JPH08248423A - Material for liquid crystal oriented film - Google Patents

Abstract

PURPOSE: To obtain a good voltage holding characteristics even when a liquid crystal is driven at high temp. by incorporating a resin containing a polyimide resin and a specified polymer as an essential resin component. CONSTITUTION: This material contains a resin as the essential resin component which contains a polyimide resin (A) and a polymer (B) comprising monomers having ethylenically unsatd. double bonds as the structural component of (B). The two different kinds of resin segments (A), (B) which constitute the essential resin component are called as a polyimide segment and a vinyl polymer segment, respectively. The polyimide segment is synthesized not by a special method. For example, tetracarboxylic acid and diamine compd. are compounded with an org. solvent to obtain a polyamic acid, from which the objective polyimide is synthesized. The vinyl polymer segment is also synthesized by using compds. which can be synthesized by a well-known method or using available industrial products, and the segment is synthesized by radical or block copolymn. of monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a liquid crystal alignment film, and more particularly to a material for a liquid crystal alignment film capable of obtaining a good voltage holding characteristic even when driven at high temperature.

[0002]

2. Description of the Related Art A liquid crystal display element is a display element utilizing electro-optical changes of liquid crystal, and is used in various fields such as calculators, electronic timepieces, personal computers and televisions.

At present, twisted nematic type and super twisted nematic type liquid crystal display elements are known. In these liquid crystal display elements,
It is important to align the major axis of the liquid crystal molecules used in a certain direction.

Generally, in order to control the orientation of the liquid crystal molecules, a polyimide thin film excellent in orientation and chemical stability, especially a rubbed polyimide thin film is used as a liquid crystal orientation film. The polyimide used for this purpose is tetracarboxylic acid, tetracarboxylic acid monoanhydride, tetracarboxylic acid dianhydride, tetracarboxylic acid monoester, tetracarboxylic acid diester, tetracarboxylic acid triester, tetracarboxylic acid tetraester. It is synthesized by reacting a tetracarboxylic acid such as an ester with a diamine compound.

As a method for forming a polyimide thin film, which is a liquid crystal alignment film, on an electrode substrate for a liquid crystal display device, first, a polyamic acid or polyamic acid ester which is a precursor of a desired polyimide is prepared, and then the polyamic acid or polyamic acid is used. A method of applying a solution of a polyamic acid ester to a substrate and then heating it to 200 to 350 ° C. to volatilize an organic solvent and cause dehydration ring closure of the polyamic acid or polyamic acid ester to cause an imidization reaction, which is excellent in heat resistance. A method is known in which after obtaining a polyimide soluble in an organic solvent, a solution prepared by dissolving the polyimide in a suitable solvent is applied to a substrate and then heated to volatilize the organic solvent to form a thin film.

In recent years, an active matrix type liquid crystal display element (hereinafter referred to as AM-LCD), which is expected to become the mainstream of LCD panels in the future, has been developed, and it is possible to display moving images with clear images and fast movement. It's coming. However, in the AM-LCD, if the voltage applied to each pixel is not held for the frame period, the display quality is significantly deteriorated. Therefore, the voltage holding ratio showing this characteristic is an important characteristic as a liquid crystal alignment film material.

In the liquid crystal display element in which the liquid crystal occupies most of the space between the electrodes, the most important factor affecting the voltage holding ratio is the molecular structure and purity of the liquid crystal material, but the liquid crystal alignment film also has a large influence. It is known that the liquid crystal alignment film material produced by the latter method has a higher voltage holding ratio than the liquid crystal alignment film material produced by the former method.

However, these liquid crystal alignment film materials have a problem that the voltage holding ratio decreases as the temperature of the liquid crystal display element rises. To solve these problems, for example, JP-A-2-287324 and JP-A-5-34
As described in Japanese Patent No. 1291, a method of obtaining excellent voltage holding characteristics by using a polyimide resin using a tetracarboxylic acid anhydride or diamine compound having a unique structure as a raw material for a liquid crystal alignment film is known. Proposed.

However, since a compound having a special structure must be used as a raw material, the combination of the tetracarboxylic acid and the diamine compound is limited, and the desired liquid crystal alignment film characteristics may not be obtained.

[0010]

The present invention is based on such a technical background and can be synthesized without using a tetracarboxylic acid or diamine compound having a special structure as a raw material, and is high even at high temperature. It is an object of the present invention to provide a material for a liquid crystal alignment film that can obtain a voltage holding ratio.

[0011]

Therefore, the present inventors have completed the present invention as a result of repeated originality studies in view of the current state of the drawbacks of the prior art as described above.

That is, the present invention contains a resin containing a polyimide resin (A) and a polymer (B) containing a monomer having an ethylenically unsaturated double bond as a constituent component as an essential resin component. The present invention relates to a liquid crystal alignment film material, preferably a liquid crystal alignment film material, wherein the monomer having an ethylenically unsaturated double bond is a monomer having a (meth) acryloyl group.

The liquid crystal alignment film material of the present invention is an essential resin component containing a resin containing a polyimide resin (A) and a polymer (B) having a monomer having an ethylenically unsaturated double bond as a constituent component. Contained as.

This essential resin component is hereinafter abbreviated as the copolymer resin of the present invention. The two different types of resin segments (A) and (B) constituting this essential resin component will be abbreviated as the polyimide segment of the present invention and the vinyl polymer segment of the present invention, respectively.

In the present invention, the polyimide resin is a general term for polyimide and its precursor.
That is, in addition to the completely imidized resin, the precursor polyamic acid and the polyamic acid partially imidized are included.

One of the two different types of resin segments constituting the copolymer resin of the present invention is the polyimide segment of the present invention. There is no special point in the methodological synthesis of this polyimide segment, for example, tetracarboxylic acids and a diamine compound, with the objective polyimide composition via a polyamic acid compounded in a ratio of the intended polyimide composition using an organic solvent. A known polyimide synthesizing method such as a method for synthesizing a polyimide to be used can be used. Further, industrial products such as polyimide resins that can be obtained as the polyimide segment of the present invention can be used.

The tetracarboxylic acids used to obtain the polyimide segment of the present invention are not particularly limited, but for example, pyromellitic acid, 2, 3,
6,7-naphthalene tetracarboxylic acid, 1,2,5,6
-Naphthalene tetracarboxylic acid, 1,4,5,8-naphthalene tetracarboxylic acid, 2,3,6,7-anthracene tetracarboxylic acid, 1,2,5,6-anthracene tetracarboxylic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 2,3,3 ', 4-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3', 4,4'-benzophenonetetracarboxylic acid , Bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) methane,
2,2-bis (3,4-dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2
-Bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane,
Bis (3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,
6-bis (3,4-dicarboxyphenyl) pyridine,
Ethylene glycol bis (trimellitic acid), 1,3-
Propanediol bis (trimellitic acid), 1,4-butanediol bis (trimellitic acid), 1,5-pentanediol bis (trimellitic acid), 1,6-hexanediol bis (trimellitic acid), 1, Aromatic tetracarboxylic acids such as 8-octanediol bis (trimellitic acid), 1,10-decanediol bis (trimellitic acid), and 1,16-hexadecanediol bis (trimellitic acid), and monoanhydrides thereof. , Dianhydride, monoalkyl ester, dialkyl ester, trialkyl ester, tetraalkyl ester; 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3
-Cyclohexene-1,2-dicarboxylic acid, bicyclo [2,2,1] heptane-2,3,5,6-tetracarboxylic acid, 1-alkyl-bicyclo [2,2,1] heptane-2,3 5,6-tetracarboxylic acid, 1,2,3
4-cyclobutanetetracarboxylic acid, 1,2,3,4-
Cyclopentane tetracarboxylic acid, 1,2,4,5-cyclohexane tetracarboxylic acid, 2,3,5-tricarboxycyclopentyl acetic acid, 3,4-dicarboxy-
1,2,3,4-tetrahydro-1-naphthalene succinic acid, bicyclo [2,2,2] oct-7-ene-2,
3,5,6-tetracarboxylic acid, 3,5,6-tricarboxynorbornane-2-acetic acid, decahydronaphthalene-1,4,5,8-tetracarboxylic acid, 4,8-dimethyl-1,2, Alicyclic rings such as 3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid and 3,3'-bicyclohexyl-1,1 ', 2,2'-tetracarboxylic acid Formula tetracarboxylic acids and their monoanhydrides, dianhydrides, monoalkylesters, dialkylesters, trialkylesters, tetraalkylesters; 1,2,3,4-butanetetracarboxylic acid, 2,
Examples thereof include alicyclic tetracarboxylic acids such as 2,6,6-heptanetetracarboxylic acid and monoanhydrides, dianhydrides, monoalkyl esters, dialkyl esters, trialkyl esters and tetraalkyl esters thereof. It goes without saying that these tetracarboxylic acids mentioned above may be used alone or in combination of two or more kinds. Among these, tetracarboxylic acids having an alicyclic structure or an aliphatic structure as described above are preferable, and among these tetracarboxylic acids having an alicyclic structure or an aliphatic structure, 5- (2,5-dioxotetrahydro) -3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, bicyclo [2,2,1] heptane-2,
More preferred are 3,5,6-tetracarboxylic acids, 1,2,3,4-cyclobutanetetracarboxylic acids and 2,3,5-tricarboxycyclopentyl acetic acids.

The diamine compound used to obtain the polyimide segment of the present invention is not particularly limited, but examples thereof include o-, m- and p-phenylenediamine, 2,4-diaminotoluene and 1,4. -Diamino-2-methoxybenzene, 2,5-diaminoxylene, 1,3-diamino-4-chlorobenzene, 1,4-
Diamino-3-chlorobenzene, 1,4-diamino-
2,5-dichlorobenzene, 1,4-diamino-2-bromobenzene, 1,3-diamino-4-isopropylbenzene, 1,4-diamino-2-chloro-5-methylbenzene, 5-nitro-m- Phenylenediamine, 4,
4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diamino-3,3 ',
5,5'-tetramethyldiphenylmethane, 4,4'-
Diamino-3,3 ', 5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 4,4'- Diamino-3,3 '
-Dimethyl-5,5'-diethyldiphenylmethane,
4,4'-diamino-2,2 ', 3,3'-tetrachlorodiphenylmethane, 4,4'-diamino-3,3'-
Dichlorodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl-2,2-
Propane, 4,4'-diaminodiphenyl ether,
3,4'-diaminodiphenyl ether, 4,4'-diamino-3,3'-dimethyldiphenyl ether, 4,
4'-diamino-3,3'-diethyldiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 3,3 ', 5 5'-tetramethyl-4,4'-diaminobiphenyl, 3,3 ', 5,5'-tetraethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2 , 2 ', 5,
5'-tetrachloro-4,4'-diaminobiphenyl,
2,2'-dichloro-4,4-diamino-5,5'-dimethoxybiphenyl, benzidine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4- Bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1 , 3-bis (3-aminophenoxy) benzene, 1,4-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1
-(4-Aminophenyl) -1-methylethyl] benzene, trimethylene glycol-bis- (4-aminobenzoate), 1,2-bis (2-aminophenylthio)
Ethane, 4,4'-diaminobenzanilide, 9,10
-Bis (4-aminophenyl) anthracene, 9,9-
Bis (4-aminophenyl) -10-hydroanthracene, 9,9-bis (4-aminophenyl) fluorene,
o-Tolidine sulfone, 2,2'-diaminostilbene, 4,4'-diaminostilbene, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,5-diamino Aromatic diamine compounds such as naphthalene and 3,4'-diaminobenzanilide;4,4'-diaminodiphenylhexafluoropropane,3,3'-diaminodiphenylhexafluoropropane, 2,2-bis [4-
(4-Aminophenoxy) phenyl] hexafluoropropane, 4,4′-bis-2- (4-aminophenoxyphenylhexafluoroisopropyl) diphenyl ether, 2,2-bis- (3-amino-4,5-dimethylphenyl ) Fluorine-containing diamine compounds such as hexafluoropropane, 2,2'-trifluorodimethyl-4,4'-diaminobiphenyl; 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-
Diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 1,3
-Diaminomethylbenzene, 1,4-diaminomethylbenzene, 1,3-diaminomethylcyclohexane, 1,
4-diaminomethylcyclohexane, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4′-dimethylheptamethylenediamine, isophoronediamine, Tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene dimethylenediamine, 3 (4), 8 (9) -bis (aminoethyl) tricyclo [5,2,1,0 ^2,6 ] Aliphatic or alicyclic diamine compounds such as decane; general formula (V)

[0019]

Embedded image

(Wherein R "represents an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a cycloalkyl group such as a cyclohexyl group; an aromatic group or an alkenyl group such as a phenyl group, and m is 1 ~ 4 integer, n is 1
Represents an integer of 20), and a general formula (VI)

[0021]

[Chemical 6]

(Wherein R ″ is the same as above, n is 1 to 20)
Represents an integer) and a diaminoorganosiloxane compound and the like. It goes without saying that these diamine compounds described above may be used alone or in combination of two or more.

The ratio of the tetracarboxylic acid and the diamine compound used in the present invention is such that the amount of the diamine compound is 50 to 200 mol%, preferably 80 to 120 mol% with respect to the amount of the tetracarboxylic acid. When it is used in an amount of 50 mol% or less or 200 mol% or more, the molecular weight of the obtained polyimide is low and it is difficult to form a thin film.

The organic solvent that can be used when synthesizing the polyimide segment of the present invention is not particularly limited, and for example, 1-methyl-2-pyrrolidone, 1-acetyl-2-pyrrolidone, N, N-dimethylacetamide. ,
An aprotic polar solvent such as N, N-dimethylformamide, N, N-diethylformamide, pyridine, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, dimethylsulfone, hexamethylphosphoramide, N-methyl-ε-caprolactam. M-cresol,
Phenol solvents such as xylenol, phenol, halogenated phenol, etc. may be mentioned.

There is no particular limitation on the solid content concentration with respect to the organic solvent when the polyimide segment of the present invention is synthesized,
Usually 0.1 to 40% by weight, preferably 1 to 35% by weight
Is.

When synthesizing the polyimide segment of the present invention, a basic compound such as triethylamine, pyridine or lutidine; a dehydrating agent such as acetic anhydride, propionic anhydride or trifluoroacetic anhydride is used as a reaction catalyst. it can. It is also possible to accelerate the dehydration ring closure reaction by azeotropically removing water generated by the dehydration ring closure reaction from the reaction system by adding an appropriate amount of benzene, toluene, xylene or the like.

The polyimide segment of the present invention is synthesized from the above-mentioned tetracarboxylic acids and diamine compound. At that time, it passes through a polyamic acid as its precursor, but the imide conversion rate from the polyamic acid may be less than 100% for the purpose of adjusting the solubility of the polyimide or the adhesion to the substrate to be coated. it can.

In the polyimide segment of the present invention,
The logarithmic viscosity represented by the relational expression η _{inh =} (ln η _rel ) / c (wherein, η _rel represents relative viscosity and c represents concentration) is usually in 1-methyl-2-pyrrolidone at 30 ° C., c = 0.
It is 0.05 to 5 dl / g, preferably 0.05 to 3 dl / g under the condition of 5 g / dl.

The other of the two different types of resin segments constituting the copolymer resin of the present invention is the vinyl polymer segment of the present invention. The polymer chain in the vinyl polymer segment of the present invention may be any of a homopolymer, a random copolymer, an alternating copolymer, a block copolymer or a graft copolymer.

There is no special methodological point in the synthesis of the vinyl polymer segment of the present invention, and compounds which can be synthesized by a known method in common use and available industrial products can be used. It can be synthesized by radical, cation or anion homopolymerization, copolymerization or block copolymerization of a polymer. Of course, the polymerization means may be either thermal polymerization or photopolymerization.

The homopolymers, random copolymers, alternating copolymers, block copolymers or graft copolymers that can be used as the polymer chains in the vinyl polymer segment of the present invention are not particularly limited. But not
For example, polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene propylene copolymer, polybutylene-1, polyisobutylene or polyolefin such as poly-4-methylpentene-1; polybutadiene, polyisoprene, butadiene isoprene copolymer,
Examples thereof include polydienes such as styrene-butadiene copolymer, styrene-butadiene-styrene block copolymer or styrene-isoprene-styrene block copolymer, and graft copolymers using a silicon-containing (meth) acryloyloxy type macromonomer.

Further, for example, methyl (meth) acrylate,
Ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, hydroxyethyl (meth) acrylate,
2-Methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate,
Various (meth) acrylates such as (meth) acryloyloxy type macromonomers containing benzyl (meth) acrylate or silicon; Various aromatic vinyl monomers such as styrene, α-methylstyrene or p-methylstyrene Vinyl pyridine, vinyl imidazole,
Heterocyclic vinyl monomers such as vinylpyrrolidone or vinylcarbazole; various amide bond-containing vinyl monomers such as (meth) acrylamide or N-methoxymethyl (meth) acrylamide; (meth) acrylonitrile, vinyl acetate, etc. Alternatively, carboxyl group-containing vinyl monomers such as (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid; epoxy group-containing vinyl monomers such as glycidyl (meth) acrylate or β-methylglycidyl (meth) acrylate. Homopolymers obtained by polymerizing monomers such as vinyl monomers such as diesters of unsaturated dicarboxylic acids such as maleic acid or fumaric acid and monohydric alcohols having 1 to 7 carbon atoms, or Copolymers may also be mentioned.

Among these, the monomer having an ethylenically unsaturated double bond is preferably a monomer having a (meth) acryloyl group. Examples of the monomer having a (meth) acryloyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and hexyl (meth) acrylate. , 2-ethylhexyl (meth) acrylate,
Various (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate or benzyl (meth) acrylate. Various amide bond-containing vinyl monomers such as (meth) acrylamide or N-methoxymethyl (meth) acrylamide; (meth) acrylonitrile; Monomers such as silicon-containing (meth) acryloyloxy macromonomers Is mentioned. Examples of the polymer having a monomer having an ethylenically unsaturated double bond of the present invention as a constituent component include a homopolymer or a copolymer obtained by polymerizing the above-mentioned monomer.

The number average molecular weight of the polymer chain in the vinyl polymer segment of the present invention is not particularly limited, but is 200 to 500,000, preferably 400 to 200,000. The polydispersity (Mw / Mn) of the polymer chains in the vinyl polymer segment of the present invention is almost or exactly between 1 and 10, and a dispersion having a molecular weight distribution peak of 1 peak or 2 peaks or more, preferably The polydispersity is 1 to 6 and the molecular weight distribution has one peak. However, it is also possible to apply a polymer chain having a molecular weight distribution of two peaks or more to express special properties.

The copolymer resin of the present invention contains the above-mentioned polyimide segment of the present invention and the vinyl polymer segment of the present invention in its resin structure. There is no particular methodological point in the synthesis of the copolymer resin of the present invention, and the copolymer resin can be synthesized by a known method.

For example, one or more functional groups capable of reacting with the polyimide segment of the present invention may be bonded to the polymer chain of the vinyl polymer segment of the present invention, and then reacted with the polyimide segment of the present invention.

Examples of the functional group capable of reacting with the polyimide segment of the present invention include a hydroxy group, a carboxyl group, a chloroformyl group, an amino group, an isocyanate group, and a functional group containing an acid anhydride structure. There is no particular methodological point in the synthesis of the polymer having these functional groups, and the polymer can be synthesized by a known method. For example, copolymerization of a monomer having a functional group, chain transfer polymerization using a radical chain transfer agent having a functional group or introduction of a functional group to a molecular chain terminal by polymerization using a radical polymerization initiator having a functional group, Examples thereof include polymerization using an anionic polymerization initiator having a functional group and introduction of a functional group to the end of a molecular chain by endcapping an anionic polymerization growth end with a terminating agent having a functional group.

In the synthesis of the copolymer resin of the present invention,
It may be synthesized by introducing a functional group capable of initiating polymerization into the polymer chain of the polyimide resin and then polymerizing a monomer having an ethylenically unsaturated double bond in the presence thereof.

Examples of the functional group capable of initiating the polymerization introduced into the polymer chain of this polyimide resin include thermal polymerization initiation groups such as peroxy group and azo group; intramolecular bond cleavage type light typified by acetophenone derivatives. Examples thereof include a polymerization initiation group and a photopolymerization initiation group such as an intermolecular hydrogen abstraction type photopolymerization initiation group represented by a benzophenone derivative or a benzoin derivative.

The copolymer resin of the present invention can be separated from the reaction product by a known technique after the synthetic reaction by the above-mentioned method. For example, precipitation method, evaporation method, extraction, dipping, chromatograph, etc. can be used. In particular,
The reaction system is a polymer having a monomer having an unreacted ethylenically unsaturated double bond or a monomer having an ethylenically unsaturated double bond that has not reacted with the polyimide segment of the present invention as a constituent component. If it remains, reprecipitation purification can be carried out using an appropriate solvent that does not dissolve the copolymer resin of the present invention but only other unreacted substances. If the copolymer resin of the present invention contains no unreacted material, this step can be omitted as a matter of course.

The ratio of the two different types of resin segments constituting the copolymer resin of the present invention is not particularly limited, but 50 parts of the polyimide segment of the present invention is added to the total amount of both.
˜99.9% by weight is preferable, and 60 to 99% by weight is more preferable. The polyimide segment of the present invention is 99.9.
When it is more than wt%, the obtained voltage holding ratio becomes slightly insufficient at high temperature. Further, when the polyimide segment of the present invention is 50% by weight or less, the voltage holding ratio at high temperature obtained is good but the glass transition point is lowered, so that the physical properties of the coating film required at the time of producing a liquid crystal display device are slightly insufficient. Become.

The copolymer resin of the present invention may be used as a mixture with a polyimide resin having the same structure as the polyimide segment of the present invention or a polyimide resin having another structure compatible with the copolymer resin of the present invention. it can.

Since the material for a liquid crystal alignment film of the present invention is made into a thin film, the solid content concentration is usually 0.1 to 30% by weight, preferably 0.1% by weight, obtained by dissolving the copolymer resin of the present invention in an organic solvent.
Prepared as a 5-20% by weight solution. The solvent for this preparation, the organic solvent used in the synthesis of the polyimide segment of the present invention described above, alcohols, ketones, esters, ethers, halogenated hydrocarbons, organic solvents such as hydrocarbons Among them, a single solvent or a mixed solvent of two or more kinds is used within a range in which the copolymer resin of the present invention is not precipitated at a target concentration.

The advantages of the liquid crystal alignment film material according to the present invention are:
Firstly, it has a high voltage holding property even at a high temperature, and secondly, it is possible to obtain a liquid crystal alignment film having a desired property without being restricted by the combination of the tetracarboxylic acid and the diamine compound.

[0045]

EXAMPLES Next, in order to explain the present invention in more detail, synthesis examples, examples, comparative examples and application examples will be given.

Synthesis Example 1 (Synthesis of polymethylmethacrylate having amino group at one end) Methacrylic acid methyl ester (hereinafter abbreviated as MMA) 1
00 g, cysteamine hydrochloride 22.7 g and azobisisobutyronitrile (hereinafter abbreviated as AIBN) 1.5 g were dissolved in dimethylformamide 290 g and reacted at 85 ° C. for 3 hours while flowing nitrogen. The reaction solution was poured into hexane for precipitation, and reprecipitation purification was performed with chloroform / hexane and acetone / water to obtain 35 g of a white powder.

As a result of ¹ H-NMR analysis, it was confirmed that this was polyMMA having an amino group at one end. Hereinafter, this polymer is abbreviated as polymer (X).

Synthesis Example 2 (Synthesis of Methyl Methacrylate-Ethyl Acrylate Copolymer Having Amino Group at One Terminal) As monomers, 75 g of MMA and 24.8 g of acrylic acid ethyl ester (hereinafter abbreviated as EA) were used. Then, the experiment of Synthesis Example 1 was repeated, and MMA7 having an amino group at one end was
A copolymer composed of 5 mol% and 25 mol% EA was obtained. Hereinafter, this polymer is abbreviated as a polymer (Y).

Example 1 5- (2,5-dioxotetrahydro-3-furanyl)
2.1 g of -3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride (Dainippon Ink and Chemicals, trade name Epiclon B-4400, abbreviated as MCTC hereinafter) 2.1 g, polymer (X) 2.06 g And 0.1 g of pyridine are dissolved in 10 g of N-methylpyrrolidone (hereinafter abbreviated as NMP),
The reaction was carried out at 50 ° C. while flowing nitrogen to obtain a polyMMA solution having an acid anhydride group at one end. Next, 7.93 g of diaminodiphenylmethane (hereinafter abbreviated as DDM) was added to N
After dissolving in 96.5 g of MP and adding 8.68 g of MCTC little by little while flowing nitrogen and reacting for 5 hours at room temperature, the whole amount of the above polyMMA solution was added and reacted for 12 hours to contain a polyMMA segment. A solution of polyamic acid was obtained. Next, 16.3 g of acetic anhydride and 1 of pyridine
6.3 g of the mixed solution was added, and the mixture was reacted at 50 ° C. for 3 hours to complete imidization. The reaction solution was poured into methanol and the precipitated solid content was dried to obtain a polyimide-polyMMA copolymer containing 10% by weight of polyMMA segment. This copolymer was dissolved in γ-butyrolactone to prepare a solution having a solid content of 4% by weight, and then filtered through a 1 μm membrane filter to obtain a liquid crystal alignment film evaluation sample.

Example 2 The same experiment as in Example 1 was repeated except that the amount of the polymer (X) was increased to 4.32 g, and the poly MMA segment was added to 2 parts.
A polyimide-polyMMA copolymer containing 0% by weight was obtained.
Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Example 3 A solution of the polyamic acid containing the polyMMA segment synthesized in Example 1 was poured into methanol as it was without imidization, purified by reprecipitation, and dried to obtain a polyamic acid containing the polyMMA segment. It was This polymer was dissolved in γ-butyrolactone at a concentration of 4% by weight and filtered through a 1 μm membrane filter to prepare a sample for liquid crystal alignment film.

Example 4 In the same manner as in Example 1, 7.93 g of DDM and MCTC1
After 0.78 g of NMP94 g was used as a solvent to synthesize a polyamic acid, 2.06 g of polymer (X) was added and the reaction was continued at room temperature for 12 hours. Subsequently, the imidization reaction was carried out in the same manner as in Example 1 to give 10 parts of polyMMA segment.
A polyimide-polyMMA copolymer containing wt% was obtained. Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Example 5 The experiment of Example 1 was repeated except that 2.06 g of the polymer (Y) was used instead of the polymer (X), and the MMA-EA copolymer (MMA mol 75%, EA 25 mol%) was used. A polyimide-poly (MMA / EA) copolymer containing 10% by weight of the segment was obtained. Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Example 6 2.1 g of MCTC, 0.31 g of 2,2′-azobis [2- (hydroxymethyl) propionitrile] (manufactured by Wako Pure Chemical Industries, trade name VF-077) and 0.1 g of pyridine were added. 1-methyl-2-pyrrolidone (hereinafter abbreviated as NMP)
It was dissolved in 10 g and reacted at 40 ° C. while flowing nitrogen to obtain an azo initiator solution. Next, 7.93 g of diaminodiphenylmethane (hereinafter abbreviated as DDM) was added to NMP96.5.
g of MCTC, 8.68 g of MCTC was added little by little while flowing nitrogen, and the mixture was reacted at room temperature for 5 hours. Then, the entire amount of the azo initiator solution was added and reacted for 12 hours to obtain a polyamic acid containing polyMMA segment. An acid solution was obtained.
Next, a mixed solution of 16.3 g of acetic anhydride and 16.3 g of pyridine was added, and the mixture was reacted at 50 ° C. for 3 hours to complete imidization. Subsequently, 8.02 g of MMA was added thereto and polymerization was carried out at 80 ° C. for 5 hours. The reaction solution was poured into methanol and the precipitated solid content was dried to obtain a polyimide-polyMMA copolymer containing 10% by weight of polyMMA segment. Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Example 7 Bicyclo [2,2,1] heptane-2,3,5,6-tetracarboxylic dianhydride (hereinafter abbreviated as BHTCA)
1.9 g of the polymer (X) and 1.96 g of the polymer (X) were reacted at 50 ° C. with NMP as a solvent while flowing nitrogen to obtain a polyMMA solution having an acid anhydride group at one end. Then DDM 7.9
After dissolving 3 g in NMP94 g, BHTCA 7.7 g was added little by little while flowing nitrogen and reacted at room temperature for 5 hours, and then the whole amount of the polyMMA solution was added and reacted for 12 hours to obtain a polyamic acid containing a polyMMA segment. A solution of This reaction solution was dehydrated and imidized with a mixed solution of acetic anhydride and pyridine in the same manner as in Example 1, purified by reprecipitation with methanol, dissolved in γ-butyrolactone, filtered through a 1 μm membrane filter, and evaluated for a liquid crystal alignment film. Was prepared.

Example 8 1.9 g of BHTCA and 1.96 g of polymer (X) were added to NMP.
Was used as a solvent and was allowed to react at 50 ° C. while flowing nitrogen to obtain a polyMMA solution having an acid anhydride group at one end. Then D
DE8.01g is dissolved in NMP94g, BHTCA
Add 7.7 g little by little while circulating nitrogen, and add 5 at room temperature.
After reacting for a time, all the polyMMA solution was added and reacted for 12 hours to obtain a polyamic acid solution containing a polyMMA segment. This reaction solution was dehydrated and imidized with a mixed solution of acetic anhydride and pyridine and purified by reprecipitation with methanol in the same manner as in Example 1, and dissolved in γ-butyrolactone to give 1 μm.
The sample for liquid crystal alignment film evaluation was prepared by filtering with a membrane filter of m.

Example 9 1.50 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter abbreviated as CBDA) and polymer (X)
1.3 g of pyridine and 0.1 g of pyridine were reacted with 50 g of NMP as a solvent while flowing nitrogen at 50 ° C. to obtain a polyMMA solution having an acid anhydride group at one end.

Next, 2,2-bis [4- (4-aminophenoxy) phenylpropane (hereinafter abbreviated as BAP) 1
6.42 g of NMP was dissolved in 96.5 g of NMP, 6.50 g of CBDA was added little by little while passing nitrogen, and the mixture was reacted for 5 hours at room temperature. Then, the entire amount of the above polyMMA solution was added and reacted for 12 hours to obtain a polyamic acid containing a polyamic acid segment. An acid solution was obtained. This solution was diluted with NMP to a solid content concentration of 4% and filtered through a 1 μm membrane filter to obtain a liquid crystal alignment film evaluation sample.

Example 10 1.83 g of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (hereinafter abbreviated as TCA) and polymer (X)
50 with 1.96 g of NMP as a solvent while circulating nitrogen.
Poly (MMA) having acid anhydride group at one end
A solution was obtained. Next, 7.93 g of DDM was dissolved in 94 g of NMP, and 7.33 g of TCA was added little by little while flowing nitrogen and reacted at room temperature for 5 hours. Then, the entire amount of the above polyMMA solution was added and reacted for 12 hours to obtain a polyMMA segment. A solution of polyamic acid containing was obtained. This reaction solution was dehydrated and imidized with a mixed solution of acetic anhydride and pyridine in the same manner as in Example 1, purified by reprecipitation with methanol, dissolved in γ-butyrolactone, filtered through a 1 μm membrane filter, and evaluated for a liquid crystal alignment film. Was prepared.

Example 11 7.93 g of DDM was dissolved in 94 g of NMP to prepare MCTC1.
0.67 g was added little by little while flowing nitrogen and reacted at room temperature for 5 hours to synthesize a polyamic acid. Next, a mixed solution of 16.3 g of acetic anhydride and 16.3 g of pyridine was added, and the mixture was reacted at 50 ° C. for 3 hours to complete imidization. The reaction solution was poured into methanol, and the precipitated solid content was dried.
A polyimide containing DM and MCTC as constituent components was obtained.

To this, 25% by weight of a polyimide-polyMMA copolymer containing 20% by weight of the polyMMA segment synthesized in Example 2 was added, and the polymer mixture was mixed with γ.
A sample for liquid crystal alignment film was prepared by dissolving in butyrolactone at a concentration of 4% by weight and filtering with a 1 μm membrane filter.

Comparative Example 1 A sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1, using the polyimide containing DDM and MCTC synthesized in Example 10 as constituents.

Comparative Example 2 Comparative Example 1 except that 8.01 g of DDE was used instead of DDM and 9.45 g of BHTCA was used instead of MCTC.
A polyimide containing BHTCA and DDE as constituent components was obtained in the same manner as in. Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Comparative Example 3 16.41 g of BPA was dissolved in 94 g of NMP, 7.84 g of CBDA was added little by little while flowing nitrogen, and the mixture was reacted for 5 hours to synthesize a polyamic acid. This reaction solution is N
The sample was diluted with MP to a solid content concentration of 4% and filtered through a 1 μm membrane filter to obtain a liquid crystal alignment film evaluation sample.

Comparative Example 4 A polyimide having TCA and DDM as constituent components was obtained in the same manner as Comparative Example 1 except that 9.08 g of TCA was used instead of MCTC. Then, a sample for evaluating a liquid crystal alignment film was prepared in the same manner as in Example 1.

Application Example Using the polyimide solution and the polyamic acid solution prepared in Examples and Comparative Examples as the material for the liquid crystal alignment film, the pretilt angle and the voltage holding ratio were measured. In the production of the glass substrate used for this measurement, in the case of a polyimide solution, a glass substrate with an ITO transparent electrode was spin-coated using a spinner and then dried at 180 ° C. for 1 hour. In the case of a polyamic acid solution, spin coating was performed in the same manner, followed by heat treatment at 80 ° C. for 5 minutes and then at 180 ° C. for 1 hour to form a polyimide coating film.

The voltage holding ratio is TN with a cell gap of 5 μm.
A liquid crystal for a TFT "RDP-4021"
0 "(manufactured by Rodick) was injected, and measurement was performed in a high temperature bath at 23 ° C. and 70 ° C. under the conditions of a frame period of 16 milliseconds, a pulse width of 64 microseconds and an applied voltage of 4.5V.

The results are shown in Table 1.

[0069]

[Table 1]

[0070]

Since the material for liquid crystal alignment film of the present invention has a high voltage holding ratio even at high temperature, it is possible to manufacture a liquid crystal display device which is stable and can obtain a good display. Further, the liquid crystal alignment film material of the present invention, since it can be synthesized without using a tetracarboxylic acid or diamine compound having a special structure as a raw material, without being limited to a combination of a tetracarboxylic acid and a diamine compound, It has a remarkable effect that a liquid crystal alignment film having desired properties can be obtained.

Claims (8)

[Claims] 1. A liquid crystal alignment comprising a resin containing a polyimide resin (A) and a polymer (B) containing a monomer having an ethylenically unsaturated double bond as a constituent component as an essential resin component. Membrane material. 2. The material according to claim 1, wherein the monomer having an ethylenically unsaturated double bond is a monomer having a (meth) acryloyl group. 3. The material according to claim 1 or 2, wherein the polyimide resin (A) has an aliphatic structure and / or an alicyclic structure in the molecule. 4. The material according to claim 1, wherein the polyimide resin (A) has a structural unit represented by the following general formula (I) in the molecule. Embedded image (In the formula, R represents a divalent organic group) 5. The material according to claim 1, wherein the polyimide resin (A) has a structural unit represented by the following general formula (II) in the molecule. Embedded image (In the formula, R represents a divalent organic group, and R ′ represents a hydrogen atom or a lower alkyl group.) 6. The material according to claim 1, wherein the polyimide resin (A) has a structural unit represented by the following general formula (III) in the molecule. Embedded image (In the formula, R represents a divalent organic group) 7. The material according to claim 1, wherein the polyimide resin (A) has a structural unit represented by the following general formula (IV) in the molecule. [Chemical 4] (In the formula, R represents a divalent organic group) 8. The weight ratio of the polyimide resin (A) to the polymer (B) containing a monomer having an ethylenically unsaturated double bond as a constituent component is (A) / (B) = 99. 9/0.
The material according to any one of claims 1 to 7, which is 1 to 50/50.