KR102251401B1 - Liquid crystal alignment composition, 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 composition including a polyimide precursor (co)polymer and an imidization catalyst having a specific chemical structure, a method of manufacturing a liquid crystal aligning film using the same, and a liquid crystal aligning film and a liquid crystal display device using the same.

Description

A liquid crystal aligning agent composition, a method of manufacturing a liquid crystal aligning film using the same, and a liquid crystal aligning film and a liquid crystal display device using the same.

The present invention is a liquid crystal aligning agent composition capable of producing a liquid crystal aligning film having excellent storage stability, securing a high imidation rate, and having improved film strength as well as liquid crystal alignment characteristics, a method of manufacturing a liquid crystal aligning film using the same, and It relates to a used liquid crystal alignment film and a liquid crystal display device.

In a liquid crystal display device, the liquid crystal alignment layer plays a role of aligning the liquid crystal in a predetermined direction. Specifically, the liquid crystal alignment layer acts as a director in the arrangement of liquid crystal molecules, so that the liquid crystal moves by an electric field to form an image, so that the liquid crystal aligns the proper direction. In general, in order to obtain uniform brightness and high contrast ratio in a liquid crystal display device, it is essential to uniformly align the liquid crystal.

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

In order to solve the problem of the rubbing method, recently, a photo-alignment method of inducing anisotropy (anisotropy) to a polymer film by light irradiation rather than friction, and arranging liquid crystals using the same has been studied.

Various materials are introduced as materials that can be used in the photo-alignment method, and among them, polyimide is mainly used for good overall performance of the liquid crystal alignment layer. However, in general, polyimide has poor solvent solubility, and it is difficult to apply it directly to a manufacturing process in which an alignment layer is formed by coating in a solution state. Accordingly, after coating in the form of a precursor such as polyamic acid or polyamic acid ester having excellent solubility, polyimide is formed through a high-temperature heat treatment process, and the alignment treatment is performed by irradiating light thereto.

However, in the process of imidizing a precursor such as polyamic acid or polyamic acid ester into a polyimide, sufficient imidization was not performed, so that the physical properties such as film strength and chemical resistance of the finally obtained liquid crystal alignment layer decreased, and the alignment characteristics were deteriorated. There was a problem of becoming.

To solve this problem, a method of adding an imidation catalyst such as a tertiary amine to the liquid crystal alignment agent composition has been proposed, but the tertiary amine precipitates due to reaction with the carboxy group present in the polyamic acid or causes depolymerization, resulting in stability of the solution. There was a limit to hinder it.

Accordingly, there is a need to develop a catalyst that does not have a problem in the stability of the solution while promoting the imidization of a precursor such as polyamic acid or polyamic acid ester in the liquid crystal alignment agent composition.

The present invention relates to a liquid crystal aligning agent composition capable of producing a liquid crystal aligning film having excellent storage stability, securing a high imidation rate, and having improved film strength along with liquid crystal alignment characteristics.

In addition, the present invention is to provide a method for producing a liquid crystal aligning film using the liquid crystal aligning agent composition.

In addition, the present invention is to provide a liquid crystal alignment layer manufactured by the above manufacturing method and a liquid crystal display device including the same.

In order to solve the above problems, in the present specification, selected from the group consisting of a polyimide repeating unit represented by the following formula (1), a polyamic acid ester repeating unit represented by the following formula (2), and a polyamic acid repeating unit represented by the following formula (3). (Co)polymers containing one or more repeating units; It provides a liquid crystal aligning agent composition comprising; and an imidization catalyst compound represented by the following formula (6).

[Formula 1]

[Formula 2]

[Formula 3]

In Formulas 1 to 3, _{at least one of R 1} and R ₂ is an alkyl group having 1 to 10 carbon atoms, the rest are hydrogen, X ₁ to X ₃ are the same as or different from each other, and each independently a tetravalent functional group, Y ₁ to Y ₃ are the same as or different from each other, and each independently is one of a divalent functional group represented by the following formula (4) or a divalent functional group represented by the following formula (5),

[Formula 4]

In Formula 4, T is a tetravalent functional group, L ₁ and L ₂ are each independently a divalent functional group,

[Formula 5]

In Formula 5, _{at least one of Q 1} to Q ₈ is nitrogen, the rest is carbon, D is -NR'-, R'is hydrogen or an alkyl group having 1 to 6 carbon atoms,

[Formula 6]

In Formula 6, R ₃ is one of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ₄ is to R _{Each 8} is independently a monovalent functional group.

In the present specification, further, a step of forming a coating film by applying the liquid crystal aligning agent composition to a substrate; Drying the coating film; Performing alignment treatment by irradiating light or rubbing the coating film; And there is provided a method of manufacturing a liquid crystal alignment film comprising the step of curing the alignment-treated coating film by heat treatment.

In the present specification, a liquid crystal alignment layer and a liquid crystal display device including the same are provided, which are manufactured according to a method of manufacturing a liquid crystal alignment layer.

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

In the present specification, the following terms may be defined as follows unless there is a specific limitation.

In the present specification, (co)polymer refers to all of a polymer or a copolymer, the polymer refers to a homopolymer composed of a single repeating unit, and the copolymer refers to a composite polymer containing two or more types of repeating units.

In the present specification, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

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

In the present specification, the term "substitution" means that other functional groups are bonded instead of a hydrogen atom 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 can be substituted, and when two or more are substituted , Two or more substituents may be the same or different from each other.

In the present specification, the term "substituted or unsubstituted" refers to deuterium; Halogen group; Cyano group; Nitro group; Hydroxy group; Carbonyl group; Ester group; Imide group; Amide group; Primary amino group; Carboxyl group; Sulfonic acid group; Sulfonamide group; Phosphine oxide group; Alkoxy group; Aryloxy group; Alkyl thioxy group; Arylthioxy group; Alkyl sulfoxy group; Arylsulfoxy group; Silyl group; Boron group; Alkyl group; Cycloalkyl group; Alkenyl group; Aryl group; Aralkyl group; Aralkenyl group; Alkylaryl group; Alkoxysilylalkyl group; Arylphosphine group; Or it means substituted or unsubstituted with one or more substituents selected from the group consisting of a heterocyclic group containing one or more of N, O, and S atoms, or substituted or unsubstituted with two or more substituents connected among the aforementioned substituents. . For example, "a substituent to 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 to 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

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

In the present specification, the alkyl group is a monovalent functional group derived from alkane and may be linear or branched, and the number of carbon atoms of the linear alkyl group is not particularly limited, but is preferably 1 to 20. Further, the branched chain alkyl group has 3 to 20 carbon atoms. 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, but are not limited thereto. The alkyl group may be substituted or unsubstituted.

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

In the present specification, the cycloalkyl group is a monovalent functional group derived from cycloalkane, may be monocyclic or polycyclic, and is not particularly limited, but has 3 to 20 carbon atoms. According to another exemplary embodiment, the cycloalkyl group has 3 to 10 carbon atoms. 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.

In the present specification, the aryl group is a monovalent functional group derived from arene, 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 phenyl group, a biphenyl group, or a terphenyl group, but the monocyclic aryl group 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.

In the present specification, the alkylene group is a divalent functional group derived from alkane, and the description of the above alkyl group 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.

In the present specification, the heteroalkylene group is an alkylene group containing O, N or S as a hetero atom, and the description of the above alkylene group may be applied. The heteroarylene group may be substituted or unsubstituted.

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.

In the present specification, the heteroaryl group includes one or more atoms other than carbon and one or more heteroatoms, and specifically, the heteroatom may include one or more atoms selected from the group consisting of O, N, Se, and S. The number of carbon atoms is not particularly limited, but is preferably 4 to 20 carbon atoms, and the heteroaryl group may be monocyclic or polycyclic. Examples of the heterocyclic group include thiophene group, furanyl group, pyrrole group, imidazolyl group, thiazolyl group, oxazolyl group, oxadiazolyl group, pyridyl group, bipyridyl group, pyrimidyl group, triazinyl group, tria Zolyl 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, p Nanthrolyl group (phenanthroline), thiazolyl group, isoxazolyl group, oxadiazolyl group, thiadiazolyl group, benzothiazolyl group, phenothiazinyl group, aziridyl group, azaindolyl group, isoindole group, inda Sleepy, purine, pteridine, beta-carbolyl, naphthyridine, ter-pyridyl, phenazinyl, imidazopyridyl, pyropyridyl, azepine , A pyrazolyl group and a dibenzofuranyl group, but are not limited thereto. The heteroaryl group may be substituted or unsubstituted.

In the present specification, the cycloalkylene group is a divalent functional group derived from cycloalkane, 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.

In the present specification, the heteroarylene group has 2 to 20, or 2 to 10, or 6 to 20 carbon atoms. An arylene group containing O, N, or S as a hetero atom, except that it is a divalent functional group, may be applied to the description of the heteroaryl group described above. The heteroarylene group may be substituted or unsubstituted.

In the present specification, the alkoxy group having 1 to 10 carbon atoms may be a straight chain, branched chain, or cyclic alkoxy group. Specifically, the alkoxy group having 1 to 10 carbon atoms is a linear alkoxy group having 1 to 10 carbon atoms; A straight chain alkoxy group having 1 to 5 carbon atoms; A branched or cyclic alkoxy group having 3 to 10 carbon atoms; Or it may be a branched chain or cyclic alkoxy group having 3 to 6 carbon atoms. More specifically, the alkoxy group having 1 to 10 carbon atoms includes a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, tert-butoxy group, n-pentoxy group, An iso-pentoxy group, a neo-pentoxy group, a cycloheptoxy group, and the like can be exemplified. The alkoxy group may be substituted or unsubstituted.

In the present specification, the alkoxycarbonyl group having 2 to 20 carbon atoms is a functional group in which an alkoxy group is bonded to one end of the carbonyl group, and the description of the alkoxy group described above may be applied. The alkoxycarbonyl group may be substituted or unsubstituted.

In the present specification, a multivalent functional group is a residue in which a plurality of hydrogen atoms bonded to an arbitrary compound has been removed, and examples thereof include a divalent functional group, a trivalent functional group, and a tetravalent functional group. For example, a tetravalent functional group derived from cyclobutane refers to a residue in which any 4 hydrogen atoms bonded to cyclobutane have been removed.

In the present specification, a direct bond or a single bond means that no atom or group of atoms exists at the corresponding position and is connected by a bonding line. Specifically, it refers to a case where no separate atom exists in the portion represented by _{L 1} or L _{2 in the formula.}

In this specification, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a commonly known analysis device, a detector such as a Refractive Index Detector, and a column for analysis may be used. Conditions, solvents, and flow rates can be applied. As a specific example of the measurement conditions, using a Polymer Laboratories PLgel MIX-B 300mm length column using a Waters PL-GPC220 instrument, the evaluation temperature is 160 ℃, 1,2,4-trichlorobenzene used as a solvent The flow rate was 1 mL/min, the sample was prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL, and the value of Mw can be calculated using a calibration curve formed using a polystyrene standard. The molecular weight of the polystyrene standard was 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000.

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

Ⅰ. Liquid crystal aligning agent composition

According to an embodiment of the present invention, at least one selected from the group consisting of a polyimide repeating unit represented by Formula 1, a polyamic acid ester repeating unit represented by Formula 2, and a polyamic acid repeating unit represented by Formula 3 (Co)polymers containing repeating units; And a liquid crystal aligning agent composition including the imidization catalyst compound represented by Formula 6 may be provided.

As the present inventors mix the imidation catalyst compound having a structure represented by Formula 6 with a polyimide (co)polymer, as in the liquid crystal aligning agent composition of the embodiment, the imidation catalyst compound is imid at room temperature. Thermal decomposition with sol is suppressed, so it has high solution stability in the liquid crystal alignment composition, and in the high-temperature liquid crystal alignment film manufacturing process, it is pyrolyzed with imidazole to produce a liquid crystal alignment film having excellent liquid crystal alignment characteristics through a high imidation rate. It was confirmed through an experiment that the additive can have an improved film strength by promoting curing, and the invention was completed.

In particular, a composite use of the imidation catalyst compound having the structure represented by Formula 6 as an imidization catalyst of a precursor such as polyamic acid or polyamic acid ester in a liquid crystal alignment agent, and at the same time applying as an epoxy curing agent when preparing a liquid crystal alignment layer And completed the invention.

On the other hand, when using an existing polyimide as a liquid crystal aligning film, a polyimide precursor, polyamic acid or polyamic acid ester having excellent solubility is applied and dried to form a coating film, and then converted into polyimide through a high-temperature heat treatment process. Light irradiation was performed to perform orientation treatment. However, in order to obtain sufficient liquid crystal alignment by irradiating the polyimide film with light, a lot of light irradiation energy is required, and an additional heat treatment process is also performed to secure alignment stability after light irradiation. Since such a lot of light irradiation energy and additional high-temperature heat treatment process are very disadvantageous in terms of process cost and process time, there is a limit to apply to actual mass production processes.

Accordingly, the inventors of the present invention determined that through an experiment, since the polymer contained in the liquid crystal alignment agent composition contains the imide functional group represented by Chemical Formula 4, the anisotropy was generated by irradiating light immediately without a heat treatment process after forming the coating film, and then heat treatment. Since it was possible to complete the alignment layer by proceeding, it was confirmed that not only the light irradiation energy could be greatly reduced, but also the alignment and stability were excellent, and the liquid crystal alignment layer having excellent voltage retention and electrical properties could be manufactured.

In addition, it was confirmed that the use of a polymer for liquid crystal aligning agent containing a functional group containing a nitrogen atom represented by Chemical Formula 5 can have a high voltage retention at high temperature and improve the reduction of the contrast ratio and the afterimage phenomenon, and the invention was completed. I did.

(1) (co)polymer

The (co)polymer may include at least one selected from the group consisting of a polyamic acid repeating unit, a polyamic acid ester repeating unit, and a polyimide repeating unit. That is, the (co)polymer is a polymer composed of one polyamic acid repeating unit, a polymer composed of one polyamic acid ester repeating unit, a polymer composed of one polyimide repeating unit, or a mixture of two or more repeating units thereof. It may contain a copolymer.

At least one repeating unit selected from the group consisting of the polyamic acid repeating unit, the polyamic acid ester repeating unit, and the polyimide repeating unit may form the main chain of the (co)polymer.

Specifically, the polyimide repeating unit includes the repeating unit represented by Formula 1, the polyamic acid ester repeating unit includes the repeating unit represented by Formula 2, and the polyamic acid repeating unit is represented by Formula 3 It may contain a repeating unit.

In Formulas 1 to 3, X ₁ to X ₃ may be the same as or different from each other, and may each independently be a tetravalent functional group. The X ₁ to X ₃ may be a functional group derived from a polyamic acid, a polyamic acid ester, or a tetracarboxylic acid dianhydride compound used in synthesizing a polyimide.

More specifically, X ₁ to X ₃ may each independently be one of a tetravalent functional group represented by Formula 8 below.

[Formula 8]

In Formula 8, R ₉ to R ₁₄ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, and L ₃ is a single bond, -O-, -CO-, -COO-, -S-, -SO-, -SO ₂ -, -CR ₁₅ R ₁₆ -, -(CH ₂ ) _t -, -O(CH ₂ ) _t O-, -COO(CH ₂ ) _t OCO-, -CONH-, phenylene or a combination thereof It is any one selected from the group consisting of, wherein R ₁₅ and R ₁₆ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a haloalkyl group, and t is an integer of 1 to 10.

More preferably, the X ₁ to X ₃ are each independently a functional group of the following formula 8-1 derived from 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, cyclobutane-1 , From an organic group of the following formula 8-2 derived from 2,3,4-tetracarboxylic dianhydride, tetrahydro-[3,3'-bifuran]-2,2',5,5'-tetraone It may be an organic group derived from the following Formula 8-3.

[Chemical Formula 8-1]

[Formula 8-2]

[Chemical Formula 8-3]

Meanwhile, in Formulas 1 to 3, Y ₁ to Y ₃ may be the same as or different from each other, and each independently may be one of a divalent functional group represented by Formula 4 below or a divalent functional group represented by Formula 5 below. The Y ₁ to Y ₃ may be a functional group derived from a polyamic acid, a polyamic acid ester, or a diamine compound used in synthesizing a polyimide.

As a specific example, Y ₁ to Y ₃ may be a divalent functional group represented by Formula 4 below.

[Formula 4]

In Formula 4, T is a tetravalent functional group, and L ₁ and L ₂ are each independently a divalent functional group. Specifically, in Formula 4, T may be one of the tetravalent functional groups represented by Formula 8. In addition, L ₁ and L ₂ are each independently an alkylene group having 1 to 20 carbon atoms, a heteroalkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or an arylene group having 2 to 20 carbon atoms. It may be one of the heteroarylene groups.

More specifically, in Formula 4, T may be a functional group represented by the following Formula 4-1, or a functional group represented by the following Formula 4-2.

[Formula 4-1]

[Formula 4-2]

L ₁ and L ₂ may each independently be a phenylene group.

More specifically, the example of the organic group represented by Formula 4 is not greatly limited, but may be, for example, a functional group represented by the following Formula 4-3 or a functional group represented by the following Formula 4-4.

[Formula 4-3]

[Formula 4-4]

In the case where Y ₁ to Y ₃ are divalent functional groups represented by Formula 4, the (co)polymer is synthesized from diamines containing imide repeating units already imidized. Since the anisotropy is generated by irradiating light and the alignment layer can be completed by performing heat treatment afterwards, 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. In addition, it is possible to manufacture a liquid crystal alignment layer excellent in voltage retention and electrical properties.

In addition, Y ₁ to Y ₃ may be a divalent functional group represented by the following formula (5).

[Formula 5]

In Formula 5, _{at least one of Q 1} to Q ₈ is nitrogen, the rest is carbon, D is -NR'-, and R'is hydrogen or an alkyl group having 1 to 6 carbon atoms.

Specifically, in the functional group represented by Chemical Formula 5, _{at least one of Q 1} to Q ₄ is nitrogen, the rest is carbon, Q ₅ to Q ₈ are carbon, and D may be -NR'-. More preferably, in Formula 5, one of Q ₂ and Q ₄ is nitrogen, the rest is carbon, Q ₁ and Q ₃ are carbon, Q ₅ to Q ₈ are carbon, and D is -NH- The functional groups represented by the following formula 5-1 can be mentioned.

[Chemical Formula 5-1]

More specific examples of the functional group represented by Chemical Formula 5-1 include functional groups represented by Chemical Formulas 5-a to 5-c below.

[Formula 5-a]

[Formula 5-b]

[Formula 5-c]

Meanwhile, in Formula 5, _{at least one of Q 1} to Q ₄ is nitrogen and the rest satisfy carbon, so that the nitrogen atom forms an asymmetric structure that is not symmetrical with respect to the center point or the center line. I can. Formula 5 is a repeating unit derived from a diamine having a specific structure containing a nitrogen atom, which is a precursor used to form a polymer for a liquid crystal aligning agent, and appears to be due to the use of an asymmetric diamine as described below.

The functional group represented by Formula 5 has a structural characteristic in which two aromatic ring compounds, preferably a heteroaromatic ring compound and an aromatic ring compound, are bonded through a secondary amine group or a tertiary amine group. Accordingly, the alignment property and the afterimage characteristics as a liquid crystal aligning agent satisfy the same level or higher, and the voltage retention rate is improved, thereby realizing excellent electrical characteristics.

On the other hand, when two aromatic cyclic compounds are bonded by a single bond without a secondary amine group or a tertiary amine group, the alignment characteristics of the liquid crystal aligning agent are poor, and a technical problem of remarkably decreasing the voltage retention may occur.

In addition, when each of the two aromatic cyclic compounds bonded through a secondary amine group or a tertiary amine group does not contain a nitrogen atom, an imidation reaction is performed with respect to a polyamic acid or polyamic acid ester formed by the reaction of an amine and an acid anhydride. Even if it proceeds, there is a limit in that the imidation rate in the final liquid crystal alignment layer decreases as the imidation reaction cannot be sufficiently performed (eg, through heat treatment at 230° C.).

In addition, the functional group represented by Formula 5 is characterized in that only an amine group and hydrogen are bonded to two aromatic ring compounds, preferably a heteroaromatic ring compound and an aromatic ring compound, and no other substituents are introduced. In addition, when a substituent, for example, a fluoroalkyl group is introduced into the heteroaromatic ring compound or the aromatic ring compound, the alignment characteristics of the liquid crystal aligning agent are poor, and a technical problem of remarkably decreasing the voltage retention may occur.

As described above, since the functional group represented by Chemical Formula 5 is included, the liquid crystal display device to which the (co)polymer for a liquid crystal aligning agent of the embodiment is applied can achieve high voltage retention and liquid crystal alignment.

In addition, in Formulas 1 to 3, _{at least one of R 1} and R ₂ may be an alkyl group having 1 to 10 carbon atoms, and the rest may be hydrogen.

(2) Imidation catalyst compound

In addition to the above-described (co)polymer, the liquid crystal aligning agent composition of the embodiment may include an imidation catalyst compound, and the imidation catalyst compound may have a specific chemical structure represented by Formula 6. The physical/chemical properties of the imidation catalyst compound appear to be due to the specific structure of Formula 6 described above.

Specifically, the imidation catalyst compound represented by Formula 6 can be synthesized through Michael addition reaction reaction between an imidazole compound and a compound containing an α,β-unsaturated carbonyl group, and is stable in a liquid crystal aligning composition at room temperature. However, at a high temperature of 120° C. or higher, it may be decomposed into an imidazole compound and a compound containing an α,β-unsaturated carbonyl group by a retro-Michael addition reaction.

The imidazole compound obtained by the retro-Michael addition reaction can act as a strong imidization catalyst. In addition, the imidazole compound may also function as a curing agent for an epoxy additive to be described later.

Using these features, the present inventors improved the solution stability of the liquid crystal aligning agent composition at room temperature by including the imidation catalyst compound represented by Formula 6 in the liquid crystal aligning agent composition. In addition, in the process of forming a liquid crystal alignment layer in which the liquid crystal aligning agent composition is heat-treated at a high temperature of 120° C. or higher, the imidation catalyst compound represented by Formula 6 is decomposed into an imidazole compound to induce an imidation reaction through the catalytic action of the imidazole compound. I can. As described above, the imidazole compound acting as an imidation catalyst can contribute to the improvement of the film strength by inducing curing of the liquid crystal alignment film together with the catalytic action.

Specifically, in Formula 6, R ₃ is one of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, or R ₄ Or it may be directly bonded to _{R 5 to form a ring structure.}

More preferably, in Formula 6, R ₃ may be an alkoxy group having 1 to 10 carbon atoms, and examples of the alkoxy group having 1 to 10 carbon atoms include an ethoxy group, an isobutoxy group, and a normal butoxy group.

In addition, in Formula 6, R ₄ to R ₈ are each independently a monovalent functional group. Specifically, in Formula 6, R ₄ to R ₈ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkoxycarbo having 2 to 20 carbon atoms It may be one of an yl group or an aryl group having 6 to 20 carbon atoms.

More preferably, in Formula 6, R ₄ may be an alkoxycarbonyl group having 2 to 20 carbon atoms. Examples of the alkoxycarbonyl group having 2 to 20 carbon atoms include an ethoxycarbonyl group, an isobutoxycarbonyl group, and a normal butoxycarbonyl group. In addition, in Formula 6, R ₅ to R ₈ may each independently be one of hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

More preferably, the imidation catalyst compound represented by Formula 6 may include a compound represented by Formula 6-1 to Formula 6-4.

[Chemical Formula 6-1]

[Chemical Formula 6-2]

[Chemical Formula 6-3]

[Chemical Formula 6-4]

The imidation catalyst compound represented by Formula 1 may be contained in an amount of 0.1% to 20% by weight based on the total weight of the liquid crystal aligning agent composition.

The imidation catalyst compound represented by Formula 6 may be decomposed into an imidization catalyst compound represented by Formula 7 below at a temperature of 120° C. or higher.

[Formula 7]

In Formula 7, R ₆ to R ₈ are each independently a monovalent functional group. The contents of R ₆ to R ₈ in Chemical Formula 7 are as described above in Chemical Formula 6.

More specifically, the retro-Michael addition reaction in which the imidation catalyst compound represented by Formula 6 is decomposed into the imidization catalyst compound represented by Formula 7 at a temperature of 120° C. or higher is due to the mechanism of Reaction Formula 1 below.

[Scheme 1]

(3) Liquid crystal alignment agent composition

The liquid crystal alignment agent composition of the embodiment is one selected from the group consisting of a polyimide repeating unit represented by Formula 1, a polyamic acid ester repeating unit represented by Formula 2, and a polyamic acid repeating unit represented by Formula 3 (Co)polymer containing more than one repeating unit; And a compound having two or more epoxy groups in a molecule in addition to the imidation catalyst compound represented by Formula 6 above.

The present invention makes it possible to exhibit a high voltage retention of a liquid crystal aligning film prepared therefrom by including a compound having two or more epoxy groups in the molecule in the liquid crystal aligning agent composition.

The molecular weight of the compound having two or more epoxy groups in the molecule is preferably 100 g/mol to 10,000 g/mol. As a compound having two or more epoxy groups in the molecule, cycloaliphatic epoxy, bisphenol epoxy, or novolac epoxy may be used. Such specific examples include (3',4'-epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate, 4,4'-methylenebis(N,N'-diglycidylaniline), or 2 ,2'-(3,3',5,5'-tetramethylbiphenyl-4,4'-diyl)bis(oxy)bis(methylene)dioxirane can be used.

In addition, the compound having two or more epoxy groups in the molecule may be contained in an amount of 0.1% to 20% by weight based on the total weight of the liquid crystal aligning agent composition.

Meanwhile, the liquid crystal aligning agent composition of the embodiment may include a compound having two or more epoxy groups in a molecule and an imidization catalyst compound represented by Formula 6 at the same time. Accordingly, the liquid crystal aligning agent composition is heated to a high temperature of 120° C. or higher. In the process of forming a liquid crystal alignment layer subjected to heat treatment, the imidation catalyst compound represented by Formula 6 may be decomposed into an imidazole compound to induce an imidation reaction through a catalytic action of the imidazole compound. By inducing curing of the compound having an epoxy group, it may contribute to improving the film strength.

Specifically, with respect to 100 parts by weight of the compound having two or more epoxy groups in the molecule, the content of the additive compound represented by Formula 1 may be mixed in a ratio of 10 parts by weight to 50 parts by weight.

The liquid crystal alignment agent composition may have a viscosity change rate of 10% or less, or 1% to 10%, or 1% to 6%, represented by the following equation.

[Equation]

Viscosity change rate (%) = (Viscosity of the liquid crystal aligning composition after storage at room temperature for 30 days-viscosity of the first liquid crystal aligning composition) / viscosity of the first liquid crystal aligning composition * 100.

The example of the method of measuring the viscosity is not limited, but may be measured using, for example, a capillary viscometer (SI analytics, 525-20 model) at a temperature of 25°C.

Ⅱ. Method for producing a liquid crystal alignment film

In addition, the present invention comprises the steps of forming a coating film by applying the liquid crystal aligning agent composition of the embodiment to a substrate (step 1); Drying the coating film (step 2); Performing alignment treatment by irradiating light or rubbing treatment on the coating film (step 3); And it provides a method of manufacturing a liquid crystal alignment film comprising the step (step 4) of curing the alignment-treated coating film by heat treatment.

Step 1 is a step of forming a coating film by applying the above-described liquid crystal aligning agent composition to a substrate. The contents of the liquid crystal aligning agent composition include all the contents described above in the embodiment.

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

In addition, the liquid crystal aligning agent composition 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-ethylpyrroli Don, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-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 Ether, 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 mentioned. These may be used alone or may be used in combination.

In addition, the liquid crystal aligning agent composition may further include other components in addition to the organic solvent. As a non-limiting example, when the liquid crystal aligning composition is applied, the uniformity of the film thickness or surface smoothness is improved, 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 density of the liquid crystal alignment layer may be additionally included. Examples of such additives include various solvents, surfactants, silane compounds, dielectrics or crosslinkable compounds.

Step 2 is a step of drying a coating film formed by applying the liquid crystal aligning composition to a substrate.

The drying step of the coating film may be performed by a heating means such as a hot plate, a hot air circulation furnace, or an infrared furnace, and may be performed at a temperature of 50°C to 150°C, or 50°C to 100°C.

Step 3 is a step of performing alignment treatment by irradiating light to the coating film.

The coating film in the alignment treatment step may mean a coating film immediately after the drying step, or may be a coating film after heat treatment after the drying step. The "coating film immediately after the drying step" refers to light irradiation immediately after the drying step without proceeding with a step of heat treatment at a temperature higher than the drying step, and other steps other than the heat treatment may be added.

More specifically, in the case of manufacturing a liquid crystal aligning film using a liquid crystal aligning agent containing a polyamic acid or a polyamic acid ester, the step of irradiating light after essentially performing a high-temperature heat treatment for imidization of the polyamic acid is performed. However, in the case of manufacturing a liquid crystal alignment layer using the liquid crystal aligning agent of the above-described embodiment, the heat treatment step is not included, and the alignment layer is immediately irradiated with light to perform alignment treatment, and then heat-treat and cure the alignment-treated coating layer. Can be manufactured.

In the step of performing the alignment treatment, the light irradiation may be irradiation of polarized ultraviolet rays having a wavelength of 150 nm to 450 nm. At this time, the intensity of exposure varies depending on the type of (co)polymer for the liquid crystal aligning agent, and an energy of 10 mJ/cm 2 to 10 J/cm 2, preferably 30 mJ/cm 2 to 2 J/cm 2 can be irradiated. have.

As the ultraviolet light, 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. Orientation treatment is performed by irradiating a selected polarized ultraviolet ray from among polarized ultraviolet rays by passing through or reflecting a Brewster polarizing device by reflection. At this time, the polarized ultraviolet rays may be irradiated perpendicularly to the substrate surface, or may be irradiated by tilting the incident angle at a specific angle. By this method, the alignment ability of liquid crystal molecules is imparted to the coating film.

In addition, in the step of performing the orientation treatment, a method of using a rubbing cloth may be used for the rubbing treatment. More specifically, in the rubbing treatment, the surface of the coating film after the heat treatment step may be rubbed in one direction while rotating the rubbing roller in which the cloth of rubbing cloth is attached to the metal roller.

Step 4 is a step of curing the orientation-treated coating film by heat treatment. In this case, the heat treatment may be performed by a heating means such as a hot plate, a hot air circulation furnace, or an infrared furnace, and may be performed at a temperature of 100°C to 300°C, or 120°C to 250°C.

In the step of heat-treating and curing the alignment-treated coating film, an imidization catalyst compound represented by Formula 7 below may be included in the alignment-treated coating layer.

[Formula 7]

In Formula 7, R ₆ to R ₈ are each independently a monovalent functional group. The content of R ₆ to R ₈ in Formula 7 is as described above in Formula 6 of the embodiment.

In general, it is known that when an epoxy material is included in the liquid crystal aligning agent, the strength and high voltage retention of the alignment layer are improved, and it is known that the higher the content of the epoxy material, the higher the degree. However, as the content of the epoxy material increases, there is a problem in that the high-temperature AC luminance fluctuation rate of the liquid crystal cell increases. The reason why the high-temperature AC luminance fluctuation characteristics deteriorate is not limited in theory, but is due to the fact that the alignment of the liquid crystal aligning agent and the epoxy reaction proceed simultaneously because the alignment of the liquid crystal aligning agent proceeds at a high temperature.

Accordingly, the liquid crystal aligning agent composition is applied to a substrate and dried to form a coating film, and then, linearly polarized light is irradiated to induce initial anisotropy, and then a part of the alignment film is reorientated through low-temperature heat treatment and the decomposition product is stabilized. Subsequently, by performing high-temperature heat treatment at a higher temperature than the low-temperature heat treatment, it is possible to achieve imidization and at the same time stabilize orientation by an epoxy reaction. Accordingly, there is an advantage in that the initial anisotropy proceeds without an epoxy reaction, so that the content of the epoxy material can be increased while the orientation is effectively achieved.

The liquid crystal alignment layer manufactured according to the manufacturing method of the liquid crystal alignment layer as described above not only exhibits excellent alignment characteristics, but also has excellent high-temperature AC luminance fluctuation rates, and can maintain a high voltage retention rate for a long time.

The step of heat-treating and curing the alignment-treated coating film is a step performed after light irradiation in the method of manufacturing a liquid crystal aligning film using a polymer for a liquid crystal aligning agent containing a polyamic acid or a polyamic acid ester. It is distinguished from the heat treatment step performed to imidize the liquid crystal aligning agent composition while applying the composition to a substrate and irradiating light before or while irradiating light.

In addition, during the heat treatment, the epoxy reaction of the compound having two or more epoxy groups in the molecule proceeds, so that orientation stabilization may be improved. Therefore, the heat treatment temperature is a temperature at which the imidization of the polymer for liquid crystal aligning agent and the epoxy reaction of the compound having two or more epoxy groups in the molecule proceeds, and is preferably performed at 200°C to 250°C, or 210°C to 240°C. . At this time, the heat treatment means is not particularly limited, and may be performed by a heating means such as a hot plate, a hot air circulation furnace, or an infrared furnace.

Meanwhile, after the step of drying the coating film (step 2), if necessary, a step of heat-treating the coating film immediately after the drying step at a temperature equal to or higher than the drying step may be further included. The heat treatment may be performed by a heating means such as a hot plate, a hot air circulation furnace, or an infrared furnace, and is preferably performed at 150°C to 250°C. In this process, the liquid crystal aligning agent can be imidized.

Ⅲ. Liquid crystal alignment film

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

Although the thickness of the liquid crystal aligning layer is not largely limited, for example, it can be freely adjusted within the range of 0.01 µm to 1000 µm. When the thickness of the liquid crystal alignment layer increases or decreases by a specific value, physical properties measured in the liquid crystal alignment layer may also change by a predetermined value.

Specifically, the liquid crystal alignment layer may have a film strength of 0.2% or less, or 0.01% to 0.2%, or 0.1% to 0.2%, calculated by Equation 1 below.

[Equation 1]

Film strength = Haze of the liquid crystal alignment layer after rubbing treatment-Haze of the liquid crystal alignment layer before rubbing treatment.

The rubbing treatment for the liquid crystal alignment layer may be performed by rubbing the surface of the alignment layer while rotating at 1000 rpm using a rubbing machine manufactured by Sindo Engineering, and the haze value may be measured using a hazemeter.

IV. Liquid crystal display element

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

The liquid crystal alignment layer may be introduced into a liquid crystal cell by a known method, and the liquid crystal cell may likewise be introduced into a liquid crystal display device by a known method. The liquid crystal alignment layer is prepared from the liquid crystal alignment agent composition of the embodiment, and thus excellent stability can be realized along with excellent general properties. Accordingly, a liquid crystal display device capable of exhibiting high reliability is provided.

The liquid crystal display device has a voltage retention rate of 79% or more, or 79% to 99%, or 79% to 95%, or 79% to 90%, measured using the 6254C equipment of TOYO corporation at a temperature of 1V, 1Hz, and 60°C. , Or 85% to 90%. If the voltage retention rate measured using the 6254C equipment of TOYO corporation at 1V, 1Hz, and 60 ℃ temperature of the liquid crystal alignment display device decreases to less than 79%, it is difficult to implement a liquid crystal display device having high-quality driving characteristics at low power. I can lose.

According to the present invention, a liquid crystal aligning agent composition capable of producing a liquid crystal aligning film having excellent storage stability, securing a high imidation rate, and having improved film strength along with liquid crystal alignment characteristics, and a method for producing a liquid crystal aligning film using the same, And a liquid crystal alignment layer and a liquid crystal display device using the same may be provided.

The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Production Example: Preparation of diamine>

Preparation Example 1: Preparation of diamine DA1-1

A mixture was prepared by dissolving DMCBDA (1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid dianhydride) and 4-nitroaniline in DMF (Dimethylformamide). Then, the mixture was reacted at about 80° C. for about 12 hours to prepare amic acid. Thereafter, the amic acid was dissolved in DMF, and acetic anhydride and sodium acetate were added to prepare a mixture. Subsequently, the amic acid contained in the mixture was imidized at about 90° C. for about 4 hours. After dissolving the obtained imide in DMAc (Dimethylacetamide), Pd/C was added to prepare a mixture. The diamine (DA1-1) of Preparation Example 1 was prepared by reducing this for 20 minutes under a hydrogen pressure of 45° C. and 6 bar.

Preparation Example 2: Preparation of diamine DA1-2

The above except that CBDA (cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride) was used instead of DMCBDA (1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid dianhydride). Diamine (DA1-2) of Preparation Example 2 having the above structure was prepared in the same manner as in Preparation Example 1.

Preparation Example 3: Synthesis of diamine DA2-1

18.3 g (100 mmol) of 2-Chloro-5-nitropyridine (compound 4), 12.5 g (98.6 mmol) of paraphenylenediamine (p-PDA, compound 5) were completely dissolved in about 200 mL of dimethylsulfoxide (DMSO). Then, 23.4 g (200 mmol) of triethylamine (TEA) was added and stirred at room temperature for about 12 hours. When the reaction was completed, the reaction was put into a container containing about 500 mL of water and stirred for about 1 hour. The solid obtained by filtration was washed with about 200 mL of water and about 200 mL of ethanol to synthesize 16 g (61.3 mmol) of compound 6 (yield: 60%).

After dissolving the compound 6 in about 200 mL of a 1:1 mixture of ethyl acetate (EA) and THF, 0.8 g of palladium (Pd)/carbon (C) was added, and about 12 hours under a hydrogen environment. While stirring. After the reaction was completed, the filtrate filtered through a Celite pad was concentrated to prepare 11 g of diamine DA2-1 (yield: 89%).

Preparation Example 4: Synthesis of diamine DA2-2

Diamine DA2-2 of Preparation Example 4 was prepared in the same manner as in Preparation Example 3, except that metaphenylenediamine (m-PDA, Compound 7) was used instead of the paraphenylenediamine (p-PDA, compound 5). Was prepared.

Preparation Example 5: Synthesis of diamine DA2-3

Except for using 2-chloro-4-nitropyridine (2-chloro-4-nitropyridine, compound 8) in place of the 2-chloro-5-nitropyridine (2-chloro-5-nitropyridine, compound 4), the above Diamine DA2-3 of Preparation Example 5 was prepared in the same manner as in Preparation Example 3.

<Synthesis Examples 1 to 3>

Synthesis Example 1: Preparation of polymer P-1 for liquid crystal aligning agent

5.376 g (13.3 mmol) of the diamine (DA1-1) of Preparation Example 1 was completely dissolved in 74.66 g of anhydrous N-methyl pyrrolidone (NMP). Then, 2.92 g (13.03 mmol) of 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (DMCBDA) was added under an ice bath, followed by stirring at room temperature for about 16 hours.

The solution was added to an excess of distilled water to generate a precipitate. Subsequently, the generated precipitate was filtered, washed twice with distilled water, and washed three times with methanol again. The thus obtained solid product was dried in a reduced pressure oven at 40° C. for 24 hours to obtain a polyamic acid polymer P-1 for a liquid crystal aligning agent.

Synthesis Example 2: Preparation of polymer P-2 for liquid crystal aligning agent

5.0 g (13.3 mmol) of DA1-2 prepared in Preparation Example 2 was completely dissolved in 71.27 g of anhydrous N-methyl pyrrolidone (NMP). Then, 2.92 g (13.03 mmol) of 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (DMCBDA) was added to the solution under an ice bath, followed by stirring at room temperature for about 16 hours.

The solution was added to an excess of distilled water to generate a precipitate. Subsequently, the generated precipitate was filtered, washed twice with distilled water, and washed three times with methanol again. The thus obtained solid product was dried in a reduced pressure oven at 40° C. for 24 hours to obtain a polyamic acid polymer P-2 for a liquid crystal aligning agent.

Synthesis Example 3: Preparation of polymer P-3 for liquid crystal aligning agent

21.735 g (0.109 mol) of diamine DA2-1 prepared in Preparation Example 3 was completely dissolved in 236.501 g of anhydrous N-methyl pyrrolidone (NMP). And, in an ice bath, tetrahydro-[3,3'-bifuran]-2,2',5,5'-tetrahydro-[3,3'-bifuran]-2,2',5,5 '-tetraone, BT100) 20.0 g (0.101 mol) was added to the solution and stirred at room temperature for about 16 hours.

The solution was added to an excess of distilled water to generate a precipitate. Subsequently, the generated precipitate was filtered, washed twice with distilled water, and washed three times with methanol again. The thus obtained solid product was dried in a reduced pressure oven at 40° C. for 24 hours to obtain a polyamic acid polymer P-3 for a liquid crystal aligning agent.

<Example: Preparation of a liquid crystal aligning agent composition and a liquid crystal aligning film>

Example 1

(1) Preparation of liquid crystal aligning agent composition

10 g of the polyamic acid polymer (P-1) for a liquid crystal aligning agent obtained in Synthesis Example 1, diethyl 2-(2-ethyl-4-methyl-1H-imidazole-1- represented by the following formula (a) as an imidation catalyst 1) Succinate (diethyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl) succinate) 0.01 g, and 4,4′'-methylenebis (N,N-diglycidylaniline) 0.03 g of (4,4′-Methylenebis(N,N-diglycidylaniline)) was dissolved in a mixed solvent of 3.58 g of NMP, 10 g of GBL, and 5.79 g of 2-butoxyethanol to obtain a 3.5 wt% solution. Then, a liquid crystal aligning agent composition was prepared by pressure-filtering with a filter made of poly(tetrafluoreneethylene) having a pore size of 0.1 μm.

[Formula a]

(2) Preparation of liquid crystal alignment film

The liquid crystal aligning agent composition obtained in (1) of Example 1 was coated on a square glass substrate having an ITO electrode patterned and having a size of 2.5 cm x 2.7 cm by spin coating. Subsequently, the substrate to which the liquid crystal aligning agent composition was applied was placed on a hot plate at 80° C. and dried for 2 minutes. Thereafter, an orientation treatment was performed by irradiating ultraviolet rays of 254 nm at an exposure amount of 0.25 J/cm 2 using a linear polarizer self-attached exposure machine. Subsequently, the coating film was fired (cured) in an oven at about 230° C. for 20 minutes to prepare a liquid crystal alignment film having a thickness of 0.1 μm.

(3) Preparation of liquid crystal alignment cell

A sealing agent impregnated with a 4.5 μm-sized ball spacer was applied to the edge of the upper plate excluding the liquid crystal injection hole. In addition, after aligning the liquid crystal alignment layers formed on the upper plate and the lower plate to face each other and align the alignment directions parallel to each other, the upper and lower plates were bonded and the sealing agent was UV-cured and thermally cured to prepare an empty cell. Then, a liquid crystal was injected into the empty cell, and the injection port was sealed with a sealing agent to prepare a liquid crystal alignment cell.

Example 2

As an imidation catalyst, diisobutyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate [diisobutyl 2-(2-ethyl-4-) represented by the following formula (b) instead of the formula (a) A liquid crystal aligning agent composition, a liquid crystal alignment layer, and a liquid crystal alignment cell were prepared in the same manner as in Example 1, except that methyl-1H-imidazol-1-yl)succinate] was added.

[Formula b]

Example 3

Dibutyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl) succinate represented by the following formula c instead of the formula a as an imidation catalyst [dibutyl 2-(2-ethyl-4-methyl -1H-imidazol-1-yl)succinate] was added to prepare a liquid crystal aligning agent composition, a liquid crystal alignment layer, and a liquid crystal alignment cell in the same manner as in Example 1 above.

[Formula c]

Example 4

Dibutyl 2-(2-phenyl-1H-imidazol-1-yl) succinate represented by the following formula d instead of the formula a as an imidation catalyst [dibutyl 2-(2-phenyl-1H-imidazol-1-yl) ) succinate] was added to prepare a liquid crystal aligning agent composition, a liquid crystal alignment film, and a liquid crystal alignment cell in the same manner as in Example 1 above.

[Formula d]

Example 5

Liquid crystal in the same manner as in Example 1, except that the polyamic acid polymer (P-2) for the liquid crystal aligning agent obtained in Synthesis Example 2 was used instead of the polyamic acid polymer (P-1) for the liquid crystal aligning agent obtained in Synthesis Example 1. An alignment agent composition, a liquid crystal alignment film, and a liquid crystal alignment cell were prepared.

Example 6

Liquid crystal in the same manner as in Example 1, except that the polyamic acid polymer (P-3) for the liquid crystal aligning agent obtained in Synthesis Example 3 was used instead of the polyamic acid polymer (P-1) for the liquid crystal aligning agent obtained in Synthesis Example 1. An alignment agent composition, a liquid crystal alignment film, and a liquid crystal alignment cell were prepared.

<Comparative Example: Preparation of a liquid crystal aligning agent composition and a liquid crystal aligning film>

Comparative Example 1

A liquid crystal aligning agent in the same manner as in Example 1, except that diethyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate represented by Formula a was not added as an imidation catalyst. A composition, a liquid crystal alignment film, and a liquid crystal alignment cell were prepared.

Comparative Example 2

The same method as in Example 1, except that imidazole was used instead of diethyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate represented by Formula a as the imidation catalyst. As a result, a liquid crystal aligning agent composition, a liquid crystal alignment film, and a liquid crystal alignment cell were prepared.

Comparative Example 3

The above except that 1-methylimidazole was used instead of diethyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate represented by Formula a as the imidation catalyst. A liquid crystal aligning agent composition, a liquid crystal alignment film, and a liquid crystal alignment cell were prepared in the same manner as in Example 1.

<Experimental Example: Measurement of physical properties of the liquid crystal aligning agent composition and the liquid crystal aligning film obtained in Examples and Comparative Examples>

The physical properties of the liquid crystal aligning agent composition obtained in the above Examples and Comparative Examples, or the liquid crystal aligning film, and the liquid crystal aligning cell prepared using the same, were measured by the following method, and the results are shown in Table 1.

1. Imidation conversion rate (%)

With respect to the liquid crystal aligning film obtained from the liquid crystal aligning agent compositions of Examples and Comparative Examples, the FT-IR spectrum was measured by the ATR method, and the ratio of the imide structure in the (co)polymer molecule contained in the alignment film was measured.

2. Evaluation of liquid crystal orientation characteristics

Polarizing plates were attached to the upper and lower plates of the prepared liquid crystal delivery cell so as to be perpendicular to each other. Then, a liquid crystal alignment cell with a polarizing plate was placed on a backlight having a brightness of 7,000 cd/m2 and light leakage was observed with the naked eye. At this time, if the liquid crystals are well aligned because the alignment characteristics of the liquid crystal alignment layer are excellent, light does not pass through the polarizing plates vertically attached to each other and is observed darkly without defects. The orientation characteristic in this case was evaluated as'good', and when light leakage such as a liquid crystal flow trace or a bright spot was observed, it was evaluated as'defective', and the results are shown in Table 1 below.

3. Orientation film strength evaluation

For the alignment layer obtained from the liquid crystal aligning agent composition prepared in Examples and Comparative Examples, after rubbing the surface of the alignment layer while rotating at 850 rpm using a rubbing machine of Sindo Engineering, a haze value using a hazemeter Was measured, and the difference with the haze value before the rubbing treatment was calculated as shown in Equation 1 below to evaluate the film strength. If the haze change value is less than 1, the film strength is excellent.

[Equation 1]

Film strength (%) = Haze of the liquid crystal alignment layer after rubbing treatment (%)-Haze of the liquid crystal alignment layer before rubbing treatment (%).

4. Storage stability

For the liquid crystal aligning agent compositions of Example 1 and Comparative Example 4, the initial viscosity and the viscosity after storage at room temperature for 30 days were measured, respectively, and the viscosity change rate was measured by Equation 2 below. If the viscosity change during 30 days is less than 10%, the storage stability is excellent.

The viscosity of the liquid crystal aligning composition may be measured using a capillary viscometer (SI analytics, 525-20 model) at a temperature of 25°C.

[Equation 2]

Viscosity change rate (%) = (Viscosity of the liquid crystal aligning composition after storage at room temperature for 30 days-viscosity of the first liquid crystal aligning composition) / viscosity of the first liquid crystal aligning composition * 100.

5. Voltage holding ratio (VHR) measurement

The voltage maintenance rate (VHR), which is the electrical characteristic of the liquid crystal cell manufactured by the above method, was measured using Toyo's 6254 equipment. The voltage maintenance rate was measured under severe conditions of 1 V, 1 Hz, and 60°C.

Experimental Example Measurement Results of Examples and Comparative Examples division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Diamine Preparation Example 1 (DA1-1)
Manufacturing Example 1
(DA1-1)
Manufacturing Example 1
(DA1-1)
Manufacturing Example 1
(DA1-1)
Manufacturing Example 2
(DA1-2)

Manufacturing Example 3
(DA2-1)
Manufacturing Example 1
(DA1-1) Manufacturing Example 1
(DA1-1) Manufacturing Example 1
(DA1-1) polymer Synthesis Example 1 (P-1) Synthesis Example 1 (P-1) Synthesis Example 1 (P-1) Synthesis Example 1 (P-1) Synthesis Example 2 (P-2) Synthesis Example 3 (P-3) Synthesis Example 1 (P-1) Synthesis Example 1 (P-1) Synthesis Example 1 (P-1) Imidation catalyst Formula a compound Formula b compound Formula c compound Formula d compound Formula a compound Formula a compound - Imidazole 1-methylimidazole Epoxy additive 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) 4,4′-Methylenebis(N,N-diglycidylaniline) Imidation rate (%) 90 93 91 90 92 89 85 90 91 Orientation characteristics Good Good Good Good Good Good Bad Good Good Film strength (%) 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.2 0.2 Viscosity change (%) 4.8 5.0 5.3 5.0 5.5 5.1 4.7 Impossible to measure (sedimentation occurs) Impossible to measure (sedimentation occurs) Voltage retention rate (%) 82 81 79 80 81 90 81 78 77

* Formula a compound: diethyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate * Formula b compound: diisobutyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl )succinate

* Formula c compound: dibutyl 2-(2-ethyl-4-methyl-1H-imidazol-1-yl)succinate

* Formula d compound: dibutyl 2-(2-phenyl-1H-imidazol-1-yl)succinate

As shown in Table 1, in the case of the liquid crystal aligning agent compositions of Examples 1 to 6, by using a heavy imidation catalyst having a specific structure such as Chemical Formula a, Chemical Formula b, Chemical Formula c, and Chemical Formula d, the liquid crystal alignment composition As the viscosity change rate is low from 4.8% to 5.5%, stability is improved, the imidation rate in the final liquid crystal alignment layer is high from 89% to 93%, so that excellent liquid crystal alignment characteristics can be secured, and the voltage retention rate is 79% to 90% It was measured as high, and it was confirmed that excellent electrical properties can also be implemented.

In particular, as the liquid crystal aligning agent composition of Example 6 used the polymer (P-3) of Synthesis Example 3 synthesized from the diamine (DA2-1) of Preparation Example 3, the voltage retention was increased to 90%, resulting in a high level of It was confirmed that electrical characteristics can be implemented.

On the other hand, it was confirmed that the alignment film obtained from the liquid crystal aligning agent composition of Comparative Example 1 containing no catalyst had an imidation conversion ratio of 85%, and thus the liquid crystal alignment characteristics were inferior to those of the Examples.

In addition, when a catalyst having an imidazole functional group exposed as it is used as in Comparative Example 2 and Comparative Example 3, it was confirmed that the storage stability was significantly reduced due to precipitation due to gelation or the like in the liquid crystal aligning agent composition.

Claims (13)

A (co)polymer comprising at least one repeating unit selected from the group consisting of a polyimide repeating unit represented by the following formula (1), a polyamic acid ester repeating unit represented by the following formula (2), and a polyamic acid repeating unit represented by the following formula (3) ; And
A liquid crystal aligning agent composition comprising; an imidization catalyst compound represented by the following formula (6):
[Formula 1]

[Formula 2]

[Formula 3]

In Formulas 1 to 3,
At least one of R ₁ and R ₂ is an alkyl group having 1 to 10 carbon atoms, and the rest are hydrogen,
X ₁ to X ₃ are the same as or different from each other, and each independently a tetravalent functional group,
Y ₁ to Y ₃ are the same as or different from each other, and each independently is one of a divalent functional group represented by the following formula (4) or a divalent functional group represented by the following formula (5),
[Formula 4]

In Chemical Formula 4,
T is a tetravalent functional group,
L ₁ and L ₂ are each independently a divalent functional group,
[Formula 5]

In Formula 5, _{at least one of Q 1} to Q ₈ is nitrogen, the rest is carbon, D is -NR'-, R'is hydrogen or an alkyl group having 1 to 6 carbon atoms,
[Formula 6]

In Chemical Formula 6,
R ₃ is one of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,
R ₄ is an alkoxycarbonyl group having 2 to 20 carbon atoms,
R ₅ to R ₈ are each independently a monovalent functional group.
The method of claim 1,
The imidation catalyst compound represented by Formula 6 is decomposed into the imidization catalyst compound represented by Formula 7 below at a temperature of 120° C. or higher, a liquid crystal aligning agent composition:
[Formula 7]

In Chemical Formula 7,
R ₆ to R ₈ are each independently a monovalent functional group.
delete The method of claim 1,
The X ₁ to X ₃ are each independently one of the tetravalent functional groups represented by the following formula (8), a liquid crystal aligning agent composition:
[Formula 8]

In Formula 8, R ₉ to R ₁₄ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, and L ₃ is a single bond, -O-, -CO-, -COO-, -S-, -SO-, -SO ₂ -, -CR ₁₅ R ₁₆ -, -(CH ₂ ) _t -, -O(CH ₂ ) _t O-, -COO(CH ₂ )tOCO-, -CONH-, phenylene or a combination thereof It is any one selected from the group consisting of, wherein R ₁₅ and R ₁₆ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a halo alkyl group, and t is an integer of 1 to 10.
The method of claim 1,
A liquid crystal aligning agent composition further comprising a compound having two or more epoxy groups in a molecule.
The method of claim 5,
The content of the additive compound represented by Formula 1 is 10 parts by weight to 50 parts by weight, based on 100 parts by weight of the compound having two or more epoxy groups in the molecule.
The method of claim 1,
In Formula 4, T is a functional group represented by the following Formula 4-1, or a functional group represented by the following Formula 4-2:
[Formula 4-1]

[Formula 4-2]

.
The method of claim 1,
In Formula 5, _{at least one of Q 1} to Q ₄ is nitrogen, the rest is carbon, and Q ₅ to Q ₈ are carbon.
The method of claim 1,
Formula 5 is a liquid crystal aligning agent composition comprising a functional group represented by the following Formula 5-1:
[Chemical Formula 5-1]

.
Forming a coating film by applying the liquid crystal aligning agent composition of claim 1 to a substrate;
Drying the coating film;
Performing alignment treatment by irradiating light or rubbing the coating film; And
A method of manufacturing a liquid crystal alignment layer comprising the step of heat-treating and curing the alignment-treated coating layer.
The method of claim 10,
In the step of heat-treating and curing the alignment-treated coating film, an imidization catalyst compound represented by the following Formula 7 is included in the alignment-treated coating film:
[Formula 7]

In Chemical Formula 7,
R ₆ to R ₈ are each independently a monovalent functional group.
A liquid crystal aligning film containing an alignment cured product of the liquid crystal aligning agent composition of claim 1.
A liquid crystal display device comprising the liquid crystal alignment layer of claim 12.