JP6172453B2 - Liquid crystal alignment agent - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent. More specifically, the present invention relates to a liquid crystal aligning agent that provides a liquid crystal aligning film in which good liquid crystal alignment properties and high rubbing resistance are compatible at a high level.

Various drive systems having different electrode structures, physical properties of liquid crystal molecules used, manufacturing processes, and the like have been developed for liquid crystal display elements. For example, TN (twisted nematic) type, STN (super-twisted nematic) type, VA ( vertical alignment (MVA), multi-domain vertical alignment (IPS), IPS (in-plane switching), FFS (fringe field switching), PSA (polymer-stained) display, etc. .
These liquid crystal display elements have a liquid crystal alignment film for aligning liquid crystal molecules. In general, a film made of a polymer such as polyamic acid, polyimide, or polysiloxane is used as the material of the liquid crystal alignment film because it has various properties such as heat resistance, mechanical strength, and affinity with liquid crystal. ing. Here, in a driving method (for example, TN type, IPS type, FFS type, etc.) in which liquid crystal molecules are horizontally aligned, a rubbing treatment process is performed in order to impart a liquid crystal alignment capability to the film formed on the substrate. Applied. The rubbing process is a process of rubbing the surface of the film with a cloth. Usually, a cloth having bristles is wound around a roller, and the substrate and the roller are relatively moved while being rotated by pressing the roller against the film. Yes. And rubbing intensity | strength can be controlled by adjusting the rotational speed of a roller, the pushing length of a bristle, the relative moving speed of a board | substrate and a roller, etc. (patent documents 1 and 2).
In general, when the rubbing strength is increased, stronger liquid crystal orientation is developed and display defects due to image sticking are less likely to occur. However, if the rubbing strength is excessively increased, an excessive force is applied between the coating and the fabric, and thus the coating and the fabric are peeled off, which may reattach to the coating. Such reattachment of the peeled material leads to a display defect in the finished liquid crystal display element, and therefore the yield in the liquid crystal alignment film manufacturing process is lowered.

In recent years, the application of liquid crystal display elements to television applications has become common;
Other related facilities such as home theater use and Internet TV (for example, video disc system, total audio system, Internet-connected karaoke, etc.) have already become common;
Information displays and advertising displays are spreading in airports, liquids and streets. For this reason, with regard to the liquid crystal display element, the viewing time has been extended and the backlight has been strengthened. Therefore, the demand for seizure resistance has become stricter than ever. As described above, in order to improve the seizure characteristics, the rubbing strength may be increased, but this causes a problem of peeling of the coating film and the fabric.
In order to improve such a dilemma, an attempt has been made to improve the rubbing resistance by adding an additive to the liquid crystal aligning agent. For example, Patent Document 3 describes that a liquid crystal aligning agent containing a polymer and a polyfunctional epoxy compound gives a film having a high degree of rubbing resistance. According to this technique, the rubbing resistance of the coating is improved, but the liquid crystal alignment is impaired.
Thus, in the prior art, good liquid crystal orientation and high rubbing resistance are in a trade-off relationship, and no material is known that achieves both at a level suitable for practical use.

JP 2007-256485 A JP 2009-104059 A International Publication No. 2008/114848 JP 2010-97188 A International Publication No. 2009/096598

  The present invention has been made to improve the current state of the prior art as described above. Accordingly, the main object of the present invention is to provide a liquid crystal aligning agent for obtaining a liquid crystal aligning film in which rubbing resistance and liquid crystal alignability are compatible at a high level.

The above objects and advantages of the present invention are as follows:
Polymer (A) and compound (B) represented by the following formula (B)
It is achieved by a liquid crystal aligning agent characterized by containing.

(In Formula (B), two X ^{1 s} each independently represent a monovalent organic group containing a group selected from a group having an oxiranyl structure, a group having an oxetanyl structure, and a group having a (meth) acryloyloxy group). Group,
X ² is a group represented by the formula (X ² -1) or the formula (X ² -2) described in paragraphs [0035] and [0036] . )

Since the liquid crystal aligning agent of the present invention provides a coating having a high level of both rubbing resistance and liquid crystal alignment, even when applied to a liquid crystal display device equipped with a high-intensity backlight, The deterioration of display quality is extremely small, and the long-term reliability is excellent.
The liquid crystal display device manufactured using the liquid crystal aligning agent of the present invention can be effectively applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs. It can be used for display devices such as digital cameras, mobile phones, smartphones, various monitors, and liquid crystal televisions.

The liquid crystal aligning agent of this invention contains a polymer (A) and a compound (B) as above-mentioned.
Hereinafter, the essential component in the liquid crystal aligning agent of this invention and the other component arbitrarily mix | blended as needed are demonstrated in order.

<Polymer (A)>
Although there is no restriction | limiting in particular about the polymer (A) in this invention, As a preferable thing, for example, polyamic acid, the imidation polymer of polyamic acid, polyamic acid ester, polyester, polyamide, polysiloxane, a cellulose derivative, a polyacetal, a polystyrene derivative , Poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like. Among these, it is more preferable to use at least one polymer selected from the group consisting of a polyamic acid, an imidized polymer of polyamic acid, and a polyamic acid ester. These polymers are 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride It is particularly preferable that the structure has a structure derived from at least one compound selected from the group consisting of a compound and 1,2,3,4-cyclobutanetetracarboxylic dianhydride.
Hereinafter, these preferable polymers will be described in order.

[Polyamic acid]
The polyamic acid as the polymer (A) in the present invention can be synthesized, for example, by reacting tetracarboxylic dianhydride with diamine.
Examples of the tetracarboxylic dianhydride used for synthesizing the polyamic acid in the present invention include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride and the like. Can be mentioned. Specific examples of these are:
Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b- Hexahydro-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- No 1,2-dicarboxylic acid 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2 : 4,6: 8-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride Etc .;
As an aromatic tetracarboxylic dianhydride, for example, pyromellitic dianhydride, 4,4′-oxydiphthalic dianhydride, etc.,
Examples thereof include tetracarboxylic dianhydrides described in Patent Document 4 (Japanese Patent Laid-Open No. 2010-97188), and it is preferable to use one or more selected from these.

The tetracarboxylic dianhydride used for synthesizing the polyamic acid is an alicyclic tetracarboxylic dianhydride from the viewpoint of the solubility of the resulting polyamic acid in the solvent and the transparency of the liquid crystal alignment film to be formed. It is preferable that it contains. This alicyclic tetracarboxylic dianhydride is
2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2- c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2- c] furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2,3,4- More preferably, it is at least one selected from the group consisting of cyclobutanetetracarboxylic dianhydride;
2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2, Particularly preferred is at least one selected from the group consisting of 3,4-cyclobutanetetracarboxylic dianhydride.
Therefore, the polyamic acid in the present invention is particularly preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4. , 6: 8-dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride have a structure derived from at least one compound selected from the group consisting of.
The tetracarboxylic dianhydride used for synthesizing the polyamic acid in the present invention is an alicyclic tetracarboxylic dianhydride as described above, 10 mol% based on the total amount of the tetracarboxylic dianhydride. It is preferably used above, more preferably at least 20 mol%, more preferably at least 50 mol%, particularly preferably at least 75 mol, particularly preferably at least 80 mol%, In particular, it is preferably 85 mol% or more.

Examples of the diamine used for synthesizing the polyamic acid in the present invention include aliphatic diamine, alicyclic diamine, aromatic diamine, and diaminoorganosiloxane. Specific examples of these diamines include aliphatic diamines such as m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;
Examples of the alicyclic diamine include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane, and the like.
The aromatic diamine can be classified into an aromatic diamine having a liquid crystal aligning group and an aromatic diamine having no liquid crystal aligning group. Here, the liquid crystal orientation group is a group having a steroid structure, a group having an alkyl group having 4 or more carbon atoms, a group having an alkoxy group having 4 or more carbon atoms, a group having a fluoroalkyl group having 1 or more carbon atoms, Examples include a group having a fluoroalkoxy group having 1 or more carbon atoms, a group in which two or more ring structures selected from a benzene ring and a cyclohexane ring are linked directly or via a bonding group, and a group having a plurality of these. Can do.

  Specific examples of the aromatic diamine having such a liquid crystal alignment group include, for example, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diamino Benzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis (4-aminobenzoyl) Oxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4′-trifluoromethylbenzoy) Loxy) cyclohexyl-3,5-diaminobenzoate, 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, 1,3-diamino-4-octadecyl Examples thereof include oxybenzene, 3- (3,5-diaminobenzoyloxy) cholestane, 3,6-bis (4-aminobenzoyloxy) cholestane, and a compound represented by the following formula (D-1).

(In Formula (D-1), X ^I and X ^II are each independently a single bond, —O—, —COO— or OCO—, and R ^I and R ^II are each independently one having 1 carbon atom. An alkanediyl group of ˜3, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and n is 0 or 1, provided that a and b Are never 0 at the same time.)
Specific examples of the group “—C _c H _{2c + 1} ” include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group. Group, n-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group Group, n-eicosyl group and the like. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to other groups.
Specific examples of the compound represented by the formula (D-1) include compounds represented by the following formulas (D-1-1) to (D-1-5).

  Specific examples of the aromatic diamine having no liquid crystal orientation group include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2 '-Dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 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) hexafluoropropane, 4,4 ′-(p-phenylenediisopropylidene) bisa Phosphorus, 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-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole N-phenyl-3,6-diaminocarbazole, N, N′-bis (4-aminophenyl) -benzidine, N, N′-bis (4-aminophenyl) -N, N′-dimethylbenzidine, 1, 4-bis- (4-aminophenyl) -piperazine, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl 1H-indene-5-amine, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine, (4-aminophenyl) -4-aminobenzoate 1,3-bis (N- (4-aminophenyl) piperidin-4-yl) propane, bis (4-aminophenethyl) adipate, 3,5-diaminobenzoic acid, 2,4-diamino-N, N -Diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine and the like.

Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane.
As the diamine used for synthesizing the polyamic acid in the present invention, diamines described in Patent Document 4 (Japanese Patent Laid-Open No. 2010-97188) can be used in addition to the above.
The diamine used for synthesizing the polyamic acid in the present invention is preferably one or more selected from the above.
The diamine used for synthesizing the polyamic acid in the present invention preferably contains an aromatic diamine in an amount of 30 mol% or more, more preferably 50 mol% or more, based on the total diamine, and more preferably 80 mol%. It is particularly preferable to include the above.

  When the liquid crystal aligning agent of the present invention is applied to a TN type or STN type liquid crystal display element, the diamine used for synthesizing the polyamic acid is an aromatic diamine having a liquid crystal aligning group with respect to all diamines. It is preferable to contain in the ratio of 20 mol% or less, It is more preferable to contain in the range of 2-15 mol%, It is preferable to contain in the range of 10-15 mol% especially. On the other hand, when the liquid crystal aligning agent of the present invention is applied to an IPS-type or FFS-type liquid crystal display element, the diamine used for synthesizing the polyamic acid is the total use ratio of the aromatic diamine having a liquid crystal aligning group. It is preferable to set it as the range of 5 mol% or less with respect to diamine, it is more preferable to set it as the range of 3 mol% or less, and it is especially preferable not to contain this.

The polyamic acid as the polymer (A) in the present invention is prepared by using a tetracarboxylic dianhydride and a diamine as described above as appropriate molecular weight regulators (for example, acid monoanhydride, monoamine compound, It can be synthesized by reacting with a monoisocyanate compound and the like in a suitable organic solvent according to a known method.
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, and the ratio which becomes 0.3-1.2 equivalent is more preferable. The synthesis reaction of polyamic acid is preferably performed in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.
Examples of the organic solvent used in the reaction include aprotic polar solvents, phenol solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like.

Specific examples of the organic solvent include aprotic polar solvents such as N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, N, N-dimethyl. Acetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, etc. As phenolic solvents, for example, phenol, m-cresol, xylenol, halogenated phenol, etc .;
Examples of alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether, and the like. Examples of ketones include acetone, methyl ethyl ketone, Methyl isobutyl ketone, cyclohexanone, etc .; as esters, for example, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, Isoamyl propionate, isoamyl isobutyrate, diacetone alcohol and the like;
Examples of ethers include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, and ethylene glycol ethyl ether acetate. Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, diisopentyl ether and the like;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, and the like. Examples of the hydrocarbon include hexane, heptane, octane, benzene, Examples thereof include toluene and xylene.

Among these organic solvents, one or more selected from the group consisting of an aprotic polar solvent and a phenolic solvent (first group of organic solvents), or one or more selected from the first group of organic solvents, It is preferable to use a mixture with one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons and hydrocarbons (second group organic solvent). In the latter case, the use ratio of the second group organic solvent is preferably 50% by weight or less, more preferably 40% by weight with respect to the total amount of the first group organic solvent and the second group organic solvent. % Or less, more preferably 30% by weight or less.
The amount of organic solvent used (a) is such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by weight based on the total amount (a + b) of the reaction solution. It is preferable.
As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent. When polyamic acid is subjected to dehydration and cyclization to obtain an imidized polymer, the above reaction solution may be directly subjected to dehydration and cyclization reaction, or after isolation of polyamic acid contained in the reaction solution and subjected to dehydration and cyclization reaction. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration cyclization reaction. Isolation and purification of the polyamic acid can be performed according to known methods.

[Imidized polymer of polyamic acid]
The imidized polymer of polyamic acid as the polymer (A) in the present invention can be synthesized by dehydrating and ring-closing the above polyamic acid to imidize.
This imidized polymer may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the polyamic acid that is the precursor had, or by dehydrating and cyclizing only a part of the amic acid structure, A partially imidized product in which a structure and an imide ring structure coexist may be used. The polyimide according to the present invention has an imidation ratio of preferably 30% or more, more preferably 40 to 99%, and even more preferably 50 to 95% in that the voltage holding ratio can be increased. . This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of polyimide amic acid structures and the number of imide ring structures in percentage. Here, a part of the imide ring may be an isoimide ring.
The polyamic acid can be dehydrated and closed by, for example, a method of heating, or using a dehydrating agent and a dehydrating ring-closing catalyst according to a known method. Of these, a method using a dehydrating agent and a dehydrating ring-closing catalyst is preferred.

In the method of imidizing a polyamic acid solution by adding a dehydrating agent and a dehydrating ring-closing catalyst, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. It is preferable that the usage-amount of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of the amic acid structure of a polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, triethylamine and the like can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.
In this way, a reaction solution containing an imidized polymer of polyamic acid is obtained. This reaction solution may be used for the preparation of the liquid crystal aligning agent as it is, may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution, and the liquid crystal after isolating the polyimide. You may use for preparation of an aligning agent, or you may use for preparation of a liquid crystal aligning agent, after purifying the isolated polyimide. These purification operations can be performed according to known methods.

[Polyamic acid ester]
The polyamic acid ester as the polymer (A) in the present invention can be synthesized, for example, by the following method.
(1) A method of reacting a polyamic acid with a compound having a hydroxyl group, a halide and a compound having an oxiranyl group, or (2) reacting a tetracarboxylic acid diester or tetracarboxylic acid diester dihalide with a diamine. How to make.
The polyamic acid used in the method (1) is the same as the polyamic acid as the polymer (A) in the present invention. Therefore, the structure derived from an alicyclic tetracarboxylic dianhydride is preferably included in the range described above.

Examples of the compound having a hydroxyl group used in the method (1) include alcohols and phenol compounds. Specific examples thereof include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, t-butanol and the like;
Examples of phenol compounds include phenol and cresol.
Each can be mentioned.
Examples of the halide include, for example, methyl bromide, ethyl bromide, n-propyl bromide, isopropyl bromide, n-butyl bromide, isobutyl bromide, sec-butyl bromide, t-butyl bromide, stearyl bromide. Methyl chloride, ethyl chloride, n-propyl chloride, isopropyl chloride, n-butyl chloride, isobutyl chloride, secbutyl chloride, t-butyl chloride, stearyl chloride, 1,1,1-trifluoro-2-iodoethane, etc .;
Examples of the compound having an oxiranyl group include propylene oxide and the like.
Each can be mentioned.
The reaction between the polyamic acid and a compound selected from a compound having a hydroxyl group, a halide and a compound having an oxiranyl group can be carried out according to a known method.
Since the polyamic acid used in the method (1) is the same as the polyamic acid as the polymer (A) in the present invention, the resulting polyamic acid ester is preferably an alicyclic tetracarboxylic dianhydride (especially Preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1, A structure derived from at least one compound selected from the group consisting of 2,3,4-cyclobutanetetracarboxylic dianhydride) is included in the range described above.

The tetracarboxylic acid diester used in the above method (2) can be obtained, for example, by opening the tetracarboxylic dianhydride exemplified above as used in the synthesis of polyamic acid with an alcohol. . The alcohol used here is the same as the alcohol as the compound having a hydroxyl group used in the method (1). The tetracarboxylic acid diester dihalide can be obtained by reacting the tetracarboxylic acid diester obtained as described above with an appropriate chlorinating agent. Examples of the chlorinating agent include thionyl chloride. The tetracarboxylic dianhydride used as a raw material for these compounds is the same as the tetracarboxylic dianhydride for synthesizing the polyamic acid as the polymer (A) in the present invention. Accordingly, preferably alicyclic tetracarboxylic dianhydride (particularly preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane. -2: 4,6: 8-dianhydride and at least one compound selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride), It is included in the range.
The diamine used in the method (2) is the same as the diamine for synthesizing the polyamic acid as the polymer (A) in the present invention. The content ratio of the aromatic diamine containing the aromatic diamine and the liquid crystal alignment group to the total diamine is also the same as in the above case.

The reaction of tetracarboxylic acid diester or tetracarboxylic acid diester dihalide and diamine can be carried out according to a known method.
The tetracarboxylic dianhydride used as a raw material for synthesizing the tetracarboxylic acid diester or tetracarboxylic acid diester dihalide used in the method (2) is a polyamic acid as the polymer (A) in the present invention. Same as tetracarboxylic dianhydride for synthesis. Therefore, the polyamic acid ester obtained by the method (2) is preferably an alicyclic tetracarboxylic dianhydride (particularly preferably 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8 -At least one selected from the group consisting of tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride The structure derived from the compound) is included in the range described above.
The polyamic acid ester as the polymer (A) in the present invention may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist.

[Solution viscosity and weight average molecular weight of polymer (A)]
The polyamic acid, the imidized polymer of polyamic acid, and the polyamic acid ester as the polymer (A) obtained as described above are 10 to 800 mPa · s when each of them is a 10% by weight solution. It is preferable to have a solution viscosity of 15 to 500 mPa · s, and it is more preferable to have a solution viscosity of 15 to 500 mPa · s. In addition, the solution viscosity (mPa · s) of the polymer is based on a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer (eg, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). The value measured at 25 ° C. using an E-type rotational viscometer.
The polystyrene equivalent weight average molecular weight (Mw) of the polymer (A) measured by gel permeation chromatography (GPC) is preferably 500 to 100,000, and preferably 1,000 to 50,000. More preferred.

<Compound (B)>
The compound (B) in the present invention is a compound represented by the above formula (B).
Examples of X ¹ in the formula (B) include an N, N-diglycidylamino group, a 2,3-epoxycyclohexylmethoxycarbonyl group, a (meth) acryloyloxy group, and a group represented by the following formula. A group selected from these groups is preferred.

(In the above formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
“*” Indicates a bond. )
R ¹ in the above formula is preferably an alkyl group having 1 to 5 carbon atoms, and particularly preferably an ethyl group.
^X in the above formula ^2, Ru Oh a group represented by the following formula ^(X 2 -1) or ^(X 2 -2).

(In the formulas (X ² -1) and (X ² -2), R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
m1 and m2 are each independently an integer of 2 to 18,
n is an integer of 1 to 6, and “*” indicates a bond. )
M1 in the above formula (X ² -1) is preferably 2 to 12, and more preferably 2 to 6. R in the above formula (X ² -1) is preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. Therefore, the most preferable case of the formula (X ² -1) is a linear alkylene group having 2 to 5 carbon atoms.
M2 in the above formula (X ² -2) is preferably 2 to 5, and more preferably 2 or 5. R in the above formula (X ² -2) is preferably a hydrogen atom or a methyl group. In the above formula (X ² -2)

The unit represented by the formula is particularly preferably a 1,2-ethylene group, a 1,2-propylene group, or a 1,5-pentylene group. n is 1 to 3 when the unit is a 1,2-ethylene group or a 1,2-propylene group.
1 when the unit is a 1,5-pentylene group,
Each is preferred.
Specific examples of the compound (B) in the present invention include, for example, compounds represented by the following formulas, and it is preferable to use one or more selected from these compounds.

The ratio of the compound (B) used in the liquid crystal aligning agent of the present invention is preferably 0.5 to 60 parts by weight with respect to 100 parts by weight of the polymer (A). By setting the ratio of the compound (B) used to 100 parts by weight of the polymer (A) to 0.5 parts by weight, the rubbing resistance of the coating can be improved;
On the other hand, by limiting this value to 60 parts by weight or less, the liquid crystal alignment property of the liquid crystal alignment film is not impaired. The ratio of the compound (B) used is more preferably 1 to 50 parts by weight, still more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the polymer (A).

<Other ingredients>
Although the liquid crystal aligning agent of this invention contains the above polymers (A) and a compound (B) as an essential component, it may contain the other component as needed. Examples of such other components include compounds having at least one oxiranyl group in the molecule (excluding compounds corresponding to the above compound (B); hereinafter referred to as “oxiranyl compounds”), functional silane compounds, and oxidation. An inhibitor etc. can be mentioned.

[Oxiranyl compounds]
The oxiranyl compound can be blended in the liquid crystal aligning agent of the present invention in order to improve the adhesion between the liquid crystal aligning film and the substrate surface, the electrical properties of the liquid crystal aligning film, and the like.
The oxiranyl compound in the present invention is preferably a compound having at least two oxiranyl groups in the molecule, such as 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-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) E) cyclohexane, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidyl-aminomethylcyclohexane, N, N-diglycidyl- In addition to cyclohexylamine or the like, polyorganosiloxane having an oxiranyl group described in Patent Document 5 (International Publication No. 2009/096598) can be used.
When mix | blending these oxiranyl compounds with a liquid crystal aligning agent, it is preferable that the compounding ratio shall be 40 weight part or less with respect to 100 weight part of polymers (A), and it shall be 0.1-30 weight part. More preferred.

[Functional silane compounds]
The functional silane compound can be used for the purpose of improving the printability of the liquid crystal aligning agent. Examples of such functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl). ) -3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3- Aminopropyltrimethoxysilane, N-triethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-trimethoxysilyl -3,6- Methyl azananoate, N-benzyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, glycidoxymethyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycid And xylpropyltrimethoxysilane.
When these functional silane compounds are blended in the liquid crystal aligning agent, the blending ratio is preferably 2 parts by weight or less with respect to 100 parts by weight of the polymer (A), and is 0.02 to 0.2 parts by weight. More preferably.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is preferably constituted by dissolving the polymer (A) and the compound (B), and other components optionally blended as necessary, in an organic solvent.
Examples of the organic solvent used in the liquid crystal aligning agent of the present invention include 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, methyl methoxypropionate, ethyl ethoxypropionate, 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, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, Examples thereof include ethylene carbonate and propylene carbonate, and it is preferable to use one or more selected from these.

The solid content concentration in the liquid crystal aligning agent of the present invention (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) is appropriately selected in consideration of viscosity, volatility, and the like. The range is preferably 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface as described later, and preferably heated to form a film that is a liquid crystal alignment film or a film that becomes a liquid crystal alignment film. When the solid content concentration is less than 1% by weight, the film thickness of this coating becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by weight, the film thickness of the coating becomes excessive and a good liquid crystal alignment film cannot be obtained, and the viscosity of the liquid crystal aligning agent increases and the coating characteristics are increased. This is because there is a concern that it will be inferior.
The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spinner method is used, the 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 thereby 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 thereby the solution viscosity is in the range of 3 to 15 mPa · s.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal aligning film of a liquid crystal display element can be formed using the above liquid crystal aligning agent of this invention.
The driving method of the liquid crystal display element to which the liquid crystal aligning agent of the present invention is applied is not particularly limited. For example, to a liquid crystal display element such as a TN type, STN type, IPS type, FFS type, VA type, MVA type, and PSA type. Can be applied. However, since the liquid crystal display device of the present invention is excellent in rubbing resistance, it can be applied to liquid crystal display elements of TN type, STN type, IPS type, FFS type and the like that require a rubbing treatment step for forming a liquid crystal alignment film. This is preferable in that the effects of the invention can be maximized.
A liquid crystal display element can be manufactured, for example, through the following steps using the liquid crystal aligning agent of the present invention.
(1) Film formation process (essential)
(2) Rubbing process (optional)
(3) Liquid crystal cell construction process (essential)
(4) Polarizing plate bonding process (essential)
Hereafter, each said process is demonstrated in order.

(1) Film formation process In a film formation process, the liquid crystal aligning film of this invention is apply | coated on a board | substrate, and this is then heated, and a film is formed on a board | substrate.
As the substrates, two substrates having and without electrodes having the following configuration are used as a pair depending on the driving method.
TN type, STN type, VA type, MVA type or PSA type: Two substrates of a substrate provided with a patterned transparent conductive film are used as a pair, and the formation surface of the transparent conductive film of each substrate is used as a coating surface.
IPS type or FFS type: A substrate having an electrode using a pair of a substrate provided with a pair of electrodes made of a transparent conductive film or a metal film patterned in a comb shape and a counter substrate not provided with an electrode The electrode forming surface and one surface of the counter substrate are used as the coating surface.
Examples of the material constituting the substrate include glass such as float glass and soda glass; plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly (alicyclic olefin).
As a material constituting the transparent conductive film, for example, a NESA film (registered trademark of US PPG) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. Can be used. In order to obtain a patterned transparent conductive film, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, a method of using a mask having a desired pattern when forming a transparent conductive film, etc. be able to.
Examples of the material constituting the metal film include chromium.

Prior to applying the liquid crystal aligning agent to the substrate, in order to further improve the adhesion between the substrate surface and / or the transparent conductive film and the coating, a functional silane compound or a functional titanium compound is formed on the coating forming surface of the substrate. It is also possible to perform a pretreatment to apply the above in advance.
The liquid crystal aligning agent of the present invention is preferably applied on the application surface of such a substrate by an offset printing method, a spin coating method, a roll coater method or an ink jet printing method. After the application, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied alignment agent. The pre-baking temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 40 to 100 ° C. The pre-bake time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Thereafter, a firing (post-baking) step is carried out for the purpose of completely removing the solvent and, if necessary, for thermal imidization of the amic acid structure present in the polymer. The firing temperature (post-bake temperature) at this time is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes.
Thus, the film thickness of the formed film is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

(2) Rubbing treatment step This rubbing treatment step is optional depending on the driving method.
In the case of manufacturing a TN type, STN type, IPS type, or FFS type liquid crystal display element, the rubbing treatment is essential. On the other hand, when a VA liquid crystal display element is manufactured, the film formed in the step (1) can be used as a liquid crystal alignment film as it is, but a rubbing treatment may optionally be performed. When manufacturing a PSA type liquid crystal display element, the film formed in the above step (1) may be used as a liquid crystal alignment film as it is, but the tilting of liquid crystal molecules is controlled and the alignment division is performed in a simple manner. For the purpose of performing, a low-strength rubbing process may be performed.
The rubbing treatment can be performed, for example, by rubbing the coating film in a certain direction using a roll wound with a cloth made of fibers such as nylon, rayon, and cotton.

(3) Liquid crystal cell construction process When manufacturing a TN type, STN type, IPS type, FFS type, or VA type liquid crystal display element, a pair of substrates on which the liquid crystal alignment film is formed as described above are used as a liquid crystal. A liquid crystal cell can be manufactured by disposing a liquid crystal in a gap that is oppositely disposed so that the alignment films face each other. On the other hand, when a PSA liquid crystal display element is manufactured, a liquid crystal cell can be manufactured by disposing a liquid crystal composition containing a liquid crystal and a photopolymerizable compound in a gap between a pair of substrates.
In order to arrange the liquid crystal or the liquid crystal composition in the gap between the substrates, for example, the following method can be used;
1st method: After bonding the peripheral part of a pair of board | substrate arrange | positioned facing each other so that a liquid crystal aligning film may oppose with a sealing material, a liquid crystal or a liquid crystal composition in the cell gap divided by the liquid crystal aligning film surface and the sealing agent A method of injecting and filling an object, and then sealing the injection hole, or a second method: a predetermined position on one of two (two) substrates on which a liquid crystal alignment film is formed, for example, ultraviolet After applying a photo-curable sealing material and dropping a liquid crystal or a liquid crystal composition at predetermined locations on the surface of the liquid crystal alignment film, the other substrate is bonded and pressed so that the liquid crystal alignment film is opposed to the liquid crystal or A method of spreading the liquid crystal composition over the entire surface of the substrate and then irradiating the entire surface of the substrate with ultraviolet light to cure the sealant (ODF (One Drop Fill) method).
In any of the above methods, the liquid crystal cell produced as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase, and then gradually cooled to room temperature, so that the flow alignment at the time of filling the liquid crystal is achieved. It is desirable to remove.

In the above, examples of the liquid crystal disposed in the cell gap include nematic liquid crystal and smectic liquid crystal. Of these, nematic liquid crystal is preferable, for example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, and bicyclooctane. Type liquid crystal, cubane type liquid crystal and the like can be preferably used. Further, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck & Co., Inc.). A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.
In the case of manufacturing a PSA type liquid crystal display element, the liquid crystal cell is further irradiated with light while the liquid crystal is activated by applying a voltage between the conductive films of the pair of substrates. The voltage applied here can be, for example, 5 to 50 V direct current or alternating current. Moreover, as light to irradiate, the ultraviolet-ray and / or visible light which contain light with a wavelength of 150-800 nm can be used, for example, However, The ultraviolet-ray containing light with a wavelength of 300-400 nm is preferable. As a light source of irradiation light, 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 excimer laser, or the like can be used. In addition, the ultraviolet rays in the above preferable wavelength region can be obtained by means of using a light source in combination with, for example, a filter diffraction grating. The irradiation dose of light, preferably less than 1,000 J / ^{m 2} or more 200,000 J / ^{m 2,} more preferably from 1,000~100,000J / ^{m 2.}

(4) Polarizing plate bonding step The polarizing plate is bonded to the outer surface of the liquid crystal cell constructed above, whereby the liquid crystal display element of the present invention can be obtained. As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called an “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned. When the rubbing treatment is performed on the coating film, the two substrates are arranged to face each other so that the rubbing directions in each coating film are at a predetermined angle, for example, orthogonal or antiparallel.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
The imidation ratio of the imidized polymer of polyamic acid in the synthesis examples described below was measured as follows.
[Imidation rate of imidized polymer]
The imidized polymer solution obtained in each synthesis example was poured into pure water, and the resulting precipitate was sufficiently dried at room temperature under reduced pressure, then dissolved in deuterated dimethyl sulfoxide, and tetramethylsilane as a reference material at room temperature. ¹ H-NMR was measured at ¹ . From the obtained ¹ H-NMR spectrum, the imidation ratio [%] was determined by the following mathematical formula (1).
Imidation ratio [%] = (1-A ¹ / A ² × α) × 100 (1)
(In Formula (1), A ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, A ² is a peak area derived from other protons, and α is a precursor of a polymer (polyamic acid). The number ratio of other protons to one proton of NH group in)

<Synthesis of polymer (A)>
Synthesis Example 1 (Synthesis of polyamic acid)
196 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 200 g of 4,4-oxydianiline as diamine are dissolved in 2,244 g of N-methyl-2-pyrrolidone (NMP). The reaction was carried out at room temperature for 6 hours. The reaction mixture was then poured into a large excess of methanol to precipitate the reaction product. The recovered precipitate was washed with methanol and then dried at 40 ° C. under reduced pressure for 15 hours to obtain 336 g of polyamic acid (PA-1).

Synthesis Example 2 (Synthesis of imidized polymer of polyamic acid)
224 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 108 g of p-phenylenediamine as diamine are dissolved in 2,988 g of NMP, reacted at 60 ° C. for 4 hours, and a polyamic acid solution is obtained. Obtained. Next, 3,320 g of NMP was added to the obtained polyamic acid solution, 395 g of pyridine and 305 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 15% by weight of an imidized polymer (PI-1) having an imidization ratio of 88%.

Synthesis Example 3 (Synthesis of polyamic acid ester)
108 g of p-phenylenediamine and 197 g of pyridine were weighed and dissolved in 7,498 g of NMP to prepare a diamine solution. While stirring this diamine solution, 297 g of a compound represented by the following formula was added thereto, followed by stirring in an ice bath for 4 hours to obtain a polyamic acid ester solution. The obtained polyamic acid ester solution was poured into 44,988 g of water with stirring, and the deposited precipitate was collected by filtration. This precipitate was washed with 44,988 g of water once and with 7,498 g of ethanol three times in sequence, and then dried to obtain 232 g of a powdery polyamic acid ester (PAS-1).

Example 1
[Preparation of liquid crystal aligning agent]
1.000 g of the polyamic acid (PA-1) obtained in Synthesis Example 1 as the polymer (A) and the compound represented by the above formula (B1-2) as an additive (compound (B1-2)) 0 .010 g was weighed, dissolved in 24.240 g of NMP, and then filtered through a filter having a pore size of 1.0 μm to prepare a liquid crystal aligning agent.
[Evaluation of liquid crystal aligning agent]
(1) Formation of Liquid Crystal Alignment Film The liquid crystal aligning agent prepared above was applied onto the ITO forming surface of the glass substrate with ITO by spin coating, prebaked on an 80 ° C. hot plate for 1 minute, and then further heated to 230 ° C. After baking for 15 minutes in a clean oven, a coating film having an average film thickness of 100 nm was formed on the substrate. A liquid crystal alignment film was formed on the substrate by subjecting this coating film to a rubbing treatment under the conditions of a roller rotation speed of 1,000 rpm, a stage moving speed of 20 mm / second, and a hair foot pressing length of 0.4 mm.
(2) Evaluation of liquid crystal orientation (measurement of refractive index anisotropy)
About the liquid crystal aligning film formed above, the magnitude | size of refractive index anisotropy was evaluated using the Schott Moritex Co., Ltd. liquid crystal aligning film test | inspection apparatus (product name: RayScan).
The evaluation results are shown in the table below.
It can be evaluated that the higher the refractive index anisotropy value is, the better the liquid crystal orientation is. If this value is 0.020 or more, it is believed that the liquid crystal orientation is good.
(2) Evaluation of rubbing resistance The liquid crystal alignment film formed above was further subjected to 20 rubbing treatments under the same conditions as in “(1) Formation of liquid crystal alignment film” (total number of rubbing treatments 21 Times). The number of scraps (attachments) in the range of 0.1 mm × 0.1 mm was examined using a polarizing microscope with the magnification set to 200 times for the liquid crystal alignment film after the treatment. When the number of scraps was less than 10, the rubbing resistance was “good”, and when the number was 10 or more, the rubbing resistance was “bad”.
The evaluation results are shown in the table below.

Examples 2-4
In “[Preparation of liquid crystal aligning agent]” in Example 1 above, a liquid crystal aligning agent was prepared and evaluated in the same manner as in Example 1 except that the amounts of additives used were as shown in the table below. It was.
The abbreviation of compound (B) means a compound represented by the above formula having the abbreviation as a formula symbol.
The evaluation results are shown in the table below.

Example 5
[Preparation of liquid crystal aligning agent]
6.667 g of a solution containing 15% by weight of the imidized polymer (PI-1) obtained in Synthesis Example 2 as the polymer (A) (to 1.000 g in terms of imidized polymer PI-1) Corresponding amount) was added 0.010 g of compound (B1-2) as an additive, and NMP was further added to obtain a solution having a solid content of 4.0% by weight. Next, this solution was filtered through a filter having a pore size of 1.0 μm to prepare a liquid crystal aligning agent.
[Evaluation of liquid crystal aligning agent]
The evaluation was performed in the same manner as “[Evaluation of liquid crystal alignment agent]” in Example 1 except that the liquid crystal alignment agent prepared above was used.
The evaluation results are shown in the table below.

Examples 6 to 10 and Comparative Examples 1 to 4 and 6
In “[Preparation of liquid crystal aligning agent]” in Example 1 above, the same manner as in Example 1 except that the type of polymer (A), the type of additive and the amount used were as shown in the table below. A liquid crystal aligning agent was prepared and evaluated.
The evaluation results are shown in the table below.

Comparative Example 5
Example 5 except that 0.04 g of 4,4′-bis (N, N-diglycidylamino) diphenylmethane (R-1) was used as an additive in “[Preparation of liquid crystal aligning agent]” in Example 5 above. In the same manner as in No. 5, a liquid crystal aligning agent was prepared and evaluated.
The evaluation results are shown in the table below.

The abbreviations of the additives in the above table (described in the “kind” column of the additives) mean compounds represented by the above formula having the abbreviation as a formula symbol. However, the abbreviation (R-1) in the comparative example means 4,4′-bis (N, N-diglycidylamino) diphenylmethane. The compound of this comparative example is an additive widely used in the prior art for the purpose of improving the rubbing resistance of the liquid crystal alignment film.
The advantages of the present invention will become apparent from the above examples.
The compound (B1-2) which is the predetermined compound (B) of the present invention exhibits a rubbing resistance superior to R-1 while exhibiting liquid crystal orientation equivalent to R-1 in a small addition amount (implementation) Comparison between Example 1 and Comparative Example 1). In a large amount added, it is obvious that the rubbing resistance is excellent, and the liquid crystal orientation exceeds R-1 (comparison between Example 3 and Comparative Example 3).
The above-described effects expressed by the compound (B1-2) are appropriate regardless of the type of the polymer (A) used (comparison between Examples 5 and 6 and Comparative Examples 5 and 6).
Furthermore, in addition to the compound (B1-2), it was confirmed that the same effect was exhibited if the compound (B) satisfies the predetermined requirements of the present invention (comparison between Examples 7 to 10 and Comparative Example 3). ).
The mechanism in which the predetermined compound (B) of the present invention achieves both good liquid crystal alignment and high rubbing resistance, which were in a trade-off relationship in the prior art, is not clear. I guess so.
That is, by introducing a flexible alkylene group into the main chain of the additive that forms a cross-linked structure, the liquid crystal alignment film to be formed has appropriate stretchability, which results in excellent rubbing resistance. It is considered that it is easy to impart good liquid crystal orientation by rubbing treatment.

Claims (7)

Polymer (A) and compound (B) represented by the following formula (B)
Liquid crystal aligning agent characterized by containing.

(In Formula (B), two X ^{1 s} each independently represent a monovalent organic group containing a group selected from a group having an oxiranyl structure, a group having an oxetanyl structure, and a group having a (meth) acryloyloxy group). Group,
X ² is a group represented by the following formula (X ² -1) or (X ² -2))

(In the formulas (X ² -1) and (X ² -2), R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
m1 and m2 are each independently an integer of 2 to 18,
n is an integer from 1 to 6 and
“*” Indicates a bond. ) Two X ¹ in the above formula (B) are each independently an N, N-diglycidylamino group, a 2,3-epoxycyclohexylmethoxycarbonyl group, a (meth) acryloyloxy group and a group represented by the following formula: it is a group selected from the liquid crystal alignment agent according to claim 1.

(In the above formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
“*” Indicates a bond. )   The liquid crystal aligning agent of Claim 1 or 2 whose content rate of a compound (B) is 0.5-60 weight part with respect to 100 weight part of polymers (A).   3. The liquid crystal aligning agent according to claim 1, wherein the polymer (A) is at least one selected from the group consisting of a polyamic acid, an imidized polymer of a polyamic acid, and a polyamic acid ester. The polymer (A) is
2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride and 1,2, The liquid crystal aligning agent according to claim 4 , which is a polymer having a structure derived from at least one compound selected from the group consisting of 3,4-cyclobutanetetracarboxylic dianhydride. And wherein the formed liquid crystal alignment agent according to any one of claims 1 to 5 liquid crystal alignment film. A liquid crystal display element comprising the liquid crystal aligning agent according to claim 6 .