TWI863615B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent which can lower contrast variability in pixel, a liquid crystal alignment film formed from the liquid crystal alignment agent, and a liquid crystal display element including the liquid crystal alignment film. The liquid crystal alignment agent comprises a polymer (A) having a specific structure.

Description

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

The present invention relates to a liquid crystal alignment agent, and in particular to a liquid crystal alignment agent capable of reducing contrast variation within a pixel, a liquid crystal alignment film formed by using the liquid crystal alignment agent, and a liquid crystal display element comprising the liquid crystal alignment film.

Liquid crystal display units are widely used as display components for personal computers, smart phones, portable phones, or television sets. Liquid crystal display units may include a liquid crystal layer sandwiched between a device substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and a thin film transistor (TFT) for switching the electronic signal supplied to the pixel electrode. As for the driving method of liquid crystal molecules, longitudinal electric field methods such as TN (Twisted Nematic) method and VA (Vertical Alignment) method, and transverse electric field methods such as IPS (In-Plane Switching) method and FFS (Fringe Field Switching) method are known.

At present, the most popular liquid crystal alignment film in the industry is made by rubbing the surface of a film composed of polyamide and/or polyimide obtained by imidization formed on an electrode substrate in one direction with a cloth such as cotton, nylon or polyester. Rubbing treatment is a simple and highly productive industrial method. However, with the high performance, high precision and large-scale liquid crystal display elements, the surface of the alignment film is scratched by dust, mechanical force and static electricity generated by the friction treatment, which leads to various problems such as unevenness in the alignment treatment surface. As an alignment treatment method instead of friction treatment, a photoalignment method is known to impart alignment ability to liquid crystals by irradiating polarized radiation. Regarding the photo-alignment method, Japanese Patent Publication No. 9-297313 discloses the use of a photoisomerization reaction, a photocrosslinking reaction, or a photodecomposition reaction.

However, when a liquid crystal display element using a conventional liquid crystal alignment film produced by a photo-alignment method is used to display black, the contrast variation within the pixel is relatively large, which in turn causes the brightness within the screen to vary, and there is a concern that the display quality will be reduced.

The purpose of the present invention is to provide a liquid crystal alignment film that can effectively reduce contrast variation within a pixel, a liquid crystal alignment agent for obtaining the liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film.

The inventors of this case have made great efforts to achieve the above-mentioned goal and have found that a liquid crystal alignment film formed by a liquid crystal alignment agent containing a polymer with a specific structure is very effective in achieving the above-mentioned purpose, thus completing the present invention.

In view of this, one aspect of the present invention is to provide a liquid crystal alignment agent, which includes a polymer (A). The liquid crystal alignment film formed by the liquid crystal alignment agent can effectively reduce the contrast variation within the pixel of the liquid crystal display element.

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

Another aspect of the present invention is to provide a liquid crystal display unit, which includes the aforementioned liquid crystal alignment film and has a lower intra-pixel contrast variation.

According to the above-mentioned aspects of the present invention, a liquid crystal alignment agent is proposed. The liquid crystal alignment agent of the present invention contains a polymer (A). A preferred embodiment of the liquid crystal alignment agent of the present invention can be listed as a liquid crystal alignment agent containing a polymer (A) and an organic solvent. In addition, the liquid crystal alignment agent of the present invention may also contain a polymer other than the polymer (A) (such as the polymer (B) described later).

Polymer (A)

The polymer (A) of the present invention can be selected from at least one polymer in the group consisting of a polyimide precursor obtained by reacting a tetracarboxylic acid derivative component (a1) and a diamine component (a2), and an imidized polymer of a polyimide precursor. For example, the polymer (A) can include a polyimide precursor having an imide precursor structure such as polyamic acid and polyamic acid ester. The diamine component (a2) can include a diamine compound (a2-1) shown in the following formula (A21). (A21)

In formula (A21), Y ₁₁ represents a alkyl group having 1 to 10 carbon atoms; and n and m each independently represent 0 to 3.

Tetracarboxylic acid derivative component (a1)

The tetracarboxylic acid derivative component (a1) that reacts with the diamine component (a2) may be a tetracarboxylic acid dianhydride compound, or a tetracarboxylic acid dianhydride derivative such as a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide. The tetracarboxylic acid derivative component (a1) may be a single tetracarboxylic acid dianhydride compound or a derivative thereof, or may be a mixture of a plurality of such tetracarboxylic acid dianhydride compounds.

The tetracarboxylic acid derivative component (a1) of the present invention may include an alicyclic tetracarboxylic dianhydride compound (a1-1) represented by formula (A11) and other tetracarboxylic dianhydride compounds (a1-2).

Alicyclic tetracarboxylic dianhydride compound (a1-1)

The tetracarboxylic acid derivative component (a1) used for the reaction to obtain the polymer (A) may include an alicyclic tetracarboxylic dianhydride compound (a1-1) or a derivative thereof as shown in the following formula (A11). The alicyclic tetracarboxylic dianhydride compound (a1-1) or a derivative thereof as shown in the formula (A11) may be composed of a single tetracarboxylic dianhydride compound or a derivative thereof, or may be composed of a plurality of tetracarboxylic dianhydride compounds or derivatives thereof. In the present invention, the alicyclic tetracarboxylic dianhydride compound (a1-1) as shown in the formula (A11) may be, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an alicyclic structure. However, none of the four carboxyl groups are bonded to an aromatic ring. Alternatively, it is not necessary to be composed of only alicyclic structures, and a part of it may have a chain hydrocarbon structure or an aromatic ring structure. Aromatic tetracarboxylic dianhydride may be, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an aromatic ring. However, it is not necessary to be composed of only an aromatic ring structure, and a part of it may have a chain hydrocarbon structure or an alicyclic structure. Non-cyclic aliphatic tetracarboxylic dianhydride may be, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. However, it is not necessary to be composed of only alicyclic hydrocarbon structures, and a part of it may have alicyclic structures or an aromatic ring structure. (A11)

In formula (A11), _X1 can be selected from at least one of the group consisting of the structures shown in formula (A11-1) to formula (A11-7) below, and "*" represents a bonding position. (A11-1) (A11-2) (A11-3) (A11-4) (A11-5) (A11-6) (A11-7)

In formula (A11-1), _X11 , _X12 , _X13 and _X14 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. In formula (A11-7), _X15 and _X16 independently represent a hydrogen atom or a methyl group.

In some embodiments, _X1 can represent the structures shown in the following formulas (A11-1-1) to (A11-1-6). (A11-1-1) (A11-1-2) (A11-1-3) (A11-1-4) (A11-1-5) (A11-1-6)

Preferably, _X1 represents a structure represented by formula (A11-1-1). When _X1 represents a structure represented by formula (A11-1-1), a liquid crystal display unit including a liquid crystal alignment film formed therefrom has a lower intra-pixel contrast variation.

Based on the total usage amount of the tetracarboxylic acid derivative component (a1) being 100 mol, the usage amount of the alicyclic tetracarboxylic dianhydride compound (a1-1) represented by formula (A11) is 30 mol to 100 mol, preferably 40 mol to 100 mol, and more preferably 50 mol to 100 mol.

Other tetracarboxylic dianhydride compounds (a1-2)

Other tetracarboxylic dianhydride compounds (a1-2) may include tetracarboxylic dianhydride compounds represented by the following formula (A12) and derivatives thereof. (A12)

In formula (A12), X ₁ ′ may represent a structure as shown in the following formula (A12-1) to formula (A12-32), wherein “*” represents a bonding position. (A12-1) (A12-2) (A12-3) (A12-4) (A12-5) (A12-6) (A12-7) (A12-8) (A12-9) (A12-10) (A12-11) (A12-12) (A12-13) (A12-14) (A12-15) (A12-16) (A12-17) (A12-18) (A12-19) (A12-20) (A12-21) (A12-22) (A12-23) (A12-24) (A12-25) (A12-26) (A12-27) (A12-28) (A12-29) (A12-30) (A12-31) (A12-32)

In formula (A12-5) and formula (A12-6), X ₁₁ ' and X ₁₂ ' each independently represent a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group or an amide group, and in formula (A12-6), a plurality of X ₁₂ ' may be the same as or different from each other. a1 in formula (A12-5) represents an integer of 0 or 1. a1 in formula (A12-6) represents an integer of 0 or 1. In formula (A12-14), X ₁₃ ' 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, and a plurality of X ₁₃ ' may be the same as or different from each other. From the viewpoint of liquid crystal alignment, X ₁₃ ′ preferably represents a hydrogen atom, a halogen atom, a methyl group or an ethyl group, and more preferably represents a hydrogen atom or a methyl group.

In some specific examples, the aforementioned formula (A12-5) and formula (A12-6) may include but are not limited to the structures shown below.

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

Based on the total usage of the tetracarboxylic acid derivative component (a1) being 100 mol, the usage of the other tetracarboxylic dianhydride compound (a1-2) may be 0 mol to 70 mol, preferably 0 mol to 60 mol, and more preferably 0 mol to 50 mol.

Diamine component (a2)

The diamine component (a2) of the present invention may include a diamine compound (a2-1), a diamine compound (a2-2), a diamine compound (a2-3), a diamine compound (a2-4) and other diamine compounds (a2-5).

Diamine compound (a2-1)

The diamine component (a2) of the present invention comprises a diamine compound (a2-1) represented by the following formula (A21). (A21)

In formula (A21), Y ₁₁ represents a alkyl group having 1 to 10 carbon atoms; and n and m each independently represent 0 to 3.

From the viewpoint of synthesis and orientation, the diamine compound (a2-1) represented by formula (A21) may preferably include a diamine compound represented by the following formula (A21'). Further, the hydrogen atoms on the benzene rings bonded to the amino groups at both ends in formula (A21) may be substituted, such as 1 to 2 hydrogen atoms on the benzene rings are substituted with halogen, alkyl having 1 to 3 carbon atoms, alkoxy having 1 to 3 carbon atoms, fluoroalkyl having 1 to 3 carbon atoms, or fluoroalkoxy having 1 to 3 carbon atoms. (A21')

In formula (A21'), Y ₁₁ , m and n are defined as above.

The alkyl group represented by Y ₁₁ is at least one selected from the group consisting of an aliphatic chain alkyl group, an aliphatic cyclic alkyl group and an aromatic alkyl group.

The aforementioned aliphatic chain alkyl refers to a straight chain or branched chain alkyl that does not contain a ring structure in the main chain and is composed only of a chain structure, which may be saturated or unsaturated. The aforementioned aliphatic cyclic alkyl refers to a alkyl group that contains an alicyclic structure and does not contain an aromatic ring structure. However, the aliphatic cyclic alkyl group does not have to be composed only of alicyclic alkyl groups, and some of them may have a chain structure.

In the specific example of an aliphatic chain alkyl group having a carbon number of 1 to 10, these alkyl groups may include saturated and unsaturated aliphatic chain alkyl groups. The saturated aliphatic chain alkyl group may be a saturated straight chain or branched chain alkyl group. The saturated straight chain alkyl group may include, but is not limited to, a methylene group, an ethylene group, a propanediyl group, a butanediyl group, a pentanediyl group, a hexanediyl group, a heptanediyl group, an octanediyl group, a nonanediyl group, or a decanediyl group. The saturated branched chain alkyl group may include, but is not limited to, a second butanediyl group, a third butanediyl group, an isopentanediyl group, a third pentanediyl group, an isooctanediyl group, a 2-ethylhexanediyl group, a third octanediyl group, an isononanediyl group, or an isodecanediyl group.

The unsaturated aliphatic chain hydrocarbon group may include an unsaturated chain hydrocarbon group having an unsaturated bond (such as an olefinic bond and/or an alkynyl bond), and these groups may also be straight chains or branched chains. For example, the unsaturated aliphatic chain hydrocarbon group may include but is not limited to ethylenediyl, heptenediyl, 2-butenediyl, 3-methyl-4-ethyl-1-hexenediyl, propynediyl, 2-hexynediyl, 3-methyl-1-pentynediyl, 3-ethyl-1-heptynediyl or 3,5-dimethyl-4-hexene-1-heptynediyl. In addition, specific examples of the alicyclic hydrocarbon group having 3 to 10 carbon atoms include, but are not limited to, cyclobutanediyl, cyclopentanediyl, cyclohexanediyl, and cycloheptanediyl, and the hydrogen atoms on the aforementioned rings may be substituted.

The aromatic hydrocarbon group may include, but is not limited to, a benzene ring, a naphthyl ring, a tetrahydronaphthyl ring, an azulene ring, an indene ring, a fluorene ring, an anthracene ring, a phenanthrene ring or a phenalene ring.

In formula (A21), Y ₁₁ preferably represents an aliphatic chain hydrocarbon group having 1 to 5 carbon atoms, and more preferably represents a saturated linear hydrocarbon group having 1 to 3 carbon atoms. When Y ₁₁ in formula (A21) represents an aliphatic chain hydrocarbon group having 1 to 5 carbon atoms, the liquid crystal alignment agent prepared will allow the formed liquid crystal display element to have a lower intra-pixel contrast variability. When Y ₁₁ represents a saturated linear hydrocarbon group having 1 to 3 carbon atoms, the intra-pixel contrast variability of the formed liquid crystal display element can be further reduced.

In some specific examples, the diamine compound (a2-1) represented by formula (A21) may include but is not limited to the diamine compounds represented by the following formulas (A21-1) to (A21-10). (A21-1) (A21-2) (A21-3) (A21-4) (A21-5) (A21-6) (A21-7) (A21-8) (A21-9) (A21-10)

The aforementioned diamine compound (a2-1) may be used alone or in combination of two or more.

Based on the total usage amount of the diamine component (a2) being 100 mol, the usage amount of the diamine compound (a2-1) may be 1 mol to 95 mol, preferably 5 mol to 90 mol, and more preferably 10 mol to 85 mol.

If the diamine component (a2) does not contain the diamine compound (a2-1) represented by formula (A21), the resulting liquid crystal alignment agent will cause the formed liquid crystal display element to have excessively high intra-pixel contrast variation.

The main synthesis method of the diamine compound (a2-1) is described in detail below. The method described below is only for illustration, and the preparation of the diamine compound (a2-1) of the present invention is not limited thereto.

For example, the diamine compound represented by formula (A21-8) can be prepared by reducing a dinitro compound to convert the nitro group into an amino group according to the reaction formula (S21-1) shown below. (S21-1)

The reduction method of the dinitro compound is not particularly limited. For example, palladium-carbon, platinum oxide, Raney nickel, platinum black, rhodium-alumina or platinum sulfide-carbon can be used as a catalyst, and the reduction can be carried out by hydrogen, hydrazine and hydrogen chloride in a solvent such as ethyl acetate, toluene, tetrahydrofuran, dioxane and/or alcohol. It can also be carried out under pressure using an autoclave as needed. On the other hand, when the substituent structure of the hydrogen atom of the benzene ring or saturated alkyl contains an unsaturated bond, when palladium-carbon or platinum sulfide-carbon is used, the unsaturated bond of the substituent may be reduced to a saturated bond. Therefore, it is preferred to use a transition metal such as reduced iron, tin or tin chloride as a catalyst.

The aforementioned dinitro compound can be synthesized by reaction as shown in the following reaction formula (S21-2), which can be obtained by reacting a commercially available aliphatic or aromatic diol derivative with nitrobenzene substituted with a leaving group (X). The leaving group (X) is preferably, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a toluene sulfonate (-OTs) or a mesylate (-OMs). (S21-2)

The reaction shown in reaction formula (S21-2) can be carried out in the presence of a base. The base used is not particularly limited as long as it can be synthesized, and examples thereof include inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alkoxide, potassium alkoxide, sodium hydroxide, potassium hydroxide and/or sodium hydroxide; and organic bases such as pyridine, dimethylaminopyridine, trimethylamine, triethylamine and/or tributylamine. Depending on the situation, when a palladium catalyst or a copper catalyst such as dibenzylideneacetone palladium or diphenylphosphinoferrocene palladium is used in combination, the yield can be increased. From the viewpoint of easy synthesis, the method using pyridine is preferred, but methods other than this method can also synthesize the dinitro compound, so the method for synthesizing the dinitro compound is not particularly limited.

Diamine compound (a2-2)

The diamine component (a2) of the present invention may include a diamine compound (a2-2) represented by the following formula (A22). (A22)

In formula (A22), R ₁ , R ₂ and R ₃ each independently represent a divalent organic group of a benzene ring or a pyridine ring; R ₄ represents an oxygen atom or a sulfur atom; R ₅ represents a divalent chain hydrocarbon group having 1 to 30 carbon atoms or an alicyclic hydrocarbon group having 3 to 30 carbon atoms; R ₆ and R ₇ each independently represent a single bond, an oxygen atom, a sulfur atom or -NR ₈ -, wherein at least one of R ₆ and R ₇ represents an oxygen atom, a sulfur atom or -NR ₈ -, and R ₈ represents a hydrogen atom or a methyl group; when any one of R ₁ , R ₂ and R ₃ is a pyridine ring, R ₆ and R ₇ do not represent a single bond. When the diamine component (a2) comprises a diamine compound (a2-2) as represented by formula (A22), the resulting liquid crystal alignment agent will allow the formed liquid crystal display element to have a lower intra-pixel contrast variation.

Preferably, R ₅ represents a divalent chain alkyl group having a carbon number of 1 to 30; more preferably, R ₅ represents a divalent chain alkyl group having a carbon number of 1 to 11; and particularly preferably, R ₅ represents a linear alkyl group having a carbon number of 1 to 11. When R ₅ represents the aforementioned substituent, the resulting liquid crystal display element containing the liquid crystal alignment agent has a lower intra-pixel contrast variation.

The chain alkyl represented by R ₅ above refers to a straight chain or branched chain alkyl group that does not contain a ring structure in the main chain and is composed only of a chain structure, which may be saturated or unsaturated. The alicyclic alkyl group represented by R ₅ above refers to a alkyl group that contains an alicyclic structure and does not contain an aromatic ring structure. However, it is not necessary to be composed only of alicyclic alkyl groups, and some of them may have a chain structure.

In the specific example of the chain alkyl group having 1 to 30 carbon atoms, these alkyl groups may include saturated and unsaturated chain alkyl groups. The saturated chain alkyl group may be a saturated straight chain or branched chain alkyl group. The saturated straight chain alkyl group may be, for example, methylene, ethylidene, propanediyl, butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonanediyl, decanediyl, dodecanediyl, tetradecanediyl, pentadecanediyl, hexadecanediyl and octadecanediyl. The saturated branched chain alkyl group may be, for example, sec-butanediyl, tert-butanediyl, isopentanediyl, tert-pentanediyl, isooctanediyl, 2-ethylhexanediyl, tert-octanediyl, isononanediyl and isodecanediyl.

The unsaturated chain hydrocarbon group may include unsaturated chain hydrocarbon groups having unsaturated bonds (such as olefinic bonds and/or acetylene bonds), and these groups may also be straight chains or branched chains. For example: ethylenediyl, heptenediyl, 2-butenediyl, 3-methyl-4-ethyl-1-hexenediyl, propynediyl, 2-hexynediyl, 3-methyl-1-pentynediyl, 3-ethyl-1-heptynediyl and 3,5-dimethyl-4-hexene-1-heptynediyl. In addition, specific examples of alicyclic hydrocarbon groups having 3 to 30 carbon atoms may include cyclobutanediyl, cyclopentanediyl, cyclohexanediyl, cycloheptanediyl and groups in which hydrogen atoms on the rings are substituted.

In some specific examples, the diamine compound (a2-2) represented by formula (A22) may include but is not limited to the following specific diamine compounds. (A22-1) (A22-2) (A22-3) (A22-4) (A22-5) (A22-6) (A22-7) (A22-8) (A22-9) (A22-10) (A22-11) (A22-12) (A22-13) (A22-14) (A22-15) (A22-16) (A22-17) (A22-18) (A22-19) (A22-20) (A22-21) (A22-22) (A22-23) (A22-24) (A22-25) (A22-26) (A22-27) (A22-28) (A22-29) (A22-30) (A22-31) (A22-32) (A22-33) (A22-34) (A22-35) (A22-36) (A22-37) (A22-38)

In formula (A22-1), formula (A22-3), formula (A22-5), formula (A22-6), formula (A22-8), formula (A22-14), and formula (A22-24) to formula (A22-34), Ra represents a hydrogen atom or a methyl group, but is not limited thereto and may also represent other groups.

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

In the synthesis of a fully obtained polymer (A) (such as polyamine (PAA)), based on the usage of the diamine component (a2) being 100 mol, the usage of the diamine compound (a2-2) shown in formula (A22) is 5 mol to 99 mol, preferably 7 mol to 95 mol, and more preferably 10 mol to 40 mol.

The main synthesis method of the diamine compound (a2-2) is described in detail below. The method described below is only for illustration, and the preparation of the diamine compound (a2-2) of the present invention is not limited thereto.

For example, the diamine compound represented by formula (A22-7) can be prepared by reducing a dinitro compound to convert the nitro group into an amino group according to the reaction formula (S22-1) shown below. (S22-1)

The reduction method of the dinitro compound is not particularly limited. Examples include palladium-carbon, platinum oxide, Raney nickel, platinum black, rhodium-alumina, platinum sulfide-carbon, etc. as catalysts, and reduction by hydrogen, hydrazine, and hydrogen chloride in solvents such as ethyl acetate, toluene, tetrahydrofuran, dioxane, and alcohols. It is also possible to use an autoclave under pressure as needed. On the other hand, when the substituent structure of the hydrogen atom of the substituted benzene ring or saturated alkyl contains an unsaturated bond, when palladium-carbon or platinum sulfide-carbon is used, the unsaturated bond may be reduced to a saturated bond. Therefore, it is preferred to use a transition metal such as reduced iron, tin or tin chloride as a reducing condition for the catalyst.

The aforementioned dinitro compound can be synthesized by reaction as shown in the following reaction formula (S22-2), which can be obtained by reacting a commercially available diphenyl ether derivative, a phenoxypyridine derivative or a bipyridine ether derivative with nitrobenzene or nitropyridine substituted with a leaving group (X). The leaving group (X) is preferably, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a toluene sulfonate (-OTs) or a mesylate (-OMs). (S22-2)

The reaction shown in reaction formula (S21-2) can be carried out in the presence of a base. The base used is not particularly limited as long as it can be synthesized, and examples thereof include inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alkoxide, potassium alkoxide, sodium hydroxide, potassium hydroxide and/or sodium hydroxide; and organic bases such as pyridine, dimethylaminopyridine, trimethylamine, triethylamine and/or tributylamine. Depending on the situation, when a palladium catalyst or a copper catalyst such as dibenzylideneacetone palladium or diphenylphosphinoferrocene palladium is used in combination, the yield can be increased. From the viewpoint of easy synthesis, the method using potassium carbonate is preferred, but other methods are also possible, and therefore the method for synthesizing the dinitro compound is not particularly limited.

Diamine compound (a2-3)

The diamine component (a2) of the present invention may include a diamine compound (a2-3), and the diamine compound (a2-3) may include a diamine compound represented by the following formula (A23-1) or formula (A23-2). (A23-1) (A23-2)

In formula (A23-1), Y ₃₁ represents a divalent organic group as shown in formula (A23-3). A plurality of Y _32s each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (A23-2), a plurality of Y _33s each independently represents a divalent organic group as shown in formula (A23-3'). (A23-3) (A23-3')

In formula (A23-3), Ar independently represents a divalent benzene ring, a biphenyl structure or a naphthyl ring, and the hydrogen atom of the benzene ring, the biphenyl structure or the naphthyl ring may be substituted by a monovalent substituent group or may not be substituted; Y ₃₁ ' represents -(CH ₂ ) _n -, n represents an integer from 2 to 18, and at least one -CH ₂ - in -(CH ₂ ) _n - may be substituted by -O-, -C(=O)- or -OC(=O)- or may not be substituted; p1 represents an integer of 0 or 1; "*" represents a bonding position.

In formula (A23-3'), Ar' independently represents a divalent benzene ring or a biphenyl structure, and the hydrogen atom of the benzene ring or the biphenyl structure may be substituted by a monovalent substituent group or may not be substituted; Y ₃₃ ' represents -(CH ₂ ) _n -, n represents an integer from 2 to 18, and at least one -CH ₂ - in -(CH ₂ ) _n - may be substituted by -O-, -C(=O)- or -OC(=O)- or may not be substituted; p2 represents an integer of 0 or 1; "*" represents a bonding position.

The monovalent substituent of the aforementioned benzene ring, biphenyl structure, or naphthyl ring may be, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, a cyano group, or a nitro group.

From the perspective of improving the liquid crystal alignment, the divalent organic group represented by formula (A23-3) may preferably include groups represented by the following formulas (A23-3-1) to (A23-3-16), wherein "*" represents the bonding position. (A23-3-1) (A23-3-2) (A23-3-3) (A23-3-4) (A23-3-5) (A23-3-6) (A23-3-7) (A23-3-8) (A23-3-9) (A23-3-10) (A23-3-11) (A23-3-12) (A23-3-13) (A23-3-14) (A23-3-15) (A23-3-16)

In formula (A23-3-14), the multiple m's independently represent integers from 1 to 3.

From the viewpoint of improving the liquid crystal alignment, the divalent organic group represented by formula (A23-3') may preferably include groups represented by formulas (A23-3-7) to (A23-3-16).

When the diamine compound (a2-3) contains a plurality of diamine compounds as shown in formula (A23-1), it is preferably a combination of a diamine compound in which Y ₃₁ in formula (A23-1) represents a diamine compound of formula (A23-3-1) to formula (A23-3-14) and a diamine compound in which Y ₃₁ in formula (A23-1) represents a diamine compound of formula (A23-3-15) to formula (A23-3-16).

In some specific examples, the diamine compound represented by the aforementioned formula (A23-2) may include but is not limited to the diamine compounds represented by the following formulas (A23-2-1) to (A23-2-5). (A23-2-1) (A23-2-2) (A23-2-3) (A23-2-4) (A23-2-5)

The aforementioned diamine compounds (a2-3) may be used alone or in combination of two or more.

Based on the total usage amount of the diamine component (a2) being 100 mol, the usage amount of the diamine compound (a2-3) may be 5 mol to 99 mol, preferably 10 mol to 90 mol, and more preferably 15 mol to 87 mol.

Diamine compound (a2-4)

From the viewpoint of improving the voltage retention rate of the liquid crystal display element, the molecular structure of the polymer (A) may selectively have an -N(D)- group (wherein D represents a carbamate-based protective group). The polymer (A) having an -N(D)- group may be obtained by using a monomer having an -N(D)- group as at least a part of the reaction raw material, or by using it as a capping agent as described later. In some specific examples, the monomer having an -N(D)- group may be, for example, a diamine compound (a2-4) having an -N(D)- group. For example, the carbamate-based protective group may include, but is not limited to, tert-butyloxycarbonyl and 9-fluorenylmethoxycarbonyl.

Preferably, the diamine compound (a2-4) having an -N(D)- group includes a diamine compound having at least one aromatic group such as a benzene ring. More preferably, the diamine compound (a2-4) having an -N(D)- group includes a diamine compound having at least one aromatic group such as a benzene ring, and the residue other than the substituent (D) has a carbon number of 6 to 30. In some specific examples, the diamine compound (a2-4) having an -N(D)- group may include but is not limited to the diamine compounds shown in the following formulas (A24-1) to (A24-10). (A24-1) (A24-2) (A24-3) (A24-4) (A24-5) (A24-6) (A24-7) (A24-8) (A24-9) (A24-10)

The aforementioned diamine compounds (a2-4) may be used alone or in combination of two or more.

Based on the total usage amount of the diamine component (a2) being 100 mol, the usage amount of the diamine compound (a2-4) may be 5 mol to 99 mol, preferably 10 mol to 52 mol, and more preferably 15 mol to 37 mol.

Other diamine compounds (a2-5)

In addition to the aforementioned diamine compound (a2-1) as represented by formula (A21), the diamine compound (a2-2) as represented by formula (A22), the diamine compound (a2-3) and the diamine compound (a2-4), the diamine component (a2) used to obtain the polymer (A) may optionally include other diamine compounds (a2-5). For example, other diamine compounds (a2-5) may include but are not limited to: 4,4'-diaminoazobenzene or diamine compounds represented by the following formulas (A25-1) to (A25-3) and other diamine compounds having a photo-alignment group; 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol or 4,6-diaminoresorcinol; 2,4-diaminoazobenzene; Benzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid or a diamine compound having a carboxyl group such as a diamine compound represented by the following formula (A25-4) to (A25-7); 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ketone, 1,4-bis(4-aminobenzyl)benzene, 4,4'-diaminodiphenyl Aminodiphenyl ether, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-dihydroindene-5-amine or 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine; diamine compounds having a urea bond such as diamine compounds represented by the following formulas (A25-8) to (A25-10); diamine compounds having a urea bond such as diamine compounds represented by the following formulas (A25-11) to (A25-13); Diamine compounds having an amide bond; diamine compounds having a photopolymerizable group at the end such as 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallylaniline; diamine compounds having a siloxane bond, such as 3-bis(3-aminopropyl)-tetramethyldisiloxane; diamine compounds having an oxazoline structure such as diamine compounds represented by the following formulas (A25-14) to (A25-15). (A25-1) (A25-2) (A25-3) (A25-4) (A25-5) (A25-6) (A25-7) (A25-8) (A25-9) (A25-10) (A25-11) (A25-12) (A25-13) (A25-14) (A25-15)

In formula (A25-4), _Y51 represents a single bond, _-CH2- , _-C2H4- , -C( _CH3 ) _2- , _-CF2- , -C( _CF3 ) _2- , -O-, _-CO- , -NH-, _-N ( _CH3 )-, -CONH-, -NHCO-, -CH2O-, _-OCH2- , -COO-, -OCO-, -CON( _CH3 )- or -N( _CH3 )CO-; m1 and m2 each independently represent an integer of 0 to 4, and (m1+m2) represents an integer of 1 to 4. In formula (A25-5), m3 and m4 each independently represent an integer of 1 to 5. In formula (A25-6), _Y52 represents a linear or branched alkyl group having 1 to 5 carbon atoms; m5 represents an integer from 1 to 5. In formula (A25-7) _{, Y53} and _Y54 each independently represent a single bond, _-CH2- , _-C2H4- , -C( _CH3 ) _2- , -CF2-, -C( _CF3 ) _2- , -O-, _-CO- , -NH-, -N _{( CH3} )-, -CONH-, -NHCO-, -CH2O-, _-OCH2- , -COO-, -OCO-, -CON( _CH3 )- or -N( _CH3 )CO-; m6 represents an integer from 1 to 4.

The other diamine compounds (a2-5) mentioned above may be used alone or in combination of two or more.

Based on the total usage amount of the diamine component (a2) being 100 mol, the usage amount of the other diamine compound (a2-5) may be 5 mol to 99 mol, preferably 10 mol to 52 mol, and more preferably 15 mol to 37 mol.

Polymer (B)

In addition to the aforementioned polymer (A), the liquid crystal alignment agent of the present invention may also optionally contain a polymer (B) selected from the group consisting of a polyimide precursor obtained by using a tetracarboxylic acid derivative component (b1) and a diamine component (b2), and an imidized polymer (i.e., polyimide) of the polyimide precursor. For example, the polymer (B) may include, but is not limited to, at least one polymer selected from the group consisting of a polyimide precursor obtained by reacting a tetracarboxylic acid derivative component (b1) and a diamine component (b2) that does not contain the aforementioned specific diamine compound (e.g., the diamine compound (a2-1) shown in formula (A21)) and an imidized product (i.e., polyimide) of the polyimide precursor. Specific examples of the polyimide precursor include polyamic acid or polyamic acid ester, etc. The polymer (B) may be used alone or in combination of two or more.

The usage ratio of polymer (A) to polymer (B) (i.e., the mass ratio of [polymer (A)]/[polymer (B)]) may be 10/90 to 90/10, preferably 20/80 to 90/10, and more preferably 20/80 to 80/20.

Tetracarboxylic acid derivative component (b1)

The tetracarboxylic acid derivative component (b1) used to obtain the polymer (B) may include, for example, but not limited to, a non-cyclic aliphatic tetracarboxylic acid dianhydride compound, alicyclic tetracarboxylic acid dianhydride compound, aromatic tetracarboxylic acid dianhydride compound, or derivatives of these compounds. Specific examples of the non-cyclic aliphatic tetracarboxylic acid dianhydride compound, alicyclic tetracarboxylic acid dianhydride compound, and aromatic tetracarboxylic acid dianhydride compound may include, for example, the tetracarboxylic acid dianhydride compound exemplified for the aforementioned polymer (A). Preferably, the tetracarboxylic acid derivative component (b1) may include an alicyclic tetracarboxylic acid dianhydride or a derivative thereof (a1-1) as shown in the above formula (A11), or a tetracarboxylic acid dianhydride compound or a derivative thereof as shown in the above formula (A12) and X ₁ ' represents a structure shown in formula (A12-1) to formula (A12-6). The tetracarboxylic acid derivative component (b1) may be used alone or in combination of a plurality of them.

The tetracarboxylic acid derivative component (b1) preferably comprises a tetracarboxylic dianhydride compound represented by the above formula (A12) and wherein X ₁ ′ represents a structure represented by the following formula (A12-33) (hereinafter referred to as a tetracarboxylic dianhydride compound (b1-1)). (A12-33)

In the formula (A12-33), Z ₁₁ represents a single bond; and "*" represents a bonding position.

The aforementioned tetracarboxylic dianhydride compound (b1-1) may be used alone or in combination of two or more.

More preferably, the tetracarboxylic acid derivative component (b1) comprises a tetracarboxylic dianhydride compound represented by the following formula (B11). (B11)

Based on the total usage of the tetracarboxylic acid derivative component (b1) being 100 mol, the usage of the tetracarboxylic dianhydride compound (b1-1) may be 30 mol to 100 mol, preferably 40 mol to 100 mol, and more preferably 50 mol to 100 mol.

Diamine component (b2)

The diamine component (b2) used to obtain the polymer (B) may include, for example, but is not limited to, the aforementioned diamine component (a2), or a diamine compound having at least one nitrogen-containing atom structure selected from the group consisting of a nitrogen-containing heterocyclic ring, a diamine group, and a tertiary amine group (hereinafter referred to as a diamine compound (b2-1)), but the diamine component (b2) does not include the aforementioned diamine compound (a2-1).

The diamine component (b2) may be used alone or in combination of two or more.

Diamine compound (b2-1)

The diamine compound (b2-1) having the above-mentioned specific nitrogen-containing atom structure may have a nitrogen-containing heterocyclic ring, such as pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, tantalum, , pyridine , indole, benzimidazole, purine, quinoline, isoquinoline, oxadiazole, quinazoline, tether ,three , carbazole, acridine, piperidine, piperidine , pyrrolidine or hexamethyleneimine, etc. Among them, pyridine, pyrimidine, pyrrolidine , piperidine, piperidine , quinoline, carbazole or acridine is preferred.

The diamine compound (b2-1) having the above-mentioned specific nitrogen atom-containing structure may include a diamine group and a tertiary amine group as represented by the following formula (B21). (B21)

In formula (B21), Z represents a hydrogen atom or an alkyl group, a cycloalkyl group or an aryl group having 1 to 10 carbon atoms; "*" represents the bonding position to the alkyl group.

The alkyl represented by Z may include, but not limited to, methyl, ethyl or propyl; the cycloalkyl represented by Z may include, but not limited to, cyclohexyl; the aryl represented by Z may include, but not limited to, phenyl or tolyl. Z is preferably a hydrogen atom or a methyl group.

Specific examples of the diamine compound (b2-1) having the above-mentioned specific nitrogen atom-containing structure include: 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperidin , 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, diamine compounds represented by the following formulas (B21-1) to (B21-8), or diamine compounds represented by the following formulas (B21-9) to (B21-26). (B21-1) (B21-2) (B21-3) (B21-4) (B21-5) (B21-6) (B21-7) (B21-8) (B21-9) (B21-10) (B21-11) (B21-12) (B21-13) (B21-14) (B21-15) (B21-16) (B21-17) (B21-18) (B21-19) (B21-20) (B21-21) (B21-22) (B21-23) (B21-24) (B21-25) (B21-26)

The diamine compound (b2-1) may be used alone or in combination of two or more.

Based on the total usage amount of the diamine component (b2) being 100 mol, the usage amount of the diamine compound (b2-1) may be 15 mol to 100 mol, preferably 20 mol to 90 mol, and more preferably 25 mol to 80 mol.

Polymer production method

The production of polymer (A) or polymer (B) can be carried out by reacting the aforementioned diamine component and tetracarboxylic acid derivative component in a solvent (polycondensation). When a portion of polymer (A) or polymer (B) has an acylamidinic acid structure, for example, by reacting the tetracarboxylic acid derivative component with the diamine component, a polymer having an acylamidinic acid structure (i.e., polyacylamidinic acid) can be obtained. The aforementioned solvent is not particularly limited, and it only needs to be able to dissolve the formed polymer. For example, specific examples of the solvent may include but are not limited to N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-2-imidazolidinone. In some specific examples, when the solvent solubility of the polymer is high, the solvent may include methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or a solvent as shown in the following formula (D-1) to formula (D-3). In formula (D-1), Z ₁ represents an alkyl group with a carbon number of 1 to 3. In formula (D-2), Z ₂ represents an alkyl group with a carbon number of 1 to 3. In formula (D-3), Z ₃ represents an alkyl group with a carbon number of 1 to 4. (D-1) (D-2) (D-3)

The aforementioned solvents can be used alone or in combination. Secondly, even if the solvent cannot dissolve the polymer, it can still be mixed with the aforementioned solvents within the range that the generated polymer will not precipitate. When the diamine component and the tetracarboxylic acid derivative component react in the solvent, the reaction can be carried out at any concentration, but preferably 1 wt% to 50 wt%, and more preferably 5 wt% to 30 wt%. The reaction can also be carried out at a high concentration initially, and then additional solvent is added. During the reaction, the ratio of the total molar number of the diamine component to the total molar number of the tetracarboxylic acid derivative component is preferably 0.8 to 1.2. Similar to the general polycondensation reaction, the closer this molar ratio is to 1.0, the greater the molecular weight of the polymer (A) or polymer (B) formed.

A polymer having an acylamidate structure can be obtained, for example, by the following known methods: (1) a method of further reacting the polyacylamidate obtained by the above method with an esterifying agent, (2) a method of reacting a tetracarboxylic acid diester compound with a diamine compound, or (3) a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound.

The imide compound in the polymer (A) or polymer (B) contained in the liquid crystal alignment agent of the present invention can be obtained, for example, by ring-closing the polymer obtained above. In the imide compound, the ring-closing rate (also called the imidization rate) of the functional group possessed by the amide group or its derivative is not necessarily 100%, and the imidization rate can be arbitrarily adjusted according to the use and/or purpose.

The method for obtaining the imidization product may be, for example, thermal imidization in which the polymer solution obtained by the above reaction is directly heated, or catalytic imidization in which a catalyst is added to the polymer solution. When thermal imidization is performed in the solution, the temperature is preferably 100° C. to 400° C., and more preferably 120° C. to 250° C. When thermal imidization is performed, it is preferred to discharge the water generated by the imidization reaction out of the system.

The aforementioned catalytic imidization can be carried out, for example, by adding an alkaline catalyst and an acid anhydride to the polymer solution obtained by the reaction, preferably at -20°C to 250°C, and more preferably at 0°C to 180°C with stirring. The amount of the alkaline catalyst added is preferably 0.5 to 30 moles of the amide group, and more preferably 2 to 20 moles; the amount of the acid anhydride added is preferably 1 to 50 moles of the amide group, and more preferably 3 to 30 moles. Specific examples of alkaline catalysts may include but are not limited to pyridine, triethylamine, trimethylamine, tributylamine or trioctylamine. Among them, pyridine is ideal because it has a moderate alkalinity that allows the reaction to proceed. Specific examples of acid anhydrides include but are not limited to acetic anhydride, trimellitic anhydride or pyromellitic anhydride. Among them, if acetic anhydride is used, purification after the reaction is easier, so it is more ideal. The imidization rate of the catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature and/or reaction time.

When the imide formed is recovered from the above-mentioned imidization reaction solution, the reaction solution is put into a solvent and precipitated. The solvent used for precipitation may include, but is not limited to, methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene or water. After filtering and recovering the polymer precipitated in the solvent, it can be dried at normal pressure or reduced pressure, at room temperature or by heating. Alternatively, the polymer recovered by precipitation is dissolved in a solvent again and reprecipitated and recovered. This operation is repeated 2 to 10 times to reduce impurities in the polymer. The solvent used may be, for example, an alcohol or a ketone. If more than three selected solvents are used, the refining efficiency can be further improved, which is more ideal.

Solution viscosity and molecular weight of polymers

When the solution is prepared into a concentration of 10 wt% to 15 wt%, the solution concentration of the polymer (A) or polymer (B) of the present invention is not particularly limited. Based on the viewpoint of easier operation, the solution concentration can be, for example, 10 mPa·s to 1000 mPa·s. The solution viscosity (mPa·s) of the polymer is a value measured at 25°C using a good solvent for the polymer (e.g., γ-butyrolactone or N-methyl-2-pyrrolidone, etc.) to prepare a polymer solution with a concentration of 10 wt% to 15 wt%.

The weight average molecular weight ( _Mw ) of the polymer (A) or polymer (B) of the present invention measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 500,000, and more preferably 2,000 to 500,000. In addition, the molecular weight distribution ( _Mw / _Mn ) represented by the ratio of _Mw to the number average molecular weight ( _Mn ) in terms of polystyrene measured by GPC is preferably 15 or less, and more preferably 10 or less. When the molecular weight of the polymer is within the above molecular weight range, it can ensure good alignment and stability of the liquid crystal display element.

Capping agent

When synthesizing the polymer (A) or polymer (B) of the present invention, the tetracarboxylic acid derivative component and the diamine component as described above can be used, and a suitable end-capping agent can be used to synthesize an end-sealed polymer. The end-sealed polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating, and improving the sealing properties of the sealant and the liquid crystal alignment film. The end of the polymer (A) or polymer (B) of the present invention may, for example, contain an amino group, a carboxyl group, an anhydride group or a derivative thereof. The amino group, the carboxyl group, the anhydride group or a derivative thereof can be obtained by a general condensation reaction, or by using the end-capping agent described later to seal the end. Similarly, the aforementioned derivatives can be obtained, for example, using the following end-capping agent.

For example, the end-capping agent may include, but is not limited to, acetic anhydride, maleic anhydride, neddic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-((3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione or 4-ethynylphthalic anhydride; dibutyl dicarbonate or diallyl dicarbonate; Carbonic acid diester compounds; chlorocarbonyl compounds such as acrylyl chloride, methacrylic chloride or nicotinyl chloride; monoamine compounds such as aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine or n-octylamine; monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate or naphthyl isocyanate, etc.

The blocking agents may be used alone or in combination of two or more.

Based on 100 mol parts of the total usage of the diamine component, the usage of the end-capping agent is preferably 0.01 mol parts to 20 mol parts, and more preferably 0.01 mol parts to 10 mol parts.

Other ingredients in liquid crystal alignment agents

The liquid crystal alignment agent of the present invention may include polymer (A) and polymer (B) added as needed. In addition to polymer (A) and polymer (B), the liquid crystal alignment agent of the present invention may selectively include other polymers. The types of other polymers may include, but are not limited to, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, or poly(meth)acrylate, etc.

Solvent (C)

From the perspective of forming a uniform film, the liquid crystal alignment agent is in the form of a coating liquid to produce a liquid crystal alignment film. The liquid crystal alignment agent of the present invention is preferably a coating liquid containing the above-mentioned polymer component and an organic solvent (hereinafter referred to as solvent (C)). Among them, based on the set coating thickness to be formed, the polymer concentration in the liquid crystal alignment agent can be appropriately changed. From the perspective of forming a uniform and defect-free coating, the polymer concentration in the liquid crystal alignment agent is preferably above 1 wt%. From the perspective of the storage stability of the solution, the polymer concentration in the liquid crystal alignment agent is preferably below 10 wt%. The ideal polymer concentration can be 2 wt% to 8 wt%. The content of the polymer (A) in the liquid crystal alignment agent can be appropriately changed by the coating method of the liquid crystal alignment agent and/or the film thickness of the desired liquid crystal alignment film, and is preferably 2 wt % to 10 wt %, and more preferably 3 wt % to 7 wt %.

There is no particular limitation on the organic solvent contained in the liquid crystal alignment agent, and it only needs to be able to uniformly dissolve the aforementioned polymer. Specific examples thereof include, but are not limited to, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone or N-cyclohexyl-2-pyrrolidone, etc., and the aforementioned organic solvents are also called good solvents. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide or γ-butyrolactone is preferred. Based on the total usage of the solvent in the liquid crystal alignment agent being 100 wt %, the usage of the good solvent may be 20 wt % to 99 wt %, preferably 20 wt % to 90 wt %, and more preferably 30 wt % to 80 wt %.

Secondly, the organic solvent in the liquid crystal alignment agent is preferably a mixed solvent of the aforementioned solvent and a solvent (also called a poor solvent) that can improve the coating property of the liquid crystal alignment agent and the surface smoothness of the coating film. The specific poor solvent used in combination can be, for example, but not limited to the solvent described below. Based on the total usage of the solvent in the liquid crystal alignment agent being 100 wt%, the usage of the poor solvent is preferably 1 wt% to 80 wt%, more preferably 10 wt% to 80 wt%, and particularly preferably 20 wt% to 70 wt%. The type and amount of the poor solvent can be appropriately selected according to the coating device, coating conditions and/or coating environment of the liquid crystal alignment agent.

For example, the poor solvent may be, for example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethyl carbonate, ethylene glycol monobutyl ether (butyl celoxylate), ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy) )-2-propanol, 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, or diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

Among them, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone is preferred.

The preferred solvent combination of good solvent and poor solvent can be, for example, but not limited to, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether; N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether; N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone; N-ethyl-2-pyrrolidone and propylene glycol diacetate; N,N-dimethyl lactamide and diisobutyl ketone; N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate; N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate; N-methyl-2-pyrrolidone and ethyl Glycol monobutyl ether acetate; N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether; N,N-dimethyl lactamide and ethylene glycol monobutyl ether; N,N-dimethyl lactamide and propylene glycol diacetate; N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether; N,N-dimethyl lactamide and diethylene glycol diethyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether; N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone; N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether; N-methyl-2-pyrrolidone, 4-Hydroxy-4-methyl-2-pentanone and diisobutyl ketone; N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether; N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether; N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate; γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone; γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone; N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol diacetate Glycol monobutyl ether and diisopropyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl carbinol; N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether; N-methyl-2-pyrrolidone, propylene glycol monobutyl ether and dipropylene glycol dimethyl ether; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and propylene glycol diacetate; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and diisobutyl ketone; N-ethyl-2-pyrrolidone, γ-butyrolactone and diisobutyl ketone; or N-ethyl-2-pyrrolidone, N,N-dimethyllactamide and diisobutyl ketone, etc.

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

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

Additives

The liquid crystal alignment agent of the present invention may also selectively add components other than polymer components and organic solvents (hereinafter referred to as additive components). These additive components may include, for example, but are not limited to: adhesion aids for improving the adhesion between the liquid crystal alignment film and the substrate or the adhesion between the liquid crystal alignment film and the sealant, compounds for improving the strength of the liquid crystal alignment film (hereinafter referred to as cross-linking compounds), compounds for promoting imidization, dielectrics or conductive substances for adjusting the dielectric constant or resistance of the liquid crystal alignment film, etc.

Sealing agent

The aforementioned adhesion aid may be, for example, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl diethoxymethyl silane, 2-aminopropyl trimethoxysilane, 2-aminopropyl triethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxysilane, 3-ureidopropyl trimethoxysilane, 3-ureidopropyl triethoxysilane, N-ethoxycarbonyl-3-aminopropyl trimethoxysilane, N-ethoxycarbonyl-3-aminopropyl triethoxysilane, N-triethoxysilylpropyl triethyl triamine, N-trimethoxysilylpropyl triethyl triamine, vinyl trimethoxysilane, Silane, vinyl triethoxysilane, 2-(3,4-epoxyhexyl)ethyl trimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane Silane coupling agents such as methoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, tris(3-trimethoxysilylpropyl) isocyanurate, or 3-isocyanatepropyl triethoxysilane. When a bonding agent is used, based on the viewpoint of exhibiting good resistance to AC afterimage, the amount of the bonding agent used is preferably 0.1 to 30 parts by weight, and more preferably 0.1 to 20 parts by weight, relative to 100 parts by weight of the total amount of the polymer used in the liquid crystal alignment agent.

Cross-linked compounds

The crosslinking compound mentioned above may be a compound having an ethylene oxide group, a propylene oxide group, at least one group selected from the group consisting of a group represented by the following formula (E1) and a group represented by the following formula (E2), or a compound selected from the compound represented by the following formula (E3), from the viewpoint of exhibiting good resistance to AC afterimage and effectively improving film strength. (E1) (E2) (E3)

In formula (E1), _G1 and _G2 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or -CH2 _- OH. In formula (E2), _G3 represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. _G4 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. In formula (E3), _G5 represents a (g1+g2)-valent organic group containing an aromatic ring. _G6 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. g1 represents an integer from 1 to 6, and g2 represents an integer from 0 to 4.

In formula (E3), the (g1+g2)-valent organic group having an aromatic ring represented by _G5 can be exemplified by a (g1+g2)-valent aromatic hydrocarbon group having 6 to 30 carbon atoms, a (g1+g2)-valent organic group formed by directly or via a linking group bonding an aromatic hydrocarbon group having 6 to 30 carbon atoms, or a (g1+g2)-valent group having an aromatic heterocyclic ring. The aromatic hydrocarbon can be, for example, benzene or naphthalene. The aromatic heterocyclic ring can be exemplified by the aromatic heterocyclic rings of the above-mentioned specific nitrogen atom-containing structure. The linking group can be exemplified by an alkylene group having 1 to 10 carbon atoms or a group obtained by removing a hydrogen atom from the alkylene group, or a divalent or trivalent cyclohexane. Wherein, any hydrogen atom of the alkylene group may be substituted by a fluorine atom or an organic group such as trifluoromethyl. In formula (E3), the alkyl group with 1 to 5 carbon atoms represented by _G6 may be methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl or n-pentyl.

Compounds with ethylene oxide

Specific examples of the compound having an ethylene oxide group include N,N,N',N'-tetraethylene oxide propyl-m-xylene diamine, 1,3-bis(N,N-diethylene oxide propylaminomethyl)cyclohexane, N,N,N',N'-tetraethylene oxide propyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraethylene oxide propyl-p-phenylenediamine, and compounds containing nitrogen atoms such as those represented by the following formulas (E4) to (E6). (E4) (E5) (E6)

Compounds with propylene oxide

Specific examples of the compound having an propylene oxide group include compounds represented by the following formula (E7) to formula (E16). (E7) (E8) (E9) (E10) (E11) (E12) (E13) (E14) (E15) (E16)

In formula (E15), R represents , where "*" represents the key position.

Compounds having a group represented by formula (E1)

Specific examples of the compound having the group represented by formula (E1) include compounds represented by the following formulas (E1-1) to (E1-12). (E1-1) (E1-2) (E1-3) (E1-4) (E1-5) (E1-6) (E1-7) (E1-8) (E1-9) (E1-10) (E1-11) (E1-12)

Compounds having a group represented by formula (E2)

Specific examples of the compound having the group represented by formula (E2) include compounds represented by the following formulas (E2-1) to (E2-4). (E2-1) (E2-2) (E2-3) (E2-4)

Compounds having a group represented by formula (E3)

Specific examples of the compound having a group represented by formula (E3) include compounds represented by the following formulas (E3-1) to (E3-10). (E3-1) (E3-2) (E3-3) (E3-4) (E3-5) (E3-6) (E3-7) (E3-8) (E3-9) (E3-10)

In the liquid crystal alignment agent of the present invention, based on the total usage of the polymer in the liquid crystal alignment agent being 100 parts by weight, the usage of the crosslinking compound is preferably 0.5 parts by weight to 20 parts by weight. Among them, based on the viewpoint of the crosslinking reaction and the good resistance to AC afterimage, the usage of the crosslinking compound is more preferably 1 part by weight to 15 parts by weight.

Compounds that promote imidization

The aforementioned compound for promoting imidization is preferably a compound having a basic site (e.g., a primary amine group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring or an indole ring), or a guanidine group, etc.) (excluding the aforementioned cross-linking compound and the bonding aid), or a compound that generates the aforementioned basic site upon calcination. More preferably, the compound for promoting imidization is a compound that generates the aforementioned basic site upon calcination, and a specific example thereof may be an amino acid in which a part or all of the basic site of the amino acid is protected. Specific examples of the above amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, or ornithine. For the purpose of promoting the imidization compound, a more preferred specific example is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butyloxycarbonyl)-L-histidine.

Liquid crystal alignment film and method for manufacturing liquid crystal display element

The liquid crystal alignment film of the present invention is obtained from the aforementioned liquid crystal alignment agent. The liquid crystal alignment film of the present invention can be used as a horizontal alignment type or a vertical alignment type (VA type) liquid crystal alignment film, and is a liquid crystal alignment film suitable for a horizontal alignment type liquid crystal display element such as an IPS method or a FFS method. The liquid crystal display element of the present invention has the aforementioned liquid crystal alignment film. The liquid crystal display element of the present invention can be manufactured, for example, by the following method of steps (1) to (4) or steps (1) to (2) and step (4).

Step (1): Apply liquid crystal alignment agent on the substrate

The liquid crystal alignment agent of the present invention is applied on one side of a substrate provided with a patterned transparent conductive film by using a suitable coating method such as roller coating, spin coating, printing or inkjet. There is no particular limitation on the substrate, and it only needs to be a highly transparent substrate. A glass substrate or a silicon nitride substrate can also be used together with a plastic substrate such as an acrylic substrate or a polycarbonate substrate. Secondly, in a reflective liquid crystal display element, if it is only a single-sided substrate, an opaque material such as a silicon wafer can also be used, and the electrode used can also be a light-reflecting material such as aluminum. Furthermore, when manufacturing IPS type or FFS type liquid crystal elements, the comb-tooth type uses an electrode substrate composed of a patterned transparent conductive film or metal film and an opposite substrate without an electrode.

The method of coating the liquid crystal alignment agent on the substrate and forming a film can be listed as screen printing, lithography, flexographic printing, inkjet method or inkjet coating method, etc. Among them, the film forming method is preferably coating by inkjet method.

Step (2): calcining the coated liquid crystal alignment agent

Step (2) is a step of calcining the liquid crystal alignment agent coated on the substrate to form a film. After the liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated by heating means such as a hot plate, a heat circulation oven or an IR (infrared) oven, or thermal imidization of polyamine or polyamine ester can be performed. The drying and calcining steps performed after the liquid crystal alignment agent of the present invention has been coated can be selected at any temperature and time, and multiple drying or calcining steps can be performed. The drying temperature can be, for example, 40°C to 180°C. From the perspective of shortening the process, it can be performed at 40°C to 150°C. There is no particular limitation on the drying time, and it may be, for example, 1 minute to 10 minutes or 1 minute to 5 minutes. When performing thermal imidization of polyamine acid or polyamine ester, after the aforementioned drying step, a calcination step may be further performed at a temperature of, for example, 150°C to 300°C or 150°C to 250°C. There is no particular limitation on the calcination time, and it may be, for example, 5 minutes to 40 minutes or 5 minutes to 30 minutes. If the film after calcination is too thin, the reliability of the liquid crystal display element will be reduced, so the film thickness is preferably 5 nm to 300 nm, and more preferably 10 nm to 200 nm.

Step (3): Performing an alignment treatment on the film obtained in step (2)

Step (3) is to perform an alignment treatment on the film obtained in step (2) as appropriate. In other words, in a horizontal alignment type liquid crystal display element such as the IPS mode or the FFS mode, the coating film is subjected to an alignment treatment to give it an alignment capability. On the other hand, in a vertical alignment type liquid crystal display element such as the VA mode or the PSA mode, the formed coating film can be directly used as a liquid crystal alignment film, but the coating film can also be subjected to an alignment treatment to give it an alignment capability. The alignment treatment of the liquid crystal alignment film can be exemplified by a friction treatment method or a photo-alignment treatment method, and the photo-alignment treatment method is preferred. The photo-alignment treatment method can be listed as a method of irradiating the surface of the above-mentioned film-like object with radiation that has been deflected in a certain direction, and preferably heating it at a temperature of 150°C to 250°C to give liquid crystal alignment (also known as liquid crystal alignment ability). The radiation can use ultraviolet light or visible light with a wavelength of 100 nm to 800 nm. Among them, the radiation is preferably ultraviolet light with a wavelength of 100 nm to 400 nm, and more preferably ultraviolet light with a wavelength of 200 nm to 400 nm.

The radiation dose may be 1 mJ/cm ² to 10,000 mJ/cm ² , preferably 100 mJ/cm ² to 5,000 mJ/cm ² , more preferably 100 mJ/cm ² to 1500 mJ/cm ² , and particularly preferably 100 mJ/cm ² to 1000 mJ/cm ² . When a general liquid crystal alignment agent is used, the light irradiation dose for the alignment treatment is 100 mJ/cm ² to 5000 mJ/cm ² , but the liquid crystal alignment agent of the present invention can still obtain a liquid crystal alignment film in which the variation (non-uniformity) of the liquid crystal alignment within the film surface is effectively suppressed even if the light irradiation dose for the alignment treatment is reduced. When irradiating radiation, in order to improve the liquid crystal alignment, the substrate of the aforementioned film-like object can be heated at 50°C to 250°C while irradiating. The liquid crystal alignment film produced in this way can make the liquid crystal molecules align stably in a certain direction. Secondly, the liquid crystal alignment film irradiated with polarized radiation in the aforementioned method can be contact-treated with a solvent, or the liquid crystal alignment film irradiated with radiation can be heated.

There is no particular limitation on the solvent used in the aforementioned contact treatment, and it only needs to be able to dissolve the decomposition products generated from the film after irradiation with radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl celoxylate, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, or cyclohexyl acetate. Among them, based on the viewpoint of versatility and safety, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferred, and water, 1-methoxy-2-propanol or ethyl lactate are more preferred. The solvent can be used alone or in combination.

The temperature for heat treatment of the coating film irradiated with radiation is preferably 50° C. to 300° C., and more preferably 120° C. to 250° C. The time for heat treatment is preferably 1 minute to 30 minutes.

Step (4): Making liquid crystal cells

Prepare two substrates with the liquid crystal alignment films formed above, and arrange the liquid crystal between the two substrates facing each other. For example, the following two methods can be listed. The first method is to arrange the two substrates facing each other with a gap (cell gap) between them in a way that the liquid crystal alignment films face each other. Then, the periphery of the two substrates is bonded with a sealant, and then the liquid crystal composition is injected into the cell gap separated by the substrate surface and the sealant, and after it contacts the film surface, the injection hole is sealed.

The second method is called ODF (One Drop Fill). A sealant such as a UV-curable sealant is applied to a predetermined position on one of the two substrates on which a liquid crystal alignment film has been formed, and then a liquid crystal composition is dripped onto a plurality of predetermined positions on the surface of the liquid crystal alignment film. Then, the other substrate is bonded with the liquid crystal alignment films facing each other, and the liquid crystal composition is pushed onto the entire surface of the substrate so that it contacts the film surface. Next, ultraviolet light is irradiated onto the entire surface of the substrate to cure the sealant. When performing any of the aforementioned methods, it is preferred to further heat the liquid crystal composition used to a temperature at which it becomes an isotropic phase, and then slowly cool it to room temperature to remove the flow alignment during liquid crystal filling. Secondly, when the coating is subjected to rubbing treatment, the two substrates are arranged so that the rubbing directions of the coatings are at a predetermined angle to each other, for example, perpendicular or anti-parallel. The sealant may be, for example, an epoxy resin containing a hardener and aluminum oxide balls as spacers. The liquid crystal composition may be nematic liquid crystal and lamellar liquid crystal, and preferably nematic liquid crystal.

If necessary, a polarizing plate can be attached to the outer surface of the liquid crystal cell to obtain a liquid crystal display element. The polarizing plate attached to the outer surface of the liquid crystal cell can be a polarizing film called "H film" that stretches polyvinyl alcohol and absorbs iodine at the same time. It can be a polarizing plate sandwiched by a cellulose acetate protective film, or a polarizing plate composed of the H film itself.

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

Preparation of diamine compound (a2-1)

Synthesis Example a2-1-1

27.39 g (0.18 mol) of 1-phenyl-1,3-propanediol was mixed with 14.2 g (0.18 mol) of pyridine, and the mixture was dissolved in 60 g of toluene, and 85.08 g (0.54 mol) of 4-nitrochlorobenzene was added to form a reaction solution. The reaction solution was reacted at 25° C. for 6 hours. The reaction solution was then mixed with 200 ml of pure water, purified and concentrated to obtain a solid product. Thereafter, the solid product was crystallized using methanol to form a powdery intermediate product of Synthesis Example a2-1-1.

Next, the aforementioned intermediate product is dissolved in 40 grams of toluene. Keeping the solution temperature at 5°C, 0.02 grams of 10% palladium carbon (Pd-C) is added to the solution as a catalyst, and 4.8 grams of hydrazine is slowly added dropwise, and then reacted at 165°C. After reacting for 8 hours, the reaction solution is mixed with 100 ml of water, purified and concentrated to obtain a solid product. Thereafter, the solid product is crystallized using methanol. The obtained powdery product is collected and recrystallized with toluene to obtain the white powder product of Synthesis Example a2-1-1 as shown in Formula (A21-2).

Synthesis Example a2-1-2 to Synthesis Example a2-1-6

Synthesis Examples a2-1-2 to a2-1-6 use the same preparation method as the preparation method of the diamine compound (a2-1) in Synthesis Example 2-1-1, except that Synthesis Examples a2-1-2 to a2-1-6 change the type of reactants as described below.

In synthesis example a2-1-2, 2-cyclohexyl-1,4-butanediol is used to replace 1-phenyl-1,3-propanediol, and p-fluoronitrobenzene is used to replace 4-nitrochlorobenzene, and the obtained product has a structure shown in formula (A21-3).

In synthesis example a2-1-3, 2-n-pentyl-1,4-butanediol is used to replace 1-phenyl-1,3-propanediol, and the obtained product has a structure as shown in formula (A21-5).

In synthesis example a2-1-4, 6-methyl-1,4-heptanediol is used to replace 1-phenyl-1,3-propanediol, and p-fluoronitrobenzene is used to replace 4-nitrochlorobenzene, and the obtained product has a structure shown in formula (A21-7).

In synthesis example a2-1-5, 1,2-propylene glycol is used to replace 1-phenyl-1,3-propylene glycol, and p-fluoronitrobenzene is used to replace 4-nitrochlorobenzene, and the obtained product has a structure shown in formula (A21-8).

In synthesis example a2-1-6, 2-ethyl-1,3-propanediol is used to replace 1-phenyl-1,3-propanediol, and the obtained product has a structure as shown in formula (A21-9).

Preparation 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, 1.355 g (0.00525 mol) of the diamine compound (a2-1-5) obtained in Synthesis Example a2-1-5, 1.764 g (0.00525 mol) of the diamine compound (a2-2-1) represented by formula (A22-7), 3.042 g (0.0045 mol) of the diamine compound (a2-3-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added, and stirred at room temperature until dissolved. Then, 3.36 g (0.015 mol) of the compound (a1-1-1) and 20 g of NMP were added, and the mixture was reacted at room temperature for 2 hours. After the reaction is completed, the reaction solution is poured into 1500 ml of water to precipitate the polymer, and the obtained polymer is filtered and washed and filtered with methanol three times. After that, the product is placed in a vacuum oven and dried at a temperature of 60°C to obtain the polymer (A-1-1) of Synthesis Example A-1-1, whose formula is shown in Table 1.

Synthesis Examples A-1-2 to A-1-20 and Comparative Synthesis Examples A-1-21 to A-1-26

Synthesis Examples A-1-2 to A-1-20 and Comparative Synthesis Examples A-1-21 to A-1-26 use the same preparation method as the preparation method of the polymer (A-1-1) in Synthesis Example A-1-1. The difference is that Synthesis Examples A-1-2 to A-1-20 and Comparative Synthesis Examples A-1-21 to A-1-26 change the types and usage amounts of raw materials in the polymers. The formulas are shown in Table 1 and are not described in detail here.

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, 1.355 g (0.00525 mol) of the diamine compound (a2-1-5) obtained in Synthesis Example a2-1-5, 1.764 g (0.00525 mol) of the diamine compound (a2-2-1) represented by formula (A22-7), 3.042 g (0.0045 mol) of the diamine compound (a2-3-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added, and stirred at room temperature until dissolved. Then, 3.36 g (0.015 mol) of the compound (a1-1-1) and 20 g of NMP were added. After reacting at room temperature for 6 hours, 97 g of NMP, 2.55 g of acetic anhydride and 19.75 g of pyridine were added, the temperature was raised to 60°C, and stirring was continued for 2 hours to carry out the imidization reaction. After the reaction was completed, the reaction solution was poured into 1500 ml of water to precipitate the polymer. Then, the obtained polymer was filtered, and washed and filtered with methanol three times repeatedly, placed in a vacuum oven, and dried at a temperature of 60°C to obtain polymer (A-2-1), the formula of which is shown in Table 1.

Synthesis Example A-2-2 to Synthesis Example A-2-4

Synthesis Examples A-2-2 to A-2-4 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-2-4 change the type and amount of raw materials in the polymer. The formula is shown in Table 1 and is not further described here.

   

Preparation of polymer (B)

Synthesis Example B-1-1 to Synthesis Example B-1-3

Synthesis Examples B-1-1 to B-1-3 use the same preparation method as the preparation method of the polymer (A-1-1) of Synthesis Example A-1-1, except that the types and amounts of raw materials used in the polymers are changed in Synthesis Examples B-1-1 to B-1-3. The formulas are shown in Table 2 and are not described here.

Synthesis Example B-2-1 to Synthesis Example B-2-3

Synthesis Examples B-2-1 to B-2-3 use the same preparation method as the preparation method of the polymer (A-2-1) of Synthesis Example A-2-1, except that the types and amounts of raw materials used in the polymers are changed in Synthesis Examples B-2-1 to B-2-3. The formulas are shown in Table 2 and are not described here.

 

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

Embodiment 1

Weigh 50 parts by weight of the polymer (A-1-1) prepared in Synthesis Example A-1-1, 50 parts by weight of the polymer (B-1-1) prepared in Synthesis Example B-1-1, and 1600 parts by weight of NMP (C-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 above is applied on a glass substrate by rotation, and a pixel electrode is formed on the glass substrate, wherein the pixel electrode is an IPS driving electrode having a pair of ITO electrodes (electrode width is 10 μm, electrode spacing is 10 μm, and electrode height is 50 nm). The pair of ITO electrodes are respectively in a comb-shaped shape, and the comb-shaped 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 for 3 minutes, and then baked in a hot air circulation oven at 250°C for 30 minutes to form a coating with a film thickness of 100 nm.

After irradiating the coated surface with ultraviolet light of 254 nm through a polarizing plate, the substrate was baked in a hot air circulation oven at 250°C for 30 minutes to obtain a substrate with a liquid crystal alignment film. Similarly, a coating was formed on an opposing substrate and an alignment treatment was applied. The opposing substrate was a glass substrate without an electrode but with a columnar spacer of 4 μm in height.

The above two substrates are a set, and a sealant is printed on one of them, and the other is bonded in a manner that it faces the liquid crystal alignment film and the alignment direction is 0°, and then the sealant is hardened to produce an empty cell. This empty cell is injected with liquid crystal MLC-2041 (Merck) by a reduced pressure injection method, and the injection port is sealed to produce the liquid crystal display element of Example 1. The obtained liquid crystal display element is evaluated by the following evaluation method, and the results are shown in Table 3, among which the detection method of the contrast variation within the pixel will be described later.

Examples 2 to 28 and Comparative Examples 1 to 6

Examples 2 to 28 and Comparative Examples 1 to 6 use the same preparation method of the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element as Example 1. The difference is that Examples 2 to 28 and Comparative Examples 1 to 6 change the type and usage of raw materials in the liquid crystal alignment agent. Their formulas and evaluation results are shown in Table 3, which will not be described in detail here.

Evaluation method

Intra-pixel contrast variation

The torsion angle variation of the liquid crystal display element was measured using an AxoStep device manufactured by AXOMETRICS. The liquid crystal display element manufactured by the aforementioned embodiment and comparative example was placed on a measuring table, and the distribution of the circular retardance in the pixel was measured without applying voltage, and the 3 times value (3σ) of the standard deviation (σ) was calculated. Among them, the smaller the 3 times value (3σ) of the standard deviation, the lower the contrast variation in the pixel, and the contrast variation in the pixel was evaluated according to the following criteria. ※: 3σ≦2. ◎: 2＜3σ≦3. ○: 3＜3σ≦4. △: 4＜3σ≦5. ╳: 3σ＞5.

From the results of Table 3, it can be seen that if the diamine component (a2) of the liquid crystal alignment agent of the present invention does not contain the diamine compound (a2-1) as shown in formula (A21), the liquid crystal display element containing the liquid crystal alignment film prepared using this liquid crystal alignment agent will have a higher intra-pixel contrast variability. Among them, when Y ₁₁ in formula (A21) represents an aliphatic chain hydrocarbon group with a carbon number of 1 to 5, the resulting liquid crystal display element will have a lower intra-pixel contrast variability. When Y ₁₁ in formula (A21) represents a saturated linear hydrocarbon group with a carbon number of 1 to 3, the resulting liquid crystal display element will have an even lower intra-pixel contrast variability. Furthermore, when the diamine component (a2) comprises a diamine compound (a2-2) as shown in formula (A22), the liquid crystal alignment agent prepared will make the formed liquid crystal display element have a lower contrast variation within the pixel. When the tetracarboxylic acid derivative component (a1) comprises an alicyclic tetracarboxylic dianhydride compound (a1-1) as shown in formula (A11), and _X1 in formula (A11) represents the structure shown in formula (A11-1-1), the liquid crystal display unit containing the liquid crystal alignment film formed therefrom has a lower contrast variation within the pixel.

It should be added that, although the present invention uses specific compounds, compositions, reaction conditions, processes, analysis 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, anyone with common knowledge in the technical field to which the present invention belongs can know that the present invention is not limited to these. 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 can also use other compounds, compositions, reaction conditions, processes, analysis methods or instruments.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field to which the present invention belongs can make various 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 in the attached patent application.

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Claims (8)

A liquid crystal alignment agent comprises: a polymer (A), at least one selected from the group consisting of a polyimide precursor obtained by reacting a tetracarboxylic acid derivative component (a1) and a diamine component (a2), and an imide compound of the polyimide precursor, wherein the diamine component (a2) comprises a diamine compound (a2-1) represented by the following formula (A21):

In formula (A21), Y ₁₁ represents an aliphatic chain hydrocarbon group having 1 to 5 carbon atoms; and n and m each independently represent 0 to 3. The liquid crystal alignment agent as described in claim 1, wherein Y ₁₁ represents a saturated linear hydrocarbon group having 1 to 3 carbon atoms. The liquid crystal alignment agent as described in claim 1, wherein the diamine component (a2) comprises a diamine compound (a2-2) represented by the following formula (A22): H ₂ NR ₁ -R ₄ -R ₂ -R ₆ -R ₅ -R ₇ -R ₃ -NH ₂ (A22) In formula (A22), R ₁ , R ₂ and R ₃ each independently represent a divalent organic group of a benzene ring or a pyridine ring; R ₄ represents an oxygen atom or a sulfur atom; R ₅ represents a divalent chain hydrocarbon group having 1 to 30 carbon atoms or an alicyclic hydrocarbon group having 3 to 30 carbon atoms; R ₆ and R ₇ each independently represent a single bond, an oxygen atom, a sulfur atom or -NR ₈ -, wherein at least one of R ₆ and R ₇ represents an oxygen atom, a sulfur atom or -NR ₈ -, and R _R8 represents a hydrogen atom or a methyl group; when any one of _R1 , _R2 and _R3 is a pyridine ring, _R6 and _R7 do not represent a single bond. The liquid crystal alignment agent as described in claim 1, wherein the tetracarboxylic acid derivative component (a1) comprises an alicyclic tetracarboxylic dianhydride compound or a derivative thereof as shown in the following formula:

The liquid crystal alignment agent as described in claim 1 further comprises: a polymer (B), at least one selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (B) does not contain a structure derived from the diamine compound (a2-1) represented by formula (A21). A liquid crystal alignment agent as described in any one of claim 1 to claim 5, wherein the liquid crystal alignment agent is configured to prepare a liquid crystal alignment film used in a photoalignment treatment method. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 6. A liquid crystal display element, comprising a liquid crystal alignment film as described in claim 7.