TWI814748B - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal element and manufacturing method of liquid crystal alignment film - Google Patents

Abstract

The liquid crystal alignment agent contains polymer components and solvent components. The solvent component contains 1 to 70 mass % of the (A) solvent based on the total amount of the solvent components, and 0 to 40 mass % of the (B) solvent based on the total amount of the solvent components. (A) The solvent is selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, a compound represented by formula (1), and formula (2) ) at least one compound in the group consisting of compounds represented by. The solvent (B) is a compound that has a boiling point at 1 atmosphere of 200° C. or higher and is different from the solvent (A).

(R ¹ is an alkyl group with 1 to 4 carbon atoms. ^{R 2} is an alkyl group with 1 to 4 carbon atoms. R ³ is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms. N is 0 or 1)

Description

Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal element and liquid crystal assembly Manufacturing method of film [Cross-reference to related applications]

This application is based on Japanese Patent Application No. 2017-240060 filed on December 14, 2017, and the contents are incorporated herein by reference.

The invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal element.

Liquid crystal elements are used in various applications including display devices such as televisions, personal computers, and mobile phones, optical compensation films such as retardation films, and light-adjusting films. These liquid crystal elements include a liquid crystal alignment film that has the function of aligning liquid crystal molecules in a certain direction. Generally, a liquid crystal alignment film is formed by coating a liquid crystal alignment agent in which a polymer component is dissolved in an organic solvent on a glass or resin base material and heating the liquid crystal alignment film. As the polymer component of the liquid crystal alignment agent, polyamide or soluble polyimide is widely used because of its excellent mechanical strength, liquid crystal alignment, and affinity with liquid crystal (see, for example, Patent Document 1 and Patent Document 2).

[Prior art documents]

[Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2017-198975

[Patent Document 2] Japanese Patent Application Publication No. 2016-206645

If the liquid crystal alignment agent shrinks when it is coated on the substrate, or if the liquid crystal alignment agent is not uniform and thus causes uneven coating (in-plane unevenness) on the surface of the alignment film, there is a concern that the product yield will decrease. , or the liquid crystal alignment property of the obtained liquid crystal element is insufficient. The coating unevenness occurs, for example, when the film thickness of the liquid crystal alignment film is thicker (for example, 0.3 μm or more) in order to improve the alignment of the liquid crystal alignment film to the liquid crystal or to improve the adhesion between the liquid crystal alignment film and the substrate. Easy to produce. That is, if the film thickness of the liquid crystal alignment film is increased, the solvent cannot be sufficiently removed in the heating step during film formation, and uneven coating on the surface of the alignment film is likely to occur due to the influence of the residual solvent in the alignment film. In this case, there is a concern that the liquid crystal alignment properties of the obtained liquid crystal element are insufficient.

In addition, for example, in the roll-to-roll method, a base material on which an alignment film is laminated in a roll shape may be temporarily stored during the manufacturing process of a liquid crystal element. If there is a large amount of solvent remaining in the alignment film, back-migration of the polymer component or the remaining solvent in the alignment film to the substrate side is likely to occur. In addition, when the back shift to the base material side occurs, the liquid crystal alignment film may be easily peeled off from the base material, or the liquid crystal alignment properties of the obtained liquid crystal element may be deteriorated.

The present disclosure is made in view of the above problems, and one of its purposes is to provide a liquid crystal alignment agent that has good coating properties on a substrate and can sufficiently reduce the residual solvent in the alignment film.

The inventors of the present invention have conducted diligent research to solve the above problems and found that the above problems can be solved by containing a specific solvent with a low boiling point as a solvent component of the liquid crystal alignment agent. Specifically, this disclosure adopts the following means to solve the above-mentioned problems.

<1> A liquid crystal alignment agent containing a polymer component and a solvent component, wherein the solvent component contains 1 to 70 mass % of the following (A) solvent relative to the total amount of the solvent component, and The following (B) solvent is contained in 0 mass % to 40 mass % with respect to the total amount of the solvent component.

(A) The solvent is a compound selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, the following formula (1), and the following at least one compound in the group consisting of compounds represented by formula (2).

The solvent (B) is a compound that has a boiling point at 1 atmosphere of 200° C. or higher and is different from the solvent (A).

(In formula (1), R ¹ is an alkyl group having 1 to 4 carbon atoms)

(In formula (2), R ² is an alkyl group having 1 to 4 carbon atoms, and R ³ is an alkyl group having 1 to 4 carbon atoms. n is 0 or 1).

<2>A liquid crystal alignment film produced by using the liquid crystal alignment agent of <1> form.

<3> A liquid crystal element including the liquid crystal alignment film of <2>.

<4> A method for manufacturing a liquid crystal alignment film, which includes coating the liquid crystal alignment agent of <1> on a substrate and heating it at 150° C. or lower to form a coating film.

The liquid crystal alignment agent of the present disclosure has good coating properties on the substrate, and can fully remove the solvent in the liquid crystal alignment agent during heating during the formation of the alignment film, thereby fully reducing the residual solvent in the alignment film. Thereby, a decrease in product yield can be suppressed, and a high-quality liquid crystal element can be obtained.

Each component contained in the liquid crystal alignment agent of the present disclosure and other components optionally blended as necessary will be described below. The liquid crystal alignment agent of the present disclosure contains polymer components and solvent components. The liquid crystal alignment agent is a liquid polymer composition in which a polymer component is dissolved in a solvent component.

"Polymer Composition"

Regarding the polymer component contained in the liquid crystal alignment agent, the main skeleton is not particularly limited. Examples thereof include: polyamide, polyamide ester, polyimide, polyorganosiloxane, polyester, polyamide Amide, polyamide imine, polybenzoxazole precursor, polybenzoxazole, cellulose derivatives, polyacetal, styrene-maleimide copolymer, poly(methyl) Main skeleton such as acrylate. In addition, (meth)acrylate means including acrylate and methacrylate. From the viewpoint of ensuring sufficient performance of the liquid crystal element, the polymer component is preferably selected from the group consisting of polyamide acid, polyimide, At least one polymer from the group consisting of polyamide ester, polyamide imide, poly(meth)acrylate and polyorganosiloxane (hereinafter also referred to as "(P) polymer") , in terms of enabling lower heating temperatures during film formation, it is more preferred to be at least one selected from the group consisting of poly(meth)acrylate and polyorganosiloxane.

(Polymer containing photosensitive groups)

As the (P) polymer, some or all of the polymers contained in the liquid crystal alignment agent may be polymers having a photosensitive structure (hereinafter also referred to as "photosensitive group-containing polymers"). The photosensitive structure may be any structure or functional group that reacts by sensing light, and examples thereof include photoalignment groups and polymerizable groups.

When the (P) polymer has a photo-alignment group, liquid crystal alignment can be imparted to a coating film produced using a liquid crystal alignment agent by a photo-alignment method. This is preferable in that the effects brought about by the application of the photoalignment method can be obtained. Specifically, the effect is the effect of suppressing display defects or yield reduction due to the generation of dust, static electricity, etc., and can cause damage to the substrate. The organic thin film formed on the liquid crystal evenly imparts the effect of alignment ability to the liquid crystal. In addition, when the polymer (P) has a polymerizable group, it is preferable in terms of improving the adhesion of the liquid crystal alignment film to the substrate and further suppressing the decrease in yield when the roll-to-roll method is used to manufacture the liquid crystal element. .

The photoalignment group is a functional group that imparts anisotropy to the film through photoisomerization reaction, photodimerization reaction, photodecomposition reaction, photo-Friis rearrangement reaction, etc. caused by light irradiation. Specific examples thereof include: an azobenzene structure containing azobenzene or a derivative thereof as a basic skeleton; a cinnamic acid structure containing cinnamic acid or a derivative thereof as a basic skeleton; and a structure containing chalcone or a derivative thereof as a basic skeleton. Skeleton of Chalcone Knot Structure, benzophenone structure containing benzophenone or its derivatives as the basic skeleton, coumarin derivatives containing coumarin or its derivatives as the basic skeleton, containing stilbene or its derivatives as the basic skeleton The stilbene structure, the diphenylacetylene structure containing diphenylacetylene or its derivatives as the basic skeleton, the phenyl benzoate structure containing phenyl benzoate or its derivatives as the basic skeleton, the phenyl benzoate structure containing cyclobutane or its derivatives Derivatives have a cyclobutane structure as the basic skeleton, etc. Among these, the photo-alignment group contained in the polymer (P) is particularly preferably a group having a cinnamic acid structure in view of high reactivity to light.

As a group having a cinnamic acid structure, it is specifically preferred to have a partial structure represented by the following formula (4).

(In formula (4), R ³¹ and R ³² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a cyano group. R ³³ is a halogen atom, An alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a cyano group. a1 is an integer from 0 to 4. When a1 is 2 or more, a plurality of R ³³ may be the same or different. . "*" indicates bonding key)

Examples of the group represented by the formula (4) include a monovalent group obtained by removing the hydrogen atom of the carboxyl group of cinnamic acid, or a monovalent group obtained by introducing a substituent into the benzene ring of the monovalent group. (hereinafter also referred to as "ciscinnamate") group"), or a monovalent group in which the carboxyl group of cinnamic acid is esterified and a divalent organic group is bonded to the benzene ring, or a substituent is introduced into the benzene ring of the monovalent group. groups (hereinafter these are also referred to as "reverse cinnamate groups"), etc. The ciscinnamate group is represented by the following formula (cn-1), for example. The reverse cinnamate group is represented by the following formula (cn-2), for example.

(In formula (cn-1), R ³⁴ is a hydrogen atom, a halogen atom, an alkyl group with 1 to 3 carbon atoms, an alkoxy group with 1 to 3 carbon atoms, or a cyano group. R ³⁵ is a phenyl group or a biphenyl group. group, biphenylene group or cyclohexylene group, or at least a part of the hydrogen atoms of the phenyl group, biphenylene group, biphenylene group or cyclohexylene group is passed through a halogen atom, a cyano group, a carbon number of 1 to 10 A group substituted by any one of an alkyl group, an alkoxy group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. ^{A 11} is a single bond, an oxygen atom, a sulfur atom, or an alkoxy group having 1 to 3 carbon atoms. Alkanediyl, -CH=CH-, -NH-, * ² -COO-, ^* 2 -OCO-, * ² -NH-CO-, * ² -CO-NH-, * ² -CH ₂ -O - or * ² -O-CH ₂ - ("* ² " represents the bond with R ³⁵ ). b1 is 0 or 1. "*" represents the bond.

In formula (cn-2), R ³⁶ is an alkyl group having 1 to 3 carbon atoms. A ¹² is an oxygen atom, * ² -COO-, * ² -OCO-, * ² -NH-CO- or * ² -CO-NH- ("* ² " represents a bond with R ³⁷ ). R ³⁷ is an alkanediyl group having 1 to 6 carbon atoms. c1 is 0 or 1. "*" indicates a bonded key.

R ³¹ , R ³² , R ³³ and a1 have the same meaning as the formula (4))

The polymerizable group is preferably a functional group that induces a crosslinking reaction in response to light. Examples thereof include: (meth)acrylyl group, vinyl group (including vinylphenyl group and vinyloxy group (CH ₂ =CH- O-) and other vinyl-containing groups), vinylene, maleimide, allyl, ethynyl, allyloxy, epoxy, etc. Among these, a (meth)acryl group or a vinyl group is preferable in terms of high reactivity to light. In addition, the (meth)acrylyl group has a meaning including an acrylyl group and a methacrylyl group, and the epoxy group has a meaning including an oxetanyl group and an oxetanyl group.

Among these, the (P) polymer preferably has a photosensitive structure selected from a cinnamic acid structure, an azobenzene structure, a chalcone structure, a stilbene structure, a diphenylacetylene structure, and (meth)acrylamide. At least one of the group consisting of a vinyl group, a vinyl group and a phenyl benzoate structure, particularly preferably a cinnamic acid structure or a (meth)acrylyl group. When the polymer (P) has a photosensitive structure, the content ratio of the photosensitive structure relative to the total amount of monomer units constituting the polymer (P) is preferably 10 mol% or more, more preferably 20 More than mol%.

When using a polymer having a photo-alignment group as the (P) polymer, all of the polymer components of the liquid crystal alignment agent may be a polymer having a photo-alignment group, or a part thereof may be a polymer having a photo-alignment group. Polymer of photoalignment groups. When a part of the polymer component is a polymer having a photo-alignment group, the usage ratio of the polymer is preferably set to It is 1 mass % - 80 mass %, and it is more preferable that it is 2 mass % - 70 mass %.

In addition, when using a polymer having a polymerizable group as the (P) polymer Below, the usage ratio of the polymer relative to the total amount of polymer components used in the preparation of the liquid crystal alignment agent is preferably set to 1 mass % to 80 mass %, and more preferably set to 2 mass % to 70 mass %. Mass %. In addition, one type of photosensitive group-containing polymer may be used alone, or two or more types may be mixed and used.

(liquid crystalline polymer)

As the (P) polymer, some or all of the polymers contained in the liquid crystal alignment agent may have a partial structure in the side chain that exhibits liquid crystallinity in a predetermined temperature range (hereinafter also referred to as "liquid crystalline structure") polymer (hereinafter also referred to as "liquid crystalline polymer"). By containing a liquid crystalline polymer in a liquid crystal alignment agent, it is preferable in terms of further improving the initial voltage retention rate of the liquid crystal element.

Examples of the liquid crystal structure include a structure having a rigid portion (mesogen structure). Specific examples thereof include a structure having a group represented by the following formula (5), and the like.

(In formula (5), Ar ¹ and Ar ² are each independently a substituted or unsubstituted phenyl group or a substituted or unsubstituted cyclohexylene group, and X ²¹ is a single bond, -CO-, - COO-, -C=C-, -C≡C-, -N=N- or -CONR ⁴¹ -(R ⁴¹ is a hydrogen atom or a monovalent organic group). r is an integer from 1 to 3. When r is 2 or 3, Ar ² and X ²¹ independently have the above definitions. "*" indicates a bond)

In the formula (5), X ²¹ is preferably a single bond or -COO-. Examples of the monovalent organic group of R ⁴¹ include an alkyl group having 1 to 6 carbon atoms, a protecting group, and the like. Specific examples of the protecting group include: tert-butoxycarbonyl group, benzyloxycarbonyl group, 1,1-dimethyl-2-haloethyloxycarbonyl group, allyloxycarbonyl group, etc., and preferred ones are It is the third butoxycarbonyl group. The substituent of the ring part of Ar ¹ and Ar ² is preferably an alkyl group having 1 to 5 carbon atoms or a halogen atom, more preferably a methyl group or a fluorine atom.

Preferable specific examples of the partial structure represented by the formula (5) include: 4,4'-biphenyl group, 4,4'-biscyclohexyl group, p-triphenyl group, and Groups represented by the following formulas (5-1) to (5-4) respectively, and groups having a methyl group or a fluorine atom in the ring part of these groups, etc. Furthermore, "*" in the formula (5) and the following formulas (5-1) to (5-4) may also be bonded to a hydrogen atom.

(In the formula, "*" means bonded key)

When the polymer (P) is a liquid crystal polymer, a polymer having a photosensitive group in a side chain can be suitably used as the liquid crystal polymer. Specifically, the liquid crystalline polymer preferably has a group represented by the following formula (F-1) to formula (F-7) in a side chain.

(In formula (F-1) ~ formula (F-7), A ¹ , B ¹ and D ¹ are independently single bonds, -O-, -CH ₂ -, -COO-, -OCO-, -CONH - or -NH-CO-. ^{B 2} is a single bond, -COO-, -OCO-, -N=N-, -C=C-, -C≡C- or phenyl group. Y ¹ is a benzene ring, Naphthalene ring, biphenyl ring, furan ring, pyrrole ring, or a monovalent cyclic group having a cyclic hydrocarbon group with 5 to 8 carbon atoms. At least one hydrogen atom bonded to the ring can be via a halogen atom, nitro group, or cyano group. , -C=C(CN) ₂ , -C=CH-CN, alkyl group with 1 to 3 carbon atoms, or alkoxy group with 1 to 3 carbon atoms substituted. ^{Y 2} is benzene ring, naphthalene ring, biphenyl ring , furan ring, pyrrole ring, or a divalent cyclic group having a cyclic hydrocarbon group with 5 to 8 carbon atoms. At least one hydrogen atom bonded to the ring can be via a halogen atom, nitro group, cyano group, -C=C( CN) ₂ , -C=CH-CN, alkyl group with 1 to 3 carbon atoms, or alkoxy group with 1 to 3 carbon atoms substituted. Y ³ is a monovalent ring with a benzene ring, naphthalene ring or biphenyl ring group, at least one hydrogen atom bonded to the ring can be via a halogen atom, nitro group, cyano group, -C=C(CN) ₂ , -C=CH-CN, an alkyl group with 1 to 3 carbon atoms, or an alkyl group with a carbon number of 1 to 3. 1~3 alkoxy substitution. ^{X 1} is a single bond, -COO-, -OCO-, -N=N-, -C=C-, -C≡C- or phenyl group. R ¹¹ is a hydrogen atom Or an alkyl group with 1 to 6 carbon atoms. R ¹² is a hydrogen atom, a halogen atom, a nitro group, a cyano group, -C=C(CN) ₂ , -C=CH-CN, an alkyl group with 1 to 6 carbon atoms, Or an alkoxy group with 1 to 6 carbon atoms. R ¹³ is a hydrogen atom or an alkyl group with 1 to 3 carbon atoms. k is an integer from 1 to 12, m and j are each independently an integer from 1 to 3, and g is 1 An integer of ~12. Furthermore, at least one hydrogen atom bonded to the benzene ring in formula (F-6) can be passed through a halogen atom, nitro group, cyano group, -C=C(CN) ₂ , -C=CH -CN, alkyl group with 1 to 3 carbon atoms, or alkoxy group with 1 to 3 carbon atoms substituted. "*1" indicates a bond bonded to the main chain)

When part or all of the polymer (P) is a liquid crystal polymer, the liquid crystal polymer is preferably selected from the group consisting of poly(meth)acrylate, polyamide, polyimide, and polyamide. At least one member from the group consisting of acid esters, preferably poly(meth)acrylate. When a liquid crystalline polymer is used as the (P) polymer, the usage ratio of the liquid crystalline polymer may be appropriately in the range of 100% by mass or less of the total amount of polymer components used in the preparation of the liquid crystal alignment agent. settings. In addition, as the liquid crystal polymer, one type may be used alone, or two or more types may be mixed and used.

(synthesis of polymers)

(P) The polymer can be obtained by appropriately combining general methods of organic chemistry according to its main skeleton. Hereinafter, polyamide acid, polyamide imide, polyamide ester, polyamide imide, poly(meth)acrylate, and polyorganosiloxane will be described respectively.

[Polyamide]

Polyamic acid can be obtained by reacting tetracarboxylic dianhydride and a diamine compound.

(tetracarboxylic dianhydride)

Examples of the tetracarboxylic dianhydride used in the synthesis of polyamic acid include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride, and the like. Specific examples of these include, for example, aliphatic tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, etc.; examples of alicyclic tetracarboxylic dianhydride include: 1,2, 3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid 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-spirocyclo-3'-(tetrahydrofuran-2',5'-dione), 2,4,6,8-tetracarboxybicyclo [3.3.0]Octane-2:4,6:8-dianhydride, 4,9-dioxatricyclo[5.3.1.0 ^2,6 ]Undecane-3,5,8,10-tetraone , cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc.; examples of aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene) Diphthalic anhydride, ethylene glycol bis-trimellitic anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-carboxydiphthalic anhydride, etc. In addition, the tetracarboxylic dianhydride described in Japanese Patent Application Laid-Open No. 2010-97188 can also be used. In addition, the tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

(diamine compound)

Examples of the diamine compound used in the synthesis of polyamic acid include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes. Specific examples of these diamines include aliphatic diamines such as m-xylylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, and hexamethylenediamine. Amine, etc.; examples of alicyclic diamines include: 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), etc.; examples of aromatic diamines include: dodecane Oxydiaminobenzene, octadecyloxydiaminobenzene, cholestanyloxydiaminobenzene, cholestyldiaminobenzoate, cholesteryldiaminobenzoate, 3 ,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 1,1-bis(4-((amino Phenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid=5ξ-cholestan-3-yl, the following formula (E-1)

(In formula (E-1), X ^I and X ^II are independently single bonds, -O-, *-COO- or *-OCO- (where "*" represents the bond with X ^I ), R ^I is an alkanediyl group with 1 to 3 carbon atoms, R ^II is a single bond or an alkanediyl group with 1 to 3 carbon atoms, a is 0 or 1, b is an integer from 0 to 2, and c is an integer from 1 to 20. d is 0 or 1. Among them, a and b will not become 0 at the same time)

The represented compounds, diamines having a cinnamic acid structure, diamines having a liquid crystal structure and other diamines containing an alignment group; p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-amine phenyl-4'-aminobenzoate, 4,4'-diaminoazobenzene, 1,5-bis(4-aminophenoxy)pentane, bis[2-(4- Aminophenyl)ethyl]adipic acid, N,N-bis(4-aminophenyl)methylamine, 2,6-diaminopyridine, 1,4-bis(4-aminophenyl) )-piperazine, N,N'-bis(4-aminophenyl)-benzidine, 2,2'- Dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl Ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(phenylene) Diisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl; diaminoorganosiloxane For example, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane can be used. In addition, the diamine described in Japanese Patent Application Laid-Open No. 2010-97188 can also be used.

(Synthesis of polyamide)

Polyamic acid can be obtained by reacting the above-described tetracarboxylic dianhydride and a diamine compound together with a molecular weight adjuster if necessary. The usage ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid is preferably 0.2 to 2 equivalents of the acid anhydride group of the tetracarboxylic dianhydride relative to 1 equivalent of the amine group of the diamine compound. Equivalent ratio. Examples of the molecular weight adjuster include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; phenyl isocyanate, isocyanate Naphthyl acid naphthyl ester and other monoisocyanate compounds, etc. The usage ratio of the molecular weight regulator is preferably 20 parts by mass or less relative to 100 parts by mass in total of the tetracarboxylic dianhydride and the diamine compound used.

The synthesis reaction of polyamide is preferably carried out in an organic solvent. At this time, the reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 hour to 24 hours.

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. Particularly preferred organic solvents are those selected from the group consisting of N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, A group consisting of N,N-dimethylformamide, dimethyltrisoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphotriamine, m-cresol, xylenol and halogenated phenols One or more of the group can be used as a solvent, or a mixture of one or more of these and other organic solvents (for example, butyl cellulose, diethylene glycol diethyl ether, etc.) can be used. The usage amount (a) of the organic solvent is preferably set so that the total amount (b) of the tetracarboxylic dianhydride and the diamine becomes 0.1 mass % to 50 mass % with respect to the total amount of the reaction solution (a + b). quantity.

In this manner, a reaction solution in which polyamide acid is dissolved can be obtained. The reaction solution can be directly used for the preparation of the liquid crystal alignment agent, or the polyamide contained in the reaction solution can be separated and then used for the preparation of the liquid crystal alignment agent.

[Polyamide]

When the polymer (P) is a polyamic acid ester, the polyamic acid ester can be obtained, for example, by the following method: [I] Let the polyamic acid obtained by the synthesis reaction and the ester [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, etc. The polyamic acid ester contained in the liquid crystal alignment agent may only have a amino acid ester structure, or may be a partial esterification product in which the amino acid structure and the amino acid ester structure coexist. Furthermore, the reaction solution obtained by dissolving the polyamic acid ester can be directly used for the preparation of the liquid crystal alignment agent, or the polyamic acid ester contained in the reaction solution can be separated and then used for the preparation of the liquid crystal alignment agent.

[Polyimide]

When the polymer (P) is a polyimide, the polyimide can be obtained by, for example, dehydrating, ring-closing, and imidizing the polyamide acid synthesized as described above. The polyamide imide may be a complete amide imide obtained by dehydration and ring-closure of all the amide acid structures of the polyamide acid as its precursor, or it may be a dehydration and ring-closure of only a part of the amide acid structure. It is a partial amide imide compound in which the amide acid structure and the amide imine ring structure coexist. The polyimide used in the reaction preferably has an imidization rate of 20% to 99%, more preferably 30% to 90%. The acyl imidization rate represents the ratio of the number of amide imine ring structures to the total number of amide acid structures and the number of amide imine ring structures of the polyamide imide as a percentage. Here, part of the imine ring may be an isoimine ring.

The dehydration and ring-closing of polyamide is preferably carried out by the following method: dissolving the polyamide in an organic solvent, adding a dehydrating agent and a dehydration and ring-closing catalyst to the solution, and heating if necessary. In this method, as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The usage amount of the dehydrating agent is preferably 0.01 mole to 20 mole with respect to 1 mole of the amide acid structure of the polyamide acid. As the dehydration ring-closure catalyst, for example, tertiary amines such as pyridine, methylpyridine, dipyridine, and triethylamine can be used. The usage amount of the dehydration closed-loop catalyst is preferably 0.01 mole to 10 mole relative to 1 mole of the dehydrating agent used. Examples of the organic solvent used in the dehydration ring-closure reaction include those exemplified as those used in the synthesis of polyamide. The reaction temperature of the dehydration loop-closure reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 hours to 120 hours. In this way, a reaction solution containing polyimide is obtained. The reaction solution can be directly used for the preparation of the liquid crystal alignment agent, or can be used for the preparation of the liquid crystal alignment agent after the polyimide is separated. Polyimides can also be obtained by imidization of polyamide esters.

The polyamic acid, polyamic acid ester and polyimide obtained in the above manner preferably have a concentration of 10 mPa when made into a solution with a concentration of 10 mass%. s~800mPa． The solution viscosity of s is preferably 15mPa. s~500mPa． The solution viscosity of s. Furthermore, the solution viscosity (mPa.s) of polyamic acid, polyamic acid ester and polyimide is a good solvent for using these polymers (for example, γ-butyrolactone, N-methyl- 2-pyrrolidinone, etc.), measured at 25°C using an E-type rotational viscometer.

The polystyrene-reduced weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of polyamic acid, polyamic acid ester and polyimide is preferably 1,000~ 500,000, preferably 2,000~300,000. In addition, the molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the polystyrene-reduced number average molecular weight (Mn) measured by GPC is preferably 15 or less, more preferably 10 or less. By being in this molecular weight range, good alignment and stability of the liquid crystal display element can be ensured.

[Polyamideimide]

Polyamide imine can be obtained, for example, by a method of condensing a tricarboxylic acid and a diisocyanate compound; or by reacting a tricarboxylic acid with a diamine compound to introduce an imine bond into the molecule, and then A method in which a diisocyanate compound reacts with it to undergo chelation.

Examples of the tricarboxylic acid used in the synthesis of polyamide imide include trimellitic anhydride, butane-1,2,4-tricarboxylic acid, naphthalene-1,2,4-tricarboxylic acid, and the like. Examples of the diisocyanate compound include diphenylmethane-4,4'-diisocyanate, diphenyl Ether-4,4'-diisocyanate, tolylene diisocyanate, xylene diisocyanate, etc. Examples of the diamine compound include diamine compounds exemplified in the synthesis of polyamic acid.

The reaction is preferably carried out in an organic solvent. In the synthesis of the polyamide imide, it is preferable to set the usage ratio of the monomers so that the number of the isocyanate group or the amine group relative to 1 mol in total of the carboxyl group and the acid anhydride group is 0.85 mol to 1.05 mol. amount. The synthesis reaction of polyamide imine is preferably carried out in an organic solvent. At this time, the reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 hour to 24 hours. Examples of the organic solvent used in the reaction include organic solvents exemplified as those used in the synthesis of polyamide. The polystyrene-reduced weight average molecular weight (Mw) measured by GPC of the obtained polyamide imide is preferably 5,000 to 100,000, more preferably 7,000 to 80,000.

[Polyorganosiloxane]

Polyorganosiloxane can be obtained, for example, by hydrolyzing and condensing a hydrolyzable silane compound. Examples of the silane compound used in the synthesis of polyorganosiloxane include tetramethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyl Alkoxysilane compounds such as diethoxysilane; 3-mercaptopropyltriethoxysilane, mercaptomethyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(3-cyclohexyl Amino)propyltrimethoxysilane and other nitrogen- and sulfur-containing alkoxysilane compounds; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3- Silanes containing epoxy groups such as glycidoxypropylmethyldimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane Compound; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyl Alkoxysilane compounds containing unsaturated bonds such as methyl diethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, etc.; trimethoxysilylpropylsuccinic anhydride, etc. As a hydrolyzable silane compound, one type of these may be used alone or two or more types may be used in combination. In addition, "(meth)acryloxy group" has a meaning including "acryloxy group" and "methacryloxy group".

The hydrolysis. The condensation reaction is performed by reacting one or more of the silane compounds described above with water, preferably in the presence of an appropriate catalyst and organic solvent. When the reaction is carried out, the usage ratio of water is preferably 1 mole to 30 moles relative to 1 mole of silane compound (total amount). Examples of the catalyst used include acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds, and the like. The amount of catalyst used should be appropriately set depending on the type of catalyst, temperature and other reaction conditions. For example, it is preferably 0.01 times molar to 3 times molar relative to the total amount of silane compounds. Examples of the organic solvent used include hydrocarbons, ketones, esters, ethers, alcohols, and the like. Among these, it is preferable to use water-insoluble or poorly water-soluble organic solvents. The usage ratio of the organic solvent is preferably 10 to 10,000 parts by mass relative to 100 parts by mass of the total silane compound used in the reaction.

The hydrolysis. The condensation reaction is preferably carried out by heating in an oil bath or the like. 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, if necessary, use a desiccant to dry the organic solvent layer separated from the reaction solution and then remove the solvent, thereby obtaining the product as Targeted polyorganosiloxanes. Furthermore, the synthesis method of polyorganosiloxane is not limited to the above-mentioned hydrolysis. The condensation reaction can be performed, for example, by a method of reacting a hydrolyzable silane compound in the presence of oxalic acid and alcohol.

The polyorganosiloxane may be a polyorganosiloxane having a photosensitive structure or a liquid crystal structure in a side chain. The method of synthesizing the polyorganosiloxane is not particularly limited, and examples include using an epoxy group-containing silane compound as at least a part of the raw material to synthesize a polyorganosiloxane having an epoxy group in the side chain (hereinafter also referred to as "Epoxy group-containing polyorganosiloxane"), and then a method of reacting an epoxy group-containing polyorganosiloxane with a carboxylic acid having a photosensitive structure or a liquid crystal structure, etc. This method is simple and preferable in that it can improve the introduction rate of the photosensitive structure and the liquid crystal structure. In addition, a polyorganosiloxane having a photosensitive structure or a liquid crystal structure in the side chain can also be synthesized by reaction of a monomer containing a hydrolyzable silane compound having a photosensitive structure or a liquid crystal structure. For polyorganosiloxane, the polystyrene-reduced weight average molecular weight (Mw) measured by GPC is preferably in the range of 100 to 50,000, more preferably in the range of 200 to 10,000.

[Poly(meth)acrylate]

Poly(meth)acrylate can be obtained by polymerizing a monomer containing a (meth)acrylic compound. Examples of (meth)acrylic compounds include: (meth)acrylic acid, unsaturated carboxylic acids such as α-ethyl acrylate, maleic acid, fumaric acid, and vinyl benzoate; (meth)acrylic acid alkyl groups Ester, cycloalkyl (meth)acrylate, benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, (meth)acrylate 2-hydroxyethyl acrylate, glycidyl (meth)acrylate, (meth)acrylate (basic) unsaturated carboxylic acid esters such as 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxybutyl (meth)acrylate, 4-hydroxybutyl glycidyl acrylate; maleic anhydride, etc. Unsaturated polycarboxylic acid anhydrides, etc. In addition, during polymerization, as the (meth)acrylic compound, one type may be used alone or two or more types may be used in combination.

In the synthesis of poly(meth)acrylate, monomers other than (meth)acrylic compounds may be used. Examples of the monomer include aromatic vinyl compounds such as styrene, methylstyrene, and divinylbenzene; and co-monomers such as 1,3-butadiene and 2-methyl-1,3-butadiene. Conjugated diene compounds; compounds containing maleimide groups such as N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. These monomers can be used individually by 1 type or in combination of 2 or more types.

The usage ratio of monomers other than the (meth)acrylic compound is preferably 50 mol% or less, more preferably 40 mol% or less, based on the total amount of monomers used in the polymerization, and still more preferably It is set to 30 mol% or less.

Poly(meth)acrylate can be obtained by polymerizing the monomer in the presence of a polymerization initiator. As the polymerization initiator used, for example, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2 '-Azobis(4-methoxy-2,4-dimethylvaleronitrile) and other azo compounds. The usage ratio of the polymerization initiator is preferably set to 0.01 to 30 parts by mass relative to 100 parts by mass of the total monomers used in the reaction.

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, and the like. Preferred examples are diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether acetate, and the like. opposite The reaction temperature is preferably set to 30°C to 120°C, and the reaction time is preferably set to 1 hour to 36 hours. The usage amount (a) of the organic solvent is preferably 0.1 mass % to 60 mass % of the total amount (b) of the monomers used in the reaction relative to the total amount (a + b) of the reaction solution.

When the poly(meth)acrylate is a photosensitive group-containing polymer or a liquid crystal polymer, the synthesis method is not particularly limited, and examples include: (I) By including a photosensitive group in the monomer A method of synthesizing by polymerizing a hydrolyzable silane compound with a natural structure or a liquid crystal structure; (II) using an epoxy group-containing compound in at least part of the raw materials to synthesize a polymer having an epoxy group in the side chain, and then Methods for reacting carboxylic acids with photosensitive structures or liquid crystal structures, etc. The polystyrene-reduced weight average molecular weight (Mw) measured by GPC on the poly(meth)acrylate is preferably 250 to 500,000, more preferably 500 to 100,000, and still more preferably 1,000 to 50,000.

"Solvent Composition"

The liquid crystal alignment agent of the present disclosure contains (A) solvent as at least part of the solvent component, and the (A) solvent is selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, and 3-methoxypropionate. At least one of the group consisting of oxybutyl acetate, the compound represented by the formula (1) and the compound represented by the formula (2).

[(A)Solvent]

In the formula (1) and formula (2), the alkyl groups of R ¹ , R ² and R ³ may be linear or branched. Examples include: methyl, ethyl, n-propyl, iso- Propyl, n-butyl, isobutyl, tert-butyl, etc. Among these, R ¹ preferably has 3 or 4 carbon atoms, more preferably n-propyl or n-butyl. R ² preferably has 1 or 2 carbon atoms. R ³ is preferably methyl. n in the formula (2) is 0 or 1, preferably 0.

Specific examples of the compound represented by the formula (1) include propylene glycol methyl ethyl ether, propylene glycol dimethyl ether, propylene glycol methyl n-propyl ether, propylene glycol methyl n-butyl ether, and the like. Preferred is propylene glycol methyl n-propyl ether or propylene glycol methyl n-butyl ether. In addition, as the compound represented by the said formula (1), one type may be used individually, or two or more types may be used in combination.

Specific examples of the compound represented by the formula (2) include, for example, cyclohexyl acetate, cyclohexyl propionate, cyclohexyl butyrate, and cyclohexyl valerate. Preferred is cyclohexyl acetate or cyclohexyl propionate. In addition, as the compound represented by the said formula (2), one type may be used individually, or two or more types may be used in combination.

[(B)Solvent]

In order to fully suppress the occurrence of coating unevenness even when the thickness of the liquid crystal alignment film is increased, the solvent component preferably has a boiling point of 200 at 1 atmosphere together with the solvent (A). (B) solvent that is above ℃ and different from (A) solvent.

(B) The solvent is preferably at least one selected from the group consisting of aprotic polar solvents and phenols, and is more preferably an aprotic polar solvent. Specifically, those selected from the group consisting of N-methyl-2-pyrrolidinone, N-ethyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, and γ-butyrolactone are particularly preferred. and at least one member from the group consisting of compounds represented by the following formula (3).

[Chemical 9]

(In formula (3), R ⁴ and R ⁵ are each independently a hydrogen atom, or a monovalent hydrocarbon group with 1 to 6 carbon atoms that may have an ether bond, and R ⁴ and R ⁵ may also be bonded to form a ring structure; R ⁶ is an alkyl group with 1 to 4 carbon atoms).

(Compound represented by formula (3))

In the formula (3), examples of monovalent hydrocarbon groups having 1 to 6 carbon atoms in R ⁴ and R ⁵ include chain hydrocarbon groups having 1 to 6 carbon atoms, alicyclic hydrocarbon groups having 3 to 6 carbon atoms, Aromatic hydrocarbon group having 5 or 6 carbon atoms, etc. Examples of the monovalent group having an ether bond include an alkoxyalkyl group having 2 to 6 carbon atoms. Examples of the ring in which R ⁴ and R ⁵ are bonded to each other and form together with the nitrogen atom to which R ⁴ and R ⁵ are bonded include nitrogen-containing heterocyclic rings such as a pyridine ring and a piperidine ring. These nitrogen-containing heterocycles may also be bonded with monovalent chain hydrocarbon groups such as methyl groups.

R ⁴ and R ⁵ are preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and still more preferably a hydrogen atom or a methyl group. The alkyl group having 1 to 4 carbon atoms in R ⁶ may be linear or branched. R ⁶ is preferably methyl or ethyl.

Specific examples of the compound represented by the formula (3) include: 3-butoxy-N,N-dimethyl propanamide (3-butoxy-N,N-dimethyl propanamide), 3- Methoxy-N,N-dimethylpropylamide, 3-hexyloxy-N,N-dimethylpropylamide, isopropoxy-N-isopropyl-propylamide (isopropoxy-N -isopropyl-propionamide), n-butoxy-N-isopropyl-propionamide, etc. The compound represented by the said formula (3) can be used individually by 1 type, or in combination of 2 or more types.

[(C)Solvent]

The solvent component may further include solvents other than (A) solvent and (B) solvent (hereinafter also referred to as "(C) solvent"). The solvent (C) is not particularly limited as long as it is a solvent different from the solvent (A) and the solvent (B) as long as the effect of the present disclosure is not hindered. (C) The solvent is preferably at least one selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons. Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, diacetone alcohol, etc.; ketones Examples of esters include: acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc.; examples of esters include: ethyl lactate, butyl lactate, methyl acetate, and ethyl acetate. , butyl acetate, methyl methoxypropionate, ethoxyethyl propionate, diethyl oxalate, diethyl malonate, isoamyl propionate, isoamyl isobutyrate, etc.; ethers Examples of the class include: diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether (butyl cellosu), ethylene glycol di Methyl ether, glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetic acid Ester, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), tetrahydrofuran, diisoamyl ether, etc.; Examples of halogenated hydrocarbons include: methylene chloride, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, etc.; Examples of hydrocarbons include hexane, heptane, octane, cyclopentane, cyclohexane, benzene, toluene, xylene, and the like. In addition, as the (C) solvent, one type can be used alone or two or more types can be used in combination.

(C) The solvent is preferably at least one selected from the group consisting of ketones, esters, ethers, and hydrocarbons in terms of preferably suppressing coating unevenness. . Among them, a low-boiling point solvent having a boiling point of 180° C. or less under 1 atmosphere is preferred in terms of being able to form a liquid crystal alignment film by low-temperature calcination and being applicable to film base materials. Specifically, it is preferably selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, cyclohexanone, and cyclopentane. and cyclopentanone.

Among the solvent components, the content ratio of the (A) solvent is 1 mass% to 70 mass% relative to the total amount of solvent components contained in the liquid crystal alignment agent. If it is less than 1 mass %, the effect of improving the coating properties of the liquid crystal alignment agent and reducing the residual solvent in the alignment film is small. On the other hand, if it is more than 70 mass %, the solubility of the polymer decreases and the alignment film The effect of inhibiting coating unevenness is small. The content ratio of (A) the solvent is preferably 3% by mass to 65% by mass, and more preferably 5% by mass to 60% by mass.

Relative to the total amount of solvent components contained in the liquid crystal alignment agent, the content ratio of the (B) solvent is 0 mass% to 40 mass%. If the content ratio of the (B) solvent is more than 40% by mass, the remaining amount of the solvent in the alignment film will be too large, which is undesirable in that backshift is likely to occur. Furthermore, the so-called "containing 0 mass % of (B) solvent" means that the liquid crystal alignment agent does not contain (B) solvent. In order to obtain a liquid crystal alignment film that is less likely to cause uneven coating even when the film is thick, it is preferable to use it together with the solvent (A). The liquid crystal alignment agent contains a relatively small amount of (B) solvent. Specifically, in order to further enhance the effect of suppressing uneven coating, it is preferable to set the content ratio of the solvent (B) to 0.1 mass with respect to the total amount of solvent components contained in the liquid crystal alignment agent. % to 40 mass %, more preferably 0.5 mass % to 40 mass %, further preferably 1 mass % to 35 mass %, particularly preferably 1 mass % to 20 mass %.

Relative to the total amount of solvent components contained in the liquid crystal alignment agent, the content ratio of the (C) solvent is preferably 5 mass% to 98 mass%, more preferably 10 mass% to 95 mass%, and still more preferably It is set to 20 mass% to 90 mass%. In order to sufficiently reduce the amount of residual solvent in the liquid crystal alignment film even when heating during film formation is performed at low temperature (for example, 150° C. or less), relative to the total amount of solvent components contained in the liquid crystal alignment agent, The content of the solvent (C) is preferably 40% by mass or more, more preferably 50% by mass or more. In this case, by using the polymer component as at least one selected from the group consisting of poly(meth)acrylate and polyorganosiloxane, the solubility of the polymer in the solvent can be improved, and thus It is preferable in that it can sufficiently suppress uneven coating. The liquid crystal alignment agent preferably has a solvent component that is a mixed solvent containing (A) solvent and (B) solvent, and particularly preferably a mixed solvent containing (A) solvent, (B) solvent, and (C) solvent.

<<Other ingredients>>

The liquid crystal alignment agent contains polymer components and solvent components, and may also contain other components if necessary. Examples of the other components include epoxy group-containing compounds, functional silane compounds, antioxidants, metal chelating compounds, curing catalysts, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. Agents, etc. other ingredients The compounding ratio can be appropriately selected according to each compound within the range that does not impair the effect of the present invention.

The solid component concentration in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) can be appropriately selected considering viscosity, volatility, etc., and is preferably 1 mass %~10% by mass. When the solid content concentration is less than 1% by mass, the film thickness of the coating film is too small and it is difficult to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by mass, the film thickness of the coating film is too large and it is difficult to obtain a good liquid crystal alignment film. In addition, the viscosity of the liquid crystal alignment agent increases and the coatability tends to decrease.

"Liquid Crystal Component"

The liquid crystal element of the present disclosure includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. Liquid crystal elements can be effectively used in various applications, such as clocks, portable game consoles, word processors, notebook personal computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital Various display devices such as cameras, mobile phones, smart phones, various monitors, LCD TVs, and information displays, or dimming films, phase difference films, etc. When used as a liquid crystal display element, the operation mode of the liquid crystal is not particularly limited. For example, it can be applied to twisted nematic (TN) type, super twisted nematic (Super Twisted Nematic, STN) type, and vertical alignment type. (Including vertical alignment-multi-domain vertical alignment (Vertical Alignment-Multi-domain Vertical Alignment, VA-MVA) type, vertical alignment-patterned vertical alignment (Vertical Alignment-Patterned Vertical Alignment, VA-PVA) type, etc.), coplanar cutting In-Plane Switching (IPS) type, Fringe Field Switching (FFS) type, Optically Compensated Bend (OCB) type and other modes.

A liquid crystal element can be manufactured by the following steps, for example. Here, a case of manufacturing a retardation film and a liquid crystal display element will be described as an example.

[Step 1: Formation of coating film]

First, the liquid crystal alignment agent is coated on the substrate, and then, if necessary, the coated surface is heated to form a coating film on the substrate. As the base material, a transparent base material can be preferably used. Specific examples include: glass substrates such as float glass and soda-lime glass; cellulose acetates such as cellulose (triacetyl cellulose (TAC), etc.); polyethylene terephthalate Diester, polyethylene naphthalate, polybutylene terephthalate, polyester, polyether ester, polyamide, polyimide, poly(meth)acrylate, polymethylmethacrylate , polycarbonate, cyclic polyolefin and other resin films, etc. In particular, the liquid crystal alignment agent of the present disclosure can be preferably used as a liquid crystal alignment agent for coating a resin film. Furthermore, in order to ensure good adhesion between the surface of the substrate and the liquid crystal alignment film, the substrate coated with the liquid crystal alignment agent may also be subjected to conventionally known pretreatments such as alkalinization treatment.

In the case of a liquid crystal display element, at least one of a pair of base materials is a base material in which a transparent conductive film is provided on one side of the base material. Examples of the transparent conductive film include NESA (registered trademark of PPG Corporation, USA) containing tin oxide (SnO ₂ ), indium tin oxide (In ₂ O ₃ -SnO ₂ ) containing Indium tin oxide, ITO) film, etc. When manufacturing a TN type, STN type or vertical alignment type liquid crystal display element, two substrates provided with patterned transparent conductive films are used. When manufacturing an IPS type or FFS type transverse electric field type liquid crystal display element, a substrate provided with an electrode including a transparent conductive film or a metal film patterned in a comb-tooth shape and a counter substrate provided with no electrode are used. As the metal film, for example, a film containing metal such as chromium can be used.

The liquid crystal alignment agent can be coated on the substrate using an appropriate coating method according to the type of the substrate. Specific examples include: roll coater method, rotator method, inkjet printing method, offset printing method, flexographic printing method, rod coater method, extrusion die method, direct gravure coating method, chamber Blade coater method, plate gravure coater method, dip coater method, MB coater method, etc. After coating the liquid crystal alignment agent, it is preferred to heat (bake) the coating surface. The heating temperature at this time is set according to the base material. When the base material is a resin film, it is preferably 150°C or lower, more preferably 40°C to 150°C, and even more preferably 80°C to 140°C. The heating time is preferably 0.1 minute to 15 minutes, more preferably 1 minute to 10 minutes. Heating of the coated surface can also be set as multiple heat treatments using pre-baking and post-baking. In this way, a coating film serving as a liquid crystal alignment film is formed on the base material.

The film thickness of the coating film formed on the substrate is preferably 1 nm to 1 μm, more preferably 5 nm to 0.5 μm. Here, when forming a liquid crystal alignment film on a base material, in order to improve the alignment of the liquid crystal alignment film to the liquid crystal or to improve the adhesion between the liquid crystal alignment film and the base material (especially the resin film base material), the liquid crystal alignment film may be The alignment film has a relatively thick film thickness (for example, 0.2 μm or 0.3 μm or more). On the other hand, if the thickness of the liquid crystal alignment film is increased, a solvent is likely to remain in the alignment film. Due to the influence of the remaining solvent, uneven coating may occur on the surface of the alignment film, or a liquid crystal alignment film may be formed. Membrane substrate lamination When the polymer component or residual solvent in the alignment film moves to the substrate side, back migration occurs. In this case, the alignment property of the liquid crystal of the obtained display element is likely to decrease, or the product yield is likely to decrease. As one of the means to reduce the residual solvent in the alignment film, it is considered to increase the heating temperature during film formation. However, if heating at high temperature is required, the application of the resin film as a base material is limited. In this regard, when the film thickness of the liquid crystal alignment film is made to be 0.3 μm or more, the liquid crystal alignment agent of the present disclosure can suppress the occurrence of the above-mentioned defects, and is preferred as a liquid crystal alignment agent used for resin films. .

[Step 2: Alignment Processing]

Next, a process (alignment process) for imparting liquid crystal alignment capability to the coating film formed in step 1 is performed. Thereby, the alignment ability of liquid crystal molecules is imparted to the coating film to become a liquid crystal alignment film. Examples of the alignment treatment include rubbing the coating film in a certain direction with a roller wound with a cloth containing fibers such as nylon, rayon, cotton, etc., thereby imparting the coating film with Rubbing treatment for liquid crystal alignment ability; photo-alignment treatment for irradiating the substrate surface coated with liquid crystal alignment agent with light to impart liquid crystal alignment ability to the coating film, etc. The photo-alignment treatment can be preferably applied in terms of suppressing display defects or yield reduction due to generation of dust, static electricity, etc., and in terms of uniformly imparting liquid crystal alignment ability to the organic thin film formed on the substrate. Furthermore, when manufacturing a vertical alignment type liquid crystal display element, the coating film formed in step 1 can be directly used as a liquid crystal alignment film, but the coating film can also be subjected to alignment treatment.

In the photo-alignment treatment, examples of the light to be irradiated include ultraviolet rays and visible rays containing light with a wavelength of 150 nm to 800 nm. Among these, the better one is Ultraviolet light containing light with a wavelength of 300nm~400nm. The irradiation light can be polarized light or non-polarized light. As the polarized light, it is preferable to use light containing linearly polarized light. When the light used is polarized light, the light can be irradiated from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When irradiating non-polarized light, it is necessary to irradiate from a direction inclined with respect to the substrate surface.

Examples of the light source used include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, and a mercury-xenon lamp (Hg-Xe lamp). Polarized light can be obtained by using the light source in combination with, for example, a filter, a diffraction grating, or the like. The amount of light irradiation is preferably 0.1mJ/cm ² ~1,000mJ/cm ² , more preferably 1mJ/cm ² ~500mJ/cm ² .

[Step 3-1: Formation of optically anisotropic film]

When producing a retardation film as a liquid crystal element, polymerizable liquid crystal is applied to the coating film (liquid crystal alignment film) after light irradiation and cured. Thereby, an optically anisotropic film as an organic thin film with an optical compensation function is formed on the surface of the liquid crystal alignment film. The polymerizable liquid crystal used here is a liquid crystal compound polymerized by at least any one of heating and light irradiation. Examples of the polymerizable group possessed by the polymerizable liquid crystal include (meth)acrylyl group, vinyl group, vinylphenyl group, allyl group, etc., and a (meth)acrylyl group is preferred.

As the polymerizable liquid crystal, conventionally known ones can be used. Specific examples include Non-Patent Document 1 ("UV Curable Liquid Crystal and Its Application", Liquid Crystal, Vol. 3, No. 1 (1999), Nos. 34 to 42 Nematic liquid crystals described on page)). In addition, cholesteric liquid crystals, discotic liquid crystals, and twisted nematic liquid crystals added with chiral agents can also be used. Jing et al. The polymerizable liquid crystal may be a mixture of a plurality of liquid crystal compounds, or may be a composition further containing a known polymerization initiator, an appropriate solvent, a polymerizable monomer, a surfactant, and the like. When the polymerizable liquid crystal is coated on the formed liquid crystal alignment film, an appropriate coating method such as a rod coater method, a roll coater method, a rotator method, a printing method, an inkjet method, etc. can be used.

Next, the coating film of polymerizable liquid crystal formed in the above manner is subjected to one or more treatments selected from heating and light irradiation, thereby curing the coating film to form a liquid crystal layer (optically anisotropic film). In terms of obtaining good alignment, it is preferable to overlap these processes. The heating temperature of the coating film can be appropriately selected depending on the type of polymerizable liquid crystal used. For example, when using RMS03-013C manufactured by Merck, it is preferable to heat at a temperature in the range of 40°C to 80°C. The preferred heating time is 0.5 minutes to 5 minutes. As the irradiation light for the coating film, non-polarized ultraviolet rays having a wavelength in the range of 200 nm to 500 nm can be preferably used. The amount of light irradiation is preferably 50mJ/cm ² to 10,000mJ/cm ² , and more preferably 100mJ/cm ² to 5,000mJ/cm ² . Furthermore, the coating film may be irradiated with polarized radiation only once in a predetermined polarization direction, or the coating film may be irradiated multiple times with radiation having different polarization directions (incident directions).

The thickness of the optically anisotropic film to be formed can be appropriately set depending on the desired optical properties. For example, when manufacturing a 1/2 wavelength plate under visible light with a wavelength of 540 nm as a retardation film, the phase difference of the optically anisotropic film selected as the retardation film is such that the thickness is 240 nm to 300 nm. If it is 1/4 For the wavelength plate, select a phase difference with a thickness of 120nm~150nm. The target phase difference can be obtained The thickness of the optically anisotropic film varies depending on the optical properties of the polymeric liquid crystal used. For example, when RMS03-013C manufactured by Merck is used, the thickness used to manufacture the 1/4-wavelength plate is in the range of 0.6 μm to 1.5 μm.

As a method for producing a retardation film, a roll-to-roll method may be used in order to enable industrial scale production easily. In this method, the following steps of processing a long resin film into a roll are performed continuously, and the film after these steps is recovered in the form of a roll again. A process of unwinding a resin film and forming a liquid crystal alignment film on the rolled-out film; a process of applying polymerizable liquid crystal on the liquid crystal alignment film and curing it; and a process of laminating a protective film if necessary. In addition, in the roll-to-roll method, when the step of forming the liquid crystal alignment film is transferred to the steps of applying polymerizable liquid crystal and curing, the resin film with the alignment film may be temporarily wound, and then the following steps may be performed. One step (coating and hardening of polymeric liquid crystal). At this time, if there is back migration of the residual solvent or polymer component in the liquid crystal alignment film to the substrate side, or even if there is no back migration, the removal of the solvent in the alignment film is insufficient, it will be difficult to process the polymerizable liquid crystal. When the film is rolled out after coating and curing treatment, film peeling in which the liquid crystal alignment film is peeled off from the base material is likely to occur. In this regard, the liquid crystal alignment agent of the present disclosure can reduce the amount of solvent remaining in the alignment film, thereby making back migration to the substrate less likely to occur, which is preferable in this regard.

[Step 3-2: Construction of liquid crystal cell]

When manufacturing a liquid crystal display element as a liquid crystal element, two substrates on which a liquid crystal alignment film is formed as described above are prepared, and liquid crystal is arranged between the two substrates facing each other to manufacture a liquid crystal cell. Specifically, it can be enumerated: sealing a A method of laminating the peripheral portion of the substrate, injecting liquid crystal into the cell gap divided by the substrate surface and the sealant, and then sealing the injection hole; applying the sealant to the liquid crystal of one of the substrates After adding liquid crystal dropwise to the peripheral portion on the alignment film side and at predetermined places on the surface of the liquid crystal alignment film, another substrate is bonded so that the liquid crystal alignment films face each other, and the liquid crystal is spread over the entire surface of the substrate. A method of subsequently hardening the sealant (liquid crystal drop filling (ODF) method), etc. Examples of the sealant include epoxy resin containing a hardener and alumina balls as spacers. Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferred. In addition, cholesteric liquid crystal, chiral agent, ferroelectric liquid crystal, etc. can also be added to the liquid crystal for use.

Next, if necessary, a polarizing plate is bonded to the outer surface of the liquid crystal cell, thereby obtaining a liquid crystal display element. Examples of the polarizing plate include those in which a polarizing film called an "H film" in which polyvinyl alcohol is stretched and oriented while absorbing iodine is sandwiched between a cellulose acetate protective film and the H film itself. polarizing plate.

[Example]

Hereinafter, the present invention will be further described in detail through examples, but the present invention is not limited in any way by these examples.

In the following examples, the weight average molecular weight Mw, number average molecular weight Mn and epoxy equivalent of the polymer, and the solution viscosity of the polymer solution were measured by the following methods. The necessary amounts of raw material compounds and polymers used in the following examples were determined by repeating the synthesis at the synthesis scale shown in the following synthesis examples as necessary. Save.

[Weight average molecular weight Mw and number average molecular weight Mn of the polymer]

Mw and Mn are polystyrene-converted values measured by GPC under the following conditions.

Pipe string: Tosoh Co., Ltd. manufacturing, TSKgelGRCXLII

Solvent: Tetrahydrofuran

Temperature: 40℃

Pressure: 68kgf/ ^cm2

[Epoxy equivalent]

The epoxy equivalent is measured by the hydrochloric acid-methyl ethyl ketone method described in Japanese Industrial Standards (JIS) C 2105.

[Solution viscosity of polymer solution]

The solution viscosity (mPa.s) of the polymer solution was measured using an E-type rotational viscometer at 25°C.

<Synthesis of polymers and compounds>

[Synthesis Example 1-1: Synthesis of epoxy group-containing polyorganosiloxane (EPS-1)]

Put 100g of propylene glycol monomethyl ether acetate, 100g of deionized water, 10.0g of triethylamine, and 2-(3,4-epoxy ring) into a reaction vessel equipped with a mixer, a thermometer, a dropping funnel, and a reflux cooling tube. Hexyl)ethyltrimethoxysilane 68.1g, methacryloxyoctyltrimethoxysilane 31.9g, pentaerythritol tetrakis[3-(3,5-tert-butyl-4-hydroxyphenyl)propionate ]0.074g, mix at room temperature. Then, the reaction was carried out by refluxing at 60° C. for 6 hours. After the reaction is completed, the organic layer is taken out, washed with a 0.2 mass% ammonium nitrate aqueous solution until the washed water becomes neutral, and then the solvent and water are distilled under reduced pressure to obtain a viscous transparent liquid. Epoxy-containing polyorganosiloxane (EPS-1). The epoxy group-containing polysiloxane was subjected to ¹ H-nuclear magnetic resonance (NMR) analysis, and it was confirmed that an oxanyl group-based polysiloxane can be obtained at a chemical offset (δ) of around 3.2 ppm. Wave peak, no side reactions of epoxy groups will be caused during the reaction. The weight average molecular weight Mw of the epoxy group-containing polyorganosiloxane is 2,200, and the epoxy equivalent weight is 186 g/mol.

[Synthesis Example 1-2: Synthesis of polyorganosiloxane (PS-1)]

A 100 mL three-necked flask was charged with 10.1 g of the epoxy group-containing polyorganosiloxane (EPS-1) obtained in Synthesis Example 1-1, 1.3 g of 4-(4-n-pentylcyclohexyl)benzoic acid, 17 g of propylene glycol monomethyl ether acetate and 0.3 g of tetrabutylammonium bromide were stirred at 90° C. for 12 hours. After the reaction was completed, the reaction solution was diluted with 0.75 equivalents (mass) of cyclohexane and washed with water five times. The solution was concentrated and diluted with propylene glycol monomethyl ether acetate (PGMEA). This operation was repeated twice to obtain a solution containing polyorganosiloxane (PS-1) having vertical alignment groups. The weight average molecular weight Mw of the polyorganosiloxane (PS-1) is 8,000.

[Synthesis Example 2-A: Synthesis of cinnamic acid derivative (mc-1)]

Add 19.2g of 1-bromo-4-cyclohexylbenzene, 0.18g of palladium acetate, 0.98g of tris(2-tolyl)phosphine, 32.4g of triylamine and dimethylacetyl into a 500mL three-necked flask equipped with a cooling tube. Add 135 mL of amine and mix. Next, 7 g of acrylic acid was added to the mixed solution using a syringe and stirred. Furthermore, the mixed solution was stirred while heating it at 120°C for 3 hours. After confirming the completion of the reaction using thin layer chromatography (TLC), The reaction solution was cooled to room temperature. After filtering and separating the precipitate, the filtrate was poured into 300 mL of 1N hydrochloric acid aqueous solution, and the precipitate was recovered. These precipitates were recrystallized from a 1:1 (mass ratio) solution of ethyl acetate and hexane, thereby obtaining 10.2 g of a cinnamic acid derivative represented by the following formula (mc-1).

[Synthesis Example 2-1: Synthesis of epoxy group-containing polyorganosiloxane (EPS-2)]

Put 100.0g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500g of methyl isobutyl ketone and trimethoxysilane into a reaction vessel equipped with a stirrer, thermometer, dropping funnel and reflux cooling tube. 10.0g of ethylamine, mixed at room temperature. Next, 100 g of deionized water was added dropwise from the dropping funnel over 30 minutes, mixed under reflux, and reacted at 80° C. for 6 hours. After the reaction is completed, the organic layer is taken out, washed with 0.2% by weight ammonium nitrate aqueous solution until the washed water becomes neutral, and then the solvent and water are distilled under reduced pressure to obtain a viscous transparent liquid. Epoxy-containing polyorganosiloxane (EPS-1).

The ¹ H-NMR analysis of the epoxy group-containing polysiloxane confirmed that an oxetanyl-based peak was obtained near the chemical shift (δ) = 3.2 ppm, and no cyclopropyl groups were caused during the reaction. Oxygen side reactions. The weight average molecular weight Mw of the epoxy group-containing polyorganosiloxane is 2,200, and the epoxy equivalent weight is 186 g/mol.

[Synthesis Example 2-2: Synthesis of photoalignment group-containing polyorganosiloxane (PS-2)]

A 100 mL three-necked flask was charged with 10.1 g of the epoxy group-containing polyorganosiloxane (EPS-2) obtained in Synthesis Example 2-1 and an acrylic acid group-containing carboxylic acid (Toagosei Co., Ltd., trade name " Aronix M-5300", ω-carboxypolycaprolactone acrylate (degree of polymerization n≒2)) 0.5 g, butyl acetate 20 g, cinnamic acid derivative (mc- 1) 1.5g, and 0.3g of tetrabutylammonium bromide, stir at 90°C for 12 hours. After the reaction is completed, the reaction solution is diluted with the same amount (mass) of propylene glycol monomethyl ether acetate, and washed with water three times. The solution was concentrated and diluted with propylene glycol monomethyl ether acetate. This operation was repeated twice, and finally a solution containing polyorganosiloxane (PS-2) having a photoalignment group was obtained. The weight average molecular weight Mw of the polyorganosiloxane (PS-2) is 9,000.

[Synthesis Example 3-1: Synthesis of epoxy group-containing polymethacrylate (AP-1)]

A flask equipped with a cooling tube and a stirrer was charged with 1 part by mass of 2,2'-azobis(isobutyronitrile) as a polymerization initiator and 180 parts by mass of propylene glycol monomethyl ether acetate as a solvent. 50 parts by mass of 3,4-epoxycyclohexylmethyl methacrylate and 50 parts by mass of (3-ethyloxetan-3-yl)methyl methacrylate were added to the flask. After nitrogen replacement, stirring was slowly started. The solution temperature was raised to 80° C. and maintained at this temperature for 5 hours, thereby obtaining a polymer solution containing 32.9 mass % of polymethacrylate having an epoxy group. The number average molecular weight Mn of the obtained epoxy group-containing polymethacrylate was 16,000.

[Synthesis Example 4-1: Synthesis of photoalignment group-containing polyamide (PAA-1)]

2.24 g (0.01 mol) of 2,3,5-tricarboxycyclopentyl acetic dianhydride as tetracarboxylic dianhydride and 2.54 g (0.01 mol) of a compound represented by the following formula (8) as a diamine Mol) was dissolved in 27.1 g of N-methyl-2-pyrrolidone (NMP) and reacted at 40°C for 3 hours to obtain a poly(P) containing 15% by mass. 31.8g of solution of hydroxyamide (PAA-1). The solution viscosity of the polyamide solution is 68mPa. s.

[Synthesis Example 5-A: Synthesis of methacrylate (9)]

4'-(6-bromohexyloxy)biphenyl-4-ol is synthesized by heating 4,4'-biphenyldiol and 1,6-dibromohexane under alkaline conditions. Lithium methacrylate is reacted with this product to obtain 2-(4'-hydroxybiphenyl-4-yloxy)hexyloxy methacrylate. Next, 4-methoxycinnamyl chloride was added under basic conditions to synthesize a compound (methacrylate (9)) represented by the following formula (9).

[Synthesis Example 5-B: Synthesis of methacrylate (10)]

4-(6-hydroxyhexyloxy)cinnamic acid is synthesized by heating 4-hydroxycinnamic acid and 1-hydroxy-6-hexanol under alkaline conditions. Methacrylate chloride and this product are reacted under basic conditions to obtain a compound (methacrylate (10)) represented by the following formula (10).

[Synthesis Example 5-C: Synthesis of Methacrylate (11)]

4-(6-hydroxyhexyloxy)iodophenol is synthesized by heating 4-iodophenol and 6-chloro-1-hexanol under alkaline conditions. After reacting 2-methyl-3-butyn-2-ol with the product, the product is heated under alkaline conditions to obtain 4-(6-hydroxyhexyloxy)ethynylbenzene (referred to as compound A). In addition, in another route, 4-methoxycinnamyl chloride and 4-iodophenol were reacted to synthesize 4-iodophenyl-3-(4-methoxyphenyl)acrylate (referred to as compound B ). Next, compound A and compound B are reacted under basic conditions to obtain a compound (methacrylate (11)) represented by the following formula (12).

[Synthesis Example 5-1: Synthesis of liquid crystalline polymethacrylate (LCP-1)]

Methacrylate (9) is dissolved in tetrahydrofuran, and azobisisobutyronitrile (AIBN) is added as a reaction initiator to polymerize, thereby obtaining a polymer solution. This polymer solution was added dropwise to diethyl ether (5000 ml), and the obtained precipitate was filtered. The precipitate was washed with diethyl ether and dried under reduced pressure in an oven at 40° C. to obtain liquid crystalline polymethacrylate (LCP-1) in powder form. The obtained polymethacrylate (LCP-1) had a number average molecular weight of 46,000 and a weight average of The average molecular weight is 119,600. This polymethacrylate (LCP-1) exhibits liquid crystallinity in the temperature range of 116°C to 315°C.

[Synthesis Example 5-2: Synthesis of liquid crystalline polymethacrylate (LCP-2)]

Polymethacrylate (LCP-2) was obtained by performing the same operation as Synthesis Example 5-1 except that methacrylate (10) was used instead of methacrylate (9). The obtained polymethacrylate (LCP-2) had a number average molecular weight of 46,000 and a weight average molecular weight of 119,600. This polymethacrylate (LCP-2) exhibits liquid crystallinity in the temperature range of 135°C to 187°C.

[Synthesis Example 5-3: Synthesis of liquid crystalline polymethacrylate (LCP-3)]

Polymethacrylate (LCP-3) was obtained by performing the same operation as Synthesis Example 5-1 except that methacrylate (11) was used instead of methacrylate (9). The obtained polymethacrylate (LCP-3) had a number average molecular weight of 46,000 and a weight average molecular weight of 119,600. This polymethacrylate (LCP-3) exhibits liquid crystallinity in the temperature range of 66°C to 320°C.

<Production and Evaluation of Liquid Crystal Alignment Film>

[Example 1]

1. Preparation of liquid crystal alignment agent

In a solution containing polymethacrylate (AP-1) as a polymer component, polymethacrylate (AP-1): polyorganosiloxane (PS-1) = 95:5 (mass ratio) Add polyorganosiloxane (PS-1), and then add 3- Methoxymethoxypropionate (MMP), propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monomethyl ether (PGME) and stir thoroughly to make a solvent composition of MMP: PGMEA: PGME=10:40:50 (mass ratio), a solution with a solid content concentration of 4.0 mass%. The solution was filtered using a filter with a pore size of 1 μm, thereby preparing a liquid crystal alignment agent (AL-1).

2. Evaluation of coating properties

As a sample for evaluation, the liquid crystal alignment agent (AL-1) prepared in the above 1. was coated on the PET film using a bar coater, and dried at 120° C. for 2 minutes to form a liquid crystal alignment film. The unevenness on the surface of the liquid crystal alignment film was observed under a microscope to evaluate the coating properties (uneven coating) of the liquid crystal alignment agent. As evaluation samples, two types of liquid crystal alignment films having a film thickness of 0.1 μm and 0.3 μm after drying were prepared. Furthermore, the thicker the film thickness, the easier it is for unevenness to occur on the surface of the liquid crystal alignment film. During the evaluation, the case where no unevenness was observed on the coating film surface was evaluated as "very good (◎)", the case where very little unevenness was observed on the coating film surface was evaluated as "good (○)", and the coating surface was evaluated as "very good (◎)". When a slight unevenness is observed, it is evaluated as "acceptable (△)", and when a lot of unevenness is observed on the coating film surface, it is evaluated as "poor (×)". As a result, in this Example, the evaluation of "very good" was made when the film thickness was 0.1 micrometer, and the evaluation was "good" when the film thickness was 0.3 micrometer.

3. Evaluation of back migration to the base material

As a sample for evaluation, the liquid crystal alignment agent (AL-1) prepared in the above 1. was coated on a PET film using a bar coater, and dried at 120° C. for 2 minutes to form a liquid crystal alignment film with a film thickness of 0.1 μm. Next, the PET film (B) was laminated on the liquid crystal alignment film surface (A), and the state where a load of 40 g/cm ² was applied was maintained at 80° C. for 30 minutes. The layer was then cooled to room temperature while maintaining the stacked state. Thereafter, the PET film (B) was peeled off from the liquid crystal alignment film surface (A), and it was visually observed whether the polymer components and residual solvent of the liquid crystal alignment film in the PET film (B) were back-migrated. Furthermore, when the polymer component and residual solvent of the liquid crystal alignment film back-migrated to the PET film (B), the back-migrated portion was observed in the form of white turbidity. During the evaluation, the case where no back shift was observed in the PET film (B) was evaluated as "very good (◎)", the case where very little back shift was observed was evaluated as "good (○)", and the case where a slight back shift was observed was evaluated as "very good (◎)". The case where the back shift was observed was evaluated as "acceptable (△)", and the case where back shift was observed overall was evaluated as "poor (×)". In addition, evaluation was performed in the same manner as described above, except that the load was changed from 40 g/cm ² to 80 g/cm ² . As a result, in this Example, both the case where the load was set to 40 g/cm ² and the case where the load was set to 80 g/cm ² were evaluated as "very good".

[Reference Example 1, Example 3 to Example 23 and Comparative Example 1 to Comparative Example 4]

The compounding composition of the liquid crystal alignment agent was changed as described in Table 1 and Table 2 below. Except for this, the same operation as in Example 1 was performed to prepare liquid crystal alignment agent (AL-2) ~ liquid crystal alignment agent (AL-23) respectively. ), liquid crystal alignment agent (BL-1) ~ liquid crystal alignment agent (BL-4). In addition, liquid crystal alignment agent (AL-2) ~ liquid crystal alignment agent (AL-23), liquid crystal alignment agent (BL-1) ~ liquid crystal alignment agent (BL-4) are used respectively to replace the liquid crystal alignment agent (AL-1). Other than that, various evaluations were performed in the same manner as in Example 1. These results are shown in Table 3 below.

[Table 1]

In Tables 1 and 2, the numerical values in parentheses in the polymer column represent the blending ratio (parts by mass) of each polymer relative to a total of 100 parts by mass of the polymer components used in the preparation of the liquid crystal alignment agent. The numerical value in the solvent column represents the compounding ratio (parts by mass) of each solvent relative to a total of 100 parts by mass of the solvent components used in the preparation of the liquid crystal alignment agent. "-" means that the compound was not used. The abbreviations of the compounds are as follows.

<Solvent>

MMP: methyl 3-methoxypropionate

EEP: ethyl 3-ethoxypropionate

MBA: 3-methoxybutylacetate

PGMPE: propylene glycol methyl propyl ether

PGMBE: propylene glycol methyl butyl ether

CA: cyclohexyl acetate

CP: cyclohexyl propionate

NMP: N-methyl-2-pyrrolidone

GBL: gamma-butyrolactone

NEP: N-ethyl-2-pyrrolidinone

DMI: 1,3-dimethyl-2-imidazolidinone

PGMEA: propylene glycol monomethyl ether acetate

PGME: propylene glycol monomethyl ether

DEDG: Diethylene glycol diethyl ether

BC: Dinkycellosu

[table 3]

As can be seen from Table 3, the coating properties and back transfer properties of Example 1, Reference Example 1, and Examples 3 to 23 using the liquid crystal alignment agent containing (A) solvent were "very good" and "good" or "yes" evaluation to achieve a balance between the two. In addition, by using the solvent (B) in combination, the coatability when the film thickness of the liquid crystal alignment film is set to 0.3 μm is further improved. On the other hand, comparative examples that do not contain the solvent (A) In Comparative Examples 1 to 3, when the film thickness was 0.3 μm, the coating properties were evaluated as "poor". In addition, in Comparative Examples 3 and 4, the back migration properties were evaluated as "poor".

Claims (10)

A liquid crystal alignment agent, which contains a polymer component and a solvent component. The polymer component contains a P polymer, and the P polymer is selected from the group consisting of poly(meth)acrylate and polyorganosiloxane. At least one of the group, the solvent component contains 5 mass % to 60 mass % of the following (A) solvent with respect to the total amount of the solvent component, and the solvent component contains 0 mass% to 40 mass% of the following (B) solvent, (A) solvent is selected from the group consisting of 3-methoxypropionic acid methyl ester, 3-methoxybutyl acetate, and the following formula (1) At least one compound in the group consisting of the compound represented by the following formula (2) and the compound represented by the following formula (2); (B) The solvent is a compound that has a boiling point of 200°C or higher at 1 atmosphere and is different from the (A) solvent ,

(In formula (1), R ¹ is an alkyl group having 1 to 4 carbon atoms)

(In formula (2), R ² is an alkyl group having 1 to 4 carbon atoms, and R ³ is an alkyl group having 1 to 4 carbon atoms; n is 0 or 1). The liquid crystal alignment agent described in item 1 of the patent application, wherein the (B) solvent is selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3- At least one of the group consisting of dimethyl-2-imidazolidinone, γ-butyrolactone and the compound represented by the following formula (3),

(In formula (3), R ⁴ and R ⁵ are each independently a hydrogen atom, or a monovalent hydrocarbon group with 1 to 6 carbon atoms that may have an ether bond, and R ⁴ and R ⁵ may also be bonded to form a ring structure; R ⁶ is an alkyl group with 1 to 4 carbon atoms). The liquid crystal alignment agent as described in item 1 or 2 of the patent application, wherein the (P) polymer has a structure selected from the group consisting of cinnamic acid structure, azobenzene structure, chalcone structure, stilbene structure, and diphenyl structure. At least one photosensitive structure in the group consisting of an acetylene structure, a (meth)acrylyl group, a vinyl group, and a phenyl benzoate structure. The liquid crystal alignment agent described in Item 1 or Item 2 of the patent application, wherein the (P) polymer has a group structure represented by the following formula (5) in the side chain,

(In formula (5), Ar ¹ and Ar ² are each independently a substituted or unsubstituted phenyl group or a substituted or unsubstituted cyclohexylene group, and X ²¹ is a single bond, -CO-, - COO-, -C=C-, -C≡C-, -N=N- or -CONR ⁴¹ -(R ⁴¹ is a hydrogen atom or a monovalent organic group); r is an integer from 1 to 3; when r is 2 or 3, Ar ² and X ²¹ independently have the above definitions; * indicates a bond). The liquid crystal alignment agent described in Item 1 or Item 2 of the patent application is used for coating on a material selected from the group consisting of chelated cellulose, polyethylene terephthalate, polyethylene naphthalate, and polyparaethylene terephthalate. Butylene phthalate, polyethylene, polyetherether, polyamide, polyimide, poly(meth)acrylate, polymethylmethacrylate, polycarbonate and cyclic polyethylene At least one resin substrate from the group consisting of olefins. For example, the liquid crystal alignment agent described in item 1 or 2 of the patent application further contains (C) solvent, and the (C) solvent is selected from alcohols, ketones, esters, ethers, and halogenated hydrocarbons. and at least one of the group consisting of hydrocarbons, and is different from the solvent (A). The liquid crystal alignment agent described in Item 6 of the patent application, wherein the content ratio of the (C) solvent is more than 20 mass % relative to the total amount of the solvent component. A liquid crystal alignment film formed by using the liquid crystal alignment agent described in any one of items 1 to 7 of the patent application scope. A liquid crystal element, which includes the liquid crystal alignment film described in item 8 of the patent application. A method for manufacturing a liquid crystal alignment film, which involves applying the liquid crystal alignment agent as described in any one of items 1 to 7 of the patent application scope on a substrate, and heating the liquid crystal alignment film at a temperature below 150°C to form a coating film.