TWI904388B - Liquid crystal alignment agent, method of producing the same, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, a method of producing the liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent includes a polymer (A) and a solvent (B). 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 flicker level after the element is driven.

Description

Liquid crystal alignment agent, its manufacturing method, liquid crystal alignment film and liquid crystal display element

This invention relates to a liquid crystal alignment agent, a method for manufacturing the same, a liquid crystal alignment film, and a liquid crystal display element, and particularly to a liquid crystal display element using the liquid crystal alignment agent to achieve a low degree of immediate flicker after driving.

Liquid crystal display elements used in LCD TVs, LCD monitors, etc., typically have a liquid crystal alignment film inside the element to control the alignment state of the liquid crystals. Currently, the most common industrial method is to produce this liquid crystal alignment film by rubbing a cloth such as cotton, nylon, or polyester on the electrode substrate in one direction. The film surface is formed by polyamide and/or polyimide with amide modified into polyamide.

Friction treatment of the alignment film surface during the alignment process is a relatively easy method for industrial production. However, with the increasing demands for high efficiency, high precision, and large size of liquid crystal display elements, various problems such as damage to the alignment film surface, dust, the effects of mechanical force and electrostatic force, and unevenness on the alignment surface have become more significant during the friction treatment.

As an alternative to tribological treatment, photoalignment, which utilizes ultraviolet radiation from polarized light to impart alignment energy to liquid crystals, is currently known. The so-called photoalignment liquid crystal alignment treatment includes substances that utilize photoisomerization, photocrosslinking, or photodecomposition reactions in their reaction mechanisms. Furthermore, Japanese Patent Application Publication No. 9-297313 proposes a photoalignment method using a polyimide film with an alicyclic structure such as cyclobutane in its main chain. When using polyimide as the alignment film for photoalignment, its heat resistance is higher than other types of alignment films, making its application promising.

Photoalignment is a non-frictional alignment process. Industrially, it not only has the advantage of being manufactured using a simple process, but also, in liquid crystal display devices driven by In-Plane-Switching (IPS) and Fringe Field Switching (FFS) technologies, compared to liquid crystal alignment films obtained by frictional methods, the liquid crystal alignment films obtained by photoalignment are expected to improve the contrast and viewing angle characteristics of the liquid crystal display devices. Therefore, photoalignment is a promising and highly anticipated liquid crystal alignment process.

However, when liquid crystal alignment films prepared by photoalignment are applied to liquid crystal display (LCD) elements, the resulting LCD elements still suffer from high flicker immediately after driving. This means that the accumulated charge in the LCD element prepared after illumination is slowly eliminated, leading to excessively high residual charge and consequently, image retention. Therefore, to meet the requirements of current photoaligned IPS LCD manufacturers, providing a liquid crystal alignment agent capable of forming LCD elements with low flicker immediately after driving is the goal of research in this field.

One aspect of the present invention is to provide a liquid crystal alignment agent comprising a polymer (A) and a solvent (B). This liquid crystal alignment agent can improve the immediate flicker level of the manufactured liquid crystal display element after driving. Furthermore, the liquid crystal alignment agent of the present invention may optionally include an additive (C).

Another aspect of the present invention is to provide a liquid crystal alignment film, which is formed using the aforementioned liquid crystal alignment agent.

Another aspect of the present invention is to provide a liquid crystal display element comprising the liquid crystal alignment film described above.

Based on the above description of the present invention, a liquid crystal alignment agent is proposed, wherein the liquid crystal alignment agent comprises a polymer (A) and a solvent (B), as detailed below.

Polymer (A)

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

The aforementioned polymer (A) is selected from the group consisting of polyamide (PAA), polyimide (PI), polyimide block copolymers and combinations thereof, and polymer (A) comprises the structure shown in formula (1) below. (1)

In formula (1), _W1 , _W2 and _W3 represent divalent organic groups of benzene ring or pyridine ring, _X1 represents oxygen atom or sulfur atom, _X2 represents divalent chain hydrocarbon with 1 to 30 carbon atoms or alicyclic hydrocarbon with 3 to 30 carbon atoms, _X3 and _X4 each independently represent single bond, oxygen atom, sulfur atom or _-NR1- , wherein at least one of _X3 and _X4 represents oxygen atom, sulfur atom or _-NR1- , _R1 represents hydrogen atom or methyl, when any of _W1 , _W2 and _W3 is pyridine ring, _X3 and _X4 do not represent single bond, and * represents bond position. If polymer (A) does not contain the structure shown in formula (1), the resulting liquid crystal alignment agent will increase the flicker level of the liquid crystal display element immediately after driving.

Preferably, _X2 represents a divalent chain hydrocarbon with 1 to 30 carbon atoms, more preferably a divalent chain hydrocarbon with 1 to 11 carbon atoms, and most preferably a linear alkyl group with 1 to 11 carbon atoms. When _X2 represents the aforementioned substituent, the resulting liquid crystal alignment agent results in a liquid crystal display element containing the liquid crystal alignment agent exhibiting a lower degree of flicker after driving.

In some embodiments, polymer (A) further comprises at least one of a group consisting of structures shown in equations (2), (3) and (4) below. The resulting liquid crystal alignment film can further reduce the immediate flickering of the liquid crystal display element after driving. (2)

In formula (2), _X5 and _X6 each independently represent a single bond, an oxygen atom, a sulfur atom, -OCO- or -COO-, _X7 and _X8 each independently represent an alkyl group having 1 to 3 carbon atoms, _X9 and _X10 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a protecting group that is replaced by a hydrogen atom by heat, wherein at least one of _X9 and _X10 represents a protecting group that is replaced by a hydrogen atom by heat, _X11 represents an oxygen atom or a sulfur atom, and * represents a bond position.

The structure shown in the aforementioned equation (3) is listed below: (3).

In equation (3), _X12 , _X13 , _X14 and _X15 are the same or different, _X12 , _X13 , _X14 and _X15 represent monovalent bases, the two _X16 are the same or different, _X16 represents divalent bases, _p1 represents an integer from 1 to 10, and * represents the bond position.

The structure shown in the aforementioned equation (4) is listed below: (4).

In equation (4), _X17 and _X18 represent divalent substituted or unsubstituted aromatic ring groups, _X17 and _X18 are the same, _X19 represents _-NR2- , _R2 represents a protecting group that is replaced by a hydrogen atom by heat, _X20 represents a single bond, an oxygen atom or a sulfur atom, _X21 represents a divalent organic group having a chain hydrocarbon with 1 to 15 carbon atoms or an alicyclic hydrocarbon with 3 to 15 carbon atoms, * represents a bond position, wherein when _X20 represents a sulfur atom, the number of carbon atoms in the divalent organic group represented by _X21 is not less than 2.

In equation (2), at least one of _X9 and _X10 represents the functional group shown in equation (2-1) below. (2-1)

In equation (2-1), _Y1 represents a single bond or a divalent organic group of hydrocarbon with 1 to 4 carbon atoms.

Preferably, the structure shown in equation (4) above includes the structure shown in equation (4-1) below. (4-1)

In formula (4-1), _Y2 and _Y3 represent divalent groups of benzene ring, pyridine ring or pyrimidine ring with two substituents, and _Y2 and _Y3 are the same; _Y4 represents _-NR3- ; _R3 represents a protecting group that is replaced by a hydrogen atom by heat; _Y5 represents a single bond, oxygen atom or sulfur atom; _m1 represents an integer from 1 to 5, where when _Y5 represents a sulfur atom, _m1 represents an integer from 2 to 5.

In equation (4), _R2 of _-NR2- represented by _X19 represents the functional group shown in equation (4-2) below. (4-2)

In equation (4-2), _Y1 represents a single bond or a divalent organic group of hydrocarbon with 1 to 4 carbon atoms. The explanations of equations (2) to (4) correspond to the explanations of equations (6) to (8) described later, respectively, in which similar group symbols (superscript and subscript) are used to represent the same group. For example, the group represented by " _X5 " in equation (2) is the same as the group represented by " ^X5 " in equation (6), so it will not be elaborated here.

Preferred examples of the aforementioned polymer (A) may be polyamide (PAA), polyimide (PI), polyimide-based block copolymers, or combinations thereof. Among these, preferred examples of polyimide-based block copolymers are polyamide block copolymers, polyimide block copolymers, polyamide-polyimide block copolymers, or any combination thereof.

Tetracarboxylic dianhydride component (a1)

Tetracarboxylic dianhydride compound (a1-1)

The tetracarboxylic dianhydride component (a1) of this invention comprises at least one tetracarboxylic dianhydride compound (a1-1) as shown in formula (I): (I)

In formula (I), _Ra1 to _Ra4 each 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 containing a fluorine atom and having 1 to 6 carbon atoms, or a phenyl group. _Ra1 to _Ra4 may be the same or different, and at least one of _Ra1 , _Ra2 , _Ra3 and _Ra4 is not a hydrogen atom.

When _Ra1 , _Ra2 , _Ra3 , and _Ra4 have a three-dimensional barrier structure, the resulting liquid crystal alignment agent will give the formed liquid crystal display element a higher degree of immediate flicker after driving. Therefore, _Ra1 , _Ra2 , _Ra3 , and _Ra4 are preferably hydrogen atoms, methyl groups, or ethyl groups, with methyl groups being more preferred.

Specific examples of tetracarboxylic dianhydride compounds (a1-1) as shown in formula (I) may be, for example, compounds shown in formulas (I-1) to (I-8). (I-1) (I-2) (I-3) (I-4) (I-5) (I-6) (I-7) (I-8)

The aforementioned tetracarboxylic acid dianhydride compound (a1-1) can be used alone or in combination of multiple compounds.

The amount of tetracarboxylic dianhydride component (a1) used is 100 mol, and the amount of tetracarboxylic dianhydride compound (a1-1) used is 10 mol to 100 mol, preferably 15 mol to 99 mol, and even more preferably 20 mol to 98 mol.

When the tetracarboxylic acid dianhydride component (a1) contains a tetracarboxylic acid dianhydride compound (a1-1) as shown in formula (I), the liquid crystal alignment film prepared by this liquid crystal alignment agent has better liquid crystal alignment properties.

Other tetracarboxylic dianhydride compounds (a1-2)

The tetracarboxylic dianhydride component (a1) of the present invention may selectively include other tetracarboxylic dianhydride compounds (a1-2). Preferred examples of other tetracarboxylic dianhydride compounds (a1-2) may be (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds as shown in formulas (II-1) to (II-6) below.

The aforementioned (1) aliphatic tetracarboxylic dianhydride compounds include, but are not limited to, aliphatic tetracarboxylic dianhydride compounds such as ethane tetracarboxylic dianhydride or butane tetracarboxylic dianhydride.

The aforementioned (2) alicyclic tetracarboxylic dianhydride compounds include, but are not limited to, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1, Alicyclic tetracarboxylic anhydride compounds such as 2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic dianhydride, 2,3,5-tricarboxylic cyclopentylacetic dianhydride, or dicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride.

Specific examples of the aromatic tetracarboxylic dianhydride compounds mentioned in (3) above may include, but are not limited to, 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, benzopyrene tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl sulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3, 3'-4,4'-Diphenylethanetetracarboxylic dianhydride, 3,3',4,4'-Dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3',4,4'-Tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-Furantetracarboxylic dianhydride, 2,3,3',4'-Diphenylethertetracarboxylic dianhydride, 3,3',4,4'-Diphenylethertetracarboxylic dianhydride, 4,4'-Bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 2,3,3',4'-Diphenyl Thiosulfide tetracarboxylic acid dianhydride, 3,3',4,4'-diphenyl thiosulfide tetracarboxylic acid dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic acid dianhydride, 2,2',3,3'-diphenyltetracarboxylic acid dianhydride, 2,3,3',4'-diphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenyltetracarboxylic acid dianhydride Anhydride, bis(phthalic acid)benzylphosphine oxide dianhydride, p-extrin-phenyl-bis(triphenylphthalic acid) dianhydride, m-extrin-phenyl-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-tetrahydrofuran tetracarboxylic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-methyl-5- (tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-methyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c] ]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl ... Hydrogen-8-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 5-(2,5-dioxytetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, etc.

Specific examples of the tetracarboxylic acid dianhydride compounds described in (4) above, as shown in formulas (II-1) to (II-6), are as follows: (II-1) (II-2) (II-3) (II-4) (II-5) (II-6)

In formula (II-5), _A1 represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; _A2 and _A3 may be the same or different, and may represent a hydrogen atom or an alkyl group, respectively. Preferably, the tetracarboxylic acid dianhydride compound shown in formula (II-5) may be selected from the compounds shown in formulas (II-5-1) to (II-5-3). (II-5-1) (II-5-2) (II-5-3)

In formula (II-6), _A4 represents a divalent group containing an aromatic ring; _A5 and _A6 may be the same or different, and respectively represent a hydrogen atom or an alkyl group. Preferably, the tetracarboxylic acid dianhydride compound shown in formula (II-6) may be selected from the compound shown in formula (II-6-1). (II-6-1)

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

The amount of tetracarboxylic dianhydride component (a1) used is 100 mol, and the amount of other tetracarboxylic dianhydride compounds (a1-2) used is 0 to 90 mol, preferably 1 to 85 mol, and even more preferably 2 to 80 mol.

Based on the following, the amount of diamine component (a2) used is 100 moles, and the amount of tetracarboxylic acid dianhydride component (a1) used ranges from 20 moles to 200 moles, and preferably from 30 moles to 180 moles.

Diamine component (a2)

Diamine compound (a2-1)

The diamine component (a2) of the present invention may include a diamine compound (a2-1) as shown in formula (5). (5)

In formula (5), ^W1 , ^W2 and ^W3 represent divalent organic groups of benzene ring or pyridine ring, ^X1 represents oxygen atom or sulfur atom, ^X2 represents divalent chain hydrocarbon with 1 to 30 carbon atoms or divalent alicyclic hydrocarbon with 3 to 30 carbon atoms, ^X3 and ^X4 each independently represent single bond, oxygen atom, sulfur atom or ^-NR1- , wherein at least one of ^X3 and ^X4 represents oxygen atom, sulfur atom or ^-NR1- , ^R1 represents hydrogen atom or methyl, and when any of ^W1 , ^W2 and ^W3 is pyridine ring, ^X3 and ^X4 do not represent single bond. If the diamine component (a2) does not contain the diamine compound (a2-1) shown in formula (5), the prepared liquid crystal alignment agent will increase the flicker level of the liquid crystal display element immediately after driving.

Preferably, ^X2 represents a divalent chain hydrocarbon having 1 to 30 carbon atoms; more preferably, ^X2 represents a divalent chain hydrocarbon having 1 to 11 carbon atoms; and most preferably, ^X2 represents a linear alkyl group having 1 to 11 carbon atoms. When ^X2 represents one of the aforementioned substituents, the resulting liquid crystal display element containing the liquid crystal alignment agent exhibits a lower degree of immediate flicker after driving.

The aforementioned "chain-like hydrocarbons" refer to linear or branched hydrocarbons that do not contain cyclic structures in their main chain, but are composed solely of chain-like structures. These hydrocarbons can be saturated or unsaturated. The aforementioned "alicyclic hydrocarbons" refer to hydrocarbons that contain alicyclic structures but do not contain aromatic ring structures. However, they are not necessarily composed solely of alicyclic hydrocarbons; some may have even more chain-like structures.

In specific examples of chain hydrocarbons having 1 to 30 carbon atoms, these hydrocarbons may include saturated and unsaturated chain hydrocarbons. Saturated chain hydrocarbons may be saturated straight-chain or branched hydrocarbons. Saturated straight-chain hydrocarbons may include methylene, ethyl, propylene, butyl, pentyl, hexadiyl, heptadiyl, octyl, nonadiyl, decadiyl, dodecanediyl, tetradecanediyl, pentadecanediyl, hexadecanediyl, and octadecanediyl. Saturated branched hydrocarbons may include dibutanediyl, tributanediyl, isopentanediyl, tripentanediyl, isooctanediyl, 2-ethylhexanediyl, trioctanediyl, isononanediyl, and isodecanediyl.

Unsaturated chain hydrocarbons may comprise unsaturated chain hydrocarbons having unsaturated bonds (such as alkene and/or alkynyl bonds), and these groups may be straight-chain or branched. Examples include: vinyldiyl, heptendiyl, 2-butendiyl, 3-methyl-4-ethyl-1-hexendiyl, propyndiyl, 2-hexyndiyl, 3-methyl-1-pentyndiyl, 3-ethyl-1-hepyndiyl, and 3,5-dimethyl-4-hexen-1-hepyndiyl. Furthermore, specific examples of alicyclic hydrocarbons having 3 to 30 carbon atoms may include cyclobutadiyl, cyclopentadiyl, cyclohexanediyl, cycloheptanediyl, and groups on which hydrogen atoms are substituted.

Specific examples of diamine compounds (a2-1) as shown in formula (5) are described in detail below: (5-1) (5-2) (5-3) (5-4) (5-5) (5-6) (5-7) (5-8) (5-9) (5-10) (5-11) (5-12) (5-13) (5-14) (5-15) (5-16) (5-17) (5-18) (5-19) (5-20) (5-21) (5-22) (5-23) (5-24) (5-25) (5-26) (5-27) (5-28) (5-29) (5-30) (5-31) (5-32) (5-33)

In formulas (5-1), (5-3), (5-5), (5-6), (5-8), (5-14) and (5-24) to (5-34) above, Ra represents a hydrogen atom or a methyl group, but is not limited to these and may also represent other groups.

In the synthesis of a fully obtained polymer (A) (such as polyamide (PAA)), the amount of the diamine-based component (a2) used is 100 mol percent, and the amount of the diamine compound (a2-1) as shown in formula (5) above is 5 mol percent to 60 mol percent, preferably 7 mol percent to 50 mol percent, and even more preferably 10 mol percent to 40 mol percent.

The main synthetic methods for these diamine components (a2) are described below in detail. The methods described below are examples and are not limited thereto.

As shown in the following reaction formula (a), the diamine compound (a2-1) of the present invention is prepared by reducing a dinitro compound to convert a nitro group into an amino group. This reaction formula describes the diamine compound (a2-1-1) of the embodiment, which is only illustrative. Reaction (A)

There are no particular limitations on the reduction methods for dinitro compounds. Examples include using palladium-carbon, platinum oxide, Raney nickel, platinum black, rhodium-alumina, and platinum-carbon sulfide as catalysts in solvents such as ethyl acetate, toluene, tetrahydrofuran, dioxane, and alcohols, with reduction using hydrogen, hydrazine, and hydrogen chloride. High-pressure reactors can also be used as needed, and the process can be carried out under pressure. On the other hand, when the substituents of the hydrogen atoms in the substituted benzene ring or saturated hydrocarbon contain unsaturated bonds, the unsaturated bonds may be reduced to saturated bonds when using palladium-carbon or platinum-carbon. Therefore, the preferred reduction conditions are those using transition metals such as reducing iron, tin, and tin chloride as catalysts.

In the synthesis of dinitro compounds, as shown in reaction formula (b), dinitro compounds can be obtained by reacting commercially available diphenyl ether derivatives, phenoxypyridine derivatives, or dipyridine ether derivatives with nitrobenzene or nitrobyridine substituted with a leaving group (X). Preferred leaving groups (X) may include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, toluene sulfonates (-OTs), and methanesulfonates (-OMs). Reaction (B)

The above reaction can be carried out in the presence of an alkali. The alkali used is not particularly limited as long as it can be synthesized; examples include inorganic alkalis such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alkoxide, potassium alkoxide, sodium hydroxide, potassium hydroxide, and sodium hydroxide; and organic alkalis such as pyridine, dimethylaminopyridine, trimethylamine, triethylamine, and tributylamine. Depending on the circumstances, the yield can be increased by using palladium catalysts such as dibenzylacetone palladium or diphenylphosphine ferrocene palladium, or copper catalysts. From the perspective of ease of synthesis, the method using potassium carbonate is preferred, but other methods are also possible, therefore the synthesis method is not particularly limited.

Diamine compound (a2-2)

The diamine component (a2) of the present invention may further include at least one of a group consisting of a diamine compound (a2-2) as shown in formula (6), a diamine compound (a2-3) as shown in formula (7), and a diamine compound (a2-4) as shown in formula (8). (6)

In formula (6), ^X5 and ^X6 each independently represent a single bond, an oxygen atom, a sulfur atom, -OCO- or -COO-, ^X7 and ^X8 each independently represent an alkyl group having 1 to 3 carbon atoms, X9 and ^X10 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a protecting group that is replaced by a hydrogen atom by heat, wherein at least one of ^{X9 and X10} represents a protecting group that is replaced by a hydrogen atom by heat, and ^X11 represents an oxygen atom or a sulfur atom.

When at least one of ^X9 and ^X10 represents the functional group shown in formula (6-1), the liquid crystal alignment film can further reduce the flicker level of the liquid crystal display element immediately after driving. (6-1)

In equation (6-1), ^Y1 represents a single bond or a divalent organic group of hydrocarbon with 1 to 4 carbon atoms.

The aforementioned alkyl groups having 1 to 3 carbon atoms can be straight-chain or branched alkyl groups, and can be, for example, methyl, ethyl, propyl, 1-methylethyl, or 2-methylethyl. From the viewpoint of minimizing immediate flickering after driving, it is preferable to select a structure with more freely rotating parts and less steric hindrance. For example, the alkyl groups having 1 to 3 carbon atoms are preferably methyl, ethyl, or propyl.

In equation (6), ^X5 and ^X6 are preferably selected from the viewpoint of low flickering degree immediately after driving. ^X5 and ^X6 are preferably selected from the structure with softness and low steric resistance. Therefore, ^X5 and ^X6 are preferably single bonds, oxygen atoms or sulfur atoms.

In order to form a high-density film and a stronger liquid crystal alignment film, the structure between the (thio)urea group and the benzene ring is preferably symmetrical with the (thio)urea group as the center. ^-X5 - ^X7- and ^-X8 - ^X6- preferably have the same structure. In addition, the diamine compound (a2-2) shown in formula (6) is preferably a compound as shown in formulas (6-2) to (6-4). In formula (6-2) below, _Z81 and _Z91 represent alkyl groups having 1 to 3 carbon atoms and have the same number of carbon atoms. In formula (6-3) below, _Z82 and _Z92 represent alkyl groups having 1 to 3 carbon atoms and have different numbers of carbon atoms. In formula (6-4) below, _Z83 and _Z93 each independently represent alkyl groups having 1 to 3 carbon atoms. (6-2) (6-3) (6-4)

In formulas (6-2) to (6-4), ^X9 and ^X10 are defined as previously stated and will not be repeated here. At least one of ^X9 and ^X10 represents a protecting group that is replaced by a hydrogen atom by heat. The protecting group that is replaced by a hydrogen atom by heat can be, for example, an amino carbamate protecting group, a amide protecting group, an imine protecting group, or a sulfonamide protecting group. Specific examples include, for example, tert-butoxycarbonyl, benzoxycarbonyl, 1,1-dimethyl-2-haloethoxycarbonyl, 1,1-dimethyl-2-cyanoethoxycarbonyl, 9-fluorenylmethoxycarbonyl, allyloxycarbonyl, and 2-(trimethylsilyl)ethoxycarbonyl.

Specific examples of the diamine compound (a2-2) shown in formula (6) above can be the diamine compounds shown in formulas (6-a-1) to (6-a-40) below. (6-a-1) (6-a-2) (6-a-3) (6-a-4) (6-a-5) (6-a-6) (6-a-7) (6-a-8) (6-a-9) (6-a-10) (6-a-11) (6-a-12) (6-a-13) (6-a-14) (6-a-15) (6-a-16) (6-a-17) (6-a-18) (6-a-19) (6-a-20) (6-a-21) (6-a-22) (6-a-23) (6-a-24) (6-a-25) (6-a-26) (6-a-27) (6-a-28) (6-a-29) (6-a-30) (6-a-31) (6-a-32) (6-a-33) (6-a-34) (6-a-35) (6-a-36) (6-a-37) (6-a-38) (6-a-39) (6-a-40)

In equations (6-a-1) to (6-a-40), Boc represents the structure shown in equation (6-1).

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

Diamine compounds (a2-3)

The diamine compound (a2-3) of the present invention has the structure shown in formula (7). (7)

In equation (7), ^X12 , ^X13 , ^X14 and ^X15 are the same or different, ^X12 , ^X13 , ^X14 and ^X15 represent monovalent bases, the two ^X16 are the same or different, ^X16 represents divalent bases, and ^p1 represents an integer from 1 to 10.

Specific examples of diamine compounds (a2-3) shown in formula (7) include compounds such as 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(4-aminobutyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetraphenyldisiloxane, 1,3-bis(4-amino-3-methylphenyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(3-aminopropyl)-1,3-diphenyl-1,3-dimethyldisiloxane, or 1,5-bis(3-aminopropyl)-1,3,3,5-tetraphenyl-1,5-dimethyltrisiloxane. Among them, the diamine compounds (a2-3) are preferably 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetraphenyldisiloxane and 1,5-bis(3-aminopropyl)-1,3,3,5-tetraphenyl-1,5-dimethyltrisiloxane.

Diamine compounds (a2-4)

The diamine compound (a2-4) of the present invention has the structure shown in formula (8). (8)

In formula (8), ^X17 and ^X18 represent divalent substituted or unsubstituted aromatic ring groups, ^X17 and ^X18 are the same, ^X19 represents ^-NR2- , ^R2 represents a protecting group that is replaced by a hydrogen atom by heat, ^X20 represents a single bond, an oxygen atom or a sulfur atom, and ^X21 represents a divalent organic group having a chain hydrocarbon with 1 to 15 carbon atoms or an alicyclic hydrocarbon with 3 to 15 carbon atoms, wherein when ^X20 represents a sulfur atom, the number of carbon atoms in the divalent organic group represented by ^X21 is not less than 2.

In formula (8), ^X17 and ^X18 are groups formed by removing two hydrogen atoms from the ring portion of an aromatic ring, and may also have substituents in the ring portion. Examples of aromatic rings include: aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, and biphenyl ring; and nitrogen-containing heterocyclic rings such as pyridine ring, pyrimidine ring, pyrazine ring, and pyridazine ring. The substituents in the aromatic ring may be, for example, alkyl groups having 1 to 6 carbon atoms. When ^X17 and ^X18 are the same, it is possible to easily synthesize monomers for manufacturing polymer (A) and reduce the immediate flickering of liquid crystal display elements after driving. ^X17 and ^X18 are preferably groups formed by removing two hydrogen atoms from the ring portion of a substituent benzene ring, biphenyl ring, pyridine ring or pyrimidine ring, in order to obtain a liquid crystal display element with a lower degree of immediate flicker after driving.

In equation (8), when X ¹⁹ represents -NR ² -, R ² represents a protecting group that is replaced by a hydrogen atom by heat, and X ²⁰ represents a single bond, oxygen atom, or sulfur atom, the immediate flickering degree after driving can be reduced. The protecting group represented by R ² is preferably a carbamate-based protecting group, a amide-based protecting group, an imine-based protecting group, or a sulfonamide-based protecting group. The protecting group represented by R ² can be a functional group as shown in equation (8-1), and the aforementioned protecting group is a high-temperature leaving group, reducing the amount of deprotected portion remaining in the liquid crystal alignment film. When R ² represents a protecting group that is replaced by a hydrogen atom by heat, the immediate flickering degree after driving caused by photodegradants can be further reduced. (8-1)

In equation (8-1), ^Y1 represents a single bond or a divalent organic group of hydrocarbons with 1 to 4 carbon atoms.

In equation (8), X ²¹ represents a divalent organic group having a chain hydrocarbon structure with 1 to 15 carbon atoms or an alicyclic hydrocarbon structure with 3 to 15 carbon atoms. Here, "chain hydrocarbon structure" refers to a linear hydrocarbon structure and a branched hydrocarbon structure that contain only chain structures and does not contain cyclic structures. The chain hydrocarbon structure can be saturated or unsaturated. "Alicyclic hydrocarbon structure" refers to a hydrocarbon structure that contains only alicyclic hydrocarbon structures as ring structures and does not contain aromatic ring structures. The alicyclic hydrocarbon structure does not necessarily include only the alicyclic hydrocarbon structure, but also includes a portion of it having a chain structure. In some embodiments, when X ²⁰ represents a sulfur atom, the number of carbon atoms in the divalent organic group represented by X ²¹ is not less than 2. When X ²¹ represents the aforementioned divalent organic group, the liquid crystal alignment film made by this liquid crystal alignment agent can further reduce the immediate flickering degree of the liquid crystal display element after driving.

Preferably, the diamine compound (a2-4) shown in formula (8) above comprises the diamine compound shown in formula (8-2) below. (8-2)

In formula (8-2), ^Y2 and ^Y3 represent divalent groups of benzene, pyridine, or pyrimidine rings with two substituents, and ^Y2 and ^Y3 are the same; ^Y4 represents ^-NR3- ; ^R3 represents a protecting group that is replaced by a hydrogen atom by heat; ^Y5 represents a single bond, an oxygen atom, or a sulfur atom; and ^m1 represents an integer from 1 to 5, where ^m1 represents an integer from 2 to 5 when ^Y5 represents a sulfur atom. When ^Y2 and ^Y3 represent the aforementioned divalent groups and ^m1 represents the aforementioned integers, the flicker level of the liquid crystal display element containing the prepared liquid crystal alignment film can be further reduced immediately after driving.

In formula (8-2), when ^Y4 represents ^-NR3- and ^Y5 represents a single bond, oxygen atom, or sulfur atom, the crystallinity of the photodegradation product of polymer (A) can be reduced, thereby reducing the degree of flashing immediately after driving. ^R3 represents a protecting group that is replaced by a hydrogen atom by heat. The protecting group is preferably a high-temperature leaving group, and specific examples may include urethane-based protecting groups, amide-based protecting groups, amide-imine-based protecting groups, and sulfonamide-based protecting groups, wherein ^R3 represents a functional group as shown in the aforementioned formula (8-1).

In terms of reducing the immediate flickering after activation, the bonding positions of ^Y4 and ^Y5 in formula (8-2) on the benzene ring, pyridine ring, or pyrimidine ring represented by ^Y2 and ^Y3 , respectively, are preferably para positions relative to the nitrogen atom in formula (8-2). The diamine compound shown in formula (8-2) is preferably the diamine compound shown in formula (8-3). (8-3)

In equation (8-3), Q1 and Q2 independently represent -CH- or nitrogen atoms, respectively. The definitions of ^Y4 , ^Y5 and ^m1 are as described above and will not be repeated here.

Specific examples of the aforementioned diamine compounds (a2-4) are shown in the compounds represented by formulas (8-1-1) to (8-1-10). Specific diamine compounds (a2-4) can be synthesized using suitable general methods of combination organic chemistry. Furthermore, specific diamine compounds (a2-4) can be used alone or in combination of two or more. In formulas (8-1-1) to (8-1-10), _Rb represents a t-butyloxy carbonyl group. (8-1-1) (8-1-2) (8-1-3) (8-1-4) (8-1-5) (8-1-6) (8-1-7) (8-1-8) (8-1-9) (8-1-10)

When the diamine component (a2) further includes at least one of the group consisting of diamine compound (a2-2) as shown in formula (6), diamine compound (a2-3) as shown in formula (7) and diamine compound (a2-4) as shown in formula (8), the liquid crystal alignment film made by this liquid crystal alignment agent can further reduce the flicker level of the liquid crystal display element immediately after driving.

Based on the use of diamine component (a2) at 100 mol percent, the total use of diamine compound (a2-2) as shown in formula (6), diamine compound (a2-3) as shown in formula (7) and diamine compound (a2-4) as shown in formula (8) is 2 mol percent to 95 mol percent, preferably 2.5 mol percent to 93 mol percent, and even more preferably 3 mol percent to 90 mol percent.

Other diamine compounds (a2-5)

In addition to the aforementioned diamine compounds (a2-1) to (a2-4), the diamine component (a2) of the present invention may optionally include other diamine compounds (a2-5).

Other diamine compounds that can be used (a2-5) include aliphatic diamines, alicyclic diamines, aromatic diamines, and diamino organosilicones. Specific examples of these other diamines include aliphatic diamines such as 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, and 1,12-diaminododecane. Alicyclic diamines include, for example, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane and bis(4-amino-3-methylcyclohexyl)methane. Aromatic diamines include, for example, p-diaminobenzene, 2,5-dimethyl-p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 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-diaminoresorcinol, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis... (4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, 4,4'-thiodiphenylamine, 3,3'-thiodiphenylamine, 4,4'-bis(4-aminophenoxy)diphenylamine, 1,5-diaminonaphthalene, 1,4-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 4,4'-diaminonaphthalene Benzene, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 2,2'-dimethyl-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'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4 '-Diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 9,10-bis(4-aminophenyl)anthracene, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, bis(4-aminophenyl)silane, bis(3-aminophenyl)silane, dimethylbis(4-aminophenyl)silane, Dimethylbis(3-aminophenyl)silane, 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'-diaminobenzophenone, 2,2'-diaminobenzophenone, 2,3'-diaminobenzophenone, 4,4'-diaminodiphenyl Methane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylmethane, 2,3'-diaminodiphenylmethane, bis(3,5-diethyl-4-aminophenyl)methane, 1,2-bis(4-aminophenyl)ethane, 1,2-bis(3-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,3-bis(3-aminophenyl)propane, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(3-aminophenyl)propane, 2,2'-bis(3- (amino-4-methylphenyl)propane, 1,3-bis(4-aminophenoxy)propane, 1,3-bis(3-aminophenoxy)propane, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)butane, 1,4-bis(3-aminophenoxy)butane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(3-aminophenyl)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)octane, 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)decane Monoalkyl, 1,12-(4-aminophenoxy)dodecane, 1,12-(3-aminophenoxy)dodecane, 4,4'-diaminodiphenylamine, 3,3'-diaminodiphenylamine, 3,4'-diaminodiphenylamine, 2,2'-diaminodiphenylamine, 2,3'-diaminodiphenylamine, 4,4'-sulfonyldiphenylamine, 3,3'-sulfonyldiphenylamine, 4,4'-(p-phenylene diisopropylidene)diphenylamine, 4,4'-(m-phenylene diisopropylidene)diphenylamine, 4,4'-[1,4-phenylene di(methylene)]diphenylamine, 4 3,4'-[1,3-phenylene di(methylene)]diphenylamine, 3,4'-[1,4-phenylene di(methylene)]diphenylamine, 3,4'-[1,3-phenylene di(methylene)]diphenylamine, 3,3'-[1,4-phenylene di(methylene)]diphenylamine, 3,3'-[1,3-phenylene di(methylene)]diphenylamine, 1,4-benzobis[(4-aminophenyl)m-methyl ketone], 1,4-benzobis[(3-aminophenyl)m-methyl ketone], 1,3-benzylbis[(4-aminophenyl)m-methyl ketone], 1,3- Benzobis[(3-aminophenyl)m-methyl ketone], 1,4-benzobis(4-aminobenzoate), 1,4-benzobis(3-aminobenzoate), 1,3-benzobis(4-aminobenzoate), 1,3-benzobis(3-aminobenzoate), bis(4-aminophenyl) terephthalate, bis(3-aminophenyl) terephthalate, 3,5-diaminobenzoic acid, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,2'-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2' -bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(3-aminophenyl)hexafluoropropane, 2,2'-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminothiazide, N-methyl-3,6-diaminothiazide, N-ethyl-3,6-diaminothiazide, N-phenyl-3,6-diaminothiazide, 1,4-bis-(4-aminophenyl)-piperazine, 1-(4-aminophenyl)-2,3- Dihydro-1,3,3-trimethyl-1H-indene-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine, cholestyryloxy-3,5-diaminobenzene, cholestyryloxy-3,5-diaminobenzene, cholestyryloxy-2,4-diaminobenzene, cholestyryloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid alkyl ester, 3,5-diaminobenzoic acid alkyl ester, 3,5-diaminobenzoic acid lanosteryl ester, 3,6-bis(4-aminobenzoyloxy) 3,6-bis(4-aminophenoxy)cholestan, 3-(3,5-diaminophenoxy)cholestan, 3,6-bis(4-aminobenzyloxy)cholestan, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 4-(4'-trifluoromethylbenzoyloxy)cyclohexyl-3,5-diaminobenzoate, bis(4-aminophenyl)isophthalate, bis(3-aminophenyl)isophthalate, N,N'-(1,4-phenylene)bis(4-aminobenzoylamine), N,N N,N'-(1,3-phenylene)bis(4-aminobenzoxylamine), N,N'-(1,4-phenylene)bis(3-aminobenzoxylamine), N,N'-(1,3-phenylene)bis(3-aminobenzoxylamine), N,N'-bis(4-aminophenyl)terephthalamide, N,N'-bis(3-aminophenyl)terephthalamide, N,N'-bis(4-aminophenyl)m-phthalamide, N,N'-bis(3-aminophenyl)m-phthalamide, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane Hexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenoxy)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, 2,4-diamino-N,N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine, 1,3-diamino-4-octadecyloxybenzene, and compounds represented by formula (III) below. (III)

In formula (III), _D1 and _D2 represent single bonds, -O-, -COO-, or -OCO-, respectively; _E1 represents an alkyldiyl group with 1 to 3 carbon atoms; _E2 represents a single bond or an alkyldiyl group with 1 to 3 carbon atoms; a represents 0 or 1; b represents an integer from 0 to 2; c represents an integer from 1 to 20; and d represents 0 or 1, but a and b do not both represent 0. Specific examples of diamino organosilicones include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

In equation (III) above The divalent group represented is preferably an alkyl group with 1 to 3 carbon atoms, -O-, #-COO- or _{-OC2H4 -} O-, where "#" indicates the bond with the diaminophenyl group.

Specific examples of "-C _c H _2c+1 " include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecanyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecanyl, and n-eicosyl. Furthermore, in formula (III) above, preferably, the two amino groups of the diaminophenyl are located at the 2,4- or 3,5-positions relative to the other substituents.

Specific examples of compounds represented by formula (III) above can be listed below as compounds represented by formulas (III-1) to (III-4). (III-1) (III-2) (III-3) (III-4)

There are no particular restrictions on the amount of other diamine compounds (a2-5) used. For example, based on the use of 100 moles of diamine component (a2), the use of other diamine compounds (a2-5) can be from 0 moles to 95 moles, preferably from 0 moles to 93 moles, and even more preferably from 0 moles to 90 moles.

The other diamine compounds (a2-5) mentioned above can be used alone or in combination.

Molecular weight regulators

When synthesizing polymer (A), it can also be synthesized together with the aforementioned tetracarboxylic dianhydride component (a1) and diamine component (a2) using an appropriate molecular weight regulator to synthesize a terminal-modified polymer (A). By preparing a terminal-modified polymer, the aforementioned effect of reducing the immediate flickering degree after driving can be preserved, and the coatability (such as printability) of the liquid crystal alignment agent can be further improved.

Molecular weight modifiers may include (1) monocarboxylic anhydrides, (2) monoamine compounds, and (3) monoisocyanate compounds. Specific examples of these compounds include (1) maleic anhydrides such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, and n-hexadecylsuccinic anhydride. (2) Monoamine compounds may include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptaneamine, and n-octylamine, n-nonylamine, n-decylamine, n-undecaneamine, n-dodecaneamine, n-tridecaneamine, n-tetradecaneamine, n-pentadecananeamine, n-hexadecaneamine, n-heptadecaneamine, n-octadecaneamine, and n-eicosylamine. (3) Monoisocyanate compounds may include phenyl isocyanate and naphthyl isocyanate.

The total amount of tetracarboxylic acid dianhydride component (a1) and diamine component (a2) used is 100 parts by weight, and the amount of molecular weight regulator used is 20 parts by weight or less, and preferably 10 parts by weight or less.

Method for preparing polymer (A)

Polyamide (PAA)

The polyamide (PAA) of this invention can be prepared by reacting a tetracarboxylic dianhydride component (a1) and a diamine component (a2) together with a molecular weight regulator, as needed. The preferred ratio of tetracarboxylic dianhydride component (a1) to diamine component (a2) used in the synthesis reaction is 1 equivalent to the amino group of the diamine compound and 0.2 to 2 equivalents to the anhydride group of the tetracarboxylic dianhydride.

The synthesis reaction of polyamide (PAA) of polymer (A) is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 hours to 24 hours. The organic solvent used in the reaction may be such as aprotic polar solvent, phenolic solvent, alcohol, ketone, ester, ether, halogenated hydrocarbon, and hydrocarbon. Preferred organic solvents are one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide (DMF), dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoric acid triamine, m-cresol, xylenol and halogenated phenols, or a mixture of at least one of these solvents with other organic solvents (e.g., butyl solvent and diethylene glycol diethyl ether).

Preferably, the amount of organic solvent used, determined by the amount of tetracarboxylic acid dianhydride component (a1) and diamine component (a2) relative to the total amount of the reaction solution, is between 0.1% and 50% by weight. The reaction solution obtained by dissolving polymer (A) can be directly used in the preparation of the liquid crystal alignment agent, or the polymer (A) contained in the reaction solution can be separated and then used in the preparation of the liquid crystal alignment agent.

Polyimide (PI)

The polyimide (PI) of this invention can be obtained by dehydrating and cyclizing the aforementioned synthesized polyvinylamine (PAA) and then amide-imidizing it. The polyimide (PI) can be a fully amide-imidized product obtained by dehydrating and cyclizing all the amide structure of the polyvinylamine (PAA) as its precursor, or it can be a partially amide-imidized product where only a portion of the amide structure is dehydrated and cyclized, resulting in the coexistence of the amide structure and the amide ring structure. Preferably, the amide-imidization rate of the polyimide (PI) is 40% to 100%, more preferably 60% to 90%. The amide ratio is expressed as a percentage relative to the total number of amide structures and amide ring structures in polyimide (PI), representing the proportion of the number of amide ring structures. Here, a portion of the amide ring may also be an isoamide ring.

The dehydration and ring-closing of polyimide (PI) is preferably carried out by the following method: dissolving polyamide (PAA) in an organic solvent, adding a dehydrating agent and a dehydration ring-closing catalyst to the solution, and heating as needed. Examples of dehydrating agents include acetic anhydride, propionic anhydride, and trifluoroacetic anhydride. The amount of dehydrating agent used is 0.01 mol to 20 mol, preferably 1 mol, relative to the acetic acid structure of PAA. Examples of dehydration ring-closing catalysts include tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine. The amount of dehydrating ring-closing catalyst used is preferably 0.01 mol to 10 mol, relative to 1 mol of dehydrating agent. Examples of organic solvents used in the synthesis of polyamide (PAA) can be listed. The reaction temperature of the dehydration ring-closing reaction is preferably 0°C to 180°C, and the reaction time is preferably 1.0 hour to 120 hours. The resulting reaction solution containing polyimide (PI) can be used directly in the preparation of liquid crystal alignment agents, or the polyimide (PI) can be separated before use in the preparation of liquid crystal alignment agents.

Polyimide block copolymer

The preparation of the polyimide-based block copolymer of the present invention can be carried out by a general method. Preferably, the preparation method of the polyimide-based block copolymer first dissolves the starting material in a solvent and carries out a polycondensation reaction. The starting material includes at least one polyamide (PAA) and/or at least one polyimide (PI) mentioned above, and may further include a tetracarboxylic dianhydride component (a1) and a diamine component (a2).

The tetracarboxylic acid dianhydride component (a1) and diamine component (a2) in the aforementioned starting material are the same as those used in the preparation of polyacrylic acid (PAA) above, and the solvent used in the polycondensation reaction can be the same as the solvent in the liquid crystal alignment agent described below, which will not be elaborated here.

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

Preferably, the starting material comprises, but is not limited to, (1) two polyamides (PAA) with different terminal groups and different structures; (2) two polyimides (PI) with different terminal groups and different structures; (3) polyamides (PAA) and polyimides (PI) with different terminal groups and different structures; (4) polyamides (PAA), tetracarboxylic dianhydride compounds and diamine compounds, wherein at least one of the tetracarboxylic dianhydride compounds and diamine compounds is related to the form (5) Polyimide (PI), a tetracarboxylic acid dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic acid dianhydride compound and the diamine compound has a different structure from that of the tetracarboxylic acid dianhydride component (a1) and the diamine component (a2) used to form polyimide (PI); (6) Polyimide (PAA), polyimide (PI) (i) a tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine is structurally different from the tetracarboxylic dianhydride component (a1) and the diamine component (a2) used to form polyamide (PAA) or polyimide (PI); (7) two structurally different polyamide (PAA), tetracarboxylic dianhydride compound and diamine compound; (8) two structurally different polyimide (PI) and tetracarboxylic dianhydride compound. (9) Two polyamides (PAA) with anhydride-terminated groups and different structures and diamine compounds; (10) Two polyamides (PAA) with amino-terminated groups and different structures and tetracarboxylic dianhydride compounds; (11) Two polyimides (PI) with anhydride-terminated groups and different structures and diamine compounds; (12) Two polyimides (PI) with amino-terminated groups and different structures and tetracarboxylic dianhydride compounds.

When preparing a solution with a concentration of 10% by weight, the solution viscosity of polymer (A) is preferably between 10 mPa·s and 800 mPa·s, and more preferably between 15 mPa·s and 500 mPa·s. Furthermore, the solution viscosity is the value measured at 25°C using a type E rotational viscometer for a polymer solution with a concentration of 10% by weight prepared using a good solvent for polymer (A) (e.g., γ-butyrolactone and N-methyl-2-pyrrolidone).

The polymer (A) has a weight-average molecular weight converted from polystyrene, as determined by gel permeation chromatography, of 10,000 to 90,000, more preferably 12,000 to 75,000, and even more preferably 15,000 to 60,000.

Liquid crystal alignment agent

The liquid crystal alignment agent of the present invention comprises a polymer (A) and a solvent (B). Furthermore, the liquid crystal alignment agent of the present invention may optionally include an additive (C).

Polymer (A)

The aforementioned polymer (A) is selected from the group consisting of polyamide (PAA), polyimide (PI), polyimide block copolymers and combinations thereof.

The proportion of polyimide block copolymer used relative to the total amount of all polymers used in the liquid crystal alignment agent is preferably 1% to 90% by weight, more preferably 10% to 80% by weight, and most preferably 20% to 70% by weight.

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 synthesis of polyacrylic acid (PAA) mentioned above. At the same time, the solvent used in the synthesis of polyacrylic acid (PAA) mentioned above can also be used.

Specific examples of solvent (B) include, but are not limited to, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, γ-butyrolactamine, 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) may be used alone or in combination of multiple solvents.

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

The solid content concentration in the liquid crystal alignment agent (the percentage of the total weight of components other than the solvent in the liquid crystal alignment agent to the total weight of the liquid crystal alignment agent) can be appropriately selected considering factors such as viscosity and volatility, and is preferably in the range of 1% to 10% by weight. That is, the liquid crystal alignment agent is coated onto the substrate surface as described later, and preferably heated to form a coating that serves as a liquid crystal alignment film or a coating that forms a liquid crystal alignment film. At this time, when the solid content concentration is between 1% and 10% by weight, the film thickness is suitable to obtain a good liquid crystal alignment film.

The proportion of polymer (A) in the liquid crystal alignment agent relative to 100 parts by weight of the total solid components (other than solvent) in the liquid crystal alignment agent is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, and even more preferably 30 parts by weight or more.

Additive (C)

Without affecting the effectiveness of the invention, the liquid crystal alignment agent of the invention may selectively include an additive (C), and the additive (C) may be an epoxy compound or a silane compound with functional groups, etc. The function of the additive (C) is to improve the adhesion of the aforementioned liquid crystal alignment film to the substrate surface. The additive (C) may also include compounds that can improve the uniformity of film thickness and surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is coated. In addition, the additive (C) includes compounds that can promote charge transfer and charge release in the liquid crystal alignment film. The additive (C) may be used alone or in combination of multiple types.

The aforementioned epoxy compounds may include, but are not limited to, ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, propylene glycol diepoxypropyl ether, tripropylene glycol diepoxypropyl ether, polypropylene glycol diepoxypropyl ether, neopentyl glycol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, glycerol diepoxypropyl ether, 2,2-dibromoneopentyl glycol diepoxypropyl ether, 1,3,5,6-tetraepoxypropyl-2,4-hexanediol, N,N N',N'-Tetracyclooxypropyl-m-xylenediamine, 1,3-bis(N,N-dicyclooxypropylaminomethyl)cyclohexane, N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane, N,N-epoxypropyl-p-epoxypropoxyaniline, 3-(N-allyl-N-epoxypropyl)aminopropyltrimethoxysilane, 3-(N,N-dicyclooxypropyl)aminopropyltrimethoxysilane, etc.

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

The aforementioned silane compounds having functional groups may include, but are 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, and N-triethoxysilyl Propyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triacryldecane, 10-triethoxysilyl-1,4,7-triacryldecane, 9-trimethoxysilyl-3,6-diacrylnonyl acetate, 9-triethoxysilyl-3,6-diacrylnonyl 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.

The amount of polymer (A) used is 100 parts by weight, and the amount of the aforementioned silane compound with functional groups used is 2 parts by weight or less, preferably 0.02 parts by weight to 0.2 parts by weight.

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

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

The amount of polymer (A) used is 100 parts by weight, and the amount of the aforementioned surfactant used can be from 0.01 parts by weight to 2 parts by weight, and preferably from 0.1 parts by weight to 1 part by weight.

The aforementioned compounds that help improve the electrical properties of liquid crystal alignment films can be, for example, nitrogen-containing heterocyclic amine compounds. Nitrogen-containing heterocyclic amine compounds can be added directly to the liquid crystal alignment agent, or they can be prepared into a solution with a suitable solvent (the concentration can be from 0.1% to 10% by weight, and preferably from 1% to 7% by weight) and then added. There are no particular restrictions on the solvent used.

In addition to the specific examples of the additive (C) mentioned above, as long as the effect of the present invention is not impaired, the liquid crystal alignment agent of the present invention may selectively add dielectric or conductive materials to change the dielectric constant and conductivity of the liquid crystal alignment film.

The amount of polymer (A) used is 100 parts by weight, and the amount of additive (C) used is from 0.5 parts by weight to 50 parts by weight, and preferably from 1 part by weight to 45 parts by weight.

Liquid crystal alignment film and liquid crystal element

The liquid crystal alignment film of the present invention can be formed using a liquid crystal alignment agent prepared as described above. In particular, the liquid crystal alignment film of the present invention is preferably manufactured by a method including a photoalignment step, wherein the photoalignment step involves forming a coating using the liquid crystal alignment agent and subjecting the coating to light irradiation to impart liquid crystal alignment capability. Furthermore, the liquid crystal element of the present invention includes a liquid crystal alignment film formed using the aforementioned liquid crystal alignment agent. The operating mode of the liquid crystal in a liquid crystal element is not particularly limited. For example, it can be applied to various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) (including vertical alignment-multi-domain vertical alignment (VA-MVA) and vertical alignment-patterned vertical alignment (VA-PVA), in-plane switching (IPS), fringe field switching (FFS), and optically compensated bending (OCB). A liquid crystal element can be manufactured, for example, by a method comprising the following first to third steps. The substrate used in the first step varies depending on the desired operating mode. The action modes in steps two and three are universal.

Step 1: Formation of the coating

First, a liquid crystal alignment agent is applied to a substrate, preferably by heating the coated surface to form a coating film on the substrate. For example, the substrate can be a glass such as float glass or sodium glass, or a transparent substrate made of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefins). As a transparent conductive film disposed on one side of the substrate, a NESA film (registered trademark of PPG Industries, Inc.) containing tin oxide ( _SnO₂ ) or an _indium tin oxide (ITO) film containing indium oxide-tin oxide ( _In₂O₃ - _SnO₂ ) can be used. In manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. Conversely, in manufacturing IPS or FFS type liquid crystal elements, a substrate with electrodes comprising a patterned comb-shaped transparent conductive film or metal film and a non-electrode opposing substrate is used. The metal film can be, for example, a film containing metals such as chromium. The liquid crystal alignment agent is applied to the electrode forming surface, preferably by means of planar printing, flexographic printing, spin coating, roller coating, or inkjet printing.

After applying the liquid crystal alignment agent, preheating (pre-baking) is preferably performed to prevent sagging of the applied liquid crystal alignment agent. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Subsequently, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the acetic acid structures present in the polymer. The calcination temperature (post-baking temperature) is preferably 80°C to 300°C, and the post-baking time is preferably 5 minutes to 200 minutes. The film thickness formed in this manner is preferably 0.001 μm to 1 μm. After the liquid crystal alignment agent is applied to the substrate, the organic solvent is removed, thereby forming a liquid crystal alignment film or a coating that becomes a liquid crystal alignment film.

Step 2: Orientation Treatment

In the manufacture of TN, STN, IPS, or FFS type liquid crystal elements, a process is performed to impart liquid crystal alignment capability to the coating formed in the aforementioned first step (alignment treatment). Herein, the alignment capability of liquid crystal molecules is imparted to the coating to form a liquid crystal alignment film. Alignment treatment can also be performed by friction treatment, which involves rubbing a cloth-wound roller along a specific direction. However, considering the high photosensitivity of the polymer (A) and the fact that even a small amount of exposure can cause the coating to exhibit anisotropy, photoalignment treatment, which irradiates the coating formed on the substrate and imparts liquid crystal alignment capability to the coating, is preferable. On the other hand, in the case of manufacturing vertically aligned liquid crystal elements, the coating formed in the aforementioned first step can be used directly as a liquid crystal alignment film, but alignment treatment can also be applied to the coating.

The light irradiation in the photoalignment process can be performed by: irradiating the coating after the post-baking step; irradiating the coating after the pre-baking step and before the post-baking step; or irradiating the coating during the heating process in at least one of the pre-baking and post-baking steps. In the photoalignment process, the radiation used to irradiate the coating can be, for example, ultraviolet and visible light with wavelengths from 150 nm to 800 nm. Preferably, it is ultraviolet light with wavelengths from 200 nm to 400 nm. If the radiation is polarized, it can be linearly polarized or partially polarized. Furthermore, when the radiation used is linearly polarized or partially polarized, irradiation can be performed from a direction perpendicular to the substrate surface, from an inclined direction, or a combination of these. When irradiating unpolarized radiation, the irradiation direction is set to an inclined direction.

The light source used can be, for example, low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonant lamps, xenon lamps, and excimer lasers. The radiation dose is preferably between 400 J/ ^m² and 20,000 J/ ^m² , more preferably between 1,000 J/ ^m² and 5,000 J/ ^m² . To improve reactivity, the coating can be heated while simultaneously being irradiated with light.

When manufacturing a liquid crystal alignment film, a contact step may be included, in which the coating subjected to photo-irradiation treatment comes into contact with water, a water-soluble organic solvent, or a mixture of water and a water-soluble organic solvent. By performing this contact step, decomposition products generated during photo-alignment treatment can be removed from the film. Examples of water-soluble organic solvents include: methanol, ethanol, 1-propanol, isopropanol, 1-methoxy-2-propanol acetate, butyl solvent, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Preferably, the solvent used in the contact step is water, isopropanol, or mixtures thereof.

The contact methods between the coating and the solvent can include, but are not limited to, spraying, rinsing, dipping, and coating treatments. There is no particular limitation on the contact time between the coating and the solvent, for example, 5 seconds to 15 minutes.

When manufacturing the liquid crystal alignment film, a heating step may also be performed: the coating subjected to photoirradiation treatment is heated in at least one of the aforementioned contact steps, within a temperature range of 120°C to 280°C. In the heating step, from the viewpoint of promoting the reorientation of the molecular chains by heating, the heating temperature is preferably 140°C or higher, more preferably 150°C to 250°C. The heating time is preferably 5 minutes to 200 minutes, more preferably 10 minutes to 60 minutes.

Step 3: Construction of the liquid crystal unit

Two substrates with liquid crystal alignment films formed in the manner described above are prepared, and liquid crystal is disposed between the two substrates arranged opposite each other, thereby manufacturing a liquid crystal cell. Examples of manufacturing liquid crystal cells include: (1) arranging two substrates opposite each other with the liquid crystal alignment films facing each other and with a gap (spacer) between them, using a sealant to bond the periphery of the two substrates, injecting liquid crystal to fill the cell gaps divided by the substrate surface and the sealant, and then sealing the injection hole; (2) applying a sealant to a predetermined position on one of the substrates with the liquid crystal alignment films formed, then dropping liquid crystal at several points on the surface of the liquid crystal alignment films, bonding the other substrate with the liquid crystal alignment films facing each other, and diffusing the liquid crystal across the entire surface of the substrate (one drop filling (ODF) method), etc. Ideally, the manufactured liquid crystal cells should be heated to the temperature at which the liquid crystal becomes an isotropic phase, and then slowly cooled to room temperature, thereby removing the flow alignment that occurred during liquid crystal filling.

As a sealant, epoxy resins containing alumina spheres as spacers can be used, for example. As spacers, photo spacers, bead spacers, etc., can be used. As a liquid crystal, nematic liquid crystals and saturated liquid crystals can be listed, with nematic liquid crystals being preferred. Examples include Schiff base-based liquid crystals, azo-based liquid crystals, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, dicyclooctane-based liquid crystals, and cubane-based liquid crystals. Additionally, cholesterol-type liquid crystals, chiral reagents, and ferroelectric liquid crystals can also be added to these liquid crystals.

Next, a polarizing plate is attached to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates include those formed by sandwiching a polarizing film called an "H-film" with a cellulose acetate protective film, or polarizing plates containing the H-film itself, wherein the "H-film" is formed by stretching and aligning polyvinyl alcohol on one side and absorbing iodine on the other. This yields the liquid crystal element.

The disclosed liquid crystal element can be effectively applied to various uses, such as in clocks, portable games, word processors, personal laptops, car navigation systems, video cameras, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various surveillance cameras, LCD televisions, information displays, and other display devices or dimming films. Furthermore, the liquid crystal element formed using the liquid crystal alignment agent of this invention can also be applied to retardation films.

Preparation of diamine compound (a2-1)

Preparation of diamine compound (a2-1-1)

Step 1:

Dissolve 10.74 g (46.5 mmol) of 4-hydroxy-4'-nitrodiphenyl ether in 40.0 g of DMF, add 9.76 g (69.7 mmol) of potassium carbonate, and then add dropwise a 40.0 g DMF solution containing 17.15 g (69.7 mmol) of β-bromo-4-nitrophenylethyl ether to form a mixture.

The mixture was stirred at 70°C for 5 hours, 200 g of water was added, the precipitate was filtered, and the mixture was washed with 200 g of MeOH. The precipitate was dried under reduced pressure to obtain 12.91 g (32.6 mmol) of 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether.

The reaction in step 1 above is shown in reaction formula (C): Reaction (C)

Step 2:

5.19 g (13.1 mmol) of 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether was dissolved in 100.0 g of tetrahydrofuran, and 0.1 g (5 wt%) of palladium-carbon was added. The mixture was stirred at room temperature under hydrogen atmosphere for 1 hour. The reaction solution was dissolved in 1200.0 g of tetrahydrofuran, the catalyst was removed by filtration, and the filtrate was concentrated. The precipitated solid was washed with 200.0 g of heptane. The solid was then dried to obtain 2.86 g (8.5 mmol) of the diamine compound (a2-1-1) as shown in formula (5-7).

The reaction in step 2 above is shown in reaction formula (D): Reaction (D)

Preparation of diamine compound (a2-1-2)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the preparation of diamine compound (a2-1-2) involved the use of 4-(3-propanol)-4'-nitrodiphenyl ether in step 1. ) replaces 4-hydroxy-4'-nitrodiphenyl ether, and uses 1-bromo-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-2) having the structure shown in formula (5-2).

Preparation of diamine compound (a2-1-3)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-3) was prepared in step 1 using β-bromo-1-ethylamino-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-3) having the structure shown in formula (5-6).

Preparation of diamine compound (a2-1-4)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the preparation of diamine compound (a2-1-4) was carried out in step 1 with 1-(3-bromopropyl)-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced with it to prepare a diamine compound (a2-1-4) having the structure shown in formula (5-4).

Preparation of diamine compound (a2-1-5)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-5) was prepared in step 1 using 2-(4-hydroxy-phenoxy)-5-nitropyridine. ) replaces 4-hydroxy-4'-nitrodiphenyl ether, and is replaced by α-chloro-1-ethoxy-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-5) having the structure shown in formula (5-24).

Preparation of diamine compound (a2-1-6)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-6) was prepared in step 1 using α-chloro-2-ethoxy-5-nitropyridine ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced with it to prepare a diamine compound (a2-1-6) having the structure shown in formula (5-26).

Preparation of diamine compound (a2-1-7)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-7) was prepared in step 1 using α-chloro-1-ethoxy-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced with it to prepare a diamine compound (a2-1-7) having the structure shown in formula (5-9).

Preparation of diamine compound (a2-1-8)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-8) was prepared in step 1 using 1-(2-methyl-8-chloro-2,6-octadienyl-1-amino)-4-nitrobenzene (…). ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-8) having the structure shown in formula (5-10).

Preparation of diamine compound (a2-1-9)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-9) was prepared in step 1 using 1-(3-chloro-cyclohexyl)-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-9) having the structure shown in formula (5-11).

Preparation of diamine compound (a2-1-10)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-10) was prepared in step 1 using 1-(3-bromo-(2-cyclopentyl)-propane-1-thioetheryl)-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced with it to prepare a diamine compound (a2-1-10) having the structure shown in formula (5-19).

Preparation of diamine compound (a2-1-11)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the preparation of diamine compound (a2-1-11) involved using 1-(2-chloro-tetrazyl)-4-nitrobenzene in step 1. ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-11) having the structure shown in formula (5-12).

Preparation of diamine compound (a2-1-12)

The same method and reactant molar ratio as the aforementioned diamine compound (a2-1-1) were used, except that the diamine compound (a2-1-12) was prepared in step 1 using 16-bromo-hexadecyl-1-ether-4-nitrobenzene ( ) replace β-bromo-4-nitrophenylethyl ether to prepare compounds having the structure of the latter formula ( Then, the 4-nitro-4'-(2-(4-nitrophenoxy)ethoxy)-1,1'-diphenyl ether of step 2 is replaced to obtain a diamine compound (a2-1-12) having the structure shown in formula (5-22).

Preparation of polymer (A)

Synthesis Example A-1-1

A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked cone flask, and nitrogen gas was introduced. Then, 5.0 g (0.015 mol) of the diamine compound (a2-1-1) as shown in formula (5-7), 14.6 g (0.030 mol) of the diamine compound (a2-2-1) as shown in formula (6-a-2), 5.9 g (0.055 mol) of p-diaminebenzene (a2-5-1), and 80 g of NMP were added, and the mixture was stirred at room temperature until dissolved. Next, 13.5 g (0.060 mol) of the tetracarboxylic dianhydride compound (a1-1-1) as shown in formula (I-2), 8.7 g (0.040 mol) of benzyl tetracarboxylic dianhydride (a1-2-1), and 20 g of NMP were added, and the reaction was carried out at room temperature for 2 hours. After the reaction was completed, the reaction solution was poured into 1500 mL of water to precipitate the polymer. The obtained polymer was filtered, and the washing and filtration steps were repeated three times with methanol. Then, the product was placed in a vacuum oven and dried at a temperature of 60°C to obtain the polymer (A-1-1) of synthetic example A-1-1, the formulation of which is shown in Table 1.

Synthetic Examples A-1-2 to A-1-26 and Comparative Synthetic Examples A-1-1’ to A-1-12’

Synthetic Examples A-1-2 to A-1-26 and Comparative Examples A-1-1’ to A-1-12’ all used the same preparation method as the polymer (A-1-1) of Synthetic Example A-1-1. The difference lies in the type and amount of raw materials used in Synthetic Examples A-1-2 to A-1-26 and Comparative Examples A-1-1’ to A-1-12’. Their formulations are shown in Table 1. In Table 1, columns without numbers indicate that the compound was not used.

Synthesis Example A-2-1

A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked cone flask, and nitrogen gas was introduced. Then, 10.0 g (0.030 mol) of the diamine compound (a2-1-1) as shown in formula (5-7), 10.0 g (0.030 mol) of the diamine compound (a2-1-2) as shown in formula (5-2), 13.7 g (0.040 mol) of the diamine compound (a2-4-1) as shown in formula (8-1-2), and 80 g of NMP were added, and the mixture was stirred at room temperature until dissolved. Next, 22.5 g (0.100 mol) of the compound (a1-1-1) as shown in formula (I-2) 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 stirred continuously for 2 hours to carry out the acetylation reaction. After the reaction was completed, the reaction solution was poured into 1500 mL of water to allow the polymer to precipitate. Then, the obtained polymer was filtered, washed with methanol, and filtered three times. It 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, the formulation of which is shown in Table 1.

Synthetic Examples A-2-2 to A-2-6

Synthetic Examples A-2-2 to A-2-6 all used the same preparation method as the polymer (A-2-1) in Synthetic Example A-2-1. The difference lies in the type and amount of raw materials used in Synthetic Examples A-2-2 to A-2-6, as shown in Table 1. In Table 1, columns without numbers indicate that the raw material was not used.

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

Implementation Example 1

Weigh 100 parts by weight of the polymer (A-1-1) prepared in Synthesis Example A-1-1 and 800 parts by weight of NMP (B-1), and stir and mix them at room temperature to obtain the liquid crystal alignment agent of Example 1.

The aforementioned liquid crystal alignment agent was spin-coated onto a glass substrate, and pixel electrodes were formed on the glass substrate. The pixel electrodes were IPS driver electrodes with a pair of ITO electrodes (electrode width: 10 μm, electrode spacing: 10 μm, electrode height: 50 nm). These ITO electrodes each had a toothed shape, and the toothed portions were arranged in a separated yet interlocking manner. The glass substrate coated with the liquid crystal alignment agent was then dried on a heated plate at 80°C for 5 minutes, and then baked in a hot air circulating oven at 250°C for 60 minutes to form a coating with a thickness of 100 nm.

A substrate with a liquid crystal alignment film is prepared by irradiating the coated surface with ultraviolet light at a wavelength of 254 nm through a polarizing plate. Next, a coating is formed on the opposing substrate and an alignment treatment is applied. The opposing substrate is a glass substrate without electrodes but with columnar spacers of 4 μm in height.

The two substrates mentioned above are a set. A sealant is printed on one of them, and the other is bonded together with the liquid crystal alignment film facing each other with an alignment direction of 0 degrees. The sealant is then cured to create an empty cell. This empty cell is injected into liquid crystal MLC-2041 (manufactured by Merck) using a reduced-pressure injection method, and the injection port is sealed, thus forming the liquid crystal display element of Example 1. The evaluation method for the flicker level immediately after driving in Example 1 is performed on the aforementioned substrate with a liquid crystal alignment film that has been irradiated with ultraviolet light, and the results are shown in Table 2.

Examples 2 to 34 and Comparative Examples 1 to 12

Examples 2 to 34 and Comparative Examples 1 to 12 use the same preparation method as the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element as in Example 1. The difference is that Examples 2 to 34 and Comparative Examples 1 to 12 change the type and amount of raw materials in the liquid crystal alignment agent. Their formulations and evaluation results are shown in Table 2, which will not be described in detail here.

Evaluation methods

The degree of flickering immediately after driving.

The fabricated liquid crystal display element is placed between two polarizing plates whose polarization axes are arranged perpendicularly. The LED backlight is turned on without applying voltage, and the arrangement angle of the liquid crystal display element is adjusted to minimize the transmitted light brightness. Next, an AC voltage of 30 Hz is applied to the liquid crystal display element, and the V-T curve (voltage-transmittance curve) is measured simultaneously. The AC voltage with a relative transmittance of 23% is calculated and used as the driving voltage.

The method for measuring flicker after driving is as follows: Under the temperature condition of 23°C for the liquid crystal display element, the illuminated LED backlight is turned off and left in darkness for 72 hours. Then, it is turned on again, and at the same time as the backlight is turned on, an AC voltage of 30 Hz with a relative transmittance of 23% is applied to drive the liquid crystal display element for 60 minutes, and the flicker amplitude is tracked. The flicker amplitude is measured by reading the brightness value of the liquid crystal display element passing through two polarizers and between them using a data acquisition/data recording switching device 34970A (manufactured by Agilent Technologies) connected to the photodiode and IV converter amplifier. Flicker (FL) is calculated according to the following formula (X). The lower the flicker, the better the quality of the liquid crystal display element made with this liquid crystal alignment agent. (X)

In formula (X), z is the luminance value read when driven by the aforementioned device 34970A at an AC voltage of 30 Hz with a relative transmittance of 23%. ※: FL < 2%. ◎: 3% > FL ≥ 2%. ○: 4% > FL ≥ 3%. △: 5% > FL ≥ 4%. ╳: FL ≥ 5%.

As can be seen from the results in Tables 1 and 2, if the polymer (A) of the liquid crystal alignment agent of the present invention does not contain the diamine compound (a2-1) as shown in formula (5), the instantaneous flicker after driving of the formed liquid crystal display element is high. Secondly, when the polymer (A) of the liquid crystal alignment agent of the present invention further contains at least one of the following groups: the diamine compound (a2-2) as shown in formula (6), the diamine compound (a2-3) as shown in formula (7), and the diamine compound (a2-4) as shown in formula (8), the formed liquid crystal display element has an even lower instantaneous flicker after driving.

It should be added that although 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 element of the present invention, it will be understood by anyone with ordinary knowledge in the art to which the present invention pertains that the present invention is not limited thereto. Without departing from the spirit and scope of the present invention, the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element of the present invention may also be produced using other compounds, compositions, reaction conditions, processes, analytical methods or instruments.

Table 1

Table 1 (Continued)

Table 1 (Continued)

Table 2

Table 2 (Continued)

Table 2 (Continued)

without

without

Claims (16)

A liquid crystal alignment agent comprises: a polymer (A); and a solvent (B); wherein the polymer (A) is selected from the group consisting of polyamide, polyimide, polyimide block copolymers and combinations thereof, and the polymer (A) comprises the structure shown in formula (1). (1) In formula (1), _W1 , _W2 and _W3 represent divalent organic groups of benzene ring or pyridine ring, _X1 represents oxygen atom or sulfur atom, _X2 represents divalent chain hydrocarbon with 1 to 30 carbon atoms or alicyclic hydrocarbon with 3 to 30 carbon atoms, _X3 and _X4 each independently represent single bond, oxygen atom, sulfur atom or _-NR1- , wherein at least one of _X3 and _X4 represents oxygen atom, sulfur atom or _-NR1- , _R1 represents hydrogen atom or methyl, when any of _W1 , _W2 and _W3 is pyridine ring, _X3 and _X4 do not represent single bond, and * represents bond position. The liquid crystal alignment agent as described in claim 1, wherein X ₂ represents a divalent chain hydrocarbon having a carbon number of 1 to 30. The liquid crystal alignment agent as described in claim 1, wherein X ₂ represents a divalent chain hydrocarbon having 1 to 11 carbon atoms. The liquid crystal alignment agent as described in claim 1, wherein X ₂ represents a linear alkyl group having 1 to 11 carbon atoms. The liquid crystal alignment agent as described in claim 1, wherein the polymer (A) further comprises at least one of a group consisting of the structures shown in formulas (2), (3) and (4) below; (2) In formula (2), _X5 and _X6 each independently represent a single bond, an oxygen atom, a sulfur atom, -OCO- or -COO-, _X7 and _X8 each independently represent an alkyl group having 1 to 3 carbon atoms, _X9 and _X10 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a protecting group that is replaced by a hydrogen atom by heat, wherein at least one of _X9 and _X10 represents the protecting group that is replaced by a hydrogen atom by heat, _X11 represents an oxygen atom or a sulfur atom, and * represents a bond position; (3) In equation (3), _X12 , _X13 , _X14 and _X15 are the same or different, _X12 , _X13 , _X14 and _X15 represent monovalent bases, the two _X16 are the same or different, _X16 represents divalent bases, _p1 represents an integer from 1 to 10, and * represents the bond position; (4) In formula (4), _X17 and _X18 represent divalent substituted or unsubstituted aromatic ring groups, _X17 and _X18 are the same, _X19 represents _-NR2- , _R2 represents a protecting group that is replaced by a hydrogen atom by heat, _X20 represents a single bond, an oxygen atom or a sulfur atom, _X21 represents a divalent organic group having a chain hydrocarbon with 1 to 15 carbons or an alicyclic hydrocarbon with 3 to 15 carbons, * represents a bond position, wherein when _X20 represents a sulfur atom, the number of carbons in the divalent organic group represented by _X21 is not less than 2. A liquid crystal alignment film is made from a liquid crystal alignment agent as described in any one of claims 1 to 5. A liquid crystal display element comprising a liquid crystal alignment film as described in claim 6. A method for manufacturing a liquid crystal alignment agent includes: preparing the liquid crystal alignment agent from a polymer (A) and a solvent (B), wherein the polymer (A) is prepared by a polymerization reaction of a tetracarboxylic acid dianhydride component (a1) and a diamine component (a2), and the diamine component (a2) comprises a diamine compound (a2-1) as shown in formula (5); (5) In formula (5), ^W1 , ^W2 and ^W3 represent divalent organic groups of benzene ring or pyridine ring, ^X1 represents oxygen atom or sulfur atom, ^X2 represents divalent chain hydrocarbon with 1 to 30 carbon atoms or divalent alicyclic hydrocarbon with 3 to 30 carbon atoms, ^X3 and ^X4 each independently represent single bond, oxygen atom, sulfur atom or ^-NR1- , wherein at least one of ^X3 and ^X4 represents oxygen atom, sulfur atom or ^-NR1- , ^R1 represents hydrogen atom or methyl, and when any of ^W1 , ^W2 and ^W3 is pyridine ring, ^X3 and ^X4 do not represent single bond. The method for manufacturing a liquid crystal alignment agent as described in claim 8, wherein ^X2 represents a divalent chain hydrocarbon having 1 to 30 carbon atoms. The method for manufacturing a liquid crystal alignment agent as described in claim 8, wherein ^X2 represents a divalent chain hydrocarbon having 1 to 11 carbon atoms. The method for manufacturing a liquid crystal alignment agent as described in claim 8, wherein ^X2 represents a linear alkyl group having 1 to 11 carbon atoms. The method for manufacturing a liquid crystal alignment agent as described in claim 8, wherein the amount of the diamine component (a2) used is 100 mol percent, and the amount of the diamine compound (a2-1) as shown in formula (5) is 5 mol percent to 60 mol percent. The method for manufacturing a liquid crystal alignment agent as described in claim 8, wherein the diamine component (a2) further comprises at least one of a group consisting of a diamine compound (a2-2) as shown in formula (6), a diamine compound (a2-3) as shown in formula (7) and a diamine compound (a2-4) as shown in formula (8). (6) In formula (6), ^X5 and ^X6 each independently represent a single bond, an oxygen atom, a sulfur atom, -OCO- or -COO-, ^X7 and ^X8 each independently represent an alkyl group having 1 to 3 carbon atoms, ^X9 and ^X10 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a protecting group that is replaced by a hydrogen atom by heat, wherein at least one of ^X9 and ^X10 represents the protecting group that is replaced by a hydrogen atom by heat, and ^X11 represents an oxygen atom or a sulfur atom; (7) In equation (7), ^X12 , ^X13 , ^X14 and ^X15 are the same or different, ^X12 , ^X13 , ^X14 and ^X15 represent monovalent bases, the two ^X16 are the same or different, ^X16 represents divalent bases, and ^p1 represents integers from 1 to 10; (8) In formula (8), ^X17 and ^X18 represent divalent substituted or unsubstituted aromatic ring groups, ^X17 and ^X18 are the same, ^X19 represents ^-NR2- , ^R2 represents a protecting group that is replaced by a hydrogen atom by heat, ^X20 represents a single bond, an oxygen atom or a sulfur atom, and ^X21 represents a divalent organic group having a chain hydrocarbon with 1 to 15 carbon atoms or an alicyclic hydrocarbon with 3 to 15 carbon atoms, wherein when ^X20 represents a sulfur atom, the number of carbon atoms in the divalent organic group represented by ^X21 is not less than 2. The method for manufacturing a liquid crystal alignment agent as described in claim 13, wherein the total amount of the diamine component (a2) used is from 2 mol% to 95 mol%, based on the amount of the diamine component (a2) used being 100 mol%. A liquid crystal alignment film made of a liquid crystal alignment agent, wherein the liquid crystal alignment agent is produced by the manufacturing method described in any one of claims 8 to 14. A liquid crystal display element comprising a liquid crystal alignment film as described in claim 15.