignment film formed using the liquid crystal aligning agent and the substrate or the sealant. As the adhesion aid, a functional silane coupling agent having a reactive functional group can be preferably used. Examples of the reactive functional group of the functional silane coupling agent include a carboxy group, a (meth)acryloyl group, an oxiranyl group, an oxetanyl group, a vinyl group, an isocyanate group, and the like.

[0106] Specific examples of the functional coupling agent include, for example, trimethoxysilylbenzoic acid, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and the like.

[0107] When a adhesion promoter is contained in the liquid crystal aligning agent of the present disclosure, the content of the adhesion promoter is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

[0108] (Solvent) The liquid crystal aligning agent of the present disclosure is preferably prepared as a liquid composition in which a polymer (P), a crosslinking agent, and components used as needed are dispersed or dissolved in a suitable solvent.

[0109] An organic solvent is preferably used as the solvent. Specific examples thereof include amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and γ-butyrolactam; ureas such as 1,2-dimethyl-2-imidazolidinone and 1,3-dimethyl-2-imidazolidinone; lactones such as γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; (Poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; Alkyl lactates such as methyl lactate, ethyl lactate, butyl lactate; alkyl alcohols which may have a linear, branched or cyclic structure such as methanol, ethanol, propanol, butanol, isopropanol, isobutanol, t-butanol, octanol, 2-ethylhexanol, cyclohexanol; alkoxy alcohols such as 3-methoxy-1-butanol; keto alcohols such as diacetone alcohol; (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate; ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, tetrahydrofuran; ketones such as methyl ethyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, 2-heptanone, 3-heptanone; Diacetates such as propylene glycol diacetate, 1,3-butylene glycol diacetate, 1,6-hexanediol diacetate; alkoxycarboxylic acid esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, 3-methyl-3-methoxybutyl propionate; other esters such as ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-amyl formate, i-amyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl 2-oxobutanoate; aromatic hydrocarbons such as toluene, xylene; phenols such as phenol, methylphenol; etc. are included.

[0110] As other components to be incorporated into the liquid crystal aligning agent, in addition to the above, for example, surfactants, antioxidants, metal chelate compounds, curing accelerators, fillers, dispersants, photosensitizers, etc. can be mentioned. The blending ratio of other components can be appropriately selected according to each compound within the range that does not impair the effects of the present disclosure.

[0111] The solid content concentration in the liquid crystal aligning agent (the ratio of the total mass of components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc. The solid content concentration of the liquid crystal aligning agent is preferably in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, it is suitable in that a sufficient film thickness of the coating film can be ensured and a liquid crystal alignment film showing better liquid crystal alignment properties can be obtained. Also, when the solid content concentration is 10% by mass or less, the coating film can be made to have an appropriate thickness, and a liquid crystal alignment film showing good liquid crystal alignment properties is easily obtained. Furthermore, the viscosity of the liquid crystal aligning agent becomes appropriate, and good coatability can be ensured.

[0112] ≪Weak Anchoring Liquid Crystal Alignment Film and Method for Producing the Same≫ The liquid crystal alignment film of the present disclosure is a weak anchoring film produced by the liquid crystal aligning agent prepared as described above. Here, "weak anchoring" means that the alignment regulating force of liquid crystal molecules is substantially zero in the in-plane direction, and even if the horizontal alignment of liquid crystal molecules is forced, the alignment regulating force in the in-plane direction is substantially zero. In a state of weak anchoring (also referred to as zero surface anchoring), the in-plane alignment direction can be freely rotated by 360° by control with an external field such as an electric field or a magnetic field.

[0113] The method for producing a weak anchoring liquid crystal alignment film using the liquid crystal aligning agent of the present disclosure is not particularly limited, and it can be carried out in the same manner as the method for producing a liquid crystal alignment film using a conventionally known liquid crystal aligning agent. In terms of being able to easily perform film formation, a method of applying the liquid crystal aligning agent of the present disclosure on a substrate and preferably heating the coating surface to form it is preferred.

[0114] The substrate on which the liquid crystal alignment film is formed is not particularly limited. As the substrate, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, poly(alicyclic olefin) can be used.

[0115] The method for applying the liquid crystal aligning agent to the substrate is not particularly limited. The application of the liquid crystal aligning agent can be carried out, for example, by a spin coating method, a printing method (for example, an offset printing method, a flexographic printing method, etc.), an inkjet method, a slit coating method, a bar coater method, an extrusion die method, a direct gravure coater method, a chamber doctor coater method, an offset gravure coater method, an impregnation coater method, an MB coater method, etc.

[0116] After applying the liquid crystal aligning agent, preheating (pre-baking) is preferably carried out for the purpose of preventing the liquid crystal aligning agent from dripping. The pre-baking temperature is preferably 30 to 200 °C, and the pre-baking time is preferably 0.25 to 10 minutes. Thereafter, a baking (post-baking) process is carried out for the purpose of further removing the solvent. The baking temperature (post-baking temperature) is preferably 80 to 280 °C, more preferably 80 to 250 °C. The post-baking time is preferably 5 to 200 minutes. The film thickness of the formed film is preferably 0.001 to 2.5 μm. By the above operations, a weakly anchoring liquid crystal alignment film can be easily manufactured. In addition, an alignment treatment (for example, a rubbing alignment treatment or a photo-alignment treatment) may be performed on the coating film after post-baking, whereby a weakly anchoring liquid crystal alignment film may be obtained.

[0117] ≪Liquid Crystal Element and Method for Manufacturing the Same≫ The liquid crystal element of the present disclosure includes a weak anchoring liquid crystal alignment film formed using the liquid crystal aligning agent described above. The driving method of the liquid crystal in the liquid crystal element is not particularly limited, and it can be applied to various modes such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS type, FFS type, OCB (Optically Compensated Bend) type, PSA type (Polymer Sustained Alignment), ECB (Electrically Controlled Birefringence) type, etc. Among these, it can be preferably applied to liquid crystal elements in horizontal modes such as IPS type and FFS type. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. The substrate used in step 1 differs depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

[0118] <Step 1: Formation of a coating film> First, a liquid crystal aligning agent is applied to each substrate surface of a pair of substrates, and preferably, a coating film is formed on the substrate by heating the coating surface. The liquid crystal element of the present disclosure is preferably manufactured by a method including a step of applying a liquid crystal aligning agent for forming a strong anchoring liquid crystal alignment film to one of the pair of substrates and a step of applying the liquid crystal aligning agent of the present disclosure (that is, a liquid crystal aligning agent for forming a weak anchoring film) to the other substrate. As the liquid crystal aligning agent for forming a strong anchoring liquid crystal alignment film, a conventionally known liquid crystal aligning agent can be appropriately used.

[0119] For a pair of substrates, for example, when manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with electrodes patterned in a comb shape (hereinafter, also referred to as the "first substrate") and a counter substrate not provided with electrodes (hereinafter, also referred to as the "second substrate") are used. Examples of the electrode include a transparent conductive film. Examples of the transparent conductive film include a NESA film (registered trademark of PPG Industries, Inc., USA) made of tin oxide (SnO 2 ), indium tin oxide (In 2 O 3 -SnO 2) An ITO film or the like can be used. As an aspect of forming a liquid crystal alignment film on the first substrate and the second substrate, there are an aspect of forming a strongly anchoring liquid crystal alignment film on the first substrate and a weakly anchoring liquid crystal alignment film on the second substrate (the first aspect); an aspect of forming a weakly anchoring liquid crystal alignment film on the first substrate and a strongly anchoring liquid crystal alignment film on the second substrate (the second aspect). Among these, from the viewpoint of low-voltage driving of the liquid crystal element, the first aspect is preferable.

[0120] <Step 2: Alignment treatment> When manufacturing an IPS-type or FFS-type liquid crystal element, a treatment (alignment treatment) for imparting liquid crystal alignment ability is performed on at least one of the coating films formed on the first substrate and the second substrate in the above step 1. As the alignment treatment, a rubbing treatment of rubbing the surface of the coating film formed on the substrate with cotton, nylon, etc., or a photo-alignment treatment of irradiating the coating film with light to impart liquid crystal alignment ability is preferably used. The alignment treatment may be performed on each of the coating film formed on the first substrate and the coating film formed on the second substrate, or may be performed on only one of the coating film formed on the first substrate and the coating film formed on the second substrate. From the viewpoint of obtaining a liquid crystal element showing good liquid crystal alignment, it is preferable to apply a liquid crystal aligning agent for forming a strongly anchoring liquid crystal alignment film to one of the first substrate and the second substrate, and perform the alignment treatment only on the coating film formed thereby. In this case, the strongly anchoring liquid crystal alignment film may be a rubbed alignment film formed by a rubbing alignment treatment or a photo-alignment film formed by a photo-alignment treatment. The liquid crystal aligning agent used for forming the strongly anchoring liquid crystal alignment film preferably contains a crosslinking agent in that the liquid crystal alignment and adhesion can be made more excellent, and it is more preferable that the crosslinking agent does not have an aromatic ring in that the improvement effect of low-voltage driving of the liquid crystal element is high.

[0121] According to the weak anchoring liquid crystal alignment film formed by the liquid crystal aligning agent of the present disclosure, a liquid crystal element showing good liquid crystal alignment can be obtained without performing alignment treatments such as rubbing alignment treatment or photo-alignment treatment. Utilizing such characteristics, the weak anchoring liquid crystal alignment film formed by the liquid crystal aligning agent of the present disclosure may be disposed as a protective film provided on a color filter in a liquid crystal element, and the weak anchoring liquid crystal alignment film may be given functions as a protective film (specifically, planarization and protection from impurities, humidity, etc.).

[0122] <Step 3: Construction of Liquid Crystal Cell> Prepare two substrates on which the liquid crystal alignment film is formed as described above, and manufacture a liquid crystal cell in which a liquid crystal layer is disposed between the two opposed substrates. To manufacture a liquid crystal cell, for example, a method in which two substrates are opposed to each other with a gap therebetween so that the liquid crystal alignment films face each other, the peripheral portions of the two substrates are bonded together with a sealing agent, and liquid crystal is injected and filled into a cell gap surrounded by the substrate surface and the sealing agent and the injection holes are sealed; a method by the ODF method; and the like can be mentioned. As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers can be used. Examples of the liquid crystal constituting the liquid crystal layer include nematic liquid crystal and smectic liquid crystal, and among them, nematic liquid crystal is preferable.

[0123] When manufacturing a liquid crystal display device, subsequently, a polarizing plate is bonded to the outer surface of the liquid crystal cell. Examples of the polarizing plate include a polarizing plate in which a polarizing film called an "H film" that absorbs iodine while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films, or a polarizing plate composed of the H film itself.

[0124] The liquid crystal element of the present disclosure can be effectively applied to various uses. Specifically, for example, it can be used as various display devices such as watches, portable game machines, word processors, notebook personal computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, and also as a dimming device, a retardation film, and the like.

[0125] According to the present disclosure described in detail above, the following means are provided. 〔Means 1〕A liquid crystal aligning agent for forming a weak anchoring film used for forming a weak anchoring liquid crystal alignment film, which contains a polymer (P) having an aliphatic ring with 7 or more ring members in a side chain and a crosslinking agent. 〔Means 2〕The liquid crystal aligning agent for forming a weak anchoring film according to 〔Means 1〕, wherein the crosslinking agent has no aromatic ring. 〔Means 3〕The liquid crystal aligning agent for forming a weak anchoring film according to 〔Means 1〕 or 〔Means 2〕, wherein the polymer (P) is at least one selected from the group consisting of an addition polymer, a polyamic acid, a polyamic acid ester, a polyimide, and a polyorganosiloxane. 〔Means 4〕The liquid crystal aligning agent for forming a weak anchoring film according to any one of 〔Means 1〕 to 〔Means 3〕, wherein the polymer (P) has an aliphatic ring with 8 or more ring members in a side chain. 〔Means 5〕The liquid crystal aligning agent for forming a weak anchoring film according to any one of 〔Means 1〕 to 〔Means 4〕, which further contains a polymer (Q) having no aliphatic ring with 7 or more ring members in a side chain. 〔Means 6〕The liquid crystal aligning agent for forming a weak anchoring film according to 〔Means 5〕, wherein the polymer (Q) is at least one selected from the group consisting of a polyamic acid, a polyamic acid ester, and a polyimide. 〔Means 7〕A method for manufacturing a liquid crystal alignment film, which forms a weak anchoring liquid crystal alignment film using the liquid crystal aligning agent according to any one of 〔Means 1〕 to 〔Means 6〕. 〔Means 8〕A method for manufacturing a liquid crystal element including a pair of substrates including a first substrate and a second substrate and a liquid crystal layer disposed between the pair of substrates, which includes a step of applying the liquid crystal aligning agent for forming a weak anchoring film according to any one of 〔Means 1〕 to 〔Means 6〕 on at least one of the surfaces of the first substrate and the second substrate to form a weak anchoring liquid crystal alignment film. [Means 9] A method for manufacturing a liquid crystal element according to [Means 8], further including a step of forming the weak anchoring liquid crystal alignment film on the surface of one of the first substrate and the second substrate, and forming a strong anchoring liquid crystal alignment film having an anchoring energy stronger than that of the weak anchoring liquid crystal alignment film on the surface of the substrate different from the substrate on which the weak anchoring liquid crystal alignment film is formed among the first substrate and the second substrate. [Means 10] A method for manufacturing a liquid crystal element according to [Means 9], wherein the strong anchoring liquid crystal alignment film is a rubbed alignment film or a photo-alignment film. [Means 11] A method for manufacturing a liquid crystal element according to [Means 9] or [Means 10], wherein the first substrate has a pair of electrodes, the second substrate has no electrode, the strong anchoring liquid crystal alignment film is formed on the surface of the first substrate, and the weak anchoring liquid crystal alignment film is formed on the surface of the second substrate.

Example

[0126] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

[0127] In the following examples, the imidization ratio of polyimide and the molecular weights (Mw, Mn) of the polymers were measured by the following methods. <Imidization ratio of polyimide> The polyimide solution was poured into pure water, and the obtained precipitate was sufficiently dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and 1 1H-NMR measurement was performed at room temperature using tetramethylsilane as a reference substance. From the obtained 1 1H-NMR spectrum, the imidization ratio [%] was determined by the following formula (1). Imidization ratio [%] = (1 - (β 1 / (β 2 × α))) × 100 …(1) (In formula (1), β 1 is the peak area derived from the proton of the NH group appearing around a chemical shift of 10 ppm, and β 2is the peak area derived from other protons, and α is the ratio of the number of other protons to one proton of the NH group in the precursor of the polymer (polyamic acid).) <Molecular weight (Mw, Mn) of the polymer> The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions. Apparatus: "GPC-101" manufactured by Showa Denko K.K. GPC column: "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" manufactured by Shimadzu GL Sciences Inc. were connected Mobile phase: Tetrahydrofuran (THF) Column temperature: 40 °C Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[0128] The abbreviations of the compounds used in the following examples are shown below. For convenience, "the compound represented by formula (X)" may be simply referred to as "compound (X)" hereinafter. "Parts" and "%" in the examples and comparative examples are based on mass unless otherwise specified.

[0129] (Monomer having an unsaturated bond) MA-1 to MA-9

Chemical formula

[0130] (Monomer having an unsaturated bond) MB-1 to MB-12

Chemical formula

[0131] (Tetracarboxylic dianhydride) T-1 to T-9

Chemical formula

[0132] (Diamine) DA-1 to DA-4, daa-1, daa-2 [Chem.]

[0133] (Diamine) DB-1 to DB-18 [Chem.]

[0134] (Additive) AD-1 to AD-7 [Chem.]

[0135] (Synthesis of Polymer) 1. Synthesis of Styrene-Maleimide Copolymer [Synthesis Example 1] Under nitrogen, into a 100 mL two-necked flask, 35 mol parts of compound (MB-4), 45 mol parts of compound (MB-1) and 20 mol parts of compound (MB-1) were added with respect to a total of 100 mol parts of polymerization monomers, 0.3922 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (10 parts by mass with respect to 100 parts by mass of the total amount of polymerization monomers) as a radical polymerization initiator, and 15.68 g of N-methyl-2-pyrrolidone (NMP) (400 parts by mass with respect to 100 parts by mass of the total amount of polymerization monomers) as a solvent were added, and 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 the target addition polymer (this is designated as polymer (PM-1)).

[0136] [Synthesis Examples 2 to 10] The same operations as in Synthesis Example 1 were carried out except that the types and amounts of the polymerization monomers used were changed as shown in Table 1 to obtain addition polymers (these are designated as polymers (PM-2) to (PM-10)).

[0137] [Table 1]

[0138] 2. Synthesis of Polyamic Acid [Synthesis Example 11] 50 mol parts of compound (T-1) and 50 mol parts of compound (T-2) as tetracarboxylic dianhydrides, and 60 mol parts of compound (DB-6), 20 mol parts of compound (DB-5) and 20 mol parts of compound (DB-8) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP), and reacted at 60 °C for 6 hours to obtain a solution containing 20% by mass of polyamic acid (this is designated as polymer (PAA-1)).

[0139] [Synthesis Examples 12 to 16, 18 to 21, 23] The same operations as in Synthesis Example 11 were carried out except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 2, to obtain polyamic acids (polymers (PAA-2) to (PAA-6), (PAA-8) to (PAA-11), (PAA-13)). In Table 1, the numerical values of the tetracarboxylic dianhydrides (acid dianhydrides 1 to 3) represent the ratio (molar ratio) of each compound to the total amount of 100 mol parts of the tetracarboxylic dianhydrides used in the synthesis of the polymer. The numerical values of the diamine compounds (diamines 1 to 4) represent the ratio (molar ratio) of each compound to the total amount of 100 mol parts of the diamine compounds used in the synthesis of the polymer.

[0140] 3. Synthesis of Polyimide [Synthesis Example 17] 50 mol parts of compound (T-1) and 50 mol parts of compound (T-2) as tetracarboxylic dianhydrides, and 60 mol parts of compound (DA-4), 20 mol parts of compound (DB-5) and 20 mol parts of compound (DB-8) as diamine compounds were dissolved in NMP, and reacted at 60 °C for 6 hours to obtain a solution containing 20 mass% of polyamic acid. Next, NMP was added to the obtained polyamic acid solution to make a solution having a polyamic acid concentration of 10 mass%, and pyridine and acetic anhydride were added thereto, followed by performing a dehydration ring-closing reaction at 80 °C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15 mass% of polyimide (this is referred to as polymer (PAA-7)) having an imidization rate of about 50%.

[0141] [Synthesis Examples 22, 24] The same operations as in Synthesis Example 17 were carried out except that the types and amounts of the tetracarboxylic dianhydride and diamine compounds used were changed as shown in Table 2, to obtain polyimides (polymers (PAA-12), (PAA-14)).

[0142] [Table 2]

[0143] [Preparation and Evaluation of Liquid Crystal Alignment Agent] [Example 1: Rubbing Alignment FFS-Type Liquid Crystal Display Element] 1. Preparation of Liquid Crystal Alignment Agent (1) Preparation of Liquid Crystal Alignment Agent for Weak Anchoring Film Formation To a solution containing 100 mass parts of the polymer (PM-2) obtained in Synthesis Example 2, 7 mass parts of compound (AD-2) and 2 mass parts of compound (AD-5) were added, and further diluted with N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (GBL), butyl cellosolve (BC), diacetone alcohol (DAA) and diethylene glycol diethyl ether (DEDG) to obtain a solution having a solvent composition of NMP:GBL:BC:DAA:DEDG = 30:30:15:15:10 (mass ratio) and a solid content concentration of 3.5 mass%. This solution was filtered through a filter having a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

[0144] (2) Preparation of Liquid Crystal Alignment Agent for Forming Strong Anchoring Film by Rubbing Alignment Method A solution containing 70 parts by mass of the polymer (PAA-11) obtained in Synthesis Example 21 and a solution containing 30 parts by mass of the polymer (PAA-13) obtained in Synthesis Example 23 were mixed. 3 parts by mass of the compound (AD-1) was added to this mixed solution, and it was further diluted with NMP, GBL, BC, DAA, and DEDG to obtain a solution having a solvent composition of NMP:GBL:BC:DAA:DEDG = 30:30:15:15:10 (mass ratio) and a solid content concentration of 3.5% by mass. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-R1). (3) Manufacture and Evaluation of Liquid Crystal Display Element The FFS type liquid crystal display element 10 shown in FIG. 1 was manufactured and various characteristic evaluations were performed. When manufacturing the FFS type liquid crystal display element 10, first, on one surface of the glass substrate 11a, a substrate (referred to as the first substrate) having an electrode pair in which a bottom electrode 15 without a pattern, an insulating layer 14 made of a silicon nitride film, and a top electrode 13 patterned in a comb shape were formed in this order, and a counter glass substrate 11b (referred to as the second substrate) without an electrode were prepared. A plan schematic view of the used top electrode 13 is shown in FIG. 2. Note that FIG. 2(a) is a top view of the top electrode 13, and FIG. 2(b) is an enlarged view of the portion C1 surrounded by the broken line in FIG. 2(a). In this example, the line width d1 of the electrode was 4 μm and the distance d2 between the electrodes was 6 μm. Also, as the top electrode 13, four systems of driving electrodes, namely electrode A, electrode B, electrode C, and electrode D, were used (FIG. 3). Note that the bottom electrode 15 functions as a common electrode acting on all of the four systems of driving electrodes, and each of the regions of the four systems of driving electrodes becomes a pixel region. In FIG. 1, reference numeral 12 represents a liquid crystal alignment film and reference numeral 16 represents a liquid crystal layer.

[0145] (i) Formation of Weak Anchoring Liquid Crystal Alignment Film The weakly anchoring liquid crystal aligning agent (AL-1) prepared in (1) above was applied to one substrate surface of the second substrate using a spin coater, heated on a hot plate at 80°C for 1 minute, and then heated in an oven at 230°C with the inside of the oven purged with nitrogen for 30 minutes to form a weakly anchoring liquid crystal alignment film with an average film thickness of 100 nm.

[0146] (ii) Formation of a strongly anchoring liquid crystal alignment film by the rubbing alignment method The strongly anchoring liquid crystal aligning agent (AL-R1) prepared in (2) above was applied to the electrode formation surface of the first substrate using a spin coater, heated on a hot plate at 80°C for 1 minute, and then heated in an oven at 230°C with the inside of the oven purged with nitrogen for 30 minutes to form a coating film with an average film thickness of 100 nm. On the surface of this coating film, a rubbing treatment was performed twice using a rubbing machine having a roll wrapped with a rayon cloth at a roll rotation speed of 1,000 rpm, a stage moving speed of 30 mm / second, and a felt pressing length of 0.3 mm. At this time, the rubbing direction was set so as to be parallel to the direction of the double-headed arrow in Fig. 2(b). The coating film subjected to the rubbing alignment treatment was ultrasonically cleaned in ultrapure water for 1 minute and then dried in an oven at 100°C for 10 minutes to form a strongly anchoring liquid crystal alignment film.

[0147] (iii) Manufacture of an FFS type liquid crystal display element An epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was applied by dispenser to the outer periphery of the surface having one liquid crystal alignment film among the substrates prepared in (i) and (ii) above, leaving a liquid crystal injection port. Thereafter, the surfaces of the pair of substrates having the liquid crystal alignment films were opposed to each other and pressed together, and the adhesive was thermally cured at 150°C for 1 hour. Next, a negative nematic liquid crystal (Merck, MLC-6608, Δn = 0.083) was filled into the gap between the substrates through the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy-based adhesive. Further, in order to remove the flow alignment during liquid crystal injection, it was heated at 120°C and then gradually cooled to room temperature.

[0148] (iv) Evaluation of adhesion The weakly anchoring liquid crystal aligning agent (AL-1) prepared in the above (1) and the strongly anchoring liquid crystal aligning agent (AL-R1) prepared in the above (2) were respectively applied onto a glass substrate using a spin coater, heated on a hot plate at 80 °C for 1 minute, and then heated in an oven at 230 °C with the inside of the oven replaced by nitrogen for 30 minutes, to fabricate two glass substrates each with a coating film having an average film thickness of 100 nm. Next, a liquid crystal sealant (manufactured by Sekisui Chemical Co., Ltd., S-WB21) was applied to the central portion of the surface of one glass substrate having the coating film, and the glass substrate was bonded to the other glass substrate having the coating film so that they were in contact with the liquid crystal sealant. The application amount of the liquid crystal sealant was set such that the diameter of the liquid crystal sealant after bonding the substrates was 4 mm. Thereafter, after irradiating with light of 30,000 J / m 2 (in terms of 365 nm conversion), it was heated in an oven at 120 °C for 1 hour to obtain an evaluation cell. Thereafter, using a small benchtop tester (model number: EZ-LX) manufactured by Shimadzu Corporation, the evaluation cell was pushed in, and the pressure (N) at the time when the film peeled off (mainly peeling due to interfacial failure between the liquid crystal sealant and the film or cohesive failure inside the liquid crystal sealant) was measured. By dividing the pressure (N) at the time of peeling by the area (mm 2 ) of the liquid crystal sealant, the adhesion of the film to the liquid crystal sealant and the substrate (N / mm 2 ) was calculated. The evaluation was such that when the measured value of the pressure was 1.5 N / mm 2 or more, it was rated as "good (◎)", when it was 1.0 N / mm 2 or more and less than 1.5 N / mm 2 , it was rated as "acceptable (○)", and when it was less than 1.0 N / mm 2 , it was rated as "defective (×)". As a result, in this example, the evaluation was "acceptable (○)".

[0149] (v) Evaluation of low voltage driving The liquid crystal display element manufactured in the above (iii) was sandwiched between two polarizing plates so that the luminance was minimized, and the liquid crystal display element was set between a backlight set so that the optical axes were aligned and a luminance meter. Thereafter, a voltage was applied to the liquid crystal display element up to 10 V at intervals of 0.1 V. A V-T curve was obtained by measuring the luminance with respect to the applied voltage, and the value of the voltage at which the luminance became maximum was estimated. For the evaluation, a liquid crystal display element in which a liquid crystal alignment film was formed by a rubbing alignment method using a strong anchoring liquid crystal aligning agent (AL-R1) prepared in the above (2) in the same manner as the first substrate was also used for the second substrate was prepared as a reference cell, and it was judged by how much the maximum luminance voltage of the liquid crystal display element manufactured in each example was reduced in voltage with respect to the maximum luminance voltage of the reference cell. Those in which the maximum luminance voltage of the liquid crystal display element manufactured in the above (iii) was reduced in voltage by 0.8 V or more with respect to the maximum luminance voltage of the reference cell were rated as "good (◎)", and those in which the voltage was reduced by 0.4 V or more and less than 0.8 V with respect to the maximum luminance voltage of the reference cell were rated as "acceptable (○)", and those in which the voltage reduction with respect to the maximum luminance voltage of the liquid crystal display element of the reference cell was less than 0.4 V were rated as "defective (×)". As a result, in this example, the evaluation was "acceptable (○)".

[0150] (vi) Evaluation of liquid crystal alignment property (AC afterimage property) Regarding the liquid crystal display element manufactured in the above (iii), the change in the liquid crystal azimuth angle before and after applying an alternating current voltage that gives the maximum luminance and driving for 2 days was measured with a birefringence meter (AXOSTEP high-precision Mueller matrix imaging polarimeter manufactured by AXOMETRICS). For the evaluation, a change in the liquid crystal azimuth angle of less than 0.5 degrees was rated as "good (◎)", 0.5 degrees or more and less than 1 degree was rated as "acceptable (○)", and 1 degree or more was rated as "defective (△)". The smaller the change in the liquid crystal azimuth angle, the less likely it is that an AC afterimage will occur even when the liquid crystal display element is driven for a long time, and it can be said that the liquid crystal alignment property is good. As a result, in this example, the evaluation was "good (◎)".

[0151] [Examples 2, 3, 7 to 10, 12, 13, Comparative Examples 1 to 7] A liquid crystal aligning agent was prepared and a liquid crystal alignment film was formed in the same manner as in Example 1 except that the polymers and additives contained in the weakly anchoring liquid crystal aligning agent were changed as shown in Table 3 below. Then, a rubbing-aligned FFS type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 3 below.

[0152] [Example 4] A liquid crystal aligning agent was prepared and a liquid crystal alignment film was formed in the same manner as in Example 1 except that the polymers and additives contained in the weakly anchoring liquid crystal aligning agent were changed as shown in Table 3 below, and that a rubbing alignment treatment was also performed on the liquid crystal alignment film formed by the weakly anchoring liquid crystal aligning agent. Then, a rubbing-aligned FFS type liquid crystal display element was manufactured and various evaluations were performed. Note that the conditions for the rubbing alignment treatment on the liquid crystal alignment film formed by the weakly anchoring liquid crystal alignment film were the same as those for the rubbing alignment treatment on the liquid crystal alignment film formed by the strongly anchoring liquid crystal aligning agent. The evaluation results are shown in Table 3 below. In Table 3, the numerical values in the polymer column and the additive column represent the compounding ratio (parts by mass) in terms of solid content with respect to 100 parts by mass of the total amount of the polymer components used in the preparation of the liquid crystal aligning agent.

[0153] [Example 5: Photo-aligned FFS type liquid crystal display element] (1) Preparation of weakly anchoring liquid crystal aligning agent A solution containing 20 parts by mass of the polymer (PM-6) obtained in Synthesis Example 6 and a solution containing 80 parts by mass of the polymer (PAA-8) were mixed. 5 parts by mass of the compound (AD-2) was added to this mixed solution, and further diluted with NMP, N-ethyl-2-pyrrolidone (NEP), GBL, and BC to obtain a solution having a solid content concentration of 4.0% by mass and a solvent composition ratio of NMP:NEP:GBL:BC = 25:25:25:25 (mass ratio). This solution was filtered through a filter with a pore size of 0.2 μm to prepare a weakly anchoring liquid crystal aligning agent (AL-5).

[0154] (2) Preparation of liquid crystal aligning agent for forming strongly anchoring film by photo-alignment method A solution containing 70 parts by mass of the polymer (PAA-11) obtained in Synthesis Example 21 and a solution containing 30 parts by mass of the polymer (PAA-14) obtained in Synthesis Example 24 were mixed. 3 parts by mass of the compound (AD-2) was added to this mixed solution, and it was further diluted with NMP, NEP, GBL, and BC to obtain a solution with a solvent composition of NMP:NEP:GBL:BC = 25:25:25:25 (mass ratio) and a solid content concentration of 3.5% by mass. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-P1).

[0155] (3) Manufacture and evaluation of liquid crystal display elements The FFS type liquid crystal display element 10 shown in FIG. 1 was manufactured and various characteristic evaluations were performed. (i) Formation of a strongly anchoring liquid crystal alignment film by the photo-alignment method The strongly anchoring liquid crystal alignment agent (AL-P1) prepared in (2) above was applied to the electrode formation surface of the first substrate using a spin coater. Next, it was heated on a hot plate at 80°C for 1 minute, and then heated in an oven at 230°C with the inside of the oven replaced with nitrogen for 30 minutes to form a coating film with an average film thickness of 100 nm. On the surface of this coating film, ultraviolet light containing a linearly polarized 254 nm emission line with a dose of 200 mJ / cm 2 was irradiated from the substrate normal direction to perform a photo-alignment treatment. At this time, the polarization plane direction of the polarized ultraviolet light was set so that the direction of the line segment projected onto the substrate was orthogonal to the direction of the double-headed arrow in FIG. 2(b). The coating film subjected to the photo-alignment treatment was heated in an oven at 230°C with the inside of the oven replaced with nitrogen for 30 minutes to perform a heat treatment, thereby forming a strongly anchoring liquid crystal alignment film.

[0156] (ii) Formation of a weakly anchoring liquid crystal alignment film The weakly anchoring liquid crystal alignment agent (AL-5) prepared in (1) above was applied to one surface of the second substrate using a spin coater, heated on a hot plate at 80°C for 1 minute, and then heated in an oven at 230°C with the inside of the oven replaced with nitrogen for 30 minutes to form a weakly anchoring liquid crystal alignment film with an average film thickness of 100 nm.

[0157] (iii) Manufacture of FFS type liquid crystal display elements Using the pair of substrates prepared in (i) and (ii) above, an FFS type liquid crystal display element was manufactured in the same manner as in Example 1.

[0158] (iv) Evaluation of adhesion Using the weak anchoring liquid crystal aligning agent (AL-5) prepared in (1) above and the strong anchoring liquid crystal aligning agent (AL-P1) prepared in (2) above, the adhesion was evaluated in the same manner as in Example 1. As a result, the evaluation in this example was "good (◎)". (v) Evaluation of low voltage drive Regarding the liquid crystal display element manufactured in (iii) above, the low voltage drive was evaluated in the same manner as in Example 1. As a result, the evaluation in this example was "good (◎)". (vi) Evaluation of liquid crystal alignment (AC afterimage characteristics) Regarding the liquid crystal display element manufactured in (iii) above, the liquid crystal alignment (AC afterimage characteristics) was evaluated in the same manner as in Example 1. As a result, the evaluation in this example was "good (◎)".

[0159] [Examples 6, 11] A liquid crystal aligning agent was prepared in the same manner as in Example 5 except that the polymer and additives contained in the weak anchoring liquid crystal aligning agent were changed as shown in Table 3 below, and a liquid crystal alignment film was formed. Then, a photo-aligned FFS type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 3 below.

[0160]

Table 3

[0161] As shown in Table 3, in Examples 1 to 13, the evaluations of adhesion, low-voltage drivability, and liquid crystal alignment were all good or acceptable, and the balance of various characteristics was achieved. Also, in Examples 1 to 13, it was possible to improve the adhesion of the liquid crystal alignment film while maintaining low-voltage drivability and good liquid crystal alignment of the liquid crystal element. Furthermore, by using a crosslinking agent having no aromatic ring, there was a tendency that low-voltage drivability of the liquid crystal element could be further enhanced (Examples 3, 5, 9). Also, by using an addition polymer as the polymer (P), the liquid crystal element tended to be easily driven at a low voltage and the liquid crystal alignment became better.

[0162] On the other hand, in Comparative Examples 1 to 3, 6, 7 using a polymer having no aliphatic ring with 7 or more ring members instead of the polymer (P) and Comparative Examples 4, 5 using a polymer having an aliphatic ring with 7 or more ring members in the main chain, the evaluations of low-voltage drivability and liquid crystal alignment of the liquid crystal element were poor and inferior to those of Examples 1 to 13.

[0163] From the above results, it became clear that according to the liquid crystal alignment agent of the present disclosure, while showing excellent liquid crystal alignment, it was possible to sufficiently achieve low-voltage drivability of the liquid crystal element due to weak anchoring of the liquid crystal alignment film, and moreover, it was possible to form a liquid crystal alignment film having excellent adhesion.

Explanation of Reference Numerals

[0164] 10…FFS type liquid crystal display element, 11a, 11b…glass substrate, 12…liquid crystal alignment film, 13…top electrode, 14…insulating layer, 15…bottom electrode

Claims

1. A liquid crystal aligning agent for forming a weak anchoring film, which is used for forming a weak anchoring liquid crystal aligning film, comprises a polymer (P) having an aliphatic ring with 7 or more ring members in a side chain, a crosslinking agent, and is a liquid crystal aligning agent for forming a weak anchoring film.

2. The liquid crystal aligning agent for forming a weak anchoring film according to Claim 1, wherein the crosslinking agent has no aromatic ring.

3. The liquid crystal aligning agent for forming a weak anchoring film according to Claim 1 or 2, wherein the polymer (P) is at least one selected from the group consisting of an addition polymer, a polyamic acid, a polyamic acid ester, a polyimide, and a polyorganosiloxane.

4. The liquid crystal aligning agent for forming a weak anchoring film according to Claim 1 or 2, wherein the polymer (P) has an aliphatic ring with 8 or more ring members in a side chain.

5. The liquid crystal aligning agent for forming a weak anchoring film according to Claim 1 or 2, further comprising a polymer (Q) having no aliphatic ring with 7 or more ring members in a side chain.

6. The liquid crystal aligning agent for forming a weak anchoring film according to Claim 5, wherein the polymer (Q) is at least one selected from the group consisting of a polyamic acid, a polyamic acid ester, and a polyimide.

7. A method for manufacturing a liquid crystal aligning film, which forms a weak anchoring liquid crystal aligning film by using the liquid crystal aligning agent according to Claim 1 or 2.

8. A method for manufacturing a liquid crystal element, which includes a pair of substrates composed of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, and includes a step of applying the liquid crystal aligning agent for forming a weak anchoring film according to Claim 1 or 2 on at least one surface of the first substrate and the second substrate to form a weak anchoring liquid crystal aligning film.

9. Form a weak anchoring liquid crystal aligning film on the surface of one of the first substrate and the second substrate, and further includes a step of forming a strong anchoring liquid crystal aligning film having stronger anchoring energy than the weak anchoring liquid crystal aligning film on the surface of a substrate different from the substrate on which the weak anchoring liquid crystal aligning film is formed among the first substrate and the second substrate. The method for manufacturing a liquid crystal element according to Claim 8.

10. The method for manufacturing a liquid crystal element according to Claim 9, wherein the strong anchoring liquid crystal aligning film is a rubbed aligning film or a photo-aligned film.

11. The first substrate has a pair of electrodes, the second substrate has no electrode, and a strong anchoring liquid crystal aligning film is formed on the surface of the first substrate. The method for manufacturing a liquid crystal element according to claim 9, wherein the weak anchoring liquid crystal alignment film is formed on the surface of the second substrate.

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