KR102096369B1 - Liquid crystal aligning agent, liquid crystal alignment film, liquid crystal display device, polymer and compound - Google Patents

Abstract

(식 (1) 중, 2개 있는 X는, 각각 독립적으로, 산소 원자, 황 원자, 에스테르 결합, 티오에스테르 결합, 아미드 결합, -NH-, -C(＝O)-, 탄소수 1∼10의 2가의 포화 지방족기 또는 탄소수 2∼10의 2가의 불포화 지방족기이고; 2개 있는 Y는, 각각 독립적으로, 단결합, 산소 원자, 황 원자, 에스테르 결합 또는 티오에스테르 결합이고; R은 메틸렌기이거나, 혹은 도중이 산소 원자에 의해 중단되어 있어도 좋은 탄소수 2∼12의 알킬렌기이고; 그리고 「*」는 결합손을 나타냄).(Solution means) A liquid crystal aligning agent comprising at least one polymer selected from the group consisting of polyamic acid having a structure represented by the following formula (1) in the main chain and an imidized polymer thereof:

(In Formula (1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, and 1 to 10 carbon atoms. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms; two Ys are each independently a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond; R is a methylene group or , Or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom; and "*" represents a bonding hand).

Description

Liquid crystal aligning agent, liquid crystal aligning film, liquid crystal display element, polymer and compound {LIQUID CRYSTAL ALIGNING AGENT, LIQUID CRYSTAL ALIGNMENT FILM, LIQUID CRYSTAL DISPLAY DEVICE, POLYMER AND COMPOUND}

The present invention relates to a liquid crystal aligning agent.

In a liquid crystal display element widely used in televisions, mobile devices, and various monitors, a liquid crystal alignment film is used to align liquid crystal molecules in a liquid crystal cell. As a method of imparting the liquid crystal alignment ability to the liquid crystal alignment film, a method of rubbing an organic film, a method of depositing silicon oxide in all directions, and a method of forming a monomolecular film having a long chain alkyl group have been conventionally known.

Since the photo-alignment method can realize uniform liquid crystal alignment without generating static electricity and dust, and also enables precise control of the liquid crystal alignment direction, studies have been actively conducted in recent years (Patent Documents 1 to 3).

However, the liquid crystal aligning film formed by the photo-alignment method using a conventionally known liquid crystal aligning film material has a relationship between yielding high contrast and realizing good afterimage characteristics, and the properties of both of these cannot be sufficiently high. . For this reason, it has not been possible to simultaneously satisfy the demands for the display of high-definition images and the reproduction display of high-definition moving images.

Japanese Patent Publication No. Hei 6-287453 Japanese Patent Publication No. 2003-307736 Japanese Patent Publication No. Hei 9-297313 Japanese Patent Publication No. 2010-97188

The present invention was made to overcome the above-described phenomenon.

Accordingly, the object of the present invention is to provide a liquid crystal aligning film having excellent liquid crystal alignment properties, such as excellent electrical properties, excellent contrast characteristics, and particularly excellent contrast and good afterimage characteristics, while exhibiting good liquid crystal alignment properties by the photo-alignment method. Is to provide a second.

According to the present invention, the above objects and advantages of the present invention are characterized by containing at least one polymer selected from the group consisting of polyamic acid having a structure represented by the following formula (1) in the main chain and an imidized polymer thereof. It is achieved by a liquid crystal aligning agent:

(In Formula (1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, and 1 to 10 carbon atoms. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;

Two Y are each independently a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond;

R is a methylene group or an alkylene group having 2 to 12 carbon atoms which may be interrupted by an oxygen atom in the middle;

And "*" represents a bonding hand).

The liquid crystal aligning agent of this invention can form a liquid crystal aligning film which has favorable liquid crystal aligning property by a photo-alignment method. Since the liquid crystal aligning film formed from the liquid crystal aligning agent of this invention is excellent in the electrical characteristics represented by voltage retention, and high contrast and favorable afterimage characteristics (burn-in characteristic) are compatible, the liquid crystal display element provided with the said liquid crystal aligning film is It can be applied to various uses.

When the use of the liquid crystal display element provided with the liquid crystal aligning film formed from the liquid crystal aligning film of this invention is illustrated, it is as follows, for example;

Televisions, portable games, word processors, notebook PCs, car navigation systems, camcorders, portable information terminals, digital cameras, mobile phones, and various monitors.

1 is an explanatory diagram showing a pattern of an electrode used in a liquid crystal display element for evaluating afterimage characteristics.

(Form for carrying out the invention)

As described above, the liquid crystal aligning agent of the present invention has at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the formula (1) in the main chain and an imidized polymer thereof (hereinafter referred to as "specific polymer"). ).

Here, the main chain of a polymer means the part of a "stem" consisting of a chain of the longest atoms in the polymer. It is permissible for this main chain to contain a ring structure. In this case, the entire ring structure is present in the main chain. Having a structure represented by the formula (1) in the main chain means that this structure constitutes a part of the main chain. The requirement of the specific polymer in the present invention is that the structure represented by the formula (1) is present in the main chain, but the structure is other than the main chain, for example, a side chain (part branched from the "stem" of the polymer). However, overlapping existence is not prohibited.

When X or Y in the formula (1) is an ester bond or a thioester bond, and X is an amide bond, the bonding direction may be either.

Examples of the divalent saturated aliphatic group having 1 to 10 carbon atoms in X include a methylene group, a 2,2-propylene group, and an alkylene group having 2 to 10 carbon atoms. It is preferable that carbon number of this alkylene group is 2-4, and it is more preferable that it is 2. As the divalent unsaturated aliphatic group having 2 to 10 carbon atoms in X, an alka (poly) alkylene group having 2 to 10 carbon atoms is preferable. It is preferable that carbon number of this alka (poly) alkylene group is 2-4. Examples of the specific examples include -CH = CH-, -CH = CH-CH _2- , -CH ₂ -CH = CH-CH _2- , -CH = CH-CH = CH-, and the like.

When X is a saturated aliphatic group or an unsaturated aliphatic group, and the group is left and right asymmetric, the bonding direction may be either.

As X, it is preferable that each of the two X is independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, -NH-, -CH ₂ -CH ₂ -or -CH = CH-, and an ester bond, It is more preferable that the thioester bond, -NH-, -CH ₂ -CH ₂ -or -CH = CH-. It is preferable that it is an oxygen atom as Y.

R in said Formula (1) is a site | part which gives flexibility to the main chain of a specific polymer. Therefore, as this R, the following formula:

-(CH ₂ ) _n -or

-(CR'H-CH ₂ )-(O-CR'H-CH ₂ ) _m-

(However, R 'is independently a hydrogen atom, a methyl group or an ethyl group;

n is an integer from 1 to 12;

m is an integer represented by 1 to 3) is preferred. However, as understood from the definition of R in formula (1), the upper limit of the number of carbon atoms in the formula is limited to 12.

As R 'in the above formula, it is preferable that it is a hydrogen atom;

As n, it is preferable that it is 2-8, and it is more preferable that it is 4-6;

As m, it is preferable that it is 1 or 2.

In the formula (1), the four phenylene groups are each independently preferably a 1,3-phenylene group or a 1,4-phenylene group, and more preferably a 1,4-phenylene group.

Examples of the structure represented by the formula (1) include structures represented by the following formulas (1-1) to (1-12):

(In the formulas (1-1) to (1-12), n is an integer from 2 to 12, and m is 1 or 2.)

As n in the said Formula (1-1), (1-3), (1-5), (1-7), (1-9) and (1-11), it is preferable that it is 2-8. , 4 to 6 is more preferable.

As long as the specific polymer in the present invention is at least one polymer selected from the group consisting of polyamic acid having the structure represented by the formula (1) in the main chain and an imidized polymer thereof, the rest of the structure is arbitrary, It may be obtained by any synthetic method.

The specific polymer in the present invention is, for example, a polyamic acid obtained by reacting a dicarboxylic acid with a tetracarboxylic acid anhydride containing a tetracarboxylic acid anhydride having a structure represented by the formula (1), and a diamine, and an imidized polymer thereof. It may be one or more polymers selected from the group consisting of, or a group consisting of a polyamic acid obtained by reacting a tetracarboxylic acid anhydride and a diamine containing a diamine having a structure represented by the formula (1) above and an imidized polymer thereof. It may be one or more polymers selected from. Of these, the latter is preferred from the viewpoint of ease of synthesis of raw material monomers.

[Tetracarboxylic acid 2 anhydride]

Examples of the tetracarboxylic acid anhydride used for synthesizing the specific polymer in the present invention include aliphatic tetracarboxylic acid anhydride, alicyclic tetracarboxylic acid anhydride, aromatic tetracarboxylic acid anhydride, and the like. As these specific examples, as aliphatic tetracarboxylic acid dianhydride, butane tetracarboxylic acid dianhydride etc. are mentioned, for example;

As an alicyclic tetracarboxylic acid anhydride, for example, 1,2,3,4-cyclobutanetetracarboxylic acid anhydride, 2,3,5-tricarboxylic cyclopentyl acetic anhydride, 1,3,3a, 4, 5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 , 5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3- Oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 5- (2,5-dioxotetrahydro-3 -Furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3,5,6-tricarbox-2-carboxymethylnorbornane-2: 3,5: 6-2 anhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-2 anhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane 3, 5,8,10-tetraone and the like;

Examples of the aromatic tetracarboxylic acid anhydride include, for example, pyromellitic acid anhydride, a compound represented by the following formula (T1), and the like, as well as those described in Patent Document 4 (Japanese Laid-Open Patent Publication No. 2010-97188). Tetracarboxylic acid anhydride can be used:

(In formula (T1), when Z is plural, each independently represents an oxygen atom, a sulfur atom, an ester bond, a thioester bond, or -NH-;

R <^1> is a C6-C18 arylene group or a C2-C6 alkylene group each independently when it is plural; And

n1 is an integer from 0 to 2).

It is preferable that Z in the formula (T1) is an oxygen atom or an ester bond. Examples of the arylene group for R ¹ include a phenylene group, a naphthylene group, and a biphenylene group;

As an alkylene group, 1,2-ethylene group, 1,2-propylene group, 1,3-propylene group etc. are mentioned, for example. R ¹ is preferably an arylene group, and when there are plural, it is particularly preferably each independently a 1,4-phenylene group, a 2,6-naphthylene group or a 4,4′-biphenylene group. It is preferable that it is 0 or 1 as n1.

As a specific example of the compound represented by said formula (T1), the compound etc. which are represented by each of following formula (T-1) and (T-2) are mentioned, for example.

The tetracarboxylic acid dianhydride used for synthesizing the specific polymer in the present invention preferably contains the compound represented by the formula (T1), and the compound represented by the formula (T1) is the total tetracarboxylic acid 2 It is preferable to contain 20 mol% or more with respect to anhydride, it is more preferable to contain 50 mol% or more, and it is still more preferable to contain 80 mol% or more.

[Diamine]

The diamine used for synthesizing the specific polymer in the present invention preferably includes a diamine having a structure represented by the formula (1). Examples of the diamine having a structure represented by the formula (1) include, for example, a compound represented by the following formula (A1) (hereinafter referred to as "specific diamine"):

(In formula (A1), X, Y and R are respectively the same meanings as in formula (1)).

About the bonding direction of the four phenylene groups present in the formula (A1), the phenylene groups in the formula (1) are the same as described above, respectively.

Preferable examples of the specific diamine in the present invention are, for example, in the structures represented by the formulas (1-1) to (1-12) above, each of the two amino groups in the two bonding hands represented by "*" And compounds obtained by direct bonding.

As the diamine used for synthesizing the specific polymer in the present invention, only a specific diamine may be used, or other diamines may be used in combination with the specific diamine.

As other diamine which can be used here, it can be considered as diamine which has a pretilt angle expressing group and diamine which does not have a pretilt angle expressing group, for example.

The diamine having a pretilt angle expressing group is preferably an aromatic diamine having a pretilt angle expressing group, and specific examples thereof include dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2, 4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecanoxy-2,5- Diaminobenzene, tetradecaneoxy-2,5-diaminobenzene, pentadecaneoxy-2,5-diaminobenzene, hexadecaneoxy-2,5-diaminobenzene, octadecaneoxy-2,5-diamino Benzene, Cholestanyloxy-3,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholestanyloxy-2,4-diaminobenzene, Cholesteryloxy-2,4- Diaminobenzene, 3,5-diaminobenzoic acid cholesterol, 3,5-diaminobenzoic acid cholesteryl, 3,5-diaminobenzoic acid ranstanil, 3,6-bis (4-aminobenzoyloxy) chol Stan, 3,6-bis (4-amino Phenoxy) cholestane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4- Heptylcyclohexane, 1,1-bis (4-((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4- ( 4-heptylcyclohexyl) cyclohexane, N- (2,4-diaminophenyl) -4- (4-heptylcyclohexyl) benzamide, compounds represented by the following formula (A-1), and the like:

(In formula (A-1), X ^I and X ^II are each a single bond, * -O-, * -COO-, or * -OOC- (however, a bond with "*" attached to formula (AI) To the left);

R ^I is a single bond, a methylene group, or an alkylene group having 2 or 3 carbon atoms;

a is 0 or 1, b is an integer from 0 to 2, provided that a and b are not simultaneously 0;

c is an integer from 1 to 20).

As the divalent group represented by X ^I -R ^I -X ^II -in the formula (A-1), a methylene group, an alkylene group having 2 or 3 carbon atoms, * -O-, * -COO- or * -O- It is preferable that it is CH ₂ CH ₂ -O- (however, the bonding hand with “*” is bonded to a diaminophenyl group). In the group -C _c H _{2c +1} , when c is 3 or more, it is preferable that this group is linear. It is preferable that two amino groups in a diaminophenyl group are in the 2,4-position or 3,5-position with respect to another group. Specific examples of the compound represented by the formula (A-1) include, for example, the following formulas (A-1-1-1), (A-1-1-2) and (A-1-2):

It is preferable that it is a compound represented by each of (in the said formula, "n-" shows that it is linear, respectively.).

Examples of the diamine having no pretilt angle expressing group include aliphatic diamine having no pretilt angle expressing group, alicyclic diamine, aromatic diamine, diamino organosiloxane, and the like.

Among the diamines having no pretilt-angle expressing group, examples of the aliphatic diamines include 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, and hexamethylenediamine;

Examples of the alicyclic diamine include 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), and 1,3-bis (aminomethyl) cyclohexane;

As the aromatic diamine having no pretilt-angle expressing group, for example, as an aromatic diamine, for example, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane , 4,4'-diaminodiphenylsulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2 ' -Bis (trifluoromethyl) biphenyl, 2,7-diaminofluorene, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoro Propane, 4,4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-di Minoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarb Bazol, N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, 1,4-bis- (4-aminophenyl) -Piperazine, 3,5-diaminobenzoic acid, 4- (4'-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4'-trifluoromethylbenzoyloxy) Cyclohexyl-3,5-diaminobenzoate, 2,4-diamino-N, N-diallyaniline, 4-aminobenzylamine, 3-aminobenzylamine, 1- (2,4-diaminophenyl) Piperazine-4-carboxylic acid, 4- (morpholin-4-yl) benzene-1,3-diamine, 1,3-bis (N- (4-aminophenyl) piperidinyl) propane, α-amino- ω-aminophenylalkylene, 4- (2-aminoethyl) aniline, compounds represented by the following formula (N), and the like;

As a diamino organosiloxane that does not have a pretilt-angle expressing group, for example, 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, etc. can be mentioned, respectively, and Patent Document 4 (Japanese Patent Laid-Open) Tetracarboxylic acid dianhydride described in Patent Publication 2010-97188) can be used.

The diamine used for synthesizing the specific polymer in the present invention preferably contains 5 mol% or more, and more preferably 10 mol% or more, of the specific diamine as described above with respect to the total diamine. It is more preferable to contain -80 mol%.

The liquid crystal aligning agent of this invention is especially suitable for forming a liquid crystal aligning film applied to a so-called horizontally-aligned liquid crystal display element, such as TN type, STN type, IPS type, FFS type, etc. by a photo-alignment method. Therefore, it is preferable to limit the use ratio of the diamine having a pretilt angle expressing group among the diamines to be used to a certain value or less. The use ratio of the diamine having a pretilt angle expressing group is preferably 20 mol% or less, more preferably 10 mol% or less, particularly 5 mol% or less, relative to the total diamine used. It is preferred to.

<Synthesis of specific polymers>

Polyamic acid as a specific polymer in the present invention can be obtained by reacting the above tetracarboxylic acid anhydride and diamine together with a terminal sealant used as necessary.

The imidized polymer as a specific polymer in the present invention can be obtained by imidizing the polyamic acid obtained as described above by dehydration and ring closure.

Examples of the terminal blocker include carbonic acid anhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride;

Monoamines such as aniline, cyclohexylamine, and n-butylamine;

And monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate.

The ratio of the tetracarboxylic acid anhydride and the diamine used in the synthesis reaction of the polyamic acid is 0.2 to 2 equivalents to the equivalent of the acid anhydride group of the tetracarboxylic acid anhydride and 1 equivalent of the diamine amino group. It is preferable, More preferably, it is the ratio which becomes 0.3 to 1.2 equivalent. When a terminal sealing agent is used, it is preferable that the use ratio is 20 weight or less based on 100 parts by weight of the total of tetracarboxylic acid anhydride and diamine.

The synthesis reaction of the polyamic acid is preferably in an organic solvent, preferably at a temperature of -20 to 150 ° C, more preferably 0 to 100 ° C, preferably 0.1 to 24 hours, more preferably 0.5 It is done for 12 hours.

Examples of the organic solvent that can be used in the synthesis of polyamic acid include non-protic polar solvents, phenols and derivatives thereof, alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons. . Of these organic solvents, at least one selected from the group consisting of aprotic polar solvents and phenols and derivatives thereof (first group of organic solvents) is used, or at least one selected from the first group of organic solvents. It is preferable to use a mixture of at least one selected from the group consisting of and alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons (second group of organic solvents). In the latter case, the use ratio of the organic solvent of the second group is preferably 50% by weight or less, more preferably 40% by weight or less, based on the total amount of the organic solvent of the first group and the organic solvent of the second group. It is more preferably 30% by weight or less.

Especially preferably, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoria Using at least one member selected from the group consisting of mid, m-cresol, xylenol, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and halogenated phenol. It is preferred.

The amount of organic solvent used (a) is the ratio (b / (a + b)) of the total amount (b) of tetracarboxylic acid anhydride and diamine (and terminal blocker, if present) to the total amount (a + b) of the polymerization reaction solution. ) Is preferably 0.1 to 50% by weight.

Thus, a solution containing polyamic acid is obtained. This solution can be provided to the next imidization reaction or preparation of the liquid crystal aligning agent of the present invention as it is or after isolating and purifying the polyamic acid by a known method as necessary.

When using an imidized polymer of polyamic acid as a specific polymer in the present invention, the imidation rate of the imidized polymer is preferably 30% or more from the viewpoint of ensuring the expression of good electrical properties, and 50 It is more preferable to be% or more, and even more preferably to be 65% or more. On the other hand, from the viewpoint of securing the solubility of a specific polymer that is an imidized polymer and improving the coating property of the obtained liquid crystal aligning agent, the imidation ratio is preferably 99% or less, and more preferably 80% or less.

To imidize the polyamic acid obtained as described above by dehydration and ring closure, preferably by (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, and dehydrating and dehydrating ring closure in this solution. It is carried out by a method of adding a catalyst and heating as necessary.

The reaction temperature in the method for heating the polyamic acid of (i) is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C, the dehydration cyclization reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C, the molecular weight of the imidized polymer obtained may be lowered. The reaction time is preferably 1.0 to 24 hours, and more preferably 1.0 to 12 hours.

On the other hand, in the method of adding a dehydrating agent and a dehydrating ring-closure catalyst in the solution of the polyamic acid of the above (ii), as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of the dehydrating agent used depends on the desired imidation rate, but is preferably 0.01 to 20 mol per 1 mol of the rock acid structure of the polyamic acid. Moreover, tertiary amines, such as pyridine, collidine, rutidine, and triethylamine, can be used as a dehydration cyclization catalyst. The amount of the dehydration ring-closed catalyst is preferably 0.01 to 10 mol per 1 mol of the dehydrating agent used. The imidation rate can be increased as the amount of the dehydrating agent and the dehydrating ring-closing catalyst used increases. Examples of the organic solvent used in the dehydration ring-closure reaction include organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closing reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, and more preferably 2.0 to 30 hours. In this way, a solution containing an imidized polymer of polyamic acid is obtained. This solution can be provided to the preparation of the liquid crystal aligning agent of this invention after isolation | refining and purification of an imidized polymer as it is, or by a well-known method as needed.

<Other ingredients>

The liquid crystal aligning agent of the present invention contains the above-mentioned specific polymer as an essential component, preferably composed of a solution composition dissolved in a solvent to be described later, but may further contain other components as necessary. .

Examples of such other components include other polymers, compounds having at least one epoxy group in the molecule (hereinafter referred to as "epoxy compounds"), functional silane compounds, and the like.

[Other polymers]

The above-mentioned other polymers are polymers other than a specific polymer, and can be used to improve the solution properties (coating properties) and electrical properties of the liquid crystal aligning agent of the present invention.

As other polymers, polyamic acid which does not have a structure represented by the formula (1) in the main chain, imidized polymer of the polyamic acid, polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, And poly (styrenephenylmaleimide) derivatives and poly (meth) acrylates.

The proportion of other polymers used is preferably 50% by weight or less, more preferably 30% by weight or less, based on 100 parts by weight of the specific polymer.

[Epoxy compound]

Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, Neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl Ether, N, N, N ', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidyl-aminomethylcyclohexane, N, N-di Glycidyl-cyclohexylamine etc. are mentioned as a preferable thing.

The blending ratio of these epoxy compounds is preferably 40 parts by weight or less, and more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the specific polymer.

[Functional silane compound]

Examples of the functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2 -Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxy Silane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimeth Methoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecan, 10-triethoxysilyl-1,4,7-triazadecan, 9-trimethoxysilyl-3 , 6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, 9-trimethoxysilyl-3,6-methyl diazanonanoate, 9-triethoxy Methyl reel-3,6-diazanonanoate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, And N-phenyl-3-aminopropyltriethoxysilane.

The blending ratio of these functional silane compounds is preferably 2 parts by weight or less, and more preferably 0.02 to 0.2 parts by weight with respect to 100 parts by weight of a specific polymer.

<Liquid crystal aligning agent>

The liquid crystal aligning agent of this invention is comprised by the above-mentioned specific polymer and other components mix | blended arbitrarily as needed, Preferably it melt | dissolves and contains.

As a solvent which can be used for the liquid crystal aligning agent of the present invention, it is preferable to use an organic solvent, for example, N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N -Dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methylmethoxypropionate, ethylethoxypro Cypionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol Ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethyl And ethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, and propylene carbonate. These may be used alone or in combination of two or more.

The solid content concentration (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) in the liquid crystal aligning agent of the present invention is suitably selected in consideration of viscosity, volatility, and the like, but is preferably Is 1 to 10% by weight. That is, although the liquid crystal aligning agent of this invention is apply | coated to the surface of a board | substrate as mentioned later, Preferably, the coating film used as a liquid crystal aligning film is formed, but when the solid content concentration is less than 1 weight%, the film thickness of this coating film is small. Thus, when a good liquid crystal alignment film is not obtained, and when the solid content concentration exceeds 10% by weight, the film thickness of the coating film becomes excessive and a good liquid crystal alignment film is not obtained, and the viscosity of the liquid crystal aligning agent is increased, resulting in coating properties. It becomes inferior.

The range of particularly preferable solid content concentration differs depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, in the case of the spinner method, a solid content concentration of 1.5 to 4.5% by weight is particularly preferable. In the case of the printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thus the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thus the solution viscosity is in the range of 3 to 15 mPa · s.

The temperature when preparing the liquid crystal aligning agent of the present invention is preferably 10 to 45 ° C, and more preferably 20 to 30 ° C.

<Method of forming a liquid crystal alignment film>

A liquid crystal aligning film can be formed using the liquid crystal aligning agent of this invention. That is, a liquid crystal aligning film can be formed by apply | coating the liquid crystal aligning agent of this invention on a board | substrate to form a coating film, and passing through the process of irradiating light to this coating film.

The liquid crystal aligning agent of this invention is applicable to manufacture of a liquid crystal display element which has suitable liquid crystal cells, such as TN type, STN type, IPS type, FFS type, VA type, MVA type, for example. However, it is preferable to apply to a liquid crystal display element having a so-called horizontally-aligned liquid crystal cell, such as TN type, STN type, IPS type, FFS type, etc., in that the advantageous effect of the present invention is maximized.

When the liquid crystal aligning film formed of the liquid crystal aligning film of the present invention is applied to a TN type or STN type liquid crystal display device, as the substrate, two substrates on which a patterned transparent conductive film is formed are used as a pair, and the liquid crystal is used. The alignment agent is applied on the surface of each substrate on which the transparent conductive film is formed. On the other hand, when a liquid crystal alignment film is applied to an IPS-type or FFS-type liquid crystal display device, the substrate includes a substrate having an electrode on which a transparent conductive film or a metal film is patterned in a comb shape, and a counter substrate on which no electrode is formed. Is used as a pair, and the liquid crystal aligning agent is applied to the formation surface of the comb-shaped electrode and one surface of the counter substrate.

In either of the above cases, examples of the substrate include glass such as float glass and soda glass; Transparent substrates made of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, and polycarbonate can be used. As the transparent conductive film, for example, an ITO film made of In ₂ O ₃ -SnO ₂ , a NESA (registered trademark) film made of SnO ₂ or the like can be used. As the metal film, for example, a film made of metal such as chromium can be used. For patterning the transparent conductive film and the metal film, for example, after forming a transparent conductive film without a pattern, a method of forming a pattern by photo-etching, sputtering, or the like, or using a mask having a desired pattern when forming the transparent conductive film Method.

In order to further improve the adhesion between the substrate and the transparent conductive film or metal film and the coating film during application of the liquid crystal aligning agent for photo-alignment onto the substrate, the substrate and the transparent conductive film or metal film are previously A functional silane compound, titanate compound, or the like may be applied.

The liquid crystal aligning agent for photo-alignment onto the substrate can be preferably applied by an appropriate coating method such as an offset printing method, a spin coating method, a roll coater method, an inkjet printing method, and then the coated surface is heated (free). Baking) to form a coating film. The pre-baking conditions are, for example, 0.1 to 5 minutes at 40 to 120 ° C.

Subsequently, by irradiating light to the coating film formed as described above, the liquid crystal alignment ability is imparted to the coating film to be a liquid crystal alignment film. Here, as the light, for example, ultraviolet rays and visible rays containing light having a wavelength of 150 to 800 nm can be used, but it is preferable to use ultraviolet rays containing light having a wavelength of 200 to 400 nm. The irradiation light may be polarized or non-polarized, but is preferably polarized. As the light source, for example, a low pressure mercury lamp, a high pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an Hg-Xe lamp, an excimer laser, or the like can be used. The light in the above-described preferred wavelength range can be obtained by means of using the light source in combination with a filter, a diffraction grating, or the like.

The irradiation amount of light is preferably 400 to 50,000 J / m 2, and more preferably 1,000 to 10,000 J / m 2.

It is preferable to provide the coating film irradiated with light as described above and provided with the liquid crystal aligning ability for use after further heating (post-baking). The post-baking condition is preferably 120 to 300 ° C, more preferably 150 to 250 ° C, preferably 5 to 200 minutes, and more preferably 10 to 100 minutes.

The film thickness of the liquid crystal aligning film formed from the liquid crystal aligning agent of the present invention is preferably 0.001 to 1 µm, and more preferably 0.005 to 0.5 µm.

<Liquid crystal display element>

By the method of the present invention, a liquid crystal display element can be manufactured as follows, for example, using a substrate on which a liquid crystal alignment film is formed as described above.

A pair of substrates on which a liquid crystal alignment film is formed is prepared as described above, and a liquid crystal cell having a configuration in which liquid crystals are held between the pair of substrates is manufactured.

As the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal, or the like can be used. It is preferable to have positive dielectric anisotropy to form a nematic liquid crystal, for example, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, flutes Midine type liquid crystal, dioxane type liquid crystal, bicyclooctane type liquid crystal, cuban type liquid crystal, and the like are used. In addition, for example, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonate, and cholesteryl carbonate;

A chiral agent sold under the trade names "C-15" and "CB-15" (above, manufactured by Merck);

Ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be further added and used.

In order to manufacture a liquid crystal cell, for example, two substrates are disposed to face each other with a gap (cell gap) facing each liquid crystal alignment film, and the peripheral portions of the two substrates are bonded using a sealing agent, and the substrate surface And after filling and filling the liquid crystal into the cell gap partitioned by the sealing agent, sealing the injection port;

After applying, for example, a photocurable sealing agent to a predetermined number of places on one of the two substrates on which the liquid crystal alignment film is formed, the liquid crystal is added dropwise to a predetermined number of places on the surface of the liquid crystal alignment film, and then the liquid crystal alignment film The other substrate may be bonded so as to face each other, and then the entire surface of the substrate may be irradiated with ultraviolet light to cure the sealing agent (ODF method = One Drop Fill method) or the like. As the sealing agent, for example, an aluminum oxide ball as a spacer and an epoxy resin containing a curing agent can be used.

Even in the case of any of the above methods, it is preferable to remove the flow orientation during liquid crystal charging by heating the liquid crystal cell to a temperature at which the liquid crystal used takes an isotropic phase and then gradually cooling it to room temperature.

And a liquid crystal display element can be manufactured by bonding a polarizing plate to the outer surface of a liquid crystal cell. Here, a desired liquid crystal display element can be obtained by appropriately adjusting the angles of the polarizing plates in the two substrates on which the liquid crystal alignment film is formed. As a polarizing plate, the polarizing plate called the "H film" which absorbed iodine while extending | stretching orientation of polyvinyl alcohol, the polarizing plate sandwiched between the cellulose acetate protective film, or the polarizing plate which consists of H film itself, etc. are mentioned.

The liquid crystal display device manufactured as described above is excellent in performances such as display characteristics and electrical characteristics.

(Example)

Hereinafter, the present invention will be described more specifically by examples, but the present invention is not limited to these examples.

The solution viscosity of each polymer solution in the synthesis examples of the following polymers is a value measured at 25 ° C using an E-type rotational viscometer for the polymer solutions indicated in each synthesis example.

<Synthesis example of specific diamine>

The following synthesis examples were repeated on the following scales as necessary to ensure the required amount for the synthesis of subsequent polymers.

Synthesis Example A-1

Compound (A-1-1) was synthesized according to Reaction Scheme 1 below.

(1) Synthesis of Compound (A-1-1a)

In the reaction vessel, 105.0 mmol of methyl 4-hydroxybenzoate (15.98 g), 50.0 mmol of 1,4-dibromobutane (10.80 g), 120.0 mmol of potassium carbonate (16.59 g) and 100 mL of N, N-dimethylacetamide The mixture was mixed and reacted at 80 ° C under stirring for 6 hours. From the middle of the reaction, crystal formation was observed in the reaction system.

After the completion of the reaction, 500 mL of ethyl acetate and 300 mL of distilled water were added to the reaction mixture in this order to perform separation and washing. After washing, the recovered organic layer was placed under reduced pressure, and the total amount of the solid obtained by removing the solvent was recovered, washed with ethanol, and then dried under reduced pressure to obtain 44.4 mmol (A-1-1a) of a white crystalline compound (A-1-1a). 15.91g) (Yield 88.8%).

(2) Synthesis of Compound (A-1-1b)

In the reaction vessel, the total amount of the compound (A-1-1a) obtained above (44.4 mmol (15.91 g)), lithium hydroxide monohydrate 133.2 mmol (5.59 g), methanol 60 mL, ethanol 40 mL and distilled water 30 mL were added and mixed. The reaction was carried out at 80 ° C under stirring for 3 hours. After completion of the reaction, 1N hydrochloric acid (mL) was added to the reaction mixture to make the liquidity acidic, and the resulting powder was filtered. This powder was thoroughly washed sequentially with distilled water and ethanol, and then dried under reduced pressure to obtain 41.6 mmol (13.73 g) of compound (A-1-1b) (yield 93.6%).

(3) Synthesis of Compound (A-1-1c)

In the reaction vessel, the total amount of the compound (A-1-1b) obtained above (41.6 mmol (13.73 g)), 35 mL of thionyl chloride and N, N-dimethylformamide were added and mixed, and the mixture was stirred at 80 ° C. The reaction was performed for 1 hour. After completion of the reaction, the reaction mixture was placed under reduced pressure in a water flow aspirator to remove unreacted thionyl chloride. 100 mL of tetrahydrofuran was added to the obtained solution, and this was set as solution <1>.

In another reaction vessel, 87.3 mmol (12.14 g) of 4-nitrophenol, 124.7 mmol (17.3 mL) of triethylamine and 150 mL of tetrahydrofuran were added and stirred under an ice bath. Here, the solution <1> was added dropwise over 1 hour, and the reaction was performed at 25 ° C under stirring for 4 hours. After completion of the reaction, 500 mL of ethyl acetate was added to the reaction mixture, and then washed sequentially with 1N hydrochloric acid and distilled water. At this time, the powder was floating on the organic layer side.

The powder was collected by filtration, recovered, and dried under reduced pressure to obtain 36.9 mol (21.15 g) of a pale yellow powdery compound (A-1-1c) (yield 88.8%).

(4) Synthesis of Compound (A-1-1)

In a nitrogen atmosphere, in a reaction vessel, 36.9 mol (21.15 g) of the compound (A-1-1c) obtained above, 738 mmol (48.3 g) of ammonium chloride, 147.6 mmol (7.75 g) of ammonium chloride, 332 mL of tetrahydrofuran, and 37 mL of ethanol were added. Mix and stir in an ice bath. After 18.5 mL of distilled water was added dropwise thereto, the reaction was performed by sequentially stirring at 25 ° C for 8 hours and at 70 ° C for 1 hour. After completion of the reaction, insoluble components such as inorganic salts were filtered off from the reaction mixture and removed. The organic layer obtained by adding 1,850 mL of ethyl acetate to the filtrate was washed 4 times with 738 mL of distilled water. After the organic layer after washing was filtered, the solvent was removed under reduced pressure to obtain a powder. This powder was sequentially washed with ethanol and ethyl acetate, and then the solvent was completely removed under reduced pressure to obtain 21.0 mmol (10.7 g) of compound (A-1-1) (yield 56.8%).

Synthesis Example A-2

Compound (A-8-1) was synthesized according to Scheme 2 below:

(Ts in the formula (A-8-1b) is a tosyl group).

(1) Synthesis of Compound (A-8-1a)

To a 200 mL three-necked flask equipped with a nitrogen introduction tube, a reflux tube, and a thermometer, 20 g of 4-nitrophenylacetic acid, 10 g of p-hydroxybenzaldehyde and 5 mL of piperidine were added and reacted at 140 ° C for 1 hour. Subsequently, 75 mL of ethanol, 25 mL of water, and 0.5 mL of acetic acid were added and reacted under reflux for 2 hours. After completion of the reaction, 17 g of a reddish brown compound (A-8-1a) was obtained by filtering the produced precipitate and recrystallizing it using isopropanol.

(2) Synthesis of Compound (A-8-1c)

To a 1 L three-necked flask equipped with a reflux tube and a nitrogen introduction tube, 14 g of the compound (A2-8-1a) obtained above, 20 g of potassium carbonate, and 460 mL of acetonitrile were added and reacted under reflux for 30 minutes. Subsequently, 12 g of compounds (A-8-1b) were added thereto, and the reaction was performed under reflux for 24 hours. After completion of the reaction, the reaction mixture was poured into 1 L of ethyl acetate, suspended, washed once with 500 mL of dilute hydrochloric acid and three times with 500 mL of water, and then washed sequentially. After removing the solvent from the organic layer under reduced pressure, the obtained yellow crystals were filtered and taken. , 14 g of compound (A-8-1c) was obtained by completely removing the solvent under reduced pressure.

(3) Synthesis of Compound (A-8-1)

In a 1 L three-necked flask equipped with a reflux tube, a nitrogen introduction tube, and a thermometer, 13 g of the compound (A-8-1c) obtained above, 1.3 g of 5% by weight palladium carbon powder, 250 mL of tetrahydrofuran, 35 mL of ethanol and 80 weight of 12 mL of hydrazine monohydrate was added and reacted under reflux for 6 hours. After completion of the reaction, 500 mL of ethyl acetate was added to the filtrate obtained by filtration of the reaction mixture, followed by washing three times with 500 mL of water. The organic layer after washing was concentrated, and the precipitated white crystals were filtered out and the solvent was completely removed under reduced pressure to obtain 9.5 g of white crystals of the compound (A-8-1).

<Synthesis of polymer>

The abbreviations of tetracarboxylic dianhydride used in the synthesis examples of the following polymers have the following meanings, respectively.

Compound (T-1): Compound represented by Formula (T-1)

Compound (T-2): Compound represented by formula (T-2)

Synthesis Example P-1

9.3 g of compound (T-1) as tetracarboxylic acid anhydride and 10.7 g of compound (A-1-1) obtained in Synthesis Example A-1 as diamine were dissolved in 80 g of N-methyl-2-pyrrolidone, By reacting at room temperature for 4 hours, a solution containing 20% by weight of polyamic acid (PA-1) was obtained. The solution viscosity of this solution was 2,700 mPa · s.

Synthesis Example P-2

7.4 g of compound (T-2) as tetracarboxylic acid anhydride and 13.6 g of compound (A-1-1) obtained in Synthesis Example A-1 as diamine were dissolved in 80 g of N-methyl-2-pyrrolidone, By reacting at room temperature for 4 hours, a solution containing 20% by weight of polyamic acid (PA-2) was obtained. The solution viscosity of this solution was 1,900 mPa · s.

Synthesis Example P-3

9.5 g of compound (T-1) as tetracarboxylic acid anhydride and 10.5 g of compound (A-8-1) obtained in Synthesis Example A-2 as diamine were dissolved in 80 g of N-methyl-2-pyrrolidone, By reacting at room temperature for 4 hours, a solution containing 20% by weight of polyamic acid (PA-3) was obtained. The solution viscosity of this solution was 3,000 mPa · s.

Comparative Synthesis Example R-1

13.3 g of compound (T-1) as tetracarboxylic acid anhydride and 6.7 g of 4-aminobenzoic acid-4-aminophenyl as diamine were dissolved in 80 g of N-methyl-2-pyrrolidone and reacted at room temperature for 4 hours. Thereby, a solution containing 20% by weight of polyamic acid (R-1) was obtained. The solution viscosity of this solution was 1,500 mPa · s.

Comparative Synthesis Example R-2

13.6 g of compound (T-1) as tetracarboxylic dianhydride and 6.4 g of 1,2-bis (4-aminophenyl) ethane as diamine were dissolved in 80 g of N-methyl-2-pyrrolidone and 4 hours at room temperature. By performing the reaction, a solution containing 20% by weight of polyamic acid (R-2) was obtained. The solution viscosity of this solution was 2, 900 mPa · s.

<Preparation and evaluation of liquid crystal aligning agent>

Example 1

1. Preparation of liquid crystal aligning agent

To the solution containing polyamic acid (PA-1) obtained in Synthesis Example (P-1), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added and stirred sufficiently, and the solvent was added. It was set as the solution whose composition was NMP: BC = 60: 40 (weight ratio), and solid content concentration 2.5 weight%. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 µm.

2. Evaluation of liquid crystal aligning agent

(1) Preparation of liquid crystal cell for evaluation of liquid crystal alignment, voltage retention and contrast

The liquid crystal aligning agent prepared above was coated on each transparent electrode surface of two glass substrates (a pair) with a transparent electrode made of an ITO film using a spinner so that the film thickness was 0.1 µm, followed by 1 minute at 80 ° C. Heating (pre-baking) was performed to form coating films, respectively. The surface of these coatings was irradiated from the normal direction of the substrate with the irradiation amount shown in Table 1, using Hg-Xe lamps, and irradiated with ultraviolet rays of polarization containing 254 nm of bright lines, and heated in a clean oven at 230 ° C. for 1 hour (post-baking) ) To form a liquid crystal alignment film on two (a pair) substrates, respectively.

Next, for one of the pair of substrates subjected to the light irradiation treatment, after leaving the liquid crystal injection port on the outer periphery of the surface on which the liquid crystal alignment film was formed, screen printing coating the epoxy resin adhesive containing an aluminum oxide sphere having a diameter of 5.5 µm , A pair of substrates were overlapped and pressed so that the liquid crystal alignment film-forming surface was relative to each other, and the projection direction of the polarizing surface upon light irradiation coincided, and the adhesive was thermally cured by heating at 150 ° C for 1 hour.

Subsequently, a nematic liquid crystal (MLC-7028, manufactured by Merck Co., Ltd.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Moreover, in order to remove the flow orientation at the time of liquid crystal injection, the liquid crystal cell was produced by heating this to 150 degreeC and gradually cooling to room temperature.

(2) Evaluation of liquid crystal alignment

The presence or absence of an abnormal domain when the voltage of AC 5V was turned on / off (applied / released) with respect to the liquid crystal cell produced above was observed with a polarization microscope.

As a result of evaluating the case where the abnormal domain was not observed as the liquid crystal alignment property "good" and the case where at least one of the abnormal domains was observed as the liquid crystal alignment property "poor", the liquid crystal alignment property of this liquid crystal cell was determined to be "good". .

(3) Evaluation of voltage preservation rate

When the voltage of 5 V was applied to the liquid crystal cell manufactured as described above and applied with a 60 microsecond span and a span of 167 milliseconds, the voltage preservation ratio of 167 milliseconds after release of the application was measured. As a result, the voltage preservation ratio of the liquid crystal cell was 98%. .

As a measuring device for the voltage retention rate, a model name "VHR-1" manufactured by Toyo Technica Co., Ltd. was used.

(4) Contrast evaluation

The contrast after driving the above-mentioned liquid crystal cell for 30 hours was investigated.

A device in which a polarizer and a photodetector are provided between the light source and the light amount detector is used, the liquid crystal cell prepared above is disposed between the polarizer and the photodetector, and the light transmittance β under cross-Nicol is examined, The minimum relative transmittance (%) was calculated by substituting these values into the following formula (1):

Minimum relative transmittance (%) = {(β-B0) / (B100-B0)} × 100 (1)

(In formula (1), B0 is the light transmittance of the blank under the cross nicol;

B100 is the light transmittance of the blank under parallel Nicole; And

β is the light transmittance measured in a state in which a liquid crystal cell is disposed between the polarizer and the analyzer under the cross nicol).

The minimum relative transmittance calculated by Equation (1) above indicates the degree of the black level in the dark state, and the smaller the value of the minimum relative transmittance, the better the contrast can be evaluated.

The case where the minimum relative transmittance was less than 0.5% was evaluated as contrast "good", the case where it was 0.5 to 1.0%, the contrast "possible", and the case where it exceeded 1.0% as contrast "poor". The minimum relative transmittance of the liquid crystal cell was 0.3%, so the contrast was judged to be "good".

(5) Production of liquid crystal cell for evaluating afterimage characteristics

A liquid crystal cell for evaluating afterimage characteristics (FFS) in the same manner as in "(1) Preparation of liquid crystal cell for liquid crystal alignment, voltage retention and contrast evaluation", except that a pair of substrates having the following configuration was used as a pair of substrates. Type liquid crystal cell), and further, a polarizing plate was bonded to both sides of the substrate to obtain a liquid crystal display element.

Here, as the electrode substrate, a glass substrate formed of two lines of electrodes (electrodes A 101 and B 102) made of chromium having a comb-shaped pattern shown in FIG. 1; As counter substrates, glass substrates without electrodes were used. The liquid crystal aligning agent was applied to the electrode-forming surface of the electrode substrate and one surface of the counter substrate.

(6) Evaluation of afterimage characteristics (burn-in)

The liquid crystal display device manufactured above was placed under an environment of 25 ° C. and 1 atmosphere, and no voltage was applied to electrode B, and a composite voltage of 3.5 V AC and 5 V DC voltage was applied to electrode A for 2 hours. Immediately after 2 hours, an alternating voltage of 4 V was applied to both electrodes A and B. Then, from the time when the voltage of the alternating current 4V was started to be applied to both electrodes, the time until the difference in light transmittance between both electrodes could not be visually observed was measured. When this time was less than 100 seconds, the afterimage characteristic "good";

When it was 100 seconds or more and less than 150 seconds, afterimage characteristics were "possible"; And

When it was 150 seconds or more, as a result of evaluating the residual image characteristic as "poor", the residual image characteristic of the liquid crystal display element was "good".

Examples 2 to 4 and Comparative Examples 1 and 2

Instead of the solution containing polyamic acid (PA-1), a solution containing each type of polyamic acid shown in Table 1 was used, and also, “2. (1) Preparation of liquid crystal cells for liquid crystal alignment, voltage retention and contrast evaluation ”and“ 2. (5) A liquid crystal aligning agent was prepared in the same manner as in Example 1, except that the amounts of polarized ultraviolet rays irradiated in "Production of a Liquid Crystal Cell for Evaluation of Afterimage Characteristics" were respectively as described in Table 1, and the liquid crystal was obtained. Various evaluations were performed using an alignment agent.

Table 1 shows the evaluation results.

As can be easily understood from Table 1, the liquid crystal aligning agent of the present invention containing a polymer having a structure represented by the formula (1) in the main chain, when the photo-alignment method is applied to it, the liquid crystal aligning property and voltage preservation rate In addition to this superiority, it has been verified to provide a liquid crystal alignment film excellent in both contrast and afterimage characteristics.

Claims (8)

A liquid crystal aligning agent comprising at least one polymer selected from the group consisting of polyamic acid having a structure represented by the following formula (1) in the main chain and an imidized polymer thereof:

(In Formula (1), two X's are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, and 1 to 10 carbon atoms. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
Two Y are each independently a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond;
R is a C2-C12 alkylene group interrupted by an oxygen atom; And
"*" Represents a bonding hand). According to claim 1,
R in the formula (1), the following formula:
-(CR'H-CH ₂ )-(O-CR'H-CH ₂ ) _m-
(However, R 'is a hydrogen atom, a methyl group or an ethyl group;
m is an integer of 1 to 3) and the liquid crystal aligning agent. According to claim 1,
A liquid crystal aligning agent in which the polymer is at least one polymer selected from the group consisting of polyamic acid obtained by reacting tetracarboxylic acid anhydride and a diamine containing a compound represented by the following formula (A1) and an imidized polymer thereof:

(In formula (A1), X, Y and R are respectively the same meanings as in formula (1)). According to claim 3,
The liquid crystal aligning agent in which the tetracarboxylic acid anhydride contains a compound represented by the following formula (T1):

(In formula (T1), Z is an oxygen atom, a sulfur atom, an ester bond, a thioester bond, or -NH-, provided that when Z is plural, each independently has the above-mentioned definitions;
R ¹ is an arylene group having 6 to 18 carbon atoms or an alkylene group having 2 to 6 carbon atoms, provided that when R ¹ is plural, each independently has the above-mentioned definitions; And
n1 is an integer from 0 to 2). It is formed from the liquid crystal aligning agent in any one of Claims 1-4, The liquid crystal aligning film characterized by the above-mentioned. A liquid crystal display device comprising the liquid crystal alignment film according to claim 5. Polyamic acid obtained by reacting tetracarboxylic acid anhydride and a diamine containing a compound represented by the following formula (A1) or an imidized polymer thereof:

(In Formula (A1), two Xs are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, and 1 to 10 carbon atoms. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
A plurality of Y are each independently a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond;
R is a C2-C12 alkylene group interrupted by an oxygen atom). Compound represented by the following formula (A1):

(In Formula (A1), two Xs are each independently an oxygen atom, a sulfur atom, an ester bond, a thioester bond, an amide bond, -NH-, -C (= O)-, and 1 to 10 carbon atoms. A divalent saturated aliphatic group or a divalent unsaturated aliphatic group having 2 to 10 carbon atoms;
A plurality of Y are each independently a single bond, an oxygen atom, a sulfur atom, an ester bond or a thioester bond;
R is a C2-C12 alkylene group interrupted by an oxygen atom).

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