KR20210157773A - Liquid crystal alignment, method of preparing liquid crystal alignment film, and liquid crystal alignment film, liquid crystal display using the same - Google Patents

Abstract

The present invention relates to a liquid crystal aligning agent including a copolymer having two kinds of polyamic acid repeating units having different diamine-derived functional group structures, a method for manufacturing a liquid crystal aligning film using the same, a liquid crystal aligning film using the same, and a liquid crystal display device. The present invention can realize excellent electrical properties.

Description

Liquid crystal aligning agent, manufacturing method of liquid crystal aligning film using same, liquid crystal aligning film and liquid crystal display device

The present invention relates to a liquid crystal aligning agent capable of ensuring a high imidization rate in an alignment film manufacturing process and implementing excellent electrical properties, a method for manufacturing a liquid crystal alignment film using the same, a liquid crystal alignment film and a liquid crystal display device.

In the liquid crystal display device, the liquid crystal alignment layer is responsible for aligning the liquid crystal in a predetermined direction. Specifically, the liquid crystal alignment layer serves as a director for the arrangement of liquid crystal molecules, so that when the liquid crystal moves by an electric field to form an image, an appropriate direction is obtained. In order to obtain uniform brightness and high contrast ratio in the liquid crystal display device, it is essential to uniformly align the liquid crystal.

As one of the methods for aligning liquid crystals in the prior art, a rubbing method in which a polymer film such as polyimide is applied to a substrate such as glass and rubbing the surface in a predetermined direction using fibers such as nylon or polyester was used. However, in the rubbing method, fine dust or electrical discharge (ESD) may be generated when the fibers and the polymer film are rubbed, which may cause serious problems in manufacturing the liquid crystal panel.

In order to solve the problem of the rubbing method, recently, a photo-alignment method in which anisotropy (anisotropy) is induced in a polymer film by light irradiation rather than friction, and aligning liquid crystals using this is being studied.

Various materials have been introduced as materials that can be used for the photo-alignment method, and among them, polyimide is mainly used for good overall performance of the liquid crystal alignment layer. Accordingly, after coating in the form of a precursor such as polyamic acid or polyamic acid ester, the polyimide is formed through a heat treatment process at a temperature of 200 ° C. to 230 ° C., and the orientation treatment is performed by irradiation with light.

However, in order to obtain sufficient liquid crystal alignment by irradiating the polyimide film with light, a lot of energy is required, which makes it difficult to secure actual productivity, and an additional heat treatment process is also required to secure alignment stability after light irradiation, and the panel Due to the enlargement of the panel, abrasion of the column space (CS) occurred during the manufacturing process, and haze was generated on the surface of the liquid crystal alignment layer, which caused a defect in the Milky Way.

In addition, for high-quality driving of the liquid crystal display device, a high voltage holding ratio (VHR) must be exhibited, and polyimide alone has a limitation in representing this. In particular, as the demand for low-power displays increases in recent years, liquid crystal aligning agents may affect not only the basic characteristics of liquid crystal alignment, but also electrical characteristics such as afterimages and voltage retention caused by DC/AC voltage. was discovered, and there is a growing need for development of a liquid crystal alignment material that can simultaneously implement excellent liquid crystal alignment and electrical properties.

An object of the present invention is to provide a liquid crystal aligning agent capable of ensuring a high imidization rate in an alignment film manufacturing process and implementing excellent electrical properties.

In addition, the present invention is to provide a method for manufacturing a liquid crystal aligning film using the liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal display device.

In order to solve the above problems, in the present specification, a repeating unit represented by the following Chemical Formula 1; and a repeating unit represented by the following Chemical Formula 2; provides a liquid crystal aligning agent including a copolymer.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, X ₁ and X ₂ are the same as or different from each other, each independently a tetravalent functional group, and Y ₁ is a divalent functional group including a cyclic imide group and an arylene group substituted with at least one hetero atom, and , Y ₂ is a divalent functional group including a cyclic imide group and an unsubstituted arylene group.

In the present specification, further, forming a coating film by applying the liquid crystal aligning agent to the substrate; drying the coating film; Orienting the dried coating film by irradiating light or rubbing treatment; and curing the alignment-treated coating film by heat treatment.

In the present specification, there is also provided a liquid crystal aligning film including an alignment cured product of the liquid crystal aligning agent.

In the present specification, a liquid crystal display device including the liquid crystal alignment layer is also provided.

Hereinafter, a liquid crystal aligning agent according to a specific embodiment of the present invention, a method for manufacturing a liquid crystal aligning film using the same, a liquid crystal aligning film and a liquid crystal display device will be described in more detail.

Unless explicitly stated herein, terminology is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention.

As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite.

As used herein, the meaning of 'comprising' specifies a particular characteristic, region, integer, step, operation, element and/or component, and other specific characteristic, region, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of

And, in the present specification, terms including ordinal numbers such as 'first' and 'second' are used for the purpose of distinguishing one component from other components, and are not limited by the ordinal number. For example, within the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

In the present specification, examples of the substituent are described below, but is not limited thereto.

In the present specification, the term "substituted" means that other functional groups are bonded instead of hydrogen atoms in the compound, and the position to be substituted is not limited as long as the position at which the hydrogen atom is substituted, that is, the position where the substituent is substituted, is not limited, and when two or more substituted , two or more substituents may be the same as or different from each other.

As used herein, the term "substituted or unsubstituted" refers to deuterium; halogen group; cyano group; nitro group; hydroxyl group; carbonyl group; ester group; imid; amide group; primary amino group; carboxyl group; sulfonic acid group; sulfonamide group; a phosphine oxide group; alkoxy group; aryloxy group; alkyl thiooxy group; arylthioxy group; an alkyl sulfoxy group; arylsulfoxy group; silyl group; boron group; an alkyl group; cycloalkyl group; alkenyl group; aryl group; aralkyl group; aralkenyl group; an alkylaryl group; alkoxysilylalkyl group; an arylphosphine group; Or N, O, and S atom means that it is substituted or unsubstituted with one or more substituents selected from the group consisting of a heterocyclic group containing one or more, or substituted or unsubstituted, two or more of the above-exemplified substituents are linked. . For example, "a substituent in which two or more substituents are connected" may be a biphenyl group. That is, the biphenyl group may be an aryl group or may be interpreted as a substituent in which two phenyl groups are connected.

, 또는

는 다른 치환기에 연결되는 결합을 의미하고, 직접결합은 L 로 표시되는 부분에 별도의 원자가 존재하지 않은 경우를 의미한다. In this specification,

, or

denotes a bond connected to another substituent, and a direct bond denotes a case in which a separate atom does not exist in the portion represented by L .

In the present specification, aromatic is a characteristic that satisfies the Huckels Rule, and a case in which all of the following three conditions are satisfied according to the Huckels Rule may be defined as aromatic.

1) There must be 4n+2 electrons that are completely conjugated by empty p-orbitals, unsaturated bonds, unpaired electron pairs, etc.

2) 4n+2 electrons must form a planar isomer and form a ring structure.

3) All atoms of the ring must be able to participate in conjugation.

In the present specification, the alkyl group is a monovalent functional group derived from an alkane, and may be straight-chain or branched, and the number of carbon atoms in the straight-chain alkyl group is not particularly limited, but is preferably 1 to 20. In addition, the number of carbon atoms of the branched chain alkyl group is 3 to 20. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n -pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl , n-heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl- propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, 2,6-dimethylheptan-4-yl, and the like. The alkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, the haloalkyl group refers to a functional group in which a halogen group is substituted with the aforementioned alkyl group, and examples of the halogen group include fluorine, chlorine, bromine or iodine. The haloalkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, the cycloalkyl group is a monovalent functional group derived from cycloalkane, and may be monocyclic or polycyclic, and is not particularly limited, but has 3 to 20 carbon atoms. According to another exemplary embodiment, the carbon number of the cycloalkyl group is 3 to 10. Specifically, cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3, 4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, bicyclo[2,2,1]heptyl, and the like, but are not limited thereto. The cycloalkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, the aryl group is a monovalent functional group derived from arene, and is not particularly limited, but preferably has 6 to 20 carbon atoms, and may be a monocyclic aryl group or a polycyclic aryl group. The aryl group may be a monocyclic aryl group, such as a phenyl group, a biphenyl group, or a terphenyl group, but is not limited thereto. The polycyclic aryl group may be a naphthyl group, an anthracenyl group, a phenanthryl group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, and the like, but is not limited thereto. The aryl group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, the alkylene group is a divalent functional group derived from an alkane, and the description of the alkyl group described above may be applied, except that these are divalent functional groups. For example, as a linear or branched type, it may be a methylene group, an ethylene group, a propylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, a pentylene group, a hexylene group, and the like. The alkylene group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, the arylene group is a divalent functional group derived from arene, and the description of the aryl group described above may be applied, except that these are divalent functional groups. For example, it may be a phenylene group, a biphenylene group, a terphenylene group, a naphthalene group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a perylene group, a tetracenyl group, an anthracenyl group, and the like. The arylene group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, the heteroaryl group includes one or more atoms other than carbon and one hetero atom, and specifically, the hetero atom may include one or more atoms selected from the group consisting of O, N, Se and S, etc. . The number of carbon atoms is not particularly limited, but preferably has 4 to 20 carbon atoms, and the heteroaryl group may be monocyclic or polycyclic. Examples of the heterocyclic group include a thiophene group, a furanyl group, a pyrrole group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl group, a pyridyl group, a bipyridyl group, a pyrimidyl group, a triazinyl group, a triazinyl group Jolyl group, acridyl group, pyridazinyl group, pyrazinyl group, quinolinyl group, quinazolinyl group, quinoxalinyl group, phthalazinyl group, pyrido pyrimidyl group, pyrido pyrazinyl group, pyrazino pyrazinyl group , isoquinolinyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzimidazolyl group, benzothiazolyl group, benzocarbazolyl group, benzothiophene group, dibenzothiophene group, benzofuranyl group, pe Nonthrolyl group (phenanthroline), thiazolyl group, isoxazolyl group, oxadiazolyl group, thiadiazolyl group, benzothiazolyl group, phenothiazinyl group, aziridyl group, azaindolyl group, isoindolyl group, inda Zolyl group, purine group, pteridine group, beta-carbolyl group, naphthyridine group, ter-pyridyl group, phenazinyl group, imidazopyridyl group, pyropyridyl group, azepine group , a pyrazolyl group and a dibenzofuranyl group, but is not limited thereto. The heteroaryl group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, the cycloalkylene group is a divalent functional group derived from cycloalkene, and the description of the cycloalkyl group described above may be applied, except that it is a divalent functional group. The cycloalkylene group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, in the present specification, the hetero arylene group has 2 to 20, or 2 to 10, or 6 to 20 carbon atoms, and an atom selected from the group consisting of O, N, Se and S as a hetero atom is 1 As the arylene group contained above, the description of the above-mentioned heteroaryl group may be applied, except that it is a divalent functional group. The hetero arylene group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, a multivalent functional group is a residue in a form in which a plurality of hydrogen atoms bonded to an arbitrary compound are removed, and may include, for example, a divalent functional group, a trivalent functional group, and a tetravalent functional group. For example, the tetravalent functional group derived from cyclobutane refers to a residue in which 4 hydrogen atoms bonded to cyclobutane are removed.

In the present specification, a direct bond or a single bond means that no atom or group of atoms is present at the corresponding position, and thus is connected by a bonding line. Specifically, it refers to a case in which a separate atom does not exist in the portion represented by _{L 1} and L _{2 in the formula.}

Hereinafter, the present invention will be described in more detail.

1. Liquid crystal aligning agent

According to one embodiment of the invention, a repeating unit represented by the following formula (1); and a repeating unit represented by Formula 2 below may be provided.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, X ₁ and X ₂ are the same as or different from each other, each independently a tetravalent functional group, and Y ₁ is a divalent functional group including a cyclic imide group and an arylene group substituted with at least one hetero atom, and , Y ₂ is a divalent functional group including a cyclic imide group and an unsubstituted arylene group.

The present inventors, as in the liquid crystal aligning agent of the embodiment, contain the polyamic acid repeating unit represented by Formula 1 and the polyamic acid repeating unit represented by Formula 2 together, so that the polyamic acid repeating unit represented by Formula 1 is Due to the imidation catalytic action by the arylene group structure substituted with at least one hetero atom included, it was confirmed through experiments that the imidization rate and electrical properties of the liquid crystal aligning agent could be improved, and the invention was completed.

Conventionally, in order to induce imidization catalysis, a method of adding a separate additive such as a monoamine compound into the liquid crystal aligning agent has been used. Due to the large increase in the viscosity of the liquid crystal aligning agent, it is difficult to smoothly coat the liquid crystal aligning film in the subsequent synthesis, and there is a limit in that the reproducibility and stability are reduced due to a rapid change in the internal composition during long-term storage of the liquid crystal aligning agent.

Therefore, in the present invention, by embedding a structure capable of imidization catalytic action in the polyamic acid repeating unit included in the copolymer, it was possible to overcome the technical limitations of the existing imidization catalyst additive input.

In addition, when synthesizing the liquid crystal aligning film by the cyclic imide group commonly contained in the polyamic acid repeating unit represented by Formula 1 and the polyamic acid repeating unit represented by Formula 2, the anisotropy is achieved by irradiating light directly without a high-temperature heat treatment process. Since the liquid crystal aligning film can be completed by generating the liquid crystal aligning film and then performing heat treatment, not only can the light irradiation energy be greatly reduced, but also the alignment and stability are excellent even with a simple process including one heat treatment process, and the voltage It is possible to manufacture a liquid crystal aligning film excellent also in electrical properties such as maintenance ratio.

Specifically, the liquid crystal aligning agent may include a repeating unit represented by Formula 1; and a repeating unit represented by Formula 2 above. The copolymer may be a copolymer for a liquid crystal aligning agent used as a main component of the liquid crystal aligning agent.

The form of the copolymer is not particularly limited, and for example, various copolymer forms of random copolymers, block copolymers, and graft copolymers may be applied without limitation.

The copolymer may include a repeating unit represented by Formula 1; and two different polyamic acid repeating units of the repeating unit represented by Formula 2 above. The copolymer may be thermally imidized under high temperature heat treatment conditions by a method for producing a liquid crystal alignment layer to be described later, and the polyamic acid repeating unit may be converted into polyimide. Accordingly, the copolymer corresponds to a kind of polyimide precursor, and, if necessary, a polyamic acid ester repeating unit that is an esterification product of the repeating unit represented by Formula 1 or an esterification product of the repeating unit represented by Formula 2 may further include.

The repeating unit represented by Formula 1 is a repeating unit included in a polyamic acid polymer that is a reaction product of a diamine compound and a tetracarboxylic dianhydride compound, and is substituted with at least one hetero atom included in the polyamic acid repeating unit represented by Formula 1 Due to the imidization catalytic action by the arylene group structure, the imidization rate and electrical properties of the liquid crystal aligning agent may be improved.

In the repeating unit represented by Formula 1, X ₁ is a functional group derived from a tetracarboxylic dianhydride compound used for synthesizing polyamic acid. Specifically, X ₁ may be a tetravalent functional group, and more specifically, may be any one tetravalent functional group selected from functional groups represented by Formula 6 below.

[Formula 6]

상기 화학식6에서, R₁ 내지 R₆은 서로 동일하거나 상이하며, 각각 독립적으로 수소 또는 탄소수 1 내지 6의 알킬기 중 하나이고, L₁는 단일결합, -O-, -CO-, -COO-, -S-, -SO-, -SO₂-, -CR₇R₈-, -(CH₂)_Z-, -O(CH₂)_ZO-, -COO(CH₂)_ZOCO-, -CONH-, 또는 페닐렌 중에서 선택된 어느 하나이며, 상기 L₁에서 R₇ 및 R₈는 서로 동일하거나 상이하며, 각각 독립적으로 수소, 탄소수 1 내지 10의 알킬기 또는 탄소수 1 내지 10의 할로알킬기 중 하나이고, 상기 L₁에서 z는 1 내지 10의 정수이다.

In Formula 6, R ₁ to R ₆ are the same as or different from each other, and each independently represents one of hydrogen or an alkyl group having 1 to 6 carbon atoms, and L ₁ is a single bond, -O-, -CO-, -COO-, -S-, -SO-, -SO ₂ -, -CR ₇ R ₈ -, -(CH ₂ ) _Z -, -O(CH ₂ ) _Z O-, -COO(CH ₂ ) _Z OCO-, -CONH -, or any one selected from phenylene, wherein in L ₁ R ₇ and R ₈ are the same or different from each other, and each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a haloalkyl group having 1 to 10 carbon atoms, In L ₁ , z is an integer of 1 to 10.

More specifically, X ₁ is 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (1,3-Dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, DMCBDA) derived from A functional group of the following Chemical Formula 6-1, a functional group of the following Chemical Formula 6-2 derived from cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA); Or it may be one of the functional groups of the following formula 6-3 derived from pyromellitic dianhydride (PMDA).

[Formula 6-1]

[Formula 6-2]

[Formula 6-3]

In the repeating unit represented by Formula 1, Y ₁ is a functional group derived from a diamine compound used for synthesizing polyamic acid. Specifically, Y ₁ may be a divalent functional group including a cyclic imide group and an arylene group substituted with at least one hetero atom. That is, the diamine used for synthesizing the repeating unit represented by Chemical Formula 1 may have a chemical structure _{of H 2} NY ₁ -NH _{2 .}

The imide group is _a functional group represented by R a -CO-NR _b -CO-R _{c , wherein R a} , R _b , R _c are the same as or different from each other, and each independently hydrogen, any monovalent organic group, Or it may be an organic group linked to each other. The cyclic imide group _{means an organic group in which R a} and R _c are linked to each other.

When synthesizing the liquid crystal aligning film by the cyclic imide group, since the liquid crystal aligning film can be completed by directly irradiating light without a high temperature heat treatment process to generate anisotropy, and then performing heat treatment to complete the liquid crystal aligning film, the light irradiation energy can be greatly reduced In addition, it is possible to manufacture a liquid crystal aligning film having excellent alignment and stability, as well as electrical characteristics such as voltage maintenance retention rate, even with a simple process including one heat treatment process.

On the other hand, due to the imidation catalytic action by the arylene group structure substituted with at least one hetero atom, the imidization rate and electrical properties of the liquid crystal aligning agent may be improved.

In the arylene group substituted with at least one hetero atom, the arylene group is a divalent functional group derived from arene, but is not particularly limited, but preferably has 6 to 20 carbon atoms, and a monocyclic arylene group or a polycyclic arylene group may include For example, it may be a phenylene group, a biphenylene group, a terphenylene group, a naphthalene group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a perylene group, a tetracenyl group, an anthracenyl group, and the like.

In addition, the hetero atom may include one or more atoms selected from the group consisting of O, N, Se and S. That is, the hetero atom may include one of each of O, N, Se, and S, or a mixture of two or more thereof, and specifically nitrogen (N) may be used as the hetero atom. The hetero atom may be substituted with at least one, or one, arylene group.

Specifically, the _{divalent functional group including a cyclic imide group of Y 1} and an arylene group substituted with at least one hetero atom may be a divalent functional group represented by Formula 3 below.

[Formula 3]

In Formula 3, A ₁ and A ₂ are the same as or different from each other, each independently represent phenylene in which at least one nitrogen atom is substituted, and T ₁ is a tetravalent functional group. In Formula 3, the description of the tetravalent functional group of _{T 1} may include all the contents described above for _{X 1 of the repeating unit represented by Formula 1 as it is.}

In Formula 3, the _{phenylene in which at least one nitrogen atom of A 1} and A ₂ is substituted may be any one of a functional group represented by Formula 4-1 or a functional group represented by Formula 4-2.

[Formula 4-1]

[Formula 4-2]

More specifically, the divalent functional group represented by Chemical Formula 3 may be any one of a functional group represented by Chemical Formula 3-1 or a functional group represented by Chemical Formula 3-2.

[Formula 3-1]

[Formula 3-2]

In Formulas 3-1 and 3-2, T ₁ is a tetravalent functional group. In Formulas 3-1 and 3-2, the description of the tetravalent functional group of _{T 1} may include all the contents described above for _{X 1 of the repeating unit represented by Formula 1 as it is.}

In a more specific example, examples of the functional group represented by Chemical Formula 3-1 include functional groups represented by the following Chemical Formulas 3-3 to 3-5.

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

In addition, examples of the functional group represented by Chemical Formula 3-2 include functional groups represented by the following Chemical Formulas 3-6 to 3-8.

[Formula 3-6]

[Formula 3-7]

[Formula 3-8]

On the other hand, the repeating unit represented by Formula 2 is a repeating unit included in a polyamic acid polymer that is a reaction product of a diamine compound and a tetracarboxylic dianhydride compound, and is a cyclic imide group included in the polyamic acid repeating unit represented by Formula 2 above. When synthesizing the liquid crystal aligning film by this, since the liquid crystal aligning film can be completed by directly irradiating light without a high temperature heat treatment process to generate anisotropy, and then performing heat treatment to complete the liquid crystal aligning film, the light irradiation energy can be greatly reduced and one heat treatment A liquid crystal alignment film having excellent alignment and stability, as well as electrical properties such as voltage maintenance retention rate, can be manufactured through a simple process including a process.

In the repeating unit represented by Formula 2, X ₂ is a functional group derived from a tetracarboxylic dianhydride compound used for synthesizing polyamic acid. Specifically, X ₂ may be a tetravalent functional group, and more specifically, may be any one tetravalent functional group selected from functional groups represented by Formula 6 below.

[Formula 6]

상기 화학식6에서, R₁ 내지 R₆은 서로 동일하거나 상이하며, 각각 독립적으로 수소 또는 탄소수 1 내지 6의 알킬기 중 하나이고, L₁는 단일결합, -O-, -CO-, -COO-, -S-, -SO-, -SO₂-, -CR₇R₈-, -(CH₂)_Z-, -O(CH₂)_ZO-, -COO(CH₂)_ZOCO-, -CONH-, 또는 페닐렌 중에서 선택된 어느 하나이며, 상기 L₁에서 R₇ 및 R₈는 서로 동일하거나 상이하며, 각각 독립적으로 수소, 탄소수 1 내지 10의 알킬기 또는 탄소수 1 내지 10의 할로알킬기 중 하나이고, 상기 L₁에서 z는 1 내지 10의 정수이다.

In Formula 6, R ₁ to R ₆ are the same as or different from each other, and each independently represents one of hydrogen or an alkyl group having 1 to 6 carbon atoms, and L ₁ is a single bond, -O-, -CO-, -COO-, -S-, -SO-, -SO ₂ -, -CR ₇ R ₈ -, -(CH ₂ ) _Z -, -O(CH ₂ ) _Z O-, -COO(CH ₂ ) _Z OCO-, -CONH -, or any one selected from phenylene, wherein in L ₁ R ₇ and R ₈ are the same or different from each other, and each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a haloalkyl group having 1 to 10 carbon atoms, In L ₁ , z is an integer of 1 to 10.

More specifically, X ₂ is derived from 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride (1,3-Dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, DMCBDA). A functional group of the following Chemical Formula 6-1, a functional group of the following Chemical Formula 6-2 derived from cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA); Or it may be one of the functional groups of the following formula 6-3 derived from pyromellitic dianhydride (PMDA).

[Formula 6-1]

[Formula 6-2]

[Formula 6-3]

In the repeating unit represented by Formula 2, Y ₂ is a functional group derived from a diamine compound used for synthesizing polyamic acid. Specifically, Y ₂ may be a divalent functional group including a cyclic imide group and a divalent functional group including an unsubstituted arylene group. That is, the diamine used for synthesizing the repeating unit represented by Chemical Formula 2 may have a chemical structure _{of H 2} NY ₂ —NH _{2 .}

The imide group is _a functional group represented by R a -CO-NR _b -CO-R _{c , wherein R a} , R _b , R _c are the same as or different from each other, and each independently hydrogen, any monovalent organic group, Or it may be an organic group linked to each other. The cyclic imide group _{means an organic group in which R a} and R _c are linked to each other.

When synthesizing the liquid crystal aligning film by the cyclic imide group, since the liquid crystal aligning film can be completed by directly irradiating light without a high temperature heat treatment process to generate anisotropy, and then performing heat treatment to complete the liquid crystal aligning film, the light irradiation energy can be greatly reduced In addition, it is possible to manufacture a liquid crystal aligning film having excellent alignment and stability, as well as electrical characteristics such as voltage maintenance retention rate, even with a simple process including one heat treatment process.

The unsubstituted arylene group is a divalent functional group derived from arene, but is not particularly limited, but preferably has 6 to 20 carbon atoms, and may include a monocyclic arylene group or a polycyclic arylene group. For example, it may be a phenylene group, a biphenylene group, a terphenylene group, a naphthalene group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a perylene group, a tetracenyl group, an anthracenyl group, and the like.

Specifically, the divalent functional group including a cyclic imide group and an unsubstituted arylene group of _{Y 2 may be a divalent functional group represented by Formula 5 below.}

[Formula 5]

In Formula 5, A ₃ and A ₄ are the same as or different from each other, each independently represent phenylene, and T ₂ is a tetravalent functional group. In Formula 5, the description of the tetravalent functional group of _{T 2} may include all the contents described above for _{X 2 of the repeating unit represented by Formula 2 as it is.}

In a more specific example, examples of the functional group represented by Chemical Formula 5 may include functional groups represented by the following Chemical Formulas 5-1 to 5-3.

[Formula 5-1]

[Formula 5-2]

[Formula 5-3]

On the other hand, based on the total repeating units contained in the copolymer, the molar content of the repeating unit represented by Formula 1 is 5 mol% or more, or 5 mol% or more and 95 mol% or less, or 5 mol% or more and 90 mol% or less, or 5 mol% or more and 50 mol% or less, or 10 mol% or more and 95 mol% or less, or 10 mol% or more and 90 mol% or less, or 10 mol% or more and 50 mol% or less.

The molar content of the repeating unit represented by Chemical Formula 1 may be obtained by dividing the number of moles of the repeating unit represented by Chemical Formula 1 by the total number of moles of repeating units contained in the copolymer and multiplying by 100.

In addition, since the repeating unit represented by Chemical Formula 1 and the repeating unit represented by Chemical Formula 2 differ only in the type of diamine used in the synthesis, the molar content of the repeating unit can be calculated from the number of moles of diamine added during the reaction. can

Specifically, the molar amount of the diamine (H ₂ NY ₁ -NH ₂₎ and a diamine (H ₂ NY ₂ -NH ₂₎ used in the repeat units synthesized represented by the above formula (2) that is used for repeat synthesis unit of the formula (1) The molar content of the above-described repeating unit may be obtained through the percentage ratio of the number of moles of _{diamine (H 2} NY ₁ -NH ₂ ) used in synthesizing the repeating unit represented by Formula 1 in the total.

On the other hand, when the molar content of the repeating unit represented by Formula 1 is excessively reduced to less than 5 mol% based on the total repeating units contained in the copolymer, the polyamic acid included in the repeating unit represented by Formula 1 is Since the imidation catalytic action by the arylene group structure substituted with at least one hetero atom is not sufficiently implemented, there is a limit in that the imidization rate and electrical properties of the liquid crystal aligning agent are reduced.

In addition, when the molar content of the repeating unit represented by Formula 1 is excessively increased based on the total repeating units contained in the copolymer, at least one hetero atom included in the repeating unit of the polyamic acid represented by Formula 1 is used. When the imidization catalytic action by the substituted arylene group structure is excessive, the reproducibility and stability are reduced due to a rapid change in the internal composition during long-term storage of the liquid crystal aligning agent due to side reactions, etc., and it is difficult to maintain stable alignment characteristics.

The copolymer contains 5 moles or more and 2000 moles or less, or 5 moles or more and 1000 moles or less, or 5 moles or more and 100 moles or less, or 10 moles of the repeating unit represented by Formula 1 to 100 moles of the repeating unit represented by Formula 2 It may be included in an amount of 2000 moles or less, or 10 moles or more and 1000 moles or less, or 10 moles or more and 100 moles or less.

The molar ratio between the repeating units In addition, the diamine used to synthesize the repeating unit represented by the diamine (H ₂ NY ₁ -NH ₂₎ and the formula (2) number of moles to be used in the repeating unit represented by the formula Synthesis 1 (H ₂ NY ₂ -NH ₂ ) can be obtained through the ratio between moles.

Meanwhile, the liquid crystal aligning agent may have an imidization rate of 75% or more, or 75% or more and 100% or less, or 75% or more and 99% or less, or 77% or more and 90% or less according to Equation 1 below.

[Equation 1]

Imidization rate (%) = (H ₁ / H ₂ ) X 100

In Equation 1, H ₁ is the height of the peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film obtained by applying the liquid crystal aligning agent to the substrate and baking at 230 ° C. for 1000 seconds _{, H 2} is the liquid crystal aligning agent It is the height of the peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film obtained by coating on a substrate and firing at 300° C. for 1000 seconds.

The type of substrate used for measuring the imidization rate is not particularly limited, for example, an ITO electrode having a thickness of 60 nm and an area of 1 cm X 1 cm on a rectangular glass substrate having a size of 2.5 cm X 2.7 cm. A patterned substrate may be used.

As an example of the IR spectrum measurement method, FT-IR measurement equipment may be used, and other IR spectrum measurement conditions are not particularly limited, and various known IR measurement methods are applicable without limitation.

The peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film corresponds to the imide group represented by _{R a} -CO-NR _b -CO-R _c ^{, and 1380 cm −} _{H 2} , the height of the peak shown in ¹ , means the imide functional group content after 100% complete imidization is completed, and is the height of the peak appearing at ^{1380 cm -1 on the IR spectrum of the coating film obtained by calcining at 230 ° C. for 1000 seconds.} H ₁ may mean the content of imide functional groups contained in the synthesized liquid crystal alignment layer.

That is, the high imidization rate of Equation 1 above 75% means that the liquid crystal aligning agent of one embodiment is present in a high content even when synthesizing the liquid crystal aligning agent into a liquid crystal aligning film even through a relatively low temperature sintering process of 230 ° C. This means that a liquid crystal aligning film having excellent electrical properties such as voltage maintenance retention rate can be manufactured.

This seems to be due to the inclusion of a cyclic imide group in common in both the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2 contained in the liquid crystal aligning agent of the embodiment, which can significantly reduce light irradiation energy There is an advantage in that a liquid crystal aligning film having excellent alignment and stability can be manufactured even by a simple process including one heat treatment process.

Meanwhile, the liquid crystal aligning agent may further include an organic solvent. That is, the liquid crystal aligning agent may be dissolved or dispersed in an organic solvent. Specific examples of the organic solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone Don, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, gamma-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy -N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone , methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl Ethers, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether, ethylene glycol monopropyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, etc. can be heard These may be used alone or may be used in combination.

In addition, the liquid crystal aligning agent may further include other components in addition to the organic solvent. As a non-limiting example, when the liquid crystal aligning agent is applied, the uniformity or surface smoothness of the film thickness is improved, or the adhesion between the liquid crystal aligning film and the substrate is improved, or the dielectric constant or conductivity of the liquid crystal aligning film is changed, Alternatively, an additive capable of increasing the compactness of the liquid crystal alignment layer may be additionally included. Examples of such additives include various solvents, surfactants, silane-based compounds, dielectrics or crosslinking compounds.

However, the content of the monoamine compound contained in the liquid crystal aligning agent may be less than 0.01% by weight. The monoamine compound may include at least one selected from the group consisting of pyridine, triethylamine, and 4-dimethylaminopyridine, and the monoamine compound serves as an imidization catalyst for promoting imidization of the liquid crystal aligning agent. material that can be used as

The meaning that the content of the monoamine compound contained in the liquid crystal aligning agent is less than 0.01% by weight means that the monoamine compound contained in the liquid crystal aligning agent is not included at all (0% by weight), or the degree of difficulty in measurement is extremely fine. It means that the effect is not realized to the extent that it is included as an amount and can be regarded as not added.

That is, the liquid crystal aligning agent of one embodiment is different from the prior art of adding a separate additive such as a monoamine compound into the liquid crystal aligning agent in order to induce imidization catalysis, by not adding a monoamine compound. When the catalyst additive is added, the viscosity of the liquid crystal aligning agent is greatly increased due to side reactions with the copolymer contained in the liquid crystal aligning agent, making it difficult to coat the liquid crystal aligning film smoothly after synthesizing the liquid crystal aligning agent. Changes can overcome the limitations of reducing reproducibility and stability.

Examples of the method for preparing the liquid crystal aligning agent are not particularly limited, and for example, a liquid crystal alignment comprising the step of reacting a mixture containing a diamine of the following Chemical Formula 7 and a diamine of the following Chemical Formula 8 with tetracarboxylic acid or an anhydride thereof A method for preparing the copolymer for formulation can be used.

[Formula 7]

In Formula 7, A ₁ and A ₂ are the same as or different from each other, each independently represent phenylene in which at least one nitrogen atom is substituted, and T ₁ is a tetravalent functional group. In Formula 7, _{the contents of A 1} , A ₂ , and T ₁ may include all the contents described above in Formula 3 above.

[Formula 8]

In Formula 5, A ₃ and A ₄ are the same as or different from each other, each independently represent phenylene, and T ₂ is a tetravalent functional group. In Formula 7, _{the contents of A 3} , A ₄ , and T ₂ may include all the contents described above in Formula 5 above.

Here, based on the whole mixture containing the diamine of Formula 7 and the diamine of Formula 8, the molar content of the diamine of Formula 7 is 5 mol% or more, or 5 mol% or more and 95 mol% or less, or 5 mol% or more 90 mol% or less, or 5 mol% or more and 50 mol% or less, or 10 mol% or more and 95 mol% or less, or 10 mol% or more and 90 mol% or less, or 10 mol% or more and 50 mol% or less.

Specifically, the above-described molar content can be obtained through the percentage ratio of the number of moles of the diamine of Formula 7 to the total number of moles of the diamine of Formula 7 and the diamine of Formula 8.

In addition, with respect to 100 moles of the diamine of Formula 8, 5 moles or more and 2000 moles or less of the diamine of Formula 7, or 5 moles or more and 1000 moles or less, or 5 moles or more and 100 moles or less, or 10 moles or more and 2000 moles or less, or It may contain 10 moles or more and 1000 moles or less, or 10 moles or more and 100 moles or less.

The mixture containing the diamine of Formula 7 and the diamine of Formula 8 is a tetracarboxylic acid or anhydride thereof commonly used in the preparation of polyamic acid, for example, 1,3-dimethylcyclobutane-1,2,3,4 -tetracarboxylic dianhydride (1,3-Dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, DMCBDA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (Cyclobutane-1,2,3, 4-tetracarboxylic dianhydride, CBDA), Pyromellitic dianhydride (PMDA, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, or 1,2,4,5-cyclohexanetetracarboxylic acid di It can be reacted with an anhydride, etc. to prepare a copolymer composed of amic acid, amic acid ester, or a mixture thereof.

Or, if necessary, in addition to the diamine of Formula 7 and the diamine of Formula 8, various types of diamine compounds widely known in the liquid crystal aligning field related field, for example, p-phenylenediamine, 4,4-oxydianiline, 4,4'-methylenedianiline may be further mixed to prepare an amic acid, an amic acid ester, or a mixture thereof.

The reaction conditions may be appropriately adjusted with reference to the production conditions of polyamic acid known in the art to which the present invention pertains. And, it is possible to prepare a copolymer including the repeating unit represented by the above-described formula (1) and the repeating unit represented by the formula (2) at the same time through the obtained amic acid.

2. Manufacturing method of liquid crystal aligning film

In addition, the present invention comprises the steps of forming a coating film by applying the liquid crystal aligning agent of the embodiment to a substrate; drying the coating film; Orienting the dried coating film by irradiating light or rubbing treatment; And it provides a method of manufacturing a liquid crystal alignment film comprising the step of curing the coating film by heat treatment of the alignment treatment.

In the step of forming a coating film by applying the liquid crystal aligning agent of the one embodiment to the substrate, the content regarding the liquid crystal aligning agent includes all of the contents described above in the embodiment.

A method of applying the liquid crystal aligning agent to the substrate is not particularly limited, and for example, a method such as screen printing, offset printing, flexographic printing, inkjet, or spin coating may be used.

The step of drying the coating film formed by applying the liquid crystal aligning agent to the substrate may be performed by heating means such as a hot plate, a hot air circulation furnace, an infrared furnace, etc. temperature can be performed.

In the step of irradiating light or rubbing the dried coating film for alignment treatment, light irradiation may be to irradiate polarized ultraviolet rays with a wavelength of 150 nm to 450 nm. At this time, the intensity of exposure varies depending on the type of the copolymer for liquid crystal aligning agent, and energy of 10 mJ/cm 2 or more and 10 J/cm 2 or less, or 30 mJ/cm 2 or more and 2 J/cm 2 or less energy may be irradiated.

In the present specification, the dried coating film means "the coating film immediately after the drying step", and means directly irradiating light without proceeding with the step of heat treatment at a temperature higher than the drying step after the drying step. It is possible.

As the ultraviolet rays, a polarizing device using a substrate coated with a dielectric anisotropic material on the surface of a transparent substrate such as quartz glass, soda lime glass, soda lime free glass, a polarizing plate on which aluminum or metal wire is finely deposited, or quartz glass The alignment treatment is performed by irradiating polarized ultraviolet rays selected from among the polarized ultraviolet rays through a method of passing or reflecting a Brewster polarizing device by reflection. In this case, the polarized ultraviolet rays may be irradiated perpendicular to the substrate surface, or may be irradiated by inclining the incident angle to a specific angle. By this method, the alignment ability of the liquid crystal molecules is imparted to the coating film.

In addition, the rubbing treatment in the alignment treatment step may use a method using a rubbing cloth. More specifically, in the rubbing treatment, the surface of the coating film may be rubbed in one direction while rotating a rubbing roller having a cloth of rubbing cloth attached to a metal roller.

In the step of heat-treating and curing the orientation-treated coating film, the heat treatment may be performed by a heating means such as a hot plate, a hot air circulation furnace, an infrared furnace, and 180 ° C or more and 300 ° C or less, or 200 ° C or more and 300 ° C or less, Alternatively, it may be carried out at a temperature of 200 °C or higher and 250 °C or lower.

3. Liquid crystal alignment film

In addition, the present invention provides a liquid crystal aligning film prepared according to the manufacturing method of the liquid crystal aligning film described above. Specifically, the liquid crystal aligning layer may include an alignment cured product of the liquid crystal aligning agent of the embodiment. The alignment cured product means a material obtained through an alignment process and a curing process of the liquid crystal aligning agent of the embodiment.

As described above, the repeating unit represented by Formula 1; And when a liquid crystal aligning agent comprising a copolymer including a repeating unit represented by Formula 2 is used, a liquid crystal aligning film having a high voltage retention in a liquid crystal cell and a high imidization rate in the alignment film manufacturing process is manufactured can do.

The thickness of the liquid crystal alignment layer is not particularly limited, but can be freely adjusted within, for example, 0.001 μm or more and 100 μm or less. When the thickness of the liquid crystal alignment layer increases or decreases by a specific value, physical properties measured in the alignment layer may also change by a specific value.

4. Liquid crystal display device

In addition, the present invention provides a liquid crystal display device including the above-described liquid crystal alignment layer.

The liquid crystal alignment layer may be introduced into a liquid crystal cell by a known method, and the liquid crystal cell may be introduced into a liquid crystal display device by a known method as well. The liquid crystal aligning layer may be prepared from the liquid crystal aligning agent of the embodiment to implement excellent stability along with excellent overall physical properties. Accordingly, a liquid crystal display device capable of exhibiting high reliability is provided.

The liquid crystal display device may have a voltage retention of 70% or more, or 79% or more and 87% or less, measured using TOYO corporation's 6254C equipment at 1V, 1Hz, and 60 ℃ temperature. When the voltage retention measured using TOYO corporation's 6254C equipment at 1V, 1Hz, and 60 ℃ temperature of the liquid crystal alignment display device decreases to less than 70%, it is difficult to implement a liquid crystal display device with high quality driving characteristics at low power. can get

In addition, after attaching the polarizing plates to the upper and lower plates so that they are perpendicular to each other, the liquid crystal display device is attached on a backlight of 7,000 cd/m2, and the initial luminance (L0), which is the luminance in the black state measured using PR-880 equipment, and room temperature The luminance fluctuation rate, which is a value obtained by dividing the difference between the later luminance L1, which is the luminance in the black state, measured after driving at AC voltage of 5V, by the initial luminance L0 value, and multiplied by 100, is 20% or less, or less than 10%.

According to the present invention, a liquid crystal aligning agent capable of ensuring a high imidization rate in the alignment film firing process and implementing excellent electrical properties, a method for manufacturing a liquid crystal alignment film using the same, a liquid crystal alignment film using the same, and a liquid crystal display device can be provided have.

The invention is described in more detail in the following examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

<Preparation Example: Preparation of diamine>

Preparation Example 1: Preparation of diamine DA1

It was prepared according to the following reaction scheme.

구체적으로, DMCBDA(1,3-디메틸사이클로부탄-1,2,3,4-테트라카복실산 이무수물, 화합물 1)과 2-아미노-5-니트로피리딘(2-amino-5-nitropyridine, 화합물 2)을 DMF(Dimethylformamide)에 용해시켜 혼합물을 제조하였다. 이어서, 상기 혼합물을 약 80 ℃에서 약 12 시간 동안 반응시켜 화합물 3의 아믹산을 제조하였다. 이후, 상기 화합물 3의 아믹산을 DMF에 용해시키고, 아세트산 무수물 및 아세트산 나트륨을 첨가하여 혼합물을 제조하였다. 이어서, 상기 혼합물에 포함된 화합물 3의 아믹산을 약 90 ℃에서 약 4 시간 동안 이미드화시켜 화합물 4을 얻었다. 이렇게 얻어진 화합물 4의 이미드를 DMAc(Dimethylacetamide)에 용해시킨 후, Pd/C를 첨가하고 혼합물을 제조하였다. 이를 약 45 ℃ 및 약 6 bar의 수소 압력 하에서 20 시간 동안 환원시켜 디아민 DA1(Molecular weight : 406.40)을 제조하였다.

Specifically, DMCBDA (1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, compound 1) and 2-amino-5-nitropyridine (2-amino-5-nitropyridine, compound 2) was dissolved in DMF (dimethylformamide) to prepare a mixture. Then, the mixture was reacted at about 80° C. for about 12 hours to prepare amic acid of compound 3. Thereafter, the amic acid of Compound 3 was dissolved in DMF, and acetic anhydride and sodium acetate were added to prepare a mixture. Then, the amic acid of compound 3 contained in the mixture was imidized at about 90° C. for about 4 hours to obtain compound 4. The imide of Compound 4 thus obtained was dissolved in DMAc (dimethylacetamide), and then Pd/C was added to prepare a mixture. This was reduced at about 45° C. and under a hydrogen pressure of about 6 bar for 20 hours to prepare diamine DA1 (Molecular weight: 406.40).

Preparation Example 2: Preparation of diamine DA2

It was prepared according to the following reaction scheme.

구체적으로, DMCBDA(1,3-디메틸사이클로부탄-1,2,3,4-테트라카복실산 이무수물, 화합물 5)과 4-니트로아닐린(4-nitroaniline, 화합물 6)을 DMF(Dimethylformamide)에 용해시켜 혼합물을 제조하였다. 이어서, 상기 혼합물을 약 80 ℃에서 약 12 시간 동안 반응시켜 화합물 7의 아믹산을 제조하였다. 이후, 상기 화합물 7의 아믹산을 DMF에 용해시키고, 아세트산 무수물 및 아세트산 나트륨을 첨가하여 혼합물을 제조하였다. 이어서, 상기 혼합물에 포함된 화합물 7의 아믹산을 약 90 ℃에서 약 4 시간 동안 이미드화시켜 화합물 8을 얻었다. 이렇게 얻어진 화합물 8의 이미드를 DMAc(Dimethylacetamide)에 용해시킨 후, Pd/C를 첨가하고 혼합물을 제조하였다. 이를 약 45 ℃ 및 약 6 bar의 수소 압력 하에서 약 20 시간 동안 환원시켜 디아민 DA2(Molecular weight : 404.43)을 제조하였다.

Specifically, DMCBDA (1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, compound 5) and 4-nitroaniline (4-nitroaniline, compound 6) were dissolved in DMF (dimethylformamide). A mixture was prepared. Then, the mixture was reacted at about 80° C. for about 12 hours to prepare amic acid of compound 7. Then, the amic acid of compound 7 was dissolved in DMF, and acetic anhydride and sodium acetate were added to prepare a mixture. Then, the amic acid of compound 7 contained in the mixture was imidized at about 90° C. for about 4 hours to obtain compound 8. The imide of compound 8 thus obtained was dissolved in DMAc (dimethylacetamide), and then Pd/C was added to prepare a mixture. This was reduced at about 45° C. and under a hydrogen pressure of about 6 bar for about 20 hours to prepare diamine DA2 (Molecular weight: 404.43).

Preparation Example 3: Preparation of diamine DA3

It was prepared according to the following reaction scheme.

구체적으로, DMCBDA(1,3-디메틸사이클로부탄-1,2,3,4-테트라카복실산 이무수물, 화합물 9)과 (5-아미노피리딘-2-일)카바메이트 (5-aminopyridin-2-yl)carbamate, 화합물 10)을 DMF(Dimethylformamide)에 용해시켜 혼합물을 제조하였다. 이어서, 상기 혼합물을 약 80 ℃에서 약 12 시간 동안 반응시켜 화합물 11의 아믹산을 제조하였다. 이후, 상기 화합물 11의 아믹산을 DMF에 용해시키고, 아세트산 무수물 및 아세트산 나트륨을 첨가하여 혼합물을 제조하였다. 이어서, 상기 혼합물에 포함된 화합물 11의 아믹산을 약 90 ℃에서 약 4 시간 동안 이미드화시켜 화합물 12를 얻었다. 이렇게 얻어진 화합물 12의 이미드를 TFA(trifluoro acetic acid)와 DCM(Dichloromethane) 혼합용매에 넣어 혼합물을 제조하였다. 이를 실온에서 20 시간 동안 교반하여 디아민 DA3(Molecular weight : 406.40)을 제조하였다.

Specifically, DMCBDA (1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, compound 9) and (5-aminopyridin-2-yl) carbamate (5-aminopyridin-2-yl ) carbamate, compound 10) was dissolved in DMF (dimethylformamide) to prepare a mixture. Then, the mixture was reacted at about 80° C. for about 12 hours to prepare amic acid of compound 11. Then, the amic acid of compound 11 was dissolved in DMF, and acetic anhydride and sodium acetate were added to prepare a mixture. Then, the amic acid of compound 11 contained in the mixture was imidized at about 90° C. for about 4 hours to obtain compound 12. The imide of compound 12 thus obtained was put in a mixed solvent of TFA (trifluoro acetic acid) and DCM (Dichloromethane) to prepare a mixture. This was stirred at room temperature for 20 hours to prepare diamine DA3 (Molecular weight: 406.40).

<Example: Preparation of copolymer for liquid crystal aligning agent, liquid crystal aligning agent, liquid crystal aligning film and liquid crystal aligning cell>

Example 1

(1) Preparation of copolymer for liquid crystal aligning agents

As described in Table 1 below, 19.49 g of the diamine DA1 prepared in Preparation Example 1 as the first diamine and 19.40 g of the diamine DA2 prepared in Preparation Example 2 as the second diamine in a nitrogen atmosphere flask were added to the solvent N-methyl- After dissolving in 333.73 g of 2-pyrrolidone (N-methyl-2-pyrrolidone: NMP), the temperature was maintained at 50 °C. Then, 20.00 g of 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride (DMCBDA) as acid dianhydride in the flask was added and stirred at 25°C for 24 hours to prepare a copolymer for a liquid crystal aligning agent.

(2) Preparation of liquid crystal aligning agent

20 g of the copolymer for liquid crystal aligning agent was dissolved in a mixed solvent of 28.6 g of NMP and 11.4 g of 2-butoxyethanol to obtain a 5 wt% solution. Then, the obtained solution was filtered under pressure with a filter having a pore size of 0.1 μm made of poly(tetrafluoroethylene) material to prepare a liquid crystal aligning agent from which impurities were removed.

(3) Preparation of liquid crystal aligning film

Specifically, Example 1 was applied to each of the upper and lower substrates for voltage retention (VHR) in which ITO electrodes having a thickness of 60 nm and an area of 1 cm X 1 cm were patterned on a rectangular glass substrate having a size of 2.5 cm X 2.7 cm. The liquid crystal aligning agent obtained by (2) of was apply|coated. Then, the substrate coated with the liquid crystal aligning agent was placed on a hot plate at 80° C. and dried for 3 minutes to evaporate the solvent. In order to align the obtained coating film, ultraviolet rays of 254 nm were irradiated using an exposure machine with a linear polarizer attached to each coating film of the upper and lower plates. Thereafter, the alignment-treated upper/lower plates were baked (cured) in an oven at about 230° C. for about 30 minutes to obtain a liquid crystal aligning film having a thickness of 0.1 μm.

(4) Preparation of liquid crystal alignment cell

A sealing agent impregnated with a 4.5 μm ball spacer was applied to the edge of the upper plate except for the liquid crystal injection hole. And, after aligning the liquid crystal alignment films obtained in Example 1 (3) formed on the upper plate and the lower plate so that they face each other and the orientation directions are parallel to each other, the upper and lower plates are bonded and the sealing agent is UV and heat cured to prepare an empty cell did Then, liquid crystal was injected into the empty cell and the injection hole was sealed with a sealing agent, thereby manufacturing a liquid crystal alignment cell.

Examples 2 to 5

As shown in Table 1 below, a copolymer for a liquid crystal aligning agent, a liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal aligning cell were prepared in the same manner as in Example 1 except for changing the material type and the amount added.

<Comparative Example: Preparation of a copolymer for liquid crystal aligning agent, liquid crystal aligning agent, liquid crystal aligning film and liquid crystal aligning cell>

Comparative Examples 1 to 2

As shown in Table 1 below, a copolymer for a liquid crystal aligning agent, a liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal aligning cell were prepared in the same manner as in Example 1 except for changing the material type and the amount added.

<Reference example: Preparation of copolymer for liquid crystal aligning agent, liquid crystal aligning agent, liquid crystal aligning film and liquid crystal aligning cell >

Reference Example 1

As shown in Table 1 below, a copolymer for a liquid crystal aligning agent, a liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal aligning cell were prepared in the same manner as in Example 1 except for changing the material type and the amount added.

division primary diamine secondary diamine acid dianhydride menstruum substance type substance content
(molar ratio) substance type substance content
(molar ratio) substance type substance content
(molar ratio) substance type substance content Example 1 Preparation Example 1 (DA1) 19.49g
(0.50) Preparation Example 2 (DA2) 19.40g
(0.50) DMCBDA 20.00g
(0.93) NMP 333.73g Example 2 Preparation Example 1 (DA1) 3.90 g (0.10) Preparation Example 2 (DA2) 34.92g
(0.90) DMCBDA 20.00g
(0.93) NMP 333.30g Example 3 Preparation 3 (DA3) 3.90 g (0.10) Preparation Example 2 (DA2) 34.92g
(0.90) DMCBDA 20.00g
(0.93) NMP 333.30g Example 4 Preparation Example 1 (DA1) 4.46 g (0.10) Preparation Example 2 (DA2) 39.91g
(0.90) CBDA 20.00g
(0.93) NMP 364.77g Example 5 Preparation Example 1 (DA1) 4.01 g (0.10) Preparation Example 2 (DA2) 35.89g
(0.90) PMDA 20.00g
(0.93) NMP 339.40g Comparative Example 1 - - Preparation Example 2 (DA2) 38.80 g (1.00) DMCBDA 20.00g
(0.93) NMP 333.19g Comparative Example 2 p-PDAs 10.37 g (1.00) Preparation Example 2 (DA2) 0.10g
(0.00) DMCBDA 20.00g
(0.93) NMP 172.12g Reference Example 1 Preparation Example 1 (DA1) 0.39g (0.01) Preparation Example 2 (DA2) 38.41g
(0.99) DMCBDA 20.00g
(0.93) NMP 333.30g

* Molar ratio of 1st diamine: (number of moles of 1st diamine) / (sum of moles of 1st diamine and 2nd diamine)

* Second diamine molar ratio: (number of moles of second diamine) / (sum of moles of first diamine and second diamine)

* Molar ratio of acid dianhydride: (number of moles of acid dianhydride) / (sum of moles of first and second diamines)

* CBDA: Cyclobutane-1,2,3,4-tetracarboxylic dianhydride

* PMDA: Pyromellitic dianhydride

* p-PDA: p-phenylenediamine (p-Phenylenediamine)

<Experimental example>

Using the liquid crystal aligning agent or liquid crystal aligning cell obtained in Examples and Comparative Examples, each physical property was measured in the following manner, and the results are shown in Table 2.

1. Evaluation of liquid crystal alignment characteristics

Polarizing plates were attached to the upper and lower plates of the liquid crystal alignment cells prepared in Examples and Comparative Examples so as to be perpendicular to each other. The liquid crystal cell to which the polarizing plate was attached was attached to a backlight of 7,000 cd/m2, and the luminance in the black state was measured using the PR-880 equipment, which is a luminance brightness measuring equipment. Then, the liquid crystal cell was driven at room temperature with an AC voltage of 5 V for 24 hours. Thereafter, in a state in which the voltage of the liquid crystal cell was turned off, the luminance of the black state was measured in the same manner as described above. _{The difference between the initial luminance (L 0} ) measured before driving of the liquid crystal cell and the later luminance (L ₁ ) measured after driving was divided by the initial luminance (L ₀ ) value and multiplied by 100 to calculate the luminance change rate. As the luminance fluctuation rate calculated in this way is closer to 0%, it means that the orientation stability is excellent. Based on the measurement result of the luminance change rate, the level of afterimage was evaluated under the following criteria. It is desirable to minimize the AC afterimage, and in the measurement result, if the luminance fluctuation rate is less than 10%, it is evaluated as 'excellent', if the luminance fluctuation rate is 10% or more and less than 20%, 'normal', and if the luminance fluctuation rate exceeds 20%, it was evaluated as 'poor'. , the results are shown in Table 2 below.

2. Voltage holding ratio (VHR)

Voltage holding ratio (VHR), which is an electrical characteristic of the liquid crystal alignment cells prepared in Examples and Comparative Examples, was measured using TOYO Corporation's 6254C equipment. Voltage retention (VHR) was measured at 1 V, 1 Hz, and 60 °C (VHR 60 °C 1 Hz n-LC conditions). The measurement results for the voltage retention (VHR) of the liquid crystal alignment cell are shown in Table 2 below.

3. Imidization rate

With respect to the liquid crystal aligning agent obtained in Examples and Comparative Examples, on a rectangular glass substrate having a size of 2.5 cm X 2.7 cm, a thickness of 60 nm, an area of 1 cm X 1 cm on each of the upper and lower substrates patterned with ITO electrodes After spin coating, the IR spectrum of the coating film obtained by baking (curing) on a hot plate at 230 °C for 1000 seconds and the IR spectrum of the coating film obtained by baking (curing) on a hot plate at 300 °C for 1000 seconds were obtained through FT-IR measurement equipment.

And, the peak appearing in the 230 ℃ 1000 seconds baked coating film of the IR spectrum the height of the peak 1380cm ^-1 (H _1), IR spectrum of the coating film obtained by baking in the 300 ℃ 1000 seconds the 1380cm ^-1 appear in the resulting After the height (H ₂ ) was obtained, the ratio obtained by the following Equation 1 was defined as the imidization ratio, and this ratio was calculated and shown in Table 2.

[Equation 1]

Imidization rate (%) = The height of the peak (H ₁ ^{) at 1380 cm -1} in the IR spectrum of the coating film obtained by baking at 230 ° C. for 1000 seconds ^{/ 1380 cm -1} in the IR spectrum of the coating film obtained by baking at 300 ° C. for 1000 seconds The height of the appearing peak (H ₂ ) X 100

The peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film corresponds to the imide group represented by _{R a} -CO-NR _b -CO-R _c ^{, and 1380 cm −} _{H 2} , the height of the peak shown in ¹ , means the imide functional group content after 100% complete imidization is completed, and is the height of the peak appearing at ^{1380 cm -1 on the IR spectrum of the coating film obtained by calcining at 230 ° C. for 1000 seconds.} H ₁ may mean the content of imide functional groups contained in the synthesized liquid crystal alignment layer.

division Orientation characteristics VHR(%) Imidization rate (%) Example 1 Great 87 83 Example 2 Great 83 80 Example 3 Great 84 81 Example 4 Great 79 77 Example 5 Great 85 90 Comparative Example 1 Great 43 63 Comparative Example 2 error 37 70 Reference Example 1 Great 54 68

As shown in Table 2, in the case of Examples 1 to 5, the diamine obtained in Preparation Example 1 or Preparation Example 3 was used as the first diamine, and the diamine obtained in Preparation Example 2 was applied together as the second diamine for a liquid crystal aligning agent. By using the copolymer, it is possible to secure excellent alignment with a luminance fluctuation rate of less than 10% of the liquid crystal cell, and the voltage retention (VHR) is increased to 79% or more and 87% or less, thereby improving electrical properties, and imide It was confirmed that the efficiency of the polyimide liquid crystal alignment film manufacturing process could be improved by increasing the ratio to 77% or more and 90% or less. On the other hand, in the case of Comparative Examples 1 and 2, since the diamine obtained in Preparation Example 1 or Preparation Example 3 was not included, the voltage retention rate (VHR) of the liquid crystal cell was significantly reduced to 37% or more and 43% or less compared to Examples, resulting in improved electrical properties. It was confirmed that the efficiency of the polyimide liquid crystal aligning film manufacturing process was also reduced as the imidization rate was lowered to 63% or more and 70% or less compared to the example.

Claims (15)

a repeating unit represented by the following formula (1); and
A liquid crystal aligning agent comprising a copolymer comprising; a repeating unit represented by the following formula (2):
[Formula 1]

[Formula 2]

In Formulas 1 and 2,
X ₁ and X ₂ are the same as or different from each other, and are each independently a tetravalent functional group,
Y ₁ is a divalent functional group including a cyclic imide group and an arylene group substituted with at least one hetero atom,
Y ₂ is a divalent functional group including a cyclic imide group and an unsubstituted arylene group.
According to claim 1,
The _{divalent functional group including a cyclic imide group of Y 1} and an arylene group substituted with at least one hetero atom is a divalent functional group represented by the following Chemical Formula 3, a liquid crystal aligning agent:
[Formula 3]

In Formula 3,
A ₁ and A ₂ are the same as or different from each other, and each independently represents phenylene in which at least one nitrogen atom is substituted,
T ₁ is a tetravalent functional group.
3. The method of claim 2,
The phenylene in which at least one nitrogen atom is substituted is any one of a functional group represented by the following Chemical Formula 4-1 or a functional group represented by Chemical Formula 4-2, a liquid crystal aligning agent:
[Formula 4-1]

[Formula 4-2]

.
3. The method of claim 2,
The divalent functional group represented by Formula 3 below is any one of a functional group represented by Formula 3-1 or a functional group represented by Formula 3-2, a liquid crystal aligning agent:
[Formula 3-1]

[Formula 3-2]

In Formulas 3-1 and 3-2,
T ₁ is a tetravalent functional group.
According to claim 1,
The _{divalent functional group including a cyclic imide group and an unsubstituted arylene group of Y 2} is a divalent functional group represented by the following Chemical Formula 5, a liquid crystal aligning agent:
[Formula 5]

In Formula 5,
A ₃ and A ₄ are the same as or different from each other, and are each independently phenylene,
T ₂ is a tetravalent functional group
According to claim 1,
The _{tetravalent functional group of X 1} and X ₂ is any one selected from functional groups represented by the following Chemical Formula 6, a liquid crystal aligning agent:
[Formula 6]

In the above formula (6),
R ₁ to R ₆ are the same as or different from each other, and each independently represent one of hydrogen or an alkyl group having 1 to 6 carbon atoms,
L ₁ is a single bond, -O-, -CO-, -COO-, -S-, -SO-, -SO ₂ -, -CR ₇ R ₈ -, -(CH ₂ ) _Z -, -O(CH ₂ ) _Z O-, -COO(CH ₂ ) _Z OCO-, -CONH-, or any one selected from phenylene,
In L ₁ , R ₇ and R ₈ are the same as or different from each other, and each independently represents one of hydrogen, an alkyl group having 1 to 10 carbon atoms, or a haloalkyl group having 1 to 10 carbon atoms,
In L ₁ , z is an integer of 1 to 10.
According to claim 1,
Based on the total repeating units contained in the copolymer, the molar content of the repeating unit represented by Formula 1 is 5 mol% or more, the liquid crystal aligning agent.
According to claim 1,
The copolymer is a liquid crystal aligning agent comprising 5 moles or more and 2000 moles or less of the repeating unit represented by the formula (1) with respect to 100 moles of the repeating unit represented by the formula (2).
According to claim 1,
A liquid crystal aligning agent having an imidization rate of 75% or more by the following Equation 1:
[Equation 1]
Imidization rate (%) = (H ₁ / H ₂ ) X 100
In Equation 1, H ₁ is the height of the peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film obtained by applying the liquid crystal aligning agent to the substrate and baking at 230 ° C. for 1000 seconds,
H ₂ is the height of the peak appearing at ^{1380 cm -1} on the IR spectrum of the coating film obtained by applying the liquid crystal aligning agent to the substrate and baking at 300° C. for 1000 seconds.
According to claim 1,
The content of the monoamine compound contained in the liquid crystal aligning agent is less than 0.01% by weight, the liquid crystal aligning agent.
11. The method of claim 10,
The monoamine compound is a liquid crystal aligning agent comprising at least one selected from the group consisting of pyridine, triethylamine, and 4-dimethylaminopyridine.
Forming a coating film by applying the liquid crystal aligning agent of claim 1 to a substrate;
drying the coating film;
Orienting the dried coating film by irradiating light or rubbing treatment; and
A method of manufacturing a liquid crystal alignment film, including; curing the alignment-treated coating film by heat treatment.
The liquid crystal aligning film containing the orientation hardened|cured material of the liquid crystal aligning agent of Claim 1.
A liquid crystal display device comprising the liquid crystal alignment layer of claim 13 .
15. The method of claim 14,
The liquid crystal display device has a voltage retention ratio of 70% or more measured using TOYO corporation's 6254C equipment at 1V, 1Hz, and 60 ℃ temperature.