JP6519583B2 - Liquid crystal aligning agent containing polyamic acid ester-polyamic acid copolymer, and liquid crystal aligning film using the same - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent containing a polyamic acid ester-polyamic acid copolymer, and a liquid crystal alignment film using the same.

  In a liquid crystal display element used for a liquid crystal television, a liquid crystal display or the like, a liquid crystal alignment film for controlling the alignment state of liquid crystal is usually provided in the element. The liquid crystal alignment film is a film for controlling the alignment of liquid crystal molecules in a predetermined direction in a liquid crystal display element, a retardation plate using a polymerizable liquid crystal, or the like. For example, the liquid crystal display element has a structure in which liquid crystal molecules forming a liquid crystal layer are sandwiched between liquid crystal alignment films formed on the surfaces of a pair of substrates. Then, in the liquid crystal display element, liquid crystal molecules are aligned in a predetermined direction with a pretilt angle by the liquid crystal alignment film, and respond by applying a voltage to an electrode provided between the substrate and the liquid crystal alignment film. As a result, the liquid crystal display element displays a desired image by using the change in alignment due to the response of liquid crystal molecules.

As the liquid crystal alignment film, a polyimide-based liquid crystal alignment film obtained by applying and baking a liquid crystal alignment agent containing a solution of polyimide precursor such as polyamic acid (polyamide acid) or soluble polyimide as a main component It is used.
In addition to the excellent liquid crystal alignment and the expression of a stable pretilt angle, the liquid crystal alignment film has a high level because liquid crystal display elements are required to suppress a drop in contrast and to reduce an afterimage phenomenon along with high definition of liquid crystal display elements. Characteristics such as voltage holding ratio, small residual charge when applying DC voltage, and / or quick relaxation of accumulated residual charge by DC voltage are becoming increasingly important.

  Various proposals have been made for polyimide liquid crystal alignment films in order to meet the above-mentioned requirements. For example, a liquid crystal alignment film containing a tertiary amine of a specific structure in addition to the polyamic acid and the imide group-containing polyamic acid as a liquid crystal alignment film having a short time until the residual image generated by the direct current voltage disappears Patent Document 1), and those using a liquid crystal aligning agent containing a soluble polyimide using a specific diamine compound having a pyridine skeleton or the like as a raw material (see, for example, Patent Document 2) have been proposed. Also, as a liquid crystal alignment film with high voltage holding ratio and short time until residual image generated by DC voltage disappears, in addition to polyamic acid and its imidized polymer etc., one carboxylic acid group in the molecule A liquid crystal aligning agent containing a very small amount of a compound selected from a compound containing, a compound containing one carboxylic acid anhydride group in the molecule, and a compound containing one tertiary amino group in the molecule A thing (for example, refer patent document 3) is proposed.

  In addition, as a liquid crystal alignment film having excellent liquid crystal alignment, high voltage holding ratio, low afterimage, excellent reliability, and high pretilt angle, tetracarboxylic acid having tetracarboxylic acid dianhydride having a specific structure and cyclobutane is mentioned. What used the liquid crystal aligning agent containing the polyamic acid obtained from a dianhydride and a specific diamine compound, and its imidation polymer (for example, refer patent document 4) is known. In addition, as a method of suppressing an afterimage caused by AC drive generated in a liquid crystal display element driven by a lateral electric field drive method, a method of using a specific liquid crystal alignment film having good liquid crystal alignment and large interaction with liquid crystal molecules Reference 5) has been proposed.

In addition to the above, in recent years, a liquid crystal television with a large screen and high definition is mainly used, and a demand for an afterimage becomes more severe, and a characteristic that can withstand long-term use in a severe environment is required. Along with this, the liquid crystal alignment film to be used is required to be more reliable than the conventional one. With respect to various properties of the liquid crystal alignment film, it is also required to maintain good properties, for example, after being exposed to a high temperature for a long time, as well as having good initial properties.
On the other hand, polyamic acid ester is highly reliable as a polymer component constituting a polyimide-based liquid crystal aligning agent, and the heat treatment for imidizing this does not cause a molecular weight decrease, so that the alignment stability of liquid crystal It has been reported that the reliability is excellent (see Patent Document 6). However, polyamic acid esters generally have problems such as high volume resistivity and slow relaxation of residual charge accumulated by DC voltage.

Japanese Patent Laid-Open No. 9-316200 Japanese Patent Application Laid-Open No. 10-104633 Japanese Patent Application Laid-Open No. 8-76128 Japanese Patent Application Laid-Open No. 9-138414 Japanese Patent Laid-Open No. 11-38415 Japanese Patent Application Laid-Open No. 2003-26918

  Polyamic acid ester and polyamic acid with a high relaxation rate of residual charge as a means to improve the disadvantages such as late relaxation of residual charge while maintaining the alignment stability and high reliability of liquid crystal which is an advantage of polyamic acid ester It was examined to use a liquid crystal aligning agent obtained by blending with a liquid crystal display device having a liquid crystal alignment film obtained by using such a blend type liquid crystal aligning agent, but there is a problem in the liquid crystal alignment during long-term driving. Was confirmed.

As a result of analyzing the above problems, it was found that fine asperities were formed on the surface of the liquid crystal alignment film, and the fine asperities caused a decrease in the liquid crystal alignment.
The present invention improves the flatness of the liquid crystal alignment film obtained from the blend type liquid crystal aligning agent of a polyamic acid ester and a polyamic acid, thereby achieving good liquid crystal alignment and voltage holding ratio (hereinafter referred to as VHR). It is an object of the present invention to provide a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film having a high storage DC relaxation rate in addition to the aging resistance.

The inventors of the present invention conducted intensive studies and found that the compatibility between the polyamic acid ester component and the polyamic acid component is low as a cause of the occurrence of irregularities on the surface of the liquid crystal alignment film obtained using the above-mentioned blend type liquid crystal aligning agent. Found out. Therefore, as a means for improving the unevenness of the film surface, a copolymer of polyamic acid ester and polyamic acid (hereinafter also referred to as PAE-PAA copolymer) and polyamic acid ester or polyamic acid are mixed. It has been found that the flatness of the liquid crystal alignment film is improved while maintaining the advantages of the blend-based liquid crystal alignment agent.
That is, the present inventor is a liquid crystal aligning agent containing a polyamic acid ester and a polyamic acid by using a PAE-PAA copolymer, which is a liquid crystal aligning property, aging resistance of voltage holding ratio and relaxation rate of residual charge. It has been found that a liquid crystal alignment film is obtained in which all of the above points are good and the occurrence of fine irregularities on the surface of the liquid crystal alignment film is significantly reduced.

（但し、Ｘ_１及びＸ₂は、それぞれ独立して４価の有機基であり、Ｙ_１及びＹ_２は、それぞれ独立して、２価の有機基であり、Ｒ_１は、炭素数１〜５のアルキル基であり、Ａ_１及びＡ_２は、それぞれ独立して、水素原子、又は置換基を有してもよい、炭素数１〜１０のアルキル基、炭素数２〜１０のアルケニル基若しくは炭素数２〜１０のアルキニル基である。）
成分（Ｂ）：下記式（３）で表される構造単位を有するポリイミド前駆体及び該ポリイミド前駆体のイミド化重合体からなる群より選ばれる少なくとも１種の重合体。

（但し、Ｘ_３は４価の有機基であり、Ｙ_３は２価の有機基であり、Ｒ_２は水素原子又は炭素数１〜５のアルキル基であり、Ｚ_１及びＺ_２は、それぞれ独立して、水素原子、又は置換基を有してもよい、炭素数１〜１０のアルキル基、炭素数２〜１０のアルケニル基若しくは炭素数２〜１０のアルキニル基である。）The present invention is based on the above-described findings, and has the following 1 to 10 as its gist.
1. The liquid crystal aligning agent characterized by containing the following component (A) and a component (B).
Component (A): A copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

(However, X ₁ and X ₂ are each independently a tetravalent organic group, Y ₁ and Y ₂ are each independently a divalent organic group, and R ₁ is a group having 1 to 1 carbon atoms. And each of A ₁ and A ₂ independently represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, which may have a substituent, or It is a C2-C10 alkynyl group.)
Component (B): at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (3) and an imidized polymer of the polyimide precursor.

(However, X ₃ is a tetravalent organic group, Y ₃ is a divalent organic group, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Z ₁ and Z ₂ are each Independently, it is a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms which may have a substituent.

2. The liquid crystal aligning agent according to the above 1, wherein the polyimide precursor of the component (B) is a polyamic acid.
3. The liquid crystal aligning agent according to the above 1, wherein the polyimide precursor of the component (B) is a polyamic acid ester.
4. The said copolymer has 20-80 mol% of structural units represented by Formula (1) with respect to all the structural units which it has, and 80-20 mol% of structural units represented by Formula (2) The liquid crystal aligning agent in any one of said 1-3 having.
5. 5. Liquid crystal aligning agent in any one of said 1-4 whose content of the said component (A) and the said component (B) is 1/9-9/1 by mass ratio.
6. Furthermore, the organic solvent is contained and the total content of the said component (A) and the said component (B) is 0.5-15 mass% with respect to this organic solvent in any one of said 1-5 which is Liquid crystal aligning agent.
7. X _1, X ₂ and X ₃ are each independently a liquid crystal aligning agent according to any one of the above 1 to 6 is at least one selected from the group consisting of structures represented by the following formula.

９．上記１〜８のいずれかに記載の液晶配向剤を塗布、焼成して得られることを特徴とする液晶配向膜。
１０．上記９に記載の液晶配向膜を有することを特徴とする液晶表示素子。8. Y _1, Y ₂ and Y ₃ are each independently a liquid crystal aligning agent according to any one of the above 1 to 7 is at least one selected from the group consisting of structures represented by the following formula.

9. 9. A liquid crystal alignment film obtained by applying and baking the liquid crystal alignment agent according to any one of the above 1 to 8.
10. 9. A liquid crystal display device having the liquid crystal alignment film as described in 9 above.

According to the present invention, there is provided a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film which exhibits good flatness and aging resistance of voltage holding ratio, has a high accumulation DC relaxation rate, and little decrease in liquid crystal alignment due to long-term driving. Be done.
In the liquid crystal aligning agent of the present invention, it is not always clear whether the unevenness generated on the surface of the liquid crystal alignment film obtained can be suppressed by blending the PAE-PAA copolymer and the polyamic acid or polyamic acid ester, It is estimated as follows.
By making the composition of the two components to be blended closer, the compatibility of the two components is considered to be able to suppress the occurrence of surface irregularities. On the other hand, it is thought that good liquid crystal alignment, aging resistance of voltage holding ratio and relaxation rate of residual charge can be obtained by keeping the two components completely mixed and separated in the film to some extent.
The liquid crystal alignment film of the present invention has a liquid crystal alignment property and a component having good VHR aging resistance, and the accumulated DC relaxation speed is distributed on the substrate side on the film surface side of the liquid crystal alignment film. It becomes possible to provide an alignment film.

  Hereinafter, a polyamic acid ester-polyamic acid copolymer (PAE-PAA copolymer) which is a component (A) which can be contained in the liquid crystal aligning agent of the present invention, and a polyimide precursor (polyamic acid) which is a component (B) The ester or polyamic acid will be described. And the liquid crystal aligning agent of this invention comprised by containing them, and a liquid crystal display element are also demonstrated.

<Component (A): PAE-PAA copolymer>
The PAE-PAA copolymer used in the present invention is a polyimide precursor for obtaining a polyimide, and is a polymer having a site capable of the imidization reaction shown below by heating.

（Ｒ_１は式（１）におけるＲ_１と同じである。）
本発明の液晶配向剤に含有されるＰＡＥ-ＰＡＡ共重合体は、下記式（１）で表される構造単位と、下記式（２）で表される構造単位とを有する。

_{(R 1} is the same as _{R 1} in Formula (1).)
The PAE-PAA copolymer contained in the liquid crystal aligning agent of the present invention has a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

In the above formula (1), R ₁ is an alkyl group having 1 to 5 carbon atoms, and is preferably a methyl group or an ethyl group from the viewpoint of wettability to a glass substrate.
In the above formulas (1) and (2), each of A ₁ and A ₂ independently represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl having 2 to 10 carbon atoms Or an alkynyl group having 2 to 10 carbon atoms.
Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, t-butyl group, hexyl group, octyl group, decyl group, cyclopentyl group, cyclohexyl group and bicyclohexyl group.
Examples of the alkenyl group include those in which one or more CH ₂ —CH ₂ structures present in the above alkyl group are replaced by a CH = CH structure, and more specifically, a vinyl group, an allyl group, 1— Propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group and the like.
Examples of the alkynyl group include those in which one or more CH ₂ -CH ₂ structures present in the above alkyl group are replaced by a C≡C structure, and more specifically, ethynyl group, 1-propynyl group, 2 -Propynyl group etc. are mentioned.
The alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms and the alkynyl group having 2 to 10 carbon atoms may have a substituent, and further, a ring structure is formed by the substituent It is also good. In addition, forming a ring structure by a substituent means that substituents form each other or a part of a substituent and a mother skeleton are combined to form a ring structure.

Examples of the substituent include a halogen group, a hydroxyl group, a thiol group, a nitro group, an aryl group, an organooxy group, an organothio group, an organosilyl group, an acyl group, an ester group, a thioester group, a phosphate group, an amide group An alkyl group, an alkenyl group, an alkynyl group etc. can be mentioned.
As a halogen group which is a substituent, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom is mentioned.
The aryl group which is a substituent includes a phenyl group. This aryl group may be further substituted by the other substituent described above.

  As the organooxy group which is a substituent, a structure represented by -O-R can be shown. The R may be the same or different and can be exemplified by the alkyl group, the alkenyl group, the alkynyl group and the aryl group described above. The substituent mentioned above may further substitute by these R. Specific examples of the organooxy group include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.

  As the organothio group which is a substituent, a structure represented by -S-R can be shown. As this R, the above-mentioned alkyl group, an alkenyl group, an alkynyl group, an aryl group etc. can be illustrated. The substituent mentioned above may further substitute by these R. Specific examples of the organothio group include methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, octylthio and the like.

As an organosilyl group which is a substituent, a structure represented by -Si- (R) ₃ can be shown. The R may be the same or different and can be exemplified by the alkyl group, the alkenyl group, the alkynyl group, the aryl group and the like described above. The substituent mentioned above may further substitute by these R. Specific examples of the organosilyl group include trimethylsilyl group, triethylsilyl group, tripropylsilyl group, tributylsilyl group, tripentylsilyl group, trihexylsilyl group, pentyldimethylsilyl group, hexyldimethylsilyl group and the like.

  As an acyl group which is a substituent, the structure represented by -C (O) -R can be shown. As this R, the alkyl group mentioned above, an alkenyl group, an aryl group etc. can be illustrated. The substituent mentioned above may further substitute by these R. Specific examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoyl group and the like.

As a substituted ester group, a structure represented by -C (O) O-R or OC (O) -R can be shown. As this R, the above-mentioned alkyl group, an alkenyl group, an alkynyl group, an aryl group etc. can be illustrated. The substituent mentioned above may further substitute by these R.
As a thioester group which is a substituent, the structure represented by -C (S) O-R or -OC (S) -R can be shown. As this R, the above-mentioned alkyl group, an alkenyl group, an alkynyl group, an aryl group etc. can be illustrated. The substituent mentioned above may further substitute by these R.

As a phosphate ester group which is a substituent, the structure represented by -OP (O)-(OR) ₂ can be shown. The R may be the same or different and can be exemplified by the alkyl group, the alkenyl group, the alkynyl group, the aryl group and the like described above. The substituent mentioned above may further substitute by these R.
As an amido group which is a substituent, —C (O) NH ₂ , —C (O) NHR, —NHC (O) R, —C (O) N (R) ₂ or —NRC (O) R The structure represented can be shown. The R may be the same or different and can be exemplified by the alkyl group, the alkenyl group, the alkynyl group and the aryl group described above. The substituent mentioned above may further substitute by these R.

As an aryl group which is a substituent, the same thing as the aryl group mentioned above can be mentioned. This aryl group may be further substituted by the other substituent described above.
As an alkyl group which is a substituent, the same thing as the alkyl group mentioned above can be mentioned. This alkyl group may be further substituted with the other substituent described above.
As an alkenyl group which is a substituent, the same thing as the alkenyl group mentioned above can be mentioned. This alkenyl group may be further substituted with the other substituent described above.
As an alkynyl group which is a substituent, the same thing as the alkynyl group mentioned above can be mentioned. The above-mentioned other substituents may be further substituted on this alkynyl group.

Generally, introducing a bulky structure may lower the reactivity of the amino group and the liquid crystal alignment, and therefore, as A ₁ and A ₂ , a hydrogen atom or a carbon number of 1 which may have a substituent The alkyl group of 5 is more preferable, and a hydrogen atom, a methyl group or an ethyl group is particularly preferable.

In the above formulas (1) and (2), as long as X ₁ and X ₂ are tetravalent organic groups, the structure is not particularly limited, and two or more types may be mixed. If Specific examples of X ₁ and _{X 2,} include X-1 to X-47 shown below. Among them, from the availability of the monomer, X ₁ is X-1, X-2, X-3, X-4, X-5, X-6, X-8, X-16, X-19, X -21, X-25, X-26, X-27, X-28, X-32 or X-47 are preferred.

Further, in the equation (1) and (2), _{Y 1} and _{Y 2} is a divalent organic group, is not particularly limited. Y ₁ and Y ₂ may be the same or different.
Specific examples of Y ₁ and Y ₂ include the following Y- _{1 to} Y-99. Among them, from the viewpoint of availability of monomers, Y-7, Y-8, Y-20, Y-21, Y-22, Y-28, Y-29, Y-29, Y-30, Y-31, Y- 41, Y-43, Y-64, Y-65, Y-66, Y-68, Y-71, Y-72, Y-98 or Y-99 is preferable, Y-22, Y-28, Y- 30, Y-31, Y-72, Y-98 or Y-99 is more preferred.

In the above-mentioned PAE-PAA copolymer, the proportion of the structural unit represented by the formula (1) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, based on all structural units.
In the above-mentioned PAE-PAA copolymer, the proportion of the structural unit represented by the formula (2) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, based on all structural units.

<Production Method of PAE-PAA Copolymer>
The PAE-PAA copolymer of the present invention is produced by the following method.
In the structural unit represented by the above formula (1), a tetracarboxylic acid diester which forms X ₁ , and a diamine which forms Y ₁ and Y ₂ in the above (1) and the formula (2) are condensed agents, In the presence of a base and an organic solvent, a polycondensation reaction is carried out at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 12 hours, and then the base is neutralized. Diphenyl phosphate is added for the purpose, tetracarboxylic acid or its dianhydride forming X ₂ is added in the structural unit represented by the above formula (2), and the temperature is 0 ° C. to 50 ° C. It is produced by further reacting for 24 minutes, preferably 1 to 12 hours.

From the solubility of monomers and polymers, the organic solvent used for the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone or the like, and these may be used alone or in combination of two or more. You may use it. The concentration of the polymer is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight polymer is easily obtained.
Examples of the condensing agent include triphenyl phosphite, dicyclohexyl carbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triadidi. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N And N ', N'-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate and the like can be used. It is preferable that the addition amount of a condensing agent is 2-3 times mole with respect to tetracarboxylic-acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base added is preferably 2 to 4 moles per mole of the diamine component from the viewpoint of easy removal and easy to obtain a high molecular weight product.
The PAE-PAA copolymer obtained as described above can be recovered by precipitating the polymer by injecting the reaction solution into a poor solvent while well stirring it. Further, precipitation may be carried out several times, and after washing with a poor solvent, drying at room temperature or under heating may yield a powder of purified PAE-PAA copolymer. The poor solvent is not particularly limited, and water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene and the like can be mentioned.

<Component (B): Polyimide Precursor: Polyamic Acid Ester or Polyamic Acid>
The component (B) contained in the liquid crystal aligning agent of this invention is a polyimide precursor, and has a structural unit represented by following formula (3).

In the above formula (3), _{R 2} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. When the component (B) is a polyamic acid ester, the coating property of the polyamic acid ester on the glass substrate decreases as the carbon number in the alkyl group increases, so that R ₂ is a methyl group or It is preferably an ethyl group.

In the above formula (3), Z ₁ and Z ₂ each independently represent a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or carbon optionally having a substituent. It is an alkynyl group of several 2-10. The alkyl group having 1 to 10 carbon atoms, specific examples of the alkynyl group an alkenyl group or a C2-10 C2-10 may include the same as the specific examples of the A ₁ and A ₂ .

  The alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms and the alkynyl group having 2 to 10 carbon atoms may have a substituent, and further, a ring structure is formed by the substituent It is also good. In addition, forming a ring structure by a substituent means that substituents form each other or a part of a substituent and a mother skeleton are combined to form a ring structure.

Examples of the substituent group include the same as specific examples of substituents in the A ₁ and A _2.
In the above formula (3), X ₃ is not particularly limited as long as it is a tetravalent organic group. Specific examples of X _3, may include the same as the specific examples of the X ₁ and X _2.
As long as Y ₃ in the above formula (3) is a divalent organic group, it is not particularly limited. Specific examples of Y _3, may include the same as the specific examples of the Y ₁ and Y _2.

<Method for Producing Component (B): Polyamic Acid>
When component (B) is a polyamic acid, the polyamic acid is produced by the following method.
In the structural unit represented by the above formula (3), a tetracarboxylic acid forming X ₃ or a dianhydride thereof and a diamine forming Y ₃ in the presence of an organic solvent at −20 ° C. to 150 ° C. C., preferably at 0.degree. C. to 50.degree. C., for 30 minutes to 24 hours, preferably 1 to 12 hours.
From the solubility of monomers and polymers, the organic solvent used for the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone or the like, and these may be used alone or in combination of two or more. You may use it. The concentration of the polymer is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight polymer is easily obtained.
The polyamic acid obtained as described above can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while well stirring it. Further, precipitation is carried out several times, and after washing with a poor solvent, the powder of purified polyamic acid can be obtained by normal temperature or heat drying. The poor solvent is not particularly limited, and water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene and the like can be mentioned.

<Method for Producing Component (B): Polyamic Acid Ester>
When component (B) is a polyamic acid ester, the polyamic acid ester is produced by the following method.
(1) When manufactured from polyamic acid Polyamic acid ester can be manufactured by esterifying the polyamic acid manufactured as mentioned above. Specifically, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours It can be manufactured by

  As the esterifying agent, those which can be easily removed by purification are preferable, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide Dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -Tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents with respect to 1 mole of the repeating unit of the polyamic acid.

  As the organic solvent, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl- And imidazolidinone. In addition, when the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, or 4-hydroxy-4-methyl-2-pentanone can be used.

  These solvents may be used alone or in combination. Furthermore, even if it is a solvent which does not dissolve a polyimide precursor, it may be used by mixing with the above-mentioned solvent in the range which the generated polyimide precursor does not precipitate. Further, since water in the solvent inhibits the polymerization reaction and causes hydrolysis of the formed polyimide precursor, it is preferable to use the solvent which has been dehydrated and dried.

The solvent used for the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the polymer, and one or more of these may be used as a mixture. Good.
The polymer concentration at the time of production is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer hardly occurs and a polymer can be easily obtained.

(2) When manufactured by reaction of tetracarboxylic acid diester dichloride and diamine Polyamic acid ester forms Y ₃ with tetracarboxylic acid dichloride which forms X ₃ in the structural unit represented by the above formula (3) The reaction is carried out by reacting the corresponding diamine with a base and an organic solvent at -20.degree. C. to 150.degree. C., preferably 0.degree. C. to 50.degree. C., for 30 minutes to 24 hours, preferably 1 to 4 hours. it can.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds mildly. The amount of the base added is preferably 2 to 4 moles, per mole of the tetracarboxylic acid diester dichloride, from the viewpoint of easy removal and high molecular weight.
The solvent used for the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of monomers and polymers, and one or more of these may be used as a mixture.
The polymer concentration at the time of production is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer hardly occurs and a polymer can be easily obtained. Further, in order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for producing the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent external air from being mixed in a nitrogen atmosphere.

(3) In the case of producing from tetracarboxylic acid diester and diamine: The polyamic acid ester is a structural unit represented by the above formula (3), which is a tetracarboxylic acid diester forming X ₃ and a diamine forming Y ₃ C. for 30 minutes to 24 hours, preferably 3 to 15 hours, at 0.degree. C. to 150.degree. C., preferably 0.degree. C. to 100.degree. C., in the presence of a condensing agent, a base and an organic solvent. .
Examples of the condensing agent include triphenyl phosphite, dicyclohexyl carbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triadidi. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N And N ', N'-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate and the like can be used. The addition amount of the condensing agent is preferably 2 to 3 moles per mol of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base added is preferably 2 to 4 moles per mole of the diamine component, in terms of easy removal and high molecular weight.
In the above reaction, addition of a Lewis acid as an additive allows the reaction to proceed efficiently. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0 times the molar amount with respect to the diamine component.

Among the three polyamic acid ester production methods, the high molecular weight polyamic acid ester can be obtained with good reproducibility, and therefore the production method (3) is particularly preferable.
The solution of the polyamic acid ester obtained as described above can precipitate the polymer by pouring it into a poor solvent while stirring well. Precipitation is carried out several times, and after washing with a poor solvent, normal temperature or heat drying can be carried out to obtain a powder of purified polyamic acid ester. The poor solvent is not particularly limited, and water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene and the like can be mentioned.

<Liquid crystal alignment agent>
The content of the component (A) and the content of the component (B) in the liquid crystal aligning agent of the present invention is preferably 1/9 to 9/1 by mass ratio, more preferably 2/8 to 8 It is 8/2.
The liquid crystal aligning agent of this invention contains the polyamic acid ester or polyamic acid represented by Formula (3) as a component (B).
When component (B) is a polyamic acid ester, the weight average molecular weight of the polyamic acid ester is preferably 5,000 to 300,000, more preferably 10,000 to 200,000. Also, the number average molecular weight is preferably 2,500 to 150,000, more preferably 5,000 to 30,000.
When component (B) is a polyamic acid, the weight average molecular weight of the polyamic acid is preferably 10,000 to 305,000, and more preferably 20,000 to 210,000. Also, the number average molecular weight is preferably 5,000 to 152,500, more preferably 10,000 to 105,000.

The liquid crystal aligning agent of the present invention is in the form of a solution in which the above-mentioned PAE-PAA copolymer and polyamic acid ester or polyamic acid are dissolved in an organic solvent. When each component is synthesized in an organic solvent, it may be the reaction solution obtained as it is, or may be one obtained by diluting this reaction solution with another solvent as appropriate. When each component is obtained as a powder, it may be dissolved in an organic solvent to form a solution.
The content (concentration) of the polymer component in the liquid crystal aligning agent of the present invention can be appropriately changed also by setting the thickness of the polyimide film to be formed, but a point that a uniform and defect-free coating film is formed From the viewpoint of the organic solvent, the content of the polymer component is preferably 0.5% by mass or more, and preferably 15% by mass or less, more preferably 1 to 10% by mass from the viewpoint of solution storage stability. is there. In this case, a concentrated solution of the polymer may be prepared in advance, and the concentrated solution may be diluted to be a liquid crystal aligning agent. 10-30 mass% is preferable, and, as for the density | concentration of the concentrated solution of this polymer component, 10-15 mass% is more preferable. Alternatively, the powder of the polymer component may be dissolved in an organic solvent to produce a solution, which may be heated. The heating temperature is preferably 20 ° C to 150 ° C, and particularly preferably 20 ° C to 80 ° C.

  The said organic solvent contained in the liquid crystal aligning agent of this invention will not be specifically limited if a polymer component melt | dissolves uniformly. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropanamide and the like can be mentioned. These may be used alone or in combination of two or more. Moreover, even if it is a solvent which can not melt | dissolve a polymer component uniformly by itself, as long as a polymer does not precipitate, you may mix with said organic solvent.

  The liquid crystal aligning agent of this invention may contain the solvent for improving the coating-film uniformity at the time of apply | coating a liquid crystal aligning agent to a board | substrate other than the organic solvent for dissolving a polymer component. As such a solvent, a solvent having a surface tension lower than that of the organic solvent is generally used. Specific examples thereof include ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1- Butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate Propylene glycol, 2- (2-ethoxypropoxy) propanol, lactic acid methyl ester, lactic acid ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid Isoamyl ester, and the like. Two or more of these solvents may be used in combination.

The liquid crystal aligning agent of the present invention is, besides the above, a compound which improves the film thickness uniformity and surface smoothness when the liquid crystal aligning agent is applied, as long as the effects of the present invention are not impaired, and a silane coupling agent You may contain various additives, such as a crosslinking agent.
Examples of the compound for improving the uniformity of the film thickness and the surface smoothness include fluorine-based surfactants, silicone-based surfactants, nonion-based surfactants and the like.
More specifically, for example, F-Top (registered trademark) EF301, EF303, EF352 (manufactured by Tochem Products), Megafuck (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink and Chemicals, Inc.), Florard FC430, FC431 (made by Sumitomo 3M), Asahi Guard (trademark) AG710, Surflon (trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (made by Asahi Glass Co., Ltd.) etc. are mentioned.

The proportion of these surfactants used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 parts by mass, with respect to 100 parts by mass of the resin component contained in the liquid crystal aligning agent.
The silane coupling agent is added for the purpose of improving the adhesion between the substrate on which the liquid crystal aligning agent is applied and the liquid crystal alignment film formed thereon, and, for example, the compounds are listed below as specific examples. Although it is not limited to these.

  3-Aminopropyltriethoxysilane, 3- (2-Aminoethyl) aminopropyltrimethoxysilane, 3- (2-Aminoethyl) aminopropylmethyldimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-phenylaminopropyltrithiol Amine based silane coupling agents such as methoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, 3-aminopropyldiethoxymethylsilane, etc .; vinyltrimethoxysilane, vinyltriethoxysilane, Vinyl-based silane coupling compounds such as vinyltris (2-methoxyethoxy) silane, vinylmethyldimethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane and p-styryltrimethoxysilane Agents; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-) Epoxy-based silane coupling agents such as epoxycyclohexyl) ethyltrimethoxysilane; 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrithiol Methacrylic silane coupling agents such as ethoxysilane; acrylic silane coupling agents such as 3-acryloxypropyltrimethoxysilane; ureido silane cups such as 3-ureidopropyltriethoxysilane Sulfide-based silane coupling agents such as bis (3- (triethoxysilyl) propyl) disulfide and bis (3- (triethoxysilyl) propyl) tetrasulfide; 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyl Mercapto-based silane coupling agents such as trimethoxysilane and 3-octanoylthio-1-propyltriethoxysilane; isocyanate-based silane coupling agents such as 3-isocyanate propyltriethoxysilane and 3-isocyanate propyltrimethoxysilane; triethoxysilyl Aldehyde type silane coupling agents such as butyraldehyde; Carba such as triethoxy silyl propyl methyl carbamate, (3-triethoxy silyl propyl) -t-butyl carbamate Mate based silane coupling agent.

If the amount of the silane coupling agent added is too large, unreacted ones may adversely affect the liquid crystal alignment, and if too small, no effect on adhesion is exhibited. 0.1 to 5.0% by weight is preferable, and 0.1 to 1.0% by weight is more preferable.
An imidization accelerator may be added to the liquid crystal alignment film of the present invention in order to efficiently advance the imidization of the PAE-PAA copolymer or the polyamic acid ester when the coated film is fired.

<Liquid crystal alignment film>
The liquid crystal aligning agent of the present invention is a film obtained by applying the above-mentioned liquid crystal aligning agent to a substrate, drying it as necessary, and baking it. The substrate to which the liquid crystal aligning agent of the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and, for example, other than a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used. When the liquid crystal aligning agent of the present invention is used in the production of a liquid crystal display element, it is preferable to form a liquid crystal alignment film using a substrate on which an ITO (Indium Tin Oxide) electrode or the like for driving the liquid crystal is formed. In the case of manufacturing a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used if it is only one side of the substrate, and in this case the electrode may be made of a material that reflects light such as aluminum. it can.

  As a method of apply | coating the liquid crystal aligning agent of this invention on a board | substrate, screen printing, offset printing, a flexographic printing, or the inkjet method is mentioned, for example. Other coating methods include dip method, roll coater method, slit coater method, spinner method or spray method, and these may be used according to the purpose.

Usually, in order to fully remove the contained organic solvent, it is made to dry at 50 degreeC-120 degreeC for 1 minute-10 minutes, Then, it bakes at 150 degreeC-300 degreeC for 5 minutes-120 minutes. The thickness of the coated film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be reduced, so it is 5 to 300 nm, preferably 10 to 200 nm.
As a method of carrying out the alignment process of the obtained liquid crystal aligning film, the rubbing method, the photo alignment treatment method, etc. are mentioned.

  The rubbing process of the coating film surface formed on the board | substrate as mentioned above can use the existing rubbing apparatus. Examples of the material of the rubbing cloth at this time include cotton, rayon, nylon and the like. As the conditions for the rubbing treatment, generally, conditions such as a rotational speed of 300 to 2,000 rpm, a feed rate of 5 to 100 mm / s, and a pressing amount of 0.1 to 1.0 mm are used. Thereafter, ultrasonic cleaning using pure water, alcohol or the like removes the residue generated by rubbing.

As a specific example of the light alignment treatment method, a method of irradiating the surface of the coating film with radiation deflected in a certain direction, and in some cases, heating treatment at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability Can be mentioned. As radiation, ultraviolet light and visible light having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable.
Moreover, in order to improve liquid crystal orientation, you may irradiate a radiation, heating a coating film board | substrate at 50-250 degreeC. The dose of radiation is preferably ^{1~10,000mJ / cm 2, 100~5,000mJ / cm} 2 is particularly preferred. The liquid crystal alignment film produced as described above can stably align liquid crystal molecules in a certain direction.

<Liquid crystal display element>
The liquid crystal display element of the present invention is a liquid crystal display element obtained by preparing a liquid crystal alignment film-provided substrate from the liquid crystal aligning agent of the present invention by the above-described method and then manufacturing a liquid crystal cell by a known method.
An example of a method for manufacturing a liquid crystal display element is as follows. First, prepare a pair of substrates on which a liquid crystal alignment film is formed, and sandwich them with a spacer of preferably 1 to 30 μm, more preferably 2 to 10 μm, and an arbitrary angle of 0 ° to 270 ° in the rubbing direction Set up as follows, and fix the surroundings with a sealant. Next, liquid crystal is injected between the substrates and sealed. The liquid crystal sealing method is not particularly limited, and a vacuum method of injecting liquid crystal after reducing the pressure in the produced liquid crystal cell, a dropping method of sealing after dropping liquid crystal, and the like can be exemplified.

The present invention will be described in more detail by way of the following examples. The present invention is not construed as being limited to these.
The structures and abbreviations of main compounds used in Examples and Comparative Examples are as follows.

<Carboxylic acid>
X-1: 2,4-bis (methoxycarbonyl) cyclobutane-1,3-dicarboxylic acid X-2: 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride X-3: pyromellitic dianhydride X-4: 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride

<Diamine>
Y-1: bis (4-aminophenoxy) methane Y-2: 1,2-bis (4-aminophenoxy) ethane Y-3: 1,3-bis (4-aminophenoxy) propane Y-4: 4, 4'-diaminodiphenylamine Y-5: 4- (2- (methylamino) ethyl) aniline Y-6: 1,3-bis (4-aminophenethyl) urea Y-7: 3,5-diaminobenzoic acid <condensed Agent>
DBOP: diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate <silane coupling agent>
Z-1: 3-glycidoxypropyl triethoxysilane

<Structural formula>

Below, it shows about the evaluation method performed by the present Example and the comparative example.
[viscosity]
The viscosity of the polyamic acid solution or polyamic acid ester solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, corn rotor TE-1 (1 ° 34 ', R24), temperature It was measured at 25 ° C.

[Solid content concentration]
Calculation of solid content concentration of a polyamic acid solution or a polyamic acid ester solution was performed as follows.
Approximately 1.1 g of a polyamic acid solution or a polyamic acid ester solution was taken in a hand-held aluminum cup No. 2 (manufactured by As One), and heated at a temperature of 200 ° C. for 2 hours in an oven DNF400 (manufactured by Yamato Scientific Co., Ltd.). Thereafter, it was left at room temperature for 5 minutes, and the weight of the solid content remaining in the aluminum cup was weighed. The solid content concentration was calculated from the solid content weight and the original solution weight value.

[Molecular weight]
The molecular weight of the polyamic acid solution or polyamic acid ester solution is measured by a GPC (normal temperature gel permeation chromatography) apparatus, polyethylene glycol, and a number average molecular weight (hereinafter also referred to as Mn) as a polyethylene oxide equivalent value and a weight average molecular weight (hereinafter referred to as Mn). Hereinafter, it was also called Mw.) Was calculated.
GPC apparatus: manufactured by Shodex (GPC-101)
Column: Shodex (KD 803, KD 805 in series)
Column temperature: 50 ° C
Eluent: N, N-dimethylformamide (as additive, 30 mmol / L of lithium bromide-hydrate (LiBr · H ₂ O), 30 mmol / L of phosphoric acid · anhydrous crystal (o-phosphoric acid), tetrahydrofuran) (THF) 10 ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing a calibration curve: Toso TSK standard polyethylene oxide (weight average molecular weight (Mw): about 900,000, 150,000, 100,000, and 30,000), Polymer laboratory polyethylene glycol (peak top molecular weight (Mp): about 12,000, 4,000, and 1,000). In order to avoid overlapping of the peaks, the measurement was made with four mixed samples of 900,000, 100,000, 12,000 and 1,000, and 3 samples of 150,000, 30,000 and 4,000. Measure two samples of mixed samples separately.

[Flatness of film]
In Examples and Comparative Examples, the flatness of the polyimide film was measured as follows.
Shape image measurement was performed in a dynamic force mode (DFM) using an L-trace apparatus manufactured by SSI Nano Technology. As a cantilever, SI-DF 40 was used, and after first correcting the shape image obtained under the measurement conditions shown below, the value of the average surface roughness was calculated.
Scanning area: 10 × 10 μm
Attenuation rate: -0.128
I gain: 0.0444
P gain: 0.0488
A gain: 10
S gain: 10
Scanning frequency: 2.0 Hz

[Aging tolerance of voltage holding ratio]
Evaluation was performed using the liquid crystal cell produced by the method shown below.
(Preparation of liquid crystal cell)
The liquid crystal aligning agent is filtered with a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried for 5 minutes on a hot plate at 80 ° C., and baked for 30 minutes at 230 ° C. The polyimide film of This polyimide film is rubbed with a rayon cloth (roll diameter 120 mm, rotation speed 1000 rpm, moving speed 20 mm / sec, pushing amount 0.4 mm), then ultrasonic irradiation is performed in pure water for 1 minute, and then at 80 ° C. Dried for 10 minutes.
After preparing two substrates with a liquid crystal alignment film obtained in this way and placing a 4 μm spacer on the liquid crystal alignment film surface of one of the substrates, combine the two substrates so that the rubbing directions become antiparallel. The periphery was sealed leaving a liquid crystal injection port, and an empty cell having a cell gap of 4 μm was fabricated. Liquid crystal (MLC-2041, manufactured by Merck & Co., Ltd.) was vacuum injected into this cell at normal temperature, and the inlet was sealed to form an anti-parallel liquid crystal cell.

[Aging tolerance of voltage holding ratio]
The liquid crystal cell produced by the above method was aged in an oven at 60 ° C. for 48 hours under an LED light source (1000 cd). The voltage holding ratio was measured before and after aging, and in the case of 85% or more before aging and 50% or more after aging, ○, and those not satisfying the above characteristics were x.
(Measurement conditions of voltage holding ratio)
By applying a voltage of 1 V for 60 μs and measuring a voltage after 100 ms, the fluctuation from the initial value was calculated as a voltage holding ratio. The temperature of the liquid crystal cell was measured at 60.degree.

[Accumulated DC relaxation rate] and [Liquid crystal alignment]
Evaluation was performed using the liquid crystal cell produced by the method shown below.
(Preparation of liquid crystal cell)
First, a substrate with an electrode was prepared. The substrate is a glass substrate of 30 mm × 50 mm in size and 0.7 mm in thickness. An ITO electrode provided with a solid pattern is formed on the substrate to form a counter electrode as a first layer. A SiN (silicon nitride) film formed by the CVD method is formed as a second layer on the first opposing electrode. The film thickness of the second SiN film is 500 nm and functions as an interlayer insulating film. A comb-like pixel electrode formed by patterning an ITO film as a third layer is disposed on the second layer SiN film, and two pixels of a first pixel and a second pixel are formed. doing. The size of each pixel is 10 mm in height and about 5 mm in width. At this time, the first opposing electrode and the third pixel electrode are electrically insulated by the action of the second SiN film.

  The pixel electrode of the third layer has a comb-like shape formed by arranging a plurality of V-shaped electrode elements whose central portion is bent. The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is configured by arranging a plurality of bent, V-shaped electrode elements in the central portion, the shape of each pixel is not rectangular, and the central portion is similar to the electrode elements. It has a shape resembling bold letters that bends at. And each pixel is divided up and down bordering on the central bending part, and has the 1st field of the upper part of a bending part, and the 2nd field of the lower side.

  When the first region and the second region of each pixel are compared, the forming directions of the electrode elements of the pixel electrodes constituting them are different. That is, on the basis of the rubbing direction of the liquid crystal alignment film described later, the electrode element of the pixel electrode is formed at an angle of + 10 ° (clockwise) in the first region of the pixel, and the pixel in the second region of the pixel The electrode elements of the electrodes are formed at an angle of -10 ° (clockwise). That is, in the first area and the second area of each pixel, the directions of rotational movement (in-plane switching) in the plane of the substrate of the liquid crystal induced by voltage application between the pixel electrode and the counter electrode are mutually different. It is configured to be in the opposite direction.

  Next, after filtering the obtained liquid crystal aligning agent with a filter with a pore diameter of 1.0 μm, a glass substrate having the prepared electrode-provided substrate and a columnar spacer with a height of 4 μm on which an ITO film is formed on the back surface. , And was applied by spin coating. Subsequently, after drying for 5 minutes on a 100 degreeC hotplate, it baked at 230 degreeC for 20 minutes, and obtained the polyimide film on each board | substrate as a coating film with a film thickness of 60 nm. This polyimide film is rubbed with a rayon cloth (roll diameter 120 mm, rotation speed 500 rpm, moving speed 30 mm / sec, pushing amount 0.3 mm) in a predetermined rubbing direction, and then ultrasonic irradiation in pure water for 1 minute And dried at 80 ° C. for 10 minutes.

  Then, using the two types of substrates with the liquid crystal alignment film, combine them so that the rubbing directions are antiparallel, seal the periphery with the liquid crystal injection port left, and use an empty cell with a cell gap of 3.6 μm. Made. A liquid crystal (MLC-2041, manufactured by Merck & Co., Ltd.) was vacuum injected into this empty cell at normal temperature, and then the inlet was sealed to obtain a liquid crystal cell with anti-parallel alignment. The obtained liquid crystal cell constitutes an FFS mode liquid crystal display element. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, allowed to stand overnight, and used for each evaluation.

[Accumulated DC relaxation rate (afterimage disappearance time)]
The accumulated DC relaxation rate (afterimage disappearance time) was evaluated using the following optical system and the like.
The manufactured liquid crystal cell is placed between two polarizing plates disposed so that the polarization axes are orthogonal to each other, and the LED backlight is turned on with no voltage applied so that the brightness of transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted.
Next, a VT curve (voltage-transmittance curve) was measured while applying an AC voltage of frequency 30 Hz to this liquid crystal cell, and an AC voltage at which the relative transmittance was 23% was calculated as a drive voltage.
In the residual image evaluation, while applying a 30 Hz AC voltage with a relative transmittance of 23% to drive the liquid crystal cell, a DC voltage of 1 V was applied at the same time to drive for 30 minutes. Thereafter, the applied DC voltage value was set to 0 V, only the application of the DC voltage was stopped, and in this state, driving was performed for another 20 minutes.
Afterimage evaluation is performed by defining as ○ when the relative transmittance recovers to 25% or less and as × when it is 25% or more until 20 minutes elapse from the time when the application of the DC voltage is stopped. The Moreover, the residual image evaluation according to the method mentioned above was implemented on the temperature conditions of the state whose temperature of a liquid crystal cell is 23 degreeC.

[Liquid crystal alignment (afterimage evaluation by long-term drive)]
In a constant temperature environment of 60 ° C., an alternating voltage of 100% in relative transmittance at a frequency of 30 Hz was applied for 100 hours. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and left at room temperature for a day.
After standing, the liquid crystal cell is placed between two polarizing plates disposed so that the polarization axes are orthogonal to each other, and the backlight is turned on with no voltage applied to minimize the brightness of transmitted light. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell is rotated from the angle at which the second region of the first pixel is the darkest to the angle at which the first region is the dark is calculated as the angle Δ. Similarly, in the second pixel, the second area and the first area were compared, and the similar angle Δ was calculated. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. The case where the value of the angle Δ of the liquid crystal cell is 0.2 degrees or less is defined as ○, and the case where the value is 0.2 degrees or more as x.

Synthesis Example 1 Polyamic Acid Ester Solution 174.9 g (672.0 mmol) of X-1 was charged into a 5000 mL four-necked flask containing a stirrer, and 3351 g of N-methyl-2-pyrrolidone was added thereto. Stir to dissolve. Next, 148.7 g (1470 mmol) of triethylamine and 180.8 g (700.0 mmol) of Y-3 were added and dissolved by stirring.
While stirring this solution, 563.5 g (1470 mmol) of DBOP was added, 460.4 g of N-methyl-2-pyrrolidone was further added, and the solution was stirred at room temperature for 12 hours to obtain a solution of polyamic acid ester. The viscosity of this polymic acid ester solution at a temperature of 25 ° C. was 61.1 mPa · s.
The polymic acid ester solution was poured into methanol (29280 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 100 ° C. to obtain a powder of polyamic acid ester. The molecular weight of this polyamic acid ester was Mn = 13,400 and Mw = 34,600.
1.77 g of this polyamic acid ester powder was taken in a 100 mL conical flask containing a stirrer, 27.7 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 18 hours for dissolution. Subsequently, 0.02 g of Z-1 and 9.85 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a polyamic acid ester solution having a solid concentration of 4.34% by mass.

Synthesis Example 2 Polyamic Acid Solution In a 100 mL four-necked flask containing a stirrer, 9.56 g (37.0 mmol) of Y-3 was taken, 74.6 g of N-methyl-2-pyrrolidone was added, and nitrogen was added. The mixture was stirred and dissolved while being fed. While stirring this diamine solution, 6.89 g (35.2 mmol) of X-2 was added, and 18.6 g of N-methyl-2-pyrrolidone was further added, and stirring was carried out at 23 ° C. for 5 hours under a nitrogen atmosphere to obtain polyamic. An acid solution was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 436 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 15,400 and Mw = 41,700.
Separate 10.3 g of this polyamic acid solution into a 100 mL Erlenmeyer flask containing a stirrer, add 18.7 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1 and 9.68 g of butyl cellosolve, Stirring with a tick stirrer for 2 hours gave a polyamic acid solution with a solid concentration of 4.00% by mass.

Synthesis Example 3 PAE-PAA Copolymer Solution After charging 3.90 g (15.0 mmol) of X-1 into a 200 mL four-necked flask containing a stirrer, N-methyl-2-pyrrolidone 59. 7 g was added and stirred to dissolve. Next, 3.24 g (32.0 mmol) of triethylamine and 5.17 g (20.0 mmol) of Y-3 were added and dissolved by stirring.
While the solution was being stirred, 11.50 g (30.0 mmol) of DBOP was added, and 12.8 g of N-methyl-2-pyrrolidone was further added, followed by stirring at room temperature for 12 hours. After that, 1.00 g (4.00 mmol) of diphenyl phosphate and 0.94 g (4.80 mmol) of X-2 were added, and then 12.8 g of N-methyl-2-pyrrolidone was added, followed by 12 hours at room temperature. Stirring gave a solution of PAE-PAA copolymer. The viscosity of this polymic acid ester solution at a temperature of 25 ° C. was 36.1 mPa · s.
The polymic acid ester solution was poured into methanol (666 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a powder of PAE-PAA copolymer. The molecular weight of this PAE-PAA copolymer was Mn = 5,900 and Mw = 12,200.
6.16 g of this polyamic acid-polyamic acid ester powder was taken in a 100 mL conical flask containing a stirrer, 65.2 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 18 hours for dissolution. Subsequently, 0.06 g of Z-1 and 23.3 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a polyamic acid-polyamic acid ester solution having a solid concentration of 6.13% by mass.

Synthesis Example 4 PAE-PAA Copolymer Solution 2.47 g (9.50 mmol) of X-1 was charged into a 100 mL four-necked flask containing a stirrer, and then N-methyl-2-pyrrolidone 55. 4 g was added and stirred to dissolve. Next, 2.11 g (20.9 mmol) of triethylamine and 4.91 g (19.0 mmol) of Y-3 were added and dissolved by stirring.
While this solution was stirred, 7.28 g (19.0 mmol) of DBOP was added, and further 11.9 g of N-methyl-2-pyrrolidone was added, followed by stirring at room temperature for 12 hours. Thereafter, 0.95 g (3.80 mmol) of diphenyl phosphate and 1.75 g (8.93 mmol) of X-2 are added, followed by 11.9 g of N-methyl-2-pyrrolidone, and the reaction is carried out at room temperature for 7 hours. Stirring gave a solution of PAE-PAA copolymer. The viscosity of this polymic acid ester solution at a temperature of 25 ° C. was 32.7 mPa · s.
The polymic acid ester solution was poured into methanol (591 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a PAE-PAA copolymer powder. The molecular weight of this PAE-PAA copolymer was Mn = 7,000 and Mw = 13,200.
1.46 g of this polyamic acid-polyamic acid ester powder was taken in a 100 mL conical flask containing a stirrer, 20.4 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 18 hours for dissolution. Subsequently, 0.01 g of Z-1 and 7.3 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a polyamic acid-polyamic acid ester solution having a solid content concentration of 4.60% by mass.

Synthesis Example 5 Polyamic Acid Solution 2.21 g (9.60 mmol) of Y-1 was taken in a 100 mL four-necked flask containing a stirrer, 65.2 g of N-methyl-2-pyrrolidone was added, and nitrogen was added. The mixture was stirred and dissolved while being fed. While this diamine solution was stirred, 2.47 g (8.40 mmol) of X-4 was added, and the mixture was stirred at 23 ° C. for 4 hours under a nitrogen atmosphere. Thereafter, 2.87 g (14.4 mmol) of Y-4 was added and dissolution was confirmed, and then 2.80 g (14.3 mmol) of X-2 was added. Further, 27.95 g of N-methyl-2-pyrrolidone was added and stirred for 30 hours to obtain a polyamic acid solution. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 118 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 15,600 and Mw = 36,800.
16.6 g of this polyamic acid solution is separated into a 100 mL conical flask containing a stirrer, 11.0 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1 and 9.20 g of butyl cellosolve are added, Stirring with a tick stirrer for 2 hours gave a polyamic acid solution with a solid concentration of 4.47% by mass.

Synthesis Example 6 Polyamic Acid Solution In a 100 mL four-necked flask containing a stirrer, 1.80 g (12.0 mmol) of Y-5 was taken, 76.6 g of N-methyl-2-pyrrolidone was added, and nitrogen was added. The mixture was stirred and dissolved while being fed. While stirring this diamine solution, 2.29 g (10.5 mmol) of X-3 was added, and the mixture was stirred at 23 ° C. for 2 hours under a nitrogen atmosphere. Thereafter, 5.37 g (18.0 mmol) of Y-6 was added, and after confirming dissolution, 3.59 g (18.3 mmol) of X-2 was added. Further, 19.1 g of N-methyl-2-pyrrolidone was added and stirred for 4 hours to obtain a polyamic acid solution. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 332 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 16,600 and Mw = 38,000.
13.8 g of this polyamic acid solution is separated into a 100 mL conical flask containing a stirrer, and 13.8 g of N-methyl-2-pyrrolidone, 0.02 g of Z-1 and 9.22 g of butyl cellosolve are added, Stirring with a tick stirrer for 2 hours gave a polyamic acid solution with a solid concentration of 4.50% by mass.

Synthesis Example 7 Polyamic Acid Solution 79.7 g (400 mmol) of Y-4 and 15.2 g (100 mmol) of Y-7 were taken in a 2000 mL four-necked flask containing a stirrer, and N-methyl-2 was obtained. -1403 g of pyrrolidone was added and dissolved by stirring with feeding nitrogen. While stirring this diamine solution, 144.2 g (490 mmol) of X-4 was added, and 350.8 g of N-methyl-2-pyrrolidone was further added, and the solution was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere to obtain a polyamic acid solution Obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 4656 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 11,000 and Mw = 27,100.
93.8 g of this polyamic acid solution is separated into a 200 mL Erlenmeyer flask containing a stirrer, 45.3 g of N-methyl-2-pyrrolidone, 0.11 g of Z-1 and 46.4 g of butyl cellosolve are added, Stirring with a tick stirrer for 2 hours gave a polyamic acid solution with a solid concentration of 6.02% by mass.

Synthesis Example 8 PAE-PAA Copolymer Solution 6.01 g (23.1 mmol) of X-1 was charged into a 200 mL four-necked flask containing a stirrer, and then N-methyl-2-pyrrolidone 114. 3 g was added and stirred to dissolve. Next, 5.10 g (50.4 mmol) of triethylamine, 4.18 g (21.0 mmol) of Y-4 and 4.84 g (21.0 mmol) of Y-1 were added and stirred to dissolve.
While stirring this solution, 17.7 g (46.2 mmol) of DBOP was added, 24.5 g of N-methyl-2-pyrrolidone was further added, and the mixture was stirred at room temperature for 12 hours. Thereafter, 2.10 g (8.40 mmol) of diphenyl phosphate and 3.94 g (18.1 mmol) of X-3 were added, followed by 24.5 g of N-methyl-2-pyrrolidone, and the reaction was carried out for 5 hours at room temperature. Stirring gave a solution of PAE-PAA copolymer. The viscosity of this PAE-PAA copolymer solution at a temperature of 25 ° C. was 47.7 mPa · s.
The PAE-PAA copolymer solution was poured into 2-propanol (1242 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a powder of PAE-PAA copolymer. The molecular weight of this PAE-PAA copolymer was Mn = 8,800 and Mw = 16,300.
1.80 g of this PAE-PAA copolymer powder was taken in a 100 mL conical flask containing a stirrer, 28.2 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 12 hours for dissolution. Subsequently, 0.02 g of Z-1 and 10.0 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid concentration of 4.11% by mass.

Synthesis Example 9 PAE-PAA Copolymer Solution After charging 7.81 g (30.0 mmol) of X-1 into a 200 mL four-necked flask containing a stirrer, N-methyl-2-pyrrolidone 110. 9 g was added and stirred to dissolve. Next, 6.48 g (64.8 mmol) of triethylamine, 3.98 g (20.0 mmol) of Y-4 and 4.89 g (20.0 mmol) of Y-2 were added and dissolved by stirring.
While stirring this solution, 23.0 g (60.0 mmol) of DBOP was added, 23.8 g of N-methyl-2-pyrrolidone was further added, and the mixture was stirred at room temperature for 12 hours. Thereafter, 2.00 g (8.00 mmol) of diphenyl phosphate and 2.01 g (9.20 mmol) of X-3 were added, followed by 23.8 g of N-methyl-2-pyrrolidone, and the reaction was carried out for 5 hours at room temperature. Stirring gave a solution of PAE-PAA copolymer. The viscosity of this PAE-PAA copolymer solution at a temperature of 25 ° C. was 60.9 mPa · s.
The PAE-PAA copolymer solution was poured into 2-propanol (2000 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a powder of PAE-PAA copolymer. The molecular weight of this PAE-PAA copolymer was Mn = 8,400 and Mw = 16,200.
1.81 g of this PAE-PAA copolymer powder was taken in a 100 mL Erlenmeyer flask containing a stirrer, 28.4 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 12 hours for dissolution. Subsequently, 0.02 g of Z-1 and 10.1 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid concentration of 4.09% by mass.

Synthesis Example 10 Solution of PAE-PAA Copolymer Into a 200 mL four-necked flask containing a stirrer, 7.81 g (30.0 mmol) of X-1 was added, and then N-methyl-2-pyrrolidone 112 Add .0g and stir to dissolve. Next, 6.48 g (64.8 mmol) of triethylamine, 3.19 g (16.0 mmol) of Y-4 and 5.86 g (24.0 mmol) of Y-2 were added and dissolved by stirring.
While stirring this solution, 23.0 g (60.0 mmol) of DBOP was added, 24.0 g of N-methyl-2-pyrrolidone was further added, and the mixture was stirred at room temperature for 12 hours. Thereafter, 2.00 g (8.00 mmol) of diphenyl phosphate and 2.01 g (9.20 mmol) of X-3 were added, followed by 24.0 g of N-methyl-2-pyrrolidone, and the reaction was carried out for 5 hours at room temperature. Stirring gave a solution of PAE-PAA copolymer. The viscosity of this PAE-PAA copolymer solution at a temperature of 25 ° C. was 71.4 mPa · s.
The PAE-PAA copolymer solution was poured into 2-propanol (2000 g), and the obtained precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a powder of PAE-PAA copolymer. The molecular weight of this PAE-PAA copolymer was Mn = 8,600 and Mw = 17,700.
1.85 g of this PAE-PAA copolymer powder was taken in a 100 mL conical flask containing a stirrer, 29.0 g of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature for 12 hours for dissolution. Subsequently, 0.02 g of Z-1 and 10.3 g of butyl cellosolve were added, and the mixture was stirred for 2 hours to obtain a PAE-PAA copolymer solution having a solid concentration of 3.96% by mass.

Comparative Example 1
A mixed solution of the polyamic acid ester solution obtained in Synthesis Example 1 and the polyamic acid solution obtained in Synthesis Example 5 at a solid content weight ratio of 50:50 is filtered with a 1.0 μm filter and then transparent. It spin-coated on the glass substrate with an electrode. Then, it was left for 10 minutes on a hot plate at a temperature of 30 ° C., and baked at a temperature of 230 ° C. for 20 minutes to obtain a polyimide film with a film thickness of 100 nm. As a result of measuring the average surface roughness of this polyimide film, it was 7.4 nm. Since the surface of the polyimide film had many irregularities, it was not suitable for producing a liquid crystal cell.

Comparative Example 2
A polyimide film having a thickness of 100 nm was obtained in the same manner as in Comparative Example 1 except that the polyamic acid solution obtained in Synthesis Example 2 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of this polyimide film was 0.4 nm.
After producing a liquid crystal cell by the method described in the above-mentioned [Production of liquid crystal cell], evaluation of [aging resistance of voltage holding ratio], [accumulation DC relaxation rate] and [liquid crystal alignment property] was carried out. The results are shown in Table 2.

Example 1
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in Comparative Example 1 except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of this polyimide film was 0.6 nm.
Moreover, after producing a liquid crystal cell by the method similar to the comparative example 1, evaluation of [aging resistance of voltage holding ratio], [accumulation DC relaxation rate], and [liquid crystal alignment property] was implemented.
The liquid crystal cell was produced by the same method also about the following Examples 2-7, and the same evaluation was performed. The results are summarized in Table 2.

Example 2
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in the comparative example except that the PAE-PAA copolymer solution obtained in Synthesis Example 4 and the polyamic acid solution obtained in Synthesis Example 5 were used. The average surface roughness of this polyimide film was 0.4 nm.

Example 3
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in Comparative Example except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 6 were used. The average surface roughness of this polyimide film was 0.6 nm.

Example 4
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in Comparative Example except that the PAE-PAA copolymer solution obtained in Synthesis Example 3 and the polyamic acid solution obtained in Synthesis Example 7 were used. The average surface roughness of this polyimide film was 0.7 nm.

Example 5
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in the comparative example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 8 were used. The average surface roughness of this polyimide film was 0.2 nm.

Example 6
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in Comparative Example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 9 were used. The average surface roughness of this polyimide film was 0.2 nm.

Example 7
A polyimide film with a film thickness of 100 nm was obtained in the same manner as in the comparative example except that the polyamic acid ester solution obtained in Synthesis Example 1 and the PAE-PAA copolymer solution obtained in Synthesis Example 10 were used. The average surface roughness of this polyimide film was 0.2 nm.

The composition of the liquid crystal aligning agent used in the said Example and comparative example is put together in Table 1, and is shown. The numerical values in parentheses indicate the ratio (molar ratio) of each carboxylic acid or each diamine when two types of carboxylic acids or diamines are used to obtain each component.

As shown in Table 2, it was found that the liquid crystal alignment film formed using the liquid crystal aligning agent of Examples 1 to 7 including the PAE-PAA copolymer was excellent in flatness.
Furthermore, it has been found that the liquid crystal alignment film of the present invention is excellent in the aging resistance of the voltage holding ratio, the time until the residual image generated by the direct current voltage disappears is excellent, and the liquid crystal alignment is also excellent.
On the other hand, the liquid crystal alignment film formed using the liquid crystal alignment agent of Comparative Example 1 lacks flatness, and the liquid crystal alignment film obtained from the liquid crystal alignment agent of Comparative Example 2 has a voltage lower than that of the liquid crystal alignment film of the present invention. It turned out that it is inferior in the aging tolerance of a retention, and a liquid crystal orientation.

  As mentioned above, it turned out that the liquid crystal aligning agent of this invention can form the liquid crystal aligning film which has flatness, the outstanding electrical property, and the favorable liquid crystal aligning property.

The liquid crystal aligning film formed using the liquid crystal aligning agent of this invention has flatness, and has the outstanding voltage retention rate aging tolerance, the accumulation | storage DC relaxation rate, and a favorable liquid crystal aligning property. The liquid crystal aligning agent of the present invention can not only improve the liquid crystal alignment but also improve the electric characteristics such as the voltage holding ratio and the residual DC voltage by being able to reduce fine irregularities on the surface of the liquid crystal alignment film obtained. Ru. As a result, it is widely useful for TN devices, STN devices, TFT liquid crystal devices, and further, vertical alignment liquid crystal display devices and the like.
The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2014-077226 filed on April 3, 2014 are incorporated herein by reference and incorporated as disclosure of the specification of the present invention. It is a thing.

Claims (10)

The liquid crystal aligning agent characterized by containing the following component (A) and a component (B).
Component (A): A copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

(However, X ₁ and X ₂ are each independently a tetravalent organic group, Y ₁ and Y ₂ are each independently a divalent organic group, and R ₁ is a group having 1 to 1 carbon atoms. And each of A ₁ and A ₂ independently represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, which may have a substituent, or It is a C2-C10 alkynyl group.)
Component (B): at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (3) and an imidized polymer of the polyimide precursor.

(However, X ₃ is a tetravalent organic group, Y ₃ is a divalent organic group, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Z ₁ and Z ₂ are each Independently, it is a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms which may have a substituent.   The liquid crystal aligning agent of Claim 1 whose polyimide precursor of the said component (B) is a polyamic acid.   The liquid crystal aligning agent of Claim 1 whose polyimide precursor of the said component (B) is a polyamic acid ester.   The said copolymer has 20-80 mol% of structural units represented by Formula (1) with respect to all the structural units which it has, and 80-20 mol% of structural units represented by Formula (2) The liquid crystal aligning agent in any one of Claims 1-3 which it has.   The content of the said component (A) and the said component (B) is 1/9-9/1 by mass ratio, The liquid crystal aligning agent in any one of Claims 1-4.   Furthermore, the organic solvent is contained, The total content of the said component (A) and the said component (B) is 0.5-15 mass% with respect to this organic solvent, The claim in any one of Claims 1-5. Liquid crystal aligning agent. The liquid crystal aligning agent according to any one of claims 1 to 6, wherein X ₁ , X ₂ and X ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas.

The liquid crystal aligning agent according to any one of claims 1 to 7, wherein Y ₁ , Y ₂ and Y ₃ are each independently at least one selected from the group consisting of structures represented by the following formulas.

  It is obtained by apply | coating and baking the liquid crystal aligning agent in any one of Claims 1-8, The liquid crystal aligning film characterized by the above-mentioned.   A liquid crystal display device having the liquid crystal alignment film according to claim 9.