TWI891825B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent includes a polymer (A), a solvent (B) and a compound (C). The polymer (A) is manufactured by reacting a tetracarboxylic acid dianhydride component (a1) with a diamine component (a2). The liquid crystal alignment film is formed form the liquid crystal alignment agent, and the liquid crystal display element including the liquid crystal alignment film has a low bright spot property due to frictions.

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element, and more particularly to a liquid crystal display element utilizing the liquid crystal alignment agent to produce a low-friction bright spot.

Liquid crystal display elements used in LCD televisions and monitors typically incorporate a liquid crystal alignment film (LCA) to control the alignment of the liquid crystals. Currently, the most common industrial method involves rubbing a fabric such as cotton, nylon, or polyester in one direction onto an electrode substrate. The film's surface is then coated with polyamide and/or its imidized form, a process known as rubbing.

During the alignment process of liquid crystal alignment films, rubbing the film surface is a relatively easy method to produce industrially. However, with the increasing demand for higher performance, higher precision, and larger LCD devices, problems such as damage to the alignment film surface, dust, the effects of mechanical and electrostatic forces, and unevenness across the treated surface during rubbing have become increasingly prominent.

As an alternative to rubbing treatment, photoalignment methods are currently known, which utilize polarized ultraviolet light irradiation to impart alignment properties to liquid crystals. These photoalignment methods include substances that utilize photoisomerization, photocrosslinking, or photodecomposition reactions. Furthermore, Japanese Patent Publication No. 9-297313 proposes a photoalignment method using a polyimide film with an alicyclic structure such as cyclobutane in its backbone. The application of polyimide as a photoalignment film is promising due to its higher heat resistance than other types of alignment films.

Optical alignment is a non-rubbing alignment method. It not only boasts the industrial advantage of simple manufacturing processes, but also promises to improve the contrast and viewing angle characteristics of liquid crystal displays using in-plane switching (IPS) and fringe field switching (FFS) drive methods, compared to those using rubbing methods. Therefore, optical alignment is a promising and highly sought-after liquid crystal alignment method.

However, when liquid crystal alignment films produced using the photoalignment method are used in liquid crystal display devices, particularly those with curved liquid crystal panels, the panels are bent along the exterior of the housing. This causes the spacers within the liquid crystal panel to move within the panel, rubbing against the liquid crystal alignment film. The liquid crystal alignment film, with pressure applied by the spacers, cannot regulate the alignment of the liquid crystals. For example, even when the liquid crystal panel displays black, light may leak through the edges of the spacers, appearing as bright spots and causing problems.

The present invention was developed in light of the above-mentioned circumstances, and aims to provide a liquid crystal display device having a liquid crystal panel that minimizes bright spots while still maintaining a curved shape even when physical friction, such as friction caused by spacers, occurs, and a liquid crystal aligner used therein.

One aspect of the present invention provides a liquid crystal alignment agent comprising a polymer (A), a solvent (B), and a compound (C). The liquid crystal alignment film produced using this liquid crystal alignment agent can enhance the low-friction bright spot characteristics of liquid crystal display devices.

Another aspect of the present invention is to provide a liquid crystal alignment film formed using the above-mentioned liquid crystal alignment agent.

Another aspect of the present invention is to provide a liquid crystal display device comprising the above-mentioned liquid crystal alignment film.

According to the above aspects of the present invention, a liquid crystal alignment agent is provided, and the liquid crystal alignment agent comprises a polymer (A), a solvent (B), and a compound (C), which is described below.

Polymer (A)

The polymer (A) of the present invention can be prepared by polymerization of a tetracarboxylic dianhydride component (a1) and a diamine component (a2).

Preferred examples of the polymer (A) are polyamic acid polymers, polyimide polymers, polyimide block copolymers, or combinations thereof. Preferred examples of polyimide block copolymers are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

Tetracarboxylic dianhydride component (a1)

Tetracarboxylic dianhydride compound (a1-1)

The tetracarboxylic dianhydride component (a) of the present invention comprises at least one tetracarboxylic dianhydride compound (a1-1) represented by the following formula (II):

In formula (II), _X1 to _X4 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group. _X1 to _X4 may be the same or different, and at least one of _X1 , _X2 , _X3 , and _X4 is not a hydrogen atom.

When X ₁ , X ₂ , X ₃ , and X ₄ have a steric hindrance structure, the resulting liquid crystal alignment agent will cause the resulting liquid crystal display device to have poor low-friction bright spot characteristics. Therefore, X ₁ , X ₂ , X ₃ , and X ₄ are preferably hydrogen atoms, methyl groups, or ethyl groups, with methyl groups being more preferred.

Specific examples of the tetracarboxylic dianhydride compound (a1-1) represented by formula (II) include compounds represented by formulas (II-1) to (II-8). Formula (II-1) is preferred for achieving low-friction bright spot properties.

The above-mentioned tetracarboxylic dianhydride compound (a1-1) can be used alone or in combination of two or more.

Based on 100 mol of the total amount of the tetracarboxylic dianhydride component (a1), the amount of the tetracarboxylic dianhydride compound (a1-1) used is 10 mol to 100 mol, preferably 15 mol to 90 mol, and more preferably 20 mol to 80 mol.

When the tetracarboxylic dianhydride component (a1) comprises a tetracarboxylic dianhydride compound (a1-1) represented by formula (II), the liquid crystal alignment film prepared using this liquid crystal alignment agent can further enhance the low-friction bright spot characteristics of liquid crystal display devices.

Other tetracarboxylic dianhydride compounds (a1-2)

The tetracarboxylic dianhydride component (a1) of the present invention may optionally contain other tetracarboxylic dianhydride compounds (a1-2). Preferred examples of other tetracarboxylic dianhydride compounds (a1-2) include (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds represented by the following formulas (V-1) to (V-6).

The (1) aliphatic tetracarboxylic dianhydride compound of the present invention includes but is not limited to aliphatic tetracarboxylic dianhydride compounds such as ethanetetracarboxylic dianhydride or butanetetracarboxylic dianhydride.

The (2) alicyclic tetracarboxylic acid dianhydride compound of the present invention includes but is not limited to 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,3-dichloro-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1, Alicyclic tetracarboxylic acid dianhydride compounds such as 2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic acid dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, or dicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride.

Specific examples of the aromatic tetracarboxylic dianhydride compound (3) of the present invention may include but are not limited to 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, benzene tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-di ... ,3'-4,4'-diphenylethane tetracarboxylic dianhydride, 3,3',4,4-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furan tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 2,3,3',4'-diphenyl Sulfide tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfide tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic acid dianhydride, 2,2',3,3'-diphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride anhydride, bis(phthalic acid)phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) dianhydride, m-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, ethylene glycol-bis(dehydrated trimellitate), propylene glycol-bis(dehydrated trimellitate), 1,4-butanediol-bis(dehydrated trimellitate), 1,6-hexanediol-bis( Dehydrated trimellitate), 1,8-octanediol-bis(dehydrated trimellitate), 2,2-bis(4-hydroxyphenyl)propane-bis(dehydrated trimellitate), 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-methyl-5- (Tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c ]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, Hydrogen-8-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 5-(2,5-dioxo-tetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, etc.

According to (4) of the present invention, the tetracarboxylic dianhydride compounds represented by formula (V-1) to formula (V-6) are described in detail as follows:

In formula (V-5), _N1 represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; _N2 and _N3 may be the same or different and may each represent a hydrogen atom or an alkyl group. Preferably, the tetracarboxylic dianhydride compound represented by formula (V-5) can be selected from the compounds represented by formulas (V-5-1) to (V-5-3) below.

In formula (V-6), _N4 represents a divalent group containing an aromatic ring; _N5 and _N6 may be the same or different and each represent a hydrogen atom or an alkyl group. Preferably, the tetracarboxylic dianhydride compound represented by formula (V-6) can be selected from the compounds represented by formula (V-6-1) below.

The above-mentioned other tetracarboxylic dianhydride compounds (a1-2) can be used alone or in combination of two or more.

Based on a total usage amount of 100 mol of the tetracarboxylic dianhydride component (a1), the usage amount of the other tetracarboxylic dianhydride compounds (a1-2) is 0 mol to 90 mol, preferably 20 mol to 80 mol, and more preferably 30 mol to 70 mol.

Based on a usage amount of 100 mol of the diamine component (a2), the usage amount of the tetracarboxylic dianhydride component (a1) ranges from 20 mol to 200 mol, and preferably from 30 mol to 120 mol.

Diamine component (a2)

Diamine compound (a2-1)

The diamine component (a2) of the present invention may include a diamine compound (a2-1) represented by the following formula (III).

In formula (III), _Y1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and _Y2 represents a linear alkyl group having 1 to 10 carbon atoms. When the diamine component (a2) comprises the diamine compound (a2-1) represented by formula (III), the resulting liquid crystal alignment film exhibits excellent liquid crystal alignment properties and alignment stability.

The aforementioned alkyl group having 1 to 4 carbon atoms may be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a sec-butyl group, or an isobutyl group. From the perspective of polymerization reactivity, a methyl group or an ethyl group is preferred, with a methyl group being more preferred.

The aforementioned linear alkylene group having 1 to 10 carbon atoms may be, for example, methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,7-heptylene, 1,8-octylene, 1,9-nonylene, or 1,10-decylene.

From the perspectives of liquid crystal alignment and alignment stability, as well as compound availability, the diamine represented by formula (III) is preferably at least one selected from the group consisting of diamines represented by formulas (III-1) to (III-10) below.

Based on 100 mol% of the total amount of the diamine component (a2), the amount of the diamine compound (a2-1) used is 2 mol% to 99.5 mol%, preferably 20 mol% to 90 mol%, and more preferably 3 mol% to 80 mol%.

When the diamine component (a2) contains the diamine compound (a2-1) represented by formula (III), the liquid crystal alignment film prepared using this liquid crystal alignment agent can further enhance the low-friction bright spot characteristics of liquid crystal display devices.

Diamine compound (a2-2)

The diamine component (a2) of the present invention may include a diamine compound (a2-2) having a urea structure and represented by formula (IV).

In formula (IV), _Z7 represents an oxygen atom or a sulfur atom; _Z3 and _Z4 each independently represent an alkylene group having 1 to 3 carbon atoms; _Z1 and _Z2 each independently represent a single bond, -O-, -S-, -OCO-, or -COO-; and _Z5 and _Z6 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group represented by formula (IV'), wherein at least one of _Z5 and _Z6 represents a group represented by formula (IV').

-G-L (IV')

In formula (IV'), G represents a single bond or a divalent hydrocarbon group having 1 to 4 carbon atoms; and L represents a protective group that is substituted with a hydrogen atom by heat.

In the aforementioned _Z5 and _Z6 , the group represented by formula (IV') can be, for example, the structure represented by formula (IV'-1) below. When at least one of _Z5 and _Z6 represents the structure represented by formula (IV'-1), the resulting liquid crystal alignment film can further improve the low-friction bright spot characteristics of a liquid crystal display device.

The aforementioned alkylene group with 1 to 3 carbon atoms may be linear or branched, and may be, for example, a methylene group, an ethylene group, a propylene group, a 1-methylethylene group, or a 2-methylethylene group. From the perspective of low friction, structures with more freely rotating moieties and less steric hindrance are preferred. For example, the alkylene group with 1 to 3 carbon atoms may preferably be a methylene group, an ethylene group, or a propylene group.

In formula (IV), _Z1 and _Z2 are preferably selected from the perspective of low friction and low _steric hindrance structures. Therefore, _{Z1 and Z2} are preferably single bonds, -O-, or -S-.

In order to form a film with high density and a stronger liquid crystal alignment film, the structure between the (thio)urea group and the benzene ring is preferably symmetrical based on the (thio)urea group as the center. -Z ₃ -Z ₁ - and -Z ₄ -Z ₂ - preferably have the same structure. In addition, the diamine compound (a2-2) represented by formula (IV) is preferably a compound represented by formula (IV-a) to (IV-c). In formula (IV-a), Z ₈₁ and Z ₉₁ represent an alkylene group having 1 to 3 carbon atoms and have the same carbon number as each other. In formula (IV-b), Z ₈₂ and Z ₉₂ represent an alkylene group having 1 to 3 carbon atoms and have different carbon numbers from each other. In formula (IV-c), Z ₈₃ and Z ₉₃ each independently represent an alkylene group having 1 to 3 carbon atoms.

In formula (IV-a) to formula (IV-c), the definitions of Z ₅ and Z ₆ are as described above and are not further described here. Among them, at least one of Z ₅ and Z ₆ represents the group represented by the aforementioned formula (IV'). L in formula (IV') can be, for example, a carbamate protecting group, an amide protecting group, an imide protecting group, or a sulfonamide protecting group. Among them, L is preferably a carbamate protecting group, and specific examples thereof can include, for example, tert-butyloxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-haloethoxycarbonyl, 1,1-dimethyl-2-cyanoethoxycarbonyl, 9-fluorenylmethoxycarbonyl, allyloxycarbonyl, or 2-(trimethylsilyl)ethoxycarbonyl.

Specific examples of formula (IV) include diamine compounds represented by the following formulas (IV-1) to (IV-40).

In formulas (IV-1) to (IV-40), Boc represents the structure represented by formula (IV'-1).

The aforementioned diamine compound (a2-2) can be used alone or in combination of two or more.

Based on a total usage amount of 100 mol of the diamine component (a2), the usage amount of the diamine compound (a2-2) can be 0.5 mol to 30 mol, preferably 0.75 mol to 25 mol, and more preferably 1 mol to 20 mol.

When the diamine component (a2) comprises a diamine compound (a2-2) represented by formula (IV), the resulting liquid crystal alignment film can further enhance the low-friction bright spot characteristics of liquid crystal display devices.

Other diamine compounds (a2-3)

In addition to the aforementioned diamine compounds (a2-1) and (a2-2), the diamine component (a2) of the present invention may optionally contain other diamine compounds (a2-3).

Other diamine compounds (a2-3) may be, for example, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,5-diaminophenol, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminobenzyl alcohol, Aminoresorcinol, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-biphenyl, 3,3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'- -Diaminobiphenyl, 2,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylmethane, 2,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, 4,4'-Sulfonyldiphenylamine, 3,3'-Sulfonyldiphenylamine, Bis(4-aminophenyl)silane, Bis(3-aminophenyl)silane, Dimethylbis(4-aminophenyl)silane, Dimethylbis(3-aminophenyl)silane, 4,4'-Thiodiphenylamine, 3,3'-Thiodiphenylamine, 4,4'-Diaminodiphenylamine, 3,3'-Diaminodiphenylamine, 3,4'-Diaminodiphenylamine, 2,2'-Diaminodiphenylamine Aniline, 2,3'-diaminodiphenylamine, N-methyl(4,4'-diaminodiphenyl)amine, N-methyl(3,3'-diaminodiphenyl)amine, N-methyl(3,4'-diaminodiphenyl)amine, N-methyl(2,2'-diaminodiphenyl)amine, N-methyl(2,3'-diaminodiphenyl)amine, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diamino Benzophenone, 1,4-diaminonaphthalene, 2,2'-diaminobenzophenone, 2,3'-diaminobenzophenone, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 1,2-bis(4-aminophenyl)ethane, 1,2-bis(3-aminophenyl)ethane , 1,3-bis(4-aminophenyl)propane, 1,3-bis(3-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(3-aminophenyl)butane, bis(3,5-diethyl-4-aminophenyl)methane, 1,4-bis(4-aminophenoxy) benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl) phenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-[1,4-phenylenebis(methylene)]diphenylamine, 4,4'-[1,3-phenylenebis(methylene)]diphenylamine, 3,4'-[1,4-phenylenebis(methylene)]diphenylamine, 3,4'-[1,3-phenylenebis(methylene)] Diphenylamine, 3,3'-[1,4-phenylenedi(methylene)]diphenylamine, 3,3'-[1,3-phenylenedi(methylene)]diphenylamine, 1,4-benzobis[(4-aminophenyl)m-ketone], 1,4-benzobis[(3-aminophenyl)m-ketone], 1,3-phenylenedibis[(4-aminophenyl)m-ketone], 1,3-phenylenedibis[(3-aminophenyl)m-ketone], 1,4-benzo Bis(4-aminobenzoate), 1,4-benzobis(3-aminobenzoate), 1,3-phenylenedibis(4-aminobenzoate), 1,3-benzobis(3-aminobenzoate), bis(4-aminophenyl) terephthalate, bis(3-aminophenyl) terephthalate, bis(4-aminophenyl) isophthalate, bis(3-aminophenyl) isophthalate, N,N'-(1,4-phenylene) )bis(4-aminobenzamide), N,N'-(1,3-phenylene)bis(4-aminobenzamide), N,N'-(1,4-phenylene)bis(3-aminobenzamide), N,N'-(1,3-phenylene)bis(3-aminobenzamide), N,N'-bis(4-aminophenyl)-p-phenylenediamine, N,N'-bis(3-aminophenyl)-p-phenylenediamine, N,N'-bis(4-aminophenyl)-p-phenylenediamine N,N'-Bis(3-aminophenyl)m-xylylenediamide, 9,10-bis(4-aminophenyl)anthracene, 4,4'-bis(4-aminophenoxy)diphenylsulfone, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(3-aminophenyl)m-xylylenediamide, 9,10-bis(4-aminophenyl)anthracene, 4,4'-bis(4-aminophenoxy)diphenylsulfone, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(4-aminophenyl)hexafluoropropane, -aminophenyl)hexafluoropropane, 2,2'-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(3-aminophenyl)propane, 2,2'-bis(3-aminophenyl)propane, 1,3-bis(4-aminophenoxy)propane, 1,3-bis(3-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,4-Bis(3-aminophenoxy)butane, 1,5-Bis(4-aminophenoxy)pentane, 1,5-Bis(3-aminophenoxy)pentane, 1,6-Bis(4-aminophenoxy)hexane, 1,6-Bis(3-aminophenoxy)hexane, 1,7-Bis(4-aminophenoxy)heptane, 1,7-(3-aminophenoxy)heptane, 1,8-Bis(4-aminophenoxy)octane, 1,8-Bis(3-aminophenoxy) 1,9-bis(4-aminophenoxy)nonane, 1,9-bis(3-aminophenoxy)nonane, 1,10-(4-aminophenoxy)decane, 1,10-(3-aminophenoxy)decane, 1,11-(4-aminophenoxy)undecane, 1,11-(3-aminophenoxy)undecane, 1,12-(4-aminophenoxy)dodecane, 1,12-(3-aminophenoxy) 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane or 1,12-diaminododecane, etc.

The aforementioned other diamine compounds (a2-3) can be used alone or in combination.

There is no particular limitation on the amount of the other diamine compounds (a2-3). For example, based on a total amount of 100 mol of the diamine component (a2), the amount of the other diamine compounds (a2-3) can be 0 mol to 99.5 mol, preferably 0 mol to 99.25 mol, and even more preferably 0 mol to 99 mol.

Preparation method of polymer (A)

The polyamine polymer of the present invention can be prepared by a conventional method. Preferably, the method comprises the following steps: dissolving a mixture comprising the tetracarboxylic dianhydride component (a1) and the diamine component (a2) in a solvent, conducting a polycondensation reaction at a temperature of 0°C to 100°C for 1 to 24 hours, and then distilling the reaction solution under reduced pressure in an evaporator to obtain the polyamine polymer. Alternatively, the reaction solution can be poured into a large amount of a poor solvent to obtain a precipitate, and then drying the precipitate under reduced pressure to obtain the polyamine polymer.

The solvent used in the polymerization reaction may be the same as or different from the solvent (B) in the liquid crystal alignment agent described below. There is no particular limitation on the solvent used in the polymerization reaction, as long as it can dissolve the reactants and the product. Preferably, the solvent includes but is not limited to (1) aprotic polar solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, or hexamethylphosphoric acid triamide; (2) phenolic solvents, such as m-cresol, xylenol, phenol, or halogenated phenols. Based on 100 parts by weight of the mixture, the amount of the solvent used in the polymerization reaction is preferably 200 to 2000 parts by weight, and more preferably 300 to 1800 parts by weight.

In particular, in the polycondensation reaction, the solvent may be combined with an appropriate amount of a poor solvent, wherein the poor solvent does not cause the polyamine polymer to precipitate. The poor solvent may be used alone or in combination, and includes but is not limited to: (1) alcohols, such as methanol, ethanol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, or triethylene glycol; (2) ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; (3) esters, such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, or ethylene glycol ethyl ether acetate; (4) ethers , such as: diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; (5) halogenated hydrocarbons, such as: dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene or o-dichlorobenzene; (6) hydrocarbons, such as: tetrahydrofuran, hexane, heptane, octane, benzene, toluene or xylene or any combination of the above solvents. Based on the usage amount of the mixture being 100 parts by weight, the usage amount of the poor solvent is preferably 0 parts by weight to 60 parts by weight, and more preferably 0 parts by weight to 50 parts by weight.

The polyimide polymer of the present invention can be prepared by a conventional method. Preferably, the polyimide polymer preparation method first dissolves a mixture comprising a tetracarboxylic dianhydride component (a1) and a diamine component (a2) in a solution and undergoes a polymerization reaction to form a polyimide polymer. Subsequently, the mixture is further heated in the presence of a dehydrating agent and a catalyst to undergo a dehydration and ring-closing reaction, whereby the amide functional groups in the polyimide polymer are converted to imide functional groups (i.e., imidization) through the dehydration and ring-closing reaction, thereby obtaining the polyimide polymer.

The solvent used in the dehydration and ring-closing reaction can be the same as solvent (B) in the liquid crystal alignment agent described below and is not described separately. Based on 100 parts by weight of the polyamine polymer, the amount of solvent used in the dehydration and ring-closing reaction is preferably 200 to 2000 parts by weight, and more preferably 300 to 1800 parts by weight.

To achieve an optimal degree of imidization in the polyimide polymer, the dehydration and ring-closing reaction temperature is preferably between 40°C and 200°C, more preferably between 40°C and 150°C. If the dehydration and ring-closing reaction temperature is lower than 40°C, the imidization reaction is incomplete, reducing the degree of imidization of the polyimide polymer. However, if the dehydration and ring-closing reaction temperature is higher than 200°C, the weight-average molecular weight of the resulting polyimide polymer is relatively low.

The dehydrating agent used in the dehydration ring-closing reaction can be selected from an anhydride compound, specifically, an anhydride compound such as acetic anhydride, propionic anhydride or trifluoroacetic anhydride. Based on 1 mol of the polyamide polymer, the amount of the dehydrating agent used is 0.01 mol to 20 mol. The catalyst used in the dehydration ring-closing reaction can be selected from (1) pyridine compounds, such as pyridine, trimethylpyridine or dimethylpyridine; (2) tertiary amine compounds, such as triethylamine. Based on 1 mol of the dehydrating agent used, the amount of the catalyst used is 0.5 mol to 10 mol.

Preferred examples of the polyimide block copolymers of the present invention are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

The polyimide-based block copolymer of the present invention can be prepared by a conventional method. Preferably, the polyimide-based block copolymer preparation method first dissolves the starting materials in a solvent and conducts a polycondensation reaction. The starting materials include at least one polyamic acid polymer and/or at least one polyimide polymer described above, and may further include a tetracarboxylic dianhydride component (a1) and a diamine component (a2).

The tetracarboxylic dianhydride component (a1) and diamine component (a2) in the aforementioned starting materials are the same as those used in the preparation of the polyamic acid polymer. The solvent used in the polycondensation reaction can be the same as the solvent used in the liquid crystal alignment agent described below and will not be further described here.

Based on 100 parts by weight of the aforementioned starting materials, the amount of solvent used in the polycondensation reaction is preferably 200 to 2000 parts by weight, and more preferably 300 to 1800 parts by weight. The operating temperature of the polycondensation reaction is preferably 0°C to 200°C, and more preferably 0°C to 100°C.

Preferably, the starting materials include but are not limited to (1) two polyamic acid polymers with different terminal groups and different structures; (2) two polyimide polymers with different terminal groups and different structures; (3) a polyamic acid polymer and a polyimide polymer with different terminal groups and different structures; (4) a polyamic acid polymer, a tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine compound forms a polymer. The tetracarboxylic dianhydride component (a1) and the diamine component (a2) used in the polyimide polymer have different structures; (5) a polyimide polymer, a tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine compound has a different structure from the tetracarboxylic dianhydride component (a1) and the diamine component (a2) used to form the polyimide polymer; (6) a polyimide polymer, a polyimide polymer , a tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine compound has a structure different from that of the tetracarboxylic dianhydride component (a1) and the diamine component (a2) used to form the polyamic acid polymer or the polyimide polymer; (7) two polyamic acid polymers, tetracarboxylic dianhydride compounds and diamine compounds having different structures; (8) two polyimide polymers, tetracarboxylic dianhydride compounds and Diamine compounds; (9) two polyamic acid polymers whose terminal groups are acid anhydride groups and whose structures are different, and a diamine compound; (10) two polyamic acid polymers whose terminal groups are amino groups and whose structures are different, and a tetracarboxylic dianhydride compound; (11) two polyimide polymers whose terminal groups are acid anhydride groups and whose structures are different, and a diamine compound; (12) two polyimide polymers whose terminal groups are amino groups and whose structures are different, and a tetracarboxylic dianhydride compound.

Insofar as the efficacy of the present invention is not affected, preferably, the aforementioned polyamic acid polymer, the aforementioned polyimide polymer and the aforementioned polyimide-based block copolymer can be terminal-modified polymers after molecular weight adjustment. By using terminal-modified polymers, the coating performance of the liquid crystal alignment agent can be improved. The method for preparing the aforementioned terminal-modified polymer can be prepared by adding a monofunctional compound to the polyamic acid polymer while performing a polycondensation reaction. The monofunctional compound includes but is not limited to (1) monobasic acid anhydrides, such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride or n-hexadecylsuccinic anhydride; (2) monoamine Compounds, such as monoamine compounds such as aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine or n-eicosylamine; (3) Monoisocyanate compounds, such as monoisocyanate compounds such as phenyl isocyanate or naphthyl isocyanate.

The polymer (A) of the present invention has a polystyrene-equivalent weight average molecular weight of 10,000 to 90,000, preferably 12,000 to 75,000, and more preferably 15,000 to 60,000, as measured by gel permeation chromatography.

Solvent (B)

The solvent used in the liquid crystal alignment agent of the present invention is not particularly limited, as long as it can dissolve the polymer (A) and any other components and does not react with them. Preferably, it is the same solvent used in the aforementioned synthesis of polyamine. Furthermore, a poor solvent used in the aforementioned synthesis of polyamine may also be used in combination.

Specific examples of the solvent (B) include, but are not limited to, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, γ-butyrolactamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, N,N-dimethylformamide, or N,N-dimethylacetamide.

The aforementioned solvent (B) can be used alone or in combination.

Based on 100 parts by weight of polymer (A), the amount of solvent (B) used is 800 to 4000 parts by weight, preferably 900 to 3500 parts by weight, and more preferably 1000 to 3000 parts by weight.

Compound (C)

The compound (C) of the present invention may include compounds represented by formula (I-1) and/or formula (I-2).

In formula (I-1) and formula (I-2), _R1 represents an n-valent linear aliphatic alkyl group having at least 2 carbon atoms, or an n-valent alicyclic alkyl group having at least 4 carbon atoms; n represents an integer from 2 to 6; _R2 and _R3 each independently represent a hydrogen atom, an aliphatic alkyl group, an alicyclic alkyl group, an aromatic alkyl group, a group represented by formula (I-3), a group represented by formula (I-4), or a group represented by formula (I-5), wherein at least one of _R2 and _R3 represents a group represented by formula (I-3), a group represented by formula (I-4), or a group represented by formula (I-5).

In formula (I-3), h represents an integer of 1 to 6; in formula (I-4), i represents an integer of 1 to 6, and R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; in formula (I-5), j represents an integer of 1 to 6.

The linear aliphatic hydrocarbon group of _R1 in Formula (I-1) and Formula (I-2) may include, for example, any of an alkyl group, an alkenyl group, and an alkynyl group bonded to n-1 hydrogen atoms. In the present invention, such groups may be, for example, n-valent alkyl groups, n-valent alkenyl groups, and n-valent alkynyl groups.

The aforementioned n-valent alkyl group having at least 2 carbon atoms may include, but is not limited to, methyl, 1,2-ethyl, 1,3-propyl, 1,4-butyl, 1,5-pentyl, 1,6-hexyl, 1,7-heptyl, 1,8-octyl, 1,9-nonyl, 1,6-decyl, 1,10-decyl, 1,11-undecyl, 1,12-dodecyl, 1,13-tridecyl, 1,14-tetradecyl, 1,15-pentadecyl, 1,16-hexadecyl, 1,17-heptadecyl, 1,18-octadecyl, 1,19-octadecyl, 1,20-eicosyl, 1,3,6-hexyl, 1,4,7-heptyl, 1,2,8-octyl, 1,3,9-nonyl, 1,3,4,6-hexyl, 1,4,6,7-heptyl, 1,4,5,6,7-heptyl or 1,2,3,4,5,6-hexyl, etc.

The aforementioned n-valent alkenyl group having at least 2 carbon atoms may include, but is not limited to, 1,2-vinylene, 1-3-(1-propenyl), 1-3-(2-propenyl), 1,4-(2-butenyl), 1,5-(2-pentenyl), 1,6-(2-hexenyl), 1,7-(2-heptenyl), 1,8-(2-octenyl), 1,9-(2-nonenyl), 1,10-(2-decenyl), 1,11-(2-undecenyl), 1,12-(2-dodecenyl), 1,13-(2-tridecenyl), 1,14-(2-octenyl), 1,15-(2-hexenyl), 1,16-(2-hexenyl), 1,1 ...hexenyl), 1,18-(2-octenyl), 1,19-(2-nonenyl), 1,20-(2-decenyl), 1,21-(2-dodecenyl), 1,22-(2-dodecenyl), 1,23-(2-hexenyl), 1,24-(2-hexenyl), 1,25-(2-hexenyl), 1,26-(2-hexenyl), 1,27-(2-hexen -(2-tetradecenyl), 1,15-(2-pentadecenyl), 1,16-(2-hexadecenyl), 1,17-(2-heptadecenyl), 1,18-(2-octadecenyl), 1,19-(2-octadecenyl), 1,3,6-(2-hexenyl), 1,4,7-(3-heptenyl), 1,2,8-(4-octenyl), 1,3,9-(5-nonenyl), 1,3,4,6-(2-hexenyl), 1,4,6,7-(3-heptenyl) or 1,4,5,6,7-(3-heptenyl), etc.

The aforementioned n-valent alkynyl group having at least 2 carbon atoms may include, but is not limited to, 1,2-ethynyl, 1-3-(1-propynyl), 1-3-(2-propynyl), 1,4-(2-butynyl), 1,5-(2-pentynyl), 1,6-(2-hexynyl), 1,7-(2-heptynyl), 1,8-(2-octynyl), 1,9-(2-nonynyl), 1,10-(2-decynyl), 1,11-(2-undecynyl), 1,12-(2-dodecynyl), 1,13-(2-tridecynyl), 1,1 4-(2-tetradecynyl)yl, 1,15-(2-pentadecinyl)yl, 1,16-(2-hexadecynyl)yl, 1,17-(2-heptadecinyl)yl, 1,18-(2-octadecynyl)yl, 1,19-(2-octadecynyl)yl, 1,3,6-(2-hexynyl)yl, 1,4,7-(3-heptynyl)yl, 1,2,8-(4-octynyl)yl, 1,3,9-(5-nonynyl)yl, 1,3,4,6-(2-hexynyl)yl, 1,4,6,7-(3-heptynyl)yl or 1,4,5,6,7-(3-heptynyl)yl, etc.

The alicyclic hydrocarbon group of R ₁ in Formula (I-1) and Formula (I-2) may include, for example, a structure in which a monovalent group of a cycloalkyl group, a decalinyl group, or an adamantyl group is bonded to n-1 hydrogen atoms.

The aforementioned n-valent alicyclic alkyl group having at least 4 carbon atoms may include, but is not limited to, 1,1-cyclobutyl, 1,2-cyclobutyl, 1,3-cyclobutyl, 1,4-cyclobutyl, 1,1-cyclohexyl, 1,2-cyclohexyl, 1,3-cyclohexyl, 1,4-cyclohexyl, 1,2,4-cyclohexyl, 1,3,5-cyclohexyl, 1,2,4,5-cyclohexyl, 1,2,3,4,5,6-cyclohexyl, 2,6-decalinyl, 1,3-adamantyl, or 1,3,5-adamantyl.

In Formula (I-1) and Formula (I-2), _R1 is preferably a linear aliphatic alkyl group having 2 to 20 carbon atoms. When _R1 is a linear aliphatic alkyl group having 2 to 20 carbon atoms, the compound (C) exhibits improved solubility in organic solvents or resins, and the resulting liquid crystal display device exhibits enhanced low-friction bright spot characteristics.

n in formula (I-1) and formula (I-2) is preferably 2. When n in formula (I-1) and formula (I-2) represents 2, the liquid crystal alignment film prepared by this liquid crystal alignment agent can further enhance the low-friction bright spot characteristics of the liquid crystal display element. Preferably, R ₁ in the aforementioned formula (I-1) and formula (I-2) represents a linear aliphatic alkyl group having a carbon number of 2 to 20, and the hydrogen atoms at both ends of the linear aliphatic alkyl group serve as bonding sites. When R ₁ represents a linear aliphatic alkyl group having a carbon number of 2 to 20, the liquid crystal alignment film prepared by this liquid crystal alignment agent can further enhance the low-friction bright spot characteristics of the liquid crystal display element.

In R ₂ and R ₃ in formula (I-1) and formula (I-2), specific examples of the aliphatic hydrocarbon group include alkyl, alkenyl, and alkynyl groups.

Alkyl groups may include but are not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl and octadecyl, etc.

Alkenyl groups include, but are not limited to, ethenyl, 1-propenyl, 2-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-octenyl, 1-decenyl, and 1-octadecenyl.

Alkynyl groups include, but are not limited to, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-octynyl, 1-decynyl, and 1-octadecyl.

In R ₂ and R ₃ in formula (I-1) and formula (I-2), specific examples of the alicyclic hydrocarbon group include a cycloalkyl group, a naphthyl group, and an adamantyl group.

Cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclooctadecyl, and 2-indenyl.

In R ₂ and R ₃ in formula (I-1) and formula (I-2), specific examples of the aromatic hydrocarbon group include monocyclic, condensed-ring, and polycyclic aromatic hydrocarbon groups.

Monocyclic aromatic hydrocarbon groups may include, but are not limited to, phenyl, o-tolyl, m-tolyl, p-tolyl, 2,4-xylyl, p-isopropylphenyl, and mesityl.

Fused-ring aromatic hydrocarbon groups may include, but are not limited to, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 5-anthryl, 1-phenanthrenyl, 9-phenanthrenyl, 1-acenaphthenyl, 2-mercaptophenyl, 1-pyridyl, and 2-triphenylene.

Polycyclic aromatic hydrocarbon groups may include but are not limited to o-biphenyl, m-biphenyl and p-biphenyl.

In formula (I-1) and formula (I-2), R ₂ and R ₃ are preferably an aliphatic alkyl group, an alicyclic alkyl group, or a monocyclic aromatic alkyl group, more preferably an aliphatic alkyl group or an alicyclic alkyl group, and even more preferably an aliphatic alkyl group.

However, it is understood that while _R2 and _R3 are preferably aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, or monocyclic aromatic hydrocarbon groups as described above, at least one of _R2 and _R3 in Formula (I-1) and Formula (I-2) must be a group represented by Formula (I-3), a group represented by Formula (I-4), or a group represented by Formula (I-5). If Compound (C) does not have a group represented by Formula (I-3), a group represented by Formula (I-4), or a group represented by Formula (I-5), a liquid crystal display device having a liquid crystal alignment film prepared therefrom will have poor low-friction bright spot characteristics.

In formulas (I-1) and (I-2), when the structures of formulas (I-1) and (I-2) contain a group represented by formula (I-3) compared to the groups represented by formulas (I-4) and (I-5), a liquid crystal display device having a liquid crystal alignment film made therefrom will have better low-friction bright spot characteristics.

Specific examples of the compounds represented by formula (I-1) and formula (I-2) include, but are not limited to, the compounds represented by formula (VI-1) to formula (VI-73) below.

The aforementioned compound (C) may be used alone or in combination of two or more.

Based on 100 parts by weight of polymer (A), the amount of compound (C) used is 1 to 15 parts by weight, preferably 2 to 12.5 parts by weight, and more preferably 2.5 to 10 parts by weight.

If the liquid crystal alignment agent of the present invention does not use compound (C), the resulting liquid crystal alignment film will not be able to improve the low-friction bright spot characteristics of the liquid crystal display device.

Preparation method of compound (C)

The compounds (C) represented by formula (I-1) and formula (I-2) of the present invention can be prepared by amidation or ureidation of divalent or higher-valent carboxylic acids and their derivatives, or divalent or higher-valent diisocyanates, with amines containing a glycidyl group, an alicyclic epoxy group, or an oxocyclobutane group.

There are various methods for the amidation of amines containing glycidyl, alicyclic epoxy, or oxocyclobutane groups with carboxylic acids or their derivatives.

In the case of carboxylic acids, the reaction proceeds by removing water. In the case of carboxylic esters, the reaction proceeds by removing alcohols. In the case of carboxylic anhydrides or halides, the reaction proceeds by removing the acid. When removing water or alcohols, they can be easily distilled from the reaction system by heating, reducing the pressure, or both. When removing acids, they can be removed with bases such as triethylamine, tributylamine, dimethylbenzylamine, pyridine, dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]-7-undecene, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

The ureidation reaction of amines containing a glycidyl group, an alicyclic epoxy group, or an oxycyclobutane group with diisocyanate or its derivatives can be carried out at room temperature.

A catalyst may be used during the aforementioned amidation and ureation. The catalyst may be, for example, an acid catalyst such as sulfuric acid, hydrochloric acid, nitrate, methanesulfonic acid, or p-toluenesulfonic acid; an inorganic base catalyst such as sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, or cesium carbonate; an organic base catalyst such as an amine or an alcoholate; an amine catalyst may be, for example, triethylamine, diisopropylethylamine, tributylamine, trioctylamine, tetramethylethylenediamine, N,N-dimethylethanolamine, N,N-dimethylbenzylamine, pyridine, 4-(dimethylamino)pyridine, imidazole, or the like. , N-methylimidazole, 1,8-diazabicyclo[5.4.0]-7-undecene or 1,5-diazabicyclo[4.3.0]-5-nonene, etc. The alkoxide catalyst may be, for example, sodium methoxide, sodium ethoxide or sodium tert-butoxide; salts containing metal ions such as iron (III), zirconium (IV), plutonium (III), titanium (IV), tin (IV) or eum (IV) and their complexes; ammonium salts such as diphenylammonium trifluoromethanesulfonate or pentafluorophenylammonium trifluoromethanesulfonate.

In the amidation and ureation reactions, a solvent and catalyst may be used as necessary. The solvent used may be any solvent other than those that react with reactive substrates such as alcohol, amine, and carboxylic acid groups. Examples of the solvent used include water, hexane, heptane, octane, cyclohexane, benzene, toluene, ethylbenzene, xylene, chloroform, ethyl acetate, butyl acetate, isobutyl acetate, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, tetrahydrofuran (THF), cyclohexanone, dichloromethane, chloroform, dimethylsulfoxide, dimethylformamide, or dimethylacetamide.

The amination of carboxylic acids is particularly advantageous using condensing agents. These agents simultaneously activate the carboxylic acid or amine and initiate the esterification reaction under mild conditions. Since the byproduct, water, combines with the condensing agent to form another compound, the condensing agent acts as both a catalytic and dehydrating compound.

The compounds represented by formula (I-1) and formula (I-2) of the present invention are characterized by being soluble in organic solvents.

The aforementioned organic solvent may be, for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran (THF), cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, benzene, toluene, ethylbenzene, xylene, cyclohexane, hexane, octane, dichloromethane, chloroform, dimethylformamide, dimethylacetamide, acetonitrile, or dimethylsulfoxide.

The liquid crystal alignment agent containing the compound (C) of the present invention can be coated on one or both sides of various substrates, or formed using a mold and, if necessary, dried by heat, then thermally cured at 100°C to 200°C to obtain the desired cured product. The substrate can be, for example, glass, ceramics, polycarbonate, polyester fiber, urethane, acrylic fiber, polyacetate, polyamide, polyimide, polystyrene, epoxy resin, polyolefin, polycycloolefin, or polyvinyl alcohol, or a metal substrate such as stainless steel.

The thermal curing temperature of the liquid crystal alignment agent containing the compound (C) of the present invention can be 100°C to 180°C, preferably 120°C to 180°C, and more preferably 120°C to 150°C.

It is understood that the raw materials for synthesizing compound (C) of the present invention are not limited to the materials listed above. Those skilled in the art can select appropriate raw materials for synthesizing compound (C) based on the relevant disclosures herein to produce compound (C) of the present invention.

For example, the synthesis method of the compound represented by the following formula (VI-74) is described as an example.

First, 146 parts by weight of adipic acid (reactant 1; a divalent or higher carboxylic acid or its derivative; ), 202 parts by weight of N-ethyl-2-epoxyethanemethylamine (Reactant 2; amines containing a glycidyl group, an alicyclic epoxy group, or an oxyheterocyclobutane group; ), 2 parts by weight of potassium hydroxide (catalyst) and 200 parts by weight of toluene (solvent), wherein the molar ratio of reactant 1 to reactant 2 is 1:2. The Dean-Stark tube is filled with toluene and heated to reflux while blowing nitrogen to remove the water produced by azeotropy. After the reaction has lasted for 4 hours, the toluene is removed and the resulting product is measured by 1H-NMR and IR to identify it as the target product. Then, the temperature is lowered to 50°C and a uniform light yellow transparent solution is taken out. The reaction formula of the reaction is shown below.

Additives (D)

The liquid crystal alignment agent of the present invention may optionally include an additive (D), within the scope of not affecting the efficacy of the present invention. The additive (D) may be an epoxy compound or a silane compound with a functional group. The additive (D) functions to improve the adhesion of the liquid crystal alignment film to the substrate surface. The additive (D) may also include a compound that improves the film thickness uniformity and surface smoothness of the liquid crystal alignment film during coating of the liquid crystal alignment agent. Furthermore, the additive (D) may include a compound that promotes charge transfer and release within the liquid crystal alignment film. The additive (D) may be used alone or in combination of multiple compounds.

The aforementioned epoxy compounds may include but are not limited to ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N, N',N'-tetracycloxypropyl-m-xylenediamine, 1,3-bis(N,N-dicycloxypropylaminomethyl)cyclohexane, N,N,N',N'-tetracycloxypropyl-4,4'-diaminodiphenylmethane, N,N- Epoxypropyl-p-glycidoxyaniline, 3-(N-allyl-N-epoxypropyl)aminopropyltrimethoxysilane, 3-(N,N-dicycloxypropyl)aminopropyltrimethoxysilane, etc.

Based on 100 parts by weight of polymer (A), the amount of epoxy compound used is generally less than 40 parts by weight, and preferably 0.1 to 30 parts by weight.

The silane compound having a functional group may include, but is not limited to, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilane Propyl triethylenetriamine, N-trimethoxysilylpropyl triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazdecane, 10-triethoxysilyl-1,4,7-triazdecane, 9-trimethoxysilyl-3,6-diazonyl acetate, 9-triethoxysilyl-3,6-diazonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(ethylene oxide)-3-aminopropyltrimethoxysilane, N-bis(ethylene oxide)-3-aminopropyltriethoxysilane, etc.

Based on 100 parts by weight of polymer (A), the amount of the silane compound used is generally less than 10 parts by weight, and preferably 0.5 to 10 parts by weight.

The aforementioned compounds that can be used to improve the film thickness uniformity and surface smoothness of the liquid crystal alignment film may include, but are not limited to, fluorine-based surfactants, silicone-based surfactants, and non-ionic surfactants.

Specific examples of the aforementioned compounds that improve film thickness uniformity and surface smoothness include F-top EF301, EF303, and EF352 (manufactured by Shin Akita Chemical Co., Ltd.); Megafac F171, F173, and R-30 (manufactured by Dainippon Ink & Chemical Co., Ltd.); Fluorad FC430 and FC431 (manufactured by Sumitomo 3M Co., Ltd.); and Asahi Guard AG710 and Surflon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by Asahi Glass Co., Ltd.).

Based on 100 parts by weight of polymer (A), the amount of the surfactant used can be 0.01 to 2 parts by weight, and preferably 0.01 to 1 part by weight.

The aforementioned compound that helps improve the electrical properties of the liquid crystal alignment film can be, for example, a nitrogen-containing heterocyclic amine compound. The nitrogen-containing heterocyclic amine compound can be added directly to the liquid crystal alignment agent, or prepared as a solution in a suitable solvent (at a concentration of 0.1wt% to 10wt%, preferably 1wt% to 7wt%) before addition. The solvent used is not particularly limited.

In addition to the specific examples of additives (D) mentioned above, the liquid crystal alignment agent of the present invention may optionally contain dielectric or conductive substances to modify the electrical properties of the liquid crystal alignment film, such as the dielectric constant and conductivity, as long as the effects of the present invention are not impaired.

Based on 100 parts by weight of polymer (A), the amount of additive (D) used can be 0.5 to 50 parts by weight, and preferably 1 to 45 parts by weight.

Preparation method of liquid crystal alignment agent

The preparation method of the liquid crystal alignment agent of the present invention is not particularly limited and can be prepared using a conventional mixing method. For example, the tetracarboxylic dianhydride component (a1) and the diamine component (a2) are first uniformly mixed to react and form a polymer (A). Then, the polymer (A) is added to the solvent (B) and the compound (C) at a temperature between 0°C and 200°C and stirred continuously with a stirring device until dissolved. Preferably, the polymer (A) and the compound (C) are added to the solvent (B) at a temperature between 20°C and 60°C. During the preparation of the liquid crystal alignment agent, an additive (D) may be optionally added to the solvent (B).

Method for forming liquid crystal alignment film

The liquid crystal alignment film of the present invention is produced by coating the liquid crystal alignment agent formed above on a substrate, followed by drying and baking.

The substrate on which the liquid crystal alignment agent of the present invention is applied is selected from transparent materials. Transparent materials include, but are not limited to, alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, and polycarbonate, all of which are used in liquid crystal displays. Preferably, the substrate is already equipped with ITO electrodes for liquid crystal driving to simplify the manufacturing process. Furthermore, for reflective liquid crystal displays with only a single-sided substrate, the substrate can be made of an opaque material such as a silicon wafer. In this case, the electrodes can be formed of a light-reflective material such as aluminum. The liquid crystal alignment agent of the present invention can be applied by methods such as spin coating, printing, and inkjet printing.

The liquid crystal alignment agent of the present invention can be dried and baked at any temperature and time after coating. Generally, to fully remove organic solvents, drying is performed at 50°C to 120°C for 1 to 10 minutes. Baking is then performed at 150°C to 300°C for 5 to 120 minutes. There are no specific restrictions on the thickness of the coating after baking, but excessively thin coatings can compromise the reliability of LCDs. Therefore, the coating thickness is preferably between 5nm and 300nm, with 10nm to 200nm being preferred.

Although the liquid crystal alignment agent of the present invention can be subjected to conventional rubbing alignment treatment, it achieves better results when using photo-alignment treatment.

A specific example of the photo-alignment treatment method includes irradiating the surface of the aforementioned film with radiation polarized in a specific direction, and then optionally heating it at a temperature of 150°C to 250°C to impart liquid crystal alignment properties to the aforementioned film. The radiation can be ultraviolet light or visible light with a wavelength of 100nm to 800nm, preferably ultraviolet light with a wavelength of 100nm to 400nm, and more preferably with a wavelength of 200nm to 400nm. Furthermore, to improve the liquid crystal alignment properties, the coated substrate can be heated at 50°C to 250°C while being irradiated with radiation. The radiation dose is preferably 1mJ/cm ² to 10,000mJ/cm ² , and more preferably 100mJ/cm ² to 5,000mJ/cm ² . The liquid crystal alignment film prepared in the above manner can stably align liquid crystal molecules in a certain direction.

The liquid crystal alignment agent of the present invention undergoes a pre-bake process, a post-bake process, and a photo-alignment process to form a liquid crystal alignment film. The pre-tilt angle of the liquid crystal alignment film is 0 to 3 degrees.

Manufacturing method of liquid crystal display element

The present invention also provides a liquid crystal display device comprising the aforementioned liquid crystal alignment film.

The manufacturing method of liquid crystal display devices is well known to those skilled in the art, so the following description is brief.

Referring to FIG. 1 , a preferred embodiment of the liquid crystal display device 100 of the present invention includes a first unit 110 , a second unit 120 , and a liquid crystal unit 130 . The second unit 120 is spaced apart from the first unit 110 , and the liquid crystal unit 130 is disposed between the first unit 110 and the second unit 120 .

The first unit 110 includes a first substrate 112, an electrode 114, and a first liquid crystal alignment film 116. The electrode 114 is formed on the surface of the first substrate 112 in a stylized pattern, and the first liquid crystal alignment film 116 is formed on the surface of the electrode 114.

The second unit 120 includes a second substrate 122 and a second liquid crystal alignment film 126, wherein the second liquid crystal alignment film 126 is formed on the surface of the second substrate 122.

The first substrate 112 and the second substrate 122 are made of transparent materials, including but not limited to alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, and polycarbonate, which are used in liquid crystal displays. The electrode 114 is made of a transparent electrode such as tin oxide ( _SnO2 ), indium oxide-tin oxide ( _In2O3 - _SnO2 ), or _a metal electrode such as chromium.

The first liquid crystal alignment film 116 and the second liquid crystal alignment film 126 are the aforementioned liquid crystal alignment films. Their function is to form a pre-tilt angle in the liquid crystal cell 130, and the liquid crystal cell 130 can be driven by the parallel electric field generated by the electrode 114.

The liquid crystal used in the liquid crystal unit 130 may be used alone or in combination. The liquid crystals include, but are not limited to, diaminobenzene liquid crystals, pyridazine liquid crystals, shiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, and cubane liquid crystals. Furthermore, other liquid crystals such as cholesterol chloride, cholesterol nonanoate, and cholesterol carbonate may be added as needed. Cholesterol-type liquid crystals such as 1,2-dimethoxy-1,4-dihydro-1-nitro-2-nitro-1,4-dihydro-2-nitro-1-nitro ...

Liquid crystal display devices made with the liquid crystal alignment agent of this invention are suitable for various nematic liquid crystal types, such as TN, STN, TFT, VA, and IPS. Furthermore, depending on the selected liquid crystal, liquid crystal displays with strong or anti-strong induction properties can also be used. Among these liquid crystal displays, IPS-type liquid crystal displays are particularly suitable.

The following examples illustrate the application of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can make various modifications and improvements without departing from the spirit and scope of the present invention.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: First conductive film

116:The first liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

For a more complete understanding of the embodiments of the present invention and its advantages, please refer to the following description in conjunction with the accompanying drawings. It must be emphasized that the various features are not drawn to scale and are for illustrative purposes only. The relevant drawings are described as follows: Figure 1 is a schematic diagram illustrating the structure of a liquid crystal display device according to one embodiment of the present invention.

Preparation of polymer (A)

Synthesis Example A-1-1

A 500 ml four-necked Erlenmeyer flask was equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer, and nitrogen was introduced. Then, 4.76 g (0.035 mol) of the diamine compound (a2-1-1) represented by formula (III-1), 1.92 g (0.005 mol) of the diamine compound (a2-2-1) represented by formula (IV-20), 1.98 g (0.01 mol) of 4,4'-diaminodiphenylmethane (a2-3-2), and 80 g of N-methyl-2-pyrrolidone (NMP) were added and stirred at room temperature until dissolved. Next, 1.961 g (0.005 mol) of the compound (a1-1-3) represented by formula (II-8), 9.8154 g (0.045 mol) of pyromellitic dianhydride (a1-2-1), and 20 g of NMP were added, and the mixture was reacted at room temperature for 2 hours. After the reaction, the reaction solution was poured into 1500 ml of water to precipitate the polymer. The resulting polymer was filtered and then washed and filtered with methanol three times. The product was then placed in a vacuum oven and dried at 60°C to obtain the polymer (A-1-1) of Synthesis Example A-1-1, the formula of which is shown in Table 1.

Synthesis Examples A-1-2 to A-1-13

Synthesis Examples A-1-2 to A-1-13 use the same preparation method as the polymer (A-1-1) in Synthesis Example A-1-1. The difference lies in the changes in the types and amounts of raw materials used in the polymers in Synthesis Examples A-1-2 to A-1-13. The formulations are shown in Table 1 and are not further described here.

Synthesis Example A-2-1

A 500 ml four-necked Erlenmeyer flask was equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer, and nitrogen was introduced. Then, 6.77 g (0.04975 mol) of the diamine compound (a2-1-1) represented by formula (III-1), 0.1216 g (0.00025 mol) of the diamine compound (a2-2-3) represented by formula (IV-2), and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added and stirred at room temperature until dissolved. Next, 1.9608 g (0.005 mol) of the compound (a1-1-3) represented by formula (II-8), 9.8154 g (0.045 mol) of pyromellitic dianhydride (a1-2-1), and 20 g of NMP were added. After reacting at room temperature for 6 hours, 97 g of NMP, 2.55 g of acetic anhydride, and 19.75 g of pyridine were added, the temperature was raised to 60°C, and stirring was continued for 2 hours to allow the imidization reaction to proceed. After the reaction was complete, the reaction solution was poured into 1500 ml of water to precipitate the polymer. The resulting polymer was then filtered, washed with methanol, and filtered three times repeatedly. The polymer was then placed in a vacuum oven and dried at 60°C to obtain the polymer (A-2-1) of Synthesis Example A-2-1. Its formula is shown in Table 1.

Synthesis Examples A-2-2 to A-2-4

Synthesis Examples A-2-2 to A-2-4 use the same preparation method as the polymer (A-2-1) in Synthesis Example A-2-1. The difference lies in the changes in the types and amounts of raw materials used in the polymers. The formulations are shown in Table 1 and are not further described here.

Synthesis Example C-1

Synthesis Example C-1 uses the same preparation method and reactant molar ratio as the preparation method of the compound represented by formula (VI-74) above, except that Synthesis Example C-1 uses suberic acid ( ) is substituted for adipic acid to react with N-ethyl-2-oxoethanediamine. The compound obtained by the reaction has the structure shown in Formula (VI-32).

Synthesis Example C-2

First, 168.19 parts by weight of hexamethylene diisocyanate (reactant 1; ), 258.4 parts by weight of N-propyl-2-oxiranethylamine (Reactant 2; ) and 200 parts by weight of acetone (solvent), wherein the molar ratio of reactant 1 to reactant 2 is 1:2. A Dean-Stark tube is filled with acetone and heated to 30°C to allow the reaction to proceed. After 5 hours of reaction, the acetone is removed, and the resulting product is analyzed by 1H-NMR and IR to identify it as the target product. The compound prepared in Synthesis Example C-2 has the structure shown in Formula (VI-33).

Synthesis Example C-3

Synthesis Example C-3 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-1 above, except that Synthesis Example C-3 uses succinic acid ( ) substituted with suberic acid and N-propyl-2-oxiranethylamine ( ) is substituted with N-ethyl-2-epoxyethanemethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-6).

Synthesis Example C-4

Synthesis Example C-4 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-2, except that Synthesis Example C-4 uses dimethylene diisocyanate ( ) is substituted with hexamethylene diisocyanate to react with N-propyl-2-epoxyethaneethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-9).

Synthesis Example C-5

Synthesis Example C-5 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-1 above, except that Synthesis Example C-5 uses adipic acid ( ) substituted with suberic acid and N-ethyl-2-methylepoxypropaneethylamine ( ) is substituted with N-ethyl-2-epoxyethanemethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-23).

Synthesis Example C-6

Synthesis Example C-6 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-2, except that Synthesis Example C-6 uses dimethylene diisocyanate ( ) substituted with hexamethylene diisocyanate and N-propylene-7-oxobicyclo[4.1.0]3-heptylmethylamine ( ) substituted with N-propyl-2-epoxyethaneethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-12).

Synthesis Example C-7

Synthesis Example C-7 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-1, except that Synthesis Example C-7 uses 1,2-cyclohexanedicarboxylic acid ( ) substituted with suberic acid and N-propyl-2-oxiranbutylamine ( ) is substituted with N-ethyl-2-epoxyethanemethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-67).

Synthesis Example C-8

Synthesis Example C-8 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-2, except that Synthesis Example C-8 uses diphenylmethane diisocyanate ( ) substituted with hexamethylene diisocyanate and N-ethyl-2-oxiranethylamine ( ) substituted with N-propyl-2-oxoethaneethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-69).

Synthesis Example C-9

Synthesis Example C-9 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-1 above, except that Synthesis Example C-9 uses 1,4-phenylenediacetic acid ( ) substituted with suberic acid and N-methyl-7-oxabicyclo[4.1.0]heptane-3-amine ( ) is substituted with N-ethyl-2-epoxyethanemethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-71).

Synthesis Example C-10

Synthesis Example C-10 uses the same preparation method and reactant molar ratio as the preparation method of the compound of Synthesis Example C-2, except that Synthesis Example C-10 uses p-xylylenediisocyanate ( ) substituted with hexamethylene diisocyanate and N-ethyl-2-epoxypropane methylamine ( ) substituted with N-propyl-2-oxoethaneethylamine. The compound obtained by the reaction has the structure shown in Formula (VI-73).

Preparation of liquid crystal alignment agents, liquid crystal alignment films, and liquid crystal display devices

Example 1

Weigh 100 parts by weight of the polymer (A-1-1) prepared in Synthesis Example A-1-1, 800 parts by weight of NMP (B-1), and 1 part by weight of the compound represented by Formula (VI-32) (C-1), and stir and mix them at room temperature to prepare the liquid crystal alignment agent of Example 1.

The prepared liquid crystal alignment agent was spin-coated onto a glass substrate, which also had pixel electrodes formed on it. These were IPS driver electrodes consisting of a pair of ITO electrodes (electrode width: 10μm, electrode spacing: 10μm, electrode height: 50nm). The ITO electrodes each had a serrated shape, with the serrated portions of each electrode spaced and interlocking. The glass substrate coated with the liquid crystal alignment agent was then dried on an 80°C hot plate for 5 minutes and then baked in a 250°C hot air circulating oven for 60 minutes to form a 100nm thick coating.

The coated surface was irradiated with 254nm UV light through a polarizing plate to produce a substrate with a liquid crystal alignment film. Next, a similar coating was formed and an alignment treatment was performed on a counter substrate, a glass substrate without electrodes but with 4μm-high columnar spacers.

The two substrates are assembled into a set. A sealant is printed on one of the substrates, and the other is bonded together with the liquid crystal alignment film facing the other with the alignment angle at 0 degrees. The sealant is then cured to create an empty cell. This empty cell is then injected with liquid crystal MLC-2041 (Merck) using a reduced-pressure injection method, and the injection port is sealed, resulting in the liquid crystal display device of Example 1. The evaluation of rubbing bright spots in Example 1 was conducted on the aforementioned substrates with liquid crystal alignment films that had been irradiated with UV light. The results are shown in Table 2. The method for detecting rubbing bright spots is described later.

Examples 2 to 30 and Comparative Examples 1 to 5

Examples 2 through 30 and Comparative Examples 1 through 5 utilize the same preparation methods for the liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device as Example 1. The difference between Examples 2 through 30 and Comparative Examples 1 through 5 lies in the changes in the types and amounts of raw materials used in the liquid crystal alignment agent. Their formulations and evaluation results are shown in Table 2 and are not further described here.

Evaluation method

Low friction highlights

Low-friction bright spots were evaluated by UV-irradiating the substrates with liquid crystal alignment films obtained in Examples 1 to 30 and Comparative Examples 1 to 5. The substrates were mounted on a Bruker AXS UMT-2 instrument (with an FVL sensor and a 1.6mm sapphire ball mounted on the tip). The scratch test was conducted for 100 seconds at a force of 1mN to 20mN at a horizontal axis of 0.5mm (5mm/s) and a traverse distance of 2mm. MLC-2041 (Merck) was then dropped onto the substrates. 4μm spacers were then applied to the substrates with liquid crystal alignment films obtained in each of the above Examples and Comparative Examples, and the spacers were placed toward the side where the MLC-2041 was dropped. The substrate was sandwiched and the scratch test area was observed using a polarizing microscope (ECLIPSE E600WPOL, manufactured by Nikon) at a 90-degree angle to the polarizing plate. The light was observed to see if it was transmitted. Evaluation was performed based on the number of bright spots and the following criteria.

※: The number of tiny bright spots is 5 or less.

◎: The number of tiny bright spots is 6 to 9.

○: The number of tiny bright spots is between 10 and 12 o'clock.

△: The number of tiny bright spots is between 13 and 15.

╳: The number of tiny bright spots is 16 or more.

From the results in Table 2, it can be seen that if the liquid crystal alignment agent of the present invention does not contain the compound (C) represented by formula (I-1) or formula (I-2), the low-friction bright spot characteristics of the liquid crystal display element formed are poor. Among them, if _R2 and _R3 in the structures represented by formula (I-1) and formula (I-2) do not represent the structures represented by the aforementioned formula (I-3), formula (I-4) or formula (I-5), the low-friction bright spot characteristics of the liquid crystal display element formed are poor. Secondly, if at least one of _R2 and _R3 in formula (I-1) and formula (I-2) represents the structure represented by formula (I-3), the liquid crystal display element formed can have better low-friction bright spot characteristics. When R ₁ in the structures represented by formula (I-1) and formula (I-2) represents a linear aliphatic hydrocarbon group having 2 to 20 carbon atoms, the resulting liquid crystal display device can also have better low-friction bright spot characteristics.

Furthermore, if the tetracarboxylic dianhydride component (a1) of the polymer (A) contains a tetracarboxylic dianhydride compound (a1-1) represented by formula (II), the low-friction bright spot characteristics of the resulting liquid crystal display device can be further enhanced.

If the diamine component (a2) of the polymer (A) contains a diamine compound (a2-1) represented by formula (III), the resulting liquid crystal display device can have better low-friction bright spot characteristics.

Furthermore, when the diamine component (a2) comprises a diamine compound (a2-2) represented by formula (IV), the low-friction bright spot characteristics of the resulting liquid crystal display device can be further enhanced. In formula (IV), if at least one of _Z5 and _Z6 represents a specific structure represented by formula (IV'-1), the low-friction bright spot characteristics of the resulting liquid crystal display device can be further enhanced.

It should be noted that while the present invention uses specific compounds, compositions, reaction conditions, processes, analytical methods, or specific instruments as examples to illustrate the liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device of the present invention, anyone with ordinary skill in the art to which the present invention pertains will recognize that the present invention is not limited thereto. The liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device of the present invention may also be produced using other compounds, compositions, reaction conditions, processes, analytical methods, or instruments without departing from the spirit and scope of the present invention.

Although the present invention has been disclosed above in terms of embodiments, this is not intended to limit the present invention. Anyone with ordinary skill in the art to which the present invention pertains may make various modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the patent application attached hereto.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: First conductive film

116:The first liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

Claims (12)

A liquid crystal alignment agent comprises: a polymer (A) prepared by a polymerization reaction of a tetracarboxylic dianhydride component (a1) and a diamine component (a2); a solvent (B); and a compound (C) comprising a compound represented by the following formula (I-1) and/or formula (I-2): (I-1) (I-2) wherein _R1 represents an n-valent linear aliphatic alkyl group having 2 to 20 carbon atoms, an n-valent alicyclic alkyl group having 4 to 12 carbon atoms, or a group represented by formula (VI-A), a group represented by formula (VI-B), or a group represented by formula (VI-C); (VI-A) (VI-B) (VI-C) In formulas (VI-A) to (VI-C), "*" represents a bonding position; n represents 2; _R2 and _R3 each independently represent a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, a group represented by formula (I-3), a group represented by formula (I-4), or a group represented by formula (I-5), wherein at least one of _R2 and _R3 represents a group represented by formula (I-3), a group represented by formula (I-4), or a group represented by formula (I-5); (I-3) (I-4) (I-5) In formula (I-3), h represents an integer of 1 to 6; in formula (I-4), i represents an integer of 1 to 6, and R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; in formula (I-5), j represents an integer of 1 to 6. The liquid crystal aligner as described in claim 1, wherein at least one of R ₂ and R ₃ represents a group represented by formula (I-3). The liquid crystal alignment agent as described in claim 1, wherein the amount of the compound (C) used is 1 part by weight to 15 parts by weight based on 100 parts by weight of the polymer (A). The liquid crystal alignment agent as described in claim 1, wherein the tetracarboxylic dianhydride component (a1) comprises at least one tetracarboxylic dianhydride compound (a1-1) represented by formula (II): (II) wherein _X1 to _X4 independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group; _X1 to _X4 may be the same or different, and at least one of _X1 , _X2 , _X3 and _X4 is not a hydrogen atom. The liquid crystal alignment agent as described in claim 4, wherein the usage amount of the tetracarboxylic dianhydride component (a1) is 100 mol%, and the usage amount of the tetracarboxylic dianhydride compound (a1-1) is 10 mol% to 100 mol%. The liquid crystal alignment agent as described in claim 1, wherein the diamine component (a2) comprises a diamine compound (a2-1) represented by formula (III): (III) wherein Y ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and Y ₂ represents a linear alkyl group having 1 to 10 carbon atoms. The liquid crystal alignment agent as described in claim 6, wherein the usage amount of the diamine component (a2) is 100 mol%, and the usage amount of the diamine compound (a2-1) is 2 mol% to 99.5 mol%. The liquid crystal alignment agent as described in claim 1, wherein the diamine component (a2) comprises a diamine compound (a2-2) represented by formula (IV): (IV) wherein Z ₇ represents an oxygen atom or a sulfur atom; Z ₃ and Z ₄ each independently represent an alkylene group having 1 to 3 carbon atoms; Z ₁ and Z ₂ each independently represent a single bond, -O-, -S-, -OCO- or -COO-; and Z ₅ and Z ₆ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a group represented by formula (IV'), wherein at least one of Z ₅ and Z ₆ represents a group represented by formula (IV'): -GL (IV') In formula (IV'), G represents a single bond or a divalent hydrocarbon group having 1 to 4 carbon atoms; and L represents a protecting group that is substituted by a hydrogen atom by heat. The liquid crystal aligner as described in claim 8, wherein the group represented by formula (IV') is a group represented by formula (IV'-1): (IV'-1). The liquid crystal alignment agent as described in claim 8 or 9, wherein the usage amount of the diamine component (a2-2) is 0.5 mol% to 30 mol% based on 100 mol% usage amount of the diamine component (a2). A liquid crystal alignment film is formed using the liquid crystal alignment agent as described in any one of claims 1 to 10. A liquid crystal display element comprises the liquid crystal alignment film as described in claim 11.