JP5751403B2 - Liquid crystal alignment agent - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent. More specifically, deterioration of display quality such as deterioration of electrical characteristics and liquid crystal alignment defects can be suppressed even when continuously driven for a long time, and good printability can be provided in a liquid-saving coating process in the liquid crystal display element manufacturing process. The present invention relates to a possible liquid crystal aligning agent.

As the liquid crystal display element, a liquid crystal display element of a horizontal alignment mode using a nematic liquid crystal having a positive dielectric anisotropy represented by a TN (Twisted Nematic) type, a STN (Super Twisted Nematic) type, etc. There is known a vertical alignment mode VA (Vertical Alignment) type liquid crystal display element using a nematic type liquid crystal having a dielectric anisotropy of 5%.
Such a liquid crystal display element includes a liquid crystal alignment film having a function of aligning liquid crystal molecules in a certain direction. As the material constituting the liquid crystal alignment film, polyamic acid, polyimide, polyamide, polyester, polyorganosiloxane, and the like are known. In particular, the liquid crystal alignment film made of polyamic acid or polyimide has heat resistance, mechanical strength, liquid crystal It has been used preferably for a long time because of its excellent affinity with molecules (Patent Documents 1 to 3).
In recent years, studies on improvement of display quality such as high definition of liquid crystal display elements and reduction of power consumption have progressed, and the range of use of liquid crystal display elements has been expanded. In particular, with the start of digital television broadcasting in which precise image information is transmitted, the use for liquid crystal televisions replacing CRT televisions is rapidly expanding. Therefore, there is a demand for a liquid crystal display element that is superior in electrical characteristics, has higher display quality, and can be continuously driven for a longer time.
However, a liquid crystal display device having a conventionally known liquid crystal alignment film has a display quality such as deterioration of electrical characteristics and poor alignment of liquid crystal molecules due to deterioration of the liquid crystal alignment film due to heat or light during long-time continuous lighting. It has been pointed out that problems that significantly decrease are likely to occur.

Therefore, there is a demand for the development of a liquid crystal alignment film that does not deteriorate the display quality such as deterioration of electrical characteristics and alignment failure of liquid crystal molecules even when the light is continuously lit for a long time.
In addition, in recent years, in order to effectively use the liquid crystal aligning agent, an attempt has been made to reduce the amount of the liquid crystal aligning agent used in the application process (printing process) of the liquid crystal aligning agent. However, with conventional alignment agents, when printing with a small amount of liquid, abnormalities such as printing defects and precipitation of resin components in the coating film, which may be caused by evaporation of the solvent in the liquid crystal alignment agent during printing, occur. There is a problem. Therefore, in order to maintain the quality of the film quality while achieving liquid-saving of the liquid crystal aligning agent, a liquid crystal aligning agent that exhibits excellent printability even with a small amount of liquid is awaited.
Recently, a compound having a bis (3-amino-4-hydroxyphenyl) adamantane structure has been proposed as a novel diamine, and is described as being applicable to liquid crystal alignment film applications (Patent Document 4). However, according to the study by the present inventors, a liquid crystal alignment film made of a polymer synthesized using a diamine having such a structure has a very low voltage holding ratio and is not suitable for practical use. Is clear.

JP-A-4-153622 JP 56-91277 A Japanese Patent Laid-Open No. 11-258605 JP 2004-262889 A JP 2010-97188 A JP-A-6-222366 JP-A-6-281937 JP-A-5-107544

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal that does not deteriorate display quality such as deterioration of electrical characteristics and alignment failure of liquid crystal molecules even when the lamp is lit continuously for a long time. An object of the present invention is to provide a liquid crystal aligning agent that can form an alignment film and has excellent printability even when printing is performed with a smaller amount of liquid.
Still other objects and advantages of the present invention will become apparent from the following description.

The above objects and advantages of the present invention are as follows:
A liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the following formula (A ″) and a polyimide having a structure represented by the following formula (A ″) Achieved by:

(Wherein (A "), ^{X 1} and ^{X 3} are each independently, et ether bond or an ester bond,
X ² and X ⁴ are each independently an ether bond or an ester bond,
Each R is independently a methylene group or an alkylene group having 2 to 6 carbon atoms;
a1, a2, a3 and a4 are each independently 0 or 1,
R ¹ is a hydroxyl group, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, or a carboxyalkyl group having 2 to 5 carbon atoms,
a5 is an integer of 0 to 14,
“*” Indicates a bond. )

The liquid crystal aligning agent of the present invention exhibits excellent printability even when printing is performed with a small amount of liquid, and can form a liquid crystal aligning film having excellent film quality and uniformity. In addition, the liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention has suppressed deterioration that causes display quality such as deterioration of electrical characteristics and alignment failure of liquid crystal molecules even when continuously driven for a long time. is there.
Therefore, the liquid crystal display element including the liquid crystal alignment film formed from the liquid crystal display element of the present invention can be effectively applied to various devices, such as a watch, a portable game, a word processor, a notebook computer, a car, and the like. It can be suitably used for display devices such as navigation systems, camcorders, personal digital assistants, digital cameras, mobile phones, various monitors, and liquid crystal televisions.
Furthermore, the film formed from the liquid crystal aligning agent of this invention can be applied suitably also as an insulating film in various electronic materials.

Hereinafter, the present invention will be described in detail.
The liquid crystal aligning agent of the present invention comprises at least one heavy selected from the group consisting of a polyamic acid having a structure represented by the above formula (A ″) and a polyimide having a structure represented by the above formula (A ″). Contains coalescence. Hereinafter, such a polymer is referred to as a “specific polymer” in the present specification. In the specific polymer, the structure represented by the formula (A ″) may be present in the main chain of the polymer, may be present in the side chain of the polymer, or the polymer It may be present in both the main chain and the side chain.
Examples of the alkyl group having 1 to 4 carbon atoms of R ¹ in the above formula (A ″) include a methyl group, an ethyl group, an isopropyl group, and an isobutyl group;
Examples of the alkoxyl group having 1 to 4 carbon atoms include a methoxyl group, an ethoxyl group, an isopropoxyl group, and an isobutoxyl group;
Examples of the carboxyalkyl group having 2 to 5 carbon atoms include a carboxymethyl group, a 2-carboxyethyl group, a 3-carboxy-n-propyl group, a 3-carboxy-2-methyl-propyl group, and a 4-carboxy-n-butyl group. Each group can be mentioned.
In the above formula (A ″), a5 is preferably 0 or 1, and more preferably 0.
When any one of X ¹ , X ² , X ³ and X ^{4 in} the above formula (A ″) is an ester bond, the ester bond may be oriented in either direction.
If a1 and a2 are both 0, it is preferred that X ¹ is an ether bond or an ester bond;
If a3 and a4 are both 0, it is preferred that X ³ is an ether bond or an ester bond.
Examples of the structure represented by the above formula (A ″) include the following formula (A ′):

(In the formula (A ′), X ¹ , X ³ , X ² , X ⁴ , R, a 1, a 2, a 3, a 4, R ¹ and a 5 and “*” are the same as those in the above formula (A ″). Is synonymous with.))
The structure represented by these is preferable, As a specific example, for example, following formula (A'-1)-(A'-12)

(In the above formula, “*” represents a bond.)
The structure represented by each of these can be mentioned.
The specific polymer in the present invention preferably has a structure represented by the above formula (A ″) as 2.5 × 10 ⁻⁵ mol / g or more, and 2.5 × 10 ^{−5 to} 2.25. It is more preferable to have × 10 ⁻³ mol / g, and it is more preferable to have 1.25 × 10 ^{−4 to} 1.75 × 10 ⁻³ g / mol.
The polyamic acid having a structure represented by the above formula (A ″) is, for example, a tetracarboxylic dianhydride containing a compound represented by the above formula (A ″) and a compound having two carboxylic anhydride groups, It can be obtained by reacting a diamine, or by reacting a tetracarboxylic dianhydride with a diamine containing a compound represented by the above formula (A ″) and a compound having two amino groups. ,
The polyimide having the structure represented by the above formula (A ″) can be obtained, for example, by dehydrating and ring-closing the polyamic acid obtained as described above.
As a specific polymer contained in the liquid crystal aligning agent of the present invention, a tetracarboxylic dianhydride and a diamine containing a compound having a structure represented by the above formula (A ″) and two amino groups are reacted. It is preferable that the polymer is at least one polymer selected from the group consisting of a polyamic acid obtained by the above-described process and a polyimide obtained by dehydrating and ring-closing the polyamic acid.
Hereinafter, the polyamic acid and polyimide, which are preferred specific polymers in the present invention, will be described in order.

<Polyamic acid>
As described above, a preferred polyamic acid in the present invention is obtained by reacting a tetracarboxylic dianhydride with a diamine containing a compound represented by the above formula (A ″) and a compound having two amino groups. Can be obtained.
[Tetracarboxylic dianhydride]
Examples of the tetracarboxylic dianhydride used for synthesizing the polyamic acid in the present invention include an aliphatic tetracarboxylic dianhydride, an alicyclic tetracarboxylic dianhydride, an aromatic tetracarboxylic dianhydride, and the like. Can be mentioned. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as butane tetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4, 5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b- Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane -2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene- No 1,2-dicarboxylic acid 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2 : 4,6: 8-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone and the like;
As aromatic tetracarboxylic dianhydride, for example, pyromellitic dianhydride can be mentioned, respectively,
The tetracarboxylic dianhydride described in Patent Document 5 (Japanese Patent Laid-Open No. 2010-97188) can be used.

The tetracarboxylic dianhydride used to synthesize the polyamic acid may be at least one selected from the group consisting of alicyclic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Preferably, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8 -Tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2, 5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and pyromellitic acid More preferably, it is at least one selected from the group consisting of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,3 , 3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione Particularly preferred is at least one selected.
Examples of the tetracarboxylic dianhydride used for synthesizing the polyamic acid include 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1 , 3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione It is preferable that at least one selected from the group contains 10 mol% or more, more preferably 20 mol% or more, more preferably 40 mol% or more, based on the total tetracarboxylic dianhydride. preferable.

[Diamine]
The diamine used for synthesizing a preferred polyamic acid in the liquid crystal aligning agent of the present invention is a compound having a structure represented by the above formula (A ″) and two amino groups (hereinafter referred to as “diamine (A)”). ).
The diamine (A) is preferably an aromatic diamine having a structure represented by the above formula (A ″) and two amino groups, for example, the following formula (A0):

(In the formula (A0), X ¹ , X ³ , X ² , X ⁴ , R, R ¹ , a 1, a 2, a 3, a 4 and a 5 are respectively synonymous with those in the above formula (A ″),
Each R ² is independently a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a carboxyalkyl group having 2 to 5 carbon atoms;
a6 is an integer of 0-4 each independently. )
The compound represented by these can be illustrated.
The alkyl group having 1 to 4 carbon atoms, the alkoxyl group having 1 to 4 carbon atoms, and the carboxyalkyl group having 2 to 5 carbon atoms in R ² in the above formula (A0) are respectively represented by R ¹ in the above formula (A ″). It can be the same as illustrated.
A6 in the above formula (A0) is preferably 0.
The position of the amino group in the two (substituted) aminophenyl groups present on the left and right of the formula (A0) is preferably the 3-position or the 4-position with respect to X ¹ or X ³ .
The diamine (A) is more preferably an aromatic diamine having a structure represented by the above formula (A ′) and two amino groups, for example, the following formula (A):

(In the formula (A), X ¹ , X ³ , X ² , X ⁴ , R, R ¹ , a 1, a 2, a 3, a 4 and a 5 are respectively synonymous with those in the above formula (A ″),
R ² and a6 are respectively synonymous with those in the above formula (A0). )
The compound represented by these can be mentioned as a more preferable example.
The position of the amino group in the two (substituted) aminophenyl groups present on the left and right of the formula (A) is preferably the 3-position or the 4-position with respect to X ¹ or X ³ .
As particularly preferred specific examples of the diamine (A) used in the present invention, for example, the following formulas (A-1) to (A-14):

The compound represented by each of these can be mentioned.
Such a diamine (A) can be synthesized by appropriately combining organic chemistry methods. For example, the compound represented by the above formula (A-1) is reacted with 1,3-adamantanediol and 2 equivalents of 4-fluoronitrobenzene to give 1,3-bis (4-nitrophenoxy) adamantane, and then suitable. It can be synthesized by amination of the nitro group using a simple reduction system. Here, by using 1,3-bis (hydroxymethyl) adamantane instead of 1,3-adamantanediol, a compound represented by the above formula (A-6) can be obtained;
By using 1,3-bis (hydroxymethyl) adamantane instead of 1,3-adamantanediol and further using 3-fluoronitrobenzene instead of 4-fluoronitrobenzene, the above formula (A-14) is used. A compound can be obtained.
The compound represented by the above formula (A-2) is a salt of 1,3-bis (2-carboxypropanoyloxy) adamantane obtained by reacting 1,3-adamantanediol with 2 equivalents of succinic anhydride. It can be obtained by further reacting with thionyl to obtain an acid chloride, and then aminating the nitro group of the compound obtained by reacting 2 equivalents of 4-nitrophenol.
The compound represented by the formula (A-4) is reacted with 1,3-adamantanediol and 2 equivalents of 4-nitrobenzoyl chloride to give 1,3-bis (4-nitrobenzoyloxy) adamantane, It can be synthesized by amination of the nitro group using an appropriate reduction system. Here, by using 1,3-bis (hydroxymethyl) adamantane instead of 1,3-adamantanediol, a compound represented by the above formula (A-9) can be obtained;
By using 3-fluoronitrobenzene instead of 4-fluoronitrobenzene, the compound represented by the above formula (A-13) can be obtained.

The compound represented by the above formula (A-5) is obtained by reacting 2 equivalents of a compound obtained by the reaction of 4-nitrophenol with 1,2-dibromoethane with 1,3-adamantanediol to give a dinitro compound. It can be obtained by amination of the nitro group of the dinitro compound. Here, by using 1,3-bis (hydroxymethyl) adamantane instead of 1,3-adamantanediol, a compound represented by the above formula (A-10) can be obtained.
In the synthesis of the compound represented by the above formula (A-2), the compound represented by the above formula (A-7) is substituted with 1,3-bis (hydroxymethyl) adamantane instead of 1,3-adamantanediol. Depending on the method used or by reacting 2 equivalents of the compound obtained by the reaction of 4-nitrophenol with succinic anhydride with 1,3-bis (hydroxymethyl) adamantane, a dinitro compound is obtained. It can be obtained by a method of aminating the nitro group possessed.
The compound represented by the above formula (A-11) is obtained by reacting 1,3-adamantane dicarboxylic acid with 2 equivalents of 4-fluoronitrobenzene to obtain a di (4-nitrophenyl) ester of 1,3-adamantane dicarboxylic acid. Then, it can be obtained by amination of the nitro group of the diester compound.
The compound represented by the above formula (A-12) is obtained by reacting 2 equivalents of a compound obtained by reacting 4-nitrophenol and 2-bromoethanol with 1,3-adamantane dicarboxylic acid to produce 1,3- It can be obtained by converting to a di (2- (4-nitrophenoxy) ethyl) ester of adamantanedicarboxylic acid and then aminating the nitro group of the diester compound.

  As the diamine (A) used in the present invention, from the viewpoint of ease of synthesis of the compound, the above formulas (A-2), (A-4) to (A-7) and (A-9) To (A-12) are preferred, and the compounds represented by formulas (A-6), (A-7) and (A-9) to (A-12) are more preferred. preferable. From the viewpoint of the heat resistance of the liquid crystal alignment film to be formed, it is represented by each of the above formulas (A-1), (A-4), (A-6), (A-9) and (A-11). It is preferable to use one or more selected from the group consisting of the following compounds. On the other hand, from the viewpoint of the printability of the obtained liquid crystal aligning agent, each of the above formulas (A-1), (A-4), (A-6), (A-9) and (A-11) is used. It is preferable to use one or more selected from the group consisting of the compounds represented by the formulas (A-1), (A-4), (A-6) and (A-11). It is more preferable to use one or more selected from the group consisting of:

As a diamine used for synthesizing a preferred polyamic acid in the present invention, only the diamine (A) may be used alone, or a diamine (A) and another diamine may be used in combination.
Examples of other diamines that can be used here include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes. Specific examples thereof include aliphatic diamines such as 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;
Examples of alicyclic diamines include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane and the like;

As aromatic diamines, for example, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2'- Dimethyl-4,4′-diaminobiphenyl, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2- Bis (4-aminophenyl) hexafluoropropane, 4,4 ′-(p-phenylenediisopropyl Ridene) bisaniline, 4,4 ′-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,6- Diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6- Diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N, N′-bis (4-aminophenyl) -benzidine, N, N′-bis (4-aminophenyl) -N, N′-dimethylbenzidine, Dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy- , 4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, dodecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene Cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, 3,5-diamino Cholestanyl benzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,5-diaminobenzoic acid, 1,4-bis- (4-aminophenyl) -piperazine, 1- (2, 4-Diaminophenyl) piperazine-4-cal Boronic acid, 4- (morpholin-4-yl) benzene-1,3-diamine, 1,3-bis (N- (4-aminophenyl) piperidinyl) propane, N, N-diallyl-diaminoaniline, α-amino -Ω-aminophenylalkylene, the following formula (D-1)

(In the formula (D-1), X ^I and X ^II are each a single bond, ^* —O—, ^* —COO— or ^* —OCO— (where the bond marked with “*” represents the formula (D facing leftward -I).) a and, R ^I is a methylene group or an alkylene group having a carbon number of 2 or 3, a is 0 or 1, b is an integer of 0 to 2, provided that a And b are not 0 at the same time, and c is an integer of 1 to 20.)
A compound represented by:
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, and at least one diamine selected from these (hereinafter referred to as “other specific”). Diamine ")),
The diamine described in Patent Document 5 (Japanese Patent Laid-Open No. 2010-97188) can be given along with or instead of these.
The formula ^{(D-1) X I -R} I -X II in - a divalent methylene group as a group, an alkylene group having 2 or 3 carbon atoms ^represented, * ^-O-, * -COO- or ^* It is preferably —O—CH ₂ CH ₂ —O— (wherein a bond marked with “*” is bonded to a diaminophenyl group). Specific examples of the group C _c H _{2c + 1} — include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n -Nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n -An eicosyl group etc. can be mentioned. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to the other groups.
Specific examples of the compound represented by the formula (D-1) include, for example, the following formulas (D-1-1) to (D-1-3).

And the like, and the like.
As other diamines used in the present invention, other specific diamines are preferably used, and in particular, p-phenylenediamine, 3,5-diaminobenzoic acid, 1- (2,4-diaminophenyl) piperazine-4- At least one selected from the group consisting of carboxylic acid, 4- (morpholin-4-yl) benzene-1,3-diamine, cholestanyloxy-2,4-diaminobenzene and cholestanyl 3,5-diaminobenzoate It is preferable to use it.
The diamine used for synthesizing the polyamic acid preferably contained in the liquid crystal aligning agent of the present invention preferably contains diamine (A) in an amount of 1 mol% or more based on the total diamine, and is 1 to 90 mol%. More preferably, it is more preferably 5 to 70 mol%, and particularly preferably 10 to 50 mol%. Moreover, it is preferable that the diamine used in order to synthesize | combine a preferable polyamic acid contains the other specific diamine as mentioned above other than diamine (A). In this case, the ratio of the other specific diamine to be used is preferably 1 to 99 mol%, more preferably 30 to 95 mol%, particularly 50 to 90 mol%, based on the total diamine. It is preferable.
The diamine used for synthesizing the polyamic acid preferably contained in the liquid crystal aligning agent of the present invention is composed of only the diamine (A), or composed of only the diamine (A) and other specific diamines. preferable.

[Synthesis of polyamic acid]
The polyamic acid contained in the liquid crystal aligning agent of this invention is obtained by making tetracarboxylic dianhydride and diamine containing diamine (A) react.
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, More preferably, it is the ratio which becomes 0.3-1.2 equivalent.
The polyamic acid synthesis reaction is preferably performed in an organic solvent, preferably at a temperature of −20 ° C. to 150 ° C., more preferably 0 to 100 ° C., and preferably 0.1 to 24 hours, more preferably 0.00. 5 to 12 hours.
Examples of the organic solvent that can be used in the synthesis of the polyamic acid include an aprotic polar solvent, phenol and derivatives thereof, alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon and the like. Examples of the aprotic polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide and the like. ;
Examples of the phenol derivative include m-cresol, xylenol, halogenated phenol and the like;
Examples of the alcohol include methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether;
Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;
Examples of the ester include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate;

Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether. Acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, etc .;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like;
Examples of the hydrocarbon include hexane, heptane, octane, benzene, toluene, xylene, isoamylpropionate, isoamylisobutyrate, and diisopentyl ether.
Among these organic solvents, one or more selected from the group consisting of an aprotic polar solvent and phenol and derivatives thereof (first group organic solvent), or one selected from the first group of organic solvents It is preferable to use a mixture of the above and one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (second group organic solvent). In the latter case, the use ratio of the second group of organic solvents is preferably 50% by weight or less, more preferably 40% by weight or less, with respect to the total of the first group of organic solvents and the second group of organic solvents. Furthermore, it is preferable that it is 30 weight% or less.

As described above, a reaction solution obtained by dissolving polyamic acid is obtained.
This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent.
When polyamic acid is dehydrated and cyclized into a polyimide, the above reaction solution may be directly subjected to dehydration and cyclization reaction, or may be subjected to dehydration and cyclization reaction after isolating the polyamic acid contained in the reaction solution. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration ring closure reaction.
The polyamic acid is isolated by pouring the reaction solution into a large amount of poor solvent to obtain a precipitate, and drying the precipitate under reduced pressure, or by distilling off the solvent in the reaction solution under reduced pressure using an evaporator. It can be carried out. In addition, a method of dissolving this polyamic acid in an organic solvent again and then precipitating with a poor solvent, or a step of washing a solution obtained by dissolving polyamic acid in an organic solvent again and then distilling it off under reduced pressure again with an evaporator 1 The polyamic acid can be purified by a method performed once or several times.

<Polyimide>
The polyimide that can be contained in the liquid crystal aligning agent of the present invention can be obtained by dehydrating and ring-closing imidizing the polyamic acid obtained as described above.
The polyimide preferably contained in the liquid crystal aligning agent of the present invention may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the polyamic acid as a raw material had, and only a part of the amic acid structure is included. It may be a partially imidized product that is dehydrated and cyclized and has both an amic acid structure and an imide ring structure. The polyimide preferably contained in the liquid crystal aligning agent of the present invention preferably has an imidation ratio of 30% or more, more preferably 40% or more, and particularly preferably 50 to 90%. The said imidation rate represents the ratio which the number of the imide ring structure accounts with respect to the sum total of the number of the amic acid structures of polyimide, and the number of imide ring structures in percentage. At this time, a part of the imide ring may be an isoimide ring.
The dehydration ring closure of the polyamic acid is preferably performed by (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, and adding a dehydrating agent and a dehydration ring closure catalyst to this solution as necessary. This is done by heating.
The reaction temperature in the method (i) of heating the polyamic acid is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the resulting polyimide may decrease. The reaction time is preferably 1.0 to 24 hours, more preferably 1.0 to 12 hours.

On the other hand, in the method (ii) of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can do. The use ratio of the dehydrating agent depends on the desired imidization rate, but is preferably 0.01 to 20 mol with respect to 1 mol of the amic acid structure of the polyamic acid. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. However, it is not limited to these. The use ratio of the dehydration ring-closing catalyst is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent to be used. The imidation rate can be increased as the proportion of the dehydrating agent and dehydrating ring-closing agent increases. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.
The polyimide obtained in the above method (i) may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after purifying the obtained polyimide. On the other hand, in the above method (ii), a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. It may be used for the preparation of a liquid crystal aligning agent or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. In order to remove the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution, for example, a method such as solvent replacement can be applied. The isolation and purification of the polyimide can be performed by performing the same operation as described above as the isolation and purification method of the polyamic acid.

-End-modified polymer-
The polyamic acid and the polyimide contained in the liquid crystal aligning agent of the present invention may be terminal-modified polymers each having a molecular weight adjusted. By using the terminal-modified polymer, the coating properties of the liquid crystal aligning agent can be further improved without impairing the effects of the present invention. Such a terminal-modified polymer can be obtained by adding an appropriate molecular weight regulator to the polymerization reaction system when synthesizing a polyamic acid. Examples of molecular weight regulators include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like.
Examples of the acid monoanhydride include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, n -Hexadecyl succinic anhydride etc. can be mentioned. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, Examples include n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine. it can. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.
The use ratio of the molecular weight modifier is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, with respect to 100 parts by weight of the total of tetracarboxylic dianhydride and diamine used when synthesizing the polyamic acid. .

-Solution viscosity-
The polyamic acid and polyimide obtained as described above preferably have a solution viscosity of 20 to 800 mPa · s, and a solution viscosity of 30 to 500 mPa · s, respectively, when a solution having a concentration of 10% by weight is obtained. It is more preferable that it has.
The solution viscosity (mPa · s) of the above polymer is E for a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). It is a value measured at 25 ° C. using a mold rotational viscometer.

<Other additives>
The liquid crystal alignment film of the present invention contains the specific polymer as described above as an essential component, but may contain other components as necessary. Examples of such other components include other polymers, compounds having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”), and functional silane compounds.
[Other polymers]
These other polymers can be used to improve solution and electrical properties. Such other polymer is a polymer other than the specific polymer. For example, a polyamic acid obtained by reacting a tetracarboxylic dianhydride with a diamine not containing the diamine (A) (hereinafter referred to as “other polyamic acid”). ), A polyimide obtained by dehydrating and ring-closing the polyamic acid (hereinafter referred to as “other polyimide”), polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene- Phenylmaleimide) derivatives, poly (meth) acrylates and the like. Of these, other polyamic acids or other polyimides are preferred.
The use ratio of the other polymer is preferably 85% by weight or less, more preferably based on the total of the polymers (referring to the total of the above-mentioned specific polymer and other polymers; the same shall apply hereinafter). It is preferably 50% by weight or less, more preferably 40% by weight or less, and particularly preferably 30% by weight or less. In particular, it is preferable not to use other polymers.

[Epoxy compound]
The epoxy compound is preferably a compound having at least two epoxy groups in the molecule. For example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene Glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohex N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidyl-aminomethylcyclohexane, N, N-diglycidyl-cyclohexylamine Etc. can be mentioned as preferred.
The compounding ratio of these epoxy compounds is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the total amount of the polymer.

[Functional silane compounds]
Examples of the functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyl Trimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4 7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9- Triethoxysilyl-3,6-diazanonyl acetate, methyl 9-trimethoxysilyl-3,6-diazananoate, methyl 9-triethoxysilyl-3,6-diazananoate, N-benzyl-3-aminopropyltri Methoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxy Methyltriethoxysilane, 2-glycidoxyethyltrimeth Shishiran, 2-glycidoxyethyl triethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyl triethoxy silane and the like.
The blending ratio of these functional silane-containing compounds is preferably 2 parts by weight or less, more preferably 0.2 parts by weight or less, with respect to 100 parts by weight of the total polymer.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is constituted by dissolving the specific polymer as described above and other additives optionally blended as required, preferably dissolved in an organic solvent.
Examples of the organic solvent that can be used in the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4. -Methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, Ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl Ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, etc. Can be mentioned. These can be used alone or in admixture of two or more.

The solid content concentration in the liquid crystal aligning agent of the present invention (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, and the like. The range is preferably 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface as described later, and preferably, when heated, a coating film that becomes a liquid crystal aligning film is formed, but the solid content concentration is less than 1% by weight. In this case, the film thickness of the coating film becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by weight, the film thickness of the coating film becomes excessive. Thus, a good liquid crystal alignment film cannot be obtained, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating properties.
The particularly preferable solid content concentration range varies depending on the method used when applying the liquid crystal aligning agent to the substrate. For example, when the spinner method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thereby the solution viscosity is in the range of 3 to 15 mPa · s.
The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 10 to 50 degreeC, More preferably, it is 20 to 30 degreeC.

<Liquid crystal display element>
The liquid crystal display element of the present invention comprises a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention as described above.
The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In step (1), the substrate to be used varies depending on the desired operation mode. Steps (2) and (3) are common to each operation mode.
(1) First, the liquid crystal aligning agent of this invention is apply | coated on a board | substrate, Then, a coating film is formed on a board | substrate by heating an application surface.

(1-1) When manufacturing a TN type, STN type, or VA type liquid crystal display element, a pair of two substrates provided with a patterned transparent conductive film is used as a pair on the transparent conductive film formation surface. The liquid crystal aligning agent of the present invention is preferably applied by an offset printing method, a spin coating method or an ink jet printing method, respectively, and then each coated surface is heated to form a coating film. Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly (alicyclic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. In order to obtain a patterned transparent conductive film which can be used, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, a mask having a desired pattern when forming the transparent conductive film The method using can be used. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound or functional titanium is formed on the surface of the substrate surface on which the coating film is to be formed. You may give the pretreatment which apply | coats a compound etc. previously.
After applying the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied aligning agent. The pre-baking temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 40 to 100 ° C. The pre-bake time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Then, a baking (post-baking) process is implemented for the purpose of removing a solvent completely, and heat imidizing a polyamic acid as needed. The firing (post-bake) temperature is preferably 80 to 300 ° C, more preferably 120 to 250 ° C, and the post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. Thus, the film thickness of the formed film is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

(1-2) On the other hand, when manufacturing an IPS type liquid crystal display element, the conductive film forming surface of the substrate provided with the comb-shaped transparent conductive film and the counter substrate provided with no conductive film The liquid crystal aligning agent of this invention is apply | coated to one surface, respectively, Then, a coating film is formed by heating each application surface.
The material of the substrate and transparent conductive film, the patterning method of the transparent conductive film, the pretreatment of the substrate, the coating method of the liquid crystal aligning agent, and the heating method after coating used in this case are the same as in (1-1) above.
The preferable film thickness of the coating film to be formed is the same as (1-1) above.

(2) When the liquid crystal display element manufactured by the method of the present invention is a VA liquid crystal display element, the coating film formed as described above can be used as a liquid crystal alignment film as it is. If desired, it may be used after the following rubbing treatment.
On the other hand, when manufacturing a liquid crystal display element other than the VA type, a rubbing treatment is performed on the coating film formed as described above to obtain a liquid crystal alignment film.
The rubbing treatment can be performed by rubbing the coating film surface formed as described above with a roll wound with a cloth made of fibers such as nylon, rayon, and cotton in a certain direction. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film.
Further, for the liquid crystal alignment film formed as described above, liquid crystal alignment as described in, for example, Patent Document 6 (JP-A-6-222366) and Patent Document 7 (JP-A-6-281937). A process for changing the pretilt angle of a partial region of the liquid crystal alignment film by irradiating a part of the film with ultraviolet rays, or a liquid crystal alignment film as described in Patent Document 8 (Japanese Patent Laid-Open No. 5-107544) Form a resist film on a part of the surface, and then perform a rubbing process in a direction different from the previous rubbing process, and then remove the resist film, so that the liquid crystal alignment film has different liquid crystal alignment capabilities for each region. Thus, it is possible to improve the visual field characteristics of the liquid crystal display element obtained.

(3) A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above, and disposing a liquid crystal between the two substrates opposed to each other. Here, when the rubbing process is performed on the coating film, the two substrates are disposed to face each other so that the rubbing directions in the respective coating films are at a predetermined angle, for example, orthogonal or antiparallel.
In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.
The first method is a conventionally known method. First, two substrates are arranged to face each other through a gap (cell gap) so that the respective liquid crystal alignment films are opposed to each other, and the peripheral portions of the two substrates are bonded using a sealant, and the substrate surface and the sealant are bonded. A liquid crystal cell can be manufactured by injecting and filling liquid crystal into the cell gap partitioned by the above, and then sealing the injection hole.
The second method is a method called an ODF (One Drop Fill) method. For example, an ultraviolet light curable sealing material is applied to a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is dropped on the liquid crystal alignment film surface. The other substrate is bonded so as to face each other, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, whereby a liquid crystal cell can be manufactured.
Regardless of which method is used, the liquid crystal cell produced as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase and then gradually cooled to room temperature. It is desirable to remove.
And the liquid crystal display element of this invention can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell.

Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.
As the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal, or the like can be used, and among these, a nematic liquid crystal is preferable. In the case of a VA liquid crystal cell, a nematic liquid crystal having negative dielectric anisotropy is preferable. For example, dicyanobenzene liquid crystal, pyridazine liquid crystal, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, and phenylcyclohexane liquid crystal are used. It is done. In the case of a TN type liquid crystal cell or an STN type liquid crystal cell, a nematic type liquid crystal having positive dielectric anisotropy is preferable. For example, biphenyl type liquid crystal, phenyl cyclohexane type liquid crystal, ester type liquid crystal, terphenyl type liquid crystal, biphenyl cyclohexane type A liquid crystal, a pyrimidine liquid crystal, a dioxane liquid crystal, a bicyclooctane liquid crystal, a cubane liquid crystal, or the like is used. For example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names C-15 and CB-15 (manufactured by Merck); Ferroelectric liquid crystals such as -p-amino-2-methylbutyl cinnamate may be further added and used.
As a polarizing plate bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an “H film” that absorbs iodine while stretching and aligning polyvinyl alcohol is sandwiched between protective films of cellulose acetate The polarizing plate which consists of itself can be mentioned.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The polymer solution viscosity and polyimide imidation ratio in the following synthesis examples were evaluated by the following methods.
[Solution viscosity of polymer]
The solution viscosity (mPa · s) of the polymer was measured at 25 ° C. using an E-type rotational viscometer for each N-methylpyrrolidone solution adjusted to a polymer concentration of 10% by weight.
[Imidation rate of polyimide]
The imidization rate of the polymer was determined by putting a small amount of the polyimide solution obtained in each synthesis example into pure water, collecting the produced precipitate and drying it under reduced pressure at room temperature, and then converting this to deuterated dimethyl sulfoxide. dissolved, from ^{1 H-NMR} spectrum was measured at room temperature using tetramethylsilane as a reference substance was determined by the following equation (1).
Imidation rate (%) = (1-A ¹ / A ² × α) × 100 (1)
(In Formula (1), A ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, A ² is a peak area derived from other protons, and α is a precursor of a polymer (polyamic acid). The number ratio of other protons to one proton of NH group in)

<Synthesis example of diamine (A)>
Synthesis example A1
Scheme 1 below

Thus, a compound represented by the above formula (A-1) (hereinafter referred to as “compound (A-1)”) was synthesized.
1,3-adamantanediol 0.30 mol (50.47 g), sodium hydride (50 wt% oil suspension) 0.66 mol-NaH (31.68 g as suspension), toluene 540 ml and N, N-dimethyl Formamide 360 ml was mixed and reacted at 80 ° C. with stirring for 1 hour. Next, after the reaction mixture was cooled to 20 ° C., a solution of 0.63 mol (88.89 g) of 4-fluoronitrobenzene in 180 mL of N, N-dimethylformamide was added dropwise over 1 hour. After completion of the dropping, the reaction was carried out at 110 ° C. with stirring for 64 hours. After cooling the reaction mixture to 5 ° C., 2,700 mL of distilled water was added thereto and extracted with 1,800 mL of dichloromethane. The dichloromethane layer was washed three times with 1,500 mL of distilled water, dried over magnesium sulfate, and then the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.19 mol (77.98 g) of Compound 1.
Under a nitrogen atmosphere, 0.19 mol (77.98 g) of the above compound 1, 3.35 g of Pd / C (palladium carbon), 300 mL of tetrahydrofuran and 300 mL of ethanol were mixed and stirred at 60 ° C. Next, 47.6 mL of hydrazine monohydrate was added dropwise thereto over 1 hour, and then reacted at 60 ° C. with stirring for 4 hours. After completion of the reaction, Pd / C was removed from the reaction mixture by Celite filtration, and then the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.17 mol (59.57 g) of compound (A-1).
Synthesis example A2
Scheme 2 below

Thus, a compound represented by the above formula (A-2) (hereinafter referred to as “compound (A-2)”) was synthesized.
Under a nitrogen atmosphere, 0.33-mol (50.47 g) of 1,3-adamantanediol, 0.60 mol (60.04 g) of succinic anhydride, 26.0 mmol (3.18 g) of 4-dimethylaminopyridine, 400 mL of ethyl acetate and Triethylamine 0.36 mol (49.9 mL) was mixed, and the reaction was conducted with stirring under reflux for 18 hours. After removing the solvent from the reaction mixture under reduced pressure, 800 mL of chloroform was added to the residue, and the residue was washed successively with 400 mL of diluted hydrochloric acid and twice with 400 mL of distilled water. The chloroform layer after washing was dehydrated with magnesium sulfate, and then the solvent was removed under reduced pressure. The obtained solid was washed with ethyl acetate and dried to obtain 0.22 mol (81.04 g) of Compound 2.
0.22 mol (81.04 g) of Compound 2, 176 mL of thionyl chloride and a catalytic amount of dimethylformamide were mixed and reacted at 80 ° C. with stirring for 1 hour. Unreacted thionyl chloride was removed from the reaction mixture by reducing the pressure using a water flow aspirator, and then 300 mL of methylene chloride was added. The obtained solution was passed through 60 mL of distilled water three times, then dehydrated with magnesium sulfate, and the solvent was removed under reduced pressure. Tetrahydrofuran (200 mL) was added to the residue to obtain a solution (1).
4-Nitrophenol 0.46 mol (63.99 g), tetrahydrofuran 400 mL and triethylamine 0.66 mol (91.5 mL) were mixed and stirred in an ice bath. The solution (1) was added dropwise thereto over 1 hour, and then reacted at 25 ° C. with stirring for 4 hours. 1,200 mL of ethyl acetate was added to the reaction mixture, and after washing 4 times with 500 mL of distilled water, the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.20 mmol (122.11 g) of Compound 3.
Under a nitrogen atmosphere, 0.20 mol (122.11 g) of compound 3, 4.00 mol (261.56 g) of zinc, 0.80 mol (42.79 g) of ammonium chloride, 720 mL of ethanol and 720 mL of tetrahydrofuran were mixed and stirred at 0 ° C. did. Distilled water (100 mL) was added thereto, and the reaction was carried out by stirring at 25 ° C. for 8 hours. After removing the catalyst system from the reaction mixture by Celite filtration, 1,200 mL of ethyl acetate was added, and the resulting solution was washed 4 times with 800 mL of distilled water. After removing the solvent from the washed solution under reduced pressure, the obtained solid was recrystallized from ethanol to obtain 0.14 mol (77.08 g) of Compound (A-2).
Synthesis example A3
Scheme 3 below

Thus, a compound represented by the above formula (A-4) (hereinafter referred to as “compound (A-4)”) was synthesized.
1,3-adamantanediol 0.5 mol (84.12 g), triethylamine 1.50 mol (207.9 mL) and tetrahydrofuran 1,200 mL were mixed and stirred in an ice bath. A solution composed of 1.05 mol (194.84 g) of 4-nitrobenzoyl chloride and 600 mL of tetrahydrofuran was added dropwise thereto over 2 hours, and the reaction was carried out at 25 ° C. with stirring for 4 hours. Next, 2,500 mL of ethyl acetate was added to the reaction mixture, and after washing 4 times with 1,000 mL of distilled water, the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.39 mol (181.91 g) of Compound 4.
Under a nitrogen atmosphere, 0.39 mol (181.91 g) of Compound 4, 6.87 g of Pd / C, 600 mL of tetrahydrofuran and 600 mL of ethanol were mixed and stirred at 60 ° C. After 97.6 mL of hydrazine monohydrate was added dropwise over 1 hour, the reaction was carried out at 60 ° C. with stirring for 4 hours. After removing Pd / C from the reaction mixture by Celite filtration, the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.33 mol (134.14 g) of Compound (A-4).
Synthesis example A4
Scheme 4 below

Thus, a compound represented by the above formula (A-6) (hereinafter referred to as “compound (A-6)”) was synthesized.
Mixing 0.60 mol (117.78 g) of 1,3-bis (hydroxymethyl) adamantane, 1.32 mol (186.26 g) of 4-fluoronitrobenzene, 2.40 mol (331.70 g) of potassium carbonate and 1,000 mL of dimethylformamide The reaction was conducted at 80 ° C. with stirring for 18 hours. 1,000 mL of distilled water was added to the reaction mixture, and the precipitate (solid) was collected by filtration. The obtained solid was sufficiently washed with water and then recrystallized from ethanol to obtain 0.56 mol (245.54 g) of Compound 5.
Under a nitrogen atmosphere, 0.56 mol (245.54 g) of the above compound 5, 9.86 g of Pd / C, 900 mL of tetrahydrofuran and 900 mL of ethanol were mixed and stirred at 25 ° C. After 140.2 mL of hydrazine monohydrate was added dropwise over 2 hours, the reaction was performed at 25 ° C. with stirring for 24 hours. After removing Pd / C from the reaction mixture by Celite filtration, the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.52 mol (196.82 g) of compound (A-6).
Synthesis example A5
Schemes 5 (1) and 5 (2) below

Thus, a compound represented by the above formula (A-7) (hereinafter referred to as “compound (A-7)”) was synthesized.
4-nitrophenol 0.75 mol (104.33 g), succinic anhydride 1.50 mol (150.11 g), 4-dimethylaminopyridine 0.09 mol (11.00 g), ethyl acetate 1,500 mL and triethylamine 0.9 mol (124.8 mL) was mixed and reacted at 25 ° C. with stirring for 6 hours. After adding 750 mL of ethyl acetate to the reaction mixture, the mixture was washed twice with 1500 mL of diluted hydrochloric acid and three times with 1500 mL of distilled water. After removing the solvent from the washed reaction mixture under reduced pressure, it was applied to a column chromatograph (developing solvent: chloroform / ethanol = 20/1 (volume ratio)), and the solvent was removed from the corresponding fraction under reduced pressure. Compound 7 (0.57 mol, 136.33 g) was obtained.
0.53 mol (126.77 g) of the above compound 6, 200 mL of thionyl chloride and a catalytic amount of dimethylformamide were mixed and reacted at 80 ° C. with stirring for 1 hour. After removing the unreacted thionyl chloride from the reaction mixture by reducing the pressure with a water flow aspirator, 800 mL of methylene chloride was added to make a solution. This solution was passed through 160 mL of distilled water three times and then dehydrated with magnesium sulfate. Next, after removing the solvent from the dehydrated solution under reduced pressure, 500 mL of tetrahydrofuran was added to obtain a solution (2).
0.25 mol (49.07 g) of 1,3-bis (hydroxymethyl) adamantane, 500 mL of tetrahydrofuran and 0.75 mol (104.0 mL) of triethylamine were mixed and stirred in an ice bath. The solution (2) was added dropwise thereto over 1 hour, and then reacted at 25 ° C. with stirring for 3 hours. After adding 3,000 mL of ethyl acetate to the reaction mixture, it was washed 4 times with 1,000 mL of distilled water. The solid obtained by removing the solvent from the reaction mixture after washing under reduced pressure was recrystallized from ethanol to obtain 0.19 mol (121.34 g) of Compound 7.
Under a nitrogen atmosphere, 0.19 mol (121.34 g) of the above compound 7, 3.80 mol (248.48 g) of zinc, 0.76 mol (40.65 g) of ammonium chloride, 680 mL of ethanol and 680 mL of tetrahydrofuran were mixed at 0 ° C. Stir. Distilled water (95 mL) was added thereto, and the reaction was carried out at 25 ° C. with stirring for 8 hours. Insoluble catalyst was removed from the reaction mixture by Celite filtration. Next, 1,200 mL of ethyl acetate was added thereto, and after washing with 800 mL of distilled water four times, the solid obtained by removing the solvent under reduced pressure was recrystallized from ethanol to obtain Compound (A-7) 0. .16 mol (87.46 g) was obtained.
Synthesis Example A6
Scheme 6 below

Thus, a compound represented by the above formula (A-9) (hereinafter referred to as “compound (A-9)”) was synthesized.
1,3-bis (hydroxymethyl) adamantane 0.5 mol (98.15 g), triethylamine 1.50 mol (207.9 mL) and tetrahydrofuran 1200 mL were mixed and stirred in an ice bath. A solution composed of 1.05 mol (194.84 g) of 4-nitrobenzoyl chloride and 600 mL of tetrahydrofuran was added dropwise thereto over 2 hours, and the reaction was carried out at 25 ° C. with stirring for 4 hours. The reaction mixture was added with 2500 mL of ethyl acetate, washed with 1,000 mL of distilled water four times, and then the solvent was removed under reduced pressure, and the resulting solid was recrystallized from ethanol to obtain 0.41 mol of compound 8. (202.74 g) was obtained.
Under a nitrogen atmosphere, 0.41 mol (202.74 g) of the above compound 8, 7.22 g of Pd / C, 630 mL of tetrahydrofuran and 630 mL of ethanol were mixed and stirred at 60 ° C. To this was added dropwise 102.6 mL of hydrazine monohydrate over 1 hour, and the reaction was carried out at 60 ° C. with stirring for 4 hours. After removing Pd / C from the reaction mixture by Celite filtration, the solvent was removed under reduced pressure. The obtained solid was recrystallized from ethanol to obtain 0.34 mol (147.74 g) of compound (A-9).
Synthesis example A7
Scheme 7 below

Thus, a compound represented by the above formula (A-11) (hereinafter referred to as “compound (A-11)”) was synthesized.
1,3-adamantane dicarboxylic acid 0.5 mol (112.13 g), thionyl chloride 400 mL, and a catalytic amount of dimethylformamide were mixed and reacted at 80 ° C. with stirring for 1 hour. After removing the unreacted thionyl chloride from the reaction mixture by reducing the pressure with a water flow aspirator, 680 mL of methylene chloride was added to make a solution. This solution was passed through 150 mL of distilled water three times, then dehydrated with magnesium sulfate, and the solvent was removed under reduced pressure to obtain a solid. This solid was dissolved in 450 mL of tetrahydrofuran to obtain a solution (3).
4-Nitrophenol 1.05 mol (146.07 g), tetrahydrofuran 800 mL, triethylamine 1.50 mol (207.9 mL) were mixed and stirred in an ice bath. The above solution (3) was added over 1 hour. After the dropwise addition, the reaction was carried out at 25 ° C. with stirring for 4 hours. 2,800 mL of ethyl acetate was added to the reaction mixture, and after washing 4 times with 1,200 mL of distilled water, the solvent was removed under reduced pressure to obtain a solid. The obtained solid was recrystallized from ethanol to obtain 0.41 mmol (191.24 g) of Compound 9.
Under a nitrogen atmosphere, 0.41 mol (191.24 g) of the above compound 9, 8.20 mol (536.20 g) of zinc, 1.64 mol (87.72 g) of ammonium chloride, 1,500 mL of ethanol and 1,500 mL of tetrahydrofuran were mixed. And stirred at 0 ° C. Distilled water (200 mL) was added thereto, and the reaction was carried out at 25 ° C. with stirring for 8 hours. After removing insoluble catalyst from the reaction mixture by Celite filtration, 2,500 mL of ethyl acetate was added, and the resulting solution was washed 4 times with 1500 mL of distilled water. The solid obtained by removing the solvent from the washed solution under reduced pressure was recrystallized from ethanol to obtain 0.29 mol (117.88 g) of Compound (A-11).
Synthesis Example A8
Scheme 8 (1) and 8 (2) below

Thus, a compound represented by the above formula (A-12) (hereinafter referred to as “compound (A-12)”) was synthesized.
4-Nitrophenol 0.5 mol (69.56 g), potassium carbonate 0.75 mol (103.66 g), 2-bromoethanol 0.75 mol (53.6 mL) and acetonitrile 500 mL were mixed and stirred at 85 ° C. for 24 hours. The reaction was performed. A solution obtained by adding 1,500 mL of ethyl acetate to the reaction mixture was washed four times with 1,000 mL of distilled water. The solid obtained by removing the solvent from the washed solution under reduced pressure is applied to a column chromatograph (developing solvent: chloroform / ethanol = 20/1 (volume ratio)), and the solvent is removed from the corresponding fraction under reduced pressure. As a result, 0.48 mol (87.92 g) of Compound 10 was obtained.
0.2 mol (44.85 g) of 1,3-adamantane dicarboxylic acid, 160 mL of thionyl chloride and a catalytic amount of dimethylformamide were mixed and reacted at 80 ° C. with stirring for 1 hour. After removing the unreacted thionyl chloride from the reaction mixture by reducing the pressure with a water flow aspirator, 270 mL of methylene chloride was added to make a solution. This solution was passed through 60 mL of distilled water three times, then dehydrated with magnesium sulfate, and the solvent was removed under reduced pressure to obtain a solid. This solid was dissolved in 180 mL of tetrahydrofuran to obtain a solution (4).
0.42 mol (76.93 g) of the above compound 10, 320 mL of tetrahydrofuran and 0.60 mol (83.2 mL) of triethylamine were mixed and stirred in an ice bath, and the solution (4) was added dropwise thereto over 1 hour. Thereafter, the reaction was carried out at 25 ° C. with stirring for 4 hours. A solution obtained by adding 1,200 mL of ethyl acetate to the reaction mixture was washed four times with 500 mL of distilled water, and then the solvent was removed under reduced pressure. Obtained .15 mmol (83.17 g).
Under a nitrogen atmosphere, 0.15 mol (83.17 g) of Compound 11 above, 2.64 g of Pd / C, 240 mL of tetrahydrofuran and 240 mL of ethanol were mixed and stirred at 25 ° C. After 37.6 mL of hydrazine monohydrate was added dropwise over 1 hour, the reaction was carried out at 25 ° C. with stirring for 24 hours. After removing Pd / C from the reaction mixture by Celite filtration, the solid obtained by removing the solvent under reduced pressure was recrystallized from ethanol to obtain 0.13 mol (64.30 g) of Compound (A-12). Obtained.

<Synthesis of specific polymer>
Synthesis examples P1 to P16
To N-methyl-2-pyrrolidone, diamines and tetracarboxylic dianhydrides of the types and amounts shown in Table 1 are added in the order shown in the table to form a solution having a monomer concentration of 20% by weight. By carrying out the reaction for a time, solutions containing polyamic acids (PA-1) to (PA-16) were obtained. A small amount of each solution was sampled, and the solution viscosity measured as a solution having a polyamic acid concentration of 10% by weight by adding N-methyl-2-pyrrolidone is shown in Table 1.
Half of each of these polyamic acid solutions was secured and used in the following Examples 1 to 15, 31 and 32 and Comparative Example 1, respectively.
After adding pyridine and acetic anhydride to the remaining half of each polyamic acid solution so as to have a molar ratio shown in Table 1 with respect to 1 mol of the amic acid unit of the polyamic acid, heating to 110 ° C. Then, dehydration ring closure reaction was carried out for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with new N-methyl-2-pyrrolidone (in this operation, pyridine and acetic anhydride used for the dehydration ring-closing reaction were removed from the system), and polyimide was obtained. A solution containing about 16% by weight of (PI-1) to (PI-16) was obtained. Table 1 shows the imidization ratio of each polyimide contained in these polyimide solutions and the solution viscosities measured as N-methyl-2-pyrrolidone solutions having a polyimide concentration of 10% by weight.
These polyimide solutions were used in Examples 16 to 32 and Comparative Example 2 below.
Synthesis example P16 is a comparative synthesis example.

In Table 1, the abbreviations for diamine and tetracarboxylic acid anhydride have the following meanings, respectively.
<Diamine>
[Diamine (A)]
The symbols described in the columns correspond to the symbols of the compounds synthesized in Synthesis Examples A1 to A8.
[Other diamines]
d-1: 3,5-diaminobenzoic acid d-2: cholestanyloxy-2,4-diaminobenzene d-3: cholestanyl 3,5-diaminobenzoate d-4: p-phenylenediamine d-5: 1 -(2,4-diaminophenyl) piperazine-4-carboxylic acid d-6: 4- (morpholin-4-yl) benzene-1,3-diamine d-7: 4,4-diaminobenzanilide <tetracarboxylic acid Dianhydride>
t-1: 2,3,5-tricarboxycyclopentylacetic acid dianhydride t-2: 1,2,3,4-cyclobutanetetracarboxylic dianhydride t-3: 1,3,3a, 4,5 9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione

<Preparation and evaluation of liquid crystal aligning agent>
Example 1
(I) Preparation of liquid crystal aligning agent (1) Preparation of liquid crystal aligning agent for evaluation of printability In a solution containing 100 parts by weight of polyamic acid (PA-1) obtained in Synthesis Example P1, N-methyl-2- Pyrrolidone (NMP) and butyl cellosolve (BC) were added to obtain a solution having a solvent composition of NMP: BC = 70: 30 (weight ratio) and a solid content concentration of 6.5% by weight. A liquid crystal aligning agent for printability evaluation was prepared by filtering this solution using a filter having a pore diameter of 1 μm.
(2) Preparation of Liquid Crystal Alignment Agent for Manufacturing Liquid Crystal Display Element In the preparation of the liquid crystal alignment agent for evaluation of printability, liquid crystal alignment was performed in the same manner as above except that the solid content concentration of the solution before filtration was 4.0% by weight. A liquid crystal aligning agent for producing display elements was prepared.
(II) Evaluation of Liquid Crystal Alignment Agent Each of the two alignment agents prepared above was evaluated by the following methods.
(1) Evaluation of printability (1-1) Evaluation of applicability The liquid crystal aligning agent for printability evaluation prepared above is applied to an anix roll using a liquid crystal alignment film printer (manufactured by Nissha Printing Co., Ltd.). The liquid crystal aligning agent dropping amount was applied to the transparent electrode surface of the glass substrate with a transparent electrode made of an ITO film under the condition of 15 reciprocating drops (about 0.15 g). Here, the liquid crystal aligning agent dropping amount is smaller than the dropping amount (reciprocal 30 drops, about 0.3 g) usually employed in the same type of printing press, and is a more severe printing condition. The substrate after application of the liquid crystal aligning agent was heated (prebaked) at 80 ° C. for 1 minute to remove the solvent, and then heated (postbaked) at 180 ° C. for 10 minutes to form a coating film having an average film thickness of 600 mm. The coating film was observed with a microscope with a magnification of 20 times to examine the presence or absence of repellency and coating unevenness, and when both were not observed, the printability was “good”, and when either was observed, the printability was “bad”. As evaluated. The evaluation results are shown in Table 2.
(1-2) Evaluation of film thickness uniformity About the coating film formed above, using a stylus type film thickness meter (manufactured by KLA Tencor), the film thickness at the center of the substrate and 15 mm from the outer edge of the coating film to the center. The film thickness at the approached position was measured, and the film thickness difference between the two was examined. This value is shown in Table 2.
If this film thickness difference is 25 mm or less, the film thickness uniformity is excellent (very good), and if it exceeds 25 mm and 50 mm or less, it can be said that the film thickness uniformity is good.

(2) Manufacture of liquid crystal display element On the transparent conductive film made of ITO film provided on one surface of a 1 mm thick glass substrate, the liquid crystal aligning agent for liquid crystal display element preparation prepared above is applied by a spinner, and a hot plate A pre-bake was performed at 80 ° C. for 1 minute and then post-baked at 220 ° C. for 15 minutes to form a coating film (liquid crystal alignment film) having an average film thickness of 800 mm. This operation was repeated to produce two (a pair) substrates having a liquid crystal alignment film.
After applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm to the outer edges of each of the pair of substrates having the liquid crystal alignment film, they are stacked so that the liquid crystal alignment film surfaces face each other. The adhesive was cured by pressing together. Next, a negative type liquid crystal (MLC-6608, manufactured by Merck & Co., Inc.) is filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photo-curing adhesive, and both sides on the outside of the substrate are sealed A vertically aligned liquid crystal display element was manufactured by laminating a polarizing plate.
(3) Evaluation of heat resistance The liquid crystal display element manufactured above was applied with a voltage of 5 V at 70 ° C. with an application time of 60 microseconds and a span of 167 milliseconds, and then a voltage after 167 milliseconds from the release of application. The retention rate was measured by “VHR-1” manufactured by Toyo Corporation. The numerical value at this time was defined as the initial voltage holding ratio (VHR _BF ).
Next, thermal stress was applied to the liquid crystal cell after the initial voltage holding ratio measurement at an environmental temperature of 100 ° C. for 1000 hours.
With respect to the liquid crystal cell after heat stress, the voltage holding ratio was measured again by the same method as described above. The numerical value at this time was defined as a voltage holding ratio (VHR _AF ) after light irradiation.
By subtracting VHR _AF from the VHR _BF measured above, the change in voltage holding ratio (ΔVHF) before and after light irradiation was determined. These values are shown in Table 2.
When this change is less than 2.0%, the heat resistance is excellent (very good), and when it is 2.0% or more and less than 5.0%, the heat resistance is good, and 5.0% or more. If there is, it can be said that the heat resistance is poor.

Examples 2-32 and Comparative Examples 1 and 2
As the polymer-containing solution, the solutions containing the polymers shown in Table 2 were used, respectively, and when NMP and BC were added to the polymer solution in the preparation of the liquid crystal aligning agent when specially listed in Table 2, Two types of liquid crystal aligning agents were prepared and evaluated in the same manner as in Example 1 except that the types and amounts of the epoxy compounds specified in Table 2 were further added. The evaluation results are shown in Table 2.
In Examples 31 and 32, two types of polymer solutions were mixed and used so that the mixing ratio of the polymers in the liquid crystal aligning agent was the value described in Table 2.

In Table 2, the abbreviations for epoxy compounds have the following meanings, respectively.
G1: N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane G2: N, N, N ′, N′-tetraglycidyl-m-xylenediamine

Claims (4)

It contains at least one polymer selected from the group consisting of a polyamic acid having a structure represented by the following formula (A ″) and a polyimide having a structure represented by the following formula (A ″). A liquid crystal aligning agent.

(In the formula (A ″), X ¹ and X ³ are each independently an ether bond or an ester bond,
X ² and X ⁴ are each independently an ether bond or an ester bond,
Each R is independently a methylene group or an alkylene group having 2 to 6 carbon atoms;
a1, a2, a3 and a4 are each independently 0 or 1,
R ¹ is a hydroxyl group, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, or a carboxyalkyl group having 2 to 5 carbon atoms,
a5 is an integer of 0 to 14,
“*” Indicates a bond. ) The polymer is
Tetracarboxylic dianhydride and the following formula (A0)

(In the formula (A0), X ¹ , X ³ , X ² , X ⁴ , R, R ¹ , a 1, a 2, a 3, a 4 and a 5 are respectively synonymous with those in the above formula (A ″),
Each R ² is independently a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a carboxyalkyl group having 2 to 5 carbon atoms;
a6 is an integer of 0-4 each independently. )
2. The polymer according to claim 1, which is at least one polymer selected from the group consisting of a polyamic acid obtained by reacting with a diamine containing a compound represented by formula (1) and a polyimide obtained by dehydrating and ring-closing the polyamic acid. Liquid crystal aligning agent.   A liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1. A liquid crystal display element comprising the liquid crystal alignment film according to claim 3.