JPH09176315A - Polyimide-based block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copolymer containing plural polyimide blocks having specific recurring unit in the molecule, having a plurality of good properties difficult to get at the same time by conventional means and useful as a constituent component of an agent for forming a liquid crystal orientation film. SOLUTION: This copolymer contains (A) a 1st polyimide block having a recurring unit of the formula I or the formula II (R<1> is a tetravalent organic group; Q<1> is a bivalent organic group; X is H or a univalent organic group; (m) and (n) are each the number of recurring units) and (B) a 2nd polyimide block bonded to the component A, having a structure different from that of the component A and containing a recurring unit of the formula III or the formula IV (R<2> is a tetravalent alicyclic group; Q<2> is a bivalent alicyclic group or a bivalent aromatic group; X is H or a univalent organic group; (p) and (q) are each the number of recurring units) and has a logarithmic viscosity (ηln) of 0.1-2dL/g. The copolymer can be produced e.g. by preparing a polyamic acid prepolymer having amino group on molecular terminal as a starting raw material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyimide block copolymer. More specifically, the present invention relates to a polyimide block copolymer which has an alicyclic group in the molecule, is soluble in various organic solvents, and is particularly suitable as a constituent component of a liquid crystal alignment film forming agent.

[0002]

2. Description of the Related Art At present, as a liquid crystal display element, a liquid crystal alignment film made of polyimide or the like is formed on the surface of a substrate provided with a transparent conductive film to form a substrate for a liquid crystal display element, and two of them are opposed to each other. A nematic liquid crystal layer having, for example, positive dielectric anisotropy is formed in the gap to form a cell having a sandwich structure, and the long axis of the liquid crystal molecule is continuous from one substrate to the other substrate. The so-called TN (Twisted Nemat)
A TN type liquid crystal display device having an ic) type liquid crystal cell is known. The orientation of the liquid crystal in the TN type liquid crystal display element is usually expressed by a liquid crystal orientation film that has been subjected to a rubbing treatment.

Recently, STNs are superior in contrast and visual characteristics to TN type liquid crystal display devices.
A (Super Twisted Nematic) type liquid crystal display device has been developed. In this STN type liquid crystal display element, a nematic liquid crystal substance blended with a chiral agent which is an optically active substance is used as a liquid crystal, and the long axis of the liquid crystal molecule is twisted continuously between substrates over 180 degrees The birefringence effect caused by However, when an STN type liquid crystal display device is manufactured using a conventional liquid crystal alignment film made of polyimide, the pretilt angle of the liquid crystal molecules developed by the liquid crystal alignment film is small, and therefore, the liquid crystal molecules are distributed between the substrates. It is difficult to continuously twist it over 180 degrees or more, and the obtained liquid crystal display element does not have a desired display function.

Therefore, in the STN type liquid crystal display element, a liquid crystal alignment film capable of obtaining a large pretilt angle is required. A large pretilt angle can be obtained by using, for example, a liquid crystal alignment film formed by oblique vapor deposition of silicon monoxide. However, this liquid crystal alignment film has a complicated manufacturing process and is suitable for mass production. There is a problem that it does not. On the other hand, also in the TN type liquid crystal display element, it has been desired to use a liquid crystal alignment film having a high pretilt angle in order to suppress a display defect due to a reverse tilt phenomenon when the cell is driven. Against the background of the above circumstances, it has been considered to use a polyimide exhibiting such characteristics as a material for a liquid crystal alignment film in order to develop a large pretilt angle of, for example, 3 degrees or more. Attempts have been made to use a polyimide having a group or a fluorine atom introduced therein.
However, in this technique, the introduction of such a special atom or atomic group reduces the polarity of the polyimide itself, so that the obtained liquid crystal alignment film has low adhesiveness to the substrate and imparts a liquid crystal alignment ability. There is a problem that the liquid crystal alignment film is peeled off from the substrate when the alignment treatment by rubbing is performed.

A liquid crystal alignment film made of polyimide is usually
A solution prepared by dissolving polyamic acid (polyamidecarboxylic acid) or soluble polyimide in an appropriate organic solvent is used as a liquid crystal alignment film forming agent, and this is applied to the surface of a substrate constituting a cell of a liquid crystal display element, and if necessary, It is formed by performing imidization treatment by heating to form a polyimide thin film, and subjecting this thin film to an orientation treatment such as a rubbing treatment. Further, with respect to the liquid crystal alignment film before or after the alignment treatment by the rubbing treatment or the like, an alignment characteristic correction process by irradiating a selected local region with radiation such as ultraviolet rays, that is, in the region,
The size of the pretilt angle of the liquid crystal molecules may be reduced, for example, compared to the other regions. However, by realizing the state in which regions having different pretilt angles are mixed in this way, the liquid crystal The display element has a low visual angle dependence in which the contrast varies depending on the viewing direction.
It will be of good quality.

At present, polyimide, which is used as a material for a liquid crystal alignment film forming agent, is required to have the following various characteristics in relation to its application and function, the method of forming a liquid crystal alignment film, and the like. Has been done. (A) A liquid crystal display element exhibits good alignment characteristics and a desired pretilt angle is obtained. (B) It has great durability against an alignment treatment such as a rubbing treatment. (C) Good coatability should be obtained. (D) High transparency. (E) High voltage holding ratio. (F) Flicker (flicker) when used as a liquid crystal display element
Be few. (G) Good storage stability. (H) To be able to easily perform the alignment characteristic modification process with high efficiency by irradiation with radiation.

[0007]

However, among the conventional polyimides, the above-mentioned properties are not satisfied in a well-balanced manner, and a polyimide having an excellent property does not have another property. Is normal.
In order to obtain a polyimide having a plurality of properties, it is also possible to use a mixture of a plurality of polyimides having different properties, but in this case, it is rare that those properties are expressed together, rather, each polyimide It is difficult to obtain good properties due to differences in physical properties and insufficient compatibility, and it is difficult to obtain high transparency, which is a property required for liquid crystal alignment films, etc. In the end, the purpose cannot be achieved because problems such as not being obtained occur.

Polyimide is usually produced by polycondensation reaction of tetracarboxylic dianhydride and diamine or diisocyanate. In order to obtain a polyimide having a plurality of different properties, for example, a plurality of diamines can be used. It is also conceivable to manufacture a polyimide by using the material. However, in the case of such a method, it is difficult to control the conditions of the polycondensation reaction,
It is not possible to easily produce a polyimide having desired properties.

The present invention has been made based on the above-mentioned conventional technical situation, and its purpose is to have a plurality of desired characteristics which are difficult to obtain simultaneously by ordinary means. Another object of the present invention is to provide a polyimide block copolymer which is particularly useful as a material for a liquid crystal alignment film.

[0010]

The polyimide-based block copolymer of the present invention comprises a first polyimide-based block and a structure in which the first polyimide-based block is combined with the first polyimide-based block and the structure of the first polyimide-based block is the same. A polyimide-based block copolymer containing a different second polyimide-based block in the molecule, wherein the first polyimide-based block has a repeating unit represented by the following formula 1 or formula 2, The second polyimide block has the following formula 3
Alternatively, it has a repeating unit represented by Formula 4, and has a logarithmic viscosity (ηln) of 0.1 to 2 dl / g.

[0011]

Embedded image

(In formulas 1 and 2, R ¹ represents a tetravalent organic group, Q ¹ represents a divalent organic group, X represents a hydrogen atom or a monovalent organic group, and m and n are Indicates the number of repeating units.)

[0013]

Embedded image

(In formulas 3 and 4, R ² represents a tetravalent alicyclic group, Q ² represents a divalent alicyclic group or a divalent aromatic group, and X represents a hydrogen atom or 1 Represents a valent organic group, and p and q represent the number of repeating units.)

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. In the present specification, the term “polyimide-based” is used as a concept including polyimide and polyamic acid. Thus, for example, the term "polyimide block copolymer" includes those including block copolymer type polyamic acid, polyimide block copolymer and polyimide-polyamic acid block copolymer, and "polyimide type block copolymer". The term "block" should be understood to include both polyamic acid blocks and polyimide blocks.
Further, in the present specification, the term "tetracarboxylic acids"
Is (i) a tetracarboxylic dianhydride in which two divalent carboxylic acid anhydride groups (-CO-O-CO-) are bonded to a tetravalent nuclear atomic group, and (ii) a tetravalent nuclear atom. -COO
A tetracarboxylic acid or a tetracarboxylic acid ester having a total of four X groups (X is a hydrogen atom or an organic group such as an alkyl group and an aryl group; the same applies below), (iii) tetravalent nucleus It is used as a concept that includes a tetracarboxylic acid monoanhydride or a tetracarboxylic acid ester monoanhydride in which one divalent carboxylic acid anhydride group and two -COOX groups are bonded to the atomic group in total. There is. In addition, in this specification, a "polyamic acid prepolymer" is also called an "amic acid oligomer", and a "polyimide prepolymer" is also called an "imide oligomer."

<Polyimide Block Copolymer> The polyimide block copolymer of the present invention comprises the first polyimide block having a repeating unit represented by the above formula 1 or 2 and the above formula 3 or formula 4. A second polyimide block having the repeating unit shown in the molecule. In Formula 1 and Formula 2 representing the repeating unit of the first polyimide-based block, R ¹ is a tetravalent organic group, and a tetravalent residue obtained by removing a carboxylic acid anhydride group or a —COOX group from a tetracarboxylic acid described below. It is a base. Q ¹ is a divalent organic group, which is a divalent residue obtained by removing an amino group from a diamine described below. The number of repeating units m and n is usually 3 to 2000, and preferably 3 to 100. In Formula 3 and Formula 4 showing the repeating unit of the second polyimide block, R
² is a tetravalent alicyclic group, which is a tetravalent residue obtained by removing a carboxylic acid anhydride group or a -COOX group from alicyclic tetracarboxylic acids described later. Q ² is a divalent alicyclic group or a divalent aromatic group, which is a divalent residue obtained by removing an amino group from the alicyclic diamine or aromatic diamine described below. The number of repeating units p and q is usually 2 to 1000, and preferably 2 to 100.
The polyimide-based block copolymer of the present invention comprises a ^second alicyclic group (R ² ) represented by the above formulas 3 and 4 and an alicyclic group or aromatic group (Q ² ) as an essential component. Since it has a polyimide block, when the polyimide block copolymer is applied as a material for a liquid crystal alignment film forming agent, it is required to exhibit a high voltage holding ratio and high transparency in the formed liquid crystal alignment film. You can

The polyimide-based block copolymer of the present invention has an inherent viscosity (ηln) of 0.1 to 2 dl / g, preferably 0.5 to 1.5 dl / g. When the logarithmic viscosity (ηln) is less than 0.1 dl / g,
When used as a liquid crystal alignment film-forming agent, the resulting liquid crystal alignment film is liable to be scraped off during rubbing treatment, causing film peeling.
On the other hand, when the logarithmic viscosity (ηln) exceeds 2 dl / g, the coating property as a liquid crystal alignment film forming agent is remarkably reduced.

<Method for Producing Polyimide Block Copolymer> Next, a method for producing the polyimide block copolymer of the present invention will be described. The polyimide-based block copolymer of the present invention is a “step A” for preparing a polyamic acid prepolymer (A) having an amino group at a molecular end, and a polyamic acid having a reactive group derived from a tetracarboxylic acid at a molecular end. It can be produced by performing "Step B" for preparing the acid prepolymer (B) and "Step C" of reacting the polyamic acid prepolymer (A) with the polyamic acid prepolymer (B). it can. In the manufacturing method described above, it goes without saying that either step A or step B may be performed first. Hereinafter, each step will be described.

Step A: In this Step A, a tetracarboxylic acid having an organic group R ^A is reacted with a diamine having an organic group Q ^A as shown in the following reaction formula 1 or reaction formula 2, With respect to the number of moles of the tetracarboxylic acids used, the diamine has a mole number of, for example, 1.0.
The polyamic acid prepolymer (A) having an amino group at the molecular end is prepared by using an excess amount exceeding the equimolar amount so as to be 01 to 2 times.

[0020]

Embedded image

Step B: In this Step B, a tetracarboxylic acid having an organic group R ^B is reacted with a diamine having an organic group Q ^B as shown in the following reaction formula 3 or reaction formula 4, The number of moles of tetracarboxylic acid is, for example, 1.0, relative to the number of moles of diamine used.
The polyamic acid prepolymer (B) having a reactive group derived from a tetracarboxylic acid at the molecular end is used by using an excess amount exceeding the equimolar amount so as to be 01 to 2 times.
Is prepared.

[0022]

[Chemical 6]

Step C: In this Step C, the terminal amino groups of the polyamic acid prepolymer (A) obtained in Step A and the terminal tetracarboxylic acids of the polyamic acid prepolymer (B) obtained in Step B By reacting with a reactive group derived from the same as in step A or step B, the divalent linking group (—CO—NH—) is added to the nuclear atomic group R ^A as shown in the following formula 5. Bonded organic groups Q ^A
A polyamic acid block (A) having a bond with a repeating unit as a repeating unit, and a polyamic acid block (B) having a bond with a similar nuclear atomic group R ^B and an organic group Q ^B as a repeating unit
A block copolymer-type polyamic acid in which and are bonded is produced.

[0024]

Embedded image

In the above, the polyamic acid prepolymer (A) and the polyamic acid prepolymer (B) have different structures from each other, and specifically, the molecular structures of the repeating units of each polyamic acid prepolymer are different. It is a thing. If this is expressed in Formula 5, the nuclear atomic groups R ^A and R ^B may be the same or different, and the organic groups Q ^A and Q ^B may be the same or different. , R ^A and R ^B and Q ^A and Q ^B are not the same at the same time, and at least one of them must be different from each other. Therefore, in practice, different compounds are used as tetracarboxylic acids in step A and step B, different compounds are used as diamine in step A and step B, or both are performed. When the tetracarboxylic acids and diamines used in Step A and Step B are the same compound, that is, in the formula 5, when R ^A = R ^B and Q ^A = Q ^B , the polyamic acid prepolymer (A) And the polyamic acid prepolymer (B) are the same, the resulting polymer does not become a block copolymer but a mere homopolymer.

In order to obtain the polyimide block copolymer of the present invention, step A for preparing the polyamic acid prepolymer (A) and step B for preparing the polyamic acid prepolymer (B). In at least one step, it is necessary to use alicyclic tetracarboxylic acids as tetracarboxylic acids and at least one alicyclic or aromatic diamine as diamine. That is, the polyamic acid block ((A) derived from the polyamic acid prepolymer (A) prepared by performing step A using an alicyclic tetracarboxylic acid and at least one of an alicyclic and aromatic diamine) A) corresponds to the second polyimide-based block ( ^RA = R ² , Q ^A = Q ² ) and uses alicyclic tetracarboxylic acids and at least one of alicyclic and aromatic diamines. By carrying out the step B with the polyamic acid prepolymer (B) thus prepared, the polyamic acid block (B) derived from the polyamic acid prepolymer (B) corresponds to the second polyimide-based block (R ^B = R ² , Q ^B). =
Q ² ). In addition, in both the process A and the process B,
When an alicyclic tetracarboxylic acid and at least one of an alicyclic and aromatic diamine are used, one of the polyamic acid block (A) and the polyamic acid block (B) is used as the second polyimide. It may correspond to a system block.

In step A and step B, one or the other of the tetracarboxylic acid and the diamine is used in an excess amount, but the ratio of the two in each step is determined in the finally obtained polyimide block copolymer. It can be selected according to the characteristics. This percentage is usually
On the other hand, the other is a range in which the number of moles is 1.001 to 2 times.

In the above formula 5, as r and s which represent the repeating unit of the polyamic acid block, the number of repeating units of the polyamic acid block corresponding to the first polyimide block is 3 to 2000, preferably 3 to 10
0, the number of repeating units of the polyamic acid block corresponding to the second polyimide block is 2 to 1000,
It is preferably 2 to 100. Moreover, the number z of the repeating unit of the conjugate having a unit of the polyamic acid block (A) and the polyamic acid block (B) as a unit is from 1 to 100.
Range. Here, when z is 2 or more, the number of r or s in each conjugate repeating unit may be the same or different. Then, it is preferable that the total number of moles of the tetracarboxylic acids and the total number of moles of the diamine used in both step A and step B are substantially equivalent and have an equivalent relationship.

Further, in step A or step B, it is possible to use a plurality of types of compounds as the tetracarboxylic acid and it is also possible to use a plurality of types of compound as the diamine. In addition, 1 of the polyamic acid prepolymer produced in the same manner as in step A or step B
It is also possible to produce a block copolymerization type polyamic acid containing three or more polyamic acid blocks by reacting one or more kinds in step C or by reacting in the same manner as in step C. . The above polyamic acid prepolymer and block copolymerization type polyamic acid may contain an imide bond formed by dehydration ring closure of a part of the amic acid site depending on the reaction conditions.

Examples of the alicyclic tetracarboxylic acid used in step A and / or step B include alicyclic tetracarboxylic dianhydride, alicyclic tetracarboxylic acid and alicyclic tetracarboxylic acid ester. it can.

Specific examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2-dimethyl-1,2,3,3.
4-cyclobutanetetracarboxylic dianhydride, 1,3-
Dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,
2,3,4-cyclobutanetetracarboxylic dianhydride,
1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 3,5,6-tricarboxynorbornane-
2-acetic acid dianhydride, 2,3,4,5-tetrahydrofuran tetracarboxylic acid dianhydride, 1,3,3a, 4,5
9b-Hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro- 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, 4,5,9
b-hexahydro-8-methyl-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, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, bicyclo [2.2. 2] -Oct-7-ene-2,3,5,6-
Examples thereof include tetracarboxylic dianhydride.

Specific examples of the alicyclic tetracarboxylic acid include 1,2,3,4-cyclobutane tetracarboxylic acid,
1,2,3,4-cyclopentanetetracarboxylic acid,
2,3,5-tricarboxycyclopentyl acetic acid, 3,
5,6-tricarboxynorbornane-2-acetic acid, 2,
3,4,5-tetrahydrofuran tetracarboxylic acid, 5
-(2,5-Dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, bicyclo [2.2.2] -oct-7-ene-2,3,5
6-tetracarboxylic acid and the like can be mentioned.

Specific examples of the alicyclic tetracarboxylic acid ester include methyl ester, ethyl ester, propyl ester, isopropyl ester and butyl ester of the above alicyclic tetracarboxylic acid.

As the tetracarboxylic acids other than the alicyclic tetracarboxylic acids which may be used in the steps A and B, aliphatic tetracarboxylic dianhydride, aliphatic tetracarboxylic acid, aliphatic tetracarboxylic acid ester, Examples thereof include aromatic tetracarboxylic dianhydride, aromatic tetracarboxylic acid, and aromatic tetracarboxylic acid ester.

Specific examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, and specific examples of the aliphatic tetracarboxylic acid include butanetetracarboxylic acid. Specific examples of the aliphatic tetracarboxylic acid ester include methyl ester, ethyl ester propyl ester and butyl ester of the above aliphatic tetracarboxylic acid.

Specific examples of the aromatic tetracarboxylic dianhydride include, for example, pyromellitic dianhydride, 3,3 ',
4,4′-benzophenonetetracarboxylic dianhydride,
3,3 ′, 4,4′-biphenylsulfone tetracarboxylic acid dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride , 3,3 ', 4,4'-biphenyl ether tetracarboxylic dianhydride, 3,3', 4,4 '
-Dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furan tetracarboxylic dianhydride, 4,4 '-Bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,
4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfone dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride,
3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride , P-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-
Examples thereof include bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylether dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride. .

Specific examples of the aromatic tetracarboxylic acid include pyromellitic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 3,3', 4,4'-biphenyl sulfone tetracarboxylic acid, 3, 3 ', 4,
4'-biphenyl ether tetracarboxylic acid, 3,
3 ', 4,4'-dimethyldiphenylsilanetetracarboxylic acid, 1,2,3,4-furantetracarboxylic acid,
4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfide, 4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfone, 3,3 ',
4,4'-perfluoroisopropylidene diphthalic acid,
3,3 ', 4,4'-biphenyltetracarboxylic acid, p
-Phenylene-bis (triphenylphthalic acid), m-phenylene-bis (triphenylphthalic acid), bis (triphenylphthalic acid) -4,4'-diphenylmethane and the like.

Specific examples of the aromatic tetracarboxylic acid ester include alicyclic or aromatic tetracarboxylic acid esters such as methyl ester, ethyl ester propyl ester and butyl ester of the above aromatic tetracarboxylic acid.

As the tetracarboxylic acid (alicyclic / aliphatic / aromatic), tetracarboxylic dianhydride is preferable because of its high reactivity. Moreover, these tetracarboxylic acids can be used individually or in combination of 2 or more types.

The alicyclic diamine used in step A and / or step B is 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-.
Methanoin danylene dimethylene diamine, tricyclo [6.2.1.0 ^2.7 ] -undecylenedimethyl diamine, 4,4'-methylene bis (cyclohexyl amine)
And the like.

The aromatic diamine used in step A and / or step B includes p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane,
4,4'-diaminodiphenyl sulfide, 4,4'-
Diaminodiphenyl sulfone, 3,5-diamino-3 '
-Trifluoromethylbenzanilide, 3,5-diamino-4'-trifluoromethylbenzanilide, 3,
3′-dimethyl-4,4′-diaminobiphenyl, 4,
4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 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-aminophenoxy) phenyl] propane,
2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 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 ′, 5,5′-tetrachloro-
4,4'-diaminobiphenyl, 2,2'-dichloro-
4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4 '-(p-phenyleneisopropylidene)
Bisaniline, 4,4 '-(m-phenyleneisopropylidene) bisaniline, 2,2-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4'-diamino-2 , 2 '
-Bis (trifluoromethyl) biphenyl, 4,4'-
Examples thereof include bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, bis (4-aminophenoxy) -2,2′-dimethylpropane and diaminotetraphenylthiophene.

As diamines other than alicyclic diamines and diamines other than aromatic compounds, 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine. , Octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, and the like.

Among these diamines, p-phenylenediamine, 4,4'-diaminodiphenylmethane,
1,5-diaminonaphthalene, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 4,
4 '-(p-phenylene isopropylidene) bisaniline, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2 -Bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 4,4'-bis [ (4-Amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl and 3,5-diamino-4′-trifluoromethylbenzanilide are preferred, especially p-phenylenediamine,
4,4'-diaminodiphenylmethane and 4,4'-
(P-Phenylene isopropylidene) bisaniline is particularly preferred. These diamines can be used alone or
More than one species can be used in combination.

The reaction in step A, step B and step C is carried out in an organic solvent under the temperature condition of usually 0 to 200 ° C, preferably 0 to 100 ° C. The organic solvent used in this reaction is not particularly limited as long as it can dissolve the generated polyamic acid, and examples thereof include N-methyl-2-pyrrolidone, N, N-dimethylacetamide,
Aprotic polar solvents such as N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide;
Phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol can be mentioned. The amount of the organic solvent used is such that the total amount of tetracarboxylic acids and diamine is 0.1 to 3 with respect to the total amount of the reaction solution.
The amount is preferably 0% by weight.
This organic solvent includes poor solvents such as alcohols, ketones, esters, ethers, halogenated hydrocarbons,
Hydrocarbons can be used together in such a proportion that the polyamic acid prepolymer to be produced does not precipitate. Examples of the poor solvent include ethyl alcohol, cyclohexanol, propylene glycol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, diethyl malonate, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene. Glycol-propyl ether, ethylene glycol ethyl ether acetate, tetrahydrofuran, dichloroethane,
Examples thereof include chlorobenzene, hexane, heptane, toluene and xylene.

The block copolymer type polyamic acid represented by the above formula 5 is obtained by subjecting it to imidization treatment.
A polyimide block (A) having a bond with an organic group Q ^A bonded to a nuclear atomic group R ^A via an imide bond as a repeating unit, as represented by the following formula 6 in which the amic acid site is dehydrated and cyclized: , A polyimide block copolymer in which a polyimide block (B) having a repeating unit of a bond of a similar nuclear atomic group R ^B and an organic group Q ^B is bonded. Note that also in Equation 6, R ^A and R ^B and Q ^A and Q
It is necessary that ^B are not the same at the same time but different from each other in at least one of them.

[0046]

Embedded image

Specifically, the imidization treatment is carried out by heating the block copolymer type polyamic acid obtained through the steps A, B and C, or by dissolving the polyamic acid copolymer in an organic solvent. Then, in the presence of a dehydrating agent and an imidization catalyst in this solution, heating is carried out as necessary to dehydrate and ring-close the amic acid site. The imidization treatment by heating is usually at a temperature of 60 to 250 ° C., preferably 100 to 2
Performed at 00 ° C. If the heating temperature is lower than 60 ° C, the dehydration ring-closing reaction does not proceed sufficiently, while if the heating temperature exceeds 200 ° C, the obtained polyimide block copolymer may have a small molecular weight. When the imidization treatment is carried out using a dehydrating agent and an imidization catalyst,
As a dehydrating agent, for example, acetic anhydride, propionic anhydride,
An acid anhydride such as trifluoroacetic anhydride can be used. The amount of the dehydrating agent used is preferably 1.6 to 20 mol per 1 mol of the repeating unit of the polyamic acid.

Examples of the imidization catalyst include 3 such as pyridine, collidine, lutidine and triethylamine.
Primary amines can be used, but are not limited to these. The amount of the imidization catalyst used is preferably 0.5 to 10 mol per 1 mol of the dehydrating agent used. As the organic solvent used for this imidization treatment,
The organic solvents exemplified as those used in Step A, Step B and Step C can be mentioned, and the reaction temperature for the dehydration ring closure in this imidization treatment is usually 0 to 200.
C., preferably 60 to 150.degree. By controlling the reaction conditions in the imidization treatment,
The imidization ratio of the block copolymer can be adjusted arbitrarily.

Since these polyimide-based block copolymers are a combination of two or more kinds of polyimide-based blocks having different structures from each other, basically a polyamic acid or a polyamic acid is used. In addition to having the intrinsic properties as a polyimide, the polyamic acid or the homopolymer of the polyimide relating to each block has a plurality of types of properties. That is, for example, the first polyimide component and the second polyimide component coexist in the molecule as blocks, respectively, so that the first characteristic of the homopolymer of the polyimide constituting the first block and the second characteristic At the same time, it has the second characteristic of the homopolymer of the polyimide forming the block. Alternatively, the property of the polyimide block copolymer is that the property of the homopolymer of the polyimide forming a certain block is in a state of being modified by the property of the homopolymer of the polyimide forming another block. You can Such characteristics are
Which cannot be obtained by a mere mixture of the polyimide and the second polyimide, and all the tetracarboxylic acids and diamines used for obtaining the first and second polyimides, for example, It is not possible to obtain it even when it is reacted. That is, it can be said that the polyimide-based block copolymer of the present invention is a copolymer having a plurality of good properties that are difficult to obtain simultaneously by ordinary means.

In the above description, R ¹ , R ² and R ² are contained in the same block in the formula representing the polyimide block copolymer.
^A tetravalent organic group (alicyclic group) represented by R ^A and R ^B ,
When there are a plurality of divalent organic groups (alicyclic group or aromatic group) represented by Q ¹ , Q ² , Q ^A and Q ^B , they have the same structure. Further, as described above, the characteristics of the polyimide block copolymer are determined by the structure of the repeating unit in each block constituting the polyimide block copolymer and the number of repeating units or the ratio thereof. Therefore, by controlling those factors, it is possible to control the properties of the finally obtained polyimide block copolymer. That is, tetracarboxylic acids used for the production of each block,
By selecting the type of diamine, and by adjusting the amount or ratio of its use, the number of blocks that should constitute the resulting polyimide block copolymer, if each type and their ratio is controlled, by this, It is possible to control the properties of the finally obtained polyimide block copolymer. As a result, for example, based on the properties of polyimide, which is an empirically known homopolymer, by performing molecular design according to the actual application, it is possible to produce a polyimide-based copolymer having desired properties. .

<Polyimide Block Copolymer Solution>
The polyimide-based block copolymer of the present invention is usually used as a solution (hereinafter referred to as "copolymer solution") by dissolving the polyimide-based block copolymer as a main component in an appropriate organic solvent. This copolymer solution is a thin film used for various purposes, for example, a thin film as an electrical insulating material, a thin film forming a heat resistant coating, a thin film as a surface protective coating, a thin film as a gas separation film, a thin film as a resist, It can be used for forming other thin films, and in particular, for example, TN type liquid crystal display device, S
It is useful as a liquid crystal alignment film forming agent for forming a liquid crystal alignment film forming a TN type liquid crystal display device and a ferroelectric liquid crystal display device. Alternatively, the thin film formed on the substrate can be peeled from the substrate and used as a film. The organic solvent used to prepare the copolymer solution is not particularly limited as long as it dissolves the polyimide block copolymer, various can be used, as a specific example. The organic solvents exemplified as those used in Step A, Step B and Step C can be mentioned.

Various additives can be added to the copolymer solution depending on its use. In particular, the copolymer solution used as the liquid crystal alignment film-forming agent may contain various additives in order to improve the properties of the copolymer solution itself and the properties of the liquid crystal alignment film formed therefrom. As such an additive, for example, a functional silane-containing compound can be contained for the purpose of improving the adhesiveness of the liquid crystal alignment film to the surface of the substrate constituting the liquid crystal display element. Examples of such a functional silane-containing compound include aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, and ureidopropyltrimethoxysilane.

In order to form a thin film using the copolymer solution containing the polyimide block copolymer of the present invention, usually, the copolymer solution is applied to the surface of an appropriate substrate and dried, When it has a polyamic acid block, it may be heated for further dehydration ring closure if necessary. When used as a liquid crystal alignment film forming agent,
For example, a liquid crystal alignment film is formed by the following method,
Further, a liquid crystal display element is manufactured.

(1) A liquid crystal alignment film forming agent is applied to one surface of a substrate for a liquid crystal display element provided with a transparent conductive film, and the applied surface is heated to form a thin film which is a material of the liquid crystal alignment film. To do. Here, as the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; or a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, or polycarbonate can be used. As a transparent conductive film provided on one surface of the substrate, a NESA film made of tin oxide (SnO ₂ ) (registered trademark of PPG Co., USA), an IT made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ).
An O film or the like can be used, and for patterning these transparent conductive films, a photoetching method or a method using a mask in advance is used. As a method of applying the thin film forming agent, a method such as a roll coater method, a spinner method, a curtain coating method, etc. can be used in addition to the printing method. When applying the thin film forming agent, in order to further improve the adhesiveness between the substrate surface and the transparent conductive film and the coating film, a functional silane-containing compound, a functional titanium compound, etc. are formed on one surface of the substrate and the transparent conductive film. Can also be applied in advance. The heating temperature for drying the coated surface or dehydration ring closure of the polyamic acid block is set to 80 to 200 ° C.,
The temperature is preferably 120 to 200 ° C. The dry film thickness of the formed coating film is usually 0.001 to 1 μm,
It is preferably 0.005 to 0.5 μm.

(2) The formed thin film is subjected to orientation treatment.
This orientation treatment is performed by, for example, a rubbing treatment method of rubbing a cloth made of nylon, rayon, cotton or the like in a certain direction with a roll wound around, a UV irradiation method of irradiating UV rays, or the like. By this alignment treatment, the thin film is provided with alignment ability for liquid crystal molecules to form a liquid crystal alignment film. In addition, a selected local region of the formed thin film may be exposed to radiation such as 1 to 3 before or after the alignment treatment.
10,000 mJ / cm ² , preferably 200 to 3000
By irradiating with ultraviolet rays of mJ / cm ² , it is also possible to carry out an alignment characteristic modification treatment.

(3) Two substrates having the liquid crystal alignment film formed as described above are prepared, and the two substrates are so arranged that the rubbing directions of the respective liquid crystal alignment films are orthogonal, parallel or antiparallel. , Facing each other with a gap (cell gap) in between, the peripheral portions of the two substrates are bonded together with a sealant, and liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealant. To form a liquid crystal cell. Then, a polarizing plate is provided on the outer surface of the liquid crystal cell, that is, on the other surface side of each of the substrates constituting the liquid crystal cell so that the polarization direction thereof is the same as or orthogonal to the rubbing direction of the liquid crystal alignment film formed on the one surface of the substrate. A liquid crystal display device can be obtained by bonding to. Here, as the sealing agent, for example, an epoxy resin containing an aluminum oxide sphere as a curing agent and a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, a nematic liquid crystal is preferable, for example, a Schiff base liquid crystal, an azoxy liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, and a terphenyl liquid crystal. A liquid crystal, a biphenylcyclohexane-based liquid crystal, a pyrimidine-based liquid crystal, a dioxane-based liquid crystal, a bicyclooctane-based liquid crystal, a cubane-based liquid crystal, or the like can be used. In addition, ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can be used. In addition to these liquid crystals, for example, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate, and cholesteryl carbonate, and the product name "C
-15 "and" CB-15 "(manufactured by Merck & Co., Inc.) can also be used by adding a chiral agent and the like. As a polarizing plate to be attached to the outer surface of a liquid crystal cell, a polarizing film in which a polarizing film called an H film absorbing iodine while sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films, or the H film itself And a polarizing plate made of

The liquid crystal alignment film formed as described above is basically made of a polyimide block copolymer having the structure represented by the above formula (6). And, as described above, it has a plurality of good characteristics that cannot be realized by the conventional polyimide and is difficult to obtain at the same time by the ordinary means. For example, some polyimides have good coatability, but the alignment characteristics of the liquid crystal alignment film are unstable depending on the number of rubbing treatments and the size of the film thickness. Polyimide has a low coating property, but as a liquid crystal alignment film, stable liquid crystal alignment characteristics independent of the number of rubbing treatments and the size of the film thickness are obtained, and a large pretilt angle is exhibited.

However, according to the liquid crystal alignment film forming agent made of a polyimide-based block copolymer containing both of these types of polyimides as blocks, good coatability can be obtained and the liquid crystal alignment film to be formed is In addition, stable liquid crystal alignment characteristics are obtained that do not depend on the number of rubbing treatments and the size of the film thickness, and a large pretilt angle is exhibited. Further, the characteristics of having a high sensitivity to radiation and the characteristics of being able to maintain high adhesiveness to a substrate are characteristics that cannot be obtained at the same time by ordinary means with a polyimide homopolymer, but with a polyimide block copolymer, For example, it is possible to obtain both such properties at the same time, and as a result, it becomes possible to perform the alignment property modification process with high efficiency in the liquid crystal alignment film. Specifically, highly efficient alignment property correction processing by irradiation of radiation such as ultraviolet rays to a selected local region, which is performed on a thin film that becomes a liquid crystal alignment film before or after alignment processing such as rubbing processing, is highly efficient. Therefore, it is possible to obtain the characteristic that high adhesion to the substrate of the liquid crystal alignment film is maintained, which is usually lost when such radiation is applied. When it is performed, the liquid crystal alignment film is not damaged. Therefore, according to such a liquid crystal alignment film, it is possible to easily achieve partial control of the pretilt angle, and it is possible to manufacture a liquid crystal display element with less viewing angle dependence of contrast with high efficiency. .

[0059]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. In addition, in the following synthetic examples and comparative synthetic examples, the value of the logarithmic viscosity (ηln) of the prepolymer, the polyamic acid and the polyimide copolymer is N-methyl-2.
Using pyrrolidone as the solvent and the polymer concentration being
The viscosity of a solution of 5 g / 100 ml was measured at 30 ° C., and the viscosity was determined by the following formula.

[0060]

[Equation 1]

In the following Examples and Comparative Examples, the "coating property of the liquid crystal alignment film forming agent" is the thickness of the thin film formed by the liquid crystal alignment film forming agent, and the stylus type film thickness meter "alpha step" (American TENCOR INST
It was evaluated by determining the average value of the thickness of the thin film and its standard deviation.
The "adhesiveness of the thin film to the substrate" was evaluated by the presence or absence of peeling when the thin film formed on the ITO film was rubbed. Also, "durability against orientation treatment" is IT
It was evaluated by observing the surface state (presence or absence of rubbing scratches) of the liquid crystal alignment film formed on the O film. The “orientation of the liquid crystal display element” was observed by a polarizing microscope for the presence or absence of an abnormal domain when the voltage was turned on / off (applied / released), and judged to be “good” when there was no abnormal domain. In addition, the "pretilt angle of the liquid crystal display element" is "TJ.Sc".
hffer, et al. , J. et al. Appl. Phys. ,
vol. 19, 2013 (1980) ", and measured by a crystal rotation method using a He-Ne laser beam. The “voltage holding ratio of the liquid crystal display element” is 8
After applying a voltage of 5 V for 6 × 10 ⁻⁵ seconds to the liquid crystal display device installed in a 0 ° C. constant temperature chamber, the voltage holding ratio after 16.7 × 10 ⁻³ seconds has passed since the voltage application was released "VH
R-1 "(manufactured by Toyo Corporation).

[Synthesis Example 1] Step A (synthesis of amino group-terminated prepolymer): 5.19 g (23.80 mmol) of pyromellitic dianhydride,
5.90 g (2,4'-diaminodiphenylmethane
(9.80 mmol) was dissolved in 99.81 g of N-methyl-2-pyrrolidone, and the mixture was reacted by stirring at room temperature for 2 hours to obtain a solution of an amino group-terminated prepolymer. The logarithmic viscosity of this amino group-terminated prepolymer is 0.1.
It was 0 dl / g. Step B (Synthesis of acid anhydride group-terminated prepolymer): 2,
8.05 g (35.70 mmol) of 3,5-tricarboxycyclopentylacetic acid dianhydride and 5.90 g (29.80 mmol) of 4,4'-diaminodiphenylmethane were added to 125.N-methyl-2-pyrrolidone. 19 g
Was dissolved in the solution and reacted at room temperature for 2 hours with stirring to obtain a solution of an acid anhydride group-terminated prepolymer. The logarithmic viscosity of this acid anhydride group-terminated prepolymer is 0.05 dl /
g. Step C (Synthesis of Block Copolymerization Type Polyamic Acid): Reaction is carried out by mixing the entire solution of the amino group-terminated prepolymer and the entire solution of the acid anhydride group-terminated prepolymer and stirring at 60 ° C. for 6 hours. Let The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A block copolymer type polyamic acid of 10 dl / g was obtained. This is designated as "specific polymer (Ia)".

(Imidization Treatment) 25.00 g of the specific polymer (Ia) obtained in the above step was dissolved in 475 g of N-methyl-2-pyrrolidone, and 9.42 g of pyridine and 12.15 g of acetic anhydride were added. And imidized at 110 ° C. for 5 hours. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A polyimide block copolymer of 10 dl / g was obtained. This is referred to as "specific polymer (II
a) ”.

[Synthesis Example 2] Step A (synthesis of amino group-terminated prepolymer): 2, 3,
5-Tricarboxycyclopentyl acetic acid dianhydride 5.3
5 g (23.90 mmol) and 4,4′-diaminodiphenylmethane (5.92 g, 29.99 mmol) were dissolved in N-methyl-2-pyrrolidone (101.43 g) and stirred at room temperature for 2 hours to react. By doing so, a solution of the amino group-terminated prepolymer was obtained. The logarithmic viscosity of this amino group-terminated prepolymer was 0.05 dl / g. Step B (synthesis of acid anhydride group-terminated prepolymer): 7.81 g (35.80 mmol) of pyromellitic dianhydride,
5,4 g of 4,4'-diaminodiphenylmethane (2
9.90 mmol) was dissolved in 123.57 g of N-methyl-2-pyrrolidone, and the reaction was carried out by stirring at room temperature for 2 hours to obtain a solution of an acid anhydride group-terminated prepolymer. The logarithmic viscosity of this acid anhydride group-terminated prepolymer was 0.10 dl / g. Step C (Synthesis of Block Copolymerization Type Polyamic Acid): Reaction is carried out by mixing the entire solution of the amino group-terminated prepolymer and the entire solution of the acid anhydride group-terminated prepolymer and stirring at 60 ° C. for 6 hours. Let The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A block copolymer type polyamic acid of 10 dl / g was obtained. This is designated as "specific polymer (Ib)".

[Synthesis Example 3] Step A (synthesis of amino group-terminated prepolymer): 2, 3,
5-tricarboxycyclopentyl acetic acid dianhydride 6.7
0 g (29.90 mmol) and 1,4-diaminocyclohexane 4.27 g (37.50 mmol) were added to N
-Methyl-2-pyrrolidone was dissolved in 98.73 g, and the mixture was stirred at room temperature for 2 hours for reaction to obtain an amino group-terminated prepolymer solution. The logarithmic viscosity of this amino group-terminated prepolymer was 0.06 dl / g. Step B (synthesis of acid anhydride group-terminated prepolymer): 9.77 g (44.80 mmol) of pyromellitic dianhydride,
1,4-diaminocyclohexane 4.27 g (37.5
0 mmol) and N-methyl-2-pyrrolidone 12
A solution of an acid anhydride group-terminated prepolymer was obtained by dissolving in 6.36 g and reacting with stirring for 2 hours at room temperature. The logarithmic viscosity of the acid anhydride group-terminated prepolymer is 0.
It was 12 dl / g. Step C (Synthesis of Block Copolymerization Type Polyamic Acid): Reaction is carried out by mixing the entire solution of the amino group-terminated prepolymer and the entire solution of the acid anhydride group-terminated prepolymer and stirring at 60 ° C. for 6 hours. Let The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A block copolymer type polyamic acid of 14 dl / g was obtained. This is designated as "specific polymer (Ic)".

(Imidization treatment) 25.00 g of the specific polymer (Ic) obtained in the above step was dissolved in 475 g of N-methyl-2-pyrrolidone, and 11.82 g of pyridine and 15.25 g of acetic anhydride were added. And imidized at 110 ° C. for 5 hours. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A polyimide block copolymer of 10 dl / g was obtained. This is referred to as "specific polymer (II
c) ”.

[Synthesis Example 4] Step A (synthesis of amino group-terminated prepolymer): 2, 3,
5-Tricarboxycyclopentyl acetic acid dianhydride 7.2
1 g (32.20 mmol) and 4,4′-diaminodiphenylmethane 7.65 g (38.60 mmol) were dissolved in N-methyl-2-pyrrolidone 133.74 g and reacted by stirring at room temperature for 2 hours. By doing so, a solution of the amino group-terminated prepolymer was obtained. The logarithmic viscosity of this amino group-terminated prepolymer was 0.16 dl / g. Step B (Synthesis of acid anhydride group-terminated prepolymer): 2,
7.21 g (32.20 mmol) of 3,5-tricarboxycyclopentyl acetic acid dianhydride and 2.94 g (25.70 mmol) of 1,4-diaminocyclohexane were added to 98.73 g of N-methyl-2-pyrrolidone. Was dissolved in the solution and reacted at room temperature for 2 hours with stirring to obtain a solution of an acid anhydride group-terminated prepolymer. The logarithmic viscosity of the acid anhydride group-terminated prepolymer was 0.06 dl / g. Step C (Synthesis of Block Copolymerization Type Polyamic Acid): Reaction is carried out by mixing the entire solution of the acid anhydride group-terminated prepolymer and the entire solution of the amino group-terminated prepolymer and stirring at 60 ° C. for 6 hours. Let The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A block copolymer type polyamic acid of 19 dl / g was obtained. This is designated as "specific polymer (Id)".

(Imidization Treatment) 25.00 g of the specific polymer (Id) obtained in the above step was dissolved in 475 g of N-methyl-2-pyrrolidone, and 10.17 g of pyridine and 13.13 g of acetic anhydride were added. And imidized at 110 ° C. for 5 hours. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A 19 dl / g polyimide block copolymer was obtained. This is referred to as "specific polymer (II
d) ”.

[Comparative Synthesis Example 1] 13.3 g of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride (59.
20 mmol) and 11,4 g of 4,4'-diaminodiphenylmethane (59.20 mmol) were dissolved in 225.00 g of N-methyl-2-pyrrolidone, and the mixture was heated at 60 ° C.
The mixture was stirred for 6 hours to react. The reaction product obtained was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated and washed with methyl alcohol.
By drying for 15 hours at ℃, logarithmic viscosity of 1.2
3 dl / g of polyamic acid was obtained. This is referred to as "polymer (Ix)".

[Comparative Synthesis Example 2] Pyromellitic dianhydride 1
3.10 g (60.10 mmol) and 4,4′-diaminodiphenylmethane 11.90 g (60.10 mmol) were added to N-methyl-2-pyrrolidone 225.00 g.
And was stirred at 60 ° C. for 6 hours for reaction. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. 42 dl / g of polyamic acid was obtained. This is referred to as "polymer (Iy)".

[Comparative Synthesis Example 3] 8.03 g (35.7) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride
0 mmol) and 5.19 g of pyromellitic dianhydride (2
3.80 mmol) and 11,4 g of 4,4'-diaminodiphenylmethane (59.50 mmol) in N-.
Dissolve in 225.00 g of methyl-2-pyrrolidone,
The mixture was reacted by stirring at 0 ° C for 6 hours. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. 00 dl / g of polyamic acid was obtained. This is referred to as "polymer (Iz)". (Imidization treatment) Polymer (Iz) obtained in the above process
25.00 g was dissolved in 475 g of N-methyl-2-pyrrolidone, and 9.42 g of pyridine and 12.15 g of acetic anhydride.
Was added for imidization at 110 ° C. for 5 hours. The obtained reaction product was poured into a large excess of methyl alcohol to precipitate the polymer, and the solid substance was separated, washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to give a logarithmic viscosity of 1. A polyimide block copolymer of 00 dl / g was obtained. This is referred to as "polymer (IIz)".

Example 1 (1) Preparation of Liquid Crystal Alignment Film Forming Agent: The specific polymer (Ia) obtained in Synthesis Example 1 was dissolved in γ-butyrolactone to obtain a solution having a solid content concentration of 5% by weight, This solution was filtered with a filter having a pore size of 1 μm to prepare a liquid crystal alignment film forming agent.

(2) Fabrication of liquid crystal display device: The liquid crystal alignment film forming agent prepared in the above (1) was applied to the transparent conductive film made of the ITO film provided on one surface of the glass substrate. A thin film was formed by coating using a coating machine and drying at 250 ° C. for 1 hour. When the thickness of this thin film was measured, the average value was 600Å and the standard deviation was ± 20Å, and the film thickness was highly uniform, and the liquid crystal alignment film forming agent had good coatability. Was recognized. A liquid crystal alignment film was formed by rubbing the surface of the formed thin film with a rubbing machine having a roll around which a cloth made of nylon was wound. Here, the rubbing treatment condition is a roll bristle pushing length of 0.6.
mm, the rotation speed of the roll was 500 rpm, and the moving speed of the stage was 1 cm / sec. At the time of this rubbing treatment, the adhesion of the thin film to the glass substrate was good, and peeling of the thin film due to the rubbing treatment did not occur. No rubbing scratch was observed on the surface of the formed liquid crystal alignment film.

As described above, two substrates each having a liquid crystal alignment film formed thereon were prepared, and the outer edge of each substrate had a diameter of 17 μm.
After applying an epoxy resin adhesive containing m aluminum oxide spheres by a screen printing method, the two liquid crystal alignment films are opposed to each other and the rubbing directions are antiparallel to each other. They were arranged facing each other, and the outer edge portions were brought into contact with each other and pressure-bonded to cure the adhesive. Nematic liquid crystal "MLC-2001" (manufactured by Merck & Co., Inc.) was injected and filled into the cell gap defined by the adhesive on the surface and the outer edge of the substrate, and then the injection hole was sealed with an epoxy adhesive. A liquid crystal cell was constructed. Thereafter, a polarizing plate was attached to the outer surface of the liquid crystal cell such that the polarization direction coincided with the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate, thereby producing a liquid crystal display element. The liquid crystal display device manufactured as described above had good orientation and a pretilt angle of 4.0 °. The voltage holding ratio of the liquid crystal display element was 99% or more, which was extremely high.

[Examples 2 to 7] Liquid crystal alignment film forming agents were prepared in the same manner as in Example 1 except that the specific polymers shown in Table 1 were used instead of the specific polymer (Ia).
A liquid crystal display device having a liquid crystal alignment film was produced in the same manner as in Example 1 except that the liquid crystal alignment film forming agent was used. Liquid crystal alignment film forming agent coating properties (thin film thickness average and standard deviation), thin film substrate adhesion (thin film peeling), alignment treatment durability (rubbing scratches), liquid crystal Table 1 shows the evaluation results and the measurement results for each of the orientation of the display element, the pretilt angle of the liquid crystal display element, and the voltage holding ratio of the liquid crystal display element.

Comparative Example 1 In the same manner as in Example 1 except that the polymer (IIz) having the same monomer composition as that of the specific polymer (Ia) was used in place of the specific polymer (Ia). A liquid crystal display device having a liquid crystal alignment film was prepared in the same manner as in Example 1 except that a liquid crystal alignment film forming agent was prepared and the liquid crystal alignment film forming agent was used. It was Table 1 shows the evaluation results and measurement results together.
Shown in From the results shown in Table 1, it is understood that the liquid crystal alignment film forming agent containing the polymer (IIz) is inferior in coating property (uniformity of film thickness). Further, the manufactured liquid crystal display element had a low voltage holding ratio of 95.2%.

Comparative Example 2 By blending 60.4 parts by weight of the polymer (Ix) and 39.6 parts by weight of the polymer (Iy), the monomer composition ratio was the same as that of the specific polymer (Ia). A certain polymer mixture was prepared and the specific polymer (Ia)
A liquid crystal alignment film forming agent was prepared in the same manner as in Example 1 except that this polymer mixture was used instead of. Next, a liquid crystal display element having a liquid crystal alignment film was prepared in the same manner as in Example 1 except that the liquid crystal alignment film forming agent was used, and the same characteristic evaluation as in each example was performed. The evaluation results and the measurement results are shown together in Table 1. From the results shown in Table 1,
It is understood that the liquid crystal alignment film forming agent containing the polymer mixture has poor coatability (uniformity of film thickness), and the formed thin film has poor durability to alignment treatment. Further, the manufactured liquid crystal display element had a low voltage holding ratio of 80.2%.

[0078]

[Table 1]

[0079]

The polyimide block copolymer of the present invention has a plurality of good properties which are difficult to obtain at the same time by ordinary means. The polyimide block copolymer of the present invention is particularly useful as a constituent component of a liquid crystal alignment film forming agent, and a liquid crystal alignment film forming agent prepared using the copolymer has good coating properties (film thickness Uniformity) and storage stability, the liquid crystal alignment film formed by the liquid crystal alignment film forming agent has a good alignment regulating force, a required pretilt angle, a rubbing scratch resistance, a high voltage holding ratio, It is possible to exhibit excellent characteristics such as low afterimage resistance, seizure resistance, and flicker resistance (flickering resistance) simultaneously and in a well-balanced manner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Matsuki 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A molecule containing a first polyimide-based block and a second polyimide-based block which is bonded to the first polyimide-based block and has a structure different from that of the first polyimide-based block. Wherein the first polyimide block has a repeating unit represented by the following formula 1 or formula 2, and the second polyimide block has the following formula 3 or formula 4 And a logarithmic viscosity (ηln) of 0.1 to 2 dl / g. Embedded image (In Formula 1 and Formula 2, R ¹ represents a tetravalent organic group, Q ¹ represents a divalent organic group, X represents a hydrogen atom or 1
It shows a valent organic group. m and n represent the number of repeating units. ) (In Formula 3 and Formula 4, R ² represents a tetravalent alicyclic group, Q ² represents a divalent alicyclic group or a divalent aromatic group, and X represents a hydrogen atom or a monovalent organic group. Represents a group, and p and q represent the number of repeating units.)