JP2007192850A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

To provide a liquid crystal display element excellent in high reliability, high liquid crystal alignment, and high rubbing resistance, and to provide a liquid crystal alignment film that can be easily peeled for substrate regeneration.
A liquid crystal aligning agent comprising both a polymer having an amic acid bond unit and a polymer having an imide bond unit formed by a reaction of a tetracarboxylic dianhydride and a diamine, wherein the amic acid bond unit is formed as described above. A liquid crystal aligning agent comprising a repeating unit represented by a specific formula as:
[Selection figure] None

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. More specifically, it is excellent in reliability, low afterimage, rubbing resistance and liquid crystal orientation, and is applied to a large substrate, and can be easily peeled off with any commercially available aqueous or organic liquid crystal alignment film stripper for the substrate regeneration. It is related with the liquid crystal aligning agent which gives the liquid crystal aligning film which can be performed, the said liquid crystal aligning film, and the said liquid crystal display element using the same.

  Conventionally, a cell of a sandwich structure is formed by forming a nematic liquid crystal layer having positive dielectric anisotropy between two substrates having a liquid crystal alignment film formed on the surface via a transparent conductive film, There is known a TN liquid crystal display element having a TN (Twisted Nematic) type liquid crystal cell in which the major axis of liquid crystal molecules is continuously twisted by 90 degrees from one substrate toward the other substrate.

  Further, the addition of a chiral agent achieves a state in which the major axis of the liquid crystal molecules is continuously twisted between the substrates by 180 degrees or more, and an STN (Super Twisted Nematic) type liquid crystal display element utilizing the birefringence effect generated thereby. Is also present. More recently, a homeotropically aligned nematic liquid crystal layer having negative dielectric anisotropy between opposing substrates and a cholesteric liquid crystal layer in which the helical axis is parallel to the substrate normal are formed. A guest-host type reflective liquid crystal display element in which a dye is added to the above has also been developed. Here, as a material for the liquid crystal alignment film constituting the liquid crystal display element, polyimide, polyamide, polyester, and the like are conventionally known. In particular, polyimide is used in many liquid crystal display elements because of its excellent heat resistance, affinity with liquid crystals, mechanical strength, and the like.

  However, recently, liquid crystal display elements have also made remarkable progress as high-performance display elements in terms of size, weight reduction, and low power consumption, and accordingly, the required performance for liquid crystal alignment films has become increasingly severe. . In particular, the demand for process improvement and cost reduction accompanying the increase in size of the substrate has become stricter. However, a liquid crystal alignment film consisting of a polyamic acid, a polyimide precursor known in the art, and an imide polymer having a structure obtained by dehydrating and cyclizing it, has high reliability and high alignment control power. Furthermore, in order to realize high rubbing resistance, high adhesion and coating properties are imparted to the substrate. As a result, it was not possible to sufficiently peel off the alignment film using a commercially available aqueous or organic liquid crystal alignment film remover in order to regenerate a large substrate in order to reduce the cost. On the other hand, an alignment film that can be easily peeled off using a commercially available liquid crystal alignment film remover has a problem in that reliability, alignment regulating power, and rubbing resistance are reduced.

  An object of the present invention is to provide a liquid crystal aligning agent that provides a liquid crystal aligning film that exhibits good reliability, alignment characteristics, and rubbing resistance and can be easily peeled off with a commercially available aqueous or organic stripping solution.

  Another object of the present invention is to provide a liquid crystal alignment film having excellent performance as described above.

  Still another object of the present invention is to provide a liquid crystal display device comprising the liquid crystal alignment film of the present invention.

  Still other objects and advantages of the present invention will become apparent from the following description.

  The above objects and advantages of the present invention are, according to the present invention, firstly, a polymer having an amic acid bond unit and a polymer having an imide bond unit (hereinafter, referred to as “specific polymer (II)”). .) A liquid crystal aligning agent comprising both, and a polymer having a repeating unit represented by the following formula (I) as the above amic acid bond unit (hereinafter sometimes referred to as “specific polymer (I)”). It is achieved by a liquid crystal aligning agent characterized by containing.

（式中、Pは互いに独立に下記式（a）〜（e）

(In the formula, P are independently of each other the following formulas (a) to (e)

のそれぞれで表される４価の有機基であり、（a）〜（e）から選ばれる少なくとも一種の結合単位を含有する。Qは２価の有機基である。）

These are tetravalent organic groups represented by each of the formula (1) and contain at least one type of bond unit selected from (a) to (e). Q is a divalent organic group. )

  According to the present invention, secondly, the above objects and advantages of the present invention are achieved by a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention.

  According to the present invention, thirdly, the above objects and advantages of the present invention are achieved by a liquid crystal display device comprising the liquid crystal alignment film of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display element excellent in high reliability, high liquid crystal orientation, and high rubbing tolerance can be provided, and an alignment film can be easily peeled for substrate reproduction | regeneration.

  The liquid crystal display element having a liquid crystal alignment film made of the liquid crystal aligning agent of the present invention can be suitably used for TN type and STN type liquid crystal display elements, and by selecting a liquid crystal to be used, an SH (Super Homeotropic) type, It can also be suitably used for IPS (In-Plane Switching) type, ferroelectric and antiferroelectric liquid crystal display elements.

  Furthermore, the liquid crystal display element of the present invention can be effectively used for various devices, and is used for display devices such as a desk calculator, a wristwatch, a table clock, a coefficient display board, a word processor, a personal computer, and a liquid crystal television.

  Hereinafter, the present invention will be described in detail. The liquid crystal alignment film of the present invention is usually formed by applying the liquid crystal aligning agent of the present invention on a transparent electrode substrate and then drying (usually heat drying), and performing an alignment treatment on the film surface such as rubbing. Used later. The liquid crystal aligning agent of this invention consists of both the polymer which has an amic acid bond unit formed by reaction of tetracarboxylic dianhydride and diamine, and the polymer which has an imide bond unit.

  In the liquid crystal alignment film of the present invention, in the step of applying and drying the liquid crystal aligning agent on the substrate, heat drying is performed, and the amide bond unit in the liquid crystal aligning agent is dehydrated and closed to form an imide bond unit. You can also.

<Specific polymer (I)>
The polyamic acid used in the present invention is obtained by ring-opening polyaddition of a tetracarboxylic dianhydride and a diamine compound.

[Tetracarboxylic dianhydride]
As tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic acid By containing at least one selected from dianhydrides, the liquid crystal alignment film can be easily peeled from the substrate with a peeling liquid. In particular, it is preferable that the above five kinds of compounds are contained in an amount of 20 mol% or more based on the total of the amic acid binding units.

  The polyamic acid used in the present invention can contain other tetracarboxylic dianhydrides as necessary in addition to the above five compounds as tetracarboxylic dianhydrides.

  Examples of such other tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, and 2,3. , 5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, bicyclo [2.2. 2] -Oct-7-ene-2,3,5,6-tetracarboxylic 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, pyromellitic anhydride, butanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4 -Cyclo Tantetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2, 4,5-cyclohexanetetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c]- Furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c]- Furan-1,3-dione, 1 3,3a, 4,5,9b-hexahydro-5-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1, 3,3a, 4,5,9b-hexahydro-7-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1, 3,3a, 4,5,9b-hexahydro-7-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1, 3,3a, 4,5,9b-hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1, 3,3a, 4,5,9b-Hexahydro-5,8-dimethyl-5 (Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3- Aliphatic and alicyclic tetracarboxylic dianhydrides such as cyclohexene-1,2-dicarboxylic dianhydride, compounds represented by the following formulas (I) and (II);

(Wherein R ¹ and R ³ represent a divalent organic group having an aromatic ring, R ² and R ⁴ represent a hydrogen atom or an alkyl group, and a plurality of R ² and R ⁴ are the same. But it may be different.)

  1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-di Carboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride Bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) ) Dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, ethylene glycol-bis (anhydrotrimelli Tate), propylene glycol-bis (anhydro trimellitate), 1,4-butanediol-bis (anhydro trimellitate), 1,6-hexanediol-bis (anhydro trimellitate), 1,8 -Octanediol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydrotrimellitate), compounds represented by the following formulas (1) to (4), etc. And aromatic tetracarboxylic dianhydrides. These other tetracarboxylic dianhydrides may be used alone or in combination of two or more.

[Diamine compound]
Examples of the diamine compound include m-phenylenediamine, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenylsulfone, 3,3′-dimethyl-4,4′-. Diaminobiphenyl, 4,4′-diaminobenzanilide, 4,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4′-diaminobiphenyl, 5-amino-1- (4 ′ -Aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4'-aminophenyl) -1,3,3-trimethylindane, 3,4'-diaminodiphenyl ether, 3,3'- Diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis [4- (4-amino Enoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- ( 4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9, 9-bis (4-aminophenyl) -10-hydroanthracene, 2,7-diaminofluorene, 9,9-bis (4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2′-ditolylfluoromethyl-4,4′-diaminodiphenyl, 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 1,4.4 ′-(p-phenyleneisopropyl Ridene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′- Aromatic diamines such as diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4′-bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl;

1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoin danylene dimethylene diamine, tricyclo [6,2,1,0 ^2.7 ] -undecylenedimethyl diamine, 4 Aliphatic and cycloaliphatic diamines such as 4,4'-methylenebis (cyclohexylamine);

  Monosubstituted phenylenediamines represented by the following formula (III); diaminoorganosiloxanes represented by the following formula (IV) (excluding bisaminopropyltetramethyldisiloxane);

(Wherein X represents a divalent organic group selected from —O—, —COO—, —OCO—, —NHCO—, —CONH— and —CO—, and R ⁵ represents a steroid skeleton or trifluoro R ⁹ represents a monovalent organic group having a methyl group, R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms, a plurality of R ⁹ may be the same or different, and p is an integer of 1 to 3 And q is an integer from 1 to 20.)

  Examples include compounds represented by the following formulas (5) to (8). These diamine compounds can be used alone or in combination of two or more.

(In the formula, y is an integer of 2 to 12, and z is an integer of 1 to 5.)

  Among these diamine compounds, p-phenylenediamine, bisaminopropyltetramethyldisiloxane, 4,4′-diaminodiphenylmethane, 2,2-dimethyl-4,4-diminobiphenyl and 3,6-bis (4- Aminobenzoyloxy) cholestane, 4,4′-diaminodiphenyl ether is preferred.

  The ratio of the tetracarboxylic dianhydride and the diamine compound used in the polyamic acid synthesis reaction is such that the acid anhydride group contained in the tetracarboxylic dianhydride is equivalent to 1 equivalent of the amino group contained in the diamine compound. Is preferably a ratio of 0.2 to 2 equivalents, more preferably a ratio of 0.3 to 1.4 equivalents. In both cases where the ratio of the acid anhydride group contained in the tetracarboxylic dianhydride is less than 0.2 equivalent or more than 2 equivalent, the molecular weight of the polymer obtained becomes too small, and the liquid crystal aligning agent is applied. May be inferior.

  The polyamic acid constituting the liquid crystal aligning agent of the present invention is synthesized by a reaction between the tetracarboxylic dianhydride and the diamine compound. The synthetic reaction of polyamic acid is usually performed in an organic solvent under a temperature condition of 0 to 150 ° C, preferably 0 to 100 ° C. If the reaction temperature is less than 0 ° C, the solubility of the compound in the solvent may be inferior, and if it exceeds 150 ° C, the molecular weight of the resulting polymer may be reduced.

  The organic solvent used for the synthesis of the polyamic acid is not particularly limited as long as it can dissolve the tetracarboxylic dianhydride, the diamine compound, and the polyamic acid generated by the reaction. For example, γ-butyrolactone, N-methyl- Aprotic polar solvents such as 2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, tetramethylurea, hexamethylphosphoryltriamide, 1,3-dimethyl-2-imidazolidinone; Mention may be made of phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol.

  The amount (A) of the organic solvent used is such that the total amount (B) of the tetracarboxylic dianhydride as the reaction raw material and the diamine compound is 0.1 to 30% by weight with respect to the total amount (A + B) of the reaction solution. It is preferable that the amount is small.

  In addition, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polyamic acid, are used in combination with the organic solvent as long as the resulting polyamic acid does not precipitate. be able to. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetic acid. Methyl, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, 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, ethylene glycol methyl ether acetate, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol dimethyl ether , Dipropylene glycol diethyl ether, ethylene glycol ethyl ether acetate, 4-hydroxy-4-methyl-2-pentanone, ethyl 2-hydroxypropionate, ethyl lactate, methyl lactate, butyl lactate, ethyl ethoxy acetate, ethyl hydroxy acetate, 2 -Methyl hydroxy-3-methylbutanoate, 3-methyl Methyl xylpropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-methyl-3-methoxybutanol, 3-ethyl-3-methoxybutanol, 2-methyl-2-methoxybutanol, 2-ethyl- 2-methoxybutanol, 3-methyl-3-ethoxybutanol, 3-ethyl-3-ethoxybutanol, 2-methyl-2-ethoxybutanol, 2-ethyl-2-ethoxybutanol, tetrahydrofuran, dichloromethane, 1,2-dichloroethane 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like. These can be used alone or in combination of two or more.

  By the above synthesis reaction, a polymer solution obtained by dissolving polyamic acid is obtained. And a polyamic acid can be obtained by pouring this polymer solution in a lot of poor solvents, obtaining a deposit, and drying this deposit under reduced pressure. Further, the polyamic acid can be purified by dissolving the polyamic acid again in an organic solvent and then performing the step of precipitation with a poor solvent once or several times.

<Specific polymer (II)>
The specific polymer (II) constituting the liquid crystal aligning agent of the present invention can be prepared by the following methods (1) to (2). A polymer having a so-called imidization ratio of 70% or more in which a part of the repeating unit of polyamic acid is dehydrated and closed is also preferably used for the liquid crystal aligning agent of the present invention.

  Method (1): A method in which polyamic acid is heated to perform dehydration ring closure.

  The reaction temperature in this method is preferably 60 to 300 ° C, more preferably 120 to 250 ° C. If the reaction temperature is less than 60 ° C., the imidization reaction does not proceed sufficiently, and if the reaction temperature exceeds 300 ° C., the molecular weight of the resulting polyimide may be small.

  Method (2): A method in which polyamic acid is dissolved in an organic solvent, a dehydrating agent and an imidization catalyst are added to the solution, and heating is performed as necessary.

In this method, as the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. It is preferable that the usage-amount of a dehydrating agent shall be 1.6-20 mol with respect to 1 mol of repeating units of a polyamic acid. Moreover, as an imidation catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example, However, It is not limited to these. The amount of the imidization catalyst used is preferably 0.5 to 10 mol with respect to 1 mol of the dehydrating agent to be used. In addition, as an organic solvent used for imidation reaction, the same thing as the organic solvent illustrated as what is used for the synthesis | combination of a polyamic acid can be mentioned. And the reaction temperature of imidation reaction becomes like this. Preferably it is 0-180 degreeC, More preferably, it is 60-150 degreeC.
As the tetracarboxylic dianhydride used for the synthesis of the specific polymer (I), a compound used for the synthesis of the specific polymer (I) can be used.
Among these tetracarboxylic dianhydrides, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, 2,3,5 -Tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, bicyclo [2.2.2] -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo It is preferable to use at least two selected from the group consisting of -3-furanyl) naphtho [1,2-c] furan-1,3-dione.

<Intrinsic Viscosity of Acid Specific Polymer (I) and Specific Polymer (II)>
The intrinsic viscosity (measured in N-methyl-2-pyrrolidone at 30 ° C., the same below) of the polyamic acid and polyimide obtained as described above is preferably 0.05 to 10 dl / g, more preferably. Is 0.05 to 5 dl / g.

<End-modified polymer>
The polyamic acid and polyimide used for the liquid crystal aligning agent for forming the liquid crystal aligning film of the present invention may be a terminal-modified polymer. This terminal-modified polymer has an adjusted molecular weight and can improve the coating properties of the liquid crystal aligning agent without impairing the effects of the present invention. The terminal-modified polymer can be synthesized by adding an acid anhydride, a monoamine compound, or a monoisocyanate compound to the reaction system when synthesizing the polyamic acid.

  Examples of the acid anhydride added to the reaction system for synthesizing the polyamic acid in order to obtain a terminal-modified polymer include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, Examples thereof include n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride, n-hexadecyl succinic anhydride, and the like. Examples of the monoamine added to the reaction system include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosyl Alkylamines such as amine; 3-aminopropylmethyldiethoxysilane, 3- [N-allyl-N- (2-aminoethyl)] aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-amino Propylmethyldimethoxysilane, N-[(3-trimethoxysilyl) propyl Propyl] diethylenetriamine, and the like. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

<Liquid crystal aligning agent>
The liquid crystal alignment film of the present invention is formed from a liquid crystal aligning agent in which the polyimide and / or polyamic acid is usually dissolved and contained in an organic solvent.

  As an organic solvent which comprises the liquid crystal aligning agent of this invention, the same thing as the solvent illustrated as what is used for the synthesis reaction of a polyamic acid can be mentioned. Moreover, the poor solvent illustrated as what can be used together in the case of the synthesis reaction of a polyamic acid can also be selected suitably, and can be used together.

  The solid content concentration in the liquid crystal aligning agent that gives the liquid crystal alignment film of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably in the range of 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface to form a coating film that becomes a liquid crystal alignment film. When the solid content concentration is less than 1% by weight, the coating film thickness is It is too small to obtain a good liquid crystal alignment film. When the solid content concentration exceeds 10% by weight, it is difficult to obtain a good liquid crystal alignment film because the film thickness is excessive, and the viscosity of the liquid crystal aligning agent is increased, so that the coating properties tend to be inferior. Moreover, the temperature at the time of preparing the liquid crystal aligning agent of this invention, Preferably, it is 0 to 200 degreeC, More preferably, it is 20 to 60 degreeC.

<Epoxy group-containing compound>
The liquid crystal aligning agent which forms the liquid crystal aligning film of this invention can contain the compound which has an at least 1 epoxy group in a molecule | numerator if necessary. Examples of the epoxy compound having at least one epoxy group in the molecule include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neo Pentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′ N ', - may be mentioned as being preferred and tetraglycidyl-4,4'-diaminodiphenylmethane. The blending ratio of these epoxy compounds is preferably 5 parts by weight or less with respect to 100 parts by weight of the polymer.

  The liquid crystal aligning agent that forms the liquid crystal alignment film of the present invention may further contain a functional silane-containing compound from the viewpoint of improving the adhesion to the substrate surface. Examples of such functional silane-containing compounds 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-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl- , 4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N -Bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, etc. can be mentioned. The blending ratio of these functional silane-containing compounds is preferably 40 parts by weight or less with respect to 100 parts by weight of the polymer.

<Liquid crystal display element>
A liquid crystal display element obtained using the liquid crystal alignment film of the present invention can be produced, for example, by the following method.

(1) A liquid crystal aligning agent for forming a liquid crystal alignment film of the present invention is applied to one surface of a substrate provided with a patterned transparent conductive film by a method such as a roll coater method, a spinner method, a printing method, and the like. A coating film is formed by heating the coated surface. Here, as the substrate, for example, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, or polycarbonate can be used. As a transparent conductive film provided on one surface of the substrate, an 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 ), etc. Can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is used. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane-containing compound, a functional titanium-containing compound, or the like is previously applied to the surface of the substrate. You can also The heating temperature after application of the liquid crystal aligning agent is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. In addition, the liquid crystal aligning agent of the present invention containing a polyamic acid forms a coating film that becomes an alignment film by removing the organic solvent after coating, but further proceeds with dehydration ring closure by further heating, and is further imidized. It can also be set as a coating film. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.

(2) A rubbing process is performed in which the formed coating film surface is rubbed in a certain direction with a roll wound with a cloth made of a fiber such as nylon, rayon, or cotton. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film.

  Further, by partially irradiating the liquid crystal alignment film formed of the liquid crystal alignment agent of the present invention with ultraviolet rays as disclosed in, for example, JP-A-6-222366 and JP-A-6-281937. A resist film is partially formed on the surface of the liquid crystal alignment film that has been subjected to a treatment for changing the pretilt angle or a rubbing treatment as disclosed in JP-A-5-107544, which is different from the previous rubbing treatment. The visibility characteristics of the liquid crystal display element can be improved by removing the resist film after performing the rubbing treatment in the direction and changing the liquid crystal alignment ability of the liquid crystal alignment film.

(3) Two substrates on which the liquid crystal alignment film is formed as described above are produced, the two substrates are arranged to face each other with a gap (cell gap) therebetween, and a sealant is applied to the peripheral portion of the two substrates. The liquid crystal is formed by injecting and filling the liquid crystal into the cell gap defined by the substrate surface and the sealing agent, and sealing the injection hole. And the liquid crystal display element of this invention is obtained by bonding a polarizing plate to the outer surface of a liquid crystal cell, ie, the other surface side of each board | substrate which comprises a liquid crystal cell.

  Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.

  Examples of liquid crystals include nematic liquid crystals such as Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenyl cyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenyl cyclohexane liquid crystals, pyrimidine liquid crystals, dioxanes. Type liquid crystal, bicyclooctane type liquid crystal, cubane type liquid crystal and the like can be used. Further, for these liquid crystals, for example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, cholesteryl carbonate, and chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck). Etc. can also be used.

  Further, as a polarizing plate to be 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 sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films. The polarizing plate which consists of itself can be mentioned.

<Liquid crystal alignment liquid>
Commercially available stripping solutions used for stripping the liquid crystal alignment film of the present invention from the substrate include, for example, TS-204 manufactured by Sanyo Kasei Kogyo Co., Ltd., EP-5 manufactured by Yokohama Yushi Kogyo Co., Ltd., PRS-2000 manufactured by JTBaker, etc. . The stripping solution used for the liquid crystal alignment film includes an aqueous stripping solution containing a glycol solvent and an alkaline compound and / or a nonionic surfactant, or an organic solvent stripping solution containing N-methylpyrrolidone or γ-butyrolactone. is there.

  Examples of the glycol solvent contained in the aqueous stripping solution include ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoisopropyl ether, diethylene glycol monobutyl ether acetate, and the like.

  Examples of the alkaline compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium hydrogen phosphate, diammonium hydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorus Potassium dihydrogen phosphate, sodium dihydrogen phosphate, lithium silicate, sodium silicate, potassium silicate, lithium carbonate, sodium carbonate, potassium carbonate, lithium borate, potassium borate, sodium borate, potassium borate, ammonia, Tetramethylammonium hydroxide, dihydroxyethyltrimethylammonium hydroxide, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, ethanolamine Emissions, N- methylpiperidine, etc. trimethyl hydroxyethyl ammonium hydroxide and the like.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene allyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, oxyethylene-oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene Examples include ethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene alkylamine.

  Examples of the organic solvent-based stripping solution include stripping solutions made of N-methylpyrrolidone or γ-butyrolactone, or containing 20% or more thereof and 0 to 20% of the alkaline compound.

  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 peelability of the liquid crystal alignment film in the examples and comparative examples of the present specification was determined by visually confirming the presence or absence of the film before and after immersing the coating film on the glass substrate in the peeling solution. The rubbing resistance was determined by rubbing the coating film formed on the glass substrate 10 times and confirming the presence or absence of scratches. Furthermore, the orientation and reliability tests of the liquid crystal display device produced using the alignment film were evaluated by the following methods.

(Orientation test)
A liquid crystal cell was prepared with the substrate coated with the alignment film, and the orientation was evaluated by checking whether or not fluid alignment occurred when the liquid crystal was vacuum injected into the cell.

(Reliability test)
A liquid crystal display element was placed in a constant temperature bath at 70 ° C., and continuously driven for 24 hours with a drive waveform generator “Function / arbitrary waveform generator” (manufactured by Hewlett Packard).

Synthesis example 1
2,3,5-tricarboxycyclopentylacetic acid dianhydride 112.09 g (0.5 mol) and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5 as tetracarboxylic dianhydride (Tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione 157.15 g (0.5 mol), p-phenylenediamine as a diamine compound 90.03 g (0 8325 mol), 24.85 g (0.1 mol) of bisaminopropyltetramethyldisiloxane and 26.3 g (0.06) of 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate. Mol), 1.396 g (0.015 mol) of aniline as a monoamine was dissolved in 4500 g of N-methyl-2-pyrrolidone, and 6 ℃ In the reaction was allowed to proceed for 6 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 400 g of polyamic acid having a logarithmic viscosity of 0.81 dl / g and an imidization rate of 0%. 30 g of the resulting polyamic acid was dissolved in 570 g of N-methyl-2-pyrrolidone, 23.4 g of pyridine and 18.1 g of acetic anhydride were added, and dehydration was carried out at 110 ° C. for 4 hours, followed by precipitation, washing, The pressure was reduced to obtain 18.01 g of polyimide having a logarithmic viscosity of 0.75 dl / g (referred to as “polyimide (A-1)”).

Synthesis example 2
29.22 g (1.0 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as tetracarboxylic dianhydride and 200.24 g (1. of 1.4) of 4,4′-diaminodiphenyl ether as diamine compound. 0 mol) was dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 40 ° C. for 3 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 465.46 g of a polyamic acid having a logarithmic viscosity of 0.91 dl / g (referred to as “polyamic acid (B-1)”). It was.

Synthesis example 3
3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride as a tetracarboxylic dianhydride, 322.23 g (1.0 mol), and 200.24 g (1. 4) of 4,4′-diaminodiphenyl ether as a diamine compound. 0 mol) was dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 40 ° C. for 3 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 485.45 g of polyamic acid having a logarithmic viscosity of 0.94 dl / g (referred to as “polyamic acid (B-2)”). It was.

Synthesis example 4
3,3 ′, 4,4′-biphenyl ether as tetracarboxylic dianhydride 310.22 g (1.0 mol) of tetracarboxylic dianhydride, and 200.24 g (1 of 4,4′-diaminodiphenyl ether as diamine compound) 0.0 mol) was dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 40 ° C. for 3 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 482.22 g of a polyamic acid having a logarithmic viscosity of 0.90 dl / g (referred to as “polyamic acid (B-3)”). It was.

Comparative Synthesis Example 1
1,3,3a, 4,5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan- as tetracarboxylic dianhydride 314.29 g (1.0 mol) of 1,3-dione and 200.24 g (1.0 mol) of 4,4′-diaminodiphenyl ether as a diamine compound were dissolved in 4,500 g of N-methyl-2-pyrrolidone. The reaction was carried out at 0 ° C. for 3 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 480.22 g of polyamic acid having a logarithmic viscosity of 0.89 dl / g (referred to as “polyamic acid (B-4)”). It was.

Comparative Synthesis Example 2
As a tetracarboxylic dianhydride, 196.12 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic acid and 200.24 g (1.0 mol) of 4,4′-diaminodiphenyl ether as a diamine compound were added. -Methyl-2-pyrrolidone was dissolved in 4,500 g and reacted at 40 ° C. for 3 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 369.12 g of a polyamic acid having a logarithmic viscosity of 0.89 dl / g (referred to as “polyamic acid (B-5)”). It was.

Example 1
The polyimide (A-1) obtained in Synthesis Example 1 and the polyamic acid (B-1) obtained in Synthesis Example 2 and the epoxy group-containing compound were mixed with γ-butyrolactone / N-methyl-2-pyrrolidone / butyl cellosolve. A liquid crystal aligning agent was prepared by dissolving in a solvent (weight ratio 72/15/13) to obtain a solution having a solid content concentration of 4% by weight and filtering the solution using a filter having a pore size of 1 μm. The polyimide and polyamic acid were used in such a ratio that polyimide: polyamic acid = 1: 4 (weight ratio), and the epoxy group-containing compound was prepared to contain 2 parts by weight with respect to 100 parts by weight of the polymer. . The liquid crystal aligning agent is applied to the transparent electrode surface of the glass substrate with a transparent electrode made of an ITO film using a printing machine for applying a liquid crystal alignment film, dried on a hot plate at 210 ° C. for 10 minutes, and a dry average film thickness of 600 An angstrom film was formed. This film was immersed in a stripping solution PRS-2000 manufactured by JTBaker at 50 ° C. for 10 minutes, and then visually checked for the presence of a liquid crystal alignment film. The liquid crystal alignment film was not seen on the glass substrate, and it was peelable. Using a rubbing machine having a roll in which a rayon cloth is wrapped around this film, a rubbing treatment is performed 10 times with a roll rotation speed of 400 rpm, a stage moving speed of 3 cm / sec, and a hair foot indentation length of 0.4 mm. As a result, it was not possible to confirm scraping or peeling. On the other hand, the alignment film-coated substrate that had been rubbed once was immersed in water for 1 minute, and then both substrates were dried in a clean oven at 100 ° C. for 10 minutes. Next, an epoxy resin adhesive containing divinylbenzene spheres having a diameter of 5.5 μm is applied to the outer edges of the pair of rubbed liquid crystal sandwich substrates having the liquid crystal orientation film, and then the pair of liquid crystal sandwich substrates is attached to the liquid crystal orientation film. The adhesive was cured by overlapping and pressing so that the surfaces were opposed. Next, after filling a nematic liquid crystal (MLC-6221 manufactured by Merck & Co., Inc.) between a pair of substrates from the liquid crystal injection port, the liquid crystal injection port is sealed with an acrylic photo-curing adhesive, and the both sides on the outside of the substrate are sealed. A polarizing plate was laminated to prepare a liquid crystal display element. No flow orientation was observed, and after the reliability test, no contrast unevenness or display defect was observed.

Examples 2 and 3, Comparative Examples 1 and 2
A liquid crystal display device was produced in the same manner as in Example 1 except that the polyimide obtained in Synthesis Example 1 and the polyamic acids obtained in Synthesis Examples 3 and 4 and Comparative Synthesis Examples 1 and 2 were used.

Claims (6)

A liquid crystal aligning agent comprising both a polymer having an amic acid bond unit and a polymer having an imide bond unit, characterized by containing a repeating unit represented by the following formula (I) as the amic acid bond unit: Liquid crystal aligning agent.

(In the formula, P are independently of each other the following formulas (a) to (e)

These are tetravalent organic groups represented by each of the formula (1) and contain at least one type of bond unit selected from (a) to (e). Q is a divalent organic group. ) The liquid crystal aligning agent of Claim 1 whose amic acid bond unit shown by said (a)-(e) is 20 mol% or more with respect to the sum total of an amic acid bond unit. 1,2,3,4-Cyclobutanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride as tetracarboxylic dianhydrides for synthesizing polymers having imide bond units 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, bicyclo [ 2.2.2] -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro The liquid crystal aligning agent according to claim 1 or 2, comprising at least two selected from the group consisting of -2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione. The liquid crystal aligning agent of Claims 1-3 which contains 0-5 weight part of compounds which have at least 1 epoxy group in a molecule | numerator with respect to 100 weight part of polymers. The liquid crystal aligning film formed from the liquid crystal aligning agent in any one of Claims 1-4. A liquid crystal display device comprising the liquid crystal alignment film according to claim 5.