JP2621347B2 - Alignment material for liquid crystal display devices - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an alignment material for a liquid crystal display device.

[Prior Art] Conventionally, a polyamide acid or a polyimide soluble in an organic solvent has been used as an alignment material for a liquid crystal display element. As polyamic acids, aromatic polyamic acids and alicyclic or aliphatic polyamic acids are known.

Aromatic polyamic acid has a poor stability, and gradually undergoes a dehydration ring closure reaction to be converted to polyimide.When used as a liquid crystal alignment film, it is usually heated at a temperature of 300 ° C. or higher.
It has been used as a stable polyimide film.

However, when the film is heated at a high temperature and used as a polyimide film, there is a problem that a plastic substrate such as polyester or polyethersulfone having low heat resistance cannot be used.

On the other hand, polyimides soluble in alicyclic or aliphatic polyamic acids and organic solvents are excellent in stability, but the volume resistivity of the liquid crystal alignment film formed therefrom is high, and depending on the type of liquid crystal display element, the printing voltage may be reduced. It has the disadvantage of having to be high.

Further, the refractive index of a film formed from a polyimide soluble in an alicyclic or aliphatic polyamic acid and an organic solvent,
Generally, it is lower than a polyimide film formed from an aromatic polyamic acid, and has a drawback that wiring formed on a substrate is easily seen.

Further, there is a problem that the liquid crystal alignment line using the above-mentioned polyimide and polyamic acid easily causes electrostatic breakdown at the time of rubbing.

[Problems to be Solved by the Invention] The present invention solves such a conventional technical problem by using a specific alignment material for a liquid crystal display element, has excellent stability, and does not require heating at a high temperature. , Excellent electrical characteristics, and does not cause electrostatic breakdown at the time of rubbing, the refractive index of the film is high,
An object of the present invention is to provide an alignment material for a liquid crystal display element, which can provide a liquid crystal alignment film having no visible wiring.

[Means for Solving the Problems] That is, the present invention is synthesized by dehydrating and clogging a reaction product of an alicyclic tetracarboxylic acid and a diamine in an organic solvent in the presence of a dehydrating agent and a basic catalyst. Having an imide bond and an amide bond in a ratio of 5/95 to 95/5, and an intrinsic viscosity ηinh (concentration: 0.5 g / 100 ml, solution γ-butyrolactone, measurement temperature: 30 ° C .; the same applies hereinafter) of 0.05 to 20 dl /. g (hereinafter referred to as "polymer" at the end) and a reaction product of an amine compound are dissolved in an organic solvent,
An object of the present invention is to provide an aligning agent for a liquid crystal display device, wherein the solid content is 0.05 to 20% by weight.

The tetracarboxylic acids used in the present invention are tetracarboxylic acid, tetracarboxylic monoanhydride, tetracarboxylic dianhydride, tetracarboxylic monoalkyl ester, tetracarboxylic dialkyl ester, tetracarboxylic trialkyl ester, And tetracarboxylic acid tetraalkyl esters.

Such tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acids, 1,2,3,4-cyclopentanetetracarboxylic acids, 2,3,5-tricarboxycyclopentylacetic acids, 3,5, 6-tricarboxy-norbornane-2-acetic acids, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexenedicarboxylic acid,
Bicyclo (2,2,2) -oct-7-ene-tetracarboxylic acids, 1,2,3,4-furantetracarboxylic acids, 3,3 ′,
Alicyclic tetracarboxylic acids such as 4,4'-perfluoroisopropylidenetetracarboxylic acids can be mentioned. Among these tetracarboxylic acids, particularly preferred are 2,3,5-tricarboxycyclopentylacetic acid and 1,2,3,4-cyclopentenetetracarboxylic acid.

Further, in the present invention, the alicyclic tetracarboxylic acids may be replaced with butanetetracarboxylic acids, 4,4′-bis (3,4
-Dicarboxyphenoxy) diphenyl sulfides,
4,4'-bis (3,4-dicarboxyphenoxy) diphenylsulfones, 4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropanes, 3,3 ', 4,4'-par Fluoroisopropylidenetetracarboxylic acids, 3,3 ′, 4,
4'-biphenylethertetracarboxylic acids, bis (phthalic acid) phenylphosphine oxides, p-phenylene-bis- (triphenylphthalic acid), m-phenylene-bis- (triphenylphthalic acid), bis (triphenylphthalic acid) (Phenylphthalic acid) -4,4'-diphenyl ethers, bis (triphenylphthalic acid) -4,4'-diphenylmethane, pyromellitic acids, 3,3 ', 4,4'-benzophenonetetracarboxylic acids, 3,3 ', 4,4'-biphenylsulfonetetracarboxylic acids, 1,4,5,8-naphthalenetetracarboxylic acids, 2,3,6,7-naphthalenetetracarboxylic acids, 3,3', 4,4'-biphenyl Aliphatic or aromatic compounds such as ether tetracarboxylic acids, 3,3 ', 4,4'-dimethyldiphenylsilane tetracarboxylic acid, and 3,3', 4,4'-tetraphenyl silane tetracarboxylic acid It can be used in combination Rakarubon acids. The proportion of these aliphatic or aromatic tetracarboxylic acids used in combination is usually 50 mol% or less, preferably 20 mol% or less, based on the alicyclic tetracarboxylic acids.

As the diamine, paraphenylenediamine, metaphenylenediamine, 4,4'-diaminediphenylmethane, 4,4'-diaminodiphenylethane, benzidine, 4,4'-diaminodiphenylsulfide, 4,4 '
-Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-diaminobenzanilide, 3,4'-diamino Diphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2
-Bis [4- (4-aminophenoxy) phenyl] propane, 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-hydro-anthracene,
9,9-bis (4-aminophenyl) fluorene, 4,4'-
Methylene-bis (2-chloroaniline), 2,2 ', 5,5'
-Tetrachloro-4,4'-diaminobiphenyl, 2,2'-
Aromatic diamines such as dichloro-4,4-diamino-5,5'-dimethoxybiphenyl and 3,3'-dimethoxy-4,4'-diaminobiphenyl, 1,1'-metaxylylenediamine, 1,3- Propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4'-dimethylheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclo pentadienylidene diamine, hexahydro-4,7-meth Noin mite range diamine, tricyclo (6,2,1,0 ^2.7) - aliphatic or alicyclic diamines such as undecylenate range methyl-diamine, and Wherein R is an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, or a propyl group; an alicyclic group such as a cyclohexyl group; or an aromatic group such as a phenyl group; , N represents an integer of 1 to 20.) and the like.

These tetracarboxylic acids and diamines can be used alone or in combination of two or more.

The diamine is used in an amount of usually 0.5 to 2 mol, preferably 0.8 to 1.3 mol, per mol of tetracarboxylic acid.
Is a mole.

The reaction between the tetracarboxylic acid and the diamine is performed in an organic solvent by a conventionally known method.

The organic solvent used herein is not particularly limited as long as it can dissolve the obtained polymer product (polyamic acid and the like). For example, N-methyl-2-pyrrolidone, N, N
-Dimethylacedamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, bis (methoxyethyl) ether, tetrahydrofuran, chloroform, 1,4-dioxane and the like.

In this case, the organic solvent includes ethers, halogenated hydrocarbons, and hydrocarbons, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, which are other common organic solvents. Diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane,
Trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like can also be mixed to such an extent that a polymer product is not precipitated.

The amount of the organic solvent to be used is not particularly limited, but is such that the solid concentration is usually 0.1 to 30% by weight.

The reaction between the tetracarboxylic acid and the diamine is usually performed at 0 to 150 ° C, preferably 0 to 80 ° C.

The polymer used in the present invention has an imide bond and an amide bond at a ratio of 5 to 95/95 to 5, preferably 95 to 20/5 to 80. It is synthesized by dehydration and ring closure in the same organic solvent as above using a dehydrating agent and a basic catalyst. Here, as the dehydrating agent, acetic anhydride, propionic anhydride,
An acid anhydride such as trifluoroacetic anhydride can be used. The basic catalyst is not particularly limited, but tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used.

The amount of the dehydrating agent used is 0.8 to 1.2 equivalents of the amount of the dehydrating and ring-closing bond of the polymer product, and the amount of the basic catalyst used is 0.5 to 10 equivalents of the dehydrating agent used in the dissolving organic solvent. The reaction temperature is usually 80 to 180 ° C.

The ratio of the imide bond of the polymer in the present invention is
If it exceeds 95, it becomes impossible to produce a liquid crystal alignment film having no visible wiring, and the film is likely to be damaged by electrostatic breakdown during rubbing. When the ratio of the imide bond is less than 5, the orientation of the liquid crystal when formed into a liquid crystal alignment film becomes insufficient.

The intrinsic viscosity ηinh of the polymer used in the present invention is 0.0
It is 5-20 dl / g.

Next, as the amine compound used in the present invention, n-amylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-dodecylamine, n-undecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-nonadecylamine,
primary amines such as n-eicosylamine, n-heicosylamine, n-docosylamine, n-tricosylamine, n-tetracosylamine, n-triacontylamine, cyclohexylamine; N-methyl-n-octylamine; N-methyl-n-
Decylamine, N-methyl-n-dodecylamine, N-
Secondary amines such as methyl-n-tetradecylamine, N-methyl-n-hexadecylamine, N-methyl-n-octadecylamine, dicyclohexylamine, dioctylamine, didodecylamine, dihexadecylamine and dioctadecylamine N, N-dimethyloctylamine, N, N-dimethyl-n-
Decylamine, N, N-dimethyl-n-dodecylamine,
N, N-dimethyl-n-tetradecylamine, N, N-dimethyl-n-hexadecylamine, N, N-dimethyl-n-octadecylamine, N, N-dimethyl-n-eicosylamine, N, N Tertiary amines such as -dimethyl-n-docosylamine; aniline, pn-butylaniline, pt-butylaniline, pn-octylaniline, pn-decylaniline, pn-dodecylaniline, p -N-tetradecylaniline, diphenylamine, α-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 1-aminoanthraquinone, 4-aminobiphenyl, 2-aminobiphenyl, 6-aminochrysene, 3-
Aminofluorancene, 2-aminofluorene, 1-amino-9-fluorenone, 4-amino-9-fluorenone, 5-aminoindane, 5-aminoisoquinoline, 9
Aromatic amine compounds such as -aminophenanthrene.

In order to obtain a good liquid crystal alignment film, it is preferable to use an alkylamine or an aromatic amine compound having 1 to 30 carbon atoms, and further to use an alkylamine or an aromatic amine compound having 3 to 20 carbon atoms. preferable.

The polymer and the amine compound are usually 0 to 150 ° C,
The amine compound is reacted as it is or in a solution of an amine compound dissolved in the organic solvent in a solution in which the polymer is synthesized, preferably at 0 to 60 ° C.

The amount of the amine compound to be used is generally 0.01 to 5 equivalents, preferably 0.05 to 2 equivalents, based on the amide bond amount of the polymer used from the viewpoint of the orientation and stability of the liquid crystal alignment film.

The solution of the reaction product thus obtained is usually
Using the same organic solvent used for the reaction,
It is prepared and used in a solution of 0.05 to 20% by weight, preferably 1 to 15% by weight.

A liquid crystal display device using the alignment material of the present invention as a liquid crystal alignment film can be manufactured, for example, by the following method.

First, on a substrate having a transparent electrode, an alignment material for a liquid crystal display element is applied by a roll coater method, a spinner method, a printing method, etc. to form a coating film, and the coating film is formed at 80 to 200 ° C., preferably 120 to 200 ° C. At a temperature of 5 to 180 minutes, preferably 30 to 90 minutes
Dry for minutes.

The thickness of the coating after drying is usually 0.01 to 1 μm, preferably 0.01 to 0.5 μm.

When applying the alignment material for a liquid crystal display element, if necessary, in order to further improve the adhesiveness between the substrate and the liquid crystal alignment film, a silane coupling agent may be previously provided on the substrate.
A titanium coupling agent or the like can be applied.

Further, as the substrate used for the liquid crystal display element, a transparent substrate made of float glass, soda glass or a polyester film such as flexible polyethylene terephthalate or polybutylene terephthalate, and further made of polyethersulfone, polycarbonate, other plastic films, etc. Can be used, and as the transparent electrode,
A NESA film made of SnO ₂ and an ITO film made of In ₂ O ₃ -SnO ₂ can be used.For patterning of these transparent electrodes,
A photoetching method or a method using a mask in advance is used.

The coating film thus obtained is rubbed with a roll around which a cloth made of synthetic fiber such as nylon is wound, and is subjected to a liquid crystal alignment treatment.

Next, the pair of substrates processed as described above is sealed with a sealant in a state where a predetermined interval is provided so that the rubbing directions are orthogonal or antiparallel, and a liquid crystal is filled between the two substrates. The filling port is sealed with a sealant to form a liquid crystal cell, and orthogonal or parallel polarizing plates are pressure-bonded to both surfaces of the cell to obtain a liquid crystal display element.

As the sealing agent, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as a spacer can be used. The cell thickness of the liquid crystal display element is usually 0.5 to 20 μm, and the size of the spacer is selected and used so that the cell thickness falls within this range.

The liquid crystal used for the liquid crystal display element is not particularly limited as long as it has a positive dielectric anisotropy, but is preferably a liquid crystal that forms a nematic liquid crystal, such as a Schiff base liquid crystal, an azoxy liquid crystal, and a biphenyl liquid crystal. Phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, and cubane liquid crystal.

These liquid crystals are usually used as a mixture,
It may be used alone.

Further, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate and cholesteryl carbonate, and trade names C-15, CB-15
A chiral agent or the like sold as (manufactured by British Drug House) can also be used.

Also, p-decyloxybenzylidene-p'-amino-
Ferroelectric liquid crystals such as 2-methylbutylcinnamate (DOBAMBC) can also be used.

Further, as the sealant, there are an organic sealant and an inorganic sealant, and the organic sealant is particularly preferable because it can be operated at a low temperature.

Examples of the polarizing plate used outside the liquid crystal cell include a polarizing plate in which a polarizing film called an H film, in which polyvinyl alcohol is stretched and oriented while absorbing iodine, is sandwiched by a cellulose acetate protective film or a polarizing plate made of the H film itself. Can be mentioned.

A liquid crystal display device using the alignment material of the present invention as a liquid crystal alignment film is used for any liquid crystal display of an SBE display device, a TN type display device, or a ferroelectric liquid crystal display device by selecting a liquid crystal to be used. be able to.

[Examples] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 19.83 g of 4,4'-diaminodiphenylmethane was dissolved in 380.25 g of γ-butyrolactone, 22,2.4 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride was added with stirring, and the mixture was reacted at 60 ° C. for 4 hours. To synthesize polyamic acid.
Furthermore, 422.5 g of γ-butyrolactone and pyridine 4.
After adding 0 g and 5.1 g of acetic anhydride and reacting at 130 ° C. for 5 hours, by-produced acetic acid and pyridine were scattered under reduced pressure to obtain a polymer solution having a solid concentration of 5% by weight. Next, a part of the solution was poured into methanol to precipitate a product, which was dried under reduced pressure to obtain a solid polymer.The solid polymer was dissolved in deuterated dimethyl sulfoxide, and the ¹ H-NMR spectrum was measured. However, the ratio of imide bonds and amide bonds was 30/70. The intrinsic viscosity of the polymer measured in γ-butyrolactone was 0.86 dl / g.

Next, diphenylamine was added to 845 g of the obtained polymer solution.
34.72 g was added and reacted at room temperature for 20 hours with stirring.

After passing the solution of the reaction product thus obtained through a 1 μm membrane filter,
The solution was applied on a glass substrate having a transparent electrode made of an ITO film by a spin coating method, and further dried at 180 ° C. for 30 minutes to obtain a coating film having a thickness of 0.08 μm. The resulting coating film had excellent transparency, a refractive index of 1.64, and a transmittance of visible light of 0.1 μm equivalent film thickness of 98% or more. Next, the coated surface of the substrate was subjected to a rubbing treatment in one direction using a nylon cloth, but no peeling or damage of the film due to electrostatic breakdown was observed.

A pair of upper and lower substrates subjected to the rubbing treatment are bonded with an epoxy resin containing a sealant so that the rubbing directions are orthogonal to each other, and a phenylcyclohexane-based liquid crystal is injected between the substrates through a liquid crystal injection port, sealed, and sealed outside the cell. A polarizing plate was bonded on both sides such that the polarizing direction of the polarizing plate coincided with the rubbing direction of the liquid crystal alignment film applied to each substrate, thereby producing a liquid crystal display device. Observation with a polarizing microscope revealed that the obtained liquid crystal display element was well oriented. In addition, when the light was turned off, no ITO wiring was observed.

Examples 2 to 4 In the same manner as in Example 1, a polyamic acid was synthesized using 19.83 g of 4,4'-diaminodiphenylmethane and 22.42 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride. Further, the reaction was carried out in the same manner as in Example 1 using acetic anhydride and pyridine shown in Table 1, and a polymer having an imide bond and an amide bond in the ratio shown in Table 1 was synthesized.

Next, a certain amount of γ-butyrolactone and ethylene glycol were added to the obtained polymer to prepare a 5% by weight solution of γ-butyrolactone and ethylene glycol in a weight ratio of 80:20. Further, 1 equivalent of n-butylamine with respect to the amount of carboxyl group of the polyamic acid was added and reacted at room temperature for 20 hours to obtain an alignment agent for a liquid crystal display device.

Using the obtained alignment agent, a liquid crystal display device was prepared and evaluated in the same manner as in Example 1. No peeling or damage of the film due to electrostatic breakdown at the time of rubbing was observed, and the alignment of the liquid crystal was very low. Good, and no wiring was observed.

Example 5 An alignment material for a liquid crystal display element of the present invention was obtained in the same manner as in Example 1, except that α-naphthylamine was used instead of diphenylamine used in Example 1.

Next, a liquid crystal display device was prepared and evaluated in the same manner as in Example 1 using the obtained alignment material. No peeling or damage of the film due to electrostatic breakdown at the time of rubbing was observed, and the alignment of the liquid crystal was not observed. Good, and no wiring was observed.

Comparative Example 1 An alignment material for a liquid crystal display device was obtained in the same manner as in Example 1, except that the diphenylamine used in Example 1 was not used. Using the obtained alignment material, a liquid crystal display element was prepared and evaluated in the same manner as in Example 1. As a result, peeling or damage of the film due to electrostatic breakdown at the time of rubbing was observed, and wiring was also observed.

Comparative Example 2 A polyamic acid was synthesized in the same manner as in Example 1 to obtain a polyamic acid solution having a solid content of 5% by weight. Using the obtained solution as an alignment material, a liquid crystal display device was prepared and evaluated in the same manner as in Example 1. As a result, peeling or damage of the film due to electrostatic breakdown during rubbing was observed, and wiring was also observed. Was.

[Effects of the Invention] The alignment material for a liquid crystal display device comprising a reaction product of the specific polymer of the present invention and an amine compound has excellent stability,
A liquid crystal alignment film having excellent liquid crystal alignment properties and transparency can be obtained simply by drying at a temperature of 0 ° C. or lower. Further, the alignment material of the present invention does not show peeling or damage of the film due to electrostatic breakdown at the time of rubbing, and can arbitrarily increase the refractive index of the film,
Further, it is suitable for manufacturing a good liquid crystal display element having no visible wiring.

Continuation of front page (56) References JP-A-62-262829 (JP, A) JP-A-59-142526 (JP, A) JP-A-62-98327 (JP, A)

Claims (1)

(57) [Claims] An imide bond and an amide bond are synthesized by subjecting a reaction product of an alicyclic tetracarboxylic acid and a diamine to dehydration and ring closure in an organic solvent in the presence of a dehydrating agent and a basic catalyst. The reaction product of a polymer having an intrinsic viscosity ηinh (concentration 0.5 g / 100 ml, solvent γ-butyrolactone, measuring temperature 30 ° C.) of 0.05 to 20 dl / g and an amine compound having a ratio of An alignment material for a liquid crystal display element, which is dissolved in an organic solvent at a solid concentration of 0.05 to 20% by weight.