JP5672762B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent suitable as a material for forming a liquid crystal aligning film, a liquid crystal aligning film formed from the liquid crystal aligning agent, and a liquid crystal display element including the liquid crystal aligning film.

  Liquid crystal display elements have advantages such as low power consumption and easy miniaturization and flattening, and are widely used from small liquid crystal display devices such as mobile phones to large screen liquid crystal display devices such as liquid crystal televisions. Yes.

  As a display mode of the liquid crystal display device, a Twisted Nematic type (TN type), a Super Twisted Nematic type (STN type), an In-Plane Switching type (IPS type), or a Vertical Alignment type (in accordance with a change in the alignment state of liquid crystal molecules. A liquid crystal display element having a liquid crystal cell such as VA type is known. In any display mode, since the alignment state of the liquid crystal molecules is controlled by the liquid crystal alignment film, the characteristics of the liquid crystal alignment film and the liquid crystal alignment agent used as the material of the liquid crystal alignment film are the characteristics of the liquid crystal display element. Affects the expression of.

  As materials for such a liquid crystal aligning agent, for example, Patent Documents 1 to 6 disclose resin materials such as polyamic acid, polyimide, polyamide, and polyester, and are particularly formed from a liquid crystal aligning agent using polyamic acid or polyimide as a material. The liquid crystal alignment film has excellent affinity with liquid crystal, heat resistance, mechanical strength, and the like, and is applied to many liquid crystal display elements.

  However, in recent years, the range of use of liquid crystal display elements has been expanded, and there is a need for liquid crystal display elements that do not deteriorate display quality even during long-term continuous driving. In conventional liquid crystal display elements made of polyamic acid or polyimide, In the continuous driving for a long time, the liquid crystal alignment film is deteriorated by heat or light, which may cause deterioration of electrical characteristics, alignment failure of liquid crystal molecules, and the like. In order to solve this, a technique using a liquid crystal aligning agent containing a lot of polyfunctional epoxy compounds has been developed (see Japanese Patent No. 3799700 and Japanese Patent Application Laid-Open No. 2008-299318).

  On the other hand, a substrate containing defects such as pinholes and uneven coating in the liquid crystal alignment film manufacturing process is peeled off for reuse (hereinafter referred to as “rework”). In this rework, the peelability of the liquid crystal alignment film from the substrate is required. However, when a liquid crystal aligning agent containing a large amount of the above polyfunctional epoxy is used, there is a risk that the releasability of the liquid crystal aligning film during reworking may be reduced due to the crosslinking reaction of the epoxy groups during baking.

  Under these circumstances, even when driven continuously for a long time, it is desired to develop a liquid crystal alignment film that suppresses deterioration of display quality due to deterioration of electrical characteristics and the like and can be easily peeled off during rework. .

JP-A-4-153622 JP 60-107020 A JP 56-91277 A US Pat. No. 5,928,733 Japanese Patent Laid-Open No. 62-165628 Japanese Patent Laid-Open No. 11-258605 Patent 3799700 JP 2008-299318 A

  The present invention has been made based on the circumstances as described above, and its purpose is to suppress deterioration of display quality due to deterioration of electrical characteristics, etc., even when continuously driven for a long time, and It is an object to provide a liquid crystal alignment film that can be easily peeled off during rework, a liquid crystal alignment agent suitable as a material for forming the alignment film, and a liquid crystal display device including the liquid crystal alignment film.

（式（Ｉ）中、Ｒ^Ａは単結合又は炭素数１〜４のアルカンジイル基である。Ｒ^Ｂは２価の鎖状炭化水素基、２価の脂環式炭化水素基、２価の芳香族基、２価の複素環式基、又はこれらを組み合わせた基である。ｎは０又は１の整数である。） The invention made to solve the above problems is
[A] At least one polymer selected from the group consisting of polyamic acid and polyimide (hereinafter sometimes referred to as polymer [A]), and [B] an imide represented by the following formula (I) Ring-containing epoxy compound (hereinafter sometimes referred to as epoxy compound [B])
It is a liquid crystal aligning agent containing.

(In the formula (I), R ^A is a single bond or an alkanediyl group having 1 to 4 carbon atoms. R ^B is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent group. (Aromatic group, divalent heterocyclic group, or a combination thereof. N is an integer of 0 or 1.)

  Since the liquid crystal aligning agent contains the specific polymer [A] and the epoxy compound [B], a decrease in display quality due to deterioration of electrical characteristics or the like is suppressed, and liquid crystal alignment that is easy to peel off during rework A film can be formed.

（式（Ｉ−１）及び式（Ｉ−２）中、Ｒ^Ａは上記式（Ｉ）と同義である。Ｒ^１、Ｒ^２及びＲ^３は、それぞれ独立して、−Ｏ−、−ＣＯＯ−、−ＯＣＯ−を含んでいてもよい炭素数１〜２０の直鎖状又は分岐状のアルキル基である。また、Ｒ^１とＲ^２とが、又はＲ^１とＲ^２とＲ^３とが、互いに連結して、水素原子の一部又は全部が置換されていてもよい環構造を形成してもよい。ｎは０又は１の整数である。） The above formula (I) is preferably at least one selected from the group consisting of compounds represented by the following formula (I-1) and formula (I-2).

(In formula (I-1) and formula (I-2), R ^A has the same meaning as in formula (I) above. R ¹ , R ² and R ³ are each independently —O—, —COO. A linear or branched alkyl group having 1 to 20 carbon atoms which may contain-or -OCO-, and R ¹ and R ² , or R ¹ , R ² and R ³ are And may be linked to each other to form a ring structure in which some or all of the hydrogen atoms may be substituted. N is an integer of 0 or 1.)

  By using the above formula (I) as a specific compound, it is possible to form a liquid crystal alignment film in which the deterioration of display quality due to the deterioration of electrical characteristics or the like is further suppressed and the rework in peeling is easier.

  The polymer [A] is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2 , 4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-using a tetracarboxylic dianhydride containing at least one selected from the group consisting of dianhydrides The polyamic acid synthesized in this manner and at least one selected from the group consisting of polyimides obtained by dehydrating and ring-closing this polyamic acid are preferable. Desirable characteristics are further expressed by using a polymer [A] synthesized using such a specific compound as tetracarboxylic dianhydride.

R ^{A in the} above formula (I) is preferably a methanediyl group. In the above formulas (I-1) and (I-2), R ¹ and R ² are connected to each other to form a benzene ring in which some or all of the hydrogen atoms may be substituted. It is preferable. When the epoxy compound [B] has the above specific structure, the electrical characteristics and the releasability in rework can be further improved.

  The liquid crystal display element of this invention is equipped with the liquid crystal aligning film formed from the said liquid crystal aligning agent. The liquid crystal display element can be suitably applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, liquid crystal televisions, etc. Used in display devices.

（式（Ｉ）中、Ｒ^Ａは単結合又は炭素数１〜４のアルカンジイル基である。Ｒ^Ｂは２価の鎖状炭化水素基、２価の脂環式炭化水素基、２価の芳香族基、２価の複素環式基、又はこれらを組み合わせた基である。ｎは０又は１の整数である。） [A] A polymer composition containing at least one polymer selected from the group consisting of polyamic acid and polyimide, and [B] an imide ring-containing epoxy compound represented by the following formula (I).

(In the formula (I), R ^A is a single bond or an alkanediyl group having 1 to 4 carbon atoms. R ^B is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent group. (Aromatic group, divalent heterocyclic group, or a combination thereof. N is an integer of 0 or 1.)

  The said polymer composition can be conveniently used as components, such as a liquid crystal aligning agent for forming a liquid crystal aligning film. Moreover, the film | membrane formed from the said polymer composition can also be used as an insulating film for electronic materials.

  According to the present invention, it is possible to form a liquid crystal alignment film that suppresses deterioration of display quality due to deterioration of electrical characteristics and the like and can be easily peeled off during rework. The liquid crystal display element can be suitably applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, liquid crystal televisions, etc. Used in display devices.

  Hereinafter, embodiments of the present invention will be described in detail.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of this invention contains polymer [A] and an epoxy compound [B]. Since the liquid crystal aligning agent contains the specific polymer [A] and the epoxy compound [B], a decrease in display quality due to deterioration of electrical characteristics or the like is suppressed, and liquid crystal alignment that is easy to peel off during rework A film can be formed. Moreover, the said liquid crystal aligning agent may contain arbitrary components, unless the effect of this invention is impaired. Hereinafter, the polymer [A], the epoxy compound [B], and optional components will be described in detail.

<Polymer [A]>
The polymer [A] contained in the liquid crystal aligning agent of the present invention is at least one polymer selected from the group consisting of polyamic acid and polyimide. Hereinafter, the polyamic acid and the polyimide will be described in detail.

[Polyamic acid]
A polyamic acid is obtained by reacting a tetracarboxylic dianhydride and a diamine compound.

  Examples of tetracarboxylic dianhydrides include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and the like. Besides these, tetracarboxylic dianhydrides described in Japanese Patent Application No. 2009-157556 can be used. These tetracarboxylic dianhydrides can be used alone or in combination of two or more.

  Examples of the aliphatic tetracarboxylic dianhydride include 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 -1,2-dicarboxylic acid Water, 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 and the like.

  Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride.

  Of these tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides are preferred, 2,3,5-tricarboxycyclopentylacetic dianhydride, 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, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1, 3-dione, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and pyromellitic dianhydride are more preferable, and 2,3,5-tricarboxycyclopentylacetic acid dianhydride is particularly preferable. Desirable characteristics are further expressed by using a polymer [A] synthesized using such a specific compound as tetracarboxylic dianhydride.

  The preferred amount of tetracarboxylic dianhydride is preferably 10 mol% or more, more preferably 20 mol% or more, and 2,3,5-tricarboxycyclopentylacetic acid, based on the total tetracarboxylic dianhydride. Dianhydride, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1, It is particularly preferred to use only one or more selected from the group consisting of 3-dione, 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

  Examples of the diamine compound include aliphatic diamine, alicyclic diamine, diaminoorganosiloxane, and aromatic diamine. In addition to these, diamine compounds described in Japanese Patent Application No. 2009-157556 can be used. These diamine compounds can be used alone or in combination of two or more.

  Examples of the aliphatic diamine include 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.

  Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane.

  Examples of the aromatic diamine include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 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-pheny Diisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 3,4-diaminopyridine, 4,4′-bis (4-aminophenoxy) biphenyl, 3,6-diaminocarbazole, 2,6 -Diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, 1,4-bis- (4-amino) Phenyl) -piperazine, 3,5-diaminobenzoic acid, N-phenyl-3,6-diaminocarbazole, N, N′-bis (4-aminophenyl) -benzidine, N, N′-bis (4-aminophenyl) ) -N, N'-dimethylbenzidine, dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diamy Benzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecanoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2 , 5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy- 2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bi (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4 ′ -Trifluoromethylbenzoyloxy) 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, 2,4-diamino-N, - diallyl aniline, 4-amino-benzylamine, represented by a diamine compound with 3-amino benzylamine and the following formula (1), and the like.

  In the formula (1), X is an alkanediyl group having 1 to 3 carbon atoms, —O—, —COO— or —OCO—. a is 0 or 1; b is an integer of 0-2. c is an integer of 1-20.

In the above formula (1), as the C _c H _{2c + 1} group, for example, linear or branched, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group Decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group and the like.

  Examples of the diamine compound represented by the above formula (1) include compounds represented by the following formulas (1-1) to (1-5).

  In the above formula (1), it is preferable that a and b are not 0 at the same time.

  Of these diamine compounds, aromatic diamines and diaminoorganosiloxanes are preferable, and p-phenylenediamine, 4,4′-diaminodiphenylmethane, 2,2′-dimethyl-4,4′-diaminobiphenyl, and 3,6-bis. More preferred are (4-aminobenzoyloxy) cholestane, cholestanyl 3,5-diaminobenzoate, cholestanyloxy-2,4-diaminobenzene, and 1,3-bis (3-aminopropyl) -tetramethyldisiloxane.

[Synthesis of polyamic acid]
The ratio of the tetracarboxylic dianhydride and the diamine compound used in the polyamic acid synthesis reaction is such that the acid anhydride group of the tetracarboxylic dianhydride is 0 with respect to 1 equivalent of the amino group contained in the diamine compound. .2 equivalents to 2 equivalents are preferable, and 0.3 equivalents to 1.2 equivalents are more preferable.

  The synthesis reaction of the polyamic acid is preferably performed in an organic solvent. The reaction temperature is preferably −20 ° C. to 150 ° C., more preferably 0 ° C. to 100 ° C. The reaction time is preferably 0.1 hour to 24 hours, more preferably 0.5 hour to 12 hours.

  The organic solvent is not particularly limited as long as it can dissolve the synthesized polyamic acid. For example, an aprotic polar solvent, phenol and its derivatives, alcohols, ethers, halogenated hydrocarbons, hydrocarbons, etc. Is mentioned. These organic solvents may be used alone or in combination of two or more.

  Examples of the aprotic polar solvent include amides, ketones, esters, and other aprotic polar solvents.

  Examples of amides include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide and the like.

  Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  Examples of esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, γ-butyrolactone, isoamylpropio Nate, isoamyl isobutyrate and the like.

  Examples of other aprotic polar solvents include dimethyl sulfoxide, tetramethyl urea, hexamethyl phosphortriamide and the like.

  Examples of the phenol derivative include m-cresol, xylenol, halogenated phenol and the like.

  Examples of alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether. Can be mentioned.

  Examples of ethers include diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol di-i-propyl ether, ethylene glycol di-n-butyl ether, and ethylene glycol. Examples include monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, and diisopentyl ether.

  Examples of halogenated hydrocarbons include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, and the like.

  Examples of hydrocarbons include hexane, heptane, octane, benzene, toluene, xylene and the like.

  Of these organic solvents, aprotic polar solvents are preferable, and NMP and γ-butyrolactone are more preferable.

  As the usage-amount (a) of an organic solvent, it is 0.1 mass%-50 with respect to the total (a + b) of the total amount (b) of a tetracarboxylic dianhydride and a diamine compound, and the usage-amount (a) of an organic solvent. Mass% is preferred.

  The polyamic acid solution obtained after the reaction may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution. You may use for preparation of a liquid crystal aligning agent, after refine | purifying an acid. Examples of the method for isolating the polyamic acid include a method of pouring a reaction solution into a large amount of a poor solvent and drying a precipitate obtained under reduced pressure, and a method of distilling the reaction solution under reduced pressure using an evaporator. Examples of the method for purifying the polyamic acid include a method in which the isolated polyamic acid is dissolved again in an organic solvent and precipitated with a poor solvent, and a method in which the step of distilling off the organic solvent or the like with an evaporator is performed once or a plurality of times. .

  In synthesizing the polyamic acid, a terminal-modified polymer may be synthesized using an appropriate molecular weight regulator together with a tetracarboxylic dianhydride and a diamine compound. By using such a terminal-modified polymer, the applicability (printability) of the liquid crystal aligning agent can be further improved without impairing the effects of the present invention.

  Examples of molecular weight regulators include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like.

  Examples of the acid monoanhydride include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride, n-hexadecyl succinic acid. An anhydride etc. are mentioned.

  Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine and the like.

  Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

  As a usage-amount of a molecular weight modifier, 20 mass parts or less are preferable with respect to a total of 100 mass parts of tetracarboxylic dianhydride and diamine, and 10 mass parts or less are more preferable.

[Polyimide]
The polyimide can be produced by dehydrating and ring-closing the amic acid structure of the polyamic acid to imidize it.

  The polyimide may be a completely imidized product in which all of the amic acid structure of the precursor polyamic acid has been dehydrated and cyclized, and only a part of the amic acid structure may be dehydrated and cyclized to form an amic acid structure and an imide. It may be a partially imidized product in which a ring structure coexists. Here, a part of the imide ring may be an isoimide ring.

The imidation ratio of polyimide is preferably 30% or more, and more preferably 40% to 99%. The imidation ratio is a percentage of the number of imide ring structures to the total number of polyimide amic acid structures and imide ring structures. The imidation rate was determined by adding a polyimide solution to pure water, drying the obtained precipitate under reduced pressure at room temperature, dissolving it in deuterated dimethyl sulfoxide, and using tetramethylsilane as a reference substance at ¹ H at room temperature. It calculated | required by the type | formula represented by following formula (2) from the < ¹ > H-NMR spectrum obtained by measuring -NMR.

Imidation ratio (%) = {1- (A ¹ / A ² ) × α} × 100 (2)

In formula (2), A ¹ is the peak area (10 ppm) derived from the proton of the NH group. A ² is the peak area derived from other protons. α is the number ratio of other protons to one NH group proton in the polyamic acid.

  As a method for synthesizing polyimide, for example, (i) a method in which polyamic acid is heated, (ii) polyamic acid is dissolved in an organic solvent, a dehydrating agent and a dehydrating ring-closing catalyst are added to this solution, and heating is performed as necessary. Examples thereof include a method based on a dehydration ring-closing reaction of a polyamic acid such as a method (hereinafter sometimes referred to as “method (ii)”). Of these, method (ii) is preferred.

  Examples of the dehydrating agent in the method (ii) include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride.

  Although the usage-amount of a dehydrating agent is suitably selected by the desired imidation rate, 0.01 mol-20 mol are preferable with respect to 1 mol of the amic acid structure of a polyamic acid.

  Examples of the dehydration ring closure catalyst in the method (ii) include tertiary amines such as pyridine, collidine, lutidine, and triethylamine.

  The amount of the dehydration ring closure catalyst used is preferably 0.01 mol to 10 mol with respect to 1 mol of the dehydrating agent contained.

  Examples of the organic solvent used in the method (ii) include organic solvents similar to those exemplified as those used for the synthesis of polyamic acid.

  The reaction temperature in method (ii) is preferably 0 ° C to 180 ° C, more preferably 10 ° C to 150 ° C. The reaction time is preferably 1.0 hour to 120 hours, more preferably 2.0 hours to 30 hours. By setting the reaction conditions in the above range, the dehydration ring-closing reaction proceeds sufficiently, and the molecular weight of the resulting polyimide can be made appropriate.

  In the method (ii), a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution, it may be used for the preparation of the liquid crystal aligning agent. You may use for preparation of an agent, or you may use for preparation of a liquid crystal aligning agent, after purifying the isolated polyimide. The method for removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution can be carried out according to a known method, and examples thereof include the same methods as those exemplified as the polyamic acid isolation method and purification method.

  The solution viscosity in a 10 mass% solution of the polymer [A] obtained as described above is preferably 20 mPa · s to 800 mPa · s, and more preferably 30 mPa · s to 500 mPa · s. The solution viscosity (mPa · s) of the polymer is a value measured at 25 ° C. using an E-type rotational viscometer for a polymer solution having a concentration of 10% by mass prepared using γ-butyrolactone or NMP.

<Epoxy compound [B]>
The epoxy compound [B] contained in the liquid crystal aligning agent of the present invention is an imide ring-containing epoxy compound represented by the above formula (I).

In the above formula (I), R ^A is a single bond or an alkanediyl group having 1 to 4 carbon atoms. R ^B is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent aromatic group, a divalent heterocyclic group, or a combination thereof. n is an integer of 0 or 1.

  Examples of the alkanediyl group having 1 to 4 carbon atoms include a methanediyl group, an ethanediyl group, a propanediyl group, and a butanediyl group. Of these, a single bond or a methanediyl group is preferred.

  The formula (I) is preferably at least one selected from the group consisting of the compounds represented by the formula (I-1) and the formula (I-2). By using the above formula (I) as a specific compound, it is possible to form a liquid crystal alignment film in which the deterioration of display quality due to the deterioration of electrical characteristics or the like is further suppressed and the rework in peeling is easier.

In the above formulas (I-1) and (I-2), R ^A has the same meaning as in the above formula (I). R ¹ , R ² and R ³ are each independently a linear or branched alkyl group having 1 to 20 carbon atoms which may contain —O—, —COO— or —OCO—. R ¹ and R ² , or R ¹ , R ^2, and R ³ may be connected to each other to form a ring structure in which some or all of the hydrogen atoms may be substituted. n is an integer of 0 or 1.

  Examples of the linear or branched alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, Examples include lauryl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group. Of these, a methyl group, an ethyl group, and a propyl group are preferable.

R ¹ , R ² and R ³ in the above formulas (I-1) and (I-2) are the same as R ¹ and R ² , or R ¹ , R ² and R ³ are connected to each other. A ring structure in which some or all of the hydrogen atoms may be substituted may be formed. Examples of the ring structure include an aromatic ring, an aliphatic ring, a heterocyclic ring, a condensed ring, and a ring obtained by combining these. Among these, an aromatic ring is preferable, and a benzene ring and a naphthalene ring are more preferable.

  Examples of the substituent of the ring structure which may be substituted include a halogen atom, a hydroxyl group, a nitro group, a cyano group, an alkyl group, a carboxyl group, a cycloalkyl group, an aryl group, an alkoxy group, an acyl group, an acyloxy group, and an alkoxy group. A carbonyl group, a cyanoalkyl group, a haloalkyl group, etc. are mentioned. Among these, a halogen atom, an alkyl group, a cyanoalkyl group, and an alkoxy group are preferable, and a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a cyanomethyl group, and a methoxy group are more preferable.

  N in the above formulas (I-1) and (I-2) is an integer of 0 or 1. n is preferably 0.

R ^{A in the} above formula (I) is preferably a methanediyl group. In the above formulas (I-1) and (I-2), R ¹ and R ² are connected to each other to form a benzene ring in which some or all of the hydrogen atoms may be substituted. Is particularly preferred. When the epoxy compound [B] has the above specific structure, the electrical characteristics and the releasability in rework can be further improved.

  Examples of the compounds represented by the above formulas (I-1) and (I-2) include the following formulas (I-1-1) to (I-1-16) and (I-2-1) to ( And a compound represented by I-2-14).

  Of the above formulas (I-1-1) to (I-1-16) and (I-2-1) to (I-2-14), (I-1-1), (I-1- 4), (I-1-15), (I-1-16), and (I-2-6) are particularly preferable, and (I-1-4) and (I-2-6) are most preferable.

  In addition, the epoxy group in Formula (I) may be substituted. Examples of the substituent include a halogen atom, a hydroxyl group, a nitro group, a cyano group, an alkyl group, a carboxyl group, a cycloalkyl group, an aryl group, an alkoxy group, an acyl group, an acyloxy group, an alkoxycarbonyl group, a cyanoalkyl group, and a haloalkyl group. Is mentioned.

  The method for synthesizing the epoxy compound [B] is not particularly limited, and can be performed by combining conventionally known methods. Moreover, a commercial item can also be utilized.

  As a content rate of an epoxy compound [B], 0.1 mass part-50 mass parts are preferable with respect to 100 mass parts of polymers [A], 1 mass part-40 mass parts are more preferable, and 3 mass parts- 30 parts by mass is particularly preferred. When the content ratio of the epoxy compound [B] is in the above range, it is possible to provide a liquid crystal alignment film that forms a liquid crystal display element with low deterioration of electrical characteristics and high display quality even when driven for a long time, and The liquid crystal aligning agent with favorable peelability in the rework of the film | membrane formed can be provided.

<Optional component>
Examples of the optional component include a functional silane compound.

[Functional silane compounds]
The functional silane compound can be used for the purpose of improving the adhesion of the liquid crystal alignment film to be formed to the substrate surface.

  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-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltri Methoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7 Triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxy Silyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, methyl 9-trimethoxysilyl-3,6-diazananoate, methyl 9-triethoxysilyl-3,6-diazananoate N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltri Ethoxysilane, 2-glycidoxyethyltrimethoxy Run, 2-glycidoxyethyl triethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, and the like.

  As a usage-amount of a functional silane compound, 2 mass parts or less are preferable with respect to 100 mass parts of polymers [A], and 0.02 mass part-0.2 mass part are more preferable.

<Method for preparing liquid crystal aligning agent>
As described above, the liquid crystal aligning agent contains the polymer [A] and the epoxy compound [B] and optionally contains optional components. Preferably, each component is dissolved in an organic solvent. Prepared as a composition.

  Examples of the organic solvent include NMP, 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, di Examples include ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, and propylene carbonate. These organic solvents may be used alone or in combination of two or more.

  The solid content concentration of the liquid crystal aligning agent of the present invention, that is, the ratio of the mass of all components other than the solvent in the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent is selected in consideration of viscosity, volatility, etc. 1 mass%-10 mass% are preferable. When the solid content concentration is less than 1% by mass, the film thickness of the liquid crystal alignment film formed from the liquid crystal alignment agent is too small, and a good liquid crystal alignment film may not be obtained. On the other hand, if the solid content concentration exceeds 10% by mass, the film thickness of the coating film may be excessive and a good liquid crystal alignment film may not be obtained. There may be a shortage. The range of the preferable solid content concentration varies depending on the method employed when the liquid crystal aligning agent is applied to the substrate. For example, the solid concentration in the case of the spinner method is preferably 1.5% by mass to 4.5% by mass. In the printing method, the solid content concentration is preferably 3% by mass to 9% by mass, and thereby the solution viscosity is preferably 12 mPa · s to 50 mPa · s. In the case of the ink jet method, the solid content concentration is preferably in the range of 1% by mass to 5% by mass, and thereby the solution viscosity is preferably in the range of 3 mPa · s to 15 mPa · s.

  As temperature at the time of preparing the said liquid crystal aligning agent, 10 to 50 degreeC is preferable and 20 to 30 degreeC is more preferable.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is formed from the liquid crystal alignment agent. Accordingly, the liquid crystal alignment film can be prevented from being deteriorated in display quality due to deterioration of electrical characteristics, etc., and can be easily peeled off during rework.

<Method for forming liquid crystal alignment film>
The liquid crystal alignment film of the present invention is formed by applying the liquid crystal aligning agent on the substrate, then heating the coating surface to form a coating film on the substrate, and further subjecting it to rubbing depending on the desired display mode. it can.

  When manufacturing a liquid crystal display element having a display mode of TN type, STN type, or VA type, a pair of two substrates provided with a patterned transparent conductive film is provided on each transparent conductive film forming surface, The liquid crystal aligning agent is preferably applied by an offset printing method, a spin coating method, or an ink jet method, and then each coated surface is heated to form a coating film.

  Examples of the substrate include glass substrates such as float glass and soda glass, and transparent substrates including plastic substrates such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, and polycarbonate (alicyclic olefin).

Examples of the transparent conductive film provided on one surface of the substrate include a NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), and the like. Can be mentioned.

  As a method for obtaining a patterned transparent conductive film, for example, a method for forming a pattern by photo-etching after forming a transparent conductive film without a pattern, and a method for using a mask having a desired pattern when forming a transparent conductive film Etc. When applying the liquid crystal alignment agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound, a functional titanium compound, etc. A pretreatment for applying in advance may be performed.

  After applying the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping. As temperature of prebaking, 30 to 200 degreeC is preferable, 40 to 150 degreeC is more preferable, and 40 to 100 degreeC is especially preferable. The prebaking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes.

  Next, baking (post-baking) is carried out for the purpose of completely removing the solvent and, if necessary, heat imidizing the polyamic acid. As temperature of post-baking, 80 to 300 degreeC is preferable and 120 to 250 degreeC is more preferable. The post-bake time is preferably 5 minutes to 200 minutes, more preferably 10 minutes to 100 minutes.

  Thus, 10 nm-500 nm are preferable and, as for the film thickness of the coating film formed, 10 nm-200 nm are more preferable.

  When manufacturing an IPS type liquid crystal display element, a conductive film forming surface of a substrate provided with a comb-shaped transparent conductive film and a surface of a counter substrate provided with no conductive film The liquid crystal aligning agent is preferably applied by an offset printing method, a spinner method, or an ink jet method, and each coating surface is then heated to form a coating film. Substrate material, transparent conductive film material, transparent conductive film patterning method, substrate pretreatment, heating method after applying a liquid crystal aligning agent, and preferred film thickness of the coating film to be formed are TN type display modes This is the same as that described in the case of manufacturing an STN type or VA type liquid crystal display element.

  When the display mode is a VA type liquid crystal display element, the coating film formed as described above can be used as it is as a liquid crystal alignment film, but after performing a rubbing treatment described later as desired. You may use for use.

  When manufacturing a liquid crystal display element having a display mode other than the VA type, a rubbing treatment is performed on the coating film formed as described above to obtain a liquid crystal alignment film. The rubbing treatment can be performed by rubbing the coating film surface formed as described above in a certain direction with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and becomes a liquid crystal aligning film.

  Further, the liquid crystal alignment film formed as described above is irradiated with ultraviolet rays on a part of the liquid crystal alignment film as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 6-222366 and 6-281937. By changing the pretilt angle of a partial region of the liquid crystal alignment film or by forming a resist film on a part of the surface of the liquid crystal alignment film as disclosed in JP-A-5-107544, Visibility characteristics of the liquid crystal display element obtained by performing a rubbing treatment in a direction different from the rubbing treatment and then removing the resist film so that the liquid crystal alignment film has different liquid crystal orientation ability for each region can be improved. .

<Liquid crystal display element>
The liquid crystal display element of the present invention includes the liquid crystal alignment film. The liquid crystal display element can be suitably applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, liquid crystal televisions, etc. Used in display devices.

<Method for forming liquid crystal display element>
The liquid crystal display element of this invention can be manufactured as follows, for example. Two substrates on which the liquid crystal alignment film is formed are prepared, and a liquid crystal cell is manufactured by disposing a liquid crystal between the two substrates opposed to each other. Here, when the rubbing treatment is performed on the coating film, the two substrates are disposed to face each other so that the rubbing directions in the respective coating films are at a predetermined angle, for example, orthogonal or antiparallel. In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.

  The first method is a conventionally known method. First, two sheets are interposed through a gap (hereinafter, also referred to as “cell gap”) so that the liquid crystal alignment films face each other. The two substrates are placed facing each other, the peripheral portions of the two substrates are bonded together using a sealant, and liquid crystal is injected and filled in the cell gap defined by the substrate surface and the sealant, and then the injection hole is sealed. Thus, a liquid crystal cell can be manufactured.

  The second method is a technique called an ODF (One Drop Fill) method in which, for example, an ultraviolet light curable material is placed at a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed. After applying a sealing material and dropping liquid crystal on the liquid crystal alignment film surface, the other substrate is bonded so that the liquid crystal alignment film faces, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant. Thus, a liquid crystal cell can be manufactured.

  Regardless of which method is used, 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 during liquid crystal injection is achieved. It is desirable to remove. And the said liquid crystal display element is obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell.

  Examples of the sealing agent include an aluminum resin sphere as a spacer and an epoxy resin containing a curing agent.

  Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Of these, nematic liquid crystal is preferable. In the case of the VA liquid crystal cell, nematic liquid crystal having negative dielectric anisotropy is preferable. Examples of such liquid crystal include dicyanobenzene liquid crystal, pyridazine liquid crystal, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, and phenylcyclohexane liquid crystal. In the case of a TN liquid crystal cell or STN liquid crystal cell, a nematic liquid crystal having positive dielectric anisotropy is preferable. Examples of such liquid crystal include biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, and cubane liquid crystal. . Further, chiral agents such as those sold as cholesteric liquid crystals (Merck, “C-15”, “CB-15”) such as cholesteryl chloride, cholesteryl nonate, cholesteryl carbonate, etc. for the above liquid crystal; p-decyloxybenzylidene A ferroelectric liquid crystal such as -p-amino-2-methylbutylcinnamate can be further added and used.

  As a polarizing plate bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an “H film” that absorbs iodine while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of itself is mentioned.

<Polymer composition>
The polymer composition of the present invention contains [A] at least one polymer selected from the group consisting of polyamic acid and polyimide, and [B] an imide ring-containing epoxy compound represented by the above formula (I). To do. The said polymer composition can be conveniently used as components, such as a liquid crystal aligning agent for forming a liquid crystal aligning film. Moreover, the film | membrane formed from the said polymer composition can also be used as an insulating film for electronic materials.

In the above formula (I), R ^A is a single bond or an alkanediyl group having 1 to 4 carbon atoms. R ^B is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent aromatic group, a divalent heterocyclic group, or a combination thereof. n is an integer of 0 or 1.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

<Synthesis of polyamic acid>
[Synthesis Example 1]
As tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 98 g (0.50 mol) and pyromellitic dianhydride 109 g (0.50 mol), and diamine compound 4,4 198 g (1.0 mol) of '-diaminodiphenylmethane was dissolved in a mixed solvent consisting of 230 g of NMP and 2,060 g of γ-butyrolactone, reacted at 40 ° C. for 3 hours, and then 1,350 g of γ-butyrolactone was added. A solution containing 10% by mass of (PA-1) was obtained. The solution viscosity of this solution was 118 mPa · s.

[Synthesis Example 2]
196 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 212 g (1, .2) of 2,2′-dimethyl-4,4′-diaminobiphenyl as diamine compound. 0 mol) was dissolved in a mixed solvent composed of 370 g of NMP and 3,300 g of γ-butyrolactone and reacted at 40 ° C. for 3 hours to obtain a solution containing polyamic acid (PA-2). The solution viscosity of this solution was 154 mPa · s.

<Synthesis of polyimide>
[Synthesis Example 3]
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 106 g (0.985 mol) of p-phenylenediamine as a diamine compound and cholestanyl 3,5-diaminobenzoate 7 0.8 g (0.015 mol) was dissolved in 3,042 g of NMP and reacted at 60 ° C. for 6 hours. The solution viscosity of the obtained polyamic acid solution was 181 mPa · s. Next, 3,380 g of NMP was added to the obtained polyamic acid solution, 395 g of pyridine and 306 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new γ-butyrolactone to remove pyridine and acetic anhydride out of the system. In this way, a solution containing 15% by mass of polyimide (PI-1) having an imidation ratio of about 95% was obtained. A small amount of the obtained polyimide solution was taken, and γ-butyrolactone was added to measure the solution viscosity as a solution having a polyimide concentration of 10% by mass, which was 102 mPa · s.

[Synthesis Example 4]
As tetracarboxylic dianhydride, 110 g (0.50 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro -2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione 160 g (0.50 mol) and p-phenylenediamine 94 g (0.87 mol) as a diamine compound, 1,3 -25 g (0.10 mol) of bis (3-aminopropyl) tetramethyldisiloxane and 9.6 g (0.015 mol) of 3,6-bis (4-aminobenzoyloxy) cholestane, 8.1 g of octadecylamine as monoamine (0 .030 mol) was dissolved in 960 g of NMP and reacted at 60 ° C. for 6 hours. A small amount of the obtained polyamic acid solution was taken, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 58 mPa · s. Next, 2,700 g of NMP was added to the obtained polyamic acid solution, 400 g of pyridine and 410 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new γ-butyrolactone to remove pyridine and acetic anhydride out of the system. In this way, a solution containing about 15% by mass of polyimide (PI-2) having an imidization rate of 95% was obtained. A small amount of the obtained polyimide solution was taken, and γ-butyrolactone was added to measure the solution viscosity as a solution having a polyimide concentration of 10% by mass, which was 72 mPa · s.

[Synthesis Example 5]
226 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 76 g (0.80 mol) of p-phenylenediamine as a diamine compound, 53 g of cholestanyl 3,5-diaminobenzoate (0.10 mol) and 100 g (0.20 mol) of cholestanyloxy-2,4-diaminobenzene were dissolved in 1,820 g of NMP and reacted at 60 ° C. for 6 hours. A small amount of the resulting polyamic acid solution was taken, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 80 mPa · s. Next, 4,225 g of NMP was added to the obtained polyamic acid solution, 104 g of pyridine and 134 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new NMP to remove pyridine and acetic anhydride out of the system. In this way, a solution containing about 15% by mass of polyimide (PI-3) having an imidization ratio of 66% was obtained. A small amount of the obtained polyimide solution was collected, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by mass was 98 mPa · s.

[Synthesis Example 6]
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 87 g (0.80 mol) of p-phenylenediamine and cholestanyloxy-2,4-diamino as diamine compounds 99 g (0.20 mol) of benzene was dissolved in 1,848 g of NMP and reacted at 60 ° C. for 6 hours. A small amount of the resulting polyamic acid solution was collected, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 120 mPa · s. Next, 3,809 g of NMP was added to the obtained polyamic acid solution, 79 g of pyridine and 102 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, pyridine and acetic anhydride were removed from the system by replacing the solvent in the system with new NMP. In this way, a solution containing about 15% by mass of polyimide (PI-4) having an imidation ratio of 49% was obtained. A small amount of the obtained polyimide solution was collected, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by mass was 155 mPa · s.

[Synthesis Example 7]
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 76 g (0.70 mol) of p-phenylenediamine as a diamine compound, 40 g of 4,4′-diaminodiphenylmethane ( 0.20 mol) and 50 g (0.10 mol) of cholestanyloxy-2,4-diaminobenzene were dissolved in 1,556 g of NMP and reacted at 60 ° C. for 6 hours. A small amount of the obtained polyamic acid solution was collected, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. The result was 133 mPa · s. Next, 3,614 g of NMP was added to the obtained polyamic acid solution, 79 g of pyridine and 102 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new NMP (pyridine and acetic anhydride used for the imidization reaction were removed from the system in this operation), and a polyimide (PI) having an imidization ratio of 46% (PI A solution containing about 15% by mass of -5) was obtained. A small amount of the obtained polyimide solution was collected, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by mass was 133 mPa · s.

<Preparation of liquid crystal aligning agent (for TN type liquid crystal display element)>
[Example 1]
A solution containing a polyamic acid (PA-1) and a solution containing a polyimide (PI-1) as the polymer [A] are mixed into a polyamic acid (PA-1): polyimide (PI-1) = 80: 20 (mass). Ratio), and γ-butyrolactone, NMP and ethylene glycol-mono-n-butyl ether were added thereto, and further the formula (I-1) exemplified as the above formula (I-1) as an epoxy compound [B] was added. -1-1) is added in an amount corresponding to 10 parts by mass with respect to 100 parts by mass of the total amount of the polymer [A] and sufficiently stirred, and the solvent composition is γ-butyrolactone: NMP: ethylene glycol-mono-n-. Butyl ether = 71: 17: 12 (mass ratio), solid content concentration was 3.5 mass%. A liquid crystal aligning agent (S-1) was prepared by filtering this solution using a filter having a pore diameter of 1 μm.

[Examples 2 to 13, Comparative Examples 1 to 12]
The types of polymer [A] and epoxy compound [B] and the amounts used thereof are as shown in Table 1, and the same operation as in Example 1 was carried out to prepare liquid crystal aligning agents (S-2) to (S-13). ) And (CS-1) to (CS-12) were prepared, and these were designated as Examples 2 to 13 and Comparative Examples 1 to 12, respectively.

In addition, (G-1) to (G-3) used corresponding to the epoxy compound [B] in the comparative example are as follows. In Table 1, (I-1-4), (I-1-15), (I-1-16), and (I-2-6) are respectively represented by the above formulas (I-1) and (I-1-6). -2) means the compounds mentioned as examples.
G-1 N, N, N ′, N′-tetraglycidyl-m-xylylenediamine G-2 N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane G-3 polyoxyethylene (5) Phenyl glycidyl ether (Nagase ChemteX Corporation, EX145)

<Preparation of liquid crystal aligning agent (for VA type liquid crystal display element)>
[Example 14]
NMP and ethylene glycol-mono-n-butyl ether are added to a solution containing polyimide (PI-3) as the polymer [A], and (I-1-1) is added as the epoxy compound [B]. The amount corresponding to 10 parts by mass with respect to 100 parts by mass of the polymer was added and stirred sufficiently, and the solvent composition was NMP: ethylene glycol-mono-n-butyl ether = 60: 40 (mass ratio), solid content. It was set as the solution whose density | concentration is 3.5 mass%. A liquid crystal aligning agent (S-14) was prepared by filtering this solution using a filter having a pore size of 1 μm.

[Examples 15 to 27, Comparative Examples 13 to 25]
The types of polymer [A] and epoxy compound [B] and the amounts used thereof are as shown in Table 1, and the same operation as in Example 14 was carried out to prepare liquid crystal aligning agents (S-15) to (S-27). ) And (CS-13) to (CS-25) were prepared as Examples 15 to 27 and Comparative Examples 13 to 25, respectively.
<Manufacture of TN liquid crystal display element>
[Example 28]
A liquid crystal aligning agent (S-1) is applied on a transparent conductive film made of an ITO film provided on one surface of a 1 mm thick glass substrate by a spinner, prebaked at 80 ° C. for 1 minute on a hot plate, and then By heating at 200 ° C. for 30 minutes, a coating film having a thickness of 80 nm was formed. The coating film is rubbed with a rubbing machine having a roll wrapped with a rayon cloth at a roll rotation speed of 500 rpm, a stage moving speed of 3 cm / sec, and a hair foot indentation length of 0.4 mm to give liquid crystal alignment ability. did. Then, ultrasonic cleaning was performed in ultrapure water for 1 minute, and then drying was performed in a 100 ° C. clean oven for 10 minutes to obtain a substrate having a liquid crystal alignment film. This operation was repeated to obtain a pair (two) of substrates having a liquid crystal alignment film. Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edges of the pair of substrates having the liquid crystal alignment film, the liquid crystal alignment film surfaces are overlapped and pressure bonded. The adhesive was cured. Next, after filling nematic liquid crystal (Merck, MLC-6221) between a pair of substrates from the liquid crystal injection port, the liquid crystal display element is manufactured by sealing the liquid crystal injection port with an acrylic photo-curing adhesive. This was designated as Example 28.

[Examples 29 to 40 and Comparative Examples 26 to 37]
Similar to Example 28, using the liquid crystal aligning agents (S-1) to (S-13) of Examples 1 to 13 and the liquid crystal aligning agents (CS-1) to (CS-12) of Comparative Examples 1 to 12 The liquid crystal display element was manufactured by operating, and these were made into Examples 29-40 and Comparative Examples 26-37.

<Manufacture of VA liquid crystal display element>
[Example 41]
A liquid crystal aligning agent (S-14) is applied on a transparent conductive film made of an ITO film provided on one surface of a 1 mm thick glass substrate by a spinner, prebaked at 80 ° C. for 1 minute on a hot plate, and then By heating at 210 ° C. for 30 minutes, a coating film (liquid crystal alignment film) having a film thickness of 80 nm was formed. This operation was repeated to obtain a pair (two) of substrates having a liquid crystal alignment film. Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edges of the pair of substrates having the liquid crystal alignment film, the liquid crystal alignment film surfaces are overlapped and pressure bonded. The adhesive was cured. Next, after filling nematic liquid crystal (Merck, MLC-6608) between a pair of substrates from the liquid crystal inlet, the liquid crystal inlet is sealed with an acrylic photo-curing adhesive to produce a liquid crystal display element. This was taken as Example 41.

[Examples 42 to 54 and Comparative Examples 38 to 50]
A liquid crystal display device operated in the same manner as in Example 41 using the liquid crystal aligning agents (S-14) to (S-27) and the liquid crystal aligning agents (CS-13) to (CS-25) of Comparative Examples 13 to 25 These were made into Examples 42-54 and Comparative Examples 38-50.

<Evaluation>
The following evaluation was performed about the liquid crystal aligning agent of Examples 1-27 and Comparative Examples 1-25, and the liquid crystal display element of Examples 28-54 and Comparative Examples 26-50.

[Measurement of peelability]
Each liquid crystal aligning agent concerning Examples 1-27 and Comparative Examples 1-25 was apply | coated with the spinner on the transparent conductive film which consists of an ITO film | membrane provided in one surface of the glass substrate of thickness 1mm, and 100 degreeC with a hotplate. For 90 seconds to form a coating film having a thickness of about 80 nm. This operation was repeated to prepare two substrates with a coating film. Next, the obtained substrate was stored in a dark room at 25 ° C. under a nitrogen atmosphere, taken out from the dark room after 12 hours and 72 hours, respectively, and immersed in a beaker containing 40 ° C. NMP for 2 minutes. After 2 minutes, the substrate was taken out of the beaker and washed several times with ultrapure water, and then water droplets on the surface were removed by air blowing, the substrate was observed, and whether a coating film remained was observed. Removed from the dark room after 72 hours, “○” indicates that the coating film was not left after NMP soaking, and the substrate taken out from the dark room after 72 hours could not be removed, but removed from the dark room after 12 hours Substrates that could be peeled were marked with “Δ”, and those that could not be peeled were marked with “x”. The results are shown in Table 1.

[Measurement of voltage holding ratio]
The deterioration of the electrical characteristics leading to the deterioration of display quality was evaluated from the voltage holding ratio of the liquid crystal display element. For each of the liquid crystal display elements according to Examples 28 to 54 and Comparative Examples 26 to 50, a voltage of 5 V was applied at 70 ° C. with an application time of 60 microseconds and a span of 167 milliseconds, and 167 milliseconds after the application release. The voltage holding ratio was measured by Toyo Technica Co., Ltd., VHR-1, and the value was defined as the initial voltage holding ratio (VH _1N ). Next, the liquid crystal cell after the initial voltage holding ratio measurement was irradiated with light for 1,000 hours using a weather meter using a carbon arc as a light source. For the liquid crystal display element after light irradiation, the voltage holding ratio was measured again by the same method as described above, and the value was defined as the voltage holding ratio after light irradiation (VH _AF ). The amount of decrease in the voltage holding ratio obtained as VH _IN −VH _AF was calculated by defining it as ΔVHR.
For the TN type liquid crystal display elements (Examples 28 to 40 and Comparative Examples 26 to 37), when the voltage holding ratio decrease ΔVHR is less than 7%, the reliability is “◎”, and when the reliability is 7% or more and less than 10% The reliability is “◯”, and the reliability is “×” when 10% or more.
For the VA liquid crystal display elements (Examples 41 to 54 and Comparative Examples 38 to 50), the reliability “「 ”is 2.5% or more and 5% or more when the decrease amount ΔVHR of the voltage holding ratio is less than 2.5%. Less than%, reliability “◯”, 5% or more reliability “×”. The results are shown in Table 2.

As is clear from the results in Tables 1 and 2, the liquid crystal alignment film formed from the liquid crystal alignment agent of the present invention can form a liquid crystal alignment film that can be easily peeled off during rework. In addition, the liquid crystal display element of the present invention provided with the liquid crystal alignment film has a good voltage holding ratio in any of the TN type and VA type display modes, and can suppress deterioration in display quality without deteriorating electrical characteristics. I understood.

  According to the present invention, it is possible to form a liquid crystal alignment film in which deterioration of display quality such as deterioration of electrical characteristics is suppressed and peeling in rework is easy. The liquid crystal display element can be suitably applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, liquid crystal televisions, etc. Used in display devices. Moreover, the film | membrane formed from the said polymer composition can also be used as an insulating film for electronic materials.

Claims (7)

[A] A liquid crystal aligning agent containing at least one polymer selected from the group consisting of polyamic acid and polyimide, and [B] an imide ring-containing monofunctional epoxy compound represented by the following formula (I).

(In the formula (I), R ^A is a single bond or an alkanediyl group having 1 to 4 carbon atoms. R ^B is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent group. (Aromatic group, divalent heterocyclic group, or a combination thereof. N is an integer of 0 or 1.) The liquid crystal aligning agent according to claim 1, wherein the formula (I) is at least one selected from the group consisting of compounds represented by the following formulas (I-1) and (I-2).

(In formula (I-1) and formula (I-2), R ^A has the same meaning as in formula (I) above. R ¹ , R ² and R ³ are each independently —O—, —COO. A linear or branched alkyl group having 1 to 20 carbon atoms which may contain-or -OCO-, and R ¹ and R ² , or R ¹ , R ² and R ³ are And may be linked to each other to form a ring structure in which some or all of the hydrogen atoms may be substituted. N is an integer of 0 or 1.)   The above [A] polymer is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2 , 4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-using a tetracarboxylic dianhydride containing at least one selected from the group consisting of dianhydrides 3. The liquid crystal aligning agent according to claim 1, wherein the liquid crystal aligning agent is at least one selected from the group consisting of a polyamic acid synthesized and a polyimide formed by dehydrating and ring-closing the polyamic acid. The liquid crystal aligning agent according to claim 1, wherein R ^{A of the} formula (I) is a methanediyl group. In the above formula (I-1) and formula (I-2), R ¹ and R ² are connected to each other to form a benzene ring in which some or all of the hydrogen atoms may be substituted. The liquid crystal aligning agent of Claim 2, Claim 3, or Claim 4.   The liquid crystal aligning film formed from the liquid crystal aligning agent of any one of Claims 1-5.   A liquid crystal display element provided with the liquid crystal aligning film of Claim 6.