TWI874658B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

A liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element are provided. The liquid crystal display element has low flicker level after the element is driven. The liquid crystal alignment agent includes a polymer (A) and a solvent (B). The polymer (A) is manufactured by the polymerization reaction of a mixture including the tetracarboxylic dianhydride component (a) and the diamine component (b), and has a structure as shown in formula (I).

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element, and in particular to a liquid crystal display element that utilizes the liquid crystal alignment agent to produce a liquid crystal display element with better flicker after driving.

Liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, etc. usually have a liquid crystal alignment film inside the element to control the arrangement of the liquid crystal. The most common method in the industry is to rub the surface of the film formed by polyamide and/or imide formed on the electrode substrate with cotton, nylon, polyester and other fabrics in one direction, and perform the so-called friction treatment to produce this liquid crystal alignment film.

During the alignment process of the liquid crystal alignment film, the film surface is rubbed, which is a relatively easy-to-produce method in industry. However, with the increasing requirements for high performance, high precision, and large-scale liquid crystal display elements, during the rubbing process, various problems such as damage to the alignment film surface, flying dust, the influence of mechanical force and electrostatic force, and unevenness on the alignment treatment surface have become more prominent.

As a method to replace the friction treatment, it is known that there is a photo-alignment method that uses polarized ultraviolet light to give liquid crystal alignment energy. The so-called photo-alignment method of liquid crystal alignment treatment refers to any substance that uses photoisomerization reaction, photocrosslink reaction, photodecomposition reaction, etc. in the reaction mechanism. Furthermore, the Japanese Patent Publication No. 9-297313 proposes that the photo-alignment method uses a polyimide film with a cyclocyclic structure such as cyclobutane in the main chain. When using polyimide as an alignment film for photo-alignment, because this alignment film has higher heat resistance than other types of alignment films, the applicability of this alignment film is promising.

The optical alignment method is a method of non-rubbing alignment treatment. It has the advantage of being manufactured using a simple process in the industry. In the liquid crystal display elements of the In-Plane-Switching (IPS) driving method and the Fringe Field Switching (FFS) driving method, the liquid crystal alignment film obtained by the optical alignment method can be used to improve the contrast and viewing angle characteristics of the liquid crystal display element, compared with the liquid crystal alignment film obtained by the rubbing treatment method. Therefore, the optical alignment method is a promising and highly anticipated liquid crystal alignment treatment method.

However, when the liquid crystal alignment film produced by the photo-alignment method is applied to a liquid crystal display element, the produced liquid crystal display element still has the problem of poor flicker after driving. From the above, it can be seen that in order to meet the requirements of the current photo-alignment IPS type liquid crystal display industry, providing a liquid crystal alignment agent that can form a liquid crystal display element with better flicker after driving is the goal of the research efforts of the technical field.

In view of this, the present invention provides a liquid crystal alignment agent that can improve the above-mentioned problem of poor flicker after driving.

The present invention provides a liquid crystal alignment agent, comprising: a polymer (A) and a solvent (B). The polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in the following formula (I):

In formula (I), ^Y1 represents a protecting group which is substituted with a hydrogen atom by heat, ^X1 and ^X2 each independently represent a divalent organic group, and * represents a bonding site.

In one embodiment of the present invention, in the above formula (I), Y ¹ represents a group represented by the following formula (II):

In formula (II), ^Y2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 3 to 20 carbon atoms, and * represents a bonding site.

In one embodiment of the present invention, the diamine component (b) comprises a diamine compound (b1) having a structure as shown in the following formula (b-1):

In formula (b-1), Y1 ^{is Y1} in formula (I), ^X3 and ^X4 each independently represent an alkylene group having 1 to 3 carbon atoms, and ^X5 and ^X6 each independently represent a single bond, -O-, -S-, -OCO- or -COO-.

In one embodiment of the present invention, the tetracarboxylic dianhydride component (a) comprises a tetracarboxylic dianhydride compound (a1) having a structure as shown in the following formula (a-1):

In formula (a-1), ^R1 to ^R4 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 having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group; ^R1 to ^R4 may be the same or different, and at least one of ^R1 , ^R2 , ^R3 and ^R4 is not a hydrogen atom.

In one embodiment of the present invention, the diamine component (b) comprises a diamine compound (b2) having a structure as shown in the following formula (b-2):

In formula (b-2), Ar represents an aromatic ring, ^X11 represents an alkylene group having 1 to 5 carbon atoms, and ^X12 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

In one embodiment of the present invention, based on the usage of the tetracarboxylic dianhydride component (a) being 100 mol, the usage of the tetracarboxylic dianhydride compound (a1) is 10 mol to 100 mol.

In one embodiment of the present invention, based on the usage of the diamine component (b) being 100 mol, the usage of the diamine compound (b1) is 0.5 mol to 50 mol.

In one embodiment of the present invention, based on the usage of the diamine component (b) being 100 mol, the usage of the diamine compound (b2) is 1 mol to 99.5 mol.

In one embodiment of the present invention, based on the usage of polymer (A) being 100 parts by weight, the usage of solvent (B) is 800 to 4000 parts by weight.

The present invention further provides a liquid crystal alignment film formed using the liquid crystal alignment agent as described above.

The present invention further provides a liquid crystal display element, including the liquid crystal alignment film as described above.

Based on the above, the liquid crystal alignment agent of the present invention uses a polymer (A) with a specific structure, so the liquid crystal alignment agent can improve the technical problem of poor flicker after driving in the previous technology.

In order to make the above features and advantages of the present invention more clearly understood, the following is a detailed description of the embodiments with the accompanying drawings.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: First conductive film

116: First liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

Figure 1 is a schematic diagram of the structure of the liquid crystal display element of the present invention.

<Liquid crystal alignment agent>

The present invention provides a liquid crystal alignment agent, including a polymer (A) and a solvent (B), and optionally an additive (C). The polymer (A) is prepared by polymerization of a mixture containing a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in formula (I). The following will describe in detail the various components of the liquid crystal alignment agent used in the present invention.

Polymer (A)

The polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in the following formula (I):

In formula (I), ^Y1 represents a protecting group which is substituted with a hydrogen atom by heat, ^X1 and ^X2 each independently represent a divalent organic group, and * represents a bonding site.

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

Examples of the divalent organic group represented by X ¹ and X ² in formula (I) include groups having a structure derived from a monomer skeleton used for polymer synthesis.

The protective group represented by ^Y1 in formula (I) which is substituted by a hydrogen atom by heat is a thermally releasable group. More specifically, ^Y1 is a protective group for an amino group, and as long as it is a protective group which is substituted by a hydrogen atom by heat, its structure is not particularly limited. From the perspective of the storage stability of the liquid crystal alignment agent, the protective group ^Y1 is preferably one which does not releasable at room temperature, more preferably one which releasable at a heat of 80°C or more, still more preferably one which releasable at a heat of 100°C or more, and particularly preferably one which releasable at a heat of 120°C or more. The temperature at which the protective group Y1 releasable is preferably below 250°C, more preferably below 230°C. If the temperature at which the protective group ^Y1 releasable is too high, the polymer may decompose.

^Y1 in formula (I) is preferably a group represented by the following formula (II):

In formula (II), ^Y2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 3 to 20 carbon atoms, and * represents a bonding site.

Based on the viewpoint of raw material availability, ^Y2 is preferably, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, benzyl, n-hexadecyl or 9-fluorenylmethyl. Based on the viewpoint of polymer solubility and thermal dissociation, ^Y2 is preferably, for example, t-butyl.

When the polymer (A) in the liquid crystal alignment agent does not contain the structure represented by formula (I), the flicker of the resulting liquid crystal display element after driving is poor.

Tetracarboxylic dianhydride component (a)

The tetracarboxylic dianhydride component (a) includes a tetracarboxylic dianhydride compound (a1) having a structure as shown in formula (a-1), and other tetracarboxylic dianhydride compounds (a2).

Tetracarboxylic dianhydride compound (a1)

The tetracarboxylic dianhydride compound (a1) has a structure represented by the following formula (a-1):

In formula (a-1), ^R1 to ^R4 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 having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group, ^R1 to ^R4 may be the same or different, and at least one of ^R1 , ^R2 , ^R3 and ^R4 is not a hydrogen atom.

R ₁ , R ₂ , R ₃ and R ₄ are preferably those with the smallest possible steric hindrance. Specifically, they are preferably hydrogen atoms, methyl groups or ethyl groups, and methyl groups are more preferred.

Specific examples of the tetracarboxylic dianhydride compound (a1) having a structure as shown in formula (a-1) include compounds shown in the following formulas (a-1-1) to (a-1-8). In terms of the scintillation after driving, the compound of formula (a-1-1) is preferred.

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

Based on the total usage of the tetracarboxylic dianhydride component (a) being 100 mol, the usage of the tetracarboxylic dianhydride compound (a1) is 10 mol to 100 mol, preferably 15 mol to 80 mol, and more preferably 20 mol to 70 mol.

If the tetracarboxylic dianhydride component (a) contains a tetracarboxylic dianhydride compound (a1), the flicker degree of the formed liquid crystal display element after driving can be further reduced.

Other tetracarboxylic dianhydride compounds (a2)

Preferred specific examples of other tetracarboxylic dianhydride compounds (a2) include: (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds represented by formula (a-2-1) to formula (a-2-6), etc.

(1) Aliphatic tetracarboxylic dianhydride compounds include but are not limited to aliphatic tetracarboxylic dianhydride compounds such as ethanetetracarboxylic dianhydride or butanetetracarboxylic dianhydride.

(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, 1,2, Alicyclic tetracarboxylic acid dianhydride compounds such as 3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic acid dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride or dicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride.

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

(4) The tetracarboxylic dianhydride compounds represented by formula (a-2-1) to formula (a-2-6) are as follows.

In formula (a-2-5), _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 each independently represent a hydrogen atom or an alkyl group. Specific examples of the tetracarboxylic dianhydride compound represented by formula (a-2-5) include at least one of the compounds represented by formula (a-2-5-1) to formula (a-2-5-3).

In formula (a-2-6), _A4 represents a divalent group containing an aromatic ring; _A5 and _A6 may be the same or different, and each independently represents a hydrogen atom or an alkyl group. The tetracarboxylic dianhydride compound represented by formula (a-2-6) is preferably a compound represented by formula (a-2-6-1).

Other tetracarboxylic dianhydride compounds (a2) can be used alone or in combination of two or more.

Based on the total usage of the tetracarboxylic dianhydride component (a) being 100 mol, the usage of other tetracarboxylic dianhydride compounds (a2) is 0 mol to 90 mol, preferably 20 mol to 85 mol, and more preferably 30 mol to 80 mol.

Based on the total usage of the diamine component (b) described later being 100 mol, the total usage of the tetracarboxylic dianhydride component (a) is 20 mol to 200 mol, preferably 30 mol to 120 mol.

Diamine component (b)

The diamine component (b) includes a diamine compound (b1) having a structure as shown in formula (b-1), a diamine compound (b2) having a structure as shown in formula (b-2), and other diamine compounds (b3).

Diamine compound (b1)

The diamine compound (b1) has a structure represented by the following formula (b-1):

In formula (b-1), Y1 ^{is Y1} in formula (I), ^X3 and ^X4 each independently represent an alkylene group having 1 to 3 carbon atoms, and ^X5 and ^X6 each independently represent a single bond, -O-, -S-, -OCO- or -COO-.

^X3 and ^X4 each independently represent an alkylene group having 1 to 3 carbon atoms. The alkylene group may be linear or branched. Specific examples include methylene, ethylene, propylene, 1-methylethylene, 2-methylethylene, etc. Among them, those having as much free rotation site as possible and having a small steric hindrance are preferred. Specifically, methylene, ethylene, and propylene are preferred.

X ⁵ and X ⁶ each independently represent a single bond, -O-, -S-, -OCO- or -COO-. Among them, a structure that is as soft as possible and has little steric hindrance is preferred. Specifically, a single bond, -O- or -S- is preferred.

Specific examples of the diamine compound (b1) having a structure as shown in formula (b-1) include compounds shown in the following formulas (b-1-1) to (b-1-11).

The diamine compound (b1) can be used alone or in combination of two or more.

Based on the total usage of the diamine component (b) being 100 mol, the usage of the diamine compound (b1) is 0.5 mol to 50 mol, preferably 0.5 mol to 40 mol, and more preferably 0.5 mol to 30 mol.

If the diamine component (b) does not contain the diamine compound (b1), the flicker of the resulting liquid crystal display element after driving is poor.

Synthesis method of diamine compound (b1)

The synthesis method of the diamine compound (b1) is not particularly limited. As a general synthesis method, it can be prepared by reducing the dinitro compound Cpd.2 of the diamine compound Cpd.1 as shown below. ^X3 , ^X4 , ^X5 , and ^X6 have the same meanings as ^X3 , ^X4 , ^X5 , and ^X6 described in formula (b-1).

The above reduction reaction includes hydrogenation reaction in the presence of a catalyst, reduction reaction in the presence of protons, reduction reaction using formic acid as a hydrogen source, reduction reaction using hydrazine as a hydrogen source, etc. These reduction reactions can also be combined. If the structure of the dinitro compound Cpd.2 and the reactivity of the reduction reaction are taken into consideration, the hydrogenation reaction is preferred.

The catalyst used in the reduction reaction is preferably a metal supported on activated carbon that can be obtained from commercial products, such as palladium-activated carbon, platinum-activated carbon, rhodium-activated carbon, etc. In addition, metal catalysts such as palladium hydroxide, platinum dioxide, and Raney nickel that are not necessarily supported on activated carbon can also be used. Palladium-activated carbon, which is widely used, is preferred because it can obtain good results.

In order to make the reduction reaction more effective, the reaction can be carried out in the presence of activated carbon. At this time, the amount of activated carbon used is not particularly limited. For the dinitro compound Cpd.2, 1-20 mass % is preferred, and 5-10 mass % is more preferred.

For the same reason, the reaction may be carried out under pressure. In this case, if you want to avoid the reduction of the benzene ring, you can carry out the reaction under a pressure range of up to 20 atmospheres. It is better to carry out the reaction under a pressure range of up to 10 atmospheres.

For the reduction reaction, it is best to use a solvent, as long as the solvent does not react with the raw materials, and it can be used without restriction.

For example, aprotic polar organic solvents (DMF (N,N-dimethylformamide), DMSO (dimethylsulfoxide), DMAc (dimethylacetamide), NMP (N-methyl-2-pyrrolidone) etc.); ethers (Et ₂ O (diethyl ether), i-Pr ₂ O (diisopropyl ether), TBME (tert-butyl methyl ether), CPME (cyclopentyl methyl ether), THF (tetrahydrofuran), dioxane, etc.); aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.); aromatic hydrocarbons (benzene, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, tetrahydronaphthalene, etc.); halogen hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.); nitriles (acetonitrile, propionitrile, butyronitrile, etc.). These solvents can be appropriately selected considering their ease of reaction, and can be used alone or in combination of two or more. If necessary, the solvent can be dried with an appropriate dehydrating agent or desiccant, and can also be used as a non-aqueous solvent.

The amount of solvent used (reaction concentration) is not particularly limited, and is 0.1 to 100 times the mass of the dinitro compound Cpd.2. It is preferably 0.5 to 30 times the mass, and more preferably 1 to 10 times the mass.

The reaction temperature is not particularly limited, and is preferably in the range of -100°C to the boiling point of the solvent used, preferably -50~150°C. The reaction time is usually 0.05~350 hours, preferably 0.5~100 hours.

On the other hand, the synthesis method of the dinitro compound Cpd.2 is not particularly limited and can be synthesized by any method. As a specific example, the dinitro compound Cpd.3 and di-tert-butyl dicarbonate are reacted in a solvent in the presence of a base as required.

For 1 equivalent of carboxyl group of the dinitro compound Cpd.3, it is best to use 1 to 5 equivalents, and more preferably 1.3 to 2.5 equivalents of di-tert-butyl dicarbonate. By setting the reaction conditions such as the number of equivalents, the number of Boc groups introduced can be controlled.

The presence of alkali in the reaction is not essential, but when alkali is used, inorganic alkalis such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, potassium phosphate, sodium carbonate, potassium carbonate, lithium carbonate, and cesium carbonate can be used; amines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, diisopropylethylamine, pyridine, dimethylaminopyridine, imidazole, quinoline, and collidine can be used; alkalis such as sodium hydroxide, potassium hydroxide, tert-butoxysodium, and tert-butoxypotassium can be used.

As for the solvent in this reaction, any solvent that does not react with the raw materials can be used. The same solvents as those described in the synthesis of diamine compound Cpd.1 from dinitro compound Cpd.2, non-protonic polar organic solvents, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogen hydrocarbons, low-order fatty acid esters, etc. can be used. These solvents can be appropriately selected in consideration of factors such as the ease of causing reactions, and can be used alone or in combination of two or more. If necessary, the solvent can be dried using an appropriate dehydrating agent or drying agent and used as a non-aqueous solvent.

The amount of solvent used is not particularly limited. For the dinitro compound Cpd.3, 0.1 to 100 times the mass of the solvent can be used. Preferably, it is 0.5 to 30 times the mass, and more preferably, it is 1 to 10 times the mass. Although the reaction temperature is not particularly limited, it can be used in the range of -100°C to the boiling point of the solvent used, preferably in the range of -50 to 150°C. The reaction time is usually 0.05 to 200 hours, preferably 0.5 to 100 hours.

Diamine compound (b2)

The diamine compound (b2) has a structure represented by the following formula (b-2):

In formula (b-2), Ar represents an aromatic ring, ^X11 represents an alkylene group having 1 to 5 carbon atoms, and ^X12 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Ar is a site for making an aromatic amine site exist on the diamine having a secondary amine at the polymerization reaction site, and is not particularly limited as long as it is an aromatic ring. From the viewpoints of raw material availability, ease of synthesis, liquid crystal orientation, etc., Ar is preferably a phenylene group or a naphthyl group. From the viewpoint of versatility, a phenylene group is preferred. When Ar is a phenylene group, that is, when H ₂ N-Ar is an aminobenzene group, the substitution position of X ¹¹ is preferably the meta-position or the para-position.

^X11 represents an alkylene group having 1 to 5 carbon atoms. As long as the carbon number of ^X11 is within this range, it may be a branched or cyclic structure, preferably a straight chain structure, and particularly preferably an alkylene group having 1 or 2 carbon atoms.

^X12 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and the alkyl group may be a straight chain or a branched structure. It is preferably a group as small as possible, and particularly preferably a hydrogen atom, a methyl group or an ethyl group.

Specific examples of the diamine compound (b2) having a structure as shown in formula (b-2) include compounds shown in the following formulas (b-2-1) to (b-2-12).

The diamine compound (b2) can be used alone or in combination of two or more.

Based on the total usage of the diamine component (b) being 100 mol, the usage of the diamine compound (b2) is 1 mol to 99.5 mol, preferably 2 mol to 80 mol, and more preferably 3 mol to 70 mol.

If the diamine component (b) contains a diamine compound (b2), the flicker degree of the formed liquid crystal display element after driving can be further reduced.

Other diamine compounds (b3)

Other diamine compounds (b3) include (1) aliphatic diamine compounds, (2) alicyclic diamine compounds, (3) aromatic diamine compounds, (4) diamine compounds represented by formula (b-3-1) to formula (b-3-29), or combinations thereof.

(1) Specific examples of aliphatic diamine compounds include, but are not limited to, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 4,4′-diaminoheptane, 1,3-diamino-2,2-dimethyl Propane, 1,6-diamino-2,5-dimethylhexane, 1,7-diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, 2,11-diaminododecane, 1,12-diaminooctadecane, 1,2-bis(3-aminopropoxy)ethane, or a combination of the above compounds.

(2) Specific examples of alicyclic diamine compounds include, but are not limited to, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienediamine, tricyclo[6.2.1.0 ^2,7 ]-undecenedimethyldiamine, 4,4'-methylenebis(cyclohexylamine), or combinations thereof.

(3) Specific examples of aromatic diamine compounds include, but are not limited to, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 5-amino-1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, 6-amino-1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, hexahydro-4,7-methoxy-indene dimethylenediamine, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, Aminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,5-bis(4-aminophenoxymethylene)adamantane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 9,9-bis(4-aminophenyl)-10 -Hydrogen anthracene, 9,10-bis(4-aminophenyl)anthracene, 2,7-diaminofluorene, 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylene-bis(2-chloroaniline), 4,4'-(p-phenyleneisopropylidene)bisaniline, 4,4'-(m-phenyleneisopropylidene)bisaniline, 2,2'-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane, 4,4'-bis[(4-amino-2-trifluoromethyl)phenoxy]-octafluorobiphenyl, 5-[4-(4-n-phenyleneisopropylidene)bisaniline 5-[4-(4-n-pentylcyclohexyl)cyclohexyl]phenylmethylene-1,3-diaminobenzene, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-(4-ethylphenyl)cyclohexane, or a combination of the above compounds.

(4) The diamine compounds represented by formula (b-3-1) to formula (b-3-29) are as follows.

、

、

、

， 或

；B²表示具有甾(膽固醇(steroid))骨架的基、三氟甲基、氟基、碳數為2至30的烷基、或衍生自吡啶、嘧啶、三嗪、哌啶或哌嗪等含氮原子環狀結構的一價基團。 In formula (b-3-1), ^B1 represents -O-,

,

,

,

, or

; ^B2 represents a group having a steroid skeleton, a trifluoromethyl group, a fluoro group, an alkyl group having 2 to 30 carbon atoms, or a monovalent group derived from a nitrogen atom-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine or piperazine.

Specific examples of the compound represented by formula (b-3-1) include, but are not limited to, 2,4-diaminophenyl ethyl formate, 3,5-diaminophenyl ethyl formate, 2,4-diaminophenyl propyl formate, 3,5-diaminophenyl propyl formate, formate), 1-dodecoxy-2,4-diaminobenzene, 1-hexadecoxy-2,4-diaminobenzene, 1-octadecoxy-2,4-diaminobenzene, at least one of the compounds represented by formula (b-3-1-1) to formula (b-3-1-6), or a combination of the above compounds.

The compounds represented by formula (b-3-1-1) to formula (b-3-1-6) are shown below.

In formula (b-3-2), ^B1 is the same as ^B1 in formula (b-3-1), ^B3 and ^B4 each independently represent a divalent aliphatic ring, a divalent aromatic ring or a divalent heterocyclic group; ^B5 represents an alkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a fluoroalkoxy group having 1 to 5 carbon atoms, a cyano group or a halogen atom.

Specific examples of the compound represented by formula (b-3-2) include at least one of the compounds represented by formula (b-3-2-1) to formula (b-3-2-13).

In formula (b-3-2-1) to formula (b-3-2-13), s represents an integer from 3 to 12.

In formula (b-3-3), ^B6 each independently represents a hydrogen atom, an acyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen atom, and ^B6 in each repeating unit may be the same or different; u represents an integer from 1 to 3.

Specific examples of the compound represented by formula (b-3-3) include when u is 1: p-diaminobenzene, m-diaminobenzene, o-diaminobenzene or 2,5-diaminotoluene, etc.; when u is 2: 4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2, 2’-dichloro-4,4’-diaminobiphenyl, 3,3’-dichloro-4,4’-diaminobiphenyl, 2,2’,5,5’-tetrachloro-4,4’-diaminobiphenyl, 2,2’-dichloro-4,4’-diamino-5,5’-dimethoxybiphenyl or 4,4’-diamino-2,2’-bis(trifluoromethyl)biphenyl, etc.; or when u is 3: 1,4-bis(4’-aminophenyl)benzene, etc.

Specific examples of the compound represented by formula (b-3-3) preferably include p-diaminobenzene, 2,5-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 1,4-bis(4'-aminophenyl)benzene or a combination of the above compounds.

In formula (b-3-4), w represents an integer from 1 to 5. The compound represented by formula (b-3-4) is preferably 4,4'-diamino-diphenyl sulfide.

In formula (b-3-5), ^B7 and ^B9 each independently represent a divalent organic group, and ^B7 and ^B9 may be the same or different; ^B8 represents a divalent group derived from a cyclic structure containing a nitrogen atom such as pyridine, pyrimidine, triazine, piperidine or piperazine.

In formula (b-3-6), ^B10 , ^B11 , ^B12 and ^B13 each independently represent a alkyl group having 1 to 12 carbon atoms, and ^B10 , ^B11 , ^B12 and ^B13 may be the same or different; X1 each independently represents an integer from 1 to 3; and X2 represents an integer from 1 to 20.

In formula (b-3-7), B ¹⁴ represents an oxygen atom or a cyclohexylene group; B ¹⁵ represents a methylene group (methylene, -CH ₂ -); B ¹⁶ represents a phenylene group or a cyclohexylene group; and B ¹⁷ represents a hydrogen atom or a heptyl group.

Specific examples of the compound represented by formula (b-3-7) include a compound represented by formula (b-3-7-1), a compound represented by formula (b-3-7-2), or a combination of the above compounds.

The compounds represented by formula (b-3-8) to formula (b-3-29) are shown below.

In formula (b-3-16) to formula (b-3-24), B ¹⁸ preferably represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms; B ¹⁹ preferably represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

Other diamine compounds (b3) can be used alone or in combination.

Specific examples of other diamine compounds (b3) preferably include but are not limited to 1,2-diaminoethane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 5-[4-(4-n-pentylcyclohexyl)cyclohexyl]phenylmethylene-1,3-diaminobenzene, 1,3-bis(3-aminophenoxy)benzene, 1,1-bis[4-(4-aminophenoxy) )phenyl]-4-(4-ethylphenyl)cyclohexane, ethyl 2,4-diaminophenylcarboxylate, p-diaminobenzene, m-diaminobenzene, o-diaminobenzene, compounds represented by formula (b-3-1-1), formula (b-3-1-2), formula (b-3-1-5), formula (b-3-2-1), formula (b-3-2-11), formula (b-3-7-1), formula (b-3-25) or formula (b-3-28).

Based on the total usage of the diamine component (b) being 100 mol, the usage of the other diamine compound (b3) is 0 mol to 98.5 mol, preferably 0 mol to 97.5 mol, and more preferably 0 mol to 96.5 mol.

Method for preparing polymer (A)

The polymer (A) may include at least one of polyamide and polyimide. In addition, the polymer (A) may further include a polyimide block copolymer. The preparation methods of the above-mentioned various polymers are further described below.

Method for preparing polyamine

The method for preparing polyamine is to first dissolve a mixture in a solvent, wherein the mixture includes a tetracarboxylic dianhydride component (a) and a diamine component (b), and perform a polycondensation reaction at a temperature of 0°C to 100°C. After reacting for 1 to 24 hours, the reaction solution is subjected to reduced pressure distillation in an evaporator to obtain polyamine. Alternatively, the reaction solution is poured into a large amount of a poor solvent to obtain a precipitate. Then, the precipitate is dried by reduced pressure drying to obtain polyamine.

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

It is worth noting that in the polycondensation reaction, the solvent can be used in combination with an appropriate amount of a poor solvent, wherein the poor solvent will not cause the precipitation of polyamine. The poor solvent can be used alone or in combination, and includes but is not limited to (1) alcohols, such as methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol or triethylene glycol; (2) ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; (3) esters, such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate or ethylene glycol ethyl ether acetate; (4) ethers, For example: ethers such as diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; (5) halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene or o-dichlorobenzene; or (6) hydrocarbons such as tetrahydrofuran, hexane, heptane, octane, benzene, toluene or xylene or any combination of the above solvents. Based on the usage of the diamine component (a2) being 100 parts by weight, the usage of the poor solvent is preferably 0 to 60 parts by weight, and more preferably 0 to 50 parts by weight.

Method for preparing polyimide

The method for preparing polyimide is to heat the polyimide prepared by the above method for preparing polyimide in the presence of a dehydrating agent and a catalyst. During the heating process, the amide functional group in the polyimide can be converted into an imide functional group (i.e., imidization) through a dehydration ring-closing reaction.

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

In order to obtain a better degree of imidization of polyamide, the operating temperature of the dehydration ring-closing reaction is preferably 40°C to 200°C, and more preferably 40°C to 150°C. If the operating temperature of the dehydration ring-closing reaction is lower than 40°C, the imidization reaction is incomplete, thereby reducing the degree of imidization of polyamide. However, if the operating temperature of the dehydration ring-closing reaction is higher than 200°C, the weight average molecular weight of the obtained polyimide is low.

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

Method for preparing polyimide block copolymer

The polyimide-based block copolymer is selected from polyamic acid block copolymer, polyimide block copolymer, polyamic acid-polyimide block copolymer or any combination of the above polymers.

The method for preparing the polyimide-based block copolymer is preferably to first dissolve the starter in a solvent and perform a polycondensation reaction, wherein the starter includes at least one polyamide and/or at least one polyimide, and may further include a carboxylic anhydride component and a diamine component.

The carboxylic anhydride component and the diamine component in the starting material can be the same as the tetracarboxylic dianhydride component (a) and the diamine component (b) used in the method for preparing polyamide, and the solvent used in the polycondensation reaction can be the same as the solvent (B) in the liquid crystal alignment agent described below, which will not be further described here.

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

The starting materials preferably include but are not limited to (1) two polyamines with different terminal groups and different structures; (2) two polyimides with different terminal groups and different structures; (3) polyamines and polyimides with different terminal groups and different structures; (4) polyamines, carboxylic acid anhydride components and diamine components, wherein at least one of the carboxylic acid anhydride components and diamine components has a different structure from the carboxylic acid anhydride components and diamine components used to form polyamines; (5) polyimides, carboxylic acid anhydride components and diamine components, wherein at least one of the carboxylic acid anhydride components and diamine components has a different structure from the carboxylic acid anhydride components and diamine components used to form polyimides; (6) polyamines, polyimides, carboxylic acid anhydride components and diamine component, wherein at least one of the carboxylic anhydride component and the diamine component has a structure different from the carboxylic anhydride component and the diamine component used to form the polyamine or polyimide; (7) two polyamines, carboxylic anhydride components and diamine components with different structures; (8) two polyimides, carboxylic anhydride components and diamine components with different structures; (9) two polyamines and diamine components with different terminal groups being anhydride groups; (10) two polyamines and carboxylic anhydride components with different terminal groups being amine groups; (11) two polyimides and diamine components with different terminal groups being anhydride groups; or (12) two polyimides and carboxylic anhydride components with different terminal groups being amine groups.

Within the scope that does not affect the efficacy of the present invention, polyamine, polyimide and polyimide-based block copolymers are preferably terminal-modified polymers after molecular weight adjustment. By using terminal-modified polymers, the coating performance of liquid crystal alignment agents can be improved. The method for preparing terminal-modified polymers can be prepared by adding monofunctional compounds while polyamine is undergoing a polycondensation reaction.

Specific examples of monofunctional compounds include but are not limited to (1) monoacid anhydrides, such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride or n-hexadecyl succinic anhydride; (2) monoamine compounds, such as aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine or n-eicosylamine; or (3) monoisocyanate compounds, such as monoisocyanate compounds such as phenyl isocyanate or naphthyl isocyanate.

The weight average molecular weight of the polymer (A) of the present invention measured by gel permeation chromatography (GPC) is 10,000 to 90,000, preferably 12,000 to 75,000, and more preferably 15,000 to 60,000, calculated based on polystyrene.

Solvent (B)

The solvent (B) 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. It is preferably the same solvent used in the aforementioned synthesis of polyamine. At the same time, it can also be used in combination with the poor solvent used in the synthesis of the aforementioned polyamine.

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

Solvent (B) can be used alone or in combination of two or more.

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

Additive(C)

Within the scope that does not affect the efficacy of the present invention, the liquid crystal alignment agent of the present invention may optionally include an additive (C), and the additive (C) may be an epoxy compound or a silane compound with a functional group. The function of the additive (C) is to improve the adhesion between the aforementioned liquid crystal alignment film and the surface of the substrate. The additive (C) can be used alone or in combination.

The epoxy compound mentioned above may include but is not limited to ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N , N', N'-tetracycloxypropyl-m-xylene diamine, 1,3-bis(N, N-dicycloxypropylaminomethyl)cyclohexane, N, N, N', N'-tetracycloxypropyl-4,4'-diaminodiphenylmethane, N, N-cycloxypropyl-p-cycloxypropyloxyaniline, 3-(N-allyl-N-cycloxypropyl)aminopropyltrimethoxysilane, 3-(N, N-dicycloxypropyl)aminopropyltrimethoxysilane, etc.

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

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

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

Based on the usage of polymer (A) being 100 parts by weight, the usage of additive (C) can be 0.5 parts by weight to 50 parts by weight, and preferably 1 part by weight to 45 parts by weight.

<Method for producing liquid crystal alignment agent>

The manufacturing method of the liquid crystal alignment agent of the present invention is not particularly limited, and a general mixing method can be adopted, such as first mixing the tetracarboxylic dianhydride component (a) and the diamine component (b) evenly to react and form a polymer (A). Then, the polymer (A) is added with a solvent (B) and an additive (C) at a temperature of 0°C to 200°C, and stirred continuously with a stirring device until dissolved. Preferably, the polymer (A) and the additive (C) are added to the solvent (B) at a temperature of 20°C to 60°C.

<Manufacturing method of liquid crystal alignment film>

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

The substrate on which the liquid crystal alignment agent of the present invention is applied is selected from transparent materials, wherein the transparent materials include but are not limited to alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, polycarbonate, etc. used in liquid crystal display devices. It is preferred to use the ITO electrode for liquid crystal driving that has been formed on the substrate to simplify the process. Furthermore, for a reflective liquid crystal display with only a single-sided substrate, the aforementioned substrate can use an opaque material such as a silicon wafer. In this case, the electrode can be formed using a material that reflects light such as aluminum. The coating method of the liquid crystal alignment agent of the present invention can be, for example, a spin coating method, a printing method, an inkjet method, etc.

The liquid crystal alignment agent of the present invention can be dried and baked at any temperature and time after coating. Generally speaking, in order to fully remove the organic solvent contained, it is necessary to dry at 50°C to 120°C for 1 minute to 10 minutes. After that, bake at 150°C to 300°C for 5 minutes to 120 minutes. There is no special restriction on the thickness of the coating after baking, but too thin a coating will cause the reliability of the liquid crystal display to deteriorate, so the above coating thickness is preferably 5nm to 300nm, and 10nm to 200nm is more preferred.

Although the liquid crystal alignment agent of the present invention can be subjected to the known rubbing alignment treatment, the effect is better when the photoalignment treatment method is used.

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

The liquid crystal alignment agent of the present invention is subjected to pre-baking, post-baking and photo-alignment treatment to form a liquid crystal alignment film, and the pre-tilt angle of the liquid crystal alignment film is 0° to 3°.

<Method for manufacturing liquid crystal display element>

The present invention also provides a liquid crystal display element, which includes the aforementioned liquid crystal alignment film.

The manufacturing method of liquid crystal display elements is well known to those in the art, so the following is only briefly described.

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

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

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

The first substrate 112 and the second substrate 122 are selected from transparent materials, wherein the transparent materials include but are not limited to alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, polycarbonate, etc. used in liquid crystal display devices. The material of the electrode 114 is selected from transparent electrodes such as tin oxide (SnO ₂ ), indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) or metal electrodes such as chromium.

The first liquid crystal alignment film 116 and the second liquid crystal alignment film 126 are the above-mentioned liquid crystal alignment films, which function to form a pre-tilt angle for the liquid crystal unit 130, and the liquid crystal unit 130 can be driven by the parallel electric field generated by the electrode 114.

The liquid crystal used in the liquid crystal unit 130 may be used alone or in combination. The liquid crystal includes but is not limited to diaminobenzene liquid crystal, pyridazine liquid crystal, shiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal, etc., and cholesterol chloride, cholesterol nonanoate, cholesterol carbonate, etc. may be added as needed. carbonate), or chiral agents such as "C-15" and "CB-15" (Merck), or ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate.

The liquid crystal display element made by the liquid crystal alignment agent of the present invention is suitable for various nematic liquid crystals, such as TN, STN, TFT, VA, IPS and other liquid crystal display elements. In addition, according to the selected liquid crystal, it can also be used for different liquid crystal display elements such as strong induction or anti-strong induction. Among the above-mentioned liquid crystal display elements, it is particularly suitable for IPS type liquid crystal display elements.

The present invention will be further described with reference to the following embodiments, but it should be understood that these embodiments are merely illustrative and should not be construed as limitations on the implementation of the present invention.

<Implementation Example> Synthesis Example of Polymer (A)

The following is an example of the synthesis of polymer (A):

Synthesis Example A-1-1

A nitrogen inlet, a stirrer, a condenser and a thermometer were installed on a 500 ml four-necked conical flask, and nitrogen was introduced. Then, 0.096 g (0.00025 mol) of a diamine compound represented by formula (b-1-1) (hereinafter referred to as b-1-1), 6.078 g (0.04975 mol) of a diamine compound represented by formula (b-2-1) (hereinafter referred to as b-2-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added and stirred at room temperature until dissolved. Then, add 1.12 g (0.005 mol) of the tetracarboxylic acid dianhydride compound (hereinafter referred to as a-1-1), 9.815 g (0.045 mol) of benzene tetracarboxylic dianhydride (hereinafter referred to as a-2-1) and 20 g of NMP, and react at room temperature for 2 hours. After the reaction, pour the reaction solution into 1500 ml of water to precipitate the polymer, filter the obtained polymer, and repeat the steps of washing and filtering with methanol three times. After that, place the product in a vacuum oven and dry it at a temperature of 60°C to obtain the polymer (A-1-1) of Synthesis Example A-1-1, and its formula is shown in Table 1.

Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-3

Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-3 use the same preparation method as the preparation method of the polymer (A-1-1) of Synthesis Example A-1-1. The difference is that Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-3 change the type and amount of raw materials in the polymer. The formulas are shown in Tables 1 and 2, and are not described here in detail.

Synthesis Example A-2-1

A nitrogen inlet, a stirrer, a condenser and a thermometer were installed on a 500 ml four-necked conical flask, and nitrogen was introduced. Then, 0.096 g (0.00025 mol) of a diamine compound represented by formula (b-1-1) (hereinafter referred to as b-1-1), 6.078 g (0.04975 mol) of a diamine compound represented by formula (b-2-1) (hereinafter referred to as b-2-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added and stirred at room temperature until dissolved. Then, add 1.12 g (0.005 mol) of the tetracarboxylic dianhydride compound represented by formula (a-1-1) (hereinafter referred to as a-1-1), 9.815 g (0.045 mol) of benzene tetracarboxylic dianhydride (hereinafter referred to as a-2-1) and 20 g of NMP. After reacting at room temperature for 6 hours, add 97 g of NMP, 2.55 g of acetic anhydride and 19.75 g of pyridine, raise the temperature to 60°C, and continue stirring for 2 hours to carry out the imidization reaction. After the reaction is completed, pour the reaction solution into 1500 ml of water to precipitate the polymer. Then, the obtained polymer was filtered, washed with methanol and filtered three times repeatedly, placed in a vacuum oven, and dried at 60°C to obtain polymer (A-2-1), the formula of which is shown in Table 2.

Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Example A'-2-1

Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Example A'-2-1 use the same preparation method as the preparation method of the polymer (A-2-1) in Synthesis Example A-2-1. The difference is that Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Example A'-2-1 change the type and amount of raw materials in the polymer. The formula is shown in Table 2 and will not be described here.

In addition, the compounds corresponding to the abbreviations in Table 1 and Table 2 are shown below.

Embodiments of liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element

Implementation Example 1

Weigh 100 parts by weight of the polymer prepared in Synthesis Example A-1-1 (hereinafter referred to as A-1-1) and 800 parts by weight of N-methyl-2-pyrrolidone (NMP, hereinafter referred to as B-1), and stir and mix them at room temperature to prepare the liquid crystal alignment agent of Example 1.

The liquid crystal alignment agent prepared in Example 1 is rotationally coated on a glass substrate, and the glass substrate has a pixel electrode, wherein the pixel electrode is an IPS driving electrode having a pair of ITO electrodes (electrode width: 10μm, electrode spacing: 10μm, electrode height: 50nm), and the pair of ITO electrodes have a comb-like shape, and the comb-like parts of each other are configured in a separated and interlocking manner. Then, the glass substrate coated with the liquid crystal alignment agent is dried on a heating plate at 80°C, and after 5 minutes, it is baked in a hot air circulation oven at 250°C for 60 minutes to form a coating with a film thickness of 100nm.

The coated surface was irradiated with ultraviolet light of 254nm wavelength through a polarizing plate, and then the substrate was baked at 230℃ for 30 minutes to obtain a substrate with a liquid crystal alignment film. Then, similarly, a coating was formed on the opposite substrate and an alignment treatment was applied. The opposite substrate was a glass substrate without an electrode but with a columnar spacer with a height of 4μm.

The two substrates are a set, a sealant is printed on one of them, and the other is bonded in a way that it faces the liquid crystal alignment film and the alignment direction is 0°. Then, the sealant is hardened to produce an empty cell. After that, the liquid crystal MLC-2041 (Merck) is injected into the empty cell by the reduced pressure injection method, and the injection port is sealed to obtain the liquid crystal display element of Example 1.

Examples 2 to 20 and Comparative Examples 1 to 4

Examples 2 to 20 and Comparative Examples 1 to 4 use the same manufacturing method as that of Example 1 for the liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element. The difference is that the type and amount of raw materials in the liquid crystal alignment agent are changed. The formula and evaluation results are shown in Table 3 and Table 4, respectively, and will not be further described here.

In addition, the compounds corresponding to the abbreviations in Table 3 and Table 4 are shown below.

Evaluation method Flash after driving

The prepared liquid crystal display element is placed between two polarizing plates with polarization axes arranged in a vertically crossed manner. The LED backlight is turned on without applying voltage, and the configuration angle of the liquid crystal display element is adjusted to minimize the brightness of the light passing through. Then, an alternating voltage with a frequency of 30Hz is applied to the liquid crystal display element, and the V-T curve (voltage-transmittance curve) is measured at the same time. The alternating voltage with a relative transmittance of 23% is calculated as the driving voltage.

The method for measuring the flicker after driving is to turn off the LED backlight that has been turned on under the temperature condition that the temperature of the liquid crystal display element is 23℃, and then turn it on again after being placed in a dark place for 72 hours. At the same time as the backlight starts to light up, an AC voltage with a relative transmittance of 23% and a frequency of 30Hz is applied to the liquid crystal display element for 60 minutes, and the amplitude of the flicker is tracked. The amplitude of the flicker is read using a data acquisition/data recording switching device 34970A (made by Agilent technologies) connected to a photodiode and an I-V conversion amplifier to read the brightness value of the liquid crystal display element passing through the two polarizing plates and between them. The flicker (FL) is calculated according to the following formula (III). The lower the flicker, the better the quality of the liquid crystal display element made with the liquid crystal alignment agent.

In formula (III), z is the brightness value read when the above device 34970A is driven by an AC voltage with a relative transmittance of 23% and a frequency of 30Hz.

◎: FL<3%

○: 4%>FL≧3%

△: 5%>FL≧4%

╳: FL≧5%.

Evaluation results

From Table 3 and Table 4, it can be seen that compared with the liquid crystal display elements (Examples 1 to 20) made of the liquid crystal alignment agent containing the polymer (A) having the structure represented by formula (I), the liquid crystal display elements of Comparative Examples 1 to 4 that do not contain the polymer (A) having the structure represented by formula (I) have the problem of poor instant flicker.

In addition, when the diamine component (b) in the polymer (A) further contains 0.5 mol% to 50 mol% of the diamine compound (b1) (Examples 1, 3-14, 16-20), the flicker after driving of the formed liquid crystal display element can be further reduced.

In addition, when the diamine component (b) in the polymer (A) further contains a diamine compound (b2) (Examples 1, 3-6, 11-14, 16, 17, 19), the flicker after driving of the formed liquid crystal display element can be further reduced.

In summary, the liquid crystal alignment agent of the present invention uses a polymer (A) with a specific structure, so the liquid crystal alignment agent can improve the technical problem of poor instant flicker in the previous technology.

In addition, when the diamine component (b) in the polymer (A) contains a specific content of the diamine compound (b1) or the diamine compound (b2), the flicker after driving of the formed liquid crystal display element can be further reduced.

Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the attached patent application.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: First conductive film

116: First liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

Claims (10)

A liquid crystal alignment agent comprises: a polymer (A); and a solvent (B), wherein the polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in the following formula (I), and the diamine component (b) comprises a diamine compound (b1) having a structure as shown in the following formula (b-1):

In formula (I), ^Y1 represents a protecting group which is substituted by a hydrogen atom by heat, ^X1 and ^X2 each independently represent a divalent organic group, and * represents a bonding site.

In formula (b-1), ^{Y1 is Y1} in formula (I), ^X3 and ^X4 each independently represent an alkylene group having 1 to 3 carbon atoms, and ^X5 and ^X6 each independently represent a single bond, -O-, -S-, -OCO- or -COO-. The liquid crystal alignment agent as described in claim 1, wherein in the formula (I), ^Y1 represents a group represented by the following formula (II):

In formula (II), ^Y2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 3 to 20 carbon atoms, and * represents a bonding site. The liquid crystal alignment agent as described in claim 1, wherein the tetracarboxylic dianhydride component (a) comprises a tetracarboxylic dianhydride compound (a1) having a structure as shown in the following formula (a-1):

In formula (a-1), ^R1 to ^R4 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 having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group; ^R1 to ^R4 may be the same or different, and at least one of ^R1 , ^R2 , ^R3 and ^R4 is not a hydrogen atom. The liquid crystal alignment agent as described in claim 1, wherein the diamine component (b) comprises a diamine compound (b2) having a structure as shown in the following formula (b-2):

In formula (b-2), Ar represents an aromatic ring, ^X11 represents an alkylene group having 1 to 5 carbon atoms, and ^X12 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The liquid crystal alignment agent as described in claim 3, wherein the amount of the tetracarboxylic dianhydride component (a) used is 100 mol, and the amount of the tetracarboxylic dianhydride compound (a1) used is 10 mol to 100 mol. The liquid crystal alignment agent as described in claim 1, wherein the usage amount of the diamine component (b) is 100 mol, and the usage amount of the diamine compound (b1) is 0.5 mol to 50 mol. The liquid crystal alignment agent as described in claim 4, wherein the usage amount of the diamine component (b) is 100 mol, and the usage amount of the diamine compound (b2) is 1 mol to 99.5 mol. The liquid crystal alignment agent as described in claim 1, wherein the amount of the polymer (A) used is 100 parts by weight, and the amount of the solvent (B) used is 800 parts by weight to 4000 parts by weight. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 8. A liquid crystal display element, comprising a liquid crystal alignment film as described in claim 9.

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